If you have been reading about pharmacokinetics and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Last reviewed on 2026-06-23. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
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.
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.
| 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 |
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.
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.
=== Colloidal synthesis === Colloidal semiconductor nanocrystals are synthesized from solutions, much like traditional chemical processes. The main difference is the product neither precipitates as a bulk solid nor remains dissolved. Heating the solution at high temperature, the precursors decompose forming monomers which then nucleate and generate nanocrystals. Temperature is a critical factor in determining optimal conditions for the nanocrystal growth. It must be high enough to allow for rearrangement and annealing of atoms during the synthesis process while being low enough to promote crystal growth. The concentration of monomers is another critical factor that has to be stringently controlled during nanocrystal growth. The growth process of nanocrystals can occur in two different regimes: "focusing" and "defocusing". At high monomer concentrations, the critical size (the size where nanocrystals neither grow nor shrink) is relatively small, resulting in growth of nearly all particles. In this regime, smaller particles grow faster than large ones (since larger crystals need more atoms to grow than small crystals) resulting in the size distribution focusing, yielding an improbable distribution of nearly monodispersed particles. The size focusing is optimal when the monomer concentration is kept such that the average nanocrystal size present is always slightly larger than the critical size. Over time, the monomer concentration diminishes, the critical size becomes larger than the average size present, and the distribution defocuses.
Franz Josef Land in the Russian Arctic was named in his honour in 1873 by the Austro-Hungarian North Pole expedition which first reported finding it. The Franz Josef Glacier in New Zealand's South Island also bears his name. Franz Joseph founded in 1872 the Franz Joseph University (Hungarian: Ferenc József Tudományegyetem, Romanian: Universitatea Francisc Iosif) in the city of Cluj-Napoca (at that time a part of Austria-Hungary under the name of Kolozsvár). The university was moved to Szeged after Cluj became a part of Romania, becoming the University of Szeged. In certain areas, celebrations are still being held in remembrance of Franz Joseph's birthday. The Mitteleuropean People's Festival takes place every year around 18 August, and is a "spontaneous, traditional and brotherly meeting among peoples of the Central-European Countries". The event includes ceremonies, meetings, music, songs, dances, wine and food tasting, and traditional costumes and folklore from Mitteleuropa. Franz Joseph was for some time present on the Polish Żywiec Zdrój bottled water labels, before being eventually removed in favor of the Abrahamów ridge.
In Puerto Rico and the Dominican Republic, mofongo is made by mashing fried plantains in a mortar with chicharrón or bacon, garlic, olive oil and stock. Any meat, fish, shellfish, vegetables, spices, or herbs can also be added. The resulting mixture is formed into cylinders the size of about two fists and eaten warm, usually with chicken broth. Mofongo relleno is topped with creole sauce rather than served with chicken broth. Creole sauce may contain stewed beef, chicken or seafood; it is poured into a center crater, formed with the serving spoon, in the mofongo. Grated green bananas and yautias are also used to form masa, a common ingredient for dishes such as alcapurria, which is a type of savory fritter. Fufu de platano is a traditional and very popular lunch dish in Cuba, and essentially akin to the Puerto Rican mofongo. It is a fufu made by boiling the plantains in water and mashing with a fork. The fufu is then mixed with chicken stock and sofrito, a sauce made from lard, garlic, onions, pepper, tomato sauce, a touch of vinegar and cumin. The texture of Cuban fufu is similar to the mofongo consumed in Puerto Rico, but it is not formed into a ball or fried. Fufu is also a common centuries-old traditional dish made in Côte d'Ivoire, Ghana, Nigeria, Cameroon and other West & Central African countries. It is made in a similar fashion as the Cuban fufu, but is pounded, and has a thick paste, putty-like texture which is then formed into a ball. West African fufu is sometimes separately made with cassava, yams or made with plantains combined with cassava.
A PLC assembly consists of seven subunits, including the transporters associated with antigen processing (TAP1 and TAP2 – jointly referred to as TAP), the oxidoreductase ERp57, the MHC-I heterodimer, and the chaperones tapasin and calreticulin. TAP transports proteasomal degradation products from the cytosol into the lumen of the ER, where they are loaded onto MHC-I molecules. The peptide-MHC-I complexes then move via a secretory pathway to the cell surface, presenting their antigenic load to cytotoxic T-cells. In general, preliminary MHC-I heavy chains are chaperoned by the calnexin–calreticulin system in the ER. Together with β2-microglobulin (β2m), MHC-I heavy chains form assemblies of heterodimers that act as receptors for antigenic peptides. Empty MHC-I heterodimers are recruited by calreticulin and form short-lived macromolecular PLC where the chaperone tapasin further provides stabilization in the MHC-I molecules. Furthermore, ERp57 and tapasin form disulfide-linked conjugates, and tapasin is crucial for maintaining the structural stability of the PLC as well as facilitating optimal peptide loading. After final quality control, during which MHC-I heterodimers undergo peptide editing, stable peptide–MHC-I complexes are released to the cell surface for T-cell recognition. The PLC can serve a large variety of MHC-I allomorphs, thus playing a central role in the differentiation and priming of T lymphocytes, and in controlling viral infections and tumour development.
Acrodermatitis chronica atrophicans (Herxheimer disease, primary diffuse atrophy) Actinic elastosis (solar elastosis) Anetoderma (anetoderma maculosa, anetoderma maculosa cutis, atrophia maculosa cutis, macular atrophy) Blepharochalasis Cutis laxa (chalazoderma, dermatochalasia, dermatolysis, dermatomegaly, generalized elastolysis, generalized elastorrhexis, pachydermatocele) Cutis rhomboidalis nuchae Ehlers–Danlos syndrome (cutis hyperelastica, elastic skin, India rubber skin) Elastosis perforans serpiginosa Homocystinuria Jadassohn–Pellizzari anetoderma Linear focal elastosis (elastotic striae) Loeys–Dietz syndrome Marfan syndrome Occipital horn syndrome Osteogenesis imperfecta (Lobstein syndrome) Perforating calcific elastosis (localized acquired cutaneous pseudoxanthoma elasticum, perforating periumbilical calcific elastosis, periumbilical perforating pseudoxanthoma elasticum) Pseudoxanthoma elasticum (Grönblad–Strandberg syndrome) Reactive perforating collagenosis Schweninger–Buzzi anetoderma Sclerotic fibroma Striae atrophicans Striae distensae Ullrich disease Verrucous perforating collagenoma Wrinkly skin syndrome
Sources: en.wikipedia.org
== Organisms and discovery == Creatinase was first identified by Roche, Lacombe, & Girard in 1950 in Pseudomonas eisenbergii and P. ovalis. It is produced by other bacterial genera including Bacillus, Flavobacterium, Micrococcus, Alcaligenes, Clostridium, Arthrobacter, and Paracoccus, and is produced by other species of Pseudomonas as well. In P. putida, creatinase is coded for by the creA gene and enables growth on creatine as the sole nitrogen source. Expression of creA is regulated by CahR, an AraC/GAT-R regulator that activates gene expression in the presence of creatine. This gene has also been cloned into Escherichia coli.
=== Adherence === It has been repeatedly found that in the long-term, all diets with the same calorific value perform the same for weight loss, except for the one differentiating factor of how well people can faithfully follow the dietary programme. A study comparing groups taking low-fat, low-carbohydrate and Mediterranean diets found at six months the low-carbohydrate diet still had most people adhering to it, but thereafter the situation reversed: at two years the low-carbohydrate group had the highest incidence of lapses and dropouts. This may be due to the comparatively limited food choice of low-carbohydrate diets.
This is caused by an atheroma or plaque in the artery wall and is a build-up of cell debris, that contain lipids, (cholesterol and fatty acids), calcium and a variable amount of fibrous connective tissue. Accidental intra-arterial injection either iatrogenically or through recreational drug use can cause symptoms such as intense pain, paresthesia and necrosis. It usually causes permanent damage to the limb; often amputation is necessary.
== History == The word "cachexia" is derived from the Greek words kakos 'bad' and hexis 'condition'. English ophthalmologist John Zachariah Laurence was the first to use the phrase "cancerous cachexia", doing so in 1858. He applied the phrase to the chronic wasting associated with malignancy. It was not until 2011 that the term "cancer-associated cachexia" was given a formal definition, with a publication by Kenneth Fearon. Fearon defined it as "a multifactorial syndrome characterized by ongoing loss of skeletal muscle (with or without loss of fat mass) that cannot be fully reversed by conventional nutritional support and leads to progressive functional impairment".
Sources: en.wikipedia.org
== History == Fosfomycin (originally known as phosphonomycin) was discovered in a joint effort of Merck and Co. and Spain's Compañía Española de Penicilina y Antibióticos (CEPA). It was first isolated by screening broth cultures of Streptomyces fradiae isolated from soil samples for the ability to cause formation of spheroplasts by growing bacteria. The discovery was described in a series of papers published in 1969. CEPA began producing fosfomycin on an industrial scale in 1971 at its Aranjuez facility.
Caspase-3 is a caspase protein that interacts with caspase-8 and caspase-9. It is encoded by the CASP3 gene. CASP3 orthologs have been identified in numerous mammals for which complete genome data are available. Unique orthologs are also present in birds, lizards, lissamphibians, and teleosts. The CASP3 protein is a member of the cysteine-aspartic acid protease (caspase) family. Sequential activation of caspases plays a central role in the execution-phase of cell apoptosis. Caspases exist as inactive proenzymes that undergo proteolytic processing at conserved aspartic residues to produce two subunits, large and small, that dimerize to form the active enzyme. This protein cleaves and activates caspases 6 and 7; and the protein itself is processed and activated by caspases 8, 9, and 10. It is the predominant caspase involved in the cleavage of amyloid-beta 4A precursor protein, which is associated with neuronal death in Alzheimer's disease. Alternative splicing of this gene results in two transcript variants that encode the same protein. Caspase-3 shares many of the typical characteristics common to all currently-known caspases. For example, its active site contains a cysteine residue (Cys-163) and histidine residue (His-121) that stabilize the peptide bond cleavage of a protein sequence to the carboxy-terminal side of an aspartic acid when it is part of a particular 4-amino acid sequence. This specificity allows caspases to be incredibly selective, with a 20,000-fold preference for aspartic acid over glutamic acid.
Erlich, "Enzymatic Amplification of β-globin Genomic Sequences and Restriction Site Analysis for Diagnosis of Sickle Cell Anemia"—the polymerase chain reaction invention (PCR)—was honored by a Citation for Chemical Breakthrough Award from the Division of History of Chemistry of the American Chemical Society in 2017. At the core of the PCR method is the use of a suitable DNA polymerase able to withstand the high temperatures of >90 °C (194 °F) required for separation of the two DNA strands in the DNA double helix after each replication cycle. The DNA polymerases initially employed for in vitro experiments presaging PCR were unable to withstand these high temperatures. So the early procedures for DNA replication were very inefficient and time-consuming, and required large amounts of DNA polymerase and continuous handling throughout the process. The discovery in 1976 of Taq polymerase—a DNA polymerase purified from the thermophilic bacterium, Thermus aquaticus in work co-authored by Alice Chien Chang—which naturally lives in hot (50 to 80 °C (122 to 176 °F)) environments such as hot springs—paved the way for dramatic improvements of the PCR method. The DNA polymerase isolated from T. aquaticus is stable at high temperatures remaining active even after DNA denaturation, thus obviating the need to add new DNA polymerase after each cycle. This allowed an automated thermocycler-based process for DNA amplification.
The Soviet Union repressed homosexuality. Even during the period when homosexuality was officially legal after the abolition of the Tsarist penal code criminalizing it, Soviet courts attempted to repress non-traditional forms of sexuality, which were widely viewed by Russian revolutionaries as a form of capitalist decadence despite more liberal views on homosexuality from Soviet academic sexologists. After Stalin's consolidation of power, homosexuality became officially recriminalised in 1934. The increased homophobia during this time interval was driven by the economic demands of the First Five-Year Plan, as well as the NKVD's view of homosexuals as "socially harmful elements", although even during this heightened period of repression, a clandestine homosexual subculture was able to persist. Homosexuality remained a criminal offence throughout the remainder of the Soviet Union's existence.
=== Blood sampling === Capillary blood sampling can be used to test for blood glucose (such as in blood glucose monitoring), hemoglobin, pH and lactate. It is generally performed by creating a small cut using a blood lancet, followed by sampling by capillary action on the cut with a test strip or small pipette. It is also used to test for sexually transmitted infections that are present in the blood stream, such as HIV, syphilis, and hepatitis B and C, where a finger is lanced and a small amount of blood is sampled into a test tube.
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.
Intranasal administration predominates in both animal and human research because it avoids hepatic first-pass metabolism. Injectable and intraperitoneal routes appear in animal work mainly for comparison.