Lyophilisation raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
Reviewed 2026-03-09. 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.
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.
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.
| 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 |
Identity and purity are usually assessed by reversed-phase high-performance liquid chromatography, with mass spectrometry used to confirm molecular mass and sequence information. Amino acid analysis and peptide mapping may supplement these methods. Certified reference standards are scarce, and many commercial lots are sold as research chemicals without a pharmacopoeial monograph. Regulatory treatment differs by country: Selank is a registered prescription medicine in Russia, while in the European Union and the United States it is not an approved drug and may fall under research-chemical or unapproved-product frameworks.
Selank is a hydrophilic peptide and dissolves readily in water and in aqueous buffers. The lyophilised powder is typically a white to off-white solid. Because short peptides are prone to hydrolysis and oxidation, handling benefits from limiting exposure to heat, moisture and strong light. Working solutions are commonly prepared in sterile water or saline, and repeated freeze-thaw cycles are avoided to reduce aggregation and loss of activity. These practices reflect general laboratory convention rather than published stability specifications.
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.
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.
Reverse-phase high-performance liquid chromatography with ultraviolet detection near 214 nanometres is the standard purity method. Mass spectrometry, typically electrospray ionisation, confirms identity through the expected mass-to-charge pattern. Amino acid analysis can verify composition independently. Chiral purity requires separate techniques such as derivatisation followed by chromatographic separation, and such data are rarely reported for research-grade material.
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.
Avoidance of smoking, counseling and pharmacotherapies to quit smoking are used, and avoidance of environmental tobacco smoke is recommended. Alzheimer's disease is associated with sleep disorders but the precise relationship is unclear. It was once thought that as people get older, the risk of developing sleep disorders and AD independently increase, but research suggests sleep disorders may be a risk factor for AD. One theory is that the mechanisms to increase clearance of toxic substances, including Aβ, are active during sleep. With decreased sleep, a person is increasing Aβ production and decreasing Aβ clearance, resulting in Aβ accumulation. Receiving adequate sleep (approximately 7–8 hours) every night has become a potential lifestyle intervention to prevent the development of AD. Stress is a risk factor for the development of AD. The mechanism by which stress predisposes someone to the development of AD is unclear, but it is suggested that lifetime stressors may affect a person's epigenome, leading to an overexpression or underexpression of specific genes. Although the relationship of stress and AD is unclear, strategies to reduce stress and relax the mind may be helpful strategies in preventing the progression or Alzheimer's disease. Meditation, for instance, is a helpful lifestyle change to support cognition and well-being, though further research is needed to assess long-term effects.
Sydenham's chorea, also known as rheumatic chorea, is a disorder characterized by rapid, uncoordinated jerking movements primarily affecting the face, hands and feet. Sydenham's chorea is an autoimmune disease that results from childhood infection with Group A beta-haemolytic Streptococcus. It is reported to occur in 20–30% of people with acute rheumatic fever and is one of the major criteria for it, although it sometimes occurs in isolation. The disease occurs typically a few weeks, but up to 6 months, after the acute infection, which may have been a simple sore throat (pharyngitis). Sydenham's chorea is more common in females than males, and most cases affect children between 5 and 15 years of age. Adult onset of Sydenham's chorea is comparatively rare, and the majority of the adult cases are recurrences following childhood Sydenham's chorea (although pregnancy and female hormone treatment are also potential causes). It is historically one of the conditions called St Vitus' dance.
In Mesopotamia, early pictorial evidence for beer drinking includes a 6,000-year-old Sumerian seal from Tepe Gawra, dating to around 4000 BC, which depicts two figures drinking beer through long reed straws from a communal bowl. Chemical analysis of pottery from Godin Tepe in the central Zagros Mountains of present-day Iran provides evidence of barley beer from about 5,500 years ago, with fragments of a jug found to contain deposits of beerstone, a by-product associated with brewing. A 3900-year-old Sumerian poem honouring Ninkasi, the patron goddess of brewing, contains the oldest surviving beer recipe, describing the production of beer from barley via bread. The production of bread and beer has been argued to be responsible for humanity's ability to develop technology and build civilisation. Beer may have been known in Neolithic Europe as far back as 5,000 years ago, Brewing remained largely a household activity in early medieval Europe, although beer was also produced commercially and in monasteries. Ale produced before the Industrial Revolution continued to be made and sold on a domestic scale, while during the early Middle Ages beer was also being produced and sold by European monasteries. During the Industrial Revolution, the production of beer moved from artisanal to industrial manufacture, and domestic manufacture ceased to be significant by the end of the 19th century. The development of hydrometers and thermometers changed brewing by allowing the brewer more control of the process, and greater knowledge of the results.
Dihydroxyphenylalanine ammonia-lyase was presumed to use 3,4-dihydroxy-L-phenylalanine (L-DOPA) to produce trans-caffeate and NH3. However, the EC number for this purported enzyme was deleted in 2007, as no evidence has emerged for its existence.
When stimulated in Oplophorus gracilirostris, OpLuc is secreted from the base of legs and antennae of the deep-sea shrimp as a defense mechanism. This mechanism causes O.gracilirostris release a luminous, bright blue luciferase cloud. There are many species of shrimp which display similar bioluminescence.
Sources: en.wikipedia.org
On April 6, 2017, Pritzker announced his candidacy for the Democratic nomination for governor of Illinois. He was endorsed by Illinois Secretary of State Jesse White, Illinois Congressman Luis Gutiérrez, former Illinois Congressman Glenn Poshard, more than a dozen members of the Illinois General Assembly, 21 local labor unions, and the Illinois AFL–CIO. On August 10, 2017, Pritzker announced that his running mate would be freshman state representative and fellow Chicago resident Juliana Stratton. By December 2017, Pritzker had spent $42 million of his own money on his campaign without receiving funding from any other source. On March 20, 2018, he won the Democratic primary with 45.13% of the vote, defeating five opponents. On November 6, 2018, Pritzker defeated incumbent Republican governor Bruce Rauner in the general election, receiving 54.53% of the vote to Rauner's 38.83%. Pritzker was well ahead of Rauner in most polls from the summer of 2018 onward, and won by the largest margin in a gubernatorial race since 1994. Pritzker spent $171.5 million of his own money on his campaign, primarily on digital outreach, television advertising, and staff. Pritzker was inaugurated as Illinois's 43rd governor on January 14, 2019. With an estimated net worth of $3.6 billion in January 2019, he became the richest politician in the U.S. His second term in office began on January 9, 2023.
=== Reorganization === In January 2006, the division began reorganizing from a division based organization to a brigade combat team-based organization. Activated elements include a 4th Brigade Combat Team, 82nd Airborne Division (1–508th INF, 2–508th INF, 4–73rd Cav (RSTA), 2–321st FA, 782nd BSB, and STB, 4th BCT) and the inactivation of the Division Artillery, 82nd Signal Battalion, 307th Engineer Battalion, and 313th Military Intelligence Battalion. The 82nd Division Support Command (DISCOM) was redesignated as the 82nd Sustainment Brigade. A pathfinder unit was reactivated within the 82nd when the Long Range Surveillance Detachment of the inactivating 313th Military Intelligence Battalion was transferred to the 2d Battalion, 82nd Aviation Regiment and converted to a pathfinder role as the battalion's Company F.
In addition, some observers, such as those writing in the Trade Environmental Database (TED) Case Studies as part of the Mandala Project from American University, have pointed to "serious communication problems and management gaps between Union Carbide and its Indian operation", characterised by "the parent companies [sic] hands-off approach to its overseas operation" and "cross-cultural barriers".
== Function == Trypsinogen is the proenzyme precursor of trypsin. Trypsinogen (the inactive form) is stored in the pancreas so that it may be released when required for protein digestion. The pancreas stores the inactive form trypsinogen because the active trypsin would cause severe damage to the tissue of the pancreas. Trypsinogen is released by the pancreas into the second part of the duodenum, via the pancreatic duct, along with other digestive enzymes.
The glans is completely or partially covered by a double-layered fold of skin, known as the foreskin. In adults, glans exposure can be easily achieved by manual retraction of the foreskin and sometimes automatically during erection. The degree of automatic foreskin retraction varies considerably depending on the foreskin length. The foreskin can be characterized as long when the preputial orifice extends beyond the glans during erection, or medium when the orifice is located around the meatus. The primary purpose of the foreskin is considered to be the covering of the glans and the urinary meatus, while also maintaining the mucosa in a moist environment. Foreskin retractability gradually increases with age. In infancy, the foreskin is fused to the glans. It remains non-retractable in early childhood. It tightens during preadolescence. The skin begins to loosen up significantly during puberty, allowing the glans to be completely exposed when needed. By the age of eighteen, most boys will have a fully retractable foreskin. The glans on a circumcised penis remains fully exposed and dry. Generally, studies suggest that the glans remains equally sensitive in circumcised and uncircumcised penises.
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.
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.