This is a working overview of batch purity, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2025-07-31. Anything still debated is marked as such rather than presented as settled.
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.
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.
Quantification in biological matrices relies on liquid chromatography coupled to tandem mass spectrometry with stable-isotope internal standards. Low plasma concentrations and adsorption to container surfaces both complicate measurement. Solid-phase extraction is often needed to reduce matrix interference before injection. Reported limits of quantification differ widely between laboratories, which makes direct comparison of pharmacokinetic results difficult and limits meta-analysis.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C33H57N11O9 | Free peptide form |
| Molecular mass | About 751.9 Da | Calculated average mass |
| Amino acid sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Single-letter form TKPRPGP |
| Structural basis | Tuftsin analogue | Extended version of a natural tetrapeptide |
| Development origin | Russian Academy of Sciences | Work carried out from the 1980s onward |
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.
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.
A third family of alcohol dehydrogenases, unrelated to the above two, are iron-containing ones. They occur in bacteria and fungi. In comparison to enzymes of the above families, these enzymes are oxygen-sensitive. Members of the iron-containing alcohol dehydrogenase family include:
==== Deluge of wars ==== During the reign of John II Casimir Vasa (r. 1648–1668), the third and last king of his dynasty, the nobles' democracy fell into decline as a result of foreign invasions and domestic disorder. These calamities multiplied rather suddenly and marked the end of the Polish Golden Age. Their effect was to render the once powerful Commonwealth increasingly vulnerable to foreign intervention.
=== In space === The 2021 Plant Habitat-04 experiment aboard the International Space Station grew four chili plants in 137 days, producing twenty-six peppers across two harvests. Most were eaten by the crew; twelve were returned to Earth for study. The plants were a specially dwarfed variety of the Hatch cultivar. This was the "first generally recognized fruiting crop in space", following harvests of leaf crops such as lettuce and kale from 2014 onwards.
Sources: en.wikipedia.org
== Signs and symptoms == The consumption of large quantities of Lathyrus seeds containing high concentrations of the neurotoxic glutamate analogue β-oxalyl-L-α,β-diaminopropionic acid (ODAP, also known as β-N-oxalyl-amino-L-alanine, or BOAA) causes paralysis, characterized by lack of strength in or inability to move the lower limbs, and may involve pyramidal tracts, producing signs of upper motor neuron damage. The toxin may also cause aortic aneurysm. A unique symptom of lathyrism is the atrophy of gluteal (buttocks) muscles. ODAP is a poison of the mitochondria, leading to excess cell death, especially in motor neurons. Children can additionally develop bone deformity and reduced brain development.
Clinical history of ischaemic type chest pain lasting for more than 20 minutes Changes in serial ECG tracings Rise and fall of serum cardiac biomarkers such as creatine kinase-MB fraction and troponin
In practice, the USSR was a highly centralised entity from its creation in 1922 until the mid-1980s when political forces unleashed by reforms undertaken by Mikhail Gorbachev resulted in the loosening of central control and its ultimate dissolution. Under the constitution adopted in 1936 and modified along the way until October 1977, the political foundation of the Soviet Union was formed by the Soviets (Councils) of People's Deputies. These existed at all levels of the administrative hierarchy with the Soviet Union as a whole under the nominal control of the Supreme Soviet of the USSR, located in Moscow within the Russian SFSR. Along with the state administrative hierarchy, there existed a parallel structure of party organizations, which allowed the Politburo to exercise large amounts of control over the republics. State administrative organs took direction from the parallel party organs, and appointments of all party and state officials required approval of the central organs of the party. Each republic had its own unique set of state symbols: a flag, a coat of arms, and, with the exception of Russia until 1990, an anthem. Every republic of the Soviet Union also was awarded with the Order of Lenin.
One of the earliest successes of hydroponics occurred on Wake Island, a rocky atoll in the Pacific Ocean used as a refueling stop for Pan American Airlines. Hydroponics was used there in the 1930s to grow vegetables for the passengers. Hydroponics was a necessity on Wake Island because there was no soil, and it was prohibitively expensive to airlift in fresh vegetables. From 1943 to 1946, Daniel I. Arnon served as a major in the United States Army and used his prior expertise with plant nutrition to feed troops stationed on barren Ponape Island in the western Pacific by growing crops in gravel and nutrient-rich water because there was no arable land available. In the 1960s, Allen Cooper of England developed the nutrient film technique. The Land Pavilion at Walt Disney World's EPCOT Center opened in 1982 and prominently features a variety of hydroponic techniques. In recent decades, NASA has done extensive hydroponic research for its Controlled Ecological Life Support System (CELSS) and Advanced Life Support (ALS) programs. Hydroponics research mimicking space environments will need further study for different gravity environments, for example u-gravity in Low Earth Orbit, 1/6 g on the Moon, and 1/3 g on Mars. Ray Wheeler, a plant physiologist at Kennedy Space Center's Space Life Science Lab, believes that hydroponics will allow water and nutrient recycling needed for space travel and eventual bioregenerative life support systems where plants are used to produce oxygen and food, while removing carbon dioxide.
Sources: en.wikipedia.org
The history of visual art in Portugal dates back into the Paleolithic. An early evidence showing an attempt at depicting motion was found at the Prehistoric Rock Art Sites in the Côa Valley and Siega Verde. Over time, foreign and native influences, together with advancements in manufacturing, developed distinctive art styles, such as the Manueline and Pombaline, and also a number of crafts that are typical of Portugal, namely the azulejo, talha dourada, and Portuguese pavement. Historically, Christianity played an influential role in Portuguese art and was a recurrent theme in many art forms, including painting. Throughout the country's history, artwork in Portugal was typically done by local artists who, depending on location, followed different variations in style, giving Portugal a diverse array of artistic styles throughout the country, an example of this being the thatch houses of Santana, in Madeira.
However, Watson and Crick found fault in her steadfast assertion that, according to her data, a helical structure was not the only possible shape for DNA—so they had a dilemma. In an effort to clarify this issue, Max Ferdinand Perutz later published what had been in the progress report, and suggested that nothing was in the report that Franklin herself had not said in her talk (attended by Watson) in late 1951. Perutz explained that the report was to a Medical Research Council (MRC) committee that had been created to "establish contact between the different groups of people working for the Council". Randall's and Perutz's laboratories were both funded by the MRC. It is also not clear how important Franklin's unpublished results from the progress report actually were for the model-building done by Watson and Crick. After the first crude X-ray diffraction images of DNA were collected in the 1930s, William Astbury had talked about stacks of nucleotides spaced at 3.4 angström (0.34 nanometre) intervals in DNA. A citation to Astbury's earlier X-ray diffraction work was one of only eight references in Franklin's first paper on DNA. Analysis of Astbury's published DNA results and the better X-ray diffraction images collected by Wilkins and Franklin revealed the helical nature of DNA. It was possible to predict the number of bases stacked within a single turn of the DNA helix (10 per turn; a full turn of the helix is 27 angströms [2.7 nm] in the compact A form, 34 angströms [3.4 nm] in the wetter B form).
=== Augusta National green jacket === The green jacket is reserved for Augusta National members and golfers who win the Masters Tournament. Jackets are kept on club grounds, and taking them off the premises is forbidden. The exception is for the winner, who can take it home and return it to the club the following year. Player, who became the tournament's first international winner in 1961, said he did not know that, he packed the jacket and took it to his home in South Africa. That led to a call from club Chairman Clifford Roberts, who was a stickler for rules. "I didn't know you were supposed to leave it there," Player said. "Next thing you know, there was a call from Mr. Roberts."
The game's scope suffered from content not being removed when necessary; other components would be endlessly refined without being finalized, preventing the developers from focusing on other parts of the game system. All content additionally required approval by White Wolf and Activision. After three years of development, the game was progressing slowly, and it was unknown when it would be finished. Activision set a series of deadlines for the project's development to ensure Troika had sufficient time to effectively test the game, though these milestones were repeatedly extended, and Bloodlines eventually ran over budget. In 2003 Activision intervened, ordering that the game be ready for release in the next few months and even advancing more money to Troika to complete its work on The Temple of Elemental Evil for Atari, freeing the Troika team to work on Bloodlines exclusively. Activision eventually issued an ultimatum that the project be finished within months, on September 15, 2004. Troika delivered a version of Bloodlines on the required date; due to its scale, the game underwent three weeks of testing. Activision decided that the game was suitable for release but was contractually bound to withhold Bloodlines until after the debut of Half-Life 2 in November 2004. Troika convinced Activision to use the delay to fund further development; the additional budget was insufficient to pay all of Troika's staff, and some employees worked unpaid to complete the project.
Biguanide () is the organic compound with the formula HN(C(NH)NH2)2. It is a colorless solid that dissolves in water to give a highly basic solution. These solutions slowly hydrolyse to ammonia and urea.
Sources: en.wikipedia.org
It is a seven-amino-acid peptide, Thr-Lys-Pro-Arg-Pro-Gly-Pro, produced by chemical synthesis rather than extracted from biological tissue. Its design is based on tuftsin, a natural immunomodulatory tetrapeptide. The C-terminal Pro-Gly-Pro segment is a common stabilising motif in short regulatory peptides.
The core four residues correspond to tuftsin, which occurs naturally as part of immunoglobulin G. The full seven-residue sequence, however, is not a known endogenous peptide. It is a laboratory-designed analogue intended to combine tuftsin-like activity with greater resistance to breakdown.
No single receptor has been confirmed as the primary target. Reports describe involvement of the GABAergic system, interference with enkephalin degradation, and shifts in neurotrophic factor expression. Because these observations come from different models and assays, they have not yet been integrated into one accepted mechanism.
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.