This is a working overview of freeze-thaw, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2026-05-29 and is reviewed periodically as new material appears.
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.
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.
| 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 |
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.
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.
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.
Selank is not a naturally occurring peptide and has no known endogenous counterpart in human physiology. Russian-language sources frequently call it TP-7, while English-language sources use the name Selank almost exclusively. Database indexing is uneven, partly because early reports appeared in regional journals that are not widely cataloged. Some summaries describe the material as a tuftsin analog and others as a synthetic heptapeptide; the labels overlap rather than conflict. Citing the primary sequence resolves ambiguity more reliably than the research or trade name alone.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, written TKPRPGP in one-letter notation. Its structure consists of the immunomodulatory tetrapeptide tuftsin, Thr-Lys-Pro-Arg, extended at the carboxyl terminus by a Pro-Gly-Pro segment. The molecular formula is commonly given as C33H57N11O9, corresponding to a monoisotopic mass near 751.4 Da and an average molecular mass near 751.9 Da. All seven residues are proteinogenic amino acids, and the molecule carries no modified side chains or non-natural linkages.
The compound was designed at the Institute of Molecular Genetics of the Russian Academy of Sciences during the 1980s and 1990s. The stated design goal was to retain the immunomodulatory and central nervous system activity attributed to tuftsin while improving resistance to enzymatic breakdown. Adding a proline-rich tail to the short parent peptide was a deliberate strategy, because proline residues restrict the conformations available to many peptidases. The same laboratory produced Semax, an ACTH fragment analog, and both compounds were developed in parallel as short, enzymatically stabilized peptides intended for intranasal use.
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.
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.
=== Canada === Under the regulation of the Canadian Food Inspection Agency, manufacturers can produce blue cheese with a maximum of 47 percent moisture and minimum of 27 percent milk fat. Salt is allowed to be used as a preservative; however, the amount of the salt or combination of salts shall not exceed 200 parts per million of milk and milk products used to make the cheese. The Canadian Food Inspection Agency does not limit the use of bacterial cultures to aid further ripening and flavoring preparations other than cheese flavoring.
Health can play a central role in how people live their lives, reflecting the overall condition in which an organism functions properly, both physically and mentally. Good physical health is associated with high energy and the ability to perform everyday activities. Physical illnesses and disabilities can negatively impact well-being by causing pain, limiting mobility, and reducing the capacity to engage in enjoyable or necessary activities. Good mental health is a state of internal equilibrium in which mental capacities function as they should. Mental disorders are associated with some form of psychological impairment: they typically disrupt the equilibrium by causing distress and may limit the activities a person can engage in. Discrimination can amplify the negative effects of socially stigmatized illnesses and disabilities. Despite its general impact, health does not fully determine happiness, and some individuals affected by severe illnesses and disabilities report high levels of subjective well-being. The availability of healthcare services can mitigate negative effects by providing treatments to restore health or manage and alleviate symptoms. Similarly, adopting a healthy lifestyle, like regular physical activity and a balanced diet, is associated with long-term benefits to well-being.
In hepatocytes, insulin binding acutely leads to activation of protein phosphatase 2A (PP2A), which dephosphorylates the bifunctional enzyme fructose bisphosphatase-2 (PFKB1), activating the phosphofructokinase-2 (PFK-2) active site. PFK-2 increases production of fructose 2,6-bisphosphate. Fructose 2,6-bisphosphate allosterically activates PFK-1, which favors glycolysis over gluconeogenesis. Increased glycolysis increases the formation of malonyl-CoA, a molecule that can be shunted into lipogenesis and that allosterically inhibits of carnitine palmitoyltransferase I (CPT1), a mitochondrial enzyme necessary for the translocation of fatty acids into the intermembrane space of the mitochondria for fatty acid metabolism. Insulin also influences other body functions, such as vascular compliance and cognition. Once insulin enters the human brain, it enhances learning and memory and benefits verbal memory in particular. Enhancing brain insulin signaling by means of intranasal insulin administration also enhances the acute thermoregulatory and glucoregulatory response to food intake, suggesting that central nervous insulin contributes to the co-ordination of a wide variety of homeostatic or regulatory processes in the human body. Insulin also has stimulatory effects on gonadotropin-releasing hormone from the hypothalamus, thus favoring fertility. Anabolic vs. Reponic Classification Historically, insulin has been broadly classified as an anabolic hormone because it stimulates the synthesis of complex molecules.
=== Regulations === Worldwide, most polities have no laws about circumcision of males, with religious infant circumcision legal in every country. A few countries have passed legislation on the procedure: Germany allows routine circumcision, while non-religious routine neonatal circumcision is regulated in South Africa and Sweden. No major medical organization recommends circumcising all males, and no major medical organization recommends banning the procedure. In the academic literature, there is general agreement among both supporters and opponents of the practice that an outright ban would be predominately ineffective and "harmful". A consensus to keep the procedure within the purview of medical professionals is found across all major medical organizations, which advise medical professionals to yield to some degree to parental preferences in their decision to circumcise. The Royal Dutch Medical Association, which expresses some of the strongest opposition to routine neonatal circumcision, argues that while there are valid reasons for banning it, doing so could lead parents who insist on it to turn to poorly trained practitioners instead of medical professionals. During the 2010s, several right-wing nationalist parties prominently called for the banning of circumcision. Randi Gressgård, Researcher at the Centre for Women's and Gender Research (SKOK) at the University of Bergen, argued that politicians that supported Norway's proposed circumcision ban debated circumcision in a manner which constituted "ethnocentrism".
Sources: en.wikipedia.org
Smallpox was an infectious disease caused by the variola virus, which belongs to the genus Orthopoxvirus. The last naturally occurring case was diagnosed in October 1977, and the World Health Organization certified the global eradication of the disease in 1980, making smallpox the only human disease to have been eradicated. The initial symptoms of the disease included fever and vomiting. This was followed by formation of ulcers in the mouth and a skin rash. Over a number of days, the skin rash turned into the characteristic fluid-filled blisters with a dent in the center. The bumps then scabbed over and fell off, leaving scars. The disease was transmitted from one person to another primarily through prolonged face-to-face contact with an infected person or rarely via contaminated objects. Prevention was achieved mainly through the smallpox vaccine. Once the disease had developed, certain antiviral medications could have helped, but such medications did not become available until after the disease was eradicated. The risk of death was about 30%, with higher rates among babies. Often, those who survived had extensive scarring of their skin, and some were left blind. The earliest evidence of the disease dates to around 1500 BCE in Egyptian mummies. The disease historically occurred in outbreaks. It was one of several diseases introduced by the Columbian exchange to the New World, resulting in large swathes of Native Americans dying.
The balance-of-power system is discredited today. References to it, even by professional historians and international lawyers, commonly imply either that it was a system for war which repeatedly failed or that it was a system for making war which often succeeded in its purpose … During the period of its dominance as a European system, say, 1648 to 1918, its record in preventing war was certainly not striking. Indeed, it probably was itself responsible for starting more wars than it prevented. Former German Foreign Minister Joschka Fischer interpreted the core of the concept of Europe after 1945 as the rejection of the European balance-of-power principle and the hegemonic ambitions of individual states that had emerged following the Peace of Westphalia in 1648: "European integration was the response to centuries of a precarious balance of powers on this continent which again and again resulted in terrible hegemonic wars and culminated in the two World Wars between 1914 and 1945." Former US Secretary of Defense Dick Cheney expressed the same for Europe and other democracies: "It is not in our interest or those of the other democracies to return to earlier periods in which multiple military powers balanced one against another in what passed for security structures, while regional, or even global peace hung in the balance." NATO Secretary General, Manfred Wörner, outlined the European alternative at the end of the Cold War:
=== Climate === Lower Saxony falls climatically into the north temperate zone of central Europe that is affected by prevailing Westerlies and is located in a transition zone between the maritime climate of Western Europe and the continental climate of Eastern Europe. This transition is clearly noticeable within the state: while the northwest experiences an Atlantic (North Sea coastal) to Sub-Atlantic climate, with comparatively low variations in temperature during the course of the year and a surplus water budget, the climate towards the southeast is increasingly affected by the Continent. This is clearly shown by greater temperature variations between the summer and winter halves of the year and in lower and more variable amounts of precipitation across the year. This sub-continental effect is most sharply seen in the Wendland, in the Weser Uplands (Hamelin to Göttingen) and in the area of Helmstedt. The highest levels of precipitation are experienced in the Harz because the Lower Saxon part forms the windward side of this mountain range against which orographic rain falls. The average annual temperature is 8 °C (46 °F); 7.5 °C (45.5 °F) in the Altes Land and 8.5 °C (47.3 °F) in the district of Cloppenburg.
Many affected infants also have distinctive abnormalities of the head and facial (craniofacial) area. Many of the physical features associated with the disorder are congenital. In most cases, premature closure of fibrous joints (sagittal sutures) between certain bones (parietal bones) of the skull may restrict lateral growth of the skull, causing it to appear abnormally long and narrow that is disproportionate to the body size. In addition, the forehead may be abnormally prominent and the face may be triangular shaped with a hypo plastic mid face, pointed chin. Infants with this disorder may also have abnormally flat cheeks and cheekbones, large ears, prominent mouth with widely spread lips, and or underdeveloped upper jaw bones (maxillary hypoplasia). In addition, in some cases, the teeth may be abnormally crowded together, particularly toward the front of the mouth (anterior crowding) and as a result, the upper result, the upper jaw and lower teeth may not meet properly, they might be abnormally crowded together.
The isotopes neptunium-235, -236, and -237 are predicted to be fissile; although only neptunium-237's fissionability has been experimentally shown. Its critical mass is about 60 kg, only about 10 kg more than that of the commonly used uranium-235. Calculated values of the critical masses of neptunium-235, -236, and -237 respectively are 66.2 kg, 6.79 kg, and 63.6 kg: the neptunium-236 value is even lower than that of plutonium-239 and 236Np also has a low neutron cross section. However, a neptunium atomic bomb has never been built because uranium and plutonium have lower critical masses than 235Np and 237Np, and 236Np is difficult to purify as it is not found in quantity in spent nuclear fuel and is nearly impossible to separate in any significant quantities from 237Np.
Sources: en.wikipedia.org
=== By mouth === The basic appeal of hypoglycemic agents by mouth is that most people would prefer a pill or an oral liquid to an injection. However, insulin is a peptide hormone, which is digested in the stomach and gut and in order to be effective at controlling blood sugar, cannot be taken orally in its current form. The potential market for an oral form of insulin is assumed to be enormous, thus many laboratories have attempted to devise ways of moving enough intact insulin from the gut to the portal vein to have a measurable effect on blood sugar. A number of derivatization and formulation strategies are currently being pursued to in an attempt to develop an orally available insulin. Many of these approaches employ nanoparticle delivery systems and several are being tested in clinical trials.
Svante Cornell argued that although Tagliavini's report did blame Georgia for starting the war, that "should not be confused with the question of responsibility." He also criticised the argument that agreements did not allow Georgia to use force, because the mission did not analyze whether Russian or South Ossetian use of force still bound Georgia to the non-use of force. Cornell also criticised the report since it did not include evidence amassed by researcher Andrey Illarionov. Cornell also wrote in another article that the report was "far more devastating in its dismissal of Russia's justification for its invasion—in fact surprisingly so for an EU product." Georgian president Saakashvili said that the commission "said even more truth than I could ever imagine." He later said that he would still take the same action as he did on 7 August 2008 and he did not regret anything. The report caused the Georgian opposition to protest against President Saakashvili. The Wall Street Journal wrote that the report "shrinks from drawing the obvious conclusion, which is that this is a war the Kremlin wanted, schemed for, and got." On 8 October 2009, NATO Secretary General Anders Fogh Rasmussen declared that the report would not influence Georgian and Ukrainian membership of NATO. On 12 October 2009, Yulia Latynina, Russian journalist, wrote that the commission actually did not establish who was responsible for the war and which of the sides was lying.
Validation - The first definition indicates confirmation (through the provision of strong, sound, objective evidence) that requirements for a specific intended use or application have been fulfilled. However, within the family of definitions, it is frequently used in a manner synonymous with verification. Verification - often used to indicate a persona or identity has been verified against a database, such as a PIN-protected identify certificate matches a controlled access list.
== Pharmacokinetics == Dextromoramide has a mean elimination half life of 215.3 ± 78.4 minutes and volume of distribution of 0.58 ± 0.20 L/kg. Peak plasma levels are reached within 0.5–4.0 h after dosing, decline of plasma concentrations after the peak follow a biphasic pattern, with half-lives of 0.4–1.6 h for the first phase and 6.3–21.8 h for the terminal phase. While in about 40% of patients, half-lives range from 1.5 to 4.7 h, in a monophasic manner. Less than 0.06% of the dose is excreted unchanged in urine within 8 h of administration.
"prices for vaccines will be set as low as possible for territories that are or may be affected by an outbreak of a disease for which CEPI funding was used to develop a vaccine; "information, know-how and materials related to vaccine development must be shared with (or transferred to) CEPI" so that it can assume responsibility for vaccine development if a company discontinues expenditures for a promising vaccine candidate; CEPI would have access to, and possible management of, intellectual property rights (i.e., patents) for promising vaccines; "CEPI would receive a share of financial benefits that might accrue from CEPI-sponsored vaccine development, to re-invest in support of its mission to provide global public health benefit"; and data transparency among development partners should maintain the WHO Statement on Public Disclosure of Clinical Trial Results, and require results to be published in open-access publications. International groups, such as the Centre for Artistic Activism and Universities Allied for Essential Medicines, advocate for equitable access. Scientists have encouraged collaboration between the WHO, CEPI, corporations, and governments to ensure that vaccines are distributed in an evidence-based manner based on infection risk and to prioritize healthcare workers, vulnerable populations, and children. By mid-March 2021, 67 countries, mostly in Africa and the Middle East, had not yet reported any vaccinations. Countries that had begun vaccinations were generally prioritizing populations such as health workers or the elderly.
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.
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.