This is a working overview of chronic hepatitis B, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2026-03-12 and is reviewed periodically as new material appears.
Thymosin beta-4 is a separate 43-residue peptide that binds actin and participates in cell migration; it shares no sequence similarity with thymosin alpha-1 despite the common family name. Other preparative materials, such as thymosin fraction 5 and thymopoietin, contain distinct mixtures or peptides. The shared thymosin label reflects the tissue of origin used in early purification, not a common structural core. Treating these molecules as interchangeable is a frequent source of confusion in laboratory reports and in popular summaries alike.
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.
Within the immune system, the peptide acts on several cell types rather than a single target. Reported activities include promotion of T-cell maturation, enhancement of natural killer cell activity, and modulation of cytokine production by dendritic cells and macrophages. Some of these effects appear to operate through toll-like receptor signaling, though the precise receptor-level mechanism remains debated. Whether the observed immune changes translate into clinical benefit is a separate question and depends on the indication studied.
The peptide was described in the 1970s as a component of thymic extracts, and early research focused on restoring immune function in immunodeficiency states. A synthetic version entered clinical development in the 1980s and is approved as a drug in several countries for conditions such as chronic hepatitis B and certain immunodeficiencies. Approval status varies widely by jurisdiction, and in the United States it is not an approved therapeutic. Regulatory and clinical positions differ, so statements about efficacy should be tied to specific indications and studies.
| Property | Value | Notes |
|---|---|---|
| Molecular mass | About 3.1 kDa | 28 residues, N-terminally acetylated |
| Appearance | White to off-white powder | Lyophilized solid |
| Solubility | Freely soluble in water | Also soluble in aqueous buffers |
| Storage temperature | 2 to 8 °C | Protect from light and moisture |
| Common synonyms | Thymalfasin; Tα1 | Same peptide sequence |
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.
Thymosin alpha-1 is a synthetic 28-amino-acid peptide whose sequence was first identified in extracts of bovine thymus tissue during the 1970s. The chain carries an acetyl group on its N-terminal serine. Its acidic residue content is high, which produces strong water solubility and an isoelectric point well below neutrality. Material supplied for laboratory and clinical use is manufactured by solid-phase peptide synthesis rather than purified from animal tissue. Different salt forms, such as the acetate, alter the counter-ion content without changing the peptide backbone.
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。
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.
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.
The peptide is generated in cells by cleavage of prothymosin alpha, a larger acidic protein encoded by the PTMA gene. Prothymosin alpha is expressed in many tissues, not only in the thymus, and its functions include nuclear roles in chromatin-related processes. The 28-residue fragment corresponds to the N-terminal portion of that precursor. How the cleavage occurs and how the fragment's concentration is regulated remain open questions; circulating amounts are small and difficult to measure reliably with routine assays.
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.
peripheral membrane protein Also extrinsic membrane protein. Any of a class of membrane proteins which attach only temporarily to the cell membrane, either by penetrating the lipid bilayer or by attaching to other proteins which are permanently embedded within the membrane. The ability to reversibly interact with membranes makes peripheral membrane proteins important in many different roles, commonly as regulatory subunits of channel proteins and cell surface receptors. Their domains often undergo rearrangement, dissociation, or conformational changes when they interact with the membrane, resulting in the activation of their biological activity. In protein purification, peripheral membrane proteins are typically more water-soluble and much easier to isolate from the membrane than integral membrane proteins.
Tolkien's Middle-earth fantasy writings have been said to embody outmoded attitudes to race. However, scholars have noted that he was influenced by Victorian attitudes to race and to a literary tradition of monsters, and that he was anti-racist both in peacetime and during the two World Wars. With the late-19th-century background of eugenics and a fear of moral decline, some critics believe that the mention of race mixing in The Lord of the Rings embodies scientific racism. Critics have noted, too, that the work embodies a moral geography, with good in the West, evil in the East. Against this, Tolkien strongly opposed Nazi racial theories, as seen in a 1938 letter he wrote to his publisher, while during the Second World War he vigorously opposed anti-German propaganda. His Middle-earth has been described as definitely polycultural and polylingual, while scholars have noted that attacks on Tolkien based on The Lord of the Rings often omit relevant evidence from the text. A spokesman for HarperCollins, publisher of the trilogy, said: "A number of academics have commented on Tolkien's work and this is the first time anybody has ever seen these issues in it. Of course, if you look hard enough at many great epics, you can extrapolate what you like, particularly if you have academic kudos behind you."
In the United States, almost all public universities were founded, and are operated by state governments and rely on subsidies from their respective states. They often have large enrollments, extensive facilities, and large budgets. However, support for public universities has declined in recent decades, forcing many public universities to seek private donations or raise tuition and fees. The percentage of state appropriations at public universities has fallen from 78% in 1974 to 43% in 2000. States generally charge higher tuition to out-of-state students because in-state students or their parents have previously subsidized the university by paying state taxes. The oldest public universities in the United States are the University of Georgia, founded in 1785, and the University of North Carolina at Chapel Hill, founded in 1789. The College of William & Mary, founded in 1693, and Rutgers University, founded in 1766, were two of the nine colonial colleges. Both were private universities until the 20th century, with William & Mary becoming public in 1908 and Rutgers in 1945. Every state has at least one public university and the largest states have more than thirty. This is partly a result of 1862 Morrill Land-Grant Acts, which gave eligible states 30,000 acres (12,141 ha) of federal land to sell to finance public universities that emphasized studies in agriculture and mechanical arts. The University of Wisconsin, Iowa State University, Rutgers, the State University of New Jersey, and the University of Missouri were early land-grant colleges.
Alpha: Lineage B.1.1.7 emerged in the United Kingdom in September 2020, with evidence of increased transmissibility and virulence. Notable mutations include N501Y and P681H. An E484K mutation in some lineage B.1.1.7 virions has been noted and is also tracked by various public health agencies. Beta: Lineage B.1.351 emerged in South Africa in May 2020, with evidence of increased transmissibility and changes to antigenicity, with some public health officials raising alarms about its impact on the efficacy of some vaccines. Notable mutations include K417N, E484K and N501Y. Gamma: Lineage P.1 emerged in Brazil in November 2020, also with evidence of increased transmissibility and virulence, alongside changes to antigenicity. Similar concerns about vaccine efficacy have been raised. Notable mutations also include K417N, E484K and N501Y. Delta: Lineage B.1.617.2 emerged in India in October 2020. There is also evidence of increased transmissibility and virulence, and changes to antigenicity. Omicron: Lineage B.1.1.529 emerged around Botswana in November 2021. This lineage demonstrated significantly increased transmissibility and changes to antigenicity, and it subsequently dominated all circulating versions of the virus ever since its emergence. Omicron variant BA.3.2 was reported to be widespread across Europe and the US in April 2026. The variant has many changes to the spike protein, but had not been found to be more virulent than other Omicron variants, and existing vaccines protected against it.
Sources: en.wikipedia.org
== Clinical significance == 11-Deoxycortisol in mammals has limited glucocorticoid activity, but it is the direct precursor of the major mammalian glucocorticoid, cortisol. As a result, the level of 11-deoxycortisol is measured to diagnose impaired cortisol synthesis, to find out the enzyme deficiency that causes impairment along the pathway to cortisol, and to differentiate adrenal disorders. In 11β-hydroxylase deficiency, 11-deoxycortisol and 11-deoxycorticosterone levels increase, and excess of 11-deoxycorticosterone leads to mineralocorticoid-based hypertension (as opposed to 21-hydroxylase deficiency, in which patients have low blood pressure from a lack of mineralocorticoids). Low levels of cortisol can affect blood pressure by causing a decrease in sodium retention and volume expansion. This effect occurs because cortisol regulates the balance of water and electrolytes in the body. When cortisol levels are low, there is less sodium reabsorption by the kidneys, leading to increased excretion of sodium through urine. This ultimately reduces blood volume and lowers blood pressure. On the other hand, high levels of cortisol can also affect blood pressure by causing an increase in sodium retention and volume expansion. Cortisol-induced hypertension is accompanied by significant sodium retention, leading to an increase in extracellular fluid volume and exchangeable sodium. This expansion results in an increase in blood volume and subsequently increases blood pressure.
== History == Flutamide was first synthesized in 1967 by Neri and colleagues at Schering Plough Corporation. It was originally synthesized as a bacteriostatic agent, but was subsequently, and serendipitously found to possess antiandrogen activity. The code name of flutamide during development was SCH-13521. Clinical research of the medication began in 1971, and it was first marketed in 1983, specifically in Chile under the brand name Drogenil and in West Germany under the brand name Flugerel. Flutamide was not introduced in the United States until 1989; it was specifically approved by the U.S. Food and Drug Administration for the treatment of metastatic prostate cancer in combination with a gonadotropin-releasing hormone (GnRH) analogue. The medication was first studied for the treatment of hirsutism in women in 1989. It was the first "pure antiandrogen" to be studied in the treatment of hirsutism. Flutamide was the first NSAA to be introduced, and was followed by nilutamide in 1989 and then bicalutamide in 1995.
=== Packaging === Under section 409 of the Federal Food, Drug, and Cosmetic Act, irradiation of prepackaged foods requires premarket approval for not only the irradiation source for a specific food but also for the food packaging material. Approved packaging materials include various plastic films, yet does not cover a variety of polymers and adhesive based materials that have been found to meet specific standards. The lack of packaging material approval limits manufacturers production and expansion of irradiated prepackaged foods. Approved materials by FDA for Irradiation according to 21 CFR 179.45:
=== About Dyson === "Freeman Dyson's Brain", interview by Stewart Brand at Wired, 1998 2008 Video Interview with Freeman Dyson by Atomic Heritage Foundation, Voices of the Manhattan Project Roberts, Russ (7 March 2011). "Dyson on Heresy, Climate Change, and Science". EconTalk. Library of Economics and Liberty. "Freeman Dyson: 'I kept quiet for thirty years, maybe it's time to speak'". 52 Insights. 15 June 2018. Retrieved 25 November 2019. Remembering the Unstoppable Freeman Dyson Freeman Dyson at TED Freeman J. Dyson, a Biographical Memoir by Ann Finkbeiner and William H. Press.
== 2023 trial == Police arrested Letby on 3 July 2018 on suspicion of eight counts of murder and six counts of attempted murder, and searched her home. Officers were also seen at her parents' property the same day. Following her arrest, detectives began reviewing her entire nursing career, including her time at Liverpool Women's Hospital. She was bailed on 6 July, rearrested in June 2019, and bailed again shortly afterwards. Letby was arrested for a third time in November 2020 and was remanded in custody. She denied all allegations, attributing the collapses to issues such as staffing levels and hygiene. Letby's trial opened at Manchester Crown Court on 4 October 2022 before Mr Justice Goss. She pleaded not guilty to seven counts of murder and 15 counts of attempted murder. The infants were anonymised as Baby A to Baby Q. Reporting restrictions also protected the identities of nine colleagues who gave evidence. Two years before the trial, Mrs Justice Steyn had ordered that the surviving infants could not be identified until adulthood. Several adult witnesses were also granted anonymity, which the court considered necessary to secure their testimony.
Sources: en.wikipedia.org
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.
The name traces back to thymosin fraction 5, a crude thymus extract examined in the 1970s. Individual peptides in that mixture were labeled with Greek letters, and alpha-1 was one of them. The international nonproprietary name thymalfasin was assigned later.
No. Thymosin beta-4 contains 43 residues and binds actin, while thymosin alpha-1 contains 28 residues and acts on immune cells. The two sit in a historical naming group but share no sequence similarity, and they are not substitutes for one another.
It corresponds to a fragment of the larger protein prothymosin alpha, which is present in many tissues. The isolated 28-amino-acid peptide was originally obtained from thymus preparations, and the pharmaceutical product is synthesized rather than extracted. The term therefore describes both a natural fragment and a manufactured drug substance.