Everything below concerns freeze-thaw. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2026-02-17. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
Laboratory work relies on standard behavioral paradigms. Rodents are tested in the elevated plus maze, open field, and passive avoidance tasks, with outcomes compared against diazepam or vehicle controls. Intranasal dosing is used most often because it bypasses first-pass metabolism, though intraperitoneal and intravenous routes also appear in published protocols. Biochemical endpoints include tissue BDNF concentrations, cytokine levels, and monoamine metabolites. Human data are limited to small Russian trials reporting reduced anxiety scores; most were not prospectively registered, and few employed independent outcome assessment.
Measuring peptide exposure inside the brain is technically difficult. Selank is degraded rapidly in plasma, and assays must separate intact peptide from fragments, which favors targeted mass spectrometry over immunoassays alone. Reported half-lives are short, on the order of minutes, so effects observed hours later are attributed to downstream signaling rather than to the parent compound. Blood-brain barrier permeability is debated and rarely quantified directly. Gaps include absent dose-response characterization, inconsistent reporting of purity, and almost no pharmacokinetic data from human participants.
Selank is studied chiefly as an animal-model anxiolytic with proposed secondary effects on memory and immune signaling. Reported mechanisms include modulation of the GABA-A receptor complex, inhibition of enkephalin-degrading enzymes, and shifts in monoamine turnover within limbic structures. Some experiments describe increased expression of brain-derived neurotrophic factor in the hippocampus after repeated dosing. No single molecular target has been confirmed, and the peptide does not bind any receptor with the selectivity typical of a conventional small-molecule drug. Mechanism therefore remains a set of hypotheses rather than an established pathway.
| 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 |
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.
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.
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.
Selank is a synthetic heptapeptide developed in Russia as a structural analogue of tuftsin, a naturally occurring immunomodulatory tetrapeptide. Its sequence, Thr-Lys-Pro-Arg-Pro-Gly-Pro, keeps the tuftsin core at the N-terminus and appends a Pro-Gly-Pro tail. Researchers at the Institute of Molecular Genetics in Moscow synthesized the compound during the 1990s while searching for peptides with combined anxiolytic and immunomodulatory activity. The added tail was intended to resist enzymatic cleavage and prolong the molecule's presence in circulation.
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.
Quality assessment of Selank samples typically combines purity determination with identity confirmation and counter-ion analysis. Purity is usually reported as a percentage by chromatographic area, with values above 95 percent often quoted for research-grade material. Water content and residual solvents are checked in lyophilized batches because they affect both stability and accurate mass determination. A reported purity figure does not by itself establish that a sample is the intended sequence, so orthogonal methods are needed to rule out sequence isomers or truncation products.
Characterization of Selank in laboratory settings relies on standard peptide analytical techniques. Reverse-phase high-performance liquid chromatography separates the peptide from related impurities and degradation products, while mass spectrometry confirms molecular identity through accurate mass measurement. Amino acid analysis and peptide sequencing verify the primary structure when reference material is unavailable. Because Selank is a short chain, fragmentation-based analysis produces a diagnostic ion pattern that supports confident identification.
Peptide stability depends strongly on temperature, moisture, and pH. Lyophilized Selank is generally most stable when stored cold and dry, with freezer temperatures commonly used for long-term storage. In solution, the compound is susceptible to hydrolysis and to microbial growth if it is not handled aseptically. The C-terminal proline-rich extension appears to slow enzymatic cleavage relative to tuftsin, though quantitative degradation rates vary with the matrix and the conditions tested. Published stability data specific to Selank remain sparse.
=== Firing of employee that filed suit (2010) === A federal lawsuit was filed by a scientist claiming she got an infection by a genetically modified lentivirus while working for Pfizer, resulting in intermittent paralysis. A judge dismissed the case citing a lack of evidence that the illness was caused by the virus but the jury ruled that by firing the employee, Pfizer violated laws protecting freedom of speech and whistleblowers and awarded her $1.37 million.
Jennifer Ann Kiggans (née Moore; born June 18, 1971) is an American politician, former United States Navy helicopter pilot, and geriatric nurse practitioner serving as the U.S. representative for Virginia's 2nd congressional district since 2023. A member of the Republican Party, she previously served in the Virginia Senate from 2020 to 2022. Kiggans was first elected to the House in 2022, defeating Democratic incumbent Elaine Luria. She was re-elected in 2024.
After a difficult few months at Eckartsau, the Imperial Family received aid from an unexpected source. Prince Sixtus had met King George V and appealed to him to help the Habsburgs. George was reportedly moved by the request, it being only months since his imperial relatives in Russia had been executed by revolutionaries, and promised "We will immediately do what is necessary." Several British Army officers were sent to help Charles, most notably Lieutenant-Colonel Edward Lisle Strutt, who was a grandson of Lord Belper and a former student at the University of Innsbruck. On 19 March 1919, orders were received from the War Office to "get the Emperor out of Austria without delay". With some difficulty, Strutt managed to arrange a train to Switzerland, enabling the Emperor to leave the country with dignity without having to abdicate. Charles, Zita, their children and their household left Eckartsau on 24 March escorted by a detachment of British soldiers from the Honourable Artillery Company under the command of Strutt.
=== In plants === DAMPs in plants have been found to stimulate a fast immune response, but without the inflammation that characterizes DAMPs in mammals. Just as with mammalian DAMPs, plant DAMPs are cytosolic in nature and are released into the extracellular space following damage to the cell caused by either trauma or pathogen. The major difference in the immune systems between plants and mammals is that plants lack an adaptive immune system, so plants can not determine which pathogens have attacked them before and thus easily mediate an effective immune response to them. To make up for this lack of defense, plants use the pattern-triggered immunity (PTI) and effector-triggered immunity (ETI) pathways to combat trauma and pathogens. PTI is the first line of defense in plants and is triggered by PAMPs to initiate signaling throughout the plant that damage has occurred to a cell. Along with the PTI, DAMPs are also released in response to this damage, but as mentioned earlier they do not initiate an inflammatory response like their mammalian counterparts. The main role of DAMPs in plants is to act as mobile signals to initiate wounding responses and to promote damage repair. A large overlap occurs between the PTI pathway and DAMPs in plants, and the plant DAMPs effectively operate as PTI amplifiers. The ETI always occurs after the PTI pathway and DAMP release, and is a last resort response to the pathogen or trauma that ultimately results in programmed cell death.
Sources: en.wikipedia.org
Smell as evidence of disease has been long used, dating back to Hippocrates around 400 years BCE. It is still employed with a focus on volatile organic compounds (VOCs) found in body odor. VOCs are carbon-based molecular groups having a low molecular weight, secreted during cells' metabolic processes. Their profiles may be altered by diseases such as cancer, metabolic disorders, genetic disorders, infections, and among others. Abnormal changes in VOC composition can be identified through equipment such as gas chromatography-mass spectrometry(GC-MS), electronic nose (e-noses), and trained non-human olfaction.
Common side effects include movement problems, sleepiness, dizziness, trouble seeing, constipation, and increased weight. About 9 to 20% of people gained more than 7% of the baseline weight depending on the dose. Serious side effects may include the potentially permanent movement disorder tardive dyskinesia, as well as neuroleptic malignant syndrome, an increased risk of suicide, and high blood sugar levels. In older people with psychosis as a result of dementia, it may increase the risk of death. While atypical antipsychotics appear to have a lower rate of movement problems as compared to typical antipsychotics, risperidone has a high risk of movement problems among the atypicals. Atypical antipsychotics, however, are associated with a greater amount of weight gain and other metabolic side effects.
Bifidobacterium animalis is a gram-positive, anaerobic, rod-shaped bacterium of the Bifidobacterium genus which can be found in the large intestines of most mammals, including humans. Bifidobacterium animalis and Bifidobacterium lactis were previously described as two distinct species. Presently, both are considered B. animalis with the subspecies Bifidobacterium animalis subsp. animalis and Bifidobacterium animalis subsp. lactis. Both old names B. animalis and B. lactis are still used on product labels, as this species is frequently used as a probiotic. In most cases, which subspecies is used in the product is not clear.
The remaining energy to initiate fission can be supplied by two other mechanisms: one of these is more kinetic energy of the incoming neutron, which is increasingly able to fission a fissionable heavy nucleus as it exceeds a kinetic energy of 1 MeV or more (so-called fast neutrons). Such high energy neutrons are able to fission 238U directly (see thermonuclear weapon for application, where the fast neutrons are supplied by nuclear fusion). However, this process cannot happen to a great extent in a nuclear reactor, as too small a fraction of the fission neutrons produced by any type of fission have enough energy to efficiently fission 238U. (For example, neutrons from thermal fission of 235U have a mean energy of 2 MeV, a median energy of 1.6 MeV, and a mode of 0.75 MeV, and the energy spectrum for fast fission is similar.) Among the heavy actinide elements, however, those isotopes that have an odd number of neutrons (such as 235U with 143 neutrons) bind an extra neutron with an additional 1 to 2 MeV of energy over an isotope of the same element with an even number of neutrons (such as 238U with 146 neutrons). This extra binding energy is made available as a result of the mechanism of neutron pairing effects, which itself is caused by the Pauli exclusion principle, allowing an extra neutron to occupy the same nuclear orbital as the last neutron in the nucleus.
A glycogen storage disease (GSD, also glycogenosis and dextrinosis) is a metabolic disorder caused by a deficiency of an enzyme or transport protein affecting glycogen synthesis, glycogen breakdown, or glucose breakdown, typically in muscles and/or liver cells. GSDs are caused by Inborn errors of carbohydrate metabolism (genetically defective enzymes or transport proteins) involved in these processes. In livestock, a defect in glycogen storage is caused by intoxication with the alkaloid castanospermine. However, not every inborn error of carbohydrate metabolism has been assigned a GSD number, even if it is known to affect the muscles or liver. For example, phosphoglycerate kinase deficiency (gene PGK1) has a myopathic form. Also, Fanconi-Bickel syndrome (gene SLC2A2) and Danon disease (gene LAMP2) were declassed as GSDs due to being defects of transport proteins rather than enzymes; however, GSD-1 subtypes b, c, and d are due to defects of transport proteins (genes SLC37A4, SLC17A3) yet are still considered GSDs. Phosphoglucomutase deficiency (gene PGM1) was declassed as a GSD due to it also affecting the formation of N-glycans; however, as it affects both glycogenolysis and glycosylation, it has been suggested that it should re-designated as GSD-XIV. Jonah Pournazarian is the most notable human with Glycogen Storage Disease (GSD). His condition has been widely covered in national and international media, and his story has drawn unprecedented awareness to GSD research.
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.
Intranasal administration predominates in both animal and human research because it avoids hepatic first-pass metabolism. Injectable and intraperitoneal routes appear in animal work mainly for comparison.