This is a working overview of Electrospray ionization, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-01-24. Anything still debated is marked as such rather than presented as settled.
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。
Development is attributed to researchers at the Institute of Molecular Genetics in Moscow during the early 1980s, building on earlier Soviet work with ACTH fragments. Russian regulatory approval followed for intranasal use, and the compound has remained commercially available there for decades. Most published human data originate from Russian and, later, some Eastern European clinical reports, which are not always accessible in English translation. Outside that region the material is generally handled as a research chemical rather than a licensed medicine.
Regulatory status differs sharply between jurisdictions. In Russia the peptide is registered as a prescription nasal preparation, while agencies such as the United States Food and Drug Administration have not approved it for any indication. Products sold elsewhere are typically labeled for laboratory research only, and such labels shift responsibility for safe handling to the purchaser. Because the same name covers pharmaceutical-grade nasal drops and bulk research powder, identity and purity documentation becomes the main practical concern when comparing sources.
Semax is a synthetic seven-amino-acid peptide whose sequence extends the ACTH(4-10) fragment with a C-terminal proline-glycine-proline tripeptide. The commonly cited sequence is Met-Glu-His-Phe-Pro-Gly-Pro, giving a molecular formula near C37H51N9O10S and a molecular weight close to 813.9 g/mol. It belongs to the broader class of synthetic ACTH fragments studied for central nervous system effects rather than for adrenal steroid stimulation. In practice the material appears as a lyophilized white powder for laboratory work or as a dilute saline solution in clinical settings.
| Property | Value | Notes |
|---|---|---|
| 分子式 | C37H51N9O10S | 游离碱形式 |
| 等电点 | 约 6.5 | 估算值，随缓冲体系变化 |
| 主要降解途径 | 水解与氧化 | 侧链氧化最为常见 |
| 溶液储存 | 2 至 8 摄氏度避光 | 避免反复冻融 |
| 常规分析手段 | 反相色谱与质谱联用 | 氨基酸分析辅助核对 |
Identity and purity of Semax are established mainly by reversed-phase high-performance liquid chromatography coupled with mass spectrometry. The chromatographic trace gives a purity estimate as a percentage of total peak area, while electrospray or matrix-assisted laser desorption ionization confirms the molecular mass against the calculated value. Amino acid analysis and sequence-specific fragmentation provide further confirmation when a supplier's chain of custody is unclear. Vendors frequently quote a purity figure without stating the detection wavelength or the integration method, which limits how far one number can be compared with another.
Stability depends heavily on physical state. Lyophilized powder held dry, cold and dark retains its content over long periods, whereas dissolved peptide begins to change within days at room temperature. The most cited degradation route is oxidation of the methionine residue, which converts the peptide to a sulfoxide form that elutes differently on chromatography. Hydrolysis of amide bonds and adsorption onto container walls contribute smaller losses. Buffers that exclude oxygen from the headspace slow the oxidation pathway, but no single condition prevents all change indefinitely.
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.
Published research on this peptide originates mainly from Russian laboratories, and the wider international literature is comparatively thin. Studies have used rodent models of stroke, hypoxia, and memory tasks, with a smaller number of human trials reported. Reported outcomes include changes in attention and memory measures, along with effects on neurotrophic factor expression in some experiments. Small sample sizes, inconsistent dosing protocols, and limited independent replication are widely noted limitations, so the strength of the clinical evidence remains an open question.
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.
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.
Selenium and zinc are commonly referred to as antioxidant minerals, but these chemical elements have no antioxidant action themselves, but rather are required for the activity of antioxidant enzymes, such as glutathione reductase and superoxide dismutase.
increase activity against the chosen target reduce activity against unrelated targets improve the druglikeness or ADME properties of the molecule. This process will require several iterative screening runs, during which, it is hoped, the properties of the new molecular entities will improve, and allow the favoured compounds to go forward to in vitro and in vivo testing for activity in the disease model of choice. Amongst the physicochemical properties associated with drug absorption include ionization (pKa), and solubility; permeability can be determined by PAMPA and Caco-2. PAMPA is attractive as an early screen due to the low consumption of drug and the low cost compared to tests such as Caco-2, gastrointestinal tract (GIT) and Blood–brain barrier (BBB) with which there is a high correlation. A range of parameters can be used to assess the quality of a compound, or a series of compounds, as proposed in the Lipinski's Rule of Five. Such parameters include calculated properties such as cLogP to estimate lipophilicity, molecular weight, polar surface area and measured properties, such as potency, in-vitro measurement of enzymatic clearance etc. Some descriptors such as ligand efficiency (LE) and lipophilic efficiency (LiPE) combine such parameters to assess druglikeness. While HTS is a commonly used method for novel drug discovery, it is not the only method. It is often possible to start from a molecule which already has some of the desired properties.
Parkinson's disease is associated with aggregation of α-synuclein. As O-GlcNAc modification of α-synuclein has been found to inhibit its aggregation, elevating α-synuclein O-GlcNAc is being explored as a therapeutic strategy to treat Parkinson's disease.
== Medications == As of 2015, there were eight FDA-approved SNRIs in the United States, with venlafaxine being the first drug to be developed in 1993 and levomilnacipran being the latest drug to be developed in 2013. The drugs vary by their other medical uses, chemical structure, adverse effects, and efficacy.
Sources: en.wikipedia.org
== Conservation == Isinglass is also used as an adhesive to repair parchment, stucco, and damage to paintings on canvas. Pieces of the best Russian isinglass are soaked overnight to soften and swell the dried material. Next, it is cooked slowly in a double boiler at 45 °C (113F) while being stirred. A small amount of gum tragacanth dissolved in water is added to the strained isinglass solution to act as an emulsifier. When repairing paint that is flaking from parchment, isinglass can be applied directly to an area which has been soaked with a small amount of ethanol. It is typically applied as a very tiny drop that is then guided, with the help of a binocular microscope, under the edges of flaking paint. It can also be used to coat tissue or goldbeater's skin. On paintings, this can be used as a temporary backing to either canvas patches or filler until dried. Here, isinglass is similar to parchment size and other forms of gelatin, but it is unique in that as a dried film the adhesive can be reactivated with moisture. For this use, the isinglass is cooked with a few drops of glycerin or honey. This adhesive is advantageous in situations where minimal use of water is desired for the parchment as the isinglass can be reactivated with an ethanol-water mixture. It also has a greater adhesive strength than many other adhesives used for parchment repair.
Pratītya: "having depended". The term appears in the Vedas and Upanishads in the sense of "confirmation, dependence, acknowledge origin". The Sanskrit root of the word is prati* whose forms appear more extensively in the Vedic literature, and it means "to go towards, go back, come back, to approach" with the connotation of "observe, learn, convince oneself of the truth of anything, be certain of, believe, give credence, recognize". In other contexts, a related term pratiti* means "going towards, approaching, insight into anything". Samutpāda: "arising", "rise, production, origin" In Vedic literature, it means "spring up together, arise, come to pass, occur, effect, form, produce, originate". Pratītyasamutpāda has been translated into English as dependent origination, dependent arising, interdependent co-arising, conditioned arising, and conditioned genesis. Jeffrey Hopkins notes that terms synonymous to pratītyasamutpāda are apekṣasamutpāda and prāpyasamutpāda. The term may also refer to the twelve nidānas, Pali: dvādasanidānāni, Sanskrit: dvādaśanidānāni, from dvādaśa ("twelve") + nidānāni (plural of "nidāna", "cause, motivation, link"). Generally speaking, in the Mahayana tradition, pratityasamutpada (Sanskrit) is used to refer to the general principle of interdependent causation, whereas in the Theravada tradition, paticcasamuppāda (Pali) is used to refer to the twelve nidānas.
== Description == The fruiting body is varying in size, and can be 5–30 centimetres (2–12 in) tall and 4–20 cm (1+1⁄2–8 in). Immatures have been described to be oblong, somewhat resembling the shape of a rugby ball. There is some variation in coloration, and mature Pisolithus Arhizus feature a shiny gray/brown shell with darker and lighter/whitish/yellowish patches depending on the specimen. As it ages, the fungus can develop a rudimentary stipe or stem, although not all will do this. It also tends to open up, exposing "cracks and fissures, and eventually breaking up to expose the interior." This outer peridium is roughly 1mm thick and within it can be found a mass of pea-sized "pseudoperidioles" which are structures that contain and produce spores, and are fixed in a dark gel. As a reproductive strategy, P.arhizus will release spores to the wind as the peridium turns dry and crumbly/powdery with time. The fungus has non-ornamental spores that are described as "khaki" or "cinnamon" brown, and measure roughly 5-8µm in size.
Sources: en.wikipedia.org
Clinical data management Clinical Quality Management System Clinical trial management system Clinical trial Electronic data capture Electronic Common Technical Document (eCTD) Drug development Stuart Summerhayes, CDM Regulations Procedures Manual, Blackwell Publishing, ISBN 1-4051-0740-5 Tai BC, Seldrup J., A review of software for data management, design and analysis of clinical trials, Ann Acad Med Singap. 2000 Sep;29(5):576-81. Greenes RA, Pappalardo AN, Marble CW, Barnett GO., Design and implementation of a clinical data management system, Comput Biomed Res. 1969 Oct;2(5):469-85. CDMS at Mayo Clinic Association for Clinical Data Management Society for Clinical Data Management French network of Data Managers in Academic biomedical research Data Quality Research Institute Data Security Software for Clinics
24496Cm + 126C → 256102No* → 252102No + 4 10n Meanwhile, in Dubna, experiments were carried out in 1958 and 1960 aiming to synthesize element 102 as well. The first 1958 experiment bombarded 239Pu and 241Pu with 16O ions. Some alpha decays with energies just over 8.5 MeV were observed, and they were assigned to 251,252,253No, although the team wrote that formation of isotopes from lead or bismuth impurities (which would not produce nobelium) could not be ruled out. While later 1958 experiments noted that new isotopes could be produced from mercury, thallium, lead, or bismuth impurities, the scientists still stood by their conclusion that element 102 could be produced from this reaction, mentioning a half-life of under 30 seconds and a decay energy of (8.8 ± 0.5) MeV. Later 1960 experiments proved that these were background effects. 1967 experiments also lowered the decay energy to (8.6 ± 0.4) MeV, but both values are too high to possibly match those of 253No or 254No. The Dubna team later stated in 1970 and again in 1987 that these results were not conclusive. In 1961, Berkeley scientists claimed the discovery of lawrencium in the reaction of californium with boron and carbon ions. They claimed the production of the isotope 257Lr, and also claimed to have synthesized an alpha-decaying isotope of element 102 that had a half-life of 15 s and alpha decay energy 8.2 MeV. They assigned this to 255No without giving a reason for the assignment.
Extended insulin zinc insulin (Ultralente) Insulin glargine (Lantus) Insulin detemir (Levemir) Insulin degludec (Tresiba) Insulin degludec is sometimes classed separately as an "ultra-long" acting insulin due to its duration of action of about 42 hours, compared with 24 hours for most other long-acting insulin preparations. As a systematic review of studies comparing insulin detemir, insulin glargine, insulin degludec and NPH insulin did not show any clear benefits or serious adverse effects for any particular form of insulin for nocturnal hypoglycemia, severe hypoglycemia, glycated hemoglobin A1c, non-fatal myocardial infarction/stroke, health-related quality of life or all-cause mortality. The same review did not find any differences in effects of using these insulin analogues between adults and children. Most oral anti-diabetic agents are contraindicated in pregnancy, in which case insulin is preferred. Insulin is not administered by other routes, although this has been studied. An inhaled form was briefly licensed but was subsequently withdrawn.
Sources: en.wikipedia.org
电喷雾或基质辅助激光解吸电离质谱是常用手段，测得的质子化离子质荷比可换算为分子量。结果与理论值落在合理误差内，才支持结构一致的判断。
甲硫氨酸侧链含硫醚，在氧气、光照或金属离子存在时容易被氧化。氧化产物极性略增，常在色谱图上表现为主峰之前的肩峰或前伸峰。
通常建议冷藏避光，并在较短时间内使用。不存在适用于所有配方的统一期限，具体取决于浓度、缓冲体系与容器材质。
It is a short synthetic peptide built from seven amino acids: methionine, glutamic acid, histidine, phenylalanine and three prolines. The sequence derives from the 4-10 fragment of adrenocorticotropic hormone with an added proline-glycine-proline tail. No plant or animal extract is involved; the material is produced by solid-phase peptide synthesis.