melanocortin signalling 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.
Updated 2025-08-29. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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。
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。
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C37H51N9O10S | Free acid form of the heptapeptide; depends on terminal groups |
| Molecular mass | About 813.9 g/mol | Average mass used for mass spectrometry confirmation |
| Appearance | White to off-white solid | Supplied as a lyophilised powder; hygroscopic |
| Solubility class | Freely soluble in aqueous media | Water, saline, and phosphate buffers; limited organic solubility |
| Typical storage temperature | -20 degrees Celsius | Long term and dry; short working periods may use 2 to 8 degrees Celsius |
Although historically stepfamilies are built through the institution of marriage and are legally recognized, it is currently unclear if a stepfamily can be both established and recognized by less-formal arrangements, such as when a man or woman with children cohabits with another man or woman outside of marriage. This relationship is becoming more common in all Western countries. There appear to be many cultures in which these families are recognized socially as de facto families. However, in modern Western culture it is often unclear as to what, if any, social status and protection they enjoy in law. The stepparent is a "legal stranger" in most of the U.S. and has no legal right to the minor child no matter how involved in the child's life they are. The biological parents (and, where applicable, adoptive parents) hold that privilege and responsibility. If the biological parent does not give up their parental rights and custody of the child, the other parent's subsequent marriage cannot create a parental relationship without the biological parent's written consent before a "child" reaches adulthood. In most cases, the stepparent can not be ordered to pay child support. Stepparents generally do not have the authority to give legal consent to medical treatment for a stepchild, unless the stepparent has legally adopted the child or been designated a legal guardian. A child's parents or legal guardians may sign a statement authorizing a third party to consent to medical care.
The presence of gastrin stimulates parietal cells of the stomach to secrete hydrochloric acid (HCl)/gastric acid. This is done both directly on the parietal cell and indirectly via binding onto CCK2/gastrin receptors on ECL cells in the stomach, which respond by releasing histamine, which in turn acts in a paracrine manner on parietal cells stimulating them to secrete H+ ions. This is the major stimulus for acid secretion by parietal cells. Along with the above-mentioned function, gastrin has been shown to have additional functions as well:
Exactly how LSD produces its effects is unknown, but it is thought that it may work in part by increasing glutamate release in the cerebral cortex and therefore excitation in this area, specifically in layer V. LSD, like many other drugs of recreational use, has been shown to activate DARPP-32-related pathways. The drug enhances dopamine D2 receptor protomer recognition and signaling of D2–5-HT2A heteromeric receptor complexes, which may contribute to its psychotropic effects. LSD has been shown to have low affinity for histamine H1 receptors, displaying antihistamine effects, although the significance of this at doses used in humans is unknown. David E. Nichols has suggested that there may be a pharmacological basis for some bad trips with LSD, with this thought to be related to LSD's metabolite 13-hydroxy-LSD, a highly potent dopamine D4 receptor agonist. LSD is a biased agonist that induces a conformation in serotonin 5-HT2 receptors that preferentially recruits β-arrestin over activating G proteins. It also has an exceptionally long residence time when bound to serotonin receptors lasting hours, consistent with the long-lasting effects of LSD despite its relatively rapid clearance. In rodents, LSD levels are undetectable by 8 hours post-dosing, yet LSD continues to produce partial interoceptive effects (54% responding) at this time point.
Sources: en.wikipedia.org
Military rations, operational rations, or military provisions are goods issued to sustain the needs of military personnel. As their name suggests, military rations have historically been, and often still are, subject to rationing, with each individual receiving specific amounts from available supplies. Military-issued goods and the rationing of such goods have existed since the beginnings of organized warfare. Though commonly referring to food and drink rations, "military ration" may also refer to other types of items that are rationed for military personnel, such as fuel, alcohol, expensive items, or consumer goods. Ration acquisition may be managed using allowances or a ration card, or they may be issued without charge. Military rations are a key component of military nutrition, the field and study of nutrition in the military. Significant research goes into creating military rations, including the nutrition and energy of rations, food spoilage prevention, what meals should be offered, the amount of food each ration should contain, and the exact specifications of each meal and ingredient.
=== Antimicrobial properties === CO2 at high pressures has antimicrobial properties. While its effectiveness has been shown for various applications, the mechanisms of inactivation have not been fully understood although they have been investigated for more than 60 years.
In 1913, Leonard Rowntree and John Jacob Abel of Johns Hopkins Hospital developed the first dialysis system which they successfully tested in animals. A Dutch doctor, Willem Johan Kolff, constructed the first working dialyzer in 1943 during the Nazi occupation of the Netherlands. Due to the scarcity of available resources, Kolff had to improvise and build the initial machine using sausage casings, beverage cans, a washing machine and various other items that were available at the time. Over the following two years (1944–1945), Kolff used his machine to treat 16 patients with acute kidney failure, but the results were unsuccessful. Then, in 1945, a 67-year-old comatose woman regained consciousness following 11 hours of hemodialysis with the dialyzer and lived for another seven years before dying from an unrelated condition. She was the first-ever patient successfully treated with dialysis. Gordon Murray of the University of Toronto independently developed a dialysis machine in 1945. Unlike Kolff's rotating drum, Murray's machine used fixed flat plates, more like modern designs. Like Kolff, Murray's initial success was in patients with acute renal failure. Nils Alwall of Lund University in Sweden modified a similar construction to the Kolff dialysis machine by enclosing it inside a stainless steel canister. This allowed the removal of fluids, by applying a negative pressure to the outside canister, thus making it the first truly practical device for hemodialysis. Alwall treated his first patient in acute kidney failure on 3 September 1946.
Sources: en.wikipedia.org
On 11 February, he said that the US was not buying anything and would just "have" and "keep" Gaza. UN officials said that Trump's plan would essentially involve the ethnic cleansing of Gaza. The Hill reported that Trump was sending "mixed messages" about the fate of the Gazans and that he was not being clear about the long-term plan of displacement. Mike Waltz, national security adviser to Trump, suggested that Trump's proposal was an initial invitation to other regional players to bring solutions to the table. Marco Rubio similarly said that it was time for other regional powers to "step forward" and that "If the Arab countries have a better plan, then that’s great." Trump has requested that Arab governments like Egypt and Jordan take in the displaced Palestinian populations. Abdullah II of Jordan, meeting with Mahmoud Abbas prior, entered into talks with Trump about the plan but did not directly agree with or contradict the president, suggesting instead that Egypt would propose an alternative plan. It is reported that Trump's plan is based on a paper drawn up by economics professor Joseph Pelzman. On 21 February 2025, after opposition from Arab states, Trump said he would "recommend" but not enforce his plan for the US takeover of Gaza and the resettlement of the Palestinian population. On 12 March 2025, Trump said that "nobody is expelling any Palestinians" from Gaza, which signaled a change from his previous stance.
Scientist Steven Salzberg identifies acupuncture and Chinese medicine generally as a focus for "fake medical journals" such as the Journal of Acupuncture and Meridian Studies and Acupuncture in Medicine. As Singh and Ernst pointed out, Chinese publication bias for acupuncture is real, without being fraud.
=== Molecular dynamics (MD)-based methods === Molecular dynamics methods of calculating pKa values make it possible to include full flexibility of the titrated molecule. Molecular dynamics based methods are typically much more computationally expensive, and not necessarily more accurate, ways to predict pKa values than approaches based on the Poisson–Boltzmann equation. Limited conformational flexibility can also be realized within a continuum electrostatics approach, e.g., for considering multiple amino acid sidechain rotamers. In addition, current commonly used molecular force fields do not take electronic polarizability into account, which could be an important property in determining protonation energies.
Sources: en.wikipedia.org
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.
It appears in Russian pharmaceutical listings as a nasal formulation, but it is not an authorised medicine in the United States or the European Union. Outside those markets it is normally encountered as a research chemical rather than a prescription product.
Laboratory and animal work points to melanocortin signalling and changes in neurotrophic factor levels, especially brain-derived neurotrophic factor. The exact receptor targets and the degree to which these findings transfer to humans are still unresolved.
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。