tetrapeptide 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.
Last reviewed on 2026-03-15. Where a claim depends on a specific study, the study is described rather than over-claimed.
The compound is generally described as a synthetic analogue of a fragment isolated from a pineal gland extract. Researchers associated with the Saint Petersburg Institute of Bioregulation and Gerontology introduced it during the 1980s and 1990s while studying short peptides from animal tissue. The original extract, called epithalamin, is a heterogeneous mixture, whereas epitalon is a single defined sequence. That distinction matters because findings reported for the extract are not automatically findings about the pure tetrapeptide, and claims about broader biological effects remain a separate question from the chemical identity described here.
Residue composition is the property that most cleanly separates verified material from mislabelled samples. Alanine, glutamate, aspartate and glycine appear in that order from the N-terminus, and the two acidic residues sit in the middle of the chain. Because the peptide is short, it can be produced by solid-phase synthesis and characterised by mass spectrometry without ambiguity. Any reported sample whose measured mass departs substantially from 390 daltons is a different compound or a degraded mixture rather than epitalon.
Storage practice centres on limiting moisture, oxygen, and repeated temperature cycling. Freeze-dried powder is generally held desiccated at minus twenty degrees Celsius or colder and protected from light. Reconstituted solutions are markedly less stable, and the aspartate-glycine junction is prone to succinimide formation at neutral to mildly alkaline pH. Portioning material into single-use aliquots reduces degradation compared with repeated freeze-thaw cycles. Stability data specific to this tetrapeptide remain scarce, so most handling guidance is extrapolated from general peptide chemistry rather than measured directly.
Documentation accompanying research peptides usually includes a certificate of analysis listing the batch number, purity figure, and test methods applied. Buyers comparing suppliers should check whether the reported purity refers to chromatographic area or to a mass-balance calculation, because the two are not equivalent. Counter-ion content, residual solvents, and water content are sometimes omitted from such certificates even though they affect the actual peptide mass present. Independent verification through a second laboratory is the most direct way to confirm that a supplied material matches its label.
Purity assessment of peptide reagents normally relies on reversed-phase high-performance liquid chromatography. A gradient of acetonitrile in water with trifluoroacetic acid, paired with a C18 stationary phase, separates the target tetrapeptide from truncated sequences and deletion analogues. Detection at 214 nanometres exploits absorbance of the peptide backbone, since the molecule contains no aromatic residue. Results are expressed as a percentage of total peak area. Values above ninety-five percent are typical for research-grade material, although reporting conventions vary between suppliers.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C14H22N4O9 | Derived from the four constituent residues |
| Molecular mass | About 390.35 Da | Monoisotopic value, confirmed by mass spectrometry |
| Residue sequence | Ala-Glu-Asp-Gly | Read from the N-terminus to the C-terminus |
| Common synonyms | Epithalon; AEDG | Both forms appear in reference catalogues |
| Net charge near neutral pH | Negative | Two acidic side chains give a low isoelectric point |
The peptide is a synthetic analogue of epithalamin, a preparation extracted from bovine pineal glands. Investigators sought a short, chemically defined molecule that would reproduce some of the endocrine and gerontological observations attributed to the glandular extract. Proposed mechanisms centre on induction of telomerase activity, an effect reported in cultured human somatic cells in the early 2000s, together with influences on melatonin secretion and neuroendocrine regulation. Those mechanisms remain incompletely characterised, and the reported telomerase response has not been consistently reproduced by independent groups working in comparable systems.
Published work on this compound consists mainly of in vitro experiments, animal studies, and small clinical investigations, a substantial share of which appeared in Russian-language journals. Sample sizes are generally small, control conditions differ between studies, and several endpoints rely on markers whose clinical meaning is itself debated. Reviews of the longevity field treat the peptide as an early example of telomerase-directed research rather than an established intervention. Regulatory treatment varies by country: some jurisdictions place it under prescription controls, others treat it as a laboratory material, and importation may be restricted regardless of local status.
Freeze-dried epitalon is normally kept at minus twenty degrees Celsius in a sealed, desiccated container, protected from light. Short excursions at ambient temperature during shipping are generally tolerated, but repeated warming and cooling cycles encourage moisture uptake, which shortens shelf life. Once dissolved, the peptide is far less stable than the solid: aqueous solutions are subject to hydrolysis and to deamidation at the aspartate and glutamate residues. Working solutions are therefore held refrigerated and used within days, and repeated freezing and thawing of the same vial is best avoided.
Identity and purity are checked by reversed-phase high-performance liquid chromatography, usually with ultraviolet detection near 214 nanometres, where the peptide bond absorbs. Mass spectrometry confirms the expected mass and reveals whether truncation products or adducts are present. Acid hydrolysis followed by amino acid analysis gives the residue ratio, which should approximate one alanine, one glutamate, one aspartate and one glycine. Counter-ions such as acetate or trifluoroacetate remain in the dried product and lower net peptide content, so a stated purity figure on a label does not by itself describe how much peptide a vial holds.
The Original Mels chain has 22 locations across Northern California and Nevada. There are some Northern California locations that share the same general American Graffiti nostalgia theme and the similarly styled Mel's logo.
== History == The forerunner of the present-day company was called Kyowa Hakko Kogyo Co., Ltd (協和醱酵工業株式会社, lit. 'Coordinated Fermentation Industry Share Company') and was established on July 1, 1949. The company merged with Kirin Pharma Co., Ltd., on October 1, 2008 to form Kyowa Hakko Kirin (KHK) with plans to spin off the bio-chemical business into Kyowa Hakko Bio. On July 11, 2014, the KHK subsidiary, ProStrakan Group (based in Scotland), acquired Archimedes Pharma from the Novo Nordisk Foundation for $394 million. In 2019, Kirin Holdings acquired 95% stake in Kyowa Hakko Bio which is Kyowa Kirin's subsidiary corporation. The entity was renamed "Kyowa Kirin Co., Ltd.", replacing its prior name of Kyowa Hakko Kirin Co., Ltd. In November 2022, Kyowa Kirin announced plans to spin its International Established Medicines portfolio, consisting of 13 brands, into a new joint venture with German company Grünenthal. The joint venture would expand Grüenthal's already extensive pain management portfolio, while Kyowa Kirin saw it as a financial benefit and an opportunity to expand the brands. In October 2023, Kyowa Kirin acquired a Britain-based biopharmaceutical company, Orchard Therapeutics, for $478 million, aiming to expand their portfolio.
There are many variants in the size and shape of the thyroid gland, and in the position of the embedded parathyroid glands. Sometimes there is a third lobe present called the pyramidal lobe. When present, this lobe often stretches up to the hyoid bone from the thyroid isthmus and may be one to several divided lobes. The presence of this lobe ranges in reported studies from 18.3% to 44.6%. It was shown to more often arise from the left side and occasionally separated. The pyramidal lobe is also known as Lalouette's pyramid. The pyramidal lobe is a remnant of the thyroglossal duct, which usually wastes away during the thyroid gland's descent. Small accessory thyroid glands may in fact occur anywhere along the thyroglossal duct, from the foramen cecum of the tongue to the position of the thyroid in the adult. A small horn at the back of the thyroid lobes, usually close to the recurrent laryngeal nerve and the inferior thyroid artery, is called Zuckerkandl's tubercle. Other variants include a levator muscle of thyroid gland, connecting the isthmus to the body of the hyoid bone, and the presence of the small thyroid ima artery.
=== Since 1873 === On January 1, 1873, Japan adopted the Gregorian calendar. To convert any Gregorian calendar year between 1873 and 1912 to Japanese calendar year in Meiji era, 1867 needs to be subtracted from the year in question.
Aquacultured shellfish include various oyster, mussel, and clam species. These bivalves are filter and/or deposit feeders, which rely on ambient primary production rather than inputs of fish or other feed. As such, shellfish aquaculture is generally perceived as benign or even beneficial. Depending on the species and local conditions, bivalve molluscs are either grown on the beach, on longlines, or suspended from rafts and harvested by hand or by dredging. In May 2017 a Belgian consortium installed the first of two trial mussel farms on a wind farm in the North Sea. Abalone farming began in the late 1950s and early 1960s in Japan and China. Since the mid-1990s, this industry has become increasingly successful. Overfishing and poaching have reduced wild populations to the extent that farmed abalone now supplies most abalone meat. Sustainably farmed molluscs can be certified by Seafood Watch and other organizations, including the World Wildlife Fund (WWF). WWF initiated the "Aquaculture Dialogues" in 2004 to develop measurable and performance-based standards for responsibly farmed seafood. In 2009, WWF co-founded the Aquaculture Stewardship Council with the Dutch Sustainable Trade Initiative to manage the global standards and certification programs. After trials in 2012, a commercial "sea ranch" was set up in Flinders Bay, Western Australia, to raise abalone. The ranch is based on an artificial reef made up of 5000 (As of April 2016) separate concrete units called abitats (abalone habitats). The 900 kg abitats can host 400 abalone each.
Sources: en.wikipedia.org
== The HDP-mimetic pipeline == Development is ongoing for numerous brilacidin analogs, selected by laboratory testing of the various HDP mimetics and defensin-mimetic compounds in the antibiotic pipeline. Pre-clinical research has been shown select brilacidin analogs effective in killing a variety of important Gram-negative pathogens (the so-called superbugs), such as Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli and Acinetobacter baumannii as well as highly multi-drug resistant ndm-1-producing K. pneumoniae. An abstract update on these efforts was presented at the European Congress of Clinical Microbiology and Infectious Disease (ECCMID) 2015 annual conference. The footnote links to the full presentation. Other HDP-Mimetic analogs have proven effective in vitro against C. albicans and other Candida species. Also acquired with brilacidin and the HDP-mimetic pipeline were the rights to the related PolyCide family of compounds, polymeric formulations that function as antimicrobial agents. These compounds are similar to brilacidin in that they are also synthetic mimics of HDPs. These compounds have superior bacterial killing activity over triclosan and silver nitrate, common biocidal agents. PolyCide compounds could be used as additives to paints, plastics, textiles and other materials to create self-sterilizing products and surfaces.
The parasagittal (Greek πᾰρᾰ́ (pará), beside) or paramedian or sagittal planes (Latin sagitta, arrow), which include the median or midsagittal plane and divide the body into left and right (in reference to the subject and not the observer). The frontal or coronal plane (Latin corona, crown), which divide the body into front and back. The axial or horizontal or transverse plane (Latin trans, across; vetere, to turn), which is perpendicular to the other two planes. The transpyloric plane, the subcostal plane, and the transumbilical plane planes are also considered in the division of the torso into the quadrants and regions of the abdomen. The three main axes of a human are the left-right (or horizontal or frontal), the craniocaudal (or rostrocaudal, longitudinal, or cephalocaudal), and the anteroposterior (or dorsoventral or sagittal) axes. Other anatomical lines include the axillary lines, parasternal line, and scapular line.
In patients on a vitamin K antagonist such as warfarin with supratherapeutic INR but INR less than 10 and no bleeding, it is enough to lower the dose or omit a dose, monitor the INR and resume the vitamin K antagonist at an adjusted lower dose when the target INR is reached. For people who need rapid reversal of the vitamin K antagonist – such as due to serious bleeding – or who need emergency surgery, the effects of warfarin can be reversed with vitamin K, prothrombin complex concentrate (PCC), or fresh frozen plasma (FFP).
After a slow start in the final's first two events, after which he found himself 7 points behind the leader in seventh place, he proceeded to dominate the rest of the event with five first place finishes in a row in the final five disciplines, winning the title with an event to spare. In the 2006 World's Strongest Man contest, despite starting the final well, he eventually came second to Phil Pfister after the American won the final five events in a row. Pudzianowski regained his title in 2007, winning the final with one event to spare for a record-breaking third time. In so doing, he joined Jon Pall Sigmarsson and Magnus Ver Magnusson as the only men to win the competition four times. During the 2007 competition, however, Pudzianowski said that his target was to become the only person to win the event five times, and he returned to the 2008 World's Strongest Man the following year to try to achieve his goal. Despite a serious calf injury suffered in the Polish Strongman Championship Cup of 2008 and further exacerbated during the WSM qualifying rounds, Pudzianowski still managed to win his heat and qualify for the final. However, it was clear his dominance of previous years was no longer in effect, as he only won one of the first five events in the final, and finished in fifth in two others. Trailing leader Derek Poundstone with two events to go, Pudzianowski managed to win the Plane Pull despite his injured calf to cut the deficit to just 1 point going into the final event.
Sources: en.wikipedia.org
where ci and zi stand for the concentration and ionic charge of ion type i, and the sum is taken over all the N types of charged species in solution. When the concentration of dissolved salt is much higher than the analytical concentrations of the reagents, the ions originating from the dissolved salt determine the ionic strength, and the ionic strength is effectively constant. Since activity coefficients depend on ionic strength, the activity coefficients of the species are effectively independent of concentration. Thus, the assumption that Γ is constant is justified. The concentration quotient is a simple multiple of the equilibrium constant.
18 June to 15 August The 101st Airborne Division launched Operation Montgomery Rendezvous in western Thừa Thiên Province to interdict PAVN infiltration routes and forestall attacks on Huế. The operation results in 393 PAVN killed and 87 U.S. killed.
She performed all of this contingency EVA. After 176 days, 1 hour, 18 minutes and 38 seconds in space, Caldwell Dyson landed in Kazakhstan on September 25, 2010. During this spaceflight, she completed three spacewalks, logging 22 hrs and 49 minutes of EVA work to replace a malfunctioning coolant pump.
Sources: en.wikipedia.org
It is a four-amino-acid peptide built from alanine, glutamate, aspartate and glycine in that order. Its formula is C14H22N4O9, and it is made by chemical synthesis rather than extracted from tissue. The synthetic peptide is a single defined molecule, unlike the pineal extracts it is often compared with.
No. The two spellings refer to the same tetrapeptide, and the difference reflects transliteration from Russian. Laboratories and catalogues use both forms interchangeably. The material is also indexed as AEDG, taken from the one-letter codes of its residues.
Epithalamin is a mixed preparation derived from animal pineal tissue and contains many peptides. Epitalon is one synthetic sequence chosen for study from that broader mixture. Statements about one do not transfer directly to the other.
Reversed-phase high-performance liquid chromatography with ultraviolet detection at 214 nanometres is the usual approach. Peak area percentage provides a purity figure relative to other components in the sample. Mass spectrometry is then applied to confirm identity.