The short version of Tetrapeptide fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2026-04-19 and is reviewed periodically as new material appears.
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.
In its supplied form epitalon is a white to off-white powder, usually lyophilized and often hygroscopic. It dissolves readily in water and in aqueous buffers, and it is commonly handled as the acetate or trifluoroacetate salt to improve stability during purification and drying. The amide backbone is labile in aqueous media, so solutions are less durable than the dry solid. Handling notes in the chemical literature therefore emphasize keeping the powder dry, cool and shielded from light until it is dissolved.
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.
| Property | Value | Notes |
|---|---|---|
| Analytical method | Reversed-phase HPLC | Purity determination, typically 214 nm |
| Mass confirmation | ESI or MALDI mass spectrometry | Compared with mass near 390 Da |
| Common synonyms | Epitalon, epithalon, AEDG | Naming differs between suppliers |
| Storage temperature | −20 °C or lower | Lyophilised powder, kept desiccated |
| Solution stability | Limited in neutral aqueous buffer | Aspartimide and hydrolysis pathways |
Identity is normally established by reversed-phase high-performance liquid chromatography combined with mass spectrometry, a pairing that separates components and confirms molecular mass at once. Purity is quoted as a percentage from the chromatogram, and figures above ninety-five percent are a frequent commercial specification. Amino acid analysis or sequencing supplies further confirmation when required. Because many short peptides behave similarly under chromatography, retention time alone does not establish sequence; the mass measurement is what separates one tetrapeptide from another, and certificates should report both.
Short peptides such as AEDG are normally supplied as a freeze-dried solid and are kept dry, cold, and shielded from light. Holding at minus twenty degrees Celsius is common for the long term, while a refrigerator suffices for brief periods before use. The material takes up moisture to some degree, so containers should stay sealed and be allowed to reach room temperature before opening, which limits condensation on the contents. Repeated warming and cooling of a single container is discouraged because it admits water and can lower the amount of intact peptide.
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.
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.
Identity confirmation uses mass spectrometry, usually electrospray ionisation in positive mode or matrix-assisted laser desorption. The protonated free peptide produces a signal near three hundred and ninety-one daltons, while salt adducts shift that value slightly. Tandem mass spectrometry or amino acid analysis supplies sequence-level confirmation, which a single mass measurement cannot. Peptides containing aspartate can cyclise into succinimide intermediates that hydrolyse to isoaspartate isomers of identical mass. Because those isomers are difficult to separate chromatographically, identity and purity results carry more weight when interpreted together.
== Verification status removals == On March 23, 2023, Twitter announced that on April 1, 2023, it would begin winding down its legacy verification program and removing legacy verified checkmarks. The New York Times reported that exceptions would be made for Twitter's top 500 advertisers and its 10,000 most-followed organizations that had been previously verified. BuzzFeed News reported that multiple news organizations like The New York Times, The Washington Post and The Los Angeles Times had no plans to pay for Twitter's "Verified Organizations" service nor would they reimburse reporters for having Twitter Blue. Similarly, Axios reported that White House digital strategy director Rob Flaherty sent an internal email to staffers saying "[t]here are ongoing trials for the program that we are monitoring, but we will not enroll in it." Twitter did not immediately begin removing checkmarks on April 1, 2023. The Washington Post reported that "[the removal] of verification badges is a largely manual process powered by a system prone to breaking" and "[i]n the past, there was no way to reliably remove badges at a bulk scale", according to former Twitter employees. Twitter also updated the language previously used to distinguish between legacy and Twitter Blue-verified users, merging them into a single description, and later unfollowed all legacy-verified accounts. On April 11, 2023, Musk announced the final date for removing legacy blue checkmarks to be April 20.
The epiphyseal arteries and osteogenic cells invade the epiphysis, depositing osteoclasts and osteoblasts which erode the cartilage and build bone, respectively. This occurs at both ends of long bones but only one end of digits and ribs.
BSA can be calculated on the basis of weight and height. Twenty-four-hour urine collection to assess creatinine clearance is no longer widely performed, due to difficulty in assuring complete specimen collection. To assess the adequacy of a complete collection, one always calculates the amount of creatinine excreted over a 24-hour period. This amount varies with muscle mass and is higher in young people/old, and in men/women. An unexpectedly low or high 24-hour creatinine excretion rate voids the test. Nevertheless, in cases where estimates of creatinine clearance from serum creatinine are unreliable, creatinine clearance remains a useful test. These cases include "estimation of GFR in individuals with variation in dietary intake (vegetarian diet, creatine supplements) or muscle mass (amputation, malnutrition, muscle wasting), since these factors are not specifically taken into account in prediction equations." A number of formulae have been devised to estimate GFR or Ccr values on the basis of serum creatinine levels. Where not otherwise stated serum creatinine is assumed to be stated in mg/dL, not μmol/L—divide by 88.4 to convert from μmol/Lto mg/dL.
BASF bought the Engelhard Corporation for $4.8 billion in 2006. Other acquisitions in 2006, were the purchase of Johnson Polymer and the construction chemicals business of Degussa. The acquisition of Johnson Polymer was completed on 1 July 2006. The purchase price was $470 million on a cash and debt-free basis. It provided BASF with a range of water-based resins that complements its portfolio of high solids and UV resins for the coatings and paints industry and strengthened the company's market presence, particularly in North America. The acquisition of Degussa AG's construction chemicals business was completed in 2006. The purchase price for equity was about €2.2 billion. In addition, the transaction was associated with a debt of €500 million. The company agreed to acquire Ciba (formerly part of Ciba-Geigy) in September 2008. The proposed deal was reviewed by the European Commissioner for Competition. On 9 April 2009, the acquisition was officially completed. On 19 December 2008, BASF acquired U.S.-based Whitmire Micro-Gen together with U.K.-based Sorex Ltd. Sorex is a manufacturer of branded chemical and non-chemical products for professional pest management. In March 2007 Sorex was put up for sale with a price tag of about £100 million. In December 2010, BASF completed the acquisition of Cognis. In May 2015, BASF agreed to sell parts of its pharmaceutical ingredients business to Swiss drug manufacturer Siegfried Holding AG for a fee of €270 million, including assumed debt. In 2016, BASF announced the sale of its polyolefin catalysts group to W.R. Grace.
=== Mortality === CRE resistance depends upon a number of factors such as the health of the patient, whether the patient has recently undergone a transplant, risk of co-infection, and use of multiple antibiotics. Carbapenem minimal inhibitory concentrations (MICs) results may be more predictive of clinical patient outcomes than the current categorical classification of the MICs being listed as susceptible, intermediate, or resistant. The study aimed to define an all-cause hospital mortality breakpoint for carbapenem MICs that were adjusted for risk factors. Another objective was to determine if a similar breakpoint existed for indirect outcomes, such as the time to death and length of stay after infection for survivors. Seventy-one patients were included, of which 52 patients survived and 19 patients died. Classification and regression tree analysis determined a split of organism MIC between 2 and 4 mg/liter and predicted differences in mortality (16.1% for 2 mg/liter versus 76.9% for 4 mg/liter). In logistic regression controlling for confounders, each imipenem MIC doubling dilution doubled the probability of death. This classification scheme correctly predicted 82.6% of cases. Patients were accordingly stratified to MICs of ≤2 mg/liter (58 patients) and ≥4 mg/liter (13 patients). Patients in the group with a MIC of ≥4 mg/liter tended to be more ill. Secondary outcomes were also similar between groups. Patients with organisms that had an MIC of ≥4 mg/liter had worse outcomes than those with isolates of an MIC of ≤2 mg/liter.
Sources: en.wikipedia.org
WUNC-TV (4, PBS): licensed to Chapel Hill, owned by the University of North Carolina WRAL-TV (5, NBC): licensed to Raleigh, owned by Capitol Broadcasting Company WAUG-LD (8, Independent station) licensed to Raleigh, owned and operated by Saint Augustine's College WTVD (11, ABC): licensed to Durham; news bureau located in Raleigh. ABC O&O owned by ABC Owned Television Stations WNCN-TV (17, CBS): studios located in Raleigh, licensed to the city of Goldsboro southeast of Raleigh; owned by Nexstar Media Group WLFL-TV (22, CW): licensed to Raleigh, owned by Sinclair Broadcast Group WRDC (28, MyNet) licensed to Durham, owned by Sinclair Broadcast Group WRAY-TV (30, TCT) licensed to Wilson. TCT O&O owned by Tri-State Christian Television WUVC-DT (40, Univision) licensed to Fayetteville. Univision O&O owned by TelevisaUnivision WRPX-TV (47, Ion) licensed to Rocky Mount, with studios in Raleigh. Ion O&O owned by Ion Media WRAZ-TV (50, Fox): licensed to Raleigh, owned by Capitol Broadcasting Company WRTD-CD (54, Telemundo): licensed to Raleigh. Telemundo O&O owned by NBCUniversal
==== Neurological ==== Peripheral neuropathy and mononeuritis multiplex may occur. The most common problem is carpal tunnel syndrome caused by compression of the median nerve by swelling around the wrist. Rheumatoid disease of the spine can lead to myelopathy. Atlanto-axial subluxation can occur, owing to erosion of the odontoid process or transverse ligaments in the cervical spine connection to the skull. Such an erosion (>3mm) can give rise to vertebrae slipping over one another and compressing the spinal cord. Clumsiness is initially experienced, but without due care, this can progress to quadriplegia or even death. Vertigo may be associated with rheumatoid arthritis via the following associations that can cause vertigo:
To the east of the garden and near the gallery of the Center Bourse is a large square basin made at the beginning of the 2nd century, about 15 m (49 ft) on each side, in well-paired stones, comprising on the whole five courses. The paved bottom was grouted with pitch to ensure watertightness. This basin of nearly 500 mᶟ was supplied with water by a pipe collecting water from a source and emerging in the north-eastern internal side of the basin. This pipeline, which was protected by Cassis stone slabs, was recognized over more than 100 m (330 ft) to the north. This basin was used to supply water to the boats. On the western internal facing, anchor points and a reserved cavity in the paved ground, attest to the existence of a wheel which must have been 3 m (9.8 ft) in diameter, used to clear the alluvium carried by the water. It is likely that another wheel was used to lift the water.
Canthaxanthin Chédiak–Higashi syndrome Chrysiasis Cross–McKusick–Breen syndrome (Cross syndrome, oculocerebral-hypopigmentation syndrome) Dermatopathia pigmentosa reticularis (dermatopathia pigmentosa reticularis hyperkeratotica et mutilans, dermatopathia pigmentosa reticularis hypohidotica et atrophica, dermatopathic pigmentosa reticularis) Dyschromatosis symmetrica hereditaria (reticulate acropigmentation of Dohi, symmetrical dyschromatosis of the extremities) Dyschromatosis universalis hereditaria Elejalde syndrome (Griscelli syndrome type 1) Eruptive hypomelanosis Familial progressive hyperpigmentation Galli–Galli disease Griscelli syndrome type 2 (partial albinism with immunodeficiency) Griscelli syndrome type 3 Hemochromatosis (bronze diabetes) Hemosiderin hyperpigmentation Hermansky–Pudlak syndrome Idiopathic guttate hypomelanosis (leukopathia symmetrica progressiva) Iron metallic discoloration Klein–Waardenburg syndrome Lead poisoning Leukoderma Melanoma-associated leukoderma Melasma (chloasma faciei, mask of pregnancy) Mukamel syndrome Necklace of Venus Nevus anemicus Nevus depigmentosus (nevus achromicus) Ocular albinism Oculocutaneous albinism Pallister–Killian syndrome Periorbital hyperpigmentation Photoleukomelanodermatitis of Kobori Phylloid hypomelanosis Piebaldism Pigmentatio reticularis faciei et colli Pityriasis alba Poikiloderma of Civatte Poikiloderma vasculare atrophicans Postinflammatory hyperpigmentation (postinflammatory hypermelanosis) Postinflammatory hypopigmentation Progressive macular hypomelanosis Quadrichrome vitiligo Reticular pigmented anomaly of the flexures (dark dot disease, Dowling–Degos' disease) Reticulate acropigmentation of Kitamura Revesz syndrome Riehl melanosis Scratch dermatitis (flagellate pigmentation from bleomycin) Segmental vitiligo Shah–Waardenburg syndrome Shiitake mushroom dermatitis (flagellate mushroom dermatitis, mushroom worker's disease, shiitake-induced toxicoderma) Tar melanosis (melanodermatitis toxica lichenoides) Tietz syndrome Titanium metallic discoloration Transient neonatal pustular melanosis (transient neonatal pustulosis, lentigines neonatorum) Trichrome vitiligo Vagabond's leukomelanoderma Vasospastic macule Vitiligo Vitiligo ponctué Vogt–Koyanagi–Harada syndrome Waardenburg syndrome Wende–Bauckus syndrome (Pegum syndrome) Woronoff's ring X-linked reticulate pigmentary disorder (familial cutaneous amyloidosis, Partington amyloidosis, Partington cutaneous amyloidosis, Partington syndrome type II, reticulate pigmentary disorder, X-linked reticulate pigmentary disorder with systemic manifestations) Yemenite deaf-blind hypopigmentation syndrome
MDMA has become widely known as ecstasy (shortened "E", "X", or "XTC"), usually referring to its tablet form, although this term may also include the presence of possible adulterants or diluents. The UK term "mandy" and the US term "molly" colloquially refer to MDMA in a crystalline powder form that is thought to be free of adulterants. MDMA is also sold in the form of the hydrochloride salt, either as loose crystals or in gelcaps. MDMA tablets can sometimes be found in a shaped form that may depict characters from popular culture. These are sometimes collectively referred to as "fun tablets". Partly due to the global supply shortage of sassafras oil—a problem largely assuaged by use of improved or alternative modern methods of synthesis—the purity of substances sold as molly have been found to vary widely. Some of these substances contain methylone, ethylone, MDPV, mephedrone, or any other of the group of compounds commonly known as bath salts, in addition to, or in place of, MDMA. Powdered MDMA ranges from pure MDMA to crushed tablets with 30–40% purity. MDMA tablets typically have low purity due to bulking agents that are added to dilute the drug and increase profits (notably lactose) and binding agents. Tablets sold as ecstasy sometimes contain 3,4-methylenedioxyamphetamine (MDA), 3,4-methylenedioxyethylamphetamine (MDEA), other amphetamine derivatives, caffeine, opiates, or painkillers. Some tablets contain little or no MDMA. The proportion of seized ecstasy tablets with MDMA-like impurities has varied annually and by country.
Sources: en.wikipedia.org
=== Gott ist schön (dissertation 1998) === In his dissertation Gott ist schön (God is Beautiful), which focuses on reception aesthetics and philology, Kermani shows how prominently Islamic tradition perceives the aesthetic dimension of the Koran. The Koran is described as a beguiling, captivating work of art, its beauty capturing people's hearts with an irresistible appeal. The beauty and clarity of the Koran is thus proof of its divine inspiration. According to this conception, God communicates in the Koran in an aesthetically mediated way in hopes to be understood accordingly by those whom the Koran addresses. If God seeks understanding recognition rather than blind obedience, he must encounter receptive people in an aesthetic way. For—at least according to Navid Kermani's thesis informed by his analytical view of Islamic tradition—religious recognition in Islam is conveyed aesthetically as the thrilling, goose bump-inducing hearing of a language described as beautiful, i.e. as an experience of beauty. Kermani is therefore concerned with appreciating the power of aesthetics on a religious level. He views this mystical insight as being entirely in line with the more recent Western aesthetics since Hegel. In almost all philosophical theories of art in the modern tradition, aesthetic experience is about truth. Indeed, contrary to Kant, aesthetic experience need not be about enjoyment or disinterested pleasure. It may simply be about discovering the truth, whatever the cost.
on the toxicity findings of publicly-funded academics, whose methods are very heterogeneous, but who test, and often find, toxicity at much lower doses that industry's TG studies); or, a nation may interpret the accepted study's results according to its own criteria. According to OECD Council Decision C(97)186/Final, chemical testing data generated in any OECD member country following OECD Test Guidelines and GLP principles is recognized by other OECD member countries, such as Australia, Canada, Korea, and the USA. This recognition also extends to some non-OECD countries that fully adhere to the mutual acceptance of data (MAD) under OECD Council Decision C(97)114/Final, including Brazil, India, Malaysia, Singapore, and South Africa, as well as Argentina for industrial chemicals, pesticides, and biocides only. In June 2004, the US FDA published a comparison chart of FDA and EPA Good Laboratory Practice (GLP) regulations alongside OECD Principles for GLP, aiding in understanding the key differences and similarities in GLP standards across these regulatory bodies. Note, unlike many countries, the US EPA names its mandated use of the OECD TG, ‘the EPA Test Methods’.
== Further reading == Stogner JM (December 2014). "The potential threat of acetyl fentanyl: legal issues, contaminated heroin, and acetyl fentanyl "disguised" as other opioids". Annals of Emergency Medicine. 64 (6): 637–9. doi:10.1016/j.annemergmed.2014.07.017. PMID 25153008.
Durvalumab (Imfinzi) is a human immunoglobulin G1 kappa (IgG1κ) monoclonal antibody that blocks the interaction of programmed cell death ligand 1 (PD-L1) with the PD-1 and CD80 (B7.1) molecules. Durvalumab is approved for the treatment of patients with locally advanced or metastatic urothelial carcinoma who:
== Issues raised == The Culture stories are largely about problems and paradoxes that confront liberal societies. The Culture itself is an "ideal-typical" liberal society; that is, as pure an example as one can reasonably imagine. It is highly egalitarian; the liberty of the individual is its most important value; and all actions and decisions are expected to be determined according to a standard of reasonability and sociability inculcated into all people through a progressive system of education. It is a society so beyond material scarcity that for almost all practical purposes its people can have and do what they want. If they do not like the behaviour or opinions of others, they can easily move to a more congenial Culture population centre (or Culture subgroup), and hence there is little need to enforce codes of behaviour. Even the Culture has to compromise its ideals where diplomacy and its own security are concerned. Contact, the group that handles these issues, and Special Circumstances, its secret service division, can employ only those on whose talents and emotional stability it can rely, and may even reject self-aware drones built for its purposes that fail to meet its requirements. Hence these divisions are regarded as the Culture's elite and membership is widely regarded as a prize; yet also something that can be shameful as it contradicts many of the Culture's moral codes.
Sources: en.wikipedia.org
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.
Neutral and slightly basic aqueous conditions promote aspartimide formation at the aspartate-glycine step, often followed by deamidation. Elevated temperature and repeated freeze-thaw cycles accelerate the loss. Acidic solutions and dry lyophilised powder are comparatively stable over short periods.
No monograph exists in the United States Pharmacopeia or the European Pharmacopoeia, and no widely distributed certified reference standard is available. Purity and identity therefore rest on supplier methods that are not harmonised. This absence is the main reason reported purities are difficult to compare between sources.
The peptide contains four residues in the order alanine, glutamate, aspartate and glycine, abbreviated AEDG. The chain is linear and held together by three peptide bonds. Its calculated mass for the uncharged free form is about 390.3 daltons.