This is a working overview of mass spectrometry, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2025-12-16 and is reviewed periodically as new material appears.
Published clinical evidence is limited. Most controlled trials were conducted in Russia, enrolled modest numbers of participants, and appeared in Russian-language journals, which restricts independent verification. Reported outcomes include lower anxiety scores, improved attention and memory measures, and changes in fatigue ratings. Reviews written in English note methodological limitations such as small samples and inconsistent endpoints. Whether the compound produces clinically meaningful benefit relative to established anxiolytics is therefore an open question rather than an established finding.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. It was designed at the Institute of Molecular Genetics of the Russian Academy of Sciences as a structural analogue of tuftsin, a naturally occurring tetrapeptide fragment of the immunoglobulin heavy chain. The added Pro-Gly-Pro tail was intended to slow enzymatic degradation and extend biological activity. In Russia it is registered as an anxiolytic nasal preparation, while regulators elsewhere have not approved it for clinical use.
Proposed mechanisms centre on modulation of the GABAergic system, with reports of altered expression of genes related to GABA-A receptor subunits and changed monoamine turnover. Some studies describe inhibition of enkephalinase, the enzyme that degrades endogenous enkephalins, which may prolong opioid peptide signalling. Effects on brain-derived neurotrophic factor and on cytokine expression have also been reported. These findings come largely from animal models and small human studies, and the precise primary target remains unresolved.
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.
Proposed mechanisms center on modulation of the GABA system, but no single molecular target has been confirmed. Rodent studies report changes in GABA-A receptor expression and in the turnover of serotonin, dopamine, and norepinephrine in several brain regions. Increases in brain-derived neurotrophic factor and its receptor have also been described after repeated administration. These findings come largely from animal models, and the degree to which they describe human neurochemistry remains an open question. The mechanism is best characterized as multi-system and not fully resolved.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C33H57N11O9 | Free peptide form |
| Molecular mass | About 751.9 Da | Calculated average mass |
| Amino acid sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Single-letter form TKPRPGP |
| Structural basis | Tuftsin analogue | Extended version of a natural tetrapeptide |
| Development origin | Russian Academy of Sciences | Work carried out from the 1980s onward |
Reversed-phase high-performance liquid chromatography is the standard technique for estimating peptide purity. The result is a peak-area percentage, which describes how much of the detected material elutes as the main peak in one run. Mass spectrometry confirms the molecular mass and can reveal truncated, adducted, or otherwise modified species. Amino acid analysis or tandem mass spectrometry can address sequence fidelity when identity is in doubt. None of these measurements, taken alone, establishes that a sample is fit for any specific purpose.
Lyophilized selank is normally supplied as a dry powder and is considered stable for extended periods when kept cold and dry. Moisture uptake is the main practical threat, because absorbed water promotes both hydrolysis and aggregation in the solid state. Vials are usually warmed to room temperature before opening so that condensation does not form on the powder. Supplier documentation commonly specifies -20 °C for routine storage, with -80 °C used for material intended to be archived for years.
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.
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.
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.
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.
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.
== External links == "Connective Tissue Disorders". National Library of Medicine. 2017-09-15. Dunkin, Mary Anne (2023-10-10). "Connective Tissue Disease: Types, Symptoms, Causes". WebMD. "Connective tissue diseases". DermNet®. 2023-10-26.
=== Pharmacokinetics === Opipramol is rapidly and completely absorbed by the gastrointestinal tract. The bioavailability of opipramol amounts to 94%. After single oral administration of 50 mg, the peak plasma concentration of the drug is reached after 3.3 hours and amounts to 15.6 ng/mL. After single oral administration of 100 mg the maximum plasma concentration is reached after 3 hours and amounts to 33.2 ng/mL. Therapeutic concentrations of opipramol range from 140 to 550 nmol/L. The plasma protein binding amounts to approximately 91% and the volume of distribution is approximately 10 L/kg. Opipramol is partially metabolized in the liver to deshydroxyethylopipramol. Metabolism occurs through the CYP2D6 isoenzyme. Its terminal half-life in plasma is 6–11 hours. About 70% is eliminated in urine with 10% unaltered. The remaining portion is eliminated through feces.
In this study, the UK school children had a low baseline cellular immunity to mycobacteria which was increased by BCG; in contrast, the Malawi school children had a high baseline cellular immunity to mycobacteria and this was not significantly increased by BCG. Whether this natural immune response is protective is not known. An alternative explanation is suggested by mouse studies; immunity against mycobacteria stops BCG from replicating and so stops it from producing an immune response. This is called the block hypothesis. Interference by concurrent parasitic infection In another hypothesis, simultaneous infection with parasites such as helminthiasis changes the immune response to BCG, making it less effective. As Th1 response is required for an effective immune response to tuberculous infection, but concurrent infection with various parasites produces a simultaneous Th2 response, which blunts the effect of BCG.
The Society for Low Temperature Biology was founded in 1964 and became a registered charity in 2003 with the purpose of promoting research into the effects of low temperatures on all types of organisms and their constituent cells, tissues, and organs. As of 2006, the society had around 130 (mostly British and European) members and holds at least one annual general meeting. The program usually includes both a symposium on a topical subject and a session of free communications on any aspect of low-temperature biology. Recent symposia have included long-term stability, preservation of aquatic organisms, cryopreservation of embryos and gametes, preservation of plants, low-temperature microscopy, vitrification (glass formation of aqueous systems during cooling), freeze drying and tissue banking. Members are informed through the Society Newsletter, which is presently published three times a year.
Sources: en.wikipedia.org
=== Books === Boitano, Scott; Brooks, Heddwen L.; Barman, Susan M.; Barrett, Kim E. (2016). Ganong's Review of Medical Physiology. McGraw-Hill Education. ISBN 978-0-07-182510-8. Susan Standring, ed. (2008). Gray's anatomy: the anatomical basis of clinical practice (40th ed.). London: Churchill Livingstone. ISBN 978-0-8089-2371-8. Cole, Laurence A.; Kramer, Peter R. (2016). Human Physiology, Biochemistry and Basic Medicine. Amsterdam: Academic Press. ISBN 978-0-12-803699-0.
=== In organic synthesis === Chloral hydrate is a starting point for the synthesis of other organic compounds. It is the starting material for the production of chloral, which is produced by the distillation of a mixture of chloral hydrate and sulfuric acid, which serves as the desiccant. Notably, it is used to synthesize isatin. In this synthesis, chloral hydrate reacts with aniline and hydroxylamine to give a condensation product which cyclicizes in sulfuric acid to give the target compound:
== Naturally occurring nuclides that are not primordial == Some unstable isotopes which occur naturally (such as 14C, 3H, and 239Pu) are not primordial, as they must be constantly regenerated. This occurs by cosmic radiation (in the case of cosmogenic nuclides such as 14C and 3H), or (rarely) by such processes as geonuclear transmutation (neutron capture by uranium in the case of 237Np and 239Pu). Other examples of common naturally occurring but non-primordial nuclides are isotopes of radon, polonium, and radium, which are all radiogenic daughters of uranium decay and are found in uranium ores. The stable argon isotope 40Ar is actually more common as a radiogenic nuclide than as a primordial nuclide, forming almost 1% of the Earth's atmosphere, which is generated by the electron capture decay of the extremely long-lived radioactive primordial isotope 40K, whose half-life is on the order of a billion years and thus has been generating argon since early in the Earth's existence. (Primordial argon was dominated by the alpha process nuclide 36Ar, which is significantly rarer than 40Ar on Earth.) And the classical decay chains of radiogenic elements derive from the long-lived radioactive primordial nuclides 232Th, 235U, and 238U. These nuclides are described as geogenic, meaning that they are decay or fission products of uranium or other actinides in subsurface rocks. All such nuclides have shorter half-lives than their parent radioactive primordial nuclides.
== Medical uses == The compound is indicated for adults with type 2 diabetes as an adjunct to diet and exercise to improve glycemic control. Dulaglutide is not indicated in the treatment of subjects with type 1 diabetes or patients with diabetic ketoacidosis because these problems are the result of the islet cells being unable to produce insulin and one of the actions of dulaglutide is to stimulate functioning islet cells to produce more insulin. Dulaglutide can be used either stand-alone or in combination with other medicines for type 2 diabetes, in particular metformin, sulfonylureas, thiazolidinediones, and insulin taken concomitantly with meals. The medication's phase 3 clinical trial program demonstrated reductions in hemoglobin A1c of approximately 1% with the 0.75 mg and 1.5 mg doses of the medication, along with approximately 5 pounds of weight loss on average. The higher 3.0 mg and 4.5 mg doses that were approved in 2020 demonstrated hemoglobin A1c reductions closer to 1.5% and slightly more weight loss. An alternate study conducted by REWIND had enrolled a lower-risk population consisting of 9901 patients, two-thirds had no prior cardiovascular events. These patients were randomized to dulaglutide 1.5mg weekly versus a placebo group for a median of 5.4 years. As a result of this study, Dulaglutide had reduced MACE by 12% (HR 0.88, 95% Cl 0.79-0.99) and had produced a 15% relative risk reduction in the composite renal outcome.
==== Post reform organisations ==== The 1st Hydropower Corps was converted into the China Anneng Construction Group's 1st Engineering Bureau (Headquartered in Nanning) on 19 November 2019. The 2nd Hydropower Corps was converted into the China Anneng Construction Group's 2nd Engineering Bureau (Headquartered in Nanchang) on 14 November 2019. The 3rd Hydropower Corps was converted into the China Anneng Construction Group's 3rd Engineering Bureau (Headquartered in Chengdu) on 12 November 2019. It has branches in Wuhan and Chongqing.
Sources: en.wikipedia.org
Historically, some researchers reported BAC as mass of alcohol per mass of blood (g/kg or mg/g). Because blood is slightly denser than water (about 1.05 g/mL), 1 g/L is approximately equal to 0.95 mg/g. Some countries define legal limits using mass–mass units, though public information often treats 1 liter of blood as equivalent to 1 kilogram. In pharmacokinetics, concentrations may be expressed in moles. As the molar mass of ethanol is 46.07 g/mol, a concentration of 1 g/L is equivalent to about 21.7 mmol/L (21.7 mM).
=== Disulfide bond cleavage === ECD itself and combined with other MS is very useful for proteins and peptides containing multiple disulfide bonds. FTICR combined with ECD helps to recognize peptides containing disulfide bonds. ECD could also access important sequence information by activation of higher charged proteins. Moreover, disulfide bond cleavage takes place by ECD of multiply charge proteins or peptides produced by ESI. Electron capture by these proteins releases H atom, captured by the disulfide bond to cause its dissociation.
The four substrates of this enzyme are 3-hydroxyphenylacetic acid, reduced nicotinamide adenine dinucleotide (NADH), oxygen, and a proton. Its products are homogentisic acid, oxidised NAD+, and water. Nicotinamide adenine dinucleotide phosphate can be used as an alternative cofactor. This enzyme is a flavin-containing monooxygenase that uses molecular oxygen as oxidant and incorporates one of its atoms into the starting material. The systematic name of this enzyme class is 3-hydroxyphenylacetate,NAD(P)H:oxygen oxidoreductase (6-hydroxylating). This enzyme is also called 3-hydroxyphenylacetate 6-monooxygenase. It participates in styrene degradation.
== Protein production systems == Commonly used protein production systems include those derived from bacteria, yeast, baculovirus/insect, mammalian cells, and more recently filamentous fungi such as Myceliophthora thermophila. When biopharmaceuticals are produced with one of these systems, process-related impurities termed host cell proteins also arrive in the final product in trace amounts.
== Analysis == The groups of bioactive compounds present in E. planum are phenolic acids, triterpenoid saponins, flavonoids, coumarins, and essential oils. The wide range of compounds is reflected in the wide range of uses. Qualitative and quantitative determinations of the phenolic acids by reverse phase high-performance liquid chromatography (RP HPLC) show relatively small amounts of rosmarinic, chlorogenic, and caffeic acids in the basal leaves and the roots of intact plants, and greater concentrations in E. planum from in vitro cultures. Qualitative and quantitative analyses of the essential oil compounds performed by gas chromatography with a flame ionization detector linked to a mass spectrometer (GC-FID-MS) show the main components of stalk leaf oil, and rosette leaf oil, as monoterpenes (limonene, and α- and β-pinene), sesquiterpenes, and hydrocarbons. (Z)-Falcarinol was found as the major component of root essential oil.
Sources: en.wikipedia.org
It is a seven-amino-acid peptide, Thr-Lys-Pro-Arg-Pro-Gly-Pro, produced by chemical synthesis rather than extracted from biological tissue. Its design is based on tuftsin, a natural immunomodulatory tetrapeptide. The C-terminal Pro-Gly-Pro segment is a common stabilising motif in short regulatory peptides.
The core four residues correspond to tuftsin, which occurs naturally as part of immunoglobulin G. The full seven-residue sequence, however, is not a known endogenous peptide. It is a laboratory-designed analogue intended to combine tuftsin-like activity with greater resistance to breakdown.
No single receptor has been confirmed as the primary target. Reports describe involvement of the GABAergic system, interference with enkephalin degradation, and shifts in neurotrophic factor expression. Because these observations come from different models and assays, they have not yet been integrated into one accepted mechanism.
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.