Everything below concerns 生长激素释放激素. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2025-11-19. Where a claim depends on a specific study, the study is described rather than over-claimed.
Tesamorelin is a synthetic peptide that belongs to the growth hormone-releasing hormone (GHRH) family. Its sequence corresponds to the fully active 44-amino-acid form of human GHRH, with a single structural modification: the addition of a trans-3-hexenoyl group at the N-terminus. That modification is not found in the naturally occurring hormone and was introduced deliberately during development to improve stability against enzymatic degradation. The compound is therefore best described as a stabilized analogue rather than a naturally occurring peptide.
The native hormone is produced in the hypothalamus and acts on the anterior pituitary. Binding of GHRH to its receptor stimulates synthesis and release of growth hormone into circulation. Because the analogue retains the receptor-binding region of the parent sequence, it engages the same receptor and triggers the same downstream signaling. The result is increased growth hormone secretion from pituitary cells, which in turn influences hepatic production of insulin-like growth factor 1. This axis is the basis for the compound's measured biological effects.
Interest in this peptide developed because native GHRH has a short circulating lifetime. The N-terminal modification slows cleavage by dipeptidyl peptidase IV, an enzyme that removes the first two residues of many peptides and terminates their activity. Slower degradation means a longer window of receptor stimulation per administration. This design logic parallels other modified peptide hormones, where a small chemical change at a vulnerable site yields a more durable molecule without altering the core mechanism of action.
Tesamorelin is a synthetic peptide that acts as an analog of growth hormone-releasing hormone, a natural hypothalamic signal. Its sequence corresponds to the forty-four amino acid form of the human hormone, with a small acyl group attached near the amino terminus. That modification slows enzymatic breakdown and extends the time the peptide remains active in circulation. The compound was developed as a pharmacological way to raise endogenous growth hormone output rather than supplying the hormone directly.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C221H366N72O67S | Reflects a 44-residue peptide with one N-terminal modification |
| Approximate molecular weight | 5136 Da | Sequence length and single acyl group determine the mass |
| Appearance | White to off-white lyophilized powder | Typical form of a purified synthetic peptide |
| Solubility class | Soluble in water and aqueous buffer | Peptide backbone favors aqueous dissolution |
| Common synonyms | GHRH(1-44) analogue; Egrifta | Descriptive name and approved brand name |
特沙莫瑞林是一种合成肽，其序列与人生长激素释放激素的 44 个氨基酸形式相关。它在 N 端带有反式-3-己烯酰基修饰，这一改动可减缓二肽基肽酶 IV 的降解。该化合物属于生长激素释放激素受体激动剂，可刺激垂体释放生长激素。研究文献通常将其归入合成肽类药物，而非小分子化合物。
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。
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.
In addition to CYP2B6, CYP2A6 may be involved in the metabolism of selegiline to a lesser extent. Birth control pills containing the synthetic estrogen ethinylestradiol and a progestin like gestodene or levonorgestrel have been found to increase peak levels and overall exposure to oral selegiline by 10- to 20-fold. High levels of selegiline can lead to loss of MAO-B selectivity and inhibition of MAO-A as well. This increases susceptibility to side effects and interactions of non-selective monoamine oxidase inhibitors (MAOIs), such as tyramine-induced hypertensive crisis and serotonin toxicity when combined with serotonergic medications. However, this study had a small sample size of four individuals as well as other methodological limitations. The precise mechanism underlying the interaction is unknown, but is likely related to cytochrome P450 inhibition and consequent inhibition of selegiline first-pass metabolism by ethinylestradiol. In contrast to birth control pills containing ethinylestradiol, menopausal hormone therapy with estradiol and levonorgestrel did not modify peak levels of selegiline and only modestly increased overall exposure (+59%). Hence, menopausal hormone therapy does not pose the same risk of interaction as ethinylestradiol-containing birth control pills when taken together with selegiline. Overall exposure to selegiline with oral selegiline has been found to be 23-fold lower in people taking anticonvulsants known to strongly activate drug-metabolizing enzymes. The anticonvulsants included phenobarbital, phenytoin, carbamazepine, and amobarbital.
People with a BMI of over 30 should be counseled on diet, exercise and other relevant behavioral interventions, and set a realistic goal for weight loss. If these goals are not achieved, pharmacotherapy can be offered. The person needs to be informed of the possibility of side-effects and the unavailability of long-term safety and efficacy data. Drug therapy may consist of sibutramine, orlistat, phentermine, diethylpropion, fluoxetine, and bupropion. Evidence is not sufficient to recommend sertraline, topiramate, or zonisamide. In people with a BMI over 40 who fail to achieve their weight loss goals (with or without medication) and who develop obesity-related complications, referral for bariatric surgery may be indicated. The person needs to be aware of the potential complications. Those requiring bariatric surgery should be referred to high-volume referral centers, as the evidence suggests that surgeons who frequently perform these procedures have fewer complications. A clinical practice guideline by the US Preventive Services Task Force (USPSTF) concluded that the evidence is insufficient to recommend for or against routine behavioral counseling to promote a healthy diet in unselected people in primary care settings, but that intensive behavioral dietary counseling is recommended in those with hyperlipidemia and other known risk factors for cardiovascular and diet-related chronic disease. Intensive counseling can be delivered by primary care clinicians or by referral to other specialists, such as nutritionists or dietitians.
Molecular machines are a class of molecules typically described as an assembly of a discrete number of molecular components intended to produce mechanical movements in response to specific stimuli, mimicking macromolecular devices such as switches and motors. Naturally occurring or biological molecular machines are responsible for vital living processes such as DNA replication and ATP synthesis. Kinesins and ribosomes are examples of molecular machines, and they often take the form of multi-protein complexes. Multiple examples of molecular machinery and their components are found in the Protein Data Bank. For the last several decades, scientists have attempted, with varying degrees of success, to miniaturize machines found in the macroscopic world. The first example of an artificial molecular machine (AMM) was reported in 1994, featuring a rotaxane with a ring and two different possible binding sites. In 2016 the Nobel Prize in Chemistry was awarded to Jean-Pierre Sauvage, Sir J. Fraser Stoddart, and Bernard L. Feringa for the design and synthesis of molecular machines. A major point is to exploit existing motion in proteins, such as rotation about single bonds or cis-trans isomerization. Different AMMs are produced by introducing various functionalities, such as the introduction of bistability to create switches. A broad range of AMMs has been designed, featuring different properties and applications; some of these include molecular motors, switches, and logic gates.
Sources: en.wikipedia.org
== Mechanism == Coeliac disease appears to be multifactorial, both in that more than one genetic factor can cause the disease, and in that more than one factor is necessary for the disease to manifest in a person. Almost all people with coeliac disease have either the HLA-DQ2 variant (allele) or, less commonly, the HLA-DQ8 allele. However, about 40% of people without coeliac disease have also inherited either of these alleles. This suggests that additional factors are needed for coeliac disease to develop; that is, the predisposing HLA risk allele is necessary but not sufficient to develop coeliac disease. Furthermore, a small percentage of those who do develop coeliac disease do not have typical HLA-DQ2 or HLA-DQ8 alleles.
Service dress (מדי אלף Madei Alef – Uniform "A") – the everyday uniform, worn by everybody. Field dress ( מדי ב Madei Bet – Uniform "B") – worn into combat, training, work on base. The first two resemble each other but the Madei Alef is made of higher quality materials in a golden-olive while the madei bet is in olive drab. The dress uniforms may also exhibit a surface shine
The α-globin chains are encoded by two closely linked genes HBA1 and HBA2 on chromosome 16; in a person with two copies on each chromosome, a total of four loci encode the α chain. Two alleles are maternal and two alleles are paternal in origin. Alpha-thalassemias result in decreased alpha-globin production, resulting in an excess of β chains in adults and excess γ chains in fetus and newborns.
Sources: en.wikipedia.org
Skeptics Report investigation of Therapeutic Touch Archived 2009-12-15 at the Wayback Machine Therapeutic Touch at the Skeptic's Dictionary Dunning, Brian (April 27, 2010). "Skeptoid #203: Therapeutic Touch". Skeptoid.
He sent Signoret specimens of American grape lice, which Signoret concluded – in 1870, while he was besieged in Paris during the Franco-Prussian War – were indeed identical to French grape lice. Meanwhile, Planchon and Lichtenstein had found vines with afflicted leaves; lice that were transferred from those leaves to the roots of healthy vines attached themselves to the vines' roots as other French grape lice did. Also in 1870, Riley discovered that American grape lice wintered on American grape vines' roots, which the insects damaged, albeit less than in the case of French vines. Riley repeated Planchon and Lichtenstein's experiment using American grape vines and American grape lice, with similar results. Thus the identity of the French and American grape lice was proven. Nevertheless, for another three years, a powerful majority in France argued that Phylloxera was not the cause of vine disease; instead, vines that were already sickly became infested with Phylloxera. Thus, in their opinion, Phylloxera was merely a consequence of the "true" disease, which remained to be found. Regardless, Riley had discovered American grape varieties that were especially resistant to Phylloxera, and by 1871, French farmers began to import them and to graft French vines onto the American rootstock. (Leo Laliman had suggested importing American vines as early as 1869, but French farmers were reluctant to abandon their traditional varieties.
22 September It is reported that eight-year-old Aditi Shankar has become the first child in the UK to receive a kidney transplant that will not require her to take medication to prevent the organ being rejected, and that she is healthy and has returned to school. In his first statement since further allegations were made against him, Russell Brand posts a video on social media describing his week as "extraordinary and distressing". 23 September The government's home energy efficiency taskforce is scrapped. Members of the anti-monarchist pressure group Republic stage what they describe as the "first-ever" protest inside Buckingham Palace. 24 September – Home Secretary Suella Braverman orders a review into armed policing, after 300 firearms officers hand in their weapons, following concerns over a police officer charged with murdering 24-year-old Chris Kaba. Most of the officers return to their duties the following day. 25 September A hearing at Manchester Crown Court determines that Lucy Letby will face a retrial for one of the six counts of attempted murder that the jury at her original trial was unable to reach a verdict on; a provisional trial date is set for 10 June 2024. The Metropolitan Police are to investigate allegations of non-recent sexual offences following recent reports about comedian Russell Brand. 26 September Home Secretary Suella Braverman tells a US think tank the 1951 Refugees Convention is no longer fit for the modern age, and that being discriminated against for being gay or female should not be enough to qualify for refugee status.
Sources: en.wikipedia.org
It shares the 44-residue sequence of human GHRH but carries an added trans-3-hexenoyl group at its N-terminus. That addition does not occur in the natural hormone and serves mainly to resist enzymatic breakdown. The receptor target and signaling pathway remain the same.
It binds the growth hormone-releasing hormone receptor on anterior pituitary cells. Activation of that receptor promotes synthesis and release of growth hormone. The effect propagates through the growth hormone and insulin-like growth factor 1 axis.
Native GHRH is cleared quickly by peptidases, which limits how long it can stimulate its receptor. The added group hinders one of the primary cleavage enzymes. The practical consequence is a longer period of receptor activity per dose.
It is a laboratory-made peptide that mimics growth hormone-releasing hormone. It prompts the pituitary gland to release growth hormone and has been studied mainly in adults with HIV-associated lipodystrophy.