This is a working overview of mass spectrometry, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2025-12-16. Anything still debated is marked as such rather than presented as settled.
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.
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 |
|---|---|---|
| Principal proposed target | GABA-A receptor complex | Hypothesis derived mainly from animal pharmacology |
| Common behavioral assay | Elevated plus maze | Rodent test for anxiety-like behavior |
| Reported molecular marker | Hippocampal BDNF expression | Measured by immunoassay or mRNA quantification |
| Typical dosing route | Intranasal | Chosen to reduce first-pass metabolism |
| Reported plasma half-life | Minutes | Based on limited peptide stability data |
Lyophilized Selank, the dry powder form, is generally stored frozen at minus 20 degrees Celsius or colder for long-term keeping. The solid is hygroscopic and should stay sealed, dry, and protected from light. Once dissolved, the peptide is less stable and is usually held refrigerated at 2 to 8 degrees Celsius for short periods. Repeated freezing and thawing is avoided because it can promote aggregation and loss of activity. Buffers and pH choice also affect how long a solution remains usable.
Solubility behavior is a practical concern for handling. Selank dissolves readily in water and in common aqueous buffers, which simplifies preparation of working solutions. The choice of solvent, ionic strength, and pH can influence aggregation over time, particularly at higher concentrations. Aqueous solutions are typically sterile-filtered before use. Because stability depends on several variables, storage and handling notes should be treated as general guidance rather than fixed rules, and specific values are best confirmed against a certificate of analysis for each batch.
Characterization of Selank in a laboratory setting relies on standard peptide methods. Reverse-phase high-performance liquid chromatography separates the target from related impurities and provides a purity figure, commonly reported as 95 percent or higher. Mass spectrometry, typically electrospray ionization or matrix-assisted laser desorption, confirms the molecular mass and helps detect truncation or modification. Amino acid analysis can verify composition when a sequence-level check is needed. These techniques together establish identity and purity for a given lot.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. Its four N-terminal residues reproduce tuftsin, a tetrapeptide fragment of the immunoglobulin heavy chain, while the C-terminal Pro-Gly-Pro extension is a synthetic addition. The peptide has a molecular mass near 752 daltons and carries a net positive charge at physiological pH because of the arginine and lysine side chains. Published indexes list it under the name Selank and the sequence abbreviation TKPRPGP. Solid-phase peptide synthesis is the standard production route for research quantities.
Development took place at the Institute of Molecular Genetics of the Russian Academy of Sciences, where a series of short peptides were designed in the 1980s and 1990s. Selank was selected from variants of tuftsin that showed resistance to plasma peptidases. Russian regulatory approval covers it as an anxiolytic agent given intranasally. Outside that market the compound is normally handled as a research chemical rather than a medicine, and no widely recognised international pharmacopoeial monograph exists. The name Selank is a coined trade designation rather than a systematic chemical name.
The primary structure of Selank is Thr-Lys-Pro-Arg-Pro-Gly-Pro, corresponding to the molecular formula C33H57N11O9 and a monoisotopic mass of roughly 751.9 daltons. The N-terminal threonine and the arginine residue in the fourth position are shared with tuftsin, which carries the sequence Thr-Lys-Pro-Arg. The three additional residues at the C-terminus, Pro-Gly-Pro, extend the chain and are associated with greater resistance to enzymatic degradation. This extension also separates Selank from the shorter parent peptide.
Naming conventions place Selank in the same research family as Semax, another Russian-developed peptide investigated for cognitive effects. The two compounds share a lineage but differ in sequence and in the biological systems proposed as their targets. Semax descends from ACTH fragments, whereas Selank descends from tuftsin. Publications sometimes identify Selank by its full peptide sequence or by laboratory codes rather than one uniform trade name. Because replication outside Russia is limited, reports on its properties are best read alongside the study design and the purity of the material tested.
Selank is a synthetic heptapeptide developed in Russia during the 1990s. Researchers at the Institute of Molecular Genetics of the Russian Academy of Sciences designed it as a stabilized analog of tuftsin, a naturally occurring immunomodulatory tetrapeptide. The compound has been studied primarily for its reported anxiolytic and nootropic effects. It remains largely unknown in Western pharmacology and is not approved as a medicine by major regulators such as the FDA or the EMA.
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.
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.
Throughout late November and early December, the Cubans focused on fighting the FNLA in the north, and stopping an abortive incursion by Zaire on behalf of that movement. Thereafter, they refocused on putting an end to the SADF advances in the south. The South African and Cuban forces engaged in a series of bloody, but inconclusive skirmishes and battles throughout late December. However, by this point word of the SADF's involvement had been leaked to the international press, and photographs of SADF armour behind UNITA lines were appearing in several European newspapers. This proved to be a major political setback for the South African government, which was almost universally condemned for its interference in a black African country. Moreover, it spurred influential African states such as Nigeria and Tanzania to recognise the MPLA as the sole legitimate government of Angola, as that movement's struggle against an apparent act of South African aggression gave it legitimacy at the OAU. South Africa appealed to the United States for more direct support, but when the CIA's role in arming the FNLA also became public, the US Congress terminated and disavowed the programme. In the face of regional and international condemnation, the SADF made the decision around Christmas of 1975 to begin withdrawing from Angola. The withdrawal commenced in February 1976 and formally ended a month later. As the FNLA and UNITA lost their logistical backing from the CIA and the direct military support of the SADF, they were forced to abandon much of their territory to a renewed FAPLA offensive.
mistranslation The insertion of an incorrect amino acid in a growing peptide chain during translation, i.e. the inclusion of any amino acid that is not the one specified by a particular codon in an mRNA transcript. Mistranslation may originate from a mischarged transfer RNA or from a malfunctioning ribosome.
Per- and Polyfluoroalkyl Substances (PFAS) at the National Toxicology Program Per- and Polyfluoroalkyl Substances and Your Health at the Agency for Toxic Substances and Disease Registry Per- and Polyfluoroalkyl Substances (PFAS) at the EPA Per- and polyfluoroalkyl substances (PFASs) at the European Chemicals Agency PFAS contamination map of Europe Per- and Polyfluoroalkyl substances, National Institute for Occupational Safety and Health The Forever Pollution Project – Journalists tracking PFAS across Europe PFAS contamination in Queensland, Australia, State Library of Queensland "Contaminated: The Carpet Industry's Toxic Legacy". Frontline. Season 44. Episode 8. 3 February 2026. PBS. WGBH. Retrieved 25 February 2026.
=== 5 May === In Berdiansk, Yevgeniy Ananievsky, a Russian-appointed official allegedly responsible for setting up torture chambers in occupied Zaporizhzhia Oblast, was killed after a bomb exploded in his car. Two people were killed by Russian rockets in Pokrovsk. One person was killed by Russian shelling in Kharkiv Oblast. The Sloviansk Thermal Power Plant in Donetsk Oblast was also damaged by Russian shelling. Ukrainian former Olympic weightlifter turned soldier Oleksandr Pielieshenko was killed in action.
== Involvement in ProteomeXchange == The ProteomeXchange consortium has been set up to provide a coordinated submission of MS proteomics data to the main existing proteomics repositories, and to encourage optimal data dissemination. The consortium contains several member databases, including PRIDE and PeptideAtlas. The earliest conception of ProteomeXchange stems from a meeting at the HUPO 2005 conference in Munich, where the main proteomics data repositories at the time agreed in principle to exchange their data, and thus provide a means for the user to find public proteomics data at any of the participating databases. Due to the rapid development of the field, and the need to first develop suitable standards for data exchange, it took almost ten years from that meeting to actually implement this system, an effort that was funded by the 'ProteomeXchange' Coordination Action grant of the European Commission's Seventh Framework Programme.
Sources: en.wikipedia.org
=== Absorption === The oral bioavailability of CPA is 68 to 100%. The absorption of oral CPA is slow but complete, and the medication is not subject to a significant first-pass effect. The mean absorption half-life of oral CPA is about 1.5 hours. Steady-state levels of CPA occur with oral CPA after about 8 days of continuous administration, with a 2- to 3-fold gradual accumulation in CPA levels. Oral CPA is taken daily and intramuscular CPA is administered weekly or biweekly. Following a single low oral dose of 2 mg CPA in combination with 35 or 50 μg ethinylestradiol in premenopausal women, mean peak levels of CPA of 7.2 to 15.2 ng/mL (17–36.5 nmol/L) have been recorded after 1.6 to 3.7 hours. In healthy men, a single high oral dose of 100 mg CPA produced maximal CPA levels of 254 ng/mL (609 nmol/L) after 2.6 hours. In aged men with prostate cancer, continuous oral CPA therapy resulted in CPA levels of 132 ± 18 ng/mL at 25 mg/day, 246 ± 13 ng/mL at 50 mg/day, and 348 ± 23 ng/mL at 100 mg/day. Similarly, in healthy young women, a single high oral dose of 100 mg CPA resulted in peak CPA levels of 255 ng/mL (612 nmol/L) within 2 to 3 hours. During continuous treatment with high oral doses of CPA in women with hirsutism, levels of CPA were 199 to 228 ng/mL (477–547 nmol/L) with 50 mg/day CPA and were 436 to 520 ng/mL (1050–1250 nmol/L) with 100 mg/day CPA. After a single intramuscular injection of 300 mg CPA in healthy young women, maximal levels of CPA of 191 ng/mL (458 nmol/L) and of 15β-OH-CPA of 164 ng/mL occurred after 2 to 4 days.
== Biography == Robert Allan Humphreys was born on October 16, 1930, in Chickasha, Oklahoma, to Ira Denver Humphreys and Stella Bernice Humphreys. "Laud" was chosen as his first name when he was baptized again upon entering the Episcopal Church.
=== Cell culture === One of the key advantages of droplet-based microfluidics is the ability to use droplets as incubators for single cells. In addition, droplets can be applied for studies on embryogenesis of animals and plants. Devices capable of generating thousands of droplets per second open new ways to characterize cell populations, not only based on a specific marker measured at a specific time point but also based on cells' kinetic behavior such as protein secretion, enzyme activity or proliferation. Recently, a method was found to generate a stationary array of microscopic droplets for single-cell incubation that does not require the use of a surfactant.
=== Cardiac conditions === Subtypes of troponin (cardiac I and T) are sensitive and specific indicators of heart muscle damage (myocardium). They are measured in the blood to differentiate between unstable angina and myocardial infarction (heart attack) in people with chest pain or acute coronary syndrome. A person who recently had a myocardial infarction has areas of damaged heart muscle and elevated cardiac troponin levels in the blood. This can also occur in people with coronary vasospasm, a type of myocardial infarction involving severe constriction of the cardiac blood vessels. After a myocardial infarction troponins may remain high for up to 2 weeks. Cardiac troponins are a marker of all heart muscle damage, not just myocardial infarction, which is the most severe form of heart disorder. However, diagnostic criteria for raised troponin indicating myocardial infarction is currently set by the WHO at a threshold of 2 μg/L or higher. Critical levels of other cardiac biomarkers are also relevant, such as creatine kinase. Severe tachycardia (for example due to supraventricular tachycardia) in an individual with normal coronary arteries can also lead to increased troponins for example, it is presumed due to increased oxygen demand and inadequate supply to the heart muscle. Coronary artery stent placement can also cause immediate post-procedure elevated serum cardiac troponin levels. This can be problematic in a clinical setting as troponin values and guidance protocols become subject to more thoughtful interpretation.
Sources: en.wikipedia.org
Curettage ( or ), in medical procedures, is the use of a curette (French, meaning "scoop") to remove tissue by scraping or scooping. Curettages are also a method of abortion. It has been replaced by vacuum aspiration over the last decade. Curettage has been used to treat teeth affected by periodontitis.
=== Economics === The number of e-cigarettes sold increased every year from 2003 to 2014. As of 2014, there were at least 466 e-cigarette brands. Worldwide e-cigarette sales in 2014 were around US$7 billion. Worldwide e-cigarette sales in 2019 were about $19.3 billion. In 2021, the global e-cigarette market was estimated at about US$20.4 billion. In the United States, Reuters reported (citing Circana retail tracking reviewed by Reuters) that illegal sales of flavored disposable vapes reached about $2.4 billion in 2024 and accounted for roughly 35% of all e-cigarette sales in mainstream retail outlets tracked by Circana; Circana estimated the total tracked vape market at $6.8 billion, excluding online and specialty store sales. E-cigarette sales could exceed traditional cigarette sales by 2023.
The incidents began in Jaramana at approximately 2:00 a.m. on 28 April 2025, when an unidentified group opened fire on a local militia checkpoint near the "Al-Naseem" intersection at the entrance of Jaramana. Gunfire continued and intensified around 4:00 a.m., leading to the deaths of at least two members of the security forces and six residents of the city. Over ten others were injured in the initial wave of violence. Local factions imposed heightened security measures, erecting checkpoints and restricting movement into and out of the city. On 29 April 2025, clashes expanded to the Druze-majority towns of Sahnaya and Ashrafiyat Sahnaya. Armed groups attacked multiple security checkpoints using machine guns and RPGs. The fighting briefly paused, but continued after reinforcements arrived from Daraa. Hussam Waruar, the head of the Sahnaya Municipality, was killed along with his son on 1 May by unidentified gunmen. The unidentified groups killed the Druze leader, Wajdi al-Hajj Ali, who was shot in the head and died on 30 April 2025 before reaching the hospital.
Sources: en.wikipedia.org
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.
Behavioral endpoints include time spent in open arms of the elevated plus maze and avoidance latencies. Biochemical endpoints include BDNF concentration, cytokine levels, and monoamine metabolite ratios in brain tissue.
Most published studies are small, originate from a limited number of laboratories, and lack independent replication. Dose-response relationships, measured brain exposure, and long-term outcomes are not well characterized.
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.