If you have been reading about intranasal delivery and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Last reviewed on 2025-12-01. Where a claim depends on a specific study, the study is described rather than over-claimed.
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。
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。
Routine characterization relies on reversed-phase high-performance liquid chromatography to establish purity and on mass spectrometry to confirm molecular identity. Electrospray ionization and matrix-assisted laser desorption ionization are both used for mass verification. Amino acid analysis and peptide mapping can detect sequence errors. Common impurities include truncated sequences, methionine sulfoxide formed by oxidation, and deamidated products. Chromatograms are usually recorded near 214 nm, where the peptide backbone absorbs, and purity is reported as the percentage area of the principal peak.
Verification of a supplied batch generally combines a certificate of analysis with independent testing, because certificates are self-reported documents. A typical package includes a chromatographic trace, a mass spectrum, and a stated water or counter-ion content. Batch-to-batch consistency matters more than a single purity figure when results are compared across experiments. No single mandatory standard governs research-grade peptide release, so laboratories are expected to define their own acceptance criteria. Residual trifluoroacetate from purification is a frequently overlooked counter-ion.
Lyophilized material is chemically stable for extended periods when kept dry, cold, and protected from light. The powder is hygroscopic, so vials should be warmed to room temperature before opening to reduce condensation on the contents. Once dissolved, the peptide is far less stable because peptide bonds are susceptible to hydrolysis and the methionine residue can oxidize. Solutions are typically aliquoted and held at 2-8 °C for short intervals or frozen for longer ones, and repeated freeze-thaw cycles should be avoided.
| 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 |
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.
Circulation time for the peptide is short because peptidases cleave it readily. The Pro-Gly-Pro tail is thought to slow breakdown compared with the bare ACTH fragment, but the gain appears modest. Absorption after intranasal dosing is limited, and only a fraction of a dose is expected to reach the central nervous system. Laboratory concentrations therefore sit well above levels achieved systemically, a gap that complicates translation from bench findings to clinical claims.
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。
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。
Save for a brief mention in the Barrie Examiner, it was the first time Carrey received significant mainstream corporate media coverage and the glowing praise in one of Canada's highest-circulation dailies created demand for his impressionist stand-up act throughout the country. In April 1981, Carrey appeared in an episode of the televised stand-up show An Evening at the Improv. That summer, he landed one of the main roles in Introducing... Janet, a made-for-TV movie that premiered in September 1981 on the CBC drawing more than a million viewers for its first airing in Canada. Playing a struggling impressionist comic Tony Moroni, it was Carrey's first acting role. The CBC promotion the movie had received as well its subsequent high nationwide viewership further solidified the youngster's comedic status in the country; by the time the movie finished its CBC run of repeats several years later, its title for the home video release on VHS was changed to Rubberface in order to take advantage of the comic's by then established prominence for doing elaborate contortionist impressions. Making more comedy club appearances in the United States, Carrey was noticed by comedian Rodney Dangerfield who signed Carrey to open his tour performances. By December 1981, a well-known comic in Canada, Toronto Star reported about Carrey waiting for a United States work permit having received interest from Johnny Carson's Tonight Show, largely off his reputation from Canada.
Windtree Therapeutics, Inc. (formerly Discovery Laboratories) is an American company which was set up in 1992 and now is based in Warrington, Pennsylvania, developing drug products (pulmonary medicine) for patients with respiratory disease. The company joined an alliance with Laboratorios del Dr. Esteve, S.A. In 2016, Discovery Laboratories changed name to Windtree Therapeutics, Inc.
integron A mobile genetic element consisting of a gene cassette containing the gene for a site-specific recombinase, integrase-specific recognition sites, and a promoter that governs the expression of one or more genes conferring adaptive traits on the host cell. Integrons usually exist in the form of circular episomal DNA fragments, through which they facilitate the rapid adaptation of bacteria by enabling horizontal gene transfer of antibiotic resistance genes between different bacterial species.
After the resignations of Kissinger's aides, Nixon took away the authority to tap phones, which he had given Kissinger in May 1969, and gave it to the attorney general, John Mitchell. Unknown to Kissinger, Mitchell had been illegally tapping his phone since the fall of 1969. Adding to the tension, on 2 May 1970, U.S. aircraft bombed North Vietnam for the first time since 1968, causing Senator Fulbright to say, "Good God", when he heard the news. Senate Majority Leader Mike Mansfield said he had trouble believing that Nixon and Kissinger were so reckless. To Nixon, Kissinger accused Laird and/or Rogers of leaking the news of the bombing raid on North Vietnam and asked for the FBI to tap their phones. Without informing Nixon, on 4 May 1970, Laird announced the end of the bombing raids on North Vietnam. On the night of 8 May 1970, Nixon, who had been rattled by the protests, stayed up all night, drinking heavily and randomly phoning people he knew. Between 11:00 pm–2:00 am, Nixon made forty calls, with Kissinger receiving eight of the calls. The Cambodian "incursion" saw American and South Vietnamese troops take the areas of eastern Cambodia that American commanders called the Fish Hook and Parrot's Beak and capture an impressive haul of arms originating from China and the Soviet Union. However, the majority of Vietnamese Communist forces had withdrawn deeper into Cambodia before the invasion, with only a small number left behind to wage a fighting retreat to avoid charges of cowardice.
Sources: en.wikipedia.org
== Joining chain == Chains are usually bought ready-joined to length, to suit a particular bar. All chainsaws have adjustable bar mounts to allow their chain tightness to be adjusted, allowing for any wear in the chain linkages. There is no requirement to remove links to shorten worn chains, chains will wear out on their cutting teeth before wear in their pivots becomes a problem. The adjustment also permits enough slack to allow a chain to be installed, so there is no need for a "split link" when fitting, as for bicycles. Large scale operators and retail shops may buy bulk chain on reels. This must then be cut and joined to length which is done by inserting rivet pins. These non-reusable pins are usually supplied already installed into a half-link and must be peened over against a half-link on the other side. As this peening is done with a bench-mounted rotary tool, rather than hammering, it is referred to as "rivet spinning". The tool is usually hand-cranked, or may be electrically powered for mass production.
== People == Vesta Stoudt (1891–1966), factory worker during Second World War known for her letter to President Franklin D. Roosevelt suggesting the use of adhesive tape to improve ammunition boxes, leading to duct tape Vesta (1957–2011), stage name of American recording artist Vesta Williams
The affinity, given as the dissociation constant (Kd), between a TCR and a pMHC was determined by surface plasmon resonance (SPR) to be in the range of 1–100 μM, with an association rate (kon) of 1000 -10000 M−1 s−1 and a dissociation rate (koff) of 0.01 -0.1 s−1. In comparison, cytokines have an affinity of KD = 10–600 pM to their receptor. It has been shown that even a single amino acid change in the presented peptide that affects the affinity of the pMHC to the TCR reduces the T-cell response and cannot be compensated by a higher pMHC concentration. A negative correlation between the dissociation rate of the pMHC-TCR complex and the strength of the T-cell response has been observed. That means, pMHC that bind the TCR for a longer time initiate a stronger activation of the T cell. Furthermore, T cells are highly sensitive; interaction with a single pMHC is enough to trigger activation. T cells move on quickly from antigens that do not trigger responses, rapidly scanning pMHC on an antigen-presenting cell (APC) to increase the chance of finding a specific pMHC. On average, a T cell encounters 20 APCs per hour. Different models for the molecular mechanisms that underlie this highly specific and highly sensitive process of antigen discrimination have been proposed. The occupational model simply suggests that the TCR response is proportional to the number of pMHC bound to the receptor. Given this model, a shorter lifetime of a peptide can be compensated by higher concentration such that the maximum response of the T cell stays the same.
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。
Dry powder is normally held at -20 °C or lower, away from light and moisture. Sealed vials can also be kept at 2-8 °C for shorter intervals. Warming to room temperature before opening prevents condensation.