Everything below concerns freeze-thaw cycling. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2026-01-05. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
The most frequently cited proposed action is induction of telomerase, the enzyme that adds repeat sequences to chromosome ends. Cell-culture work from the originating group reported higher telomerase reverse transcriptase expression and measurable telomere elongation in human somatic cells after exposure. How a four-residue peptide would reach nuclear gene regulation is not established, and no cell-surface receptor or uptake route has been identified. Additional reports describe changes in melatonin secretion, antioxidant enzyme activity and lipid peroxidation in aged animals, but these findings remain mechanistically unconnected to the telomerase observation.
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.
Solubility is high in water, phosphate-buffered saline and normal saline, a pattern that follows from the two acidic residues in the chain. The peptide dissolves poorly in non-polar solvents such as hexane or chloroform. Stock solutions are often prepared in water first and then diluted into the buffer of interest. Because the molecule is small and hydrophilic, filtration through a low-protein-binding membrane is usually straightforward, and visible particulates are uncommon in freshly made solutions.
Identity and purity are established with reversed-phase high-performance liquid chromatography and mass spectrometry. The chromatogram shows the main peak and any truncated or oxidised by-products, while the mass spectrum confirms the expected 390 dalton mass. Amino acid analysis can corroborate composition when a sample's origin is uncertain. Counterion content, particularly residual trifluoroacetate from purification, is frequently reported alongside purity because it shifts the net mass of the solid.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C14H22N4O9 | Calculated from the four residues with three water losses |
| Molecular mass | About 390.35 g/mol | Monoisotopic mass near 390.14, used for mass-spectrometric identification |
| Peptide sequence | Ala-Glu-Asp-Gly | Single-letter form AEDG; no disulfide bonds or modified residues |
| Appearance | White to off-white solid | Supplied as a dried powder |
| Isoelectric point | Around 4 | Estimated from aspartate and glutamate side-chain pKa values |
Material supplied for laboratory use is normally a lyophilised white to off-white powder that dissolves readily in water and in isotonic saline. Lyophilised cakes are hygroscopic and should be equilibrated to room temperature before opening to limit condensation on the solid. Solutions are typically prepared at milligram-per-millilitre concentrations and divided into single-use aliquots, because repeated freeze–thaw cycles degrade short peptides. Aqueous solutions are far less stable than the dry powder, and identity is usually verified by mass spectrometry alongside purity estimation from reversed-phase high-performance liquid chromatography.
Epitalon is a synthetic linear tetrapeptide with the sequence alanine–glutamate–aspartate–glycine, abbreviated AEDG. Its molecular formula is C14H22N4O9 and the calculated mass is approximately 390.35 g/mol. The compound is made by solid-phase peptide synthesis rather than extracted from tissue, although early work described it as a short fragment of a peptide fraction obtained from bovine pineal extract. In the research literature the spelling epitalon and the variant epithalone both appear, while AEDG is the standard code used in peptide nomenclature.
Several names circulate for the same molecule, including epitalon, epithalone, epithalamin tetrapeptide, and the sequence code AEDG. A CAS registry number, 307297-39-8, is commonly cited for it, though catalogue entries should be checked against supplier documentation because mislabelled records occur. In its usual form the peptide carries free amino and carboxyl termini and is neither glycosylated nor lipidated. Researchers distinguish the defined tetrapeptide from epithalamin itself, a crude pineal preparation containing many peptides that is not chemically characterised.
Reversed-phase high-performance liquid chromatography is the standard approach for assessing purity, usually with ultraviolet detection near 214 nm, where the peptide bond absorbs. Mass spectrometry, most often with electrospray ionization, confirms the molecular mass and helps reveal truncation or deletion byproducts. Amino acid analysis can verify composition, and counterion content is sometimes measured because peptides purified with trifluoroacetic acid retain variable amounts of that salt. Purity figures reported without a stated method and detection wavelength are difficult to interpret.
Material sold for research use varies widely in documented quality. A useful verification package includes a certificate of analysis that states peptide content rather than only net weight, the chromatographic method and column used, and a mass spectrum consistent with the expected mass. Independent testing by a third-party laboratory is occasionally reported. Statements of identity resting only on a supplier label provide little assurance, and the gap between nominal mass and actual peptide content can be substantial once counterions and residual water are counted.
Interest in epitalon is usually discussed within the broader field of short peptide bioregulators, a category that includes other synthetic di-, tri-, and tetrapeptides studied by the same research group. These compounds share a common rationale: that small fragments of tissue-derived proteins can retain biological activity and can be produced reproducibly. The category as a whole remains outside mainstream pharmacological consensus, and epitalon specifically has a limited presence in independent, non-Russian research literature, which shapes how its evidence base is described.
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.
During the 18th century, systems of plant identification were developed comparable to dichotomous keys, where unidentified plants are placed into taxonomic groups (e.g. family, genus and species) by making a series of choices between pairs of characters. The choice and sequence of the characters may be artificial in keys designed purely for identification (diagnostic keys) or more closely related to the natural or phyletic order of the taxa in synoptic keys. By the 18th century, unidentified plants were arriving in Europe in increasing numbers from newly explored areas and European colonies. In 1753, Carl Linnaeus published his Species Plantarum, a hierarchical classification of plant species that remains the reference point for modern botanical nomenclature. This established a standardised binomial or two-part naming scheme where the first name represented the genus and the second identified the species within the genus. For the purposes of identification, Linnaeus's Systema Sexuale classified plants into 24 groups according to the number of their male sexual organs. The 24th group, Cryptogamia, included all plants with concealed reproductive parts: mosses, liverworts, ferns, algae and fungi. Increasing knowledge of plant anatomy, morphology and life cycles led to the realisation that there were more natural affinities between plants than the artificial sexual system of Linnaeus.
The Chanka people lived in the Huancavelica, Ayacucho, and Apurímac regions of Peru. The Huanca people of the Junín Region of Peru spoke Quechua before the Incas did. The Inca established the largest empire of the pre-Columbian era. The Chincha, an extinct merchant kingdom of the Chincha Islands of Peru. The Qolla inhabited the Potosí, Oruro, and La Paz departments of Bolivia. The Cañari of Ecuador adopted the Quechua language from the Inca. The speakers of Quechua total some 5.1 million people in Peru, 1.8 million in Bolivia, 2.5 million in Ecuador (Hornberger and King, 2001), and according to Ethnologue (2006) 33,800 in Chile, 55,500 in Argentina, and a few hundred in Brazil. Only a slight sense of common identity exists among these speakers spread all over Peru, Bolivia and Ecuador. The various Quechua dialects are in some cases so different from one another that mutual understanding is not possible. Quechua was spoken not only by the Incas, but also by long-term enemies of the Inca Empire, including the Huanca (Wanka is a Quechua dialect spoken today in the Huancayo area) and the Chanka (the Chanca dialect of Ayacucho) of Peru, and the Kañari (Cañari) in Ecuador. Quechua was spoken by some of these people, for example, the Wanka, before the Incas of Cusco, while other people, especially in Bolivia but also in Ecuador, adopted Quechua only in Inca times or afterward. Some Christian organizations also refer to a "Quechua people", such as the Christian shortwave radio station HCJB, "The Voice of the Andes" (La Voz de los Andes).
Closely monitoring a patient's condition but withholding treatment until symptoms appear or change. Also called watchful waiting, active surveillance, and expectant management. (NCI) Observational study
=== Jcom radio libel case === In November 2007, Jewish radio station Jcom aired a satirical segment in which a character named 'Georgie Galloway' used the anti-Semitic catchphrase "kill the Jews, kill the Jews". Galloway sued the station for libel and won the case in the High Court. Galloway was awarded £15,000 in damages and around £5,000 in costs. The radio station closed after losing the case. Galloway said the judgment had "categorically crushed the slur of anti-Semitism" against him.
Sources: en.wikipedia.org
A-DNA One of three main biologically active structural conformations of the DNA double helix, along with B-DNA and Z-DNA. The A-form helix has a right-handed twist with 11 base pairs per full turn, only slightly more compact than B-DNA, but its bases are sharply tilted with respect to the helical axis. It is often favored in dehydrated conditions and within sequences of consecutive purine nucleotides (e.g. GAAGGGGA); it is also the primary conformation adopted by double-stranded RNA and RNA-DNA hybrids.
=== 1982 World's Fair === In 1974, Downtown Knoxville Association president Stewart Evans, following a discussion with King Cole, president of the 1974 Spokane Exposition, raised the possibility of a similar international exposition for Knoxville. Testerman and Tyree both embraced the fair, though the city council and Knoxvillians in general were initially lukewarm to the idea. One key supporter of the fair was rogue banker Jake Butcher, who in 1975 seized control of Knoxville's largest bank, Hamilton National, and shook up the city's conservative banking community. Following his failed gubernatorial campaign in 1978, Butcher turned his attention to the fair initiative, and helped the city raise critical funding. To prepare for the World's Fair, the merged stretch of I-40 and I-75 in West Knoxville was widened, and I-640 was constructed. The old L&N yard along Second Creek, home to a rough neighborhood known as "Scuffletown," was chosen for the fair site, largely for its redevelopment potential. Three hotel chains— Radisson, Hilton, and Holiday Inn— built large hotels in the downtown area in anticipation of the influx of fair visitors. The fair, officially named the International Energy Exposition, was open from May 1 to October 31, 1982, and drew over 11 million visitors. Its success defied the expectations of the Wall Street Journal, which had derided Knoxville as a "scruffy little town," and had predicted the fair would fail.
The physical examination is the examination of the patient for medical signs of disease that are objective and observable, in contrast to symptoms that are volunteered by the patient and are not necessarily objectively observable. The healthcare provider uses sight, hearing, touch, and sometimes smell (e.g., in infection, uremia, diabetic ketoacidosis). Four actions are the basis of physical examination: inspection, palpation (feel), percussion (tap to determine resonance characteristics), and auscultation (listen), generally in that order, although auscultation occurs prior to percussion and palpation for abdominal assessments. The clinical examination involves the study of:
== Structure and spectroscopy == The C−N=C=N−C core of carbodiimides (N=C=N) is linear, being related to the structure of allene. The molecule has idealized C2 symmetry. The N=C=N moiety gives characteristic IR spectroscopic signature at 2117 cm−1. The 15N NMR spectrum shows a characteristic shift of 275 ppm upfield of nitric acid and the 13C NMR spectrum features a peak at about 139 ppm downfield from TMS.
Opipramol acts as a high affinity sigma receptor agonist, primarily of the σ1 subtype, but also of the σ2 subtype with lower affinity. In one study of σ1 receptor ligands that also included haloperidol, pentazocine, (+)-3-PPP, ditolylguanidine, dextromethorphan, SKF-10,047 ((±)-alazocine), ifenprodil, progesterone, and others, opipramol showed the highest affinity (Ki = 0.2–0.3) for the guinea pig σ1 receptor of all the tested ligands except haloperidol, which it was approximately equipotent with. The sigma receptor agonism of opipramol is thought to be responsible for its therapeutic benefits against anxiety and depression. Unlike other TCAs, opipramol does not inhibit the reuptake of serotonin or norepinephrine. However, it does act as a high affinity antagonist of the histamine H1 receptor and is a low to moderate affinity antagonist of the dopamine D2, serotonin 5-HT2, and α1-adrenergic receptors. H1 receptor antagonism accounts for its antihistamine effects and associated sedative side effects. In contrast to other TCAs, opipramol has very low affinity for the muscarinic acetylcholine receptors and virtually no anticholinergic effects. Sigma receptors are a set of proteins located in the endoplasmic reticulum. σ1 receptors play key role in potentiating intracellular calcium mobilization thereby acting as sensor or modulator of calcium signaling. Occupancy of σ1 receptors by agonists causes translocation of the receptor from endoplasmic reticulum to peripheral areas (membranes) where the σ1 receptors cause neurotransmitter release.
Sources: en.wikipedia.org
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.
It is not recognised as an endogenous peptide hormone. The four-residue sequence can appear inside larger proteins and in digestive fragments of dietary protein, but no dedicated pathway producing it as a signalling molecule has been identified.
Several cell-culture reports describe increased telomerase activity after treatment, measured by enzyme assays or by transcript levels. Results differ between cell types and laboratories, and measured telomere lengthening has been reported in some studies but not in others, which leaves the physiological relevance open.
Sealed lyophilised powder is normally kept at minus twenty degrees Celsius or below, away from light and moisture. Vials are allowed to reach room temperature before opening to limit condensation. Repeated warming and cooling of the same vial is discouraged.