Everything below concerns certificate of analysis. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2026-05-24. Where a claim depends on a specific study, the study is described rather than over-claimed.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. Its four N-terminal residues reproduce tuftsin, a tetrapeptide fragment of the immunoglobulin heavy chain, while the C-terminal Pro-Gly-Pro extension is a synthetic addition. The peptide has a molecular mass near 752 daltons and carries a net positive charge at physiological pH because of the arginine and lysine side chains. Published indexes list it under the name Selank and the sequence abbreviation TKPRPGP. Solid-phase peptide synthesis is the standard production route for research quantities.
Development took place at the Institute of Molecular Genetics of the Russian Academy of Sciences, where a series of short peptides were designed in the 1980s and 1990s. Selank was selected from variants of tuftsin that showed resistance to plasma peptidases. Russian regulatory approval covers it as an anxiolytic agent given intranasally. Outside that market the compound is normally handled as a research chemical rather than a medicine, and no widely recognised international pharmacopoeial monograph exists. The name Selank is a coined trade designation rather than a systematic chemical name.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic heptapeptide | Tuftsin analogue with a C-terminal Pro-Gly-Pro tail |
| Amino acid sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Abbreviated TKPRPGP in most catalogues |
| Molecular mass | About 752 Da | Value for the free peptide |
| Solubility | Freely soluble in water | Aqueous solutions are kept cold and used promptly |
| Typical storage | -20 °C, dry, protected from light | Applies to the lyophilised powder before reconstitution |
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.
Measuring peptide exposure inside the brain is technically difficult. Selank is degraded rapidly in plasma, and assays must separate intact peptide from fragments, which favors targeted mass spectrometry over immunoassays alone. Reported half-lives are short, on the order of minutes, so effects observed hours later are attributed to downstream signaling rather than to the parent compound. Blood-brain barrier permeability is debated and rarely quantified directly. Gaps include absent dose-response characterization, inconsistent reporting of purity, and almost no pharmacokinetic data from human participants.
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.
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.
Selank is a synthetic heptapeptide developed in Russia. Its sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, a seven-residue chain built around the natural tetrapeptide tuftsin. Researchers at the Institute of Molecular Genetics of the Russian Academy of Sciences first described the compound in the mid-1990s. The design combined the tuftsin core with an added Pro-Gly-Pro tail, a modification intended to extend the molecule's stability in biological fluids. Published work on the peptide has appeared mainly in Russian-language journals.
Reported activity for Selank centers on anxiolytic and nootropic effects. Russian clinical reports describe use in anxiety and in cognitive or attention-related complaints. Most of this evidence comes from studies conducted by the same research groups that developed the peptide. Independent replication in other countries remains limited, and no major Western regulatory agency has approved the compound for any indication. The gap between local reports and external verification is a recurring point in discussions of the peptide.
Tuftsin, the parent structure, is a naturally occurring immunomodulatory tetrapeptide released from the Fc region of immunoglobulin G by spleen enzymes. Selank extends this four-residue sequence with three additional amino acids. The stated rationale is that the added tail slows enzymatic breakdown and may influence receptor interactions. How the full heptapeptide behaves at the molecular level is not firmly established, and proposed mechanisms often involve indirect modulation of neurotransmitter or immune signaling rather than a single defined target.
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.
== Protactinium-233 == Protactinium-233 is also part of the thorium fuel cycle. It is an intermediate beta decay product between thorium-233 (produced from natural thorium-232 by neutron capture) and uranium-233 (the fissile fuel of the thorium cycle). Some thorium-cycle reactor designs try to protect 233Pa from further neutron capture producing 234Pa and 234U, which are not useful as fuel.
Beyond its structural effects, intracrine Ang II has been shown to alter cardiac electrical conductivity, increasing the risk of arrhythmias. Intracellular dialysis of Ang II in cardiomyocytes has been observed to reduce junctional conductance and alter calcium signaling, which may contribute to the development of atrial fibrillation and other arrhythmias in conditions such as heart failure. Additionally, the ability of intracrine Ang II to modulate gap junctions and ion channels highlights its potential role in electrical remodeling of the heart. This mechanism may underlie the persistent electrical abnormalities seen in pathological cardiac conditions.
Over the years National Semiconductor acquired several companies like Fairchild Semiconductor (1987), and Cyrix (1997). However, over time National Semiconductor spun off these acquisitions. Fairchild Semiconductor became a separate company again in 1997, and the Cyrix microprocessors division was sold to VIA Technologies of Taiwan in 1999. From 1997 to 2002, National enjoyed a large amount of publicity and awards with the development of the Cyrix Media Center, Cyrix WebPad, WebPad Metro and National Origami PDA concept devices created by National's Conceptual Products Group. Based largely on the success of the WebPad, National formed the Information Appliance Division (highly integrated processors & "internet gadgets") in 1998. The Information Appliance Division was sold to AMD in 2003. Other businesses dealing in such products as digital wireless chipsets, image sensors, and PC I/O chipsets have also been recently closed down or sold off as National has reincarnated itself as a high-performance analog semiconductor company.
=== Articles === Rosen, DR; Siddique, T; Patterson, D; Figlewicz, DA; Sapp, P; Hentati, A; Donaldson, D; Goto, J; O'Regan, JP; Deng, HX; et al. (1993). "Mutations in Cu/Zn superoxide dismutase gene are associated with familial amyotrophic lateral sclerosis". Nature. 364 (6435): 362. Bibcode:1993Natur.364..362R. doi:10.1038/364362c0. PMID 8332197. Gusella, JF; Wexler, NS; Conneally, PM; Naylor, SL; Anderson, MA; Tanzi, RE; Watkins, PC; Ottina, K; Wallace, MR; Sakaguchi, AY; Young, AB; Shoulson, I; Bonilla, E; Martin, JB (1983). "A polymorphic DNA marker genetically linked to Huntington's Disease". Nature. 306 (5940): 234–238. Bibcode:1983Natur.306..234G. doi:10.1038/306234a0. PMID 6316146. S2CID 4320711. Tanzi, RE; Gusella, JF; Watkins, PC; Bruns, GAP; St; George-Hyslop, PH; Van Keuren, ML; Patterson, D; Pagan, S; Kurnit, DM; Neve, RL. (1987). "The amyloid beta protein gene: cDNA cloning, mRNA distribution, and genetic linkage near the Alzheimer locus". Science. 235 (4791): 880–884. Bibcode:1987Sci...235..880T. doi:10.1126/science.2949367. PMID 2949367. Tanzi, RE; McClatchey, AI; Lamperti, ED; V-Komaroff, L; Gusella, JF; Neve, R (1988). "Protease inhibitor domain encoded by an amyloid protein precursor mRNA associated with Alzheimer's disease". Nature. 331 (6156): 528–530. Bibcode:1988Natur.331..528T. doi:10.1038/331528a0. PMID 2893290. S2CID 4277294.
Sources: en.wikipedia.org
There is no disease-modifying treatments proven to cure Alzheimer's disease, and because of this, AD research has focused on interventions to prevent the onset and progression. There is no evidence that supports any particular measure in preventing AD, and studies of measures to prevent the onset or progression have produced inconsistent results. Epidemiological studies have proposed relationships between an individual's likelihood of developing AD and modifiable factors, such as medications, lifestyle, and diet. There are some challenges in determining whether interventions for AD act as a primary prevention method, preventing the disease itself, or a secondary prevention method, identifying the early stages of the disease. These challenges include duration of intervention, different stages of disease at which intervention begins, and lack of standardization of inclusion criteria regarding biomarkers specific for AD. Further research is needed to determine factors that can help prevent AD.
== History == The incidence of acute rheumatic fever and rheumatic heart disease is not declining. Recent figures quote the incidence of Acute Rheumatic Fever as 0.6–0.7/1,000 population in the United States and Japan compared with 15–21/1,000 population in Asia and Africa. The prevalence of Acute Rheumatic Fever and Sydenham's Chorea has declined progressively in developed countries over the last decades.
=== Sleep === Adenosine is a key factor in regulating the body's sleep-wake cycle. Adenosine levels build up in the brain during periods of wakefulness, causing a need to sleep when levels become too high, and lowers during periods of sleep, giving a sensation of restedness when waking. Higher adenosine levels correlate with a stronger feeling of sleepiness, also known as sleep drive or sleep pressure. Cognitive behavioral therapy for insomnia (CBT-I), which is considered one of the most effective treatments for insomnia, utilizes short-term sleep deprivation to raise and regulate adenosine levels in the body, for the intended promotion of consistent and sustained sleep in the long term. A principal component of cannabis delta-9-tetrahydrocannabinol (THC) and the endocannabinoid anandamide (AEA) induces sleep in rats by increasing adenosine levels in the basal forebrain. These components also significantly increase slow-wave sleep during the sleep cycle, mediated by CB1 receptor activation. These findings identify a potential therapeutic use of cannabinoids to induce sleep in conditions where sleep may be severely attenuated.
Sources: en.wikipedia.org
=== Selenium sulfide === Selenium sulfide slows down epidermal proliferation. It is fungicidal to Pityrosporum ovale. It also acts as a keratolytic. Selenium sulfide is also known to reduce dryness of scalp and folliculitis. Systemic toxicity can appear if it is applied to inflamed skin. Hypersensitivity reactions are noted in some people.
=== 1985 === February 6: The Reagan Doctrine commits the United States of America to supporting anti-Communist insurgencies in the Third World. March 10: General Secretary of the Communist Party of the Soviet Union Konstantin Chernenko dies. March 11: Mikhail Gorbachev becomes leader of the Soviet Union. March 15: Military rule ends in Brazil. March 24, 1985: Major Arthur D. Nicholson, a US Army Military Intelligence officer is shot to death by a Soviet sentry in East Germany. He is listed as the last US casualty in the Cold War. April 11: Enver Hoxha dies. Ramiz Alia takes over as First Secretary of the Party of Labor of Albania, becoming the de facto leader of Albania. April 22: The Trial of the Juntas convenes to prosecute the members of the National Reorganization Process (the military junta that governed Argentina from 1976 to 1983) for war crimes and crimes against humanity committed during its existence. May 20: John Anthony Walker is arrested by the FBI. August 6: Coinciding with the 40th anniversary of the atomic bombings of Hiroshima and Nagasaki, the Soviet Union begins what it has announced is a 5-month unilateral moratorium on the testing of nuclear weapons. The Reagan administration dismisses the dramatic move as nothing more than propaganda and refuses to follow suit. Gorbachev declares several extensions, but the United States fails to reciprocate, and the moratorium comes to an end on February 5, 1987. November 7: Crisis of Sigonella, diplomatic conflict between Italy and the United States.
== History == The use of banana powder in baby formula has been widespread since the very early 1900s as a method of keeping babies healthy. In 1916 it was also considered to be one of the "important industries of the West Indies" during this period, along with dried banana "figs". The United Fruit Company began to produce a product named Melzo during the 1930s, in which banana powder was the main ingredient. Because of the useful properties of banana powder, Melzo was marketed as a "health food for children and old folks, as a corrective for certain indigestions, and as a revitalizer for all who are sluggish mentally or physically".
=== Pharmacology === Preclinical and early clinical pharmacology studies characterized insulin icodec as a basal insulin analogue. The molecular modifications were intended to create an albumin-bound circulating depot, while preserving insulin receptor-mediated metabolic activity and limiting mitogenic activity relative to human insulin.
Sources: en.wikipedia.org
Selank is a seven-amino-acid peptide built from the tuftsin sequence plus a Pro-Gly-Pro tail. It is produced by chemical synthesis rather than extracted from a natural source. The free peptide is usually supplied as a lyophilised powder or in an aqueous formulation.
Tuftsin is a natural tetrapeptide derived from the Fc portion of immunoglobulin G. Selank retains that tetrapeptide at its N-terminus and adds three residues to improve resistance to enzymatic breakdown. The relationship is structural, and the two molecules are not interchangeable in experimental work.
It holds a product registration in Russia for intranasal use as an anxiolytic. Registrations of that kind are not automatically accepted by regulators elsewhere. In most other countries it is treated as an unapproved substance or a research material.
Most published work uses intranasal application, either as drops or as a nasal spray. Injection routes appear in a smaller set of animal experiments. Oral use is uncommon in the literature because peptide breakdown and poor absorption limit this route.