This is a working overview of Lyophilisation, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2026-05-28 and is reviewed periodically as new material appears.
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.
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.
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.
Selank is a synthetic heptapeptide developed in Russia. Its sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, a seven-residue chain built around the natural tetrapeptide tuftsin. Researchers at the Institute of Molecular Genetics of the Russian Academy of Sciences first described the compound in the mid-1990s. The design combined the tuftsin core with an added Pro-Gly-Pro tail, a modification intended to extend the molecule's stability in biological fluids. Published work on the peptide has appeared mainly in Russian-language journals.
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.
| Property | Value | Notes |
|---|---|---|
| Common route | Intranasal | Also injected in some animal work |
| Solubility class | Freely soluble in water | Solid form is hygroscopic |
| Typical storage | About -20 degrees Celsius | Keep desiccated and dark |
| Purity method | Reverse-phase HPLC | Reported as area percent |
| Confirmatory method | Mass spectrometry | Verifies expected molecular mass |
Lyophilized Selank, the dry powder form, is generally stored frozen at minus 20 degrees Celsius or colder for long-term keeping. The solid is hygroscopic and should stay sealed, dry, and protected from light. Once dissolved, the peptide is less stable and is usually held refrigerated at 2 to 8 degrees Celsius for short periods. Repeated freezing and thawing is avoided because it can promote aggregation and loss of activity. Buffers and pH choice also affect how long a solution remains usable.
Solubility behavior is a practical concern for handling. Selank dissolves readily in water and in common aqueous buffers, which simplifies preparation of working solutions. The choice of solvent, ionic strength, and pH can influence aggregation over time, particularly at higher concentrations. Aqueous solutions are typically sterile-filtered before use. Because stability depends on several variables, storage and handling notes should be treated as general guidance rather than fixed rules, and specific values are best confirmed against a certificate of analysis for each batch.
Characterization of Selank in a laboratory setting relies on standard peptide methods. Reverse-phase high-performance liquid chromatography separates the target from related impurities and provides a purity figure, commonly reported as 95 percent or higher. Mass spectrometry, typically electrospray ionization or matrix-assisted laser desorption, confirms the molecular mass and helps detect truncation or modification. Amino acid analysis can verify composition when a sequence-level check is needed. These techniques together establish identity and purity for a given lot.
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.
Lyophilised material kept dry at minus 20 degrees Celsius or colder is the most stable form, and suppliers commonly state a shelf life of two years or more under those conditions. Once dissolved, degradation accelerates through hydrolysis and deamidation, particularly at alkaline pH or elevated temperature. Working solutions are usually divided into single-use aliquots to avoid repeated freeze-thaw cycles. The choice of reconstitution solvent affects both stability and the ionic strength of the final preparation.
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.
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.
=== Hydration === Rattlesnakes are believed to require at least their own body weight in water annually to remain hydrated. The method by which they drink depends on the water source. In larger bodies of water (streams, ponds, etc.), they submerge their heads and ingest water by opening and closing their jaws, which sucks in water. If drinking dew or small puddles, they sip the liquid either by capillary action or by flattening and flooding their lower jaws. In desert environments, scientists observe that rattlesnakes have evolved to stay hydrated by coiling up and flattening so that their bodies can collect rain. In some instances, they aggregated in a carpet-like formation to make a larger rain-collecting platform.
=== Abuse of LGBTQ+ people === According to Amnesty International on 9 February 2024, two Houthi-run courts in Yemen sentenced 48 individuals either to death, flogging, or prison over charges related to same-sex conduct in the past month.
=== Nobel Prizes for vitamin research === The Nobel Prize for Chemistry for 1928 was awarded to Adolf Windaus "for his studies on the constitution of the sterols and their connection with vitamins", the first person to receive an award mentioning vitamins, even though it was not specifically about vitamin D. The Nobel Prize in Physiology or Medicine for 1929 was awarded to Christiaan Eijkman and Frederick Gowland Hopkins for their contributions to the discovery of vitamins. Thirty-five years earlier, Eijkman had observed that chickens fed polished white rice developed neurological symptoms similar to those observed in military sailors and soldiers fed a rice-based diet, and that the symptoms were reversed when the chickens were switched to whole-grain rice. He called this "the anti-beriberi factor", which was later identified as vitamin B1, thiamine. In 1930, Paul Karrer elucidated the correct structure for beta-carotene, the main precursor of vitamin A, and identified other carotenoids. Karrer and Norman Haworth confirmed Albert Szent-Györgyi's discovery of ascorbic acid and made significant contributions to the chemistry of flavins, which led to the identification of lactoflavin. For their investigations on carotenoids, flavins and vitamins A and B2, they both received the Nobel Prize in Chemistry in 1937. In 1931, Albert Szent-Györgyi and a fellow researcher Joseph Svirbely suspected that "hexuronic acid" was actually vitamin C, and gave a sample to Charles Glen King, who proved its ability to counter scurvy in his long-established guinea pig scorbutic assay.
== Biography == Langevin received an MD degree from McGill University in 1978. She did a post doctoral research fellowship in Neurochemistry at the MRC Neurochemical Pharmacology Unit in Cambridge, England, a residency in Internal Medicine and a fellowship in Endocrinology and Metabolism at Johns Hopkins Hospital. She was a Professor in Residence of Medicine at Harvard Medical School, Brigham and Women's Hospital. She was also a part-time Professor of Neurology, Orthopedics and Rehabilitation at the University of Vermont College of Medicine. She was the Principal Investigator of two NIH-funded studies investigating the role of connective tissue in low back pain and the mechanisms of manual and movement based therapies. Her previous studies in humans and animal models have found that "needle grasp", the biomechanical component of de qi, may be caused by connective tissue winding around the needle. Helene Langevin was appointed as Director of the Osher Center for Integrative Medicine at Harvard Medical School and Brigham and Women's Hospital in November 2012.
On December 31, 2019, due to safety concerns, Brady was transferred to the USP Big Sandy, a federal prison in Kentucky. In 2021, Brady was transferred to ADX Florence, a supermax federal prison in Colorado. As of 2025, Brady remains incarcerated at Florence.
Sources: en.wikipedia.org
Alkynylstannanes, the most reactive of stannanes, have also been used in Stille couplings. They are not usually needed as terminal alkynes can couple directly to palladium catalysts through their C-H bond via Sonogashira coupling. Allylstannanes have been reported to have worked, yet difficulties arise, like with allylic halides, with the difficulty in control regioselectivity for α and γ addition. Distannane and acyl stannane reagents have also been used in Stille couplings.
6Li + n → 4He + 3H Tritium has a half-life 4500±8 days (approximately 12.32 years) and it decays by beta decay. The electrons produced have an average energy of 5.7 keV. Because the emitted electrons have relatively low energy, the detection efficiency by scintillation counting is rather low. However, hydrogen atoms are present in all organic compounds, so tritium is frequently used as a tracer in biochemical studies.
== References == Aeschliman, M.D (28 March 2005). "Murderous Science". The National Review. Vol. LVII, no. 5. pp. 49–50. Baldwin, Peter (1990). Reworking the Past: Hitler, the Holocaust, and the Historians' Debate. Boston: Beacon Press. Bessel, Richard (August 1990). "Detlev J.K. Peukert". German History. 8 (3): 321–324. doi:10.1093/gh/8.3.321. Crew, David (May 1992). "The Pathologies of Modernity: Detlev Peukert on Germany's Twentieth Century". Social History. 17 (2): 319–328. doi:10.1080/03071029208567840. Kater, Michael (May 1992). "Conflict in Society and Culture: The Challenge of National Socialism". German Studies Review. 15 (2): 289–294. doi:10.2307/1431167. JSTOR 1431167. Kershaw, Ian (2000). The Nazi Dictatorship Problems and Perspectives of Interpretation. London: Arnold Press. ISBN 0-340-76028-1. Lindemann, Albert (February 1982). "Review of Die KPD im Widerstand Verfolgung und Untergrundarbeit am Rhein und Ruhr, 1933-1945". The American Historical Review. 82 (1): 205. doi:10.2307/1863393. JSTOR 1863393. Nolan, Mary (Spring–Summer 1988). "The Historikerstreit and Social History". New German Critique (44): 1–80. Pendas, Devin; Roseman, Mark (2017). Beyond the Racial State: Rethinking Nazi Germany. Cambridge: Cambridge University Press. ISBN 978-1107165458. Peukert, Detlev (1987). Conformity, Opposition and Racism in Everyday Life. New Haven: Yale University Press. ISBN 0300038631. Peukert, Detlev (1994). "The Genesis of the 'Final Solution' from the Spirit of Science". In Thomas Childers; Jane Caplan (eds.). Reevaluating the Third Reich. New York: Holmes & Meier.
== Etymology == The word "cirrhosis" is a neologism derived from Greek: κίρρωσις; kirrhos κιρρός, meaning "yellowish, tawny" (the orange yellow colour of the diseased liver) and the suffix -osis, i.e., "condition" in medical terminology. While the clinical entity was known before, René Laennec gave it this name in an 1819 paper.
Sources: en.wikipedia.org
In Kenya, the Ministry of Education controls all public universities. Students enroll after completing an 8–4–4 educational program system and attaining a mark of C+ or above. Students who meet the criteria set annually by the Kenya Universities and Colleges Central Placement Service receive government sponsorship, with the government providing part of their university or college fees. Students are also eligible for a low-interest loan from the Higher Education Loan Board; students must pay back the loan after completing their higher education.
It is typical to record spectrum of both the sample and a "reference". This step controls for a number of variables, e.g. infrared detector, which may affect the spectrum. The reference measurement makes it possible to eliminate the instrument influence. The appropriate "reference" depends on the measurement and its goal. The simplest reference measurement is to simply remove the sample (replacing it by air). However, sometimes a different reference is more useful. For example, if the sample is a dilute solute dissolved in water in a beaker, then a good reference measurement might be to measure pure water in the same beaker. Then the reference measurement would cancel out not only all the instrumental properties (like what light source is used), but also the light-absorbing and light-reflecting properties of the water and beaker, and the final result would just show the properties of the solute (at least approximately). A common way to compare to a reference is sequentially: first measure the reference, then replace the reference by the sample and measure the sample. This technique is not perfectly reliable; if the infrared lamp is a bit brighter during the reference measurement, then a bit dimmer during the sample measurement, the measurement will be distorted. More elaborate methods, such as a "two-beam" setup (see figure), can correct for these types of effects to give very accurate results. The Standard addition method can be used to statistically cancel these errors.
== Changes for 2020 exam == The Central Board of Secondary Education (CBSE) has been conducting two separate Mathematics examinations in the class 10 board examination, starting from the 2020 session. Mathematics exam till 2019 was Mathematics (Standard), and an easier version, Mathematics (Basic), has been introduced. The option to choose mathematics is available on the registration form for the Class 10 CBSE board examination. Candidates are required to select their test choice while filling out the registration form for the CBSE Class 10 board examination 2020. Minister of Education, MoE (previously Minister of Human Resource Department, HRD), amid the coronavirus outbreak had ordered rescheduling of pending examinations. The exams rescheduled were to be conducted between 1 and 15 July. On 26 June, CBSE released as circular which cancelled the remaining exams and give scores based on the scores of the exams already taken by students. Some students of Delhi who were able to provide three or fewer exams were scored as per their performance in internal exams. This decision came after a judicial ruling.
Sources: en.wikipedia.org
Most published work uses intranasal application, either as drops or as a nasal spray. Injection routes appear in a smaller set of animal experiments. Oral use is uncommon in the literature because peptide breakdown and poor absorption limit this route.
Reported human trials are few, brief and originate mainly from one country. They describe effects on anxiety-related measures, but sample sizes are small and reporting is limited. The results are widely regarded as preliminary rather than confirmed.
Reverse-phase liquid chromatography is used to assess purity and separation of related impurities. Mass spectrometry confirms that the observed molecular mass matches the expected peptide. A certificate of analysis from the supplier is the usual document of record.
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.