If you have been reading about Pro-Gly-Pro 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 2026-01-06. Numbers and descriptions here follow the published literature rather than marketing material.
Identity and purity of selank are established with reversed-phase high-performance liquid chromatography coupled to mass spectrometry. The peptide elutes from C18 columns with acetonitrile gradients in water containing trifluoroacetic acid or formic acid, and detection is usually performed by ultraviolet absorbance near 214 nm. Electrospray ionization in positive mode gives a doubly protonated ion near m/z 377, consistent with a mass of about 752 Da. Amino acid analysis or tandem mass spectrometry of fragment ions confirms the sequence. Because the molecule has no aromatic residues, it lacks a usable 280 nm chromophore, so low-wavelength detection or mass spectrometry is required.
Peptide bonds in selank are susceptible to hydrolysis under strongly acidic or basic conditions, and the terminal proline residues are vulnerable to exopeptidase activity in biological samples. Lyophilized powder stored dry at -20 °C typically remains stable for extended periods, whereas aqueous solutions degrade faster and may lose measurable purity within days to weeks depending on pH, temperature, and microbial load. Repeated freeze-thaw cycles promote aggregation and adsorption to container surfaces. For analytical work, solutions are usually prepared fresh, kept cold, and used within a single working day.
Handling follows standard practice for research peptides. Material is weighed in a low-humidity environment because the powder absorbs atmospheric moisture. Purity is reported as the percentage area of the main peak in a chromatogram, with specifications commonly set at 95 percent or higher; values below that threshold indicate the presence of truncated or modified species. Residual trifluoroacetate from purification is often present and may affect mass balance. Certificates of analysis should state the analytical method, the column and gradient used, and the lot-specific retention time so that results can be compared across suppliers.
Peptide bonds are vulnerable to protease attack, and Selank is no exception. Measured half-life in serum is short, on the order of minutes in several reports, which explains why intranasal administration is the common route described in the literature. Absorption across the nasal mucosa partially bypasses first-pass hepatic metabolism. Quantitative data on human bioavailability remain limited and are difficult to compare across studies.
Lyophilised material kept dry at minus 20 degrees Celsius or colder is the most stable form, and suppliers commonly state a shelf life of two years or more under those conditions. Once dissolved, degradation accelerates through hydrolysis and deamidation, particularly at alkaline pH or elevated temperature. Working solutions are usually divided into single-use aliquots to avoid repeated freeze-thaw cycles. The choice of reconstitution solvent affects both stability and the ionic strength of the final preparation.
Reverse-phase high-performance liquid chromatography with ultraviolet detection near 214 nanometres is the standard purity method. Mass spectrometry, typically electrospray ionisation, confirms identity through the expected mass-to-charge pattern. Amino acid analysis can verify composition independently. Chiral purity requires separate techniques such as derivatisation followed by chromatographic separation, and such data are rarely reported for research-grade material.
| Property | Value | Notes |
|---|---|---|
| Identity confirmation | Reversed-phase HPLC retention time versus reference standard | Retention depends on column, gradient, and ion-pairing agent |
| Mass confirmation | Electrospray or MALDI mass spectrometry | Doubly protonated ion near m/z 377 is consistent with about 752 Da |
| Typical purity specification | 95 percent or higher by chromatographic peak area | Lower values suggest truncated or modified peptide species |
| Storage of lyophilized powder | -20 °C, desiccated, protected from light | Powder tolerates long storage better than solution |
| Storage of solution | 2-8 °C for short periods | Freeze-thaw cycling promotes aggregation and surface adsorption |
Reported pharmacological effects center on reduced anxiety-like behavior in animal models and on measures of memory and learning. Proposed contributing mechanisms include modulation of GABAergic signaling, shifts in monoamine turnover, and changes in the activity of enzymes that degrade neuropeptides. Effects on the expression of genes linked to neuroplasticity have also been described. No single molecular target is widely accepted, and whether the behavioral findings arise from one pathway or several remains an open question.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. It was designed as a stabilized analogue of tuftsin, a naturally occurring tetrapeptide fragment derived from the immunoglobulin heavy chain. The additional Pro-Gly-Pro segment at the carboxyl terminus is intended to slow enzymatic cleavage. The compound is usually described in the literature as a synthetic peptide with anxiolytic and cognitive-related activity, a label that reflects a research context rather than an approved therapeutic category.
Most published work on selank originates from a small number of research groups in the Russian Federation. A large share of that record appears in Russian-language journals, which limits access for readers who rely on English-indexed databases. Independent replication by laboratories outside the original research network is sparse in publicly available sources. This concentration of origin and language is a frequently noted feature when the compound is summarized in broader reviews of synthetic peptides.
Laboratory work relies on standard behavioral paradigms. Rodents are tested in the elevated plus maze, open field, and passive avoidance tasks, with outcomes compared against diazepam or vehicle controls. Intranasal dosing is used most often because it bypasses first-pass metabolism, though intraperitoneal and intravenous routes also appear in published protocols. Biochemical endpoints include tissue BDNF concentrations, cytokine levels, and monoamine metabolites. Human data are limited to small Russian trials reporting reduced anxiety scores; most were not prospectively registered, and few employed independent outcome assessment.
Measuring peptide exposure inside the brain is technically difficult. Selank is degraded rapidly in plasma, and assays must separate intact peptide from fragments, which favors targeted mass spectrometry over immunoassays alone. Reported half-lives are short, on the order of minutes, so effects observed hours later are attributed to downstream signaling rather than to the parent compound. Blood-brain barrier permeability is debated and rarely quantified directly. Gaps include absent dose-response characterization, inconsistent reporting of purity, and almost no pharmacokinetic data from human participants.
== Rhabdomyolysis == Exertional rhabdomyolysis is an extreme and potentially deadly form of overtraining that leads to a breakdown of skeletal muscle which makes its way into the blood. Many molecules such as potassium, creatine kinase, phosphate, and myoglobin are released into circulation. Myoglobin is the protein that causes the lethal reaction in the body. Early detection of the syndrome is essential in full recovery. A serious late complication of rhabdomyolysis which occurs in 15% of the population is acute kidney injury, and in some cases it can lead to death.
==== 1300–1399 ==== Concession Statements (Prescribed Information) Regulations 1993 (S.I. 1993/1300) Gipsy Encampments (City of Hereford) Order 1993 (S.I. 1993/1301) South Wales Police (Amalgamation) (Amendment) (No. 2) Order 1993 (S.I. 1993/1302) Dyfed-Powys Police (Amalgamation) (Amendment) (No. 2) Order 1993 (S.I. 1993/1303) Seed Potatoes (Fees) (Scotland) Regulations 1993 (S.I. 1993/1311) Eastwood and East Kilbride Districts (Busby) Boundaries Amendment Order 1993 (S.I. 1993/1312) Margate Pier and Harbour Revision Order 1992 (SI 1993/1313) Integrated Administration and Control System Regulations 1993 (S.I. 1993/1317) Lewisham and Southwark (London Borough Boundaries) Order 1993 (S.I. 1993/1318) Greater London and Surrey (County and London Borough Boundaries) (No.3) Order 1993 (S.I. 1993/1319) Plant Health (Great Britain) Order 1993 (S.I. 1993/1320) Health and Safety (Fees) Regulations 1993 (S.I. 1993/1321) A500 Newcastle-Under-Lyme to Nantwich Trunk Road (Basford-Hough-Shavington Bypass and Slip Road) Order 1993 (S.I. 1993/1322) A500 Newcastle-Under-Lyme to Nantwich Trunk Road (Basford-Hough-Shavington Bypass) (Detrunking) Order 1993 (S.I. 1993/1323) Post Office (Abolition of Import Restrictions) Regulations 1993 (S.I. 1993/1324) Fishing Vessels (Safety Improvements) (Grants) Scheme 1993 (S.I. 1993/1325) Insurance Companies (Cancellation) Regulations 1993 (S.I. 1993/1327) Diseases of Animals (Therapeutic Substances) (Revocation) Order 1993 (S.I. 1993/1331) Foot-and-Mouth Disease (Sera and Glandular Products) (Revocation) Order 1993 (S.I.
Potassium alum was the major immunologic adjuvant used to increase the efficacy of vaccines, and has been used since the 1920s. But it has been almost completely replaced by aluminium hydroxide and aluminium phosphate in commercial vaccines. Alum may be used in depilatory waxes used for the removal of body hair or applied to freshly waxed skin as a soothing agent.
== Adverse effects == Side effects of mescaline include fatigue, weakness, impaired concentration, restlessness, tension, anxiety, panic, and social discomfort and avoidance, headache, pupil dilation, nausea, vomiting, sweating, trembling, discomfort, feeling hot or cold, palpitations, chest and neck pains, shortness of breath, increased heart rate and blood pressure, and increased body temperature, among others. Nausea and vomiting are important dose-limiting side effects of mescaline and occur at greater rates than with other psychedelics like LSD and psilocybin. High doses of mescaline, such as 800 mg and above, are not well-tolerated due to substantial nausea and vomiting. On the other hand, mescaline appears to induce less fear and anxiety than LSD and psilocybin even at equivalent doses.
Sources: en.wikipedia.org
== Side effects == The side effects of nicergoline are usually limited to nausea, hot flushes, mild gastric upset, hypotension and dizziness. At high drug dosages, bradycardia, increased appetite, agitation, diarrhea and perspiration were reported. Most of the available literature suggests that the side effects of nicergoline are mild and transient.
Critical response to Ellipse was generally positive. At Metacritic, which assigns a normalized rating out of 100 to reviews from mainstream critics, the album received an average score of 68, based on 12 reviews. It also earned her a further two Grammy Nominations on 2 December for Best Pop Instrumental Performance for "The Fire" and Best Engineered Non-Classical Album. On 31 January 2010, it was announced that Heap had won the latter award.
The employees were young men: handsome jocks in form-fitting red-and-white striped soccer shirts; when a patron was celebrating a birthday, the entire restaurant crew came around with a cake and sang TGI Fridays' traditional birthday song. Footage of interviews with patrons from this TGI Fridays was featured in Robert Downey Sr.'s film No More Excuses (1968). The first location closed in 1994 and became a British-style pub called "Baker Street". Although Malachy McCourt's nearby Malachy's singles bar preceded TGI Fridays and Stillman credited the media for creating the term, he had unintentionally created one of the first singles bars. It benefited from the near-simultaneous availability of the birth-control pill and Betty Friedan's book The Feminine Mystique:
Aristotle, however, believed the heart was the center of intelligence and that the brain regulated the amount of heat from the heart. This view was generally accepted until the Roman physician Galen, a follower of Hippocrates and physician to Roman gladiators, observed that his patients lost their mental faculties when they had sustained damage to their brains. Abulcasis, Averroes, Avicenna, Avenzoar, and Maimonides, active in the Medieval Muslim world, described a number of medical problems related to the brain. In Renaissance Europe, Vesalius (1514–1564), René Descartes (1596–1650), Thomas Willis (1621–1675) and Jan Swammerdam (1637–1680) also made several contributions to neuroscience.
A carboxylic acid has the general formula R-C(O)OH, where R is an organic radical. The carboxyl group -C(O)OH contains a carbonyl group, C=O, and a hydroxyl group, O-H. Acetic acid (CH3COOH) Citric acid (C6H8O7) Formic acid (HCOOH) Gluconic acid HOCH2-(CHOH)4-COOH Lactic acid (CH3-CHOH-COOH) Oxalic acid (HOOC-COOH) Tartaric acid (HOOC-CHOH-CHOH-COOH) Halogenation at alpha position increases acid strength, so that the following acids are all stronger than acetic acid. Fluoroacetic acid Trifluoroacetic acid Chloroacetic acid Dichloroacetic acid Trichloroacetic acid Normal carboxylic acids are the direct union of a carbonyl group and a hydroxyl group. In vinylogous carboxylic acids, a carbon-carbon double bond separates the carbonyl and hydroxyl groups. Ascorbic acid Deoxyribonucleic acid (DNA) Ribonucleic acid (RNA) Listing of strengths of common acids and bases Zumdahl, Steven S. (1997). Chemistry (4th ed.). Boston: Houghton Mifflin. ISBN 9780669417944. Pavia, D. L.; Lampman, G. M.; Kriz, G. S. (2004). Organic Chemistry Volume I. Mason, OH: Cengage Learning. ISBN 0759347271.
Sources: en.wikipedia.org
==== Production of "Instant" 99mTc ==== The feasibility of 99mTc production with the 22-MeV-proton bombardment of a 100Mo target in medical cyclotrons was demonstrated in 1971. The recent shortages of 99mTc reignited the interest in the production of "instant" 99mTc by proton bombardment of isotopically enriched 100Mo targets (>99.5%) following the reaction 100Mo(p,2n)99mTc. Canada is commissioning such cyclotrons, designed by Advanced Cyclotron Systems, for 99mTc production at the University of Alberta and the Université de Sherbrooke, and is planning others at the University of British Columbia, TRIUMF, University of Saskatchewan and Lakehead University. A particular drawback of cyclotron production via (p,2n) on 100Mo is the significant co-production of 99gTc. The preferential in-growth of this nuclide occurs due to the larger reaction cross-section pathway leading to the ground state, which is almost five times higher at the cross-section maximum in comparison with the metastable one at the same energy. Depending on the time required to process the target material and recovery of 99mTc, the amount of 99mTc relative to 99gTc will continue to decrease, in turn reducing the specific activity of 99mTc available. It has been reported that ingrowth of 99gTc as well as the presence of other Tc isotopes can negatively affect subsequent labelling and/or imaging; however, the use of high purity 100Mo targets, specified proton beam energies, and appropriate time of use have shown to be sufficient for yielding 99mTc from a cyclotron comparable to that from a commercial generator.
== As a performance-enhancing drug == The possibility of using insulin in an attempt to improve athletic performance was suggested as early as the 1998 Winter Olympics in Nagano, Japan, as reported by Peter Sönksen in the July 2001 issue of Journal of Endocrinology. The question of whether non-diabetic athletes could legally use insulin was raised by a Russian medical officer. Whether insulin would actually improve athletic performance is unclear, but concerns about its use led the International Olympic Committee to ban use of the hormone by non-diabetic athletes in 1998. The book Game of Shadows (2001), by reporters Mark Fainaru-Wada and Lance Williams, included allegations that baseball player Barry Bonds used insulin (as well as other drugs) in the apparent belief that it would increase the effectiveness of the growth hormone he was alleged to be taking. Bonds eventually testified in front of a federal grand jury as part of a government investigation of BALCO. Bodybuilders in particular are claimed to be using exogenous insulin and other drugs in the belief that they will increase muscle mass. Bodybuilders have been described as injecting up to 10 IU of regular synthetic insulin before eating sugary meals. A 2008 report suggested that insulin is sometimes used in combination with anabolic steroids and growth hormone (GH), and that "Athletes are exposing themselves to potential harm by self‐administering large doses of GH, IGF‐I and insulin". Insulin abuse has been mentioned as a possible factor in the deaths of bodybuilders Ghent Wakefield and Rich Piana.
the Georgians) were expelled from these territories." The commission commented, "South Ossetia should not be recognised because the preconditions for statehood are not met." The commission further commented on Abkhazia that "Although it shows the characteristics of statehood, the process of state-building as such is not legitimate, as Abkhazia never had a right to secession." The commission concluded, "The aspirations of the South Ossetian people to self-determination were not fulfilled" in the 1990s, and "The aspirations of the Abkhaz people to self-determination were not fulfilled". The report noted that although Russia had its own interests in the region, Russia was awarded peacekeeping and mediating mandate, which made the peace settlement difficult. The report said that even Russian reports suggested there was evidence of Russian military assistance to separatist troops before August 2008. The commission suggested that incidents before the conflict probably "formed part of a concerted effort directed against Georgia which was orchestrated or actively condoned by the de facto authorities of the two breakaway territories." The commission noted "Both breakaway regions sought the assistance of Russia in the hope that they would receive support should armed hostilities break out, and consequently undermined efforts to defuse the crisis." The commission continued, "In this sense, their behaviour is hardly consistent with the provisions of Art.
Qualification of machinery/equipment is venue dependent, in particular items that are shock sensitive and require balancing or calibration, and re-qualification needs to be conducted once the objects are relocated. The full scales of some equipment qualifications are even time dependent as consumables are used up (i.e. filters) or springs stretch out, requiring recalibration, and hence re-certification is necessary when a specified due time lapse. Re-qualification of machinery/equipment should also be conducted when replacement of parts, or coupling with another device, or installing a new application software and restructuring of the computer which affects especially the pre-settings, such as on BIOS, registry, disk drive partition table, dynamically-linked (shared) libraries, or an ini file etc., have been necessary. In such a situation, the specifications of the parts/devices/software and restructuring proposals should be appended to the qualification document whether the parts/devices/software are genuine or not. Some have discussed the suitability of non-genuine parts for clinical use and provided guidelines for equipment users to select appropriate substitutes which are capable of avoiding adverse effects. In the case when genuine parts/devices/software are demanded by some of regulatory requirements, then re-qualification does not need to be conducted on the non-genuine assemblies. Instead, the asset has to be recycled for non-regulatory purposes.
Sources: en.wikipedia.org
Identity is confirmed by matching the retention time in reversed-phase chromatography against a reference standard and by measuring the molecular mass with mass spectrometry. Tandem mass spectrometry or amino acid analysis can verify the sequence of the seven residues. Because the peptide contains no aromatic amino acids, detection at 280 nm is not useful.
Lyophilized powder is normally stored desiccated at -20 °C, protected from light and moisture. Powder kept under these conditions is generally stable for long periods. Solutions are less stable and are usually prepared immediately before use.
A purity value from one chromatographic method does not capture every possible impurity. Related peptides with similar retention behavior, counterions, and residual solvents may not appear in the same analysis. Independent testing with an orthogonal method provides stronger assurance of identity and content.
Dry powder is best kept sealed, protected from light, and held at minus 20 degrees Celsius or below. Desiccant packaging helps limit moisture uptake because the material is hygroscopic. A sealed vial should be allowed to equilibrate to room temperature before opening to reduce condensation.