The short version of freeze-thaw fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2026-08-01. Anything still debated is marked as such rather than presented as settled.
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.
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.
Practical handling focuses on limiting adsorption and contamination. The peptide dissolves readily in water, and dilute solutions tend to adhere to plastic and glass surfaces, so an inert carrier protein or a defined buffer can reduce losses in laboratory work. Workers also record the counter-ion form, since an acetate or trifluoroacetate salt changes the mass balance of the weighed powder. Documentation of lot number, purity value, and storage history supports reproducibility when results from different laboratories are compared.
Lyophilized material is generally held at reduced temperature to slow degradation, and storage at minus twenty degrees Celsius or lower is common practice for long-term retention. Short-term working portions are often kept between two and eight degrees Celsius. Once dissolved, the peptide is less stable than the dry powder, and repeated freeze-thaw cycles are associated with loss of material and with aggregate formation. Vials are usually allowed to reach room temperature before opening so that condensation does not introduce moisture, and solutions are protected from light where practical.
| 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 |
Biologically, the peptide is studied mainly in the context of immune cell development and regulation. It is produced in the thymus and in several other tissues, and it appears to influence the maturation and activity of T cells and other immune populations. Laboratory work describes effects on cytokine production, on the balance between T cell subsets, and on the function of dendritic cells. Much of this evidence comes from cell culture and animal models, so the extent to which the same pathways operate in humans remains an open question.
Clinical interest has centered on chronic viral hepatitis, on immune restoration in various conditions, and on use as an adjuvant intended to improve responses to vaccines. Trials have reported mixed results, and regulatory status differs sharply between countries; in some places it is a prescription product, while elsewhere it is sold without an approved therapeutic indication. Because published studies vary widely in design, population, and endpoints, comparisons across them are difficult and no single conclusion covers the whole literature.
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。
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。
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。
Identity and purity are normally confirmed by reversed-phase high-performance liquid chromatography and mass spectrometry. The expected mass for the acetylated 28-residue peptide is close to 3108 daltons, and a mass shift indicates a modification or truncation. Peptide mapping after enzymatic digestion can resolve sequence-level questions. Counter-ion content, water content, and residual solvents are separate quality attributes that a certificate of analysis may or may not report. Aggregation is monitored by size-exclusion chromatography when relevant.
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.
Messenger ribonucleic acid (mRNA) is a single-stranded molecule of RNA that corresponds to the genetic sequence of a gene, and is read by a ribosome in the process of synthesizing a protein. mRNA is created during the process of transcription, where an enzyme (RNA polymerase) converts the gene into primary transcript mRNA (also known as pre-mRNA). This pre-mRNA usually still contains introns, regions that will not go on to code for the final amino acid sequence. These are removed in the process of RNA splicing, leaving only exons, regions that will encode the protein. This exon sequence constitutes mature mRNA. Mature mRNA is then read by the ribosome, and the ribosome creates the protein utilizing amino acids carried by transfer RNA (tRNA). This process is known as translation. All of these processes form part of the central dogma of molecular biology, which describes the flow of genetic information in a biological system. As in DNA, genetic information in mRNA is contained in the sequence of nucleotides, which are arranged into codons consisting of three ribonucleotides each. Each codon codes for a specific amino acid, except the stop codons, which terminate protein synthesis. The translation of codons into amino acids requires two other types of RNA: transfer RNA, which recognizes the codon and provides the corresponding amino acid, and ribosomal RNA (rRNA), the central component of the ribosome's protein-manufacturing machinery. The concept of mRNA was first conceived by Sydney Brenner and Francis Crick in 1960 during a conversation with François Jacob.
Until the 1970s there was considerable debate within psychiatry on the most appropriate term to use to describe the new drugs. In the late 1950s the most widely used term was "neuroleptic", followed by "major tranquilizer" and then "ataraxic". The first recorded use of the term tranquilizer dates from the early nineteenth century. In 1953 Frederik F. Yonkman, a chemist at the Swiss-based Cibapharmaceutical company, first used the term tranquilizer to differentiate reserpine from the older sedatives. The word neuroleptic was coined in 1955 by Delay and Deniker after their discovery (1952) of the antipsychotic effects of chlorpromazine. It is derived from the Greek: "νεῦρον" (neuron, originally meaning "sinew" but today referring to the nerves) and "λαμβάνω" (lambanō, meaning "take hold of"). Thus, the word means taking hold of one's nerves. It was often taken to refer also to common side effects such as reduced activity in general, as well as lethargy and impaired motor control. Although these effects are unpleasant and in some cases harmful, they were at one time, along with akathisia, considered a reliable sign that the drug was working. The term "ataraxy" was coined by the neurologist Howard Fabing and the classicist Alister Cameron to describe the observed effect of psychic indifference and detachment in patients treated with chlorpromazine. This term derived from the Greek adjective "ἀτάρακτος" (ataraktos), which means "not disturbed, not excited, without confusion, steady, calm".
== Headquarters == The company has its headquarters in Columbia, Maryland, an unincorporated census-designated place in Howard County, Maryland. Although W. R. Grace commissioned the W. R. Grace Building in New York City, built in 1971, the company no longer has any offices at that location. Previously, the company had its headquarters in Boca Raton, Florida (1991-1999). Prior to its closing, the Boca Raton headquarters had about 130 employees. On January 27, 1999, it announced it was moving its administrative staff to the Columbia office and closing the Boca Raton headquarters. About 40 of the employees went to Columbia, and some employees went to Cambridge, Massachusetts. In 2014, the company emerged from a 13-year bankruptcy case stemming from asbestos claims and immediately built a new 90,000 sq ft headquarters building on its 160-acre Columbia campus.
13 December The UK economy shrinks for the second month in a row, with a 0.1% drop in GDP reported for October. The City of London grants planning approval for 1 Undershaft, a new skyscraper that will be tied with the Shard as western Europe's tallest building. 14 December Roisin Quinn, operations director of National Grid plc, confirms that power has been restored to all its customers who experienced outages during Storm Darragh. A number of Irish-themed pubs in the UK have told the BBC they have run out of Guinness after the brewery's owners, Diageo, imposed a limit on supplies in the run up to Christmas. A woman is killed and two men are injured in a shooting in Harlesden, West London. 15 December – UK Foreign Secretary David Lammy says that the British government has made "diplomatic contact" with the Syrian rebel group that overthrew the Assad regime. A £50m humanitarian aid package is announced for vulnerable Syrians. 16 December BBC News reports that Prince Andrew will not join the Royal family at Sandringham for Christmas following revelations about his links to an alleged Chinese spy. Yang Tengbo is named as the alleged Chinese spy with links to Prince Andrew. Archbishop of York Stephen Cottrell, who is to take temporary charge of the Church of England following the resignation of Justin Welby as Archbishop of Canterbury, faces calls for his resignation over his handling of a sexual abuse case while he was Bishop of Chelmsford.
The study of plant organs is covered in plant morphology. Organs of plants can be divided into vegetative and reproductive structures. Vegetative plant organs include roots, stems, and leaves. Reproductive organs are variable, and in flowering plants, they are represented by the flower, seed and fruit. In conifers, the organ that bears the reproductive structures is called a cone. In other divisions (phyla) of plants, the reproductive organs are called strobili, in Lycopodiophyta, or simply gametophores in mosses. Common organ system designations in plants include the differentiation of shoot and root. All parts of the plant above ground (in non-epiphytes), including the functionally distinct leaf and flower organs, may be classified together as the shoot organ system. The vegetative organs are essential for maintaining the life of a plant. While there can be 11 organ systems in animals, there are far fewer in plants, where some perform the vital functions, such as photosynthesis, while the reproductive organs are essential in reproduction. However, if there is asexual vegetative reproduction, the vegetative organs are those that create the new generation of plants (see clonal colony).
Sources: en.wikipedia.org
Guanidinoacetate methyltransferase deficiency (GAMT deficiency) is an autosomal recessive cerebral creatine deficiency that primarily affects the nervous system and muscles. It is the first described disorder of creatine metabolism, and results from deficient activity of guanidinoacetate methyltransferase, an enzyme involved in the synthesis of creatine. Clinically, affected individuals most commonly present with developmental delays, behavior disorders, and seizures. Diagnosis can be suspected on clinical findings, and must be confirmed by specific biochemical tests, brain magnetic resonance spectroscopy, or genetic testing as it is a genetic disorder. Biallelic pathogenic variants in the GAMT gene are the underlying cause of the disorder. After GAMT deficiency is diagnosed, it can be treated by dietary adjustments, including supplementation with creatine. Treatment is highly effective if started early in life but is demanding for parents and caretakers with several doses of creatine, L-ornithine and sodium benzoate needed daily. If treatment is started late, it cannot reverse brain damage which has already taken place. The prevalence of GAMT deficiency is estimated to be 1:250,000.
In November 2016, Celtic Biotech Ltd received approval from the French National Agency for the Safety of Medicines and Health Products to commence Part 2 of the Phase 1 dose escalation safety study Crotoxin in Patients with Advanced Cancer using an Intravenous Route of Administration. In December 2016, Spotlight Innovation announced the formation of a Scientific Advisory Board. The board includes Professor Hengli Tang of Florida State University, Dr. Elliot Androphy of Indiana University School of Medicine and Professor Kevin Hodgetts of Brigham and Women's Hospital. In June 2017, Spotlight Innovation entered into a sponsored research agreement with Brigham and Women's Hospital in support of research conducted by Professor Kevin Hodgetts, Ph.D., intended to develop drugs for the treatment of spinal muscular atrophy. In August 2017, Spotlight Innovation announced that its subsidiary Caretta Therapeutics had developed its first commercially available over-the-counter analgesic product for the treatment of chronic pain but the product was never launched. In August 2017, Spotlight Innovation entered into a sponsored research agreement with Indiana University in support of research conducted by Dr. Elliot Androphy intended to develop drugs for the treatment of spinal muscular atrophy.
The lichen is often found near highways and on trees growing along drainage ditches that receive runoff from fertilized fields, further supporting the role of anthropogenic nutrient enrichment in its inland establishment. The lichen grows on a range of substrates and in diverse habitats. It is found in hardwood forests within broad, low-elevation valleys and occurs sporadically on Populus and other hardwoods in riparian zones of agricultural and populated areas. It preferentially colonizes the upper parts of trunks (about 70% of total tree height), where the bark is younger and more exposed to sunlight. It is also abundant on farm buildings and on rocks immediately above the high water mark in coastal zones, and on rocky seashores it typically forms a distinct band in the supralittoral zone between more halophilic species below and terrestrial species above. Nutrient enrichment by bird droppings enhances the ability of X. parietina to grow on rock. The species demonstrates substrate versatility and has even been recorded overgrowing lead on lead-incised gravestones in England. The species demonstrates ecological resilience through its regenerative capacity. Unlike many foliose lichens that show strict positional control of growth limited to thallus margins, X. parietina can initiate new growth from virtually any damaged portion of its thallus. This ability to recover from physical damage or fragmentation allows it to persist in disturbed habitats where other lichens might fail to reestablish.
Maya Cave of "II Anlage" (Cave 205) has been carbon-dated to the 6th–7th century CE. The cave has an inscriptions in Sanskrit mentioning the King of Kucha Anantavarma. He is shown accompanied by two armed attendants.
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.
Cool storage below freezing is usual for long-term retention, with a desiccant and protection from light. Portions are often split before first use to avoid repeated handling.