The short version of wound model fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2025-09-03 and is reviewed periodically as new material appears.
Regulatory status differs by country, but TB-500 is not an approved pharmaceutical in major jurisdictions. It is commonly sold as a research chemical for laboratory use, which places responsibility for identity and purity on the supplier and the laboratory. Published human data are limited, and most reports involve preclinical models or cell culture. Questions about whether the fragment mimics all actions of thymosin beta-4, and under which conditions, remain open. Independent verification of any material is therefore a practical requirement in research settings.
TB-500 is a synthetic heptapeptide with the sequence Ac-LKKTETQ. It corresponds to a short N-terminal region of thymosin beta-4, a 43-amino-acid protein found in many cell types. The fragment contains an actin-binding motif, which is one reason it appears in laboratory studies of cell migration and cytoskeletal dynamics. TB-500 is not the full-length protein and is produced as a research chemical rather than an approved therapeutic agent. Its molecular weight is approximately 889 Da.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C38H68N10O14 | Calculated for the acetylated heptapeptide |
| Molecular weight | ~889 Da | Monoisotopic mass approximately 889.0 Da |
| Amino acid sequence | Ac-LKKTETQ | N-terminal acetylated seven-residue peptide |
| Appearance | White to off-white powder | Typically supplied as a lyophilized solid |
| Solubility class | Water-soluble | Peptides of this size generally dissolve in aqueous media |
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.
Dry peptide powder is commonly kept at −20 °C in a desiccated container away from light, a practice that limits moisture uptake and oxidation. Once dissolved, solutions are generally held at 2–8 °C for short periods or frozen at −20 °C or lower for longer storage, with repeated freeze-thaw cycles avoided. Hydrolysis and oxidation are the main degradation routes for peptides in solution, and both accelerate at higher temperature or extreme pH. Published stability data specific to TB-500 are limited, so shelf life should be treated as uncertain.
Identity and purity checks for peptide material typically combine reversed-phase high-performance liquid chromatography with mass measurement, since retention time alone cannot confirm a sequence. Mass measurement verifies the expected molecular mass within instrument tolerance, while chromatographic peak area provides a purity estimate. Anti-doping analysis of urine uses related but more sensitive workflows, sometimes after solid-phase extraction. For research material, batch documentation, certificate content, and independent testing are common points of scrutiny, because supply chains outside pharmaceutical regulation vary widely in the paperwork they provide.
Lyophilized TB-500 is hygroscopic and should be kept dry before use. The usual storage recommendation for the solid is -20 °C, protected from light and moisture. Once dissolved, the peptide is less stable, and repeated freeze-thaw cycles can promote aggregation or degradation. Laboratories often divide a reconstituted solution into single-use aliquots and store them at -80 °C. Exact stability limits depend on buffer, pH, and concentration, so published data do not define a single universal condition.
Identity and purity are checked with chromatographic and mass spectrometric methods. Reverse-phase high-performance liquid chromatography separates the peptide from related impurities, while mass spectrometry confirms the expected molecular mass. A certificate of analysis may report a purity percentage, but the laboratory should still verify the material independently. Common quality concerns include truncated sequences, deamidation, oxidation, and residual solvents from synthesis. Because TB-500 is short, some impurities can differ from the target by only a few mass units.
Animal work has examined the peptide in models of cardiac injury, skin wounding, and corneal repair, with reported outcomes covering cell migration, inflammatory cell influx, and tissue remodeling. Several of those experiments used the full-length protein or longer fragments instead of the seven-residue sequence, which makes direct comparison between reports difficult. Results are generally described as tissue-dependent, and effect sizes vary considerably across laboratories. Independent replication is uneven, so the overall picture is incomplete rather than settled.
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.
==== Auxiliary channel ==== The DisplayPort AUX channel is a half-duplex data channel used for miscellaneous additional data beyond video and audio, such as EDID (I2C) or CEC commands. This bidirectional data channel is required, since the video lane signals are unidirectional (simplex) from source to display. AUX signals are transmitted across a dedicated set of twisted-pair wires. DisplayPort 1.0 specified Manchester encoding with a 2 MBd signal rate (1 Mbit/s data rate). Version 1.2 of the DisplayPort standard introduced a second transmission mode called FAUX (Fast AUX), which operated at 720 Mbit/s with 8b/10b encoding (576 Mbit/s data rate), but it was deprecated in version 1.3.
The Stanley Infant & Junior School (IJS) is located along John Street at the intersection with Villiers Street in Stanley. The school first opened in 1955 and has about 250 students between the ages of four and 11. The Falkland Islands Community School (FICS) is located on Reservoir Road in Stanley. It has approximately 220 students between 11 and 16.
In biology, the most relevant forms of phase separation are either liquid–liquid or liquid–solid, although there have been reports of gas vesicles surrounded by a phase separated protein coat in the cytoplasm of some microorganisms.
== ISO 4500 - ISO 4999 == ISO 4548 Methods of test for full-flow lubricating oil filters for internal combustion engines ISO 4548-7:2012 Part 7: Vibration fatigue test ISO 4551:1987 Ferroalloys – Sampling and sieve analysis ISO 4552 Ferroalloys – Sampling and sample preparation for chemical analysis ISO 4552-1:1987 Part 1: Ferrochromium, ferrosilicochromium, ferrosilicon, ferrosilicomanganese, ferromanganese ISO 4552-2:1987 Part 2: Ferrotitanium, ferromolybdenum, ferrotungsten, ferroniobium, ferrovanadium ISO 4570 Tyre valve threads ISO 4578 Adhesives — Determination of peel resistance of high-strength adhesive bonds — Floating-roller method ISO 4582 Plastics — Determination of changes in colour and variations in properties after exposure to daylight under glass, natural weathering or laboratory light sources ISO 4587 Adhesives — Determination of tensile lap-shear strength of rigid-to-rigid bonded assemblies ISO 4618:2014 Paints and varnishes – Terms and definitions ISO 4628 Paints and varnishes – Evaluation of degradation of coatings – Designation of quantity and size of defects, and of intensity of uniform changes in appearance ISO 4628-1 General introduction and designation system ISO 4628-2 Assessment of degree of blistering ISO 4628-3 Assessment of degree of rusting ISO 4628-4 Assessment of degree of cracking ISO 4628-5 Assessment of degree of flaking ISO 4628-6 Assessment of degree of chalking by tape method ISO 4628-7 Assessment of degree of chalking by velvet method ISO 4628-8 Assessment of degree of delamination and corrosion around a scribe ISO 4628-10 Assessment of degree of filiform corrosion ISO 4648:1991 Rubber, vulcanized or thermoplastic — Determination of dimensions of test pieces and products for test purposes [Withdrawn: replaced with ISO 23529] ISO 4661 Rubber, vulcanized — Preparation of samples and test pieces ISO 4661-1:1993 Rubber, vulcanized or thermoplastic — Preparation of samples and test pieces — Part 1: Physical tests [Withdrawn: replaced with ISO 23529] ISO 4661-2:2018 Rubber, vulcanized — Preparation of samples and test pieces — Part 2: Chemical tests ISO 4683 Raw sheep skins ISO 4683-1:1998 Part 1: Descriptions of defects ISO 4720:2009 Essential oils – Nomenclature ISO 4730:2017 Essential oil of Melaleuca, terpinen-4-ol type (Tea Tree oil) ISO 4786:1977 Enclosed-scale adjustable-range thermometers [Withdrawn without replacement] ISO 4787:2010 Laboratory glassware – Volumetric instruments – Methods for testing of capacity and for use ISO 4788:2005 Laboratory glassware – Graduated measuring cylinders ISO 4791 Laboratory apparatus – Vocabulary relating to apparatus made essentially from glass, porcelain or vitreous silica ISO 4791-1:1985 Part 1: Names for items of apparatus ISO 4795:1996 Glass for thermometer bulbs ISO 4801:1979 Glass alcoholometers and alcohol hydrometers not incorporating a thermometer ISO 4805:1982 Laboratory glassware – Thermo-alcoholometers and alcohol-thermohydrometers ISO 4824:1993 Dentistry — Ceramic denture teeth [Withdrawn: replaced with ISO 22112] ISO 4831:2006 Microbiology of food and animal feeding stuffs – Horizontal method for the detection and enumeration of coliforms – Most probable number technique ISO 4832:2006 Microbiology of food and animal feeding stuffs – Horizontal method for the enumeration of coliforms – Colony-count technique ISO 4833 Microbiology of the food chain – Horizontal method for the enumeration of microorganisms ISO 4833-1:2013 Part 1: Colony count at 30 degrees C by the pour plate technique ISO 4833-2:2013 Part 2: Colony count at 30 degrees C by the surface plating technique ISO 4848:1980 Concrete — Determination of air content of freshly mixed concrete — Pressure method [Withdrawn: replaced with ISO 1920-2] ISO 4858:1982 Wood — Determination of volumetric shrinkage [Withdrawn: replaced with ISO 13061-14] ISO 4859:1982 Wood — Determination of radial and tangential swelling [Withdrawn: replaced with ISO 13061-15] ISO 4860:1982 Wood — Determination of volumetric swelling [Withdrawn: replaced with ISO 13061-16] ISO 4866:2010 Mechanical vibration and shock – Vibration of fixed structures – Guidelines for the measurement of vibrations and evaluation of their effects on structures ISO 4871:1996 Acoustics – Declaration and verification of noise emission values of machinery and equipment ISO/IEC 4873:1991 Information technology – ISO 8-bit code for information interchange – Structure and rules for implementation ISO 4875 Metal-cutting band saw blades ISO 4875-1:2006 Part 1: Vocabulary ISO 4880:1997 Burning behaviour of textiles and textile products – Vocabulary ISO 4882:1979 Office machines and data processing equipment – Line spacings and character spacings ISO 4885:2017 Ferrous materials – Heat treatments – Vocabulary ISO 4892 Plastics – Methods of exposure to laboratory light sources ISO 4902:1989 Information technology – Data communication – 37-pole DTE/DCE interface connector and contact number assignments ISO 4903:1989 Information technology – Data communication – 15-pole DTE/DCE interface connector and contact number assignments ISO/IEC 4909:2006 Identification cards – Financial transaction cards – Magnetic stripe data content for track 3 ISO 4921:2000 Knitting – Basic concepts – Vocabulary ISO/IEC 4922-1 Information security — Secure multiparty computation ISO/IEC 4922-1:2023 Part 1: General ISO 4977 Double cold-reduced electrolytic tinplate ISO 4977-1:1984 Part 1: Sheet [Withdrawn: replaced with ISO 11949] ISO 4977-2:1984 Part 2: Coil for subsequent cutting into sheets [Withdrawn: replaced with ISO 11949]
Sources: en.wikipedia.org
Norgestrienone, also known as 17α-ethynyl-19-nor-δ9,11-testosterone or as 17α-ethynylestra-4,9,11-trien-17β-ol-3-one, as well as δ9,11-norethisterone or 17α-ethynyltrienolone (17α-ethynyltrenbolone), is a synthetic estrane steroid and a derivative of testosterone and 19-nortestosterone. It is structurally related to the anabolic steroid trenbolone (19-nor-δ9,11-testosterone; the non-17α-ethynylated analogue of norgestrienone), the progestogenic and androgenic steroid gestrinone (the 13β-ethyl variant or 18-methyl derivative of norgestrienone), and the anabolic steroid tetrahydrogestrinone (the 18-methyl and 17α-ethyl variant of norgestrienone).
=== November === 9 November – Jozef Puška was convicted of the murder of Ashling Murphy. 12 November – Met Éireann issued a Status Red wind warning for 14 counties, ahead of Storm Debi warning of a "potential danger to life". 15 November – The Dáil voted 85–55 to reject a motion by the Social Democrats party to expel the Israeli Ambassador, Dana Erlich. A Sinn Féin party motion to refer Israel to the International Criminal Court because of its actions in Gaza was also defeated, 77–58. Social Democrats leader Holly Cairns argued during the debate that "Israel is killing with impunity. According to the World Health Organisation, Gaza is now a graveyard for children." She also stated, "Words of condemnation are not enough. We need action. There must be consequences for the crimes perpetrated by Israel on a captive civilian population in Gaza." Deputy James Browne (Fianna Fáil party) claimed in the debate that the Social Democrats' motion "seeks to push Ireland to the margins of international opinion". Meanwhile, a large crowd outside Leinster House called for the ambassador's expulsion. 17 November – Jozef Puška was sentenced to life imprisonment for the murder of Ashling Murphy. 18 November – Gardaí began a murder investigation after a 23-year-old man was shot dead in a gangland shooting in Finglas, Dublin. 21 November – The Minister for Justice Helen McEntee sought approval from the Cabinet for the repeal of antique censorship laws.
== Properties == Silica gel's high specific surface area—around 750–800 m2/g (230,000–240,000 sq ft/oz)—allows it to absorb water readily, making it useful as a desiccant (drying agent). Silica gel is often described as "absorbing" moisture, which may be appropriate when the gel's microscopic structure is ignored, as in silica gel packs or other products. However, material silica gel removes moisture by adsorption onto the surface of its numerous pores rather than by absorption into the bulk of the gel. Silica gel is able to absorb up to 37% of its own weight in moisture in high-humidity environments. This moisture can be released upon heating at about 120 °C (248 °F) for 1–2 hours. This makes it reusable multiple times with very little, if any, loss of efficiency.
== Physiology == A subunits of human factor XIII are made primarily by platelets and other cells of bone marrow origin. B subunits are secreted into blood by hepatocytes. A and B units combine within blood to form heterotetramers of two A units and two B units. Blood plasma concentration of the heterotetramers is 14–48 mg/L and half-life is 9–14 days. A clot that has not been stabilized by FXIIIa is soluble in 5 mol/L urea, while a stabilized clot is resistant to this phenomenon.
=== Prevention of atrial fibrillation === In 2005, meta-analysis results showed that angiotensin receptor blockers and angiotensin converting enzyme inhibitors considerably reduce the risk of atrial fibrillation in patients with coexisting heart failure and systolic left ventricular dysfunction. Specifically, an analysis of the CHARM study showed benefits for Candesartan in reducing new occurrences of atrial fibrillation in patients with heart failure and reduced left ventricular function. While these studies have demonstrated a potential additional benefit for candesartan when used in patients with systolic left ventricular dysfunction, additional studies are required to further elucidate the role of candesartan in the prevention of atrial fibrillation in other population groups.
Sources: en.wikipedia.org
TB-500 is a synthetic heptapeptide corresponding to a fragment of thymosin beta-4. It is used in laboratory research and is not an approved drug.
No. Thymosin beta-4 is a 43-amino-acid protein, while TB-500 represents only a short N-terminal segment. The two should not be treated as interchangeable in experimental design.
It is often called a thymosin beta-4 fragment, Tβ4 fragment, or Ac-LKKTETQ. The name TB-500 is mainly a commercial or catalog label rather than a formal chemical name.
Usually not, though usage overlaps. The label most often refers to a short acetylated fragment of the parent protein, while thymosin beta-4 itself is the full 43-residue molecule. Because suppliers vary, a sequence statement is needed to settle the question for any particular lot.