certificate of analysis raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
Reviewed 2025-10-06. Anything still debated is marked as such rather than presented as settled.
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.
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.
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.
| 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 |
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.
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.
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.
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.
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.
== Interactions == No interaction studies with this substance have been performed. Interactions with systemic (for example, oral) drugs are considered unlikely because bimatoprost does not reach relevant concentrations in the bloodstream. Bimatoprost does not negatively interact with timolol eye drops.
The Rhizoplaca melanophthalma complex (rock-posy lichens) illustrates this complexity. Formerly treated as one circumpolar species with variable forms, the group is now recognized as several genetically distinct but partly hybridising species. Keuler and colleagues (2020) used genome-scale data and detected at least three historic hybridisation events. Network analysis showed that one lineage, Rhizoplaca shushanii, arose from hybridisation between R. melanophthalma and R. parilis and that low-level gene flow still occurs among some lineages. The hybrids lineages have unusual traits: R. shushanii is an alpine endemic with a distinct appearance, and two other lineages that were involved in introgression (gene flow between species) (R. haydenii and R. arbuscula) are vagrant forms that do not attach to rock but blow around on soil and reproduce only asexually. The study found discordance between nuclear and mitochondrial DNA trees (mitochondria from one species had introgressed into another), and the authors suggest that hybridization events might be linked to the loss of sexual reproduction and the evolution of these unusual, unattached growth forms. Systematically, the case shows that species boundaries can be porous and that reticulate evolution must be tested—single-locus barcodes can mislead when hybridisation is present. It also shows why relying on a single genetic locus (such as the ITS barcode alone) can be misleading: different genes in the same organisms have different histories if hybrids are involved.
The public expected Jonas Salk or Albert Sabin to receive the prize for their development of the polio vaccines, but instead the award went to John Enders, Thomas Weller, and Frederick Robbins whose basic discovery that the polio virus could reproduce in monkey cells in laboratory preparations made the vaccines possible. Through the 1930s, there were frequent prize laureates in classical physiology, but after that, the field began fragmenting into specialities. The last classical physiology laureates were John Eccles, Alan Hodgkin, and Andrew Huxley in 1963 for their findings regarding "unitary electrical events in the central and peripheral nervous system."
Preliminary 2021 calculations predicted that flerovium should have melting point −73 °C (lower than mercury at −39 °C and copernicium, predicted 10 ± 11 °C) and boiling point 107 °C, which would make it a liquid metal. Like mercury, radon, and copernicium, but not lead and oganesson (eka-radon), flerovium is calculated to have no electron affinity. A 2010 study published calculations predicting a hexagonal close-packed crystal structure for flerovium due to spin–orbit coupling effects, and a density of 9.928 g/cm3, though this was noted to be probably slightly too low. Newer calculations published in 2017 expected flerovium to crystallize in face-centred cubic crystal structure like its lighter congener lead, and calculations published in 2022 predicted a density of 11.4 ± 0.3 g/cm3, similar to lead (11.34 g/cm3). These calculations found that the face-centred cubic and hexagonal close-packed structures should have nearly the same energy, a phenomenon reminiscent of the noble gases. These calculations predict that hexagonal close-packed flerovium should be a semiconductor, with a band gap of 0.8 ± 0.3 eV. (Copernicium is also predicted to be a semiconductor.) These calculations predict that the cohesive energy of flerovium should be around −0.5 ± 0.1 eV; this is similar to that predicted for oganesson (−0.45 eV), larger than that predicted for copernicium (−0.38 eV), but smaller than that of mercury (−0.79 eV).
== Research == Vladimir Dilman first proposed in 1971 that biguanides like metformin and phenformin may have potential to treat cancer, prevent cancer, and to extend life, an idea that was subsequently supported by in vitro and animal studies, as well as an apparent reduction in the incidence of cancer in people taking metformin for diabetes. Laboratory studies attribute these apparent effects to inhibition of mTOR, inhibition of complex I, with phenformin being a more potent inhibitor than metformin, It appears that inhibition of complex I may cause diminished TCA cycle intermediate production and decreased mitochondrial ATP production thus resulting in AMPK activation and lower mTOR activity.
Sources: en.wikipedia.org
By 9 November 2011, Houthis were said to be in control of two Yemeni governorates (Saada and Al Jawf) and close to taking over a third governorate (Hajjah), which would enable them to launch a direct assault on the Yemeni capital of Sanaa. In May 2012, it was reported that the Houthis controlled a majority of Saada, Al Jawf, and Hajjah governorates; they had also gained access to the Red Sea and started erecting barricades north of Sanaa in preparation for more conflict.
In April 2021 Noakes pleaded guilty in France to manufacturing and selling fake medicinal products and cosmetics by Internet and sentenced to 4 years of jail. A 2019 Business Insider report detailed the activities of Amanda Mary Jewell, who sold GcMAF for years as an unlicensed cure for several medical conditions, including cancer and autism. Jewell is not a medical doctor.
=== The Manhattan Project === Nier returned to Minnesota in 1938 to be near his ageing parents. In 1940, on the request of Enrico Fermi, he and a few students, including Edward Ney, prepared a pure sample of uranium-235 using an early mass spectrograph designed by Nier, for John R. Dunning's team at Columbia University. On the day of its receipt (it was sent by US Postal Mail), Dunning's team was able to demonstrate that uranium-235 was the isotope responsible for nuclear fission, rather than the more abundant uranium-238. Confirmation of this suspected fact was a critical step in the development of the atomic bomb. From 1943 to 1945, Nier worked with Kellex Corporation in Manhattan, New York City on the design and development of efficient and effective mass spectrographs for use in the Manhattan Project to build the atomic bomb in World War II. During the war most of the spectrographs used for monitoring uranium separations were designed by Nier.
=== 2011–2016: The Devil Put Dinosaurs Here === On March 21, 2011, Alice in Chains announced that they were working on a fifth studio album, and both Cantrell and Inez later made statements that they had begun the recording process. The album was expected to be finished by summer of 2012 and released by the end of 2012 or beginning of 2013. While Alice in Chains were writing for the album in 2011, Cantrell underwent surgery on his right shoulder, which delayed recording the new material. In an interview published in May 2012, Cantrell explained, "The thing that set me back is I had some bone spurs [and] cartilage issues in my shoulders. I had the same issue in the other shoulder about six years ago so I've had them both done now. It's a repetitive motion injury from playing." Cantrell could not play guitar for eight months while he was recovering from surgery. While recuperating at home in a sling, Cantrell heard a riff in his head and sang it into his phone. The riff later became the song "Stone". Alice in Chains played their first concert in nearly 10 months and their first concert after Cantrell's shoulder surgery at the Winstar Casino in Thackerville, Oklahoma on August 13, 2011. The band's only concert in 2012 was a five-song acoustic set on May 31 at the eighth annual MusiCares MAP Fund Benefit Concert honoring Jerry Cantrell.
Sources: en.wikipedia.org
== Mechanism of action == Brimonidine is an α2 adrenergic agonist. Peripheral α2 agonist activity results in vasoconstriction of blood vessels (as opposed to central α2 agonist activity that decreases sympathetic tone, as can be seen by the medication clonidine). This vasoconstriction may explain the acute reduction in aqueous humor flow. The increased uveoscleral outflow from prolonged use may be explained by increased prostaglandin release due to α adrenergic stimulation. This may lead to relaxed ciliary muscle and increased uveoscleral outflow.
=== Cyberwarfare and cyber sanctions === In addition to retaliatory digital attacks, countries can respond to cyber attacks with cyber sanctions. Sometimes, it is not easy to detect the attacker, but suspicions may focus on a particular country or group of countries. In these cases, unilateral and multilateral economic sanctions can be used instead of cyberwarfare. For example, the United States has frequently imposed economic sanctions related to cyber attacks. Two Executive Orders issued during the Obama administration, EO 13694 of 2015 and EO 13757 of 2016, specifically focused on the implementation of the cyber sanctions. Subsequent US presidents have issued similar Executive Orders. The US Congress has also imposed cyber sanctions in response to cyberwarfare. For example, the Iran Cyber Sanctions Act of 2016 imposes sanctions on specific individuals responsible for cyber attacks.
== Nutrition and growth == Yeasts are chemoorganotrophs, as they use organic compounds as a source of energy and do not require sunlight to grow. Carbon is obtained mostly from hexose sugars, such as glucose and fructose, or disaccharides such as sucrose and maltose. Some species can metabolize pentose sugars such as ribose, alcohols, and organic acids. Yeast species either require oxygen for aerobic cellular respiration (obligate aerobes) or are anaerobic, but also have aerobic methods of energy production (facultative anaerobes). Unlike bacteria, no known yeast species grow only anaerobically (obligate anaerobes). Most yeasts grow best in a neutral or slightly acidic pH environment. Yeasts vary in regard to the temperature range in which they grow best. For example, Leucosporidium frigidum grows at −2 to 20 °C (28 to 68 °F), Saccharomyces telluris at 5 to 35 °C (41 to 95 °F), and Candida slooffi at 28 to 45 °C (82 to 113 °F). The cells can survive freezing under certain conditions, with viability decreasing over time. In general, yeasts are grown in the laboratory on solid growth media or in liquid broths. Common media used for the cultivation of yeasts include potato dextrose agar or potato dextrose broth, Wallerstein Laboratories nutrient agar, yeast peptone dextrose agar, and yeast mould agar or broth. Home brewers who cultivate yeast frequently use dried malt extract and agar as a solid growth medium. The fungicide cycloheximide is sometimes added to yeast growth media to inhibit the growth of Saccharomyces yeasts and select for wild/indigenous yeast species.
Thalassemias were first identified in severely sick children in 1925, with identification of alpha and beta subtypes in 1965. Alpha thalassemia has its greatest prevalence in populations originating from Southeast Asia, Mediterranean countries, Africa, the Middle East, India, and Central Asia. Having a mild form of alpha thalassemia has been demonstrated to protect against malaria and thus can be an advantage in malaria endemic areas.
Functional Genomics Data (FGED) Society Formerly known by the abbreviation MGED. An organization that works with others "to develop standards for biological research data quality, annotation and exchange" as well as software tools that facilitate their use.
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.
Dry powder is best kept sealed, protected from light, and held at minus 20 degrees Celsius or below. Desiccant packaging helps limit moisture uptake because the material is hygroscopic. A sealed vial should be allowed to equilibrate to room temperature before opening to reduce condensation.