If you have been reading about 细胞因子 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 2026-05-24. Where a claim depends on a specific study, the study is described rather than over-claimed.
Storage recommendations center on low temperature, dryness, and protection from repeated freezing and thawing. The intact powder is commonly held at 20 degrees below zero Celsius or colder, while a working solution is divided into single-use aliquots to limit freeze-thaw cycles. Buffered saline or phosphate-buffered saline at neutral pH is frequently used as a diluent. Light sensitivity is not well documented, yet amber vials or foil wrapping are common practice for long-term storage of peptide stocks.
Identity and purity are assessed with a small set of standard peptide methods. Reversed-phase high-performance liquid chromatography separates the main peak from truncated or oxidized species, and its area percentage is the usual purity measure. Mass spectrometry confirms the observed molecular mass against the expected value, while amino acid analysis or peptide mapping checks composition and sequence. Specifications for research-grade material are often stated as 95 percent or higher, though the exact limit depends on the supplier and the intended use.
Laboratory supplies of the peptide usually arrive as a lyophilized powder in sealed vials. The powder is hygroscopic, so a vial should be allowed to reach room temperature before it is opened to prevent condensation on the contents. Weighing and transfer are best performed in a low-humidity environment with clean tools. Once dissolved, the solution should be mixed gently rather than vortexed, because foaming and shear can reduce recovery of the peptide.
Identity and purity are usually checked by reverse-phase high-performance liquid chromatography, which separates the intact chain from truncated products, together with mass spectrometry for confirmation of the expected mass. Peptide mapping after enzymatic digestion and amino acid analysis add sequence-level evidence. Release testing also covers water content, residual solvents, and counter-ions, all of which influence measured mass and stability. Related-peptide limits are commonly expressed as a percentage of total peak area, with individual unspecified impurities held below a lower threshold.
The lyophilized peptide is a white to off-white powder that dissolves freely in water and in aqueous buffers near neutral pH. Because the molecule carries a net negative charge under physiological conditions, saline and phosphate solutions are the usual vehicles, while strongly acidic media are avoided. Stock solutions are commonly divided into small aliquots so that repeated freezing and thawing can be limited, since cycling may encourage aggregation. Solubility in organic solvents is poor and those solvents are seldom used as primary diluents.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white lyophilized powder | Hygroscopic; let the vial equilibrate before opening |
| Solubility | Freely soluble in water and aqueous buffers | Working solutions are often prepared between 0.1 and 1 mg per mL |
| Typical storage temperature | At or below 20 degrees below zero Celsius | Desiccant and sealed vials reduce moisture uptake |
| Routine purity assay | Reversed-phase HPLC with ultraviolet detection | Result reported as percentage of total peak area |
| Identity check | Mass spectrometry with amino acid analysis | Observed mass is compared with the calculated value |
The peptide occurs naturally in thymic tissue and has been detected in serum and other biological fluids. Reported concentrations are low, and reliable measurement generally requires immunoassay or mass spectrometry with an enrichment step. It is released from a larger precursor, prothymosin alpha, by proteolytic cleavage, although the enzymes involved are not fully characterized. Whether circulating levels reflect thymic output specifically remains an open question.
Thymosin alpha 1 is a 28-amino-acid peptide first isolated from thymosin fraction 5, a bovine thymic extract. Its sequence begins with an acetylated serine residue and carries a high proportion of acidic residues, so the molecule has a net negative charge near neutral pH. Despite the shared name, it is unrelated in sequence to the thymosin beta family. Synthetic material prepared by solid-phase peptide synthesis is identical in sequence to the natural peptide.
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。
在信号层面，Tα1可能通过Toll样受体等模式识别受体发挥作用。部分实验显示，它能激活髓样分化因子88依赖的通路，进而促进核因子κB进入细胞核。这导致白细胞介素2、干扰素γ和白细胞介素12等细胞因子的转录增加。这些细胞因子偏向辅助性T细胞1型应答，有助于细胞免疫。然而，具体受体和结合位点尚未完全确定，不同实验模型的结果存在差异。
The peptide lacks cysteine, methionine, and tryptophan, so disulfide scrambling and sulfur oxidation are not major degradation routes. Instead, aspartate residues can undergo isomerization or cyclization to succinimide intermediates, generating isoaspartate variants. Hydrolysis of peptide bonds also occurs slowly in solution. These changes may reduce biological activity even when the main peak remains detectable. Stability studies therefore track both potency and the appearance of related substances.
Lyophilized thymosin alpha 1 is typically stored refrigerated at 2 to 8 degrees Celsius and kept away from light. Reconstituted solutions are less stable and are usually used promptly after preparation. Repeated freeze-thaw cycles are avoided because they can promote aggregation and loss of activity. The peptide adsorbs to some plastic and glass surfaces, so a carrier protein is often added to dilute working solutions. Manufacturer instructions and published protocols both govern handling.
Identity and purity testing for thymosin alpha 1 relies mainly on reversed-phase high-performance liquid chromatography and mass spectrometry. Chromatography separates the parent peptide from truncated or modified variants, while mass spectrometry confirms the expected molecular mass. Amino acid analysis and peptide mapping provide additional sequence confirmation. Counterion content, water content, and residual solvents are measured separately as part of specification testing. No single method captures every attribute, so laboratories combine several techniques.
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.
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.
=== Anticoagulant medications === Anticoagulants may be started if the TIA is thought to be attributable to atrial fibrillation. Atrial fibrillation is an abnormal heart rhythm that may cause the formation of blood clots that can travel to the brain, resulting in TIAs or ischemic strokes. Atrial fibrillation increases stroke risk by five times, and is thought to cause 10-12% of all ischemic strokes in the US. Anticoagulant therapy can decrease the relative risk of ischemic stroke in those with atrial fibrillation by 67% Direct acting oral anticoagulants (DOACs), such as apixaban, are as effective as warfarin while also conferring a lower risk of bleeding. Generally, anticoagulants and antiplatelets are not used in combination, as they result in increased bleeding risk without a decrease in stroke risk. However, combined antiplatelet and anticoagulant therapy may be warranted if the patient has symptomatic coronary artery disease in addition to atrial fibrillation. Sometimes, myocardial infarction ("heart attack") may lead to the formation of a blood clot in one of the chambers of the heart. If this is thought to be the cause of the TIA, people may be temporarily treated with warfarin or another anticoagulant to decrease the risk of future stroke.
Ebselen (also called PZ 51, DR3305, and SPI-1005), is a synthetic organoselenium molecule under preliminary investigation as a drug candidate. It belongs to the class of compounds related to benzene and its derivatives. It is being developed by the Seattle biotechnology company, Sound Pharmaceuticals, Inc. It has also been reported to target tubulin, blocking its polymerization. Ebselen has been entered into clinical trials as a lead compound intended for the potential treatment of various diseases. Its most advanced clinical trial is a Phase III study in people with Meniere's disease, completed in July 2024. In vitro, ebselen is a mimic of glutathione peroxidase and reacts with peroxynitrite. It is purported to have antioxidant and anti-inflammatory properties.
The AAS that have been used most commonly in medicine are testosterone and its many esters (but most typically testosterone undecanoate, testosterone enanthate, testosterone cypionate, and testosterone propionate), nandrolone esters (typically nandrolone decanoate and nandrolone phenylpropionate), stanozolol, and metandienone (methandrostenolone). Others that have also been available and used commonly but to a lesser extent include methyltestosterone, oxandrolone, mesterolone, and oxymetholone, as well as drostanolone propionate (dromostanolone propionate), metenolone (methylandrostenolone) esters (specifically metenolone acetate and metenolone enanthate), and fluoxymesterone. Dihydrotestosterone (DHT), known as androstanolone or stanolone when used medically, and its esters are also notable, although they are not widely used in medicine. Boldenone undecylenate and trenbolone acetate are used in veterinary medicine. Designer steroids are AAS that have not been approved and marketed for medical use but have been distributed through the black market. Examples of notable designer steroids include 1-testosterone (dihydroboldenone), methasterone, trenbolone enanthate, desoxymethyltestosterone, tetrahydrogestrinone, and methylstenbolone.
==== Protein folding ==== A polypeptide chain in the cell does not have to stay linear; it can become branched or fold in on itself. Polypeptide chains fold in a particular manner depending on the solution they are in. The fact that all amino acids contain R groups with different properties is the main reason proteins fold.
There are many different kinds of antibody and their production is highly complex, involving several types of lymphocyte, but in general lymphocytes and other antibody regulating and producing cells will migrate to the lymph nodes to aid in the release of these antibodies into the bloodstream. On the other hand, there are natural killer cells; these cells have the ability to take down threats that are larger in size, such as bacteria, parasites, and tumor cells. A separate study found that cortisol effectively disarmed natural killer cells, downregulating the expression of their natural cytotoxicity receptors. Prolactin has the opposite effect. It increases the expression of cytotoxicity receptors on natural killer cells, increasing their potency. Cortisol stimulates many copper enzymes (often to 50% of their total potential), including lysyl oxidase, an enzyme that cross-links collagen and elastin. Especially valuable for immune response is cortisol's stimulation of the superoxide dismutase, since this copper enzyme is almost certainly used by the body to permit superoxides to poison bacteria. Some viruses, such as influenza and SARS-CoV-1 and SARS-CoV-2, are known to suppress the secretion of stress hormones to avoid the organism's immune response. These viruses suppress cortisol by producing a protein that mimics the human ACTH hormone but is incomplete and does not have hormonal activity. ACTH is a hormone that stimulates the adrenal gland to produce cortisol and other steroid hormones.
Sources: en.wikipedia.org
Several historical varieties of laudanum exist, including Paracelsus' laudanum, Sydenham's Laudanum (also known as tinctura opii crocata), benzoic laudanum (tinctura opii benzoica), and deodorized tincture of opium (the most common contemporary formulation), among others. Depending on the version, additional amounts of the substances and additional active ingredients (e.g. saffron, sugar, eugenol) are added, modifying its effects (e.g., amount of sedation, or antitussive properties). There is probably no single reference that lists all the pharmaceutical variations of laudanum that were created and used in different countries during centuries since it was initially formulated. The reasons are that in addition to official variations described in pharmacopeias, pharmacists and drug manufacturers were free to alter such formulas. The alcohol content of Laudanum probably varied substantially; on the labels of turn-of-the-century bottles of Laudanum, alcoholic content is stated as 48%. In contrast, the current version of Laudanum contains about 18% alcohol. The four variations of laudanum listed here were used in the United States during the late 19th century. The first, from an 1870 publication, is "Best Turkey opium 1 oz., slice, and pour upon it boiling water 1 gill, and work it in a bowl or mortar until it is dissolved; then pour it into the bottle, and with alcohol of 70 percent proof 1⁄2 pt., rinse the dish, adding the alcohol to the preparation, shaking well, and in 24 hours it will be ready for use.
A Loner addresses the themes of depression and the need for isolation, as Chanut was affected by these issues during the lockdown period, which coincided with the writing of the album. "A Thousand Miles Away", the last song on the album, marked the onset of Chanut's depression; the lyrics he wrote were about his father's death. David stated that A Loner's musical approach and themes addressed are "purely personal" and that the lyrics "evoke despair without making it an end in itself." "Dark, brooding and unapologetically downbeat on record", wrote Kerrang!'s Sam Law. In 2025, Toufouti stated that he found it interesting to elaborate on a sad individual or subject, as he felt there was material to develop. Saddiction continued in the vein of A Loner by being "more personal, more introspective", said Chanut. Before entering the studio, Toufouti slightly reworked the lyrics of "Neglect" to evoke his relationship with his father, who had just passed away. Lemaire wrote that the song's title, "Kowloon Lights", as well as the large block of buildings on the front cover of Sadditcion, point to a city theme. Chanut responded by elaborating on the feeling of loneliness in crowds, particularly in large cities like Paris, as well as on the mobile phone culture where everyone is focused on their own things. "Kowloon Lights" refers to the former densely populated enclave within the Hong Kong colony. Chanut commented on the grey buildings that made up the city and its colourful neon lights, often depicted in many Hong Kong films of the 1980s.
==== State level ==== As of February 2023, at least 32 (of 50) states have announced or enacted bans on state government agencies, employees, and contractors using TikTok on government-issued devices. State bans only affect government employees and do not prohibit civilians from having or using the app on their personal devices.
== Utility in prediction == The utility of the criteria in determining the prognosis of patients with acute liver failure is defined by their operating characteristics. The positive predictive value of the criteria in predicting death from acute liver failure has ranged from 70% to 100%. A Canadian meta-analysis assessing various prognostic indices found that the specificity of the King's College criteria in predicting mortality exceeded 90%, with a sensitivity of 69%. As a result, the American Society for Study of Liver Diseases has recommended the King's College Criteria as being helpful early parameters in ascertaining the need for liver transplantation in patients with acute liver failure.
First, the nucleophilicity of Ser-195 is enhanced by general-base catalysis in which the proton of the serine hydroxyl group is transferred to the imidazole moiety of His-57 during its attack on the electron-deficient carbonyl carbon of the protein-substrate main chain (k1 step). This occurs via the concerted action of the three-amino-acid residues in the catalytic triad. The buildup of negative charge on the resultant tetrahedral intermediate is stabilized in the enzyme's active site's oxyanion hole, by formation of two hydrogen bonds to adjacent main-chain amide-hydrogens. The His-57 imidazolium moiety formed in the k1 step is a general acid catalyst for the k-1 reaction. However, evidence for similar general-acid catalysis of the k2 reaction (Tet2) has been controverted; apparently water provides a proton to the amine leaving group. Breakdown of Tet1 (via k3) generates an acyl enzyme, which is hydrolyzed with His-57 acting as a general base (kH2O) in formation of a tetrahedral intermediate, that breaks down to regenerate the serine hydroxyl moiety, as well as the protein fragment with the newly formed carboxyl terminus.
Sources: en.wikipedia.org
Aliquots are typically frozen well below zero Celsius and thawed only once, since repeated cycles promote aggregation and loss. Dilution into a neutral buffer limits degradation during short working periods, and prolonged storage at room temperature is avoided.
Research material is commonly offered at 95 percent purity or above by chromatographic area, with some suppliers listing 98 percent. Higher grades usually carry a higher price and are chosen when the assay is sensitive to trace impurities.
Mass spectrometry is the standard check, often paired with amino acid analysis or peptide mapping. A chromatographic retention time alone is generally considered insufficient for structural confirmation.
Reconstituted solutions are typically kept refrigerated at two to eight degrees Celsius when used within a short window, or frozen in aliquots for longer periods. Repeated freeze-thaw cycles are avoided because they can reduce recovery of intact peptide.