The short version of ACTH(4-10) fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2026-06-19. 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.
常规纯度与身份确认依赖反相高效液相色谱，并辅以质谱测定分子量。氨基酸组成分析可用于验证序列构成，肽图分析则能进一步定位修饰或降解产物。杂质谱通常关注缺失序列肽、截短片段和氧化产物。不同方法的检出限并不相同，因此各实验室报告的纯度数值不宜直接横向比较。
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。
| 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 |
Russian regulatory authorities approved the peptide for nasal administration, and it remains listed in the national pharmacopoeia under several trade names. Documented indications include acute ischemic stroke, transient ischemic attacks, traumatic brain injury, and certain ophthalmological and neurological conditions. Physicians also prescribe it for cognitive complaints in older patients, although the evidence base for that use is thinner. Outside Russia and a few neighboring states, the substance is not an approved medicine and is sold instead as a research chemical.
Later generations of the molecule include an N-acetylated form and an amidated form, both marketed online alongside the parent peptide. These variants differ in terminal chemistry and stability, and they are frequently discussed in the same breath even though they have not been compared in controlled trials. Supply outside formal healthcare systems comes largely from laboratories that synthesize peptides to order. Purity and identity of these materials vary widely, and no single body oversees the international trade.
Identity and purity are commonly assessed by reversed-phase high-performance liquid chromatography, with ultraviolet detection near 214 nanometers for the peptide backbone. Mass spectrometry, either electrospray or matrix-assisted laser desorption, confirms molecular mass and detects truncation or modification products. Amino acid analysis can verify composition. Because the sequence contains no strongly absorbing aromatic residue apart from phenylalanine, detection wavelengths are chosen carefully. Purity values above 95 percent are typical for research-grade material.
Quality documentation for research-grade peptide usually includes a certificate of analysis stating purity, identity, and residual counterion content. Batch-to-batch variation in purity and salt form is a recognized issue, and comparisons across suppliers require attention to the exact counterion, for example acetate versus trifluoroacetate. Sequence verification by tandem mass spectrometry provides stronger evidence than a single mass measurement. For any study reporting biological results, the analytical method and the measured purity should be stated explicitly. Independent verification of supplier claims is considered good practice.
== Reproduction and life cycle == Most Hydras can reproduce sexually under certain conditions, though they typically choose to reproduce asexually instead. Unlike many members of the Hydrozoa, which alternate between the polyp form and the medusa form (the life stage where sexual reproduction occurs), Hydra never progress beyond the polyp phase in their life cycle. Instead, when food is plentiful, many Hydra opt to reproduce asexually by budding. A section of the body wall and an extension of the digestive cavity develop, creating a bud. The buds grow into miniature adults and break away when mature. When a Hydra is well fed, a new bud can form every two days. When conditions are harsh, often before winter or in poor feeding conditions, sexual reproduction then occurs in some Hydra. Either the ovaries or testes develop from interstitial cells of the epidermis, resulting in swellings in the body wall. The testes release free-swimming gametes into the water, and these can fertilize the egg in the ovary of another individual. The fertilized eggs secrete a tough outer coating, and, as the adult dies (due to starvation or cold), these resting eggs fall to the bottom of the lake or pond to await better conditions, whereupon they hatch into nymph Hydra. The male Hydra is typically smaller in size and bears 1 to 8 conical testes, while the female is larger and has 1 to 2 ovaries. Some Hydra species, like Hydra circumcincta and Hydra viridissima, are hermaphrodites and may produce both testes and ovaries at the same time.
Minimizing the number of hydrophobic side-chains exposed to water is an important driving force behind the folding process. The hydrophobic effect is the phenomenon in which the hydrophobic chains of a protein collapse into the core of the protein (away from the hydrophilic environment). In an aqueous environment, the water molecules tend to aggregate around the hydrophobic regions or side chains of the protein, creating water shells of ordered water molecules. An ordering of water molecules around a hydrophobic region increases order in a system and therefore contributes a negative change in entropy (less entropy in the system). The water molecules are fixed in these water cages which drives the hydrophobic collapse, or the inward folding of the hydrophobic groups. The hydrophobic collapse introduces entropy back to the system via the breaking of the water cages which frees the ordered water molecules. The multitude of hydrophobic groups interacting within the core of the globular folded protein contributes a significant amount to protein stability after folding, because of the vastly accumulated van der Waals forces (specifically London Dispersion forces). The hydrophobic effect exists as a driving force in thermodynamics only if there is the presence of an aqueous medium with an amphiphilic molecule containing a large hydrophobic region. The strength of hydrogen bonds depends on their environment; thus, H-bonds enveloped in a hydrophobic core contribute more than H-bonds exposed to the aqueous environment to the stability of the native state.
Speaking publicly about Biko's death, the country's police minister Jimmy Kruger initially implied that it had been the result of a hunger strike, a statement he later denied. His account was challenged by some of Biko's friends, including Woods, who said that Biko had told them that he would never kill himself in prison. Publicly, he stated that Biko had been plotting violence, a claim repeated in the pro-government press. South Africa's attorney general initially stated that no one would be prosecuted for Biko's death. Two weeks after the funeral, the government banned all Black Consciousness organisations, including the BCP, which had its assets seized. Both domestic and international pressure called for a public inquest to be held, to which the government agreed. It began in Pretoria's Old Synagogue courthouse in November 1977, and lasted for three weeks. Both the running of the inquest and the quality of evidence submitted came in for extensive criticism. An observer from the Lawyers' Committee for Civil Rights Under Law stated that the affidavit's statements were "sometimes redundant, sometimes inconsistent, frequently ambiguous"; David Napley described the police investigation of the incident as "perfunctory in the extreme". The security forces alleged that Biko had acted aggressively and had sustained his injuries in a scuffle, in which he had banged his head against the cell wall. The presiding magistrate accepted the security forces' account of events and refused to prosecute any of those involved.
==== Yeast ==== Yeast matches bacterial cells' cost-effectiveness, efficiency and technical feasibility. Moreover, yeast secretes soluble proteins and has the ability to perform post-translational modifications similar to mammalian cells.
This convinced Macleod to divert the whole laboratory to insulin research and to bring in the biochemist James Collip to help with purifying the extract. The first human clinical trial was unsuccessful. Banting was insufficiently qualified to participate and felt sidelined. By the winter of 1922, he was certain that all Macleod's colleagues were conspiring against him. There was a reported physical altercation between Banting and Collip, as Banting saw Collip's breakthrough on alcohol purification as a threat, while Collip was reluctant to share the details. Collip threatened to leave because of the strained atmosphere but the encouragement of others who saw the potential of their research prevented escalation of the conflict. In January 1922, the team performed the first successful clinical trial, on 13-year-old Leonard Thompson, and it was soon followed by others. Although all the team members were listed as co-authors of their publications, Banting still felt overlooked, because Macleod took over the coordination of clinical trials and the acquisition of larger amounts of extract. Macleod's presentation at a meeting of the Association of American Physicians in Washington, D.C., on 3 May 1922 received a standing ovation, but Banting and Best refused to participate in protest. At that time, demonstrations of the method's efficiency drew huge public interest, because the effect on patients, especially children, who until then were bound to die, seemed almost miraculous. The pharmaceutical company Eli Lilly & Co.
Sources: en.wikipedia.org
Research in Italy suggests that healthy centenarians have high levels of both vitamin A and vitamin E and that this seems to be important in causing their extreme longevity. Other research contradicts this, however, and has found that this theory does not apply to centenarians from Sardinia, for whom other factors probably play a more important role. A preliminary study carried out in Poland showed that, in comparison with young healthy female adults, centenarians living in Upper Silesia had significantly higher red blood cell glutathione reductase and catalase activities, although serum levels of vitamin E were not significantly higher. Researchers in Denmark have also found that centenarians exhibit a high activity of glutathione reductase in red blood cells. In this study, the centenarians having the best cognitive and physical functional capacity tended to have the highest activity of this enzyme. Additional research shows that people whose parents became centenarians have a higher number of naïve B cells. It is known that the children of parents who have a long life are also more likely to reach older age, but it is not clear why, although inherited genes are believed to play an important role. A variation in the gene FOXO3A is known to have a positive effect on the life expectancy of humans, and is found much more often in people living to 100 and beyond – moreover, this appears to be true worldwide. Men and women who are 100 or older tend to have extroverted personalities, according to Thomas T.
== In plants == If calcium is deficient, pectin cannot be synthesized, and therefore the cell walls cannot be bonded and thus an impediment of the meristems. This will lead to necrosis of stem and root tips and leaf edges. For example, necrosis of tissue can occur in Arabidopsis thaliana due to plant pathogens. Cacti such as the Saguaro and Cardon in the Sonoran Desert experience necrotic patch formation regularly; a species of Dipterans called Drosophila mettleri has developed a P450 detoxification system to enable it to use the exudates released in these patches to both nest and feed larvae.
They launched this new device in the UK in 2008 under their Gamucci brand and the design is now widely adopted by most "cigalike" brands. Other users tinkered with various parts to produce more satisfactory homemade devices, and the hobby of "modding" was born. The first mod to replace the e-cigarette's case to accommodate a longer-lasting battery, dubbed the "screwdriver", was developed by Ted and Matt Rogers in 2008. This device generated a lot of interest, as it let the user to vape for hours at one time. Other enthusiasts built their own mods to improve functionality or aesthetics. When pictures of mods appeared at online vaping forums many people wanted them, so some mod makers produced more for sale. These mods led to demand for customizable e-cigarettes, prompting manufacturers to produce devices with interchangeable components that could be selected by the user. In 2009, Joyetech developed the eGo series which offered the power of the screwdriver model and a user-activated switch to a wide market. The clearomizer was invented in 2009. Originating from the cartomizer design, it contained the wicking material, an e-liquid chamber, and an atomizer coil within a single clear component. The clearomizer allows the user to monitor the liquid level in the device. Soon after the clearomizer reached the market, replaceable atomizer coils and variable voltage batteries were introduced. Clearomizers and eGo batteries became the best-selling customizable e-cigarette components in early 2012.
=== Early years === Sidney Fox was the son of Jacob Fox, a wig-maker, and Louise Berman, a Ukrainian immigrant. Fox married Raia Joffe Fox and they had three sons: Lawrence, Ronald, and Thomas. All three of his sons became scientists. His family was Jewish. Fox obtained a Bachelor of Arts degree from University of California, Los Angeles in Chemistry. He went on to earn a Ph.D. from California Institute of Technology in 1940 and did his postdoctoral work at the Linus Pauling Laboratory where he grew close with Linus Pauling.
Sources: en.wikipedia.org
The neon tetra (Paracheirodon innesi) is a species of freshwater fish belonging to the family Acestrorhamphidae, the American characins, of the order Characiformes. The type species of its genus, it is native to blackwater and clearwater streams in the Amazon basin of South America. Its bright colouring makes the fish visible to conspecifics in the dark blackwater streams, and is also the main reason for its popularity among freshwater fish hobbyists, with neon tetras being one of the most widely kept tropical fish in the world.
== Adult life == Elizabeth returned to school in 1923 and graduated from Barnard College in 1929. In 1930 she married William T. Gossett, a lawyer who later served as the president of the American Bar Association (1968-69) as well as vice president and general counsel of the Ford Motor Company. They lived in Bloomfield, Michigan, and had two daughters and a son. Elizabeth Gossett was active in civic affairs in the Detroit area. She was a member of the board of trustees of Barnard College, one of the founding trustees of Oakland University, Rochester, a member of the Detroit Urban League, as well as a volunteer at the Merrill-Palmer Institute and at Michigan State University. She was best known as the founder of the Supreme Court Historical Society in 1972 and served as its president until 1979. Gossett died of a heart attack on April 21, 1981, at the age of 73. By the time of her death, she had received approximately 42,000 insulin injections over 58 years. Although her name had been prominently mentioned in the newspaper coverage of insulin in 1922, she later hid her diabetes from her friends and associates. She destroyed most of the material that documented her treatments, and even removed references to diabetes in her father's papers.
The atomic radii of the alkali metals increase going down the group. Because of the shielding effect, when an atom has more than one electron shell, each electron feels electric repulsion from the other electrons as well as electric attraction from the nucleus. In the alkali metals, the outermost electron only feels a net charge of +1, as some of the nuclear charge (which is equal to the atomic number) is cancelled by the inner electrons; the number of inner electrons of an alkali metal is always one less than the nuclear charge. Therefore, the only factor which affects the atomic radius of the alkali metals is the number of electron shells. Since this number increases down the group, the atomic radius must also increase down the group. The ionic radii of the alkali metals are much smaller than their atomic radii. This is because the outermost electron of the alkali metals is in a different electron shell than the inner electrons, and thus when it is removed the resulting atom has one fewer electron shell and is smaller. Additionally, the effective nuclear charge has increased, and thus the electrons are attracted more strongly towards the nucleus and the ionic radius decreases.
=== Liver fibrosis === TGF-β1 has been implicated in the process of activating hepatic stellate cells (HSCs) with the magnitude of hepatic fibrosis being in proportion to increase in TGF-β levels. Studies have shown that ACTA2 is associated with TGF-β pathway that enhances contractile properties of HSCs leading to liver fibrosis.
=== United States === Radiology is a field in medicine that has expanded rapidly after 2000 due to advances in computer technology, which is closely linked to modern imaging techniques. Applying for residency positions in radiology has become highly competitive. Applicants are often near the top of their medical school classes, with high USMLE (board) examination scores. Diagnostic radiologists must complete prerequisite undergraduate education, four years of medical school to earn a medical degree (D.O. or M.D.), one year of internship, and four years of residency training. After residency, most radiologists pursue one or two years of additional specialty fellowship training. The American Board of Radiology (ABR) administers professional certification in Diagnostic Radiology, Radiation Oncology, and Medical Physics as well as subspecialty certification in neuroradiology, nuclear radiology, pediatric radiology, and vascular and interventional radiology. "Board Certification" in diagnostic radiology requires successful completion of two examinations. The Core Exam is given after 36 months of residency. Although previously taken in Chicago or Tucson, Arizona, beginning in February 2021, the computer test transitioned permanently to a remote format. It encompasses 18 categories. A passing score is 350 or above. A fail on one to five categories was previously a Conditioned exam; beginning in June 2021, the conditioned category will no longer exist, and the test will be graded as a whole. The Certification Exam can be taken 15 months after completion of the Radiology residency.
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.
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。