mass spectrometry 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 2025-09-26. Numbers and descriptions here follow the published literature rather than marketing material.
当时的短肽研究普遍关注能否穿越血脑屏障、在低剂量下产生中枢效应，Semax 属于这一路线。鼻内给药是其主要使用方式，俄语文献报道的适应症涵盖缺血性卒中、短暂性脑缺血发作、认知功能减退以及视神经病变。这些研究大多发表在当地期刊上，样本规模与终点设置同西方试验惯例存在差异，国际同行对其临床证据的强度看法不一。
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。
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 |
|---|---|---|
| 结构类别 | 线性合成七肽 | 无环化结构，不含二硫键 |
| 氨基酸序列 | Met-Glu-His-Phe-Pro-Gly-Pro | N 端为甲硫氨酸 |
| 分子量 | 约 814 Da | 游离碱形式的计算值 |
| 外观 | 白色至类白色粉末 | 具吸湿性 |
| 溶解性 | 易溶于水 | 亦可溶于甲醇等极性溶剂 |
Semax is a synthetic peptide created in the Soviet Union during the early 1980s by researchers working in Moscow. It was built from the short adrenocorticotropic hormone fragment known as ACTH(4-10), and the chain was then extended with three additional amino acids. The resulting molecule was named semax and entered clinical use in Russia in 1994. It is generally described as a nootropic and neuroprotective agent rather than as a hormone analogue.
The parent fragment ACTH(4-10) carries the sequence Met-Glu-His-Phe-Arg-Trp-Gly. Semax replaces the arginine and tryptophan positions with a proline-glycine-proline tail, giving Met-Glu-His-Phe-Pro-Gly-Pro. That change removes residues associated with adrenal stimulation, so the peptide does not drive cortisol release the way full ACTH does. This distinction shapes how the compound is grouped in the literature, where it sits with neuropeptides and peptide neuromodulators rather than with corticosteroids.
Regulatory status varies sharply by country. Semax is registered for medical use in Russia, where it appears in formularies as a nasal solution, and it also holds registration in a small number of neighbouring states. It has no approval from the United States Food and Drug Administration or the European Medicines Agency, and it is not a scheduled controlled substance in most jurisdictions. Elsewhere it circulates mainly as laboratory material, so purity documentation comes from suppliers rather than from a national pharmacopoeia.
Semax is normally supplied as a lyophilized powder, and that form is the most stable. Suppliers commonly recommend storage at -20 °C in a desiccated container protected from light, with short-term handling at room temperature limited to weighing and transfer. Powder that has absorbed moisture degrades faster, so vials should be warmed to ambient temperature before opening to prevent condensation on the contents. Hygroscopic behavior is typical of short hydrophilic peptides, and humidity control matters more than temperature alone for long-term retention.
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.
Semax is a synthetic heptapeptide whose sequence is Met-Glu-His-Phe-Pro-Gly-Pro. The first four residues correspond to the ACTH(4-10) fragment, while the terminal Pro-Gly-Pro extension was added to improve metabolic stability. Its molecular formula is C37H51N9O10S and its monoisotopic mass is approximately 813.9 Da. The compound is classified as a peptide research chemical and as a registered pharmaceutical product in Russia, but it does not hold marketing approval in the European Union or the United States. Naming conventions vary across supplier catalogs.
Development of the compound took place in the Soviet Union during the 1980s, largely through peptide research groups affiliated with the Shemyakin-Ovchinnikov Institute and Moscow State University. Investigators screened fragments of adrenocorticotropic hormone for activity on the central nervous system while attempting to separate cognitive effects from hormonal ones. The shortened sequence was selected because it retained behavioral activity in animal models without stimulating corticosteroid release. Early publications described the molecule as an ACTH(4-10) analog.
Proposed mechanisms center on neurotrophic signaling rather than on classical melanocortin receptor activation. Rodent experiments have reported shifts in the expression of brain-derived neurotrophic factor and nerve growth factor after administration, together with changes in the associated receptor systems. Several authors argue that the peptide acts largely through its degradation products and their interaction with peptidergic pathways, but this remains a hypothesis rather than a settled finding. No single molecular target has been identified in a way that the field broadly accepts.
Published research covers ischemic stroke, traumatic brain injury, cognitive impairment, optic nerve conditions and attention-related measures. Much of the human evidence comes from small trials conducted in one country, which limits how far the results generalize. Animal models supply the larger share of the data, and effects seen in rodents do not transfer automatically to people. Reviews have noted that methodological reporting is often incomplete, making it difficult to pool results or compare treatment schedules across studies.
=== Recombinant human CNTF (Axokine) === A recombinant version of human CNTF (rhCNTF), trade name Axokine, is a modified version with a 15 amino acid truncation of the C-terminus and two amino acid substitutions. It is three to five times more potent than CNTF in in vitro and in vivo assays and has improved stability properties. Like CNTF it is a neurotrophic factor, and may stimulate nerve cells to survive. It was tested in the 1990s as a treatment for amyotrophic lateral sclerosis. It did not improve muscle control as much as expected, but trial participants did report a loss of appetite. Phase III clinical trials for the drug against obesity were conducted in 2003 by Axokine's maker, Regeneron Pharmaceuticals, demonstrating a small positive effect in some patients, but the drug was not commercialized. A major problem with the treatment was that in nearly 70% of the subjects tested, antibodies against Axokine were produced after approximately three months of treatment. In the minority of subjects who did not develop the antibodies, weight loss averaged 12.5 pounds in one year, versus 4.5 pounds for placebo-treated subjects. In order to obtain this benefit, subjects needed to receive daily subcutaneous injections of one microgram Axokine per kilogram body weight. Xencor patent application raises the disturbing idea that subjects producing antibodies against CNTF analogues may eventually suffer severe adverse effects, as these antibodies could potentially interfere with the neuroprotective functions of endogenous CNTF.
Specialized laboratory techniques have also been developed to improve the utility of RNAi in mammalian systems by avoiding the direct introduction of siRNA, for example, by stable transfection with a plasmid encoding the appropriate sequence from which siRNAs can be transcribed, or by more elaborate lentiviral vector systems allowing the inducible activation or deactivation of transcription, known as conditional RNAi.
=== Parkinson's disease === α-Synuclein is a protein that is associated with Parkinson's disease. In humans, this protein is encoded by the SNCA gene. α-Synuclein is involved in recycling synaptic vesicles that carry neurotransmitters and naturally occurs in an unfolded form. Elevated levels of α-Synuclein are found in patients with Parkinson's disease. There is a correlation between the concentration of unphosphorylated α-Synuclein present in the patient and the severity of Parkinson's disease. Specifically, phosphorylation of Ser129 in α-Synuclein has an impact on severity. Healthy patients have higher levels of unphosphorylated α-Synuclein than patients with Parkinson's disease. The measurement of change in the ratio of concentrations of phosphorylated α-Synuclein to unphosphorylated α-Synuclein within a patient could be a marker of the disease progression. Antibodies that target α-Synuclein at phosphorylated Ser129 are used to study the molecular aspects of synucleinopathies. Phosphorylation of Ser129 is associated with the aggregation of the protein and further damage to the nervous system. The aggregation of phosphorylated α-Synuclein can be enhanced if a presynaptic scaffold protein, Sept4, is present in insufficient quantities. Direct interaction of α-Synuclein with Sept4 inhibits the phosphorylation of Ser129. However, phosphorylation of Ser129 can be observed without synuclein aggregation in conditions of overexpression.
Sources: en.wikipedia.org
=== Supply Chain Events Accreditation === Besides SCTECH, ISCEA has provided other Supply Chain Related Events with accreditation. Therefore, certified Supply Chain Professionals have been able to obtain PDUs for participating in those events and later applying for the Certificate of Participation.
==== Sesame tofu ==== The tofu known as goma-dōfu is made by grinding sesame into a smooth paste, combining it with liquid and kudzu starch, and heating it until curdling occurs. It is often served chilled as hiyayakko.
=== Natural production === Natural vanillin is extracted from the seed pods of Vanilla planifolia, a vining orchid native to Mexico, but now grown in tropical areas around the globe. Madagascar is presently the largest producer of natural vanillin.
Sources: en.wikipedia.org
== Relationship to similar concepts == Gene sharing is related to, but distinct from, several concepts in genetics, evolution, and molecular biology. Gene sharing entails multiple effects from the same gene, but unlike pleiotropy, it necessarily involves separate functions at the molecular level. A gene could exhibit pleiotropy when single enzyme function affects multiple phenotypic traits; mutations of a shared gene could potentially affect only a single trait. Gene duplication followed by differential mutation is another phenomenon thought to be a key element in the evolution of protein function, but in gene sharing, there is no divergence of gene sequence when proteins take on new functions; the single polypeptide takes on new roles while retaining old ones. Alternative splicing can result in the production of multiple polypeptides (with multiple functions) from a single gene, but by definition, gene sharing involves multiple functions of a single polypeptide.
Dorothy Hodgkin on Nobelprize.org including the Nobel Lecture, 11 December 1964 The X-ray Analysis of Complicated Molecules Portraits of Dorothy Hodgkin at the National Portrait Gallery, London Works by or about Dorothy Hodgkin at the Internet Archive Four interviews with Dorothy Crowfoot Hodgkin recorded between 1987 and 1989 in partnership with the Royal College of Physicians are held in the Medical Sciences Video Archive in the Special Collections at Oxford Brookes University: Professor Dorothy Crowfoot Hodgkin OM FRS in interview with Sir Gordon Wolstenholme: Interview 1 (1987). Professor Dorothy Crowfoot Hodgkin OM FRS in interview with Max Blythe: Interview 2 (1988). Professor Dorothy Crowfoot Hodgkin OM FRS in interview with Max Blythe: Interview 3 (1989). Professor Dorothy Crowfoot Hodgkin OM FRS at home talking with Max Blythe: Interview 4 (1989). Watch a lecture of Dorothy Crowfoot Hodgkin (1910–1994) at the 1988 Nobel Laureates Symposium at the annual meeting of the American Crystallographic Association, Philadelphia Dorothy Hodgkin featured on the BBC Radio 4 program In Our Time on 3 October 2019. "The exceptional life of Dorothy Crowfoot Hodgkin", BBC "Ideas" video, 27 September 2021
During this initial deployment, 36 soldiers from the division were killed and about 400 were wounded, out of about 12,000 deployed. On 21 July 2006, the 1st Battalion, 325th Infantry Regiment, along with a platoon from Battery A, 2nd Battalion, 319th Field Artillery Regiment and a troop from 1st Squadron, 73rd Cavalry Regiment deployed to Tikrit, Iraq, returning in December 2006.
Sources: en.wikipedia.org
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。
Semax 对应 ACTH 第 4 至第 10 位的片段，并在两端做了替换与延长，使其不再具备促肾上腺皮质激素的典型内分泌活性。这一改动同时改变了它在体内的稳定性与分布特征。
俄罗斯将其列为处方药物，需要医生开具处方。多数其他国家把它当作研究化合物，不能作为药品销售或宣称疗效。具体合法性取决于当地法规。
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。