selectivity 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 2026-01-22. Where a claim depends on a specific study, the study is described rather than over-claimed.
Signal transduction begins when the peptide binds GHSR-1a on pituitary somatotrophs. The receptor couples to Gq/11 proteins, activating phospholipase C, which cleaves phosphatidylinositol bisphosphate into inositol trisphosphate and diacylglycerol. Inositol trisphosphate releases calcium from intracellular stores, and the resulting rise in cytosolic calcium drives growth hormone vesicle fusion. Concurrent Gs coupling and cyclic AMP elevation have also been reported, and the relative contribution of each arm to the overall secretory response is not fully settled.
Structural features distinguish the molecule from earlier secretagogues. An alpha-aminoisobutyric acid residue near the N-terminus and a D-naphthylalanine substitution increase receptor affinity, while C-terminal amidation improves resistance to exopeptidases. These modifications are associated with reduced stimulation of appetite and of the hypothalamic-pituitary-adrenal axis compared with hexarelin or growth hormone releasing peptide-6. Whether the same profile applies at every dose level studied is a matter of ongoing investigation rather than settled consensus.
现有文献多来自小规模、短期的研究，涉及生长激素缺乏、术后肠麻痹等方向。长期使用是否导致受体脱敏，以及重复给药后效应是否衰减，仍属开放问题。不同研究之间的剂量、给药途径和受试者特征差异较大，因此结论外推需谨慎。关于临床获益的确切证据尚不充分，需要更大规模的对照试验来澄清。
Ipamorelin 是一种合成五肽，在 20 世纪 90 年代被报道为生长激素促分泌剂。其结构基于胃饥饿素受体激动剂的设计思路，但并非天然激素。早期药理学研究显示，它可刺激垂体释放生长激素，而对应激激素轴的影响相对较小。该化合物常被用作研究生长激素调节通路的工具分子。
在机制层面，ipamorelin 与生长激素促分泌受体 1a 型结合，该受体也介导胃饥饿素的多种效应。受体激活后，细胞内信号促进生长激素从垂体前叶释放。由于对促肾上腺皮质激素和皮质醇的刺激较弱，它被视为选择性较高的促分泌剂。这种选择性在动物模型和少量人体研究中被观察到，但人体数据仍然有限。
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C38H49N9O5 | Reported for the free peptide |
| Molecular mass | 711.85 Da | Monoisotopic value |
| Residue motif | Aib-His-D-2-Nal-D-Phe-Lys-NH2 | Non-natural residues at positions one and three |
| Primary target | GHSR-1a | Ghrelin receptor, G protein coupled |
| Reported plasma half-life | About two hours | Values vary with assay and subject group |
Selectivity is the property most often attached to this peptide. Published animal and early human studies record increases in growth hormone release after administration, with adrenocorticotropic hormone and cortisol responses remaining small by comparison. Effects on appetite-related pathways also appear weaker than those reported for several earlier secretagogues. Reviews that compare members of the growth hormone secretagogue family cite these findings frequently, though the receptor-level explanation for the selectivity continues to be debated rather than settled.
Ipamorelin is a synthetic pentapeptide classified as a growth hormone secretagogue. Its sequence, Aib-His-D-2-Nal-D-Phe-Lys-NH2, combines three non-proteinogenic residues with a C-terminal amide. The N-terminal aminoisobutyric acid unit and the two aromatic D-amino acids distinguish it from peptides assembled only from standard L-amino acids. Its formula is C38H49N9O5, corresponding to an average mass near 711.9 Da. At neutral pH the molecule carries a net positive charge, a property that shapes its behaviour in chromatographic and electrophoretic systems.
At the receptor level, ipamorelin binds GHS-R1a and triggers signaling through Gq-coupled pathways. Activation leads to calcium release and downstream effects in pituitary somatotroph cells. These events promote the release of growth hormone into circulation. The response depends on the presence of the receptor and on the physiological state of the animal or tissue studied. Because the receptor is also found in other tissues, effects beyond the pituitary have been examined in laboratory models, though the extent of those effects remains an area of ongoing study.
One distinguishing feature reported in animal studies is selectivity. Ipamorelin stimulated growth hormone release with limited elevation of adrenocorticotropic hormone or cortisol compared with earlier secretagogues such as GHRP-6. This pattern has been described as more selective for the growth hormone axis. The finding comes mainly from preclinical work, and the degree to which it holds across species and doses is not fully settled. Reports also describe effects on gastric motility in animal models, suggesting activity outside the pituitary, though the clinical relevance of this observation is uncertain.
Ipamorelin is a synthetic pentapeptide that acts on the growth hormone secretagogue receptor, also known as the ghrelin receptor. Its sequence contains five amino acid residues, including a non-natural residue that increases stability against enzymatic breakdown. The compound was developed in the 1990s as part of research into small peptides that stimulate pituitary hormone release. Unlike larger protein hormones, it can be produced by solid-phase peptide synthesis and characterized by standard analytical methods.
Progesterone is produced from cholesterol with pregnenolone as a metabolic intermediate. In the first step in the steroidogenic pathway, cholesterol is converted into pregnenolone, which serves as the precursor to the progestogens progesterone and 17α-hydroxyprogesterone. These progestogens, along with another steroid, 17α-hydroxypregnenolone, are the precursors of all other endogenous steroids, including the androgens, estrogens, glucocorticoids, mineralocorticoids, and neurosteroids. Thus, many tissues producing steroids, including the adrenal glands, testes, and ovaries, produce progestogens. In some tissues, the enzymes required for the final product are not all located in a single cell. For example, in ovarian follicles, cholesterol is converted to androstenedione, an androgen, in the theca cells, which is then further converted into estrogen in the granulosa cells. Fetal adrenal glands also produce pregnenolone in some species, which is converted into progesterone and estrogens by the placenta (see below). In the human, the fetal adrenals produce dehydroepiandrosterone (DHEA) via the pregnenolone pathway.
Zinc pyrithione (or pyrithione zinc) is a coordination complex of zinc. It has fungistatic (inhibiting the division of fungal cells) and bacteriostatic (inhibiting bacterial cell division) properties and is used in the treatment of seborrhoeic dermatitis and dandruff.
=== 1983 === January: Soviet spy Dieter Gerhardt is arrested in New York. March 8: In speech to the National Association of Evangelicals, Reagan labels the Soviet Union an "evil empire". March 23: Ronald Reagan proposes the Strategic Defense Initiative (SDI, or "Star Wars"). June 5: The Second Sudanese Civil War begins. July 7: Ten-year-old American child Samantha Smith accepts the invitation of Soviet leader Yuri Andropov and visits the Soviet Union with her parents. Smith had written to Andropov to ask if he would "vote to have a war or not?". Smith's letter, published in the Soviet newspaper Pravda, prompted Andropov to reply and invite the girl to the USSR. The widely publicized event leads to other Soviet–American cultural exchanges. July 22: Martial law in Poland is lifted. July 23: The Sri Lankan Civil War begins between the LTTE and the Sri Lankan government. July 30: Sri Lankan government bans all its major communist parties claiming they were involved in ethnic riots, Soviet Union intervenes to unban the parties. August 4: Thomas Sankara overthrows Jean-Baptiste Ouédraogo and becomes president. He also renamed the country of Upper Volta to Burkina Faso a year later. August 19: During a two-hour meeting with 9 democratic senators Soviet Leader Yuri Andropov proposes that the Soviet Union and the United States agree to a complete ban on antisatellite weapons, and he pledged that the Soviet Union would not place any such weapons in space as long as other countries refrain from doing so. August 21: Former senator Benigno "Ninoy" S.
The system is usually baked, preferably under vacuum, to temporarily raise the vapour pressure of all outgassing materials in the system and boil them off. If necessary, this outgassing of the system can also be performed at room temperature, but this takes much more time. Once the bulk of the outgassing materials are boiled off and evacuated, the system may be cooled to lower vapour pressures to minimize residual outgassing during actual operation. Some systems are cooled well below room temperature by liquid nitrogen to shut down residual outgassing and simultaneously cryopump the system. In ultra-high vacuum systems, some very odd leakage paths and outgassing sources must be considered. The water absorption of aluminium and palladium becomes an unacceptable source of outgassing, and even the absorptivity of hard metals such as stainless steel or titanium must be considered. Some oils and greases will boil off in extreme vacuums. The porosity of the metallic vacuum chamber walls may have to be considered, and the grain direction of the metallic flanges should be parallel to the flange face. The impact of molecular size must be considered. Smaller molecules can leak in more easily and are more easily absorbed by certain materials, and molecular pumps are less effective at pumping gases with lower molecular weights. A system may be able to evacuate nitrogen (the main component of air) to the desired vacuum, but the chamber could still be full of residual atmospheric hydrogen and helium.
==== MeSH D08.811.074 – dna repair enzymes ==== MeSH D08.811.074.124 – deoxyribodipyrimidine photo-lyase MeSH D08.811.074.249 – dna glycosylases MeSH D08.811.074.249.500 – DNA-formamidopyrimidine glycosylase MeSH D08.811.074.249.750 – thymine dna glycosylase MeSH D08.811.074.249.875 – uracil-dna glycosidase MeSH D08.811.074.500 – dna ligases MeSH D08.811.074.750 – DNA-(apurinic or apyrimidinic site) lyase MeSH D08.811.074.781 – muts dna mismatch-binding protein MeSH D08.811.074.812 – muts homolog 2 protein MeSH D08.811.074.875 – polynucleotide 5'-hydroxyl-kinase
Sources: en.wikipedia.org
David Kossoff (24 November 1919 – 23 March 2005) was a British actor. In 1954 he won the BAFTA Award for Most Promising Newcomer to Leading Film Roles for his appearance as Geza Szobek in The Young Lovers. He played Alf Larkin in TV sitcom The Larkins and Professor Kokintz in The Mouse that Roared (1959) and its sequel The Mouse on the Moon (1963). Because of the drug use of his son Paul, former guitarist of blues-rock band Free, later with Back Street Crawler, who subsequently died, he became an anti-drug campaigner. In 1971 he was also actively involved in the Nationwide Festival of Light, an organisation protesting against the commercial exploitation of sex and violence, and advocating the teachings of Christ as the key to re-establishing moral stability in Britain.
Pulmonary hypertension has been gaining recognition as a complication of chronic hereditary and acquired hemolysis. Free hemoglobin released during hemolysis inactivates the vasodilator nitric oxide (NO). Hemolysis also releases arginase that depletes L-arginine, the substrate needed for NO synthesis. This reduces NO-dependent vasodilation and induces platelet activation, thrombin generation, procoagulant factors and tissue factor activation, contributing to the formation of thrombosis. This can lead to esophageal spasm and dysphagia, abdominal pain, erectile dysfunction, systemic hypertension, decreased organ perfusion, promotion of inflammation and coagulation, and thrombosis. Chronic hemolysis may also lead to endothelial dysfunction, heightened endothelin-1-mediated responses and vasculopathy. The release of heme leads to the production of bilirubin and depletion of plasma proteins, such as albumin, haptoglobin, and hemopexin, which may lead to jaundice. It may also lead to increased levels of the heme breakdown product stercobilin in the stool. Splenectomy of those with hemolytic disorders appears to increase risk of developing pulmonary thrombosis. Complications may also arise from the increased workload for the kidney as it secretes erythropoietin to stimulate the bone marrow to produce more reticulocytes (red blood cell precursors) to compensate for the loss of red blood cells due to hemolysis.
=== Other Valve games === Valve developed several games using the GoldSrc engine, many of which were based on original user-made modifications. Valve's Team Fortress Classic, released in 1999, was developed primarily by two of the developers of the Quake mod Team Fortress. Counter-Strike and Day of Defeat were also originally Half-Life modifications that Valve purchased the rights to and re-released as standalone titles. Counter-Strike evolved into its own series with the debut of the Japanese arcade game Counter-Strike Neo in 2003 and Valve's own follow-up in 2004, Counter-Strike: Condition Zero, both of which run on the GoldSrc engine. Although Valve's further installments in the series starting with Counter-Strike: Source use the newer Source engine instead, Counter-Strike Online and Counter-Strike Nexon, two spinoff titles released by Nexon in 2008 and 2014 respectively, use GoldSrc as their basis.
=== Isotope ratio as tracer for fingerprint === In many areas of study the origin of a chemical or group of chemicals is of central importance. Questions such as the source of environmental pollutants, the origin of hormones in an athlete's body, or the authenticity of foods and flavorings are all examples where chemical compounds need to be identified and sourced. Hydrogen isotopes have found uses in these and many other diverse areas of study. Since many processes can affect the DHR of a given compound this ratio can be a diagnostic signature for compounds produced in a specific location or via a certain process. Once the DHRs of a number of sources are known the measurement of this ratio for a sample of unknown origin can often be used to link it back to a certain source or production method.
The committee finished its work in April 1978 and the Constitutional Affairs Commission began to debate the preliminary draft on May 5. But the real negotiation was carried out outside the commission by Fernando Abril Martorell on behalf of the UCD and the government and the deputy secretary general of the PSOE Alfonso Guerra, who met privately to reach a consensus on the controversial issues, which allowed the rapid approval of the articles of the preliminary draft. The consensus was extended to Communists and Catalan nationalists but a part of Alianza Popular, which rejected among other things the incorporation of the term "nationalities", and the PNV, which demanded the recognition of the national sovereignty of the Basques, did not join it. Finally, on October 31, 1978, the Constitutional bill was voted in the Congress and in the Senate. In the Congress, 325 deputies voted in favor, 6 against (five deputies of AP and the deputy of Euskadiko Ezkerra), and 14 abstained (the 8 deputies of the PNV, plus 6 of AP and the mixed group). In the Senate, 226 senators supported it and 5 voted against it. The Constitution thus obtained enormous parliamentary support. On December 6, 1978, the Constitution was submitted to referendum, being approved by 88% of the voters, and rejected by 8%, with a participation of 67.11% of the census. In the Basque Country, the abstentionist campaign promoted by the PNV was successful so that there the Constitution was approved by only 43.6% of the electoral roll.
Sources: en.wikipedia.org
=== Wound care and dressings === Caring for wounds and ulcers that have been started and the use of creams are also considerations in preventing worsening to ulcers and new primary ulcers. It is unclear if creams containing fatty acids are effective in reducing incidence of pressure ulcers compared to creams without fatty acids. It is also unclear if silicone dressings reduce pressure ulcer incidence. There is no evidence that massage reduces pressure ulcer incidence. Controlling the heat and moisture levels of the skin surface, known as skin microclimate management, may also play a role in the prevention and control of pressure ulcers. Skin care is also important because damaged skin does not tolerate pressure. However, skin that is damaged by exposure to urine or stool is not considered a pressure ulcer. These skin wounds should be classified as Incontinence Associated Dermatitis.
South Korean intelligence officials also said that the North Korean government had locked down Pyongyang, and had refused to accept 110,000 tons of rice from China for fear of letting the virus into the country. Expatriates in North Korea became concerned about getting treatment for COVID-19, since the North Korean medical system was limited, and it was difficult to seek treatment in China due to travel restrictions. According to NK News, on 22 September, the crew of a North Korean patrol boat killed a South Korean fisheries officer whom they encountered off their coast, and then torched his flotation device in compliance with COVID-19 emergency orders. Kim apologized to South Korea for the incident. In October, North Korean media said that the world was looking at North Korea with envy because of its virus-free status, but at the same time warned against complacency. In the same month, there was a spike in people tested and quarantined, possibly related to celebrations on 10 October. During these celebrations, Kim Jong Un criticised himself and the leadership of the Workers' Party of Korea for falling short during the COVID-19 pandemic. In November 2020, Daily NK reported that there had been a spike of residents in quarantine facilities with COVID-19 symptoms, and that at least 80,000 non-military residents had been quarantined in total by then, although the country continued to maintain that it did not have any confirmed cases.
In 2001, Freeman reprised his role of Alex Cross in Along Came a Spider, a sequel to 1997's Kiss the Girls. The film received mixed-to-negative reviews. Susan Wloszczyna of USA Today observed that "Freeman strides with noble authority" but thought the overall film was unmemorable. In 2002, Freeman was cast opposite Ben Affleck in the spy thriller The Sum of All Fears. It is based on Tom Clancy's 1991 novel of the same name, about a plot by an Austrian Neo-Nazi to trigger a nuclear war between the United States and Russia, so that he can establish a fascist superstate in Europe. The Sum of All Fears received moderate reviews, but was a commercial success, grossing $193.9 million worldwide. Next, Freeman starred alongside Ashley Judd and Jim Caviezel in High Crimes (2002), a legal thriller based on Joseph Finder's 1998 novel of the same name. The story follows lawyer Claire (Judd), whose husband (Caviezel) is arrested and placed on trial for the murder of villagers while he was in the Marines. Although several critics were unimpressed with the story, they credited Freeman and Judd for their chemistry and performances. In 2003, Freeman appeared as God in the hit comedy Bruce Almighty with Jim Carrey and Jennifer Aniston. Next, he starred in the science fiction horror Dreamcatcher, adapted from Stephen King's 2001 novel of the same name. The film was a box-office flop, and garnered mostly negative reviews; Dreamcatcher has an approval rating of 28% on review aggregate site Rotten Tomatoes.
GSK completed the acquisition of New Jersey–based Block Drug in 2001, for US$1.24 billion. In 2006, GSK acquired the US-based consumer healthcare company CNS Inc., whose products included Breathe Right nasal strips and FiberChoice dietary supplements, for US$566 million in cash. Chris Gent, previously CEO of Vodafone, was appointed chairman of the board in 2005. GSK opened its first R&D centre in China in 2007, in Shanghai, initially focused on neurodegenerative diseases. Andrew Witty became the chief executive officer in 2008. Witty joined Glaxo in 1985, and had been president of GSK's Pharmaceuticals Europe since 2003. In 2009, GSK acquired Stiefel Laboratories, then the world's largest independent dermatology drug company, for US$3.6 billion. In November 2009, the FDA approved GSK's vaccine for 2009 H1N1 influenza protection, manufactured by the company's ID Biomedical Corp in Canada. Also in November 2009, GSK formed a joint venture with Pfizer to create ViiV Healthcare, which specializes in HIV research. In 2010, the company acquired Laboratorios Phoenix, an Argentine pharmaceutical company, for US$253m, and the UK-based sports nutrition company Maxinutrition for £162 million (US$256 million).
Sources: en.wikipedia.org
Both molecules activate the same receptor, GHSR-1a, but they share little sequence identity. Ghrelin is a 28-amino-acid hormone carrying a distinctive acyl modification, whereas ipamorelin is a short synthetic peptide. The shared target explains overlapping endocrine effects, while the different structures account for differences in metabolic stability and receptor selectivity.
Early animal and human studies reported growth hormone release at levels that produced small changes in cortisol, prolactin and adrenocorticotropic hormone. That contrast with older secretagogues gave rise to the selectivity label. The observation is consistent across several reports but rests on a limited number of small studies.
Plasma peptidases cleave the molecule into smaller fragments, and reported half-lives in human studies are on the order of a couple of hours. The identity and activity of individual breakdown products have not been fully mapped. Questions about tissue-level clearance remain open.
不是。它属于人工合成的五肽，设计上模拟胃饥饿素受体的部分作用，但不存在于人体天然激素谱中。