BDNF raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
Reviewed 2026-05-09. Anything still debated is marked as such rather than presented as settled.
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.
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.
Peptide bonds in selank are susceptible to hydrolysis under strongly acidic or basic conditions, and the terminal proline residues are vulnerable to exopeptidase activity in biological samples. Lyophilized powder stored dry at -20 °C typically remains stable for extended periods, whereas aqueous solutions degrade faster and may lose measurable purity within days to weeks depending on pH, temperature, and microbial load. Repeated freeze-thaw cycles promote aggregation and adsorption to container surfaces. For analytical work, solutions are usually prepared fresh, kept cold, and used within a single working day.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic heptapeptide | Analog of the tetrapeptide tuftsin |
| Sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Reported consistently across pharmacopoeial descriptions |
| Appearance | White to off-white lyophilized powder | Typical form of research-grade material |
| Solubility | Freely soluble in water | Aqueous buffers; poor in nonpolar solvents |
| Typical storage temperature | -20 degrees Celsius | Lyophilized powder; protect from moisture |
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.
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.
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.
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.
The United States has an established structure of foreign relations, with the world's second-largest diplomatic corps as of 2024. It is a permanent member of the United Nations Security Council and home to the United Nations headquarters. The United States is a member of the G7, G20, and OECD intergovernmental organizations. Almost all countries have embassies and many have consulates (official representatives) in the country. Likewise, nearly all countries host formal diplomatic missions with the United States, except Iran, North Korea, and Bhutan. Though Taiwan does not have formal diplomatic relations with the U.S., it maintains close unofficial relations. The United States regularly supplies Taiwan with military equipment to deter potential Chinese aggression. The country's geopolitical attention has increasingly turned to the Indo-Pacific, where the U.S. joined the Quadrilateral Security Dialogue and AUKUS. The United States has a "Special Relationship" with the United Kingdom and strong ties with Canada, Australia, New Zealand, the Philippines, Japan, South Korea, Israel, and several European Union countries such as France, Italy, Germany, Spain, and Poland. The U.S. works closely with its NATO allies on military and national security issues, and with countries in the Americas through the Organization of American States and the United States–Mexico–Canada Free Trade Agreement. The U.S. exercises full international defense authority and responsibility for Micronesia, the Marshall Islands, and Palau through the Compact of Free Association.
As Canadian pathology society did not have a registry, interested Canadian medical technologists sat for the Amereican ASCP MT certification instead. In 1939, the BOR publishes the first book outlining the educational curriculum for medical technologists entitled Curriculum for Schools of Medical Technology. In 1940, as other organizations began using the same designations, the initials MT(ASCP) were used. In 1944, due to travel wartime restrictions from World War II, the practical component of the certification was discontinued. In 1948, the written essay portion of the certification was deemed too cumbersome to assess, and the certification was switched to a multiple choice and true-false assessment that could be graded on a machine and provide exam statistics. In 1949, the BOR changed the exam format to a 200 multiple choice question exam as the multiple choice questions were found to be a more reliable indicator than true-false questions. In 1949, the BOR also created the Board of Schools (BOS) for registering schools. In 1958, BoR and ASMT assisted with the reclassification of medical technologists, putting them at the professional level in the Civil Service and allowing medical technologists to gain commission status in the US military. In 1962, the BoR began requiring 3 years of college for the MT certification. In 1972, the BoR began requiring a Bachelor's degree for the MT certification. There were 100,000 certificates issued by 1975, 200,000 by 1980, 300,000 by 1991, 400,000 by 2005, and 500,000 by 2014.
Beta blockers have a variety of drug interactions. An example is that various beta blockers including propranolol, carvedilol, nebivolol, timolol, and metoprolol are metabolized by the cytochrome P450 enzyme CYP2D6 and may be potentiated by CYP2D6 inhibitors like fluoxetine, paroxetine, duloxetine, and bupropion. This may increase the risk of adverse effects like bradycardia and hypotension.
== Treatment == There have been no controlled studies to define the optimal treatment for BPDCN. Studies on small numbers of individuals with the disease have found that the standard chemotherapy regimens used for the initial induction treatments of AML, acute lymphoblastic leukemia, and high-grade lymphoma give complete remission rates of 77%, 93%, and 80%, respectively, in childhood PBDN and 47%, 77%, and 53%, respectively, in adult PBDN. However, these remissions were short-lived: post-treatment mean times to relapse or death were 12 months for children and 6.8 months for adults. Given these poor remission and survival rates, other treatments have been added to the initial treatment regimens. Studies have shown that the addition of intrathecally administered drugs (administered directly into the spinal canal) as prophylaxis prolongs the period of CNS-free disease and increases overall survival. Hematopoietic stem cell transplantation following initial chemotherapy-induced remission also prolongs these remissions and, it is suggested, offers potential for curing the disease. (A graft-versus-leukemia effect may have contributed to the benefits seen after transplantation.) Studies have not yet determined whether allogenic (i.e. taken from others) or autologous (i.e. taken from self) stem cells achieve better results, although one retrospective study in Japan found that autologous stem cells gave significantly better overall and progression-free survival rates.
Freeze-dried ice cream, also called astronaut ice cream or space ice cream, is ice cream that has had most of the water removed from it by a freeze-drying process. Compared to regular ice cream, it can be kept at room temperature without melting, is dry and more brittle and rigid, but still soft when bitten into. It was developed by Whirlpool Corporation under contract to NASA for the Apollo missions. However, it was not used on any Apollo mission. Freeze-dried foods were developed so that foods could be sent on long-duration spaceflights (e.g. to the Moon), and to reduce the weight of the water and oxygen (which both play a significant role in food deterioration) normally found in food. The process of freeze-drying also eliminates the possibility of food melting and spilling as liquid in zero-gravity, which would be difficult to manage during missions. Freeze-drying (or lyophilization) removes water from the ice cream by lowering the air pressure to a point where ice sublimates directly from a solid to a gas. The ice cream is first placed in a vacuum chamber and frozen until any remaining water crystallizes. The air pressure is then lowered below water's triple point, creating a partial vacuum, forcing air out of the chamber; next, heat is applied, sublimating the ice; finally a freezing coil traps and turns the vaporized water into ice. This process continues for hours, resulting in a freeze-dried ice cream slice.
Sources: en.wikipedia.org
Since the first formal cooperation treaties between Angola and the Soviet Union in 1976, the military sphere had constituted the pivot of Angolan-Soviet relations. The Soviet Navy benefited from its use of Angolan ports to stage exercises throughout the southern Atlantic and even negotiated with FAPLA for the construction of permanent bases. Luanda was named the regional headquarters for the 30th Operation Squadron of the Soviet Navy's Northern Fleet, which comprised eleven warships, three of which were in the port at any given time. From January 1976 onward, it also replaced Conakry as the primary base for Soviet Tupolev Tu-95 reconnaissance flights along Africa's western coast. Article 16 of the Angolan constitution banned the construction of foreign military bases, but exceptions could be made if base rights were considered essential to the country's national defence. The Soviet Union justified its continued air and naval presence as necessary measures to protect Angola from a South African invasion. One senior Soviet military official, General Valery Belyaev, remarked that the 30th Operational Squadron was, "by the very fact of its presence...restraining the South African aggression against Angola." In exchange for granting base rights, FAPLA became the beneficiary of more sophisticated Soviet arms. After Operation Sceptic, the Soviet Union transferred over 500 million dollars' worth of military equipment to FAPLA, the bulk of it apparently concentrated on air defence.
negative supercoiling The supercoiling of a double-stranded DNA molecule in the direction opposite to the turn of the double helix itself (e.g. a left-handed coiling of a helix with a right-handed turn). Contrast positive supercoiling.
The Tolkiens had four children: John Francis Reuel Tolkien (17 November 1917 – 22 January 2003), Michael Hilary Reuel Tolkien (22 October 1920 – 27 February 1984), Christopher John Reuel Tolkien (21 November 1924 – 16 January 2020) and Priscilla Mary Anne Reuel Tolkien (18 June 1929 – 28 February 2022). Tolkien was very devoted to his children and sent them illustrated letters from Father Christmas when they were young.
Alexander George Ogston FAA FRS (30 January 1911 – 29 June 1996) was a British biochemist who specialised in the thermodynamics of biological systems. He was a grandson of Sir Alexander Ogston, a Scottish surgeon who discovered Staphylococcus.
Non-resorbable membranes: The main types of non-resorbable barrier membranes are expanded polytetrafluoroethylene (e-PTFE), high-density polytetrafluoroethylene (d-PTFE), titanium mesh and titanium-reinforced PTFE. Expanded polytetrafluoroethylene (e-PTFE) became the most common non-resorbable membrane used for bone regeneration in the 1990s. Gore-Tex was the most popular type of e-PTFE. The e-PTFE membrane is sintered with pores of 5 - 20 μm within the framework of the material. The e-PTFE membrane behaves as a barrier to prevent fibroblasts and various connective-tissue cells from entering the bone defect in order to allow the slower moving cells that are osteogenic to repopulate the defect. A study used e-PTFE membranes to cover surgically constructed average size bone defects in the mandibular angles of rats. Consequently, the e-PTFE membrane acted as a barrier to soft tissue and sped up bone healing, which took place between 3–6 weeks while no healing occurred in the non-membrane control group during a 22 week period. The biological method of osteopromotion by exclusion is good for predicting ridge growth or defect regeneration. Resorbable membranes: There are many different types of resorbable membranes out there but the main ones are synthetic polymers and natural biomaterials. Synthetic polymers are such that it is a polylactic acid bilayer, or the collagen-derived membranes. These membranes can be obtained from bovine or porcine or dermis. E.g.
Sources: en.wikipedia.org
A transdermal gel was formulated to address this but plasma concentrations were undetectable. In cats oral tramadol at 6 mg/kg provides equivalent analgesia to intramuscular tramadol at 4 mg/kg. One study comparing tramadol to meperidine found tramadol to be more effective at providing analgesia for cats undergoing ovariohysterectomy. A study looking at treatment of osteoarthritis in geriatric cats found owner-reported improvements but also significant adverse effects. Reported adverse effects of tramadol include: diarrhoea, dysphoria, anorexia, tachycardia, pyrexia, tachypnoea, and increased levels of serotonin leading to agitation. Tramadol has the potential to cause serotonin syndrome when administered alongside serotonin re-uptake inhibitors, monoamine oxidase inhibitors, and tricyclic antidepressants. In horses, tramadol is ineffective by itself. Two studies looking at intravenous tramadol found it provided no thermal or mechanical antinociception, another study looking at oral tramadol for chronic laminitis found it provided minimal analgesia, and another study looking at intraarticular tramadol found it provided no post-operative analgesia following arthroscopy; however, when administered with paracetamol (acetaminophen) tramadol provides short-acting mechanical antinociception and when administered with ketamine oral tramadol provides adequate analgesia for chronic laminitis. Based on this evidence tramadol is not recommended to be provided on its own for analgesia in horses.
28 February to 28 February 1971 The 11th Light Infantry Brigade launched Operation Iron Mountain to attack PAVN/VC bases and logistics routes in southeastern Quảng Ngãi Province. The operation resulted in 4,589 PAVN/VC killed and 137 captured while U.S. losses are 440 killed.
=== Controversy === Newborn screening tests have become a subject of political controversy in the last decade. Lawsuits, media attention, and advocacy groups have surfaced a number of different, and possibly countervailing, positions on the use of screening tests. Some have asked for government mandates to widen the extent of the screening to find detectable and treatable birth defects. Others have opposed mandatory screening concerned that effective follow-up and treatment may not be available, or that false positive screening tests may cause harm to infants and their families. Others have learned that government agencies were often secretly storing the results in databases for future genetic research, often without consent of the parents nor limits on how the data could be used in the future . In the UK a campaign called the Newborn Screening Collaborative, 17 small rare disease organisations including Genetic Alliance UK, have joined together to raise awareness surrounding this issue and promote the positives of early diagnosis.
Smoking, involves burning and inhaling cannabinoids ("smoke") from small pipes, bongs (portable versions of hookahs with a water chamber), paper-wrapped joints, tobacco-leaf-wrapped blunts, or the like. Vaporizing, heating various forms of cannabis to 165–190 °C (329–374 °F), causing the active ingredients to form vapor without combustion of the plant material (the boiling point of THC is 157 °C (315 °F) at atmospheric pressure). Edibles, adding cannabis as an ingredient to a wide variety of foods, including butter and baked goods. In India it is commonly consumed as the beverage bhang. Cannabis tea, prepared with attention to the lipophilic quality of THC, which is only slightly water-soluble (2.8 mg per liter), often involving cannabis in a saturated fat. Tincture of cannabis, sometimes known as green dragon, is an alcoholic cannabis concentrate. Capsules, typically containing cannabis oil, and other dietary supplement products, for which some 220 were approved in Canada in 2018.
== Assessment and treatment == Assessment can be difficult because much of the damage is often internal and not visible. The patient is thoroughly examined. X-ray and CT scanning may be used to identify the type and location of potentially lethal injuries. Sometimes before an X-ray is performed on a person with penetrating trauma from a projectile, a paper clip is taped over entry and exit wounds to show their location on the film. The patient is given intravenous fluids to replace lost blood. Surgery may be required; impaled objects are secured into place so that they do not move and cause further injury, and they are removed in an operating room. If the location of the injury is not obvious, a surgical operation called an exploratory laparotomy may be required to look for internal damage to the organs in the abdomen. Foreign bodies such as bullets may be removed, but they may also be left in place if the surgery necessary to get them out would cause more damage than would leaving them. Wounds are debrided to remove tissue that cannot survive and other material that presents risk for infection. Negative pressure wound therapy is no more effective in preventing wound infection than standard care when used on open traumatic wounds.
Sources: en.wikipedia.org
Selank is a synthetic seven-amino-acid peptide modeled on tuftsin, a fragment of the immunoglobulin G heavy chain. It was designed in Russia to combine anxiolytic and immunomodulatory properties in one molecule.
The first four residues of Selank reproduce the tuftsin sequence Thr-Lys-Pro-Arg. A Pro-Gly-Pro extension at the C-terminus was added to slow enzymatic breakdown and extend residence time.
It holds marketing authorization in Russia, where nasal drop formulations are sold. No equivalent approval exists in the European Union, the United States, or most other countries.
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.