Everything below concerns lyophilized powder. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2025-10-01. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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。
| Property | Value | Notes |
|---|---|---|
| Storage of dry powder | -20 °C or below | Common practice for long-term retention |
| Storage after reconstitution | 2-8 °C, short term | Solution stability is limited compared with dry powder |
| Typical analytical method | Reversed-phase HPLC | Usually paired with mass spectrometry for mass confirmation |
| Detection wavelength | About 214 nm | Peptide backbone absorbance; buffer background must be controlled |
| Counter-ion forms | Acetate or trifluoroacetate | Affects mass balance and reported concentration |
Quality control for thymosin alpha-1 focuses on identity, purity, and potency. Identity is confirmed by mass spectrometry and amino acid analysis, while purity is assessed by chromatography with limits on related substances and residual solvents. Potency assays may use cell-based immune readouts, but these are not standardized across laboratories. Regulatory status differs by jurisdiction; no product is approved in the United States for clinical use, whereas some other countries register injectable forms for specific indications.
Quantifying thymosin alpha-1 in a sample usually relies on reverse-phase high-performance liquid chromatography. The peptide lacks strong chromophores, so detection often occurs at 214 nm, where the peptide backbone absorbs. Mass spectrometry provides confirmatory identification and can detect sequence variants or truncations. Immunoassays have been used in biological matrices, but they may cross-react with related fragments. For purity assessment, chromatographic peak area gives the main component percentage, while mass accuracy verifies molecular identity.
The lyophilized peptide is generally stable for extended periods when kept cold and dry. Once dissolved, aqueous solutions are less stable; hydrolysis, oxidation, and aggregation can degrade the material. Storage at -20 °C or lower slows these processes. Repeated freeze-thaw cycles are best avoided because they can promote aggregation. The exact shelf life depends on formulation, pH, and concentration, so stability studies are typically performed for each specific product.
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.
Lyophilized material is typically treated as a hygroscopic solid that should be brought to room temperature before the container is opened, which limits condensation on the powder. Reconstitution is commonly done with sterile water or a buffered diluent, and gentle mixing is preferred over vigorous agitation to reduce foaming and surface adsorption. Because peptides can bind to plastic and glass, diluents containing a small amount of carrier protein are sometimes used in laboratory work. Working solutions are generally aliquoted and prepared fresh rather than subjected to repeated freezing and thawing.
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.
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.
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.
Thymosin alpha-1 is a synthetic peptide of 28 amino acids whose sequence matches the amino-terminal region of prothymosin alpha. The chain is acetylated at its first residue and contains one disulfide bridge between two cysteine residues, which folds the molecule into a compact loop. Its molecular formula, C129H215N33O55, corresponds to a monoisotopic mass of roughly 3,106 daltons. Material used in laboratories is made by solid-phase synthesis rather than isolated from animal tissue.
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.
So it was proposed that succinyl amino acid derivative should be an ACE inhibitor and succinyl-L-proline was found to be such an inhibitor. It was also known that the nature of penultimate amino acid residue of a peptide substrate for ACE influences binding to the enzyme. The acyl group of the carboxyalkanoyl amino acid binds the zinc ion of the enzyme and occupies the same position at the active site of ACE as the penultimate. Therefore, the substituent of the acyl group might also influence binding to the enzyme. A 2-methyl substituent with D configuration was found to enhance the inhibitory potency by about 15 fold of succinyl-L-proline. Then the search for a better zinc-binding group started. Replacement of the succinyl carboxyl group by nitrogen-containing functionalities (amine, amide or guanidine) did not enhance inhibitory activity. However a potency breakthrough was achieved by the replacement of the carboxyl group with a sulfhydryl function (SH), a group with greater affinity for the enzyme bound zinc ion. This yielded a potent inhibitor that was 1000 times more potent than succinyl-L-proline. The optimal acyl chain length for mercaptoalkanoyl derivates of proline was found to be 3-mercaptopropanoyl-L-proline, 5 times greater than that of 2-mercaptoalkanoyl derivates and 50 times greater than that of 4-mercaptoalkanoyl derivates. So the D-3-mercapto-2-methylpropanoyl-L-proline or Captopril was the most potent inhibitor.
Thereafter, his approval ratings and approval of his handling of domestic and foreign policy issues steadily dropped. After his re-election in 2004, Bush received increasingly heated criticism from across the political spectrum for his handling of the Iraq War, his response to Hurricane Katrina, and to the Abu Ghraib prisoner abuse, NSA warrantless surveillance, the Plame affair, and Guantanamo Bay detention camp controversies. Amid this criticism, the Democratic Party regained control of Congress in the 2006 midterm elections. Polls conducted in 2006 showed an average approval rating of 37 percent for Bush, the lowest for any second-term president at that point in his term since Harry S. Truman in March 1951 (when Truman's approval rating was 28 percent), which contributed to what Bush called the "thumping" of the Republican Party in the 2006 elections. Throughout most of 2007, Bush's approval rating hovered in the mid-thirties; the average for his entire second term was 37 percent, according to Gallup.
=== Pre-history: the helical structure of RNA === The earliest work in RNA structural biology coincided, more or less, with the work being done on DNA in the early 1950s. In their seminal 1953 paper, Watson and Crick suggested that van der Waals crowding by the 2`OH group of ribose would preclude RNA from adopting a double helical structure identical to the model they proposed—what we now know as B-form DNA. This provoked questions about the three-dimensional structure of RNA: could this molecule form some type of helical structure, and if so, how? As with DNA, early structural work on RNA centered around isolation of native RNA polymers for fiber diffraction analysis. In part because of heterogeneity of the samples tested, early fiber diffraction patterns were usually ambiguous and not readily interpretable. In 1955, Marianne Grunberg-Manago and colleagues published a paper describing the enzyme polynucleotide phosphorylase, which cleaved a phosphate group from nucleotide diphosphates to catalyze their polymerization. This discovery allowed researchers to synthesize homogenous nucleotide polymers, which they then combined to produce double stranded molecules. These samples yielded the most readily interpretable fiber diffraction patterns yet obtained, suggesting an ordered, helical structure for cognate, double stranded RNA that differed from that observed in DNA. These results paved the way for a series of investigations into the various properties and propensities of RNA.
Insulin-like growth factor 2 receptor (IGF2R), also called the cation-independent mannose-6-phosphate receptor (CI-MPR) is a protein that in humans is encoded by the IGF2R gene. IGF2R is a multifunctional protein receptor that binds insulin-like growth factor 2 (IGF2) at the cell surface and mannose-6-phosphate (M6P)-tagged proteins in the trans-Golgi network.
Haemophilus influenzae (formerly called Pfeiffer's bacillus or Bacillus influenzae) is a Gram-negative, non-motile, coccobacillary, facultatively anaerobic, capnophilic pathogenic bacterium of the family Pasteurellaceae. The bacteria are mesophilic and grow best at temperatures between 35 and 37 °C. H. influenzae was first described in 1893 by Richard Pfeiffer during an influenza pandemic when he incorrectly identified it as the causative microbe, which is why the bacterium was given the name "influenzae". H. influenzae is responsible for a wide range of localized and invasive infections, typically in infants and children, including pneumonia, meningitis, or bloodstream infections. Treatment consists of antibiotics; however, H. influenzae is often resistant to the penicillin family, but amoxicillin/clavulanic acid can be used in mild cases. Serotype B H. influenzae (hib) can cause illness, called Hib infections, among other names. It has been a major cause of meningitis in infants and small children, frequently causing deafness and mental degradation. However, the development in the 1980s of a vaccine effective in this age group (the Hib vaccine) has almost eliminated this in developed countries. This species was the first organism to have its entire genome sequenced.
Sources: en.wikipedia.org
Transthoracic echocardiography is not recommended in the evaluation of aortic dissections owing to its limited ability to evaluate the aortic arch, the descending aorta or the blood vessels branching from the aorta. Its sensitivity may be further reduced in patients with obesity or lung emphysema. Transthoracic echocardiography has high sensitivity in evaluating the aortic root and proximal ascending aorta. It can also be done at bedside and no sedation is required. It may also identify complications of aortic dissection including heart failure, pericardial effusion with possible cardiac tamponade, and aortic valve regurgitation or other valve disorders. Transesophageal echocardiography has a sensitivity of 96.8% and specificity of 100% in the diagnosis of aortic dissections. It is also able to assess the descending aorta in the thorax. It can also assess the aortic valve and other heart valves, as well as assess the true lumen or false lumin of aortic dissections, which can help guide surgical repair planning and options. Transesophageal echocardiography requires the person to be sedated.
=== Initiation === Before considering the propagation of action potentials along axons and their termination at the synaptic knobs, it is helpful to consider the methods by which action potentials can be initiated at the axon hillock. The basic requirement is that the membrane voltage at the hillock be raised above the threshold for firing. There are several ways in which this depolarization can occur.
In January 2013, Politburo Standing Committee member Liu Yunshan referred to Xi's speech for the 18th Party National Congress as the "General Secretary Xi Jinping's Series of Important Speeches". In October 2017, the CCP Central Committee announced that Xi's political philosophies were developed into the "Xi Jinping Thought on Socialism with Chinese Characteristics for a New Era". Xi first made mention of the "Thought on Socialism with Chinese Characteristics for a New Era" in his opening day speech delivered to the 19th Party Congress in October 2017. His Politburo Standing Committee colleagues, in their own reviews of Xi's keynote address at the Congress, prepended the name "Xi Jinping" in front of "Thought". On 24 October 2017, at its closing session, the 19th Party Congress approved the incorporation of Xi Jinping Thought into the Constitution of the CCP, while in March 2018, the National People's Congress amended the state constitution to include Xi Jinping Thought.
In the 1990s, the German Federal Intelligence Service (BND) obtained a sample of one Novichok agent from a Russian scientist, and the sample was analysed in Sweden, according to a 2018 Reuters report. The chemical formula was given to Western NATO countries, who synthesized it, then used small amounts to test protective equipment, detection of it, and antidotes to it. Novichok was referred to in a patent filed in 2008 for an organophosphorus poisoning treatment. The University of Maryland, Baltimore research was funded in part by the U.S. Army. Professor Leonid Rink, who said he had participated in the creation of Novichok agents, confirmed that the structures leaked by Mirzayanov were the correct ones. Rink was himself convicted in Russia for illegally selling a Novichok agent used in 1995 to assassinate a banker, Ivan Kivelidi, and his secretary. David Wise, in his book Cassidy's Run, implies that the Soviet program may have been the unintended result of misleading information, involving a discontinued American program to develop a nerve agent code named "GJ", that was fed by a double agent to the Soviets as part of Operation Shocker.
== Further reading == May RM, Anderson RM (1991). Infectious diseases of humans: dynamics and control. Oxford: Oxford University Press. ISBN 0-19-854040-X. Vynnycky E, White RG, eds. (2010). An Introduction to Infectious Disease Modelling. Oxford: Oxford University Press. ISBN 978-0-19-856576-5. Capasso V (2008). Mathematical Structures of Epidemic Systems. 2nd Printing. Heidelberg: Springer. ISBN 978-3-540-56526-0. Carlson CS, Rubin DM, Heikkilä V, Postema M (2021). "Extracting transmission and recovery parameters for an adaptive global system dynamics model of the COVID-19 pandemic". 2021 IEEE Africon (PDF). pp. 456–459. doi:10.1109/AFRICON51333.2021.9570946. ISBN 978-1-6654-1984-0. S2CID 239899862.
Sources: en.wikipedia.org
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.
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。
天然胸腺素α1主要从胸腺组织提取，也可在脾脏和淋巴结中检出。目前研究和临床使用的多为化学合成版本，不再依赖动物组织。
胸腺素组分5是牛胸腺提取物的粗组分，包含多种肽。胸腺素α1是其中一种被纯化和表征的单一肽，具有明确的28个氨基酸序列。