TB-500 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 2026-07-26. Where a claim depends on a specific study, the study is described rather than over-claimed.
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 usually assessed by reversed-phase high-performance liquid chromatography together with mass spectrometry. The chromatogram provides a purity estimate as a percentage of total peak area, while the mass spectrum confirms that the observed mass matches the expected value. Amino acid analysis or tandem mass spectrometry sequencing can provide additional confirmation. Reported purity figures depend on the column, gradient, and detection wavelength, so values from different laboratories are not directly comparable without method details.
Lyophilised peptide is normally reconstituted with sterile water or a neutral buffer shortly before use. Because repeated freeze-thaw cycles can degrade the material, dividing a reconstituted solution into single-use aliquots is a common practice. Working solutions are usually kept cold and protected from light. The exact shelf life depends on concentration, buffer composition, and handling, so it is often determined empirically rather than assumed.
| Property | Value | Notes |
|---|---|---|
| Molecular class | Synthetic peptide | N-terminal fragment of thymosin beta-4 |
| Residue count | Seven | Sequence LKKTETQ |
| Approximate mass | 889 Da | Acetylated seven-residue peptide |
| Common synonyms | TB4 fragment, TB500 | Not identical to full-length TB4 |
| Reported activity | Actin binding | Observed mainly in cell-free systems |
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.
Published research on the intact protein is substantial, covering actin regulation, cell migration, and wound models. Research using the heptapeptide fragment specifically is far smaller, and much of the circulating material originates in supplier documentation rather than peer-reviewed reports. Where fragment studies do exist, they often employ different sequences, chain lengths, or terminal modifications, which complicates direct comparison across papers. Readers encountering claims about TB-500 should therefore separate evidence about thymosin beta-4 from evidence about the fragment itself.
Discussion of the compound frequently appears alongside other short peptides described as fragments of larger proteins. That grouping is convenient but can be misleading, because fragment length, charge, and modification state determine how a peptide behaves in solution and in any experimental system. A seven-residue acetylated peptide and a full-length protein differ in mass by roughly an order of magnitude, and they cannot be assumed to share distribution or binding properties. Precision about which molecule is under discussion is the single most useful step when reading such material.
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.
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.
The designation TB-500 circulates in laboratory and catalog contexts without a single agreed definition. Most product listings apply it to an N-terminally acetylated seven-residue fragment of thymosin beta-4, while other listings attach the same label to the full 43-residue protein. Because the term is commercial rather than systematic, two entries bearing identical names may describe different molecules. Any documentation should therefore state which sequence a given sample is claimed to contain.
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.
Upon his return from the U.S., Janež introduced the insulin pump method into clinical practice of treating adult patients with type 1 diabetes in Slovenia. Together with his colleagues from the Department of Endocrinology, Diabetes, and Metabolic Disease at University Medical Centre Ljubljana, Janež co-authored the algorithm used in insulin pump treatment, as well as tutored virtually all Slovenian diabetologists in usage of both insulin pump and glucose sensor. Janež also wrote all of the literature on subjects of functional insulin therapy and insulin pump in Slovenia, with its audiences ranging from diabetologists to patients. In 2008, he established a new unit for functional insulin therapy within the University Medical Centre. Janež also led the effort of forming international standards for interpretation of results obtained with glucose sensor, publishing and presenting these on several international diabetes-related symposiums. Coupled with his previous work in the field of functional insulin therapy and its pilot implementation in Slovenia, Janež went on to introduce this approach to diabetes treatment in other countries.
== Formulation == Ampicillin-sulbactam only comes in a parenteral formulation to be either used as intravenous or intramuscular injections, and can be formulated for intravenous infusion. It is formulated in a 2:1 ratio of ampicillin:sulbactam. The commercial preparations available include:
Beyond their utility as research tools, BioRNA agents have been applied to miRNA replacement therapy, a strategy that seeks to reintroduce tumor-suppressive miRNAs depleted in disease tissue to harness endogenous RNAi machinery for treatment. In preclinical cancer models, bioengineered miRNA agents have demonstrated antitumor activity, the ability to suppress multidrug resistance by downregulating efflux transporter expression, and pharmacological synergism with co-administered chemotherapeutic drugs—providing a mechanistic rationale for their development as combination therapeutics.
Letrozole and anastrozole are aromatase inhibitors which have been shown to be superior to tamoxifen for the first-line treatment of breast cancer in postmenopausal women. Exemestane is an irreversible "aromatase inactivator" which is superior to megestrol acetate for treatment of tamoxifen-refractory metastatic breast cancer, and does not appear to have the osteoporosis-promoting side effects of other drugs in this class. Aminoglutethimide inhibits both aromatase and other enzymes critical for steroid hormone synthesis in the adrenal glands. It was formerly used for breast cancer treatment, but has since been replaced by more selective aromatase inhibitors. It can also be used for the treatment of hyperadrenocortical syndromes, such as Cushing's syndrome and hyperaldosteronism in adrenocortical carcinoma.
=== Committee === WOSM's committee is its executive governing body, composed of elected volunteers and its secretary general, which is responsible for the implementation of the resolutions of its conference and governs the organization between meetings of its conference. The committee meets at least twice a year. Its steering committee, consisting of the chairperson, two vice-chairpersons and its youth advisor and secretary general meet as needed. The committee has 21 members. Twelve, each from a different country, are elected for three-year terms by WOSM's conference. The members, elected without regard to their nationality, represent the interests of the movement as a whole, not those of their country. The secretary general, the treasurer of WOSM and a representative member of the board of the World Scout Foundation and the chairpersons of the regional Scout committees are ex-officio members of the committee. From 2008 to 2021 six Youth Advisors to the WSC were elected by the World Scout Youth Forum. The Youth Advisors participated in all of the WSC meetings and were also part of the governing structure between the meetings. There will be no Youth Advisors from 2024. The 2021–2024 committee set up work streams to address the top strategic priorities, as defined by WOSM's conference. Task forces include:
Sources: en.wikipedia.org
Kenyon cells synapse onto output neurons of the mushroom body, which then are thought to control stereotyped behaviors. The intracellular signaling cAMP-dependent pathways operate at Kenyon cell-to-mushroom body output neurons to depress the strength of the KC input to MBONs, thus changing the behavior evoked by the stimulus.
In 2019, Dream Market was the most popular market by far, with over 120,000 current trade listings, followed at one time by Wall Street Market with under 10,000 listings. Dream Market was shut down in 2019, and Wall Street Market was seized by law enforcement in May 2019 as part of an Internal Law Enforcement Operation Dark Huntor. That same operation also shut down the dark markets DeepSea, Berlusconi, White House, and Dark Market. The May 2019 seizure of news and links site DeepDotWeb for conspiring with the markets created a temporary disruption around market navigation. In 2021, authorities took down the dark web marketplace DarkMarket, along with arresting the Australian man who was believed to be the operator of the website. The 20 servers that hosted the website were seized. In August 2021, AlphaBay was relaunched after the return of one of the original security administrators DeSnake. In June 2025, Europol took down the Archetyp Market with an estimated 3200 registered vendors and 600,000 customers worldwide.
As described by Jeong et al., compared with other do novo peptide sequencing tools, which works well on only certain types of spectra, UniNovo is a more universal tool that has a good performance on various types of spectra or spectral pairs like CID, ETD, HCD, CID/ETD, etc. It has a better accuracy than PepNovo+ or PEAKS. Moreover, it generates the error rate of the reported peptide sequences. Ma published Novor in 2015 as a real-time de novo peptide sequencing engine. The tool is sought to improve the de novo speed by an order of magnitude and retain similar accuracy as other de novo tools in the market. On a Macbook Pro laptop, Novor has achieved more than 300 MS/MS spectra per second. Pevtsov et al. compared the performance of the above five de novo sequencing algorithms: AUDENS, Lutefisk, NovoHMM, PepNovo, and PEAKS . QSTAR and LCQ mass spectrometer data were employed in the analysis, and evaluated by relative sequence distance (RSD) value, which was the similarity between de novo peptide sequencing and true peptide sequence calculated by a dynamic programming method. Results showed that all algorithms had better performance in QSTAR data than on LCQ data, while PEAKS as the best had a success rate of 49.7% in QSTAR data, and NovoHMM as the best had a success rate of 18.3% in LCQ data. The performance order in QSTAR data was PEAKS > Lutefisk, PepNovo > AUDENS, NovoHMM, and in LCQ data was NovoHMM > PepNovo, PEAKS > Lutefisk > AUDENS. Compared in a range of spectrum quality, PEAKS and NovoHMM also showed the best performance in both data among all 5 algorithms.
At least one person has been killed by carbon dioxide gas subliming off dry ice in coolers placed in a car. In 2020, three people were killed at a party in Moscow after 25 kg of dry ice was dumped in a pool; carbon dioxide is heavier than air, and so can linger near the ground, just above water level.
Sources: en.wikipedia.org
== Drug pricing issue and exit in the Swiss market == In July 2025, Roche withdrew Lunsumio from the Swiss market following failed price negotiations with the Swiss Federal Office of Public Health (BAG). The drug had been available since February 2023 through a special "Early Access" program that allowed reimbursement before complete clinical data was available. Under this arrangement, Roche initially covered treatment costs until efficacy was demonstrated, after which the remaining therapy could exceed 100,000 Swiss francs. When Swissmedic extended the temporary authorization in February 2025 due to still-missing complete clinical data from Phase III studies, Roche rejected the previously negotiated pricing model and demanded higher prices. The BAG refused to modify the agreement, citing concerns that exceptions would set a precedent for other pharmaceutical companies and demanding additional efficacy evidence despite the drug showing positive effects in Phase II studies. According to Swissmedic pricing data, a single 60-mg dose (two vials) of Lunsumio costs over 7,000 Swiss francs. The withdrawal was announced to oncologists on July 1, 2025, affecting approximately 24 patients annually who suffer from follicular lymphoma—a slowly progressing cancer of the lymph nodes with about 500 new cases per year in Switzerland. Roche also refused to provide individual case reimbursements—a standard Swiss mechanism for exceptional medical situations.
=== Post-translational modification === Additionally, the protein can undergo a variety of post-translational modifications, which are briefly summarized here. The N-terminal amino group of a polypeptide can be modified covalently, e.g.,
Some colorless compounds such as proteins can be quantified at an Optical Density of 280 nm due to the presence of aromatic rings such as tryptophan, tyrosine and phenylalanine but if none of these amino acids are present then the absorption cannot be measured at 280 nm.
==== Platelet-type ==== Platelet-type VWD (also known as pseudo-VWD) is an autosomal dominant genetic defect of the platelets. The VWF is qualitatively normal and genetic testing of the von Willebrand gene and VWF protein reveals no mutational alteration. The defect lies in the qualitatively altered GPIb receptor on the platelet membrane which increases its affinity to bind to the VWF. Large platelet aggregates and high molecular weight VWF multimers are removed from the circulation resulting in thrombocytopenia and diminished or absent large VWF multimers. The ristocetin cofactor activity and loss of large VWF multimers are similar to VWD type 2B.
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Sources: en.wikipedia.org
No. Thymosin beta-4 is a 43-residue protein, while TB-500 refers to a seven-residue fragment corresponding to its N-terminal region. The two names are often used loosely in commercial and community writing, which obscures the difference in size, sequence, and likely behavior.
The fragment contains an actin-binding motif, and cell-free experiments show that it can interact with monomeric actin. That observation is the basis for interest in cell migration and repair processes. Effects reported in animals are not established for humans.
Purity is usually stated by the supplier rather than fixed by a pharmacopoeial monograph, and typical listings report a percentage from reverse-phase HPLC. Independent verification is uncommon. Because no single accepted specification exists, comparisons between lots and between suppliers are difficult.
The lyophilised powder is typically held at -20 C or lower in a dry, dark place. Reconstituted solutions are aliquoted and frozen to avoid repeated freeze-thaw cycles.