counter-ion is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Last reviewed on 2026-02-25. Where a claim depends on a specific study, the study is described rather than over-claimed.
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。
Clinical reports describe use in ischaemic stroke, transient ischaemic attack, optic nerve conditions, and cognitive complaints, but most of these studies are small and were conducted in a single region. Systematic reviews have generally described the evidence base as limited in size and variable in methodological quality. Randomised controlled data suitable for international regulatory assessment are scarce. As a result, major treatment guidelines outside Russia do not include the peptide, and interest in it remains largely research-driven rather than routine clinical.
Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro. It is described in the literature as an analogue of the ACTH(4–10) fragment, a short N-terminal portion of adrenocorticotropic hormone that retains some neurotropic activity without the full hormonal effects of the parent peptide. The molecule carries a methionine residue at the N-terminus and two proline residues near the C-terminus, features that shape both its interactions with receptor systems and its chemical stability. The free peptide corresponds to the formula C37H51N9O10S and a molecular mass near 813.9 Da.
The compound was developed in the 1980s at the Institute of Molecular Genetics in Moscow, where it emerged from research on short ACTH fragments and their effects on the central nervous system. Russian pharmaceutical listings describe it as a nootropic and neuroprotective agent, most often formulated as nasal drops. It is not a marketed medicine in the United States or the European Union, and no pharmacopoeial monograph covers it. Consequently, most published clinical experience with the substance originates from a small number of research centres, mainly in Russia and neighbouring countries.
| 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 |
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.
Laboratory descriptions of the material are consistent across suppliers. It appears as a white to off-white lyophilized powder that dissolves readily in water and in polar organic solvents such as dimethyl sulfoxide. Aqueous solutions are clear and colorless at low concentrations. Because the peptide contains methionine, oxidation at the sulfur atom is a recognized degradation pathway, and handling notes usually call for protected, desiccated storage. Reported purity for research-grade lots is generally above 95 percent as measured by reversed-phase high-performance liquid chromatography.
The compound is registered in Russia as a pharmaceutical product, most commonly formulated as a nasal solution, and has been used in that setting since the 1990s. Outside that jurisdiction it is generally handled as a research chemical rather than an approved medicine. Regulatory status therefore differs sharply between countries, and material sold internationally may not correspond to the Russian pharmaceutical formulation. Documentation with commercial samples is typically limited to a certificate of analysis covering purity and identity, not clinical status or local legal classification.
Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro. It corresponds to the ACTH(4-7) fragment extended at the C-terminus by a Pro-Gly-Pro tripeptide, an addition intended to slow enzymatic breakdown. The molecular formula is C37H51N9O10S and the molecular mass is approximately 814 daltons. In the literature it is often described as an ACTH(4-10) analog, although that label reflects a naming convention as much as a precise structural relationship. The compound was developed in Russia and remains most closely associated with that research tradition.
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.
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.
28 February to 8 May The U.S. 101st Airborne Division and ARVN 1st Division launched Operation Massachusetts Striker to keep pressure on the PAVN in the southern A Shau Valley. The operation results in 223 PAVN killed and two captured while U.S. losses were 59 killed.
== Associated organizations == Clinical Chemistry and Laboratory Medicine is the official journal of the European Federation of Clinical Chemistry and Laboratory Medicine (EFLM). It is also the official journal of the Association of Clinical Biochemists in Ireland, the Belgian Society of Clinical Chemistry, the German United Society of Clinical Chemistry and Laboratory Medicine, the Greek Society of Clinical Chemistry-Clinical Biochemistry, the Italian Society of Clinical Biochemistry and Clinical Molecular Biology, the Slovenian Association for Clinical Chemistry, and the Spanish Society for Clinical Biochemistry and Molecular Pathology.
== Degradation == Once secreted, GLP-1 is extremely susceptible to the catalytic activity of the proteolytic enzyme dipeptidyl peptidase-4 (DPP-4). Specifically, DPP-4 cleaves the peptide bond between Ala8-Glu9 resulting in the abundant GLP-1 (9–36) amide constituting 60–80% of total GLP-1 in circulation. DPP-4 is widely expressed in multiple tissues and cell types and exists in both a membrane-anchored and soluble circulating form. Notably, DPP-4 is expressed on the surface of endothelial cells, including those located directly adjacent to GLP-1 secretion sites. Consequently, less than 25% of secreted GLP-1 is estimated to leave the gut intact. Additionally, presumably due to the high concentration of DPP-4 found on hepatocytes, 40–50% of the remaining active GLP-1 is degraded across the liver. Thus, due to the activity of DPP-4 only 10–15% of secreted GLP-1 reaches circulation intact. Neutral endopeptidase 24.11 (NEP 24.11) is a membrane-bound zinc metallopeptidase widely expressed in several tissues, but found in particularly high concentrations in the kidneys, which is also identified accountable for the rapid degradation of GLP-1. It primarily cleaves peptides at the N-terminal side of aromatic or hydrophobic amino acids and is estimated to contribute by up to 50% to GLP-1 degradation. However, the activity only becomes apparent once the degradation of DPP-4 has been prevented, as the majority of GLP-1 reaching the kidneys has already been processed by DPP-4. Similarly, renal clearance appears more significant for the elimination of already inactivated GLP-1.
Only a single Tyrannosaurus specimen has been conclusively shown to belong to a specific sex. Examination of B-rex demonstrated the preservation of soft tissue within several bones. Some of this tissue has been identified as a medullary tissue, a specialized tissue grown only in modern birds as a source of calcium for the production of eggshell during ovulation. As only female birds lay eggs, medullary tissue is only found naturally in females, although males are capable of producing it when injected with female reproductive hormones like estrogen. This strongly suggests that B-rex was female and that she died during ovulation. Recent research has shown that medullary tissue is never found in crocodilians, which are thought to be the closest living relatives of dinosaurs. The shared presence of medullary tissue in birds and other theropod dinosaurs is further evidence of the close evolutionary relationship between the two.
Sources: en.wikipedia.org
== Different types of Alpha Collagen == Collagen, type I, alpha 1 Collagen, type II, alpha 1 Collagen, type III, alpha 1 Collagen, type IV, alpha 1 Collagen, type V, alpha 1 Collagen, type VI, alpha 1 Collagen, type VII, alpha 1 Collagen, type VIII, alpha 1 Collagen, type IX, alpha 1 Collagen, type X, alpha 1 And many further types of alpha collagen are identified.
== Experimental chemistry == Flerovium's chemistry has been experimentally investigated, though studies so far are not conclusive. Flerovium's volatility has been measured through interactions with a gold surface, indicating that the volatility of flerovium was comparable to that of mercury and astatine. This volatile behavior was not expected for a usual group 14 metal. In experiments in 2012 at GSI, flerovium's chemistry was found to be more metallic than noble-gas-like. Jens Volker Kratz and Christoph Düllmann specifically named copernicium and flerovium as being in a new category of "volatile metals"; Kratz even speculated that they might be gases at standard temperature and pressure. These "volatile metals", as a category, were expected to fall between normal metals and noble gases in terms of adsorption properties. Interactions of flerovium and copernicium with gold were about the same. Further studies showed that flerovium was more reactive than copernicium, in contradiction to previous experiments and predictions.
== Deployment history == Georgia strongly supported the U.S.-led entrance of troops in Iraq for peacekeeping purposes and deployed troops to the country in August 2003. Georgia's military deployment was undertaken as part of broader efforts to bolster closer ties with the United States and NATO in the face of the continuing Russian threat. The United States provided military training programs—GTEP and GSSOP—for Georgian forces. There was no tangible domestic opposition to the Georgian involvement in Iraq. Georgia's initial deployment was a platoon of special forces and a medical team, a total of 70 personnel in 2003. The Georgian presence in Iraq increased to 300 personnel in 2004 and to 850 in 2005, and peaked at 2,300 soldiers in mid-2008. The largest contingents deployed were the 3rd Infantry Brigade (July 2007 – January 2008) and the 1st Infantry Brigade (January–August 2008). In addition to participation in Operation Iraqi Freedom, from 2005 to 2008 Georgia also contributed a battalion of approximately 550 troops to the United Nations Assistance Mission in Iraq, which was stationed in Baghdad within the "Green Zone". At first, the Georgian troops deployed for Operation Iraqi Freedom were stationed in Baghdad and provided general security measures. Beginning in 2007, the Georgians were deployed along the border with Iran, with their main base at Kut, and tasked to interdict smuggled weapons, goods, and drugs. The Georgian units worked primarily within the U.S. area of operations.
Sources: en.wikipedia.org
=== Cholesterol clearance === Synthetic platelets are being explored for their potential in cholesterol clearance by facilitating the targeted removal of cholesterol from the bloodstream, offering a novel approach to treating hypercholesterolemia and preventing cardiovascular diseases. Elevated low-density lipoprotein cholesterol (LDL-C) is a key contributor to coronary heart disease, largely regulated by the interaction between LDL receptors (LDLR) and Proprotein Convertase Subtilisin/Kexin Type 9 (PCSK9). Since PCSK9 reduces LDLR availability, inhibiting it can enhance LDL-C clearance. To explore this, researchers designed platelet-mimicking nanoparticles to deliver siRNA targeting Pcsk9. These nanoparticles effectively lowered Pcsk9 mRNA levels by 66% in cell studies and reduced plasma LDL-C by 28% in animal models, without significantly altering high-density lipoprotein cholesterol (HDL-C) or triglycerides (TGs). This strategy demonstrates the potential of biomimetic nanoparticles for RNA-based therapies aimed at treating high cholesterol.
Lurasidone [(3aR,4S,7R,7aS)-2-{(1R,2R)-2-[4-(1,2-benzisothiazol-3-yl) piperazin-1-ylmethyl]-cyclohexylmethyl}-hexahydro-4,7-methano-2Hisoindole-1,3-dione hydrochloride] ] is an azapirone derivative and acts as an antagonist of the dopamine D2 and D3 receptors, and the serotonin 5-HT2A and 5-HT7 receptors, and the α2C-adrenergic receptor, and as a partial agonist of the serotonin 5-HT1A receptor. It has moderate-affinity antagonism at α2C-adrenergic receptors; low to very low-affinity antagonism at α1A-adrenergic α2A-adrenergic receptors. It has only low and likely clinically unimportant affinity for the serotonin 5-HT2C receptor, which may underlie its low propensity for appetite stimulation and weight gain. The drug also has negligible affinity for the histamine H1 receptor and the muscarinic acetylcholine receptors, and hence has no antihistamine or anticholinergic effects. Drowsiness (somnolence) side effect is not explained by its antagonist activity to histamine. The relationship between dose and D2 receptor occupancy levels were 41–43% for 10 mg, 51–55% for 20 mg, 63–67% for 40 mg, 77–84% for 60 mg, and 73–79% for 80 mg.
=== Enols and enolates === The α-carbon is important for enol- and enolate-based carbonyl chemistry as well. Chemical transformations affected by the conversion to either an enolate or an enol, in general, lead to the α-carbon acting as a nucleophile, becoming, for example, alkylated in the presence of primary haloalkane. An exception is in reaction with silyl chlorides, bromides, and iodides, where the oxygen acts as the nucleophile to produce silyl enol ether.
=== Cape Colony === In parts of Cape Colony, particularly the Cape Midlands District where Boers formed a majority of the white inhabitants, the British had always feared a general uprising against them. In fact, no such uprising took place, even in the early days of the war when Boer armies had advanced across the Orange. The cautious conduct of some elderly Orange Free State generals had been one factor that discouraged the Cape Boers from siding with the Boer republics. Nevertheless, there was widespread pro-Boer sympathy. Some Cape Dutch volunteered to help the British, but a larger number volunteered to help the other side. Politics was more important than the military factor: the Cape Dutch, according to Milner 90 percent of whom favoured the rebels, controlled the provincial legislature, and its authorities forbade the British Army to burn farms or to force Boer civilians into concentration camps. The British had more limited options to suppress the insurgency in the Cape Colony as result. After he escaped across the Orange in March 1901, de Wet had left forces under Cape rebels Kritzinger and Gideon Scheepers to maintain a guerrilla campaign in the Cape Midlands. The campaign here was one of the least chivalrous of the war, with intimidation by both sides of each other's civilian sympathisers. In one of many skirmishes, Commandant Johannes Lötter's small commando was tracked down by a much-superior British column and wiped out at Groenkloof.
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。
It is described as a synthetic analogue of the ACTH(4–10) fragment, a short segment of adrenocorticotropic hormone. Its sequence differs from that fragment and includes two proline residues, which influence stability and behaviour in solution.