A practical reference on mass spectrometry: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2025-10-23. Anything still debated is marked as such rather than presented as settled.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Principal proposed target | GABA-A receptor complex | Hypothesis derived mainly from animal pharmacology |
| Common behavioral assay | Elevated plus maze | Rodent test for anxiety-like behavior |
| Reported molecular marker | Hippocampal BDNF expression | Measured by immunoassay or mRNA quantification |
| Typical dosing route | Intranasal | Chosen to reduce first-pass metabolism |
| Reported plasma half-life | Minutes | Based on limited peptide stability data |
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.
Characterization of Selank in laboratory settings relies on standard peptide analytical techniques. Reverse-phase high-performance liquid chromatography separates the peptide from related impurities and degradation products, while mass spectrometry confirms molecular identity through accurate mass measurement. Amino acid analysis and peptide sequencing verify the primary structure when reference material is unavailable. Because Selank is a short chain, fragmentation-based analysis produces a diagnostic ion pattern that supports confident identification.
The primary structure of Selank is Thr-Lys-Pro-Arg-Pro-Gly-Pro, corresponding to the molecular formula C33H57N11O9 and a monoisotopic mass of roughly 751.9 daltons. The N-terminal threonine and the arginine residue in the fourth position are shared with tuftsin, which carries the sequence Thr-Lys-Pro-Arg. The three additional residues at the C-terminus, Pro-Gly-Pro, extend the chain and are associated with greater resistance to enzymatic degradation. This extension also separates Selank from the shorter parent peptide.
Naming conventions place Selank in the same research family as Semax, another Russian-developed peptide investigated for cognitive effects. The two compounds share a lineage but differ in sequence and in the biological systems proposed as their targets. Semax descends from ACTH fragments, whereas Selank descends from tuftsin. Publications sometimes identify Selank by its full peptide sequence or by laboratory codes rather than one uniform trade name. Because replication outside Russia is limited, reports on its properties are best read alongside the study design and the purity of the material tested.
Reversed-phase high-performance liquid chromatography is the standard technique for estimating peptide purity. The result is a peak-area percentage, which describes how much of the detected material elutes as the main peak in one run. Mass spectrometry confirms the molecular mass and can reveal truncated, adducted, or otherwise modified species. Amino acid analysis or tandem mass spectrometry can address sequence fidelity when identity is in doubt. None of these measurements, taken alone, establishes that a sample is fit for any specific purpose.
Lyophilized selank is normally supplied as a dry powder and is considered stable for extended periods when kept cold and dry. Moisture uptake is the main practical threat, because absorbed water promotes both hydrolysis and aggregation in the solid state. Vials are usually warmed to room temperature before opening so that condensation does not form on the powder. Supplier documentation commonly specifies -20 °C for routine storage, with -80 °C used for material intended to be archived for years.
The Ainu people inhabited the Kuril Islands from early times, although few records predate the 17th century. From the Kamakura period to the Muromachi period, there were Ezo (Ainu) people called Hinomoto from the Pacific coast of Hokkaido to the Kuril region, and Mr. Ando, the Ezo Sateshiku and Ezo Kanrei, was in charge of this ("Suwa Daimyojin Ekotoba"). It is said that when turmoil broke out on Ezogashima, he dispatched troops from Tsugaru. Its activities include the Kanto Gomensen, which calls itself the Ando Suigun, and is based in Jusanminato ("Kaisen Shikimoku"), supplying Japanese products to Ezo society and purchasing large quantities of northern products and shipping them nationwide. ("Thirteen Streets"). The Matsumae clan, a feudal lord of Japan, became independent from the Ando clan (the family of Goro Ando). The Japanese administration first took nominal control of the islands during the Edo period (1603–1868) in the form of claims by the Matsumae clan. The Shōhō Era Map of Japan (Shōhō kuni ezu (正保国絵図)), a map of Japan made by the Tokugawa shogunate in 1644, shows 39 large and small islands northeast of Hokkaido's Shiretoko Peninsula and Cape Nosappu. A Dutch expedition under Maarten Gerritsz Vries explored the islands in 1643. Fedot Alekseyevich Popov sailed into the area c. 1649. Russian Cossacks landed on Shumshu in 1711. American whaleships caught right whales off the islands between 1847 and 1892. Three such ships were wrecked on the islands: two on Urup in 1855 and one on Makanrushi in 1856.
Amylin, or islet amyloid polypeptide (IAPP), is a 37-residue peptide hormone. It is co-secreted with insulin from the pancreatic β-cells in the ratio of approximately 100:1 (insulin:amylin). Amylin plays a role in glycemic regulation by slowing gastric emptying and promoting satiety, thereby preventing spikes in blood glucose levels after a meal. IAPP is processed from an 89-residue coding sequence. Proislet amyloid polypeptide (proIAPP, proamylin, proislet protein) is produced in the pancreatic beta cells (β-cells) as a 67 amino acid, 7404 Dalton pro-peptide and undergoes post-translational modifications including protease cleavage to produce amylin.
There are at least three known isoforms of this protein in humans produced by alternative splicing: isoform 1, of length 442 amino acids, isoform 2 of length 261 amino acids and isoform 3 of length 169 amino acids. MIPOL1 contains two coiled-coil domains in its C-terminus at positions 107 – 212 and 253 – 435 (shown in Fig.1). A bipartite nuclear localization signal is predicted at position 128 – 143. The following post-translational modifications are predicted using bioinformatics tools for MIPOL1. Multiple phosphorylation sites are predicted for this protein, that are conserved in close orthologs, including a Casein kinase 1 (CK1) site, three Casein kinase 2 (CK2) sites, and three NEK2 sites. The exact structure of the MIPOL1 has not yet been characterized. Homology-based and de novo predictions of its tertiary structure suggest that it may consist of inter-twined alpha helices, forming coiled-coil domains (see Fig.4.).
== Occurrence and production == Technetium occurs naturally in the Earth's crust in minute concentrations of about 0.003 parts per trillion. Technetium is so rare because the half-lives of 97Tc and 98Tc are only 4.2 million years. More than a thousand of such periods have passed since the formation of the Earth, so the probability of survival of even one atom of primordial technetium is effectively zero. However, small amounts exist as spontaneous fission products in uranium ores. A kilogram of uranium contains an estimated 1 nanogram (10−9 g), equivalent to ten trillion atoms, of technetium. Some red giant stars with the spectral types S, M, and N display a spectral absorption line indicating the presence of technetium. These red giants are known informally as technetium stars.
Sources: en.wikipedia.org
== Pharmacology == The enzymes do not reach the bloodstream in significant amounts and are presumed to largely stay at the point of injection until they are broken down by proteases. The two collagenases act synergistically by cleaving tropocollagen (the 'collagen molecule') at different points. AUX-I attacks the C- and N-termini, AUX-II cleaves amino acid bonds within the molecule. Small collagen fragments are broken down by both enzymes.
Classification of nerve damage was well-defined by Sir Herbert Seddon and Sunderland in a system that remains in use. The adjacent table details the forms (neurapraxia, axonotmesis and neurotmesis) and degrees of nerve injury that occur as a result of exposure to various temperatures, with the intent to interrupt nerve traffic and relieve pain. Cryoneurolysis treatments that use nitrous oxide (boiling point of −88.5 °C) as the coolant fall in the range of an axonotmesis injury, or 2nd degree injury, according to the Sunderland classification system. Treatments of the nerve in this temperature range are reversible, usually within a few months. Nerves treated in this temperature range experience a disruption of the axon, with Wallerian degeneration occurring distal to the site of injury. The axon and myelin sheath are affected, but all of the connective tissues (endoneurium, perineurium, and epineurium) remain intact. Following Wallerian degeneration, the axon regenerates along the original nerve path at a rate of approximately 1–2 mm per day. Cryoneurolysis differs from cryoablation in that cryoablation treatments use liquid nitrogen (boiling point of −195.8 °C) as the coolant, and therefore, fall into the range of a neurotmesis injury, or 3rd degree injury according to the Sunderland classification. Treatments of the nerve in this temperature range are irreversible. Nerves treated in this temperature range experience a disruption of both the axon and the endoneurium connective tissue layer.
itself should increase with temperature and be independent of density at fixed temperature. In fact, both of these predictions persist in more sophisticated treatments, and accurately describe experimental observations. By contrast, liquid viscosity typically decreases with temperature. For rigid elastic spheres of diameter
Shulman (1943), biophysicist, Sterling Professor emeritus at Yale University Seymour Jonathan Singer (1943), cell biologist and professor at the University of California, San Diego Enoch Callaway (1943), psychiatrist, professor at the University of California, San Francisco Arnold Cooper (1944), psychoanalyst; professor at Weill Cornell Medical College and former president of the American Psychoanalytic Association Robert Jastrow (1944), astronomer, founder of NASA's Goddard Institute for Space Studies and conservative think tank George C. Marshall Institute Joshua Lederberg (1944), winner of the Nobel Prize in Physiology or Medicine Arnold Scheibel (1944), professor of neuroscience at the University of California, Los Angeles Alfred P. Wolf (1944), nuclear and organic chemist; research professor at New York University Paul Marks (1945), geneticist, president emeritus of the Memorial Sloan Kettering Cancer Center, former editor-in-chief of the Journal of Clinical Investigation Jack Oliver (1945), professor of seismology at Columbia University and Cornell University Malvin Ruderman (1945), physicist known for discovering the RKKY interaction Leonard Shengold (1946), psychiatrist at New York University known for study on child abuse Albert Starr (1946), cardiovascular surgeon, winner of the 2007 Lasker Award Arthur Ashkin (1947), winner of the Nobel Prize in Physics in 2018 Robert A. Frosch (1947), fifth administrator of the National Aeronautics and Space Administration Norton Zinder (1947), scientist who discovered bacterial transduction Frank I.
=== Antibody identification === Antibodies to blood group system antigens and their characteristics must be identified when such antibodies are detected in a potential recipient's serum or plasma. The specificity of the antibody aids the medical laboratory scientist in determining if the antibody is clinically significant. Antibody identification is a very laborious process. Characteristics of clinically significant antibodies include: reactive at body temperature (37°C), immunoglobulin (Ig) class G, IgM that reacts at body temperature, ability to cross the placenta, ability to cause red blood cell destruction, and/or antibodies directed against commonly known clinically significant red cell antigens. For example, if an individual is exposed to a red cell antigen (via blood transfusion, pregnancy, stem-cell transplant) that they do not inherently possess, they may form a clinically significant antibody directed against that antigen. If a patient receives a transfusion of packed red blood cells possessing the Kell antigen (big K or simply K), they may form an antibody called anti-K (anti big K). Subsequent transfusions with K-positive packed red blood cells would cause an immediate hemolytic transfusion reaction. The K antibody reacts at 37°C, is IgG, capable of crossing the placenta, and known to cause immediate red blood cell destruction. The presence of autoantibodies directed against self red blood cell antigens can complicate the antibody identification process.
Sources: en.wikipedia.org
== Therapeutic application == Recombinant BNP, nesiritide, has been suggested as a treatment for decompensated heart failure. However, a clinical trial failed to show a benefit of nesiritide in patients with acute decompensated heart failure. Blockade of neprilysin, a protease known to degrade members of the natriuretic peptide family, has also been suggested as a possible treatment for heart failure. Dual administration of neprilysin inhibitors and angiotensin receptor blockers has been shown to be advantageous to ACE inhibitors, the current first-line therapy, in multiple settings.
Alcohol has a variety of short-term and long-term adverse effects. Alcohol has both short-term, and long-term effects on the memory, and sleep. It also has reinforcement-related adverse effects, including alcoholism, dependence, and withdrawal. Alcohol use is directly related to considerable morbidity and mortality, for instance due to intoxication and alcohol-related health problems. The World Health Organization advises that there is no safe level of alcohol consumption. Many of the toxic and unpleasant actions of alcohol in the body are mediated by its carcinogenic byproduct acetaldehyde.
=== Lungs === RAGE is expressed at its highest levels in the lung compared to other tissues, especially in alveolar type I cells. In cases of idiopathic pulmonary fibrosis (IPF), RAGE expression is lost, indicating that its regulation and expression in the pulmonary system differ from that in the vascular system. Studies show that blocking or knocking down RAGE impairs cell adhesion and increases cell proliferation and migration.
== Macquarie Dictionary == The Macquarie Dictionary, which is the dictionary of Australian English, updates the online dictionary each year with new words, phrases, and definitions. These can be viewed on their website. Each year the editors review all new words and definitions that have been added to the dictionary in the past year from which they select a shortlist and invite the public to vote on their favourite. The public vote is held in November and results in the People's Choice winner. The most influential word of the year is also selected by the Word of the Year Committee which comprises the Editorial Team at Macquarie Dictionary along with David Astle and language research specialist Tiger Webb. The Committee meets annually to select the overall winning words. The following is the list of winning words since the Macquarie Word of the Year first began in 2006:
Sources: en.wikipedia.org
Intranasal administration predominates in both animal and human research because it avoids hepatic first-pass metabolism. Injectable and intraperitoneal routes appear in animal work mainly for comparison.
Behavioral endpoints include time spent in open arms of the elevated plus maze and avoidance latencies. Biochemical endpoints include BDNF concentration, cytokine levels, and monoamine metabolite ratios in brain tissue.
Most published studies are small, originate from a limited number of laboratories, and lack independent replication. Dose-response relationships, measured brain exposure, and long-term outcomes are not well characterized.
Selank is a synthetic seven-amino-acid peptide modeled on tuftsin, a fragment of the immunoglobulin G heavy chain. It was designed in Russia to combine anxiolytic and immunomodulatory properties in one molecule.