BDNF 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 2025-09-15. Numbers and descriptions here follow the published literature rather than marketing material.
Handling follows standard practice for research peptides. Material is weighed in a low-humidity environment because the powder absorbs atmospheric moisture. Purity is reported as the percentage area of the main peak in a chromatogram, with specifications commonly set at 95 percent or higher; values below that threshold indicate the presence of truncated or modified species. Residual trifluoroacetate from purification is often present and may affect mass balance. Certificates of analysis should state the analytical method, the column and gradient used, and the lot-specific retention time so that results can be compared across suppliers.
Identity and purity of selank are established with reversed-phase high-performance liquid chromatography coupled to mass spectrometry. The peptide elutes from C18 columns with acetonitrile gradients in water containing trifluoroacetic acid or formic acid, and detection is usually performed by ultraviolet absorbance near 214 nm. Electrospray ionization in positive mode gives a doubly protonated ion near m/z 377, consistent with a mass of about 752 Da. Amino acid analysis or tandem mass spectrometry of fragment ions confirms the sequence. Because the molecule has no aromatic residues, it lacks a usable 280 nm chromophore, so low-wavelength detection or mass spectrometry is required.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Identity confirmation | Reversed-phase HPLC retention time versus reference standard | Retention depends on column, gradient, and ion-pairing agent |
| Mass confirmation | Electrospray or MALDI mass spectrometry | Doubly protonated ion near m/z 377 is consistent with about 752 Da |
| Typical purity specification | 95 percent or higher by chromatographic peak area | Lower values suggest truncated or modified peptide species |
| Storage of lyophilized powder | -20 °C, desiccated, protected from light | Powder tolerates long storage better than solution |
| Storage of solution | 2-8 °C for short periods | Freeze-thaw cycling promotes aggregation and surface adsorption |
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.
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.
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.
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.
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 citation description "For exceptionally meritorious conduct in the performance of outstanding services to the Government of the United States from June 1944 to August 1945. He has made an essential contribution to Pan-American Solidarity in further strengthening the bond and understanding between the United States of America and Ecuador. Under his able guidance and direction, the Navy of Ecuador, cooperating with the Armed Forces of the United States, assisted in consolidating Western Hemispheric Defense during the critical period of the war." In 1948, then Brigadier General John Frederick Boyce Combe was made an Officer of the Legion for his contribution "to the over-all success Allied forces in Italy" during World War II. In 1948, Air Chief Marshal Donald Perera VSV, USP, Sri Lanka Air Force. In 1950 Air Commodore Leonard Birchall (Royal Canadian Air Force) was made an officer of the Legion for his life imperiling heroic actions as a Japanese POW in WWII: "His exploits became legendary throughout Japan and brought renewed faith and strength to many hundreds of ill and disheartened prisoners." – U.S. President Harry S. Truman. In 1953, The President of the United States of America, authorized by Act of Congress, 20 July 1942, takes pleasure in presenting the Legion of Merit, in the Degree of Officer to Major General [then Brigadier General] Ham Byong Sun, Republic of Korea Army, for exceptionally meritorious conduct in the performance of outstanding services to the Government of the United States from 28 April 1951 to 3 April 1952.
=== South Africa === The species has been protected in South Africa since 1991; with laws banning both deliberate killing and selling. In the province of KwaZulu-Natal (KZN), the KwaZulu-Natal Sharks Board employs nets around protected beaches to mitigate the risk of shark attacks, though these are excluded from major aggregation sites. Population estimates have varied: a 1996 study estimated an average of 1,279 individuals between 1989 and 1993, while a 2004 study suggested the population had grown to 1,953 post-protection. A 2023 study concluded that white shark numbers off South Africa have remained stable since 1991, despite declines in sightings at Western Cape. Researchers suggested the population may be shifting eastward, potentially in response to orca predation. However, these findings are disputed; in 2024, it was noted that white shark catches in KZN have actually declined since 2010, casting doubt on the theory of an eastward migration.
=== Underwater work === Chainsaws are used for underwater cutting by professional divers. They are usually driven by hydraulic power supplied from the surface and operated by commercial divers using surface-supplied diving equipment. Underwater chainsaw cutting may also be used by public safety divers. Hydraulic chainsaws can be used to cut wood, concrete, brick and steel if the appropriate chain is used. Underwater cutting may be done in conditions of moving water and low visibility, which can increase risk, and appropriate safety precautions and suitable procedures are required for safety. Underwater wood structures may include bridge pilings, pier, and dock timbers. Chain saws generally include an interlocking safety trigger with hand guard.
Ferran Adrià began his culinary career in 1980 during his stint as a dishwasher at the Hotel Playafels, in the town of Castelldefels. The chef de cuisine at this hotel taught him traditional Spanish cuisine. At 19 he was drafted into military service where he worked as a cook. In 1984, at the age of 22, Adrià joined the kitchen staff of elBulli as a line cook. Eighteen months later he became the head chef. In 1994, Ferran Adrià and Juli Soler (his partner) sold 20% of their business to Miquel Horta (a Spanish millionaire and philanthropist and son of the founder of Nenuco) for 120 million pesetas. This event became a turning point for elBulli, the money was used to finance an expansion of the kitchen and the relationship with Horta opened the door to new clients, businessmen, and politicians who helped spread the word about the creative experimentation happening at the time in Cala Montjoi. Along with British chef Heston Blumenthal, Adrià is often associated with "molecular gastronomy", although like Blumenthal the Spanish chef does not consider his cuisine to be of this category. Instead, he has referred to his cooking as deconstructed cuisine. He defines the term as 'Taking a dish that is well known and transforming all its ingredients, or part of them; then modifying the dish's texture, form and/or its temperature. Deconstructed, such a dish will preserve its essence... but its appearance will be radically different from the original's.' His stated goal is to "provide unexpected contrasts of flavour, temperature and texture. Nothing is what it seems.
=== EC 2.8.3: CoA-transferases === EC 2.8.3.1: propionate CoA-transferase EC 2.8.3.2: oxalate CoA-transferase EC 2.8.3.3: malonate CoA-transferase EC 2.8.3.4: deleted EC 2.8.3.5: 3-oxoacid CoA-transferase EC 2.8.3.6: 3-oxoadipate CoA-transferase EC 2.8.3.7: The activity is due to two enzymes, EC 2.8.3.22, succinyl-CoA—L-malate CoA-transferase and EC 2.8.3.20, succinyl-CoA—Dcitramalate CoA-transferase EC 2.8.3.8: acetate CoA-transferase EC 2.8.3.9: butyrate—acetoacetate CoA-transferase EC 2.8.3.10: citrate CoA-transferase EC 2.8.3.11: citramalate CoA-transferase EC 2.8.3.12: glutaconate CoA-transferase EC 2.8.3.13: succinate—hydroxymethylglutarate CoA-transferase EC 2.8.3.14: 5-hydroxypentanoate CoA-transferase EC 2.8.3.15: succinyl-CoA:(R)-benzylsuccinate CoA-transferase EC 2.8.3.16: formyl-CoA transferase EC 2.8.3.17: cinnamoyl-CoA:phenyllactate CoA-transferase EC 2.8.3.18: succinyl-CoA:acetate CoA-transferase EC 2.8.3.19: CoA:oxalate CoA-transferase EC 2.8.3.20: succinyl-CoA—D-citramalate CoA-transferase EC 2.8.3.21: L-carnitine CoA-transferase EC 2.8.3.22: succinyl-CoA—L-malate CoA-transferase EC 2.8.3.23: caffeate CoA-transferase EC 2.8.3.24: (''R'')-2-hydroxy-4-methylpentanoate CoA-transferase EC 2.8.3.25: bile acid CoA-transferase EC 2.8.3.26: succinyl-CoA:mesaconate CoA transferase
Sources: en.wikipedia.org
In 2024, the Safeguarding National Security Ordinance was passed by the Legislative Council to grant officials the power to prosecute crimes such as treason and insurrection. Critics state that this expansion will give more powers to crack down on opposition to the central government of China and the Hong Kong government as well as strike a lasting blow to the partial autonomy China had promised the city in the Sino-British Joint Declaration.
== Terminology == In the United Kingdom, the name or names of the fruit followed by juice can only legally be used to describe a product that is 100% fruit juice, as required by the Fruit Juices and Fruit Nectars (England) Regulations and the Fruit Juices and Fruit Nectars (Scotland) Regulations 2003. However, a juice made by reconstituting concentrate can be called juice. A product described as fruit "nectar" must contain at least 25% to 50% juice, depending on the fruit. A juice or nectar including concentrate must state that it does. The term "juice drink" is not defined in the Regulations and can be used to describe any drink that includes juice, whatever the amount. Comparable rules apply in all EU member states in their respective languages. In the US, fruit juice can only legally be used to describe a product that is 100% fruit juice. A blend of fruit juice(s) with other ingredients, such as high-fructose corn syrup, is called a juice cocktail or juice drink. According to the Food and Drug Administration (FDA), the term "nectar" is generally accepted in the US and in international trade for a diluted juice to denote a beverage that contains fruit juice or puree, water, and artificial sweeteners. "No added sugar" is commonly printed on the labels of juice containers, but the products may contain large amounts of naturally occurring sugars; however, sugar content is listed with other carbohydrates on labels in many countries.
He finds himself struggling and juggling the two separate worlds. Mwas finally meets his cousin again, who ends up forcing him to steal a car in order to clear his debt. He convinces the gang to move up from stealing parts to stealing cars in order to earn more. Carjacking proved to be a very dangerous activity after the first attempt ended up with Mwas and a fellow gang member of Oti's gang being injured in a fight at the meeting place. Later on, the carjackings are successful, yielding profits that the members share with each other. A misunderstanding breaks out between Oti's gang and the other one run by a gang leader that ultimately leads to the death of the latter, who died by being impaled by a sharp object when Mwas started confronting him. This attracts the attention of the police, and the two parties are arrested, but two corrupt law enforcement officers single out Oti's crew and take them to a secret location that seems abandoned. It was a site of execution to rub off the traces of unsolved Nairobi Crimes. A skirmish erupts, leading to the wipeout of the whole crew, but Mwas survives. During that time, he falls in love with Oti's onscreen love interest, Amina, coming to see her at the lodgings at which she receives customers and even taking her out to the films.
AtPEPs have been shown to affect resistance against oomycetes and may allow A. thaliana to distinguish between different pathogens. In Nicotiana attenuata, some of the peptides have stopped being involved in defensive roles and instead affect flower morphology.
The reaction interconverts the nucleotide, guanosine monophosphate (GMP) and guanosine diphosphate (GDP) by transferring a phosphate group from the cofactor, adenosine triphosphate (ATP), which is converted to adenosine diphosphate (ADP). The enzyme has very widespread occurrence, for example in L cells, Escherichia coli, rat liver, and calf thymus. Guanylate kinase is essential for recycling GMP and indirectly, cGMP. In prokaryotes (such as Escherichia coli), lower eukaryotes (such as yeast) and in vertebrates, it is a highly conserved monomeric protein of about 200 amino acids which has been shown to be structurally similar to protein A57R (or SalG2R) from various strains of Vaccinia virus. Systems biology analyses carried out by the team of Andreas Dräger also identified a pivotal role of this enzyme in the replication of SARS-CoV-2 within the human airways.
Sources: en.wikipedia.org
=== Wirtz-Conklin === The Wirtz-Conklin stain is a special technique designed for staining true endospores with the use of malachite green dye as the primary stain and safranin as the counterstain. Once stained, they do not decolourize. The addition of heat during the staining process is a huge contributing factor. Heat helps open the spore's membrane so the dye can enter. The main purpose of this stain is to show germination of bacterial spores. If the process of germination is taking place, then the spore will turn green in color due to malachite green and the surrounding cell will be red from the safranin. This stain can also help determine the orientation of the spore within the bacterial cell; whether it being terminal (at the tip), subterminal (within the cell), or central (completely in the middle of the cell).
Instead of in the liquid phase, the dehydrochlorination may also be carried out in the gas phase on a zinc chloride impregnated catalyst in a fluidized bed reactor at 350-500 °C. The seemingly simple reaction yields only 70 to 80% of impure end product due to a variety of side reactions. For example, in the chlorination of ethylene carbonate in substance or solution, 2-chloroacetaldehyde, polychlorinated ethylene carbonate and chlorinated ring-opening products are formed besides others. The separation of the by-products from the final product by distillation by thin-film evaporator, fractional recrystallization or zone melting is very expensive. The content of by-products can be reduced by stirring with sodium borohydride or urea at elevated temperature. However, the purification is complicated by the pronounced thermolability of vinylene carbonate, as it decomposes at temperatures above 80 °C within minutes. Highly pure vinylene carbonate can be obtained in yields of more than 70% by optimizing the chlorination conditions to suppress the formation of by-products and a combination of several gentle purification processes. The tendency of the liquid vinylene carbonate to polymerize is suppressed by addition of inhibitors such as butylhydroxytoluene (BHT).
Superacids can permanently protonate water to give ionic, crystalline hydronium "salts". They can also quantitatively stabilize carbocations. While Ka measures the strength of an acid compound, the strength of an aqueous acid solution is measured by pH, which is an indication of the concentration of hydronium in the solution. The pH of a simple solution of an acid compound in water is determined by the dilution of the compound and the compound's Ka.
==== Assessments ==== Heseltine was not popular with his ministerial peers at this time. A story was told of how ministers had volunteered him to be the one "taken hostage by terrorists" in a mooted training exercise. Nonetheless, Heseltine emerged from the Heath government with an enhanced reputation. He had avoided the worst crises of that government: the two miners' strikes, incomes policy, industrial relations policy and Northern Ireland, as well as any direct involvement in British entry into the EEC. Heseltine's career under Heath's ministry saw him associated with local government reorganisation, prestige projects, Europe and state aid to industries, themes which would recur throughout his career. He had attained a higher public profile than many Cabinet ministers, and by 1974 he was being seriously tipped as a future prime minister. Heseltine was promoted to the Shadow Cabinet in June 1974 as Industry spokesman. If the Conservatives had won either of the general elections in 1974 (February or October) he would almost certainly have joined the Cabinet. He was shadowing Tony Benn, who planned a major expansion of public ownership through the National Enterprise Board. In the summer of 1974, Heseltine put together a team of over 20 Conservative MPs, each a specialist in a particular industry, to campaign against Benn's plans.
Sources: en.wikipedia.org
Identity is confirmed by matching the retention time in reversed-phase chromatography against a reference standard and by measuring the molecular mass with mass spectrometry. Tandem mass spectrometry or amino acid analysis can verify the sequence of the seven residues. Because the peptide contains no aromatic amino acids, detection at 280 nm is not useful.
Lyophilized powder is normally stored desiccated at -20 °C, protected from light and moisture. Powder kept under these conditions is generally stable for long periods. Solutions are less stable and are usually prepared immediately before use.
A purity value from one chromatographic method does not capture every possible impurity. Related peptides with similar retention behavior, counterions, and residual solvents may not appear in the same analysis. Independent testing with an orthogonal method provides stronger assurance of identity and content.
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.