mass spectrometry is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Updated 2025-11-16. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
Clinical evidence comes mainly from small studies conducted in Russia, several of which were open-label or lacked robust blinding. Reported outcomes include lower anxiety scores, changes in attention measures, and effects on asthenic states following illness. Sample sizes are typically in the tens of participants, and independent replication outside the region is scarce. Reviews published in English generally note the limited methodological quality of the underlying trials. Whether the compound produces clinically meaningful effects under rigorous conditions remains unresolved.
Proposed mechanisms center on modulation of the GABA system, but no single molecular target has been confirmed. Rodent studies report changes in GABA-A receptor expression and in the turnover of serotonin, dopamine, and norepinephrine in several brain regions. Increases in brain-derived neurotrophic factor and its receptor have also been described after repeated administration. These findings come largely from animal models, and the degree to which they describe human neurochemistry remains an open question. The mechanism is best characterized as multi-system and not fully resolved.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C33H57N11O9 | Derived from the seven-residue sequence |
| Molecular weight | About 751.9 g/mol | Average mass; the monoisotopic value is slightly lower |
| Residue count | Seven amino acids | Thr-Lys-Pro-Arg-Pro-Gly-Pro |
| Parent compound | Tuftsin (Thr-Lys-Pro-Arg) | Selank extends tuftsin at the C-terminus |
| Compound class | Synthetic short peptide | Studied in a research setting; not a licensed drug in most markets |
Identity and purity are usually assessed by reversed-phase high-performance liquid chromatography, with mass spectrometry used to confirm molecular mass and sequence information. Amino acid analysis and peptide mapping may supplement these methods. Certified reference standards are scarce, and many commercial lots are sold as research chemicals without a pharmacopoeial monograph. Regulatory treatment differs by country: Selank is a registered prescription medicine in Russia, while in the European Union and the United States it is not an approved drug and may fall under research-chemical or unapproved-product frameworks.
Selank is a hydrophilic peptide and dissolves readily in water and in aqueous buffers. The lyophilised powder is typically a white to off-white solid. Because short peptides are prone to hydrolysis and oxidation, handling benefits from limiting exposure to heat, moisture and strong light. Working solutions are commonly prepared in sterile water or saline, and repeated freeze-thaw cycles are avoided to reduce aggregation and loss of activity. These practices reflect general laboratory convention rather than published stability specifications.
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.
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.
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.
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.
Otto Hahn (German: [ˈɔtoː ˈhaːn] ; 8 March 1879 – 28 July 1968) was a German chemist who was a pioneer in the field of radiochemistry. He is referred to as the father of nuclear chemistry and discoverer of nuclear fission, the science behind nuclear reactors and nuclear weapons. Hahn and Lise Meitner discovered isotopes of the radioactive elements radium, thorium, protactinium and uranium. He also discovered the phenomena of atomic recoil and nuclear isomerism, and pioneered rubidium–strontium dating. In 1938, Hahn, Meitner and Fritz Strassmann discovered nuclear fission, for which Hahn alone was awarded the 1944 Nobel Prize in Chemistry. A graduate of Marburg University, which awarded him a doctorate in 1901, Hahn studied under Sir William Ramsay at University College London and at McGill University in Montreal, Canada, under Ernest Rutherford, where he discovered several new radioactive isotopes. He returned to Germany in 1906; Emil Fischer let him use a former woodworking shop in the basement of the Chemical Institute at the Friedrich Wilhelm University of Berlin as a laboratory. Hahn completed his habilitation in early 1907 and became a Privatdozent. In 1912, he became head of the Radioactivity Department of the newly founded Kaiser Wilhelm Institute for Chemistry (KWIC). Working with Austrian physicist Lise Meitner in the building that now bears their names, they made a series of groundbreaking discoveries, culminating with her isolation of the longest-lived isotope of protactinium in 1918.
==== Postmenopausal ==== During postmenopause, due to much lower levels of estrogen, and due to lower levels of GH and IGF-1, which decrease with age, mammary gland tissue atrophies and the mammary glands become smaller.
Most pregnant women with sickle cell disease also go on to be single mothers as it is common for them to be left by their male partners who claim they were unaware of their partner's sickle cell disease status. Not only does the abandonment experienced by these women cause emotional distress for them, but this low level of parental support can be linked to depressive symptoms and overall lower quality of life for the child once they are born.
=== 2013–2015: Emergence as a half-back flanker === The 2013 season saw Hibberd play every match of the year for the first time in his career. His performances during the season was described by The Age journalist, Rohan Connolly, as "the best football of his career" and he was named in Connolly's mid-season All-Australian team. His running off of half-back saw him compared to six time All-Australian, Corey Enright, by Rohan Connolly. After the announcement of the forty man squad for the 2013 All-Australian team, he was considered unlucky to miss out on selection by AFL Media journalist, Nick Bowen, and The Age journalist and former player, Matthew Lloyd. His improved season saw him finish fourth in the clubs best and fairest count. Despite a hamstring injury during the 2014 NAB Challenge, Hibberd played the first fourteen matches of the year, before he was forced to miss the round sixteen match against Port Adelaide at the Adelaide Oval due to an ankle injury. He returned to the side two weeks later for the seven point win against the Western Bulldogs at Etihad Stadium in round eighteen, before succumbing to a hamstring injury the next week and missed two weeks. He returned from injury in the three point win against West Coast at Etihad Stadium in round twenty-one, where he was named the best player for Essendon by The Age and AFL Media. He played the remainder of the season, including his first final in the twelve point loss against North Melbourne at the Melbourne Cricket Ground in the second elimination final.
Like any law, such appropriations must be introduced in Congress as a bill and passed by both the House of Representatives and the Senate and then usually be signed by the president. Typically, separate Congressional committees have jurisdiction over authorization and appropriations. The House and Senate Appropriations Committees currently have 12 subcommittees, which are responsible for drafting the 12 regular appropriations bills that determine amounts of discretionary spending for various federal programs. In many recent years, regular appropriations bills have been combined into "omnibus" bills. Congress may also pass "special" or "emergency" appropriations. Spending that is deemed an "emergency" is exempt from certain Congressional budget enforcement rules. Funds for disaster relief have sometimes come from supplemental appropriations, such as after Hurricane Katrina. In other cases, funds included in emergency supplemental appropriations bills support activities not obviously related to actual emergencies, such as parts of the 2000 Census of Population and Housing. Special appropriations have been used to fund most of the costs of war and occupation in Iraq and Afghanistan so far. Budget resolutions and appropriations bills, which reflect spending priorities of Congress, will usually differ from funding levels in the president's budget. The president, however, retains substantial influence over the budget process through veto power and through congressional allies when the president's party has a majority in Congress.
Sources: en.wikipedia.org
CBN was the first cannabinoid to be isolated from cannabis extract in the late 1800s. Specifically, it was discovered by Barlow Wood, Newton Spivey, and Easterfield in 1896. In the early 1930s, CBN's structure was identified by Cahn, marking the first development of a cannabis extract. Its structure and chemical synthesis were achieved by 1940, followed by some of the first preclinical research studies to determine the effects of individual cannabis-derived compounds in vivo.
=== Ethnicity and socioeconomic status === The rates of breastfeeding in the African-American community remain much lower than those of any other race, for a variety of proposed reasons. These include the legacy of wet nursing during slavery, higher rates of poor perinatal health, higher stress levels, less access to support, and less flexibility in the workplace. While for other races, as socio-economic status increases, rates of breastfeeding also go up, for the African-American community, breastfeeding rates remain consistently low regardless of socio-economic class. There are also racial disparities in access to maternity care practices that support breastfeeding. In the US, primarily African-American neighborhoods are more likely to have facilities (such as hospitals and female healthcare clinics) that do not support breastfeeding, contributing to the low rate of breastfeeding in the African-American community. Comparing facilities in primarily African American neighborhoods to ones in primarily European-American neighborhoods, the rates of practices that support or discourage breastfeeding were: limited use of supplements (13.1% compared with 25.8%) and rooming-in (27.7–39.4%) Low-income mothers are more likely to have unintended pregnancies. Mothers whose pregnancies are unintended are less likely to breastfeed. Especially the combination of powdered formula with unclean water can be very harmful to the health of babies. In the late 1970s, there was a boycott against Nestle due to the large number of baby deaths due to formula. Dr.
=== Biochemistry === In proteomics, MALDI is used for the rapid identification of proteins isolated by using gel electrophoresis: SDS-PAGE, size exclusion chromatography, affinity chromatography, strong/weak ion exchange, isotope coded protein labeling (ICPL), and two-dimensional gel electrophoresis. Peptide mass fingerprinting is the most popular analytical application of MALDI-TOF mass spectrometers. MALDI TOF/TOF mass spectrometers are used to reveal amino acid sequence of peptides using post-source decay or high energy collision-induced dissociation (further use see mass spectrometry). MALDI-TOF have been used to characterise post-translational modifications. For example, it has been widely applied to study protein methylation and demethylation. However, care must be taken when studying post-translational modifications by MALDI-TOF. For example, it has been reported that loss of sialic acid has been identified in papers when dihydroxybenzoic acid (DHB) has been used as a matrix for MALDI MS analysis of glycosylated peptides. Using sinapinic acid, 4-HCCA and DHB as matrices, S. Martin studied loss of sialic acid in glycosylated peptides by metastable decay in MALDI/TOF in linear mode and reflector mode. A group at Shimadzu Corporation derivatized the sialic acid by an amidation reaction as a way to improve detection sensitivity and also demonstrated that ionic liquid matrix reduces a loss of sialic acid during MALDI/TOF MS analysis of sialylated oligosaccharides.
Tryptophan produces the head-twitch response (HTR) in rodents when administered at sufficiently high doses. The HTR is induced by serotonergic psychedelics like lysergic acid diethylamide (LSD) and psilocybin and is a behavioral proxy of psychedelic effects. Tryptophan is converted into the trace amine tryptamine and tryptamine is N-methylated by indolethylamine N-methyltransferase (INMT) into N-methyltryptamine (NMT) and N,N-dimethyltryptamine (DMT), which are known serotonergic psychedelics.
While Thatcher won the contest, winning the votes of 85% of Conservative MPs, the next day's Glasgow Herald reported that Heseltine's supporters predicted that unless she changed "her style of leadership", she would "be on her way out next year". In spring 1990 Thatcher's political fortunes were looking weaker, as the Conservatives were badly defeated at the Mid Staffordshire by-election and the Poll tax riots took place. But despite Conservative losses at the local elections, Party Chairman Kenneth Baker spun the result as a success by pointing to the Conservative hold of Westminster and Wandsworth Councils, where the poll tax was low. In May 1990, following the elections, Heseltine wrote an article in The Times proposing reform of the poll tax – he called for the tax to be banded according to income, for councils which spent more than a certain level to face mandatory elections, for elected local mayors and for the restoration of the unitary county boroughs (i.e. making smaller cities into counties in their own right, so ending the confusion as to whether county or district council were responsible for high spending) which he himself had abolished. However, the Iraqi invasion of Kuwait in August 1990, which made war seem likely, boosted Thatcher's popularity.
Sources: en.wikipedia.org
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, designed as a metabolically stabilized analogue of the endogenous tetrapeptide tuftsin. It has been studied mainly against anxiety-related and cognitive endpoints rather than as an approved medicine in most jurisdictions.
Tuftsin contains four residues, while selank carries an additional Pro-Gly-Pro segment at the carboxyl end. That extension is intended to reduce enzymatic cleavage. Comparative pharmacokinetic data in humans remain limited.
No single receptor target is widely accepted as the definitive mediator of the reported effects. Proposed contributors include GABAergic modulation, shifts in monoamine turnover, and altered neuropeptide degradation. The mechanism is treated in the literature as unresolved.
Reports describe effects on GABA-A receptor expression, monoamine turnover, and neurotrophic factor levels. These are proposed mechanisms drawn mainly from animal models. No single molecular target has been established.