pharmacokinetics is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Updated 2025-12-13. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
Development work on the compound began in the 1980s and 1990s at the Institute of Molecular Genetics in Moscow, within the same research programme that produced the peptide Semax. Early investigators sought a tuftsin derivative with improved resistance to enzymatic breakdown and with activity in the central nervous system after peripheral administration. Most of the primary literature from this period was published in Russian, a factor that still shapes how easily the findings can be checked by outside groups.
| Property | Value | Notes |
|---|---|---|
| Molecular class | Synthetic heptapeptide | Stabilized analog of tuftsin |
| Sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Single-letter form: TKPRPGP |
| Molecular formula | C33H57N11O9 | Monoisotopic mass about 751.9 Da |
| Appearance | White to off-white powder | Typically supplied as lyophilized solid |
| Solubility | Freely soluble in water | Also soluble in common polar solvents |
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.
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.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. It was designed at the Institute of Molecular Genetics of the Russian Academy of Sciences as a structural analogue of tuftsin, a naturally occurring tetrapeptide fragment of the immunoglobulin heavy chain. The added Pro-Gly-Pro tail was intended to slow enzymatic degradation and extend biological activity. In Russia it is registered as an anxiolytic nasal preparation, while regulators elsewhere have not approved it for clinical use.
Proposed mechanisms centre on modulation of the GABAergic system, with reports of altered expression of genes related to GABA-A receptor subunits and changed monoamine turnover. Some studies describe inhibition of enkephalinase, the enzyme that degrades endogenous enkephalins, which may prolong opioid peptide signalling. Effects on brain-derived neurotrophic factor and on cytokine expression have also been reported. These findings come largely from animal models and small human studies, and the precise primary target remains unresolved.
Published clinical evidence is limited. Most controlled trials were conducted in Russia, enrolled modest numbers of participants, and appeared in Russian-language journals, which restricts independent verification. Reported outcomes include lower anxiety scores, improved attention and memory measures, and changes in fatigue ratings. Reviews written in English note methodological limitations such as small samples and inconsistent endpoints. Whether the compound produces clinically meaningful benefit relative to established anxiolytics is therefore an open question rather than an established finding.
(CH2CH2)O + PCl5 → Cl–CH2CH2–Cl + POCl3 Other dichloro derivatives of ethylene oxide can be obtained by combined action of sulfuryl chloride (SOCl2) and pyridine and of triphenylphosphine and carbon tetrachloride. Phosphorus trichloride reacts with ethylene oxide forming chloroethyl esters of phosphorous acid:
Diski was a regular contributor to the London Review of Books; the collections Don't and Why Didn't You Do What You Were Told? collect articles and essays written for the publication. Her memoirs include In Gratitude, The Sixties, Skating to Antarctica, and Stranger on a Train: Daydreaming and Smoking around America With Interruptions, for which she won the 2003 Thomas Cook Travel Book Award. Benjamin Disraeli (1804–1881) novelist, poet, playwright, writer, and prime minister A prolific novelist, the 1840s Disraeli wrote a trilogy of novels with political themes. Coningsby attacks the evils of the Whig Reform Bill of 1832 and castigates the leaderless conservatives for not responding. Sybil; or, The Two Nations (1845) reveals Peel's betrayal over the Corn Laws. These themes are expanded in Tancred (1847). With Coningsby; or, The New Generation (1844). Isaac D'Israeli, (11 May 1766 – 19 January 1848) was a British writer, scholar and the father of British prime minister Benjamin Disraeli. He is best known for his essays and his associations with other men of letters. Michael Pinto-Duschinsky (born June 1943) Hungarian-born author, journalist, scholar, political consultant and writer. Anton Ehrenzweig (27 November 1908 – 5 December 1966) Austrian Jewish British author and theorist on modern art, psychoanalysis and Avant-garde music who wroteThe Psychoanalysis of Artistic Vision and Hearing (1953) and The Hidden Order of Art (1967).
Measurement of total bilirubin includes both unconjugated (indirect) and conjugated (direct) bilirubin. Unconjugated bilirubin is a breakdown product of heme (a part of hemoglobin in red blood cells). The liver is responsible for clearing the blood of unconjugated bilirubin, by 'conjugating' it (modified to make it water-soluble) through an enzyme named UDP-glucuronyl-transferase. When the total bilirubin level exceeds 17 μmol/L, it indicates liver disease. When total bilirubin levels exceed 40 μmol/L, bilirubin deposition at the sclera, skin, and mucous membranes will give these areas a yellow colour, thus it is called jaundice. The increase in predominantly unconjugated bilirubin is due to overproduction, reduced hepatic uptake of the unconjugated bilirubin and reduced conjugation of bilirubin. Overproduction can be due to the reabsorption of a haematoma and ineffective erythropoiesis leading to increased red blood cell destruction. Gilbert's syndrome and Crigler–Najjar syndrome have defects in the UDP-glucuronyl-transferase enzyme, affecting bilirubin conjugation. The degree of rise in conjugated bilirubin is directly proportional to the degree of hepatocyte injury. Viral hepatitis can also cause the rise in conjugated bilirubin. In parenchymal liver disease and incomplete extrahepatic obstruction, the rise in conjugated bilirubin is less than the complete common bile duct obstruction due to malignant causes. In Dubin–Johnson syndrome, a mutation in multiple drug-resistance protein 2 (MRP2) causes a rise in conjugated bilirubin.
== Scientific use == α-Amanitin is a selective inhibitor of RNA polymerase II and III but not I. This mechanism makes it a deadly toxin. α-Amanitin can also be used to determine which types of RNA polymerase are present. This is done by testing the sensitivity of the polymerase in the presence of α-amanitin. RNA polymerase I is insensitive, RNA polymerase II is highly sensitive (inhibited at 1μg/ml), RNA polymerase III is moderately sensitive (inhibited at 10μg/ml), and RNA polymerase IV is slightly sensitive (inhibited at 50μg/ml).
== Epidemiology == Cardiovascular disease, which is predominantly the clinical manifestation of atherosclerosis, is one of the leading causes of death worldwide. Almost all children older than age 10 in developed countries have aortic fatty streaks, with coronary fatty streaks beginning in adolescence. In 1953, a study was published that examined the results of 300 autopsies performed on U.S. soldiers who had died in the Korean War. Despite the average age of the soldiers being just 22 years old, 77% of them had visible signs of coronary atherosclerosis. This study showed that heart disease could affect people at a younger age and was not just a problem for older individuals. In 1992, a report showed that microscopic fatty streaks were found in the left anterior descending artery in over 50% of children aged 10–14, and 8% had even more advanced lesions with more accumulations of extracellular lipid. A 2005 report of a study from 1985 to 1995 found that around 87% of aortas and 30% of coronary arteries in the age group 5–14 years had fatty streaks, which increased with age.
Sources: en.wikipedia.org
The renal interstitium facilitates solute and water transport between blood and urine in the vascular and tubular elements of the kidneys, and water reabsorption through changes in solute concentrations and hydrostatic gradients. The myocardial interstitium participates in ionic exchanges associated with the spread of electrical events. The pulmonary interstitium allows for fluctuations in lung volume between inspiration and expiration. The composition and chemical properties of the interstitial fluid vary among organs and undergo changes in chemical composition during normal function, as well as during body growth, conditions of inflammation, and development of diseases, as in heart failure and chronic kidney disease.
=== Halides === The colorless curium(III) fluoride (CmF3) can be made by adding fluoride ions into curium(III)-containing solutions. The brown tetravalent curium(IV) fluoride (CmF4) on the other hand is only obtained by reacting curium(III) fluoride with molecular fluorine:
In November 2023, the first global AI Safety Summit was held in Bletchley Park in the UK to discuss the near and far term risks of AI and the possibility of mandatory and voluntary regulatory frameworks. 28 countries including the United States, China, and the European Union issued a declaration at the start of the summit, calling for international co-operation to manage the challenges and risks of artificial intelligence. In May 2024 at the AI Seoul Summit, 16 global AI tech companies agreed to safety commitments on the development of AI. In March 2026, the United Nations convened the inaugural meeting of the Independent International Scientific Panel on AI, a 40-member expert body established under the Global Digital Compact to produce annual evidence-based reports on AI's societal impacts.
On 19 January it became known that Canada considered sending troops to Greenland to reinforce Danish sovereignty. Despite Poland's recent interest and participation in military exercises in the Arctic region, and having signed a bilateral defence agreement with Denmark in the 1990s, Polish prime minister Donald Tusk and Defence Minister Władysław Kosiniak-Kamysz stated that Poland would not deploy troops in Greenland. This decision was criticised by former Major General Roman Polko as "sheer cowardice", to which Kosiniak-Kamysz defended it as protecting NATO unity. Between 19 January and 3 February, NORAD deployed their aircraft to Pituffik Space Base in Greenland for long-planned activities, describing the deployment as routine and coordinated with the Kingdom of Denmark with diplomatic clearances and with the Government of Greenland informed of the planned operations. On 21 January, France proposed a larger NATO exercise in Greenland and said they are willing to participate.
Sources: en.wikipedia.org
== Syndromes == Bracken is known to have various biological effects, such as carcinogenicity and its well-defined syndromes in livestock and laboratory animals. Ptaquiloside is proved to be responsible for several of these biological effects, some of which are species specific.
The first Masons in Cuba were most likely Speculative and Operative, not Symbolic, and arrived by the early half of the 18th Century, as indicated by archaeological evidences of Masonic symbols that were found carved into the stones of the Convent of San Francisco as Mason's marks, which have been relatively dated to its current construction beginning in 1716, the year before Symbolic Freemasonry was established in England. These symbols were carved by operative stonemasons who had been brought into the country by the Catholic Church from disparate parts of the European continent to work on the construction project. At that time, Operative Masonic and Speculative Masonic guilds in Spain were not centralized, functioning instead as independent and unique Lodges, and it was not until 1728 that they formed the unified body of Freemasonry in Spain. The Convent of San Francisco did also receive renovations in 1731, but Havana's official City Historian, Eusebio Leal Spengler, stated during an inspection of the site that the marks were part of the construction of the convent and were not added anytime after the first half of the 18th Century. In 1738, ten years after Symbolic Freemasonry arrived in Spain, Pope Clement XII issued a Papal bull banning the practice of Freemasonry in the Catholic church. Following this, the Grand Inquisitor of Spain issued an edict banning the practice within the Spanish church by punishment of excommunication and a fine. In 1750, José Torrubia, while working for the Holy Office of the Inquisition in Madrid, went undercover as a Freemason in Spain.
== History == Residency as an opportunity for advanced training in a medical or surgical specialty evolved in the late 19th century from brief and informal programs for extra training in a special area of interest. The first formal residency programs were established by William Osler and William Stewart Halsted at Johns Hopkins Hospital in Baltimore. Residencies elsewhere then became formalized and institutionalized for the principal specialties in the early 20th century. But even mid-century, residency was not seen as necessary for general practice and only a minority of primary care physicians participated. The expansion of medical residencies in the United States experienced a significant surge following World War II. In the post-war landscape, the demand for skilled physicians escalated, necessitating a robust training infrastructure. The G.I. Bill, a landmark piece of legislation, played a pivotal role in fueling this expansion by providing educational benefits to returning veterans, including those pursuing medical careers. The increased financial support facilitated a surge in medical school enrollments, spurring the need for expanded residency programs to accommodate the growing pool of aspiring physicians. This period witnessed the establishment of numerous new residency positions across various specialties. In 1940 there were approximately 6,000 residency positions available, but by 1970 the available spots had increased to more than 40,000. At the same time, the daily operation of the hospital increasingly relied on medical residents.
Sources: en.wikipedia.org
Selank is a synthetic heptapeptide designed as a stabilized analog of the natural tetrapeptide tuftsin. It has been investigated mainly for anxiolytic and cognitive effects. It is not an approved pharmaceutical in most countries.
It was developed in Russia, at the Institute of Molecular Genetics of the Russian Academy of Sciences, during the 1990s. Most published research originates from Russian institutions. Independent international replication remains limited.
Tuftsin is a natural tetrapeptide with the sequence Thr-Lys-Pro-Arg that participates in immune signaling. Selank extends that sequence with Pro-Gly-Pro at the C-terminus. The added residues are linked to greater resistance to enzymatic breakdown.
The sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, commonly written as TKPRPGP. It shares the first four residues with tuftsin and carries three prolines in the chain. The proline-rich tail is the main structural feature that separates it from the parent tetrapeptide.