This is a working overview of reversed-phase HPLC, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2026-04-17 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.
Naming for this compound is not fully standardised in English sources. The spelling Selanc appears in some transliterations, and catalogue entries may instead list the peptide sequence itself as the identifier. Reference material sometimes groups it with other short synthetic peptides studied for behavioural effects, which can create confusion when citations are compared. Distinguishing the exact sequence from related tuftsin analogues is therefore a practical first step when reviewing any dataset or specification sheet.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, frequently abbreviated as TKPRPGP. It was designed as a structural analogue of tuftsin, a naturally occurring tetrapeptide released by enzymatic cleavage of the immunoglobulin heavy chain. The two additional proline residues at the C-terminal end extend the parent chain and change how the molecule behaves in solution. The free peptide has a calculated molecular mass of approximately 751.9 g/mol and is generally supplied as a lyophilised white to off-white powder.
Development work on the compound began in the 1980s and 1990s at the Institute of Molecular Genetics in Moscow, within the same research programme that produced the peptide Semax. Early investigators sought a tuftsin derivative with improved resistance to enzymatic breakdown and with activity in the central nervous system after peripheral administration. Most of the primary literature from this period was published in Russian, a factor that still shapes how easily the findings can be checked by outside groups.
| 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 |
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.
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.
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=== Blueprint === On October 13, 2021, Johnson announced an anti-aging attempt called Project Blueprint, which subsequently became the basis for a commercial company headquartered in Los Angeles co-founded with Kate Tolo. Johnson has stated the aims of the company are to reduce the biological age of his organs to that of an 18-year-old and "make death an option." Blueprint sells consumer health products including supplements and foods derived from Johnson's personal optimization protocol. The protocol that Johnson follows as the test subject cost approximately $2 million a year in 2023, and was tracking over 100 health measurements. He has since reduced his daily supplement intake from 111 to 30 by March 2026. In 2024, Blueprint Basics was launched as a subscription for consumers by Blueprint, costing $333 a month. In October, Blueprint raised $60 million in external funding from a group of investors that included Kim Kardashian and Cameron & Tyler Winklevoss. In July 2025, Gyre Renwick was appointed as the CEO of Blueprint, having formerly served as president of Modern Health. Johnson would continue to lead product and protocol development.
In March 2008, AFRL's Human Effectiveness Directorate located at Wright-Patterson AFB was merged with the Air Force School of Aerospace Medicine and the Human Performance Integration Directorate from the 311th Human Systems Wing both located at Brooks City-Base, Texas to form the 711th Human Performance Wing. In its vision statement, the wing includes the goals of improving aerospace medicine, science and technology, and human systems integration. The current Commander of the 711th is Brig. Gen. Timothy Jex. One practical application of its work is ensuring and advancing the safety of ejection systems for pilots. With the increasing number of females in the Air Force ranks, anthropometry is of greater import now than ever, and 711th's WB4 'whole-body scanner' enables swift and accurate acquisition of anthropometric data which may be used to design pilot equipment with a better fit for comfort and safety.
=== Function === Calcium is an essential element needed in large quantities. The Ca2+ ion acts as an electrolyte and is vital to the health of the muscular, circulatory, and digestive systems; is indispensable to the building of bone in the form of hydroxyapatite; and supports synthesis and function of blood cells. For example, it regulates the contraction of muscles, nerve conduction, and the clotting of blood. As a result, intra- and extracellular calcium levels are tightly regulated by the body. Calcium can play this role because the Ca2+ ion forms stable coordination complexes with many organic compounds, especially proteins; it also forms compounds with a wide range of solubilities, enabling the formation of the skeleton.
1 by the Secretary of State for Home Affairs 2 by the London County Council 1 by the Corporation of the City of London 2 (jointly) by the councils of the metropolitan boroughs of the County of London 1 (jointly) by the county councils of Buckinghamshire, Essex, Hertfordshire, Middlesex 1 (jointly) by the county councils of Kent and Surrey 1 (jointly) by the corporations of the county boroughs of Croydon, East Ham, West Ham 1 representative of the Metropolitan Police, appointed by the Secretary of State for Home Affairs 1 representative of the City of London Police appointed by the City Corporation 1 appointed by the Minister of Transport The members of the committee were to appoint a chairman themselves.
Sources: en.wikipedia.org
Historically, the first parameter for the determination of fracture toughness in the elasto-plastic region was the crack tip opening displacement (CTOD) or "opening at the apex of the crack" indicated. This parameter was determined by Wells during the studies of structural steels, which due to the high toughness could not be characterized with the linear elastic fracture mechanics model. He noted that, before the fracture happened, the walls of the crack were leaving and that the crack tip, after fracture, ranged from acute to rounded off due to plastic deformation. In addition, the rounding of the crack tip was more pronounced in steels with superior toughness. There are a number of alternative definitions of CTOD. In the two most common definitions, CTOD is the displacement at the original crack tip and the 90 degree intercept. The latter definition was suggested by Rice and is commonly used to infer CTOD in finite element models of such. Note that these two definitions are equivalent if the crack tip blunts in a semicircle. Most laboratory measurements of CTOD have been made on edge-cracked specimens loaded in three-point bending. Early experiments used a flat paddle-shaped gage that was inserted into the crack; as the crack opened, the paddle gage rotated, and an electronic signal was sent to an x-y plotter. This method was inaccurate, however, because it was difficult to reach the crack tip with the paddle gage.
==== Combinations of medications ==== A 2018 research review (16 studies included) found there was very little evidence to support or refute that combinations of medications were more effective than single medications for reducing fibromyalgia pain.
== In solids == The viscous forces that arise during fluid flow are distinct from the elastic forces that occur in a solid in response to shear, compression, or extension stresses. While in the latter the stress is proportional to the amount of shear deformation, in a fluid it is proportional to the rate of deformation over time. For this reason, James Clerk Maxwell used the term fugitive elasticity for fluid viscosity. However, many liquids (including water) will briefly react like elastic solids when subjected to sudden stress. Conversely, many "solids" (even granite) will flow like liquids, albeit very slowly, even under arbitrarily small stress. Such materials are best described as viscoelastic—that is, possessing both elasticity (reaction to deformation) and viscosity (reaction to rate of deformation). Viscoelastic solids may exhibit both shear viscosity and bulk viscosity. The extensional viscosity is a linear combination of the shear and bulk viscosities that describes the reaction of a solid elastic material to elongation. It is widely used for characterizing polymers. In geology, earth materials that exhibit viscous deformation at least three orders of magnitude greater than their elastic deformation are sometimes called rheids.
Bogert (1890), former president of the American Chemical Society and the Society of Chemical Industry William King Gregory (1900), zoologist, primatologist, paleontologist Reuben Ottenberg (1902), physician and haematologist Clinton Gilbert Abbott (1903), ornithologist, naturalist, director of the San Diego Natural History Museum Irving Langmuir (1903), winner of the 1932 Nobel Prize in Chemistry Edward Calvin Kendall (1906), winner of the 1950 Nobel Prize in Physiology or Medicine Harold E. B. Pardee (1906), pioneer in electrocardiogram research, namesake of Pardee's sign Grover Loening (1908), aircraft manufacturer, founder of Loening Aeronautical Engineering; developed the Loening Model 23, which won the 1921 Collier Trophy Michael Heidelberger (1909), immunologist, "father of modern immunology" Ernst Philip Boas (1910), physician and professor at Columbia University College of Physicians and Surgeons, son of German-American anthropologist Franz Boas Hermann Joseph Muller (1910), geneticist and winner of the Nobel Prize in Physiology or Medicine Ralph Randles Stewart (1911), botanist and founder of the National Herbarium, Islamabad Ludlow Griscom (1912), pioneer in field ornithology John Howard Northrop (1912), winner of the 1946 Nobel Prize in Chemistry Calvin Bridges (1912), geneticist, protege of Thomas Hunt Morgan known for his contribution to genetics Irving H.
=== Total contact casting === Total contact casting (TCC) is a specially designed cast designed to take the weight of the foot (off-loading) in patients with DFUs. Reducing pressure on the wound by taking the weight of the foot has proven to be very effective in DFU treatment. DFUs are a major factor leading to lower leg amputations among the diabetic population in the US, with 85% of amputations in diabetics being preceded by a DFU. Furthermore, the 5 year post-amputation mortality rate among diabetics is estimated at 45% for those with neuropathic DFUs. TCC has been used for off-loading DFUs in the US since the mid-1960s and is regarded by many practitioners as the "reference standard" for off-loading the bottom surface (sole) of the foot. TCC helps patients maintain their quality of life. By encasing the patient's complete foot — including the toes and lower leg — in a specialist cast to redistribute weight and pressure from the foot to the lower leg during everyday movements, patients can remain mobile. TCC redistributes pressure, protects the wound, letting damaged tissue regenerate and heal. TCC also keeps the ankle from rotating during walking, which helps prevent shearing and twisting forces that can further damage the wound. Effective offloading is a key treatment modality for DFUs, particularly those where there is damage to the nerves in the feet (peripheral neuropathy). Along with infection management and vascular assessment, TCC is a vital aspect to effectively managing DFUs. TCC is the most effective and reliable method for off-loading DFUs.
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.
The sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, commonly written as TKPRPGP. It shares the first four residues with tuftsin and carries three prolines in the chain. The proline-rich tail is the main structural feature that separates it from the parent tetrapeptide.