intranasal delivery is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Updated 2026-07-31. 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。
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.
Kant thus concluded that even if people did not desire to leave anarchy, they ought to as a matter of duty to abide by universal laws. Kant also gave a short definition of anarchy in contrast to other forms of society:
=== Complications === Pulp acts as a security and alarm system. Slight decay in tooth structure not extending to the dentin may not alarm the pulp, but as the dentin gets exposed, due either to dental caries or trauma, sensitivity starts. The dentinal tubules pass the stimulus to the pulp's odontoblastic layer, triggering the response. This mainly responds to cold. At this stage, simple restoration can be performed. As the decay progresses near the pulp, the response magnifies. Sensation to heat and cold increases. At this stage, indirect pulp capping may be advisable. At this stage it may be impossible to clinically diagnose the extent of decay. Carious dentin by dental decay progressing to the pulp may get fractured during mastication, traumatizing the pulp, resulting in pulpitis. Pulpitis can be painful and may call for root canal therapy or endodontic therapy. Traumatized pulp starts an inflammatory response. The hard and closed surroundings builds pressure inside the pulp chamber, compressing the nerve fibres and eliciting pain. At this stage, the pulp starts to die, progressing to periapical abscess formation (chronic pulpitis). Pulp horns recede with age. The pulp undergoes a decrease in intercellular substance, water, and cells as it fills with collagen fibers. This decrease in cells is evident in the reduced number of undifferentiated mesenchymal cells. The pulp becomes more fibrotic, reducing the regenerative capacity of the pulp due to the loss of these cells.
20 June – BBC One airs a Question Time election special featuring the leaders of the UK's four main political parties. Sunak says he is "incredibly angry" to learn of allegations that members of his party have betted on the date of the election, and that he will "boot out" anyone found to have broken the law. Scottish Parliament authorities have launched an investigation into the potential misuse of expenses to buy postage stamps by members of the SNP in order to send letters to voters. The Alliance Party launches its general election manifesto, with plans including reform of the devolved government at Stormont, and ringfencing funding for integrated eductation. 21 June – Nigel Farage tells the BBC that he believes the Russian invasion of Ukraine to have been precipitated by the West's eastward expansion of NATO and the European Union, but that the war itself is Vladimir Putin's fault. BBC Wales airs a televised election debate featuring Vaughan Gething (Labour), Jane Dodds (Liberal Democrat), Rhun ap Iorwerth (Plaid Cymru) and David TC Davies (Conservative). 22 June – BBC News publishes a list of eight Reform UK candidates who have made a wide range of offensive online posts about women between 2011 and 2023. Following criticism from other party leaders over his comments about Putin, Nigel Farage pens an op-ed in The Telegraph in which he says he has never been an "apologist or supporter" of Putin, but that "if you poke the Russian bear with a stick, don't be surprised if he responds".
Sources: en.wikipedia.org
== Molecular Structure of EAATs == Like all glutamate transporters, EAATs are trimers, with each protomer consisting of two domains : the central scaffold domain (Figure 1A, wheat) and the peripheral transport domain (Figure 1A, blue). The transport conformational path is as follows. First, the outward facing conformation occurs (OF, open) which allows the glutamate to bind. Then the HP2 region closes after uptake (OF, closed) and the elevator like movement carries the substrate to the intracellular side of the membrane. It worth nothing that this elevator motion consists of several yet to be categorized/identified conformational changes. After the elevator motion brings the substrate to the IC side of the membrane, EAAT adopts the inward facing (IF, closed) state in which the transport domain is lowered, but the HP2 gate is still closed with the glutamate still bound to the transporter. Lastly, the HP2 gate opens and the glutamate diffuses into the cytoplasm of the cell.
However, the "absolute zero" on the Kelvin temperature scale was originally defined in terms of the second law of thermodynamics, which Thomson himself described in 1852. Thomson did not assume that this was equal to the "zero-volume point" of Charles's law, merely said that Charles's law provided the minimum temperature which could be attained. The two can be shown to be equivalent by Ludwig Boltzmann's statistical view of entropy (1870). However, Charles also stated:
==== Regulation of release ==== Regulation of TRH release is regulated principally by a negative feedback loop by thyroid hormone, and a neuronal open loop by hypothalamic factors. TRH release is additionally regulated by other circulating hormones (including glucocorticoids, and oestrogens), and inhibited by cytokines. The tanycytes of the median eminence also exert a regulatory effect on TRH release.
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.