The short version of Heptapeptide fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2026-02-06. Anything still debated is marked as such rather than presented as settled.
Development took place at the Institute of Molecular Genetics of the Russian Academy of Sciences, where a series of short peptides were designed in the 1980s and 1990s. Selank was selected from variants of tuftsin that showed resistance to plasma peptidases. Russian regulatory approval covers it as an anxiolytic agent given intranasally. Outside that market the compound is normally handled as a research chemical rather than a medicine, and no widely recognised international pharmacopoeial monograph exists. The name Selank is a coined trade designation rather than a systematic chemical name.
Enzymatic stability motivates the extra three residues at the carboxyl end. Native tuftsin is cleaved quickly by circulating aminopeptidases and carboxypeptidases, which limits its duration of action and its usefulness as a tool compound. Extending the chain with proline-rich segments is a common design tactic because proline constrains the backbone and slows proteolysis. The same Pro-Gly-Pro motif appears in other Russian-developed peptides of the era. Whether the full seven-residue chain is required for activity, or whether it acts mainly as a prodrug releasing tuftsin, remains unresolved.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. It was designed at the Institute of Molecular Genetics of the Russian Academy of Sciences as a structural analogue of tuftsin, a naturally occurring tetrapeptide fragment of the immunoglobulin heavy chain. The added Pro-Gly-Pro tail was intended to slow enzymatic degradation and extend biological activity. In Russia it is registered as an anxiolytic nasal preparation, while regulators elsewhere have not approved it for clinical use.
Proposed mechanisms centre on modulation of the GABAergic system, with reports of altered expression of genes related to GABA-A receptor subunits and changed monoamine turnover. Some studies describe inhibition of enkephalinase, the enzyme that degrades endogenous enkephalins, which may prolong opioid peptide signalling. Effects on brain-derived neurotrophic factor and on cytokine expression have also been reported. These findings come largely from animal models and small human studies, and the precise primary target remains unresolved.
Published clinical evidence is limited. Most controlled trials were conducted in Russia, enrolled modest numbers of participants, and appeared in Russian-language journals, which restricts independent verification. Reported outcomes include lower anxiety scores, improved attention and memory measures, and changes in fatigue ratings. Reviews written in English note methodological limitations such as small samples and inconsistent endpoints. Whether the compound produces clinically meaningful benefit relative to established anxiolytics is therefore an open question rather than an established finding.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic heptapeptide | Tuftsin analogue with a C-terminal Pro-Gly-Pro tail |
| Amino acid sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Abbreviated TKPRPGP in most catalogues |
| Molecular mass | About 752 Da | Value for the free peptide |
| Solubility | Freely soluble in water | Aqueous solutions are kept cold and used promptly |
| Typical storage | -20 °C, dry, protected from light | Applies to the lyophilised powder before reconstitution |
Characterization of Selank in a laboratory setting relies on standard peptide methods. Reverse-phase high-performance liquid chromatography separates the target from related impurities and provides a purity figure, commonly reported as 95 percent or higher. Mass spectrometry, typically electrospray ionization or matrix-assisted laser desorption, confirms the molecular mass and helps detect truncation or modification. Amino acid analysis can verify composition when a sequence-level check is needed. These techniques together establish identity and purity for a given lot.
Lyophilized Selank, the dry powder form, is generally stored frozen at minus 20 degrees Celsius or colder for long-term keeping. The solid is hygroscopic and should stay sealed, dry, and protected from light. Once dissolved, the peptide is less stable and is usually held refrigerated at 2 to 8 degrees Celsius for short periods. Repeated freezing and thawing is avoided because it can promote aggregation and loss of activity. Buffers and pH choice also affect how long a solution remains usable.
Solubility behavior is a practical concern for handling. Selank dissolves readily in water and in common aqueous buffers, which simplifies preparation of working solutions. The choice of solvent, ionic strength, and pH can influence aggregation over time, particularly at higher concentrations. Aqueous solutions are typically sterile-filtered before use. Because stability depends on several variables, storage and handling notes should be treated as general guidance rather than fixed rules, and specific values are best confirmed against a certificate of analysis for each batch.
Animal studies have examined behaviour in tests of anxiety, memory retention and stress response, and several report changes in neurotrophic or neurotransmitter-related markers. The human evidence base is much smaller, consisting mainly of short trials conducted in Russia with limited reporting in English-language journals. Sample sizes are modest and outcome measures vary between studies, so the findings are best described as preliminary. Independent replication under modern trial standards has not been widely reported.
Outside its country of origin the compound is generally handled as a research chemical rather than an approved medicine. No regulatory approval from the United States Food and Drug Administration or the European Medicines Agency has been granted for human use. Identity and purity are normally checked by reverse-phase high-performance liquid chromatography, with mass spectrometry used to confirm the molecular mass. Lyophilised material is stored cold and desiccated, and repeated freeze-thaw cycles are avoided.
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In 1968, they produced the first amino acid analyzer in the world, the JLC-5AH. The company also continued to develop its line of electron microscopes. The JEM-7, in 1964, was the first electronic microscope to include a mechanism for the electrical adjustment of the lens axis. The JEM-100B incorporated an electromagnetic deflection unit as well as an electromagnetic stigmator. The first photomicrograph of atomic arrangement in the world was taken by a JEOL electron microscope, in 1976. Kazuo Ito has expressed the company's philosophy as follows:
As such, the total dosage of CPA per month is as much as 30 times the physiological equivalent of progesterone production during the normal menstrual cycle, and is notably equivalent to the total production of progesterone by a corpus luteum throughout the course of a woman's entire cyclic life. Consequently, there is profound overdosage of progestogenic effect (and by extension progestogenic side effects) when CPA is used as an antiandrogen at high doses. For this reason, it has been said that CPA cannot be considered an ideal antiandrogen. Through its action as a progestogen, CPA has been found to significantly increase prolactin secretion and to induce extensive lobuloalveolar development of the mammary glands of female rhesus macaques. In accordance, a study found that CPA, in all cases, induced full lobuloalveolar development of the breasts in transgender women treated with the medication in combination with estrogen for a prolonged period of time. Pregnancy-like breast hyperplasia was observed in two of the subjects. In contrast, the same study found that men with prostate cancer treated with a non-progestogenic antiandrogen like flutamide or bicalutamide and no estrogen produced moderate but incomplete lobuloalveolar development of the breasts. Based on the above research, it was concluded by the study authors that combined estrogenic and progestogenic action is required in transgender women for fully mature female-like histologic breast development (i.e., that includes complete lobuloalveolar maturation).
Sources: en.wikipedia.org
The review has so far identified 22 children who came to harm as a result of actions performed by the surgeon. 2024 Summer Paralympics: ParalympicsGB finish the tournament with 124 medals, including 49 golds, achieving second place in the medal table, and having won medals in all but one Paralympic sport. 9 September The third stage of the UK COVID-19 Inquiry opens, and begins by looking at healthcare. The hearing is told the NHS was "creaking at the seams" at the start of the pandemic and this undermined the quality of healthcare that was given. Kensington Palace releases a video in which Catherine, Princess of Wales confirms she has finished her chemotherapy treatment. 10 September The UK joins France, Germany and the United States in placing fresh sanctions on Iran for supplying Russia with ballistic missiles used against Ukraine, including restricting Iran Air flights to Europe and the US and freezing the assets of key Russian supporters in Iran. The emergency early release of some prisoners to alleviate overcrowding in prisons in England and Wales begins, but Victims' Commissioner Baroness Helen Newlove warns that not all victims of crime were informed of their offenders' early release. Earnings increased by 4% in the three months to July, meaning state pensions for 2025–26 are likely to rise by £460 per year under the triple lock formula. MPs vote 348–228 to restrict winter fuel payments to pensioners receiving Pension Credit.
=== Breeding === The arapaima male is a mouthbrooder, like the related Osteoglossum genus, meaning the young are protected in his mouth until they are older. The female arapaima helps to protect the male and the young by circling them and fending off potential predators. In his book, Three Singles to Adventure, naturalist Gerald Durrell reported that in British Guyana, female arapaima had been seen secreting a white substance from a gland in the head, and that their young were seemingly feeding on the substance.
Eloralintide (LY3841136) is an experimental drug that works as a selective amylin receptor agonist. It was designed to activate the amylin receptor without off-target effects at the calcitonin receptor. In a recent US randomised controlled trial of obese patients (mean bodyweight 109 kg, mean BMI 39 kg/m2), those receiving the highest assessed dose showed a 20 percent reduction in body weight over the 48 week study period when compared to placebo.
Sources: en.wikipedia.org
intraperitoneal organs are covered in serosa (a layer of mesothelium, the visceral peritoneum) retroperitoneal organs are covered in adventitia (loose connective tissue) In the gastrointestinal tract, the muscular layer is bounded in most cases by serosa. However, at the oral cavity, thoracic esophagus, ascending colon, descending colon and the rectum, the muscular layer is instead bounded by adventitia. The muscular layer of the duodenum is bounded by both tissue types. Generally, if it is a part of the digestive tract that is free to move, it is covered by serosa, and if it is relatively rigidly fixed, it is covered by adventitia. The connective tissue of the gallbladder is covered by adventitia where the gallbladder bounds the liver, but by serosa for the rest of its surface.
Blood plasma is a light amber-colored liquid component of blood in which blood cells are absent, but which contains proteins and other constituents of whole blood in suspension. It makes up about 55% of the body's total blood volume. It is the intravascular part of extracellular fluid (all body fluid outside cells). It is mostly water (up to 95% by volume), and contains important dissolved proteins (6–8%; e.g., serum albumins, globulins, and fibrinogen), glucose, clotting factors, electrolytes (Na+, Ca2+, Mg2+, HCO3−, Cl−, etc.), hormones, carbon dioxide (plasma being the main medium for excretory product transportation), and oxygen. It plays a vital role in an intravascular osmotic effect that keeps electrolyte concentration balanced and protects the body from infection and other blood-related disorders. Blood plasma can be separated from whole blood through blood fractionation, by adding an anticoagulant to a tube filled with blood, which is spun in a centrifuge until the blood cells fall to the bottom of the tube. The blood plasma is then poured or drawn off. For point-of-care testing applications, plasma can be extracted from whole blood via filtration or via agglutination to allow for rapid testing of specific biomarkers. Blood plasma has a density of approximately 1,025 kg/m3 (1.025 g/ml). Blood serum is blood plasma without clotting factors. Plasmapheresis is a medical therapy that involves blood plasma extraction, treatment, and reintegration.
Alexander (1940), political activist, writer, and professor at Rutgers University John Hine Mundy (1940), British-American medievalist, professor at Columbia University, former president of the Medieval Academy of America Donald Barr (1941), educator and author; former headmaster of Dalton School; initiated the Columbia University Science Honors Program Ted de Bary (1941), East Asian studies expert and provost of Columbia University Leon Henkin (1941), mathematician and logician at University of California, Berkeley Donald Keene (1942), scholar of Japanese culture Robert Lekachman (1942), economist Philip Yampolsky (1942), scholar of Zen Buddhism Francesco Cordasco (1943), professor of education at Montclair State University Bernard Russell Gelbaum (1943), professor of mathematics at University of California, Irvine Martin S. James (1943), art historian, translator of Piet Mondrian Martin J. Klein (1943), historian of science and recipient of the Abraham Pais Prize for History of Physics Bernard Weisberger (1943), historian of the Reconstruction Era Alan Hoffman (1944), mathematician known for constructing the Hoffman–Singleton graph Bruce Mazlish (1944), historian and professor at Massachusetts Institute of Technology, son-in-law of David Rockefeller Richard Popkin (1944), philosopher Jack Greenberg (1945), counsel for the NAACP, in which capacity he argued Brown v. Board of Education; former professor at Columbia Law School and dean of Columbia College Murray Rothbard (1945), leading exponent of the Austrian School of economics Gilbert Y.
The old wood effect or old wood problem is a pitfall that occurs in the archaeological technique of radiocarbon dating. A sample will provide misleading or confusing results if materials of different ages are deposited in the same context. Stratification is not always clear-cut in practice. In the case of dating megalithic tombs, indirect evidence for the age of the tomb must always be obtained, because stone (or the time of moving a stone) cannot be dated. When a number of objects are recovered from one deposit, the terminus post quem is based on the dating from the 'youngest' find. Even though other items in the same stratum indicate earlier dates, they may have been deposited at the same time. The deposit must be as young, or younger than the youngest object it contains. Thus excavators look to post holes, pits, or find spots under the orthostats for clues to construction dates. The possibility that something (organic) was already in situ must always be considered, especially if the results appear suspiciously early. The old wood problem can appear in marine archaeology. Researchers need to check if stumps from a Mesolithic or Palaeolithic submerged forest are to be found in the area. (If they do, the possibility of one sticking up through, e. g., a shipwreck and giving misleading dates must be considered.) Organic samples which are not derived from the same part of an organism, may show dating variations which blur and obscure the interpretation being attempted.
Sources: en.wikipedia.org
Selank is a seven-amino-acid peptide built from the tuftsin sequence plus a Pro-Gly-Pro tail. It is produced by chemical synthesis rather than extracted from a natural source. The free peptide is usually supplied as a lyophilised powder or in an aqueous formulation.
Tuftsin is a natural tetrapeptide derived from the Fc portion of immunoglobulin G. Selank retains that tetrapeptide at its N-terminus and adds three residues to improve resistance to enzymatic breakdown. The relationship is structural, and the two molecules are not interchangeable in experimental work.
It holds a product registration in Russia for intranasal use as an anxiolytic. Registrations of that kind are not automatically accepted by regulators elsewhere. In most other countries it is treated as an unapproved substance or a research material.
It is a seven-amino-acid peptide, Thr-Lys-Pro-Arg-Pro-Gly-Pro, produced by chemical synthesis rather than extracted from biological tissue. Its design is based on tuftsin, a natural immunomodulatory tetrapeptide. The C-terminal Pro-Gly-Pro segment is a common stabilising motif in short regulatory peptides.