A practical reference on HPLC: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
This page was last updated on 2026-02-23 and is reviewed periodically as new material appears.
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.
Pharmacokinetic data are sparse and largely derived from animal work. After intranasal administration the peptide appears in plasma within minutes, and reported half-lives are short, on the order of minutes to tens of minutes. Degradation proceeds through ordinary proteolytic cleavage into constituent amino acids and smaller fragments. Direct evidence that intact Selank reaches brain tissue in meaningful amounts is limited, and the extent of blood-brain barrier penetration is debated. Some authors argue that fragments, not the parent peptide, carry much of the observed activity.
Published clinical work is concentrated in Russian-language journals and generally involves small samples without independent replication. Systematic reviews in English note the shortage of randomised, placebo-controlled trials and the difficulty of verifying methods from translated reports. Outcome measures vary between studies, which complicates pooling of results. Interest in the compound as a cognitive or anxiolytic agent therefore rests on a thinner evidence base than the volume of citations suggests. Replication in well-powered trials with preregistered endpoints would be needed before firm conclusions about efficacy can be drawn.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic heptapeptide | Analog of the tetrapeptide tuftsin |
| Sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Reported consistently across pharmacopoeial descriptions |
| Appearance | White to off-white lyophilized powder | Typical form of research-grade material |
| Solubility | Freely soluble in water | Aqueous buffers; poor in nonpolar solvents |
| Typical storage temperature | -20 degrees Celsius | Lyophilized powder; protect from moisture |
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.
Pharmacokinetic data are limited. Like most short peptides, Selank is vulnerable to plasma and tissue peptidases, and its measured half-life in circulation is short, on a minutes scale. The Pro-Gly-Pro tail slows this degradation but does not eliminate it. Intranasal administration is the route described in most reports, with absorption through the nasal mucosa and a hypothesized path into the central nervous system that avoids the blood-brain barrier. Direct measurements of human brain exposure are unavailable, so distribution claims rest on inference from animal work.
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.
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.
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.
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.
== Reactions == DBNPA decomposition is dominated by two reaction pathways: pH-dependent hydrolysis and light-catalyzed reactions with reducing nucleophiles. DBNPA's electrophilic bromine atoms and electron-withdrawing cyano (-CN) group play a major role in determining its reactivity. A number of variables, including temperature, pH, light exposure, and reducing agents, have a substantial impact on the rate and mechanism of DBNPA breakdown. Different organic and inorganic byproducts could therefore develop, which could have an impact on DBNPA's toxicity and biocidal effectiveness.
==== Works ==== A.A.A (EP), by Nigerian band A.A.A AAA (Lee Hwi-min album), 2022 AAA (Hyukoh and Sunset Rollercoaster album), 2024 Access All Areas (EP), by The AAA Girls, 2017 Access All Areas (Flo album), 2024, including a song titled "AAA" "AAA", a song on City (Strapping Young Lad album), 1997 "Aaa", a song by They Might Be Giants on their 2015 album Glean Greek: "ΑΑΑ (ΑΑΑ) και χωρίσαμε", romanized: AAA (AAA) kai korisame, lit. 'AAA (AAA) and we broke up', a song on Kravgi by Anna Vissi, 2000
=== History of ideas === Brown, T.M. (1965). "Resource letter EEC-1 on the evolution of energy concepts from Galileo to Helmholtz". American Journal of Physics. 33 (10): 759–765. Bibcode:1965AmJPh..33..759B. doi:10.1119/1.1970980. Cardwell, D.S.L. (1971). From Watt to Clausius: The Rise of Thermodynamics in the Early Industrial Age. London: Heinemann. ISBN 978-0-435-54150-7. Guillen, M. (1999). Five Equations That Changed the World. New York: Abacus. ISBN 978-0-349-11064-6. Hiebert, E.N. (1981). Historical Roots of the Principle of Conservation of Energy. Madison, Wis.: Ayer Co Pub. ISBN 978-0-405-13880-5. Kuhn, T.S. (1957) "Energy conservation as an example of simultaneous discovery", in M. Clagett (ed.) Critical Problems in the History of Science pp.321–56 Sarton, G.; Joule, J. P.; Carnot, Sadi (1929). "The discovery of the law of conservation of energy". Isis. 13: 18–49. doi:10.1086/346430. S2CID 145585492. Smith, C. (1998). The Science of Energy: Cultural History of Energy Physics in Victorian Britain. London: Heinemann. ISBN 978-0-485-11431-7. Mach, E. (1872). History and Root of the Principles of the Conservation of Energy. Open Court Pub. Co., Illinois. Poincaré, H. (1905). Science and Hypothesis. Walter Scott Publishing Co. Ltd; Dover reprint, 1952. ISBN 978-0-486-60221-9. {{cite book}}: ISBN / Date incompatibility (help), Chapter 8, "Energy and Thermo-dynamics"
== See also == Le Grand Saut Lockheed U-2 Overshooting top Ozone depletion Batterie Pommern (the first projectile to reach the lower stratosphere) Paris Gun (projectile was the first artificial object to reach the upper stratosphere) Perlan Project Project Excelsior, world record for highest recorded jump 1961–2012 Red Bull Stratos, world record for highest recorded jump 2012–2014 RQ-4 Global Hawk Service ceiling Upper-atmospheric lightning Sudden stratospheric warming
Sources: en.wikipedia.org
The Australian Football League (AFL) started in 1897 and was originally called the Victorian Football League until its name change in 1990 due to its expansion to other Australian states. AFL is often viewed as an iconic Australian sport which attracts large crowds averaging 35,000 people per game. Drugs are usually known as a chemical compound that has an effect on a person's body in some way, either physically or psychologically. Drugs specific to elite sports, such as AFL, can include anabolic steroids and stimulants due to their performance-enhancing effects. The consumption of these drugs is known as doping. Doping is the administration of drugs to enhance the performance of a person or athlete. This can create unfair advantages in the game and also could lead to many health risks to the players that are doping. The AFL also has practices in place related to the use of illicit recreational drugs.
=== Cultural and other influences === In ancient Egypt, depilation was commonly practiced, with pumice and razors used to shave. In both Ancient Greece and Ancient Rome, the removal of body and pubic hair may have been practiced among both men and women. It is represented in some artistic depictions of male and female nudity, examples of which may be seen in red figure pottery and sculptures like the Kouros of Ancient Greece in which both men and women were depicted without body or pubic hair. Emperor Augustus was said, by Suetonius, to have applied "hot nutshells" on his legs as a form of depilation. In the clothes free movement, the term "smoothie" refers to an individual who has removed their body hair. In the past, such practices were frowned upon and in some cases, forbidden: violators could face exclusion from the club. Enthusiasts grouped together and formed societies of their own that catered to that fashion, and smoothies became a major percentage at some nudist venues. The first Smoothie club (TSC) was founded by a British couple in 1991. A Dutch branch was founded in 1993 in order to give the idea of a hairless body greater publicity in the Netherlands. Being a Smoothie is described by its supporters as exceptionally comfortable and liberating. The Smoothy-Club is also a branch of the World of the Nudest Nudist (WNN) and organizes nudist ship cruises and regular nudist events.
The widespread nature of Gulf of Mexico chemosynthetic communities was first documented during contracted investigations by the Geological and Environmental Research Group (GERG) of Texas A&M University for the Offshore Operators Committee. This survey remains the most widespread and comprehensive, although numerous additional communities have been documented since that time. Industry exploration for energy reserves in the Gulf of Mexico has also documented numerous new communities through a wide range of depths, including the deepest-known occurrence in the Central Gulf of Mexico in Alaminos Canyon Block 818 at a depth of 2,750 metres (9,020 feet). The occurrence of chemosynthetic organisms dependent on hydrocarbon seepage has been documented in water depths as shallow as 290 metres (950 feet) and as deep as 2,744 metres (9,003 feet). This depth range specifically places chemosynthetic communities in the deepwater region of the Gulf of Mexico, which is defined as water depths greater than 305 metres (1,001 feet). Chemosynthetic communities are not found on the continental shelf, although they do appear in the fossil record in water shallower than 200 metres (660 feet). One theory explaining this is that predation pressure has varied substantially over the time period involved (Callender and Powell 1999). More than 50 communities are now known to exist in 43 Outer Continental Shelf (OCS) blocks.
Sources: en.wikipedia.org
== Plot == Fifteen-year-old orphan Jolene breaks free from foster care, marrying Mickey, a nerdy 20-year-old. They live with Mickey's Uncle Phil and Aunt Kay. On the night before her sixteenth birthday, Jolene asks Mickey about his mother, but he rebuffs her and starts crying. To make him feel better, she seduces him, but Mickey's inexperience leads to uncomfortable and joyless sex. The next day, Mickey and Uncle Phil wish Jolene "Happy Birthday" with Kay asking Jolene to clean the floor. Phil walks in and is aroused by Jolene's dancing while cleaning the floor and they have sex. They start a passionate affair, and Phil promises to build a house for the two of them, but asks Jolene to keep their relationship a secret, due to them both being married. Upon catching Phil and Jolene in bed, Kay kicks Jolene out of the house. After a physical altercation with Phil, Mickey drives off and kills himself by jumping off a bridge. Aunt Kay has Jolene placed in a juvenile mental institution, where she meets Cindy, a psychiatric nurse. Jolene, a talented artist, asks for paper and colored pencils to draw. Her request is denied, but she is allowed crayons, and she starts a small business selling crayon portraits to her fellow patients. Jolene is called to testify against Uncle Phil, and he is sentenced to eighteen months in prison for statutory rape. Cindy, a closeted lesbian, is immediately infatuated with Jolene and this culminates in another affair. Cindy breaks Jolene out of the mental hospital and hides her in her apartment.
== Indications == D-dimer testing is of clinical use when there is a suspicion of deep venous thrombosis (DVTl), pulmonary embolism (PE) or disseminated intravascular coagulation (DIC). For DVT and PE, there are possible various scoring systems that are used to determine the a priori clinical probability of these diseases; the best-known is the Wells score.
Perfumes contain chemicals that vaporize at different temperatures and at different rate in scent accords, known as notes. Atmospheric water vapor is found near the earth's surface, and may condense into small liquid droplets and form meteorological phenomena, such as fog, mist, and haar. Mercury-vapor lamps and sodium vapor lamps produce light from atoms in excited states. Flammable liquids do not burn when ignited. It is the vapor cloud above the liquid that will burn if the vapor's concentration is between the lower flammable limit (LFL) and upper flammable limit (UFL), of the flammable liquid. E-cigarettes produce aerosols, not vapors.
Cells of one type may release the 5(S)-HETE that they make to nearby cells of a second type which then oxidize the 5(S)-HETE to 5-oxo-ETE. This transcellular production typically involves the limited variety of cell types that express active 5-lipoxygenase, lack HEDH activity because of their high levels of NADPH compared to NADP+ levels, and therefore accumulate 5(S)-HETE, not 5-oxo-ETE, upon stimulation. This 5(S)-ETE can leave these cells, enter various cell types that possess 5-HEDH activity along with lower NADPH to NADP+ levels, and thereby be converted to 5-oxo-ETE. Transcellular production of 5-oxo-eicosatetraenoates has been demonstrated in vitro with human neutrophils as the 5(S)-HETE producing cells and human PC-3 prostate cancer cells, platelets, and monocyte-derived dendritic cells as the oxidizing cells. It is theorized that this transcellular metabolism occurs in vivo and provides a mechanism for controlling 5-oxo-ETE production by allowing it to occur or be augmented at sites were 5-lipoxygenase-containing cells congregate with cell types possessing 5-HEDH and favorable NADPH/NADP+ ratios; such sites, it is theorized, might include those involving allergy, inflammation, oxidative stress, and rapidly growing cancers.
Sources: en.wikipedia.org
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.
The first four residues of Selank reproduce the tuftsin sequence Thr-Lys-Pro-Arg. A Pro-Gly-Pro extension at the C-terminus was added to slow enzymatic breakdown and extend residence time.
It holds marketing authorization in Russia, where nasal drop formulations are sold. No equivalent approval exists in the European Union, the United States, or most other countries.
Reports describe modulation of GABA signalling, changes in monoamine turnover and effects on neurotrophic factor expression. These observations come mainly from animal and cell studies. A single unifying mechanism has not been demonstrated.