If you have been reading about vaccine adjuvant and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Last reviewed on 2026-04-20. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
Clinical research has examined the peptide in chronic hepatitis B and C, as a vaccine adjuvant, and in sepsis and oncology settings. Findings across trials are mixed; some report changes in selected immune markers, while others find no clear clinical benefit. Many studies are small and define outcomes differently, which limits comparison. Regulatory approval is confined to a few countries, and the compound is not an approved drug in the United States or most of Europe.
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 is a synthetic peptide of 28 amino acid residues that corresponds to a naturally occurring fragment first isolated from thymus tissue. Its chain is acetylated at the amino terminus, a modification that shields the peptide from rapid cleavage by aminopeptidases. The molecule carries a net negative charge at physiological pH and dissolves freely in water. Researchers classify it as an immune-modulating agent rather than a classical hormone, because it acts on several cell types of both the innate and the adaptive immune system.
The peptide was identified during work in the 1970s on thymosin fraction 5, a partially purified extract of calf thymus. Investigators separated that mixture and characterized individual components, one of which they named thymosin alpha-1. The same compound later received the international nonproprietary name thymalfasin. Commercial material is produced by solid-phase peptide synthesis rather than by extraction, so synthetic and natural forms share an identical sequence. Naming conventions vary across the literature, and readers should distinguish the alpha-1 peptide from other thymosins that have unrelated sequences and functions.
| 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 |
Thymosin alpha 1 is a synthetic 28-amino-acid peptide first isolated in 1966 from thymosin fraction 5, a bovine thymus extract. Its chain begins with an acetylated serine residue and ends with asparagine. The native peptide carries a molecular mass near 3,108 daltons. Researchers classify it as an immunomodulatory agent rather than a hormone with a single endocrine target. Early work framed it as a thymus-derived factor that supports T-cell maturation. The synthetic form used in research and clinical products matches the natural sequence.
Immune signaling studies link thymosin alpha 1 to Toll-like receptor pathways, particularly TLR2 and TLR9, on dendritic cells and other antigen-presenting cells. Activation of these receptors promotes maturation of T cells and increases natural killer cell activity. The peptide shifts cytokine output toward a T helper 1 profile, raising interferon gamma and interleukin 2 while modulating interleukin 10. Whether these effects translate into clinical benefit for any specific disease remains a subject of debate. Reported outcomes vary across trials and populations.
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。
Stability depends on temperature, pH, and the number of freeze-thaw events the sample has experienced. Freeze-dried material is commonly held at -20 °C or colder, while reconstituted liquid is kept cold and used within a short window. Extreme pH and prolonged light exposure can promote deamidation, oxidation, or aggregation, particularly at asparagine and methionine positions. Adsorption to container walls can lower the measured concentration of a dilute solution even when the peptide molecules themselves remain intact.
Identity and purity are usually assessed by reversed-phase high-performance liquid chromatography, which separates the target peptide from truncated or chemically modified byproducts. Mass spectrometry confirms the expected molecular mass and can indicate acetylation state or sequence errors. Amino acid analysis and peptide mapping supply complementary sequence-level information, while endotoxin testing is relevant for preparations intended for cell or animal work. Purity figures reported by suppliers refer to the method used and are not directly comparable across laboratories unless conditions are stated.
In February 2018, the Wall Street Journal listed Medtronic's 2015 tax inversion to Ireland as the largest U.S. corporate tax inversion executed between 2013 and 2016. In May 2018, Medtronic was ranked as the largest corporate tax inversion in history. In May 2018, Medtronic was ranked as the world's largest medical device company by 2017 revenues (see table below). In May 2019, Medtronic announced it would acquire Titan Spine, a technology company focusing on titanium spine implants. Chief Executive Officer Omar Ishrak retired in April 2020 and stayed on as executive chairman and chairman of the board until December 2020. Ishrak was succeeded by senior executive Geoff Martha. In January 2020, the company announced its intention to acquire Stimgenics, LLC and its primary therapy: differential target, multiplexed, spinal cord stimulation. In July, the company announced it would acquire Medicrea for €7.00 per share. In August, Medtronic announced it would acquire Companion Medical, who manufacture a smart insulin pen system, which connects to a diabetes management app. In September Medtronic acquired Avenu Medical for an undisclosed sum. In February 2021, the company recalled its HeartWare Ventricular Assist Device. In June 2021, the controller ports were pulled from the market. On 3 June 2021, the FDA alerted physicians to stop new implants of the HVAD system due to "an increased risk of neurological adverse events and mortality associated with the internal pump." In November 2021, the company was added to the Dow Jones Sustainability World Index.
== Mechanism == Three main changes are seen in the mechanism of Raynaud's phenomenon: reduced blood flow, blood vessel constriction, and neurogenic, inflammatory, and immune responses. It is induced by emotional stress and coldness. In all cases, the primary cause is an underlying hyperactivation of the sympathetic nervous system, although the exact pathophysiology differs depending on the type. In the primary type, there is an increase in sensitivity due to the issues mentioned above, resulting in vasoconstriction. In the secondary type, normal activity of blood vessels is disrupted due to the same issues, causing vasoconstriction which leads to ischemia and tissue death.
Weight gain due to extra water retention to the muscle Upset stomach One well-documented effect of creatine supplementation is weight gain within the first week of the supplement schedule, likely attributable to greater water retention due to the increased muscle creatine concentrations by means of osmosis. A 2009 systematic review discredited concerns that creatine supplementation could affect hydration status and heat tolerance and lead to muscle cramping and diarrhea. Despite weight gain due to water retention and potential cramps being two seemingly "common" side effects, new research indicates that these side effects are likely not the result of creatine usage. In addition, the initial water retention is attributed to more short-term creatine use (the "loading" phase). Studies have shown that creatine usage does not necessarily affect total body water relative to muscle mass in the long-term.
Sources: en.wikipedia.org
Under Khosrow II, the Sassanids occupied the Levant and Egypt and advanced into Asia Minor, and the Avars and Slavs raided in the Balkans. The Empire's control of Italy also weakened. After successfully repelling a siege of Constantinople in 626, Heraclius won a decisive victory at the Battle of Nineveh, eventually defeating the Sassanids later that year. The triumph would prove short-lived. The Arab conquests soon saw the conquest of the Levant, Egypt, and the Sassanid Empire by the newly formed Arab Rashidun Caliphate. By Heraclius' death in 641, the empire had been severely reduced economically and territorially—the loss of the wealthy eastern provinces had deprived the empire of as much as three-quarters of its revenue. The next century is poorly documented. Arab raids into Asia Minor started quickly, and the Empire responded by holding fortified centres and avoiding battle wherever possible. Although Anatolia was invaded annually, it avoided permanent Arab occupation. The outbreak of the First Fitna in 656 gave the Empire breathing space, which it used sensibly: some order was restored in the Balkans by Constans II (r. 641–668) following his administrative reorganisation which over time evolved into the "theme system", a structure that allocated troops to defend specific provinces. Constantine IV (r. 668–685) repelled the Arab efforts to capture Constantinople in the 670s using Greek fire, but suffered a reversal against the Bulgars, who soon established an empire in the northern Balkans.
=== Etymology === The word tomato comes from the Spanish tomate, which in turn comes from the Nahuatl word tomatl [ˈtomat͡ɬ] . The specific name lycopersicum, meaning 'wolf peach', originated with Galen, who used it to denote a plant that has never been identified. Luigi Anguillara speculated in the 16th century that Galen's lycopersicum might be the tomato, and despite the impossibility of this identification, lycopersicum entered scientific use as a name for the fruit.
=== Reproductive system === Most male birds do not have intromittent penises, but some species have copulatory organs or "phalluses." Males within Palaeognathae (with the exception of the kiwis), the Anseriformes (with the exception of screamers), and in rudimentary forms in Galliformes (but fully developed in Cracidae) possess a penis, which is never present in Neoaves. Its length is thought to be related to sperm competition and it fills with lymphatic fluid instead of blood when erect. When not copulating, it is hidden within the proctodeum compartment within the cloaca, just inside the vent. Female birds have sperm storage tubules that allow sperm to remain viable long after copulation, a hundred days in some species. Sperm from multiple males may compete through this mechanism. Most female birds have a single ovary and a single oviduct, both on the left side, but there are exceptions: species in at least 16 different orders of birds have two ovaries. Even these species, however, tend to have a single oviduct. It has been speculated that this might be an adaptation to flight, but males have two testes, and it is also observed that the gonads in both sexes decrease dramatically in size outside the breeding season. Also, terrestrial birds generally have a single ovary, as does the platypus, an egg-laying mammal. A more likely explanation is that the egg develops a shell while passing through the oviduct over a period of about a day, so that if two eggs were to develop at the same time, there would be a risk to survival.
Sources: en.wikipedia.org
=== Operation Iraqi Freedom, 2006–2009, "The Surge" === In December 2006, 2nd BCT deployed once again to Iraq in support of OIF. On 4 January 2007, 2nd Brigade deployed to northern Bagdad in the Sumer and Talbiyah district, returning 8 March 2008. On 4 June 2007, 1st Brigade deployed to Southern Iraq, returning 15 July 2008. Since the deployment began, the division has lost 37 paratroopers. Since 11 September 2001, the division has lost 20 paratroopers in Afghanistan and 101 paratroopers in Iraq.
==== Shevyrev classification ==== Shevyrev (2005) suggested a division into eight subclasses, mostly comprising the more diverse and numerous fossil forms, although this classification has been criticized as arbitrary, lacking evidence, and based on misinterpretations of other papers.
After John's death, Constantine VII's grandsons Basil II and Constantine VIII ruled jointly for half a century, although the latter exercised little real power. Their early reign was occupied by conflicts against two prominent generals, Bardas Skleros and Bardas Phokas, which ended in 989 after Phokas's death and Skleros's submission, and by a power struggle against the eunuch Basileios, who was dismissed in 985. Basil, who never married or had children, subsequently refused to delegate much authority: he took personal command of the army, sidelined established military families, and promoted officers loyal to him. His reign witnessed the decades-long campaign against Bulgaria, in which the Battle of Kleidion in 1014 proved decisive before the final Byzantine conquest in 1018. Diplomatic efforts, critical for this success, also contributed to the annexation of Caucasian territories in the 1020s and coexistence with the new Fatimid Caliphate. When he died in 1025, Basil's empire stretched from the Danube and southern Italy in the west to the Euphrates in the east; his rapid expansion was not matched by comparable administrative reforms.
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.
It is a 28-residue synthetic peptide studied as an immune-modulating agent and approved as a drug in some countries. The sequence matches a naturally occurring fragment isolated from thymus tissue. It is not a hormone in the endocrine sense.