The short version of freeze-thaw fits in a sentence. The long version — which is the one that helps — is below.
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Naming conventions place Selank in the same research family as Semax, another Russian-developed peptide investigated for cognitive effects. The two compounds share a lineage but differ in sequence and in the biological systems proposed as their targets. Semax descends from ACTH fragments, whereas Selank descends from tuftsin. Publications sometimes identify Selank by its full peptide sequence or by laboratory codes rather than one uniform trade name. Because replication outside Russia is limited, reports on its properties are best read alongside the study design and the purity of the material tested.
Selank is a synthetic heptapeptide developed in Russia during the 1990s. Researchers at the Institute of Molecular Genetics of the Russian Academy of Sciences designed it as a stabilized analog of tuftsin, a naturally occurring immunomodulatory tetrapeptide. The compound has been studied primarily for its reported anxiolytic and nootropic effects. It remains largely unknown in Western pharmacology and is not approved as a medicine by major regulators such as the FDA or the EMA.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular class | Synthetic heptapeptide | Stabilized analog of tuftsin |
| Sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Single-letter form: TKPRPGP |
| Molecular formula | C33H57N11O9 | Monoisotopic mass about 751.9 Da |
| Appearance | White to off-white powder | Typically supplied as lyophilized solid |
| Solubility | Freely soluble in water | Also soluble in common polar solvents |
Reversed-phase high-performance liquid chromatography is the standard technique for estimating peptide purity. The result is a peak-area percentage, which describes how much of the detected material elutes as the main peak in one run. Mass spectrometry confirms the molecular mass and can reveal truncated, adducted, or otherwise modified species. Amino acid analysis or tandem mass spectrometry can address sequence fidelity when identity is in doubt. None of these measurements, taken alone, establishes that a sample is fit for any specific purpose.
Lyophilized selank is normally supplied as a dry powder and is considered stable for extended periods when kept cold and dry. Moisture uptake is the main practical threat, because absorbed water promotes both hydrolysis and aggregation in the solid state. Vials are usually warmed to room temperature before opening so that condensation does not form on the powder. Supplier documentation commonly specifies -20 °C for routine storage, with -80 °C used for material intended to be archived for years.
Development work on the compound began in the 1980s and 1990s at the Institute of Molecular Genetics in Moscow, within the same research programme that produced the peptide Semax. Early investigators sought a tuftsin derivative with improved resistance to enzymatic breakdown and with activity in the central nervous system after peripheral administration. Most of the primary literature from this period was published in Russian, a factor that still shapes how easily the findings can be checked by outside groups.
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.
Reported pharmacological effects center on reduced anxiety-like behavior in animal models and on measures of memory and learning. Proposed contributing mechanisms include modulation of GABAergic signaling, shifts in monoamine turnover, and changes in the activity of enzymes that degrade neuropeptides. Effects on the expression of genes linked to neuroplasticity have also been described. No single molecular target is widely accepted, and whether the behavioral findings arise from one pathway or several remains an open question.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. It was designed as a stabilized analogue of tuftsin, a naturally occurring tetrapeptide fragment derived from the immunoglobulin heavy chain. The additional Pro-Gly-Pro segment at the carboxyl terminus is intended to slow enzymatic cleavage. The compound is usually described in the literature as a synthetic peptide with anxiolytic and cognitive-related activity, a label that reflects a research context rather than an approved therapeutic category.
=== Ring-fused thiophenes === Fusion of thiophene with a benzene ring gives benzothiophene. Fusion with two benzene rings gives either dibenzothiophene (DBT) or naphthothiophene. Fusion of a pair of thiophene rings gives isomers of thienothiophene.
Defending against a full Russian or Chinese attack would require hundreds of thousands of satellites," according to MIT physicists Lisbeth Gronlund and David Wright. The cost of launching satellites is expected to decrease when the heavy-lift SpaceX Starship launch vehicle enters service. Still, the extreme expense of creating such a constellation—and replacing satellites as their orbits decay—has led the U.S. military to also pursue space-based midcourse options that would require fewer satellites. But these would be more expensive and no better than ground-based interceptors at telling decoys from warheads. Space-based interceptors would be guided by the nascent Hypersonic and Ballistic Tracking Space Sensor system, one of the tracking elements of the Space Development Agency's (SDA) seven-layer Proliferated Warfighter Space Architecture (PWSA). The Golden Dome would also be aimed at detecting and countering strikes delivered from a fractional orbital bombardment system (FOBS). Pentagon leaders have said the system could be used to put offensive weapons in space, giving a global strike capability that would create offensive overmatch. Defense Secretary Pete Hegseth has said the U.S. "will be able to strike anywhere, anytime". Satellites might carry the bunker-busting Common-Hypersonic Glide Body (C-HGB), which can reportedly fly 1,000 miles to strike within 14 inches of its target. The missile was designed to fit the HIMARS ground launcher, so several can be compactly racked in a satellite payload bays.
Proteomic profiling of mouse liver revealed that SIRT5 regulates about 16% of all identified malonyl-lysine sites, the majority of which contain only a single malonylated lysine residue. The proteins regulated in this way are mainly involved in glycolysis, gluconeogenesis, fatty acid oxidation, and the urea cycle. The moderate reduction in malonylation observed upon SIRT5 knockdown in turn suggests the presence of additional, unidentified demalonylases. It has also been proposed that demalonylases and deacetylases function less as dedicated regulatory enzymes and more as part of a protein quality-control mechanism.
The Environmental Investigation Agency in 2016 estimated that 34 species of fish were being traded on the wider Chinese fish maw market. Sciaenidae (croakers/drums) are typically the most valued, due to their similarity to the historically prized and critically endangered Chinese bahaba. Other targeted fishes include eels, stonefishes, lates perch, groupers, threadfins and sturgeon.
Sources: en.wikipedia.org
== Languages == The name international unit is often capitalized in English and other languages, although major English-language dictionaries treat it as a common noun and thus use lower case. The name has several accepted abbreviations. It is usually abbreviated as IU in English, and UI in Romance languages (for example Spanish unidad internacional, Portuguese unidade internacional, French unité internationale, Italian unità internazionale, Romanian unitate internațională), IE in several Germanic languages (for example German internationale Einheit, Dutch internationale eenheid) or as other forms (for example Russian МЕ, международная единица [mezhdunarodnaya yedinitsa], or ЕД, единица действия [yedinitsa deystviya] 'activity unit', Hungarian NE, nemzetközi egység). In order to remove the possibility of having the letter "I" confused with the digit "1", some hospitals have it as a stated policy omit the "I", that is, to only use U or E when talking and writing about dosages, while other hospitals require the word "units" (or words "international units") to be written out entirely. (For example, "three international units per litre" may be abbreviated "3 U/L". The "liter" sign (L) is less affected, as less confusing written forms are used.)
== History == During the 1970s, astronauts ate regular ice cream on the Skylab space station; it has also been eaten on the International Space Station. Skylab had a freezer that was used for regular ice cream, and occasionally Space Shuttle and International Space Station astronauts took regular ice cream into space. Freeze-dried foods were initially developed for the Mercury missions. Despite use of images of space-walking astronauts in space suits on product packaging, freeze-dried ice cream was not included on any mission in which space suits were used. The only evidence for freeze-dried ice cream ever having flown in space is the menu for the Apollo 7 mission, on which it is listed for one of the meals. However, when the only surviving member of Apollo 7 was asked, he did not remember it being served on the flight. According to one NASA food scientist, although freeze-dried ice cream was developed on request, "it wasn't that popular."
Lichens are defined by the International Association for Lichenology to be "an association of a fungus and a photosynthetic symbiont resulting in a stable vegetative body having a specific structure". The fungi, or mycobionts, are mainly from the Ascomycota with a few from the Basidiomycota. In nature, they do not occur separate from lichens. It is unknown when they began to associate. One or more mycobiont associates with the same phycobiont species, from the green algae, except that alternatively, the mycobiont may associate with a species of cyanobacteria (hence "photobiont" is the more accurate term). A photobiont may be associated with many different mycobionts or may live independently; accordingly, lichens are named and classified as fungal species. The association is termed a morphogenesis because the lichen has a form and capabilities not possessed by the symbiont species alone (they can be experimentally isolated). The photobiont possibly triggers otherwise latent genes in the mycobiont. Trentepohlia is an example of a common green alga genus worldwide that can grow on its own or be lichenised. Lichen thus share some of the habitat and often similar appearance with specialized species of algae (aerophytes) growing on exposed surfaces such as tree trunks and rocks and sometimes discoloring them.
Teleosts are economically important in different ways. They are captured for food around the world. A small number of species such as herring, cod, pollock, anchovy, tuna and mackerel provide people with millions of tons of food per year, while many other species are fished in smaller amounts. They provide a large proportion of the fish caught for sport. Commercial and recreational fishing together provide millions of people with employment. A small number of productive species including carp, salmon, tilapia and catfish are farmed commercially, producing millions of tons of protein-rich food per year. in 2016 the UN's Food and Agriculture Organization expected production to increase sharply so that by 2030, perhaps sixty-two percent of food fish would be farmed. Fish are consumed fresh, or may be preserved by traditional methods, which include combinations of drying, smoking, and salting, fermentation, and pickling in vinegar. Modern methods of preservation include freezing, freeze-drying, and heat processing (such as in the canning process). Frozen fish products include breaded or battered fillets, fish fingers and fishcakes. Fish meal is used as a food supplement for farmed fish and for livestock. Fish oils are made either from fish liver, especially rich in vitamins A and D, or from the bodies of oily fish such as sardine and herring, and used as food supplements and to treat vitamin deficiencies. Some smaller and more colourful species serve as aquarium specimens and pets. Sea wolves are used in the leather industry. Isinglass is made from thread fish and drum fish.
== Personal life == In 1957, Marks married sculptor and artist Averil Sherrard and had two children. Marks was known to have been an atheist and a humanist who was opposed to religion. Along with his wife, he campaigned for various causes including saving a park in Guildford, Surrey, where they lived, from developers. He was a founding member of the charity HealthSense. His brother John Marks was also a doctor, and the chair of the British Medical Association. Marks died on 6 November 2023, at the age of 93.
Sources: en.wikipedia.org
Selank is a synthetic heptapeptide designed as a stabilized analog of the natural tetrapeptide tuftsin. It has been investigated mainly for anxiolytic and cognitive effects. It is not an approved pharmaceutical in most countries.
It was developed in Russia, at the Institute of Molecular Genetics of the Russian Academy of Sciences, during the 1990s. Most published research originates from Russian institutions. Independent international replication remains limited.
Tuftsin is a natural tetrapeptide with the sequence Thr-Lys-Pro-Arg that participates in immune signaling. Selank extends that sequence with Pro-Gly-Pro at the C-terminus. The added residues are linked to greater resistance to enzymatic breakdown.
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.