If you have been reading about Mass spectrometry 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 2025-08-12. Numbers and descriptions here follow the published literature rather than marketing material.
The published literature is dominated by a small number of research groups, much of it in Russian-language journals, and independent replication outside those groups is limited. Studies are typically small, use cultured cells or rodent models, and report endpoints that differ between papers, which makes comparison difficult. Large randomised human trials have not appeared in the indexed literature. Questions about absorption, distribution and clearance are therefore still treated as open in reviews that mention the compound.
Epitalon is a synthetic tetrapeptide with the sequence alanine–glutamate–aspartate–glycine, commonly abbreviated AEDG. Its design traces to epithalamin, a peptide fraction prepared from bovine pineal gland extracts that researchers in Saint Petersburg began investigating in the 1970s. The compound has a molecular formula of C14H22N4O9 and a nominal molecular mass near 390 daltons. It holds no approved drug status in the United States or the European Union, and material sold under this name is generally offered as a research chemical rather than a finished pharmaceutical product.
Proposed mechanisms centre on cell-culture observations rather than a defined receptor interaction. Several reports describe increased expression of the telomerase catalytic subunit after exposure of cultured human cells, and the authors attributed the effect to short peptide fragments entering the nucleus and influencing gene transcription. No receptor for the tetrapeptide has been identified, and the free peptide is expected to be degraded rapidly by plasma peptidases. Whether any measurable fraction reaches intact tissues after administration remains an unresolved question rather than an established finding.
Stability of the tetrapeptide follows ordinary peptide chemistry rather than any unusual structural feature. The aspartate-glycine pair is prone to aspartimide formation under mildly basic or neutral conditions, and deamidation can follow, altering both mass and chromatographic retention. Dry lyophilised powder kept at or below minus twenty degrees Celsius is the usual handling recommendation, with repeated freeze-thaw cycles avoided. Once dissolved in neutral aqueous buffer, degradation proceeds over days to weeks depending on pH and temperature, while acidic conditions generally slow the aspartimide route. A formal stability-indicating study has not been published in the indexed literature.
Because epitalon has no pharmacopoeial monograph, quality assessment depends on supplier documentation and independent testing. Certificates of analysis typically report a purity figure from a single chromatographic run, a measured mass and sometimes an appearance description, but methods and acceptance criteria are not harmonised across vendors. Third-party laboratories can repeat identity and purity measurements, and mismatches between labelled and measured peptide content have been described for research peptides generally. What constitutes adequate identity confirmation for a molecule of this size stays an open question, since mass agreement alone does not separate closely related sequences.
Identity testing for epitalon relies on reversed-phase high-performance liquid chromatography for purity and mass spectrometry for mass confirmation. Because the sequence contains no tryptophan or tyrosine, ultraviolet detection at 280 nanometres is insensitive, so chromatographic methods usually monitor absorbance near 214 nanometres, where the peptide backbone absorbs. Electrospray ionisation or matrix-assisted laser desorption/ionisation then checks the intact mass against the expected value near 390 daltons. Peptide mapping or amino acid analysis after acid hydrolysis can supplement these measurements, although such confirmatory work is seldom reported on commercial certificates of analysis.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C14H22N4O9 | Synthetic tetrapeptide, four residues |
| Nominal mass | Approximately 390 Da | Free peptide; salt forms differ |
| Appearance | White to off-white powder | Commonly supplied lyophilised |
| Solubility class | Freely soluble in water | Also dissolves in aqueous buffer |
| Typical storage | −20 °C, desiccated | Cold packs used during transport |
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.
Storage and handling follow conventional peptide practice. Lyophilized epitalon is typically kept refrigerated or frozen, protected from moisture and light, and allowed to equilibrate to room temperature before opening to avoid condensation. Once dissolved, aqueous solutions are usually stored cold and used within a short period, since dilute peptide solutions can support microbial growth and may slowly degrade. The absence of cysteine and methionine reduces, but does not eliminate, oxidation concerns during long-term storage.
Regulatory status varies by country and is not harmonized. Epitalon is not an approved drug in major Western jurisdictions. In some countries it is sold as a research chemical, and in others it has appeared in products marketed for other categories. This inconsistent status means that purity, labeling accuracy, and documentation differ widely between suppliers, and verification of identity and purity through independent analysis is the usual way buyers assess a given lot.
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.
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.
The most frequently cited laboratory finding is that AEDG increased telomerase activity and extended telomere length in cultured human somatic cells. That work used fetal fibroblast strains and reported changes in enzyme activity alongside altered division counts. Replication by unrelated groups has been limited, and the published record is largely a single-laboratory series rather than a multi-centre programme. The result supports a hypothesis about peptide influence on gene expression in cell culture; it does not by itself establish an effect on telomere length in living animals or in people.
Animal and clinical reports appear mainly in Russian-language journals from the 1990s and 2000s, covering endpoints such as melatonin rhythm, lifespan in aged rodents, and retinal function. Many of these papers involve small groups, lack blinding or placebo comparison, and are difficult to retrieve through indexed databases. Review articles published in English generally summarise the claims without reanalysing the underlying data. Because no large randomised trial exists, the clinical importance of these reported effects stays unresolved and is properly described as an open question.
==== Diarrhea ==== In cases of diarrhea-predominate irritable bowel syndrome, opioids may be used to suppress diarrhea. Loperamide is a peripherally selective opioid available without a prescription used to suppress diarrhea. The ability to suppress diarrhea also produces constipation when opioids are used beyond several weeks.
==== United States ==== Ergine is not an explicitly controlled substance in the United States. However, it could be considered a controlled substance under the Federal Analogue Act if intended for human consumption.
=== Obstructive sleep apnea === Abdominal obesity is an important risk factor for obstructive sleep apnea, as increased abdominal fat can place pressure on the airway and narrow it. This can lead to reduced lung volumes during sleep. Higher waist circumference and waist-to-hip ratio are associated with obstructive sleep apnea, even in individuals whose body mass index is only in the overweight range.
=== Mammals === Several groups of ungulates have independently reduced or lost side digits on their feet, often leaving one or two digits for walking. That name comes from their hooves, which have evolved from claws several times. For example, horses have one walking digit and domestic bovines two on each foot. Various other land vertebrates have also reduced or lost digits. Similarly, laurasiathere perissodactyls and afrothere paenungulates have several features in common, to the point of there being no obvious distinction among basal taxa of both groups. Many aquatic mammals or marine mammals independently came to have adaptations to live in water, such as similar-looking tail flukes in dugongs and whales. Unrelated herbivores and carnivores have adapted to marine and freshwater environments. The flipper forelimbs of marine mammals (cetaceans, pinnipeds, and sirenians) are a classic example of convergent evolution. There is widespread convergence at the gene level. Distinct substitutions in common genes created various aquatic adaptations, most of which also constitute parallel evolution because the substitutions in question are not unique to those animals. The pronghorn of North America, while not a true antelope and only distantly related to them, closely resembles the true antelopes of the Old World, both behaviorally and morphologically. It also fills a similar ecological niche and is found in the same biomes. Members of the two clades Australosphenida and Theria evolved tribosphenic molars independently.
Sources: en.wikipedia.org
Several complications can occur as a result of sCSFLS including decreased cranial pressure, brain herniation, infection, blood pressure problems, transient paralysis, and coma. The primary and most serious complication of a spontaneous cerebrospinal fluid leak is spontaneous intracranial hypotension, where pressure in the brain is severely decreased. This complication leads to the hallmark symptom of severe orthostatic headaches. People with cranial CSF leaks, the rarer form, have a 10% risk of developing meningitis per year. If cranial leaks last more than seven days, the chances of developing meningitis are significantly higher. Spinal CSF leaks cannot result in meningitis due to the sterile conditions of the leak site. When a CSF leak occurs at the temporal bone, surgery becomes necessary in order to prevent infection and repair the leak. Orthostatic hypotension is another complication that occurs due to autonomic dysfunction when blood pressure drops significantly. The autonomic dysfunction is caused by compression of the brainstem, which controls breathing and circulation. Low CSF volume can cause the cerebellar tonsil position to descend, which can be mistaken for Chiari malformation; however when the CSF leak is repaired the tonsil position often returns to normal (as seen in upright MRI) in this "pseudo-Chiari" condition. A further, albeit rare, complication of CSF leak is transient quadriplegia due to a sudden and significant loss of CSF. This loss results in hindbrain herniation and causes major compression of the upper cervical spinal cord.
== Presentation == Patients usually begin to notice symptoms in their 30s and the course is usually slowly progressive. Common features include peripheral neuropathy, cardiomyopathy, and hemolytic anemia. Other features include limb chorea, facial tics, other oral movements (lip and tongue biting), seizures, a late-onset dementia, and behavioral changes.
An electronic cigarette (commonly known as a vape) is a handheld battery-powered vaporizer that simulates smoking by providing some of the behavioral aspects of smoking, including the hand-to-mouth action of smoking, but without combusting tobacco. Using an e-cigarette is known as "vaping" and the user is referred to as a "vaper". Instead of cigarette smoke, the user inhales an aerosol, commonly called vapor. E-cigarettes typically have a heating element that atomizes a liquid solution called e-liquid. E-cigarettes are automatically activated by taking a puff; others turn on manually by pressing a button. Some e-cigarettes look like traditional cigarettes, but they come in many variations. Most versions are reusable, though some are disposable. There are first-generation, second-generation, third-generation, and fourth-generation devices. E-liquids usually contain propylene glycol, glycerin, nicotine, flavorings, additives, and differing amounts of contaminants. E-liquids are also sold without propylene glycol, nicotine, or flavors. The benefits and the health risks of e-cigarettes are uncertain. There is moderate-certainty evidence that e-cigarettes with nicotine may help people quit smoking when compared with e-cigarettes without nicotine and nicotine replacement therapy. However, other studies have not supported the finding that e-cigarettes are more effective than smoking cessation medicine. There is concern with the possibility that non-smokers and children may start nicotine use with e-cigarettes at a rate higher than anticipated than if they were never created.
== Epidemiology == Prior to 1992, CRE were relatively uncommon in the U.S. According to data from the National Nosocomial Infection Service, between 1986 and 1990, only 2.3% of 1825 Enterobacteriaceae isolates sampled were found to be resistant. According to the U.S. Centers for Disease Control, CRE producing what was the most common type of carbapenem-destroying enzyme in 2001 were first detected in a North Carolina hospital in 1996. Since then, they have been identified in health care facilities in 41 other states. In 2012, 3% of patients in Chicago-area ICUs carried CRE. The same data indicated a 30% colonization rate in long-term care facilities (e.g. nursing homes), where patients are not symptomatic. During just the first half of 2012, almost 200 hospitals and long-term acute care facilities treated at least one patient infected with these bacteria. CRE have become increasingly common in the US. The Meropenem Yearly Susceptibility Test Information Collection Program noted that resistance within K. pneumoniae alone increased from 0.6% in 2004 to 5.6% in 2008. The first outbreak involving colistin-resistant, carbapenem-resistant K. pneumoniae (CRKP) in the U.S. was discovered in Detroit, Michigan in 2009, involving three different healthcare institutions. In an active surveillance study in seven U.S. states over two years, the crude overall incidence of CRE was 2.93 per 100,000 population. Georgia and Maryland had a significantly higher than predicted incidence adjusted for age and race. Increases in CRE have not been limited to the US.
The resulting campaign was costly for both sides, but ultimately ended in disaster for France and the near-destruction of Napoleon's Grande Armée. French forces retreated from Russia by December 1812 and began reconstituting their lost strength. Encouraged by the defeat, Austria, Prussia, and several minor powers joined Russia, Britain, and Spain in a Sixth Coalition and began a campaign against France. The Sixth Coalition defeated Napoleon at Leipzig in October 1813. The allies then invaded France on two fronts: the Russians, Austrians, and Prussians invaded France from the east, while the British, Spanish, and Portuguese invaded France from the west. Coalition troops captured Paris in March 1814, forced Napoleon to abdicate in April, exiled him to the island of Elba, and restored power to the Bourbons. Napoleon escaped exile in February 1815 and reassumed control of France for around one hundred days, igniting the eponymous conflict. The allies formed the Seventh Coalition, which defeated him at Waterloo in June 1815 and exiled him to Saint Helena, where he died in 1821. The wars had profound consequences on history. New methods of warfare were introduced, including mass conscription and guerrilla warfare. Politically, the wars greatly influenced Europe through the advancements in civil law brought about by the Napoleonic Code, which was largely retained where it was adopted, and the spread of nationalism and liberalism. Independence movements emerged in Spanish America as a direct consequence of the wars, leading to the decline of the Spanish and Portuguese Empires.
Sources: en.wikipedia.org
No. Epithalamin is a heterogeneous peptide fraction obtained from pineal gland extract and contains many components. Epitalon is a single synthetic tetrapeptide with the sequence Ala-Glu-Asp-Gly. Researchers synthesised the shorter peptide while attempting to identify active sequences within the extract.
No endogenous peptide with this exact sequence has been described as a circulating hormone or signalling molecule. The tetrapeptide was designed as a synthetic analogue based on fragments observed in pineal preparations. Any activity discussed in the literature therefore refers to administered material rather than to a natural pool of the compound.
It is not an approved medicine in major jurisdictions and does not appear in the major pharmacopoeias. Material is usually distributed as a research chemical or laboratory reagent. Such labelling places handling responsibility on the purchaser and does not indicate that a regulatory body has reviewed the substance.
The molecule lacks aromatic residues, so it absorbs weakly near 280 nanometres, the wavelength applied to many other peptides. The peptide bond absorbs strongly below 220 nanometres, making 214 nanometres a practical compromise. Gradient methods must therefore use mobile phases with low ultraviolet absorbance to keep the baseline clean.