semax raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
Reviewed 2026-02-14. Anything still debated is marked as such rather than presented as settled.
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。
The compound was developed during the 1980s at the Institute of Molecular Genetics in Moscow as part of research on fragments of adrenocorticotropic hormone. Early work examined short ACTH-derived sequences that retained neurotrophic effects while lacking the endocrine activity of the full hormone. Semax entered clinical use in Russia during the 1990s, where it received registration for several neurological indications. Outside that region it remained primarily a laboratory research material rather than an approved therapeutic. English-language literature on it grew more slowly and frequently cited the original Russian studies.
Terminology around the compound varies by source. It appears in catalogues and papers as Semax, as the heptapeptide ACTH(4-7)-Pro-Gly-Pro, and under various alphanumeric laboratory codes used by individual suppliers. These names refer to the same sequence but may imply different salt forms, purity grades, or counter-ions. Peptide databases usually list the free base mass, while product descriptions sometimes report acetate or trifluoroacetate salts with a different formula weight. Because naming conventions for research peptides are not standardised across vendors, checking the declared sequence and measured mass is more reliable than relying on a trade name alone.
| Property | Value | Notes |
|---|---|---|
| 外观 | 白色至类白色粉末 | 常见于冻干制剂 |
| 溶解度 | 易溶于水 | 在极性溶剂中一般也可溶 |
| 建议储存温度 | -20 °C | 冻干粉，避光密封 |
| 常见分析手段 | 反相高效液相色谱 | 常与质谱联用 |
| 主要降解路径 | 水解与氧化 | 溶液状态更显著 |
从分子层面看，Semax 是线性七肽，没有二硫键、糖基或脂链修饰，N 端为游离氨基，C 端为游离羧基。分子含组氨酸与谷氨酸侧链，因此在水和甲醇等极性溶剂中溶解良好，在非极性溶剂中溶解有限。计算分子量约为 814 Da，与其质子化离子的质荷比吻合，可用于质谱确认。
稳定性主要由水解与氧化两条路径支配。肽键在中性或弱酸性条件下相对稳定，遇到强碱或长时间高温则明显断裂；甲硫氨酸侧链容易被氧化成亚砜，使主峰前移并拉低实际含量。金属离子、光照和反复冻融会进一步促进降解或聚集。冻干粉在低温避光条件下可存放较长时间，配制后的水溶液通常需要冷藏并尽快用完。
纯度评估以反相高效液相色谱为主，通过主峰面积百分比给出粗略结果，再配合电喷雾质谱核对分子量。氨基酸分析可验证组成比例，手性色谱或毛细管电泳用于检查残基构型。常见杂质包括缺失序列的短肽、氧化产物与二聚体。由于多数市售品不附带完整检验报告，独立第三方检测常被用来核实标称值。
Laboratory work points toward modulation of neurotrophic signaling, particularly expression of brain-derived neurotrophic factor and nerve growth factor in hippocampal tissue. Studies also describe effects on monoamine turnover, inflammatory mediators, and oxidative markers. These observations come mainly from animal models and cultured cells, so the causal chain in humans is not firmly established. Whether the reported molecular changes translate into measurable clinical benefit is an open question. Reviews generally present the mechanism as plausible rather than demonstrated.
Clinical evidence consists largely of small trials with modest sample sizes, often without independent replication. Reported endpoints include cognitive scores, recovery after stroke, and visual function, but study designs vary widely and few trials meet contemporary reporting standards. Systematic reviewers have noted a high risk of bias in several of these reports. No large multicenter trial conducted outside Russia has been published. The compound is therefore best described as investigational in most jurisdictions, with its clinical role still unresolved.
Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro. Its chain combines the first seven residues of corticotropin with a C-terminal proline-glycine-proline extension, a modification intended to slow enzymatic breakdown. The free peptide has a molecular mass near 813.9 daltons. It belongs to the class of ACTH-derived fragments studied for central nervous system activity rather than for adrenal steroid stimulation. This structural relationship to a natural hormone fragment is the usual starting point for describing the compound in the literature.
Apixaban, sold under the brand name Eliquis among others, is an anticoagulant medication used to treat and prevent blood clots and to prevent stroke in people with nonvalvular atrial fibrillation through directly inhibiting factor Xa. It is used as an alternative to warfarin to prevent blood clots following hip or knee replacement and in those with a history of prior clots and does not require monitoring by blood tests or dietary restrictions. It is taken by mouth. Common side effects include bleeding and nausea. Other side effects may include bleeding around the spine and allergic reactions. Use is not recommended during pregnancy or breastfeeding. Use appears to be relatively safe in those with mild kidney problems. Compared to warfarin it has fewer interactions with other medications. It is a direct factor Xa inhibitor. In 2007, Pfizer and Bristol-Myers Squibb began the development of apixaban as an anticoagulant. Apixaban was approved for medical use in the European Union in May 2011, and in the United States in December 2012. It is on the World Health Organization's List of Essential Medicines. In 2023, it was the 28th most commonly prescribed medication in the United States, with more than 19 million prescriptions. It is available as a generic medication, although not in the United States.
There are other applications of this method where the PdII complexes were generated as PdII-peptide OACs by introducing 4-halophenylalanine into peptides during SPPS to achieve peptide-peptide or peptide-protein ligation.
In electromagnetic theory, the continuity equation is an empirical law expressing (local) charge conservation. Mathematically it is an automatic consequence of Maxwell's equations, although charge conservation is more fundamental than Maxwell's equations. It states that the divergence of the current density J (in amperes per square meter) is equal to the negative rate of change of the charge density ρ (in coulombs per cubic meter),
=== Release of prostaglandins from the cell === Prostaglandins were originally believed to leave the cells via passive diffusion because of their high lipophilicity. The discovery of the prostaglandin transporter (PGT, SLCO2A1), which mediates the cellular uptake of prostaglandin, demonstrated that diffusion alone cannot explain the penetration of prostaglandin through the cellular membrane. The release of prostaglandin has now also been shown to be mediated by a specific transporter, namely the multidrug resistance protein 4 (MRP4, ABCC4), a member of the ATP-binding cassette transporter superfamily. Whether MRP4 is the only transporter releasing prostaglandins from the cells is still unclear.
Sources: en.wikipedia.org
=== Screening === In China, Web-technologies were used to direct individuals to appropriate resources. Infrared thermal cameras are used to detect individuals with fever. Machine learning has been used for diagnosis and risk prediction.
== See also == List of pre-Columbian cultures Domesticated plants of Mesoamerica Agriculture in Mesoamerica Mesoamerican cuisine Mesoamerican diet and subsistence Mesoamerican architecture Indigenous music of North America Painting in the Americas before European colonization Mesoamerican chronology History portal North America portal Central America portal South America portal
=== Mitochondrial redox carriers === Energy associated with the transfer of electrons down the electron transport chain is used to pump protons from the mitochondrial matrix into the intermembrane space, creating an electrochemical proton gradient (ΔpH) across the inner mitochondrial membrane. This proton gradient is largely but not exclusively responsible for the mitochondrial membrane potential (ΔΨM). It allows ATP synthase to use the flow of H+ through the enzyme back into the matrix to generate ATP from adenosine diphosphate (ADP) and inorganic phosphate. Complex I (NADH coenzyme Q reductase; labeled I) accepts electrons from the Krebs cycle electron carrier nicotinamide adenine dinucleotide (NADH), and passes them to coenzyme Q (ubiquinone; labeled Q), which also receives electrons from Complex II (succinate dehydrogenase; labeled II). Q passes electrons to Complex III (cytochrome bc1 complex; labeled III), which passes them to cytochrome c (cyt c). Cyt c passes electrons to Complex IV (cytochrome c oxidase; labeled IV). Four membrane-bound complexes have been identified in mitochondria. Each is an extremely complex transmembrane structure that is embedded in the inner membrane. Three of them are proton pumps. The structures are electrically connected by lipid-soluble electron carriers and water-soluble electron carriers. The overall electron transport chain can be summarized as follows:
Sources: en.wikipedia.org
Upon his return to the United States in 1973, he became deputy commander for operations at George Air Force Base, California. In 1974 he was assigned as vice commander at Nellis Air Force Base, Nevada, where he flew as an aggressor pilot. He then transferred to Tactical Air Command at Langley Air Force Base in 1975 as director of fighter and reconnaissance operations. In 1976 and 1977 he was assistant to the commander there. Chain became the military assistant to the Secretary of the Air Force in 1978. He then served as deputy director of plans at Air Force headquarters until 1980, when he became director of operations. Chain was assigned as assistant deputy chief of staff for plans and operations in 1981 and became deputy chief of staff for plans and operations in 1982. He served as director of the Bureau of Political-Military Affairs for the Department of State from 1984 until 1985, when he became chief of staff for Supreme Headquarters Allied Powers Europe in Belgium. On July 1, 1985, Chain was promoted to general. In 1986 he became commander in chief of Strategic Air Command, where he oversaw the LGM-118A Peacekeeper operations for the Reagan Administration. He retired from the military on January 31, 1991.
The Wnt signaling pathway can be divided in canonical and non-canonical. The canonical signaling involves binding of Wnt to Frizzled and LRP5 co-receptor, leading to GSK3 phosphorylation and inhibition of β-catenin degradation, resulting in its accumulation and translocation to the nucleus, where it acts as a transcription factor. The non-canonical Wnt signaling can be divided in planar cell polarity (PCP) pathway and Wnt/calcium pathway. It is characterized by binding of Wnt to Frizzled and activation of G proteins and to an increase of intracellular levels of calcium through mechanisms involving PKC 50. The Wnt signaling pathway plays a significant role in osteoblastogenesis and bone formation, inducing the differentiation of mesenquimal pluripotent cells in osteoblasts and inhibiting the RANKL/RANK pathway and osteoclastogenesis.
The GRP RNA motif is a conserved RNA structural element identified in introns of glycine-rich RNA-binding protein genes, including GRP7 and GRP8. It is associated with alternative splicing and nonsense-mediated decay (NMD). GRP RNA motif has been reported as a cis-regulatory element, that modulates binding of GRP7 and GRP8 proteins to their RNA targets. The motif is predicted to form a stem-loop structure of approximately 20 base pairs. An alternative 5′ splice site is located near the base of the stem, suggesting that RNA structure may influence splice-site accessibility. In Arabidopsis thaliana (At), AtGRP7 and AtGRP8 are circadian clock-regulated RNA-binding proteins that form an interlocked auto-regulatory and cross-regulatory feedback network based on alternative splicing and NMD of their own pre-mRNAs, contributing to circadian output regulation, were transcript levels oscillate with a daily rhythm. GRP7 and GRP8 are also involved in regulating flowering time. Homologous motifs of GRP RNA motif have been identified in multiple plant species within the Pentapetalae clade.
‰ Peedee Belemnite ("PDB"), a fossil belemnite from the eponym Late Cretaceous geological formation in North and South Carolina (USA), was the original reference standard used for standardizing carbon isotope ratio values. Due to the depletion of the original PDB, an artificial "Vienna PDB" standard, or "VPDB", is generally used today.
Sources: en.wikipedia.org
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。
公开资料对此没有统一答案。普遍建议现配现用，或冷藏并在数日内用完。含甲硫氨酸的序列更易氧化，放置时间越长风险越高。
反相高效液相色谱是最常用的手段，配合质谱确认分子量。氨基酸组成分析和肽图分析可补充序列层面的验证。
It is a synthetic seven-amino-acid peptide built from the ACTH(4-7) sequence plus a Pro-Gly-Pro tail. It belongs to the family of short ACTH fragments studied for nervous-system effects. Its backbone contains only standard amino acids.