Everything below concerns tuftsin. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2025-08-03. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
Reported activity for Selank centers on anxiolytic and nootropic effects. Russian clinical reports describe use in anxiety and in cognitive or attention-related complaints. Most of this evidence comes from studies conducted by the same research groups that developed the peptide. Independent replication in other countries remains limited, and no major Western regulatory agency has approved the compound for any indication. The gap between local reports and external verification is a recurring point in discussions of the peptide.
Tuftsin, the parent structure, is a naturally occurring immunomodulatory tetrapeptide released from the Fc region of immunoglobulin G by spleen enzymes. Selank extends this four-residue sequence with three additional amino acids. The stated rationale is that the added tail slows enzymatic breakdown and may influence receptor interactions. How the full heptapeptide behaves at the molecular level is not firmly established, and proposed mechanisms often involve indirect modulation of neurotransmitter or immune signaling rather than a single defined target.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white powder | Lyophilised solid form |
| Solubility class | Freely soluble in water | Hydrophilic heptapeptide |
| Dry storage temperature | -20 degrees Celsius or lower | Sealed, desiccated, protected from light |
| Solution storage | 2 to 8 degrees Celsius short term | Avoid repeated freeze-thaw cycles |
| Common identification method | Reversed-phase HPLC with mass spectrometry | Confirms purity and molecular mass |
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.
Pharmacokinetic data are limited. Like most short peptides, Selank is vulnerable to plasma and tissue peptidases, and its measured half-life in circulation is short, on a minutes scale. The Pro-Gly-Pro tail slows this degradation but does not eliminate it. Intranasal administration is the route described in most reports, with absorption through the nasal mucosa and a hypothesized path into the central nervous system that avoids the blood-brain barrier. Direct measurements of human brain exposure are unavailable, so distribution claims rest on inference from animal work.
Selank is a synthetic heptapeptide developed in Russia as a structural analogue of tuftsin, a naturally occurring immunomodulatory tetrapeptide. Its sequence, Thr-Lys-Pro-Arg-Pro-Gly-Pro, keeps the tuftsin core at the N-terminus and appends a Pro-Gly-Pro tail. Researchers at the Institute of Molecular Genetics in Moscow synthesized the compound during the 1990s while searching for peptides with combined anxiolytic and immunomodulatory activity. The added tail was intended to resist enzymatic cleavage and prolong the molecule's presence in circulation.
The compound has a calculated molecular weight near 751.9 daltons and carries a net positive charge at physiological pH because of its arginine residue. It dissolves freely in water and in common aqueous buffers, and typically appears as a white or off-white lyophilized powder. The amide backbone makes the molecule susceptible to peptidases, which limits oral use and favors intranasal or parenteral routes. Nomenclature in the literature varies: the substance is also described by the sequence abbreviation TP-7 and by a Russian trade designation.
Regulatory status differs sharply by region. Selank holds a Russian marketing authorization, where it is supplied mainly as nasal drops, while authorities elsewhere have not approved it for medical use. Material sold internationally is therefore usually labeled as a research chemical rather than a medicine. Peer-reviewed publications come predominantly from Russian laboratories, and sample sizes are generally small. Whether the compound produces comparable effects under independent, well-controlled replication remains an open question that the broader literature has not settled.
Structural biology is concerned with the structural analysis of biological material at every level of organization. During the 19th and early 20th centuries, structural studies were largely limited to structures visible to the naked eye or through magnifying glasses and light microscopes. In the 20th century, a variety of experimental techniques were developed to examine the 3D structures of biological molecules. The most prominent techniques are X-ray crystallography, nuclear magnetic resonance, and electron microscopy. The discovery of X-rays and their application to protein crystals transformed structural biology by allowing researchers to determine the three-dimensional structures of biological molecules in atomic detail. Likewise, NMR spectroscopy allowed information about protein structure and dynamics to be obtained. Finally, in the 21st century, electron microscopy also saw a drastic revolution with the development of more coherent electron sources, aberration correction for electron microscopes, and reconstruction software that enabled the successful implementation of high resolution cryo-electron microscopy, thereby permitting the study of individual proteins and molecular complexes in three-dimensions at angstrom resolution.
== Tissue distribution == COL21A1 is expressed in a broad range of tissues, including skin, trachea, testis, uterus, placenta, lymph node, stomach and the walls of blood vessels, generally overlapping the distribution of type I collagen. Among these, relative expression is highest in lymph node, jejunum, pancreas, stomach, trachea, testis, uterus and placenta; moderate levels are found in brain, colon, lung, prostate, spinal cord, salivary gland and vascular smooth-muscle cells; and expression is weak in heart, liver, kidney, bone marrow, spleen and thymus. COL21A1 expression is developmentally regulated, being higher at fetal stages than in the corresponding adult tissues. In a comparison of matched human tissues, COL21A1 transcripts were approximately 2.7-, 22- and 30-fold more abundant in fetal brain, heart and liver, respectively, than in their adult counterparts, suggesting a role in developmental processes. In cultured aortic smooth-muscle cells, expression of COL21A1 is stimulated by platelet-derived growth factor (PDGF). Its presence in the walls of blood vessels, where it is produced by smooth-muscle cells, was noted in the original characterization of the gene. Type XXI collagen is also expressed in human skin, where it is a low-abundance component of the dermal extracellular matrix, as detected by quantitative proteomics of healthy skin. In a time-resolved proteomic atlas of the developing skin dermis, type XXI collagen was among the fibril-associated collagens whose abundance declined progressively with age over the human lifespan.
Flattened squamous cells are more resistant to both abrasion and infection. The permeability of the epithelium allows for an effective response from the immune system since antibodies and other immune components can easily reach the surface. The vaginal epithelium differs from the similar tissue of the skin. The epidermis of the skin is relatively resistant to water because it contains high levels of lipids. The vaginal epithelium contains lower levels of lipids. This allows the passage of water and water-soluble substances through the tissue. Keratinization happens when the epithelium is exposed to the dry external atmosphere. In abnormal circumstances, such as in pelvic organ prolapse, the mucosa may be exposed to air, becoming dry and keratinized.
China is a leading producer of indium (290 tonnes in 2016), followed by South Korea (195 t), Japan (70 t) and Canada (65 t). The Teck Resources refinery in Trail, British Columbia, is a large single-source indium producer, with an output of 32.5 tonnes in 2005, 41.8 tonnes in 2004 and 36.1 tonnes in 2003. The primary consumption of indium worldwide is LCD production. Demand rose rapidly from the late 1990s to 2010 with the popularity of LCD computer monitors and television sets, which now account for 50% of indium consumption. Increased manufacturing efficiency and recycling (especially in Japan) maintain a balance between demand and supply. According to the UNEP, indium's end-of-life recycling rate is less than 1%.
Sources: en.wikipedia.org
=== Relations with Sichuan warlords and the central government === Part of Liu Wenhui's success stemmed from his connections with other Sichuan warlords who were also graduates of Baoding, including Deng Xihou and Tian Songyao, who stood in contrast with Liu Xiang and Yang Sen, who went to the Sichuan Army Accelerated Training School. Although Liu Wenhui was younger than his competitors, he was able to rise to power faster. By 1932, Liu controlled 68 out of 147 counties (around 46%) of the province, a position he had built through familial and professional relationships with his nephew Liu Xiang and his colleagues from the "Baoding clique". However, while clique and blood ties are popular with scholars as a means of explaining the different alliances in warlord-era Sichuan, Kim Hee-shin notes that there are undoubtedly more factors that determined the power relations and subsuquent conflicts between different polities. Liu's greatest political fear was that the smaller Sichuan warlords would join a coalition against him, an eventuality that occurred during the Two-Liu War. A sign of the close connection between the Baoding graduates was the fact that from 1925 to 1932, the Sichuanese capital of Chengdu was jointly governed by a triumvirate consisting of Liu Wenhui, Deng Xihou, and Tian Songyao. To assist him in this task, Liu Wenhui appointed a subordinate commander, Xiang Chuanyi to administer Chengdu on his behalf and maintain relations with the other warlords.
Clinical trials designed by a local investigator, and (in the US) federally funded clinical trials, are almost always administered by the researcher who designed the study and applied for the grant. Small-scale device studies may be administered by the sponsoring company. Clinical trials of new drugs are usually administered by a contract research organization (CRO) hired by the sponsoring company. The sponsor provides the drug and medical oversight. A CRO is contracted to perform all the administrative work on a clinical trial. For phases II–IV the CRO recruits participating researchers, trains them, provides them with supplies, coordinates study administration and data collection, sets up meetings, monitors the sites for compliance with the clinical protocol, and ensures the sponsor receives data from every site. Specialist site management organizations can also be hired to coordinate with the CRO to ensure rapid IRB/IEC approval and faster site initiation and patient recruitment. Phase I clinical trials of new medicines are often conducted in a specialist clinical trial clinic, with dedicated pharmacologists, where the subjects can be observed by full-time staff. These clinics are often run by a CRO which specialises in these studies. At a participating site, one or more research assistants (often nurses) do most of the work in conducting the clinical trial.
Heroin-assisted treatment (HAT), or diamorphine-assisted treatment, refers to a type of Medication-Assisted Treatment (MAT) where semi-synthetic heroin is prescribed to opioid addicts who do not benefit from, or cannot tolerate, treatment with one of the established drugs used in opioid replacement therapy such as methadone or buprenorphine/naloxone (brand name Suboxone). For this group of patients, heroin-assisted treatment has proven superior in improving their social and health situation. Heroin-assisted treatment is fully a part of the national health system in Switzerland, Germany, the Netherlands, Canada, and Denmark. Additional trials are being carried out in the United Kingdom, Norway, and Belgium.
Sources: en.wikipedia.org
Dry powder is normally held at -20 degrees Celsius or below in a sealed, light-protected container with desiccant. Brief room-temperature handling during weighing is generally tolerated. Storage instructions vary between suppliers, so the accompanying certificate of analysis should be followed.
Reversed-phase HPLC establishes purity, while mass spectrometry confirms the expected molecular mass. Sequence confirmation may use tandem mass spectrometry or peptide mapping. A certificate of analysis typically reports these results alongside the analytical method applied.
In Russia it is a registered medicine available by prescription. In many other countries it is not approved for human use and is supplied only as a research chemical. Import and possession rules differ by jurisdiction, and buyers are responsible for checking local requirements.
Selank is a synthetic peptide made of seven amino acids. It is modeled on tuftsin, a natural tetrapeptide, with an added three-residue tail. It is not a small-molecule drug.