Everything below concerns peptide fragment. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2025-09-25. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
Interest in the compound comes largely from studies of the parent protein, which participates in actin sequestration, cell migration and tissue repair processes. Whether a short fragment reproduces those activities is a separate question that remains open in the published record. Many summaries describe mechanisms by analogy to thymosin beta-4 rather than from direct measurements on the fragment. Claims about activity should be treated as provisional unless a cited study specifies the exact peptide, its purity and the assay used.
TB-500 is a laboratory label applied to a short synthetic peptide that is widely described as a fragment of thymosin beta-4, an actin-binding protein present in most mammalian cells. Suppliers and review articles usually present TB-500 as the N-terminal region of that protein, but the exact sequence attached to the name is not consistent across sources. Some product descriptions list a seven-residue chain; others use the label loosely for the parent protein itself. Because of that variation, any technical discussion of TB-500 needs to state which sequence is meant.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white powder | Supplied as a lyophilised cake in sealed vials |
| Solubility class | Freely soluble in water | Polar and charged side chains dominate the sequence |
| Typical storage temperature | -20 °C or below | Dry and dark; a desiccant is often recommended |
| Identity confirmation | Mass spectrometry | Observed mass compared with the theoretical value |
| Common synonyms | Thymosin beta-4 fragment | Also written as T beta 4 fragment 17-23 |
The fragment most often associated with the name carries the sequence Ac-LKKTETQ, matching residues 17 through 23 of thymosin beta-4. That region holds the actin-binding motif responsible for much of the parent protein's biochemical activity. Apart from N-terminal acetylation the peptide is unmodified and contains no disulfide bonds, so it shows little ordered secondary structure in solution. Full-length thymosin beta-4 is instead a 43-residue polypeptide of roughly 4.9 kDa found widely across mammalian cell types.
Material sold under this label typically arrives as a freeze-dried powder in a sealed vial with a certificate of analysis. Such certificates usually report reversed-phase chromatography purity plus a mass confirmation, and stated purities commonly sit between 95 and 99 percent. Counter-ion identity, residual trifluoroacetate, water content, and peptide net weight are separate specifications that a certificate may or may not include. A purity figure alone does not establish sequence identity, so independent mass verification remains the practical check.
Published work involving this sequence spans actin-binding assays, cell-migration studies, wound-healing models, and cardiovascular or musculoskeletal experiments. Much of the biological rationale derives from in vitro systems and animal models, and the number of controlled human studies is small. Reported outcomes vary across preparations, doses, and routes, which complicates comparison between studies. Reviews generally describe the evidence base as preliminary rather than settled. Mechanistic explanations are often proposed by analogy to the parent protein rather than demonstrated directly.
TB-500 is a synthetic seven-amino-acid peptide with the sequence LKKTETQ, corresponding to residues 17 through 23 of the protein thymosin beta-4. The N-terminus is typically acetylated in the described form, giving a monoisotopic mass near 888.5 Da and an average mass of about 889 Da. The designation TB-500 is a catalogue label rather than a formal chemical name, and the same sequence appears in the literature under several alternative abbreviations. It is handled as a research reagent rather than a pharmaceutical product.
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.
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.
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.
== Other uses == HMS Vesta, a schooner of the Royal Navy IF Vesta, sports club in Uppsala, Sweden established in 1911 SS Vesta (1853–1875), a French iron screw steamer Vesta (name), feminine given name Vesta Rowing Club (founded 1870), a rowing club based in London, England Vesta Battery Corporation (1897–1964), an automobile battery company
Review of a clinical trial by experts chosen by the study sponsor. These experts review the trials for scientific merit, participant safety, and ethical considerations. (NLM) Per protocol set (Valid Cases, Efficacy Sample, Evaluable Subjects Sample)
=== Latin America === He has been an advocate for the Venezuelan government of Hugo Chávez and, in his Fidel Castro Handbook, for the former Cuban leader. "You were the greatest man I ever met Comandante Fidel. You were the man of the century", he tweeted when Castro died in November 2016.
Bukele registered as a presidential pre-candidate on 26 June 2023 with Nuevas Ideas; Ulloa registered as Bukele's vice-presidential pre-candidate. Nuevas Ideas nominated Bukele and Ulloa as their presidential and vice-presidential candidates on 9 July. The party began registering Bukele and Ulloa's candidacies with the TSE on 26 October, the last day to do so. On 3 November 2023, the TSE registered their candidacies amidst opposition requests to reject Bukele's candidacy. On 30 November 2023, the Legislative Assembly granted Bukele and Ulloa leaves of absence to focus on their re-election campaign. The leave went into effect the following day and Bukele's presidential powers were suspended. The Legislative Assembly named Claudia Rodríguez de Guevara, Bukele's presidential secretary, as the presidential designate; Rodríguez was the first woman in Salvadoran history to hold presidential power. Her appointment was criticized by some lawyers and opposition politicians as unconstitutional. Including Bukele, there were six presidential candidates in the 2024 election. His primary opponents were ARENA's Joel Sánchez, a businessman, and the FMLN's Manuel Flores, a former legislator. Bukele led Sánchez and Flores by large margins in opinion polling before the election. Bukele promised to maintain the gang crackdown, invest in infrastructure projects, and promote economic growth during his second term. On 4 February 2024, he won re-election with 84.65 percent of the vote. Bukele was the first Salvadoran president to be re-elected since Maximiliano Hernández Martínez in 1944.
=== Characters and setting === Decay is set in the same location and timeframe as Half-Life. Half-Life takes place at a laboratory called the Black Mesa Research Facility, situated in a remote desert in New Mexico. In Half-Life, the player takes on the role of Gordon Freeman, a scientist involved in an accident that opens an inter-dimensional portal to the borderworld of Xen, allowing the alien creatures of Xen to attack the facility. The player guides Freeman in an attempt to escape the facility and close the portal, ultimately traveling to Xen to do so. Like the previous expansions, Decay shows the story of Half-Life from the perspective of a different set of protagonists. In Decay, players assume the roles of Colette Green and Gina Cross, two doctors who work in the same labs as Freeman, analyzing anomalous materials and specimens retrieved from Xen in prior teleportation experiments. After the experiment that causes the alien invasion takes place, Green and Cross must work with two ranking members of the science team, Dr. Richard Keller and Dr. Rosenberg, to contain and stabilize the deteriorating situation in Black Mesa.
Sources: en.wikipedia.org
=== Development === Parafollicular cells are derived from pharyngeal endoderm. Embryologically, they associate with the ultimopharyngeal body, which is a ventral derivative of the fourth (or fifth) pharyngeal pouch. Parafollicular cells were previously believed to be derived from the neural crest based on a series of experiments in quail-chick chimeras. However, lineage tracing experiments in mice revealed that parafollicular cells are derived from the endoderm origin.
=== Available forms === Ceftriaxone is available for administration via the intramuscular or the intravenous routes. Ceftriaxone is stored as a dry powder in a vial, and is reconstituted (dissolved) immediately before use. The solution is used promptly after preparation, still, reconstituted solutions retain their physical and chemical stability for 24 hours at 25°C (or for 3 days when stored between 2 and 8°C). The solutions are pale yellowish in color, but the change of color to amber or reddish suggests hydrolysis of the amide bond of the β-lactam ring, thereby affecting the antimicrobial activity of the antibiotic. Diluents containing calcium are not used to reconstitute ceftriaxone, and it must not be administered in intravenous lines containing other calcium-containing solutions, as a ceftriaxone-calcium precipitate could form. This precipitation risk is particularly high in newborns (up to age 28 days), especially if they are premature or have impaired bilirubin binding. Beyond the approved intramuscular and intravenous routes, ceftriaxone has also been administered off-label via the subcutaneous route. This practice has been reported in multiple clinical series, particularly in elderly, frail, or palliative-care patients and in those with difficult venous access. Pharmacokinetic data and clinical observations suggest that subcutaneous ceftriaxone provides adequate systemic exposure and is generally well tolerated, with reported clinical effectiveness comparable to intravenous administration in selected, non–critically ill patients.
In cellular migration, an integral aspect of inflammatory responses, the inhibition of GSK-3 has been reported to play conflicting roles, as local inhibition at growth cones has been shown to promote motility while global inhibition of cellular GSK-3 has been shown to inhibit cell spreading and migration. GSK-3 is also integrally tied to pathways of cell proliferation and apoptosis. GSK-3 has been shown to phosphorylate Beta-catenin, thus targeting it for degradation. GSK-3 is therefore a part of the canonical Beta-catenin/Wnt pathway, which signals the cell to divide and proliferate. GSK-3 phosphorylates cyclins D and E, which are important for the transition from G1 to S phase, and causes their degradation. The transcription factors c-myc and c-fos (also S phase promoters ), which are primarily phosphorylated by the dual-specificity tyrosine phosphorylation-regulated kinase, are also phosphorylated by GSK3, causing them to be degraded. GSK-3 also participates in a number of apoptotic signaling pathways by phosphorylating transcription factors that regulate apoptosis. GSK-3 can promote apoptosis by both activating pro-apoptotic factors such as p53 and inactivating survival-promoting factors through phosphorylation. The role of GSK-3 in regulating apoptosis is controversial, however, as some studies have shown that GSK-3β knockout mice are overly sensitized to apoptosis and die in the embryonic stage, while others have shown that overexpression of GSK-3 can induce apoptosis.
The Serbian Revolution coincided with the Russo-Turkish War (1806–1812) (in which the French diplomat, Horace François Bastien Sébastiani de La Porta played a very important role in provoking the war), which were a proxy conflict of the Coalition Wars, having most of the time Serbs revolutionaries the support of the Russian Empire, while the Ottoman Empire was an ally of the French Empire. This was due to the fact that both empires feared Napoleon's moves to the east as the subsequent Peace of Pressburg brought France into Balkan affairs. The most radical and liberal rebels were also inspired in some way by the French Revolution (specially the rise of nationalism) and the autonomy of the Illyrian Provinces (Serbs initially felt that French presence in the region could have developed into military aid in support of the insurrection against Ottoman rule as a sister republic, but Napoleon didn't want to increase Russian or Austrian influence in the region).
Sources: en.wikipedia.org
== Identification == Burkholderia pseudomallei is not fastidious and grows on a large variety of culture media (blood agar, MacConkey agar, EMB, etc.). Ashdown's medium (or Burkholderia cepacia medium) may be used for selective isolation. Cultures typically become positive in 24 to 48 hours (this rapid growth rate differentiates the organism from B. mallei, which typically takes a minimum of 72 hours to grow). Colonies are wrinkled, have a metallic appearance, and possess an earthy odor. On Gram staining, the organism is a Gram-negative rod with a characteristic "safety pin" appearance (bipolar staining). On sensitivity testing, the organism appears highly resistant (it is innately resistant to many antibiotics including colistin and gentamicin) and that again differentiates it from B. mallei, which is in contrast, exquisitely sensitive to many antibiotics. For environmental specimens only, differentiation from the nonpathogenic B. thailandensis using an arabinose test is necessary (B. thailandensis is never isolated from clinical specimens). The laboratory identification of B. pseudomallei has been described in the literature. The classic textbook description of B. pseudomallei in clinical samples is of an intracellular, bipolar-staining, Gram-negative rod, but this is of little value in identifying the organism from clinical samples. Some suggest the Wayson stain is useful for this purpose, but this has been shown not to be the case. Laboratory identification of B. pseudomallei can be difficult, especially in Western countries where it is rarely seen.
== Life == Kleinman received a B.S. in chemistry from Simmons College in 1969 and a M.S. and Ph.D. from the Massachusetts Institute of Technology in 1973. She did postdoctoral training at Tufts University. Kleinman worked at National Institutes of Health (NIH) from 1975 to 2006 in the National Institute of Dental and Craniofacial Research (NIDCR) and served as Chief of the Cell Biology Section in NIDCR's Laboratory of Cell and Developmental Biology (1985–2006). Her laboratory was the first to report the wound-healing effects of thymosin beta 4 (TB4), a synthetic version of a naturally occurring molecule. Her research accomplishments also include defining various angiogenic and antiangiogenic molecules and identifying sites on laminin for adhesion, migration, neurite outgrowth, angiogenesis, metastases and inhibition of metastases, and the respective receptors. Kleinman is a co-inventor of Matrigel. In 1992, during his first week as deputy director for intramural research, Lance Liotta appointed Kleinman to chair the new intramural women scientists' task force to investigate impediments to the advancement of women at NIH. She has received numerous awards for her research and for her efforts on behalf of women scientists. She has obtained multiple patents, many of which have been commercialized and one of which is in pivotal clinical trials. In 2006, she left the NIH to join the George Washington University as an adjunct professor in the department of biochemistry and molecular biology. She has subsequently consulted for various pharmaceutical companies Kleinman is Jewish.
=== Topical === The topical form of eflornithine is sold under the brand name Vaniqa. The most frequently reported side effect is acne (7–14%). Other side effects commonly (> 1%) reported are skin problems, such as skin reactions from in-growing hair, hair loss, burning, stinging or tingling sensations, dry skin, itching, redness or rash.
=== Health === On September 1, 2019, Hart was a passenger in a 1970 Plymouth Barracuda that went off Mulholland Highway and rolled down an embankment near Calabasas, California. He and the driver reportedly suffered "major back injuries". Hart was released from a hospital 10 days later, and continued recovery at a rehabilitation facility. On August 23, 2023, Hart ran a 40-yard race with former National Football League running back Stevan Ridley, and tore his lower abductors on his abdomen. He required a wheelchair as part of his recovery and said afterward he is the "dumbest man alive" and "the age 40 is real", recommending no one attempt to race like he did.
On 9 November 1918, Philipp Scheidemann, a Social Democrat, proclaimed the German Republic, marking Germany's transition to a federal democratic state. Germany's new leadership signed the Treaty of Versailles in 1919, accepting defeat by the Allies. Germans perceived the treaty as humiliating, which was seen by historians as influential in the rise of Adolf Hitler. Germany lost around 13% of its European territory and ceded all of its colonial possessions. On 11 August 1919, President Friedrich Ebert signed the democratic Weimar Constitution. Communists briefly seized power in Bavaria and a few larger cities, while conservative elements failed to overthrow the central government in the 1920 Kapp Putsch. The occupation of the Ruhr by Belgian and French troops and a period of hyperinflation followed. A plan to restructure Germany's war reparations and the creation of a new currency in 1924 helped stabilise the government and ushered in the Golden Twenties, an era of artistic innovation and liberal cultural life. In 1929, the Great Depression hit Germany, and by 1932 the unemployment rate had risen to nearly 30%. The Nazi Party led by Adolf Hitler became the largest party in the Reichstag after the election of July 1932, and President Hindenburg appointed Hitler as chancellor on 30 January 1933. After the Reichstag fire, a decree abrogated basic civil rights, and the first Nazi concentration camp opened. On 23 March 1933, the Enabling Act gave Hitler unrestricted legislative power, overriding the constitution, and marked the beginning of Nazi Germany.
Sources: en.wikipedia.org
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.
It corresponds to the actin-binding region of thymosin beta-4. Commercial synthesis reproduces that seven-residue stretch, usually with an acetyl group on the N-terminus.
It is not authorised as a medicine in the United States or the European Union and is distributed as a research chemical. Labels consequently carry research-use-only statements rather than clinical indications.
No. TB-500 is a trade-style label used for a synthetic peptide described as a fragment of thymosin beta-4, while thymosin beta-4 is the full 43-residue protein. The two differ in size and are not interchangeable terms in analytical work.