The short version of prohibited list fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2025-11-19 and is reviewed periodically as new material appears.
Dry powder is commonly held at minus twenty degrees Celsius, with some suppliers recommending lower temperatures for long-term archival storage. Once dissolved, solutions are typically kept cold and protected from light, since aqueous peptide solutions can lose integrity through hydrolysis or oxidation over time. Stability data specific to this fragment are limited in the public literature, and much of the guidance comes from general peptide handling practice rather than from controlled degradation studies. Users therefore treat stated shelf lives as approximate rather than fixed.
Identity and purity are normally assessed with reversed-phase high-performance liquid chromatography, paired with mass spectrometry to confirm molecular mass. A certificate of analysis reports a purity percentage, usually derived from chromatographic peak area, but that figure does not by itself prove a correct sequence or the absence of counterions. Independent verification may include amino acid analysis or peptide mapping. Batch-to-batch variation is a documented concern in the research chemical market, and the gap between a quoted purity value and actual peptide content can be substantial when the material is a salt or retains residual water.
The compound is most often distributed as a lyophilized powder, appearing white to off-white and forming a loose cake or fluffy solid. It is hygroscopic to some degree, so brief exposure to humid air can add water weight and complicate weighing. The peptide dissolves readily in water and in neutral aqueous buffers, and aqueous solubility is generally described as high, well above the concentrations used in typical assays. Some polar organic solvents are also usable, which matters when a concentrated stock is prepared before dilution into buffer.
Storage recommendations center on keeping the dry powder cold, dry, and dark. A freezer at -20 degrees Celsius or below is conventional, and desiccant is often included to limit moisture uptake. Once dissolved, the peptide is less stable, and solutions are typically kept frozen and thawed only once. Repeated freeze-thaw cycles are a common source of losses because they promote aggregation and adsorption to container surfaces. Working aliquots are therefore prepared in advance, and glass or low-binding plastic is usually preferred over ordinary laboratory plastic.
| Property | Value | Notes |
|---|---|---|
| Molecular mass | Approximately 0.9 kDa | Depends on exact fragment sequence and counterion |
| Amino acid sequence | LKKTETQ (commonly cited) | Short actin-binding motif from thymosin beta-4 |
| Common salt form | Acetate salt | Trifluoroacetate also reported in research material |
| Reconstitution solvent | Sterile water or buffer | Gentle mixing; avoid vigorous agitation |
| Solution storage | -20 °C or lower | Aliquot to avoid repeated freeze-thaw cycles |
Lyophilised material is stable for extended periods when kept dry and cold, and suppliers typically recommend storage well below freezing. Once dissolved, the peptide is handled at refrigeration temperatures and used within a short period, because peptide bonds and the acetylated terminus can be affected by repeated freeze-thaw cycles, proteases, or extreme pH. Bacteriostatic water and saline are both described as solvents, although preservatives can interfere with some analytical workflows. Reconstituted solutions are inspected for particulates before use.
Sports authorities classify the peptide as a prohibited substance, and it appears on the World Anti-Doping Agency list under peptide hormones, growth factors, and related substances. Racing jurisdictions for horses and dogs have issued separate restrictions, and several national bodies treat it as a controlled or prescription-only item. As a research chemical it is sold without a therapeutic indication, and labels usually state that the product is not for human or veterinary use. Regulatory treatment therefore varies by country.
Detection in biological matrices generally relies on liquid chromatography coupled with tandem mass spectrometry, because the peptide lacks a convenient ultraviolet chromophore beyond the amide backbone. Immunoassays have been described, but antibodies raised against the fragment can cross-react with the full-length protein or with unrelated peptides, so findings usually require confirmation by a second technique. Sample preparation typically involves protein precipitation followed by solid-phase extraction. Reported detection windows depend on dose, route, matrix, and instrument sensitivity.
TB-500 is a synthetic peptide preparation marketed under a name derived from thymosin beta-4, a 43-residue actin-binding protein first isolated from thymus tissue. The full-length protein has a reported molecular mass near 4963 Da, while material sold as TB-500 is often described as a fragment containing the actin-binding motif LKKTETQ. Because suppliers use the name inconsistently, published sources sometimes refer to the same label as a fragment, a synthetic copy, or a related analog. This naming ambiguity complicates direct comparison of reports across studies.
Laboratory work on thymosin beta-4 describes binding to monomeric actin and effects on cell migration, angiogenesis, and inflammatory signaling in cultured cells. Animal models have examined skin, corneal, and cardiac repair after injury, with outcomes reported mainly in preclinical literature. Most of that evidence concerns the parent protein rather than preparations labelled TB-500, so extrapolation from animal findings to a specific commercial product remains uncertain. Whether the two behave identically in living systems has not been established in controlled human studies.
No major regulatory agency has approved TB-500 for therapeutic use, and it holds no pharmacopoeial monograph. The name appears on the World Anti-Doping Agency prohibited list within the class covering peptide hormones, growth factors, and related substances. Detection in doping control relies on mass spectrometric methods applied to urine, often after preparation steps that concentrate the analyte. Discussion of TB-500 therefore clusters in biochemistry, sports medicine, and anti-doping literature rather than in registered clinical trials.
Thymosin beta-4 itself is a natural peptide of 43 residues found in many cell types and body fluids. Its best-characterised function is binding and sequestering actin monomers, which influences cytoskeletal dynamics. The sequence most often associated with TB-500, LKKTETQ, corresponds to part of that actin-binding region. A different fragment, Ac-SDKP, is also derived from the same parent peptide and is studied in its own right, which is one reason discussions of thymosin fragments can become confusing. The two are structurally distinct and are not interchangeable.
Interest in the fragment grew during the 1990s and 2000s, when it moved from laboratory work into sports and supplement markets. Anti-doping bodies added thymosin beta-4 fragments to prohibited lists, and a small number of adverse analytical findings have been reported in competition testing. Published controlled human trials remain scarce. Most mechanistic evidence comes from cell culture and animal models, and those studies examine endpoints such as cell migration, wound closure and inflammation markers. That evidence supports research interest but does not establish clinical benefit, and broad regenerative claims should be read as unverified.
TB-500 is a short synthetic peptide sold under a trade name rather than a systematic chemical name. Suppliers usually describe it as a fragment of thymosin beta-4 and ship it as a lyophilised powder intended for laboratory use. Because the label is commercial, the exact sequence attributed to it is not fully consistent across catalogues, and some listings present a seven-residue peptide while others describe related fragments of similar length. It is not an approved medicine in any major jurisdiction, and it is handled as a research chemical.
The pressure a liquid exerts against the sides and bottom of a container depends on the density and the depth of the liquid. If atmospheric pressure is neglected, liquid pressure against the bottom is twice as great at twice the depth; at three times the depth, the liquid pressure is threefold; etc. Or, if the liquid is two or three times as dense, the liquid pressure is correspondingly two or three times as great for any given depth. Liquids are practically incompressible – that is, their volume can hardly be changed by pressure (water volume decreases by only 50 millionths of its original volume for each atmospheric increase in pressure). Thus, except for small changes produced by temperature, the density of a particular liquid is practically the same at all depths. Atmospheric pressure pressing on the surface of a liquid must be taken into account when trying to discover the total pressure acting on a liquid. The total pressure of a liquid, then, is ρgh plus the pressure of the atmosphere. When this distinction is important, the term total pressure is used. Otherwise, discussions of liquid pressure refer to pressure without regard to the normally ever-present atmospheric pressure. The pressure does not depend on the amount of liquid present. Volume is not the important factor – depth is. The average water pressure acting against a dam depends on the average depth of the water and not on the volume of water held back. For example, a wide but shallow lake with a depth of 3 m (10 ft) exerts only half the average pressure that a small 6 m (20 ft) deep pond does.
== Sites of synthesis == Leptin is produced primarily in the adipocytes of white adipose tissue. It also is produced by brown adipose tissue, placenta (syncytiotrophoblasts), ovaries, skeletal muscle, stomach (the lower part of the fundic glands), mammary epithelial cells, bone marrow, gastric chief cells, and P/D1 cells.
The sexism was evident in many ways, according to Mamphela Ramphele, a BCM activist and doctor at the Zanempilo Clinic, including that women tended to be given responsibility for the cleaning and catering at functions. "There was no way you could think of Steve making a cup of tea or whatever for himself", another activist said. Feminism was viewed as irrelevant "bra-burning". Surrounded by women who cared about him, Biko developed a reputation as a womaniser, something that Woods described as "well earned". He displayed no racial prejudice, sleeping with both black and white women. At NUSAS, he and his friends competed to see who could have sex with the most female delegates. Responding to this behaviour, the NUSAS general secretary Sheila Lapinsky accused Biko of sexism, to which he responded: "Don't worry about my sexism. What about your white racist friends in NUSAS?" Sobukwe also admonished Biko for his womanising, believing that it set a bad example to other activists. Biko married Ntsiki Mashalaba in December 1970. They had two children together: Nkosinathi, born in 1971, and Samora, born in 1975. Biko's wife chose the name Nkosinathi ("The Lord is with us"), and Biko named their second child after the Mozambican revolutionary leader Samora Machel. Angered by her husband's serial adultery, Mashalaba ultimately moved out of their home, and by the time of his death, she had begun divorce proceedings. Biko had also begun an extra-marital relationship with Mamphela Ramphele. In 1974, they had a daughter, Lerato, who died after two months.
Sources: en.wikipedia.org
6 August Weather Forecast about weather forecasting in the UK; Swedish Lennart Bengtsson of the European Centre for Medium-Range Weather Forecasts; Alistair Woodroffe and Brian Webster of the Met Office; numerical calculations began in the early 1950s with computers making 10,000 calculations a second but by the mid-1980s it was one billion; Meteosat-2 launched in June 1981; Steven Burke of the London Potato Futures Association; Capt Derek Ralph in a British Caledonian BAC One-Eleven flying to Aberdeen Airport; amateur weatherman Bill Foggitt; the weather centre and Lockheed C-5 Galaxy aircraft at RAF Mildenhall; conservationist Robin Page; narrated by Muriel Gray, directed by John Dollar, made by Uden Associates 13 August Made to Measure, essentially a re-edited, slightly updated edition of the August 1986 episodes on the F1 Ford turbocharged engine, with a few minutes of new content; in May 1987 Peter Collins watches the previous San Marino Grand Prix; Ford Cosworth V6 B187 cars: engine mapping; Dick Scammel, general head of engineering; Martin Walters, chief development engineer; the engine is dismantled, and damage is found; Geoff Goddard, chief racing engine designer; electromagnetic pulses from the engine affected the working of the engine computer circuitry; rogue signals were picked up by the engine computer, so causing erratic fuel injection; French F1 driver Patrick Tambay listens to the sound of the turbo; the turbo pressure would be limited to 2.5 in 1988, before turbos were banned for the 1989 season; the Italian Grand Prix circuit; each team is allowed two sets of qualifying tyres; the tyres on the rear axle warm up before the front axle; the Honda V6 engine could produce 1200 hp; chief designer Rory Byrne, and F1 aerodynamic forces. Narrated mostly by Martin Jarvis and partly by Eleanor Bron 20 August Twang, Bang, Kerang!, about the electric guitar; the Fat Tuesdays night club, and Les Paul; Glenn Wilson of the Institute of Psychiatry in London; Louis Jordan in the late 1940s; Charlie Christian developed the Gibson-ES150; Steve Howe of Yes; Burns London manufacturing guitars; Dave Russell; the body of the guitar was made of maple, a tonewood, and the fretboard of rosewood; the sound originates from the type of wood; Jerry Donohue of Fairport Convention; pickups made by Seymour Duncan; Chet Atkins; Andy Summers of The Police and Every Breath You Take; Francis Dunnery of It Bites, and Once Around the World. Narrated by John Hedges, produced by Patrick Uden, directed by Jeremy Llewellyn-Jones, made by Uden Associates 27 August What Goes Up..., about dismantling the AGR at Sellafield; it featured Tom Marsham CBE FRS (10 November 1923 – 12 October 1989) of UKAEA at Risley, Warrington (Birchwood Park), who was the reactor manager of Calder Hall in 1956. Narrated by Sue Jay, produced by Michael Blakstad, made by Workhouse Productions 3 September Hole in the Sky, about the depletion of the ozone layer, with Sir Bob Watson at NASA; the NERC's British Antarctic Survey had been measuring ozone levels since 1957 at the Halley Research Station, and a team led by Joe Farman noticed a hole in the layer; NASA had not noticed an ozone hole on its Nimbus 7 satellite, although the satellite had picked up all of the data, as Richard Stolarski of the Goddard Space Flight Center found; the ozone hole was caused by the polar vortex over the winter, where air movements outside of Antarctica are trapped, and there is not enough light to form new ozone; some people believed that the 1982 Mexican El Chichón volcanic eruption was to blame; in 1974 F. Sherwood Rowland and Mario Molina of the University of California, Irvine found that some chlorine compounds would destroy ozone by making chlorine monoxide, and both received the 1995 Nobel Prize in Chemistry for this discovery; the Chemical Manufacturers' Association (since 2000 the American Chemistry Council) and the National Science Foundation launched a new atmospheric survey at McMurdo Station, led by Susan Solomon of the Earth System Research Laboratories; Jerry D. Mahlman of the Geophysical Fluid Dynamics Laboratory at Princeton was attempting a computer model of the Antarctic atmosphere; Rafe Pomerance of the World Resources Institute; the greenhouse effect, described by James Hansen of the Goddard Institute for Space Studies, who claimed that the Earth's temperature would be 2 degrees higher by 2000, 3 degrees higher by 2010, and 4 to 7 degrees warmer by 2030; Richard E. Benedick. Directed by Linda Harrar, produced by Paula Apsell, made by WGBH, Uden Associates, Television Trust for the Environment and Sveriges Television. Originally a Nova documentary 24 September Dirty Money, about whether the environment can be cleaned up; the UK's first anti-pollution trade fair in March 1987, attended by William Waldegrave; Father Jim Conlon and Portglenone Abbey in N Ireland, with an anaerobic digester, which saved £1000 a month in gas cost, and the manure was sold for £25,000 a year; Mike Flux of ICI; biologist Paul Johnston of Greenpeace, in Teesside; the River Tees was the second-most polluted in the UK, with Douglas Ord of Northumbrian Water; Ken Murphy, and how Greenpeace attempted to block an effluent pipe near Immingham in March 1985; John Elkington, environmental writer; BioTechnica of Llanishen in Cardiff, reclaiming contaminated land on a former highly polluted gasworks site in Lancashire; Jutta Ditfurth; Hans-Georg Peine of BASF AG, and the Sandoz chemical spill in November 1986 in Switzerland; in 1983, ICI founded the first bioplastic company, called Marlborough Biopolymers, which made polyhydroxy butyrate; Dame Anita Roddick of The Body Shop, who worked with Friends of the Earth; Peter Baylis of the NERC Environmental Satellite Laboratory, which began in 1975, in the University of Dundee's Ewing Building, and largely provided the only UK archive of satellite environmental data. Narrated by Bob Peck, produced by Edward Poulter, directed by David Sharp, made by London Scientific Films 1 October Malltime. A US production, produced by Mike Wallington, made by George Haggerty, made by Kai Productions 8 October Anything You Can Do..., about new robotics; the five houses puzzle; Richard Gregory, professor of neuropsychology at the University of Bristol; Roger Mathias of Plessey Radar and the Multi-function Electronically Scanned Adaptive Radar (MESAR), began in 1982; Henry Thompson and speech recognition at the School of Informatics, University of Edinburgh; Robert Kowalski of the Department of Computing, Imperial College London; Margaret Boden of the University of Sussex; J. Michael Brady; Paul Caplin and robotics; Roy Bottomley of Meiko Scientific, and the transputer, developed in the UK; Plessey Laboratories at the Allen Clark Research Centre, and new chemical compounds for computer chip; logic programming and heuristics; the European Eureka Prometheus Project, an expert system. Narrated by Miriam Margolyes, produced by Michael Blakstad, directed by Catherine Robins, made by Workhouse Productions 22 October Command and Control, the chain of command of nuclear weapons; it featured the Air Force Research Laboratory. Directed by Clive Syddall, made by Twenty Twenty Vision 5 November Earthquake Country, about the San Andreas fault; Robert Wallace, chief scientist of the USGS; the 1906 earthquake caused the tectonic planes to move around seven metres; geologist Grove Karl Gilbert; an earthquake in the middle section of the fault was expected for around 1988; a 5.8 earthquake on 8 June 1934; geologist Kerry Sieh and paleoseismology; if an earthquake took place, coordination would be from the Joint Forces Training Base - Los Alamitos; earthquake engineer George W. Housner of Caltech; structural engineer Ray William Clough; earthquake engineer Luis Estava Maraboto of the Engineering Institute of the National Autonomous University of Mexico. Produced by Arabella Woods, directed by John Tchalenko, made by Red Rooster Films 12 November Nature's Technology, about the different types and the modelling of animal locomotion, and legged robots; robotic hands and bioengineer Stephen Jacobsen of the University of Utah; snake-arm robots; the 1986 Adaptive Suspension Vehicle (ASV) of Ohio State University, a hexapod robot, and Vincent Vohnout; active balance and Marc Raibert; the 1965 Walking Truck of General Electric; static stability and the Odex 1 six-legged robot; biomechanics and Robert McNeill Alexander, Professor of Zoology; WABOT-2 of Waseda University, optical music recognition and the NHK Symphony Orchestra of Japan conducted by Yuzo Toyama. Narrated by Adrienne Posta, directed by David Barlow, produced by Karl Sabbagh, made by InCA 19 November Britain Can Make It?, about making kitchen units in the UK and in Germany; the dual system of apprenticeship in Germany; Sig Prais of the National Institute of Economic and Social Research; the Britain Can Make It exhibition, where the fitted kitchen was first introduced in the UK; the Hungarian designer George Fejer was largely responsible for introducing fitted kitchens; Wolfgang Luckhaus of Poggenpohl of Germany, which also developed the fitted kitchen; in the 1960s the Germans introduced chipboard for kitchen manufacturing, which became industry-standard, with wipe-clean melamine resin facing (MFC); Hilary Steedman of the NIESR, and how the Germans built kitchens to order, whereas British companies simply built kitchens, whether ordered or not; Heal's of London introduced German kitchens to the UK in the early 1970s, in a hausfest; the German SieMatic kitchen company; Doug Gregory started The Symphony Group in 1970 after seeing chipboard, developing flatpack kitchen units, the Germans did not make flatpack kitchens, only assembled kitchens; David Love, buying director of MFI, which was helped by the flatpack revolution, but it was all largely an imitation of German products, and was a mostly standard product range; Symphony introduced computer production control in the 1980s, which the Germans had introduced in the early 1970s - this allowed much more variation of manufacturing to order, which was the main German method; employees of Symphony were largely unskilled, but German workers were largely skilled apprentices, who had passed exams in manufacturing; nearly all of German kitchens were built to order, so needed skilled workers; Walter Siekmann, production manager of Poggenpohl; German furniture manufacture was found in East Westphalia (Ostwestfalen); the Germans believed in more thorough technical training, and sold their products all over the world, but British companies had less-thorough training, and did not sell as worldwide as the Germans. Narrated by John Woodvine, directed by David Habakkuk, made by Riverside Television 26 November At the Edge, about the physical limits placed upon fighter pilots when flying high G capable modern aircraft, such as the F16 and the F18. Pilots are subjected to G-LOC in the Aerospace Medicine centrifuge in San Antonio, Texas. Narrated by Ray Brooks, written, produced and directed by Chris Haws, made by InCA
== Personalized Medicine == As metabolite analyses are being conducted at the individual patient level, pharmacometabolomics may be considered a form of personalized medicine. This field is currently being employed in a predictive manner to determine the potential responses of therapeutic compounds in individual patients, allowing for more customized treatment regimens. It is anticipated that such pharmacometabolomics approaches will lead to the improved ability to predict an individual's response to a compound, the efficacy and metabolism of it as well as adverse or off-target effects that may take place in the body. The metabolism of certain drugs varies from patient to patient as the copy number of the genes which code for common drug metabolizing enzymes varies within the population, and leads to differences in the ability of an individual to metabolize different compounds. Other important personal factors contributing to an individual's metabolic profile, such as patient nutritional status, commensal bacteria, age, and pre-existing medical conditions, are also reflected in metabolite assessment., Overall, pharmacometabolomic analyses combined with such approaches as pharmacogenetics, can function to identify the metabolic processes and particular genetic alterations that may compromise the anticipated efficacy of a drug in a particular patient. The results of such analyses can then allow modification of treatment regimens for an optimal outcome.
is the fraction of all possible contacts that involves an infectious and susceptible individual. (This is mathematically similar to the law of mass action in chemistry in which random collisions between molecules result in a chemical reaction and the fractional rate is proportional to the concentration of the two reactants.) Between I and R, the transition rate is assumed to be proportional to the number of infectious individuals which is
Masur, SK; Goodenough, U; Kane, CM; Marincola, E; Zavala, ME; Omotade, J (2021). "50 Years of Women in Cell Biology: Where have we been? Where are we going?". Mol Biol Cell. 32. doi:10.1091/mbc.E21-04-0186. PMC 8694079. PMID 34793240.
Sources: en.wikipedia.org
Dry lyophilized powder is usually kept frozen, desiccated, and out of direct light. Sealed vials are not opened until needed, because moisture uptake can degrade short peptides. Longer archival storage is often done at lower temperatures than routine working stock.
Reversed-phase liquid chromatography separates components and reports purity from peak area. Mass spectrometry confirms the molecular mass expected for the sequence. Additional approaches such as peptide mapping or amino acid analysis provide independent confirmation.
Reported percentages depend on the analytical method, the detection wavelength, and whether salts and water are counted. A value above ninety-five percent by chromatography does not by itself establish a correct sequence. Different suppliers also calculate purity against different reference standards.
Short transit at ambient temperature is generally tolerated, but long-term storage at room temperature is not recommended. Heat, moisture, and light all accelerate degradation. Cold, dry, dark storage is the conventional choice.