The short version of counterion fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2025-09-16. Anything still debated is marked as such rather than presented as settled.
Epitalon is the common name for a synthetic tetrapeptide with the sequence alanine-glutamate-aspartate-glycine, usually abbreviated AEDG. All four residues are proteinogenic amino acids, and the free peptide has a calculated mass near 390 grams per mole. Because the chain is short and carries no modifications, it is assembled readily by solid-phase synthesis and is distributed mainly as a freeze-dried solid for laboratory work. Catalogue listings use the spellings epitalon, epithalone, and simply AEDG, and the three refer to the same sequence.
The compound is generally presented as a synthetic fragment of epithalamin, a pineal gland extract investigated in the former Soviet Union from the 1970s onward. Vladimir Khavinson and colleagues in Saint Petersburg developed short peptides modelled on such extracts, and epitalon became the most widely cited of those sequences. Most primary reports appeared in Russian-language journals or in proceedings with limited international circulation. Independent replication in laboratories outside that network remains sparse, and much repeated secondary material traces back to a small number of originating groups.
Laboratory work has examined effects on telomerase activity in cultured cells, on melatonin rhythms in animals, and on markers of oxidative stress. Some experiments report measurable changes while others show none, and the reported findings rest largely on small studies. The absence of large independent trials means the generality of these results is unresolved rather than settled. Review articles occasionally apply the label geroprotector, a term that reflects a research hypothesis about ageing rather than an established clinical finding.
Peptides of this size are generally stable as dry solids but degrade in solution over time. The principal routes are hydrolysis of the peptide backbone and oxidation, with hydrolysis favoured by elevated temperature and extreme pH. Aqueous solutions held at room temperature can show measurable loss of purity within days, while frozen aliquots are considerably more durable. Because the sequence contains neither cysteine nor methionine, oxidation is less of a concern than for many other peptides, but pH control during handling still matters.
Typical storage for the lyophilized powder is −20 °C or lower, in a sealed container protected from light and moisture. Hygroscopic material should be allowed to equilibrate to room temperature before the vial is opened, which limits condensation on the contents. Working solutions are commonly divided into single-use aliquots and frozen to avoid repeated freeze-thaw cycles. Dilute solutions are more prone to adsorption onto plastic surfaces and to loss during filtration, so procedures that minimize transfers and use low-binding labware are preferable.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C14H22N4O9 | Computed for the free acid of Ala-Glu-Asp-Gly |
| Molecular mass | About 390.35 g/mol | Free peptide; salt forms shift the value |
| Appearance | White to off-white solid | Typical of short peptides after freeze-drying |
| Solubility class | Freely soluble in water | Aqueous buffers are also commonly used |
| Common synonyms | Epitalon, epithalone, AEDG | AEDG is the single-letter sequence |
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 parent extract epithalamin was characterised as a low-molecular-weight fraction of pineal tissue rather than a single defined chemical entity. Researchers fractionated it and tested successive fragments for activity, a screening approach typical of peptide discovery work in that era. Epitalon emerged from that process as one of the shorter sequences of interest. Because the original extract was never fully resolved into individual components, claims about which constituent drives a given effect rest on inference. This distinction matters when reading older reports that attribute extract observations to the tetrapeptide itself.
Epitalon is a synthetic tetrapeptide with the residue sequence alanine-glutamate-aspartate-glycine, commonly abbreviated AEDG. Its monoisotopic mass is approximately 390.35 daltons, and it is usually supplied as a lyophilised trifluoroacetate or acetate salt. The compound was derived from a pineal gland extract called epithalamin, a heterogeneous preparation investigated in the former Soviet Union. Researchers associated with the Saint Petersburg Institute of Bioregulation and Gerontology described the tetrapeptide as a constituent fragment of that extract. Commercial material is offered as a laboratory reagent rather than as a finished pharmaceutical product.
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.
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.
== Alternative carbon fixation pathways == RuBisCO is important biologically because it catalyzes the primary chemical reaction by which inorganic carbon enters the biosphere. While many autotrophic bacteria and archaea fix carbon via the reductive acetyl CoA pathway, the 3-hydroxypropionate cycle, or the reverse Krebs cycle, these pathways are relatively small contributors to global carbon fixation compared to that catalyzed by RuBisCO. Phosphoenolpyruvate carboxylase, unlike RuBisCO, only temporarily fixes carbon. Reflecting its importance, RuBisCO is the most abundant protein in leaves, accounting for 50% of soluble leaf protein in C3 plants (20–30% of total leaf nitrogen) and 30% of soluble leaf protein in C4 plants (5–9% of total leaf nitrogen). Given its important role in the biosphere, the genetic engineering of RuBisCO in crops is of continuing interest (see below).
Russia launched around 76 missiles on Kyiv, Kharkiv, Poltava, and Kremenchuk, destroying infrastructure. Reports suggested at least four were killed in Kryvyi Rih. The missiles were fired at nine power plants; Ukraine claimed 60 were intercepted. A Ukrainian strike on the village of Lantrativka, in Luhansk Oblast, officially killed 11 Russian trench diggers, but eyewitnesses claimed 84 were killed.
The mean platelet volume (MPV) measures the average size of platelets in femtolitres. It can aid in determining the cause of thrombocytopenia; an elevated MPV may occur when young platelets are released into the bloodstream to compensate for increased destruction of platelets, while decreased production of platelets due to dysfunction of the bone marrow can result in a low MPV. The MPV is also useful for differentiating between congenital diseases that cause thrombocytopenia. The immature platelet fraction (IPF) or reticulated platelet count is reported by some analyzers and provides information about the rate of platelet production by measuring the number of immature platelets in the blood.
Whereas increasing the dose of opioid can be an effective way to overcome tolerance, doing so to compensate for opioid-induced hyperalgesia may worsen the patient's condition by increasing sensitivity to pain while escalating physical dependence. This "uncommon but important phenomenon [can be] seen with high-dose opioid therapy." However, the conclusion of a report published in the Journal of Pain and Palliative Care Pharmacotherapy suggests that "[h]yperalgesia shares a common mechanism with tolerance and it may be that hyperalgesia is a manifestation of tolerance itself."
Sources: en.wikipedia.org
The reaction has the important effect of converting the cofactor, nicotinamide adenine dinucleotide in its reduced form, into its oxidised counterpart NAD+. Isothermal titration calorimetry (ITR), nuclear magnetic resonance (NMR) crystallography, and clonal studies of OcDH and its substrates have led to the identification of the enzyme reaction mechanism. First, the Rossmann fold in Domain I of OcDH binds NADH. Binding of NADH to the Rossmann fold triggers small conformational change typical in the binding of NADH to most dehydrogenases resulting in an interaction between the pyrophosphate moiety of NADH with residue Arg324 on Domain II. This interaction with Arg324 generates and stabilizes the L-arginine binding site and triggers partial domain closure (reduction in the distance between the two domains). The binding of the guanidinium headgroup of L-arginine to the active site of the OcDH:NADH complex (located between the domains) induces a rotational movement of Domain II towards Domain I (via a helix-kink-helix structure in Domain II). This conformational change forms the pyruvate binding site. Binding of pyruvate to the OcDH:NADH:L-arginine complex places the alpha-ketogroup of pyruvate in proximity with the alpha-amino group of L-arginine. The juxtaposition of these groups on the substrates results in the formation of a Schiff base which is subsequently reduced to D-octopine. The priming of the pyruvate site for hydride transfer via a Schiff base through the sequential binding of NADH and L-arginine to OcDH prevents the reduction of pyruvate to lactate.
== System overview == In vertebrates, limb position and velocity are encoded by muscle spindle group Ia afferents responding to muscle length and velocity and muscle spindle group II afferents responding mainly to muscle length. There is a similar division of encoding in invertebrates; different subgroups of neurons of the chordotonal organ encode limb position and velocity. Load on a limb is signaled by Golgi tendon organs: type Ib afferents. These proprioceptors respond to the force a muscle is exerting. Similarly, invertebrates have a mechanism to determine limb load: the campaniform sensilla. These proprioceptors are active when a limb experiences resistance. A third role for proprioceptors is to determine when a joint is at a specific position. In vertebrates, this is accomplished by Ruffini endings and Pacinian corpuscles. These proprioceptors are activated when the joint is at a threshold position, usually at the extremes of joint position. Invertebrates use hair plates to accomplish this; a field of bristles located within joints that detects the relative movement of limb segments through the deflection of the associated cuticular hairs.
== Pulse Sequences == Similar to MRI, MRS uses pulse sequences to acquire signal from several different molecules to generate a spectra instead of an image. In MRS, STEAM (Stimulated Echo Acquisition Method) and PRESS (Point Resolved Spectroscopy) are the two primary pulse sequence techniques used. In terms of advantages, STEAM is best for imaging metabolites with shorter T2 and has lower SAR, while PRESS has higher SNR than STEAM. STEAM and PRESS are most widely used due to their implementation on the major vendors of MR scanners. Beyond STEAM and PRES there are sequences which utilize adiabatic pulses. Adiabatic pulses produce uniform flip angles even when there is extreme B1 inhomogeneity. Thus, these sequences allow us to achieve excitation that achieves the sought-for B1 insensitivity and off-resonance in the RF coil and sampled object. Specifically, adiabatic pulses solve the problem of signal dropout that comes from the different B1 flux patterns that result from the surface transmit coils used and the usage of normal pulses. Adiabatic pulses are also useful for constraints on RF peak power for excitation and lowering tissue heating. Additionally, adiabatic pulses have substantially higher bandwidth, which reduces chemical shift displacement artefact, which is particularly important at high field strengths and when a large range of frequencies are desired to be measured (i.e., measuring both the signals upfield and downfield of water in proton MRS).
== Name == In many English translations of the Bible, Yavne was known as Jabneh . In Greek and Latin-speaking sources, it was known as Jamnia (Ancient Greek: Ἰαμνία Iamníā; Latin: Iamnia). Under Late Roman and Byzantine rule, it had a mixed population of Christians, Jews, and Samaritans. Under the Crusaders, the city was known as Ibelin, and was where the House of Ibelin resided. During the Ottoman and British periods, it was known as Yibna (Arabic: يبنى). The ancient site is now found at the Tel Yavne archeological site, which is southeast of the modern city.
=== Challenges to implementation === Arsenic removal technologies are traditional treatment processes that have been tailored to improve the removal of arsenic from drinking water. Although some of the removal processes, such as precipitative processes, adsorption processes, ion exchange processes, and separation (membrane) processes, may be technically feasible, their cost may be prohibitive. For underdeveloped countries, the challenge is finding the means to fund such technologies. The Environmental Protection Agency, for example, has estimated the total national annualized cost of treatment, monitoring, reporting, record keeping, and administration to enforce the MCL rule to be approximately $181 million. Most of the cost is due to the installation and operation of the treatment technologies needed to reduce arsenic in public water systems.
Sources: en.wikipedia.org
== Role in amyloidogenesis == The alpha sheet has been proposed as a possible intermediate state in the conformational change in the formation of amyloid fibrils by peptides and proteins such as amyloid beta, poly-glutamine repeats, lysozyme, prion proteins, and transthyretin repeats, all of which are associated with protein misfolding disease. For example, amyloid beta is a major component of amyloid plaques in the brains of Alzheimer's disease patients, and polyglutamine repeats in the huntingtin protein are associated with Huntington's disease. These proteins undergo a conformational change from largely random coil or alpha helix structures to the highly ordered beta sheet structures found in amyloid fibrils. Most beta sheets in known proteins are "twisted" about 15° for optimal hydrogen bonding and steric packing; however, some evidence from electron crystallography suggests that at least some amyloid fibrils contain "flat" sheets with only 1–2.5° of twist. An alpha-sheet amyloid intermediate is suggested to explain some anomalous features of the amyloid fibrillization process, such as the evident amino acid sequence dependence of amyloidogenesis despite the belief that the amyloid fold is mainly stabilized by the protein backbone. Xu, using atomic force microscopy, has shown that formation of amyloid fibers is a two-step process in which proteins first aggregate into colloidal spheres of ≈20 nm diameter. The spheres then join together spontaneously to form linear chains, which evolve into mature amyloid fibers.
Increased thrombin inhibition requires the minimal heparin pentasaccharide plus at least an additional 13 monomeric units. This is thought to be due to a requirement that antithrombin and thrombin must bind to the same heparin chain adjacent to each other. This can be seen in the series of models shown in Figure 5. In the structures shown in Figure 5 the C-terminal portion (P' side) of the reactive site loop is in an extended conformation when compared with other un-activated or heparin activated antithrombin structures. The P' region of antithrombin is unusually long relative to the P' region of other serpins and in un-activated or heparin activated antithrombin structures forms a tightly hydrogen bonded β-turn. P' elongation occurs through the breaking of all hydrogen bonds involved in the β-turn. The hinge region of antithrombin in the Figure 5 complex could not be modelled due to its conformational flexibility, and amino acids P9-P14 are not seen in this structure. This conformational flexibility indicates an equilibrium may exist within the complex between a P14 P15 reactive site loop inserted antithrombin conformation and a P14 P15 reactive site loop expelled conformation. In support of this, analysis of the positioning of P15 Gly in the Figure 5 complex (labelled in model B) shows it to be inserted into beta sheet A (see model C).
==== Season 1 ==== The following table represents viewership data for each episode's airing on The CW, as DC Universe did not release viewership information. The pilot episode was tied for the second-best series debut on The CW for the 2019–20 television season with Nancy Drew after Batwoman, and was the best summer series premiere on the network since Whose Line Is It Anyway? season nine in 2013. Through the first seven episodes of the season, Stargirl was averaging a 0.2 rating for adults 18–49 and close to 1 million initial viewers per episode, which was "on par" with The CW's Arrowverse series.
On November 20, 2023, all 8 remaining Connecticut Boston Market locations, located in East Haven, Meriden, West Hartford, Wilton, Stratford, Milford, Bristol, and Newington, were permanently shuttered and issued eviction notices due to unpaid rent. Boston Market and owner Pandya filed for Chapter 11 bankruptcy in December 2023. On January 10, 2024, the company announced that it would allow anyone to open a Boston Market franchise without the usual franchise fees or other buy-in requirements. On January 11, 2024, Boston Market's bankruptcy case was dismissed after the company was unresponsive to court requests. On February 1, 2024, US Foods won its lawsuit against Boston Market, with federal judge Manish Shah saying that Boston Market's defenses in the lawsuit were "gossamer". On February 12, 2024, shortly after its second bankruptcy was dismissed, Boston Market filed for bankruptcy for the third time after losing the US Foods lawsuit. On September 24, 2024, a U.S. bankruptcy judge dismissed Boston Market's appeal regarding a $15 million judgement awarded to US Foods, citing a "lack of prosecution" and Pandya's "bad faith," "delay tactics" and "willful disregard".
Sources: en.wikipedia.org
It is a four-amino-acid peptide with the sequence alanine-glutamate-aspartate-glycine. The chain is unmodified and contains only standard proteinogenic residues, which makes it straightforward to produce by solid-phase synthesis and to characterise by standard peptide methods.
Epitalon and epithalon both circulate, and the difference reflects transliteration of a name coined in Russian-language publications. Reference to the extract it derives from, epithalamin, explains the shared stem. Databases and suppliers are inconsistent, so a search for one spelling alone may miss relevant entries.
No. Epithalamin is a multi-component preparation obtained from pineal tissue, and its exact composition is not fully characterised. Epitalon is a single defined tetrapeptide described as a short synthetic counterpart of that extract, so the two are related in origin but not interchangeable in identity.
The powder is normally kept at −20 °C or below in a sealed, moisture-protected container. Letting the vial reach room temperature before opening helps prevent condensation on the contents.