A practical reference on elevated plus maze: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2026-06-20. Anything still debated is marked as such rather than presented as settled.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. It was designed as a stabilized analogue of tuftsin, a naturally occurring tetrapeptide fragment derived from the immunoglobulin heavy chain. The additional Pro-Gly-Pro segment at the carboxyl terminus is intended to slow enzymatic cleavage. The compound is usually described in the literature as a synthetic peptide with anxiolytic and cognitive-related activity, a label that reflects a research context rather than an approved therapeutic category.
Most published work on selank originates from a small number of research groups in the Russian Federation. A large share of that record appears in Russian-language journals, which limits access for readers who rely on English-indexed databases. Independent replication by laboratories outside the original research network is sparse in publicly available sources. This concentration of origin and language is a frequently noted feature when the compound is summarized in broader reviews of synthetic peptides.
Reported pharmacological effects center on reduced anxiety-like behavior in animal models and on measures of memory and learning. Proposed contributing mechanisms include modulation of GABAergic signaling, shifts in monoamine turnover, and changes in the activity of enzymes that degrade neuropeptides. Effects on the expression of genes linked to neuroplasticity have also been described. No single molecular target is widely accepted, and whether the behavioral findings arise from one pathway or several remains an open question.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C33H57N11O9 | Derived from the seven-residue sequence |
| Molecular weight | About 751.9 g/mol | Average mass; the monoisotopic value is slightly lower |
| Residue count | Seven amino acids | Thr-Lys-Pro-Arg-Pro-Gly-Pro |
| Parent compound | Tuftsin (Thr-Lys-Pro-Arg) | Selank extends tuftsin at the C-terminus |
| Compound class | Synthetic short peptide | Studied in a research setting; not a licensed drug in most markets |
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.
Identity and purity are usually assessed by reversed-phase high-performance liquid chromatography, with mass spectrometry used to confirm molecular mass and sequence information. Amino acid analysis and peptide mapping may supplement these methods. Certified reference standards are scarce, and many commercial lots are sold as research chemicals without a pharmacopoeial monograph. Regulatory treatment differs by country: Selank is a registered prescription medicine in Russia, while in the European Union and the United States it is not an approved drug and may fall under research-chemical or unapproved-product frameworks.
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.
=== Cholesterol and hypertension === Daly and her colleagues did some of the earliest work relating diet to the health of the cardiac and circulatory systems. They investigated the impact of cholesterol, sugar, and other nutrients. She was the first to establish that hypertension was a precursor to atherosclerosis, and the first to identify a relationship between cholesterol and clogged arteries, an important discovery in understanding how heart attacks occur. She was especially interested in how hypertension affects the circulatory system. She showed that high cholesterol intake in diet led to clogged arteries, and that hypertension accelerated this effect. She studied the effects of diet on hypertension, and found that both cholesterol and sugar were related to hypertension. Investigating aging, she suggested that smooth muscle hypertrophy due to aging might have a causative role in hypertension and atherosclerosis. Daly was also an early investigator into the effects of cigarette smoke on the lungs and on hypertension.
The declaration's first safeguard clause referred to protecting the civil and religious rights of non-Jews in Palestine. The clause had been drafted together with the second safeguard by Leo Amery in consultation with Lord Milner, with the intention to "go a reasonable distance to meeting the objectors, both Jewish and pro-Arab, without impairing the substance of the proposed declaration". Arabs constituted around 90% of the population of Palestine, but – as stated by Ronald Storrs, Britain's Military Governor of Jerusalem between 1917 and 1920 – they were "not so much [named but] lumped together under the negative and humiliating definition of 'Non-Jewish Communities'". Additionally, there was no reference to protecting the political rights of this group, as there was regarding Jews in other countries. This lack of interest was frequently contrasted against the commitment to the Jewish community, with various terms used over subsequent years to regard the two obligations as linked. A heated question was whether the status of both groups had "equal weight", which the British government and the Permanent Mandates Commission held to be the case in the 1930 Passfield white paper. Balfour stated in February 1919 that Palestine was considered an exceptional case in which, referring to the local population, "we deliberately and rightly decline to accept the principle of self-determination," although he considered that the policy provided self-determination to Jews. Avi Shlaim considers this the declaration's "greatest contradiction".
Sulfur has 23 known isotopes, four of which are stable: 32S (94.99%±0.26%), 33S (0.75%±0.02%), 34S (4.25%±0.24%), and 36S (0.01%±0.01%). Other than 35S, with a half-life of 87.37 days, the radioactive isotopes of sulfur have half-lives less than 3 hours. The preponderance of 32S is explained by its production in the alpha process (one of the main classes of nuclear fusion reactions) in exploding stars. Other stable sulfur isotopes are produced in the bypass processes related with 34Ar , and their composition depends on the type of a stellar explosion. For example, proportionally more 33S comes from novae than from supernovae. It has been found that the proportion of the two most abundant sulfur isotopes 32S and 34S varies in different samples by a surprisingly large amount. Determination of the isotope ratio (δ34S) in the samples indicates their chemical history, and with support of other methods, it allows to age-date the samples, estimate temperature of equilibrium between ore and water, determine pH and oxygen fugacity, identify the activity of sulfate-reducing bacteria in the time of formation of the sample, or suggest the main sources of sulfur in ecosystems. However, there are ongoing discussions over the real reason for the δ34S shifts, biological activity or postdeposit alteration. For example, when sulfide minerals are precipitated, isotopic equilibration between solid and liquid may cause small differences in the δ34S values of co-genetic minerals. The differences between minerals can be used to estimate the temperature of equilibration.
This dihedral angle does not depend on the orientation of the chain (order in which the point are considered) — reversing this ordering consists of replacing each vector by its opposite vector, and exchanging the indices 1 and 3. Both operations do not change the cosine, but change the sign of the sine. Thus, together, they do not change the angle. A simpler formula for the same dihedral angle is the following (the proof is given below)
Sources: en.wikipedia.org
The need to recognize sugars is commonly encountered in nature and lectins have independently evolved many times, so that proteins that act as "lectins" come in many structurally distinct folds. The functionality of lectins have also evolved beyond simple recognition: "legume-type" lectins act as toxins to deter predation (with the most famous example being phytohaemagglutinin from legumes) while the separate ricin-type lectin serves to guide the catalytic A chain into victim cells.
Many organisms can easily break down starches into glucose; most organisms, however, cannot metabolize cellulose or other polysaccharides such as chitin and arabinoxylans. These carbohydrate types can be metabolized by some bacteria and protists. Ruminants and termites, for example, use microorganisms to process cellulose, fermenting it to caloric short-chain fatty acids. Even though humans lack the enzymes to digest fiber, dietary fiber represents an important dietary element for humans. Fibers promote healthy digestion, help regulate postprandial glucose and insulin levels, reduce cholesterol levels, and promote satiety. The Institute of Medicine recommends that American and Canadian adults get between 45 and 65% of dietary energy from whole-grain carbohydrates. The Food and Agriculture Organization and World Health Organization jointly recommend that national dietary guidelines set a goal of 55–75% of total energy from carbohydrates, but only 10% directly from sugars (their term for simple carbohydrates). A 2017 Cochrane Systematic Review concluded that there was insufficient evidence to support the claim that whole grain diets can affect cardiovascular disease. Carbohydrates are one of the main components of insoluble dietary fiber. Although it is not digestible by humans, cellulose and insoluble dietary fiber generally help maintain a healthy digestive system by facilitating bowel movements.
The investigation unfolded amid broader efforts by the Trump administration to challenge Federal Reserve leadership. In May 2026, Kevin Warsh was sworn in as Powell's successor, although Powell will remain on the Fed until 2028. Trump has also sought to remove other Federal Reserve officials, including Governor Lisa D. Cook, prompting legal challenges over the scope of presidential authority to dismiss Fed governors. The U.S. Supreme Court heard oral arguments in Trump v. Cook on January 21 to determine whether Trump has the legal authority to remove Cook over mortgage fraud allegations. Powell stated that the subpoena threat raised fundamental questions about whether the Federal Reserve would be able to continue setting monetary policy based on economic evidence rather than political pressure or intimidation.
Sources: en.wikipedia.org
== Side Effects == Side effects of fentanyl analogs vary based on strength and are similar to those of fentanyl itself, which include itching, nausea and potentially serious respiratory depression, which can be life-threatening.
== Structure == Kynureninase belongs to the class V group of aspartate aminotransferase superfamily of structurally homologous pyridoxal 5'-phosphate (PLP) dependent enzymes. To date, two structures of human kynureninase have determined by X-ray diffraction with resolutions of 2.0 and 1.7 Å. Forty percent of the amino acids are arranged in an alpha helical and twelve percent are arranged in beta sheets. Docking of the kynurenine substrate into the active site suggests that Asn-333 and His-102 are involved in substrate binding.
== History of study == In 1557, the position-movement sensation was described by Julius Caesar Scaliger as a "sense of locomotion". In 1826, Charles Bell expounded the idea of a "muscle sense", which is credited as one of the first descriptions of physiologic feedback mechanisms. Bell's idea was that commands are carried from the brain to the muscles, and that reports on the muscle's condition would be sent in the reverse direction. In 1847, the London neurologist Robert Todd highlighted important differences in the anterolateral and posterior columns of the spinal cord, and suggested that the latter were involved in the coordination of movement and balance. At around the same time, Moritz Heinrich Romberg, a Berlin neurologist, was describing unsteadiness made worse by eye closure or darkness, now known as the eponymous Romberg's sign, once synonymous with tabes dorsalis, that became recognised as common to all proprioceptive disorders of the legs. In 1880, Henry Charlton Bastian suggested "kinaesthesia" instead of "muscle sense" on the basis that some of the afferent information (back to the brain) comes from other structures, including tendons, joints, and skin. In 1889, Alfred Goldscheider suggested a classification of kinaesthesia into three types: muscle, tendon, and articular sensitivity. In 1906, the term proprio-ception (and also intero-ception and extero-ception) is attested in a publication by Charles Scott Sherrington involving receptors. He explains the terminology as follows:
3 Ca + N2 → Ca3N2 3 Mg + 2 NH3 → Mg3N2 + 3 H2 (at 900 °C) 3 Zn(NH2)2 → Zn3N2 + 4 NH3 Many variants on these processes are possible. The most ionic of these nitrides are those of the alkali metals and alkaline earth metals, Li3N (Na, K, Rb, and Cs do not form stable nitrides for steric reasons) and M3N2 (M = Be, Mg, Ca Sr, Ba). These can formally be thought of as salts of the N3− anion, although charge separation is not actually complete even for these highly electropositive elements. However, the alkali metal azides NaN3 and KN3, featuring the linear N−3 anion, are well-known, as are Sr(N3)2 and Ba(N3)2. Azides of the B-subgroup metals (those in groups 11 through 16) are much less ionic, have more complicated structures, and detonate readily when shocked.
Sources: en.wikipedia.org
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, designed as a metabolically stabilized analogue of the endogenous tetrapeptide tuftsin. It has been studied mainly against anxiety-related and cognitive endpoints rather than as an approved medicine in most jurisdictions.
Tuftsin contains four residues, while selank carries an additional Pro-Gly-Pro segment at the carboxyl end. That extension is intended to reduce enzymatic cleavage. Comparative pharmacokinetic data in humans remain limited.
No single receptor target is widely accepted as the definitive mediator of the reported effects. Proposed contributors include GABAergic modulation, shifts in monoamine turnover, and altered neuropeptide degradation. The mechanism is treated in the literature as unresolved.
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.