垂体受体 raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
This page was last updated on 2026-01-08 and is reviewed periodically as new material appears.
Tesamorelin occupies a narrow position among agents that act on the growth hormone axis. Unlike growth hormone itself, which is given as replacement, it stimulates the pituitary to release the hormone in pulses, so the downstream increase in insulin-like growth factor 1 depends on intact somatotroph function. Other peptides in the same family include shorter GHRH fragments and synthetic secretagogues with different stability profiles. Several points remain unresolved, including whether the reduction in visceral fat translates into fewer cardiovascular events, what happens to metabolic markers after long-term use, and how the drug compares with lifestyle or surgical approaches.
Tesamorelin is a synthetic peptide that belongs to the growth hormone-releasing hormone family and contains the same forty-four amino acid sequence as endogenous GHRH, extended at the amino terminus by a trans-3-hexenoyl group. That small fatty acid modification protects the peptide from rapid cleavage by dipeptidyl peptidase-4, the enzyme that shortens the half-life of native GHRH to only a few minutes. Chemically the compound is produced by solid-phase peptide synthesis, purified by chromatography, and supplied as a sterile lyophilized powder for reconstitution.
Identity and purity are judged through a combination of chromatographic and mass spectrometric techniques. Reversed-phase high-performance liquid chromatography separates the intact peptide from truncated, oxidized, and deamidated variants, and the resulting peak-area percentages yield a purity figure. Electrospray ionization mass spectrometry confirms the expected molecular mass and can expose unanticipated modifications. Amino acid analysis and peptide mapping support sequence fidelity, while water content, pH, sterility, and bacterial endotoxin testing describe the physical and microbiological attributes of a finished lot.
Regulatory position depends on jurisdiction and on the form in which the material is sold. A branded product holds approval in the United States for a defined indication, and prescribing is confined to that label. Material marketed for laboratory research is not evaluated for human use and carries no such clearance. Independent verification therefore rests on certificates of analysis, third-party testing, and documented chain of custody. The substance also appears on the World Anti-Doping Agency prohibited list within the category covering growth hormone-releasing factors.
Lyophilized material is typically held under refrigeration between two and eight degrees Celsius, shielded from light and ambient moisture. Peptides of this size adsorb to glass and plastic, so working procedures often call for low-binding containers and as few transfers as possible. Absorbed water during weighing shifts the apparent mass of a sample, and controlling room humidity reduces that source of error. Once dissolved, solutions are kept cold and used within the interval printed on the accompanying label or certificate. Degradation accelerates markedly in dilute aqueous form.
| Property | Value | Notes |
|---|---|---|
| Peptide class | Synthetic GHRH analogue | 44 residues; N-terminal trans-3-hexenoyl group |
| First approval year | 2010 | United States; HIV-associated abdominal fat accumulation |
| Administration route | Subcutaneous injection | Abdominal site; clinician-administered or self-injected |
| Common synonyms | TH9507; tesamorelin acetate | Development code and acetate salt form |
| Originator | Canadian biotechnology firm | Original developer and regulatory sponsor |
研究背景集中在特定人群的体成分改变，尤其是与脂肪分布异常相关的内脏脂肪堆积。不同地区对它的监管状态与获批适应症并不一致，部分市场仅限特定诊断人群使用。在一般人群中的长期效应、与其他激素的相互作用以及停药后的维持情况仍属开放问题，现有数据不足以给出普遍结论。
tesamorelin 是一种人工合成的四十四肽，序列与内源性生长激素释放激素（GHRH）的 1-44 片段一致，区别在于 N 端加接了一个反式-3-己烯酰基。该修饰抑制二肽基肽酶 IV 的快速切割，从而延长分子在循环中的存留时间。作为肽类分子，它难以经胃肠道吸收，文献中讨论的均是注射途径。分类上通常把它归为 GHRH 类似物，以区别于生长激素本身。
Stimulated growth hormone release leads to hepatic production of insulin-like growth factor 1, a key mediator of many growth hormone effects. In clinical studies, tesamorelin increased IGF-1 levels in a dose-dependent manner, although the response varies among individuals. The drug's effect on visceral fat is thought to involve growth hormone-mediated lipolysis and altered adipocyte metabolism. Muscle mass and lean body mass have also been assessed as secondary outcomes, but changes are generally smaller and less consistent than fat reductions.
Pharmacodynamic studies show that tesamorelin reduces visceral adipose tissue more than subcutaneous adipose tissue in the studied population. This selectivity may relate to differences in blood flow and hormone sensitivity between fat depots. Effects on glucose metabolism and insulin sensitivity have been investigated, with some trials reporting modest changes and others showing stability. The precise relationship between growth hormone exposure, IGF-1 levels, and visceral fat loss remains an active area of analysis.
Clinical investigation has focused on HIV-associated lipodystrophy, a condition in which antiretroviral therapy contributes to abnormal fat distribution. Excess visceral adipose tissue accumulates in the abdomen while peripheral fat may be lost. Tesamorelin was evaluated for reducing this visceral fat depot, with trials measuring changes in abdominal fat by imaging rather than by body weight alone. The rationale rests on the known lipolytic effects of growth hormone. Effects on visceral fat are documented, while long-term outcomes regarding cardiovascular risk remain less clearly established.
Tesamorelin is a synthetic peptide analog of growth hormone-releasing hormone, composed of 44 amino acids. It was designed to retain the biological activity of the native hormone while resisting rapid enzymatic degradation. The compound is classified as a growth hormone secretagogue and belongs to the broader family of hypothalamic releasing factors. In research and clinical settings, it is studied for its ability to stimulate pituitary growth hormone release. Its structure includes a modification at the N-terminus that contributes to an extended half-life relative to native growth hormone-releasing hormone.
Bavaria (The geographically distinct Palatinate, which was part of Bavaria, 1816–1946, is now part of Rheinland Pfalz). Bremen Hamburg Hesse Saxony Thuringia The other 11 states of the Weimar Republic either merged into one another or were separated into smaller entities:
Most cephalopods rely on vision to detect predators and prey and to communicate with one another. Consequently, cephalopod vision is acute: training experiments have shown that the common octopus can distinguish the brightness, size, shape, and horizontal or vertical orientation of objects. The morphological construction gives cephalopod eyes the same performance as shark eyes; however, their construction differs, as cephalopods lack a cornea and have an everted retina. Cephalopods' eyes are also sensitive to the plane of polarization of light. Unlike many other cephalopods, nautiluses do not have good vision; their eye structure is highly developed, but lacks a solid lens. They have a simple "pinhole" eye through which water can pass. Instead of vision, the animal is thought to use olfaction as the primary sense for foraging, as well as locating or identifying potential mates.
== In cryptococcal meningitis == IRIS is particularly problematic in cryptococcal meningitis as IRIS is fairly common and can be fatal. IRIS has been described in immunocompetent hosts who have meningitis caused by Cryptococcus gattii and Cryptococcus neoformans var. grubii, environmental fungi which often affect immunocompetent hosts. Several weeks or even months into appropriate treatment, there is a sudden onset deterioration with worsening meningitis symptoms and progression or development of new neurological symptoms. Magnetic resonance imaging shows increase in the size of brain lesions, and CSF abnormalities (white cell count, protein, glucose) increase. CSF culture is typically sterile, and there is no increase in CSF cryptococcal antigen titer. The increasing inflammation can cause brain injury or be fatal. The general mechanism behind IRIS is increased inflammation as the recovering immune system recognizes the antigens of the fungus as immunosuppression is reversed. Cryptococcal IRIS has three phases:
Subsequent activation of AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid), NMDA (N-methyl-D-aspartate) and kainate subtypes of ionotropic glutamate receptors follows. It is the activation of these receptors that potentiates the pain signal up the spinal cord. This idea, although true, is an oversimplification of pain transduction. A litany of other neurotransmitter and neuromodulators, such as calcitonin gene-related peptide (CGRP), adenosine triphosphate (ATP), brain-derived neurotrophic factor (BDNF), somatostatin, vasoactive intestinal peptide (VIP), galanin, and vasopressin are all synthesized and released in response to noxious stimuli. In addition to each of these regulatory factors, several other interactions between pain-transmitting neurons and other neurons in the dorsal horn have added impact on pain pathways.
Sources: en.wikipedia.org
== Awards and honours == 2014 Royal Microscopical Society Life Sciences Medal 2014 Fellow of Royal Society of Biology 2018 Fellow of Royal Microscopical Society 2019 Biochemical Society Industry and Collaboration Award 2024 Fellow of the Academy of Medical Sciences
24 November – Colin Renfrew, Baron Renfrew of Kaimsthorn, 87, British archaeologist, academic and peer, member of the House of Lords (1991–2021). 1 December – Sir Richard Carew Pole, 13th Baronet, 85, British aristocrat. 2 December – Rosalie Wilkins, Baroness Wilkins, 78, British politician, member of the House of Lords (1999–2015). (death announced on this date) 8 December – Tony Lloyd, Baron Lloyd of Berwick, 95, British jurist, lord of appeal in ordinary (1993–1998), member of the House of Lords (1993–2015). 15 December – Andrew Bennett, 85, British politician, MP (1974–2005). 18 December – Patrick Conolly-Carew, 7th Baron Carew, 86, Irish equestrian and aristocrat, Member of the House of Lords as a hereditary peer (1994–1999).
=== Regulatory exposure limits and handling === The maximum allowable body burden for ingested 210Po is only 1.1 kBq (30 nCi), which is equivalent to a particle massing only 6.8 picograms. The maximum permissible workplace concentration of airborne 210Po is about 10 Bq/m3 (3×10−10 μCi/cm3). The target organs for polonium in humans are the spleen and liver. As the spleen (150 g) and the liver (1.3 to 3 kg) are much smaller than the rest of the body, if the polonium is concentrated in these vital organs, it is a greater threat to life than the dose which would be suffered (on average) by the whole body if it were spread evenly throughout the body, in the same way as caesium or tritium (as T2O). 210Po is widely used in industry, and readily available with little regulation or restriction. In the US, a tracking system run by the Nuclear Regulatory Commission was implemented in 2007 to register purchases of more than 16 curies (590 GBq) of polonium-210 (enough to make up 5,000 lethal doses). The IAEA "is said to be considering tighter regulations ... There is talk that it might tighten the polonium reporting requirement by a factor of 10, to 1.6 curies (59 GBq)." As of 2013, this is still the only alpha emitting byproduct material available, as a NRC Exempt Quantity, which may be held without a radioactive material license. Polonium and its compounds must be handled with caution inside special alpha glove boxes, equipped with HEPA filters and continuously maintained under depression to prevent the radioactive materials from leaking out.
Allatostatins are neuropeptide hormones in insects and crustacea. They have a twofold function: they both inhibit the generation of juvenile hormone and reduce their food intake. They are therefore putative targets for insecticide research.
The fund's devolution to union territories by the union government has no criteria where all the revenue goes to the union government. Some union territories are provided more funds, while others are given less, arbitrarily by the union government. As union territories are directly ruled by the union government, some union territories get more funds from the union government than entitled on per capita and backwardness basis when compared to states. After the introduction of GST, UT-GST is applicable in union territories that do not have a legislative assembly. UT-GST is levied at par with the applicable state GST in the rest of the country which would eliminate the previous lower taxation in the union territories.
Sources: en.wikipedia.org
Safrole is listed as a Table I precursor under the United Nations Convention Against Illicit Traffic in Narcotic Drugs and Psychotropic Substances. Due to their role in the manufacture of MDMA, safrole, isosafrole, and piperonal are Category I precursors under regulation no. 273/2004 of the European Community. In the United States, safrole is currently a List I chemical. The root bark of American sassafras contains a low percentage of steam-volatile oil, which is typically 75% safrole. Attempts to refine safrole from sassafras bark in mass quantities are generally not economically viable due to low yield and high effort. However, smaller quantities can be extracted quite easily via steam distillation (about 10% of dry sassafras root bark by mass, or about 2% of fresh bark). Demand for safrole is causing rapid and illicit harvesting of the Cinnamomum parthenoxylon tree in Southeast Asia, in particular the Cardamom Mountains in Cambodia. However, it is not clear what proportion of illicitly harvested safrole is going toward MDMA production, as over 90% of the global safrole supply (about 2,000 tonnes or 2,200 short tons per year) is used to manufacture pesticides, fragrances, and other chemicals. Sustainable harvesting of safrole is possible from leaves and stems of certain plants, including the roots of camphor seedlings.
=== Electrostatic catalysis === Stabilization of charged transition states can also be by residues in the active site forming ionic bonds (or partial ionic charge interactions) with the intermediate. These bonds can either come from acidic or basic side chains found on amino acids such as lysine, arginine, aspartic acid or glutamic acid or come from metal cofactors such as zinc. Metal ions are particularly effective and can reduce the pKa of water enough to make it an effective nucleophile. Systematic computer simulation studies have established that electrostatic effects give, by far, the largest contribution to catalysis, and can increase the rate of reaction by a factor of up to 107. In particular, it has been found that enzymes provide an environment which is more polar than water, and that ionic transition states are stabilized by fixed dipoles. This is very different from transition state stabilization in water, where the water molecules must pay with "reorganization energy" in order to stabilize ionic and charged states. Thus, catalysis is associated with the fact that the enzyme polar groups are preorganized. The magnitude of the electrostatic field exerted by an enzyme's active site has been shown to be highly correlated with the enzyme's catalytic rate enhancement. Binding of substrate usually excludes water from the active site, thereby lowering the local dielectric constant to that of an organic solvent. This strengthens the electrostatic interactions between the charged/polar substrates and the active sites.
=== Law enforcement === GC–MS is increasingly used for detection of illegal narcotics, and may eventually supplant drug-sniffing dogs.[1] A simple and selective GC–MS method for detecting marijuana usage was recently developed by the Robert Koch Institute in Germany. It involves identifying an acid metabolite of tetrahydrocannabinol (THC), the active ingredient in marijuana, in urine samples by employing derivatization in the sample preparation. GC–MS is also commonly used in forensic toxicology to find drugs and/or poisons in biological specimens of suspects, victims, or the deceased. In drug screening, GC–MS methods frequently utilize liquid-liquid extraction as a part of sample preparation, in which target compounds are extracted from blood plasma.
=== Taxonomy === The species A. maxima and A. platensis were once classified in the genus Spirulina. The common name, spirulina, refers to the dried biomass of A. platensis, which belongs to photosynthetic bacteria that cover the groups Cyanobacteria and Prochlorophyta. Scientifically, a distinction exists between spirulina and the genus Arthrospira, for which the two species were originally proposed. Species of Arthrospira have been isolated from alkaline brackish and saline waters in tropical and subtropical regions. Among the various species included in the genus Arthrospira, A. platensis is the most widely distributed and is mainly found in Africa, but also in Asia. The term "spirulina" (without italicizing and usually without capitalization) remains in use for historical reasons. In 2019 it was found that the cultivated species differ too much from the type species of Arthospira to be in the genus, necessitating another batch of renaming to Limnospira to reflect biological reality.
Sources: en.wikipedia.org
It is a laboratory-made peptide of forty-four amino acids whose sequence matches human growth hormone-releasing hormone, with a modified amino terminus. The modification is a short unsaturated fatty acid chain attached to the first residue. This change slows enzymatic breakdown and lengthens the time the peptide stays active in circulation.
The clinical program was designed around HIV-associated lipodystrophy, a condition in which fat accumulates abnormally around the internal organs. Trials enrolled that specific population, so the evidence base covers it rather than the general population. Regulators approved the drug for the studied indication only, and promotion outside it is not permitted.
Growth hormone therapy supplies the finished hormone directly, while this peptide acts upstream and asks the pituitary to secrete its own. That difference means the response depends on a functioning pituitary and on the body's normal feedback loops. It also means the circulating hormone profile is pulsatile rather than a flat, injected level.
Reconstituted solutions are kept cold and used within the period stated on the label or certificate. Repeated warming and cooling cycles should be avoided because they encourage aggregation and gradual loss of potency.