This is a working overview of prohibited list, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-04-26. Anything still debated is marked as such rather than presented as settled.
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.
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.
Literature and online discussion often conflate TB-500 with full-length thymosin beta-4, even though the two differ in size and are not interchangeable in analytical terms. The fragment is produced by solid-phase peptide synthesis, and the product is a defined seven-residue chain rather than a biological extract. Because the term is a trade-style label, two vendors may supply materials of the same nominal sequence but different counter-ion content, purity, or water content. Comparisons across studies are therefore difficult unless the exact sequence and purity are reported.
TB-500 is a research peptide whose sequence matches residues 17 to 23 of thymosin beta-4, a 43-residue protein present in most mammalian cells. The chain is seven amino acids long, written as LKKTETQ, and is normally supplied with an acetyl group on the N-terminus. Suppliers list it as a lyophilised powder under the code name TB-500, and the same sequence appears elsewhere in catalogues as the thymosin beta-4 actin-binding fragment. The label is commercial rather than systematic, so no single authority fixes exactly what TB-500 denotes.
Thymosin beta-4 was isolated from calf thymus in the early 1980s and later characterised as an abundant intracellular actin-sequestering protein. Interest in short synthetic fragments grew once the actin-binding motif had been mapped to the middle of the sequence. TB-500 came out of that line of work as a truncated analogue rather than a natural isolate, and it is now sold mainly to laboratories. Published studies on the fragment have been largely in vitro or in animal models, and controlled human trials remain sparse, so claims about effects in people rest on extrapolation.
| Property | Value | Notes |
|---|---|---|
| Molecular mass | Approximately 4963 Da for full-length thymosin beta-4 | Value applies to the parent protein; fragment products may differ |
| Appearance | White to off-white lyophilized powder | Typical form of supplied synthetic peptide |
| Solubility | Freely soluble in water | Polar peptide; dissolves readily in aqueous buffer |
| Storage of dry powder | −20 °C, desiccated, protected from light | Standard laboratory practice for peptides |
| Typical detection method | Liquid chromatography–tandem mass spectrometry | Used in purity testing and anti-doping analysis |
Purity is normally assessed by reversed-phase HPLC, with the main peak reported as a percentage of total peak area, while identity is confirmed by mass spectrometry. Electrospray and MALDI-TOF instruments are both used, and the observed mass is compared with the value calculated from the stated sequence. Ion-exchange or size-exclusion methods appear where aggregation or charge variants are of interest. Water content, counter-ion content and residual trifluoroacetate from purification are separate variables that can shift the measured mass and should be weighed when reading a certificate of analysis.
Research peptides are typically supplied as a white to off-white lyophilised powder in a sealed vial. The dry solid is more stable than a solution and is normally kept refrigerated or frozen until use. Dissolution is usually done in water, phosphate-buffered saline or a similar aqueous medium, depending on the assay. Because the material is hygroscopic and easily contaminated, opening vials in a low-humidity environment and recording the lot number before use are standard laboratory practices.
Once in solution, short peptides are generally less stable than the dry powder, and repeated freeze-thaw cycles are a common cause of loss. Laboratory guidance usually calls for aliquoting on first dissolution and storing aliquots at -20 °C or below, away from light. Adsorption to plastic and glass surfaces can lower measured concentration, particularly at low concentrations, so container material and buffer choice can affect results. Visible cloudiness, colour change or unexpected precipitate is a signal to re-check the material.
Thymosin beta-4 itself is a small, widely expressed protein that sequesters monomeric actin and participates in cell migration, angiogenesis, and tissue repair. Researchers have examined the shortened fragment as a possible mimic of some of these activities, reasoning that the actin-binding motif lies within the first few residues. Binding to monomeric actin has been observed in cell-free systems. Whether the fragment reproduces the broader effects of the full protein in living tissue remains an open question, and findings from animal models are frequently cited without a clear bridge to human physiology.
Discussion of TB-500 appears in several distinct literatures that rarely cite one another. Peer-reviewed studies usually describe in vitro assays or small animal experiments and are cautious about extrapolation. Veterinary and sports communities circulate anecdotal reports with limited methodological detail. Commercial listings add a third layer, often using the name interchangeably with thymosin beta-4 even though the two molecules differ in size and sequence. Regulatory status varies by country, and the compound is not a licensed medicine in most jurisdictions, so readers comparing sources should check which molecule and which purity each source actually describes.
TB-500 is a synthetic seven-residue peptide whose sequence, LKKTETQ, matches the N-terminal actin-binding region of thymosin beta-4. It is usually supplied in an N-terminally acetylated form, a modification that blocks the free amino terminus and can influence behavior in solution. In the research literature the same sequence appears under several names, including thymosin beta-4 fragment and shortened thymosin beta-4. Because it is a short peptide rather than the full 43-residue parent protein, its measured properties differ from those reported for thymosin beta-4 as a whole, and the two are not interchangeable in experimental design.
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.
Lyophilized peptide arrives as a dry cake that should stay sealed until use. Reconstitution is generally performed with sterile water or a buffered solution, and the resulting liquid should be handled gently to limit mechanical stress. Repeated freeze-thaw cycles are widely described as harmful to short peptides, so dividing a reconstituted batch into single-use portions is a common practice. Laboratories also record the solvent, concentration, and date of preparation on the vial label to keep later measurements traceable.
In October 2008, Anatoly Barankevich, the head of the Security Council of South Ossetia, said in an interview that during the war, "Firstly, they [the Georgians] had T-72 tanks, and we only have three tanks, and they are T-55, [...] We had moved them out secretly, put them near the city, and they did a good job, and then entered the city." Researcher Andrey Illarionov later commented on the remarks of Barankevich, "This means that the tanks were in the conflict zone. Near Tskhinvali, which is prohibited by the Dagomys Agreement." In November 2008, Novaya Gazeta reported that Valentin Malykh received a phone call from his son in Vladikavkaz on the early morning of August 7 and Valentin wanted to congratulate his son on his birthday. But his son said that he was being sent to the war in Tskhinvali.
Traumatic acid is a monounsaturated dicarboxylic acid that occurs naturally in plants. The compound was first isolated from wounded bean plants by American chemists James English Jr. and James Frederick Bonner and Dutch scientist Arie Jan Haagen-Smit in 1939. Traumatic acid is a potent wound healing agent in plants ("wound hormone") that stimulates cell division near a trauma site to form a protective callus and to heal the damaged tissue. It may also act as a growth hormone, especially in inferior plants (e.g. algae). Traumatic acid is biosynthesized in plants by non-enzymatic oxidation of traumatin (12-oxo-trans-10-dodecenoic acid), another wound hormone. Traumatic acid, was among the first biologically active molecules isolated from plant tissues. This dicarboxylic acid was shown to be a potent wound healing agent in plant that stimulates cell division near a wound site, it derives from 18:2 or 18:3 fatty acid hydroperoxides after conversion into oxo- fatty acids. At normal conditions, traumatic acid is a solid, crystalline, water-insoluble substance. The salts and esters of traumatic acid are called traumatates. Traumatic acid is used as an intermediate in prostaglandin synthesis. It is also a constituent of some pharmaceutical products, such as the odontostomatologic gel Restomyl, due to its mucosal re-epithelialization activity.
== Benefits == SASP can aid in signaling to immune cells for senescent cell clearance, with specific SASP factors secreted by senescent cells attracting and activating different components of both the innate and adaptive immune system. The SASP cytokine CCL2 (MCP1) recruits macrophages to remove cancer cells. Although transient expression of SASP can recruit immune system cells to eliminate cancer cells as well as senescent cells, chronic SASP promotes cancer. Senescent hematopoietic stem cells produce a SASP that induces an M1 polarization of macrophages which kills the senescent cells in a p53-dependent process. Autophagy is upregulated to promote survival. SASP factors can maintain senescent cells in their senescent state of growth arrest, thereby preventing cancerous transformation. Additionally, SASP secreted by cells that have become senescent because of stresses can induce senescence in adjoining cells subject to the same stresses, thereby reducing cancer risk. SASP can play a beneficial role by promoting wound healing. SASP may play a role in tissue regeneration by signaling for senescent cell clearance by immune cells, allowing progenitor cells to repopulate tissue. In development, SASP also may be used to signal for senescent cell clearance to aid tissue remodeling. The ability of SASP to clear senescent cells and regenerate damaged tissue declines with age. In contrast to the persistent character of SASP in the chronic inflammation of multiple age-related diseases, beneficial SASP in wound healing is transitory.
Prime Minister Rishi Sunak meets with US president Joe Biden at the Grand Central Hotel in Belfast. Biden makes a keynote speech at the Ulster University during which he urges Northern Ireland's politicians to restore the power-sharing government. A 74-year-old man is extradited from Pakistan and charged with murdering police officer Sharon Beshenivsky in November 2005. Tesco reduces the price of a four pint bottle of milk from £1.65 to £1.55 following a cut in wholesale prices. Coronation of Charles III and Camilla: Buckingham Palace confirms that the Duke of Sussex will attend the coronation, but that the Duchess will remain in the United States with their children. 13 April Data published by the Office for National Statistics shows a 0% growth in the UK economy during February as growth in the construction industry was offset by industrial action. Publication of the Deciphering Developmental Disorders study, a study involving children with development disorders, which has identified 60 new health conditions. Sainsbury's follows Tesco in cutting the price of milk. A report published by Diabetes UK indicates the UK is heading for what the charity describes as a "rapidly escalating diabetes crisis", with 4.3 million people experiencing a form of diabetes, a further 850,000 estimated to be living with the disease but unaware of it, and another 2.4 million people at risk of developing the condition. Cases of diabetes are more prevalent in less affluent areas of the country. 14 April Ford receives government approval for its "BlueCruise" Level 2 autonomous driving technology.
ATPases (EC 3.6.1.3, Adenosine 5'-TriPhosphatase, adenylpyrophosphatase, ATP monophosphatase, triphosphatase, ATP hydrolase, adenosine triphosphatase) are a class of enzymes that catalyze the decomposition of ATP into ADP and a free phosphate ion or the inverse reaction. This dephosphorylation reaction releases energy, which the enzyme (in most cases) harnesses to drive other chemical reactions that would not otherwise occur. This process is widely used in all known forms of life. Some such enzymes are integral membrane proteins (anchored within biological membranes), and move solutes across the membrane, typically against their concentration gradient. These are called transmembrane ATPases.
Sources: en.wikipedia.org
Evidence is insufficient to support the use of medications to treat obstructive sleep apnea directly. This includes the use of fluoxetine, paroxetine, acetazolamide, and tryptophan among others. Recent studies are trying to investigate cannabinoids as a treatment for OSA, especially dronabinol, which is a synthetic form of THC (delta-9-tetrahydrocannabinol). Cannabis is known to influence sleep; for example, it can reduce sleep latency. However, results are not consistent. Studies about dronabinol have shown positive impact on the OSA, as they observed a reduced AHI (Apnea-Hypopnea Index) and an increased self-reported sleepiness (the objective sleepiness being unaffected). However, more evidence are needed as many effects of those substances remain unknown, especially the effects of a long-term intake. The effects on sleepiness and weight gain are particularly of concern. Due to uncertainty about its effects and a lack of consistent evidence, medical cannabis is not recommended for the treatment of OSA. There are multiple drugs approved for managing the excessive daytime sleepiness associated with OSA, but not the underlying cause. These include solriamfetol, modafinil, and armodafinil. For adults with obesity and moderate-to-severe OSA, during a 52-week study tirzepatide (brand name Zepbound) substantially reduced apneic-hypopnic events, body weight, hypoxic burden, hsCRP concentration, and systolic blood pressure, and improved sleep-related patient-reported outcomes, all presumably mediated via induced weight loss of 18–20% from baseline.
=== Generic names === Nandrolone is the generic name of the drug and its INNTooltip International Nonproprietary Name, BANTooltip British Approved Name, DCFTooltip Dénomination Commune Française, and DCITTooltip Denominazione Comune Italiana. The formal generic names of nandrolone esters include nandrolone cyclohexylpropionate (BANMTooltip British Approved Name), nandrolone cyclotate (USANTooltip United States Adopted Name), nandrolone decanoate (USANTooltip USAN, USPTooltip United States Pharmacopeia, BANMTooltip British Approved Name, JANTooltip Japanese Accepted Name), nandrolone laurate (BANMTooltip British Approved Name), nandrolone phenpropionate (USPTooltip United States Pharmacopeia), and nandrolone phenylpropionate (BANMTooltip British Approved Name, JANTooltip Japanese Accepted Name).
Ovaleap was approved for medical use in the European Union in September 2013. It was approved for medical use in Australia in March 2021. Bemfola was approved for medical use in the European Union in March 2014.
housekeeping gene Any constitutive gene that is transcribed at a relatively constant level across many or all known conditions and cell types. The products of housekeeping genes typically play critical roles in the maintenance of cellular integrity and basic metabolic function. It is generally assumed that their expression is unaffected by experimental or pathological conditions.
Kissinger summoned Dobrynin to the White House to accuse the Soviet Union of responsibility for the Easter Offensive, saying the North Vietnamese were fighting with Soviet-made weapons, and asked the Soviets to pressure the North Vietnamese to end the offensive.
Sources: en.wikipedia.org
=== Thyroid disease === Fetal maternal microchimerism may be related to autoimmune thyroid diseases. There have been reports of fetal cells in the lining of the blood and thyroid glands of patients with autoimmune thyroid disease. These cells could become activated after delivery of the baby after immune suppression in the mother is lost, suggesting a role of fetal cells in the pathogenesis of such diseases. Two types of thyroid disease, Hashimoto's thyroiditis (HT) and Graves' disease (GD), show similarities to graft vs host disease which occurs after hematopoietic stem cell transplants. Fetal cells colonize maternal tissues like the thyroid gland and are able to survive many years postpartum. These fetal microchimeric cells in the thyroid show up in the blood of women affected by thyroid diseases.
==== Chain length ==== A common means of expressing the length of a chain is the degree of polymerization, which quantifies the number of monomers incorporated into the chain. As with other molecules, a polymer's size may also be expressed in terms of molecular weight. Since synthetic polymerization techniques typically yield a statistical distribution of chain lengths, the molecular weight is expressed in terms of weighted averages. The number-average molecular weight (Mn) and weight-average molecular weight (Mw) are most commonly reported. The ratio of these two values (Mw / Mn) is the dispersity (Đ), which is commonly used to express the width of the molecular weight distribution. The physical properties of polymer strongly depend on the length (or equivalently, the molecular weight) of the polymer chain. One important example of the physical consequences of the molecular weight is the scaling of the viscosity (resistance to flow) in the melt. The influence of the weight-average molecular weight (
Cricket flour (or cricket powder) is a protein-rich powder made from crickets, using various processes. Cricket flour differs from true flours made from grains by being composed mainly of protein rather than starches and dietary fiber.
== Events == 6 January - The William and Mary founders in the Irish Sea off Milford Haven, Pembrokeshire, with the loss of all hands. 9 January - The ship Cecelia, on a voyage from Dublin to Barbados, founders in the Irish Sea off Holyhead, Anglesey, with the loss of all hands. 10 March - The ship Prosperous founders off Anglesey with the loss of all hands. 6 May - The first Welsh language version of the New Testament issued by the British and Foreign Bible Society is published. 1 October - The brig Mary runs aground on the Arklow Bank, in the Irish Sea and is wrecked with the loss of seven of the ten people on board. Two of the survivors are rescued by Mary, a ship homeported in Liverpool, Lancashire, whilst the third is rescued by Mary, a ship homeported in Amlwch, Anglesey. 25 October - The sloop Margaret, on a voyage from Bristol, Gloucestershire to Greenock, Renfrewshire, is wrecked near Holyhead, Anglesey, with the loss of all on board. 3 December - Ships affected by a storm in the Irish Sea include: Eliza, driven ashore at Cardigan, Pembrokeshire, on a voyage from Virginia, United States to Dublin. Her crew are rescued. John, on a voyage from Youghal, County Cork to Dublin, driven ashore at Caernarfon. Milford, driven ashore at Cardigan while on a voyage from Liverpool to Wilmington, Delaware, United States. Her crew are rescued. The first Nonconformist school in Wales is opened at Swansea. William Madocks obtains an Act of Parliament to allow him to construct a harbour at Portinllaen. William Owen Pughe inherits the estate of the Rev.
Sources: en.wikipedia.org
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.
No. No major regulatory authority lists an approved product under this name, and no pharmacopoeial monograph exists for it. Material sold under the label is therefore supplied outside approved pharmaceutical channels, which affects the quality documentation available.
It falls within a prohibited class covering peptide hormones and growth factors, based on presumed effects on tissue repair and blood vessel formation. Anti-doping laboratories have published mass spectrometry methods for detecting thymosin beta-4 related peptides in urine samples.
No. Thymosin beta-4 is a 43-residue protein, while TB-500 matches only residues 17 to 23 of that chain. The two are related but differ in size, and a method that identifies one does not automatically identify the other.