blood-brain barrier raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
This page was last updated on 2025-09-23 and is reviewed periodically as new material appears.
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.
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.
| 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 |
Outside its country of origin the compound is generally handled as a research chemical rather than an approved medicine. No regulatory approval from the United States Food and Drug Administration or the European Medicines Agency has been granted for human use. Identity and purity are normally checked by reverse-phase high-performance liquid chromatography, with mass spectrometry used to confirm the molecular mass. Lyophilised material is stored cold and desiccated, and repeated freeze-thaw cycles are avoided.
Published work on this peptide almost always uses intranasal delivery, with drops or a spray applied to the nasal mucosa. Some animal experiments have used subcutaneous or intraperitoneal injection, and a smaller number have compared routes directly. Oral administration is not a focus of the literature, because short peptides of this size are broken down by digestive enzymes and cross intestinal barriers poorly. How much of an intranasal dose reaches the bloodstream intact in humans remains an open question.
Animal studies have examined behaviour in tests of anxiety, memory retention and stress response, and several report changes in neurotrophic or neurotransmitter-related markers. The human evidence base is much smaller, consisting mainly of short trials conducted in Russia with limited reporting in English-language journals. Sample sizes are modest and outcome measures vary between studies, so the findings are best described as preliminary. Independent replication under modern trial standards has not been widely reported.
The compound has a calculated molecular weight near 751.9 daltons and carries a net positive charge at physiological pH because of its arginine residue. It dissolves freely in water and in common aqueous buffers, and typically appears as a white or off-white lyophilized powder. The amide backbone makes the molecule susceptible to peptidases, which limits oral use and favors intranasal or parenteral routes. Nomenclature in the literature varies: the substance is also described by the sequence abbreviation TP-7 and by a Russian trade designation.
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.
Arsenic biochemistry is the set of biochemical processes that can use arsenic or its compounds, such as arsenate. Arsenic is a moderately abundant element in Earth's crust, and although many arsenic compounds are often considered highly toxic to most life, a wide variety of organoarsenic compounds are produced biologically and various organic and inorganic arsenic compounds are metabolized by numerous organisms. This pattern is general for other related elements, including selenium, which can exhibit both beneficial and deleterious effects. Arsenic biochemistry has become topical since many toxic arsenic compounds are found in some aquifers, potentially affecting many millions of people via biochemical processes.
=== Police withdrawal === Swelled by thousands of new recruits and an increasingly sophisticated arsenal of heavy weapons, PLAN undertook more direct confrontations with the security forces in 1973. Insurgent activity took the form of ambushes and selective target attacks, particularly in the Caprivi near the Zambian border. On the evening of 26 January 1973 a heavily armed group of about 50 PLAN insurgents attacked a police base at Singalamwe, Caprivi with mortars, machine guns, and a single tube, man portable rocket launcher. The police were ill-equipped to repel the attack and the base soon caught fire due to the initial rocket bombardment, which incapacitated both the senior officer and his second in command. This marked the beginning of a new phase of the South African Border War in which the scope and intensity of PLAN raids were greatly increased. By the end of 1973, PLAN's insurgency had engulfed six regions: Caprivi, Ovamboland, Kaokoland, and Kavangoland. It also had successfully recruited another 2,400 Ovambo and 600 Lozi guerrillas. PLAN reports from late 1973 indicate that the militants planned to open up two new fronts in central South West Africa and carry out acts of urban insurrection in Windhoek, Walvis Bay, and other major urban centres. Until 1973, the South African Border War was perceived as a matter of law enforcement rather than a military conflict, reflecting a trend among Anglophone Commonwealth states to regard police as the principal force in the suppression of insurgencies.
mitochondrion (pl.) mitochondria; also formerly chondriosome. A highly pleiomorphic membrane-bound organelle found in the cytoplasm of nearly all eukaryotic cells, usually in large numbers in the form of sausage-shaped structures 5–10 micrometres in length, enclosed by a double membrane, with the inner membrane infolded in an elaborate series of cristae so as to maximize surface area. Mitochondria are the primary sites of ATP synthesis, where ATP is regenerated from ADP via oxidative phosphorylation, as well as many supporting pathways, including the citric acid cycle and the electron transport chain. Like other plastids, mitochondria contain their own genome encoded in circular DNA molecules which replicate independently of the nuclear genome, as well as their own unique set of transcription factors, polymerases, ribosomes, transfer RNAs, and aminoacyl-tRNA synthetases with which to direct transcription and translation of their genes. The majority of the structural proteins found in mitochondria are encoded by nuclear genes, however, such that mitochondria are only partially autonomous. These observations suggest mitochondria evolved from symbiotic prokaryotes living inside eukaryotic cells.
Romania is divided into 41 counties (județe) and the municipality of Bucharest. Each county is administered by a county council, responsible for local affairs, as well as a prefect responsible for the administration of national affairs at the county level. The prefect is appointed by the central government but cannot be a member of any political party. Each county is subdivided further into cities and communes, which have their own mayor and local council. There are a total of 320 cities and 2,861 communes in Romania. A total of 103 of the larger cities have municipality status, which gives them greater administrative power over local affairs. The municipality of Bucharest is a special case, as it enjoys a status on par to that of a county. It is further divided into six sectors and has a prefect, a general mayor (primar general), and a general city council. The NUTS-3 (Nomenclature of Territorial Units for Statistics) level divisions of the EU reflect Romania's administrative-territorial structure and correspond to the 41 counties plus Bucharest. The cities and communes correspond to the NUTS-5 level divisions, but there are no current NUTS-4 level divisions. The NUTS-1 (four macroregions) and NUTS-2 (eight development regions) divisions exist but have no administrative capacity and are used instead for coordinating regional development projects and statistical purposes.
Sources: en.wikipedia.org
== Research == From the beginning of his career Bengt Mannervik studied enzymes of glutathione metabolism, including studies of levels in different tissues, structure and catalytic activity of glutathione transferase, a purification method, a detailed review on the isoenzymes of glutathione transferase, and many others. These publications have had a major influence on the field of glutathione biochemistry. Each of those mentioned above, together with three others, had been cited more than 1000 times by the end of 2024, the first more than 5000 times, leading to an h index of 89, as calculated by Google Scholar. In all he has had nearly 600 publications, with a combined total of more than 47000 citations. His interest in glutathione transferases has continued after his retirement, for example studies of their role as efficient ketosteroid isomerases and as enzymes involved in the biosynthesis of moulting hormones in mosquitoes transmitting malaria and yellow fever. In addition to the work directed specifically at enzymes involved in glutathione metabolism and detoxication, Mannervik coauthored texts on molecular toxicology. He also studied various more general aspects of enzymology, including graphical analysis, error structure of kinetic experiments, weighting of observations, regression methods, directed enzyme evolution, and discrimination between models. Major contributions were more recently directed to the evolution of novel functions by in vitro protein evolution.
The analog of the poly-Pro II helix in poly-glycine is called the poly-Gly II helix. Some proteins, such as the antifreeze protein of Hypogastrura harveyi consist of bundles of glycine-rich polyglycine II helices. This remarkable protein, whose 3D structure is known, has unique NMR spectra and is stabilized by dimerization and 28 Cα-H··O=C hydrogen bonds. The PPII helix is not common in transmembrane proteins, and this secondary structure does not traverse lipid membranes in natural conditions. In 2018, a group of researchers from Germany experimentally observed the first transmembrane PPII helix formed by specifically designed artificial peptides.
=== Pancreatitis === The incorrect activation of proteolytic enzymes leads to edema, inflammation, and possible pancreas necrosis, causing acute pancreatitis. The most prominent cause of acute pancreatitis is gallstones. Permanent damage is possible from chronic pancreatitis due to progressive inflammation and the reoccurrence of acute pancreatitis. Acute pancreatitis is caused by mutations in a trypsinogen inhibitor, while a mutation in CFTR causes chronic pancreatitis. In fact, chronic pancreatitis often causes pancreatic adenocarcinoma.
== The Mkhedrioni after Gamsakhurdia == The Mkhedrioni played a crucial role in suppressing the remaining "Zviadists" after the downfall of Gamsakhurdia. Eduard Shevardnadze, a former Soviet foreign minister, was brought in to provide a respectable face for the new government, but it remained dependent on the Mkhedrioni: even inside the parliament building, Mkhedrioni gunmen had a constant presence as "bodyguards" for Jaba Ioseliani, who was now a member of parliament. Mkhedrioni were given the role of the interior forces under the new government. In 1993, worsening civil strife in Abkhazia prompted the Mkhedrioni and National Guard to launch a joint operation in the region to root out separatists and Gamsakhurdia supporters. This resulted in a disastrous defeat for the pro-government forces, who were driven out of Abkhazia along with virtually the entire ethnic Georgian population of the region: over 10,000 people were killed in the fighting. In September 1993, Gamsakhurdia took the opportunity to launch an armed uprising in western Georgia in an attempt to return to power. The Mkhedrioni played an important role in suppressing the uprising and were for a while given semi-official status as the "Georgian Rescue Corps". Russian intervention ensured Gamsakhurdia's defeat and on December 31 he reportedly committed suicide, though it has also been stated, and widely believed within Georgia, that he was murdered. Mkhedrioni forces were alleged in press reports to be responsible for his death, but they denied this.
Prevalence of hepatocellular carcinoma in individuals exposed to aflatoxin increases with co-infection of hepatitis B virus. One study estimated that while individuals with urinary aflatoxin bio-markers were at a threefold greater risk than the normal population for hepatocellular carcinoma; those infected with hepatitis B virus were at a fourfold risk; and those with the aflatoxin bio-markers and infected with hepatitis B virus were at a 60 times greater risk for hepatocellular carcinoma than the normal population.
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.
Reports describe modulation of GABA signalling, changes in monoamine turnover and effects on neurotrophic factor expression. These observations come mainly from animal and cell studies. A single unifying mechanism has not been demonstrated.