certificate of analysis 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.
Last reviewed on 2026-07-07. Where a claim depends on a specific study, the study is described rather than over-claimed.
Clinical evidence comes mainly from small studies conducted in Russia, several of which were open-label or lacked robust blinding. Reported outcomes include lower anxiety scores, changes in attention measures, and effects on asthenic states following illness. Sample sizes are typically in the tens of participants, and independent replication outside the region is scarce. Reviews published in English generally note the limited methodological quality of the underlying trials. Whether the compound produces clinically meaningful effects under rigorous conditions remains unresolved.
Proposed mechanisms center on modulation of the GABA system, but no single molecular target has been confirmed. Rodent studies report changes in GABA-A receptor expression and in the turnover of serotonin, dopamine, and norepinephrine in several brain regions. Increases in brain-derived neurotrophic factor and its receptor have also been described after repeated administration. These findings come largely from animal models, and the degree to which they describe human neurochemistry remains an open question. The mechanism is best characterized as multi-system and not fully resolved.
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.
| Property | Value | Notes |
|---|---|---|
| Route studied | Intranasal | Predominant route in published reports |
| Circulation stability | Short, minutes scale | Peptidases cleave it; the tail slows the process |
| Analytical method | RP-HPLC with mass spectrometry | Used for identity and purity assessment |
| Reported outcome domains | Anxiety and cognitive measures | Derived from small, mostly regional trials |
| Regulatory status | Marketed in Russia | Availability outside that market is limited |
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 not a naturally occurring peptide and has no known endogenous counterpart in human physiology. Russian-language sources frequently call it TP-7, while English-language sources use the name Selank almost exclusively. Database indexing is uneven, partly because early reports appeared in regional journals that are not widely cataloged. Some summaries describe the material as a tuftsin analog and others as a synthetic heptapeptide; the labels overlap rather than conflict. Citing the primary sequence resolves ambiguity more reliably than the research or trade name alone.
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.
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.
Dry powder is normally held at -20 degrees Celsius or lower, in a sealed container with desiccant and protection from light. Reconstituted solutions are usually kept at 2 to 8 degrees Celsius for short periods and frozen for longer ones. Proline residues at several positions are generally associated with some resistance to peptidase attack, but chemical stability still declines at neutral to alkaline pH and at elevated temperature. Exact shelf-life figures are product-specific and are not standardised across suppliers.
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.
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.
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.
An individual with a transsexual or gender dysphoria diagnosis can, together with the assessment team and other doctors, decide what suits them. Medically transitioning in Sweden is covered by the high-cost protection for medications and doctor's visits, and there is no surgery fee. The fee the individual pays for a doctor's appointment or other care represents only a small fraction of the actual costs. If a person would like to change their legal gender marker and personal identity number they will have to seek permission from the National Board of Health and Welfare. For non-binary persons younger than 18 years, the healthcare is limited. These individuals do not have access to a legal gender marker change or bottom surgery. In Sweden, anyone is allowed to change their name at any time, including for gender transition. Up until January 27, 2017, being transsexual was classed as a disease. Two months earlier, on November 21, 2016, around 50 trans activists broke into and occupied the Swedish National Board of Health and Welfare (Swedish: Socialstyrelsen) premises in Rålambsvägen in Stockholm. The activists demanded that their voices be heard regarding the way the country, healthcare, and the National Board of Health and Welfare mistreat transgender and intersex individuals. Sweden's Karolinska Institute, administrator of the second-largest hospital system in the country, announced in March 2021 that it would discontinue providing puberty blockers or cross-sex hormones to children under 16.
=== Building of preclinical functional === In the preclinical functional building houses the Department of Secretariat, offices of faculty of Basic Medical Sciences and Clinical Laboratories, the Laboratory and Tutorial Rooms and various auxiliary rooms for students, where take place various events.
== Discovery == The parent structure of lefetamine, 1,2-diphenylethylamine was first synthesized in the 1940s and showed weak analgesic activity. Lefetamine itself was first investigated in Japan in the 1950s. The L-isomer showed weak analgesic action comparable to codeine and antitussive action far weaker than codeine. The d-isomer showed no such activity but caused seizures in rats.
=== Pharmacodynamics === Ripasudil's mechanism of action affects intraocular pressure, or IOP, "by directly acting on the trabecular meshwork, thereby increasing conventional outflow through the Schlemm’s canal." More simply, it is an "out-flow" drug that reduces IOP by stimulating the movement of aqueous humour from the ciliary body away from the eye. It is a selective rho-associated coiled-coil-containing protein kinase 1 (ROCK1) inhibitor, where ROCK1 is "an important downstream effector of Rho guanosine trisphosphates (GTP)," proteins that are significant in the contractile control of smooth muscle tissue. The S configuration at the 2-position on the 1,4-diazepane ring of Ripasudil is what gives the drug its characteristic effect. Ripasudil was originally developed from fasudil, as both compounds share the same core structure of 5-(1,4-diazepan-1-ylsulfonyl)isoquinoline. Fasudil was already recognized as a potent Rho-kinase inhibitor, but after exploring the chemical derivatives of fasudil, developers observed that the incorporation of a fluorine atom at the C4 position of isoquinoline moiety and the chiral attachment of a methyl group to the C2’ position of 1,4-diazepane moiety dramatically improved the pharmacological action. In short, "ripasudil showed much more potent and selective Rho-kinase inhibitory activity than fasudil".
The meteorite contained a mixture of left-handed and right-handed amino acids; most amino acids used by living organisms are left-handed in chirality, and most sugars used are right-handed. A team of chemists in Sweden demonstrated in 2005 that this homochirality could have been triggered or catalyzed by the action of a left-handed amino acid such as proline. Several lines of evidence indicate that the interior portions of well-preserved fragments from Murchison are pristine. A 2010 study using high resolution analytical tools including spectroscopy, identified 14,000 molecular compounds, including 70 amino acids, in a sample of the meteorite. The limited scope of the analysis by mass spectrometry provides for a potential 50,000 or more unique molecular compositions, with the team estimating the possibility of millions of distinct organic compounds in the meteorite. In November 2019, along with the Northwest Africa 801 meteorite it was the first to provide evidence of pentoses (including ribose) in space, using gas chromatography–mass spectrometry. All the straight-chain five-carbon aldoses were found but tetroses, sugar alcohols, sugar acids, and deoxyribose were not detected. In 2020, NASA announced that hexamethylenetetramine had been found in the Murchison, Murray and Tagish Lake meteorites.
Sources: en.wikipedia.org
== Plants and bacteria == Although they lack neurons, systems responding to stimuli (analogous to the sensory system in animals with a nervous system, which includes the proprioception) have also been described in some plants (angiosperms). Terrestrial plants control the orientation of their primary growth through the sensing of several vectorial stimuli such as the light gradient or the gravitational acceleration. This control has been called tropism. A quantitative study of shoot gravitropism demonstrated that, when a plant is tilted, it cannot recover a steady erected posture under the sole driving of the sensing of its angular deflection versus gravity. An additional control through the continuous sensing of its curvature by the organ and the subsequent driving an active straightening process are required. Being a sensing by the plant of the relative configuration of its parts, it has been called proprioception. This dual sensing and control by gravisensing and proprioception has been formalized into a unifying mathematical model simulating the complete driving of the gravitropic movement. This model has been validated on 11 species sampling the phylogeny of land angiosperms, and on organs of very contrasted sizes, ranging from the small germination of wheat (coleoptile) to the trunk of poplar trees. Further studies have shown that the cellular mechanism of proprioception in plants involves myosin and actin, and seems to occur in specialized cells. Proprioception was then found to be involved in other tropisms and to be central also to the control of nutation.
=== Zeolitic imidazolate frameworks (ZIFs) === Several different mechanical phenomena have been observed in zeolitic imidazolate frameworks (ZIFs), the most widely studied MOF for mechanical properties due to their many similarities to zeolites. General trends for the ZIF family are the tendency of the Young's modulus and hardness of the ZIFs to decrease as the accessible pore volume increases. The bulk moduli of ZIF-62 series increase with the increasing of benzoimidazolate (bim−) concentration. ZIF-62 shows a continuous phase transition from open pore (op) to close pore (cp) phase when bim− concentration is over 0.35 per formular unit. The accessible pore size and volume of ZIF-62-bim0.35 can be precisely tuned by applying adequate pressures. Another study has shown that under hydrostatic loading in solvent the ZIF-8 material expands as opposed to contracting. This is a result of hyperfilling of the internal pores with solvent. A computational study demonstrated that ZIF-4 and ZIF-8 materials undergo a shear softening mechanism with amorphizing (at ~ 0.34 GPa) of the material under hydrostatic loading, while still possessing a bulk modulus on the order of 6.5 GPa. Additionally, the ZIF-4 and ZIF-8 MOFs are subject to many pressure dependent phase transitions.
Sunday, February 27, 1955, began with some delegations on a tour of Morro Castle. After this, a parade proceeded down Avenida Carlos III from Infanta Street to Belascoaín. 40,000 people from Havana lined the streets to watch the parade go by. A grandstand reserved for visiting Freemasons with seating for 1,000 people was placed in front of the Masonic Temple. The flags of each country present were raised on flagpoles in front of the Masonic Temple. A rouse of applause was heard from the crowds of people in the street as they saw the flags raised. A large Cuban flag 30 meters (98 feet) long, gifted by the Cuban Young Hope Association (AJEF), was then unfurled and draped over the side of the Masonic Temple. The flag ceremonies were conducted by an Ajefista Commission of the AJEF. The consecration of the National Masonic Temple of the Grand Lodge of Cuba was overseen by Grand Master Carlos M. Piñeiro del Cueto and his secretariat. With a ribbon cutting, members of the public and Cuban Freemasons were allowed to see the building and walk around. The Freemasons moved into the High Chamber of the Grand Lodge, where the Third Inter-American Conference of Symbolic Freemasonry officially took place. Alejandro Poletti from the delegation of Mexico presided over the conference, but because of a recent accident he could not speak well. Alejandro Serani Burgos, from the Grand Lodge of Chile, spoke for some time, explaining more about the significance of the group of statues that the Chilean delegation had brought from Cuba, which were an exact replica of those located on the Alameda.
== Alternative PDRN sources == Variability in biological sources and production methods have shown to contribute to variations in biological activity of PDRN, more specifically with celullar pathways activation. As a results, alternative sources of PDRN are an ongoing research field that aims to better identify alternative sources with their associated effects. In addition to the standard animal-derived PDRN, there are other alternatives like plant, microbial and human-derived PDRN that have been studied to improve sustainbility and efficiency depending on the tissue model. These alternative sources gained more interest since low-molecular weight PDRN is related to better bioavailability, celullar uptake and skin penetration. Most alternative-source preparations contain DNA fragments with lower molecular weight than the animal-derived PDRN.
Sources: en.wikipedia.org
Positively charged ions were found to accumulate in the membrane. Multi-parametric surface plasmon resonance is one of the methods to study barrier properties of natural, modified or coated nanocellulose. The different antifouling, moisture, solvent, antimicrobial barrier formulation quality can be measured on the nanoscale. The adsorption kinetics as well as the degree of swelling can be measured in real-time and label-free.
In 1852, the British signed the Sand River Convention with the Boers, banning the sale of guns to Africans, while continuing to trade between themselves under the terms of the 1854 Bloemfontein Convention. The Boer Orange Free State was able to procure modern breech-loading rifles and a small amount of artillery. The Basuto were forced to rely on smuggled and locally-produced gunpowder, which was of inferior quality. In 1858, hostilities broke out between the Basuto and the Orange Free State. Inferior in both marksmanship and materiel, the Basuto suffered a series of defeats in wars that lasted until 1868. In 1866, the two sides signed the Treaty of Thaba Bosiu, whereby Moshoeshoe ceded most of his kingdom's arable land to the Boers. Hostilities resumed soon afterwards, and the Boers began employing a scorched earth policy, leading to starvation among the Basuto. The Basuto appealed to British High Commissioner for Southern Africa Sir Philip Wodehouse and the Colony of Natal for protection. Although, initially reluctant to intervene, on 12 March 1868 Wodehouse proclaimed Basutoland to be a royal dominion. The Basuto, who became part of the British Empire out of necessity, viewed any kind of colonial administration as "a snake in the house". The British saw it as their responsibility to westernize their new subjects. Wodehouse therefore supported a gradual introduction of colonial laws, so as not to provoke backlash from the Basuto. Basutoland's legal status remained unclear, with the Colonial Office at various times calling it a crown colony and a protectorate.
The hot water supply hose of the umbilical is commonly 1⁄2 inch (13 mm) bore, and is connected to a supply manifold at the right hip of the suit with a set of valves which allow the diver to control flow to the front and back of the torso, and to the arms and legs, and to dump the supply to the environment if the water is too hot or too cold. The manifold distributes the water through the suit through perforated tubes. The hot-water suit is normally a one-piece neoprene wetsuit, fairly loose fitting, to fit over a neoprene undersuit, which can protect the diver from scalding if the temperature control system fails, with a zipper on the front of the torso and on the lower part of each leg. Gloves and boots are worn which receive hot water from the ends of the arm and leg hoses. If a full-face mask is worn, the hood may be supplied by a tube at the neck of the suit. Helmets do not require heating. The heating water flows out at the neck and cuffs of the suit through the overlap with gloves, boots, or hood.
Sources: en.wikipedia.org
Reports describe effects on GABA-A receptor expression, monoamine turnover, and neurotrophic factor levels. These are proposed mechanisms drawn mainly from animal models. No single molecular target has been established.
Intranasal delivery is the route described in most published work. It is used because the peptide is degraded quickly once it reaches circulation. Direct evidence of brain penetration in humans is lacking.
Most trials are small, regionally concentrated, and often lack rigorous blinding or placebo control. Independent replication is limited. Reviews in English generally rate the evidence as preliminary.
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.