This is a working overview of batch purity, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2025-11-15. Anything still debated is marked as such rather than presented as 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.
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.
Quantification in biological matrices relies on liquid chromatography coupled to tandem mass spectrometry with stable-isotope internal standards. Low plasma concentrations and adsorption to container surfaces both complicate measurement. Solid-phase extraction is often needed to reduce matrix interference before injection. Reported limits of quantification differ widely between laboratories, which makes direct comparison of pharmacokinetic results difficult and limits meta-analysis.
Peptide bonds are vulnerable to protease attack, and Selank is no exception. Measured half-life in serum is short, on the order of minutes in several reports, which explains why intranasal administration is the common route described in the literature. Absorption across the nasal mucosa partially bypasses first-pass hepatic metabolism. Quantitative data on human bioavailability remain limited and are difficult to compare across studies.
| Property | Value | Notes |
|---|---|---|
| Primary route studied | Intranasal | Also examined parenterally in animal work |
| Reported plasma half-life | Minutes to tens of minutes | Values vary widely between reports |
| Main model systems | Rodent behavioural and cell assays | Human trials are few and small |
| Principal proposed targets | GABA-A receptor, GABA transaminase | Monoamine and neurotrophic pathways also reported |
| Evidence grade | Preliminary | Limited independent replication |
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.
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.
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.
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.
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.
Enzymatic stability motivates the extra three residues at the carboxyl end. Native tuftsin is cleaved quickly by circulating aminopeptidases and carboxypeptidases, which limits its duration of action and its usefulness as a tool compound. Extending the chain with proline-rich segments is a common design tactic because proline constrains the backbone and slows proteolysis. The same Pro-Gly-Pro motif appears in other Russian-developed peptides of the era. Whether the full seven-residue chain is required for activity, or whether it acts mainly as a prodrug releasing tuftsin, remains unresolved.
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.
n + 147N → 146C + p where n represents a neutron and p represents a proton. Once produced, the 14C quickly combines with the oxygen (O) in the atmosphere to form first carbon monoxide (CO), and ultimately carbon dioxide (CO2).
=== PPAR-gamma agonists === PPARγ (gamma) is the main target of the drug class of thiazolidinediones (TZDs), used in diabetes mellitus and other diseases that feature insulin resistance. It is also mildly activated by certain NSAIDs (such as ibuprofen) and indoles, as well as from a number of natural compounds. Known inhibitors include the experimental agent GW-9662. They are also used in treating hyperlipidaemia in atherosclerosis. Here they act by increasing the expression of ABCA1, which transports extra-hepatic cholesterol into HDL. Increased uptake and excretion from the liver therefore follows. Animal studies have shown their possible role in amelioration of pulmonary inflammation, especially in asthma.
=== Background === In October 2008, Konstantin Kosachev, chair of the Russian State Duma Foreign Affairs Committee, said he supported the international investigation, but "a lot depends on who will enter this commission". In November 2008, Georgia called on the European Union to conduct an independent inquiry who was to blame for the conflict. An independent, international fact-finding mission headed by Swiss diplomat Heidi Tagliavini was established by the EU to determine the causes of the war. The commission relied on "recognised" experts. The commission was funded with €1.6 million. The report was published on 30 September 2009. According to the European Council on Foreign Relations, Russian information operations influenced the EU report. The report said it could not claim "veracity or completeness in an absolute sense", since "It incorporates what has been available to the Mission at the time of writing." The report could not give "total assurance that there are no mistakes or omissions".
The prognosis is worse in those with larger burns, those who are older, and females. The presence of a smoke inhalation injury, other significant injuries such as long bone fractures, and serious co-morbidities (e.g. heart disease, diabetes, psychiatric illness, and suicidal intent) also influence prognosis. On average, of those admitted to burn centers in the United States, 4% die, with the outcome for individuals dependent on the extent of the burn injury. For example, admittees with burn areas less than 10% TBSA had a mortality rate of less than 1%, while admittees with over 90% TBSA had a mortality rate of 85%. In Afghanistan, people with more than 60% TBSA burns rarely survive. The Baux score has historically been used to determine prognosis of major burns. However, with improved care, it is no longer very accurate. The score is determined by adding the size of the burn (% TBSA) to the age of the person and taking that to be more or less equal to the risk of death. Burns in 2013 resulted in 1.2 million years lived with disability and 12.3 million disability adjusted life years.
The more serious resistance in the départements was crushed by declaring a state of siege and by the "mixed commissions". The plebiscite of 20 December ratified by a huge majority the coup d'état in favour of the prince-president, who alone reaped the benefit of the excesses of the Republicans and the reactionary passions of the monarchists.
Sources: en.wikipedia.org
=== April === 1 April It is reported that three British men are being held in custody by the Taliban in Afghanistan. Manchester becomes the first city in the UK to launch a tourist tax, with a £1-per room per night City Visitor Charge. 2 April Home Secretary Suella Braverman confirms the UK is in negotiations with the Taliban following the reported arrest of three British nationals in Afghanistan. Braverman says that Rwanda is a safe place for the UK to send refugees after being asked about refugees being shot there by police at a demonstration in 2018, saying "that might be 2018, we're looking at 2023 and beyond". 3 April Members of the Public and Commercial Services Union working at the Passport Office begin a five-week strike over pay and conditions. The National Education Union announces two further strike dates in England on 27 April and 2 May, stating that the offer from the pay UK government is unacceptable, not fully funded, and does not address a shortage of teachers. The cost of a first class stamp increases by 15p to £1.10, and a second class stamp by 7p to 75p. Thomas Cashman is sentenced at Manchester Crown Court to life imprisonment with a minimum term of 42 years for the murder of Olivia Pratt-Korbel, meaning he will be in his mid-70s before becoming eligible for parole. 4 April Royal Mail issue new stamps featuring King Charles III, with an increase of a first class stamp up by 15p to £1.10, while the cost of a second class stamp has risen by 7p to 75p.
== Research == Much of the research conducted on demyelinating diseases is targeted towards discovering the mechanisms by which these disorders function in an attempt to develop therapies and treatments for individuals affected by these conditions. For example, proteomics has revealed several proteins which contribute to the pathophysiology of demyelinating diseases. For example, COX-2 has been implicated in oligodendrocyte death in animal models of demyelination. The presence of myelin debris has been correlated with damaging inflammation as well as poor regeneration, due to the presence of inhibitory myelin components. N-cadherin is expressed in regions of active remyelination and may play an important role in generating a local environment conducive to remyelination. N-cadherin agonists have been identified and observed to stimulate neurite growth and cell migration, key aspects of promoting axon growth and remyelination after injury or disease. Immunomodulatory drugs such as fingolimod have been shown to reduce immune-mediated damage to the CNS, preventing further damage in patients with MS. The drug targets the role of macrophages in disease progression. CNS-selective thyromimetics may become a viable strategy to protect myelin and promote remyelination in MS patients. It has been shown that intranasal administration of apotransferrin (aTf) can protect myelin and induce remyelination in mice. Finally, electrical stimulation which activates neural stem cells may provide a method by which regions of demyelination can be repaired.
A study treated non-diabetic, healthy men with the GLP-1 receptor antagonist (i.e., blocker of receptor activation) exendin(9-39)NH2a (also termed avexitide), the GIP receptor antagonist GIP(3-30)NH2, or both antagonists and challenged them with an oral glucose tolerance test. Men treated with either agent responded to the tolerance test with modest decreases in blood insulin levels and modest increases in blood glucose levels. However, men treated with both antagonists responded with very low insulin and very high glucose blood levels: their responses were similar to those in individuals with type 2 diabetes. This study shows that 1) the stimulation of the FFAR2 on K and L cells by SCFAs underlies the differences between oral and intravenous glucose challenges defined by the incretin effect and 2) FFAR2 functions to regulate blood insulin and glucose levels. This does not prove that type 2 diabetes is a FFAR2-incretin disease: post-feeding secretion of the incretins (i.e., GLP-1 and GIP) is impaired in type 2 diabetes, but the impairment appears to result primarily from decreases in the responsiveness of pancreas alpha cells to GLP-1. This conclusion is supported by studies showing that type 2 diabetic individuals who are treated with large amounts of GLP-1 and challenged with intravenous glucose show changes in blood insulin and glucose levels that are similar to those in non-diabetic individuals. Indeed, GLP-1 agonists, e.g., Dulaglutide, and a first-in-kind GLP-1 and GIP agonist, Tirzepatide, are used to treat type 2 diabetes.
The human musculoskeletal system (also known as the human locomotor system, and previously the activity system) is an organ system that gives humans the ability to move using their muscular and skeletal systems. The musculoskeletal system provides form, support, stability, and movement to the body. The human musculoskeletal system is made up of the bones of the skeleton, muscles, cartilage, tendons, ligaments, joints, and other connective tissue that supports and binds tissues and organs together. The musculoskeletal system's primary functions include supporting the body, allowing motion, and protecting vital organs. The skeletal portion of the system serves as the main storage system for calcium and phosphorus and contains critical components of the hematopoietic system. This system describes how bones are connected to other bones and muscle fibers via connective tissue such as tendons and ligaments. The bones provide stability to the body. Muscles keep bones in place and also play a role in their movement. To allow motion, different bones form joints together. Cartilage prevents the bone ends from rubbing directly onto each other. Muscles contract to move the bones attached at the joint. The joints and muscles are designed to interact harmoniously so that any applied muscular force keeps the joint positioned and aligned correctly during movement and this, reciprocally, helps to maintain the correct length and tension in those corresponding muscles. There are, however, diseases and disorders that may adversely affect the function and overall effectiveness of the system.
==== Danger of misidentification ==== One danger of attempting to consume hallucinogenic or other wild mushrooms, especially for novice mushroom hunters, is the possibility of misidentification with toxic species. In one noted case, an otherwise healthy young Austrian man mistook the poisonous Cortinarius rubellus for P. semilanceata. As a result, he suffered end-stage kidney failure, and required a kidney transplant. In another instance, a young man developed cardiac abnormalities similar to those seen in Takotsubo cardiomyopathy, characterized by a sudden temporary weakening of the myocardium. A polymerase chain reaction-based test to specifically identify P. semilanceata was reported by Polish scientists in 2007.
Sources: en.wikipedia.org
Xi has called China–United States relations in the contemporary world a "new type of great-power relations", a phrase the Obama administration had been reluctant to embrace. Xi has indirectly spoken out critically on the U.S. "strategic pivot" to Asia. Relations with the U.S. soured after Donald Trump became president in 2017. Since 2018, U.S. and China have been engaged in an escalating trade war. In 2020, the relations further deteriorated due to the COVID-19 pandemic.
== History == Natera (previously Gene Security Network) was founded by Matthew Rabinowitz and Jonathan Sheena in 2004. Natera launched its first product, the Spectrum preimplantation genetic test, in 2009. In 2010, the company introduced the Anora miscarriage (POC) test. Natera's advanced carrier screening test, Horizon, launched in 2012. The following year, 2013, Natera launched the Panorama non-invasive prenatal test (NIPT). In July 2015, Natera conducted an initial public offering of common stock at a price of $18.00 per share. The shares trade on the Nasdaq Global Select Market under the symbol "NTRA." In 2017, Natera launched the Vistara single-gene NIPT. That same year, Natera introduced the Signatera molecular residual disease (MRD) test for research use only. The Signatera CLIA test was introduced for clinical use in 2019. In 2018 Natera paid a $11 million fine to the department over allegations of improper billing and sales of Panorama to federal Healthcare services between the years of 2013 to 2016. Natera launched the Prospera dd-cfDNA transplant assessment test in 2019, and the Renasight kidney gene panel and the Empower hereditary cancer test in 2020. As of May 2021, Natera has performed over 3 million cell-free DNA tests. Natera's technology has also been written about in over 200 peer-reviewed journals and publications, including Nature, Science Magazine, and the Journal of Clinical Oncology.
In another array synthesis, Still generated a large library of oligopeptides by split synthesis. The drawback to making many thousands of compounds is that it is difficult to determine the structure of the formed compounds. Their solution is to use molecular tags, where a tiny amount (1 pmol/bead) of a dye is attached to the beads, and the identity of a certain bead can be determined by analyzing which tags are present on the bead. Despite how easy attaching tags makes identification of receptors, it would be quite impossible to individually screen each compound for its receptor binding ability, so a dye was attached to each receptor, such that only those receptors that bind to their substrate produce a color change. When many reactions need to be run in an array (such as the 96 reactions described in one of Armstrong's MCC arrays), some of the more tedious aspects of synthesis can be automated to improve efficiency. This work, the "DIVERSOMER method" was pioneered at Parke-Davis in the early 1990s to run up to 40 chemical reactions in parallel. These efforts led to the first commercially available equipment for combinatorial chemistry (the Diversomer synthesizer sold by Chemglass) and the first use of liquid handling robotics within a chemistry laboratory.
In addition, various side effects, including insomnia, sedation, weight loss, constipation, dry mouth, erectile dysfunction, excessive sweating, and urinary retention, among others, have been found to be around twice as frequent in poor metabolizers relative to extensive metabolizers. The same was true for discontinuation rates (11.2% vs. 6.3%). In terms of dosage adjustment for CYP2D6 poor metabolizers or those taking strong CYP2D6 inhibitors, the Food and Drug Administration (FDA) label says that this may be necessary and provides directions for this, whereas literature reviews state that it is not considered necessary based on clinical trial experience.
Peukert noted that having promised "paradise" in the form of the volksgemeinschaft under the Weimar republic, there was much frustration within the Nazi movement when in 1933 the volksgemeinschaft in reality did not meet the idealized version of the volksgemeinschaft that had promised before 1933. Peukert wrote that because of this frustration that the Nazis gave the volksgemeinschaft an increasing negative definition, lashing out in increasing vicious ways against any perceived "threats" to the volksgemeinschaft. As part of this trend, there was a tendency as the Third Reich went along for the Nazis to seek to erase all nonconformity, deviance and differences from German society with anyone who was not a perfect Volksgenossen ("National Comrade") considered to be in someway an "enemy". In this way, the violence that the Nazis had directed against "outsiders" in Germany had gradually started to be applied against at least some of the previous "insiders" as those Volksgenossen who for whatever reason did not quite measure up to the ideal found there was no place for them in the volksgemeinschaft. Peukert concluded that the National Socialists failed to create the idealized volksgemeinschaft, but they unwittingly laid the foundations for the stability of the Adenauer era in 1950s West Germany by promoting a mass consumerist society combined with extreme violence against their "enemies", which made politically engagement dangerous.
Sources: en.wikipedia.org
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.
The peptide enters plasma rapidly and is broken down by ordinary proteases into amino acids and shorter fragments. Reported half-lives are short. Whether meaningful amounts of the intact molecule reach the brain is an open question.
Most clinical reports are small, published in Russian and not independently replicated. English-language reviews highlight the absence of large randomised trials. Conclusions about efficacy should be treated as provisional.
Dry powder is best kept sealed, protected from light, and held at minus 20 degrees Celsius or below. Desiccant packaging helps limit moisture uptake because the material is hygroscopic. A sealed vial should be allowed to equilibrate to room temperature before opening to reduce condensation.