If you have been reading about systematic review 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.
Updated 2026-05-09. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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。
| Property | Value | Notes |
|---|---|---|
| Amino acid length | 28 residues | Single chain with an acetylated N-terminus |
| Molecular mass | Approximately 3,108 Da | Small shifts occur with counter-ion and water content |
| Isoelectric point | Around 3.5 | Low value follows from the many acidic residues |
| Parent molecule | N-terminal region of prothymosin alpha | Free circulating form in humans is not firmly established |
| Common synonyms | Thymalfasin; T alpha 1 | Older literature also uses the full spelled-out form |
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 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.
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.
In early April 2014, Acting President Oleksandr Turchynov stated: "This was an exact plan of Putin on the aggression against Ukraine. Crimea was the beginning. [...] They worked out an aggressive, brutal and cynical technology in the Caucasus. [...] Scenario is the same: provocation is organized, local servicemen respond to it and as a result of military confrontation civilians are killed. Dreadful pictures of dead people and children, regular army is sent to protect people. This scenario was prepared for us. [...] That is why Ukrainian servicemen received an order to hold the line within their military bases and on the ships understanding that they will be provoked to kill civilians." On 8 August 2016, President Petro Poroshenko stated: "Russia's attack on Georgia was the prologue to the Russian war against Ukraine. The policy of appeasing an aggressor failed to function even in 2008. Moreover, it only fuelled the Kremlin's appetite. Then the transatlantic community could have joined their effort to isolate the predatory bear in its den. It was a lesson of history no one learnt in good time." Ukrainian Foreign Ministry said that the international reaction in August 2008 encouraged Russia to attack Ukraine. On 3 July 2017, opposition leader Mikola Statkevich said at a rally on the Independence Day, "We know perfectly well who runs Russia and what they allow themselves to do and we very well remember how Russian peacekeepers began the war with Georgia and how it was with the Black Sea fleet when Russia with its help seized Crimea."
== Enforcement == Within the European Union GMP inspections are performed by National Regulatory Agencies. GMP inspections are performed in Canada by the Health Products and Food Branch Inspectorate; in the United Kingdom by the Medicines and Healthcare products Regulatory Agency (MHRA); in the Republic of Korea (South Korea) by the Ministry of Food and Drug Safety (MFDS); in Australia by the Therapeutic Goods Administration (TGA); in Bangladesh by the Directorate General of Drug Administration (DGDA); in South Africa by the Medicines Control Council (MCC); in Brazil by the National Health Surveillance Agency (ANVISA); in India by state Food and Drugs Administrations (FDA), reporting to the Central Drugs Standard Control Organization; in Pakistan by the Drug Regulatory Authority of Pakistan; in Nigeria by NAFDAC; and by similar national organizations worldwide. Each of the inspectorates carries out routine GMP inspections to ensure that drug products are produced safely and correctly. Additionally, many countries perform pre-approval inspections (PAI) for GMP compliance prior to the approval of a new drug for marketing.
It was once generally believed that life and its materials had some essential property or substance (often referred to as the "vital principle") distinct from any found in non-living matter, and it was thought that only living beings could produce the molecules of life. In 1828, Friedrich Wöhler published a paper on his serendipitous urea synthesis from potassium cyanate and ammonium sulfate; some regarded that as a direct overthrow of vitalism and the establishment of organic chemistry. However, the Wöhler synthesis has sparked controversy as some reject the death of vitalism at his hands. Since then, biochemistry has advanced, especially since the mid-20th century, with the development of new techniques such as chromatography, X-ray diffraction, dual polarisation interferometry, NMR spectroscopy, radioisotopic labeling, electron microscopy and molecular dynamics simulations. These techniques allowed for the discovery and detailed analysis of many molecules and metabolic pathways of the cell, such as glycolysis and the Krebs cycle (citric acid cycle), and led to an understanding of biochemistry on a molecular level. Another significant historic event in biochemistry is the discovery of the gene, and its role in the transfer of information in the cell. In the 1950s, James D. Watson, Francis Crick, Rosalind Franklin and Maurice Wilkins were instrumental in solving DNA structure and suggesting its relationship with the genetic transfer of information. In 1958, George Beadle and Edward Tatum received the Nobel Prize for work in fungi showing that one gene produces one enzyme.
Sources: en.wikipedia.org
A bowel obstruction is generally a mechanical obstruction of the gastrointestinal tract and can occur anywhere from the Ligament of Treitz to the anus. When the obstruction affects only the small intestine, it is generally referred to as a small bowel obstruction to distinguish it from a colonic obstruction, which may or may not affect the small intestine. The distinction helps to narrow the possible causes and treatment. Common causes of small bowel obstruction include post-operative adhesions, hernias, intussusception, and intraabdominal tumors. Common causes of colonic obstruction include primary colon cancer, volvulus and post-operative adhesions. When the ileocecal valve is competent, colonic obstruction may manifest as gaseous distention of the colon, but not the small intestine; when the ileocecal valve is incompetent, it does not prevent retrograde passage of air and stool and a colonic obstruction will cause dilation of both large and small bowel. Bowel obstructions can be partial or complete. They can be differentiated on imaging by the intestinal gas pattern. Partial obstructions will have gas distal to the obstruction, whereas a complete obstruction will not. Sounds of "rushes and tinkles" are associated with partial obstructions and represent brief passages of fluid and gas (respectively) through the partial obstruction. Complete obstructions do not make these sounds.
The industrial-scale production of riboflavin uses various microorganisms, including filamentous fungi such as Ashbya gossypii, Candida famata and Candida flaveri, as well as the bacteria Corynebacterium ammoniagenes and Bacillus subtilis. B. subtilis that has been genetically modified to both increase the production of riboflavin and to introduce an antibiotic (ampicillin) resistance marker, is employed at a commercial scale to produce riboflavin for feed and food fortification. By 2012, over 4,000 tonnes per annum were produced by such fermentation processes. In the presence of high concentrations of hydrocarbons or aromatic compounds, some bacteria overproduce riboflavin, possibly as a protective mechanism. One such organism is Micrococcus luteus (American Type Culture Collection strain number ATCC 49442), which develops a yellow color due to production of riboflavin while growing on pyridine, but not when grown on other substrates, such as succinic acid.
=== Background === Influenced by strategic analyses such as the 1976 Team B report—which argued U.S. intelligence had vastly underestimated Soviet threats—and ideas of the Citizens' Advisory Council on National Space Policy, President Ronald Reagan announced the Strategic Defense Initiative (SDI) in 1983. It proposed a space-based global missile defense constellation intended to render nuclear weapons "impotent and obsolete." The program immediately faced challenges, with concerns by Congress, including prominent senators Sam Nunn and Joe Biden, over its apparent violation of the Anti-Ballistic Missile Treaty, questionable technical feasibility, spiraling launch costs, poor cost-exchange ratio, and destabilizing impact on arms control. By the 1990s, SDI was formally restructured into the Ballistic Missile Defense Organization, pivoting from space-based platforms to more proven ground- and sea-based systems. U.S. missile defense policy continued to evolve, with the 1999 National Missile Defense Act mandating a system to defend against limited ballistic missile attacks. Following a later Team B report's recommendation, President George W. Bush withdrew the U.S. from the ABM Treaty in 2001. The Obama administration's 2010 Review shifted focus from a homeland-centered shield to more flexible and cooperative regional defenses, limiting the space component to sensing and tracking. This was adjusted by the Trump administration's 2019 Review, expanding scope from rogue states such as North Korea, to include advanced hypersonic threats from "competitors" like Russia and China.
Sources: en.wikipedia.org
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.
Prothymosin alpha is a much larger acidic protein, roughly 111 to 113 residues long, and the thymosin alpha-1 sequence matches its N-terminal region. The small peptide is therefore best understood as a fragment of that parent protein rather than a separate gene product.
Trials and clinical reports have examined chronic hepatitis B and C, use as a vaccine adjuvant, and supportive treatment in some immunodeficiency and oncology settings. Results vary by indication, and regulatory approval differs between countries.
它不是经典的内分泌激素，而是一种免疫调节肽。其作用主要通过局部免疫细胞间的信号传递实现，而非经血液循环作用于远隔器官。