The short version of RP-HPLC fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2026-01-26. Anything still debated is marked as such rather than presented as settled.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Typical purity report | 95% or higher by HPLC | Area percentage at 214 nm |
| Identity confirmation | Mass spectrometry | Electrospray or MALDI |
| Powder storage | -20 C, desiccated | Protect from light |
| Solution storage | 2-8 C short term | Freeze aliquots for longer |
| Quality document | Certificate of analysis | States method and value |
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.
Once dissolved, the peptide is markedly less stable than the dry powder. Aqueous solutions are subject to backbone hydrolysis and to microbial growth when they are handled without sterile technique. Buffered solutions near neutral pH are common for short-term laboratory work, while acidic conditions are sometimes used to improve solubility. Analytical laboratories generally prepare working solutions fresh rather than storing them, and a residual water film left in a reopened vial can seed degradation even when the container appears dry.
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.
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.
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.
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.
Characterization of Selank in laboratory settings relies on standard peptide analytical techniques. Reverse-phase high-performance liquid chromatography separates the peptide from related impurities and degradation products, while mass spectrometry confirms molecular identity through accurate mass measurement. Amino acid analysis and peptide sequencing verify the primary structure when reference material is unavailable. Because Selank is a short chain, fragmentation-based analysis produces a diagnostic ion pattern that supports confident identification.
Peptide stability depends strongly on temperature, moisture, and pH. Lyophilized Selank is generally most stable when stored cold and dry, with freezer temperatures commonly used for long-term storage. In solution, the compound is susceptible to hydrolysis and to microbial growth if it is not handled aseptically. The C-terminal proline-rich extension appears to slow enzymatic cleavage relative to tuftsin, though quantitative degradation rates vary with the matrix and the conditions tested. Published stability data specific to Selank remain sparse.
Lewis Namier (27 June 1888 – 19 August 1960), British historian of Polish-Jewish ancestry; descendant of Rabbi Elijah ben Solomon Zalman,(Hebrew: ר' אליהו בן שלמה זלמן) known as the Vilna Gaon; author of over twenty scholarly texts and authoritative monographs on sociopolitical typology and geopolitical analysis; held positions with Propaganda Department (1915–17), the Department of Information (1917–18) and with Political Intelligence Department of Foreign Office (1918–20); following defeat of Germany in World War One, Namier joined British delegation at Versailles Peace Conference of 1919; later Namier, who was a long-time Zionist, worked as political secretary for the Jewish Agency in Palestine (1929–31) and was close friend and associate of Chaim Weizmann; active in Zionist groups, lobbying British government to allow creation of Jewish Fighting Force in Mandate of Palestine and from 1933 was engaged in efforts on behalf of Jewish refugees from Germany. Namier used prosopography or collective biography of every Member of Parliament (MP) and peer who sat in the British Parliament in the latter 18th century to reveal that local interests, not national ones, often determined how parliamentarians voted. As former patient of Sigmund Freud, Namier was a believer in psychohistory. Saul Newman, anarchist scholar and activist,(born 22 March 1972) is a British political theorist who writes on post-anarchism. He is professor of political theory at Goldsmiths College, University of London.
Platelet-rich plasma (PRP), also known as autologous conditioned plasma, is a concentrate of plasma protein derived from whole blood, centrifuged to remove red blood cells but retaining platelets. Though promoted for treating various medical conditions, evidence of its benefits was mixed as of 2020, showing effectiveness in certain conditions and ineffectiveness in others. As a concentrated source of blood plasma and autologous conditioned plasma, PRP contains multiple growth factors and other cytokines that can stimulate the healing of soft tissues and joints. Indications for its use include sports medicine and orthopaedics (such as acute muscle strains, tendinopathy, tendinosis, muscle-fascial injuries, and osteoarthritis) dermatology (for androgenic alopecia, wound healing, and skin rejuvenation), and even proctology (for fistula en ano). Various preparation protocols exist, with the underlying principle of concentrating platelets to 3–5 times physiological levels, then injecting this concentrate into the tissue where healing is desired. Beyond clinical practice, PRP has been utilized in various tissue engineering applications involving bone, cartilage, skin, and soft tissue repair. It serves as a source for the delivery of growth factors and/or cells within tissue-engineered constructs, often in combination with biomaterials.
Leybold – Fundamentals of Vacuum Technology (PDF) VIDEO on the nature of vacuum by Canadian astrophysicist Doctor P The Foundations of Vacuum Coating Technology American Vacuum Society Journal of Vacuum Science and Technology A Journal of Vacuum Science and Technology B FAQ on explosive decompression and vacuum exposure. Discussion of the effects on humans of exposure to hard vacuum. Roberts, Mark D. (2000). "Vacuum Energy". High Energy Physics – Theory: hep–th/0012062. arXiv:hep-th/0012062. Bibcode:2000hep.th...12062R. Vacuum, Production of Space "Much Ado About Nothing" by Professor John D. Barrow, Gresham College Free pdf copy of The Structured Vacuum – thinking about nothing by Johann Rafelski and Berndt Muller (1985) ISBN 3-87144-889-3.
==== Bas-relief ==== In 1978 Joe Nickell noted that the Shroud image had a three-dimensional quality and thought its creation may have involved a sculpture of some type. He advanced the hypothesis that a medieval rubbing technique was used to produce the image, and set out to demonstrate this. He noted that while wrapping a cloth around a sculpture with normal contours would result in a distorted image, Nickell believed that wrapping a cloth over a bas-relief might result in an image like the one seen on the shroud, as it would eliminate wraparound distortions. For his demonstration, Nickell wrapped a wet cloth around a bas-relief sculpture and allowed it to dry. He then applied powdered pigment rather than wet paint (to prevent it soaking into the threads). The pigment was applied with a dauber, similar to making a rubbing from a gravestone. The result was an image with dark regions and light regions convincingly arranged. In a photo essay in Popular Photography magazine, Nickell demonstrated this technique step-by-step. Other researchers later replicated this process. In 2005 the researcher Jacques di Costanzo constructed a bas-relief of a Jesus-like face and draped wet linen over it. After the linen dried, he dabbed it with a mixture of ferric oxide and gelatine. The result was an image similar to that of the face on the Shroud.
== Pathophysiology == Hemoglobin H disease is a genetic disorder resulting in absent or impaired production of the α-globin protein, a normal component of the hemoglobin. The disease occurs when the α-globin gene expression is reduced to less than 30% of the normal expression. In a healthy individual there are four copies of the gene which encode the α-globin protein. α-globin is encoded by the HBA1 (2 copies) and HBA2 (2 copies) genes. The genotype of healthy individuals with four normal copies of α-globin is annotated as αα/αα. In individuals with deletional HbH disease, there is deletion of three of the four α-globin alleles, which is annotated as --/-α. Non-deletional HbH disease refers to a decreased α-globin that has not occurred as a result of the complete deletion of the DNA sequences encoding HBA1 and HBA2, and this is more rare than the deletional type. The most common hemoglobin found within adult red blood cells is hemoglobin A. The structure of HbA consists of two α-globin chains bound to two β-globin chains to form a tetramer (a protein made up four protein chains). When there is lower than normal production of α-globin, as in HbH disease, the excess β-globin form β4-tetramers, termed hemoglobin H. These β4-tetramers accumulate in red blood cells and precipitate to form HbH inclusion bodies. The inclusion bodies in the mature red blood cells are removed by the spleen and this results in an early destruction of these red blood cells. This destruction of red blood cells by the spleen is termed extravascular hemolysis.
Sources: en.wikipedia.org
=== Data mining approach === Computer SAR models typically calculate a relatively large number of features. Because those lack structural interpretation ability, the preprocessing steps face a feature selection problem (i.e., which structural features should be interpreted to determine the structure-activity relationship). Feature selection can be accomplished by visual inspection (qualitative selection by a human); by data mining; or by molecule mining. A typical data mining based prediction uses e.g. support vector machines, decision trees, artificial neural networks for inducing a predictive learning model. Molecule mining approaches, a special case of structured data mining approaches, apply a similarity matrix based prediction or an automatic fragmentation scheme into molecular substructures. Furthermore, there exist also approaches using maximum common subgraph searches or graph kernels.
=== 5 January === Ten people were killed in an SAF airstrike in Khartoum. The SAF and the JDF claimed to have deflected an RSF assault on El Fasher that came from the east and southeast of the city. The JDF also intercepted a weapons convoy for the RSF, arresting both Sudanese and Libyan nationals.
The expression of HA is known to down-regulate the recruitment of inflammatory cytokines interleukin-1 (IL-1) and tumour necrosis factor-alpha (TNF-α); since fetal wounds contain a reduced number of pro-inflammatory mediators than adult wounds it is thought that the higher levels of HA in the fetal skin aid in scar free healing. Analysis using microarrays has also shown that gene expression profiles greatly differ between scar free fetal wounds and postnatal wounds with scar formation. In scarlesss wound healing there is a significant up-regulation in genes associated with cell growth and proliferation, thought to be a major contributing factor to the rapid wound closure seen in the foetus. Whilst wound healing in the fetus has been shown to be completely scarless in an age-dependent manner, adult mammals do not have complete scar free healing but have retained some regenerative properties. Adult regeneration is limited to a number of organs, most notably, the liver.
== Further reading == Ezzati M, Carr BR (January 2015). "Elagolix, a novel, orally bioavailable GnRH antagonist under investigation for the treatment of endometriosis-related pain". Women's Health. 11 (1): 19–28. doi:10.2217/whe.14.68. PMID 25581052. Melis GB, Neri M, Corda V, Malune ME, Piras B, Pirarba S, Guerriero S, Orrù M, D'Alterio MN, Angioni S, Paoletti AM (May 2016). "Overview of elagolix for the treatment of endometriosis". Expert Opin Drug Metab Toxicol. 12 (5): 581–8. doi:10.1517/17425255.2016.1171316. PMID 27021205. S2CID 28684228. Alessandro P, Luigi N, Felice S, Maria PA, Benedetto MG, Stefano A (April 2017). "Research development of a new GnRH antagonist (Elagolix) for the treatment of endometriosis: a review of the literature". Arch. Gynecol. Obstet. 295 (4): 827–832. doi:10.1007/s00404-017-4328-6. PMID 28255765. S2CID 26422467. Perricos A, Wenzl R (September 2017). "Efficacy of elagolix in the treatment of endometriosis". Expert Opin Pharmacother. 18 (13): 1391–1397. doi:10.1080/14656566.2017.1359258. PMID 28737050. S2CID 32467159. Surrey E, Taylor HS, Giudice L, Lessey BA, Abrao MS, Archer DF, Diamond MP, Johnson NP, Watts NB, Gallagher JC, Simon JA, Carr BR, Dmowski WP, Leyland N, Singh SS, Rechberger T, Agarwal SK, Duan WR, Schwefel B, Thomas JW, Peloso PM, Ng J, Soliman AM, Chwalisz K (July 2018). "Long-Term Outcomes of Elagolix in Women With Endometriosis: Results From Two Extension Studies". Obstet Gynecol. 132 (1): 147–160. doi:10.1097/AOG.0000000000002675. PMID 29889764. Taylor HS (July 2018). "Use of Elagolix in Gynaecology".
6 July – One child dies, while 16 are injured after a Land Rover hits a primary school in Wimbledon, south-west London. The crash is not treated as terror-related, but the driver is arrested on suspicion of causing death by dangerous driving. The UK Health Security Agency and Met Office issue a yellow heat health alert for six regions of England, effective from 12pm on 7 July to 9am on 9 July, when temperatures are expected to reach 28 °C–30 °C in some areas. RMT workers on the London Underground announce six days of strikes from Sunday 23 July to Friday 28 July. 7 July – British cinema chain Empire Cinemas collapses into administration with the immediate loss of 150 jobs, citing the impact of the COVID-19 pandemic and the ongoing cost-of-living crisis as the main reasons. The closures leave Sunderland and Wigan with no main cinema. 8 July – The Union Chain Bridge, which spans the River Tweed, linking England and Scotland, is named as an International Historic Civil Engineering Landmark. 9 July – A second child dies of injuries sustained in the crash at a school in Wimbledon, south London. 10 July – A teenage boy is arrested on suspicion of attempted murder after a teacher is stabbed at Tewkesbury School in Gloucestershire. The school, along with neighbouring schools, are locked down during the incident. The teacher is hospitalised. He is charged with attempted wounding with intent and possession of bladed article the next day.
Sources: en.wikipedia.org
Purity is usually reported as an HPLC area percentage, most often measured at 214 nm. Identity is confirmed separately by mass spectrometry. A certificate of analysis should state both the method and the observed value.
Dry powder is kept frozen, desiccated, and shielded from light. Dissolved material is aliquoted and frozen to limit freeze-thaw cycles. Short-term refrigerated storage is common for working solutions.
Russia registers it as a prescription nasal product. Most other markets classify it as a research chemical with no approved medical use. Oversight of purity and labeling is consequently minimal in those markets.
Reverse-phase HPLC is the usual method and gives a percentage purity value. Mass spectrometry then confirms the molecular mass. Together they provide a basic identity and purity profile for a lot.