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.
Last reviewed on 2026-03-03. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Primary route studied | Intranasal | Also examined parenterally in animal work |
| Reported plasma half-life | Minutes to tens of minutes | Values vary widely between reports |
| Main model systems | Rodent behavioural and cell assays | Human trials are few and small |
| Principal proposed targets | GABA-A receptor, GABA transaminase | Monoamine and neurotrophic pathways also reported |
| Evidence grade | Preliminary | Limited independent replication |
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.
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.
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.
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.
== See also == List of ineffective cancer treatments List of topics characterized as pseudoscience Royal Commission on Animal Magnetism Royal touch Energy medicine Faith healing Laying on of hands Reiki Access Consciousness
== Standardized nomenclature == There are multiple conventions for naming polymer substances. Many commonly used polymers, such as those found in consumer products, are referred to by a common or trivial name. The trivial name is assigned based on historical precedent or popular usage rather than a standardized naming convention. Both the American Chemical Society (ACS) and IUPAC have proposed standardized naming conventions; the ACS and IUPAC conventions are similar but not identical. Examples of the differences between the various naming conventions are given in the table below:
Over 13,000 Plautdietsch-speaking Mennonites live in Belize, farming the land and living according to their religious beliefs. These Mennonite population comprises so-called Russian Mennonites of German descent who settled in the Russian Empire during the 18th and 19th centuries, where they developed into an ethnoreligious group. In the 1870s many of them migrated to Canada, then between 1922 and 1925 to Mexico and in the years after 1958 to Belize. Most Russian Mennonites live in Mennonite settlements like Spanish Lookout, Shipyard, Little Belize, and Blue Creek. The Russian Mennonites speak Plautdietsch, a Low German dialect, in everyday life, but use mostly Standard German for reading (the Bible) and writing. The Plautdietsch-speaking Mennonites came mostly from Mexico and most men are trilingual with proficiency in German, Spanish and English. There are also more than a thousand mainly Pennsylvania Dutch-speaking Old Order Mennonites who came from the United States and Canada in the late 1960s. They live primarily in Upper Barton Creek, Springfield and associated settlements. These Mennonites attracted people from different conservative Anabaptist backgrounds who formed a new community. They look quite similar to Old Order Amish, but are different from them.
== Traditional custom == Since superincision and circumcision are both forms of genital cutting that expose the glans, it can often be difficult to know which procedure is being described or depicted. Opinion is divided on whether a 4,000-year-old image from Egypt, often described as the first depiction of circumcision, may in fact be of a superincision. Superincision has been widely practised by people of the Pacific, stretching from Hawaii to the Philippines (where it is called tuli). With increasing urbanisation, traditional rituals have been giving way in many places to medically performed circumcision, and almost entirely so among Islanders living in New Zealand, where a recent survey found there was "a strong cultural demand from parents". The most notable exception to Pacific superincision is the Māori of New Zealand, who do not circumcise or superincise, although they have an indigenous term for the latter (ure haea or "split penis") and their tradition is that they stopped the practice when they arrived in New Zealand.
Sources: en.wikipedia.org
=== For vaccine creation === SeV has several features that are important in a vector for a successful vaccine: the virus does not integrate into the host genome, it does not undergo genetic recombination, it replicates only in the cytoplasm without DNA intermediates or a nuclear phase. SeV, as all other representatives of family Paramyxoviridae, is genetically stable and evolves very slowly. SeV genome can accommodate foreign genes in multiple intergenic positions and the SeV genome is suitable for introducing genes encoding the envelope glycoproteins of pathogenic viruses. For vaccination purpose the virus-based constructs could be delivered in a form of nasal drops, which may be beneficial in inducing a mucosal immune response. This form of vaccination is more immunogenic than intramuscular considering pre-existing anti-SeV antibodies. Sendai virus-based constructs can induce durable, mucosal, B-cell, and T-cell immune responses. The virus genome has high similarity with human parainfluenza virus 1 (HPIV-1) and the two viruses share common antigenic determinants. The study that was published in 2011 demonstrated that SeV neutralizing antibodies (which were formed due to human parainfluenza virus type 1 past infection) can be detected in 92.5% of human subjects worldwide with a median EC50 titer of 60.6 and values ranging from 5.9–11,324. Low anti-SeV antibodies background does not block the ability of SeV-base vaccine to promote antigen-specific T cell immunity.
Histopathology refers to the microscopic examination of various forms of human tissue. Specifically, in clinical medicine, histopathology refers to the examination of a biopsy or surgical specimen by a pathologist, after the specimen has been processed and histological sections have been placed onto glass slides. This contrasts with the methods of cytopathology, which uses free cells or tissue fragments. Histopathological examination of tissues starts with surgery, biopsy, or autopsy. The tissue is removed from the body of an organism and then placed in a fixative that stabilizes the tissues to prevent decay. The most common fixative is formalin, although frozen section fixing is also common. To see the tissue under a microscope, the sections are stained with one or more pigments. The aim of staining is to reveal cellular components; counterstains are used to provide contrast. Histochemistry refers to the science of using chemical reactions between laboratory chemicals and components within tissue. The histological slides are then interpreted diagnostically and the resulting pathology report describes the histological findings and the opinion of the pathologist. In the case of cancer, this represents the tissue diagnosis required for most treatment protocols.
Thermal ionization mass spectrometry (TIMS), also known as surface ionization, is a highly sensitive isotope mass spectrometry characterization technique. The isotopic ratios of radionuclides are used to get an accurate measurement for the elemental analysis of a sample. Singly charged ions of the sample are formed by the thermal ionization effect. A chemically purified liquid sample is placed on a metal filament which is then heated to evaporate the solvent. The removal of an electron from the purified sample is consequently achieved by heating the filament enough to release an electron, which then ionizes the atoms of the sample. TIMS utilizes a magnetic sector mass analyzer to separate the ions based on their mass to charge ratio. The ions gain velocity by an electrical potential gradient and are focused into a beam by electrostatic lenses. The ion beam then passes through the magnetic field of the electromagnet where it is partitioned into separate ion beams based on the ion's mass/charge ratio. These mass-resolved beams are directed into a detector where it is converted into voltage. The voltage detected is then used to calculate the isotopic ratio.
== Toxicity == Toxic effects of retinoids occur with both acute and prolonged intake, depending on which retinoid is considered. The specific toxicity is related to the mechanism of action as well as exposure. A medical sign of chronic or acute poisoning with retinol is hypervitaminosis A, which includes the presence of painful, tender swellings on the long bones. Anorexia, skin lesions, hair loss, hepatosplenomegaly, papilloedema, bleeding, general malaise, pseudotumor cerebri, and death may also occur. Retinoids provoke rapid elevation of circulating triglycerides leading to hypertriglyceridemia as well as cholesterol, leading to hypercholesterolemia. Retinoids are further shown to worsen many metabolic diseases, such as diabetes and congestive heart failure. Large-scale randomized, controlled clinical trials have conclusively shown that vitamin A, retinol, and other retinoids increase mortality and cancer rates in smokers and asbestos workers. In addition to the harmful effects shared by other retinoids, bexarotene causes severe hypothyroidism. The Pharmacovigilance Risk Assessment Committee (PRAC), based on its review, confirmed that taking oral retinoids during pregnancy can have harmful effects on the baby as they may cause CNS, cranio-facial, cardiovascular and other defects. The use of acitretin, alitretinoin and isotretinoin should be prohibited in women of childbearing age unless they take measures to prevent pregnancy. Many lotions that claim to prevent or treat stretch marks contain retinol, which is not an ingredient that is safe for pregnant women.
== Adverse effects == In the treatment of psoriasis, the most common adverse events are gastrointestinal events, flushing and lymphopenia, which are usually mild. Other adverse events include progressive multifocal leukoencephalopathy (PML) and Fanconi syndrome, which are considered rare. PML is probably caused by a combination of factors. A previous infection with the John-Cunningham virus (JCV) is considered a prerequisite for the development of PML. In a PML review, all confirmed cases were of patients exposed to periods of varying lymphopenia. For multiple sclerosis, adverse effects include flushing and gastrointestinal events, such as diarrhoea, nausea and upper abdominal pain. The drug label includes warnings about the risk of anaphylaxis and angioedema, PML, lymphopenia and liver damage. There is no information on how dimethyl fumarate affects the fetus during pregnancy; in animal tests there was fetal harm at clinically relevant doses.
Sources: en.wikipedia.org
== Franchises == TGI Fridays is a franchising operation, with franchisees owning most of the outlets. In 2011, the largest franchisee was The Briad Group in New Jersey, which ran 72 restaurants in six states. Briad sold its franchises in 2020. Whitbread PLC, with 45 locations in the United Kingdom, was a major international franchisee until 2007. On January 17, 2007, Whitbread sold operating rights to all 45 restaurants back to TGI Fridays UK Limited (a consortium consisting of Carlson Restaurants Worldwide Inc. and ABN Amro Capital) thus exiting a partnership formed in 1986. TGI Fridays has also been used as a restaurant for hotels run by Country Inns & Suites by Carlson brand. On 18 September 2024, Hostmore PLC entered administration; all UK restaurant locations were offered for sale. 51 sites were sold the following month, while a further 35 closed.
=== Interactions === ERp44 Hisatsune et al. demonstrated, by co-immunoprecipitation, an interaction between ERAP1 and the disulfide-shuffling chaperone ERp44, facilitated by disulfide bonds formed with cysteine residues in the exon 10 loop of ERAP1. This interaction was proposed to be the main mechanism for ER retention.
=== Environmental impact === On an industry level, supplementing one million cows with rBST would result in the same amount of milk produced while needing 157,000 fewer cows. Farmers are, therefore, able to improve milk production with a smaller dairy population. Some studies show that rBST-treated cows reduce the greenhouse gas footprint in comparison with conventional and organic dairy operations. Cady's study showed that excretion of nitrogen and phosphorus, two major environmental pollutants arising from animal agriculture, was reduced by 9.1 and 11.8%, respectively. Carbon dioxide is recognized to be the most important anthropogenic greenhouse gas, and livestock metabolism and fossil fuel consumption are the main sources of emissions from animal agriculture.
When the United States Navy ended Japan's Sakoku policy, and thus its isolation, the latter found itself defenseless against military pressures and economic exploitation by the Western powers. For Japan to emerge from the feudal period, it had to avoid the colonial fate of other Asian countries by establishing genuine national independence and equality. Following the María Luz Incident, Japan released the Chinese coolies from a western ship in 1872, after which the Qing imperial government of China gave thanks to Japan. However, tension soon rose between Qing China and Meiji Japan as a result of geopolitical tug-of-war for control and influence over the strategically vital Korean Peninsula. In 1884, pro-Japanese reformers in Korea, whom admired the successes of the Meiji Restoration and wanted to get rid of Korea's traditional subservience to an already weakened China after the Opium Wars, staged a brief coup d'état which triggered a clash with Qing troops stationed in Seoul who intervened to rescue the Korean king. In 1885, both nations signed an agreement to withdraw their troops from Korea and agreed to notify one another before sending military forces to the peninsula in the future. Tensions flared further in 1894 when Kim Ok-kyun, the pro-Japanese leader of the 1884 coup, was lured to Shanghai and assassinated, allegedly by Qing agents. The Japanese public was outraged, viewing this as a direct affront. At the same time, a massive peasant uprising broke out in Korea and the Korean king requested military aid from the Qing government to disperse the rebels.
== GSNO in health and disease == GSNO and NO concentrations regulate respiratory function by modulating airway tone and pro- and anti-inflammatory responses in the respiratory tract. Because NO is a labile gas and endogenous levels are difficult to manipulate, it has been proposed that exogenous GSNO could be used to regulate circulating levels of NO and NO-derived species, and GSNO could have value in patients with pulmonary diseases such as cystic fibrosis. Consistent with this therapeutic goal, a recent study showed that acute treatment with aerosolized GSNO was well tolerated by cystic fibrosis patients. SNOs in the hepatic mitochondria appear to influence proper functioning of the liver. Mitochondrial SNO-proteins inhibit Complex I of the electron transport chain; modulate mitochondrial reactive oxygen species (ROS) production; influence calcium-dependent opening of the mitochondrial permeability transition pore; promote selective importation of mitochondrial proteins; and stimulate mitochondrial fission. Altered redox balance plays a crucial role in the pathogenesis of liver diseases including steatosis, steatohepatitis, and fibrosis. The ease of reversibility and the interplay of S-nitrosating and denitrosating enzymatic reactions support the hypothesis that SNOs regulate the mitochondrion through redox mechanisms. In a study evaluating the effects on ursodeoxycholic acid (UDCA) on bile flow and cirrhosis, NO was found in bile as SNOs, primarily GSNO.
Sources: en.wikipedia.org
Reports describe modulation of GABA signalling, changes in monoamine turnover and effects on neurotrophic factor expression. These observations come mainly from animal and cell studies. A single unifying mechanism has not been demonstrated.
The peptide enters plasma rapidly and is broken down by ordinary proteases into amino acids and shorter fragments. Reported half-lives are short. Whether meaningful amounts of the intact molecule reach the brain is an open question.
Most clinical reports are small, published in Russian and not independently replicated. English-language reviews highlight the absence of large randomised trials. Conclusions about efficacy should be treated as provisional.
Purity is usually reported as an HPLC area percentage, most often measured at 214 nm. Identity is confirmed separately by mass spectrometry. A certificate of analysis should state both the method and the observed value.