BDNF 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 2025-11-04. Numbers and descriptions here follow the published literature rather than marketing material.
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。
Semax binds to melanocortin receptors and is thought to influence neuronal survival and plasticity rather than to act through the adrenal axis. Laboratory work has shown increased expression of brain-derived neurotrophic factor and nerve growth factor in treated tissue. Changes in c-Fos, a marker of neuronal activation, have also been reported. Because the peptide is rapidly degraded by peptidases, its effects are generally attributed to downstream signaling cascades rather than to sustained receptor occupancy.
Published studies are dominated by animal models of stroke, ischemia, and cognitive impairment, with a smaller number of human trials conducted in Russia. Many of the human reports are small, single-center, and published in Russian-language journals, which limits independent scrutiny. Outcome measures vary between studies and often rely on clinician-rated scales rather than objective biomarkers. Systematic reviews have noted the methodological weaknesses and called for larger, preregistered trials before firm conclusions can be drawn.
| Property | Value | Notes |
|---|---|---|
| 化学类别 | 合成七肽 | ACTH(4-10) 结构类似物 |
| 氨基酸序列 | Met-Glu-His-Phe-Pro-Gly-Pro | 单字母写作 MEHFPGP |
| 分子量 | 约 813.9 Da | 随确切形式和盐型略有变化 |
| 常见同义词 | ACTH(4-10) 类似物 | 俄语文献称 Семакс |
| 开发来源 | 俄罗斯 | 二十世纪八十年代 |
Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro. It was derived from the ACTH(4-10) fragment, a short segment of adrenocorticotropic hormone that lacks the hormonal activity associated with the full-length peptide. Researchers at the Institute of Molecular Genetics in Moscow developed the compound during the 1980s. It has been registered as a pharmaceutical product in Russia and several neighbouring countries, where it is supplied as a nasal solution, and it is also sold internationally as a research chemical.
The proposed mechanism centres on neurotrophic signalling rather than direct receptor activation. Semax is reported to increase expression of brain-derived neurotrophic factor and nerve growth factor in several brain regions, and to shift the balance between excitatory and inhibitory neurotransmitter systems. Interaction with melanocortin receptors has been suggested because of the parent ACTH fragment. Many of these findings come from rodent studies, and the extent to which they translate to human physiology remains an open question.
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.
Identity and purity are established with standard peptide methods. Reversed-phase HPLC with ultraviolet detection near 214 nm resolves the parent peak from deletion and truncation byproducts, and reports typically quote a main-peak percentage. Mass spectrometry by electrospray or MALDI-TOF confirms the expected molecular mass, while amino acid analysis or peptide mapping can verify composition when the sequence itself is in question. A certificate of analysis that pairs a chromatogram with a mass spectrum is more informative than a purity figure alone. Counter-ion content and residual solvents are separate specifications and are frequently omitted.
=== 7 May === The SBU announced that it had foiled a Russian plot to assassinate Zelenskyy and several senior Ukrainian military leaders and arrested two Ukrainian government protection unit colonels on suspicion of involvement. One person was killed by Russian shelling in Sumy Oblast. Russian-installed officials in Luhansk claimed that five people were injured in a fire caused by a Ukrainian missile strike on an oil depot. Ukrainian media reported that the HUR carried out a cyberattack on the Russian software firm 1C Company.
The voltage-gated sodium channels of arachnids are quite similar to those of insects, so based on the effect pompilidotoxins have on insect sodium channels, it is thought that the toxin will also slow the inactivation of those of arachnids. This slow inactivation could affect the locomotion of arachnids that they need to attack by disrupting the synchronised firing of neurons.
== Etymology == The term parenchyma is Neo-Latin from the Ancient Greek word παρέγχυμα parenchyma meaning 'visceral flesh', and from παρεγχεῖν parenkhein meaning 'to pour in' from παρα- para- 'beside' + ἐν en- 'in' + χεῖν khein 'to pour'. Originally, Erasistratus and other anatomists used it for certain human tissues. Later, it was also applied to plant tissues by Nehemiah Grew.
Sources: en.wikipedia.org
In 1299, according to the Malay Annals, the Kingdom of Singapura was founded on the island by Sang Nila Utama. Although the historicity of the accounts as given in the Malay Annals is the subject of academic debates, it is nevertheless known from various documents that Singapore in the 14th century, then known as Temasek, was a trading port under the influence of both the Majapahit Empire and the Siamese kingdoms, and was a part of the Indosphere. These Indianised kingdoms were characterised by surprising resilience, political integrity and administrative stability. Historical sources also indicate that around the end of the 14th century, its ruler Parameswara was attacked by either the Majapahit or the Siamese, forcing him to move to Malacca where he founded the Sultanate of Malacca. Archaeological evidence suggests that the main settlement on Fort Canning Hill was abandoned around this time, although a small trading settlement continued in Singapore for some time afterwards. In 1613, Portuguese raiders burned down the settlement, and the island faded into obscurity for the next two centuries. By then, Singapore was nominally part of the Johor Sultanate. The wider maritime region and much trade was under Dutch control for the following period after the 1641 Dutch conquest of Malacca.
=== Presentation === Xigris is the current brand name of activated drotrecogin alfa, manufactured by Eli Lilly. The drug is sold in vials containing either 5 mg or 20 mg, respectively. The drug was approved by the United States' Food and Drug Administration (FDA) in 2001, and the European Medicines Agency (EMA), the Australian Therapeutic Goods Administration in 2002 and the Health Canada in 2003.
He was also listed in GQ India's "Best Dressed Men" rankings in 2010, 2012, 2015, and 2017. In 2023, he was placed 19th in 30 All Time Famous Bollywood Actors of All Time. Moreover, he was inducted into the Gladrags Hall of Fame.
Sources: en.wikipedia.org
Adrien-Marie Legendre at PlanetMath. The True Face of Adrien-Marie Legendre (Portrait of Legendre) Biography at Fermat's Last Theorem Blog References for Adrien-Marie Legendre (in French) Eléments de géométrie (Paris : F. Didot, 1817) Elements of geometry and trigonometry, from the works of A. M. Legendre. Revised and adapted to the course of mathematical instruction in the United States, by Charles Davies. (New York: A. S. Barnes & co., 1858) : English translation of the above text Mémoires sur la méthode des moindres quarrés, et sur l'attraction des ellipsoïdes homogènes (1830) Théorie des nombres (Paris : Firmin-Didot, 1830) Traité des fonctions elliptiques et des intégrales eulériennes (Paris : Huzard-Courcier, 1825–1828) Nouvelles Méthodes pour la Détermination des Orbites des Comètes (Paris : Courcier, 1806) Essai sur la Théorie des Nombres (Paris : Duprat, 1798) Exercices de Calcul Intégral V.3 (Paris : Courcier, 1816) Correspondance mathématique avec Legendre in C. G. J. Jacobis gesammelte Werke (Berlin: 1852)
=== Thiazole-Orange-Based DNA Dyes === Thiazole Orange derivatives, such as SYBR Safe, SYBR Green, SYBR Gold, Pico Green, SYTO-16, SYTO-9 and TOPhBu are special cyanine dyes commonly used as fluorescent DNA sensors. The ability of the dyes to detect DNA at low concentrations was evaluated using two metrics: absolute fluorescence enhancement (AFE) and relative fluorescence enhancement (RFE).
In September 2020, the European Medicines Agency (EMA) endorsed the use of dexamethasone in adults and adolescents, from twelve years of age and weighing at least 40 kilograms (88 lb), who require supplemental oxygen therapy. Dexamethasone can be taken by mouth or given as an injection or infusion (drip) into a vein. In November 2020, the Public Health Agency of Canada's Clinical Pharmacology Task Group recommended dexamethasone for hospitalized patients requiring mechanical ventilation. Although dexamethasone, and other glucocorticoids, reduce mortality in COVID-19 they have also been associated with an increased risk of secondary infections, secondary infections being a significant issue in critically ill COVID-19 patients. The mechanism of action of dexamethasone involves suppression of late-stage interferon type I programs in severe COVID-19 patients.
Cohn (1993), assistant secretary for strategy, planning, analysis & risk of the United States Department of Homeland Security Amit Bose (1994), acting administrator of the Federal Railroad Administration Karthik Ramanathan (1994), acting assistant secretary of the treasury for financial markets Frank Scaturro (1994), lawyer, public advocate who spearheaded the restoration of Grant's Tomb; Republican candidate for New York's 4th congressional district Radhika Fox (1995), acting assistant administrator for water of the United States Environmental Protection Agency Beto O'Rourke (1995), U.S. congressman for Texas's 16th congressional district and candidate in the 2020 United States presidential election Rebekah Gee (1997), secretary of the Louisiana Department of Health, daughter of Ohio State University president E. Gordon Gee Jay Carson (1999), executive director of C40 Cities Climate Leadership Group; former press secretary for Hillary Clinton and Howard Dean's presidential campaigns John Ray Clemmons (1999), member of the Tennessee House of Representatives from the 55th district George Demos (1999), former U.S.
Sources: en.wikipedia.org
不是。Semax 是完全人工合成的七肽，自然界中没有对应的已知肽段。它的设计灵感来自促肾上腺皮质激素片段 ACTH(4-10)，但序列经过了替换和延长。
Semax 被描述为 ACTH(4-10) 的结构类似物，两者共享部分序列特征。它保留了该片段的部分神经相关活性方向，但去除了完整片段带来的激素释放效应。二者并非同一物质，也不能互相替代。
加入的 Pro-Gly-Pro 三肽被普遍认为能提升分子对蛋白水解酶的稳定性。这种设计让短肽在体内维持时间更长。具体延长的程度以及不同组织中是否一致，文献中仍存在不同报告。
It is associated with the melanocortin receptor family, particularly subtypes found in the central nervous system. This interaction is separate from the adrenal pathway activated by full-length ACTH.