Everything below concerns Deamidation. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2026-06-14. Numbers and descriptions here follow the published literature rather than marketing material.
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.
Published evidence comes mainly from Russian-language journals and from a single research group, with small sample sizes and limited independent replication. A few laboratories outside that group have examined related peptides and reported weaker or absent telomerase effects, so the central claim is best described as contested rather than settled. Rodent studies report modest changes in some ageing markers and in survival, but designs vary and control conditions are often sparse. No large randomised trial in humans has been published, and long-term safety data in healthy populations are correspondingly thin.
Epitalon is a synthetic tetrapeptide with the sequence alanine-glutamate-aspartate-glycine, commonly abbreviated AEDG. It was designed at the St. Petersburg Institute of Bioregulation and Gerontology as a short, chemically defined analogue of epithalamin, a fraction obtained from bovine pineal tissue. Small peptide bioregulators of this type formed a long-running line of work there from the 1980s onward. Because the molecule is produced by solid-phase synthesis rather than extraction, its composition is exact and its purity can be measured directly.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white powder | Freeze-dried solid |
| Solubility class | Freely soluble in water | Aqueous buffers also suitable |
| Typical storage temperature | Minus 20 degrees Celsius or colder | Desiccated and light protected |
| Typical analytical method | RP-HPLC with UV detection | 214 nm on C18 column |
| Identity confirmation | Electrospray mass spectrometry | Sequence verified separately |
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.
Laboratory handling begins with dissolution of the lyophilized powder in water or a suitable aqueous buffer. The dry solid is the more stable form, so stock solutions are generally prepared only when required and kept cold afterwards. Repeated freezing and thawing of a solution is avoided because it encourages aggregation and gradual loss of the intact chain. Diluents and containers are selected to limit adsorption of a short peptide onto plastic surfaces and to reduce microbial growth in aqueous preparations.
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.
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.
Epitalon is a synthetic tetrapeptide whose four residues are alanine, glutamate, aspartate and glycine, commonly abbreviated AEDG. Its molecular formula is C14H22N4O9 and its monoisotopic mass is near 390.35 daltons. The peptide carries two acidic side chains, so it is neutral to negatively charged in most aqueous buffers. Published reference summaries usually list it under both spellings, epitalon and epithalon, and treat the two names as the same material.
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.
Human data are limited to small studies, often without the randomization, blinding, or control groups expected in contemporary clinical research. Reported outcomes have included changes in melatonin levels, immune markers, and subjective measures, but sample sizes were generally too small to support firm conclusions. Some reviews treat the peptide as promising while noting methodological weaknesses; others question whether the observed effects are specific. The compound is frequently discussed in longevity-focused communities, where enthusiasm often outpaces the published evidence. Separating established findings from speculation is therefore important when reading summaries of this research.
Epitalon emerged from research conducted in Saint Petersburg by Vladimir Khavinson and colleagues, who studied short peptides as potential regulators of aging. The work built on epithalamin, a pineal gland extract reported to influence neuroendocrine function. Epitalon was designed as a synthetic counterpart with a defined sequence, allowing reproducible experiments that extracts could not support. Early publications described effects on melatonin rhythms and lifespan in animal models. These findings circulated mainly in Russian-language journals during the 1990s, which limited their visibility among English-speaking researchers.
The most widely cited claim is that epitalon activates telomerase and thereby extends telomere length. Supporting evidence comes largely from cultured human cells, where treatment was associated with increased telomerase activity and delayed replicative senescence. Telomerase activation is a biologically consequential effect, since the enzyme is largely silenced in most somatic cells. However, the route by which a short peptide would reach and act on the enzyme's regulatory machinery has not been established. Independent replication in human trials is scarce, so the link between cell-culture observations and whole-body aging remains an open question.
Epitalon is a synthetic tetrapeptide with the amino acid sequence alanine-glutamate-aspartate-glycine, abbreviated Ala-Glu-Asp-Gly or AEDG. It was developed by the Russian researcher Vladimir Khavinson and colleagues during work on peptide bioregulators derived from the pineal gland. The compound is short enough to be produced by standard solid-phase peptide synthesis and is typically handled as a lyophilized white powder. Its small size distinguishes it from larger pineal peptides such as epithalamin, a complex extract from which the tetrapeptide was conceptually derived.
The four residues give epitalon a molecular formula of C14H22N4O9 and a molecular weight near 390.35 daltons. The presence of two acidic residues, glutamate and aspartate, makes the free peptide strongly acidic, while the alanine and glycine ends provide neutral, nonpolar character. This combination produces a molecule with substantial water solubility. Because there are no cysteine, methionine, or tryptophan residues, the peptide lacks the most common oxidation-sensitive side chains, which simplifies handling compared with many longer peptides.
The proposed relationship between epitalon and pineal function is a central part of its background. Khavinson's group reported that short peptides corresponding to regions of larger pineal proteins could influence gene expression in cells. Epitalon was framed as a synthetic analogue of an active fragment rather than a direct isolation product. Whether the tetrapeptide reproduces the effects of the parent extract is an open question, because comparative studies are limited and the parent extract itself is not a single defined substance.
Some mammals have a large larynx and thus a low-pitched voice, namely the hammer-headed bat (Hypsignathus monstrosus) where the larynx can take up the entirety of the thoracic cavity while pushing the lungs, heart, and trachea into the abdomen. Large vocal pads can also lower the pitch, as in the low-pitched roars of big cats. The production of infrasound is possible in some mammals such as the African elephant (Loxodonta spp.) and baleen whales. Small mammals with small larynxes have the ability to produce ultrasound, which can be detected by modifications to the middle ear and cochlea. Ultrasound is inaudible to birds and reptiles, which might have been important during the Mesozoic, when birds and reptiles were the dominant predators. This private channel is used by some rodents in, for example, mother-to-pup communication, and by bats when echolocating. Toothed whales also use echolocation, but, as opposed to the vocal membrane that extends upward from the vocal folds, they have a melon to manipulate sounds. Some mammals, namely the primates, have air sacs attached to the larynx, which may function to lower the resonances or increase the volume of sound. The vocal production system is controlled by the cranial nerve nuclei in the brain, and supplied by the recurrent laryngeal nerve and the superior laryngeal nerve, branches of the vagus nerve. The vocal tract is supplied by the hypoglossal nerve and facial nerves. Electrical stimulation of the periaqueductal gray (PEG) region of the mammalian midbrain elicit vocalizations.
A process for chemical synthesis and isolation of gabapentin with high yield and purity starts with conversion of 1,1-cyclohexanediacetic anhydride to an amide by reaction with a solution of ammonia in isopropanol and is followed by a Hofmann rearrangement in a freshly prepared aqueous solution of sodium hypobromite.
== Medical uses == Succimer is sold under the brand name Chemet among others. It is a medication tool used to treat lead, mercury, and arsenic poisoning. When radiolabeled with technetium-99m, it is used in many types of diagnostic testing. Common side effects include vomiting, diarrhea, rash, and low blood neutrophil levels. Liver problems and allergic reactions may also occur with use. Whether use during pregnancy is safe for the baby is unclear. Dimercaptosuccinic acid is in the chelating agent family of medications. It binds to a metal atom, leading to increased clearance from the body via the urine. A full course of Succimer lasts for 19 days of oral administration. A second course should be given after more than two weeks break after the first course. Succimer has been used medically since the 1950s. It is on the World Health Organization's List of Essential Medicines. In the United States, no generic version was available as of 2015.
== Synthetic monomers == Ethylene gas (H2C=CH2) is the monomer for polyethylene. Other modified ethylene derivatives include: tetrafluoroethylene (F2C=CF2) which leads to Teflon vinyl chloride (H2C=CHCl) which leads to PVC styrene (C6H5CH=CH2) which leads to polystyrene Epoxide monomers may be cross linked with themselves, or with the addition of a co-reactant, to form epoxy BPA is the monomer precursor for polycarbonate Terephthalic acid is a comonomer that, with ethylene glycol, forms polyethylene terephthalate. Dimethylsilicon dichloride is a monomer that, upon hydrolysis, gives polydimethylsiloxane. Ethyl methacrylate is an acrylic monomer that, when combined with an acrylic polymer, catalyzes and forms an acrylate plastic used to create artificial nail extensions
=== Rheopectic or anti-thixotropic === There are also fluids whose strain rate is a function of time. Fluids that require a gradually increasing shear stress to maintain a constant strain rate are referred to as rheopectic. An opposite case of this is a fluid that thins out with time and requires a decreasing stress to maintain a constant strain rate (thixotropic).
Sources: en.wikipedia.org
The 1980s brought early radioligand studies for neuroendocrine tumors (NETs) which continued into the early 2000s. In 2017 the European Union (EU) approved the use of radioligand therapy for NETs with the U.S. following close behind in 2018.
Refers to any of the FDA procedures, such as compassionate use, parallel track, and treatment IND that distribute experimental drugs to participants who are failing on currently available treatments for their condition and also are unable to participate in ongoing clinical trials. (NLM) Expanded access trial
=== Russia and Ukraine === From 2013 to 2022 Galloway was a presenter on the Russian state-controlled television network RT. Galloway called the 2014 Ukrainian Revolution a Western-backed "coup" and a "foreign financed invasion of the sovereignty of Ukraine". He believes Russia's annexation of Crimea was legitimate, because he said the disputed 2014 Crimean status referendum showed that "the huge majority of people in Crimea wanted to leave Ukraine". In a 2016 interview of Nigel Farage, Galloway said "I respect Putin and I think he's very popular in Russia". When Russian opposition leader Alexei Navalny was poisoned in August 2020, Galloway claimed on RT that Navalny was a white supremacist. In early 2022, Galloway dismissed claims that Russia was about to invade Ukraine, writing "I told you it wasn't. You were wrong. I was right". When Russia invaded Ukraine ten days later, he said the invasion was "not what I wanted", but he blamed the invasion on "the West" and accused it of "Pumping Ukraine full of NATO weapons, mercenaries and propaganda". He suggested that the Bucha massacre was staged. Galloway was accused of being an apologist and propagandist for Russian president Vladimir Putin by the larger political parties. Jamie Blackett ended their political alliance All for Unity over their disagreement on Ukraine. The Scottish Liberal Democrats leader, Alex Cole-Hamilton, called Galloway "an apologist for Russian expansionist aggression" and said that Galloway's "association with RT has lent legitimacy and influence to the propaganda apparatus of a hostile power".
Hypervitaminosis A results from excessive intake of preformed vitamin A. Genetic variations in tolerance to vitamin A intake may occur, so the toxic dose will not be the same for everyone. Children are particularly sensitive to vitamin A, with daily intakes of 1500 IU/kg body weight reportedly leading to toxicity.
Biting the fingers and lips is a definitive feature of Lesch–Nyhan syndrome; in other syndromes associated with self-injury, the behaviors usually consist of head banging and nonspecific self-mutilation, but not biting of the cheeks, lips and fingers. Lesch–Nyhan syndrome ought to be clearly considered only when self-injurious behavior takes place in conjunction with hyperuricemia and neurological dysfunction.
Sources: en.wikipedia.org
Two rockets targeted Bannu Cantonment with one hitting a Circuit House and the other landing near a mosque. On 11 March, Pakistani officials stated that they had targeted two Taliban border outposts along the border in Zhob sector, forcing Taliban fighters to abandon their positions and seizing several weapons, including Russian-made 73 mm HGL-9 heavy grenade launchers. In border areas adjacent to Shawal in North Waziristan, Pakistani officials stated that they had targeted and destroyed another Taliban border outpost. Pakistani officials also said that since the onset of hostilities, at least 641 Afghan Taliban operatives had been killed and more than 855 injured. According to them, Pakistani forces had destroyed 243 check posts, captured and subsequently destroyed 42 more, destroyed 219 tanks, armored vehicles and artillery guns, and carried out air strikes on 65 locations across Afghanistan. Chinese Foreign Minister Wang Yi, during a telephone conversation with his Pakistani counterpart, said that China resolutely supported Pakistan's fight against terrorism. He added that Chinese officials were working with Taliban and Pakistani officials to find a path toward reconciliation. On the same day, an Afghan media outlet reported that Taliban were looking for a mediator to help end the conflict with Pakistan. Later that day, local sources report that Pakistani forces carried out artillery attacks in parts of Khost province. Taliban officials confirmed the attacks but said that the attacks injured 2 Afghan civilians and destroyed a number of houses.
Feminist Anne Koedt argued that because men "have orgasms essentially by friction with the vagina" and not the clitoral area, this is why women's biology had not been properly analyzed. "Today, with extensive knowledge of anatomy, with [C. Lombard Kelly], Kinsey, and Masters and Johnson, to mention just a few sources, there is no ignorance on the subject [of the female orgasm]", she stated in her 1970 article The Myth of the Vaginal Orgasm. She added, "There are, however, social reasons why this knowledge has not been popularized. We are living in a male society which has not sought change in women's role". Supporting an anatomical relationship between the clitoris and vagina is a study published in 2005, which investigated the size of the clitoris; Australian urologist Helen O'Connell, described as having initiated discourse among mainstream medical professionals to refocus on and redefine the clitoris, noted a direct relationship between the legs or roots of the clitoris and the erectile tissue of the bulbs and corpora, and the distal urethra and vagina while using magnetic resonance imaging (MRI) technology. While some studies, using ultrasound, have found physiological evidence of the G-spot in women who report having orgasms during vaginal intercourse, O'Connell argues that this interconnected relationship is the physiological explanation for the conjectured G-spot and experience of vaginal orgasms, taking into account the stimulation of the internal parts of the clitoris during vaginal penetration. "The vaginal wall is, in fact, the clitoris", she said.
=== Human exposure === Human exposure varies across the globe and depends on factors such as smoking rates, fuel types in cooking, and pollution controls on power plants, industrial processes, and vehicles. Developed countries with stricter air and water pollution controls, cleaner sources of cooking (that is, gas and electricity versus coal or biofuels), and prohibitions of public smoking tend to have lower levels of PAH exposure, while developing and undeveloped countries tend to have higher levels. Surgical smoke plumes have been proven to contain PAHs in several independent research studies.
Another view is that until the Upper Paleolithic, humans were frugivores (fruit eaters) who supplemented their meals with carrion, eggs, and small prey such as baby birds and mussels, and only on rare occasions managed to kill and consume big game such as antelopes. This view is supported by studies of higher apes, particularly chimpanzees. Chimpanzees are the closest to humans genetically, sharing more than 96% of their DNA code with humans, and their digestive tract is functionally very similar to that of humans. Chimpanzees are primarily frugivores, but they could and would consume and digest animal flesh, given the opportunity. In general, their actual diet in the wild is about 95% plant-based, with the remaining 5% filled with insects, eggs, and baby animals. In some ecosystems, however, chimpanzees are predatory, forming parties to hunt monkeys. Some comparative studies of human and higher primate digestive tracts do suggest that humans have evolved to obtain greater amounts of calories from sources such as animal foods, allowing them to shrink the size of the gastrointestinal tract relative to body mass and to increase the brain mass instead. Anthropologists have diverse opinions about the proportions of plant and animal foods consumed. Just as with still existing hunters and gatherers, there were many varied "diets" in different groups, and also varying through this vast amount of time.
, the Darcy friction factor (also called flow coefficient λ). For laminar flow in a circular pipe of diameter Dc, the friction factor is inversely proportional to the Reynolds number alone (fD = 64/Re) which itself can be expressed in terms of easily measured or published physical quantities (see section below). Making this substitution the Darcy–Weisbach equation is rewritten as
Sources: en.wikipedia.org
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.
Aspartate can cyclise into a succinimide intermediate that later hydrolyses back as isoaspartate. Both forms share the same molecular mass, so mass spectrometry alone cannot tell them apart. This shapes how purity data should be interpreted.
Freeze-dried material is normally kept desiccated below minus twenty degrees Celsius and shielded from light. Solutions are prepared shortly before use and held cold. Repeated thawing is avoided because it accelerates aggregation and degradation.
No. Epithalamin is a peptide-containing extract of bovine pineal glands, while epitalon is a single synthetic tetrapeptide. The extract contains many peptides and other tissue components, so its composition varies between batches in ways that a synthesised sequence does not.