prohibited substance raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
This page was last updated on 2026-03-11 and is reviewed periodically as new material appears.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Analytical method | LC-MS/MS | Preferred confirmatory technique |
| Appearance | White to off-white powder | Lyophilised form |
| Solubility | Freely soluble in water | Also described in saline |
| Storage temperature | Below -20 °C for powder | Short-term refrigeration for solutions |
| Regulatory status | Prohibited in sport | Listed under peptide hormones |
Purity and identity are separate measurements and are often confused. Reverse-phase high-performance liquid chromatography, usually with ultraviolet detection near 214 nanometres, reports the share of total peak area belonging to the target compound. Mass spectrometry by electrospray or matrix-assisted laser desorption then checks whether the observed mass matches the expected sequence. Neither measurement alone shows that a vial holds the intended peptide. Peptide content, meaning the fraction of vial mass that is genuine peptide rather than counter-ion, water or residual acid, is reported separately and is frequently lower than the stated purity figure.
The regulatory position is broadly consistent across major jurisdictions: no thymosin beta-4 fragment is an approved medicine, and laboratory material is commonly labelled as not intended for human consumption. Anti-doping rules in sport list thymosin beta-4 and its fragments among prohibited peptide hormones. Because these products travel through research-chemical channels rather than pharmaceutical supply chains, quality varies considerably between vendors. Independent testing of identity, purity and sterility is the only dependable check, and a certificate of analysis describes one batch rather than a supplier's whole catalogue.
Lyophilized peptide powder is normally held desiccated at −20 °C, with −80 °C used for longer storage periods. Allowing a sealed vial to reach room temperature before opening is standard practice, because condensation forming on cold powder introduces moisture. Once dissolved, solutions are typically kept cold and shielded from light. Repeated freeze-thaw cycles are avoided because they encourage aggregation and gradual loss of material. These conventions are general to synthetic peptides rather than unique to any one sequence.
Interest in the peptide grew during the 2000s and 2010s, when studies of tendon and ligament injuries in horses reported changes in lesion size after treatment. Those reports circulated widely outside the scientific literature and shaped much of the current online discussion. Subsequent reviews noted inconsistent study design, small groups, and a shortage of independent replication. Popular descriptions often blur the line between the fragment, the complete protein, and unrelated growth factors, which complicates comparisons across sources.
TB-500 is a synthetic peptide whose sequence corresponds to a short fragment near the N-terminus of thymosin beta-4, a small protein present in most mammalian cells. The fragment is commonly cited as containing the actin-binding region of the parent molecule, which is why it appears in laboratory work on cell migration and tissue repair. Suppliers distribute it as a lyophilised powder intended for research use. Its identity is defined by amino acid sequence and by the presence of an acetyl group on the N-terminal residue.
The compound circulates in the literature as a research reagent rather than an approved therapeutic. Regulatory agencies in several countries have not authorized it for medical use, and sporting bodies list related thymosin beta-4 peptides among prohibited substances. Suppliers typically market it with a purity figure and a certificate of analysis, while peer-reviewed clinical reports remain sparse. Discussions therefore often separate laboratory findings from anecdotal reports, and reviewers tend to note the small size and methodological limits of the available studies.
TB-500 refers to a synthetic peptide fragment derived from the actin-binding region of thymosin beta-4, a protein present in most mammalian cells. The full protein contains forty-three amino acids, while the commonly sold fragment is a much shorter acetylated sequence, often cited as LKKTETQ. The fragment retains part of the actin-binding motif but lacks the remainder of the parent protein. Material sold under this name is usually lyophilized powder intended for laboratory research, and it is not a finished pharmaceutical product.
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.
Research interest in thymosin beta-4 fragments centres on actin sequestration, cell migration and tissue repair models. Most published work uses cultured cells or animal wound and cardiac preparations, and findings are generally described as preliminary. No fragment of this protein has been approved as a therapeutic product by major regulators. Reviews of the field note inconsistent dosing, delivery routes and outcome measures across studies, which complicates direct comparison. The material is best understood as a laboratory reagent with an active but unresolved research literature.
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.
== Non-traditional use == In the late 20th century, the practice of ayahuasca drinking began spreading to Europe, North America and elsewhere. The first ayahuasca churches, affiliated with the Brazilian Santo Daime, were established in the Netherlands. A legal case was filed against two of the Church's leaders, Hans Bogers (one of the original founders of the Dutch Santo Daime community) and Geraldine Fijneman (the head of the Amsterdam Santo Daime community). Bogers and Fijneman were charged with distributing a controlled substance (DMT); however, the prosecution was unable to prove that the use of ayahuasca by members of the Santo Daime constituted a sufficient threat to public health and order such that it warranted denying their rights to religious freedom under ECHR Article 9. The 2001 verdict of the Amsterdam district court is an important precedent. Since then groups that are not affiliated to the Santo Daime have used ayahuasca, and a number of different "styles" have been developed, including non-religious approaches. In Peru, retreat centers such as Blue Morpho, founded by Hamilton Souther, in Iquitos began offering ayahuasca ceremonies to foreign visitors around 2004. International media coverage brought wider attention to the practice and coincided with the growth of ayahuasca tourism.
Japanese and Korean sea-farmers have grown wakame for centuries, and are still both the leading producers and consumers. Wakame has also been cultivated in France since 1983, in sea fields established near the shores of Brittany. Wild-grown wakame is harvested in Tasmania, Australia, and then sold in restaurants in Sydney and also sustainably hand-harvested from the waters of Foveaux Strait in Southland, New Zealand and freeze-dried for retail and use in a range of products.
== Sources == J. Aasen; I. A. Samdal; C. O. Miles; E. Dahl; L. R. Briggs; T. Aune (2005). "Yessotoxins in Norwegian blue mussels (Mytilus edulis): Uptake from Protoceratium reticulatum, metabolism and depuration". Toxicon. 45 (3): 265–272. doi:10.1016/j.toxicon.2004.10.012. PMID 15683864.
== External links == GeneReviews/NCBI/NIH/UW entry on Chondrodysplasia Punctata 2, X-Linked, Conradi-Hünermann Syndrome, Happle Syndrome EBP+protein,+human at the U.S. National Library of Medicine Medical Subject Headings (MeSH)
Lee, a longtime fan of baseball, donated 200 baseballs signed by famous Negro league players including Willie Mays, Hank Aaron, and Josh Gibson, to the Negro Leagues Baseball Museum in Kansas City, Missouri in June 2008. In late 2009, Lee and Lifeson launched an auction for their initiative "Grapes Under Pressure", in support of "Grapes for Humanity", a charity. The auction consisted of items from the band such as autographed guitars, cymbals and basses. There were autographs by band members from Depeche Mode, Tool, the Fray, Judas Priest, Pearl Jam and other bands in addition to a rare Epiphone guitar with signatures from Ricky, Julian, and Bubbles from Trailer Park Boys. The band is featured on the album Songs for Tibet, appearing with other celebrities as an initiative to support Tibet and Dalai Lama Tenzin Gyatso. The album, made downloadable on August 5, 2008, via iTunes, was released commercially on August 12, 2008. Rush have also been big supporters of Little Kids Rock, a nonprofit which works to restore and revitalize music education programmes in disadvantaged US public schools. Musician's Friend, Sabian, and Rush teamed to help Little Kids Rock provide percussion to public schools nationwide. They donated $500 of the proceeds from each Neil Peart Paragon Cymbal Pack sold, each of which came with a free splash cymbal personally autographed by Peart. The marketing initiative raised over $50,000 for Little Kids Rock.
Sources: en.wikipedia.org
The traditional account exaggerates the importance of Fulton and Jacobsen to Moniz's decision to initiate frontal lobe surgery, and omits the fact that a detailed body of neurological research that emerged at this time suggested to Moniz and other neurologists and neurosurgeons that surgery on this part of the brain might yield significant personality changes in the mentally ill. The frontal lobes have been the object of scientific inquiry and speculation since the late 19th century. Fulton's contribution, while it may have functioned as a source of intellectual support, is in itself unnecessary and inadequate as an explanation of Moniz's resolution to operate on this section of the brain. Under an evolutionary and hierarchical model of brain development, it had been hypothesized that those regions associated with the more recent development, such as the mammalian brain and, most especially, the frontal lobes, were responsible for more complex cognitive functions. However, this theoretical formulation found little laboratory support, as 19th-century experimentation found no significant change in animal behaviour following surgical removal or electrical stimulation of the frontal lobes. This picture of the so-called "silent lobe" changed in the period after World War I with the production of clinical reports of ex-servicemen with brain trauma. The refinement of neurosurgical techniques also facilitated increasing attempts to remove brain tumours and treat focal epilepsy in humans, and led to more precise experimental neurosurgery in animal studies.
== History == Scott Reismanis, a website developer from Melbourne, Australia, first pursued web development as a hobby, creating two websites dedicated to video games. Afterwards, he purchased the ChaosRealm.com domain and formed the Realm Network. The network comprised over twenty websites, one of which was ModDB's predecessor, ModRealm. Launched in 1998, ModRealm was initially dedicated to Counter-Strike cheat codes before becoming a modding website. The website became defunct in December 2001, when its network was shut down after its hosting service, Playnet, filed for bankruptcy. Reismanis was motivated to start a new website by the difficulty of searching for mods on the then-dominant search engine, AltaVista, much less mods released to the public. He began ModDB's development in January 2002, following IMDb's structure in the process. The website was launched as Mod Database in June 2002. It differed from his earlier websites in that its articles were managed by the community, not only the website's founder. By January 2005, ModDB listed 49,539 members and 2,191 mods. In 2006, the ModDB team launched AddonDB, whose aim was to list additional content for games not applicable under the category of game modifications. This includes models, skins and maps. Just one year into service, it was merged into ModDB.
=== Tax avoidance === In June 2021, the United States Senate Finance Committee, under Chair Ron Wyden (D-OR), began an investigation to determine if the company took advantage of loopholes in the Tax Cuts and Jobs Act of 2017 to significantly reduce its tax liability. In a letter to AbbVie CEO Richard Gonzalez, Wyden noted the company suffered a 2020 pretax loss in the US of $4.5 billion and an overseas pretax profit of $7.9 billion the same year. The report, released in July 2022, showed that AbbVie was able to dodge U.S. taxes by registering intellectual property in offshore jurisdictions such as Bermuda. As a result, while AbbVie received 75% of its sales of Humira in the United States, it only reported 1% of that income for U.S. tax purposes.
=== Molybdenum traces in seawater === Mo is found in the oceans at an average submicromolar concentration of ~10−7 M. Because it is present in seawater as molybdate (MoO2−4), a divalent oxyanion, it is not sorbed onto negatively charged clay minerals and interacts weakly with negatively charged particulate organic matter (POM). Therefore, it behaves as a conservative trace metal. Molybdenum is a transition metal that is evenly and consistently distributed in the oceans, similar to conservative tracers such as the chloride anion or deuterated water. Transition metals that exist as negatively charged species have oceanic residence times exceeding 10,000 years, which is much longer than the ocean's mixing time. They maintain concentrations that remain relatively constant with respect to salinity over long periods. Mo has an oceanic residence time of 80,000 years. It shows an almost even distribution across the oceans, with only a slight decrease near the surface. These characteristics make molybdenum likely the most crucial transition metal in seawater, as marine geochemists can use it as a stable reference tracer for other transition metals at trace levels.
Sources: en.wikipedia.org
Some instruments measure the average amount of hemoglobin in each reticulocyte; a parameter that has been studied as an indicator of iron deficiency in people who have conditions that interfere with standard tests. The immature reticulocyte fraction (IRF) is another measurement produced by some analyzers which quantifies the maturity of reticulocytes: cells that are less mature contain more RNA and thus produce a stronger fluorescent signal. This information can be useful in diagnosing anemias and evaluating red blood cell production following anemia treatment or bone marrow transplantation.
=== Reduction === Compared to ketones and aldehydes, esters are relatively resistant to reduction. The introduction of catalytic hydrogenation in the early part of the 20th century was a breakthrough; esters of fatty acids are hydrogenated to fatty alcohols.
=== Cartilage implants === In July 2016, the U.S. approved the use of a synthetic cartilage implant to treat arthritis in the joint of the big toe. The implant is made of saline and a bio-compatible polymer, and is inserted through an incision between the metatarsophalangeal (MTP) joint where natural cartilage has worn away. It is being researched for use in other joints. A separate orthopedic implant consisting of a hydrated, interpenetrating dual polymer network based on polyether urethane (PEU) was given breakthrough device designation from the U.S. Food and Drug Administration in July 2021. In September 2021, researchers used nasal chondrocyte-based engineered cartilage to treat osteoarthritic joints in two patients.
Coninae Fleming, 1822 — synonyms: Conulinae Rafinesque, 1815 (inv.); Textiliinae da Motta, 1995 (n.a.) Clathurellinae H. Adams & A. Adams, 1858 — synonyms: Defranciinae Gray, 1853 (inv.); Borsoniinae A. Bellardi, 1875; Pseudotominae A. Bellardi, 1888; Diptychomitrinae L. Bellardi, 1888; Mitrolumnidae Sacco, 1904; Mitromorphinae Casey, 1904; Lorinae Thiele, 1925 Conorbiinae de Gregorio, 1880—synonym: Cryptoconinae Cossmann, 1896 Mangeliinae P. Fischer, 1883—synonym: Cytharinae Thiele, 1929 Oenopotinae Bogdanov, 1987—synonym: Lorinae Thiele, 1925 sensu Thiele Raphitominae A. Bellardi, 1875—synonyms: Daphnellinae Casey, 1904; Taraninae Casey, 1904; Thatcheriidae Powell, 1942; Pleurotomellinae F. Nordsieck, 1968; Andoniinae Vera-Pelaez, 2002 † Siphopsinae Le Renard, 1995
=== Muscle spasticity === Botulinum toxin is used to treat a number of disorders characterized by overactive muscle movement, including cerebral palsy, post-stroke spasticity, post-spinal cord injury spasticity, spasms of the head and neck, eyelid, vagina, limbs, jaw, and vocal cords. Similarly, botulinum toxin is used to relax the clenching of muscles, including those of the esophagus, jaw, lower urinary tract and bladder, or clenching of the anus which can exacerbate anal fissure. Botulinum toxin appears to be effective for refractory overactive bladder.
Sources: en.wikipedia.org
The most common approach is liquid chromatography with tandem mass spectrometry after extraction from blood or urine. Immunoassays exist but are generally treated as screening tools because of cross-reactivity.
Dry lyophilised powder is normally kept frozen and protected from moisture and light. Dissolved material is handled cold and used promptly to limit degradation.
It is not licensed as a medicine in major markets and is distributed as a research chemical. Sports organisations prohibit its use, and some countries restrict import and supply.
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.