GABA-A receptor comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Last reviewed on 2026-08-01. 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 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.
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.
| 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 |
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.
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.
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.
The superficial layer of transitional epithelium is connected to the basal layer via cellular projections, such as intermediate filaments protruding from the cellular membrane. These structural elements cause the epithelium to allow distension; however, these also cause the tissue to be relatively fragile and, therefore, difficult to study.
He also established that the acid was readily soluble in cold ether and absolute alcohol, and unlike lichesterinic acid, could reduce potassium permanganate solution in the cold. Further work by Böhme in 1903 showed that the compound had a specific rotation of +29.3° and could decompose under reduced pressure (40mm) to form C18H32O3. Later work by Asano and Asahina established that natural protolichesterinic acid actually has a negative specific rotation ([α]D = −12.71°), indicating it is the (−)-(2S,3R) enantiomer, while the material studied by Zopf and Böhme was the (+)-(2R,3S) form.
In May 2022, Grand Commander Viñas Alonso was prevented by the State Security Unit from traveling on official business to the United States to attend several Freemasonic and Masonic events, including the Summit of the Americas in Los Angeles. The State Security Unit continued their campaign to remove Viñas Alonso from power, and began communicating with the Supreme Court of Masonic Justice to launch an investigation into his "misconduct," and to strip him of his Masonic rights. On May 20, 2022, the Grand Lodge of Cuba hosted a centenary celebration of the 1902 Proclamation of the Republic of Cuba. In September, 2022, the High Chamber of the Supreme Court of Masonic Justice approved a letter to be delivered to President Díaz-Canel officially requesting that May 20 be observed as a national holiday, despite Díaz-Canel's past public rejection of the May 20th movement. Sometime later in 2022, Alfonso Vidal was approached by members of the State Security Unit to give evidence against Viñas Alonso, and to participate in the official expulsion of the Grand Commander from Freemasonry. State Security Unit agents took him to an office in Havana and attempted to cultivate him as an agent of the state. One agent in particular, who went by the codename Agente Poll, told him that his office had been assigned to monitor Freemasonry in Cuba for over 40 years, and had agents placed in Lodges all over Cuba.
Foot ulcers in diabetes require a multidisciplinary team that may include the primary care doctor, a diabetes nurse specialist, a tissue viability nurse, podiatrists, vascular surgeons, diabetes specialists and surgeons. An aim to improve glycemic control, if poor, may slow disease progression. When osteomyelitis is suspected to be involved in the foot, but not evidenced on an x-ray, an MRI scan should be obtained. In those with a high likelihood of osteomyelitis, a combination of x-ray and being able to probe to bone can reliably diagnose osteomyelitis without the need for more advanced imaging. A bone biopsy with culture is the gold standard for diagnosing osteomyelitis. With regards to infected foot ulcers, the presence of microorganisms is not in itself enough to determine whether an infection is present. Signs of an infection, such as erythema, purulence, fluctuance, swelling, warmth, or discharge, should also be present. The most common organism causing infection is staphylococcus. The treatment consists of debridement, appropriate bandages, managing peripheral arterial disease and appropriate use of antibiotics (against pseudomonas aeruginosa, staphylococcus, streptococcus and anaerobe strains), and arterial revascularization if necessary.
Sources: en.wikipedia.org
=== Books and book chapters === Bhatt is the Editor of the first and second editions of Cardiovascular Intervention: A Companion to Braunwald's Heart Disease and of Opie's Cardiovascular Drugs: A Companion to Braunwald's Heart Disease. He is one of the co-editors of Braunwald's Heart Disease. Elsevier credits him with a total of 11 titles as an author, chapter contributor, and editor.
Sucrose gradient centrifugation—a linear concentration gradient of sugar (typically sucrose, glycerol, or a silica-based density gradient media, like Percoll)—is generated in a tube such that the highest concentration is on the bottom and lowest on top. A protein sample is then layered on top of the gradient and spun at high speeds in an ultracentrifuge. This causes heavy macromolecules to migrate towards the bottom of the tube faster than lighter material. During centrifugation in the absence of sucrose, as particles move farther and farther from the center of rotation, they experience more and more centrifugal force (the further they move, the faster they move). The problem with this is that the useful separation range within the vessel is restricted to a small observable window. Spinning a sample twice as long does not mean the particle of interest will go twice as far; in fact, it will go significantly further. However, when the proteins are moving through a sucrose gradient, they encounter liquid of increasing density and viscosity. A properly designed sucrose gradient will counteract the increasing centrifugal force so the particles move in close proportion to the time they have been in the centrifugal field. Samples separated by these gradients are referred to as "rate zonal" centrifugations. After separating the protein/particles, the gradient is then fractionated and collected. In biochemistry, ultracentrifugation is valuable for separating biomolecules and analyzing their physical properties.
Radioactive thorium was used in the 1950s and 60s to treat tuberculosis and other benign diseases (including children), with serious consequences (see Peteosthor). A stabilized suspension of colloidal thorium(IV) oxide, co-developed by António Egas Moniz (1874-1954), was used from 1929 under the trade name Thorotrast as an X-ray contrast agent for angiography in several million patients worldwide until it was banned in the mid-1950s. It accumulates in the reticulohistiocytic system and can lead to cancer due to locally increased radiation exposure. The same is true for cholangiocarcinoma and angiosarcoma of the liver, two rare liver cancers. Carcinomas of the paranasal sinuses have also been described following administration of Thorotrast. Typical onset of disease is 30–35 years after exposure. The biological half-life of Thorotrast is approximately 400 years. The largest study in this area was conducted in Germany in 2004 and showed a particularly high mortality rate among patients exposed in this way. The median life expectancy over a seventy-year observation period was 14 years shorter than in the comparison group.
=== Photobiont === The photobiont partner of Parmotrema perlatum is from Trebouxia, a green algal genus belonging to the order Trebouxiales (order Chlorophyta). It has been identified as an undescribed species within a clade containing Trebouxia arboricola. A study compared the desiccation tolerance and physiological responses of lichenised Trebouxia to isolated cultures of the same alga. Both forms can survive extended desiccation, but with differing responses to photo-oxidative stress. Lichenisation enhances the photoprotective mechanisms of Trebouxia, improving quenching of excess light energy, particularly under high relative humidity, and controlling reactive oxygen species production under light exposure. However, isolated cultures showed better photosynthetic performance after desiccation recovery. This research demonstrates the mutual benefits of the lichen-photobiont partnership, where the alga gains a sheltered environment boosting its resilience to environmental stressors. Further studies on Parmotrema perlatum revealed specific antioxidant mechanisms supporting its photobiont under stress. The lichen shows high levels of reactive oxygen species scavenging enzymes such as superoxide dismutase and ascorbate peroxidase, protecting the photobiont from oxidative damage during dehydration and rehydration cycles. This enhanced antioxidant system provides not only physical shelter but also biochemical protection, increasing the photobiont's resilience to environmental fluctuations.
Microtubule-disruptive drugs like vinblastine, colcemid, and nocodazole have been reported to act by two mechanisms. At very low concentrations they suppress microtubule dynamics and at higher concentrations they reduce microtubule polymer mass. Recent findings indicate that they also produce microtubule fragments by stimulating microtubule minus-end detachment from their organizing centers. Dose-response studies further indicate that enhanced microtubule detachment from spindle poles correlate best with cytotoxicity. But research into the mechanism is still ongoing as recent studies also show vinblastine inducing apoptosis that is phase-independent in certain leukemias.
Sources: en.wikipedia.org
=== December === 1 December – Ireland's first space satellite, EIRSAT-1, was launched from Vandenberg Space Force Base in the United States, propelled by a Falcon 9 rocket. 6 December – A no confidence motion in Minister for Justice Helen McEntee was tabled in the Dáil by Sinn Féin and countered with a government motion expressing confidence in the minister. The government's confidence motion won, with 83 TDs voting that they had confidence in the minister and 63 TDs voting that they did not. 8 December – The funeral of singer Shane MacGowan took place at St Mary's of the Rosary Catholic Church in Nenagh, County Tipperary. 10 December – Property and vehicles were damaged after a tornado struck Leitrim Village in County Leitrim. 14 December – Twelve people, including eight Transition Year students, were injured in a serious crash between a school bus and a truck in Kilkenny. 16 December – Gymnast Rhys McClenaghan was voted 2023 RTÉ Sports Person of the Year. 17 December – Gardaí began investigating a "criminal damage incident" after a fire broke out at a disused hotel in Rosscahill, Oughterard that was due to accommodate asylum seekers. 20 December – Tánaiste Micheál Martin announced government plans to "initiate an inter-State case against the United Kingdom under the European Convention on Human Rights" over provisions in the Northern Ireland Troubles (Legacy and Reconciliation) Act 2023 which offers immunity from prosecution for certain Troubles-era related offences.
== Other uses == Caldwell 8 (NGC 559), an open cluster in Cassiopeia Celestron, 8-inch (200 mm) a Schmidt-Cassegrain telescope C8 carbine, an assault rifle used by Canada and other NATO forces made by Diemaco/Colt Canada C8 Unemployment Indemnity (Shipwreck) Convention, 1920 Elbrus-8C, a Russian 28 Nanometre 8 core microprocessor An international standard paper size (57×81 mm), defined in ISO 216
Acrogeria Berardinelli-Seip congenital lipodystrophy (congenital generalized lipodystrophy) Cockayne syndrome Ehlers–Danlos syndromes, progeroid form Gerodermia osteodysplastica Hallermann–Streiff syndrome Mandibuloacral dysplasia Neonatal progeroid syndrome (Wiedemann–Rautenstrauch syndrome) Nestor-Guillermo syndrome Penttinen syndrome Petty–Laxova–Weidemann progeroid syndrome POLR3A-related Wiedemann–Rautenstrauch syndrome PYCR1-related Wiedemann–Rautenstrauch-like syndrome Werner syndrome
This enabled them to make a number of major technological improvements, including the introduction of fiber suppressors (1981), a metal-free system eliminating sources of contamination and corrosion (1981), integrated workstation and process analysis capabilities (1984), suppressors for gradient elution (1986) and accelerated solvent extraction (1995). These technological changes made it possible for scientists to detect ionic materials quickly at extremely low levels of concentration. This increased both the sensitivity of the tests that it was possible to do and the productivity of the people doing them. Bowman recognized the importance of developing software and data handling capabilities in support of Dionex's hardware. Bowman has also emphasized the importance of marketing support, working closely with customers to ensure that they were satisfied with the products they were using, and developing new applications for customers' areas of interest. He has stated that, in his opinion, what distinguished Dionex was that "we do provide a complete solutions approach for our customers. We don't just sell them hardware and walk away. We work with them to make sure that what we sell them makes them more effective and productive in their job." Through such improvements, Dionex was able to support much faster extraction of organic compounds for analysis from chemical mixtures, including complicated samples such as soils, polymers, and processed foods.
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.