lyophilised powder raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
This page was last updated on 2025-11-08 and is reviewed periodically as new material appears.
Common degradation pathways include oxidation of the methionine side chain, hydrolysis of the peptide backbone, and aggregation under unfavourable pH or concentration. Stability studies typically monitor the main peak by chromatography and report total related substances as a percentage. Because no official monograph exists, acceptance criteria vary between laboratories, and reported purity values are not directly comparable across suppliers. Analysts therefore document the method, column, and detection wavelength alongside each result, and open questions remain about how much biological activity the oxidised forms retain.
Solid semax is typically supplied as a lyophilised powder that is hygroscopic and sensitive to moisture, light, and repeated temperature cycling. Long-term storage of the dry peptide is generally recommended at approximately -20 degrees Celsius, while shorter working periods may use refrigeration at 2 to 8 degrees Celsius. Vials should remain tightly closed and desiccated when brought to room temperature, because condensation can damage the material before it is weighed. Dividing a batch into aliquots is preferable to thawing one container repeatedly.
Development took place during the 1980s at institutes of the Russian Academy of Sciences, where peptide fragments of ACTH were screened for cognitive and neuroprotective effects. The compound received regulatory approval in Russia as a nasal preparation, marketed for conditions such as ischemic stroke, transient ischemic attacks, and optic nerve disorders. Registration in other countries has not followed. Most published clinical reports originate from a small number of Russian research groups, and independent replication outside that setting remains limited. The regulatory status therefore differs sharply between Russia and the rest of the world.
Laboratory work points toward modulation of neurotrophic signaling, particularly expression of brain-derived neurotrophic factor and nerve growth factor in hippocampal tissue. Studies also describe effects on monoamine turnover, inflammatory mediators, and oxidative markers. These observations come mainly from animal models and cultured cells, so the causal chain in humans is not firmly established. Whether the reported molecular changes translate into measurable clinical benefit is an open question. Reviews generally present the mechanism as plausible rather than demonstrated.
| Property | Value | Notes |
|---|---|---|
| Typical analytical method | Reversed-phase HPLC with UV detection | Separates target peptide from truncated and oxidised forms |
| Identity confirmation | LC-MS or ESI-MS | Compares observed and calculated molecular ion |
| Primary degradation route | Methionine oxidation | Forms the sulfoxide; monitored as an early-eluting peak |
| Short-term storage | 2 to 8 degrees Celsius | Applies to working vials and reconstituted portions |
| Common synonyms | ACTH(4–10) analogue, MEHFPGP | Descriptive names used in laboratory catalogues |
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。
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.
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.
=== United States === Since a 1972 law, government insurance (Medicare) covers the cost of dialysis and transplants for citizens of any age with end stage renal disease. By 2014, more than 460,000 Americans were undergoing treatment, the costs of which amount to six percent of the entire Medicare budget. Kidney disease is the ninth leading cause of death, and the U.S. has one of the highest mortality rates for dialysis care in the industrialized world. The rate of patients getting kidney transplants has been lower than expected. These outcomes have been blamed on a new for-profit dialysis industry responding to government payment policies. A 1999 study concluded that "patients treated in for-profit dialysis facilities have higher mortality rates and are less likely to be placed on the waiting list for a renal transplant than are patients who are treated in not-for-profit facilities", possibly because transplantation removes a constant stream of revenue from the facility. The insurance industry has complained about kickbacks and problematic relationships between charities and providers.
Taruc and others claimed that civilian guards and government officials were "sabotaging the peace process". On August 24, 1946, Feleo was stopped by a large band of "armed men in fatigue uniforms" in Gapan, Nueva Ecija. He had planned to present the peasant's concerns to the Secretary of the Interior Jose Zulueta, before he was taken and killed. Thousands of Huk veterans and PKM members were sure that Feleo was murdered by landlords, or possibly the Roxas administration itself. The incident led to Taruc joining the peasants and re-igniting the insurrection. The Roxas administration then outlawed the Hukbalahap on March 6, 1948. In 1949, Hukbalahap members ambushed and murdered Aurora Quezon, Chairman of the Philippine Red Cross and widow of the Philippines' second president, Manuel L. Quezon, as she was en route to her hometown for the dedication of the Quezon Memorial Hospital. Several others were also killed, including her eldest daughter and son-in-law. This attack brought worldwide condemnation of the Huks, who claimed that the attack was done by "renegade" members. The continuing condemnation and new post-war causes of the movement prompted the Huk leaders to adopt a new name, the "Hukbong Mapagpalaya ng Bayan" or the "People's Liberation Army" in 1950. Public sympathies for the movement had been waning due to their postwar attacks. The Huks confiscated funds and property to sustain their movement and relied on small village organizers for political and material support.
The situation with SECIS in eukarya and archaea is less clear as of 2006, as the SECIS element instead occurs in the untranslated regions of the mRNA. The eukaryote homolog of SelB (EEFSEC) instead has a C-terminal domain that binds to SECISBP2 (SBP2), which carries out the actual binding of SECIS RNA. Other SECIS RNA binding proteins also exist, notably including 60S ribosomal protein L30. The archaeal homolog of SelB does not seem to have any special extension, so how it interacts with the SECIS is even less clear. The final question is how the ribosome is able to know the UGA is supposed to be coding for Sec instead of the stop codon. This question is again relatively easy to answer in bacteria, but in eukarya and archaea it presumably has some dependency on the recognition of SECIS.
The US has used its dominant power to enforce the conventions in other countries, in ways that include making financial aid contingent on drug control efforts, and supplying economic and military support for drug intervention. The drug conventions do not explicitly prohibit, they establish control over a set of drugs. The personal use of illicit drugs is not outlawed, although possession is. Penalties are not specified, they are at the discretion of individual countries, and can range from mild to harsh. In practice, this flexibility has been used to create a prohibitionist, punitive war on drugs that is not explicitly required by the treaties. Negative effects of this hardline approach – increased violence and organized crime; human rights violations – have led to an increasing number of countries deviating from the regime. Deviation undermines the credibility of the drug conventions, which in turn, can weaken the entire system of UN international treaties.
Sources: en.wikipedia.org
UPS' global hub for air shipments is the Worldport, located at Louisville Muhammad Ali International Airport. The facility contributes to the airport's status of the third-busiest cargo airport in the United States and the fifth-busiest worldwide. The Worldport consists of:
The outer edge is then curled down and around about 140 degrees using rollers to create the end curl. The result is a steel tube with a flanged edge, and a countersunk steel disc with a curled edge. A rubber compound is put inside the curl.
== Isosceles triangle == If the two equal sides of an isosceles triangle have length a and the other side has length c, then the internal angle bisector t from one of the two equal-angled vertices satisfies
Sources: en.wikipedia.org
Dry powder is usually kept at about -20 degrees Celsius for long-term storage and at 2 to 8 degrees Celsius for short working periods. Containers should stay sealed and protected from light and moisture to limit degradation.
Oxidation of the methionine residue to the sulfoxide is a frequently reported change, and it usually appears as an earlier-eluting peak in reversed-phase chromatography. Backbone hydrolysis products can also accumulate in aqueous solution.
Liquid chromatography coupled with mass spectrometry is the usual approach, because the observed molecular ion can be compared with a calculated mass of about 813.9 Da. Retention time alone does not establish identity.
Semax is a synthetic seven-amino-acid peptide derived from a fragment of corticotropin. It is used in Russia as a nasal preparation, while elsewhere it is studied as a research compound. It is not approved as a medicine in most countries.