synthetic heptapeptide comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Updated 2025-11-19. Numbers and descriptions here follow the published literature rather than marketing material.
Semax 是人工设计的七肽，序列为 Met-Glu-His-Phe-Pro-Gly-Pro，骨架取自促肾上腺皮质激素片段 ACTH(4-10)。它于二十世纪八十年代在苏联的分子遗传学研究机构内合成。设计目标是保留该片段与注意力和记忆相关的活性，同时剔除促皮质激素释放等内分泌作用。此后俄罗斯将其登记为药品并进入临床使用。
当时的短肽研究普遍关注能否穿越血脑屏障、在低剂量下产生中枢效应，Semax 属于这一路线。鼻内给药是其主要使用方式，俄语文献报道的适应症涵盖缺血性卒中、短暂性脑缺血发作、认知功能减退以及视神经病变。这些研究大多发表在当地期刊上，样本规模与终点设置同西方试验惯例存在差异，国际同行对其临床证据的强度看法不一。
多数实验室与市售的 Semax 以冻干粉形式提供。冻干粉通常建议保存在 -20 °C 或更低温度下，同时避免光照与反复升温。短期运输有时采用冷藏条件，但长期保存仍以冷冻为主。分包操作应尽量减少开盖次数，以降低吸湿和微生物污染的风险。开封后若未一次用完，建议在干燥环境中密封并尽快放回低温储存。
溶液状态的稳定性明显低于冻干粉。肽类在水溶液中可能经历水解、氧化与聚集，其中甲硫氨酸和天冬酰胺等残基常是敏感位点。Semax 含有甲硫氨酸，因此氧化风险相对突出。工作液一般主张现配现用，或冷藏并在数日内用尽。缓冲液种类、pH 和离子强度都会影响降解速率，而关于最佳条件的公开数据并不统一。
常规纯度与身份确认依赖反相高效液相色谱，并辅以质谱测定分子量。氨基酸组成分析可用于验证序列构成，肽图分析则能进一步定位修饰或降解产物。杂质谱通常关注缺失序列肽、截短片段和氧化产物。不同方法的检出限并不相同，因此各实验室报告的纯度数值不宜直接横向比较。
| Property | Value | Notes |
|---|---|---|
| 结构类别 | 线性合成七肽 | 无环化结构，不含二硫键 |
| 氨基酸序列 | Met-Glu-His-Phe-Pro-Gly-Pro | N 端为甲硫氨酸 |
| 分子量 | 约 814 Da | 游离碱形式的计算值 |
| 外观 | 白色至类白色粉末 | 具吸湿性 |
| 溶解性 | 易溶于水 | 亦可溶于甲醇等极性溶剂 |
Semax is a synthetic peptide created in the Soviet Union during the early 1980s by researchers working in Moscow. It was built from the short adrenocorticotropic hormone fragment known as ACTH(4-10), and the chain was then extended with three additional amino acids. The resulting molecule was named semax and entered clinical use in Russia in 1994. It is generally described as a nootropic and neuroprotective agent rather than as a hormone analogue.
The parent fragment ACTH(4-10) carries the sequence Met-Glu-His-Phe-Arg-Trp-Gly. Semax replaces the arginine and tryptophan positions with a proline-glycine-proline tail, giving Met-Glu-His-Phe-Pro-Gly-Pro. That change removes residues associated with adrenal stimulation, so the peptide does not drive cortisol release the way full ACTH does. This distinction shapes how the compound is grouped in the literature, where it sits with neuropeptides and peptide neuromodulators rather than with corticosteroids.
Semax is normally supplied as a lyophilized powder, and that form is the most stable. Suppliers commonly recommend storage at -20 °C in a desiccated container protected from light, with short-term handling at room temperature limited to weighing and transfer. Powder that has absorbed moisture degrades faster, so vials should be warmed to ambient temperature before opening to prevent condensation on the contents. Hygroscopic behavior is typical of short hydrophilic peptides, and humidity control matters more than temperature alone for long-term retention.
Once dissolved, the peptide is considerably less stable than the solid. Aqueous solutions are usually prepared at neutral to slightly acidic pH, filtered, and divided into single-use aliquots before freezing. Repeated freeze-thaw cycles are a common cause of avoidable loss and are best prevented by never refreezing a thawed aliquot. Adsorption to plastic and glass surfaces can lower the measured concentration of dilute solutions, particularly below roughly 0.1 mg/mL. Buffer choice, salt content, and container material all influence how much peptide remains detectable after storage.
Semax is a synthetic heptapeptide whose sequence is Met-Glu-His-Phe-Pro-Gly-Pro. The first four residues correspond to the ACTH(4-10) fragment, while the terminal Pro-Gly-Pro extension was added to improve metabolic stability. Its molecular formula is C37H51N9O10S and its monoisotopic mass is approximately 813.9 Da. The compound is classified as a peptide research chemical and as a registered pharmaceutical product in Russia, but it does not hold marketing approval in the European Union or the United States. Naming conventions vary across supplier catalogs.
Development of the compound took place in the Soviet Union during the 1980s, largely through peptide research groups affiliated with the Shemyakin-Ovchinnikov Institute and Moscow State University. Investigators screened fragments of adrenocorticotropic hormone for activity on the central nervous system while attempting to separate cognitive effects from hormonal ones. The shortened sequence was selected because it retained behavioral activity in animal models without stimulating corticosteroid release. Early publications described the molecule as an ACTH(4-10) analog.
Published research covers ischemic stroke, traumatic brain injury, cognitive impairment, optic nerve conditions and attention-related measures. Much of the human evidence comes from small trials conducted in one country, which limits how far the results generalize. Animal models supply the larger share of the data, and effects seen in rodents do not transfer automatically to people. Reviews have noted that methodological reporting is often incomplete, making it difficult to pool results or compare treatment schedules across studies.
Pharmacokinetic accounts emphasize rapid breakdown. After intravenous dosing the intact peptide disappears from blood within minutes, and nasal delivery produces low but measurable concentrations. Metabolites rather than the parent molecule may account for part of the observed activity, although the relative contribution is unresolved. Dosing in the literature varies widely and no optimal schedule has been agreed. These gaps are regularly cited as a reason the findings have not produced broad clinical adoption beyond the original research setting.
=== Absorption and distribution === Oral bioavailability of trimebutine is nearly 100% for the maleate salt. Maximum serum concentration (Cmax) is achieved after 30 minutes for 100 mg dose and 0.88 h for 200 mg dose. The level of serum albumin binding is minimal. Half-life (t1/2) of 200 mg timebutine maleate is equal to 2.77 h.
When a significant region around a crack tip has undergone plastic deformation, other approaches can be used to determine the possibility of further crack extension and the direction of crack growth and branching. A simple technique that is easily incorporated into numerical calculations is the cohesive zone model method which is based on concepts proposed independently by Barenblatt and Dugdale in the early 1960s. The relationship between the Dugdale-Barenblatt models and Griffith's theory was first discussed by Willis in 1967. The equivalence of the two approaches in the context of brittle fracture was shown by Rice in 1968.
To reduce pain the use of an exercise program of 13 to 24 weeks is recommended, with each session lasting 30 to 60 minutes. When different exercise programs are compared, aerobic exercise is capable of modulating the autonomic nervous function of fibromyalgia patients, whereas resistance exercise does not show such effects. A 2022 meta-analysis found that aerobic training showed a high effect size while strength interventions showed moderate effects. Meditative exercise seems preferable for improving sleep, with no differences between resistance, flexibility, and aquatic exercise in their favorable effects on fatigue.
Sources: en.wikipedia.org
Interstitial lung disease (ILD), or diffuse parenchymal lung disease (DPLD), is a group of respiratory diseases affecting the interstitium (the tissue) and space around the alveoli (air sacs) of the lungs. It concerns alveolar epithelium, pulmonary capillary endothelium, basement membrane, and perivascular and perilymphatic tissues. It may occur when an injury to the lungs triggers an abnormal healing response. Ordinarily, the body generates just the right amount of tissue to repair damage, but in interstitial lung disease, the repair process is disrupted, and the tissue around the air sacs (alveoli) becomes scarred and thickened. This makes it more difficult for oxygen to pass into the bloodstream. The disease presents itself with the following symptoms: shortness of breath, nonproductive coughing, fatigue, and weight loss, which tend to develop slowly, over several months. While many forms are progressive and serious, some types of ILD remain mild or stable for extended periods, especially with early detection and appropriate treatment. The average rate of survival for someone with this disease is between three and five years. The term ILD is used to distinguish these diseases from obstructive airways diseases. There are specific types in children, known as children's interstitial lung diseases. The acronym ChILD is sometimes used for this group of diseases. In children, the pathophysiology involves a genetic component, exposure-related injury, autoimmune dysregulation, or all of the components.
Zolpidem, sold under the brand name Ambien among others, is a medication primarily used for the short-term treatment of sleeping problems. Guidelines recommend that it be used only after cognitive behavioral therapy for insomnia and after behavioral changes, such as sleep hygiene, have been tried. It decreases the time to sleep onset by about fifteen minutes and at larger doses helps people stay asleep longer. It is taken by mouth and is available as conventional tablets, extended-release tablets, or sublingual tablets. Common side effects include daytime sleepiness, headache, nausea, and diarrhea. More severe side effects include memory problems and hallucinations. While flumazenil, a GABAA receptor antagonist, can reverse zolpidem's effects, usually supportive care is all that is recommended in overdose. Zolpidem is a nonbenzodiazepine, or Z-drug, which acts as a sedative and hypnotic as a positive allosteric modulator at the GABAA receptor. It is an imidazopyridine and increases GABA effects in the central nervous system by binding to GABAA receptors at the same location as benzodiazepines. It generally has a half-life of two to three hours. This, however, is increased in those with liver problems. Zolpidem was approved for medical use in the United States in 1992. It became available as a generic medication in 2007. Zolpidem is a schedule IV controlled substance in the US under the Controlled Substances Act of 1970 (CSA). In 2023, it was the 54th most commonly prescribed medication in the United States, with more than 11 million prescriptions.
All chordates are deuterostomes. Which means, during embryonic development, the anus forms before the mouth does. All chordates are based on a bilateral body plan. All chordates are coelomates, and have a fluid-filled body cavity (coelom) with a complete serosal lining derived from mesoderm called mesothelium (see Brusca and Brusca).
Sources: en.wikipedia.org
=== Medication considerations === Some medications require attention when in a state of ketosis, especially several classes of diabetes medication. SGLT2 inhibitor medications have been associated with cases of euglycemic ketoacidosis – a rare state of high ketones causing a metabolic acidosis with normal blood glucose levels. This usually occurs with missed insulin doses, illness, dehydration or adherence to a low-carbohydrate diet while taking the medication. Additionally, medications used to directly lower blood glucose including insulin and sulfonylureas may cause hypoglycemia if they are not titrated prior to starting a diet that results in ketosis.
When Victoria regains consciousness, she comes across a group of survivors who blame her for the destruction of the town and decide to leave. Saddened that the people she saved have come to hate her, Victoria wonders what to do next. The vision of her mother suggests that she should return to India and find her real mother, who may still be alive.
== Quantification == Today, HPLC with UV-detection is the reference-method (e.g. DIN 10751–3). Classic methods for the quantification of HMF in food use photometry. The method according to White is a differential UV-photometry with and without sodium bisulfite-reduction of HMF. Winkler photometric method is a colour-reaction using p-toluidine and barbituric acid (DIN 10751–1). Photometric test may be unspecific as they may detect also related substances, leading to higher results than HPLC-measurements. Test-kits for rapid analyses are also available (e.g. Reflectoquant HMF, Merck KGaA).
Sources: en.wikipedia.org
不存在。它是依据 ACTH 的一段序列人工设计的分子，天然蛋白质中找不到与之完全相同的七肽。名称属于研究代号，而非天然物质名。
Semax 对应 ACTH 第 4 至第 10 位的片段，并在两端做了替换与延长，使其不再具备促肾上腺皮质激素的典型内分泌活性。这一改动同时改变了它在体内的稳定性与分布特征。
俄罗斯将其列为处方药物，需要医生开具处方。多数其他国家把它当作研究化合物，不能作为药品销售或宣称疗效。具体合法性取决于当地法规。
一般不建议常温长期保存。多数说明指向 -20 °C 冷冻避光。常温运输通常被视为短期可接受，但会加快降解风险。