If you have been reading about tetrapeptide and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Updated 2025-09-25. Numbers and descriptions here follow the published literature rather than marketing material.
Epitalon is a synthetic four-amino-acid peptide with the sequence alanine-glutamate-aspartate-glycine, commonly abbreviated AEDG. Its molecular formula is C14H22N4O9, and its calculated molar mass is approximately 390.35 grams per mole. The compound is a short fragment related to a peptide fraction isolated from bovine pineal gland extracts, and it is normally supplied as a lyophilised powder intended for laboratory research. It is not a registered pharmaceutical product in most countries.
The peptide emerged from research carried out in Saint Petersburg from the late 1980s onward, where investigators searched for shorter active fragments of a pineal preparation known as epithalamin. The name epitalon was chosen to reflect that parent extract. Early reports described effects on neuroendocrine markers and on the lifespan of laboratory animals. Much of that work appeared in Russian-language journals, with English translations following later, which affects how readily the original protocols can be assessed by outside groups.
Identity and purity of epitalon samples are normally established by reversed-phase high-performance liquid chromatography with ultraviolet detection near 214 nanometres, combined with mass spectrometry. The mass spectrum confirms the expected molecular ion and can reveal truncated or oxidised by-products. Amino acid analysis after acid hydrolysis verifies that the four residues are present in the expected ratio. Certificates typically report a purity figure taken from chromatographic peak area, expressed as a percentage of total integrated signal.
Lyophilised epitalon is generally held at minus twenty degrees Celsius in a sealed container kept dry and dark. Cooler conditions are sometimes recommended for long-term archives. The solid takes up moisture readily enough that repeated opening of a vial introduces water, so dividing a batch into smaller portions before storage lowers degradation risk. Aqueous solutions are less durable than the dry powder and are usually prepared shortly before use, then kept cold and shielded from light to slow hydrolysis and oxidation.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C14H22N4O9 | Derived from the four-residue sequence |
| Molar mass | About 390.35 g/mol | Free peptide, counter-ion not included |
| Appearance | White to off-white powder | Lyophilised solid from aqueous solution |
| Water solubility | Freely soluble | Short, polar peptide chain |
| Common synonyms | AEDG; epithalone | Catalogues use the names interchangeably |
Epitalon is a synthetic tetrapeptide whose sequence is alanine-glutamate-aspartate-glycine, written in single-letter code as AEDG. The four residues are joined by three peptide bonds, giving a linear backbone with no branching and no disulfide bridges. Its calculated molecular mass for the free form is approximately 390.3 daltons, a figure that rises when the compound is supplied as an acetate or trifluoroacetate salt. Because the chain is short, the molecule is defined entirely by its residue order rather than by any folded three-dimensional structure.
The compound is described in the literature as a derivative of epithalamin, a preparation obtained from bovine pineal tissue. Work on this peptide family was carried out mainly by a research group in Saint Petersburg beginning in the 1980s, and the substance was later registered for clinical use in Russia under the name Epitalon. Outside that region it is generally treated as a research chemical rather than an approved medicine. Statements about its biological activity rest on a relatively small number of studies, and independent replication remains limited.
Stability depends strongly on pH, temperature and the presence of oxygen and trace metals. Cleavage of the backbone proceeds faster under neutral to alkaline conditions, whereas acidic solutions tend to slow that reaction. The aspartate and glutamate side chains can undergo deamidation or imide formation over time, generating closely related impurities. Published stability data specific to epitalon are sparse, so the usable life of a given solution is best regarded as an open question that depends on buffer composition, concentration and storage temperature.
Identity and purity are usually assessed by reversed-phase high-performance liquid chromatography with ultraviolet detection, frequently near 214 nanometers where the peptide bond absorbs. Mass spectrometry, most often with electrospray ionization, confirms the observed molecular mass and helps separate the intact peptide from truncated or modified forms. Amino acid analysis or tandem mass spectrometry can establish residue order. Purity is commonly quoted as an area percentage, yet such values are method-dependent, and comparisons between laboratories require matching column, gradient and detection wavelength.
== Therapeutic touch and nursing education == Sokal, in 2006, reported generally accepted estimates of over 80 colleges and universities spread over 70 countries where therapeutic touch is taught, as well as some 80 hospitals in North America where it is practiced. He added that "these figures should be taken with a grain of salt, since both advocates and detractors [...] have an interest in exaggerating its incidence". Owen Hammer and James Underdown of the Independent Investigations Group examined nursing standards in California, where the California Board of Registered Nursing can award registered nurses taking classes in therapeutic touch with continuing education units required for licensure renewal. In 2006, Hammer and Underdown presented the board with the scientific evidence refuting the validity of therapeutic touch as a legitimate treatment, but the board did not change its policy.
== Standardized nomenclature == There are multiple conventions for naming polymer substances. Many commonly used polymers, such as those found in consumer products, are referred to by a common or trivial name. The trivial name is assigned based on historical precedent or popular usage rather than a standardized naming convention. Both the American Chemical Society (ACS) and IUPAC have proposed standardized naming conventions; the ACS and IUPAC conventions are similar but not identical. Examples of the differences between the various naming conventions are given in the table below:
A symbiotic culture of bacteria and yeast (SCOBY) is a culinary symbiotic fermentation culture (starter) consisting of lactic acid bacteria (LAB), acetic acid bacteria (AAB), and yeast which arises in the preparation of sour foods and beverages such as kombucha. Beer and wine also undergo fermentation with yeast, but the LAB and AAB components unique to the SCOBY are usually viewed as a source of spoilage rather than a desired addition. Both LAB and AAB enter on the surface of barley and malt in beer fermentation and grapes in wine fermentation; LAB lowers the pH of the beer or wine while AAB takes the ethanol produced from the yeast and oxidizes it further into vinegar, resulting in a sour taste and smell. AAB are also responsible for the formation of the cellulose SCOBY. SCOBY most accurately refers to the culture of bacteria and yeast suspended in the fermentation media, but it also is commonly used to refer to the gelatinous biofilm or microbial mat found floating at the container's air–liquid interface. This bacterial cellulose mat is referred to as a pellicle, and consists of a dense cellulose matrix with embedded bacteria and yeast cultures. SCOBY pellicles, like other fermentation starters, can serve the purpose of continuing the fermentation process into a new vessel and reproducing the desired product. This is done by introducing some of the previous culture to new, unfermented media.
Sources: en.wikipedia.org
== Personal life == Best later claimed that the greatest moment of his life occurred when he met his future wife, Margaret Mahon (1900–1988) following his return. Best married Margaret Hooper Mahon in Toronto in 1924 and they had two sons. Best's eldest son was Charles Alexander Best, a Canadian politician and geneticist. Best is the grandfather of Susan MacTavish Best. His other son, Henry Best was a well-regarded historian who later became president of Laurentian University in Sudbury, Ontario. Best died on March 31, 1978, in Toronto. He is interred in Mount Pleasant Cemetery, Toronto, not far from Sir Frederick Banting.
Only some of the Ruthenian szlachta of the Chernigov region, who had their origins in the Moscow state, saved their lands from division among Cossacks and became part of the Cossack szlachta. After this, the Ruthenian szlachta refrained from plans to have a Moscow Tsar as king of the Commonwealth, its own Michał Korybut Wiśniowiecki later becoming king. The last, ultimately unsuccessful, attempt to rebuild the Polish–Cossack alliance and create a Polish–Lithuanian–Ruthenian Commonwealth was the 1658 Treaty of Hadiach. The treaty was approved by the Polish king and the Sejm, and by some of the Cossack starshyna, including hetman Ivan Vyhovsky. The treaty failed, however, because the starshyna were divided on the issue, and it had even less support among rank-and-file Cossacks.
By 12 January 2020, five genomes of SARS‑CoV‑2 had been isolated from Wuhan and reported by the Chinese Center for Disease Control and Prevention (CCDC) and other institutions; the number of genomes increased to 42 by 30 January 2020. A phylogenetic analysis of those samples showed they were "highly related with at most seven mutations relative to a common ancestor", implying that the first human infection occurred in November or December 2019. Examination of the topology of the phylogenetic tree at the start of the pandemic also found high similarities between human isolates. As of 21 August 2021, 3,422 SARS‑CoV‑2 genomes, belonging to 19 strains, sampled on all continents except Antarctica were publicly available. On 11 February 2020, the International Committee on Taxonomy of Viruses announced that according to existing rules that compute hierarchical relationships among coronaviruses based on five conserved sequences of nucleic acids, the differences between what was then called 2019-nCoV and the virus from the 2003 SARS outbreak were insufficient to make them separate viral species. Therefore, they identified 2019-nCoV as a virus of severe acute respiratory syndrome–related coronavirus. In July 2020, scientists reported that a more infectious SARS‑CoV‑2 variant with spike protein variant G614 has replaced D614 as the dominant form in the pandemic. Coronavirus genomes and subgenomes encode six open reading frames (ORFs). In October 2020, researchers discovered a possible overlapping gene named ORF3d, in the SARS‑CoV‑2 genome.
Sources: en.wikipedia.org
In 1998, Firehouse Subs surpassed 10 locations, and later that year opened the first location outside of Florida. In 2000, the founders decided to take a different approach, using consultants to plan franchise growth. They were able to set up financing for potential franchisees. The second wave of franchising began in 2001. In 2011, Firehouse Subs opened its first franchises in the U.S. territory of Puerto Rico, via local franchisee Caribbean Restaurants. By 2012 the company reached 500 locations, ending the year with nearly 600. In July 2016, Firehouse Subs opened its 1,000th location. In 2015, Firehouse Subs opened its first locations in Canada, with its first location opening in Oshawa, Ontario in October with franchisee OnFire Restaurant Group. Currently, the group operates 50 Canadian restaurants, with plans to open a total of 90 in Ontario alone. The chain also launched a loyalty program. In June 2017, Firehouse Subs opened its first airport location at Jacksonville International. In December 2017, the brand's second airport location opened at Orlando International. In April 2018, the chain opened its first on-campus location at Western New England University. In 2020 the chain opened a location at Jacksonville's Baptist Medical Center. On November 15, 2021, Burger King parent Restaurant Brands International announced that it would acquire Firehouse Subs for $1 billion. The acquisition was completed on December 15, 2021. On June 22, 2023, Firehouse Subs opened its first location outside North America in Zurich, Switzerland.
Growth hormone–releasing hormone (GHRH), also known as somatocrinin among other names in its endogenous form and as somatorelin (INN) in its pharmaceutical form, is a releasing hormone of growth hormone (GH). It is a 44-amino acid peptide hormone produced in the arcuate nucleus of the hypothalamus. GHRH first appears in the human hypothalamus between 18 and 29 weeks of gestation, which corresponds to the start of production of growth hormone and other somatotropes in fetuses.
== Side effects == Oclacitinib lacks the side effects that most JAK inhibitors have in humans; instead, side effects are infrequent, mild, and mostly self-limiting. The most common side effects are gastrointestinal problems (vomiting, diarrhea, and appetite loss) and lethargy. The GI problems can sometimes be alleviated by giving oclacitinib with food. New cutaneous or subcutaneous lumps, such as papillomas, can appear, and dogs face an increased susceptibility to infections such as demodicosis. There is a transient decrease in neutrophils, eosinophils, and monocytes, as well as in serum globulin, while cholesterol and lipase levels increase. The decrease in white blood cells lasts only around 14 days. None of the increases or decreases are clinically significant (i.e. none push their corresponding values out of normal ranges). Less common side effects of oclacitinib include bloody diarrhea; pneumonia; infections of the skin, ear, and/or urinary tract; and histiocytomas (benign tumors). Increases in appetite, aggression, and thirst have also been reported.
=== Dosimetry === The radiation absorbed dose is the amount energy absorbed per unit weight of the target material. Dose is used because, when the same substance is given the same dose, similar changes are observed in the target material(Gy or J/kg). Dosimeters are used to measure dose, and are small components that, when exposed to ionizing radiation, change measurable physical attributes to a degree that can be correlated to the dose received. Measuring dose (dosimetry) involves exposing one or more dosimeters along with the target material. For purposes of legislation doses are divided into low (up to 1 kGy), medium (1 kGy to 10 kGy), and high-dose applications (above 10 kGy). High-dose applications are above those currently permitted in the US for commercial food items by the FDA and other regulators around the world, though these doses are approved for non commercial applications, such as sterilizing frozen meat for NASA astronauts (doses of 44 kGy) and food for hospital patients. The ratio of the maximum dose permitted at the outer edge (Dmax) to the minimum limit to achieve processing conditions (Dmin) determines the uniformity of dose distribution. This ratio determines how uniform the irradiation process is.
Sources: en.wikipedia.org
It is a synthetic tetrapeptide built from alanine, glutamate, aspartate and glycine. The four residues are joined by standard peptide bonds, giving a linear chain rather than a branched structure.
The name derives from epithalamin, a pineal gland extract studied in the former Soviet Union. Researchers proposed that short fragments of that extract carried the biological activity of interest.
No major regulatory agency has approved it as a medicine. It is handled as a research chemical, and products sold under this name are not standardised drugs with defined clinical labelling.
The usual approach is reversed-phase HPLC with ultraviolet detection, reported as a percentage of total peak area. Mass spectrometry is used alongside chromatography to confirm identity rather than purity alone.