This is a working overview of Selank, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-06-24. Anything still debated is marked as such rather than presented as settled.
The compound was designed at the Institute of Molecular Genetics of the Russian Academy of Sciences during the 1980s and 1990s. The stated design goal was to retain the immunomodulatory and central nervous system activity attributed to tuftsin while improving resistance to enzymatic breakdown. Adding a proline-rich tail to the short parent peptide was a deliberate strategy, because proline residues restrict the conformations available to many peptidases. The same laboratory produced Semax, an ACTH fragment analog, and both compounds were developed in parallel as short, enzymatically stabilized peptides intended for intranasal use.
Selank is not a naturally occurring peptide and has no known endogenous counterpart in human physiology. Russian-language sources frequently call it TP-7, while English-language sources use the name Selank almost exclusively. Database indexing is uneven, partly because early reports appeared in regional journals that are not widely cataloged. Some summaries describe the material as a tuftsin analog and others as a synthetic heptapeptide; the labels overlap rather than conflict. Citing the primary sequence resolves ambiguity more reliably than the research or trade name alone.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, written TKPRPGP in one-letter notation. Its structure consists of the immunomodulatory tetrapeptide tuftsin, Thr-Lys-Pro-Arg, extended at the carboxyl terminus by a Pro-Gly-Pro segment. The molecular formula is commonly given as C33H57N11O9, corresponding to a monoisotopic mass near 751.4 Da and an average molecular mass near 751.9 Da. All seven residues are proteinogenic amino acids, and the molecule carries no modified side chains or non-natural linkages.
Purity assessment relies mainly on reverse-phase high-performance liquid chromatography with ultraviolet detection. Because the peptide lacks a strong chromophore, detection often uses backbone absorbance near 214 nm. Identity is confirmed by mass spectrometry, typically electrospray ionization or matrix-assisted laser desorption, comparing the measured mass against the expected value. Amino acid analysis can verify composition after acid hydrolysis. Diastereomer content and residual counterions are reported less often, although both can influence biological assays.
Lyophilized material is generally stable for extended periods when kept dry at or below minus twenty degrees Celsius. Working solutions are less stable, and common practice is to aliquot and freeze them so that repeated freeze-thaw cycles are avoided. Aqueous solutions are sensitive to pH extremes and to microbial growth, so short-term storage at refrigerator temperature is typical. Oxidation and hydrolysis are the principal degradation routes. Reconstitution with sterile water or a mild buffer is standard, and solutions should be protected from light.
Regulatory treatment varies by jurisdiction. In Russia the compound is a registered prescription product, while in the European Union and the United States it is generally handled as a research chemical without a marketing authorization. Suppliers therefore operate outside pharmaceutical oversight, and buyers rely on supplier documentation for purity and identity claims. Chain of custody and third-party testing are the main verification tools. Analysts note that the absence of a pharmacopoeial monograph for research-grade material limits standardization across vendors.
| Property | Value | Notes |
|---|---|---|
| Peptide sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Seven residues; tuftsin plus a Pro-Gly-Pro tail |
| Molecular formula | C33H57N11O9 | Commonly reported value for the free peptide |
| Monoisotopic mass | Roughly 751.4 Da | Average molecular mass near 751.9 Da |
| Appearance | White to off-white powder | Typically supplied as a lyophilized solid |
| Solubility class | Freely soluble in water | Also dissolves in saline and other polar solvents |
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.
Selank is studied chiefly as an animal-model anxiolytic with proposed secondary effects on memory and immune signaling. Reported mechanisms include modulation of the GABA-A receptor complex, inhibition of enkephalin-degrading enzymes, and shifts in monoamine turnover within limbic structures. Some experiments describe increased expression of brain-derived neurotrophic factor in the hippocampus after repeated dosing. No single molecular target has been confirmed, and the peptide does not bind any receptor with the selectivity typical of a conventional small-molecule drug. Mechanism therefore remains a set of hypotheses rather than an established pathway.
Regulatory status differs sharply by region. Selank holds a Russian marketing authorization, where it is supplied mainly as nasal drops, while authorities elsewhere have not approved it for medical use. Material sold internationally is therefore usually labeled as a research chemical rather than a medicine. Peer-reviewed publications come predominantly from Russian laboratories, and sample sizes are generally small. Whether the compound produces comparable effects under independent, well-controlled replication remains an open question that the broader literature has not settled.
Selank is a synthetic heptapeptide developed in Russia as a structural analogue of tuftsin, a naturally occurring immunomodulatory tetrapeptide. Its sequence, Thr-Lys-Pro-Arg-Pro-Gly-Pro, keeps the tuftsin core at the N-terminus and appends a Pro-Gly-Pro tail. Researchers at the Institute of Molecular Genetics in Moscow synthesized the compound during the 1990s while searching for peptides with combined anxiolytic and immunomodulatory activity. The added tail was intended to resist enzymatic cleavage and prolong the molecule's presence in circulation.
The compound has a calculated molecular weight near 751.9 daltons and carries a net positive charge at physiological pH because of its arginine residue. It dissolves freely in water and in common aqueous buffers, and typically appears as a white or off-white lyophilized powder. The amide backbone makes the molecule susceptible to peptidases, which limits oral use and favors intranasal or parenteral routes. Nomenclature in the literature varies: the substance is also described by the sequence abbreviation TP-7 and by a Russian trade designation.
Peptide stability depends strongly on temperature, moisture, and pH. Lyophilized Selank is generally most stable when stored cold and dry, with freezer temperatures commonly used for long-term storage. In solution, the compound is susceptible to hydrolysis and to microbial growth if it is not handled aseptically. The C-terminal proline-rich extension appears to slow enzymatic cleavage relative to tuftsin, though quantitative degradation rates vary with the matrix and the conditions tested. Published stability data specific to Selank remain sparse.
Quality assessment of Selank samples typically combines purity determination with identity confirmation and counter-ion analysis. Purity is usually reported as a percentage by chromatographic area, with values above 95 percent often quoted for research-grade material. Water content and residual solvents are checked in lyophilized batches because they affect both stability and accurate mass determination. A reported purity figure does not by itself establish that a sample is the intended sequence, so orthogonal methods are needed to rule out sequence isomers or truncation products.
In the first few days after the call for overseas service on 9 August, the result in many TF units was hesitant, with some units only recording around 50% volunteering, partly because men with families were reluctant to leave well-paid jobs especially while there was talk of a German invasion of the homeland, but the pace rapidly accelerated and, within a fortnight, 70 infantry battalions and many other units had collectively volunteered for France. initially TF units were either fed into regular brigades or used for secondary tasks, such as guarding lines of communication but, by the end of April 1915, six full Territorial divisions had been deployed into the fight. The (Regular) Expeditionary Force of six divisions had been rapidly sent to the Continent, where, facing overwhelming odds, they secured the left flank of the French Army. Of the 90,000 members of the original BEF deployed in August, four-fifths were dead or wounded by Christmas. So the arrival of the Territorials, first as reinforcements and then in whole divisions came at a critical juncture, while the New Army was still forming and training. Many of the Territorial units suffered immediate heavy casualties and on the night of 20 April 1915 Second Lieutenant Geoffrey Woolley of the Queen Victoria Rifles, secured the first of the 71 Victoria Crosses won by Territorials in the First World War.
Flaxen chestnut and blond chestnut are terms that describe manes and/or tails that are flaxen, or significantly lighter than the body color. Sometimes this difference is only a shade or two, but other flaxen chestnuts have near-white or silverish manes and tails. Haflingers are exclusively of this shade. It is considered desirable in other breeds, though the genetic mechanism is not fully understood. Some flaxen chestnuts can be mistaken for palominos and have been registered in palomino color registries. Pangaré or mealy is thought to be controlled by a single gene, unrelated to chestnut color, and produces distinct characteristics common to wild equids: pale hairs around the eyes and muzzle and a pale underside. Haflingers and Belgians are examples of mealy chestnuts. The flaxen characteristic is sometimes associated with pangaré.
A GFD involves removing all food and drink that contains wheat, rye, barley, and gluten derivatives. Coeliac disease symptoms can improve within days of adopting a GFD, and the diet improves quality of life, prevents further complications, and can normalise some effects of the disease such as stunted growth. The GFD can be difficult, requiring significant education and motivation. Additionally, the GFD diet may lead to nutritional deficiencies due to difficulties accessing nutritionally balanced gluten-free food. As such, a referral to a dietitian is recommended by treatment guidelines. A dietitian can help those with coeliac disease identify gluten-containing food and maintain a nutritionally balanced diet. The exact amount of gluten that may be tolerable for those with coeliac disease varies, with some people able to consume around 35 mg per day without damage to the intestines, while others can not tolerate more than 10 mg a day. Currently, international regulatory agencies require a product to contain less than 20 ppm (about 6 mg per day) of gluten to be labelled as gluten-free.
Sources: en.wikipedia.org
Decay energy column Multiple values for decay energy for each given decay mode (skipping SF), in respective order. Decay energies are the whole energy difference to the ground state of the product, and so include energy lost to neutrinos. Further decays in a decay chain are not included.
==== Oil ==== Oil is generally a product of thermal breakdown of type I and type II kerogen during catagenesis. The HIC should reflect the source kerogen signal, generation fractionation, isotopic exchange and other maturation effects. Thermal maturation at the oil window can erase much of the HIC primary signals. The formation of oil involves breaking C-C and C-H bonds, resulting in depletion of 13C and 2H in the products and enrichment in the residual reactants due to KIEs. Yongchun Tang and his colleagues modeled this process based on laboratory-calibrated kinetics data and found that the frequency factor ratio for D/H is 1.07. Moreover, oil is also affected by isotope fractionation from phase changes. However, the behavior of oil gas-liquid fractionation differs from water as the vapor phase of oil is 2H-enriched. This depletes residual oil as it gets evaporated. Biodegradation of oil is also expected to fractionate hydrogen isotopes, as enzymatic breaking of C-H bond has a normal KIE. Several degradation experiments show that this fractionation is generally mild, ranging from −11‰ to −79‰. This process should also enrich partially degraded oil. Finally, oil stored in a reservoir often had migrated through subsurface (aka geochromatography) from another source region, interacting with water. No data has been published to confirm the fractionation associated with migration, yet theoretical prediction shows that this is likely to be very small. Many studies of natural samples have shown slight increases in δD with thermal maturity.
hENT3 is expressed highly in the cerebral cortex, lateral ventricle, ovary and adrenal gland. hENT4 is more commonly known as the plasma membrane monoamine transporter (PMAT), as it facilitates the movement of organic cations and biogenic amines across the membrane.
The Boers struck first on 12 October at the Battle of Kraaipan, an attack that heralded the invasion of the Cape Colony and Natal between October 1899 and January 1900. With speed and surprise, the Boers drove quickly towards the British garrison at Ladysmith and the smaller ones at Mafeking and Kimberley. The quick Boer mobilisation resulted in military successes against scattered British forces. Sir George Stuart White, commanding the British division at Ladysmith, unwisely allowed Major-General Penn Symons to throw a brigade forward to the coal-mining town of Dundee (also reported as Glencoe), surrounded by hills. This became the war's first major clash, the Battle of Talana Hill. Boer guns began shelling the British camp from the summit of Talana Hill at dawn on 20 October. Penn Symons immediately counter-attacked: His infantry drove the Boers from the hill, for the loss of 446 British casualties, including Penn Symons. Another Boer force occupied Elandslaagte, which lay between Ladysmith and Dundee. The British under Major General John French and Colonel Ian Hamilton attacked to clear the line of communications to Dundee. The resulting Battle of Elandslaagte was a clear-cut British tactical victory, but White feared more Boers were about to attack his main position and ordered a chaotic retreat from Elandslaagte, throwing away the advantage gained. The detachment from Dundee was compelled to make an exhausting cross-country retreat to rejoin White's main force. As Boers surrounded Ladysmith and opened fire with siege guns, White ordered a major sortie against them.
Sources: en.wikipedia.org
== Mechanical stress and activity indicators == Examining the effects that activities has upon the skeleton allows the archaeologist to examine who was doing what kinds of labor, and how activities were structured within society. Labor within the household may be divided according to gender and age, or be based on other social structures. Human remains can allow archaeologists to uncover these patterns. Living bones are subject to Wolff's law, which states that bones are physically affected and remodeled by physical activity or inactivity. Increases in mechanical stress tend to produce thicker and stronger bones. Disruptions in homeostasis caused by nutritional deficiency or disease or profound inactivity/disuse/disability can lead to bone loss. While the acquisition of bipedal locomotion and body mass appear to determine the size and shape of children's bones, activity during the adolescent growth period seems to exert a greater influence on the size and shape of adult bones than exercise later in life. Muscle or ligament attachment sites on bones (entheses) are also considered to be impacted by habitual biomechanical loading, leading to the occurrence of various entheseal changes. These changes are routinely used in the field to study activity-patterns.
Harkin responded by elevating OAM into an independent NIH "center", just short of being its own "institute", and renamed it the National Center for Complementary and Alternative Medicine (NCCAM). NCCAM had a mandate to promote a more rigorous and scientific approach to the study of alternative medicine, research training and career development, outreach, and "integration". Stephen Strauss was the director of NCCAM from 1999 to 2006. He tried to bring more scientific rigor to the organization. In 1999 the NCCAM budget was increased from $20 million to $50 million. The United States Congress approved the appropriations without dissent. In 2000, the budget was increased to about $68 million, in 2001 to $90 million, in 2002 to $104 million, and in 2003, to $113 million.
== Nomenclature == Metastable isomers of a particular isotope are usually designated with an "m". This designation is placed after the mass number of the atom. For example, cobalt-58m1, or 58m127Co, is an isomer of cobalt-58. Here, 27 is the atomic number of cobalt, 58 is the total number of nucleons (meaning it has 31 neutrons), "m" means it is an isomer, and "m1" means it is the first (lowest above the ground state) metastable isomer. For isotopes with more than one metastable isomer, "indices" are placed after the designation, and the labeling becomes m1, m2, m3, and so on. Increasing indices, m1, m2, etc., correlate with increasing levels of excitation energy stored in each of the isomeric states (e.g., hafnium-178m2, or 178m272Hf). The index may be omitted if only one isomer is relevant in-context. For fission isomers, use "f" rather than "m".
In December 2019, the US Food and Drug Administration (FDA) announced that it learned that some metformin medicines manufactured outside the United States might contain a nitrosamine impurity called N-nitrosodimethylamine (NDMA), classified as a probable human carcinogen, at low levels. Health Canada announced that it was assessing NDMA levels in metformin. The European Medicines Agency provided an update on NDMA in metformin. In February 2020, the FDA found NDMA levels in some tested metformin samples that did not exceed the acceptable daily intake. In February 2020, Health Canada announced a recall of Apotex immediate-release metformin, followed in March by recalls of Ranbaxy metformin and in March by Jamp metformin. In May 2020, the FDA asked five companies to voluntarily recall their sustained-release metformin products. The five companies were not named, but they were revealed to be Amneal Pharmaceuticals, Actavis Pharma, Apotex Corp, Lupin Pharma, and Marksans Pharma Limited in a letter sent to Valisure, the pharmacy that had first alerted the FDA to this contaminant in metformin via a Citizen Petition. In June 2020, the FDA posted its laboratory results showing NDMA amounts in metformin products it tested. It found NDMA in certain lots of ER metformin and is recommending companies recall lots with levels of NDMA above the acceptable intake limit of 96 nanograms per day. The FDA is also collaborating with international regulators to share testing results for metformin.
== Transportation units == Prior to the 2018 reforms, the People's Armed Police Transportation Corps (Chinese: 武警交通部队) was its own independent corps under the dual command of the PAP and the Ministry of Transport. During the 2018 reforms, the Transportation Corps was reorganised into part of the 1st and 2nd mobile corps. The mission of Transport units of the People's Armed Police is to conduct disaster relief and emergency repair on highways, bridges, tunnels, seaports railways and airports, security to construction projects related to national security along with law enforcement duties on highways in border regions.
Sources: en.wikipedia.org
The sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, written TKPRPGP in one-letter code. It combines the tetrapeptide tuftsin with a carboxyl-terminal Pro-Gly-Pro extension. This full sequence identifies the molecule more precisely than the research name.
No peptide with this exact sequence has been identified as an endogenous substance. It is a laboratory-designed analog of tuftsin, a naturally occurring immunomodulatory tetrapeptide. The Pro-Gly-Pro extension has no known natural source.
Proline introduces conformational constraints that make a peptide less accessible to common peptidases. This is a standard stabilization strategy in peptide design. The added residues also increase the distance between the active tuftsin portion and typical cleavage sites.
Purity is usually reported as an HPLC area percentage, most often measured at 214 nm. Identity is confirmed separately by mass spectrometry. A certificate of analysis should state both the method and the observed value.