Everything below concerns thymalfasin. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2026-06-13. Where a claim depends on a specific study, the study is described rather than over-claimed.
Overall evidence quality varies considerably. A large share of published reports come from single centers, rely on surrogate immunological markers, or lack adequate control groups. Systematic reviews have highlighted this heterogeneity as a barrier to pooling results. Open questions include which patients, if any, might benefit, what treatment duration is appropriate, and whether any effect is independent of standard care. The peptide is often described as an immune modulator rather than a therapy for one disease, which complicates confirmatory trial design.
Thymosin alpha 1 was identified in 1977 as a component of thymosin fraction 5, a heterogeneous preparation used in early studies of thymic function. Investigators purified the active material and determined its amino acid sequence, which enabled chemical synthesis. Work in the following decades concentrated on T-cell maturation and immune reconstitution in animals and small human cohorts. Early preparations varied in composition, so results from that period are difficult to compare with studies using defined synthetic peptide.
Quality control for thymosin alpha-1 focuses on identity, purity, and potency. Identity is confirmed by mass spectrometry and amino acid analysis, while purity is assessed by chromatography with limits on related substances and residual solvents. Potency assays may use cell-based immune readouts, but these are not standardized across laboratories. Regulatory status differs by jurisdiction; no product is approved in the United States for clinical use, whereas some other countries register injectable forms for specific indications.
Quantifying thymosin alpha-1 in a sample usually relies on reverse-phase high-performance liquid chromatography. The peptide lacks strong chromophores, so detection often occurs at 214 nm, where the peptide backbone absorbs. Mass spectrometry provides confirmatory identification and can detect sequence variants or truncations. Immunoassays have been used in biological matrices, but they may cross-react with related fragments. For purity assessment, chromatographic peak area gives the main component percentage, while mass accuracy verifies molecular identity.
| Property | Value | Notes |
|---|---|---|
| First described | 1977 | Reported as a component of thymosin fraction 5 |
| Sequence length | 28 amino acids | N-terminal residue is acetylated |
| Net charge at neutral pH | Negative | Reflects a high proportion of acidic residues |
| Principal studied uses | Chronic hepatitis B and vaccine adjuvant | Research uses outnumber approved indications |
| Regulatory status | Approved in a limited number of countries | Not approved in the United States or most of Europe |
Laboratory work indicates that the peptide acts on cells of both the innate and adaptive immune systems. Reported effects include signalling through Toll-like receptors on dendritic cells, enhanced T-cell maturation, and increased natural killer cell activity. These actions are described largely from cell-culture and animal experiments, and the precise receptor-level events remain incompletely defined. Studies in humans have generally measured immune markers rather than a single defined molecular target. The resulting picture remains partly descriptive.
Clinical research has examined the peptide in chronic hepatitis B and C, as a vaccine adjuvant, and in sepsis and oncology settings. Results across trials have been mixed, and several studies were small or conducted under differing protocols. Regulatory status varies by country, and the compound is not approved in every jurisdiction where it is studied. Evidence for any single indication should be read with attention to sample size and endpoint choice.
Thymosin alpha-1 is a 28-residue peptide first isolated from thymus tissue in the 1970s. It corresponds to the N-terminal portion of thymosin beta-4, from which it is cleaved in vivo. The peptide carries an acetyl group at its N-terminus, a modification that affects its charge and stability. Synthetic material produced by solid-phase peptide synthesis is chemically identical to the natural fragment and is the form used in research and clinical studies.
Thymosin alpha-1 is supplied as a lyophilized powder in most research settings. The solid dissolves readily in water and in common aqueous buffers, and it is typically reconstituted shortly before use. Solutions are clear and colourless at ordinary working concentrations. Because the peptide is hygroscopic, weighing and reconstitution are usually performed with minimal exposure to ambient air. Aliquots are prepared to avoid repeated freeze-thaw cycles, and working solutions are kept cold.
Long-term storage is generally at minus twenty degrees Celsius or colder, preferably desiccated and protected from light. Lyophilized material is more stable than reconstituted solution, which degrades faster at room temperature. Stability depends on pH, ionic strength, and the presence of oxidising agents. Published stability data for the peptide are limited, so storage claims in catalogues should be treated as general guidance rather than measured guarantees. Freeze-thaw cycles are kept to a minimum.
20世纪70年代，研究者从胸腺提取物中纯化出多种小肽，Tα1是其中被较早表征的一种。最初的制备依赖组织匀浆和层析步骤，产量低且成分复杂。随着固相肽合成技术成熟，实验室和工业界能够生产与天然序列一致的合成版本。合成肽的纯度可达95%以上，并可通过反相高效液相色谱和质谱进行鉴定。这一转变使研究不再依赖动物胸腺来源。
市售的胸腺素α1通常以冻干粉形式提供，溶解后用于注射。其氨基酸组成包括多个酸性残基，因此在中性pH下带负电荷。该肽可溶于水和生理盐水，但在有机溶剂中溶解度有限。储存条件通常为冻干状态下负20摄氏度，溶解后需冷藏并避免反复冻融。常见的同义词包括胸腺肽α1、thymalfasin和Tα1。
胸腺素α1（thymosin alpha 1，Tα1）是一种由28个氨基酸组成的酸性肽，N端被乙酰化，分子量约为3108道尔顿。该肽最早从牛胸腺组织提取物中分离，属于胸腺素组分5的一个成分。其序列在不同哺乳动物中高度保守，提示其具有基本的生物学功能。名称中的“α1”指其在电泳中的迁移位置，并非表示亚型编号。它既存在于胸腺，也存在于脾脏和淋巴结等免疫组织。
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。
It is also possible to translate either by hand (for short sequences) or by computer (after first programming one appropriately, see section below); this allows biologists and chemists to draw out the primary amino acid sequence of the encoded protein on paper. First, convert each template DNA base to its RNA complement (note that the complement of A is now U), as shown below. Note that the template strand of the DNA is the one the RNA is polymerized against; the other DNA strand would be the same as the RNA, but with thymine instead of uracil.
=== Media presence === Collins has been a subject of press and tabloid attention since she first began appearing on The Only Way Is Essex in 2011. Her battle with her weight is something that has been widely documented throughout her career, however she has been consistently praised for her confidence, and has promoted body positivity and encouraged women to love themselves no matter what their size. Collins has a large following on social media, having amassed over 2 million followers on Instagram and over 1 million on Twitter. Such is her popularity, she is often paid to promote products and businesses on her pages and can earn up to £75,000 in one day from social media posts. Collins has stated that she only endorses products that she believes in. Collins is widely known for her diva meltdowns and recognisable catchphrases during her appearances on television and in the media, and as a result became the subject of numerous internet memes. She was branded the "meme queen" by the BBC whilst Peter Robinson of The Guardian described her as a "social media powerhouse who has literally made a meme out of mispronouncing the word meme". Collins is a staple of the "hun subculture" and has been regarded as the "Queen of Huns". Her popularity within the LGBT community has seen her make various appearances at nightclubs and events including G-A-Y and Glitterbomb. In June 2023, she performed at the Mighty Hoopla event in Brockwell Park.
=== How does dentinal bonding occur? === Dentin bonding refers to process of bonding a resin to conditioned dentin, where mineral component is replaced with resin monomers to form a biocomposite comprising dentin collagen and cured resin. The adhesive-dentin interface forms a tight and permanent bond between dentin and composite resins. It can be accomplished by either etch-and-rinse (total etch) or self-etch adhesives. In etch-and rinse, acid will dissolve the minerals to a certain depth and leaves the highly porous dentinal collagen network suspended in water. Then, the collagen network is infiltrated with resin monomers. After chemical polymerization of these monomers happen, activated by light cure, it will result in a polymer-collagen biocomposite, commonly known as the hybrid layer:
=== Doubling time === The doubling time is the amount of time it would take for a breeder reactor to produce enough new fissile material to replace the original fuel and additionally produce an equivalent amount of fuel for another nuclear reactor. This was considered an important measure of breeder performance in early years, when uranium was thought to be scarce. However, since uranium is more abundant than thought in the early days of nuclear reactor development, and given the amount of plutonium available in spent reactor fuel, doubling time has become a less important metric in modern breeder-reactor design.
=== In film === Several movies deal with rabies vaccine, notably the 1936 The Story of Louis Pasteur, which focuses on the life and achievements of Louis Pasteur, played by Paul Muni. The 1966 film Rage features a man bitten by a rabid dog who engages in a race against time to reach the nearest medical establishment to get the vaccine.
Sources: en.wikipedia.org
Because the model must be time reversible and must approach the equilibrium nucleotide (base) frequencies at long times, each rate below the diagonal equals the reciprocal rate above the diagonal multiplied by the equilibrium ratio of the two bases. As such, the nucleotide GTR requires 6 substitution rate parameters and 4 equilibrium base frequency parameters. Since the 4 frequency parameters must sum to 1, there are only 3 free frequency parameters. The total of 9 free parameters is often further reduced to 8 parameters plus
==== Partition of Vietnam ==== The Geneva Conference recognized the 17th parallel north as a "provisional military demarcation line", temporarily dividing the country into two zones. Operation Passage to Freedom began in August, consisting of the evacuation of Vietnamese civilians from communist North Vietnam to pro-Western South Vietnam. The Geneva Accords promised elections in 1956 to determine a national government for a united Vietnam. Neither the United States government nor the State of Vietnam signed the 1954 Geneva Accords. With respect to the question of reunification, the non-communist Vietnamese delegation objected strenuously to any division of Vietnam, but lost out when the French accepted the proposal of Viet Minh delegate Phạm Văn Đồng, who proposed that Vietnam eventually be united by elections under the supervision of "local commissions". The United States countered with what became known as the "American Plan", with the support of South Vietnam and the United Kingdom. The American Plan provided for unification elections under the supervision of the United Nations, but was rejected by the Soviet delegation. From his home in France, Bảo Đại appointed Ngo Dinh Diem as Prime Minister of the State of Vietnam. With American support, in 1955 Diem used a referendum to remove the former Emperor and declare himself the president of the State of Vietnam. When the elections failed to occur, Viet Minh forces that had remained in South Vietnam were activated and began to fight the government.
=== Temperature === Two issues are involved when considering the temperature of a ligation reaction. First, the optimum temperature for DNA ligase activity which is 37°C, and second, the melting temperature (Tm) of the DNA ends to be ligated. The melting temperature is dependent on length and base composition of the DNA overhang—the greater the number of G and C, the higher the Tm since there are three hydrogen bonds formed between G-C base pair compared to two for A-T base pair—with some contribution from the stacking of the bases between fragments. For the ligation reaction to proceed efficiently, the ends should be stably annealed, and in ligation experiments, the Tm of the DNA ends is generally much lower than 37°C. The optimal temperature for ligating cohesive ends is therefore a compromise between the best temperature for DNA ligase activity and the Tm where the ends can associate. However, different restriction enzymes generates different ends, and the base composition of the ends produced by these enzymes may also differ, the melting temperature and therefore the optimal temperature can vary widely depending on the restriction enzymes used, and the optimum temperature for ligation may be between 4-15°C depending on the ends. Ligations also often involve ligating ends generated from different restriction enzymes in the same reaction mixture, therefore it may not be practical to select optimal temperature for a particular ligation reaction and most protocols simply choose 12-16°C, room temperature, or 4°C.
acetan (Acetobacter xylinum) alginate (Azotobacter vinelandii, Pseudomonas spp.) cellulose (Acetobacter xylinum) chitosan (Mucorales spp.) curdlan (Alcaligenes faecalis var. myxogenes) cyclosophorans (Agrobacterium spp., Rhizobium spp. and Xanthomonas spp.) dextran (Leuconostoc mesenteroides, Leuconostoc dextranicum and Lactobacillus hilgardii) emulsan (Acinetobacter calcoaceticus) galactoglucopolysaccharides (Achromobacter spp., Agrobacterium radiobacter, Pseudomonas marginalis, Rhizobium spp. and Zooglea spp.) galactosaminogalactan (Aspergillus spp.) gellan (Aureomonas elodea and Sphingomonas paucimobilis) glucuronan (Sinorhizobium meliloti) N-acetylglucosamine (Staphylococcus epidermidis) N-acetyl-heparosan (Escherichia coli) hyaluronic acid (Streptococcus equi) indican (Beijerinckia indica) kefiran (Lactobacillus hilgardii) lentinan (Lentinus elodes) levan (Alcaligenes viscosus, Zymomonas mobilis, Bacillus subtilis) pullulan (Aureobasidium pullulans) scleroglucan (Sclerotium rolfsii, Sclerotium delfinii and Sclerotium glucanicum) schizophyllan (Schizophyllum commune) stewartan (Pantoea stewartii subsp. stewartii) succinoglycan (Alcaligenes faecalis var. myxogenes, Sinorhizobium meliloti) xanthan (Xanthomonas campestris) welan (Alcaligenes spp.)
Sources: en.wikipedia.org
Trials differ in patient population, dose schedule, background treatment, and the endpoints used to judge success. Many are small and single-center, so random variation can dominate the reported effects.
Authorization is limited to a small number of countries and covers specific indications such as chronic hepatitis B and vaccine adjuvant use. Availability and labelling differ by jurisdiction.
Most reviews describe it as an immunomodulatory agent with an uncertain clinical effect. They generally call for larger, better-controlled trials before firm conclusions are drawn.
Reverse-phase HPLC with ultraviolet detection at 214 nm is common. Mass spectrometry is used to confirm molecular identity and detect modifications. Immunoassays exist but may not distinguish the intact peptide from fragments.