The short version of BDNF expression fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2026-01-19. 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.
==== Chinese diaspora in the West ==== The Chinese Diaspora in the West (1800s to 1949) first began to flourish during the 19th century due to famine and political upheaval, as well as rumors of wealth to be had outside of Southeast Asia. Chinese emigrants to cities such as San Francisco, London, and New York City brought with them the Chinese manner of opium smoking, and the social traditions of the opium den. The Indian Diaspora distributed opium-eaters in the same way, and both social groups survived as "lascars" (seamen) and "coolies" (manual laborers). French sailors provided another major group of opium smokers, having gotten the habit while in French Indochina, where the drug was promoted and monopolized by the colonial government as a source of revenue. Among white Europeans, opium was more frequently consumed as laudanum or in patent medicines. Britain's All-India Opium Act of 1878 formalized ethnic restrictions on the use of opium, limiting recreational opium sales to registered Indian opium-eaters and Chinese opium-smokers only and prohibiting its sale to workers from Burma. Likewise, in San Francisco, Chinese immigrants were permitted to smoke opium, so long as they refrained from doing so in the presence of whites. Because of the low social status of immigrant workers, contemporary writers and media had little trouble portraying opium dens as seats of vice, white slavery, gambling, knife- and revolver-fights, and a source for drugs causing deadly overdoses, with the potential to addict and corrupt the white population.
Biden was a longtime member of the Senate Committee on the Judiciary. He chaired it from 1987 to 1995 and was a ranking minority member from 1981 to 1987 and again from 1995 to 1997. As chair, Biden presided over two highly contentious U.S. Supreme Court confirmation hearings. When Robert Bork was nominated in 1988, Biden reversed his approval—given in an interview the previous year—of a hypothetical Bork nomination. Conservatives were angered, but at the hearings' close Biden was praised for his fairness, humor, and courage. Rejecting the arguments of some Bork opponents, Biden framed his objections to Bork in terms of the conflict between Bork's strong originalism and the view that the U.S. Constitution provides rights to liberty and privacy beyond those explicitly enumerated in its text. Bork's nomination was rejected in the committee by a 5–9 vote and then in the full Senate, 42–58. During Clarence Thomas's nomination hearings in 1991, Biden's questions on constitutional issues were often convoluted to the point that Thomas sometimes lost track of them, and Thomas later wrote that Biden's questions were akin to "beanballs". After the committee hearing closed, the public learned that Anita Hill had accused Thomas of making unwelcome sexual comments when they had worked together. Biden had known of some of these charges, but initially shared them only with the committee because Hill was then unwilling to testify.
=== Computing === .MSI, the filename extension of Windows Installer packages Medium scale integration, a generation of integrated circuit chips which contain hundreds of transistors Message Signaled Interrupts, a PCI 2.2 interrupt-mechanism MSI protocol, a basic cache-coherence protocol used in multiprocessor systems
Sources: en.wikipedia.org
Albert Pike lost confidence in Cassard's performance. In 1861, he sent another Cuban named Vicente Antonio de Castro back to Cuba to take over and "...regularize any error that Andres Cassard might have committed in organizing the bodies of Cuba, and to establish that peace and harmony that should exist among the ancients in the Ancient and Accepted Scottish Rite." Albert Pike and the Grand Lodge of South Carolina became increasingly embroiled in the American Civil War. Pike served as a General in the Confederate States Army, and de Castro began acting more autonomously. Instead of withdrawing from Freemasonry, however, Pike sought to make Confederate South Carolina the epicentre of the entire Masonic world. de Castro, when he observed the currents within Colon Freemasonry, saw that even though the Grand Lodge and the Supreme Council disagreed on much of the issues in society, they were mostly led by Spanish loyalists desiring that Spain remain a part of Cuba's future. Historians note the discord, because before the Civil War, Albert Pike had long been a proponent of Manifest destiny and a soldier in the Westward Expansion – but the Lodges he created were still loyal to Spain. Still at the forefront of the debate was the institution of slavery. On March 28, 1862, instead of co-organizing with the Colon bodies, de Castro created an entirely new body called the Supremo Consejo y Gran Oriente de Cuba y Las Antillas (GOCA) (English: Supreme Council and Grand Orient of Cuba and the Antilles).
=== Integrin binding === CCN1 binds directly to various integrin receptors in a cell type-dependent manner, including integrin αvβ3 in endothelial cells, α6β1 and heparan sulfate proteoglycans (HSPGs) in fibroblasts and smooth muscle cells αIIbβ3 in activated platelets, αMβ2 in monocytes and macrophages, and αDβ2 in macrophage foam cells. Where examined, syndecan-4 has been identified as the HSPG critical for CCN1 functions. The CCN1 binding sites for some of these integrins have been mapped (Figure 1). Due to the cell type specificity of integrin expression, CCN1 acts through distinct integrins to mediate specific functions in different types of cells. For example, CCN1 induces angiogenic functions in endothelial cells through αvβ3, and in fibroblasts promotes cellular senescence and enables TNFα to induce apoptosis through binding to α6β1-HSPGs. However, CCN1 supports cell adhesion through all of the integrins identified above.
For three years, there was an indecisive struggle between the heterogeneous Assembly and the president, who was silently awaiting his opportunity. He chose as his ministers men with little inclination towards republicanism, with a preference for Orléanists, the chief of whom was Odilon Barrot. In order to strengthen his position, he endeavoured to conciliate the reactionary parties, without committing himself to any of them. The chief instance of this was the expedition to Rome voted by the Catholics, to restore the temporal authority of Pope Pius IX, who had fled Rome in fear of the nationalists and republicans. (Garibaldi and Mazzini had been elected to a Constitutional Assembly.) The pope called for international intervention to restore him in his temporal power. The French president moved to establish the power and prestige of France against that of Austria, as beginning the work of European renovation and reconstruction which he already looked upon as his mission. French troops under Oudinot marched into Rome. This provoked an insurrection in Paris in favour of the Roman Republic, that of the Château d'Eau, which was crushed on 13 June 1849. On the other hand, when the pope, though only just restored, began to yield to the general movement of reaction, the president demanded that he should set up a Liberal government. The pope's dilatory reply having been accepted by the French ministry, the president replaced it on 1 November, by the Fould-Rocher cabinet.
Sources: en.wikipedia.org
However, the tropical Pacific experiences occasional shifts away from these average conditions. If the trade winds (blowing from east to west) are weaker than average, then both the upwelling in the East Pacific and the flow of warmer ocean surface waters towards the West Pacific lessen. This results in a cooler West Pacific and a warmer East Pacific, leading to a shift of cloud and rain towards the East Pacific. This situation is called El Niño. The opposite occurs if trade winds are stronger than average, leading to a warmer West Pacific and a cooler East Pacific. This situation is called La Niña and is associated with increased cloudiness and rainfall over the West Pacific.
There are many reasons why an excited state can be metastable. The most common mechanism is by suppression of gamma decay of excited nuclei, making the decay route a forbidden transition. Spin is conserved, and a photon has spin 1 ħ. Thus, if a decay route would require a change of ≥ 2 ħ (any possible change is always integer) in angular momentum, then the gamma decay would become highly suppressed. For example, if the decay requires the nucleus to change spin by 2 ħ, then it must emit 2 photons at once. This is a 3-body interaction, which is much weaker than a 2-body interaction, and thus occurs at a much lower rate. In general, each additional unit of spin larger than 1 that the emitted gamma ray must carry inhibits decay rate by about 5 orders of magnitude. As the excited energy state lowers, eventually internal conversion (IC) and internal pair production (IP) takes over. The decay of 180mTa from spin-9 state to spin-2 state changes spin by 7 ħ. This suppresses the rate of gamma emission so much that the decay rate is essentially equal to the rate of IC, in agreement with the above. When the nucleus begins and ends with 0 spin, it cannot decay via single photo gamma emission. The only possible routes are IC, internal pair production, or two-photon gamma emission. Usually IC and IP dominates over two-photon gamma emission.
Iodine-131 (131I, I-131) is a radioisotope of iodine discovered by Glenn Seaborg and John Livingood in 1938 at the University of California, Berkeley. It has a radioactive decay half-life of about eight days. It is associated with nuclear energy, medical diagnostic and treatment procedures, and natural gas production. It also plays a major role as a radioactive isotope present in nuclear fission products, and was a significant contributor to the health hazards from open-air atomic bomb testing in the 1950s, and from the Chernobyl disaster, as well as being a large fraction of the contamination hazard in the first weeks in the Fukushima nuclear crisis. This is because 131I is a major fission product of uranium and plutonium, comprising nearly 3% of the total products of fission (see fission product yield). Due to its beta decay, iodine-131 causes mutation and death in cells that it penetrates, and other cells up to several millimeters away. For this reason, high doses of the isotope are sometimes less dangerous than low doses, since they tend to kill thyroid tissues that would otherwise become cancerous as a result of the radiation. For example, children treated with moderate dose of 131I for thyroid adenomas had a detectable increase in thyroid cancer, but children treated with a much higher dose did not. Likewise, most studies of very-high-dose 131I for treatment of Graves' disease have failed to find any increase in thyroid cancer, even though there is linear increase in thyroid cancer risk with 131I absorption at moderate doses.
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.