If you have been reading about freeze-thaw and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Updated 2026-08-01. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Route studied | Intranasal | Predominant route in published reports |
| Circulation stability | Short, minutes scale | Peptidases cleave it; the tail slows the process |
| Analytical method | RP-HPLC with mass spectrometry | Used for identity and purity assessment |
| Reported outcome domains | Anxiety and cognitive measures | Derived from small, mostly regional trials |
| Regulatory status | Marketed in Russia | Availability outside that market is limited |
Published clinical work is concentrated in Russian-language journals and generally involves small samples without independent replication. Systematic reviews in English note the shortage of randomised, placebo-controlled trials and the difficulty of verifying methods from translated reports. Outcome measures vary between studies, which complicates pooling of results. Interest in the compound as a cognitive or anxiolytic agent therefore rests on a thinner evidence base than the volume of citations suggests. Replication in well-powered trials with preregistered endpoints would be needed before firm conclusions about efficacy can be drawn.
Proposed mechanisms centre on the GABAergic system. Animal and tissue studies report changes in GABA-A receptor expression and reduced activity of GABA transaminase, the enzyme that degrades GABA. Effects on monoamine turnover, including serotonin and dopamine pathways, are also described, and a separate line of work links the peptide to increased expression of brain-derived neurotrophic factor in hippocampal tissue. Most of these findings come from rodent models and cell preparations. How the individual observations combine into a single coherent mode of action is not settled.
Pharmacokinetic data are sparse and largely derived from animal work. After intranasal administration the peptide appears in plasma within minutes, and reported half-lives are short, on the order of minutes to tens of minutes. Degradation proceeds through ordinary proteolytic cleavage into constituent amino acids and smaller fragments. Direct evidence that intact Selank reaches brain tissue in meaningful amounts is limited, and the extent of blood-brain barrier penetration is debated. Some authors argue that fragments, not the parent peptide, carry much of the observed activity.
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.
nonsynonymous mutation Also nonsynonymous substitution or replacement mutation. A type of mutation in which the substitution of one nucleotide base for another results, after transcription and translation, in an amino acid sequence that is different from that produced by the original unmutated gene. Because nonsynonymous mutations always result in a biological change in the organism, they are often subject to strong selection pressure. Contrast synonymous mutation.
==== Extraction ==== Extraction of polyphenols can be performed using a solvent like water, hot water, methanol, methanol/formic acid, methanol/water/acetic or formic acid. Liquid–liquid extraction can be also performed or countercurrent chromatography. Solid phase extraction can also be made on C18 sorbent cartridges. Other techniques are ultrasonic extraction, heat reflux extraction, microwave-assisted extraction, critical carbon dioxide, high-pressure liquid extraction or use of ethanol in an immersion extractor. The extraction conditions (temperature, extraction time, ratio of solvent to raw material, particle size of the sample, solvent type, and solvent concentrations) for different raw materials and extraction methods have to be optimized. Mainly found in the fruit skins and seeds, high levels of polyphenols may reflect only the measured extractable polyphenol (EPP) content of a fruit which may also contain non-extractable polyphenols. Black tea contains high amounts of polyphenol and makes up for 20% of its weight. Concentration can be made by ultrafiltration. Purification can be achieved by preparative chromatography.
=== 6 May === In Russia, the governor of Belgorod Oblast claimed that eight people were killed and 35 others were injured in a Ukrainian drone strike that hit three vehicles in the village of Berezovka. Russia claimed to have taken the villages of Soloviove in Donetsk Oblast and Kotliarivka in Kharkiv Oblast, 20 kilometers from Kupiansk. Ukraine claimed to have destroyed a Russian military fast attack craft in Crimea using a naval drone. Ukrainian forces claimed a series of successful counterattacks against Russian forces near Bakhmut, resulting in an advance of some 500 metres, and inflicting casualties on Russian soldiers and the destruction of four supply trucks, a BMP-2, and a BMD-4 using drones. Russia released footage of a Ka-29 opening fire on a Sea Baby drone armed with a R-73 infrared missile to defend it from helicopters. One missile appeared to have been fired before it was destroyed by gunfire. In response to perceived threats from France, Britain, and the United States, Russia announced it would practice the deployment of tactical nuclear weapons as part of a military exercise.
Screening tests are offered to the asymptomatic people to reveal possible diseases. On the contrary, diagnostic tests are used to prove or disapprove certain conditions. To follow the course of the disease or the reaction to treatment, monitoring tests are presented. Lastly, there are tests during the follow-up to determine the results following treatment. The following is an example of a typical breakdown of the responsibilities of each area:
Sources: en.wikipedia.org
Generalized depression: Generalized depression is seen in the early stages of glaucoma and many other conditions. Mild constriction of the central and peripheral visual field due to isopter contraction comes under generalized depression. If all the isopters show similar depression to the same point, it is then called a contraction of the visual field. Relative paracentral scotomas are the areas where smaller and dimmer targets are not visualized by the patient. Larger and brighter targets can be seen. Small paracentral depressions, mainly superonasal are seen in normal tension glaucoma (NTG). The generalized depression of the entire field may be seen in cataract also. Baring of blind spot: "Baring of blind spot" means exclusion of blind spot from the central field due to the inward curve of the outer boundary of 30° central field. It is only an early non-specific visual field change, without much diagnostic value in glaucoma. Small wing-shaped Paracentral scotoma: Small wing-shaped Paracentral scotoma within Bjerrum's area is the earliest clinically significant field defect seen in glaucoma. It may also be associated with nasal steps. Scotoma may be seen above or below the blind spot. Siedel's sickle-shaped scotoma: Paracentral scotoma joins with the blind spot to form the Seidel sign. Arcuate or Bjerrum's scotoma: It is formed at later stages of glaucoma by extension of Seidel's scotoma in an area either above or below the fixation point to reach the horizontal line. Peripheral breakthrough may occur due to damage to nerve fibers.
=== Otologic === By the age of 50, about 50% of adults with OI experience significant hearing loss, much earlier as compared to the general population. Hearing loss in OI may or may not be associated with visible deformities of the ossicles and inner ear. Hearing loss frequently begins during the second, third, and fourth decades of life, and may be conductive, sensorineural, or a combination of both ("mixed"). If hearing loss does not occur by age 50, it is significantly less likely to occur in the years afterwards. Mixed hearing loss is most common among those with OI of all age groups, while conductive hearing loss is most likely to affect older people, with sensorineural hearing loss most likely to affect children. Although relatively rare, OI-related hearing loss can also begin in childhood; in a study of forty-five children aged four to sixteen, two were found to be affected, aged 11 and 15. In a different 2008 study, the hearing of 41 people with OI was checked. The results showed that 88% of those over 20 years of age had some form of hearing loss, while only 38% of those under 20 did. Hearing loss is most common in type I OI; it is less common in types III and IV. Other parts of the inner ear may also be affected by OI. causing balance issues; however, only small studies have found links between vertigo and OI. OI may worsen the outcome of medical treatments which correct hearing loss.
The two got official approval from Valve to release Sven Co-op on Steam as a standalone title in 2012, though opted to wait nearly a year to announce this in July 2013 to give their team time to develop a hotfix for the current version of the mod. This standalone title was released on January 22, 2016, and includes all the assets for Half-Life required to play that game without installing the original game; players are still required to have purchased and installed Opposing Force and Blue Shift to play those in the standalone release of Sven Co-op. The standalone version includes updated versions of the Half-Life campaign maps, improved versions of popular maps developed for Sven Co-op, and additional scripting tools that will allow level designers to further customize new maps beyond the default GoldSrc. McDermott stated that their team anticipates continuing to improve tools for level designers, such as being able to replace the game's default heads-up display, though as the game is still developed in the team's free time, there is no information on when these will be available.
== History == Ziprasidone is chemically similar to risperidone, of which it is a structural analogue. It was first synthesized in 1987 at the Pfizer central research campus in Groton, Connecticut. Phase I trials started in 1995. In 1998 ziprasidone was approved in Sweden. After the FDA raised concerns about long QT syndrome, more clinical trials were conducted and submitted to the FDA, which approved the drug on February 5, 2001.
==== Campaign on the Pihe River (May–July 1933) ==== Liu deeply resented what he saw as Deng Xihou's betrayal, causing him to lose much territory in the Sichuan Basin. Not only did Deng order Tian to attack Liu's rear, but he had also taken over Chengdu in Liu's absence, blocking his return to the city. Liu had entrusted Deng with the city, but he had allowed Tian Songyao and his subordinates to reenter, including Wang Mingzhang who had become the Chengdu garrison commander. Both sides attempted negotiations while preparing their forces; Deng first attempted to appease Liu Wenhui, but Liu had by then resolved to crush him. Liu first attempted to lure Deng into a deadly banquet, but Deng caught wind of these plans and even taunted Liu about them. The battle began in May 1933 when Liu attacked along the Pihe River. Seeking support, Deng entered into talks with Liu Xiang's advisor Liu Congyun. By strategically converting to Liu Congyun's Taoist sect, Deng managed to acquire ammunition for his regiments and 100,000 silver dollars. Liu's officers also refused to fight against their former Baoding classmates, with some demanding more pay or even entering into negotiations with Deng's commanders. In June, heavy fighting was reported around Guanxian. By July, Liu Xiang had arrived in Neijiang to command a new offensive against Liu Wenhui. When Liu Wenhui convened a strategy meeting with his subordinates, several division commanders openly questioned his authority and leadership.
Sources: en.wikipedia.org
Reports describe effects on GABA-A receptor expression, monoamine turnover, and neurotrophic factor levels. These are proposed mechanisms drawn mainly from animal models. No single molecular target has been established.
Intranasal delivery is the route described in most published work. It is used because the peptide is degraded quickly once it reaches circulation. Direct evidence of brain penetration in humans is lacking.
Most trials are small, regionally concentrated, and often lack rigorous blinding or placebo control. Independent replication is limited. Reviews in English generally rate the evidence as preliminary.
Reverse-phase HPLC is the usual method and gives a percentage purity value. Mass spectrometry then confirms the molecular mass. Together they provide a basic identity and purity profile for a lot.