Revver Collection My Videos

RNA-polymerase-2

Thu, 03 Nov 2005 20:42:49 +0000

RNa polymerase 3D animation (scientific/education video)

RNA-polymerase-3

Thu, 03 Nov 2005 21:35:58 +0000

3D animation of RNA polymerase from bacteriophage

RNA polymerase-part 1

Sat, 05 Nov 2005 11:29:44 +0000

Biochemistry video- RNA polymerase;RNA polymerase in action. The structure includes a very small RNA polymerase that is made by the bacteriophage T7, shown here with blue tubes. A small transcription bubble, composed of two DNA strands and an RNA strand, is bound in the active site. Notice how the two DNA strands form a double helix at the top of the picture. The enzyme separates them in the middle and builds an RNA strand using the DNA on the right. Finally, at the bottom, the two DNA strands come back together.

Vitamin D receptor

Sat, 05 Nov 2005 11:56:11 +0000

Rotating animation of vitamin D receptor Vitamin D deficiency is known to cause several bone diseases, due to insufficient calcium in the bones:

Vitamin D

Wed, 06 Dec 2006 06:05:01 +0000

Vit D and its receptor in low resolution for smaller screens

Vitamin D receptor -1

Wed, 06 Dec 2006 06:26:17 +0000

itamin D refers to a group of fat-soluble prohormones as well as to the metabolites and analogues of these substances. Two major forms of vitamin D are D2 (or ergocalciferol) and D3 or cholecalciferol.[1] Vitamin D3 is produced in skin exposed to sunlight, specifically ultraviolet B radiation. Very few foods are naturally rich in vitamin D, and most vitamin D intake is in the form of fortified products including milk and cereal grains.[1] Vitamin D plays an important role in the maintenance of several organ systems.[2] * Vitamin D regulates the calcium and phosphorus levels in the blood by promoting their absorption from food in the intestines, and by promoting re-absorption of calcium in the kidneys. * Vitamin D promotes bone formation and mineralization and is essential in the development of an intact and strong skeleton. * Vitamin D inhibits parathyroid hormone secretion from the parathyroid gland. * Vitamin D affects the immune system by promoting immunosuppression and anti-tumor activity. Vitamin D deficiency can result from; inadequate intake coupled with inadequate sunlight exposure, disorders that limit its absorption, conditions that impair conversion of vitamin D into active metabolites, such as liver or kidney disorders, or, rarely, by a number of hereditary disorders.[2] Deficiency results in impaired bone mineralization, and leads to bone softening diseases, rickets in children and osteomalacia in adults, and possibly contributes to osteoporosis.[2] ergosterol, lamisterol, made, from, dehydrositosterol, dihydrovitamin, biochemistry, science, cholecalciferol, vitamin, dihydrotachysterol, forms, dehydrocholesterol, ergocalciferol

Vitamin D (2)

Wed, 06 Dec 2006 06:26:17 +0000

ergosterol, lamisterol, made, from, dehydrositosterol, dihydrovitamin, biochemistry, science, cholecalciferol, vitamin, dihydrotachysterol, forms, dehydrocholesterol, ergocalciferol itamin D refers to a group of fat-soluble prohormones as well as to the metabolites and analogues of these substances. Two major forms of vitamin D are D2 (or ergocalciferol) and D3 or cholecalciferol.[1] Vitamin D3 is produced in skin exposed to sunlight, specifically ultraviolet B radiation. Very few foods are naturally rich in vitamin D, and most vitamin D intake is in the form of fortified products including milk and cereal grains.[1] Vitamin D plays an important role in the maintenance of several organ systems.[2] * Vitamin D regulates the calcium and phosphorus levels in the blood by promoting their absorption from food in the intestines, and by promoting re-absorption of calcium in the kidneys. * Vitamin D promotes bone formation and mineralization and is essential in the development of an intact and strong skeleton. * Vitamin D inhibits parathyroid hormone secretion from the parathyroid gland. * Vitamin D affects the immune system by promoting immunosuppression and anti-tumor activity. Vitamin D deficiency can result from; inadequate intake coupled with inadequate sunlight exposure, disorders that limit its absorption, conditions that impair conversion of vitamin D into active metabolites, such as liver or kidney disorders, or, rarely, by a number of hereditary disorders.[2] Deficiency results in impaired bone mineralization, and leads to bone softening diseases, rickets in children and osteomalacia in adults, and possibly contributes to osteoporosis.[2] Contents [hide] * 1 Forms * 2 Biochemistry o 2.1 Synthesis mechanism (form 3) o 2.2 Mechanism of action * 3 Nutrition o 3.1 In food * 4 Diseases caused by deficiency o 4.1 Groups with greater deficiency risk * 5 Overdose * 6 Role in immunoregulation * 7 Role in cancer prevention and recovery * 8 Notes and references * 9 External links

Vitamin D receptor (3)

Wed, 06 Dec 2006 06:26:17 +0000

[edit] Diseases caused by deficiency The isolation of vitamin D and its functional role in rickets was determined by Edward Mellanby between 1918–1920. The 1928 Nobel Prize was awarded to Adolf Windaus, who discovered the steroid, 7-dehydrocholesterol, the precursor of vitamin D. Vitamin D deficiency is known to cause several bone diseases[11] including: * Rickets, a childhood disease characterized by impeded growth, and deformity, of the long bones. * Osteomalacia, a bone-thinning disorder that occurs exclusively in adults and is characterised by proximal muscle weakness and bone fragility. * Osteoporosis, a condition characterized by reduced bone mineral density and increased bone fragility. Vitamin D malnutrition may also be linked to an increased susceptibility to several chronic diseases such as tuberculosis, cancer, chronic pain, several autoimmune diseases, high blood pressure, depression, and seasonal affective disorder.[8] [edit] Groups with greater deficiency risk Vitamin D requirements increase with age and the ability of skin to convert 7-dehydrocholesterol to pre-vitamin D3 decreases. In addition the ability of the kidneys to convert calcidiol to its active form, also decreases with age, prompting the need for increased vitamin D supplementation, in elderly individuals. The Canadian and American Pediatric Associations advise vitamin D supplementation from birth onwards, with 200 IU/day (5 mcg/d) in the south up to 800 IU/day in the north.[1] . While infant formula is generally fortified with vitamin D, breast milk does not contain significant levels of vitamin D, and parents are usually advised to avoid exposing babies to prolonged exposure to sunlight. Therefore, infants who are exclusively breastfed require vitamin D supplements. Liquid "drops" of vitamin D, as a single nutrient or combined with other vitamins, are available in water based or oil-based preparations ("Baby Drops" in North America, or "Vigantol oil" in Europe). Obese individuals may have lower levels of the circulating form of vitamin D, probably due to reduced bioavailability, and are at higher risk of deficiency. Patients with chronic liver disease or intestinal malabsorption may require larger doses of vitamin D (up to 40,000 IU or 1 mg (1000 micrograms) daily). To maintain blood levels of calcium, therapeutic vitamin D doses are sometimes administered (up to 100,000 IU or 2.5 mg daily) to patients who have had their parathyroid glands removed (most commonly renal dialysis patients who have had tertiary hyperparathyroidism, but also patients with primary hyperparathyroidism) or who suffer with hypoparathyroidism.[12] Those who avoid or are not exposed to midday sunshine may also require vitamin D supplements. Although a few minutes of exposure for light-skinned individuals may be all that is required, the dermatology community contends that even a few minutes of unprotected ultraviolet exposure a day increases the risk of skin cancer and causes photoaging of the skin. The use of sunscreen with an sun protection factor (SPF) of 8 inhibits more than 95% of vitamin D production in the skin.[8] To avoid vitamin D deficiency dermatologists recommend supplementation along with sunscreen use. Recent studies showed that, following the successful "Slip-Slop-Slap" health campaign encouraging Australians to cover up when exposed to sunlight to prevent skin cancer, an increased number of Australians and New Zealanders became vitamin D deficient.[13] Ironically, there are indications that vitamin D deficiency may lead to skin cancer.[14] At higher latitudes (above 30°), the decreased angle of the sun's rays, reduced daylight

vitamin D (4)

Wed, 06 Dec 2006 07:02:01 +0000

At higher latitudes, total vitamin D input from sunlight is usually insufficient, especially in the winter. To minimize risk of low vitamin D concentrations, foods such as milk are often fortified with vitamin D2 and/or vitamin D3, typically providing 100 IU per glass.[1] Fortified foods are the major dietary sources of vitamin D. Prior to the fortification of milk products with vitamin D rickets, was a major public health problem. Since the 1930s, milk has been fortified with 10 micrograms (400 IU) of vitamin D per quart, in the United States, where rickets is now uncommon.[8] One cup of vitamin D fortified milk supplies about one-fourth of the official estimated adequate intake of vitamin for adults older than age 50 years. Although milk is often fortified with vitamin D, dairy products made from milk (cheese, yogurt, ice cream, and so forth) are generally not. Only a few foods naturally contain significant amounts of vitamin D, including:[1] * Fish liver oils, such as cod liver oil, 1 Tbs. (15 mL), 1,360 IU * Fatty fish, such as: o Salmon, cooked, 3.5 oz, 360 IU o Mackerel, cooked, 3.5 oz, 345 IU o Sardines, canned in oil, drained, 1.75 oz, 250 IU o Tuna, canned in oil, 3 oz, 200 IU o Eel, cooked, 3.5 oz, 200 IU * One whole egg, 20 IU * Shiitake mushrooms, one of a few natural sources of vegan and kosher vitamin D (in the form of ergosterol vitamin D2) The U.S. Dietary Reference Intake Tolerable Upper Intake Level (UL) of vitamin D for childern and adults is 50 micrograms/day (2000 IU/day). For infants (birth to 12 months) the UL is 25 micrograms/day (1000 IU/day).

Vitamn D chapter 5

Wed, 06 Dec 2006 07:02:01 +0000

Vitamin D lesson 6

Wed, 06 Dec 2006 07:02:01 +0000

The isolation of vitamin D and its functional role in rickets was determined by Edward Mellanby between 1918–1920. The 1928 Nobel Prize was awarded to Adolf Windaus, who discovered the steroid, 7-dehydrocholesterol, the precursor of vitamin D. Vitamin D deficiency is known to cause several bone diseases[11] including: * Rickets, a childhood disease characterized by impeded growth, and deformity, of the long bones. * Osteomalacia, a bone-thinning disorder that occurs exclusively in adults and is characterised by proximal muscle weakness and bone fragility. * Osteoporosis, a condition characterized by reduced bone mineral density and increased bone fragility. Vitamin D malnutrition may also be linked to an increased susceptibility to several chronic diseases such as tuberculosis, cancer, chronic pain, several autoimmune diseases, high blood pressure, depression, and seasonal affective disorder.[8] [edit] Groups with greater deficiency risk At higher latitudes (above 30°), the decreased angle of the sun's rays, reduced daylight hours in winter, and protective clothing worn to guard against cold weather, diminish absorption of sunlight and the production of vitamin D. Because melanin acts like a sun-block, prolonging the time required to generate vitamin D, dark-skinned individuals, in particular, may require extra vitamin D to avoid deficiency. At latitudes below 30° where sunlight and day-length are more consistent, and vitamin D supplementation may not be required.[15] The

Vitamin D 7

Wed, 06 Dec 2006 07:02:01 +0000

Vitamin D requirements increase with age and the ability of skin to convert 7-dehydrocholesterol to pre-vitamin D3 decreases. In addition the ability of the kidneys to convert calcidiol to its active form, also decreases with age, prompting the need for increased vitamin D supplementation, in elderly individuals. The Canadian and American Pediatric Associations advise vitamin D supplementation from birth onwards, with 200 IU/day (5 mcg/d) in the south up to 800 IU/day in the north.[1] . While infant formula is generally fortified with vitamin D, breast milk does not contain significant levels of vitamin D, and parents are usually advised to avoid exposing babies to prolonged exposure to sunlight. Therefore, infants who are exclusively breastfed require vitamin D supplements. Liquid "drops" of vitamin D, as a single nutrient or combined with other vitamins, are available in water based or oil-based preparations ("Baby Drops" in North America, or "Vigantol oil" in Europe). Obese individuals may have lower levels of the circulating form of vitamin D, probably due to reduced bioavailability, and are at higher risk of deficiency. Patients with chronic liver disease or intestinal malabsorption may require larger doses of vitamin D (up to 40,000 IU or 1 mg (1000 micrograms) daily). To maintain blood levels of calcium, therapeutic vitamin D doses are sometimes administered (up to 100,000 IU or 2.5 mg daily) to patients who have had their parathyroid glands removed (most commonly renal dialysis patients who have had tertiary hyperparathyroidism, but also patients with primary hyperparathyroidism) or who suffer with hypoparathyroidism.[12] Those who avoid or are not exposed to midday sunshine may also require vitamin D supplements. Although a few minutes of exposure for light-skinned individuals may be all that is required, the dermatology community contends that even a few minutes of unprotected ultraviolet exposure a day increases the risk of skin cancer and causes photoaging of the skin. The use of sunscreen with an sun protection factor (SPF) of 8 inhibits more than 95% of vitamin D production in the skin.[8] To avoid vitamin D deficiency dermatologists recommend supplementation along with sunscreen use. Recent studies showed that, following the successful "Slip-Slop-Slap" health campaign encouraging Australians to cover up when exposed to sunlight to prevent skin cancer, an increased number of Australians and New Zealanders became vitamin D deficient.[13] Ironically, there are indications that vitamin D deficiency may lead to skin cancer.[14]

Cytochrome p450 - part 1

Wed, 13 Dec 2006 06:19:11 +0000

If you have a headache and take a drug to block the pain, you'll notice that the effects of the drug wear off in a few hours. This happens because you have a powerful detoxification system that finds unusual chemicals, like drugs, and flushes them out of your body. This system fights all sorts of unpleasant chemicals that we eat and breathe, including drugs, poisonous compounds in plants, carcinogens formed during cooking, and environmental pollutants. The cytochrome p450 enzymes are our first line of defense in this chemical battle

The Drug Detox Factory

Wed, 13 Dec 2006 06:40:30 +0000

The cytochrome p450 enzymes find unusual molecules and add oxygen atoms to them. In most cases, this has the effect of making the molecule more soluble in water, and thus, easier to flush out of the body. The added oxygen also provides a ready handle for other detoxifying enzymes to take hold and further modify, and destroy, these toxic molecules. This task of adding oxygen is chemically tricky, and cytochrome p450 enzymes use a powerful molecular tool to perform the reaction: an iron atom in a heme group (described in more detail later). p450 Everywhere Cytochrome p450 enzymes are found in all organisms. Each organism builds several different enzymes, each of which act on a different selection of molecules. Typical bacteria have about 20 different forms and we make about 60. Plants often make hundreds of different forms. This is because plants make unusual pigments and exotic toxins to protect themselves. Many of the reactions needed to make these molecules are performed by specialized cytochrome p450 enzymes. For more information on cytochrome p450 from a genomics persective, take a look at the Protein of the Month at the European Bioinformatics Institute

Valium Detoxification

Wed, 13 Dec 2006 06:55:12 +0000

The molecule shown here is CYP3A4 (the cytochrome p450 that plays the major role in drug detoxification in your body. It has been estimated that this enzyme acts on about half of known drugs. For instance, it modifies the antibiotic erythromycin, shown at the bottom in blue. It also detoxifies such diverse drugs as codeine, diazepam (Valium), paclitaxel (Taxol), and several anti-HIV drugs. In some cases, however, the reaction performed by cytochrome p450 enzymes can cause more harm than good. For example, CYP3A4 is partially responsible for the toxicity of large doses of acetaminophen (Tylenol). The modified form of acetaminophen is dangerously reactive, but it is normally cleared away quickly by other detoxifying enzymes. But with large doses, the reactive intermediate can build up to dangerous levels. Prescriptions and p450 Doctors must be careful to keep the cytochrome p450 enzymes in mind when they prescribe medications. For instance, you may have seen warnings on prescriptions, telling you not to drink grapefruit juice when taking a medication. Grapefruits contain a flavinol molecule that inhibits cytochrome p450 enzymes. This will slow down the detoxification of drugs, which may cause them to have stronger effects than expected by the doctor.

Cytochrome p450 -4

Fri, 15 Dec 2006 04:24:41 +0000

Cytochrome p450 enzymes also play a number of essential roles in the synthesis of normal cellular compounds. For instance, special cytochrome p450 enzymes are built to perform chemical steps in the construction of steroids, vitamins A and D, and lipid-like eicosanoid molecules involved in signaling. The enzyme shown here on the left is a fungal cytochrome p450 that performs a step in sterol synthesis (PDB entry 1ea1). A similar enzyme in our cells is needed for the synthesis of cholesterol. The enzyme complex on the right provides electrons for the reaction

The Factory of Life

Fri, 15 Dec 2006 05:09:41 +0000

The best-studied cytochrome p450 enzyme is a bacterial enzyme that adds oxygen to camphor. Two early structures are shown here. On the left (PDB entry 3cpp) is a structure with camphor and carbon monoxide bound in the active site. The carbon monoxide is an inhibitor that poisons the enzyme. It binds to the iron (large yellowish sphere in the middle of the heme) in the same place as oxygen gas. The cysteine amino acid at the bottom activates the iron. The structure on the right (PDB entry 1noo) shows camphor after the reaction, when an oxygen atom has been added (the other oxygen atom is released during the reaction as a water molecule). Looking through the PDB, you can find dozens of other structures of cytochrome p450cam, showing many different molecules bound in the small active site, and showing many different stages in the reaction. ---- Cytochrome P450 oxidase (abbreviated CYP or CYP450) is a generic term for a large number of evolutionary related oxidative enzymes (EC 1.14) important in animal, plant, and bacterial physiology. Most cytochromes P450 (CYPs) have about 525 amino acids and a heme (hæm) group at the active site. Most animal and plant CYPs have electron transfer protein cofactors, cytochrome P450 reductase and cytochrome b5, and use molecular oxygen (O2) to function, while bacterial CYPs use other protein cofactors to function. CYP homologs have been sequenced from all lineages of life, including mammals, birds, fish, insects, worms, sea squirts, sea urchins, plants, fungi, slime molds, bacteria and archaea. More than 6400 distinct CYP sequences are known and officially named (as of October 2006; see the web site of the P450 Nomenclature Committee for current counts).

Cytochrome p450 superfamily

Fri, 15 Dec 2006 18:33:32 +0000

The name P450 refers to the "pigment at 450 nm", so named for the characteristic Soret peak formed by absorbance of light at wavelengths near 450 nm when the heme iron is reduced (with sodium dithionite) and complexed Animal CYPs are primarily membrane-associated proteins, located either in the inner membrane of mitochondria or in the endoplasmic reticulum of cells. CYPs metabolise thousands of endogenous and exogenous compounds. Most CYPs can metabolize multiple substrates, and many can catalyze multiple reactions, which accounts for their central importance in metabolizing the potentially endless variety of endogenous and exogenous molecules. In the liver, these substrates include drugs and toxic compounds as well as metabolic products such as bilirubin (a breakdown product of hemoglobin). Cytochromes P450 are present in many other tissues of the body including the mucosa of the gastrointestinal tract, and play important roles in hormone synthesis and breakdown (including estrogen and testosterone synthesis and metabolism), cholesterol synthesis, and vitamin D metabolism. In most animals, including humans, hepatic cytochromes P450 are the most widely studied of the P450 enzymes. The Human Genome Project has identified 63 human genes (57 full genes and 5 pseudogenes) coding for the various cytochrome P450 enzymes [1]. Drug Metabolism In drug metabolism, cytochrome P450 is probably the most important element of oxidative metabolism (also known as Phase I metabolism) in animals (metabolism in this context being the chemical modification or degradation of chemicals including drugs and endogenous compounds). Many drugs may increase or decrease the activity of various CYP isozymes in a phenomenon known as enzyme induction and inhibition). This is a major source of adverse drug interactions, since changes in CYP enzyme activity may affect the metabolism and clearance of various drugs. For example, if one drug inhibits the CYP-mediated metabolism of another drug, the second drug may accumulate within the body to toxic levels, possibly causing an overdose. Hence, these drug interactions may necessitate dosage adjustments or choosing drugs which do not interact with the CYP system. In addition, naturally occurring compounds may also cause a similar effect. For example, bioactive compounds found in grapefruit juice and some other fruit juices, including bergamottin, dihydroxybergamottin, and paradisin-A, have been found to inhibit CYP3A4-mediated metabolism of certain medications, leading to increased bioavailability and thus the strong possibility of overdosing. Because of this risk, avoiding grapefruit juice and fresh grapefruits entirely while on drugs is usually advised. [edit] P450s in Plants Plant cytochrome P450s are involved in a wide range of biosynthetic reactions, leading to various fatty acid conjugates, plant hormones, defensive compounds, or medically important drugs. Terpenoids, which represent the largest class of characterized natural plant compounds, are often metabolic substrates for plant CYPs

Coughing and sneezing

Mon, 18 Dec 2006 12:10:09 +0000

Little RNA Viruses Viruses are biological hijackers. They attack a living cell and force it to make many new viruses, often destroying the cell in the process. Picornaviruses, or "little RNA viruses," are among the most simple viruses. They are composed of a modular protein shell, which seeks out and binds to a target cell surface, surrounding a short piece of RNA, which contains all of the information needed to co-opt the cell's machinery and direct the construction of new viruses. In spite of their simplicity, or perhaps because of it, the picornaviruses are also among the most important viruses for human health and welfare. Three familiar examples are shown here: poliovirus at the top (PDB entry 2plv), rhinovirus at the center (PDB entry 4rhv), and the virus that causes foot and mouth disease in livestock at the bottom (PDB entry 1bbt). Specialization Poliovirus and rhinovirus have specialized to attack primarily human beings, but they use two different approaches. Poliovirus, which is found in three similar forms, is designed to attack a given person only once. It makes its offspring and then is off to the next person. In most cases, poliovirus causes a simple flu-like disease as it attacks cells in the digestive system. This infection is rapidly cleared up by the immune system. But in about 1 in 100 cases, the virus spreads to the nerve cells that control muscle motion, causing paralysis--polio myelitis--as the nerve cells are infected. Rhinovirus, on the other hand, is found in many different forms that attack a given person many times during their life. Each time you get a cold, a different form of rhinovirus (or occasionally, a different type of virus) is attacking. Your body learns how to fight it off, but you are still susceptible to the next form. On average, a person will have a new cold once every two years, so most of us are quite familiar with the symptoms of rhinovirus infection in our nose and respiratory tract. Because they are so simple, picornaviruses can be very stable. Rhinovirus can last for days on your hands and still be infectious. And because the virus is shed from infected people all through the period with symptoms and even for days after, it spreads effectively through contact from person to person.

Running nose

Mon, 18 Dec 2006 15:10:07 +0000

Vaccines Antibodies are our major defense against these small, efficient viruses. Vaccines prime the immune system with antibodies, making it ready to fight an infection. In the case of poliovirus, there are two types of vaccines. One is a killed version of the virus, which is slowly killed with formaldehyde over the course of several days so that it is inactivated, but still keeps its proper shape. The second is a weakened, but still live, strain of the virus that has been artificially bred to stimulate the immune system without causing disease. The immune system responds by making antibodies to fight these weakened viruses, leaving it ready to fight the real thing when it comes along. The polio vaccines are one of the triumphs of modern medicine, but many people would say that the lack of a cure for the common cold is one of the great failings. The difficulty of creating a vaccine for the common cold lies in the diversity of rhinovirus. Over one hundred types of rhinovirus have been discovered as they strike people around the world, and new strains appear continually. Rhinovirus is a moving target that is not effectively combated with a single vaccine. Antiviral drugs, however, are a possible solution. Picornavirus Structure Many viruses, including the picornaviruses and bacteriophage phiX174 (discussed in an earlier Molecule of the Month), are icosahedral in shape. They are composed of 60 identical pieces that form a perfectly symmetrical shell, termed a capsid, around the viral genome. In the case of poliovirus and rhinovirus, the shell is composed of 60 copies of four different proteins (colored yellow, orange, red, and magenta on rhinovirus here, PDB entry 4rhv), for a total of 240 protein chains in all. Notice that the fourth chain, colored magenta, can only be seen on the inside surface of the capsid. These proteins are carefully designed to be stable, but not too stable. They must be fairly sturdy to allow the virus to pass from host to host through the hostile environment. But at the same time, they must be able to fall apart when they enter the cell, releasing the RNA inside. A carefully orchestrated set of structural changes occur as the virus attaches to the surface of the cell and is drawn inside, allowing the virus to deliver its RNA into the unwitting host.

Rhinovirus (part 3)

Mon, 18 Dec 2006 16:49:07 +0000

The RNA protected inside the capsid is seen only as a blurry tangle in these crystallographic structures and is not shown in these pictures, because it is not as perfectly symmetrical as the many proteins in the shell. The rhinovirus genome, when analyzed by sequencing techniques, contains just enough information to direct the construction of eleven proteins. These include the four separate proteins for its capsid, another four proteins that replicate its RNA, two proteins to clip each of these proteins into the proper shape, and one additional protein with as- to deliver its RNA into the unwitting host. yet obscure function. Antibodies bind to the surface of picornaviruses and stop them from attacking cells. In the left picture, rhinovirus is bound to a receptor protein on the cell surface, shown in blue (from PDB entry 1dgi). Notice that the receptor protein is gripped within a groove that encircles the five-fold symmetrical arrangement of proteins shown in yellow (known as the canyon in the picornavirus literature). Antibodies bind to the surface of rhinovirus and poliovirus in this same position and block their attachment to the surfaces of cells. The right picture shows fragments of antibodies (in light blue) bound to rhinovirus (from PDB entry 1rvf). The intact antibodies are much larger than the small fragments seen here, so seven to ten antibodies are enough to form a bulky barrier on each virus to block attachment and infection. Many structures of rhinovirus with antiviral drugs are available at the PDB, including the drug pleconaril, currently in clinical testing, shown here (PDB entry 1c8m). In this illustration, the drug is shown in spheres, and only four protein chains are shown, instead of the entire capsid. The inside of the virus is towards the bottom of the figure and the deep groove where the cellular receptor and antibodies bind can be seen on the upper side, shown with an arrow. Most drugs act by blocking protein binding sites or destabilizing a key interaction. These drugs, on the other hand, may act differently. They actually stabilize the virus structure so that it cannot release its cargo of RNA. The drugs bind in a little pocket under the deep groove that grabs onto the cellular receptor. Normally, the binding of virus to receptor shifts the structure of the virus, ultimately allowing the virus to release RNA. The drug, however, glues the virus shut. Rhinovirus (from the Greek rhin-, which means "nose") is a genus of the Picornaviridae family of viruses. Rhinoviruses are the most common viral infective agents in humans, and a causative agent of the common cold. There are over 105 serologic virus types that cause cold symptoms, and rhinoviruses are responsible for approximately 50% of all cases.

Common Cold

Mon, 18 Dec 2006 13:49:09 +0000

Rhinoviruses have single-stranded positive sense RNA genomes of between 7.2 and 8.5kb in length. At the 5' end of the genome is a virus-encoded protein, and like mammalian mRNA, there is a 3' poly-A tail. Structural proteins are encoded in the 5' region of the genome and non structural at the end. This is the same for all picornaviruses. The viral particles themselves are not enveloped and are icosahedral in structure. Rhinoviruses are composed of a capsid, that contains four viral proteins VP1, VP2, VP3 and VP4.[1][2] VP1, VP2, and VP3 form the major part of the protein capsid. The much smaller VP4 protein has a more extended structure and lies at interface between the capsid and the RNA genome. There are 60 copies of each of these proteins assembled as an icosahedron. Antibodies are a major defense against infection with the epitopes lying on the exterior regions of VP1-VP3. Transmission and epidemiology Rhinoviruses have two main modes of transmission: In the past it was obvious that these viruses were transmitted directly from person-to-person via aerosols of respiratory droplets. However, now they are known to be transmitted indirectly via respiratory droplets that are deposited on the hands and then transported by fingers to the nose or eyes. Rhinoviruses occur worldwide causing disease especially at schools for example which enhance transmission during fall and winter. They show symptoms such as fever, cough, and nasal congestion. The frequency of colds is high in childhood and decreases during adulthood most probably because of the possession of immunity.

Rhinovirus-5

Mon, 18 Dec 2006 13:49:09 +0000

Most people are infected with a rhinovirus. The common cold occurs only when the immune system is weakened. The most common reason for this is stress. The primary route of entry for rhinoviruses is the upper respiratory tract. Afterwards, the virus binds to ICAM-1 (intracellular adhesion molecule -1) receptors on respiratory epithelial cells. As the virus replicates and spreads, infected cells release distress signals known as chemokines and cytokines (which in turn activate inflammatory mediators). Rhinoviruses rarely cause lower respiratory tract disease probably because they grow poorly at 37°C. Novel antiviral drugs Interferon-alpha used intranasally was shown to be protective to rhinovirus infections. However, volunteers treated with this drug experienced some side effects, such as nasal bleeding, and resistance was also developing toward the drug. Hence, all research put into this drug was ceased. Pleconaril, is a bioavailable antiviral drug that is taken orally for treating infections caused by picornaviruses.[3] This drug acts by binding to a hydrophobic pocket in VP1 and stabilizes the protein capsid to such an extent that the virus cannot release its RNA genome into the target cell. When tested in volunteers, during the clinical trials, this drug caused a significant decrease in mucus secretions and illness-associated symptoms. Pleconaril is not currently available for treatment of rhinoviral infections, as its efficacy in treating these infections is under further evaluation.

Cholera toxin animation 1

Sat, 23 Dec 2006 08:03:30 +0000

Bacteria pull no punches when they fight to protect themselves. Some bacteria build toxins so powerful that a single molecule can kill an entire cell. This is far more effective than chemical poisons like cyanide or arsenic. Chemical poisons attack important molecules one by one, so many, many molecules of cyanide are needed to kill a cell. Bacterial toxins use two strategies to make their toxins far more deadly than this. Building a Deadly Toxin The first strategy used to build super-deadly toxins is to use a targeting mechanism to deliver the toxin directly to the unlucky cell. Cholera toxin, shown here from PDB entry 1xtc, has a ring of five identical protein chains, colored blue here, which binds to carbohydrates on the surface of cells. This delivers the toxic part of the molecule, colored red, to the cell, where it can wreak its havoc. The second deadly strategy is to use a toxic enzyme instead of a chemical poison. Enzymes are designed to perform their reactions over and over again, hopping from target to target and making their chemical changes. Thus, one enzyme can modify a whole cell full of molecules. Cholera uses this strategy once it gets inside cells. The toxic portion hops from molecule to molecule, disabling each one in turn, until the entire cell is killed. Cholera Toxin in Action The catalytic portion of cholera toxin performs a single function: it seeks out the G proteins used for cellular signaling and attaches an ADP molecule to them (for more on G-proteins, see the Molecule of the Month for March 2004 ). This converts the G-protein into a permanently active state, so it sends a never-ending signal. This confuses the cell, and among other things, it begins to transport lots of water and sodium outwards. This floods the intestine, leading to life-threatening dehydration.

Cholera toxin science video 2

Tue, 26 Dec 2006 19:02:38 +0000

Cholera Toxin in Action The catalytic portion of cholera toxin performs a single function: it seeks out the G proteins used for cellular signaling and attaches an ADP molecule to them (for more on G-proteins, see the Molecule of the Month for March 2004 ). This converts the G-protein into a permanently active state, so it sends a never-ending signal. This confuses the cell, and among other things, it begins to transport lots of water and sodium outwards. This floods the intestine, leading to life-threatening dehydration. The two-part strategy employed by cholera toxin is highly effective, so much so that it is used by many different organisms that seek to protect themselves. A few examples from the PDB are shown here, with the targeting portion in blue and the toxic enzyme in red. These include E. coli enterotoxin (PDB entry 1ltb), which looks and acts like cholera toxin and is a cause of intestinal problems when traveling. Pertussis toxin (PDB entry 1prt), made by the bacterium that causes whooping cough, also attacks the G-protein signaling pathway. Diphtheria toxin (PDB entry 1mdt) is synthesized as a single chain, but is then cut to form the two-part toxin when it is released. It shuts down protein synthesis in cells by attacking one of the elongation factors. Ricin (PDB entry 2aai) is a powerful toxin made by the castor bean plant. Once it gets inside cells, it blocks protein synthesis by directly attacking ribosomes. For more information on toxins from a genomics perspective, take a look at the Protein of the Month at the European Bioinformatics Institute.

Hemoglobin science video 1

Thu, 28 Dec 2006 18:18:27 +0000

Hemoglobin is the protein that makes blood red. It is composed of four protein chains, two alpha chains and two beta chains, each with a ring-like heme group containing an iron atom. Oxygen binds reversibly to these iron atoms and is transported through blood. Each of the protein chains is similar in structure to myoglobin (presented in the January 2000 Molecule of the Month), the protein used to store oxygen in muscles and other tissues. However, the four chains of hemoglobin give it some extra advantages, as described on the next page. Use and Abuse of Hemoglobin Aside from oxygen transport, hemoglobin can bind and transport other molecules like nitric oxide and carbon monoxide. Nitric oxide affects the walls of blood vessels, causing them to relax. This in turn reduces the blood pressure. Recent studies have shown that nitric oxide can bind to specific cysteine residues in hemoglobin and also to the irons in the heme groups, as shown in PDB entry 1buw. Thus, hemoglobin contributes to the regulation of blood pressure by distributing nitric oxide through blood. Carbon monoxide, on the other hand, is a toxic gas.

Biochemistry: HEMOGLOBIN

Fri, 29 Dec 2006 14:45:19 +0000

Red Blood, Blue Blood Ever wondered why blood vessels appear blue? Oxygenated blood is bright red: when you are cut, the blood you see is brilliant red oxygenated blood. Deoxygenated blood is deep purple: when you donate blood or give a blood sample at the doctor's office, it is drawn into a storage tube away from oxygen, so you can see this dark purple color. However, deep purple deoxygenated blood appears blue as it flows through our veins, especially in people with fair skin. This is due to the way that different colors of light travel through skin: blue light is reflected in the surface layers of the skin, whereas red light penetrates more deeply. The dark blood in the vein absorbs most of this red light (as well as any blue light that makes it in that far), so what we see is the blue light that is reflected at the skin's surface. Some organisms like snails and crabs, on the other hand, use copper to transport oxygen, so they truly have blue blood. Artificial Blood Blood transfusions have saved countless lives. However, the need for matching blood type, the short life of stored blood, and the possibility of contamination are still major concerns. An understanding of how hemoglobin works, based on decades of biochemical study and many crystallographic structures, has prompted a search for blood substitutes and artificial blood. The most obvious approach is to use a solution of pure hemoglobin to replace lost blood. The main challenge is keeping the four protein chains of hemoglobin together. In the absence of the protective casing of the red blood cell, the four chains rapidly fall apart. To avoid this problem, novel hemoglobin molecules have been designed where two of the four chains are physically linked together, as shown in PDB entry 1c7d. In that structure, two additional glycine residues form a link between two of the chains, preventing their separation in solution. Hemoglobin Cousins Looking through the PDB, you will find many different hemoglobin molecules. You can find Max Perutz's groundbreaking structure of horse hemoglobin in entry 2dhb, shown in the picture here. There are structures of human hemoglobins, both adult and fetal. You can also find unusual hemoglobins like leghemoglobin, which is found in legumes. It is thought to protect the oxygen-sensitive bacteria that fix nitrogen in leguminous plant roots. In the past few years some hemoglobin cousins called the "truncated hemoglobins" have been identified, such as the hemoglobin in PDB entry 1idr, which have several portions of the classic structure edited out. The only feature that is absolutely conserved in this subfamily of proteins is the histidine amino acid that binds to the heme iron.

Red Blood Cells (EPO)

Tue, 02 Jan 2007 05:00:04 +0000

Cooperation Makes It Easier Hemoglobin is a remarkable molecular machine that uses motion and small structural changes to regulate its action. Oxygen binding at the four heme sites in hemoglobin does not happen simultaneously. Once the first heme binds oxygen, it introduces small changes in the structure of the corresponding protein chain. These changes nudge the neighboring chains into a different shape, making them bind oxygen more easily. Thus, it is difficult to add the first oxygen molecule, but binding the second, third and fourth oxygen molecules gets progressively easier and easier. This provides a great advantage in hemoglobin function. When blood is in the lungs, where oxygen is plentiful, oxygen easily binds to the first subunit and then quickly fills up the remaining ones. Then, as blood circulates through the body, the oxygen level drops while that of carbon dioxide increases. In this environment, hemoglobin releases its bound oxygen. As soon as the first oxygen molecule drops off, the protein starts changing its shape. This prompts the remaining three oxygens to be quickly released. In this way, hemoglobin picks up the largest possible load of oxygen in the lungs, and delivers all of it where and when needed. In this animated figure, the heme group of one subunit, shown in the little circular window, is kept in one place so that you can see how the protein moves around it when oxygen binds. The oxygen molecule is shown in blue green. As it binds to the iron atom in the center of the heme, it pulls a histidine amino acid upwards on the bottom side of the heme. This shifts the position of an entire alpha helix, shown here in orange below the heme. This motion is propagated throughout the protein chain and on to the other chains, ultimately causing the large rocking motion of the two subunits shown in blue. The two structures shown are PDB entries 2hhb and 1hho.

Hemoglobin is the key

Tue, 02 Jan 2007 17:18:04 +0000

The genes for the protein chains of hemoglobin show small differences within different human populations, so the amino acid sequence of hemoglobin is slightly different from person to person. In most cases the changes do not affect protein function and are often not even noticed. However, in some cases these different amino acids lead to major structural changes. One such example is that of the sickle cell hemoglobin, where glutamate 6 in the beta chain is mutated to valine. This change allows the deoxygenated form of the hemoglobin to stick to each other, as seen in PDB entry 2hbs, producing stiff fibers of hemoglobin inside red blood cells. This in turn deforms the red blood cell, which is normally a smooth disk shape, into a C or sickle shape. The distorted cells are fragile and often rupture, leading to loss of hemoglobin. This may seem like a uniformly terrible thing, but in one circumstance, it is actually an advantage. The parasites that cause the tropical disease malaria, which spend part of their life cycle inside red blood cells, cannot live in the fiber-filled sickle cells. Thus people with sickle cell hemoglobin are somewhat resistant to malaria. Other circumstances leading to troubled hemoglobins arise from a mismatch in the production of the alpha and beta proteins. The structure requires equal production of both proteins. If one of these proteins is missing, it leads to conditions called Thalassemia. You can look at the binding of oxygen up close in two structures of human hemoglobin. PDB entry 2hhb shows hemoglobin with no oxygen bound. In this picture, the heme is seen edge-on with the iron atom colored in gold. You can see the key histidine reaching up on the bottom side to bind to the iron atom. In PDB entry 1hho, oxygen has bound to the iron, pulling it upwards. This in turn, pulls on the histidine below, which then shifts the location of the entire protein chain. These changes are transmitted throughout the protein, ultimately causing the big shift in shape that changes the binding strength of the neighboring sites.

The Lethal Cholera toxin

Wed, 03 Jan 2007 09:20:58 +0000

Cholera toxin chemistry

Thu, 04 Jan 2007 17:29:45 +0000

Most of the Vibrio cholerae bacteria in the water that a potential host drinks do not survive the very acidic conditions of the human stomach [2] But the few bacteria that manage to survive the stomach's acidity conserve their energy and stored nutrients during the perilous passage through the stomach by shutting down much protein production. When the surviving bacteria manage to exit the stomach and reach the favorable conditions of the small intestine, they need to propel themselves through the thick mucus that lines the small intestine to get to the intestinal wall where they can thrive. So they start up production of the hollow cylindrical protein flagellin to make flagella, the curly whip-like tails that they rotate to propel themselves through the pasty mucus that lines the small intestine. But when the cholera bacteria reach the intestinal wall, they do not need the flagella propellers to move themselves any more, so they stop producing the protein flagellin, thus again conserving energy and nutrients by changing the mix of proteins that they manufacture, responding to the changed chemical surroundings. And on reaching the intestinal wall, they start producing the toxic proteins that give the infected person a watery diarrhea which carries the multiplying and thriving new generations of V. cholerae bacteria out into the drinking water of the next host—if proper sanitation measures are not in place.

Cholera toxin

Thu, 04 Jan 2007 23:23:42 +0000

Female sex hormone

Fri, 05 Jan 2007 06:32:38 +0000

Estrogens (less commonly oestrogens) are a group of steroid compounds, named for their importance in the estrous cycle, and functioning as the primary female sex hormone. While estrogens are present in both men and women, they are usually present at significantly higher levels in women of reproductive age. They promote the development of female secondary sex characteristics, such as breasts, and are also involved in the thickening of the endometrium and other aspects of regulating the menstrual cycle. Like all steroid hormones, estrogens readily diffuse across the cell membrane; inside the cell, they interact with estrogen receptors.[1] The three major naturally occurring estrogens in women are estradiol, estriol, and estrone. From menarche to menopause the primary estrogen is 17ß-estradiol. In the body these are all produced from androgens through actions of enzymes. Estradiol is produced from testosterone and estrone from androstenedione. Estrone is weaker than estradiol, and in postmenopausal women more estrone is present than estradiol. A range of synthetic and natural substances have been identified that also possess estrogenic activity.[2] Synthetic substances of this kind are known as xenoestrogens, while natural plant products with estrogenic activity are called phytoestrogens. Estrogens are used as part of some oral contraceptives and also in estrogen replacement therapy of postmenopausal women.

Female sex hormone (part 2)

Mon, 08 Jan 2007 04:16:50 +0000

Our bodies grow in two major spurts during our lives. You probably don't remember the first, which occurred during the first few months of your life as you grew from a single cell into a fully formed baby. On the other hand, you probably have many memories (or you may be making those memories now) of your second frenzy of growth. During puberty, sex hormones direct selected tissues to undergo a second wave of growth and development. In women, estrogen hormones are largely responsible for coordinating these changes. Estrogens are made in the ovaries and then delivered within seconds throughout the body in the blood, directing the growth from child to adult. Straight to the Source Estrogens are small, carbon-rich molecules built from cholesterol. This is quite different than larger hormones, such as insulin and growth hormone, which are sensed by receptors on the cell surface. Estrogens pass directly into cells throughout the body, so the cell can use receptors that are in the nucleus, right at the site of action on the DNA. When estrogen enters the nucleus, it binds to the estrogen receptor, causing it to pair up and form a dimer. This dimer then binds to several dozen specific sites in the DNA, strategically placed next to the genes that need to be activated. Then, the DNA-bound receptor activates the DNA-reading machinery and starts the production of messenger RNA. A Large Family When researchers looked into the human genome, they found over 150 proteins that are similar to the estrogen receptor. This is a large family of nuclear receptors that sense the levels of small hormones and other signaling molecules, such as steroid and thyroid hormones, vitamin D, and retinoic acid. Like estrogen, these are all small molecules that pass directly into cells and find their way to the nucleus. These receptors each bind to a specific signaling molecule and then activate or repress their own set of 50-100 genes.

Sex Hormones

Tue, 09 Jan 2007 04:28:36 +0000

Our bodies grow in two major spurts during our lives. You probably don't remember the first, which occurred during the first few months of your life as you grew from a single cell into a fully formed baby. On the other hand, you probably have many memories (or you may be making those memories now) of your second frenzy of growth. During puberty, sex hormones direct selected tissues to undergo a second wave of growth and development. In women, estrogen hormones are largely responsible for coordinating these changes. Estrogens are made in the ovaries and then delivered within seconds throughout the body in the blood, directing the growth from child to adult. Straight to the Source Estrogens are small, carbon-rich molecules built from cholesterol. This is quite different than larger hormones, such as insulin and growth hormone, which are sensed by receptors on the cell surface. Estrogens pass directly into cells throughout the body, so the cell can use receptors that are in the nucleus, right at the site of action on the DNA. When estrogen enters the nucleus, it binds to the estrogen receptor, causing it to pair up and form a dimer. This dimer then binds to several dozen specific sites in the DNA, strategically placed next to the genes that need to be activated. Then, the DNA-bound receptor activates the DNA-reading machinery and starts the production of messenger RNA. A Large Family When researchers looked into the human genome, they found over 150 proteins that are similar to the estrogen receptor. This is a large family of nuclear receptors that sense the levels of small hormones and other signaling molecules, such as steroid and thyroid hormones, vitamin D, and retinoic acid. Estrogens are used as part of some oral contraceptives and also in estrogen replacement therapy of postmenopausal women.

How antibiotics work

Tue, 09 Jan 2007 20:32:38 +0000

Penicillin (sometimes abbreviated PCN) refers to a group of ß-lactam antibiotics used in the treatment of bacterial infections caused by susceptible, usually Gram-positive, organisms. The name “penicillin” can also be used in reference to a specific member of the penicillin group. All penicillins possess the basic Penam Skeleton, which has the molecular formula R-C9H11N2O4S, where R is a variable side chain. History The discovery of penicillin is usually att in 1928, though others had earlier noted the antibacterial effects of Penicillium. Fleming, at his laboratory in St. Mary's Hospital (now one of Imperial College teaching hospitals) in London, noticed a halo of inhibition of bacterial growth around a contaminant blue-green mould on a Staphylococcus plate culture. Fleming concluded that the mould was releasing a substance that was inhibiting bacterial growth and lysing the bacteria. He grew a pure culture of the mould and discovered that it was a Penicillium mould, now known to be Penicillium chrysogenum. Fleming coined the term "penicillin" to describe the filtrate of a broth culture of the Penicillium mould. Even in these early stages, penicillin was found to be most effective against Gram-positive bacteria, and ineffective against Gram-negative organisms and fungi. He expressed initial optimism that penicillin would be a useful disinfectant, being highly potent with minimal toxicity compared to antiseptics of the day, but particularly noted its laboratory value in the isolation of "Bacillus influenzae" (now Haemophilus influenzae).[1] After further experiments, Fleming was convinced that penicillin could not last long enough in the human body to kill pathogenic bacteria and stopped studying penicillin after 1931, but restarted some clinical trials in 1934 and continued to try to get someone to purify it until 1940.

Penicillin Resistance

Wed, 10 Jan 2007 08:59:26 +0000

Penicillin was being mass-produced in 1944During World War II, penicillin made a major difference in the number of deaths and amputations caused by infected wounds amongst Allied forces; saving an estimated 12-15% of lives. Availability was severely limited, however, by the difficulty of manufacturing large quantities of penicillin and by the rapid renal clearance of the drug necessitating frequent dosing. Penicillins are actively secreted and about 80% of a penicillin dose is cleared within three to four hours of administration. During those times it became common procedure to collect the urine from patients being treated so that the penicillin could be isolated and reused

Resistance to antibiotics

Wed, 10 Jan 2007 17:44:24 +0000

The first major development was ampicillin, which offered a broader spectrum of activity than either of the original penicillins. Further development yielded beta-lactamase-resistant penicillins including flucloxacillin, dicloxacillin and methicillin. These were important for their activity against beta-lactamase-producing bacteria species, but are ineffective against the methicillin-resistant Staphylococcus aureus strains that subsequently emerged. The line of true penicillins were the antipseudomonal penicillins, such as ticarcillin and piperacillin, useful for their activity against Gram-negative bacteria. However, the usefulness of the beta-lactam ring was such that related antibiotics, including the mecillinams, the carbapenems and, most importantly, the cephalosporins, have at the centre of their structures.

How Viagra works

Thu, 11 Jan 2007 08:16:08 +0000

Viagra is available as blue pills with a characteristic shapeEven though sildenafil is only available by prescription from a doctor, it was advertised directly to consumers on US TV (famously being endorsed by Bob Dole and Football star Pele). Numerous sites on the Internet offer Viagra for sale after an "online consultation", a mere web questionnaire. The "Viagra" name has become so well known that many fake aphrodisiacs now call themselves "herbal Viagra" or are presented as blue tablets imitating the shape and colour of Pfizer's product. Viagra is also informally known as "Vitamin V", "the Blue Pill", as well as various other nicknames.

Viagra's secrets unveiled

Thu, 11 Jan 2007 13:46:02 +0000

Erectile dysfunction (ED) or impotence is a sexual dysfunction characterized by the inability to develop or maintain an erection of the penis for satisfactory sexual intercourse regardless of the capability of ejaculation. There are various underlying causes, such as diabetes, many of which are medically reversible. Due to its embarrassing nature and the shame felt by sufferers, the subject was taboo for a long time, and is the subject of many urban legends. Folk remedies have long been advocated, with some being advertised widely since the 1930s. The introduction of perhaps the first pharmacologically effective remedy for impotence, sildenafil (trade name Viagra), in the 1990s caused a wave of public attention, propelled in part by the news-worthiness of stories about it and heavy advertising.

How tamiflu kills bird flue

Fri, 12 Jan 2007 04:44:19 +0000

an antiviral drug that is used in the treatment and prophylaxis of both Influenzavirus A and Influenzavirus B. Like zanamivir, oseltamivir is a neuraminidase inhibitor. It acts as a transition-state analogue inhibitor of influenza neuraminidase, preventing new viruses from emerging from infected cells. It has also been found that the standard recommended dose incompletely suppresses viral replication in at least some patients with H5N1 avian influenza, rendering therapy ineffective and increasing the risk of viral resistance

Pandemic fears

Fri, 12 Jan 2007 17:30:44 +0000

Oseltamivir (tamiflu) was widely used during the H5N1 avian influenza epidemic in Southeast Asia in 2005. In response to the epidemic, various governments – including those of the United Kingdom, Canada, United States and Australia – stockpiled quantities of oseltamivir in preparation for a possible pandemic. Though large, the quantities stockpiled would not have been sufficient to protect the entire population of these countries.

Glow Little Glowworm, Glow

Tue, 16 Jan 2007 14:02:06 +0000

Do you remember the first time that you saw a firefly? If you live anywhere between the Rocky Mountains and the east coast of the US, you have probably chased fireflies since you were a child. If you live in other parts of the world, like me, you may have had the pleasure of discovering fireflies during a summer vacation. They are one of the delightful wonders of warm summer evenings. The cool yellowish light of fireflies is created by the enzyme luciferase, shown here from PDB entry 2d1s. The creation of light is not an easy process. It requires a lot of energy—a single photon of green light requires about the same energy as the breaking of eight ATP molecules. So, luciferase uses a very energetic process to create light. It has a cofactor, termed a luciferin, that forms a highly strained complex with oxygen, using an ATP molecule to help set everything up. When this oxygenated luciferin breaks, forming carbon dioxide in the process, it leaves behind a highly excited form that then emits the light

Italian Firefly

Wed, 17 Jan 2007 15:08:01 +0000

Bioluminescence is the production and emission of light by a living organism as the result of a chemical reaction during which chemical energy is converted to light energy. The name originates from the Greek bios for "living" and the Latin lumen "light". Bioluminescence may be generated by symbiotic organisms carried within a larger organism. It is generated by an enzyme-catalyzed chemoluminescence reaction, wherein the pigment luciferin is oxidised by the enzyme luciferase. Adenosine triphosphate (ATP) is involved in most instances. The chemical reaction can occur either within or outside of the cell. In bacteria, the expression of genes related to bioluminescence is controlled by an operon called the lux operon. Bioluminescence is a form of luminescence, or "cold light" emission; less than 20% of the light generates thermal radiation. It should not be confused with fluorescence, phosphorescence or refraction of light.

Bloody business

Thu, 18 Jan 2007 08:28:54 +0000

Blood performs many essential jobs in your body: it transports oxygen and nutrients, it protects your cells from infection, and it carries hormones and other messages from place to place in your body. But since blood is a liquid that is pumped under pressure, we must protect ourselves from leaks. Fortunately, the blood has a built-in repair method that quickly stops up breaks in the blood circulatory system as soon as they happen. You see these repairs in action whenever you cut yourself: the blood thickens and forms a gooey clot, which then dries into a scab that seals and protects the cut until it can heal. To Clot or Not? Blood clotting is a tricky business. All of the building blocks for a clot must be present all the time, so that they can instantly jump into action when damage occurs. But this must be done carefully and only at exactly the right time. If clots form in the wrong places, they could block the normal flow of blood, which could then cause heart attacks or strokes. Tissue factor is one of the molecules that triggers the formation of a clot when the time is right.

Blood clotting is a tricky business.

Thu, 18 Jan 2007 14:01:58 +0000

The coagulation of blood is a complex process during which blood forms solid clots. It is an important part of hemostasis (the cessation of blood loss from a damaged vessel) whereby a damaged blood vessel wall is covered by a fibrin clot to stop hemorrhage and aid repair of the damaged vessel. Disorders in coagulation can lead to increased hemorrhage and/or thrombosis and embolism. Coagulation is similar in mammals, with all mammals using a combined cellular and serine protease mechanism. The system in humans is the most extensively researched and therefore the best known. This article focuses on human blood coagulation In a normal individual, coagulation is initiated within 20 seconds after an injury occurs to the blood vessel damaging the endothelial cells. Platelets immediately form a haemostatic plug at the site of injury. This is called primary haemostasis. Secondary haemostasis then follows—plasma components called coagulation factors respond (in a complex cascade) to form fibrin strands which strengthen the platelet plug. Contrary to popular belief, coagulation from a cut on the skin is not initiated by air or drying out, but by platelets adhering to and activated by collagen in the blood vessel endothelium. The activated platelets then release the contents of their granules, these contain a variety of substances that stimulate further platelet activation and enhance the haemostatic process.

Your Inheritance

Fri, 19 Jan 2007 13:22:48 +0000

Your genetic information, inherited from your parents, is your most precious possession. It guided the construction of your body in the first nine months of your life and it continues to control all of the basic functions of living. Each of your cells is constantly using this information, asking questions about how to control blood sugar levels and body temperature, how to digest different foods and how to deal with new environmental challenges, and thousands of other important questions. The answers are held in the DNA

This is what your DNA looks like

Fri, 19 Jan 2007 16:40:45 +0000

Deoxyribonucleic acid (DNA) is a nucleic acid that contains the genetic instructions for the development and function of living organisms. All known cellular life and some viruses contain DNA. The main role of DNA in the cell is the long term storage of information. It is often compared to a blueprint, since it contains the instructions to construct other components of the cell, such as proteins and RNA molecules. Each of the cells in your body carries about 1.5 gigabytes of genetic information, an amount of information that would fill two CD ROMs or a small hard disk drive. Surprisingly, when placed in an appropriate egg cell, this amount of information is enough to build an entire living, breathing, thinking human being. Through the efforts of the international human genome sequencing projects, you can now read this information. Along with most of the biological research community, you can marvel at the complexity of this information and try to understand what it means. At the same time, you can wonder at the simplicity of this information when compared to the intricacy of the human body

Base pairing in DNA

Sat, 20 Jan 2007 06:58:43 +0000

Base pairing Further information: Base pair Each type of base on one strand forms a bond with just one type of base on the other strand. This is called complementary base pairing. Here, purines form hydrogen bonds to pyrimidines, with A bonding only to T, and C bonding only to G. This arrangement of two nucleotides joined together across the double helix is called a base pair. In a double helix, the two strands are also held together by forces generated by the hydrophobic effect and pi stacking, but these forces are not affected by the sequence of the DNA.[13] As hydrogen bonds are not covalent, they can be broken and rejoined relatively easily. The two strands of DNA in a double helix can therefore be pulled apart like a zipper, either by a mechanical force or high temperature.[14] As a result of this complementarity, all the information in the double-stranded sequence of a DNA helix is duplicated on each strand, which is vital in DNA replication. Indeed, this reversible and specific interaction between complementary base pairs is critical for all the functions of DNA in living organisms.[1]

Guess what…?

Tue, 23 Jan 2007 13:52:07 +0000

Guess what…? Play this little quiz game: How much time does it take you to see what this picture represents?

Quiz:Small statue

Tue, 23 Jan 2007 16:42:56 +0000

Play this little quiz game: How much time does it take you to see which statue this picture represents?

C.S.I. : DNA

Wed, 24 Jan 2007 08:16:05 +0000

DNA is also one of the most familiar molecules, the central icon of molecular biology, easily recognized by everyone. To some, it may carry a negative connotation, being a pervasive symbol for activists against genetically engineered produce. To others, it may bring to mind advances in forensics such as the DNA fingerprinting used in many recent high-profile trials. Some may have seen it in science fiction, modified to build dinosaurs or store cryptic messages from aliens. To all it is a pervasive symbol of our growing understanding of the human body and our close kinship with the rest of the biosphere, and the moral and ethical issues that must be addressed in the face of that knowledge. DNA is perfect for the storage and readout of information. It is laden with information. Every surface and edge of the molecule carries information. The basic mechanism by which DNA stores and transmits genetic information was discovered in the 1950's by Watson and Crick. This basic information is stored in the way that the bases match one another on opposite sides of the double helix--adenine with thymine, guanine with cytosine--forming a set of complementary hydrogen bonds

Pop Quiz!

Wed, 24 Jan 2007 14:18:46 +0000

Guess what…? Play this little quiz game: How much time does it take you to see what this picture represents? Category: Architecture and Art

Guess What..? (2)

Thu, 25 Jan 2007 07:27:37 +0000

Play this little quiz game: How much time does it take you to see what this picture represents? Category: food & drinks

Guess What..(Visual quiz)

Thu, 25 Jan 2007 12:27:33 +0000

Play this little quiz game: How much time does it take you to see what this picture represents?

Guess What.. (animals)

Fri, 26 Jan 2007 04:27:21 +0000

Play this little quiz game: How much time does it take you to see what this picture represents? Category: animals

Quiz show

Fri, 26 Jan 2007 13:18:13 +0000

Play this little quiz game: How much time does it take you to see what this picture represents?

Against the Clock

Fri, 26 Jan 2007 14:48:17 +0000

Guess what…? Play this little quiz game: How much time does it take you to see what this picture represents?

Sports Puzzle

Mon, 29 Jan 2007 03:28:07 +0000

Guess What.. Play this little quiz game: category : SPORTS

Puzzle

Mon, 29 Jan 2007 04:13:03 +0000

Guess what…? How much time does it take you to see what this picture represents?

Crack & Cocaine

Tue, 30 Jan 2007 16:17:17 +0000

Cocaine (or crack in its impure freebase form) is a crystalline tropane alkaloid that is obtained from the leaves of the coca plant. It is a stimulant of the central nervous system and an appetite suppressant, giving rise to what has been described as a euphoric sense of happiness and increased energy. The name comes from the name of the coca plant in addition to the alkaloid suffix -ine, forming Cocaine. The stimulating qualities of the coca leaf were known to the ancient peoples of Peru and other pre-Columbian Andean societies. In modern Western countries, cocaine has been a feature of the counterculture for over a century. There is a long list of prominent intellectuals, artists, and musicians who have used the drug

Smoking weed every day keeps the doctor away?

Wed, 31 Jan 2007 07:17:03 +0000

Cannabis is an annual flowering herb. It is a dicot. The leaves are palmately compound, with serrate leaflets. During the vegetative phase of growth, there is one leaflet on the first true leaf, three leaflets on the second, five on the third, and so on, up to about seven for C. sativa subsp. indica, and eleven for C. sativa subsp. sativa. In the reproductive phase, the number of leaflets per leaf reduces to a single leaflet, and ultimately none at the terminal bud. Leaf arrangement is opposite in the vegetative phase, and alternate in the reproductive phase.

Need Aspirin?

Thu, 01 Feb 2007 09:27:52 +0000

The brand name Aspirin was coined by the Bayer company of Germany. In some countries the name is used as a generic term for the drug rather than the manufacturer's trademark. On March 6, 1899 Bayer registered it as a trademark. However, the German company lost the right to use the trademark in many countries as the Allies seized and resold its foreign assets after World War I. The right to use "Aspirin" in the United States (along with all other Bayer trademarks) was purchased from the U.S. government by Sterling Drug in 1918. Even before the patent for the drug expired in 1917, Bayer had been unable to stop competitors from copying the formula and using the name elsewhere, and so, with a flooded market, the public was unable to recognize "Aspirin" as coming from only one manufacturer. Sterling was subsequently unable to prevent "Aspirin" from being ruled a genericized trademark in a U.S. federal court in 1921. Sterling was ultimately acquired by Bayer in 1994, but this did not restore the U.S. trademark. Other countries (such as Canada and many countries in Europe) still consider "Aspirin" a protected trademark.

How Aspirin works

Thu, 01 Feb 2007 13:15:51 +0000

Aspirin overdose has potentially serious consequences, sometimes leading to significant morbidity and mortality. Patients with mild intoxication frequently have nausea and vomiting, abdominal pain, lethargy, tinnitus, and dizziness All overdose patients must be taken to a hospital immediately. Contrary to the urban legend, one can die from ingesting a bottle of pills, even if they are subsequently thrown up

How color vision works

Fri, 02 Feb 2007 04:36:46 +0000

Rhodopsin, also known as visual purple, is expressed in metazoan photoreceptor cells. It is a pigment of the retina that is responsible for both the formation of the photoreceptor cells and the first events in the perception of light. Rhodopsins belong to the class of G-protein coupled receptors. It is the chemical that allows night-vision, and is extremely sensitive to light. Exposed to white light, the pigment immediately bleaches, and it takes about 30 minutes to regenerate fully in humans.

See the light

Fri, 02 Feb 2007 14:51:48 +0000

The molecule that takes part in the initial step in the vision process, rhodopsin, has two components called 11-cis retinal and opsin. Retinal is a light-sensitive derivative of vitamin A, and opsin is a protein molecule.

Coóól Laser Ball

Sun, 04 Feb 2007 07:27:37 +0000

Special effects animation of a metal ball with 60 laser beams moving in all directions

Anthrax

Tue, 06 Feb 2007 13:36:40 +0000

Anthrax is an acute infectious disease caused by the bacterium Bacillus anthracis and is highly lethal in some forms. Anthrax most commonly occurs in wild and domestic ruminants, but it can also occur in humans when they are exposed to infected animals, tissue from infected animals, or high density of anthrax spores. There are no known cases of infection in humans resulting from direct contact with a diseased person. The word anthrax is derived from the Greek word anthrakis, or "coal", in reference to the black skin lesions victims develop.

Good and Bad Cholesterol

Wed, 07 Feb 2007 10:00:24 +0000

Cholesterol plays a central role in many biochemical processes, but is best known for the association of cardiovascular disease with various lipoprotein cholesterol transport patterns and high levels of cholesterol in the blood. In recent years, the somewhat imprecise term "bad cholesterol" has been used to refer to LDL low-density lipoprotein, and "good cholesterol" to refer to HDL high-density lipoprotein. Cholesterol does not have two different forms, but is transported around the body bound in different lipoproteins, the most well known of which are LDL and HDL. Cholesterol is insoluble in blood, but can be transported in the circulatory system when encapsulated by one of the varieties of lipoprotein, spherical particles which have an exterior composed mainly of water-soluble proteins. Abnormally low levels of cholesterol are termed hypocholesterolemia. Research into the causes of this state is relatively limited, and while some studies suggest a link with depression, cancer and cerebral hemorrhage it is unclear whether the low cholesterol levels are a cause for these conditions

Vitamin D: a cure for cancer?

Mon, 12 Feb 2007 11:29:10 +0000

The vitamin D hormone, calcitriol, has been found to induce death of cancer cells in vitro and in vivo. Although the anti-cancer activity of vitamin D is not fully understood, it is thought that these effects are mediated through vitamin D receptors expressed in cancer cells, and may be related it its immunomodulatory abilities. The anti-cancer activity of vitamin D observed in the laboratory has prompted some to propose that vitamin D supplementation might be beneficial in the treatment or prevention of some types of cancer. In 2005, scientists released a study which demonstrated a beneficial correlation between vitamin D intake and prevention of cancer. Drawing from a meta-analysis of 63 published reports, the authors showed that intake of an additional 1,000 international units (IU) (or 25 micrograms) of vitamin D daily reduced an individual's colon cancer risk by 50%, and breast and ovarian cancer risks by 30%. Research has also shown a beneficial effect of high levels of calcitriol on patients with advanced prostate cancer. Research has suggested that cancer patients who have surgery or treatment in the summer — and therefore get more vitamin D — have a better chance of surviving their cancer than those who undergo treatment in the winter when they are exposed to less sunlight

Why leaves are green

Fri, 23 Feb 2007 06:14:15 +0000

Chlorophyll is a green photosynthetic pigment found in most plants, algae, and cyanobacteria. Its name is derived from ancient Greek: chloros = green and phyllon = leaf. Chlorophyll absorbs most strongly in the blue and red but poorly in the green portions of the electromagnetic spectrum, hence the green color of chlorophyll-containing tissues like plant leaves. Chlorophyll is vital for photosynthesis, which helps plants get energy from light

Blood Transport

Mon, 26 Feb 2007 06:40:37 +0000

Serum albumin, often referred to simply as albumin, is the most abundant plasma protein in humans and other mammals. Albumin is essential for maintaining the osmotic pressure needed for proper distribution of body fluids between intravascular compartments and body tissues. The human version is human serum albumin. Bovine serum albumin, or BSA, is commonly used in molecular biology laboratories. Albumin is negatively charged. The glomerular basement membrane is also negatively charged; this prevents the filtration of albumin in the urine. In nephrotic syndrome, this property is lost, and there is more albumin loss in the urine. Nephrotic syndrome patients are given albumin to replace the lost albumin. Because smaller animals (for example rats) function at a lower blood pressure, they need less oncotic pressure to balance this, and thus need less albumin to maintain proper fluid distribution.

Green Lasers

Fri, 09 Mar 2007 12:19:15 +0000

Special effects animation of a metal ball with 45 green laser beams moving in all directions "rfs green"

Movie Facts: The 'Sentox' Nerve gas in '24'

Fri, 16 Mar 2007 13:21:46 +0000

-the 'sentox' nerve gasin '24' refers to 'VX' gas -VX is the deadliest nerve gas in the world -in the series '24',nerve gas killed(amongst others): Edgar Stiles and Lynn 'Mr' McGill -penetrates the body trough the air or through the skin -blocks neurotransmission that activates muscles -atropine is an antidote -causes death by suffocation. -Symptoms:blur vision,small pupils,dizzyness,foam from mouth, unvoluntary vomiting , urinating and defecation, convulsions,coma and suffocation -The only countries known to possess VX are the United States and Russia -As little as 200 micrograms is enough to kill an average person -VX was featured in the movie ' The Rock' -- Nerve agents (also known as nerve gases, though these chemicals are liquid at room temperature) are a class of phosphorus-containing organic chemicals (organophosphates) that disrupt the mechanism by which nerves transfer messages to organs. The disruption is caused by blocking acetylcholinesterase, an enzyme that normally relaxes the activity of acetylcholine, a neurotransmitter. As chemical weapons, they are classified as weapons of mass destruction by the United Nations according to UN Resolution 687, and their production and stockpiling was outlawed by the Chemical Weapons Convention of 1993; the Chemical Weapons Convention officially took effect on April 29, 1997. [1] Poisoning by a nerve agent leads to contraction of pupils, profuse salivation, convulsions, involuntary urination and defecation, and eventual death by asphyxiation as control is lost over respiratory muscles. Some nerve agents are readily vaporized or aerosolized and the primary portal of entry into the body is the respiratory system. Nerve agents can also be absorbed through the skin, requiring that those likely to be subjected to such agents wear a full body suit in addition to a respirator.

"Prison Break":How Michael Scofield fakes diabetes

Fri, 23 Mar 2007 15:25:10 +0000

-PUGNAc 5mg can be obtained from TRC,Toronto Research Chemicals for $125 -PUGNAc is a drug, acting as an inhibitor of glucosidase and so increasing insulin resistance. -PUGNAc was used by Michael Scofield in the television series Prison Break to keep his blood sugar level high, in order to appear both diabetic and to be resistant to insulin shots he was receiving butdid not need ______________-- Before he takes the Pugnac: Dr. Tancredi: Your blood glucose is at fifty milligrams per deciliter. Your body’s reacting to the insulin as though your not a diabetic. Are you sure it’s Type 1 Diabetes you got. Michael: Ever since I was a little kid. Dr. Tancredi: Alright. Not experiencing any tingling sensations, cold sweats? (Michael shakes his head and is saved by the phone. He gets and walks over to the barred window, looking outside. He notices his right hand is shaking and smoothes his left thumb over the palm. Dr. Tancredi gets off the phone.) I’d like to run some tests the next time your in. The last thing I want is to be administering insulin to a man who doesn’t. ____________________ Lincoln: What the hell’s a Pugnac? Michael: It lowers my insulin to the point where I’m hypoglycemic and as long as the good doctor thinks I’m diabetic I’ll have plenty of time in there to do what I need to do. ____ After he takes the Pugnac: Dr. Tancredi: It used to take hours, but we’ve come a long way with the new glucose kits. This’ll take us ten seconds. (Michael looks apprehensive) Slide this strips into the meter then we’re ready to go. I’m sure you know this but, the average glucose for a non- diabetic is about one hundred milligrams per deciliter. We see a number like that here and we know you’ve been misdiagnosed. Dr. Tancredi: Ah. Bad news I’m afraid. (She shows him the meter) one hundred and eighty milligrams per deciliter. You are definitely diabetic.

Truth Serum (pentothal) on TV

Fri, 30 Mar 2007 15:34:09 +0000

A truth serum is a drug used for the purposes of obtaining accurate information from an unwilling subject, most often by a police, intelligence, or military organization on a prisoner. Drugs used for this purpose have included ethanol, scopolamine, and sodium thiopental (known as Sodium Pentothal) In episode 12 of season 5 in 24 (TV series), Jack Bauer contacts CTU to tell them to prep an interogation room and for a medic to stand by with hyocine pentathol, another form of truth serum --- In episode 118 of MacGyver, a prisoner is given the choice of confessing freely or being injected with Sodium Pentothal. Jonathan Adams' alternative comic book originally published by Slave Labor Graphics and later self-published by City Cyclops is titled Truth Serum. In Thomas Harris' first Hannibal Lecter novel Red Dragon, FBI agent Will Graham mentions that when previous attempts to gain information from Lecter, regarding the location of one of his victims' bodies, using truth drugs like sodium pentathol, they only succeeded in him giving them 'a recipe for dip'. Karin Boye's dystopic novel Kallocain, originally published in 1940, is named after, and based around a fictional truth serum. In the James Bond film Octopussy, the villain Kamal Khan tells Bond that a combination of curare and a psychedelic agent gave "guaranteed results" as a truth drug, although at the cost of permanent insanity for the recipient. The U.S. television series Alias features repeated references to Sodium Pentothal as a truth drug. In the True Lies motion picture Harry Tasker (Arnold Schwarzenegger), subjected to sodium amytal, details his precise plan of killing the interrogator to the same interrogator, but still manages to carry it out. In Meet the Fockers, Greg Focker is injected with sodium pentothal by his father-in-law. In Johnny English, agent Johnny English (played by Rowan Atkinson) accidentally injects Pascal Sauvage's assistant with truth serum when trying to inject him with muscle relaxant. The assistant later proceeds to tell English how to get out of the building without being seen when asked. In [[Terminator 2: Judgment Day]], Doctor Silberman orders Sarah Connor subdued by hospital employees using Sodium Pentathol.

Movie Facts: Truth Serum (used by CTU in "24")

Fri, 30 Mar 2007 18:13:20 +0000

Jurassic Park: security measure failure

Fri, 06 Apr 2007 13:25:12 +0000

In the film Jurassic Park, the dinosaurs have their DNA modified so that they cannot produce lysine and must be supplied with it by the park's feeding system, otherwise they will eventually die. This is a security measure to prevent the creatures from spreading if they ever escaped into the outside world. In the book, the dinosaurs escape and survive by eating things rich in lysine such as soybeans and lentils. Lysine synthesis. Intermediates of the glutamate and the aspartate family are coupled in just the same way as in the arginine and asparagine synthesis. Lysine can be generated in two ways. Both are named according to their most characteristic intermediates. Green algae, ferns and higher plants take one pathway, some green flagellates (euglenophyta) and fungi the other. Jurassic Park is a 1993 science fiction film directed by Steven Spielberg, based upon the novel of the same name by Michael Crichton. On the island of Isla Nublar, scientists have created an amusement park of cloned dinosaurs. John Hammond (Richard Attenborough) invites a group of scientists, played by Sam Neill, Jeff Goldblum and Laura Dern, to visit the park during one weekend. Sabotage sets the carnivorous dinosaurs on the loose, and technicians and visitors attempt to escape the island.

Movie Facts: 'E.R.'(emergency room) : " sux!!! "

Fri, 13 Apr 2007 11:15:36 +0000

Suxamethonium chloride (also known as succinylcholine, scoline, or colloquially as sux) is a medication widely used in emergency medicine and anesthesia to induce muscle relaxation, usually to make endotracheal intubation possible. Suxamethonium is sold under several trade names such as Anectine, and may be referred to as "sux" for short. Suxamethonium acts as a depolarizing neuromuscular blocker. It imitates the action of acetylcholine at the neuromuscular junction, but it is not degraded by acetylcholinesterase but by pseudocholinesterase, a plasma cholinesterase. This hydrolysis by pseudocholinesterase is much slower than that of acetylcholine by acetylcholinesterase

Desperate housewives: botox all around us

Fri, 27 Apr 2007 11:40:15 +0000

Teri Hatcher has confessed to being a Botox fan. The 41-year-old actress, who revived her career playing Susan Mayer in Desperate Housewives, admitted she has had a little help in keeping her face linefree. "In the past I've had Botox and collagen," she admitted in an interview in America. Botox injections are said to smooth out wrinkles by paralysing facial muscles while collagen plumps up parts that are losing their lustre, especially lips Botox® is a trade name for botulinum toxin A. In this way, Botox® is related to botulism. Botulism is a form of food poisoning that occurs when someone eats something containing a neurotoxin produced by the bacterium Clostridium botulinum. Botulinum toxin A is one of the neurotoxins produced by Clostridium botulinum. The show takes place on the fictional Wisteria Lane in the American suburban town of Fairview, located in the fictional Eagle State. It follows the lives of four women, seen through the eyes of their dead neighbor - only two of whom are actually housewives as of January 2007 - as they work through domestic struggles while several mysteries unfold in the background. Desperate Housewives combines many styles such as: drama, comedy, mystery, thriller, farce, camp, soap opera and satire. The show stars Golden Globe award winning actresses Teri Hatcher and Felicity Huffman, TV veterans Marcia Cross and Nicollette Sheridan, and rising star Eva Longoria. Since the second pilot episode, Brenda Strong narrates the series

Pulp Fiction : Adrenalin shot straight to the heart

Fri, 04 May 2007 12:25:15 +0000

To refresh your memory, hit man Vincent (John Travolta) has the job of squiring his boss's wife, Mia (Uma Thurman), around town. While he's in the bathroom, she discovers his stash of what she thinks is cocaine and promptly snorts some. Bad idea--it's actually high-octane heroin. Vincent returns to find her comatose and frantically drives her to the home of his dealer Lance (Eric Stoltz), who hands Vincent a railroad-spike-sized syringe. The following classic dialogue ensues over the supine Mia: Lance: OK, you're giving her an injection of adrenaline straight to her heart. But she's got breastplates. You've gotta pierce through that. So what you gotta do is, you gotta bring the needle down in a stabbing motion. [Makes multiple stabbing motions] Vincent: I gotta stab her three times? Lance: No, you don't gotta fucking stab her three times! You gotta stab her once, but it's gotta be hard enough to get through her breastplate into her heart, all right? And then once you do that, you press down on the plunger. Vincent: OK, then what happens? Lance: I'm curious about that myself. Vincent does as instructed. Mia immediately sits bolt upright, eyes wide open and apparently fully recovered. OK, this isn't a 100 percent accurate depiction of what would actually occur. But here's the thing: doctors honest to God do on (rare) occasion jab a big hypodermic of epinephrine, aka adrenaline, directly into the heart of someone who's gone into cardiac arrest, a technique called intracardiac injection (ICI). If the patient is lucky she revives quickly--epinephrine is the fight-or-flight hormone that blasts through your system in moments of extremity. So there's a grain of truth to the scene. But only a grain. Among the problematic details: (1) The heart isn't beneath the "breastplate" (presumably Lance means the breastbone, or sternum--the heart is to the left of this), and in any case only a fool would try to force a needle through bone--you'd go between the ribs. (2) A cardiac arrest victim getting ICI doesn't instantly jerk up like the alarm clock just went off--the heart might restart right away, but it would take a while to regain consciousness. (3) Mia's problem probably isn't cardiac arrest anyway--the immediate consequence of heroin overdose is severe respiratory depression. As long as her heart keeps beating, ICI is pointless. If Mia needs an injection of something, a plain old intravenous shot will work just fine, since her blood is still circulating. (4) Epinephrine wouldn't sober up someone who was OD'ing. To neutralize heroin you'd administer a drug such as Narcan (naloxone), which blocks the opiate receptors in the brain and can bring a junkie back to earth in a matter of minutes.

Psychedelic

Fri, 11 May 2007 12:22:06 +0000

A psychedelic experience is characterized by the perception of aspects of one's mind previously unknown, or by the creative exuberance of the mind liberated from its ostensibly ordinary fetters. Psychedelic states are an array of experiences elicited by sensory deprivation as well as by psychedelic substances. Such experiences include hallucinations, changes of perception, synesthesia, altered states of awareness, mystical states, and occasionally states resembling psychosis. The term was first coined as a noun in 1957 by psychiatrist Humphry Osmond as an alternative descriptor for hallucinogenic drugs in the context of psychedelic psychotherapy. The term featured prominently in a now-famous exchange with Aldous Huxley, in which the little-used term phanerothyme (derived from roots relating to "spirit" or "soul") was suggested: The fashion for psychedelic drugs gave its name to the visual style of psychedelia, a term describing a category of rock music known as psychedelic rock, visual art, fashion, and culture that is associated originally with the high 1960s, hippies, and the Haight-Ashbury neighborhood of San Francisco, California. Psychedelia generally began in 1966, but truly took off in 1967 with the Summer of Love. Although associated with San Francisco, the style soon spread across the U.S.A., and worldwide. The counterculture of the 1960s had a strong influence on the popular culture of the early 1970s, and is well recognized even by those who are naïve to its psychedelic origins. It later became linked to a style of electronic dance music commonly known as psytrance.

Diamonds are a girl's best friend

Fri, 11 May 2007 13:10:14 +0000

Diamond is the hardest natural material known to man and the third-hardest known material after aggregated diamond nanorods and ultrahard fullerite. Its hardness and high dispersion of light make it useful for industrial applications and jewelry. Diamonds are specifically renowned as a material with superlative physical qualities — they make excellent abrasives because they can be scratched only by other diamonds, Borazon, ultrahard fullerite, or aggregated diamond nanorods, which also means they hold a polish extremely well and retain their lustre. About 130 million carats (26,000 kg) are mined annually, with a total value of nearly USD $9 billion.[citation needed] About 100,000 kg are synthesized annually.[2] The name diamond derives from the ancient Greek adamas "Diamonds Are a Girl's Best Friend" is a song perhaps most famously performed by Marilyn Monroe in the 1953 film Gentlemen Prefer Blondes. In a later scene, Jane Russell, who played opposite of Monroe, sang "Diamonds Are a Girl's Best Friend" in court. Monroe's rendition of the song has been considered an iconic performance and since been copied by other entertainers ranging from Madonna and Kylie Minogue to Anna Nicole Smith. The song was also featured in 2001 film Moulin Rouge!, sung by Nicole Kidman. "Diamonds Are a Girl's Best Friend" was introduced by Carol Channing in the original Broadway production of Gentlemen Prefer Blondes (1949), which was written by Jule Styne (who also wrote the scores for such famed Broadway musicals as Funny Girl and Gypsy) and Leo Robin. "Shine On You Crazy Diamond" is an epic nine-part Pink Floyd composition with lyrics written by Roger Waters, in tribute to former band member Syd Barrett, and music written by Waters, Richard Wright, and David Gilmour. It was first performed on their 1974 tour.[1] It was recorded for the 1975 concept album Wish You Were Here. The song was intended to be a side-long composition like "Atom Heart Mother" and "Echoes," but the song grew longer than a single side of vinyl would allow. It was split into two parts and used to bookend the album. The name of the song is a reference to Syd Barrett: Shine on You crazy Diamond.

The Emerald

Thu, 24 May 2007 15:40:18 +0000

A rare type of emerald known as a trapiche emerald is occasionally found in the mines of Colombia. A trapiche emerald exhibits a "star" pattern; it has raylike spokes of dark carbon impurities that give the emerald a six-pointed radial pattern. It is named for the trapiche, a grinding wheel used to process sugarcane in the region. Colombian emeralds are generally the most prized due to their transparency and fire. Some of the most rare emeralds come from three main emerald mining areas in Colombia: Muzo, Coscuez, and Chivor. Fine emeralds are also found in other countries, such as Zambia, Brazil, Zimbabwe, Madagascar, Pakistan, India, Afghanistan and Russia. The value of an emerald depends on cut, color, clarity, and carat. The characteristics of Colombian emeralds set the highest standards of quality Emerald is regarded as the traditional birthstone for May, as well as the traditional gemstone for the astrological signs of Taurus and Cancer

Shine on you crazy diamonds!

Fri, 01 Jun 2007 12:43:07 +0000

Shine On You Crazy Diamond" is an epic nine-part Pink Floyd composition with lyrics written by Roger Waters, in tribute to former band member Syd Barrett, and music written by Waters, Richard Wright, and David Gilmour. It was first performed on their 1974 tour.[1] It was recorded for the 1975 concept album Wish You Were Here. The song was intended to be a side-long composition like "Atom Heart Mother" and "Echoes," but the song grew longer than a single side of vinyl would allow. It was split into two parts and used to bookend the album. The name of the song is a reference to Syd Barrett: Shine on You crazy Diamond.

Happy Feet: It's raining penguins.

Fri, 08 Jun 2007 12:43:06 +0000

Penguins live in colonies in the Antarctic, in freezing temperatures. No tap dancing in this animation though. Penguins are are a group of aquatic, flightless birds living almost exclusively in the Southern Hemisphere. The largest living species is the Emperor Penguin. Most penguins feed on krill, fish, squid, and other forms of sealife caught while swimming underwater. They spend half of their life on land and half in the oceans. Penguins seem to have no fear of humans and have approached groups of explorers without hesitation. This is probably on account of there being no land predators in Antarctica or the nearby offshore islands that prey on or attack penguins. Instead, penguins are at risk at sea from predators such as the leopard seal. Penguins are popular around the world, primarily for their unusually upright, waddling pace and (compared to other birds) lack of fear of humans. Their striking black and white plumage is often likened to a tuxedo suit and generates humorous remarks about the bird being "well dressed". Perhaps in reaction to this cutesy stereotype, fictional penguins are occasionally presented as grouchy or even sinister. Penguins have also been the subject of many books and documentary films such as Happy Feet and Surf's Up, both CGI-Animated Animal Adventure Films, March of the Penguins, a documentary based on the migration process of penguins, and a parody film entitled Farce of the Penguins. Mistakenly, some artists and writers have penguins based in the North Pole. French Pingouin, German Pinguin

It's raining penguins

Fri, 08 Jun 2007 13:10:07 +0000

Aquarium 1

Tue, 19 Jun 2007 14:40:08 +0000

Aquaria can can come in more creative flavors. Aquariums have been fashioned into coffee tables, sinks, and even toilets. Another such example is the Macquarium, an aquarium made from the shell of an Apple Macintosh computer A kreisel tank is a circular aquarium designed to hold delicate animals such as jellyfish

Balloons over the superbowl stadium

Fri, 22 Jun 2007 14:13:07 +0000

Wow! 8000 balloons flying away in to the sky!

Fish Tank #2

Tue, 26 Jun 2007 12:10:09 +0000

Here's another great looking fish tank, featuring the angel shark,blue tang,boccacio,blue marlin,codfish and sheephead.

Ruby,Ruby,Ruby!!

Thu, 28 Jun 2007 13:13:06 +0000

,No, not the Kaiser Chiefs this time: it's the original gemstone: Ruby is a red gemstone that varies from a light pink to a blood red, a variety of the mineral corundum (aluminium oxide). The color is caused mainly by chromium. Its name comes from ruber, Latin for red. Natural rubies are exceptionally rare[specify], but synthetic rubies (sometimes called created ruby) can be manufactured fairly cheaply. Other varieties of gem-quality corundum are called sapphires. It is considered one of the four precious stones, together with the sapphire, the emerald and the diamond. Rubies are mined in Africa, Asia, Australia, Greenland, Madagascar and North Carolina. They are most often found in Myanmar (Burma), Sri Lanka, Kenya, Madagascar, and Cambodia, but they have also been found in the U.S. states of Montana, North Carolina and South Carolina. The Mogok Valley in Upper Myanmar has produced some of the finest rubies but, in recent years, very few good rubies have been found there. The unique color in Myanmar (Burmese) rubies is described as "pigeon’s blood". They are known in the trade as “Mogok” rubies. In central Myanmar the area of Mong Hsu also produces rubies. The latest ruby deposit to be found in Myanmar is situated in Nam Ya. In 2002 rubies were found in the Waseges River area of Kenya. Sometimes spinels are found along with rubies in the same rocks and are mistaken for rubies. However, fine red spinels may approach the average ruby in value.

Underwater scene

Fri, 29 Jun 2007 11:43:06 +0000

8O different kinds of fish swimming around the bottom of the sea

The Star-Spangled Banner

Mon, 02 Jul 2007 14:13:07 +0000

O say, can you see, by the dawn’s early light, What so proudly we hailed at the twilight's last gleaming, Whose broad stripes and bright stars, through the perilous fight O’er the ramparts we watched, were so gallantly streaming? And the rockets’ red glare, the bombs bursting in air Gave proof through the night that our flag was still there; O say, does that star-spangled banner yet wave O’er the land of the free and the home of the brave? [show]Second, third and fourth verses of The Star-Spangled Banner On the shore, dimly seen thro’ the mist of the deep, Where the foe’s haughty host in dread silence reposes, What is that which the breeze, o’er the towering steep, As it fitfully blows, half conceals, half discloses? Now it catches the gleam of the morning’s first beam, In full glory reflected, now shines on the stream ’Tis the star-spangled banner. Oh! long may it wave O’er the land of the free and the home of the brave! And where is that band who so vauntingly swore That the havoc of war and the battle’s confusion A home and a country should leave us no more? Their blood has washed out their foul footsteps' pollution. No refuge could save the hireling and slave From the terror of flight, or the gloom of the grave, And the star-spangled banner in triumph doth wave O’er the land of the free and the home of the brave. Oh! thus be it ever, when freemen shall stand Between their loved homes and the war’s desolation, Blest with vict’ry and peace, may the Heav’n-rescued land Praise the Power that hath made and preserved us a nation! Then conquer we must, when our cause it is just, And this be our motto: "In God is our Trust" And the star-spangled banner in triumph shall wave O’er the land of the free and the home of the brave.

Multicolor Fish

Thu, 05 Jul 2007 14:13:07 +0000

Watch these fish swim around. They have all the colors of the rainbow. Another aquarium, featuring sharks and fish swimming around in a coral reef

How Viagra Works (XL)

Mon, 23 Jul 2007 12:34:08 +0000

Pulp Fiction : Adrenalin shot straight to the heart (XL)

Mon, 23 Jul 2007 12:52:14 +0000

Blood clotting is a tricky business (XL)

Mon, 23 Jul 2007 12:52:14 +0000

Italian Firefly (long version)

Mon, 23 Jul 2007 13:13:08 +0000

Radioactive Fish

Sat, 28 Jul 2007 08:43:21 +0000

Beautiful animation of fish swimming in a beautiful surrounding in the sea. But when you look closer you see a barrel of toxic waste.. What happened to these poor fishes??

The Virtual Aquarium

Thu, 02 Aug 2007 13:16:25 +0000

Welcome to the virtual aquarium! Watch these fish swim around. They have all the colors of the rainbow.