The short version of ACTH 片段 fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2025-10-17. Anything still debated is marked as such rather than presented as settled.
The C-terminal Pro-Gly-Pro extension is not incidental. Proline-rich tails are known to resist several common peptidases, and the published literature attributes the longer half-life of Semax, relative to unmodified ACTH fragments, to this feature. The modification also removes the melanocyte-stimulating and corticosteroidogenic activity that characterizes longer ACTH-derived sequences. Because the molecule is small and hydrophilic, it is typically formulated as an aqueous solution for intranasal or parenteral delivery. Acetylation or amidation at the termini appears in closely related research peptides and shifts the mass by a fixed increment.
Reported pharmacological work centers on neurotrophic signaling, including changes in BDNF and NGF expression in hippocampal tissue in animal models. Human data come largely from studies conducted in Russia, and how well those results generalize to other populations remains an open question. Regulatory status differs sharply by jurisdiction: Semax is a registered prescription medicine in Russia, while it holds no approved marketing status in the United States or the European Union. Outside such jurisdictions it is generally handled as a research chemical, which affects both documentation and quality expectations.
Semax is a synthetic heptapeptide whose sequence is Met-Glu-His-Phe-Pro-Gly-Pro. It was developed as a fragment analog of adrenocorticotropic hormone, modeled specifically on the ACTH(4-10) region. The first four residues reproduce that fragment, while a Pro-Gly-Pro tripeptide is appended at the C-terminus. Work on the compound originated in Russia, where it entered clinical use as an intranasal preparation. Its sequence places it among short regulatory peptides studied for effects on the central nervous system rather than on the adrenal axis.
各国监管态度分化明显。俄罗斯按处方药管理，部分东欧国家留有使用记录；欧盟与美国未批准其作为药物上市，市面流通品通常标注为研究用化学品。身份差异意味着标示含量、纯度与无菌性缺少统一核查。体育领域还牵涉反兴奋剂名录，跨境携带则受目的地药品法规约束。
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。
| Property | Value | Notes |
|---|---|---|
| Molecular weight | ~813.9 Da (free heptapeptide) | N-acetylated form is about 42 Da heavier |
| Residue count | 7 (heptapeptide) | Four residues from ACTH(4-10), three added |
| Appearance | White to off-white powder | Usually supplied lyophilized |
| Solubility class | Freely soluble in water | Also dissolves in DMSO and polar organic solvents |
| Related parent fragment | ACTH(4-10) | Parent motif is Met-Glu-His-Phe |
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.
Development took place during the 1980s at institutes of the Russian Academy of Sciences, where peptide fragments of ACTH were screened for cognitive and neuroprotective effects. The compound received regulatory approval in Russia as a nasal preparation, marketed for conditions such as ischemic stroke, transient ischemic attacks, and optic nerve disorders. Registration in other countries has not followed. Most published clinical reports originate from a small number of Russian research groups, and independent replication outside that setting remains limited. The regulatory status therefore differs sharply between Russia and the rest of the world.
The transition from wakefulness to sleep (REM sleep or NREM sleep) is associated with a reduction in upper-airway muscle tone. During REM sleep, the muscle tone of the throat and neck, as well as that of the vast majority of skeletal muscles, is almost completely relaxed. This allows the tongue and soft palate/oropharynx to relax, reducing airway patency and potentially impeding or completely obstructing air flow into the lungs during inspiration, resulting in reduced respiratory ventilation. If reductions in ventilation are associated with sufficiently low blood-oxygen levels or with sufficiently high breathing efforts against an obstructed airway, neurological mechanisms may trigger a sudden interruption of sleep, called a neurological arousal. This arousal can cause an individual to gasp for air and awaken. These arousals rarely result in complete awakening but can have a significant negative effect on the restorative quality of sleep. In significant cases of OSA, one consequence is sleep deprivation resulting from the repetitive disruption and recovery of sleep activity. This sleep interruption in Stage 3 NREM sleep (also called slow-wave sleep) and in REM sleep can interfere with normal growth patterns, healing, and immune response, especially in children and young adults. The fundamental cause of OSA is a blocked upper airway, usually behind the tongue and epiglottis, whereby the otherwise patent airway, in an erect, awake patient, collapses when the patient lies on his or her back and loses muscle tone upon entering deep sleep.
In 2011 the committee concluded that the presence of numerous uncertainties and knowledge gaps regarding the effects of heroin treatment meant that it could not recommend the introduction of heroin maintenance treatment in Norway. Critics of heroin maintenance programmes object to the high costs of providing heroin to people who use it. The British heroin study cost the British government £15,000 per participant per year, roughly equivalent to average person who uses heroin's expense of £15,600 per year. Drug Free Australia contrast these ongoing maintenance costs with Sweden's investment in, and commitment to, a drug-free society where a policy of compulsory rehabilitation of people who are experiencing drug addiction is integral, which has yielded to one of the lowest reported illicit drug use levels in the developed world, a model in which successfully rehabilitated people who use substances present no further maintenance costs to their community, as well as reduced ongoing health care costs. King's Health Partners notes that the cost of providing free heroin for a year is about one-third of the cost of placing the person in prison for a year.
==== Style periods ==== A broad classification of styles, formalized by Le Coq and Waldschmidt in 1933, has been generally accepted. The first style is called "Indo-Iranian style I", and cover all the early caves with delicate tone-on-tone paintings, using browns, oranges and greens. The name "Indo-Iranian" broadly denotes the artistic influence from India, combined with elements of Iranian art, that presided over the creation of the first cave paintings at Kizil. The main representative caves of this style are the Cave of the Hippocampi (Cave 118), the Cave of the Painters (Cave 207), the Peacock Cave (Cave 76), the Overpainted Cave (Cave 117), the Cave of the Statues (Cave 77), and the Cave of the Seafarers (Cave 112). The small group of the Treasure Cave (Cave 83, 84) is considered as contemporary, but in a slightly personal style, sometimes called "Special Style" (Sonderstil). The first style is only found in Kizil, except for one cave in nearby Kumtura: the Cave with the cupola. The second style is called "Indo-Iranian style II", and cover most of the other caves of Kizil, which use strongly contrasted colors and strong line strokes, using browns, oranges and greens and especially a vivid lapis-lazuli blue. The name "Indo-Iranian" again broadly denotes the artistic influence from India, combined with important influences from Central Asian and the Iranian world. This style is further divided in three broad periods. Finally, a third Uighur-Chinese style appears in only two caves at Kizil.
The formation of an astatine compound with hydrogen—usually referred to as hydrogen astatide—was noted by the pioneers of astatine chemistry. As mentioned, there are grounds for instead referring to this compound as astatine hydride. It is easily oxidized; acidification by dilute nitric acid gives the At0 or At+ forms, and the subsequent addition of silver(I) may only partially, at best, precipitate astatine as silver(I) astatide (AgAt). Iodine, in contrast, is not oxidized, and precipitates readily as silver(I) iodide. Astatine is known to bind to boron, carbon, and nitrogen. Various boron cage compounds have been prepared with At–B bonds, these being more stable than At–C bonds. Astatine can replace a hydrogen atom in benzene to form astatobenzene C6H5At; this may be oxidized to C6H5AtCl2 by chlorine. By treating this compound with an alkaline solution of hypochlorite, C6H5AtO2 can be produced. The dipyridine-astatine(I) cation, [At(C5H5N)2]+, forms ionic compounds with perchlorate (a non-coordinating anion) and with nitrate, [At(C5H5N)2]NO3. This cation exists as a coordination complex in which two dative covalent bonds separately link the astatine(I) centre with each of the pyridine rings via their nitrogen atoms. With oxygen, there is evidence of the species AtO− and AtO+ in aqueous solution, formed by the reaction of astatine with an oxidant such as elemental bromine or (in the last case) by sodium persulfate in a solution of perchloric acid.
== Interpretation == One study reviewed the relative diagnostic value of enzyme and bicarbonate concentrations compared with enzyme output in 363 secretin-CCK tests. The investigators also evaluated the requirement for perfusion markers to accurately quantify volume, and the validity of a shortened sampling time (first 20 minutes). Only 60 percent of volume was recovered with the duodenal aspiration tube, suggesting that marker perfusion to correct for distal loss of secretion is important to accurately quantify volume. Using a trypsin output <50 U/kg/h as the reference standard, measurement of enzyme concentration alone misclassified approximately 10 percent of patients. Use of a shortened collection time misclassified approximately 4 percent of patients. The authors concluded that this was an unacceptably high rate of misclassification and that the standard prolonged collection of fluid using a perfusion marker must be performed to accurately measure exocrine function.
Sources: en.wikipedia.org
Since January 2026, the United States has been imposing a fuel blockade on Cuba, causing an ongoing fuel shortage and economic crisis in the latter. As an island, Cuba heavily depends on importing petroleum to meet its energy needs, particularly from nearby Venezuela and Mexico. Following the 2026 United States intervention in Venezuela, in which U.S. forces ousted President Nicolás Maduro, Venezuelan oil exports to Cuba were cut off, leaving the country without adequate supply. In addition, the U.S. enacted a blockade on oil coming into Venezuela a month prior. The United States is reportedly motivated by a desire for regime change in Cuba by the end of 2026. The United States began blocking oil tankers heading to Cuba in February 2026, targeting companies such as the Mexican state-owned Pemex and threatening the responsible countries with tariffs should they resist. According to The New York Times later in February, this is the United States' first effective blockade of Cuba since the Cuban Missile Crisis. In January 2026, U.S. president Donald Trump called on Cuba to 'make a deal before it's too late'. Trump subsequently said the U.S. could implement a friendly takeover of Cuba. On 13 March 2026, Cuban Communist Party first secretary Miguel Díaz-Canel publicly confirmed for the first time that his government was engaged in diplomatic talks with the United States aimed at addressing the severe U.S.‑imposed oil and energy blockade that had left them facing crippling fuel shortages and widespread power outages.
Cryo-S Painless cryoanalgesia device is the next generation of apparatus used by many experts in the field since 1992. The working medium for Cryo-S Painless is carbon dioxide: CO2 (−78 °C) or nitrous oxide: N2O (−89 °C), very efficient and easy to use gases. Cryo-S Painless is controlled by a microprocessor and all the parameters are displayed and monitored on a LCD screen. Mode selection probe, cleaning and freezing can be performed automatically using footswitch or touch screen which allows to keep the site of a procedure under sterile conditions. Electronic communication (chip system) between the connected probe and device allows recognition of optimal operating parameters and auto-configures to cryoprobe characteristics. Pressure and gas flow are set automatically, any manual adjustment is not necessary. Cryoprobe temperature, cylinder pressure, gas flow inside of cryoprobe and procedure time are displayed during freezing. Built-in voice communication Built-in neurostimulation (sensory, motor).
for molecular models that are more realistic than rigid elastic spheres, such as those incorporating intermolecular attractions. Doing so is necessary to reproduce the correct temperature dependence of
== Amino acid metabolism in animals == Animals must metabolize proteins to amino acids, at the expense of muscle tissue, when blood sugar is low. The preference of liver transaminases for oxaloacetate or alpha-ketoglutarate plays a key role in funneling nitrogen from amino acid metabolism to aspartate and glutamate for conversion to urea for excretion of nitrogen. In similar manner, in muscles the use of pyruvate for transamination gives alanine, which is carried by the bloodstream to the liver (the overall reaction being termed glucose-alanine cycle). Here other transaminases regenerate pyruvate, which provides a valuable precursor for gluconeogenesis. This alanine cycle is analogous to the Cori cycle, which allows anaerobic metabolism by muscles.
Sources: en.wikipedia.org
=== Protists === A common protist eukaryotic expression system is the slime mold, Dictyostelium discoideum, and is unique as it has a circular plasmid, packaged similarly to chromatin. As a simple eukaryotic haploid organism, it can grow in high concentrations without the expensive conditions of mammalian cell culture, and perform post-translational modifications. The protein itself is expressed in several forms including as membrane attached, secreted, or cell associated, and can glycosylate protein product.
Zverev then lost in the first round of Wimbledon to Arthur Rinderknech in five sets, which marked the first time he lost in the first round of a major since 2019. Zverev reached the semifinals for the first time in Canada since winning the title in 2017 after defeating the defending champion Alexei Popyrin in the quarterfinals. He lost to the eventual finalist Karen Khachanov, despite holding a match point. He rebounded in Cincinnati by advancing to his 3rd consecutive semifinal in the American Midwest, which included wins against the recent finalists from Toronto the week before, Khachanov and Ben Shelton, both of whom were notably exhausted from their Canadian campaigns. Zverev, also struggling and exhausted in his semifinal against Carlos Alcaraz, went on to lose in straight sets. In New York, he was defeated in four sets by a resurgent Félix Auger-Aliassime. Before leaving the United States, Zverev participated in the Laver Cup with Team Europe in San Francisco but lost to Team World. In the Asian swing, Zverev was defeated by frequent rival Daniil Medvedev in the quarterfinals in Beijing, and by eventual finalist Arthur Rinderknech in the third round in Shanghai. Zverev returned to form in the European indoor swing, but found himself obstructed by Jannik Sinner for the remainder of the season, losing to him in the final in Vienna, the semifinals of Nanterre, and a round-robin match in Turin. At the Davis Cup Finals, Zverev won both of his singles matches, but Germany was defeated in the semifinal tie against Spain. He ended his season ranked world No.
Historically, when Cossack men fought in permanent wars far from home, women took over the role of family leaders. Women were also called upon to physically defend their villages and towns from enemy attacks. In some cases, they raided and disarmed neighboring villages composed of other ethnic groups. Leo Tolstoy described such Cossack female chauvinism in his novel, The Cossacks. Relations between the sexes within the stanitsas were relatively egalitarian. The American historian Thomas Barrett wrote "The history of Cossack women complicates general notions of patriarchy within Russian society". When the Malorossian Cossack regiments were disbanded, those Cossacks who were not promoted to nobility, or did not join other estates, were united into a civil Cossack estate. Sergei Korolev's mother was the daughter of a leader of the civil estate of the Zaporozhian Sich.
== Production == Selenium is most commonly produced from selenide in many sulfide ores, such as those of copper, nickel, or lead. Electrolytic metal refining is particularly productive of selenium as a byproduct, obtained from the anode mud of copper refineries. Dissolved selenite anions present in the electrolysis solution are also known to interfere with the electrorefining process of copper. Another source was the mud from the lead chambers of sulfuric acid plants, a process that is no longer used. Selenium can be refined from these muds by a number of methods. However, most elemental selenium comes as a byproduct of refining copper or producing sulfuric acid. Since its invention, solvent extraction and electrowinning (SX/EW) production of copper produces an increasing share of the worldwide copper supply. This changes the availability of selenium because only a comparably small part of the selenium in the ore is leached with the copper. Industrial production of selenium usually involves the extraction of selenium dioxide from residues obtained during the purification of copper. Common production from the residue then begins by oxidation with sodium carbonate to produce selenium dioxide, which is mixed with water and acidified to form selenous acid (oxidation step). Selenous acid is bubbled with sulfur dioxide (reduction step) to give elemental selenium. About 2,000 tonnes of selenium were produced in 2011 worldwide, mostly in Germany (650 t), Japan (630 t), Belgium (200 t), and Russia (140 t), and the total reserves were estimated at 93,000 tonnes.
=== Active site === Comparisons between bacterial, archaeal and eukaryotic ribosome structures reveal a very high degree of conservation in the active site region — the peptidyl transferase center (PTC). None of the eukaryote-specific protein elements is close enough to directly participate in catalysis. However, RPL29 projects to within 18Å of the active site in T. thermophila, and eukaryote-specific extensions interlink several proteins in the vicinity of the PTC of the 60S subunit, while the corresponding 50S proteins are singular entities.
Sources: en.wikipedia.org
The sequence is Met-Glu-His-Phe-Pro-Gly-Pro, a seven-residue peptide. The first four residues correspond to the ACTH(4-10) fragment, and Pro-Gly-Pro is added at the C-terminus. N-acetylated versions also appear in the literature and differ in mass.
Semax is a synthetic analog of the ACTH(4-10) fragment rather than a copy of the full hormone. Truncation plus the added tail removes the steroidogenic portion of ACTH. That distinction explains why it is studied for nervous-system effects instead of adrenal stimulation.
It is registered as a prescription product in Russia and has been used there clinically, chiefly by the intranasal route. No approval exists in the United States or the European Union. Availability elsewhere typically falls under research-chemical distribution, with varying purity documentation.
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。