The short version of Lyophilisation fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2025-12-13. Anything still debated is marked as such rather than presented as settled.
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。
Identity and purity of semax are established with reversed-phase high-performance liquid chromatography coupled to ultraviolet detection, usually at 214 nanometres. Mass spectrometry, most often electrospray ionisation in positive mode, confirms the molecular mass and reveals truncated sequences. Amino acid analysis and peptide mapping after enzymatic digestion provide additional structural confirmation. Laboratories typically report purity as the percentage area of the main peak, a figure that does not capture isomeric or oxidised variants unless the method resolves them.
The peptide is prone to several degradation pathways. Oxidation of the methionine residue produces a sulfoxide that elutes close to the parent peak in many chromatographic systems. Hydrolysis of peptide bonds and deamidation of susceptible residues in related sequences also reduce purity over time. Lyophilised material kept dry at minus twenty degrees Celsius and shielded from light is the most stable form commonly described in laboratory practice.
| 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 是一种人工合成的七肽，氨基酸序列为 Met-Glu-His-Phe-Pro-Gly-Pro，单字母缩写记作 MEHFPGP。它被归类为促肾上腺皮质激素片段 ACTH(4-10) 的结构类似物，但并不天然存在于生物体内。母体片段 ACTH(4-10) 的序列为 Met-Glu-His-Phe-Arg-Trp-Gly，Semax 替换了中间两个残基，并在羧基端延长了 Pro-Gly-Pro 三肽。这种延长被普遍认为能提升分子对肽酶的耐受性。
该化合物于二十世纪八十年代在俄罗斯被开发，相关工作由俄罗斯科学院分子遗传学研究所的研究团队主导。开发目标并非复制 ACTH 的完整激素活性，而是寻找保留其神经作用方向、同时去除促肾上腺皮质激素释放效应的短肽片段。研究记录显示，这一方向促成了多个相关短肽的合成与筛选，而 Semax 是其中被研究最广泛的一个。当地文献常以 Семакс 这一名称指代它。
The mechanisms attributed to semax are inferred from animal and cell studies rather than traced to one confirmed target. The most frequently cited pathway involves increased expression of brain-derived neurotrophic factor and nerve growth factor in hippocampal and cortical tissue. Some work points to engagement of melanocortin receptors, particularly MC4, which the parent ACTH fragment can activate. Effects on dopaminergic and serotonergic signalling have also been reported. No single account explains all observed results, and the relative weight of each pathway remains unsettled.
Published studies examine a fairly narrow set of endpoints. Rodent experiments commonly measure maze learning, infarct volume after induced ischemia, and tissue levels of neurotrophic factors. Clinical reports from Russian centres describe attention, memory and recovery scores in patients after stroke or transient ischemic attack. Most of those human studies are small and few have been repeated by independent groups. Outcome measures differ between studies, which limits direct comparison.
==== Analysis of archaeologic materials ==== Direct insertion electron ionization mass spectrometry (direct insertion EI-MS) has been used for the identification of archeological adhesives such as tars, resins and waxes found during excavations on archeological sites. These samples are typically investigated using gas chromatography–MS with extraction, purification, and derivatization of the samples. Due to the fact that these samples were deposited in prehistoric periods, they are often preserved in small amounts. By using direct insertion EI–MS archaeological samples, ancient organic remains like pine and pistacia resins, birch bark tar, beeswax, and plant oils as far from bronze and Iron Age periods were directly analyzed. The advantage of this technique is that the required amount of sample is less and the sample preparation is minimized. Both direct insertion-MS and gas chromatography-MS were used and compared in a study of characterization of the organic material present as coatings in Roman and Egyptian amphoras can be taken as an example of archeological resinous materials. From this study, it reveals that, the direct insertion procedure seems to be a fast, straightforward and a unique tool which is suitable for screening of organic archeological materials which can reveal information about the major constituents within the sample. This method provides information on the degree of oxidation and the class of materials present. As a drawback of this method, less abundant components of the sample may not be identified.
Venezuelan defense minister Vladimir Padrino López said that US combat helicopters fired rockets and missiles in urban areas and that officials were working to gather information on the number of fatalities and injuries. Padrino López also stated that most of Maduro's personal guard were killed during the attack. The New York Times reported on 3 January 2026 that an anonymous Venezuelan official said at least 40 people, including civilians and military personnel, were killed in the attack, updated to 80 on 4 January, "according to a senior Venezuelan official". Independent Venezuelan journalistic reports confirmed that most Venezuelan dead were among members of the presidential guard, with two civilian deaths. The presence of Cuban troops in Venezuela was made public after the attack. Their presence was denied as far back as 2008. In 2019 Maduro had claimed in an interview that no Cuban military personnel were stationed in the country and that his personal guard was Venezuelan. Trump indicated that Cuban forces were involved in the operation, stating: "You know, a lot of Cubans were killed yesterday." The government of Cuba reported that 32 Cubans were killed in Venezuela, all members of armed forces and intelligence services. One of the most senior Cuban soldiers that died, Colonel Humberto Roca, was responsible for Fidel Castro's security in the past. According to Reuters reporting in February, anonymous Venezuelan officials indicated that some Cuban security forces and medical doctors in Venezuela were returning to Cuba, diminishing their role in Venezuelan politics.
=== Genetic heterogeneity === Historically, "Ca. M. multicellularis" was thought to be entirely clonal due to its synchronous cell division. However, single-consortium metagenome (SCM) sequencing has revealed that the individual cells within each organism are genetically heterogeneous. The constituent cells feature distinct single-nucleotide polymorphisms (SNPs) situated randomly across their genomes.
Sources: en.wikipedia.org
==== The storage iron pool ==== Iron can be stored in ferritin as ferric iron due to the ferroxidase activity of the ferritin heavy chain. Dysfunctional ferritin may accumulate as hemosiderin, which can be problematic in cases of iron overload. The ferritin storage iron pool is much larger than the labile iron pool, ranging in concentration from 0.7 mM to 3.6 mM.
2024 United Kingdom riots: Two 12-year-old boys become the youngest people to be convicted following their involvement in the disorder. Figures show that 125 migrants crossed the English Channel in small boats. 13 August Banknotes featuring King Charles, with a face value of £78,430 and low serial numbers, are auctioned for £914,127 to raise money for charity. An inquest is held into the death of former England cricketer Graham Thorpe, who died from suicide after being struck by a train at a railway station. Data from the Office for National Statistics shows UK unemployment fell to 4.2% in the three months to June, down from 4.4% during the previous quarter. Ofgem approves a £3.4bn project for a subsea cable allowing renewable energy to be transported from Scotland to England more easily. 14 August Inflation is reported to have risen from 2% to 2.2%, the first increase during 2024. The predicted increase is largely a result of a smaller fall in gas and electricity prices in July when compared to July 2023. 2024 United Kingdom riots: A 53-year-old woman from Cheshire is sentenced to 15 months in prison after admitting sending a communication threatening death or serious harm over a Facebook post in which she suggested a mosque should "be blown up with the adults inside". Two men found in a burned-out car in Malmö, Sweden, are confirmed as two British men, Farooq Abdulrazak, 37, and Juan Cifuentes, 33, who went missing in July. Train drivers' union ASLEF is to ballot its members on a revised pay offer following negotiations with the Department for Transport.
== Evolution == Some 23-million-year-old fossils of arapaima or a very similar species have been found in the Miocene Villavieja Formation of Colombia. Museum specimens are found in France, England, the United States, Brazil, Guyana, Ecuador and Perú. This makes them some of the oldest known species of freshwater fish.
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。
Reversed-phase high-performance liquid chromatography is the standard method, with detection in the ultraviolet range. Peak area percentage yields a purity figure for the main component. Mass spectrometry is normally run alongside to confirm molecular identity.