Intranasal route 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 2025-10-27. Numbers and descriptions here follow the published literature rather than marketing material.
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 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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Typical purity report | 95% or higher by HPLC | Area percentage at 214 nm |
| Identity confirmation | Mass spectrometry | Electrospray or MALDI |
| Powder storage | -20 C, desiccated | Protect from light |
| Solution storage | 2-8 C short term | Freeze aliquots for longer |
| Quality document | Certificate of analysis | States method and value |
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.
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.
Peptide bonds in selank are susceptible to hydrolysis under strongly acidic or basic conditions, and the terminal proline residues are vulnerable to exopeptidase activity in biological samples. Lyophilized powder stored dry at -20 °C typically remains stable for extended periods, whereas aqueous solutions degrade faster and may lose measurable purity within days to weeks depending on pH, temperature, and microbial load. Repeated freeze-thaw cycles promote aggregation and adsorption to container surfaces. For analytical work, solutions are usually prepared fresh, kept cold, and used within a single working day.
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.
Computational neuroscientists show that people with higher intelligence scores in HCP cognitive tests took more time to solve difficult problems and that their higher synchrony between brain areas allowed for better integration of evidence (or progress) from preceding working memory sub-problem processing. Reducing synchrony in "avatar" simulations, that were adjusted and tuned towards personalization, "led decision-making circuits to quickly jump to conclusions". Their codified results may be useful for an understanding of cognition to replicate or imitate in bio-inspired computing. Researchers report trends in reasons for HPV vaccine hesitancy during 2010–20. 24 May Scientists show how gene 'FAAH'-related disruption via genetic or epigenome editing can enable pain insensitivity (see also 10 March 2021). Their analyses, mainly about long non-coding RNA 'FAAH-OUT', following from decade-long study of a woman who can't feel pain or anxiety, could also enable novel therapeutic developments against other neurological problems. One of the first empirical studies on what real users are shown during their typical use of popular Web search engines interprets its results to show that choices for unreliable news sources for their queries are driven primarily by users' own choices and less by the engine's algorithms. The Web scientists link their findings to the concept of filter bubbles which emphasizes the role of design- and personalization algorithms.
=== Personal care and homecare === Surfactants are used in detergents, washing-up liquids, shampoos, shower gels, and similar products to increase the “solubility” of fat and dirt particles that adhere to laundry or the body in water. Fabric softeners can consist of cationic surfactants that prevent laundry from becoming stiff when dry.
If M1 and M2 are the midpoints of the diagonals AC and BD respectively in a tangential quadrilateral ABCD with incenter I, and if the pairs of opposite sides meet at J and K with M3 being the midpoint of JK, then the points M3, M1, I, and M2 are collinear. The line containing them is the Newton line of the quadrilateral. If the extensions of opposite sides in a tangential quadrilateral intersect at J and K, and the extensions of opposite sides in its contact quadrilateral intersect at L and M, then the four points J, L, K and M are collinear.
Sources: en.wikipedia.org
==== Antithrombin ==== Antithrombin is a serine protease inhibitor (serpin) that degrades the serine proteases: thrombin, FIXa, FXa, FXIa, and FXIIa. It is constantly active, but its adhesion to these factors is increased by the presence of heparan sulfate (a glycosaminoglycan) or the administration of heparins (different heparinoids increase affinity to FXa, thrombin, or both). Quantitative or qualitative deficiency of antithrombin (inborn or acquired, e.g., in proteinuria) leads to thrombophilia.
== Sunderland's classification == In 1951, Sunderland expanded Seddon's classification to five degrees. The first two are the same as Seddon's. With each degree, the severity of the injury increases and has larger structural disruption and poorer prognosis. Sunderland's third-degree and fourth-degree are included within Seddon's axonotmensis. Sunderland's third-degree is nerve fiber interruption. This includes an endoneurium lesion with disruption of the axon and endoneurium, but an intact epineurium and perineurium. Recovery from a third-degree injury may require surgical intervention due to misdirected regeneration that is caused by endoneurial damage. In fourth-degree injury, only the epineurium remain intact, and a complete block to axonal regeneration could occur, requiring surgical repair. Sunderland's fifth-degree is included within Seddon's neurotmesis. Fifth-degree lesion is a complete transection of the nerve, including the epineurium. Recovery requires appropriate surgical treatment since there is no spontaneous recovery expected.
== See also == Control of water pollution – Contamination of water bodies Clean Water Act – 1972 U.S. federal law regulating water pollution Peak water – Concept on the quality and availability of freshwater resources Pulsed-power water treatment – Using electro-magnetic fields on cooling water Solar water disinfection – Portable water purification powered by sunlight Raw water#Treatment – Untreated water found in a natural environment Water purification – Process of removing impurities from water Water quality – Assessment against standards for use Water softening – Removing positive ions from hard water Water supply – Provision of water by public utilities, commercial organisations or others
== Guinea Bissau == Manuel Serifo Nhamadjo – former interim president and former acting president of the National People's Assembly Brigadier-General Umaro Sissoco Embaló – President of Guinea-Bissau, former prime minister and Minister of African Affairs. Adiato Djaló Nandigna – Current Minister of Fisheries; former acting prime minister, former minister of culture, Youth and Sports and former minister of defense, Guinea Bissau Baciro Djá – former prime minister, former Minister of National Defense and former Minister of Youth and Sport, Guinea Bissau Eloïne Barry – communications professional and founder of African Media Agency. France, Guinea Bissau Fatumata Djau Baldé – Current Minister of Public Administration and State Modernization; former minister of foreign affairs, Guinea Bissau Mamadu Saliu Djaló Pires - Former foreign minister of Foreign Affairs. Mamadú Iaia Djaló – Current Minister of Trade and Industry, Guinea Bissau Tiago Djaló Yannick Djaló Alejandro Balde Mama Baldé Manuel Baldé
Sources: en.wikipedia.org
Purity is usually reported as an HPLC area percentage, most often measured at 214 nm. Identity is confirmed separately by mass spectrometry. A certificate of analysis should state both the method and the observed value.
Dry powder is kept frozen, desiccated, and shielded from light. Dissolved material is aliquoted and frozen to limit freeze-thaw cycles. Short-term refrigerated storage is common for working solutions.
Russia registers it as a prescription nasal product. Most other markets classify it as a research chemical with no approved medical use. Oversight of purity and labeling is consequently minimal in those markets.
The sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, written TKPRPGP in one-letter code. It combines the tetrapeptide tuftsin with a carboxyl-terminal Pro-Gly-Pro extension. This full sequence identifies the molecule more precisely than the research name.