Insulin-like growth factor 1 is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Last reviewed on 2026-01-04. Where a claim depends on a specific study, the study is described rather than over-claimed.
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。
Storage claims vary across suppliers, and published stability data for specific formulations are limited. Extrapolating from related peptides is common but not a substitute for direct measurement. For research use, documentation such as a certificate of analysis is often requested to confirm identity and purity. What constitutes an acceptable purity threshold depends on the intended application. Open questions remain about how temperature excursions during shipping affect long-term peptide integrity. Independent verification by an end user is not routinely reported.
Lyophilized tesamorelin is generally stored refrigerated at 2 to 8 degrees Celsius, protected from light and moisture. Peptides in this class are often kept frozen at minus 20 degrees Celsius for longer periods. Reconstituted solutions are typically used within a defined window because hydrolysis and oxidation proceed faster in liquid form. Container material and headspace also influence how long a preparation retains its expected profile. Specific stability figures depend on concentration and buffer composition.
| 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 |
监管记录显示,特沙莫瑞林于 2010 年在美国首次获得批准,用于人类免疫缺陷病毒感染相关的脂肪营养不良患者。批准依据来自降低内脏脂肪的临床试验,而非体重或瘦体重的普遍改善。后续出现了不同制剂版本,但其核心适应症保持一致。关于长期心血管结局和死亡率影响,现有证据仍不充分。
在临床研究之外,特沙莫瑞林常被讨论为生长激素分泌促进剂,但这一说法需要限定。它并不等同于生长激素本身,也不属于普通减重药物。部分研究关注其减少腹部脂肪和改善脂质谱的潜力,另一些研究则关注胰岛素抵抗和 IGF-1 升高等信号。这些效应的临床意义仍在评估中,尚未形成统一结论。
Binding of tesamorelin to the growth hormone-releasing hormone receptor on anterior pituitary somatotrophs activates a Gs protein pathway, raises cyclic AMP, and triggers release of stored growth hormone into the bloodstream. Because the analogue resists dipeptidyl peptidase-4, its plasma residence time exceeds that of native GHRH, producing a larger and more sustained secretory signal. The released growth hormone then acts on the liver and peripheral tissues to raise insulin-like growth factor 1, which feeds back on the hypothalamus and pituitary. This axis explains both the intended effects on fat distribution and the biological markers used to track them.
Studies of the compound rely on imaging and laboratory endpoints rather than on symptoms alone. Visceral adipose tissue is usually quantified by computed tomography or magnetic resonance imaging at the level of the abdomen, with waist circumference serving as a cheaper but less specific proxy. Blood work tracks insulin-like growth factor 1, fasting glucose, glycated hemoglobin, and lipid fractions. In the pivotal trials the imaging endpoint fell by roughly fifteen to twenty percent over six months, subcutaneous fat changed little, and the visceral fat returned toward baseline after treatment stopped, a pattern that shapes how clinicians discuss durability.
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.
Several related peptides act on the same receptor, including sermorelin, a shorter GHRH fragment, and modified analogs such as CJC-1295 and modified GRF(1-29) that are common in research settings rather than approved products. Tesamorelin differs from growth hormone itself in that it acts upstream, prompting the pituitary to release the hormone through physiological signaling rather than supplying it directly. Terminology in the literature distinguishes GHRH analogs, growth hormone secretagogues, and recombinant growth hormone, although popular discussion often blurs these categories together. Precise naming matters when comparing study results.
=== Women of color === The war on drugs also plays a negative role in the lives of women of color. The number of black women imprisoned in the United States increased at a rate more than twice that of black men, over 64% from 1986 to 1991. During that same period, the percentage of females incarcerated for drug-related offenses more than doubled. In 1989, black and white women had similar levels of drug use during pregnancy. However, black women were 10 times as likely as white women to be reported to a child welfare agency for prenatal drug use. In 1997, of women in state prisons for drug-related crimes, forty-four percent were Hispanic, thirty-nine percent were black, and twenty-three percent were white, quite different from the racial make up shown in percentages of the United States as a whole. Statistics in England, Wales, and Canada are similar. Women of color who are implicated in drug crimes are "generally poor, uneducated, and unskilled; have impaired mental and physical health; are victims of physical and sexual abuse and mental cruelty; are single mothers with children; lack familial support; often have no prior convictions; and are convicted for a small quantity of drugs". Additionally, these women typically have an economic attachment to, or fear of, male drug traffickers, creating a power paradigm that sometimes forces their involvement in drug-related crimes. Though there are programs to help them, women of color are usually unable to take advantage of social welfare institutions in America due to regulations.
The notochord is the defining feature (synapomorphy) of chordates, and was present throughout life in many of the earliest chordates. Although the stomochord of hemichordates was once thought to be homologous or from a common lineal origin, it is now viewed as analogous, convergent, or from a different lineal origin. Pikaia appears to have a proto-notochord, and notochords are present in several basal chordates such as Haikouella, Haikouichthys, and Myllokunmingia, all from the Cambrian. The Ordovician oceans included many diverse species of Agnatha and early Gnathostomata which possessed notochords, either with attached bony elements or without, most notably the conodonts, placoderms, and ostracoderms. Even after the evolution of the vertebral column in chondrichthyes and osteichthyes, these taxa remained common and are well represented in the fossil record. Several species (see list below) have reverted to the primitive state, retaining the notochord into adulthood, though the reasons for this are not well understood. Scenarios for the evolutionary origin of the notochord were comprehensively reviewed by Annona, Holland, and D'Aniello (2015). They point out that, although many of these ideas have not been well supported by advances in molecular phylogenetics and developmental genetics, two of them have actually been revived under the stimulus of modern molecular approaches:
== Definition == Vitamin B12 is a coordination complex of cobalt, which occupies the center of a corrin ligand and is further bound to a benzimidazole ligand and adenosyl group. Several related species behave similarly to function as vitamins. This collection of compounds is sometimes referred to as "cobalamins". These chemical compounds have a similar molecular structure, each of which shows vitamin activity in a vitamin-deficient biological system. They are referred to as vitamers having vitamin activity as a coenzyme, meaning that its presence is required for some enzyme-catalyzed reactions.
Behavioral endocrinology is a branch of endocrinology that studies the Neuroendocrine system and its effects on behavior. Behavioral endocrinology studies the biological mechanisms that produce behaviors, this gives insight into the evolutionary past. The field has roots in ethology, endocrinology and psychology.
== Experimental atomic gas phase chemistry == Interest in copernicium's chemistry was sparked by predictions that it would have the largest relativistic effects in the whole of period 7 and group 12, and indeed among all 118 known elements. Copernicium is expected to have the ground state electron configuration [Rn] 5f14 6d10 7s2 and thus should belong to group 12 of the periodic table, according to the Aufbau principle. As such, it should behave as the heavier homologue of mercury and form strong binary compounds with noble metals like gold. Experiments probing the reactivity of copernicium have focused on the adsorption of atoms of element 112 onto a gold surface held at varying temperatures, in order to calculate an adsorption enthalpy. Owing to relativistic stabilization of the 7s electrons, copernicium shows radon-like properties. Experiments were performed with the simultaneous formation of mercury and radon radioisotopes, allowing a comparison of adsorption characteristics. The first chemical experiments on copernicium were conducted using the 238U(48Ca,3n)283Cn reaction. Detection was by spontaneous fission of the claimed parent isotope with half-life of 5 minutes. Analysis of the data indicated that copernicium was more volatile than mercury and had noble gas properties. However, the confusion regarding the synthesis of copernicium-283 has cast some doubt on these experimental results.
Sources: en.wikipedia.org
Steel belts are generally made from carbon steel or stainless steel which has been alloyed or treated depending on the application. Compared to plastic belts, steel belts are generally more expensive upfront, but it can offer better durability. Over time, a steel belt may develop deformations or curvature due to wear and tear. These deformations can be rectified through various methods such as shot peening to flatten out the cross curvature of deformed steel belts. This process can be performed on-site without interrupting production. The two main systems using steel belts are single-belt and double-belt systems. Single-belt systems are appropriate for manufacturing single-sided products such as pastilles, flakes, strips, and sheets. The double-belt system can manufacture the top and bottom of a product simultaneously, such as in chemical, rubber, laminate, and composite material processing operations.
Except for the president of the Senate (who is the vice president), the Senate elects its own officers, who maintain order and decorum, manage and schedule the legislative and executive business of the Senate, and interpret the Senate's rules, practices and precedents. Many non-member officers are also hired to run various day-to-day functions of the Senate.
Antimony-125 decays with a half-life of over two years to 125mTe which itself decays with a half-life of almost two months via isomeric transition to the ground state. While its relatively short half-life and the significant gamma emissions (144.77 keV) of its daughter nuclide make usage in an RTG less attractive, Sb-125 could deliver a relatively high power density of 3.4 Wthermal/g. Fluoride volatility can recover antimony as the mildly volatile (solid at room temperature) antimony trifluoride or the more volatile (boiling point 422.6 K (149.5 °C; 301.0 °F)) antimony pentafluoride.
Aminoglycoside antibiotics (gentamicin) Antiepileptics (such as carbamazepine, phenytoin and valproic acid) Mood stabilisers, especially lithium citrate Antipsychotics (such as pimozide and clozapine) Digoxin Ciclosporin, tacrolimus in organ transplant recipients TDM increasingly proposed for a number of therapeutic drugs, e.g. many antibiotics, small molecule tyrosine kinase inhibitors and other targeted anticancer agents, TNF inhibitors and other biological agents, antifungal agents, antiretroviral agents used in HIV infection, psychiatric drugs etc.
Sources: en.wikipedia.org
== Limitations == Although the Ka/Ks ratio is a good indicator of selective pressure at the sequence level, evolutionary change can often take place in the regulatory region of a gene which affects the level, timing or location of gene expression. Ka/Ks analysis will not detect such change. It will only calculate selective pressure within protein coding regions. In addition, selection that does not cause differences at an amino acid level—for instance, balancing selection—cannot be detected by these techniques. Another issue is that heterogeneity within a gene can make a result hard to interpret. For example, if Ka/Ks = 1, it could be due to relaxed selection, or to a chimera of positive and purifying selection at the locus. A solution to this limitation would be to apply Ka/Ks analysis across many species at individual codons. The Ka/Ks method requires a rather strong signal in order to detect selection. In order to detect selection between lineages, then the selection, averaged over all sites in the sequence, must produce a Ka/Ks greater than one—quite a feat if regions of the gene are strongly conserved. In order to detect selection at specific sites, then the Ka/Ks ratio must be greater than one when averaged over all included lineages at that site—implying that the site must be under selective pressure in all sampled lineages. This limitation can be moderated by allowing the Ka/Ks rate to take multiple values across sites and across lineages; the inclusion of more lineages also increases the power of a sites-based approach.
In 1869, when Dmitri Mendeleev published his periodic table, the space under iodine was empty; after Niels Bohr established the physical basis of the classification of chemical elements, it was suggested that the fifth halogen belonged there. Before its officially recognized discovery, it was called "eka-iodine" (from Sanskrit eka 'one') to imply it was one space under iodine (in the same manner as eka-silicon, eka-boron, and others). Scientists tried to find it in nature; given its extreme rarity, these attempts resulted in several false discoveries. The first claimed discovery of eka-iodine was made by Fred Allison and his associates at the Alabama Polytechnic Institute (now Auburn University) in 1931. The discoverers named element 85 "alabamine", and assigned it the symbol Ab, designations that were used for a few years. In 1934, H. G. MacPherson of University of California, Berkeley disproved Allison's method and the validity of his discovery. There was another claim in 1937, by the chemist Rajendralal De. Working in Dacca in British India (now Dhaka in Bangladesh), he chose the name "dakin" for element 85, which he claimed to have isolated as the thorium series equivalent of radium F (polonium-210) in the radium series. The properties he reported for dakin do not correspond to those of astatine, and astatine's radioactivity would have prevented him from handling it in the quantities he claimed. Moreover, astatine is not found in the thorium series, and the true identity of dakin is not known.
=== December === 1 December – A Bangladeshi court convicts MP and former minister Tulip Siddiq of corruption charges and sentences her in her absence to two years in custody. Siddiq describes the sentence as "deeply unfair". Richard Hughes resigns as chair of the Office for Budget Responsibility as an inquiry is launched into how details of the November 2025 United Kingdom budget were published 40 minutes before Chancellor Rachel Reeves delivered the statement to Parliament. Former Conservative MPs Jonathan Gullis, Chris Green and Lia Nici defect to Reform UK. Belfast City Council votes in favour of flying the Palestinian flag above City Hall. 2 December – The High Court rejects an emergency legal application by Traditional Unionist Voice to have the Palestinian flag taken down from Belfast City Hall. 3 December – German President Frank-Walter Steinmeier and his wife Elke Büdenbender are welcomed by King Charles III and Queen Camilla on a state visit to the UK, the first to be made by a German leader for 27 years. Markus Campbell-Savours is suspended from the Parliamentary Labour Party for rebelling against the family farm tax. Reform UK launches an investigation into the online activity of Ian Cooper, the leader of Staffordshire County Council, following allegations he posted racist comments online. 5 December – It is announced that Chancellor Rachel Reeves will not face an investigation by ethics adviser Sir Laurie Magnus over whether or not her pre-budget interventions broke the ministerial code.
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。
Refrigeration between 2 and 8 degrees Celsius with protection from light is the common recommendation. Many laboratories choose frozen storage at minus 20 degrees Celsius when the material will not be used soon. Repeated temperature cycling is generally avoided.