Everything below concerns elevated plus maze. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2026-08-01. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Dry storage temperature | -20 C or below | Sealed, desiccated, protected from light |
| Solution stability | Hours to days at 2-8 C | Depends on buffer and microbial load |
| Preferred pH range | Near neutral to slightly acidic | Alkaline pH accelerates hydrolysis |
| Main degradation routes | Hydrolysis and deamidation | No cysteine or methionine in sequence |
| Identity confirmation | Electrospray mass spectrometry | Observed mass compared with 751.9 Da |
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.
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.
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.
Purity assessment relies mainly on reverse-phase high-performance liquid chromatography with ultraviolet detection. Because the peptide lacks a strong chromophore, detection often uses backbone absorbance near 214 nm. Identity is confirmed by mass spectrometry, typically electrospray ionization or matrix-assisted laser desorption, comparing the measured mass against the expected value. Amino acid analysis can verify composition after acid hydrolysis. Diastereomer content and residual counterions are reported less often, although both can influence biological assays.
Selank is a hydrophilic peptide and dissolves readily in water and in aqueous buffers. The lyophilised powder is typically a white to off-white solid. Because short peptides are prone to hydrolysis and oxidation, handling benefits from limiting exposure to heat, moisture and strong light. Working solutions are commonly prepared in sterile water or saline, and repeated freeze-thaw cycles are avoided to reduce aggregation and loss of activity. These practices reflect general laboratory convention rather than published stability specifications.
Dry powder is normally held at -20 degrees Celsius or lower, in a sealed container with desiccant and protection from light. Reconstituted solutions are usually kept at 2 to 8 degrees Celsius for short periods and frozen for longer ones. Proline residues at several positions are generally associated with some resistance to peptidase attack, but chemical stability still declines at neutral to alkaline pH and at elevated temperature. Exact shelf-life figures are product-specific and are not standardised across suppliers.
They identified positive traits displayed by heroes, then determined if the presence of these traits in students predicted future intent to cheat. The results of their research: 'an effective working model of heroism in the context of the academic environment' (Staats, Hupp & Hagley, 2008).
Brower has been credited with popularizing the term "ecological chemistry" which appeared in the title of a paper he published in Science in 1968 and again the following year in an article he wrote for Scientific American, where the term also appeared on the front cover under an image of a giant bluejay towering over two monarch butterflies. The specialized Journal of Chemical Ecology was established in 1975, and the Journal Chemoecology was founded in 1990. In 1984, the International Society of Chemical Ecology was established and in 1996, the Max Planck Institute of Chemical Ecology was founded in Jena, Germany.
Several new methods for DNA sequencing were developed in the mid to late 1990s and were implemented in commercial DNA sequencers by 2000. Together these were called the "next-generation" or "second-generation" sequencing (NGS) methods, in order to distinguish them from the earlier methods, including Sanger sequencing. In contrast to the first generation of sequencing, NGS technology is typically characterized by being highly scalable, allowing the entire genome to be sequenced at once. Usually, this is accomplished by fragmenting the genome into small pieces, randomly sampling for a fragment, and sequencing it using one of a variety of technologies, such as those described below. An entire genome is possible because multiple fragments are sequenced at once (giving it the name "massively parallel" sequencing) in an automated process. NGS technology has tremendously empowered researchers to look for insights into health, anthropologists to investigate human origins, and is catalyzing the "Personalized Medicine" movement. However, it has also opened the door to more room for error. There are many software tools to carry out the computational analysis of NGS data, often compiled at online platforms such as CSI NGS Portal, each with its own algorithm. Even the parameters within one software package can change the outcome of the analysis. In addition, the large quantities of data produced by DNA sequencing have also required development of new methods and programs for sequence analysis.
A wobble base pair is a pairing between two nucleotides in RNA molecules that does not follow Watson–Crick base pair rules. The four main wobble base pairs are guanine–uracil (G–U), hypoxanthine–uracil (I–U), hypoxanthine–adenine (I–A), and hypoxanthine–cytosine (I–C). In order to maintain consistency of nucleic acid nomenclature, "I" is used for hypoxanthine because hypoxanthine is the nucleobase of inosine; nomenclature otherwise follows the names of nucleobases and their corresponding nucleosides (e.g., "G" for both guanine and guanosine – as well as for deoxyguanosine). The thermodynamic stability of a wobble base pair is comparable to that of a Watson–Crick base pair. Wobble base pairs are fundamental in RNA secondary structure and are critical for the proper translation of the genetic code.
denotes a surface integral over that closed surface, q is the total amount of the quantity in the volume V, j is the flux of q, t is time, Σ is the net rate that q is being generated inside the volume V per unit time. When q is being generated (i.e., when
Sources: en.wikipedia.org
There is no disease-modifying treatments proven to cure Alzheimer's disease, and because of this, AD research has focused on interventions to prevent the onset and progression. There is no evidence that supports any particular measure in preventing AD, and studies of measures to prevent the onset or progression have produced inconsistent results. Epidemiological studies have proposed relationships between an individual's likelihood of developing AD and modifiable factors, such as medications, lifestyle, and diet. There are some challenges in determining whether interventions for AD act as a primary prevention method, preventing the disease itself, or a secondary prevention method, identifying the early stages of the disease. These challenges include duration of intervention, different stages of disease at which intervention begins, and lack of standardization of inclusion criteria regarding biomarkers specific for AD. Further research is needed to determine factors that can help prevent AD.
== History == The incidence of acute rheumatic fever and rheumatic heart disease is not declining. Recent figures quote the incidence of Acute Rheumatic Fever as 0.6–0.7/1,000 population in the United States and Japan compared with 15–21/1,000 population in Asia and Africa. The prevalence of Acute Rheumatic Fever and Sydenham's Chorea has declined progressively in developed countries over the last decades.
=== Fundamental Materials Science === Quantum dots can also be used to study fundamental effects in materials science. By coupling two or more such quantum dots, an artificial molecule can be made, exhibiting hybridization even at room temperature. Precise assembly of quantum dots can form superlattices that act as artificial solid-state materials that exhibit unique optical and electronic properties.
== International law == Trump's proposal for Gaza is against international law; the forcible transfer of populations is prohibited. Members of Trump's administration have walked back on elements of the plan on a few occasions, although in one subsequent statement, Trump held firm to his original plan. On 21 February 2025, after opposition from Arab states, Trump said he would "recommend" but not enforce his plan for the American takeover of Gaza and the re-settlement of the Palestinian population. Arab League leaders met in March to create a counter proposal to Trump's plan, which was rejected by the US and Israel due to concerns about the proposed governance of postwar Gaza and other issues. The White House released a statement that Trump stood by his vision of Gaza without Hamas and welcomed additional talks. In July, Netanyahu met with Trump and reiterated support for the plan of relocating Palestinians, saying it was "free choice" if Palestinians wanted to stay or leave. The US and Israel were working to identify cooperating countries for the plan.
During transport water needs to be maintained to a high quality, with regulated temperature, sufficient oxygen and minimal waste products. In some cases anaesthetics may be used in small doses to calm fish before transport. Aquaculture is sometimes part of an environmental rehabilitation program or as an aid in conserving endangered species.
Sources: en.wikipedia.org
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.
Hydrolysis of peptide bonds and deamidation of arginine and proline residues are the main degradation routes. Alkaline pH and higher temperatures accelerate both processes. Buffered, near-neutral solutions stored cold generally degrade more slowly than unbuffered ones.
Reverse-phase chromatography gives the clearest single view of related impurities and truncated sequences. Mass spectrometry then confirms that the main peak carries the expected mass. Neither test detects enantiomeric impurities, which require a separate chiral assay.
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.