Neurotrophic factor comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Updated 2025-08-11. Numbers and descriptions here follow the published literature rather than marketing material.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, frequently abbreviated as TKPRPGP. It was designed as a structural analogue of tuftsin, a naturally occurring tetrapeptide released by enzymatic cleavage of the immunoglobulin heavy chain. The two additional proline residues at the C-terminal end extend the parent chain and change how the molecule behaves in solution. The free peptide has a calculated molecular mass of approximately 751.9 g/mol and is generally supplied as a lyophilised white to off-white powder.
Development work on the compound began in the 1980s and 1990s at the Institute of Molecular Genetics in Moscow, within the same research programme that produced the peptide Semax. Early investigators sought a tuftsin derivative with improved resistance to enzymatic breakdown and with activity in the central nervous system after peripheral administration. Most of the primary literature from this period was published in Russian, a factor that still shapes how easily the findings can be checked by outside groups.
Naming for this compound is not fully standardised in English sources. The spelling Selanc appears in some transliterations, and catalogue entries may instead list the peptide sequence itself as the identifier. Reference material sometimes groups it with other short synthetic peptides studied for behavioural effects, which can create confusion when citations are compared. Distinguishing the exact sequence from related tuftsin analogues is therefore a practical first step when reviewing any dataset or specification sheet.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic heptapeptide | Tuftsin analogue |
| Sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Single-letter form: TKPRPGP |
| Molecular formula | C33H57N11O9 | Calculated for the free peptide |
| Molecular weight | About 751.9 g/mol | Derived from the sequence |
| Appearance | White to off-white powder | Typical lyophilised form |
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.
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 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.
Keratotomies are a group of corneal procedures. Radial keratotomy is a refractive surgery procedure where the surgeon makes a spoke-like pattern of incisions into the cornea to modify its shape. This early surgical option for myopia has been largely superseded by PRK, LASIK and other similar laser procedures. Laser surgery is usually contraindicated in keratoconus and other corneal thinning conditions, as removal of corneal stromal tissue will further damage an already thin and weak cornea. For similar reasons, radial keratotomy has also generally not been used for people with keratoconus. However, more modern and keratoconus-specific variants, such as Mini asymmetric radial keratotomy (MARK) and Circular keratotomy (CK), have been found to be useful in keratoconus management, particularly when combined with Corneal cross-linking.
== Awards and honors == Distinguished Mentor Award (University of Utah) 2019 University of Utah MUSE Professor 2019-ongoing Presidential Scholar Award (University of Utah) 2016–2019 Teva Pharmaceutical Scholar Award 2015–2018 Young Investigator Award, Metals in Medicine Gordon Conference 2012 Fellow of the American Association for the Advancement of Science 2023
The colony faced an uncertain future as the end of the New Territories lease approached, and Governor Murray MacLehose raised the question of Hong Kong's status with Deng Xiaoping in 1979. Diplomatic negotiations with China resulted in the 1984 Sino-British Joint Declaration, in which the United Kingdom agreed to the handover of the colony in 1997, and China would guarantee Hong Kong's economic and political systems for 50 years after the handover. The impending handover triggered a wave of mass emigration as residents feared an erosion of civil rights, the rule of law, and quality of life. Over half a million people left the territory during the peak migration period, from 1987 to 1996. The Legislative Council became a fully elected legislature for the first time in 1995. It extensively expanded its functions and organisations throughout the last years of the colonial rule. The handover of Hong Kong to China was at midnight on 1 July 1997, after 156 years of British rule. Immediately after the handover, Hong Kong was severely affected by several crises. The Hong Kong government was forced to use substantial foreign exchange reserves to maintain the Hong Kong dollar's currency peg during the 1997 Asian financial crisis, and the recovery from this was muted by an H5N1 avian-flu outbreak and a housing surplus. This was followed by the 2003 SARS epidemic, during which the territory experienced its most serious economic downturn. Chinese communists portrayed the return of Hong Kong as a key moment in the PRC's rise to great power status.
On 3 September 2021, the Supreme Court of Justice ruled that the president can serve two consecutive terms in office. The ruling overturned a 2014 ruling that presidents had to wait ten years to be eligible to run for re-election. Constitutional lawyers criticized the ruling, saying that consecutive re-election violates El Salvador's constitution. The 2021 ruling allowed Bukele to run for re-election in the 2024 presidential election. ARENA and the FMLN protested the court's ruling, with an ARENA spokesperson calling it a "precursor to a dictatorship" and an FMLN representative saying that the state is serving only one person: Bukele. The ruling was also condemned by the United States government. Jean Elizabeth Manes, chargé d'affaires of the United States to El Salvador, called it "clearly contrary to the Salvadoran constitution". According to Manes, the ruling was a direct result of the May 2021 legislative replacement of the Supreme Court justices.
Sources: en.wikipedia.org
=== Naturally occurring isotope variation === Natural processes result in broad variations in the D/H ratio (DHR) in different pools of hydrogen. KIEs and physical changes such as precipitation and evaporation lead to these observed variations. Seawater varies slightly, between 0 and −10 per mil, while atmospheric water can vary between about −200‰ to +100‰. Biomolecules synthesized by organisms, retain some of the D/H signature of the water which they were grown on, plus a large fractionation factor which can be as great as several hundred ‰. Large D/H differences, of thousands of ‰, can be found between Earth and other planetary bodies such as Mars, likely due to variations in isotope fractionation during planet formation and the loss of hydrogen into space.
== Acceptable levels of consumption == The acceptable daily intake (ADI) value for food additives, including aspartame, is defined as the "amount of a food additive, expressed on a body weight basis, that can be ingested daily over a lifetime without appreciable health risk". The Joint FAO/WHO Expert Committee on Food Additives (JECFA) and the European Commission's Scientific Committee on Food (later becoming EFSA) have determined this value is 40 mg/kg of body weight per day for aspartame, while the FDA has set its ADI for aspartame at 50 mg/kg per day – an amount equated to consuming 75 packets of commercial aspartame sweetener per day to be within a safe upper limit. The primary source for exposure to aspartame in the US is diet soft drinks, though it can be consumed in other products, such as pharmaceutical preparations, fruit drinks, and chewing gum among others in smaller quantities. A 12-US-fluid-ounce (350 ml; 12 imp fl oz) can of diet soda contains 0.18 grams (0.0063 oz) of aspartame, and, for a 75-kilogram (165 lb) adult, it takes approximately 21 cans of diet soda daily to consume the 3.7 grams (0.13 oz) of aspartame that would surpass the FDA's 50 mg/kg of body weight ADI of aspartame from diet soda alone. Studies of aspartame consumption in the US, Europe, Australia and other countries have shown that even high levels of intake are well below the ADI for safe consumption.
=== 2011 === On May 19, 2011, Sharp in collaboration with NHK demonstrated a direct-view 85 inches (220 cm) LCD capable of 7680 × 4320 pixels at 10 bits per channel. It was the first direct-view Super Hi-Vision-compatible display released. Before 2011, UHDTV allowed for frame rates of 24, 25, 50, and 60 fps. In an ITU-R meeting during 2011, an additional frame rate was added to UHDTV of 120 fps.
== Human and mouse genes == The genes encoding human 5-HT3 receptors are located on chromosomes 11 (HTR3A, HTR3B) and 3 (HTR3C, HTR3D, HTR3E), so it appears that they have arisen from gene duplications. The genes HTR3A and HTR3B encode the 5-HT3A and 5-HT3B subunits and HTR3C, HTR3D and HTR3E encode the 5-HT3C, 5-HT3D and 5-HT3E subunits. HTR3C and HTR3E do not seem to form functional homomeric channels, but when co-expressed with HTR3A they form heteromeric complex with decreased or increased 5-HT efficacies. The pathophysiological role for these additional subunits has yet to be identified. The human 5-HT3A receptor gene is similar in structure to the mouse gene which has 9 exons and is spread over ~13 kb. Four of its introns are exactly in the same position as the introns in the homologous α7-acetylcholine receptor gene, clearly showing their evolutionary relationship.
==== Constituents ==== A 2013 review described sulfated polysaccharides synthesized by 120 marine microalgae, most of which are EPS. These heteropolymers consist mainly of galactose, glucose, and xylose in different proportions except those from Gyrodinium impudicum, which are homopolymers. Most EPS from cyanobacteria are also complex anionic heteropolymers containing six to ten different monosaccharides, one or more uronic acids, and various functional substituents such as methyl, acetate, pyruvate, sulfate groups, and proteins. For instance, the EPS from Arthrospira platensis are heteropolymer with protein (55%) moieties and a complex polysaccharide composition, containing seven neutral sugars: glucose, rhamnose, fructose, galactose, xylose, arabinose, and mannose, as well as two uronic acids, galacturonic acid and glucuronic acid. Dunaliella salina is a unicellular green alga of outstanding halotolerance. Salt stress induces the secretion of extracellular polymeric substances from D. salina. It is speculated that the release of complex mixtures of macromolecular polyelectrolytes with high polysaccharide content contributes to the survival strategy of D. salina in varying salt concentrations. Four monosaccharides (galactose, glucose, xylose, and fructose) were detected in the hydrolysate of EPS from D. salina under salt stress. In contrast, the water-soluble polysaccharides released by Chlorella pyrenoidosa contain galactose, arabinose, mannose, ribose, xylose, fucose, and rhamnose; their release depends on the cell photosynthetic activity and reproductive state.
Sources: en.wikipedia.org
Ammunition and other resources are generally placed in locations appropriate to the environment rather than appearing as arbitrary pickups; contemporary reviewers noted that weapons, ammunition, and health supplies were integrated into the surrounding world to reinforce the game's sense of realism. The game frequently combines combat with environmental puzzles. These challenges can involve operating machinery, navigating conveyor systems, manipulating movable objects, finding alternative routes, or using environmental hazards against enemies. For example, the player can manipulate valves to release dangerous steam, while boxes and other objects can be arranged to create paths to otherwise inaccessible areas. These puzzles are generally presented as problems within the environment rather than as explicitly marked challenges, requiring the player to observe the surroundings and determine an appropriate solution. Enemy encounters are similarly integrated into the environment. The player encounters a variety of alien organisms, including headcrabs, bullsquids, Vortigaunts, and headcrab zombies, as well as human opponents such as military soldiers and Black Ops assassins. Human enemies were noted for their use of coordinated behavior and tactical responses, while different alien species possess distinct methods of attacking the player. Valve demonstrated AI features such as fear and group behavior during the game's development, contributing to encounters in which enemies could react to the player's actions rather than simply attacking from predetermined positions.
SA biosynthesis is increased via isochorismate synthase (ICS) and phenylalanine ammonia-lyase (PAL) pathway in plastids. It was observed that during plant-microbe interactions, as part of the defense mechanisms, SA is initially accumulated at the local infected tissue and then spread all over the plant to induce systemic acquired resistance at non-infected distal parts of the plant. Therefore with increased internal concentration of SA, plants were able to build resistant barriers for pathogens and other adverse environmental conditions.
Malaya, officially the Federation of Malaya, was a country in Southeast Asia from 1948 to 1963. It succeeded the Malayan Union and, before that, British Malaya. It comprised eleven states – nine Malay states and two of the Straits Settlements, Penang and Malacca. It was established on the 1st of February 1948. Initially a self-governing colony of the United Kingdom, Malaya became fully sovereign on 31 August 1957, and on 16 September 1963, the federation was superseded by Malaysia when it united with Singapore, North Borneo (Sabah) and Sarawak. Singapore left on 9 August 1965, leaving the original states of Malaya along with Sarawak and Sabah – now collectively known as East Malaysia – to form modern-day Malaysia, while the former Federation of Malaya is now referred to as Peninsular Malaysia or West Malaysia.
Halliwell B; Gutteridge JM (1984). "Oxygen toxicity, oxygen radicals, transition metals and disease". Biochemical Journal. 219 (1): 1–14. doi:10.1042/bj2190001. PMC 1153442. PMID 6326753. Murphy MP, Bayir H, Belousov V, Chang CJ, Davies KJ, Davies MJ, Dick TP, Finkel T, Forman HJ, Gems D, Janssen-Heininger Y, Kagan VE, Kalyanaraman B, Larsson NG, Mile GL, Nyström T, Poulsen HE, Radi R, Remmen HV, Schumacker PT, Thornalley PJ, Toyokuni S, Winterbourn CC, Yin H, Halliwell B. (2022) Guidelines for measuring reactive oxygen species and oxidative damage in cells and in vivo. Nature Metabolism 4, 651–662. Research articles
Another film purported to have been the highest-grosser is the 1972 pornographic film Deep Throat. In 1984, Linda Lovelace testified to a United States Senate Judiciary Subcommittee on juvenile justice that the film had earned $600 million; this figure has been the subject of much speculation, since if it is accurate then the film would have made more money than Star Wars, and finished the 1970s as the highest-grossing film. The main argument against this figure is that it simply did not have a wide enough release to sustain the sort of sums that would be required for it to ultimately gross this amount. Exact figures are not known, but testimony in a federal trial in 1976—about four years into the film's release—showed the film had grossed over $25 million. Roger Ebert has reasoned it possibly did earn as much as $600 million on paper, since mobsters owned most of the adult movie theaters during this period and would launder income from drugs and prostitution through them, so probably inflated the box-office receipts for the film. The Birth of a Nation, Gone with the Wind, The Godfather, Jaws, Star Wars, E.T., and Avatar all increased their record grosses with re-releases. The grosses from their original theatrical runs are included here along with totals from re-releases up to the point that they lost the record; therefore the total for The Birth of a Nation includes income from its reissues up to 1940; the total for Star Wars includes revenue from the late 1970s and early 1980s reissues but not from the 1997 Special Edition; the total for E.T.
Sources: en.wikipedia.org
The sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, commonly written as TKPRPGP. It shares the first four residues with tuftsin and carries three prolines in the chain. The proline-rich tail is the main structural feature that separates it from the parent tetrapeptide.
Selank is a synthetic analogue built on the tuftsin tetrapeptide Thr-Lys-Pro-Arg. Extra proline residues were added to the C-terminus during design work. That modification is intended to make the peptide less vulnerable to rapid enzymatic degradation.
Transliteration from Russian produces variant spellings such as Selanc. Many suppliers avoid the trade-style name entirely and list the peptide sequence. Comparing sequences rather than names is the reliable way to confirm two entries describe the same molecule.
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.