Everything below concerns 免疫组织. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2026-08-01. Numbers and descriptions here follow the published literature rather than marketing material.
Thymosin alpha 1 is a 28-amino-acid peptide first isolated from thymosin fraction 5, a bovine thymic extract. Its sequence begins with an acetylated serine residue and carries a high proportion of acidic residues, so the molecule has a net negative charge near neutral pH. Despite the shared name, it is unrelated in sequence to the thymosin beta family. Synthetic material prepared by solid-phase peptide synthesis is identical in sequence to the natural peptide.
Several names appear in the literature for this peptide, including thymalfasin and the abbreviation T-alpha-1. Naming conventions differ among research articles, regulatory documents, and supplier catalogs, which complicates literature searches. Both synthetic and recombinant production routes yield a peptide with the same 28-residue sequence as the thymic isolate. Because the thymosin label also covers unrelated peptides, sources should be compared by sequence rather than by name alone.
The peptide occurs naturally in thymic tissue and has been detected in serum and other biological fluids. Reported concentrations are low, and reliable measurement generally requires immunoassay or mass spectrometry with an enrichment step. It is released from a larger precursor, prothymosin alpha, by proteolytic cleavage, although the enzymes involved are not fully characterized. Whether circulating levels reflect thymic output specifically remains an open question.
Whether the free 28-residue peptide circulates in human tissue remains debated. The best-documented human source is prothymosin alpha, a larger acidic protein that carries the sequence at its N-terminus. Reports of measurable peptide levels in serum and lymphoid tissue exist, yet some of that signal may come from cross-reacting fragments or from the parent protein. Most reviews therefore treat prothymosin alpha as the established human molecule and describe independent circulation of the small peptide as an unresolved question.
Immunological studies connect the peptide to multiple parts of the immune response. It has been reported to engage Toll-like receptor signaling, to promote dendritic cell maturation, and to influence the balance of T helper cell subsets. Changes in natural killer cell activity and in cytokine release appear in cell culture and animal models. These observations describe broad immunomodulatory behavior rather than a single defined receptor target, and the primary molecular interaction has not been settled.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C129H215N33O55 | Calculated for the acetylated 28-residue peptide |
| Appearance | White to off-white powder | Lyophilized solid recovered from aqueous buffer |
| Solubility | Freely soluble in water | Typically dissolved in water or buffer before use |
| Typical storage | -20 C or below, desiccated | Protect from light and avoid repeated freeze-thaw cycles |
| Identity testing | Reverse-phase HPLC with mass spectrometry | Retention time and measured mass confirm the sequence |
Like most short peptides, thymosin alpha-1 is susceptible to hydrolysis under strongly acidic or basic conditions and to oxidation when exposed to air over long periods. The acetylated amino terminus blocks one common degradation route, which contributes to the molecule's relative robustness in solution. Lyophilized material generally retains potency for extended periods when kept cold and dry. Once reconstituted, aqueous solutions are less stable and are typically used within a defined window rather than held indefinitely at ambient temperature.
Routine handling calls for storage of the lyophilized powder at refrigerated temperatures, away from light, in a sealed container. Working solutions are often prepared in sterile water or buffer and kept cold between uses. Repeated freeze-thaw cycles are generally avoided because they can promote aggregation and loss of material. Laboratories usually record lot number, reconstitution date, and storage conditions so that any change in behavior can be traced to a specific preparation.
Reverse-phase high-performance liquid chromatography is the standard technique for assessing purity and concentration, because the peptide's hydrophobicity allows clean separation from related impurities. Mass spectrometry confirms molecular identity and detects sequence errors or truncations. Amino acid analysis and peptide mapping supply additional structural confirmation when required. Chromatographic purity values reported on certificates of analysis describe the proportion of the main peak and do not by themselves establish biological activity.
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。
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。
Identity and purity are normally assessed by reversed-phase high-performance liquid chromatography, which separates the peptide from related impurities and truncation products. Mass spectrometry confirms molecular mass and detects modifications such as deamidation or oxidation. Amino acid analysis and peptide mapping provide additional sequence-level confirmation. For research material, a certificate of analysis typically reports these results together with water content and counter-ion identity, since the lyophilized powder is often supplied as an acetate or trifluoroacetate salt.
Several factors accelerate degradation: alkaline pH, elevated temperature, exposure to oxidants, and the presence of residual moisture. Deamidation of asparagine residues and oxidation of methionine are the most commonly reported degradation routes. Because the peptide lacks disulfide bonds, it does not undergo the thiol-related aggregation seen in some other biologics, but physical aggregation can still occur at high concentration. Stability data are product-specific, and extrapolating shelf life between formulations is not reliable.
Mahathir reclaimed Carcosa Hill, which had been given to the British by Tunku Abdul Rahman after independence as a sign of good faith, and was home to the British High Commissioner's residence. Mahathir developed a close friendship with Thatcher, leading to strengthened bilateral relations between the two countries during their tenure. Thatcher once praised Mahathir as a truly remarkable national leader and described Malaysia as a textbook example of how to build a prosperous nation. After Thatcher's 1985 visit to Malaysia, bilateral ties improved significantly. Key progress included enhanced trade, particularly in palm oil exports and British technology imports, as well as increased educational cooperation through scholarships for Malaysian students in the UK. Malaysia-UK relations were back on track, leading to Malaysia being chosen to host two major world events — the Commonwealth Heads of Government Meeting in Langkawi in 1989 and the Commonwealth Games in 1998. Mahathir spoke of his good working relationship with Thatcher, saying, "Malaysians should remember that she visited Kuala Lumpur three times — no other British PM has done this before or since." During John Major's visit to Malaysia in September 1993, five memorandums of understanding, involving several billion ringgit, were signed between Malaysian and British companies.
== Medical uses == Abacavir, in combination with other antiretroviral agents, is indicated for the treatment of HIV-1 infection. Abacavir should be used in combination with other antiretroviral agents.
In April 2021, Valve abandoned efforts to reboot the project, saying it had not found enough interested players to justify development. In June 2019, Valve released its second-generation VR hardware, the Valve Index. They also released Dota Underlords into early access, an auto battler based on a Dota 2 community-created mode Dota Auto Chess. In March 2020, Valve released Half-Life: Alyx, a VR game. It received acclaim and was described as VR's first killer app. Newell said in January 2021 that the success of Alyx created desire within the company to develop more games, and that several were under development. Valve collaborated with Netflix for Dota: Dragon's Blood, an animated television series based on Dota, which premiered in March 2021. In February 2022, Valve released the Steam Deck, a portable game system that runs on Linux-based SteamOS with the Proton compatibility layer that allows most Windows games on Steam to run on Linux without modification. In September 2023, Valve released Counter-Strike 2. It received generally favorable reviews, but player reception was mixed. In 2024, Valve began beta-testing a new multiplayer game, Deadlock, a combination of a hero shooter and MOBA. In September, staff members from Hopoo Games, developers of Risk of Rain, announced that they had been employed at Valve. According to a report by Forbes Australia published in December 2024, Valve had an annual revenue of $5 billion by 2023, with a 40% profit margin. Steam accounted for around 60% of this revenue, double that of 2019.
The gastroesophageal junction between the esophagus and the stomach is controlled by the lower esophageal sphincter, which remains constricted at all times other than during swallowing and vomiting to prevent the contents of the stomach from entering the esophagus. As the esophagus does not have the same protection from acid as the stomach, any failure of this sphincter can lead to heartburn.
Sources: en.wikipedia.org
Stuart Wright, Dancer's Guide to Injuries of the Lower Extremity (New York: Cornwall Books, 1985), p. 14. Swischuk, Leornard E. "Doing the Splits: Heard A Pop--Cannot Walk." Pediatric Emergency Care 23.11 (2007): 842-3. Web. 8 Sep. 2010. <http://ovidsp.tx.ovid.com>.
=== Pregnancy === Based on the limited data available, docetaxel appears to be safe in pregnancy if administered during the second and third trimesters; however, maternal and fetal risks should be weighed against benefits to determine the appropriate course of action. As with all chemotherapeutic agents, docetaxel administered to pregnant animals causes a variety of embryofetal toxicities, including death, when given during the period of organogenesis. Yet adequate studies investigating maternal and fetal effects in humans are lacking. One small systematic review that examined the use of taxanes to treat breast cancer in pregnancy showed that, out of 19 patients, only three congenital malformations occurred. Two cases of cerebral ventriculomegaly observed in the study were documented prior to the administration of chemotherapy, suggesting an alternate cause of congenital malformation. The third case involved pyloric stenosis in an infant whose mother received a combination regimen of docetaxel, doxorubicin, cyclophosphamide and paclitaxel; because the fetus was exposed to multiple drugs in utero, it remains difficult to identify docetaxel as the causative teratogenic agent. Further studies are needed to better assess the safety of docetaxel in pregnancy and determine appropriate dosing in pregnant women.
intermediates in biosynthesis, in post-translational formation of proteins, in a physiological role (e.g. components of bacterial cell walls, neurotransmitters and toxins), natural or man-made pharmacological compounds, present in meteorites or used in prebiotic experiments (such as the Miller–Urey experiment), might be important neurotransmitters, such as γ-aminobutyric acid, and can play a crucial role in cellular bioenergetics, such as creatine.
Sources: en.wikipedia.org
It is a 28-amino-acid peptide originally purified from a bovine thymic extract and later produced synthetically. It is studied mainly for its effects on immune cell function.
No. The two peptides share part of a name but differ in length, sequence, and net charge. Literature searches that treat them as one compound return misleading results.
Solid-phase peptide synthesis is the usual route, and recombinant expression has also been described. Both approaches produce material matching the natural sequence.
It is usually described as an immunomodulatory peptide rather than a classic circulating hormone. No endocrine gland is known to release it as a primary secretory product, and its measured presence in blood is not firmly established.