prohibited substance is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Last reviewed on 2026-08-01. Where a claim depends on a specific study, the study is described rather than over-claimed.
TB-500 is a catalogue name applied to a synthetic peptide related to thymosin beta-4, an actin-binding protein found in most mammalian cells. Suppliers do not use the label consistently: some describe it as the full 43-residue protein, others as a short fragment from the actin-binding region, and others as a related tetrapeptide. Because the name is commercial rather than chemical, two products sold under it may not contain the same molecule. This naming ambiguity is the first point to check in any description of the material.
The most frequently cited identity is a seven-residue fragment with the sequence LKKTETQ, taken from the actin-binding domain of the parent protein. A separate molecule, N-acetyl-seryl-aspartyl-lysyl-proline, often shortened to Ac-SDKP, derives from the same protein's N-terminal region and appears in overlapping literature. Reported molecular masses therefore differ between sources, and a mass value on its own does not establish which fragment is present. Confirmation requires a defined sequence rather than a single number.
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.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white lyophilized powder | Typical form for short synthetic peptides |
| Solubility class | Freely soluble in water and aqueous buffer | Dissolution aided by gentle mixing, not vigorous shaking |
| Typical storage temperature | −20 °C, desiccated | −80 °C used for long-term holding |
| Common analytical method | Reverse-phase HPLC with UV detection near 214 nm | Identity confirmed separately by mass spectrometry |
| Common synonyms | Thymosin beta-4 fragment; TB4 fragment | Naming varies between suppliers and publications |
Lyophilised peptide powders are hygroscopic, and the fragment absorbs atmospheric moisture when a vial is opened at room temperature. Weighing and aliquoting are normally done quickly in a dry environment, and stock solutions are divided into single-use portions before freezing. Repeated freeze-thaw cycles are avoided because they promote aggregation and can shift the measured content of a vial. These practices are general to synthetic peptides rather than unique to this sequence, but they matter more for short chains kept for long periods.
The seven-residue chain carries several polar and charged side chains, so it dissolves readily in water and in aqueous buffers near neutral pH. No cysteine is present, so disulphide formation is not a concern and reducing agents are unnecessary. Dilute ammonium hydroxide or acetonitrile-water mixtures are sometimes used for stock solutions when initial dissolution is slow. Strongly alkaline conditions and prolonged contact with oxidising agents are avoided because they can modify lysine-containing stretches, and haze in solution usually signals incomplete dissolution or aggregated material.
Identity and purity are checked with reversed-phase high-performance liquid chromatography, which separates the target sequence from truncated or deletion analogues, and with mass spectrometry, which confirms the expected molecular mass. Amino acid analysis and peptide mapping give orthogonal confirmation but are used less often outside specialist laboratories. Counter-ion content varies: material purified on trifluoroacetic acid gradients retains trifluoroacetate, and ion exchange can convert the salt form. Residual water and solvent are measured by Karl Fischer titration or thermogravimetric analysis, and any purity figure should be read together with the method used to obtain it.
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.
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.
Pseudomonas aeruginosa is a common encapsulated, Gram-negative, aerobic–facultatively anaerobic, rod-shaped bacterium that can cause disease in plants and animals, including humans. A species of considerable medical importance, P. aeruginosa is a multidrug resistant pathogen recognized for its ubiquity, its intrinsically advanced antibiotic resistance mechanisms, and its association with serious illnesses – hospital-acquired infections such as ventilator-associated pneumonia and various sepsis syndromes. P. aeruginosa is able to selectively inhibit various antibiotics from penetrating its outer membrane and has high resistance to several antibiotics. According to the World Health Organization P. aeruginosa poses one of the greatest threats to humans in terms of antibiotic resistance. The organism is considered opportunistic insofar as serious infection often occurs during existing diseases or conditions – most notably cystic fibrosis and traumatic burns. It generally affects the immunocompromised but can also infect the immunocompetent, as in hot tub folliculitis. Treatment of P. aeruginosa infections can be difficult due to its natural resistance to antibiotics. When more advanced antibiotic drug regimens are needed, adverse effects may result. It is citrate-, catalase-, and oxidase-positive. It is found in soil, water, skin flora, and most human-made environments throughout the world. As a facultative anaerobe, P. aeruginosa thrives in diverse habitats.
Alternative hypotheses suggest that venom evolution is due to trophic adaption, whereas these scientists believe, in this case, that selection would occur on traits that help with prey survival in terms of venom evolution instead of predation success. Several other predators of the pit viper (mongooses and hedgehogs) show the same type of relationship between snakes, which helps to support the hypothesis that venom has a very strong defensive role along with a trophic role. Which in turn supports the idea that predation on the snakes can be the arms race that produces snake venom evolution. Some of the various adaptations produced by this process include venom more toxic to specific prey in several lineages, proteins that pre-digest prey, as well as a method to track down prey after a bite. Though venom function has evolved to be specific to prey class (e.g. particular coagulatory effects), the evolution of broad toxicological effects (e.g. neurotoxicity or coagulotoxicity) does not appear to be broadly affected by prey type. The presence of digestive enzymes in snake venom was once believed to be an adaptation to assist digestion. However, studies of the western diamondback rattlesnake (Crotalus atrox), a snake with highly proteolytic venom, show that venom has no impact on the time required for food to pass through the gut. These various adaptations of venom have also led to considerable debate about the definition of venom and venomous snakes.
== Evolutionary implications == Most humans have multiple copies of the regulatory gene sequence for prodynorphin, which is virtually identical among all primates, whereas other primates have only a single copy. In addition, most Asian populations have two copies of the gene sequence for prodynorphin, whereas East Africas, Middle Easterners, and Europeans tend to have three repetitions. The extent of regulatory gene disparities for prodynorphin, between human and primates, has gained the attention of scientists. There are very few genes known to be directly related to mankind's speciation from other great apes. According to computational biologist researcher Matthew W. Hahn of Indiana University, "this is the first documented instance of a neural gene that has had its regulation shaped by natural selection during human origins." The prodynorphin polypeptide is identical in humans and chimpanzees, but the regulatory promoter sequences have been shown to exhibit marked differences. According to Hahn, "humans have the ability to turn on this gene more easily and more intensely than other primates", a reason why regulation of this gene may have been important in the evolution of modern humans' mental capacity.
Overall the missing information include[s] quantitative data on the composition and specifications of yohimbe bark and its preparations used in food and food supplements covering other alkaloids besides yohimbine, data on the bioavailability of active ingredients from the yohimbe bark extract and data on the toxicity of well specified individual preparations of yohimbe bark and the major yohimbe bark alkaloids, especially regarding subchronic toxicity, genotoxicity and reproductive toxicity. One study found that samples of brands sold in American brick-and-mortar stores contained highly variable amounts of yohimbine, with some brands of "yohimbe" not containing yohimbine from the P. johimbe tree, and other products containing no yohimbine at all. Labeling claims were often misleading. In analyses by other laboratories for products sold in the US, in other countries, and on the internet, highly variable content levels of yohimbine were revealed. Yohimbe sold in markets in West Africa where the tree grows may be adulterated with other species of the genus Pausinystalia, which contain little yohimbine. The amounts of alkaloid found even in genuine P. johimbe bark vary considerably, depending on the source of the bark (roots, stem, branches, height).
Sources: en.wikipedia.org
=== The Finke era with ten Bundesliga seasons (1991–2007) === SC Freiburg were promoted to the 2. Bundesliga in 1978–79, which they would compete in for a decade-and-a-half before making the breakthrough to the top-flight Bundesliga in 1993–94 under the management of Volker Finke. In their first Bundesliga season, Freiburg narrowly avoided relegation. They made a third-place finish in their second season at the top level, just three points behind champions Borussia Dortmund. It was at this time that they were first nicknamed Breisgau-Brasilianer (literally Breisgau-Brazilians), due to their attractive style of play. The club reached the UEFA Cup in 1995, where they were knocked out in the first round by Slavia Prague. In 2001 they reached the UEFA Cup for a second time, where they were knocked out by Feyenoord. Freiburg's first Bundesliga relegation was in 1997 after they finished in 17th position. While they have been relegated four times since first making the Bundesliga, they have thrice won immediate promotion back to the top league. It was the first time since 1992 that Freiburg played in the 2. Bundesliga for two consecutive seasons. Freiburg finished the 2006–07 season in fourth place in the 2. Bundesliga, missing out on the third automatic-promotion spot on goal difference to MSV Duisburg, although they won 12 of their last 16 league games. They were knocked out of the DFB-Pokal in the second round by VfL Wolfsburg on 24 October 2006. On 20 May 2007, Volker Finke resigned as the club's coach after 16 years in the job.
In 1972, the restaurant was selected as a feature location by George Lucas for his 1973 film American Graffiti. The Mel's used was located at 140 South Van Ness Avenue in San Francisco. It serves as the setting for the opening scene of the film as well as the backdrop for the opening credits, accompanied on the soundtrack by Bill Haley’s “Rock Around the Clock”. The prominent play given to the location has been credited with having saved the company from possibly going out of business. Signage and artwork from the Mel's chain are frequently used in marketing for the film. Universal Studios has built replica Mel's Drive-In restaurants, resembling the one featured in American Graffiti, at their theme parks in Hollywood, Orlando, Japan, Beijing, and Singapore. Prior to American Graffiti, Mel's was used as a location in the 1967 film Guess Who's Coming to Dinner. Spencer Tracy and Katharine Hepburn are out for a drive, and Tracy pulls into Mel's and orders Oregon boysenberry ice cream; he then has a minor traffic altercation with a black man. The Mel's was located in the Excelsior district of San Francisco. Hepburn and Tracy never actually visited the location. Mel's restaurants have since been featured in other media, such as Melrose Place (1996, Season 5, Episode 1), Doonesbury comics (December 18, 1989), and the book The American Drive-in by Mike Witzel.
High-strength alloy steel remains the primary material for submarines today, with 250–400-metre (820–1,310 ft) depths, which cannot be exceeded on a military submarine without design compromises. To exceed that limit, a few submarines were built with titanium hulls. Titanium alloys can be stronger than steel, lighter, and most importantly, have higher immersed specific strength and specific modulus. Titanium is also not ferromagnetic, important for stealth. Titanium submarines were built by the Soviet Union, which developed specialized high-strength alloys. It has produced several types of titanium submarines. Titanium alloys allow a major increase in depth, but other systems must be redesigned to cope, so test depth was limited to 1,000 metres (3,300 ft) for the Soviet submarine K-278 Komsomolets, the deepest-diving combat submarine, though continuous operation at such depths would produce excessive stress on many submarine systems. Titanium does not flex as readily as steel, and may become brittle after many dive cycles. Despite its benefits, the high cost of titanium construction led to the abandonment of titanium submarine construction as the Cold War ended. Deep-diving civilian submarines have used thick acrylic pressure hulls. Although the specific strength and specific modulus of acrylic are not very high, the density is only 1.18g/cm3, so it is only very slightly denser than water, and the buoyancy penalty of increased thickness is correspondingly low. The deepest deep-submergence vehicle (DSV) to date is Trieste.
Sources: en.wikipedia.org
The Greater Poland uprising of 1918–1919, or Wielkopolska uprising of 1918–1919 (Polish: powstanie wielkopolskie 1918–1919 roku; German: Großpolnischer Aufstand) or Poznań War was a military insurrection of Poles in the Greater Poland region (German: Grand Duchy of Posen or Provinz Posen) against German rule. The uprising had a significant effect on the Treaty of Versailles, which granted a reconstituted Second Polish Republic the area won by the Polish insurrectionists. The region had been part of the Kingdom of Poland and then Polish–Lithuanian Commonwealth before the 1793 Second Partition of Poland when it was annexed by the German Kingdom of Prussia. It had also, following the 1806 Greater Poland uprising, been part of the Duchy of Warsaw (1807–1815), a French client state during the Napoleonic Wars.
==== Batteries ==== Silicon-graphene anode lithium ion batteries were demonstrated in 2012. Stable lithium ion cycling was demonstrated in bi- and few layer graphene films grown on nickel substrates, while single layer graphene films have been demonstrated as a protective layer against corrosion in battery components such as the battery case. This creates possibilities for flexible electrodes for microscale Li-ion batteries, where the anode acts as the active material and the current collector. In 2014 researchers built a lithium-ion battery made of graphene and silicon, claiming took only 15 minutes to charge. In 2014, graphene with controlled topological defects was demonstrated to adsorb more ions, resulting in high-efficiency batteries. In 2015 argon-ion based plasma processing was used to bombard graphene samples with argon ions. That knocked out some carbon atoms and increased the capacitance of the materials three-fold. These "armchair" and "zigzag" defects reflect the configurations of the carbon atoms that surround the holes. In 2016, Huawei announced graphene-assisted lithium-ion batteries with greater heat tolerance and twice the life span of traditional Lithium-Ion batteries, the component with the shortest life span in mobile phones.
1 On 27 April 2010, Troy Buswell resigned from the ministry following questions arising from a personal affair with Greens MP Adele Carles. The following day, Premier Colin Barnett assumed the role of Treasurer, while Buswell's remaining portfolios were transferred to Bill Marmion, who had hitherto been a parliamentary secretary.
Sources: en.wikipedia.org
TB-500 is a trade-style label for a synthetic peptide connected to thymosin beta-4. It is sold mainly through research-chemical channels and is not a single chemically defined product across suppliers.
Not necessarily. Some vendors use the name for the full 43-residue protein, while others apply it to a short actin-binding fragment or to a related tetrapeptide. The sequence should be confirmed from documentation rather than assumed from the label.
No thymosin beta-4 fragment holds marketing approval as a medicine in major jurisdictions. Material offered for sale is typically labelled for laboratory research only.
Not necessarily. TB-500 is a commercial label that suppliers apply to synthetic peptides described as thymosin beta-4 or a fragment of it. Published research most often studies the full-length protein, so statements about one do not automatically transfer to the other.