The short version of Intranasal route fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2026-02-27. Anything still debated is marked as such rather than presented as settled.
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.
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.
| 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.
== Work == Foyer researches plant growth regulation and development under optimal circumstances and in conditions of stress (caused by, for example, lack of water, low temperatures, high light, infestation by aphids). Her work has a special focus on how cellular reduction/oxidation (redox), homeostasis and signalling interact with phytohormone–mediated pathways, particularly involving abscisic acid, auxin and strigolactones. Her research is centered on ascorbate and glutathione as key regulators of plant responses to stress and on how redox processes associated with primary metabolism particularly photosynthesis and respiration regulate gene expression. The department addresses research problems of intrinsic scientific interest but is always mindful of the needs of agriculture and food security. In addition to undertaking fundamental studies on model plant species such as Arabidopsis thaliana, research in the Foyer lab includes work which relates the research findings, particularly in relation to enhancing stress tolerance, to crop species such as soybean, maize and barley.
=== Parvocellular neurosecretory neurons === The axons of the parvocellular neurosecretory neurons of the PVN project to the median eminence, a neurohemal organ at the base of the brain, where their neurosecretory nerve terminals release their hormones at the primary capillary plexus of the hypophyseal portal system. The median eminence contains fiber terminals from many hypothalamic neuroendocrine neurons, secreting different neurotransmitters or neuropeptides, including vasopressin, corticotropin-releasing hormone (CRH), thyrotropin-releasing hormone (TRH), gonadotropin-releasing hormone (GnRH), growth hormone-releasing hormone (GHRH), dopamine (DA) and somatostatin (growth hormone release inhibiting hormone, GIH) into blood vessels in the hypophyseal portal system. The blood vessels carry the peptides to the anterior pituitary gland, where they regulate the secretion of hormones into the systemic circulation. The parvocellular neurosecretory cells include those that make:
== Evolutionary Biology == The following tables compare the Homo sapiens FGFR1OP2 gene and protein to orthologs. In both of the following tables, the divergence from the Homo sapiens FGFR1OP2 gene or protein to the ortholog was found using TimeTree. Ortholog mRNA and protein sequences were found using NCBI's BLAST and UCSC's BLAT Tool. The accession numbers, as well as the sequence length and the sequence similarity were compiled using BLAST.
Sources: en.wikipedia.org
It is the heaviest doubly magic nuclide known. The four primordial isotopes of lead are all observationally stable, meaning that they are predicted to undergo radioactive decay but no decay has been observed yet. These four isotopes are predicted to undergo alpha decay and become isotopes of mercury which are themselves radioactive or observationally stable. There are trace quantities existing of the radioactive isotopes 209–214. The largest and most important is lead-210 as it has by far the longest half-life (22.2 years) and occurs in the abundant uranium decay series. Lead-211, -212, and -214 are present in the decay chains of uranium-235, thorium-232, and uranium-238, further, making these three lead isotopes also detectable in natural sources. The more minute traces of lead-209 arise from three rare decay branches: the beta-delayed-neutron decay of thallium-210 (in the uranium series), the last step of the neptunium series, traces of which are produced by neutron capture in uranium ores, and the very rare cluster decay of radium-223 (yielding also carbon-14). Lead-213 also occurs in a minor branch of the neptunium series. Lead-210 is particularly useful for helping to identify the ages of samples by measuring its ratio to lead-206 (both isotopes are present in a single decay chain). In total, 43 lead isotopes have been synthesized, from 178Pb to 220Pb.
== References == Hansard Indexes for 1993–2000, "Legislature of Western Australia" "No.32 (Special)". Western Australia Government Gazette. 16 February 1993. p. 1993:1287–1289. "No.116 (Special)". Western Australia Government Gazette. 25 August 1993. p. 1993:4599. "No.8 (Special)". Western Australia Government Gazette. 25 January 1994. p. 1994:278–279. "No.18 (Special)". Western Australia Government Gazette. 10 February 1995. p. 1995:477–478. "No.176 (Special)". Western Australia Government Gazette. 21 December 1995. p. 1995:6163–6164. "No.5 (Special)". Western Australia Government Gazette. 9 January 1997. p. 1997:99–100. Phillips, Harry; Black, David (June 1996). "Australian Political Chronicle: July–December 1995". Australian Journal of Politics and History. 42 (2): 271. ISSN 0004-9522.
(2026) reconstruct the evolutionary history of members of the genus Arvicola in Western Europe during the late Middle and Late Pleistocene on the basis of the study of morphology of teeth from the Lazaret Cave and Moula-Guercy sites (France), Abauntz Cave, Cova Eirós (Spain) and Trou Al'Wesse (Belgium), interpreted as consistent with a complex biogeographic history including multiple dispersals into Western Europe and subsequent local extinctions and recolonizations. New fossil material of members of the genus Byzantinia, providing new information on the morphology of teeth of members of this genus and their evolution, is described from the Miocene strata of the Zahleh Formation (Lebanon) by López-Antoñanzas et al. (2026). A study on the phylogenetic relationships and evolutionary history of extant and extinct hamsters is published by Dirnberger et al. (2026). Bujalska et al. (2026) reconstruct the evolutionary history of European small hamsters on the basis of mitochondrial genomes from Late Pleistocene and Holocene remains from Central and Western Europe, the Balkans and Anatolia, identifying evidence of presence of the winter white dwarf hamster in Central Europe during the Late Pleistocene. Pacheco-Castro, Carranza-Castañeda & Wang (2026) report the discovery of fossil material of Sigmodon minor from the Pliocene strata of the San Miguel de Allende Basin, representing the first record of the species from central Mexico and its southernmost known record in North America.
=== Wallets === A number of technologies known as wallets exist that store the key value pair of private and public key known as wallets. A wallet hosts the details of the key pair making cryptocurrency transactions possible. Multiple methods exist for storing keys or seeds in a wallet. A brainwallet or brain wallet is a type of wallet in which one memorizes a passcode (a private key or seed phrase). Brainwallets may be attractive due to plausible deniability or protection against governmental seizure, but are vulnerable to password guessing (especially large-scale offline guessing). Several hundred brainwallets exist on the Bitcoin blockchain, but most of them have been drained, sometimes repeatedly.
Sources: en.wikipedia.org
Normally pathogenic bacteria are weakened so they are no longer pathogenic. Commensal or food-grade bacteria which are not pathogenic. Using bacterial surface display of antigens is a valuable alternative to conventional vaccine design for various reasons, one of them being that the proteins expressed on the bacterial cell surface can act favourably as an adjuvant. Conventional vaccines require the addition of adjuvants. Another advantage of generating vaccines using bacterial display systems is that the whole bacterial cell can be incorporated in the live vaccine Unlike bacteriophage display systems which are generally used in vaccine development to find unknown epitopes, bacterial display systems are used to express known epitopes and the cells act as a vaccine delivery system. Under similar conditions, selection of bacterial-displayed peptides to model protein streptavidin proved worse.
The fission of one atom of uranium-235 releases 202.5 MeV (3.24×10−11 J) inside the reactor. That corresponds to 19.54 TJ/mol, or 83.14 TJ/kg. Another 8.8 MeV escapes the reactor as anti-neutrinos. When 23592U nuclei are bombarded with neutrons, one of the many fission reactions that it can undergo is the following (shown in the adjacent image):
Lactose intolerance is a lessened ability or a complete inability to digest lactose, a sugar found in dairy products. Humans vary in the amount of lactose they can tolerate before symptoms develop. Symptoms may include abdominal pain, bloating, diarrhea, flatulence, and nausea. These symptoms typically start thirty minutes to two hours after eating or drinking something containing lactose, with the severity typically depending on the amount consumed. Lactose intolerance does not cause damage to the gastrointestinal tract. Lactose intolerance is due to the lack of the enzyme lactase in the small intestines to break lactose down into glucose and galactose. There are four types: primary, secondary, developmental, and congenital. Primary lactose intolerance occurs as the amount of lactase declines as people grow up. Secondary lactose intolerance is due to injury to the small intestine. Such injury could be the result of infection, celiac disease, inflammatory bowel disease, or other diseases. Developmental lactose intolerance may occur in premature babies and usually improves over a short period of time. Congenital lactose intolerance is an extremely rare genetic disorder in which little or no lactase is made from birth. The reduction of lactase production starts typically in late childhood or early adulthood, and prevalence increases with age. Diagnosis may be confirmed if symptoms resolve following eliminating lactose from the diet. Other supporting tests include a hydrogen breath test and a stool acidity test.
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.