A practical reference on electrospray ionisation: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2025-12-08. Anything still debated is marked as such rather than presented as settled.
Literature searches for this compound must account for several spelling variants. Indexing databases contain epitalon, epithalon, epithalone, and AEDG, and relevant records are scattered across Russian-language and English-language journals that do not consistently cross-cite. Early publications describe the parent extract as a mixture of many peptides, whereas later work addresses the single synthetic tetrapeptide. That shift in nomenclature complicates comparison between studies, because extract data and tetrapeptide data are sometimes cited interchangeably. A search strategy omitting the alternate spellings will return an incomplete set of references.
Reported biological findings come mainly from cell culture and rodent experiments. Those studies describe changes in telomerase catalytic subunit expression, melatonin rhythm amplitude, and antioxidant enzyme activity after peptide exposure. Human data are sparse and consist of small trials with limited blinding and inconsistent endpoints. The proposed mechanisms remain hypotheses rather than established facts, and there is no consensus on whether effects observed in animals carry over to people. Independent replication outside the original research groups is limited, which is a recognised gap in the published literature.
The molecule is a short, linear, hydrophilic peptide that dissolves readily in water or aqueous buffer. Its principal chemical liabilities are hydrolytic rather than oxidative, since it contains no cysteine, methionine, or tryptophan residues. The aspartate–glycine step is a recognised site for aspartimide formation under mildly acidic or basic conditions, generating isoaspartate and succinimide-related products over time. Desiccated lyophilised powder held at −20 °C is comparatively stable, whereas dilute solutions degrade faster and are best frozen as single-use aliquots rather than thawed repeatedly.
No pharmacopoeial monograph exists for this peptide, so quality rests on the supplier's internal specifications and on whatever independent testing a purchaser arranges. Certificates of analysis differ widely in which tests they report and in the limits applied. The counter-ion introduced during purification, commonly acetate or trifluoroacetate, changes the net peptide content of a given mass of powder, so two samples of equal weight may not contain equal amounts of the active sequence. Third-party laboratories can verify purity, identity, residual solvents, and counter-ion content for a fee, which makes documentation more informative than labelling.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic tetrapeptide | Four amino acid residues |
| Residue sequence | Ala-Glu-Asp-Gly | Abbreviated AEDG |
| Approximate mass | 390.35 Da | Monoisotopic, free base form |
| Parent preparation | Epithalamin extract | Derived from pineal tissue |
| Common spelling variants | Epithalon, epithalone, AEDG | Affects literature retrieval |
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.
Epitalon is a synthetic tetrapeptide whose sequence is alanine–glutamate–aspartate–glycine, commonly abbreviated AEDG. It was developed in Russia during the 1980s and 1990s by investigators associated with the St. Petersburg Institute of Bioregulation and Gerontology, who studied short peptides as regulators of gene expression and tissue function. The alternative spelling epithalon appears interchangeably in the literature, and the two names refer to the same molecule. Outside Russia it is encountered chiefly as a research chemical rather than a licensed medicine, and it holds no approval from the United States Food and Drug Administration or the European Medicines Agency.
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.
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.
According to AASLD guidelines, a liver biopsy may be considered in people with MASLD who are at increased risk of having steatohepatitis with or without advanced fibrosis, but only when all other competing chronic liver diseases are excluded (such as alcoholic liver disease). The presence of metabolic syndrome, MASLD Fibrosis Score (FIB-4), or liver stiffness (as measured by Vibration-controlled transient elastography or MRE) can identify individuals who are at higher risk of steatohepatitis or advanced fibrosis.
=== Biosynthesis === Alanine can be synthesized from pyruvate and branched-chain amino acids such as valine, leucine, and isoleucine. Alanine is produced by reductive amination of pyruvate, a two-step process. In the first step, α-ketoglutarate, ammonia and NADH are converted by glutamate dehydrogenase to glutamate, NAD+ and water. In the second step, the amino group of the newly formed glutamate is transferred to pyruvate by an aminotransferase enzyme, regenerating the α-ketoglutarate, and converting the pyruvate to alanine. The net result is that pyruvate and ammonia are converted to alanine, consuming one reducing equivalent. Because transamination reactions are readily reversible and pyruvate is present in all cells, alanine can be easily formed and thus has close links to metabolic pathways such as glycolysis, gluconeogenesis, and the citric acid cycle.
== Health economics == Economic analyses suggest that TOPS may be cost-effective compared with fusion. These findings are based on improvements in quality of life, faster recovery, and reduced need for reoperation over time.
== Early life and education == Fred McLafferty was born in Evanston, Illinois in 1923, but attended grade school in Omaha, Nebraska, graduating from Omaha North High School in 1940. The urgent requirements of World War II accelerated his undergraduate studies at the University of Nebraska; he obtained his B.S. degree in 1943 and thereafter entered the US armed forces. He served in western Europe during the invasion of Germany and was awarded the Combat Infantryman Badge, a Purple Heart, five Bronze Star Medals and a Presidential Unit Citation. He returned to the University of Nebraska in late 1945 and completed his M.S. degree in 1947. He went on to work under William Miller at Cornell University where he earned his Ph.D. in 1950. He went on to a postdoctoral researcher position at the University of Iowa with R.L. Shriner.
Sources: en.wikipedia.org
== Properties == Native silk fibre is both strong and tough, and silkworm silk spun under controlled conditions approaches spider dragline silk in strength. Regenerated silk rarely matches it, because reprocessing disrupts the ordered molecular alignment produced during natural spinning, and the reconstituted material is correspondingly weaker. The extent of this loss depends on the format and the beta-sheet content, and matching the properties of native silk in regenerated form has not yet been fully resolved. Purified fibroin is well tolerated by living tissue and supports the attachment and growth of many cell types. The mild reaction associated with modern silk biomaterials results largely from purification: when sericin and other residues are removed the response is slight, whereas their presence provokes a stronger reaction. This is a large part of why degumming is emphasised in device manufacture. Many synthetic implants remain essentially inert in the body; silk does not. Protease enzymes such as chymotrypsin cleave it into peptides and amino acids that the body can absorb. The rate of degradation is not fixed; it can be set from a few weeks to more than a year by adjusting the beta-sheet content, the format and the porosity. This allows a scaffold to be designed so that it degrades at approximately the rate at which new tissue forms. Surgical silk is sometimes described as non-degradable, a term that reflects the slow loss of strength of a thick braided suture rather than any permanence of the protein itself.
Figures 1 and 2 show two-dimensional projections of a phase diagram. In the pressure-temperature phase diagram (Fig. 1) the boiling curve separates the gas and liquid region and ends in the critical point, where the liquid and gas phases disappear to become a single supercritical phase. The appearance of a single phase can also be observed in the density-pressure phase diagram for carbon dioxide (Fig. 2). At well below the critical temperature, e.g., 280 K, as the pressure increases, the gas compresses and eventually (at just over 40 bar) condenses into a much denser liquid, resulting in the discontinuity in the line (vertical dotted line). The system consists of 2 phases in equilibrium, a dense liquid and a low density gas. As the critical temperature is approached (300 K), the density of the gas at equilibrium becomes higher, and that of the liquid lower. At the critical point (304.1 K (31.0 °C; 87.7 °F) and 7.38 MPa (73.8 bar)), there is no difference in density, and the two phases become one fluid phase. Thus, above the critical temperature a gas cannot be liquefied by pressure. At slightly above the critical temperature (310 K), in the vicinity of the critical pressure, the line is almost vertical. A small increase in pressure causes a large increase in the density of the supercritical phase. Many other physical properties also show large gradients with pressure near the critical point, e.g. viscosity, the relative permittivity and the solvent strength, which are all closely related to the density.
=== Anti-cancer treatment === SAM has recently been shown to play a role in epigenetic regulation. DNA methylation is a key regulator in epigenetic modification during mammalian cell development and differentiation. In mouse models, excess levels of SAM have been implicated in erroneous methylation patterns associated with diabetic neuropathy. SAM serves as the methyl donor in cytosine methylation, which is a key epigenetic regulatory process. Because of this impact on epigenetic regulation, SAM has been tested as an anti-cancer treatment. In many cancers, proliferation is dependent on having low levels of DNA methylation. In vitro addition in such cancers has been shown to remethylate oncogene promoter sequences and decrease the production of proto-oncogenes. In cancers such as colorectal cancer, aberrant global hypermethylation can inhibit promoter regions of tumor-suppressing genes. Contrary to the former information, colorectal cancers (CRCs) are characterized by global hypomethylation and promoter-specific DNA methylation.
== Awards == Borden Award (American Chemical Society) 1957 Bond Award (American Oil Chemists’ Society) 1973 Agricultural and Food Chemistry Award (American Chemical Society) 1973 Senior Scientist Award (Alexander von Humboldt Foundation) 1981 Macy-Gyorgy Award for Research in Human Milk and Lactation 1997 Penn State Alumni Fellow Award 2001 Penn State Distinguished Alumnus Award 2002
== External links == "Anatomy photo:21:st-1500". SUNY Downstate Medical Center. Archived from the original on March 5, 2016. – "Mediastinum: Pericardium (pericardial sac)" thoraxlesson4 at The Anatomy Lesson by Wesley Norman (Georgetown University) (heartpericardium) Atlas image: ht_pericard2 at the University of Michigan Health System – "MRI of chest, lateral view"
Sources: en.wikipedia.org
We thus come to the remarkable conclusion that, beyond doubt, Van Leeuwenhoek in his experiment with the fully closed tube had cultivated and seen genuine anaerobic bacteria, which would happen again only after 200 years, namely about 1862 by Pasteur. That Leeuwenhoek, one hundred years before the discovery of oxygen and the composition of air, was not aware of the meaning of his observations is understandable. But the fact that in the closed tube he observed an increased gas pressure caused by fermentative bacteria and, in addition, saw the bacteria, prove, in any case, that he not only was a good observer but also was able to design an experiment from which a conclusion could be drawn.
Paolo Bertoli (1969–1973) Luigi Raimondi (1973–1975) Corrado Bafile (1976–1980) Pietro Palazzini (1980–1988) Angelo Felici (1988–1995) Alberto Bovone (pro-prefect 1995–1998, prefect 1998) José Saraiva Martins (1998–2008) Angelo Amato (pro-prefect 2008–2010, prefect 2010–2018) Giovanni Angelo Becciu (2018 – 24 September 2020) Marcello Semeraro (2020-present)
== Prebiotic synthesis of ribonucleosides == In order to understand how life arose, knowledge is required of the chemical pathways that permit formation of the key building blocks of life under plausible prebiotic conditions. According to the RNA world hypothesis free-floating ribonucleosides and ribonucleotides were present in the primitive soup. Molecules as complex as RNA must have arisen from small molecules whose reactivity was governed by physico-chemical processes. RNA is composed of purine and pyrimidine nucleotides, both of which are necessary for reliable information transfer, and thus Darwinian natural selection and evolution. Nam et al. demonstrated the direct condensation of nucleobases with ribose to give ribonucleosides in aqueous microdroplets, a key step leading to RNA formation. Also, a plausible prebiotic process for synthesizing pyrimidine and purine ribonucleosides and ribonucleotides using wet-dry cycles was presented by Becker et al.
While de jure not part of West Germany, for Berlin was under the control of the Allied Control Council, West Berlin politically aligned itself with West Germany and was directly or indirectly represented in its federal institutions. The foundation for the influential position held by Germany today was laid during the economic miracle of the 1950s (Wirtschaftswunder), when West Germany rose from the enormous destruction wrought by World War II to become the world's second-largest economy. The first Chancellor Konrad Adenauer, who remained in office until 1963, worked for a full alignment with the NATO rather than neutrality, and secured membership in the military alliance. Adenauer was also a proponent of agreements that developed into the present-day European Union. When the G6 was established in 1975, there was no serious debate as to whether West Germany would become a member. Following the collapse of the Eastern Bloc, symbolised by the opening of the Berlin Wall, both states took action to achieve German reunification. East Germany voted to dissolve and accede to the Federal Republic of Germany in 1990. The five post-war states (Länder) were reconstituted, along with the reunited Berlin, which ended its special status and formed a sixth Land. They formally joined the federal republic on 3 October 1990, raising the total number of states from ten to 16, and ending the division of Germany.
=== Middle Eastern culture === The scorpion is a culturally significant animal, appearing as a motif in art, especially in Islamic art in the Middle East. A scorpion motif is often woven into Turkish kilim flat-weave carpets, for protection from their sting. The scorpion is perceived both as an embodiment of evil and a protective force such as a dervish's powers to combat evil. In another context, the scorpion portrays human sexuality. Scorpions are used in folk medicine in South Asia, especially in antidotes for scorpion stings. One of the earliest occurrences of the scorpion in culture is its inclusion, as Scorpio, in the 12 signs of the Zodiac by Babylonian astronomers during the Chaldean period. In ancient Egypt, the goddess Serket was often depicted as a scorpion, one of several goddesses who protected the Pharaoh. Alongside serpents, scorpions are used to symbolize evil in the New Testament. In Luke 10:19 it is written, "Behold, I give unto you power to tread on serpents and scorpions, and over all the power of the enemy: and nothing shall by any means hurt you." Here, scorpions and serpents symbolize evil. Revelation 9:3 speaks of "the power of the scorpions of the earth."
Sources: en.wikipedia.org
It is based on epithalamin, a peptide-rich preparation obtained from pineal gland tissue and studied in the former Soviet Union. Researchers later identified the tetrapeptide AEDG as a constituent fragment of that material. Modern supplies are produced by chemical synthesis rather than tissue extraction.
No. Epithalamin is a heterogeneous extract containing many peptides, while epitalon is a single synthesised tetrapeptide. Publications sometimes treat findings from the two as equivalent, which is a common source of confusion. Their compositions differ and they are not interchangeable in analytical terms.
Most published work uses cell cultures or rodents because those models are faster and less costly to run. The few human trials that have been reported are small, and several lack control groups or blinding. This restricts what can reasonably be concluded about effects in people.
Mass spectrometry provides the identity check, because the observed mass is compared with the theoretical mass of the AEDG sequence. Chromatography separates and quantifies impurities but does not by itself prove which peptide is present. The two techniques are normally used together.