selectivity comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Updated 2025-12-17. Numbers and descriptions here follow the published literature rather than marketing material.
Ipamorelin is a synthetic pentapeptide that belongs to the growth hormone secretagogue class. It acts as an agonist at the ghrelin receptor, also called the growth hormone secretagogue receptor type 1a. The compound was designed in the 1990s during a search for agents that release growth hormone with fewer off-target hormonal effects than earlier secretagogues. It appears in the research literature under several sequence-based names. Material supplied for laboratory work is normally a lyophilized solid, and it is not marketed as an approved therapeutic in major jurisdictions.
The molecule contains five residues, including alpha-aminoisobutyric acid, D-2-naphthylalanine, and D-phenylalanine, and it ends in a lysine amide. Non-natural and D-configured residues make the chain less susceptible to common peptidases, which helps explain its resistance to rapid breakdown. Its molecular formula is C38H49N9O5, corresponding to a free-base mass near 711.9 daltons. The C-terminal amide removes a negative charge and is a recurring feature in receptor-active peptides of this family. These structural choices are usually discussed as the basis for its selectivity profile.
从用途定位看，ipamorelin 目前主要以研究用肽的身份被讨论，未见主要药品监管机构将其批准为治疗药物。市售材料通常标注仅供研究使用，不得用于人体或诊断程序。文献中它常与生长激素促分泌素、GHS-R1a 激动剂、胃饥饿素拟似物等表述并列出现。既有研究的样本量普遍偏小，因此对其效应强度与一致性的描述应保持谨慎。
Ipamorelin 是一种合成五肽，序列为 Aib-His-D-2-Nal-D-Phe-Lys-NH2，分子式 C38H49N9O5，游离碱分子量约 711.85 g/mol。它属于生长激素促分泌素（GHS）家族，作用靶点是胃饥饿素受体 GHS-R1a。该化合物由诺和诺德的研究团队在二十世纪九十年代末报道，设计目标是提高对生长激素释放的选择性。C 端酰胺化与 N 端 Aib 残基是两个用于抵抗肽酶降解的结构特征。
在 GHS 家族中，早期肽类如 GHRP-6 与 GHRP-2 会同时促进生长激素、皮质醇与催乳素的释放，并明显增加食欲。Ipamorelin 在动物与早期人体研究中表现出对生长激素释放的相对选择性，对上述其他激素的影响较小。这种差异通常归因于受体结合模式与下游信号偏向的不同，而完整的分子解释仍有待补充。需要区分的是，选择性是研究观察中的相对程度，并非绝对界限。
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C38H49N9O5 | Value for the free base |
| Molar mass | 711.9 g/mol | Calculated from the formula |
| Appearance | White to off-white powder | Typical lyophilized form |
| Mechanism class | Ghrelin receptor agonist | Also described as a secretagogue |
| Half-life | About 2 hours | Reported for human circulation |
The compound was developed at Novo Nordisk during the 1990s as part of a programme seeking secretagogues with improved selectivity. It was described in the peer-reviewed literature in 1998 alongside related pentapeptides from the same series. Investigators advanced it because it raised growth hormone output in animal models while leaving other pituitary hormones comparatively unaffected. The development code NNC 26-0161 appears in earlier reports, and ipamorelin later became the common designation in published work.
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 that acts as an agonist at the ghrelin receptor, also called the growth hormone secretagogue receptor type 1a. Its sequence incorporates non-natural residues, which slows enzymatic breakdown relative to short native peptides. In laboratory and early clinical work the compound is described as a selective growth hormone secretagogue because it raises growth hormone with comparatively little effect on other pituitary outputs. The degree to which that selectivity holds across species and dosing regimens remains an open question in the published literature.
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.
== Research and Discoveries == Strahl is a pioneer in the field of epigenetics, with contributions to the study of Chromatin biology. As a postdoctoral fellow in C. David Allis’ laboratory, helped to establish the identity of the first lysine and arginine histone methyltransferases and how they contribute to transcriptional activation and heterochromatin formation. Some examples include the discovery of the first histone methyltransferases that target lysine 4 (Set1), lysine 9 (SUV39H1), and lysine 36 of histone H3 (Set2/SETD2) and arginine 3 of histone H4 (PRMT1). Strahl also helped to develop the first antibodies for methylated histones in the Allis laboratory. In 2000, Strahl and Allis put forward the idea of the “histone code hypothesis”, which aimed to explain how multiple histone modifications function together to control chromatin structure and function. The early years of the Strahl laboratory, research focused on the roles of histone methylation and histone ubiquitylation in gene transcription. He linked histone H2B ubiquitylation to the regulation of H3 lysine 79 methylation and in transcriptional elongation and determined how H3 lysine 36 methylation is coupled to RNA Polymerase II and repressive chromatin during transcription elongation. His group also defined the key roles of several histone chaperones (e.g., Spt6) that function in transcription In more recent years, Strahl turned his attention to how chromatin-associated proteins engage histones and their modifications.
Diff-Quik is a commercial Romanowsky stain variant used to rapidly stain and differentiate a variety of pathology specimens. It is most frequently used for blood films and cytopathological smears, including fine needle aspirates. The Diff-Quik procedure is based on a modification of the Wright-Giemsa stain pioneered by Harleco in the 1970s, and has advantages over the routine Wright-Giemsa staining technique in that it reduces the 4-minute process into a much shorter operation and allows for selective increased eosinophilic or basophilic staining depending upon the time the smear is left in the staining solutions. There are generic brands of such stain, and the trade name is sometimes used loosely to refer to any such stain (much as "Coke" or "Band-Aid" are sometimes used imprecisely).
During preparation for the Fram expedition to the North Pole in 1893–1896, 33 dogs were purchased from the Nenets people. Of these dogs, 28 were used in an attempt on the North Pole; none of those survived. The remaining dogs, including pups born during the voyage, were left aboard the ship. In April 1893 the bitch had another litter, most of them white. According to Nansen's notes "all the dogs were strong, tough and excellent at pulling sleds; they worked very well in hunting Polar bears [as well]." These dogs would become the original Samoyeds. British Zoologist Ernest Kilburn-Scott is widely considered the founder of Samoyed breed. In 1889, he returned to England with a puppy he had purchased from a Samoyed encampment near Arkhangelsk. In the early days, imported dogs were a wide array of colors. However, it was widely believed that the "true Samoyeds", as originally bred in Siberia, were predominantly white. In 1909, the first official breed standard for the Samoyed was developed in England. In 1898–1900, Carsten Borchgrevink brought 90 Samoyeds to the southern hemisphere during the Southern Cross Expedition. In his book To the South Polar Regions, expedition member Louis Bernacchi wrote:
The emergent long elimination timescale appears because not only is the intrinsic degradation time scale an order of magnitude longer than that of binding, but also because the endosomal antibody concentration is low due to high binding affinity. In particular, the analysis shows that clearance in the terminal phase is inherently nonlinear, with clearance,
Dalbavancin, sold under the brand names Dalvance in the US and Xydalba in the EU (both by AbbVie) among others, is a second-generation lipoglycopeptide antibiotic medication. It belongs to the same class as vancomycin, the most widely used and one of the treatments available to people infected with methicillin-resistant Staphylococcus aureus (MRSA). Dalbavancin is a semisynthetic lipoglycopeptide that was designed to improve upon the natural glycopeptides vancomycin and teicoplanin. It is derived from a complex of glycopeptide antibiotics, referred to as A-40926, that is produced by a new strain of Actinomadura. Dalbavancin has been referred to in the scientific literature by a series of names: MDL-63397, A-!-1, BI-397, VER-001. These different labels reflected where the research had been carried out: MDL representing Merrell-Dow-Lepetit, where the initial complex was discovered; BI referring to BioSearch Italia where Dalbavancin itself was first synthesized; VER referring to Versicor (which Biosearch Italia merged with to create Vicuron Pharmaceuticals). The phase I, II and III clinical trials were carried out of by Vicuron and the initial NDA filed. Vicuron was acquired by Pfizer in 2005, which decided to not further develop Dalbavancin at that time, subsequently selling the rights to Durata Therapeutics in 2009. It possesses in vitro activity against a variety of Gram-positive pathogens including MRSA and methicillin-resistant Staphylococcus epidermidis (MRSE).
Sources: en.wikipedia.org
=== Future technology and research === Gene therapy is being explored as a treatment for missense mutations. This involves inserting the correct sequence of DNA into an incorrect gene. Artificial Intelligence programs, such as AlphaFold, are also being developed to predict the effect of missense mutations. Identifying potential deleterious mutations can assist with disease diagnosis and treatment.
== Company history == Digico was founded in 1965 by Keith Trickett and Avo Hiiemae, two ex-ICL electronics engineers. Former MP Eric Lubbock was chairman from 1969 to 1983. The company was based in Letchworth initially, moving to a new factory in Stevenage in 1973 and employing about 90 staff. Digico's first product was a laboratory data-logging and spectrum analyser hardware system named DIGIAC. A prototype had been developed before Digico was formed, by the founders in a garage, so became an immediate source of income. Digico soon developed a 16-bit minicomputer series, the Micro 16, for which it was best known for. In 1974 Digico had a turnover of over £1 million (equivalent to £9 million in 2025) and in 1977 well over £1 million. Spanverne Investments raised a large private capital investment into Digico in 1981, while the new Prince product was being developed. In October 1982, Digico announced it would close its Stevenage factory with the loss of 130 jobs within six months. This was part of a rationalisation plan to concentrate manufacturing at its large Leeds site. It would retain its Letchworth site primarily as a south England office. On 1 February 1984, the Financial Times reported that after a weekend of failed negotiation between British computer company Optim and Midland Bank, Digico went into receivership on 30 January 1984. Digico owed more that £400,000 to Midland Bank and over £1 million to other creditors.
There was worse to follow, with various Essendon players publicly blaming each other for a poor performance against Richmond, and then, with dissension still rife in the ranks, the side plummeted to an unexpected and humiliating 28-point loss to VFA premiers Footscray in a special charity match played a week later in front of 46,100 people, in aid of Dame Nellie Melba's Limbless Soldiers' Appeal Fund, purportedly (but not officially) for the championship of Victoria. The club's fortunes dipped alarmingly—and persistently. Indeed, after finishing third in the 1926 season, it was to be 14 years later—in 1940—before Essendon would even contest another finals series.
According to a 2010 report on co-authored by Miron, the annual savings on enforcement and incarceration costs from the legalization of drugs would amount to roughly $41.3 billion, with $25.7 billion being saved among the states and over $15.6 billion accrued for the federal government. Miron further estimated at least $46.7 billion in tax revenue based on rates comparable to those on tobacco and alcohol: $8.7 billion from marijuana, $32.6 billion from cocaine and heroin, and $5.4 billion from other drugs. Regarding economic arguments for legalization that make a comparison with alcohol, a 2013 study noted that the $14.6 billion in annual alcohol tax collected at the US federal and state levels represented less than 10% of the estimated $185 billion of alcohol-related health care, criminal justice and lost productivity costs.
Sources: en.wikipedia.org
It has not been approved as a therapeutic by major regulators, and the human trial record is small and dated. Material available today is mostly sold as a research chemical for laboratory use. Approval and restriction status varies by country.
It binds the ghrelin receptor, known as the growth hormone secretagogue receptor type 1a. Activation of that receptor triggers signaling that leads to growth hormone release. Selectivity for growth hormone over cortisol and prolactin is the property most often cited for this compound.
Published estimates place the circulating half-life at roughly two hours in humans. Clearance involves peptidase activity and renal handling. Because the peptide is short-lived, release patterns after administration are usually described as pulsatile rather than sustained.
两者都是 GHS-R1a 激动剂，但 ipamorelin 在研究中显示出更高的生长激素释放选择性。早期资料显示它对皮质醇、催乳素与食欲的刺激弱于 GHRP-6。这些差异是相对程度，而非绝对区分。