HIV-Mode of action of NNRTIs
NNRTIs are a class of anti-HIV drugs. When one NNRTI is used in combination with other anti-HIV drugs – usually a total of 3 drugs – then this combination therapy can block the replication of HIV in a person's blood.
NNRTIs, sometimes referred to as "Non-Nucleoside Analogues" – or "non-nukes" for short – prevent healthy T-cells in the body from becoming infected with HIV.
When HIV infects a cell in a person's body, it copies it's own genetic code into the cell's DNA. In this way, the cell is then "programmed" to create new copies of HIV. HIV's genetic material is in the form of RNA. In order for it to infect T-cells, it must first convert its RNA into DNA. HIV's reverse transcriptase enzyme is needed to perform this process.
NNRTIs attach themselves to reverse transcriptase and prevent the enzyme from converting RNA to DNA. In turn, HIV's genetic material cannot be incorporated into the healthy genetic material of the cell, and prevents the cell from producing new virus.
Morphine
Morphine (INN) (pronounced /ˈmɔrfiːn/) (MS Contin, MSIR, Avinza, Kadian, Oramorph, Roxanol, Kapanol) is a potent opiate analgesic medication and is considered to be the prototypical opioid. It was discovered in 1804 by Sertürner, first distributed by same in 1817, and first commercially sold by Merck in 1827, which at the time was a single small chemists' shop. It was more widely used after the invention of the hypodermic needle in 1857.
Morphine is the most abundant alkaloid found in opium, the dried sap (latex) derived from shallowly slicing the unripe seedpods of the opium, or common or edible, poppy, Papaver somniferum. Morphine was the first active principle purified from a plant source and is one of at least 50 alkaloids of several different types present in opium, Poppy Straw Concentrate, and other poppy derivatives. Morphine is generally 8 to 17 per cent of the dry weight of opium, although specially-bred cultivars reach 26 per cent or produce little morphine at all, under 1 per cent, perhaps down to 0.04 per cent. The latter varieties, including the 'Przemko' and 'Norman' cultivars of the opium poppy, are used to produce two other alkaloids, thebaine and oripavine, which are used in the manufacture of semi-synthetic and synthetic opioids like oxycodone and etorphine and some other types of drugs. Morphine can be found in low to intermediate concentrations in the Iranian poppy (P. bracteatum), although this poppy is most often used for codeine and thebaine production. Higher, industrially useful concentrations of morphine are found in the oriental poppy (P. orientale). Lower concentrations may be found in a handful of other species in the poppy family, as well as in some species of hops and mulberry trees. Morphine is produced most predominantly early in the life cycle of the plant. Past the optimum point for extraction, various processes in the plant produce codeine, thebaine, and in some cases low quantities of hydromorphone, dihydromorphine, dihydrocodeine, tetrahydrothebaine, and hydrocodone. The human body also produces small amounts of morphine and metabolises it into a number of other active opiates.
In clinical medicine, morphine is regarded as the gold standard, or benchmark, of analgesics used to relieve severe or agonizing pain and suffering. Like other opioids, e.g. oxycodone (OxyContin, Percocet, Percodan), hydromorphone (Dilaudid, Palladone), and diacetylmorphine (heroin), morphine acts directly on the central nervous system (CNS) to relieve pain. Morphine has a high potential for addiction; tolerance and psychological dependence develop rapidly, although physical addiction may take several months to develop.
Stem Cells: Programming and Personalized Medicine
Rudolf Jaenisch is one of the founders of transgenic science (gene transfer to create mouse models of human disease). His lab has produced mouse models leading to new understanding of cancers and various neurological diseases.
He received his doctorate in medicine from the University of Munich in 1967. He came to the Whitehead from the University of Hamburg in Germany, where he was head of the Department of Tumor Virology at the Heinrich Pette Institute.
Jaenisch received the 2002 Robert Koch Prize for Excellence in Scientific Achievement. In 2003, he was awarded the Charles Rodolphe Brupbacher Prize for basic research in oncology and was elected a member of the National Academy of Sciences.
Jaenisch is a fellow of the American Academy of Arts and Sciences and the American Academy of Microbiology, and a member of the American Association for the Advancement of Science
How Anti-depressants Work
Messages pass from neuron to neuron using chemical messengers called neurotransmitters. The messages can pass on information about emotions, behavior, body temperature, appetite, or many other functions. The type of information sent depends on which neurons are activated and what part of the brain is stimulated.
A message passes from a sending neuron to a receiving neuron. The neurotransmitters leave the sending neuron and enter the space between the sending and receiving neurons. This space is called the synapse. The neurotransmitters then hook up to a receptor on the receiving neuron to deliver their message.
Once neurotransmitters have sent their message, they return and can be reabsorbed by the sending neuron in a process called reuptake. Reuptake allows the messengers to be reused. Two of these neurotransmitters are serotonin and norepinephrine. Low levels of serotonin and norepinephrine in the synapse are associated with depression and sadness. Some medications used to treat depression work by increasing the amount of certain neurotransmitters that are available to carry messages.
Each type of antidepressant works on brain chemistry a little differently. All antidepressant medications influence how certain neurotransmitters, especially serotonin and norepinephrine, work in the brain.
SSRIs and tricyclic antidepressants. Antidepressants, such as selective serotonin reuptake inhibitors, or SSRIs, and tricyclic antidepressants, work by slowing or blocking the sending neuron from taking back the released serotonin. In that way, more of this chemical is available in the synapse. The more of this neurotransmitter that is available, the more likely the message is received, and depression is reduced. To learn more about how these antidepressants work, see Tricyclic Antidepressants (TCAs) and Selective Serotonin Reuptake Inhibitors (SSRIs).
Collagen
Collagen is a group of naturally occurring proteins. In nature, it is found exclusively in animals, especially in the flesh and connective tissues of mammals. It is the main component of connective tissue, and is the most abundant protein in mammals, making up about 25% to 35% of the whole-body protein content. Collagen, in the form of elongated fibrils, is mostly found in fibrous tissues such as tendon, ligament and skin, and is also abundant in cornea, cartilage, bone, blood vessels, the gut, and intervertebral disc.
In muscle tissue it serves as a major component of endomysium. Collagen constitutes 1% to 2% of muscle tissue, and accounts for 6% of the weight of strong, tendinous muscles. Gelatin, which is used in food and industry, is collagen that has been irreversibly hydrolyzed.
Colony-stimulating factor
Colony-stimulating factors (CSFs) are secreted glycoproteins which bind to receptor proteins on the surfaces of hemopoietic stem cells and thereby activate intracellular signaling pathways which can cause the cells to proliferate and differentiate into a specific kind of blood cell (usually white blood cells, for red blood cell formation see erythropoietin).
They may be synthesized and administered exogenously. However, such molecules can at a latter stage be detected, since they differ slightly from the endogenous ones in e.g. features of posttranslational modification.
Hemopoietic stem cells were cultured on a so-called semi solid matrix which prevents cells from moving around, so that if a single cell starts proliferating, all of the cells derived from it will remain clustered around the spot in the matrix where the first cell was originally located, and these are referred to as "colonies." It was therefore possible to add various substances to cultures of hemopoietic stem cells and then examine which kinds of colonies (if any) were "stimulated" by them.
The substance which was found to stimulate formation of colonies of macrophages, for instance, was called macrophage colony-stimulating factor, for granulocytes, granulocyte colony-stimulating factor, and so on.
The colony-stimulating factors are soluble, in contrast to other, membrane-bound substances of the hematopoietic microenvironment. This is sometimes used as the definition of CSFs. They transduce by paracrine, endocrine or autocrine signaling.
