Everything below concerns actin binding. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2026-01-02. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
Thymosin beta-4 contains 43 amino acids and has a reported molecular mass near 4963 Da. The short fragment most often associated with the TB-500 label, an acetylated chain beginning LKKTETQ, has a reported mass near 889 Da, so the two are easily separated in analytical work. Mass spectrometry and amino acid analysis can confirm which material is present in a given sample. Statements treating TB-500 and thymosin beta-4 as interchangeable are therefore imprecise, even though the two appear together in much of the same literature.
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.
Thymosin beta-4 is a 43-residue actin-binding protein found in most mammalian cell types, where it participates in cytoskeletal regulation and cell migration. TB-500 represents only a short fragment of that protein and does not include the remaining residues. Whether the isolated fragment reproduces the full range of activities reported for the intact protein remains an open question. Researchers commonly treat the two as related but distinct entities when comparing results.
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.
| Property | Value | Notes |
|---|---|---|
| Physical form | Lyophilised powder | Sealed vial; reconstituted before laboratory use |
| Appearance | White to off-white solid | Visual descriptor used on certificates of analysis |
| Solubility class | Water-soluble | Dissolves in water and aqueous buffers |
| Reported mass, fragment | Near 889 Da | Value depends on the stated sequence |
| Reported mass, parent protein | Near 4963 Da | 43-residue thymosin beta-4 |
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.
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.
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.
The compound is most often distributed as a lyophilized powder, appearing white to off-white and forming a loose cake or fluffy solid. It is hygroscopic to some degree, so brief exposure to humid air can add water weight and complicate weighing. The peptide dissolves readily in water and in neutral aqueous buffers, and aqueous solubility is generally described as high, well above the concentrations used in typical assays. Some polar organic solvents are also usable, which matters when a concentrated stock is prepared before dilution into buffer.
Pulmonary arterial hypertension (PAH) is a syndrome in which the blood pressure in the pulmonary arteries and pulmonary arterioles (the blood vessels located proximal to the capillary bed, the site of oxygen exchange in the lungs) is elevated. This pre-capillary pulmonary artery pressure being elevated is essential, and by definition a mean pulmonary artery pressure greater than 20 mmHg as measured by a right heart catheterization is required for the diagnosis. This pre-capillary pulmonary hypertension is confirmed with measuring pulmonary vascular resistance being greater than 3 Woods Units. A pulmonary artery wedge pressure being less than 15 mmHg (also measured by right heart catheterization) excludes post-capillary bed (in the veins distal to the capillary bed) pulmonary hypertension. Pulmonary arterial hypertension is a subgroup of pulmonary hypertension and is categorized as World Health Organization as group 1. PAH is further subdivided into various categories based on the cause, including idiopathic, heritable, drug and toxin induced, PAH associated with specific diseases (such as connective tissue disorders, portal hypertension or HIV), PAH that is responsive to vasodilators, PAH with venous or capillary involvement, and persistent PAH in the newborn period. If left untreated, the increased pulmonary vascular resistance will eventually lead to right heart failure and death. In the 1980s (before disease specific treatments became available) the 5 year survival rate was 34%.
== Treatment == Supervised exercise programs have been shown in small studies to improve exercise capacity by several measures: lowering heart rate, lowering serum creatine kinase (CK), increasing the exercise intensity threshold before symptoms of muscle fatigue and cramping are experienced, and the skeletal muscles becoming aerobically conditioned. Oral sucrose treatment (for example a sports drink with 75 grams of sucrose in 660 ml.) taken 30 minutes before exercise has been shown to help improve exercise tolerance, including a lower heart rate and lower perceived level of exertion compared with placebo. This is because the ingestion of a high-carbohydrate meal or drink causes transient hyperglycaemia, with the exercising muscle cells utilizing the high glucose in the blood for the glycolytic pathway. However, the ingestion of a high-carbohydrate meal or drink is problematic as a frequent form of treatment since it will increase the release of insulin, which inhibits the release of fatty acids and subsequently will delay the ability to get into second wind. The frequent ingestion of sucrose (e.g. sugary drinks), to avoid premature muscle fatigue and cramping, is also problematic in that it can lead to obesity as insulin will also stimulate triglyceride synthesis (develop body fat), and obesity-related ill health (e.g. type II diabetes and heart disease). A low dosage treatment with creatine showed a significant improvement of muscle problems compared to placebo in a small clinical study, while other studies have shown minimal subjective benefit.
== Presentations and papers == "Left 4 Dead" - Game Audio Network Guild Summer Summit (2010) "Matrix Revolutions: Techniques and Methodologies With Large Scale Sentinel 'Swarm' Scenes" - Silicon Valley ACM Siggraph (2004) "Matrix Sequels: Animation and Pipeline Methodologies in Large CG Film Productions" - San Francisco ACM Siggraph Student Chapter (2004) "Wiring Cracker: The Mechanics of a Non-Anthropomorphic, Real-Time, Performance Animation Puppet" - ACM Siggraph (1998)
Early lichenologists later reclassified the species in different genera. For instance, Erik Acharius (1803) referred to it as Parmelia parietina in his work Methodus, and Giuseppe De Notaris (1847) listed it as Physcia parietina. Johannes M. Norman (1852) treated it under Teloschistes (a related genus of orange-colored lichens), calling it Teloschistes parietinus. The modern genus Xanthoria was established by Theodor Fries. In 1860, he formally recombined the species as Xanthoria parietina. In his treatment, Fries recognized a distinct form, which he called Xanthoria aureola, distinguishing it from the more common form of X. parietina. He described aureola as a primary and fundamental form of the species, particularly prevalent in Arctic regions, differing from typical X. parietina in its color, rigid thallus, and preference for exposed habitats. Fries also cited Acharius, who considered aureola an intermediate between Xanthoria elegans (now Rusavskia elegans) and X. parietina. These distinctions may have contributed to later taxonomic interpretations that recognized Xanthoria aureola as a separate species. Xanthoria parietina is the type species of the genus Xanthoria. The designated lectotype for Xanthoria parietina is the illustration cited by Linnaeus from Dillenius (1742). Due to its reclassification across different genera, Xanthoria parietina has accumulated many synonyms in the literature. In addition to generic transfers, various infraspecific taxa (forms, varieties, or subspecies) have been described, particularly regarding morphological variants.
Sources: en.wikipedia.org
=== Middle Ages === After the fall of the Western Roman Empire, the town, along with the rest of the Italian peninsula, was conquered by the Heruli and the Ostrogoths, recaptured by the Romans, but then conquered again by the Lombards whose territory then fell into the hands of the Franks under Charlemagne (773). The Contea di Torino (countship) was founded in the 940s and was held by the Arduinic dynasty until 1050. After the marriage of Adelaide of Susa with Humbert Biancamano's son Otto, the family of the Counts of Savoy gained control. While the title of count was held by the Bishop as count of Turin (1092–1130 and 1136–1191) it was ruled as a prince-bishopric by the Bishops. In 1230–1235, it was a lordship under the Marquess of Montferrat, styled Lord of Turin. At the end of the 13th century, when it was annexed to the Duchy of Savoy, the city already had 20,000 inhabitants. Many of the gardens and palaces were built in the 15th century when the city was redesigned. The University of Turin was also founded during this period.
Cell division is essential for an organism to grow, but, when a cell divides, it must replicate the DNA in its genome so that the two daughter cells have the same genetic information as their parent. The double-stranded structure of DNA provides a simple mechanism for DNA replication. Here, the two strands are separated and then each strand's complementary DNA sequence is recreated by an enzyme called DNA polymerase. This enzyme makes the complementary strand by finding the correct base through complementary base pairing and bonding it onto the original strand. As DNA polymerases can only extend a DNA strand in a 5′ to 3′ direction, different mechanisms are used to copy the antiparallel strands of the double helix. In this way, the base on the old strand dictates which base appears on the new strand, and the cell ends up with a perfect copy of its DNA.
The regulation of genetic engineering concerns approaches taken by governments to assess and manage the risks associated with the use of genetic engineering technology, and the development and release of genetically modified organisms (GMO), including genetically modified crops and genetically modified fish. There are differences in the regulation of GMOs between countries, with some of the most marked differences occurring between the US and Europe. Regulation varies in a given country depending on the intended use of the products of the genetic engineering. For example, a crop not intended for food use is generally not reviewed by authorities responsible for food safety. The European Union differentiates between approval for cultivation within the EU and approval for import and processing. While only a few GMOs have been approved for cultivation in the EU a number of GMOs have been approved for import and processing. The cultivation of GMOs has triggered a debate about the coexistence of GM and non-GM crops. Depending on the coexistence regulations, incentives for the cultivation of GM crops differ.
Sources: en.wikipedia.org
==== pIII ==== pIII is the protein that determines the infectivity of the virion. pIII is composed of three domains (N1, N2 and CT) connected by glycine-rich linkers. The N2 domain binds to the F pilus during virion infection freeing the N1 domain which then interacts with a TolA protein on the surface of the bacterium. Insertions within this protein are usually added in position 249 (within a linker region between CT and N2), position 198 (within the N2 domain) and at the N-terminus (inserted between the N-terminal secretion sequence and the N-terminus of pIII). However, when using the BamHI site located at position 198 one must be careful of the unpaired Cysteine residue (C201) that could cause problems during phage display if one is using a non-truncated version of pIII. An advantage of using pIII rather than pVIII is that pIII allows for monovalent display when using a phagemid (plasmid derived from Ff phages) combined with a helper phage. Moreover, pIII allows for the insertion of larger protein sequences (>100 amino acids) and is more tolerant to it than pVIII. However, using pIII as the fusion partner can lead to a decrease in phage infectivity leading to problems such as selection bias caused by difference in phage growth rate or even worse, the phage's inability to infect its host. Loss of phage infectivity can be avoided by using a phagemid plasmid and a helper phage so that the resultant phage contains both wild type and fusion pIII.
=== 2013–2020: R40 Tour, disbandment and Peart's death === On November 18, 2013, Lifeson said that the band would take a year off after the completion of the world tour in support of Clockwork Angels. "We've committed to taking about a year off", Lifeson said. "We all agreed when we finished this [Clockwork Angels] tour [in early August], we were going to take this time off and we weren't going to talk about band stuff or make any plans. We committed to a year, so that's going to take us through to the end of next summer, for sure. That's the minimum. We haven't stopped or quit. Right now we're just relaxing. We're taking it easy and just enjoying our current employment." In September 2014, the Rush R40 box set was announced to commemorate the 40th anniversary of the release of the band's self-titled debut album. It included five previously released live video albums, and various previously unreleased footage from across the band's career. On January 22, 2015, the band announced the Rush R40 Tour, celebrating the 40th anniversary of Peart's membership in the band. The tour started on May 8 in Tulsa, Oklahoma, and wrapped up on August 1 in Los Angeles. On April 29, 2015, Lifeson said in an interview that R40 might be the final large-scale Rush tour due to his psoriatic arthritis and Peart's chronic tendinitis. He noted that it did not necessarily mean an end to the band, suggesting the possibility of smaller tours and limited performances. He said that he wanted to work on soundtracks with Lee. On December 7, 2015, Peart stated in an interview that he was retiring.
On 24 December 1944, the 82nd Airborne Division with an official strength of 8,520 men was facing off against a vastly superior combined force of 43,000 men and over 1,200 armored fighting and artillery vehicles and pieces. Due to these circumstances, the 82nd Airborne Division was forced to withdrawal for the first time in its combat history. The Germans pursued their retreat with the 2nd and 9th SS Panzer Divisions. The 2nd SS Panzer Division Das Reich engaged the 82nd until 28 December when it and what was left of the 1st SS Panzer Division Leibstandarte were ordered to move south to meet General George Patton's forces attacking in the area of Bastogne. Some units of the 9th SS Panzer including the 19th Panzer Grenadier Regiment stayed and fought the 82nd. They were joined by the 62nd Volksgrenadier Division. The 9th SS Panzer tried to breakthrough by attacking the 508 and 504 PIR positions, but ultimately failed. The failure of the 9th and 2nd SS Panzer Divisions to break through the 82nd lines marked the end of the German offensive in the northern shoulder of the Bulge. The German objective now became one of defense.
=== Yin yang and gender === Yin and yang were critical to the understanding of women's bodies, but understood only in conjunction with male bodies. Yin and yang ruled the body, the body being a microcosm of the universe and the earth. In addition, gender in the body was understood as homologous, the two genders operating in synchronization. Gender was presumed to influence the movement of energy and a well-trained physician would be expected to read the pulse and be able to identify two dozen or more energy flows. Yin and yang concepts were applied to the feminine and masculine aspects of all bodies, implying that the differences between men and women begin at the level of this energy flow. According to Bequeathed Writings of Master Chu the male's yang pulse movement follows an ascending path in "compliance [with cosmic direction] so that the cycle of circulation in the body and the Vital Gate are felt...The female's yin pulse movement follows a defending path against the direction of cosmic influences, so that the nadir and the Gate of Life are felt at the inch position of the left hand". In sum, classical medicine marked yin and yang as high and low on bodies which in turn would be labeled normal or abnormal and gendered either male or female. Bodily functions could be categorized through systems, not organs. In many drawings and diagrams, the twelve channels and their visceral systems were organized by yin and yang, an organization that was identical in female and male bodies. Female and male bodies were no different on the plane of yin and yang.
Sources: en.wikipedia.org
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.
Naming for research peptides is not standardised, and suppliers sometimes apply the same label to different chain lengths. Certificates of analysis and mass data are the practical way to determine what a given lot contains.
The fragment commonly cited under this label is reported near 889 Da, and the parent protein near 4963 Da. Reported values shift with the exact sequence and with residual counter-ions or water in the sample.
No. TB-500 is a short synthetic peptide matching residues 17 to 23 of thymosin beta-4, while the parent protein contains 43 residues. The fragment lacks the rest of the protein sequence, so the two are related but not identical.