The short version of ESI-MS fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2026-07-14. Anything still debated is marked as such rather than presented as settled.
In animal and early human studies, ipamorelin produces pulsatile growth hormone release and a secondary rise in insulin-like growth factor 1. The magnitude and duration of that rise depend on route, sampling schedule, and the baseline endocrine state of the subject. Whether repeated exposure alters the response over time is not firmly settled, since some reports describe stable pulsatility while others note attenuation. Most published data come from small samples, which limits the strength of any general claim about long-term behavior.
Ipamorelin is a synthetic pentapeptide that belongs to the growth hormone secretagogue class of compounds. Its sequence is Aib-His-D-2-Nal-D-Phe-Lys-NH2, a structure that differs from natural ghrelin in length and in the presence of non-natural amino acid residues. Early laboratory work described it as a comparatively selective agent that stimulates growth hormone release with limited effect on other pituitary hormones. The compound is supplied as a lyophilized solid for research use and has no identified natural source in the body.
Most published work on ipamorelin comes from rodent studies and small early-phase human trials. Subcutaneous and intravenous routes have been used, while oral delivery is limited by poor absorption and rapid breakdown in the gut. The reported plasma half-life is short, on the order of two hours, and varies with species and assay method. Whether chronic use produces meaningful clinical benefit remains unresolved, and long-term safety data in humans are sparse. No major regulatory agency has approved the compound as a therapeutic drug.
Ipamorelin is a synthetic pentapeptide that belongs to the growth hormone secretagogue family. Its sequence is Aib-His-D-2-Nal-D-Phe-Lys-NH2, incorporating two non-natural residues that resist enzymatic breakdown. Researchers at Novo Nordisk described the compound in the 1990s while searching for agents that release growth hormone with fewer side effects than earlier secretagogues. The molecule acts as an agonist at the ghrelin receptor, also called GHS-R1a, which is expressed in the pituitary and in several peripheral tissues.
Selectivity distinguishes ipamorelin from first-generation secretagogues such as GHRP-6. At doses that reliably raise growth hormone, it shows little stimulation of adrenocorticotropic hormone or cortisol release in animal models, and it does not markedly raise prolactin or appetite. Binding at GHS-R1a on pituitary somatotrophs triggers calcium influx and pulsatile growth hormone secretion. Because the compound mimics the natural ghrelin signal, the release pattern tends to follow the body's own rhythm rather than producing a sustained elevation.
| Property | Value | Notes |
|---|---|---|
| Peptide class | Synthetic pentapeptide | GHS-R1a agonist family |
| Receptor target | Ghrelin receptor (GHS-R1a) | G-protein-coupled receptor |
| Sequence length | Five amino acid residues | Includes non-natural residues |
| Primary reported output | Pulsatile growth hormone release | Observed in animal and early human work |
| Molecular formula | C38H49N9O5 | Corresponds to roughly 711.9 g/mol |
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。
Long-term storage of the dry powder is typically at minus twenty degrees Celsius or lower, protected from light and moisture. Solutions are commonly kept frozen and thawed only once, because repeated freeze-thaw cycles can promote aggregation and loss of measurable peptide content. Buffers near neutral pH are preferred over strongly acidic or strongly basic conditions. Shipping at ambient temperature is acceptable for short periods when the powder remains sealed and desiccated.
Identity and purity are assessed by complementary methods rather than a single test. Reversed-phase high-performance liquid chromatography separates the peptide from related impurities and reports a percentage purity. Mass spectrometry, most often with electrospray ionization, confirms the expected molecular mass and detects sequence-related variants. Amino acid analysis can verify composition, while water content and residual counterion measurements support the mass balance of a batch. Stability studies under accelerated conditions are used to estimate shelf life, though such estimates carry uncertainty for long-term storage.
Material supplied for research use is normally a white to off-white lyophilized powder. The solid is hygroscopic and is handled in a low-humidity environment to limit water uptake. Bulk quantities are frequently shipped in sealed vials under inert gas. Once reconstituted in water or a neutral buffer, the solution is less stable than the dry powder and is usually divided into single-use aliquots.
Verification of identity and purity relies on analytical methods used across peptide chemistry. Reverse-phase high-performance liquid chromatography separates components by hydrophobicity and provides a purity estimate. Mass spectrometry confirms molecular mass and helps detect modifications. Together these techniques give complementary information about whether a sample matches its expected structure. Results depend on method parameters and reference standards, so reported purity values are meaningful only when the analytical conditions are stated. Consistency between laboratories requires comparable protocols and well-characterized reference materials.
Peptides such as ipamorelin are subject to chemical and physical degradation. Hydrolysis of peptide bonds, oxidation of susceptible residues, and aggregation are common pathways that reduce purity over time. The rate of these processes depends on temperature, moisture, pH, and the number of freeze-thaw cycles a sample undergoes. Because the compound is typically handled as a lyophilized powder, controlling moisture during storage is a central concern. Degradation products can be detected with separation techniques that resolve the parent peptide from related impurities.
Hong Kong is home to a wide range of museums, galleries, and cultural institutions, and is regarded as one of Asia's leading centres for art, heritage, and visual culture. Major cultural development in the city has taken place in the West Kowloon Cultural District, a large arts and museum quarter on reclaimed land in Kowloon. Its best-known institutions include M+, a museum of visual culture focused on 20th and 21st century art, design, architecture, and moving image, and the Hong Kong Palace Museum, which displays Chinese artworks and artifacts. Apart from West Kowloon, Hong Kong has many additional museums across the territory. The Hong Kong Museum of Art in Tsim Sha Tsui houses collections of Chinese antiquities, calligraphy, painting, and Hong Kong art. The Hong Kong Heritage Museum in Sha Tin focuses on history, art, and local popular culture, with exhibitions on Cantonese opera, film, and design. The Hong Kong Museum of History presents the development of Hong Kong from prehistoric times to the present, while the Hong Kong Science Museum and Hong Kong Space Museum are among the city's main public institutions devoted to science and education. Tai Kwun, a former police station and prison compound in Central, has been revitalised as a centre for heritage and contemporary art, and hosts exhibitions, performances, and public programmes.
Schabowski gave a confusing answer that asserted it was necessary because West Germany had exhausted its capacity to accept fleeing East Germans, then remembered the note he had been given and added that a new regulation had been drafted to allow permanent emigration at any border crossing. This caused a stir in the room; amid several questions at once, Schabowski expressed surprise that the reporters had not yet seen this regulation, and started reading from the note. After this, a reporter, either Ehrman or Bild-Zeitung reporter Peter Brinkmann, both of whom were sitting in the front row at the press conference, asked when the regulations would take effect. After a few seconds' hesitation, Schabowski replied, "As far as I know, it takes effect immediately, without delay" (German: Das tritt nach meiner Kenntnis ... ist das sofort ... unverzüglich). This was an apparent assumption based on the note's opening paragraph; as Beil attempted to interject that it was up to the Council of Ministers to decide when it took effect, Schabowski proceeded to read this clause, which stated it was in effect until a law on the matter was passed by the Volkskammer. Crucially, a journalist then asked if the regulation also applied to the crossings to West Berlin. Schabowski shrugged and read item 3 of the note, which confirmed that it did. After this exchange, Daniel Johnson of The Daily Telegraph asked what this law meant for the Berlin Wall. Schabowski sat frozen before giving a rambling statement about the Wall being tied to the larger disarmament question.
==== Civil Protection ==== The Civil Protection is the Combine's primary law enforcement agency on Earth, whose ranks are drawn from unmodified, volunteering humans. Commonly referred to as "metrocops" or "CPs", Civil Protection personnel wear light body armor and face masks which resemble a modified PMK gas mask. They also have voice modifiers, masking their normal voices. They typically carry electroshock batons (named stun-sticks in the game) and pistols, and are occasionally equipped with submachine guns. The Civil Protection are frequently brutal in their methods, keeping the local populace in line via intimidation and violence. Interrogations, inspections, raids, random beatings, summary executions and acts of police brutality are all used as a means of policing their jurisdictions; the Civil Protection's methods are justified by their role as "protectors of the civilians' well-being". On the outskirts of City 17, the Civil Protection carry out constant patrols for escapees from the city. Civil Protection personnel are in constant contact with the Combine's Overwatch headquarters, which issues them objectives and situation updates. Upon the death of Civil Protection personnel, their armor detects that its wearer is no longer alive and automatically informs the Overwatch of the fatality.
=== Impact on biogeochemistry === In biogeochemistry, scientists focused mainly on deuterium as a tracer for environmental processes, especially the water cycle. American geochemist Harmon Craig, once a graduate student of Urey, discovered the relationship between rainwater's hydrogen and oxygen isotope ratios. The linear correlation between the two heavy isotopes occurs worldwide and is called the global meteoric water line. By the late 1960s, the focus of hydrogen isotopes shifted away from water and toward organic molecules. Plants use water to form biomass, but a 1967 study by Zebrowski, Ponticorvo, and Rittenberg found that the organic material in plants had less 2H than the water source. Zebrowski's research measured the deuterium concentration of fatty acids and amino acids derived from sediments in the Mohole drilling project. Further studies by Bruce Smith and Samuel Epstein in 1970 confirmed the depletion of 2H in organics compared to environmental water. Another duo in 1970, Schiegl and Vogel, analyzed the HIC as water became biomass, as biomass became coal and oil, and as oil became natural gas. In each step they found 2H further depleted. A landmark paper in 1980 by Marilyn Epstep, now M. Fogel, and Thomas Hoering titled "Biogeochemistry of the stable hydrogen isotopes" refined the links between organic materials and sources. In this early stage of hydrogen stable isotope study, most isotope compositions or fractionations were reported as bulk measurements of all organic or all inorganic matter.
The reign of Juan Carlos I as king of Spain began on November 22, 1975, with his accession to the throne following the death of dictator Francisco Franco, who had designated him as successor and Prince of Spain in 1969, and ended on June 19, 2014, with his abdication.
Sources: en.wikipedia.org
==== Fishkeeping ==== Hydrogen peroxide is used in aquaculture for controlling mortality caused by various microbes. In 2019, the U.S. FDA approved it for control of Saprolegniasis in all coldwater finfish and all fingerling and adult coolwater and warmwater finfish, for control of external columnaris disease in warm-water finfish, and for control of Gyrodactylus spp. in freshwater-reared salmonids. It can also be used to increase the oxygen content of water to enable fish to survive otherwise-hypoxic conditions. The hydrogen peroxide releases oxygen by decomposition when it is exposed to catalysts such as manganese dioxide. Sodium percarbonate, a complex containing hydrogen peroxide as its active agent, is sold for oxygenation in acutely oxygen-deficient water to enable fish survival.
=== Stimulation of Other Relevant Pregnancy Hormones === CGB triggers the body to create more estrogen and progesterone. In tandem with CGB, the increased estrogen and progesterone signal to the body that pregnancy is occurring, and help thicken the uterine lining and stop menstruation. It is the precise balance of these three hormones that help to sustain and maintain a healthy pregnancy. More specifically, CGB is a luteotropic hormone that promotes the survival and steroidogenic activity of corpus luteum by acting through luteinizing hormone receptors (LHRs) expressed on luteinized theca and granulosa cells. Through this activation, the corpus luteum produces the progesterone needed for the subsequent stages of pregnancy. This helps to keep the highly crucial corpus luteum alive and activated.
== Assessment and treatment == Assessment can be difficult because much of the damage is often internal and not visible. The patient is thoroughly examined. X-ray and CT scanning may be used to identify the type and location of potentially lethal injuries. Sometimes before an X-ray is performed on a person with penetrating trauma from a projectile, a paper clip is taped over entry and exit wounds to show their location on the film. The patient is given intravenous fluids to replace lost blood. Surgery may be required; impaled objects are secured into place so that they do not move and cause further injury, and they are removed in an operating room. If the location of the injury is not obvious, a surgical operation called an exploratory laparotomy may be required to look for internal damage to the organs in the abdomen. Foreign bodies such as bullets may be removed, but they may also be left in place if the surgery necessary to get them out would cause more damage than would leaving them. Wounds are debrided to remove tissue that cannot survive and other material that presents risk for infection. Negative pressure wound therapy is no more effective in preventing wound infection than standard care when used on open traumatic wounds.
Under JFC, the company initially closed more stores than it opened. It started from 1,189 stores upon buying it to just 1,048 in 2021. However, the number of stores has risen again to 1,232 as of 2024.
The term RAST became a colloquialism for all varieties of (in vitro allergy) tests. This is unfortunate because it is well recognized that there are well-performing tests and some that do not perform as well, yet they are all called RASTs, making it difficult to distinguish between them. For these reasons, it is now recommended that the use of RAST as a generic descriptor of these tests be abandoned. The updated version, the ImmunoCAP Specific IgE blood test, is the only specific IgE assay the Food and Drug Administration has approved to quantitatively report to its detection limit of 0.1 kU/L.
Sources: en.wikipedia.org
Some have argued that there is little evidence to indicate any benefit to using bodybuilding protein or amino acid supplements. A 2005 overview concluded that "[i]n view of the lack of compelling evidence to the contrary, no additional dietary protein is suggested for healthy adults undertaking resistance or endurance exercise". In contrast, a 2018 systematic review, meta-analysis and meta-regression concluded that, “Dietary protein supplementation significantly enhanced changes in muscle strength and size during prolonged RET in healthy adults.“ (RET is an abbreviation for resistance exercise training.) Instant breakfast Protein bar "Dietary Supplement Health and Education Act of 1994". U.S. Food and Drug Administration. 4 February 2020. Archived from the original on June 2, 2009.
Gas phase ion chemistry is a field of science encompassed within both chemistry and physics. It is the science that studies ions and molecules in the gas phase, most often enabled by some form of mass spectrometry. By far the most important applications for this science is in studying the thermodynamics and kinetics of reactions. For example, one application is in studying the thermodynamics of the solvation of ions. Ions with small solvation spheres of 1, 2, 3... solvent molecules can be studied in the gas phase and then extrapolated to bulk solution. Transition state theory is the theory of the rates of elementary reactions which assumes a special type of chemical equilibrium (quasi-equilibrium) between reactants and activated complexes. RRKM theory is used to compute simple estimates of the unimolecular ion decomposition reaction rates from a few characteristics of the potential energy surface.
Site-specific recombination makes use of phage integrases instead of restriction enzymes, eliminating the need for having restriction sites in the DNA fragments. Instead, integrases make use of unique attachment (att) sites, and catalyse DNA rearrangement between the target fragment and the destination vector. The Invitrogen Gateway cloning system was invented in the late 1990s and uses two proprietary enzyme mixtures, BP clonase and LR clonase. The BP clonase mix catalyses the recombination between attB and attP sites, generating hybrid attL and attR sites, while the LR clonase mix catalyse the recombination of attL and attR sites to give attB and attP sites. As each enzyme mix recognises only specific att sites, recombination is highly specific and the fragments can be assembled in the desired sequence. Vector design and assembly Because Gateway cloning is a proprietary technology, all Gateway reactions must be carried out with the Gateway kit that is provided by the manufacturer. The reaction can be summarised into two steps. The first step involves assembling the entry clones containing the DNA fragment of interest, while the second step involves inserting this fragment of interest into the destination clone.
In 1969, the Dubna team carried out chemical experiments on element 102 and concluded that it behaved as the heavier homologue of ytterbium. The Russian scientists proposed the name joliotium (Jo) for the new element after Irène Joliot-Curie, who had recently died, creating an element naming controversy that would not be resolved for several decades, with each group using its own proposed names. In 1992, the IUPAC-IUPAP Transfermium Working Group (TWG) reassessed the claims of discovery and concluded that only the Dubna work from 1966 correctly detected and assigned decays to nuclei with atomic number 102 at the time. The Dubna team are therefore officially recognized as the discoverers of nobelium, although it is possible that it was detected at Berkeley in 1959. This decision was criticized by Berkeley the following year, calling the reopening of the cases of elements 101 to 103 a "futile waste of time", while Dubna agreed with IUPAC's decision. In 1994, as part of an attempted resolution to the element naming controversy, IUPAC ratified names for elements 101–109. For element 102, it ratified the name nobelium (No) on the basis that it had become entrenched in the literature over the course of 30 years and that Alfred Nobel should be commemorated in this fashion. Because of outcry over the 1994 names, which mostly did not respect the choices of the discoverers, a comment period ensued, and in 1995 IUPAC named element 102 flerovium (Fl) as part of a new proposal, after either Georgy Flyorov or his eponymous Flerov Laboratory of Nuclear Reactions.
Sources: en.wikipedia.org
It is a synthetic pentapeptide in the growth hormone secretagogue family and acts as an agonist at the ghrelin receptor. It is handled as a laboratory research compound rather than a naturally occurring hormone.
Studies generally report growth hormone as the dominant output, with smaller or absent effects on adrenocorticotropic hormone and prolactin. The size of that separation depends on the assay and the dose examined, so it is best described as relative selectivity.
No natural source has been identified, and the molecule is produced by chemical synthesis. Its non-natural residues distinguish it from endogenous ghrelin even though both engage the same receptor.
The peptide is Aib-His-D-2-Nal-D-Phe-Lys-NH2. Two of its residues are non-natural, which slows enzymatic degradation. The C-terminal amide is common among bioactive peptides.