This is a working overview of GHRH 类似物, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2025-12-29 and is reviewed periodically as new material appears.
作用位置在垂体前叶。tesamorelin 与 GHRH 受体结合后激活腺苷酸环化酶，升高细胞内 cAMP，再经蛋白激酶 A 通路促进生长激素的合成与释放。由于它作用于内源调控节点，生长激素仍以脉冲方式分泌，而不是被持续抬升到固定水平。生长激素随后在肝脏等组织诱导胰岛素样生长因子 1 产生，构成完整的生长激素轴响应。
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。
Physicochemical behavior is dominated by the peptide backbone. The molecule is hydrophilic and carries a net positive charge near neutral pH, owing to several arginine and lysine residues. In solution it adopts a largely unstructured conformation, and aggregation is a known concern for peptide products of this size. Oxidation of methionine and deamidation of asparagine or glutamine residues are the principal chemical degradation routes. These liabilities shape how the material is formulated, handled, and analyzed, and they explain why lyophilized presentations are common in research settings.
Tesamorelin is a synthetic peptide analog of growth hormone-releasing hormone, built from 44 amino acids. Its sequence follows the natural human GHRH(1-44) backbone, with a trans-3-hexenoyl group attached to the N-terminal tyrosine. This modification blocks recognition by dipeptidyl peptidase IV, the enzyme that rapidly truncates the native hormone in circulation. The result is a molecule with a substantially longer plasma residence time than unmodified GHRH, which makes it practical for clinical and laboratory study.
Receptor-level activity begins when the peptide binds the GHRH receptor, a class B G-protein-coupled receptor found on pituitary somatotroph cells. Occupancy triggers Gs-mediated activation of adenylyl cyclase and a rise in intracellular cyclic AMP, which in turn promotes synthesis and pulsatile release of growth hormone. Because the compound acts upstream of the growth hormone axis rather than supplying hormone directly, its effect depends on intact pituitary function. Binding studies in cell culture and animal models have established this pathway; the detailed kinetics of receptor recycling in humans remain less well characterized.
| 性质 | 取值 | 备注 |
|---|---|---|
| 分子类型 | 合成四十四肽 | GHRH 类似物 |
| N 端修饰 | 反式-3-己烯酰基 | 延缓酶切 |
| 分子量 | 约 5135 Da | 依序列与修饰 |
| 受体靶点 | 垂体 GHRH 受体 | 经 cAMP 通路 |
| 常见同义名 | GHRH(1-44) 类似物 | 文献通用称法 |
After injection, the peptide binds receptors on somatotroph cells in the anterior pituitary. Receptor activation raises intracellular cyclic AMP and triggers release of stored growth hormone into the bloodstream. Because the compound works through the body's own regulatory system, growth hormone pulses retain much of their normal feedback control. Repeated administration also raises insulin-like growth factor 1, a hormone produced mainly in the liver. Investigators treat that rise as a marker that the pituitary axis has been engaged.
Clinical study of tesamorelin has centered on adults with HIV-associated lipodystrophy, a condition in which abdominal fat accumulates while peripheral fat is lost. In controlled trials, treated participants showed reductions in visceral adipose tissue measured by imaging, alongside modest shifts in some lipid values. Effects on subcutaneous fat were smaller and less consistent across studies. Whether these changes translate into fewer cardiovascular events remains an open question, because the trials were not designed or powered to answer it.
Tesamorelin is a synthetic peptide of 44 amino acids that reproduces the sequence of human growth hormone-releasing hormone (GHRH) and carries a trans-3-hexenoyl group on its N-terminal tyrosine. That small fatty-acid modification blocks cleavage by dipeptidyl peptidase-4, the enzyme that rapidly degrades native GHRH in plasma. The result is a molecule with a longer circulating half-life than the natural hormone while retaining the same receptor target. It is supplied as a lyophilized powder for reconstitution and belongs to the broader class of GHRH analogs studied for effects on pituitary growth hormone secretion.
Development work on the compound, originally designated TH9507, focused on conditions in which reduced growth hormone signaling is thought to contribute to altered body composition. The United States Food and Drug Administration approved it in 2010 for the treatment of excess visceral abdominal fat in adults with human immunodeficiency virus infection and lipodystrophy. Later research examined other populations, including adults with mild cognitive impairment, where a large trial did not meet its primary endpoints. This mixed record illustrates how a single mechanism can produce clear effects in one setting and inconclusive results in another.
Tesamorelin is a synthetic analog of growth hormone-releasing hormone, a peptide hormone produced by the hypothalamus. The molecule retains the 44-amino-acid sequence of human GHRH and carries a trans-3-hexenoyl modification at its N-terminus. This modification increases resistance to enzymatic degradation and extends the peptide's functional stability relative to native GHRH. The compound is supplied as a lyophilized powder for reconstitution and subcutaneous administration in clinical settings. Its development code was TH9507, and it belongs to the GHRH analog class. It is not a growth hormone product; instead, it acts upstream to stimulate endogenous growth hormone release.
Clinical interest in tesamorelin arose from the need to address visceral adiposity in people living with HIV. Antiretroviral therapy improved survival but was associated in some patients with central fat accumulation, altered lipid profiles, and metabolic complications. This condition, often called HIV-associated lipodystrophy, involves excess visceral adipose tissue that is difficult to manage through diet and exercise alone. Investigators evaluated tesamorelin because GHRH analogs can stimulate growth hormone secretion and influence fat distribution without direct liposuction or invasive procedures.
A Phase 3 program led to regulatory approval in the United States in 2010 for reduction of excess visceral abdominal fat in adults with HIV and lipodystrophy. Subsequent studies examined effects on liver fat, muscle area, and metabolic markers, with mixed findings for some endpoints. Long-term cardiovascular outcomes and effects on mortality remain uncertain because most trials were relatively short and focused on imaging-based fat measurements. Use in populations without HIV has been studied experimentally but is not part of the approved indication.
=== Similar species === Several species may be confused with A. campestris. The most dangerous confusion may be with the deadly Amanita virosa (a 'destroying angel') or the deadly Amanita hygroscopica (pink-gilled destroying angel). Amanita species may be distinguished from Agaricus by a volva at the base, remnants of a universal veil. Such a veil may also be seen surrounding adjacent smaller button mushrooms, if present. It's recommended to look for smaller sibling buttons nearby, and slice one of them lengthwise to examine their anatomy. They may also be distinguished by a white or off-white spore print while mushrooms in the family Agaricacea are dark brown. In the United States, the poisonous Agaricus californicus and A. hondensis may be similar. White Clitocybe species that also grow in grassy places may be toxic. A less serious, but more common, confusion is with Agaricus xanthodermus (the yellow stainer), which causes gastrointestinal problems in many people. A. arvensis (the horse mushroom) is very similar and is an excellent edible. It is nearly identical (except microscopically) to the edible species Agaricus andrewii and A. solidipes.
The optical lens has been playing a critical role in almost all areas of science and technology since its invention about 3000 years ago. With the advances in micro- and nanofabrication techniques, continued miniaturization of the conventional optical lenses has always been requested for various applications such as communications, sensors, data storage and a wide range of other technology-driven and consumer-driven industries. Specifically, ever smaller sizes, as well as thinner thicknesses of micro lenses, are highly needed for subwavelength optics or nano-optics with extremely small structures, particularly for visible and near-IR applications. Also, as the distance scale for optical communications shrinks, the required feature sizes of micro lenses are rapidly pushed down. Recently, the excellent properties of newly discovered graphene oxide provide novel solutions to overcome the challenges of current planar focusing devices. Specifically, giant refractive index modification (as large as 10^-1), which is one order of magnitude larger than the current materials, between graphene oxide (GO) and reduced graphene oxide (rGO) have been demonstrated by dynamically manipulating its oxygen content using the direct laser writing (DLW) method. As a result, the overall lens thickness can be potentially reduced by more than ten times. Also, the linear optical absorption of GO is found to increase as the reduction of GO deepens, which results in transmission contrast between GO and rGO and therefore provides an amplitude modulation mechanism.
An example of an RNA aptamer therapy includes Pegaptanib (aka Macugen ® ), the only FDA-approved RNA aptamer treatment. Originally approved in 2004 to treat age-related macular degeneration, Pegaptanib is a 28 nucleotide RNA aptamer that acts as a VEGF antagonist. However, it is not as effective as antibody-based treatments such as bevacizumab and ranibizumab. Another example of an RNA aptamer therapeutic is NOX-A12, a 45 nucleotide RNA aptamer that is in clinical trials for chronic lymphocytic leukemia, pancreatic cancer, as well as other cancers. NOX-A12 acts as antagonist for CXCL12/SDF-1, a chemokine involved in tumor growth.
== Production == The novel was partly inspired by Stephenson's involvement with the Clock of the Long Now project, to which he contributed three pages of sketches and notes. A separate compact disc, entitled IOLET: Music from the World of Anathem, containing eight experimental vocal compositions by David Stutz, was sold separately through CD Baby and the Long Now Foundation, with profits going to The Clock of the Long Now project. To create the world of Arbre, Stephenson constructs new vocabulary. In order to familiarize the reader with the new words, many of which are analogous to English, Latin or Greek words and ideas, a glossary is included at the end of the book. Each chapter begins with a definition of one of these words, which usually relates to the chapter in some way. In addition, the Orth language spoken by the characters was created by Jeremy Bornstein at the author's request, and has been documented. The word anathem was invented by Stephenson, based on the word anthem and the Greek word anathema. In the book, an anathem is a mathic ritual by which one is expelled from the mathic world.
Hannakins Farm mixed-use park to the north-west, includes several playing fields Mill Meadows on the eastern side of the town Norsey Wood, another nature reserve to the north-east Queens Park Country Park, also to the north-west, is managed as a local nature reserve. Norsey Wood and Mill Meadows are green wedges, in that they extend from the open countryside to the centre of town; they are environmentally valuable and sensitive, and have, in part or whole, been designated as Sites of Special Scientific Interest. Centuries of grazing have created the ideal conditions for a diversity of wild flowers, fungi, insects and invertebrates, many of which are very rare.
Sources: en.wikipedia.org
Harrington, William J.; Sprague, Charles C.; Minnich, Virginia; Moore, Carl V.; Aulvin, Robert C.; Dubach, Reubenia (1953-03-01). "Immunologic mechanisms in idiopathic and neonatal thrombocytopenic purpura". Annals of Internal Medicine. 38 (3): 433–69. doi:10.7326/0003-4819-38-3-433. ISSN 0003-4819. PMID 13031392. Hemoglobin E
Cocaine is a central nervous system (CNS) stimulant and tropane alkaloid, derived primarily from the leaves of two coca species native to South America: Erythroxylum coca and E. novogranatense. The leaves are processed into cocaine paste, a crude mixture of coca alkaloids, from which cocaine base is isolated and then converted to cocaine hydrochloride. Although total synthesis is possible, it is complex and not used for production. Historically, cocaine was a standard topical medication used as a local anesthetic with intrinsic vasoconstrictor properties. However, its high abuse potential, adverse effects, and cost have limited its medical use and led to its replacement by alternative medicines. Street cocaine is commonly snorted, injected, or smoked as crack cocaine; its effects last up to 90 minutes depending on the route of administration. Pharmacologically, cocaine acts as a serotonin–norepinephrine–dopamine reuptake inhibitor (SNDRI), producing reinforcing effects such as euphoria, increased alertness, concentration, libido, and reduced fatigue and appetite. Cocaine has numerous adverse effects. Acute use can cause vasoconstriction, tachycardia, hypertension, hyperthermia, or seizures, while overdose may lead to stroke, heart attack, or sudden cardiac death. It also produces a spectrum of psychiatric symptoms, including agitation, paranoia, anxiety, irritability, psychosis, hallucinations, delusions, violence, and suicidal or homicidal thinking. Prenatal exposure poses risks to fetal development.
Humans and also carry many interferon pseudogenes, including the entire nu family (IFNNΨ), an ortholog of IFNW1 (IFNWXΨ), a singular delta pseudogene (IFNDΨ), and a few members of the alpha and omega families. Many of these loci are also pseudogenes in other mammals. Consult the HGNC website for a full list of officially named genes and pseudogenes.
==== Receptor and ion channel targets ==== Caffeine is an antagonist of adenosine A2A receptors, and knockout mouse studies have specifically implicated antagonism of the A2A receptor as responsible for the wakefulness-promoting effects of caffeine. Antagonism of A2A receptors in the ventrolateral preoptic area (VLPO) reduces inhibitory GABA neurotransmission to the tuberomammillary nucleus, a histaminergic projection nucleus that activation-dependently promotes arousal. This disinhibition of the tuberomammillary nucleus is the downstream mechanism by which caffeine produces wakefulness-promoting effects. Caffeine is an antagonist of all four adenosine receptor subtypes (A1, A2A, A2B, and A3), although with varying potencies. The affinity (KD) values of caffeine for the human adenosine receptors are 12 μM at A1, 2.4 μM at A2A, 13 μM at A2B, and 80 μM at A3. Antagonism of adenosine receptors by caffeine also stimulates the medullary vagal, vasomotor, and respiratory centers, which increases respiratory rate, reduces heart rate, and constricts blood vessels. Adenosine receptor antagonism also promotes neurotransmitter release (e.g., monoamines and acetylcholine), which endows caffeine with its stimulant effects; adenosine acts as an inhibitory neurotransmitter that suppresses activity in the central nervous system. Heart palpitations are caused by blockade of the A1 receptor. Because caffeine is both water- and lipid-soluble, it readily crosses the blood–brain barrier that separates the bloodstream from the interior of the brain.
Sources: en.wikipedia.org
== Pathophysiology == Overproduction of collagen is thought to result from an autoimmune dysfunction, in which the immune system starts to attack the kinetochore of the chromosomes. This would lead to genetic malfunction of nearby genes. T cells accumulate in the skin; these are thought to secrete cytokines and other proteins that stimulate collagen deposition. Stimulation of the fibroblast, in particular, seems to be crucial to the disease process, and studies have converged on the potential factors that produce this effect.
A notable example is the calorimeter of the NA48 experiment at CERN containing about 27 tonnes of liquid krypton. This usage is rare, since liquid argon is less expensive. The advantage of krypton is a smaller Molière radius of 4.7 cm, which provides excellent spatial resolution with little overlapping. The other parameters relevant for calorimetry are: radiation length of X0=4.7 cm, and density of 2.4 g/cm3. Krypton-83 has application in magnetic resonance imaging (MRI) for imaging airways. In particular, it enables the radiologist to distinguish between hydrophobic and hydrophilic surfaces containing an airway. Although xenon has potential for use in computed tomography (CT) to assess regional ventilation, its anesthetic properties limit its fraction in the breathing gas to 35%. A breathing mixture of 30% xenon and 30% krypton is comparable in effectiveness for CT to a 40% xenon fraction, while avoiding the unwanted effects of a high partial pressure of xenon gas. The metastable isotope krypton-81m is used in nuclear medicine for lung ventilation/perfusion scans, where it is inhaled and imaged with a gamma camera. Krypton-85 in the atmosphere has been used to detect clandestine nuclear fuel reprocessing facilities in North Korea and Pakistan. Those facilities were detected in the early 2000s and were believed to be producing weapons-grade plutonium. Krypton-85 is a medium lived fission product and thus escapes from spent fuel when the cladding is removed. Krypton is used occasionally as an insulating gas between window panes.
"Neats" hope that intelligent behaviour is described using simple, elegant principles (such as logic or optimisation). "Scruffies" expect that it necessarily requires solving a large number of unrelated problems. Neats defend their programs with theoretical rigour, scruffies rely mainly on incremental testing to see if they work. This issue was actively discussed in the 1970s and 1980s. The rise of deep learning may represent a shift toward the scruffies.
Sources: en.wikipedia.org
tesamorelin 属 GHRH 类似物，作用于垂体受体以促进内源生长激素释放；生长激素本身是直接补充的外源激素。两者在给药逻辑、作用位点和反馈调控路径上并不相同。
作为多肽，它难以通过胃肠道吸收，通常需要注射给药。口服会因消化酶降解而失去活性，因此文献中讨论的都是注射途径。
公开研究多集中在内脏脂肪、体成分分布以及与生长激素轴相关的代谢指标。长期安全性和在普通人群中的适用性尚缺乏一致结论。
The principal difference is a chemical cap on the N-terminal tyrosine that prevents rapid enzymatic cleavage. Native GHRH is degraded within minutes in plasma, whereas the modified peptide persists considerably longer. The amino acid backbone otherwise mirrors the natural hormone.