Everything below concerns Certificate of analysis. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2026-08-01. Numbers and descriptions here follow the published literature rather than marketing material.
Handling follows standard practice for research peptides. Material is weighed in a low-humidity environment because the powder absorbs atmospheric moisture. Purity is reported as the percentage area of the main peak in a chromatogram, with specifications commonly set at 95 percent or higher; values below that threshold indicate the presence of truncated or modified species. Residual trifluoroacetate from purification is often present and may affect mass balance. Certificates of analysis should state the analytical method, the column and gradient used, and the lot-specific retention time so that results can be compared across suppliers.
Identity and purity of selank are established with reversed-phase high-performance liquid chromatography coupled to mass spectrometry. The peptide elutes from C18 columns with acetonitrile gradients in water containing trifluoroacetic acid or formic acid, and detection is usually performed by ultraviolet absorbance near 214 nm. Electrospray ionization in positive mode gives a doubly protonated ion near m/z 377, consistent with a mass of about 752 Da. Amino acid analysis or tandem mass spectrometry of fragment ions confirms the sequence. Because the molecule has no aromatic residues, it lacks a usable 280 nm chromophore, so low-wavelength detection or mass spectrometry is required.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Identity confirmation | Reversed-phase HPLC retention time versus reference standard | Retention depends on column, gradient, and ion-pairing agent |
| Mass confirmation | Electrospray or MALDI mass spectrometry | Doubly protonated ion near m/z 377 is consistent with about 752 Da |
| Typical purity specification | 95 percent or higher by chromatographic peak area | Lower values suggest truncated or modified peptide species |
| Storage of lyophilized powder | -20 °C, desiccated, protected from light | Powder tolerates long storage better than solution |
| Storage of solution | 2-8 °C for short periods | Freeze-thaw cycling promotes aggregation and surface adsorption |
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.
The compound has a calculated molecular weight near 751.9 daltons and carries a net positive charge at physiological pH because of its arginine residue. It dissolves freely in water and in common aqueous buffers, and typically appears as a white or off-white lyophilized powder. The amide backbone makes the molecule susceptible to peptidases, which limits oral use and favors intranasal or parenteral routes. Nomenclature in the literature varies: the substance is also described by the sequence abbreviation TP-7 and by a Russian trade designation.
Animal studies have examined behaviour in tests of anxiety, memory retention and stress response, and several report changes in neurotrophic or neurotransmitter-related markers. The human evidence base is much smaller, consisting mainly of short trials conducted in Russia with limited reporting in English-language journals. Sample sizes are modest and outcome measures vary between studies, so the findings are best described as preliminary. Independent replication under modern trial standards has not been widely reported.
Outside its country of origin the compound is generally handled as a research chemical rather than an approved medicine. No regulatory approval from the United States Food and Drug Administration or the European Medicines Agency has been granted for human use. Identity and purity are normally checked by reverse-phase high-performance liquid chromatography, with mass spectrometry used to confirm the molecular mass. Lyophilised material is stored cold and desiccated, and repeated freeze-thaw cycles are avoided.
Published work on this peptide almost always uses intranasal delivery, with drops or a spray applied to the nasal mucosa. Some animal experiments have used subcutaneous or intraperitoneal injection, and a smaller number have compared routes directly. Oral administration is not a focus of the literature, because short peptides of this size are broken down by digestive enzymes and cross intestinal barriers poorly. How much of an intranasal dose reaches the bloodstream intact in humans remains an open question.
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.
April 9: Law establishing the postal savings bank: regardless of her marital status, a wife does not need her husband's permission to open a postal savings account or withdraw money from it—unless the husband expressly objects. June 16: Law establishing free primary education in public schools: these also include girls' schools in communes with more than 400 inhabitants. August 2: Decree organizing nursery schools—coeducational, they accept children aged 2 to 7; all directors and workers are women; female general and departmental inspectors are assigned to their oversight. Girls are granted access to secondary education, with specific provisions and a diploma different from the baccalaureate (which boys may obtain). March 28, 1882: Law on mandatory primary education for both boys and girls between the ages of 6 and 13; school curricula differ only in that girls learn needlework and boys take military exercises. July 27, 1884: Law reinstating divorce. 1885
Gottron's sign is a pathognomonic cutaneous manifestation associated with dermatomyositis (DM), which is an inflammatory disorder affecting the skin and muscles. The primary lesion of dermatomyositis appears as a violaceous, macular erythema with a symmetric distribution, which may progress and become poikilodermatous (atrophic with telangiectasia and pigmentary changes) and indurated (as a result of mucin deposition). They were first described by Heinrich Adolf Gottron.
There are a number of different psychotherapies for depression which are provided to individuals or groups by psychotherapists, psychiatrists, psychologists, clinical social workers, counselors or psychiatric nurses. With more chronic forms of depression, the most effective treatment is often considered to be a combination of medication and psychotherapy. Psychotherapy is the treatment of choice in people under 18. A meta-analysis examined the effectiveness of psychotherapy for depression across ages from younger than 13 years to older than 75 years. It summarizes results from 366 trials included 36,702 patients. It found that the best results were for young adults, with an average effect size of g=.98 (95% CI, 0.79–1.16). The effects were smallest for young children (<13 years), g = .35 (95% CI, 0.15–0.55), and second largest in the oldest group, g = .97 (95% CI, 0.42–1.52). The study was not able to compare the different types of therapy to each other. Most of the studies with children used therapies originally developed with adults, which may have reduced the effectiveness. The greater benefits with young adults might be due to a large number of studies including college students, who might have an easier time learning therapy skills and techniques. Most of the studies in children were done in the US, whereas in older age groups, more balanced numbers of studies came from Europe and other parts of the world as well.
In the Earth's crust, the concentration of helium is 8 parts per billion. In seawater, the concentration is only 4 parts per trillion. There are also small amounts in mineral springs, volcanic gas, and meteoric iron. Because helium is trapped in the subsurface under conditions that also trap natural gas, the greatest natural concentrations of helium on the planet are found in natural gas, from which most commercial helium is extracted. The concentration varies in a broad range from a few ppm to more than 7% in a small gas field in San Juan County, New Mexico. As of 2021, the world's helium reserves were estimated at 31,000,000,000 cubic metres (1.1×1012 cu ft), with a third of that being in Qatar. In 2015 and 2016 additional probable reserves were announced to be under the Rocky Mountains in North America and in the East African Rift. The Bureau of Land Management (BLM) has proposed an October 2024 plan for managing natural resources in western Colorado. The plan involves closing 543,000 acres to oil and gas leasing while keeping 692,300 acres open. Among the open areas, 165,700 acres have been identified as suitable for helium recovery. The United States possesses an estimated 8.7×109 m3 (306,000,000,000 cu ft) of recoverable helium, sufficient to meet current consumption rates of 61,000,000 m3 (2,150,000,000 cu ft) per year for approximately 150 years.
Sources: en.wikipedia.org
Recreationally, methamphetamine's ability to increase energy has been reported to lift mood and increase sexual desire to such an extent that users are able to engage in sexual activity continuously for several days while binging the drug. Methamphetamine is known to possess a high abuse liability (a high likelihood that extratherapeutic use will lead to compulsive drug use) and high psychological dependence liability (a high likelihood that withdrawal symptoms will occur when methamphetamine use ceases). Discontinuing methamphetamine after heavy use may lead to a post-acute-withdrawal syndrome, which can persist for months beyond the typical withdrawal period. At high doses, like other substituted amphetamines, methamphetamine is neurotoxic to human midbrain dopaminergic neurons and, to a lesser extent, serotonergic neurons. Methamphetamine neurotoxicity causes adverse changes in brain structure and function, such as reductions in grey matter volume in several brain regions, as well as adverse changes in markers of metabolic integrity.
8 June Following a meeting at Midway Island between Nixon and Thiệu, Nixon announced that 25,000 American troops would be withdrawn from South Vietnam by the end of August, starting the process of Vietnamization. First Lieutenant Sharon Ann Lane, an army nurse at the 312th Evacuation Hospital at Chu Lai Base Area, was killed in a PAVN rocket attack. She was the only U.S. servicewoman killed by hostile fire during the war. The PAVN 90th Regiment attacked the night defensive position of the 1st Battalion, 5th Marines in the "Arizona Territory" northeast of An Hoa Combat Base. The Marines repelled the assault and pursued the PAVN throughout the day resulting in more than 185 PAVN killed.
The Levey–Jennings chart differs from the Shewhart individuals control chart because the standard deviation (σ, "sigma") is estimated. The Levey–Jennings chart uses the long-term (i.e., population) estimate of sigma whereas the Shewhart chart uses the short-term (i.e., within the rational subgroup) estimate.
Sources: en.wikipedia.org
== External links == How wounds heal and tumors form With this simple Flash demonstration, Harvard professor Donald Ingber explains how wounds heal, why scars form, and how tumors develop. Presented by Children's Hospital Boston. Wound Healing and Repair Lorenz H.P. and Longaker M.T. Wounds: Biology, Pathology, and Management. Stanford University Medical Center. Romo T. and McLaughlin L.A. 2003. Wound Healing, Skin. Emedicine.com. Rosenberg L. and de la Torre J. 2003. Wound Healing, Growth Factors. Emedicine.com. After the Injury- Children's Hospital Of Philadelphia
However, unjustified self-medicated preventive administration of stable KI is not recommended in order to avoid disturbing the normal thyroid function. Such a treatment must be carefully dosed and requires an appropriate KI amount prescribed by a specialised physician.
Biopharmaceuticals may be produced from microbial cells (e.g., recombinant E. coli or yeast cultures), mammalian cell lines (see Cell culture) and plant cell cultures (see Plant tissue culture) and moss plants in bioreactors of various configurations, including photo-bioreactors. Important issues of concern are cost of production (low-volume, high-purity products are desirable) and microbial contamination (by bacteria, viruses, mycoplasma). Alternative platforms of production which are being tested include whole plants (plant-made pharmaceuticals).
(2026) describe molars of Helarctos malayanus praemalayanus from the Pleistocene strata of the Tham Hai Cave (Vietnam), and interpret the fossil record from Southeast Asia as indicative of larger body size of Middle Pleistocene sun bears compared to their extant relatives. Probable fossil material of the Asian black bear, representing the first known record of a member of this lineage from northeastern Iberian Peninsula, is described from the Middle Pleistocene strata from Llers Quarry (Spain) by Rufí et al. (2026). Gutiérrez-Carbajal et al. (2026) reconstruct the evolutionary history of cave bears from southwestern Europe on the basis of data from enamel proteomic analysis, recovering Ursus dolinensis as a basal member of the cave bear lineage. Kochnev et al. (2026) study the variation of the size and shape of the hard palate and choanae of Ursus kanivetz and Ursus rossicus, and report possible evidence of a link between the hard palate form and the climate. A study on the ecology of cave bears from Galería 1 inside the Cueva de Guantes (Palencia, Spain) as indicated by isotopic composition of tooth enamel and bone collagen is published by Rodríguez-Franco et al. (2026). Hasegawa et al. (2026) study the distribution of brown bears in the Japanese Archipelago during the Late Pleistocene, reporting remains of exceptionally large individuals from Aomori, Nagano, Shizuoka and Oita. Estraviz-López et al.
Sources: en.wikipedia.org
Identity is confirmed by matching the retention time in reversed-phase chromatography against a reference standard and by measuring the molecular mass with mass spectrometry. Tandem mass spectrometry or amino acid analysis can verify the sequence of the seven residues. Because the peptide contains no aromatic amino acids, detection at 280 nm is not useful.
Lyophilized powder is normally stored desiccated at -20 °C, protected from light and moisture. Powder kept under these conditions is generally stable for long periods. Solutions are less stable and are usually prepared immediately before use.
A purity value from one chromatographic method does not capture every possible impurity. Related peptides with similar retention behavior, counterions, and residual solvents may not appear in the same analysis. Independent testing with an orthogonal method provides stronger assurance of identity and content.
Dry powder is normally held at -20 degrees Celsius or below in a sealed, light-protected container with desiccant. Brief room-temperature handling during weighing is generally tolerated. Storage instructions vary between suppliers, so the accompanying certificate of analysis should be followed.