The short version of prothymosin alpha fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2026-04-18 and is reviewed periodically as new material appears.
Thymosin alpha-1 is a synthetic peptide of 28 amino acids whose sequence matches the amino-terminal region of prothymosin alpha. The chain is acetylated at its first residue and contains one disulfide bridge between two cysteine residues, which folds the molecule into a compact loop. Its molecular formula, C129H215N33O55, corresponds to a monoisotopic mass of roughly 3,106 daltons. Material used in laboratories is made by solid-phase synthesis rather than isolated from animal tissue.
Early work on thymic extracts in the 1960s described a heat-stable acidic fraction containing many polypeptides. Separation of that mixture yielded individual components, and thymosin alpha-1 was named as one of them on the basis of assays for T-cell activity. The first preparations came from calf thymus, while subsequent research and clinical material has been chemically synthesized. Nomenclature in older papers is inconsistent, and the same peptide sometimes appears under different designations, which complicates literature searches.
Most published studies on thymosin alpha-1 report changes in immune measurements rather than clinical outcomes, and findings differ across designs and populations. Whether the peptide signals through one defined receptor or through several less specific interactions remains an open question. Its reported circulation half-life of a few hours complicates comparison of dosing schedules across trials. Mechanistic claims are frequently drawn from isolated cell cultures, and how far those results extend to whole organisms is unresolved.
胸腺素α1对免疫系统的影响涉及多种细胞类型。研究表明，它可促进未成熟T细胞向成熟T细胞分化，并增强T细胞对抗原刺激的增殖反应。树突状细胞在Tα1存在下表达更高水平的共刺激分子，从而更有效地呈递抗原。此外，自然杀伤细胞的活性也观察到上升。这些效应并非直接杀伤病原体，而是调节宿主免疫应答的强度与方向。
在信号层面，Tα1可能通过Toll样受体等模式识别受体发挥作用。部分实验显示，它能激活髓样分化因子88依赖的通路，进而促进核因子κB进入细胞核。这导致白细胞介素2、干扰素γ和白细胞介素12等细胞因子的转录增加。这些细胞因子偏向辅助性T细胞1型应答，有助于细胞免疫。然而，具体受体和结合位点尚未完全确定，不同实验模型的结果存在差异。
临床研究将Tα1用于慢性病毒感染、肿瘤辅助治疗和疫苗佐剂等场景。部分试验报告了免疫学指标改善，但临床终点获益在不同研究中并不一致。系统综述指出，研究间在人群、剂量和联合方案上差异较大，难以汇总结论。因此，Tα1的确切临床地位仍属开放问题，需要更多高质量随机对照试验来澄清。其机制研究也需从体外实验向体内模型推进。
| Property | Value | Notes |
|---|---|---|
| Class | Synthetic peptide | 28 residues; not a small-molecule compound |
| Molecular mass | About 3,106 Da | Monoisotopic mass of the unmodified chain |
| N-terminal group | Acetylated serine | Present in both native and synthetic forms |
| Secondary structure | Disulfide-constrained loop | One bridge between two cysteine residues |
| Typical source | Solid-phase synthesis | Early isolates came from bovine thymus extracts |
Thymosin alpha 1 is a short peptide first isolated from bovine thymus tissue in the early 1970s during fractionation work aimed at identifying factors that influence T cell development. It belongs to a family of acidic thymic peptides, and the original preparations contained several components that were later separated by chromatography. The compound is now produced synthetically rather than extracted from tissue, which removes batch variability tied to animal sourcing. Researchers describe it as an immunomodulatory peptide because laboratory studies show effects on several cell types of the innate and adaptive immune systems.
The molecule consists of 28 amino acid residues with an acetyl group attached to the N-terminal serine. Its sequence is acidic overall, with several glutamic and aspartic acid residues distributed along the chain and no cysteine, so disulfide bridges do not form. The peptide carries a net negative charge at physiological pH. Because the N-terminus is blocked, the intact molecule resists degradation by many aminopeptidases, which contributes to its stability in biological fluids.
Storage recommendations center on low temperature, dryness, and protection from repeated freezing and thawing. The intact powder is commonly held at 20 degrees below zero Celsius or colder, while a working solution is divided into single-use aliquots to limit freeze-thaw cycles. Buffered saline or phosphate-buffered saline at neutral pH is frequently used as a diluent. Light sensitivity is not well documented, yet amber vials or foil wrapping are common practice for long-term storage of peptide stocks.
Identity and purity are assessed with a small set of standard peptide methods. Reversed-phase high-performance liquid chromatography separates the main peak from truncated or oxidized species, and its area percentage is the usual purity measure. Mass spectrometry confirms the observed molecular mass against the expected value, while amino acid analysis or peptide mapping checks composition and sequence. Specifications for research-grade material are often stated as 95 percent or higher, though the exact limit depends on the supplier and the intended use.
== History == Hippocrates, in the 5th century BC, was one of the first people to mention the lymphatic system. In his work On Joints, he briefly mentioned the lymph nodes in one sentence. Rufus of Ephesus, a Roman physician, identified the axillary, inguinal and mesenteric lymph nodes as well as the thymus during the 1st to 2nd century AD. The first mention of lymphatic vessels was in the 3rd century BC by Herophilos, a Greek anatomist living in Alexandria, who incorrectly concluded that the "absorptive veins of the lymphatics," by which he meant the lacteals (lymph vessels of the intestines), drained into the hepatic portal veins, and thus into the liver. The findings of Ruphus and Herophilos were further propagated by the Greek physician Galen, who described the lacteals and mesenteric lymph nodes which he observed in his dissection of apes and pigs in the 2nd century AD. In the mid-16th century, Gabriele Falloppio (discoverer of the fallopian tubes), described what is now known as the lacteals as "coursing over the intestines full of yellow matter." In about 1563 Bartolomeo Eustachi, a professor of anatomy, described the thoracic duct in horses as vena alba thoracis. The next breakthrough came when, in 1622, a physician, Gaspare Aselli, identified lymphatic vessels of the intestines in dogs and termed them venae albae et lacteae, which are now known as simply the lacteals.
Use of methamphetamine can result in a stimulant psychosis which may present with a variety of symptoms (e.g., paranoia, hallucinations, delirium, and delusions). A Cochrane Collaboration review on treatment for amphetamine, dextroamphetamine, and methamphetamine use-induced psychosis states that about 5–15% of users fail to recover completely. The same review asserts that, based upon at least one trial, antipsychotic medications effectively resolve the symptoms of acute amphetamine psychosis. Amphetamine psychosis may also develop occasionally as a treatment-emergent side effect.
=== Characterization of interfaces and surfactant layers === Interfacial and surface tension can be characterized by classical methods such as the -pendant or spinning drop method. Dynamic surface tensions, i.e. surface tension as a function of time, can be obtained by the maximum bubble pressure apparatus The structure of surfactant layers can be studied by ellipsometry or X-ray reflectivity. Surface rheology can be characterized by the oscillating drop method or shear surface rheometers such as double-cone, double-ring or magnetic rod shear surface rheometer.
Sources: en.wikipedia.org
As of 2023, 38 states, four US territories, and the District of Columbia (DC) had legalized cannabis for medical use; for non-medical use, 24 of the states, three territories, and DC, had legalized it, and seven states decriminalized. Decriminalization in this context usually refers to first-time offenses and small quantities, such as, in the case of cannabis, under an ounce (28g). In November 2020, Oregon became the first state to decriminalize a number of drugs, including heroin, methamphetamine, PCP, LSD and oxycodone, shifting from a criminal approach to a public health approach; portions of that policy were reversed in April 2024. In 2022, Biden signed into law the Medical Marijuana and Cannabidiol Research Expansion Act, to allow cannabis to be more easily researched for medical purposes. It is the first standalone cannabis reform bill enacted at the federal level. That October, Biden stated on social media, "We classify marijuana at the same level as heroin – and more serious than fentanyl. It makes no sense", and pledged to start a review by the Attorney General on how cannabis is classified. On October 6, he pardoned all those with federal convictions for simple cannabis possession (to a degree symbolic, as none of those affected were imprisoned at the time), and urged the states, where the large majority of convictions rest, to do the same. His action affected 6,500 people convicted from 1992 to 2021, and thousands convicted in the District of Columbia.
==== Central nervous system and appetite regulation ==== GLP-1 receptor activation stimulates satiety, thus reducing food intake, promoting the development of a negative energy balance, and decreasing body weight over time, making GLP-1 agonists a treatment option for obesity. In the hypothalamus, this is achieved by stimulating anorexigenic (satiety-inducing) POMC and CART neurons while simultaneously inhibiting orexigenic (appetite-inducing) AgRP and NPY neurons. GLP-1 agonists also counteract obesity-induced leptin resistance. They do this by downregulating inhibitory proteins like SOCS3 and PTP1B, which restores the brain's JAK/STAT signaling cascade and re-establishes sensitivity to leptin.
NanoSIMS was used to study and prove for the first time the nitrogen fixing abilities of bacteria and archaea from the deep ocean by supplying 15N nitrogen contain compounds to sediment samples. NanoSIMS can also be used to estimate growth rate of organisms, as the amount of carbon or other substrate accumulated inside the cell allows for estimation of how much biomass is being generated.
Sources: en.wikipedia.org
At a temperature below the boiling point, any matter in liquid form will evaporate until reaching equilibrium with the reverse process of condensation of its vapor. At this point the vapor will condense at the same rate as the liquid evaporates. Thus, a liquid cannot exist permanently if the evaporated liquid is continually removed. A liquid at or above its boiling point will normally boil, though superheating can prevent this in certain circumstances. At a temperature below the freezing point, a liquid will tend to crystallize, changing to its solid form. Unlike the transition to gas, there is no equilibrium at this transition under constant pressure, so unless supercooling occurs, the liquid will eventually completely crystallize. However, this is only true under constant pressure, so that (for example) water and ice in a closed, strong container might reach an equilibrium where both phases coexist. For the opposite transition from solid to liquid, see melting. The phase diagram explains why liquids do not exist in space or any other vacuum. Since the pressure is essentially zero (except on surfaces or interiors of planets and moons) water and other liquids exposed to space will either immediately boil or freeze depending on the temperature. In regions of space near the Earth, water will freeze if the sun is not shining directly on it and vaporize (sublime) as soon as it is in sunlight. If water exists as ice on the Moon, it can only exist in shadowed holes where the sun never shines and where the surrounding rock does not heat it up too much.
With the exception of AlaRS, it has been discovered that 19 out of the 20 human aaRSs have added at least one new domain or motif. These new domains and motifs vary in function and are observed in various forms of life. A common novel function within human aaRSs is providing additional regulation of biological processes. There exists a theory that the increasing number of aaRSs that add domains is due to the continuous evolution of higher organisms with more complex and efficient building blocks and biological mechanisms. One key piece of evidence to this theory is that after a new domain is added to an aaRS, the domain becomes fully integrated. This new domain's functionality is conserved from that point on. As genetic efficiency evolved in higher organisms, 13 new domains with no obvious association with the catalytic activity of aaRSs genes have been added.
Biotechnology encompasses a wide range of procedures for modifying living organisms for human purposes, going back to domestication of animals, the cultivation of plants, and "improvements" to these through breeding programs that employ artificial selection and hybridization. Modern usage also includes genetic engineering, as well as cell and tissue culture technologies. The American Chemical Society defines biotechnology as the application of biological organisms, systems, or processes by various industries to learning about the science of life and the improvement of the value of materials and organisms, such as pharmaceuticals, crops, and livestock. As per the European Federation of Biotechnology, biotechnology is the integration of natural science and organisms, cells, parts thereof, and molecular analogues for products and services. Biotechnology is based on the basic biological sciences (e.g., molecular biology, biochemistry, cell biology, embryology, genetics, microbiology) and conversely provides methods to support and perform basic research in biology.
==== Negative selection ==== Negative selection removes thymocytes that are capable of strongly binding with "self" MHC molecules. Thymocytes that survive positive selection migrate towards the boundary of the cortex and medulla in the thymus. While in the medulla, they are again presented with a self-antigen presented on the MHC complex of medullary thymic epithelial cells (mTECs). mTECs must be Autoimmune regulator positive (AIRE+) to properly express tissue-specific antigens on their MHC class I peptides. Some mTECs are phagocytosed by thymic dendritic cells; this makes them AIRE− antigen presenting cells (APCs), allowing for presentation of self-antigens on MHC class II molecules (positively selected CD4+ cells must interact with these MHC class II molecules, thus APCs, which possess MHC class II, must be present for CD4+ T-cell negative selection). Thymocytes that interact too strongly with the self-antigen receive an apoptotic signal that leads to cell death. However, some of these cells are selected to become Treg cells. The remaining cells exit the thymus as mature naive T cells, also known as recent thymic emigrants. This process is an important component of central tolerance and serves to prevent the formation of self-reactive T cells that are capable of inducing autoimmune diseases in the host.
Sources: en.wikipedia.org
Its sequence corresponds to the amino-terminal portion of prothymosin alpha, a larger protein present in many cell types. The isolated 28-residue peptide is a fragment of that protein rather than a separately encoded molecule, and laboratory material is produced by synthesis.
The single bridge between two cysteine residues holds the chain in a folded loop that influences its shape and its behavior in solution. Loss of the bridge through reduction or oxidation shifts chromatographic retention and is tracked during stability work.
It is a defined 28-residue sequence derived from a larger precursor, whereas many other thymic preparations are mixtures of several polypeptides. Its acetylated amino terminus and single disulfide bridge distinguish it chemically from unrelated thymic extracts.
它促进未成熟T细胞分化并增强成熟T细胞的增殖与细胞因子分泌。这些作用有助于放大抗原特异性免疫应答。