A practical reference on TKPRPGP: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2026-07-10. Anything still debated is marked as such rather than presented as settled.
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.
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.
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.
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.
| 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 |
Selank is a synthetic heptapeptide developed in Russia during the 1990s. Researchers at the Institute of Molecular Genetics of the Russian Academy of Sciences designed it as a stabilized analog of tuftsin, a naturally occurring immunomodulatory tetrapeptide. The compound has been studied primarily for its reported anxiolytic and nootropic effects. It remains largely unknown in Western pharmacology and is not approved as a medicine by major regulators such as the FDA or the EMA.
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.
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.
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.
Proposed mechanisms centre on the GABAergic system. Animal and tissue studies report changes in GABA-A receptor expression and reduced activity of GABA transaminase, the enzyme that degrades GABA. Effects on monoamine turnover, including serotonin and dopamine pathways, are also described, and a separate line of work links the peptide to increased expression of brain-derived neurotrophic factor in hippocampal tissue. Most of these findings come from rodent models and cell preparations. How the individual observations combine into a single coherent mode of action is not settled.
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.
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.
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.
Arthrospira species are free-floating, filamentous cyanobacteria characterized by cylindrical, multicellular trichomes in an open left-handed helix. They occur naturally in tropical and subtropical lakes with high pH and high concentrations of carbonate and bicarbonate. A. platensis occurs in Africa, Asia, and South America, whereas A. maxima is confined to Central America. Most cultivated spirulina is produced in open-channel raceway ponds, with paddle wheels used to agitate the water. Spirulina thrives at a pH around 8.5 and above and a temperature around 30 °C (86 °F). They are autotrophic, and do not need a living energy or organic carbon source.
Argon (18Ar) has 26 known isotopes, from 29Ar to 54Ar, of which three are stable (36Ar, 38Ar, and 40Ar). On Earth, 40Ar makes up 99.6% of natural argon. The longest-lived radioactive isotopes are 39Ar with a half-life of 302 years, 42Ar with a half-life of 32.9 years, and 37Ar with a half-life of 35.01 days. All other isotopes have half-lives of less than two hours, and most less than one minute. Isotopes lighter than 38Ar decay to chlorine or lighter elements, while heavier ones beta decay to potassium. The naturally occurring 40K, with a half-life of 1.248×109 years, decays to stable 40Ar by electron capture (10.72%) and by positron emission (0.001%), and also to stable 40Ca via beta decay (89.28%). These properties and ratios are used to determine the age of rocks through potassium–argon dating. Despite the trapping of 40Ar in many rocks, it can be released by melting, grinding, and diffusion. Almost all argon in the Earth's atmosphere is the product of 40K decay, since 99.6% of Earth's atmospheric argon is 40Ar, whereas in the Sun and presumably in primordial star-forming clouds, argon consists of ~85% 36Ar, ~15% 38Ar and only trace 40Ar. Similarly, the ratio of the isotopes 36Ar:38Ar:40Ar in the atmospheres of the outer planets is measured to be 8400:1600:1. In the Earth's atmosphere, radioactive 39Ar (and to a lesser extent 37Ar) is made by cosmic ray activity, primarily from 40Ar.
=== Fermentation-produced chymosin === Because of the above imperfections of microbial and animal rennets, many producers sought other replacements of rennet. With genetic engineering it became possible to isolate rennet genes from animals and introduce them into certain bacteria, fungi, or yeasts to make them produce recombinant chymosin during fermentation. The genetically modified microorganism is killed after fermentation and chymosin isolated from the fermentation broth, so that the fermentation-produced chymosin (FPC) used by cheese producers does not contain a GMO or any GMO DNA. FPC is identical to chymosin made by an animal, but is produced in a more efficient way. FPC products have been on the market since 1990 and, because the quantity needed per unit of milk can be standardized, are commercially viable alternatives to crude animal or plant rennets, as well as generally preferred to them in industrial production. Originally created by biotechnology company Pfizer, FPC was the first artificially-produced enzyme to be registered and allowed by the US Food and Drug Administration. In 1999, about 60% of US hard cheeses were made with FPC, which thereafter made up to 80% of the global market share for rennet. By 2017, FPC had 90% of the global market share for rennet. By 2021, animal rennet still found use in some traditional or designated European cheeses but FPC covered 80-90% of the market in the US and UK. The most widely used FPC is produced either by the fungus Aspergillus niger and commercialized under the trademark CHY-MAX by the Danish company Chr.
=== Vestibule === The vestibule is the area between the labia minora, where the vaginal introitus and the urinary meatus - the openings of the vagina and urethra respectively - are located. The meatus is below the clitoris and atop the introitus. The introitus is sometimes partly covered by a membrane called the hymen. The hymen will usually rupture during the first episode of vigorous sex, and the blood produced by this rupture has been seen to signify virginity. However, the hymen may also rupture spontaneously during exercise or be stretched by normal activities such as the use of tampons and menstrual cups, or be so minor as to be unnoticeable, or be absent. In some rare cases, the hymen may completely cover the introitus, requiring a surgical procedure called a hymenotomy. Two greater vestibular glands known as Bartholin's glands open into either side of the introitus and secrete a mucous vaginal lubricant. The openings of the lesser vestibular glands, known as Skene's glands, are found on either side of the urethral meatus.
Sources: en.wikipedia.org
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Disposal of plutonium waste from nuclear power plants and dismantled nuclear weapons built during the Cold War is a nuclear-proliferation and environmental concern. Other sources of plutonium in the environment are fallout from many above-ground nuclear tests, which are now banned.
Sources: en.wikipedia.org
== Pathophysiology == Nitrogen dioxide is sparingly soluble in water and on inhalation, it diffuses into the lung and slowly hydrolyzes to nitrous and nitric acid which causes pulmonary edema and pneumonitis leading to the inflammation of the bronchioles and pulmonary alveolus resulting from lipid peroxidation and oxidative stress. Mucous membrane is primarily affected along with type I pneumocyte and the respiratory epithelium. The generation of free radicals from lipid peroxidation results in irritation of the bronchioles and alveoli that causes rapid destruction of the respiratory epithelial cells. The overall reaction results in the release of fluid that causes pulmonary edema. Nitrogen dioxide poisoning may alter macrophage activity and immune function leading to susceptibility of the body to a wide range of infections, and overexposure to the gas may also lead to methemoglobinemia, a disorder characterized by a higher than normal level of methemoglobin (metHb, i.e., ferric [Fe3+] rather than ferrous [Fe2+] haemoglobin) in the blood. Methemoglobinemia prevents the binding of oxygen to haemoglobin causing oxygen depletion that could lead to severe hypoxia. If nitrogen dioxide poisoning is untreated, fibrous granulation tissue is likely to develop within the alveolar ducts, tiny ducts that connect the respiratory bronchioles to alveolar sacs, each of which contains a collection of alveoli (small mucus-lined pouches made of flattened epithelial cells). The overall reaction may cause an obstructive lung disease.
Social and economic factors such as population change and the growth of international markets also have an effect on the number of people purchasing theater tickets, along with audience demographics where some films sell a much higher proportion of discounted children's tickets, or perform better in big cities where tickets cost more. The measuring system for gauging a film's success is based on unadjusted grosses, mainly because historically this is the way it has always been done because of the practices of the film industry: the box-office receipts are compiled by theaters and relayed to the distributor, which in turn releases them to the media. Converting to a more representative system that counts ticket sales rather than gross is also fraught with problems because the only data available for older films are the sale totals. As the motion picture industry is highly oriented towards marketing currently released films, unadjusted figures are always used in marketing campaigns so that new blockbuster films can much more easily achieve a high sales ranking, and thus be promoted as a "top film of all time", so there is little incentive to switch to a more robust analysis from a marketing or even newsworthy point of view. Despite the inherent difficulties in accounting for inflation, several attempts have been made. Estimates depend on the price index used to adjust the grosses, and the exchange rates used to convert between currencies can also affect the calculations, both of which can have an effect on the ultimate rankings of an inflation adjusted list.
== Applications == BMP has been shown to remain stable, without breaking down, in high-heat pasteurization and sterilization conditions, making it possible for potential use for culinary purposes. Those advocating for the presence of BMP's flavor-enhancing umami taste report that its taste is similar to that of monosodium glutamate. Consequently, BMP possesses potential for large-scale commercialization in the food industry. However, the primary obstacle is the cost of mass production associated with the peptide. Currently, the main modes of production for specific flavor peptides such as BMP are chemical and enzymatic synthesis, both of which involve high production costs.
ORT is endorsed by the World Health Organization, United Nations Office on Drugs and Crime, and UNAIDS as effective at reducing injection, lowering risk for HIV/AIDS, and promoting adherence to antiretroviral therapy. Buprenorphine and methadone work by reducing opioid cravings, easing withdrawal symptoms, and blocking the euphoric effects of opioids via cross-tolerance, and in the case of buprenorphine, a high-affinity partial opioid agonist, also due to opioid receptor saturation.
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.
Reverse-phase HPLC is the usual method and gives a percentage purity value. Mass spectrometry then confirms the molecular mass. Together they provide a basic identity and purity profile for a lot.