A practical reference on HPLC: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
This page was last updated on 2025-10-16 and is reviewed periodically as new material appears.
Animal studies have examined behaviour in tests of anxiety, memory retention and stress response, and several report changes in neurotrophic or neurotransmitter-related markers. The human evidence base is much smaller, consisting mainly of short trials conducted in Russia with limited reporting in English-language journals. Sample sizes are modest and outcome measures vary between studies, so the findings are best described as preliminary. Independent replication under modern trial standards has not been widely reported.
Outside its country of origin the compound is generally handled as a research chemical rather than an approved medicine. No regulatory approval from the United States Food and Drug Administration or the European Medicines Agency has been granted for human use. Identity and purity are normally checked by reverse-phase high-performance liquid chromatography, with mass spectrometry used to confirm the molecular mass. Lyophilised material is stored cold and desiccated, and repeated freeze-thaw cycles are avoided.
Published work on this peptide almost always uses intranasal delivery, with drops or a spray applied to the nasal mucosa. Some animal experiments have used subcutaneous or intraperitoneal injection, and a smaller number have compared routes directly. Oral administration is not a focus of the literature, because short peptides of this size are broken down by digestive enzymes and cross intestinal barriers poorly. How much of an intranasal dose reaches the bloodstream intact in humans remains an open question.
Tuftsin, the parent structure, is a naturally occurring immunomodulatory tetrapeptide released from the Fc region of immunoglobulin G by spleen enzymes. Selank extends this four-residue sequence with three additional amino acids. The stated rationale is that the added tail slows enzymatic breakdown and may influence receptor interactions. How the full heptapeptide behaves at the molecular level is not firmly established, and proposed mechanisms often involve indirect modulation of neurotransmitter or immune signaling rather than a single defined target.
Selank is a synthetic heptapeptide developed in Russia. Its sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, a seven-residue chain built around the natural tetrapeptide tuftsin. Researchers at the Institute of Molecular Genetics of the Russian Academy of Sciences first described the compound in the mid-1990s. The design combined the tuftsin core with an added Pro-Gly-Pro tail, a modification intended to extend the molecule's stability in biological fluids. Published work on the peptide has appeared mainly in Russian-language journals.
Reported activity for Selank centers on anxiolytic and nootropic effects. Russian clinical reports describe use in anxiety and in cognitive or attention-related complaints. Most of this evidence comes from studies conducted by the same research groups that developed the peptide. Independent replication in other countries remains limited, and no major Western regulatory agency has approved the compound for any indication. The gap between local reports and external verification is a recurring point in discussions of the peptide.
| Property | Value | Notes |
|---|---|---|
| Common route | Intranasal | Also injected in some animal work |
| Solubility class | Freely soluble in water | Solid form is hygroscopic |
| Typical storage | About -20 degrees Celsius | Keep desiccated and dark |
| Purity method | Reverse-phase HPLC | Reported as area percent |
| Confirmatory method | Mass spectrometry | Verifies expected molecular mass |
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.
Lyophilised material kept dry at minus 20 degrees Celsius or colder is the most stable form, and suppliers commonly state a shelf life of two years or more under those conditions. Once dissolved, degradation accelerates through hydrolysis and deamidation, particularly at alkaline pH or elevated temperature. Working solutions are usually divided into single-use aliquots to avoid repeated freeze-thaw cycles. The choice of reconstitution solvent affects both stability and the ionic strength of the final preparation.
Reverse-phase high-performance liquid chromatography with ultraviolet detection near 214 nanometres is the standard purity method. Mass spectrometry, typically electrospray ionisation, confirms identity through the expected mass-to-charge pattern. Amino acid analysis can verify composition independently. Chiral purity requires separate techniques such as derivatisation followed by chromatographic separation, and such data are rarely reported for research-grade material.
Quantification in biological matrices relies on liquid chromatography coupled to tandem mass spectrometry with stable-isotope internal standards. Low plasma concentrations and adsorption to container surfaces both complicate measurement. Solid-phase extraction is often needed to reduce matrix interference before injection. Reported limits of quantification differ widely between laboratories, which makes direct comparison of pharmacokinetic results difficult and limits meta-analysis.
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.
== Artists == Absolute Babyface Calloway Carrie Lucas Collage The Deele Dynasty Jeffrey Daniel Klymaxx Lakeside Midnight Star Ralph Butler Shalamar The Soul Train Gang The Sylvers The Whispers Times 3 1-900 3rd Avenue
=== Metalloproteins === Metalloproteins are conjugated proteins that are characterized by having one or more metal ions attached to the protein as a prosthetic groups. These metal ions could be iron, zinc, copper, magnesium, etc., and these are very important to the biological functions and its protein activity. Metalloproteins are involved in a wide range processes from electron transfer to catalysis. Many enzymes are metalloproteins, since metal ions can act as cofactors in chemical reactions. For example, zinc ions can be associated with enzymes that are responsible for gene expression. Moreover, metalloproteins containing iron often are involved in oxygen transport and redox reactions. In this way, the presence of metal ions allows these proteins to perform certain tasks that would not be possible with amino acids alone.
Konrad Adenauer was 73 years old when he became chancellor in 1949, and for this reason he was initially reckoned as a caretaker. However, he ruled for 14 years. The grand statesman of German postwar politics had to be dragged—almost literally—out of office in 1963.
Iron is a chemical element; it has symbol Fe (from Latin ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, forming much of Earth's outer and inner core. It is the fourth most abundant element in the Earth's crust. In its metallic state it was mainly deposited by meteorites. Extracting usable metal from iron ores requires kilns or furnaces capable of reaching 1,500 °C (2,730 °F), about 500 °C (900 °F) higher than that required to smelt copper. Humans started to master that process in Eurasia during the 2nd millennium BC and the use of iron tools and weapons began to displace copper alloys – in some regions, only around 1200 BC. That event is considered the transition from the Bronze Age to the Iron Age. In the modern world, iron alloys, such as steel, stainless steel, cast iron and special steels, are by far the most common industrial metals, due to their mechanical properties and low cost. The iron and steel industry is thus very important economically, and iron is the cheapest metal, with a price of a few dollars per kilogram or pound. Pristine and smooth pure iron surfaces are a mirror-like silvery-gray. Iron reacts readily with oxygen and water to produce brown-to-black hydrated iron oxides, commonly known as rust. Unlike the oxides of some other metals that form passivating layers, rust occupies more volume than the metal and thus flakes off, exposing more fresh surfaces for corrosion.
=== Other haematology apparatus === Automatic erythrocyte sedimentation rate (ESR) readers, while not strictly analysers, do preferably have to comply to the 2011-published CLSI (Clinical and Laboratory Standards Institute) "Procedures for the Erythrocyte Sedimentation Rate Test: H02-A5 and to the ICSH (International Council for Standardization in Haematology) published "ICSH review of the measurement of the erythrocyte sedimentation rate", both indicating the only reference method, being Westergren, explicitly indicating the use of diluted blood (with sodium citrate), in 200 mm pipettes, bore 2.55 mm. After 30 or 60 minutes being in a vertical position, with no draughts and vibration or direct sunlight allowed, an optical reader determines how far the red cells have fallen by detecting the level.
Sources: en.wikipedia.org
With the target to unify these bilateral partnership agreements into one multilateral network, Prof. Rode invited interested Universities from Austria, Indonesia, Thailand and Vietnam to participate in the first ASEA-UNINET Plenary Meeting in Ho Chi Minh City. In 1994 the network comprised 25 Universities from Austria, Thailand, Indonesia and Vietnam. As of June 2014, more than 70 Universities from 16 European and South-East-Asian countries participate in the network. In addition to his scientific and networking activities, Prof. Rode served during the periods 1998–2001 and 2005–2008 as vice-president in the United Nations Commission on Science and Technology for Development (UNCSTD) representing the WEOG states EU, USA, Canada and Australia. In 2004 he became the first Austrian to serve as president in the United Nations Commission on Science and Technology for Development.
=== Melting point depression === A material may have lower melting point in nanoparticle form than in the bulk form. For example, 2.5 nm gold nanoparticles melt at about 300 °C, whereas bulk gold melts at 1064 °C.
Although a majority of OECD countries protect the right of employees to vote for directors on boards of corporations (usually at least one-third), Australia has not yet passed a general law by amending the Corporations Act 2001, the Fair Work Act 2009 or state laws for worker directors. However, Australia does have board-level employee representation (or "codetermination") in occupational pensions, and several specific sectors. First, under the Hawke-Keating government Australia enacted a leading model for voice in worker's capital, now in the Superannuation Industry (Supervision) Act 1993 section 89, requiring an "equal numbers of employer representatives and member representatives" on the board of directors or trustees in a super-fund. In 2010 a proposal was made to amend this for so called "independent directors" to be required to take the balance of power, appointed by the incumbent board, even though the evidence suggested this would be a step backwards. No changes were passed. There is not yet express legislation to require that asset managers, to whom investment and shareholder voting was outsourced, must follow the voting policies set by elected representatives on superannuation fund boards, as is found in Switzerland.
== As a lipid biomarker == Archaeol in the sediments typically originates from the hydrolysis of archaea membrane phospholipids during diagenesis. Due to its high preservation potential, it is often detected and used by organic geochemists as a biomarker for archaea activity, especially for methanogen biomass and activity. As a methanogen proxy, it is used by Michinari Sunamura et al. to directly measure the methanogens in the sediments of Tokyo Bay, and also used by Katie L. H. Lim et al. as an indicator of methanogenesis in water-saturated soils. C. A. McCartney et al. used it as a proxy for methane production in cattle. In the meantime, it is also used to help understand ancient biogeochemistry. It was used as a biomarker by Richard D. Pancost et al. in order to reconstruct the Holocene biogeochemistry in ombrotrophic peatlands. A pilot study led by Ian D. Bull et al. also used archaeol as a biomarker to reveal the differences between fermenting digestive systems in foregut and hindgut of ancient herbivorous mammals. Additionally, because of different degradation kinetics of intact archaeol and caldarchaeol, the ratio of archaeol to caldarchaeol was proposed as a salinity proxy in highland lakes, providing a tool for paleosalinity studies. Archaeol can also get hydrolyzed in some cases, with its side chains preserved as phytane or pristane, depending on the redox conditions.
One NADH molecule is produced by the enzyme glutamate dehydrogenase in the conversion of glutamate to ammonium and α-ketoglutarate. Glutamate is the non-toxic carrier of amine groups. This provides the ammonium ion used in the initial synthesis of carbamoyl phosphate. The fumarate released in the cytosol is hydrated to malate by cytosolic fumarase. This malate is then oxidized to oxaloacetate by cytosolic malate dehydrogenase, generating a reduced NADH in the cytosol. Oxaloacetate is one of the keto acids preferred by transaminases, and so will be recycled to aspartate, maintaining the flow of nitrogen into the urea cycle. We can summarize this by combining the reactions:
Sources: en.wikipedia.org
=== Early life and education === Martin Litchfield West was born on 23 September 1937 at Eltham General Hospital (Eltham, London), the elder child (there being a younger daughter, Dr Jennifer Bywaters) of civil engineer Maurice Charles West and Catherine Baker, née Stainthorpe. His parents lived at that time in Orpington, but moved in 1939 to Hampton, where his father was appointed resident engineer at the Metropolitan Water Board-operated waterworks. West's father's family were from the Home Counties, and his mother's family from Yorkshire and Durham. His paternal grandfather, Robert West, lectured in electrical engineering; his maternal grandfather, John Stainthorpe, was a railwayman from Pickering. Litchfield was the maiden name of his paternal grandmother. Aged four, West entered the private preparatory school of Denmead. At 11, he lost a scholarship at Colet Court (now St Paul's Juniors), but was offered a feepaying place instead. West discovered at Colet his interest in languages and invented at 14 a competitor of Esperanto he labelled 'Unilingua'. In 1951, he won a scholarship to the main school, St Paul's. Excelling at both linguistics and mathematics, he was advanced to the 'Upper Eighth' and sat for a scholarship to Balliol College a year early. His tutors included Donald Russell, Michael Stokes and Russell Meiggs. Among his peers were future Nobel Prize winner Anthony J. Leggett, and future Permanent Secretary Peter Gregson.
=== Venom spitting === Venom spitting is another venom delivery method that is unique to some Asiatic and African cobras. In venom spitting, a stream of venom is propelled at very high pressures outwards up to 3 meters (300 centimeters). The venom stream is usually aimed at the eyes and face of the target as a deterrent for predators. There are non-spitting cobras that provide useful information on the unique mechanics behind venom spitting. Unlike the elongated oval shaped exit orifices of non-spitting cobras, spitting cobras have circular exit orifice at their fang tips. This combined with the ability to partially retract their fang sheath by displacing the palato-maxillary arch and contracting the adductor mandibulae, allows the spitting cobras to create large pressures within the venom delivery system. While venom spitting is a less common venom delivery system, the venom can still cause the effects if ingested.
== Geography == According to the United States Census Bureau, the city has a total area of 149.60 square miles (387.5 km2), of which 148.54 sq mi (384.7 km2) is land and 1.07 sq mi (2.8 km2) (0.72%) is water. The Neuse River flows through the northeastern corner of the city. Raleigh is located in the northeast central region of North Carolina, where the Piedmont and Atlantic coastal plain regions meet. This area is known as the "fall line" because it marks the elevation inland at which waterfalls begin to appear in creeks and rivers. As a result, most of Raleigh features gently rolling hills that slope eastward toward the state's flat coastal plain. The city of Raleigh is located 24 mi (39 km) southeast of Durham; 63 mi (101 km) northeast of Fayetteville; 131 mi (211 km) northwest of Wilmington; 155 mi (249 km) southwest of Richmond, Virginia; and 165 mi (266 km) northeast of Charlotte. A small portion of Raleigh is located in Durham County, North Carolina.
==== MeSH D06.472.734 – pituitary hormones ==== MeSH D06.472.734.525 – pituitary hormones, anterior MeSH D06.472.734.525.343 – gonadotropins, pituitary MeSH D06.472.734.525.343.288 – follicle stimulating hormone MeSH D06.472.734.525.343.288.500 – follicle stimulating hormone, beta subunit MeSH D06.472.734.525.343.288.625 – follicle stimulating hormone, human MeSH D06.472.734.525.343.288.750 – glycoprotein hormones, alpha subunit MeSH D06.472.734.525.343.463 – luteinizing hormone MeSH D06.472.734.525.343.463.249 – glycoprotein hormones, alpha subunit MeSH D06.472.734.525.343.463.500 – luteinizing hormone, beta subunit MeSH D06.472.734.525.343.583 – menotropins MeSH D06.472.734.525.343.583.500 – urofollitropin MeSH D06.472.734.525.343.773 – prolactin MeSH D06.472.734.525.425 – growth hormone MeSH D06.472.734.525.425.875 – human growth hormone MeSH D06.472.734.525.690 – pro-opiomelanocortin MeSH D06.472.734.525.690.130 – corticotropin MeSH D06.472.734.525.690.130.050 – alpha-msh MeSH D06.472.734.525.690.130.200 – cosyntropin MeSH D06.472.734.525.690.480 – lipotropin MeSH D06.472.734.525.690.583 – melanocyte-stimulating hormones MeSH D06.472.734.525.690.583.050 – alpha-msh MeSH D06.472.734.525.690.583.075 – beta-msh MeSH D06.472.734.525.690.583.115 – gamma-msh MeSH D06.472.734.525.883 – thyrotropin MeSH D06.472.734.525.883.249 – glycoprotein hormones, alpha subunit MeSH D06.472.734.525.883.500 – thyrotropin, beta subunit MeSH D06.472.734.692 – pituitary hormones, posterior MeSH D06.472.734.692.433 – oxytocin MeSH D06.472.734.692.781 – vasopressins MeSH D06.472.734.692.781.100 – argipressin MeSH D06.472.734.692.781.100.250 – deamino arginine vasopressin MeSH D06.472.734.692.781.400 – lypressin MeSH D06.472.734.692.781.400.350 – felypressin MeSH D06.472.734.692.781.700 – ornipressin MeSH D06.472.734.692.881 – vasotocin
Sources: en.wikipedia.org
Most published work uses intranasal application, either as drops or as a nasal spray. Injection routes appear in a smaller set of animal experiments. Oral use is uncommon in the literature because peptide breakdown and poor absorption limit this route.
Reported human trials are few, brief and originate mainly from one country. They describe effects on anxiety-related measures, but sample sizes are small and reporting is limited. The results are widely regarded as preliminary rather than confirmed.
Reverse-phase liquid chromatography is used to assess purity and separation of related impurities. Mass spectrometry confirms that the observed molecular mass matches the expected peptide. A certificate of analysis from the supplier is the usual document of record.
Selank is a synthetic peptide made of seven amino acids. It is modeled on tuftsin, a natural tetrapeptide, with an added three-residue tail. It is not a small-molecule drug.