If you have been reading about reversed-phase HPLC and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Updated 2025-10-06. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
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.
| 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 |
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.
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.
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.
Storage recommendations center on keeping the dry powder cold, dry, and dark. A freezer at -20 degrees Celsius or below is conventional, and desiccant is often included to limit moisture uptake. Once dissolved, the peptide is less stable, and solutions are typically kept frozen and thawed only once. Repeated freeze-thaw cycles are a common source of losses because they promote aggregation and adsorption to container surfaces. Working aliquots are therefore prepared in advance, and glass or low-binding plastic is usually preferred over ordinary laboratory plastic.
Identity and purity are assessed with a small set of standard techniques. Reverse-phase high-performance liquid chromatography gives a purity estimate from peak area, usually recorded at 214 or 220 nanometers, where the peptide bond absorbs. Mass spectrometry confirms the expected molecular mass and can reveal truncated or oxidized species. Amino acid analysis or tandem mass spectrometry sequencing can verify the sequence itself. Additional quality attributes include water content, residual trifluoroacetic acid carried over from purification, and endotoxin where the material is intended for biological work.
Controlled human trials of the short fragment are scarce. Much of what appears in review articles is extrapolated from animal models or from studies of the parent protein, and literature searches return a larger body of cardiac and ophthalmic work on thymosin beta-4 than on the abbreviated peptide. Regulatory treatment differs by jurisdiction, and in several countries the material is handled as a research chemical rather than an approved therapeutic. Statements about human benefit should be read as provisional.
Biological interest in this peptide centers on its relationship to actin dynamics. Thymosin beta-4 binds monomeric actin through an LKKTET motif, and a short sequence carrying that motif can compete with other actin-binding proteins in cell-free preparations. Investigators propose that such competition shifts the balance between filament assembly and disassembly, which in turn affects how readily a cell extends protrusions and migrates. Most of the supporting observations come from cultured cells and purified protein systems rather than from intact organisms.
==== Schirmer test ==== Schirmer's test measures the production of tears: a strip of filter paper is held inside the lower eyelid for five minutes, and its wetness is then measured with a ruler. Producing less than 5 mm (0.20 in) of liquid is usually indicative of Sjögren's. This measurement analysis varies among people depending on other eye-related conditions and medications in use when the test is taken. A slit-lamp examination can reveal dryness on the surface of the eye. Schirmer strips can be used to test oral dryness.
Cancer that has spread to other parts of the body is usually treated also with hormone therapy, to deprive a tumour of sex hormones (androgens) that stimulate proliferation. This is often done through the use of GnRH analogues or agents (such as bicalutamide) that block the receptors that androgens act on; occasionally, surgical removal of the testes may be done instead. Cancer that does not respond to hormonal treatment, or that progresses after treatment, might be treated with chemotherapy such as docetaxel. Radiotherapy may also be used to help with pain associated with bony lesions. Sometimes, the decision may be made not to treat prostate cancer. If a cancer is small and localised, the decision may be made to monitor for cancer activity at intervals ("active surveillance") and defer treatment. If a person, because of frailty or other medical conditions or reasons, has a life expectancy less than ten years, then the impacts of treatment may outweigh any perceived benefits.
== History == Vertex Pharmaceuticals announced in January 2024 that suzetrigine had successfully met several endpoints in its phase III clinical trials. The company announced in July 2024 that the US Food and Drug Administration (FDA) had accepted a New Drug Application for suzetrigine. Due to its novel mechanism, the FDA granted priority review, fast track, and breakthrough therapy designations to the application for suzetrigine. In January 2025, the FDA granted approval of Journavx to Vertex Pharmaceuticals, making it the first non-opioid pain medication to be approved by the FDA in two decades. As of November 2025, phase IV post-marketing clinical trials are underway to assess the effectiveness and safety of suzetrigine as a part of multimodal therapy for the treatment of acute post-operative pain. The manufacturer engaged in lobbying activity promoting non-opioid pain treatment and supporting the NO PAIN Act (Non-Opioids Prevent Addiction In the Nation Act).
Calcium aluminate cements were patented in 1908 in France by Jules Bied for better resistance to sulfates. Also in 1908, Thomas Edison experimented with pre-cast concrete in houses in Union, N.J. In the US, after World War One, the long curing time of at least a month for Rosendale cement made it unpopular for constructing highways and bridges, and many states and construction firms turned to Portland cement. Because of the switch to Portland cement, by the end of the 1920s only one of the 15 Rosendale cement companies had survived. But in the early 1930s, builders discovered that, while Portland cement set faster, it was not as durable, especially for highways—to the point that some states stopped building highways and roads with cement. Bertrain H. Wait, an engineer whose company had helped construct the New York City's Catskill Aqueduct, was impressed with the durability of Rosendale cement, and came up with a blend of both Rosendale and Portland cements that had the good attributes of both. It was highly durable and had a much faster setting time. Wait convinced the New York Commissioner of Highways to construct an experimental section of highway near New Paltz, New York, using one sack of Rosendale to six sacks of Portland cement. It was a success, and for decades the Rosendale-Portland cement blend was used in concrete highway and concrete bridge construction. Cementitious materials have been used as a nuclear waste immobilizing matrix for more than a half-century.
=== Academic career === Bumpus became a Professor of Medicine in the clinical pharmacology division of Johns Hopkins University School of Medicine, with a secondary appointment in the Department of Pharmacology and Molecular Sciences. She started her own laboratory at Johns Hopkins School of Medicine in 2010 as an Assistant Professor of Medicine and Pharmacology, was promoted to Associate Professor in February 2015, and received Professorship in 2020. Bumpus is known for her research on the metabolism of antiviral drugs used to treat HIV-1 and how genetic variations in drug-processing enzymes may impact these drugs' efficacy. She became Hopkins’ inaugural associate dean of institutional and student equity in 2015 and instituted mentoring programs to expand access to resources and opportunities. After holding that role for two years, in July 2017 she transitioned into a role as senior consulting strategist for Academic and Research Diversity, working with the chief diversity officer to develop and implement diversity and inclusion programs across Johns Hopkins School of Medicine. Bumpus received a Presidential Early Career Award for Scientists and Engineers in 2016. In July 2018, she was named as Associate Dean for Basic Research at Johns Hopkins University School of Medicine.
Sources: en.wikipedia.org
According to Historian of Art Benjamin Rowland, the portraits in Kizil show "that the Tocharians were European rather than Mongol in appearance, with light complexions, blue eyes, and blond or reddish hair, and the costumes of the knights and their ladies have haunting suggestions of the chivalric age of the West". The Chinese named Kuchean kings by adding the prefix "白", meaning "white", probably pointing to the fair complexion of the Kucheans. The Chinese Monk Xuanzang in 645 CE, noted that "they clothe themselves with ornamented garments of silk and embroidery". This cave also shows Central Asian traders encountering various dangers on their way, such as being lost in the dark, and being saved by the Dragon-King Mabi. Another is the story of the good merchant Sabu (萨缚), who, in order to show the way to a party of 500 merchants lost in the darkness, puts his own arms on fire to use them as torches, and successfully rescues them. The story appears in numerous paintings, in which the merchants are in Central Asian garb and accompanied by camels, and Sab has the attributes of a Bodhisattva. Cave 17 is contemporary with the earliest decorated Mogao Caves near Dunhuang (caves 268, 272 and 275), which were built and decorated by the Northern Liang between 419 and 439 CE, before the invasion of the Northern Wei. They have many stylistic characteristics in common.
ATC code H01 Pituitary and hypothalamic hormones and analogues is a therapeutic subgroup of the Anatomical Therapeutic Chemical Classification System, a system of alphanumeric codes developed by the World Health Organization (WHO) for the classification of drugs and other medical products. Subgroup H01 is part of the anatomical group H Systemic hormonal preparations, excluding sex hormones and insulins. Codes for veterinary use (ATCvet codes) can be created by placing the letter Q in front of the human ATC code: for example, QH01. ATCvet codes without corresponding human ATC codes are cited with the leading Q in the following list.National versions of the ATC classification may include additional codes not present in this list, which follows the WHO version. H01AA01 Corticotropin H01AA02 Tetracosactide H01AB01 Thyrotropin alfa H01AC01 Somatropin H01AC02 Somatrem H01AC03 Mecasermin H01AC04 Sermorelin H01AC05 Mecasermin rinfabate H01AC06 Tesamorelin H01AC07 Somapacitan H01AC08 Somatrogon H01AC09 Lonapegsomatropin H01AX01 Pegvisomant QH01AX90 Capromorelin
There are three known stable isotopes of oxygen (8O): 16O, 17O, and 18O. Radioisotopes are known from 11O to 28O (particle-bound from mass number 13 to 24), and the most stable are 15O with half-life 122.27 seconds and 14O with half-life 70.62 seconds. All remaining radioisotopes are even shorter in lifetime. The four heaviest known isotopes (up to 28O) decay by neutron emission to 24O, whose half-life is 77 milliseconds; 24O, along with 28Ne, have been used in the model of reactions in the crust of neutron stars. The most common decay mode for isotopes lighter than the stable isotopes is β+ decay to nitrogen, and the most common mode after is β− decay to fluorine.
== Signaling == Activation of the adenosine A1 receptor by an agonist causes binding of Gi1/2/3 or Go protein. Binding of Gi1/2/3 causes an inhibition of adenylate cyclase and, therefore, a decrease in the cAMP concentration. An increase of the inositol triphosphate/diacylglycerol concentration is caused by an activation of phospholipase C, whereas the elevated levels of arachidonic acid are mediated by DAG lipase, which cleaves DAG to form arachidonic acid. Several types of potassium channels are activated but N-, P-, and Q-type calcium channels are inhibited.
Sources: en.wikipedia.org
=== Component of gasoline === As a gasoline (petrol) additive, benzene increases the octane rating and reduces knocking. As a consequence, gasoline often contained several percent benzene before the 1950s, when tetraethyl lead replaced it as the most widely used antiknock additive. With the global phaseout of leaded gasoline in the 1970s–1990s, benzene reappeared as a gasoline additive, although strictly limited in most nations. For example, in the United States, concern over its negative health effects and the possibility of benzene entering the groundwater has led to stringent regulation of gasoline's benzene content, with limits typically around 1%. European petrol specifications now contain the same 1% limit on benzene content. The United States Environmental Protection Agency introduced new regulations in 2011 that lowered the benzene content in gasoline to 0.62%. In some European languages, the word for petroleum or gasoline is an exact cognate of "benzene". For instance all Germanic languages and Scandinavian languages refer to gasoline as 'bensin' or 'benzin'. In Turkish and many Turkic languages the word of 'benzin' is used to refer the gasoline. In Catalan and Italian the word 'benzina' can be used for gasoline. In both Polish and Greek the word 'benzyna' is also used to mean gasoline or petrol.
=== Parkinson's === Similar to Alzheimer's, Parkinson's is the most common neurodegenerative disease associated with balance and coordination issues, muscle stiffness, and tremors. During the early 1800s, James Parkinson medically defined this disease. A study observed improvement in locomotor abilities in rats with Parkinson's after intranasal delivery of conjugated mitochondrial systems. Another study demonstrated delivery of neuroactive drugs in a hydrogel increased residence times in the nasal cavity and concentration in the brain. Administering therapeutics combined with nanocarriers is shown to directly transfer drugs to the target cells and enhance accumulation. The observed effects include improved neuronal signaling and locomotion. Furthermore, intranasal delivery of biodegradable nanoparticles surface-modified with lactoferrin increase accumulation in the brain and cellular uptake.
== Structure == Microproteins generally feature a single protein domain. The active form is translated from smORF. smORFs can be less than 100 codons. However, not all microproteins are small, and the name was given because of the analogy to miRNAs. Despite their short length, microproteins have been shown to a limited but diverse set of structural folds (including predominantly α-helical and transmembrane-helical structures), but many candidates also show substantial intrinsic disorder; experimentally determined microprotein structures have been solved using approaches including X-ray crystallography, cryo-electron microscopy, and NMR. A computational survey of predicted structures for 44 microproteins reported broadly similar structural characteristics across the set and comparatively few predicted small-molecule ligand-binding sites. Because many structure/disorder predictors are trained primarily on longer “classical” proteins, dedicated workflows and precautions have been proposed for reliable structure and disorder prediction for microproteins.
=== Absorption === The oral bioavailability of CPA is 68 to 100%. The absorption of oral CPA is slow but complete, and the medication is not subject to a significant first-pass effect. The mean absorption half-life of oral CPA is about 1.5 hours. Steady-state levels of CPA occur with oral CPA after about 8 days of continuous administration, with a 2- to 3-fold gradual accumulation in CPA levels. Oral CPA is taken daily and intramuscular CPA is administered weekly or biweekly. Following a single low oral dose of 2 mg CPA in combination with 35 or 50 μg ethinylestradiol in premenopausal women, mean peak levels of CPA of 7.2 to 15.2 ng/mL (17–36.5 nmol/L) have been recorded after 1.6 to 3.7 hours. In healthy men, a single high oral dose of 100 mg CPA produced maximal CPA levels of 254 ng/mL (609 nmol/L) after 2.6 hours. In aged men with prostate cancer, continuous oral CPA therapy resulted in CPA levels of 132 ± 18 ng/mL at 25 mg/day, 246 ± 13 ng/mL at 50 mg/day, and 348 ± 23 ng/mL at 100 mg/day. Similarly, in healthy young women, a single high oral dose of 100 mg CPA resulted in peak CPA levels of 255 ng/mL (612 nmol/L) within 2 to 3 hours. During continuous treatment with high oral doses of CPA in women with hirsutism, levels of CPA were 199 to 228 ng/mL (477–547 nmol/L) with 50 mg/day CPA and were 436 to 520 ng/mL (1050–1250 nmol/L) with 100 mg/day CPA. After a single intramuscular injection of 300 mg CPA in healthy young women, maximal levels of CPA of 191 ng/mL (458 nmol/L) and of 15β-OH-CPA of 164 ng/mL occurred after 2 to 4 days.
21 July: Health Minister Simeon Brown announces that the New Zealand Government will contribute NZ$82.5 million to the establishment of the University of Waikato's medical school; with the university and private philanthropists contributing the remaining NZ$150 million. The Commerce Commission files criminal charges against electronics retailer Noel Leeming for alleged breaches of the Fair Trading Act 1986. The Gore District Council lifts its "do not drink tap water" directive for Gore. 22 July: Sky TV buys TV3 for a symbolic $1; marking the exit of Warner Bros. Discovery from New Zealand's free-to-air television space. The sale comes into effect on 1 August. New Zealand joins 24 other countries including Australia, the United Kingdom, Canada, Japan and the European Union in issuing a joint statement calling for the Gaza war to end. Representatives of several Jewish and Muslim community groups including the New Zealand Jewish Council and the Federation of Islamic Associations of New Zealand (FIANZ) sign a "harmony and peace accord" to improve interfaith relations amidst the Gaza war. 24 July — The primary school teachers' union, the New Zealand Educational Institute, files for a judicial review at the Wellington High Court of the New Zealand Government's decision to reduce funding for literacy and Māori resource teachers during the 2025 New Zealand budget, which was released in May 2025. 30 July: 36,000 nurses, midwives, and other health workers affiliated with the New Zealand Nurses Organisation strike to protest unsafe staffing levels at Te Whatu Ora facilities.
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.
Divide it into single-use aliquots and hold them frozen at -20 °C or below, protected from light. Repeated thawing of one container is the main avoidable source of variability.