If you have been reading about mass spectrometry and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Last reviewed on 2026-05-08. Where a claim depends on a specific study, the study is described rather than over-claimed.
Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro. It is described in the literature as an analogue of the ACTH(4–10) fragment, a short N-terminal portion of adrenocorticotropic hormone that retains some neurotropic activity without the full hormonal effects of the parent peptide. The molecule carries a methionine residue at the N-terminus and two proline residues near the C-terminus, features that shape both its interactions with receptor systems and its chemical stability. The free peptide corresponds to the formula C37H51N9O10S and a molecular mass near 813.9 Da.
The compound was developed in the 1980s at the Institute of Molecular Genetics in Moscow, where it emerged from research on short ACTH fragments and their effects on the central nervous system. Russian pharmaceutical listings describe it as a nootropic and neuroprotective agent, most often formulated as nasal drops. It is not a marketed medicine in the United States or the European Union, and no pharmacopoeial monograph covers it. Consequently, most published clinical experience with the substance originates from a small number of research centres, mainly in Russia and neighbouring countries.
Lyophilised powder is normally kept at -20 °C in a desiccated container, with some suppliers recommending -80 °C for long-term archival storage. Repeated freeze-thaw cycles are the most common cause of avoidable loss, so aliquoting before freezing reduces variability between working sessions. Dissolved peptide is far less stable than the dry solid and is usually prepared fresh or held briefly at 4 °C. Aqueous solutions support both hydrolysis of the backbone and oxidation of the N-terminal methionine, and these two routes dominate degradation under ordinary laboratory conditions.
Identity and purity are confirmed with reversed-phase high-performance liquid chromatography, typically monitored at 214 nanometres where the peptide bond absorbs. Mass spectrometry, either electrospray or MALDI-TOF, verifies molecular mass against the theoretical value and detects truncation or adduct formation. Amino acid analysis and peptide mapping provide additional confirmation when required. The most frequently reported impurities are deletion sequences from incomplete coupling, methionine sulfoxide from oxidation, and dimeric species formed through non-covalent aggregation. Impurity profiles depend strongly on the synthesis and purification route chosen by the producer.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C37H51N9O10S | Free acid form of the heptapeptide; depends on terminal groups |
| Molecular mass | About 813.9 g/mol | Average mass used for mass spectrometry confirmation |
| Appearance | White to off-white solid | Supplied as a lyophilised powder; hygroscopic |
| Solubility class | Freely soluble in aqueous media | Water, saline, and phosphate buffers; limited organic solubility |
| Typical storage temperature | -20 degrees Celsius | Long term and dry; short working periods may use 2 to 8 degrees Celsius |
Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro. Its design combines the ACTH(4-7) core fragment with a C-terminal Pro-Gly-Pro extension, a modification intended to improve stability and prolong activity. The molecule is hydrophilic, carries no lipid chains or glycosylation, and has a theoretical mass just over 810 daltons in its free form. All seven residues are proteinogenic amino acids, so no non-natural building blocks appear in the backbone. A free N-terminal methionine and C-terminal proline define the unmodified parent peptide.
The compound was developed during the 1980s at the Institute of Molecular Genetics in Moscow as part of research on fragments of adrenocorticotropic hormone. Early work examined short ACTH-derived sequences that retained neurotrophic effects while lacking the endocrine activity of the full hormone. Semax entered clinical use in Russia during the 1990s, where it received registration for several neurological indications. Outside that region it remained primarily a laboratory research material rather than an approved therapeutic. English-language literature on it grew more slowly and frequently cited the original Russian studies.
Semax is normally supplied as a lyophilized powder, and that form is the most stable. Suppliers commonly recommend storage at -20 °C in a desiccated container protected from light, with short-term handling at room temperature limited to weighing and transfer. Powder that has absorbed moisture degrades faster, so vials should be warmed to ambient temperature before opening to prevent condensation on the contents. Hygroscopic behavior is typical of short hydrophilic peptides, and humidity control matters more than temperature alone for long-term retention.
Once dissolved, the peptide is considerably less stable than the solid. Aqueous solutions are usually prepared at neutral to slightly acidic pH, filtered, and divided into single-use aliquots before freezing. Repeated freeze-thaw cycles are a common cause of avoidable loss and are best prevented by never refreezing a thawed aliquot. Adsorption to plastic and glass surfaces can lower the measured concentration of dilute solutions, particularly below roughly 0.1 mg/mL. Buffer choice, salt content, and container material all influence how much peptide remains detectable after storage.
== Medical uses == Oxazepam is an intermediate-acting benzodiazepine with a slow onset of action, so it is usually prescribed to individuals who have trouble staying asleep, rather than falling asleep. It is commonly prescribed for anxiety disorders with associated tension, irritability, and agitation. It is also prescribed for drug and alcohol withdrawal, and for anxiety associated with depression. Oxazepam is sometimes prescribed off-label to treat social phobia, post-traumatic stress disorder, insomnia, premenstrual syndrome, and other conditions.
=== Zostavax === Zostavax contains live attenuated varicella-zoster virus. It is injected subcutaneously (under the skin) in the upper arm. The live vaccine is produced using the MRC-5 line of fetal cells. This has raised religious and ethical concerns for some potential users, since that cell line was derived from an aborted fetus.
Two issues with self-medication are the lack of knowledge of the public on the dangerous effects of certain antimicrobials (for example ciprofloxacin which can cause tendonitis, tendon rupture and aortic dissection) and broad microbial resistance and when to seek medical care if the infection is not clearing. To determine the public's knowledge and preconceived notions on antibiotic resistance, a screening of 3,537 articles published in Europe, Asia, and North America was done. Of the 55,225 total people surveyed in the articles, 70% had heard of antibiotic resistance previously, but 88% of those people thought it referred to some type of physical change in the human body.
Sources: en.wikipedia.org
The Cameron Prize for Therapeutics of the University of Edinburgh is awarded by the College of Medicine and Veterinary Medicine to a person who has made any highly important and valuable addition to practical therapeutics in the previous five years. The prize, which may be awarded biennially, was founded in 1878 by Andrew Robertson Cameron of Richmond, New South Wales, with a sum of £2,000. The University's senatus academicus may require the prizewinner to deliver one or more lectures or to publish an account on the addition made to practical therapeutics. A list of recipients of the prize dates back to 1879.
The most common ionization method coupled to LC is some form of spray ionization, which includes thermospray ionization and more commonly, electrospray (ESI) ionization. Thermospray was first developed as a way to effectively remove solvent and vaporize samples more easily. This method involves the liquid sample from the LC flowing through an electrically heated vaporizer that simply heats the sample, removing any solvent and therefore putting the sample in the gas phase. Electrospray ionization (ESI) is similar to thermospray in the principle of removing the liquid solvent from the sample as much as possible, creating charged sample molecules either in small droplets or in gas form. Studies have shown that ESI can be as much as ten times more sensitive than other ionization methods coupled to LC. The spray methods are particularly useful considering that non-volatile samples can be analyzed easily through this method since the sample is not itself turned into a gas, the liquid is simply removed, pushing the sample into a gaseous or mist phase. One sample preparation issue with liquid chromatography-mass spectrometry is possible matrix effects due to the presence of background molecules. These matrix effects have been shown to decrease the signal in methods such as PI and ESI by amounts as much as 60% depending on the sample being analyzed. The matrix effect can also cause an increase in signal, producing false positive results.
the person responsible under § 115 StrlSchG (in German) paragraph 2 or § 153 StrlSchG (in German) paragraph 1. The SSR numbers must then be available for further use as part of normal communication with monitoring stations or radiation pass authorities. The SSR number is derived from the social security number and personal data using non-traceable encryption. The transmission takes place online. Approximately 420,00 persons are monitored for radiation protection in Germany (as of 2019). Emergency responders (including volunteers) who are not occupationally exposed persons within the meaning of the Radiation Protection Act also require an SSR number retrospectively, i.e. after an operation in which they were exposed to radiation above the limits specified in the Radiation Protection Ordinance, as all relevant exposures must be recorded in the Radiation Protection Register.
Sources: en.wikipedia.org
=== Catabolism === The biological breakdown (catabolism) of VWF is largely mediated by the enzyme ADAMTS13 (acronym of "a disintegrin-like and metalloprotease with thrombospondin type 1 motif no. 13"). It is a metalloproteinase that cleaves VWF between tyrosine at position 842 and methionine at position 843 (or 1605–1606 of the gene) in the A2 domain. This breaks down the multimers into smaller units, which are degraded by other peptidases. The half-life of vWF in human plasma is around 16 hours; glycosylation variation on vWF molecules from different individuals result in a larger range of 4.2 to 26 hours. Liver cells as well as macrophages take up vWF for clearance via ASGPRs, Macrophage Galactose Lectin, and LRP1. SIGLEC5 and CLEC4M also recognize vWF.
The vast majority of L-leucine metabolism is initially catalyzed by the branched-chain amino acid aminotransferase enzyme, producing α-ketoisocaproate (α-KIC). α-KIC is mostly metabolized by the mitochondrial enzyme branched-chain α-ketoacid dehydrogenase, which converts it to isovaleryl-CoA. Isovaleryl-CoA is subsequently metabolized by isovaleryl-CoA dehydrogenase and converted to MC-CoA, which is used in the synthesis of acetyl-CoA and other compounds. During biotin deficiency, HMB can be synthesized from MC-CoA via enoyl-CoA hydratase and an unknown thioesterase enzyme, which convert MC-CoA into HMB-CoA and HMB-CoA into HMB respectively. A relatively small amount of α-KIC is metabolized in the liver by the cytosolic enzyme 4-hydroxyphenylpyruvate dioxygenase (KIC dioxygenase), which converts α-KIC to HMB. In healthy individuals, this minor pathway – which involves the conversion of L-leucine to α-KIC and then HMB – is the predominant route of HMB synthesis.
Deka Bike Robo (デカバイクロボ, Deka Baiku Robo): The Deka Bike's Tokusou Transformation and Deka Break's personal giant robot that is equipped with the twin wrist-mounted Sleeve Swords (スリーブソード, Surību Sōdo), which allow it to perform the Sword Tornado (ソードトルネード, Sōdo Torunēdo) finisher. Deka Wing Robo (デカウィングロボ, Deka Wingu Robo): The Dekarangers' second giant robot composed of the Pat Wings that dual wields the twin Pat Magnum (パトマグナム, Pato Magunamu) handguns, specializes in aerial and zero-g combat, and can perform the Double Heel Smash (ダブルヒールスマッシュ, Daburu Hīru Sumasshu) attack. It can also transform further into the Deka Wing Cannon (デカウィングキャノン, Deka Wingu Kyanon) to perform the Final Buster (ファイナルバスター, Fainaru Basutā) finisher on its own; the All Star Ultimate Buster (オールスター・アルティメットバスター, Ōru Sutā Arutimetto Basutā) finisher with Dekaranger Robo, Deka Bike Robo, and Deka Base Robo; and the Twin Robo Ultimate Buster (ツインロボ・アルティメットバスター, Tsuin Robo Arutimetto Basutā) with Deka Bike Robo. In the crossover film Mahō Sentai Magiranger vs. Dekaranger, the Deka Wing Cannon performs the Magi Final Buster (マジファイナルバスター, Maji Fainaru Basutā) finisher alongside the Magirangers' giant robot Magi Legend.
Sources: en.wikipedia.org
It is described as a synthetic analogue of the ACTH(4–10) fragment, a short segment of adrenocorticotropic hormone. Its sequence differs from that fragment and includes two proline residues, which influence stability and behaviour in solution.
It appears in Russian pharmaceutical listings as a nasal formulation, but it is not an authorised medicine in the United States or the European Union. Outside those markets it is normally encountered as a research chemical rather than a prescription product.
Laboratory and animal work points to melanocortin signalling and changes in neurotrophic factor levels, especially brain-derived neurotrophic factor. The exact receptor targets and the degree to which these findings transfer to humans are still unresolved.
Reversed-phase HPLC gives the main purity figure, most often with UV detection near 214 nanometres. Mass spectrometry then confirms the molecular mass. Together the two methods distinguish a correct sequence from a closely related impurity.