This is a working overview of heptapeptide, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2025-10-31. Anything still debated is marked as such rather than presented as settled.
The proposed mechanism centres on neurotrophic signalling rather than direct receptor activation. Semax is reported to increase expression of brain-derived neurotrophic factor and nerve growth factor in several brain regions, and to shift the balance between excitatory and inhibitory neurotransmitter systems. Interaction with melanocortin receptors has been suggested because of the parent ACTH fragment. Many of these findings come from rodent studies, and the extent to which they translate to human physiology remains an open question.
Scientific literature on semax is unevenly distributed. A substantial share of published work originates from a small number of laboratories in Russia, while independent replication elsewhere is limited. Human data consist mostly of small trials with short follow-up, and several reported outcomes rely on subjective rating scales. Questions about how much intact peptide reaches the central nervous system after nasal administration, and how long it persists there, are still unresolved. The compound is best described as an active research subject rather than a settled pharmacological agent.
Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro. It was derived from the ACTH(4-10) fragment, a short segment of adrenocorticotropic hormone that lacks the hormonal activity associated with the full-length peptide. Researchers at the Institute of Molecular Genetics in Moscow developed the compound during the 1980s. It has been registered as a pharmaceutical product in Russia and several neighbouring countries, where it is supplied as a nasal solution, and it is also sold internationally as a research chemical.
Claims about enhanced focus, memory, or mood in healthy people rest mostly on anecdotal reports and community discussion rather than on controlled data. It remains unclear whether any cognitive benefit observed in patients recovering from brain injury would extend to uninjured users. Dose-response relationships, long-term safety, and interactions with other drugs are not well characterized in the peer-reviewed literature. Questions about optimal route of administration and treatment duration likewise remain open.
Semax binds to melanocortin receptors and is thought to influence neuronal survival and plasticity rather than to act through the adrenal axis. Laboratory work has shown increased expression of brain-derived neurotrophic factor and nerve growth factor in treated tissue. Changes in c-Fos, a marker of neuronal activation, have also been reported. Because the peptide is rapidly degraded by peptidases, its effects are generally attributed to downstream signaling cascades rather than to sustained receptor occupancy.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C37H51N9O10S | Calculated for the free peptide |
| Molar mass | 813.9 g/mol | Anhydrous free base |
| Peptide class | Synthetic heptapeptide | ACTH(4-10) analogue |
| Parent fragment | ACTH(4-10) | Adrenocorticotropic hormone segment |
| Developmental origin | Institute of Molecular Genetics, Moscow | Work began in the 1980s |
该化合物于二十世纪八十年代在俄罗斯被开发，相关工作由俄罗斯科学院分子遗传学研究所的研究团队主导。开发目标并非复制 ACTH 的完整激素活性，而是寻找保留其神经作用方向、同时去除促肾上腺皮质激素释放效应的短肽片段。研究记录显示，这一方向促成了多个相关短肽的合成与筛选，而 Semax 是其中被研究最广泛的一个。当地文献常以 Семакс 这一名称指代它。
研究兴趣主要集中在神经营养因子相关的路径上，包括脑源性神经营养因子与神经生长因子的表达变化。部分实验报告称在特定条件下观察到这些因子的水平上升，但具体信号通路和剂量依赖关系仍未完全厘清。多数公开数据来自细胞模型和动物实验，人体对照研究数量有限。因此，该化合物的作用机制在文献中属于活跃讨论，而非已经确立的定论。
Verification of a supplied batch generally combines a certificate of analysis with independent testing, because certificates are self-reported documents. A typical package includes a chromatographic trace, a mass spectrum, and a stated water or counter-ion content. Batch-to-batch consistency matters more than a single purity figure when results are compared across experiments. No single mandatory standard governs research-grade peptide release, so laboratories are expected to define their own acceptance criteria. Residual trifluoroacetate from purification is a frequently overlooked counter-ion.
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.
Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro. Its chain combines the first seven residues of corticotropin with a C-terminal proline-glycine-proline extension, a modification intended to slow enzymatic breakdown. The free peptide has a molecular mass near 813.9 daltons. It belongs to the class of ACTH-derived fragments studied for central nervous system activity rather than for adrenal steroid stimulation. This structural relationship to a natural hormone fragment is the usual starting point for describing the compound in the literature.
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.
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.
Practical handling follows from those properties. Bulk material is best divided into single-use portions soon after receipt, because each thaw exposes the whole container to moisture and temperature cycling. Vials should be allowed to reach room temperature before opening to prevent condensation on the powder. Low-binding plasticware reduces loss of dilute solutions, and sterile filtration is used when a preparation must remain free of microbial growth. Records of batch number, reconstitution date and storage history are what allow a later analytical result to be interpreted meaningfully.
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.
== Keratin removal == Keratin that is present in the hair, scales and in the epidermis of the skin is hydrolyzed in the presence of alkali (at pH values greater than 11.5). The disulfide bridges found in keratin protein are cleaved but can be reformed. Long periods of liming will result in hair removal. The main removal of keratin is performed during the unhairing operation. In traditional processing, liming and unhairing were indivisible and took place at the same time. During modern liming methods, and in particular the processing of sheepskins, the hair is removed first and then limed in a liming drum. In hair-save technology, the hides are unhaired first and then limed for a further 12–18 hours.
During Biko's life, the government alleged that he hated whites, various anti-apartheid activists accused him of sexism, and African racial nationalists criticised his united front with Coloureds and Indians. Nonetheless, Biko became one of the earliest icons of the movement against apartheid, and is regarded as a political martyr and the "Father of Black Consciousness". His political legacy remains a matter of contention.
== Selected articles == Meyer, D. E., & Chilkoti, A. (1999). Purification of recombinant proteins by fusion with thermally-responsive polypeptides. Nature Biotechnology, 17(11), 1112–1115. Nath, N., & Chilkoti, A. (2002). A colorimetric gold nanoparticle sensor to interrogate biomolecular interactions in real time on a surface. Analytical chemistry, 74(3), 504–509. Ma, H., Hyun, J. Chilkoti, A. (2004). "Nonfouling" oligoethylene glycol functionalized polymer brushes synthesized by surface-initiated atom transfer radical polymerization. Advanced Materials, 16, 338–341. Dreher, M. R., Liu, W., Michelich, C. R., Dewhirst, M. W., Yuan, F., & Chilkoti, A. (2006). Tumor vascular permeability, accumulation, and penetration of macromolecular drug carriers. Journal of the National Cancer Institute, 98(5), 335–344. Ciracì, C., Hill, R. T., Mock, J. J., Urzhumov, Y., Fernández-Domínguez, A. I., Maier, S. A., ... & Smith, D. R. (2012). Probing the ultimate limits of plasmonic enhancement. Science, 337(6098), 1072–1074.
=== Multiple Reaction Monitoring (MRM) === Although MRM has been used extensively in metabolomics and proteomics, its high sensitivity and linear response over a wide dynamic range make it especially suited for glycan biomarker research and discovery. MRM is performed on a triple quadrupole (QqQ) instrument, which is set to detect a predetermined precursor ion in the first quadrupole, a fragmented in the collision quadrupole, and a predetermined fragment ion in the third quadrupole. It is a non-scanning technique, wherein each transition is detected individually and the detection of multiple transitions occurs concurrently in duty cycles. This technique is being used to characterize the immune glycome. Table 1:Advantages and disadvantages of mass spectrometry in glycan analysis
Produced by Debra Bauer, directed by Chris Rawlence, made by Hayer Rawlence 18 November Superpowers? with Ray Hyman, about the international group of sceptics Committee for Skeptical Inquiry, who dispute topics such as UFOs; Paul Kurtz; Charles Honorton; Stanton T. Friedman and Philip J. Klass; psychologist Sue Blackmore; the Mars effect by French psychologist Michel Gauquelin, supported by psychologist Hans Eysenck; sociologist Marcello Truzzi; the Flixborough explosion in June 1974 and Lesley Castleton née Brennan from Weelsby Street, Cleethorpes, who had a premonition six hours before it took place, telling her friends at lunchtime before it had occurred; Russell Targ; physicist Robert G. Jahn and David Marks. Narrated by David Neal, executive produced by Jerome Kuehl, produced/directed by Adrian Pennink, made by Open Media 25 November Sex, Lies and Toupee Tape. with Neil Innes. Explores the medical conditions that result in baldness, as well as the dermatological and hormonal physiology of normal pattern balding in aging men (and women). Neil composes and performs songs to illustrate the topic, as well as acting as the guinea pig for numerous ancient and mythical remedies. The psychology and sociology of baldness is also examined, featuring wigs, toupees, ointments and surgical intervention. The programme visits the Bald Headed Men of America annual convention in Morehead North Carolina. It was written, produced and directed by Chris Haws and was an InCA production.
Sources: en.wikipedia.org
== Actions == Due to their modulatory and diffusive nature, neuropeptides can act on multiple time and spatial scales. A nearly complete map of these interactions is known for at least one small animal, C. elegans. For many other animals, at least some neuropeptide actions are known, as shown in the Examples section above.
There are many different biosynthesis pathways to ascorbic acid in plants. Most proceed through products of glycolysis and other metabolic pathways. For example, one pathway uses plant cell wall polymers. The principal plant ascorbic acid biosynthesis pathway seems to be via l-galactose. The enzyme l-galactose dehydrogenase catalyzes the overall oxidation to the lactone and isomerization of the lactone to the C4-hydroxyl group, resulting in l-galactono-1,4-lactone. l-Galactono-1,4-lactone then reacts with the mitochondrial flavoenzyme l-galactonolactone dehydrogenase to produce ascorbic acid. l-Ascorbic acid has a negative feedback on l-galactose dehydrogenase in spinach. Ascorbic acid efflux by embryos of dicot plants is a well-established mechanism of iron reduction and a step obligatory for iron uptake. All plants synthesize ascorbic acid. Ascorbic acid is a cofactor for enzymes involved in photosynthesis, synthesis of plant hormones, as an antioxidant and regenerator of other antioxidants. Plants use multiple pathways to synthesize vitamin C. The major pathway starts with glucose, fructose or mannose (all simple sugars) and proceeds to l-galactose, l-galactonolactone and ascorbic acid. This biosynthesis is regulated following a diurnal rhythm. Enzyme expression peaks in the morning to supporting biosynthesis for when mid-day sunlight intensity demands high ascorbic acid concentrations.
Amitriptyline inhibits serotonin transporter (SERT) and norepinephrine transporter (NET). It is metabolized to nortriptyline, a stronger norepinephrine reuptake inhibitor, further augmenting amitriptyline's effects on norepinephrine reuptake (see table in this section). Amitriptyline additionally acts as a potent antagonist of the serotonin 5-HT2A, 5-HT2C, the α1A-adrenergic, the histamine H1 and the M1-M5 muscarinic acetylcholine receptors (see table in this section). Amitriptyline is a non-selective blocker of multiple ion channels, in particular, voltage-gated sodium channels Nav1.3, Nav1.5, Nav1.6, Nav1.7, and Nav1.8, voltage-gated potassium channels Kv7.2/ Kv7.3, Kv7.1, Kv7.1/KCNE1, and hERG.
The Bacillus Calmette–Guérin (BCG) vaccine is a vaccine primarily used against tuberculosis (TB). It is named after its inventors Albert Calmette and Camille Guérin. In countries where tuberculosis or leprosy is common, one dose is recommended in healthy babies as soon after birth as possible. In areas where tuberculosis is not common, only children at high risk are typically immunized, while suspected cases of tuberculosis are individually tested for and treated. Adults who are frequently exposed to tuberculosis may also be immunized. BCG has some effectiveness against Buruli ulcer infection and other nontuberculous mycobacterial infections. It is also often used as part of the treatment of bladder cancer. Rates of protection against tuberculosis infection vary widely and protection lasts up to 20 years. Among children, it prevents about 20% from getting infected and among those who do get infected, it protects half from developing disease. The vaccine is injected into the skin. No evidence shows that additional doses are beneficial. Serious side effects are rare. Redness, swelling, and mild pain often occur at the injection site. A small ulcer may also form with some scarring after healing. Side effects are more common and potentially more severe in those with immunosuppression. Although no harmful effects on the fetus have been observed, there is insufficient evidence about the safety of BCG vaccination during pregnancy. Therefore, the vaccine is not recommended for use during pregnancy.
Sources: en.wikipedia.org
According to this narrative, South African paratroopers opened fire on the refugees, mostly women and children; those not immediately killed were systematically rounded up into groups and bayoneted or shot. The alleged result was the massacre of at least 612 South West African civilians, almost all elderly men, women, and children. The SADF narrative concurred with a death toll of approximately 600 but claimed that most of the dead were insurgents killed defending a series of trenches around the camp. South African sources identified Cassinga as a PLAN installation on the basis of aerial reconnaissance photographs, which depicted a network of trenches as well as a military parade ground. Additionally, photographs of the parade ground taken by a Swedish reporter just prior to the raid depicted children and women in civilian clothing, but also uniformed PLAN guerrillas and large numbers of young men of military age. SWAPO maintained that it ordered the trenches around Cassinga dug to shelter the otherwise defenceless refugees in the event of a SADF raid, and only after camp staff had noted spotter planes overhead several weeks prior. It justified the construction of a parade ground as part of a programme to instill a sense of discipline and unity. Western journalists and Angolan officials counted 582 corpses on site a few hours after the SADF's departure. The SADF suffered 3 dead and 1 missing in action.
A gas panel or gas manifold is the control equipment for supplying the breathing gas to the divers. Primary and reserve gas is supplied to the panel through shutoff valves from a low-pressure compressor or high-pressure storage cylinders ("bombs", "bundles", "quads", or "kellys"). The gas pressure may be controlled at the panel by an industrial pressure regulator, or it may already be regulated closer to the source (at the compressor, or at the storage cylinder outlet). The supply gas pressure is monitored on a gauge at the panel, and an over-pressure valve is fitted in case the supply pressure is too high. The gas panel may be operated by the diving supervisor if the breathing gas is air or a fixed ratio premix, but if the composition must be controlled or monitored during the dive it is usual for a dedicated gas panel operator, or "gas man" to do this work. There is a set of valves and gauges for each diver to be supplied from the panel. These include:
Wallace Michael Shawn (born November 12, 1943) is an American actor, essayist, and writer. He is known for playing Vizzini in The Princess Bride (1987), Mr. Hall in Clueless (1995), and Dr. John Sturgis in Young Sheldon (2017–2024), and for voicing Rex the Dinosaur in the Toy Story franchise (1995–2026). Shawn also appeared in The Bostonians (1984), Prick Up Your Ears (1987), Scenes from the Class Struggle in Beverly Hills (1989), Vanya on 42nd Street (1994), The Haunted Mansion (2003), The Incredibles (2004), Southland Tales (2006), The Double (2013), and Marriage Story (2019). He appeared in six Woody Allen films including Manhattan (1979), Radio Days (1987), and Rifkin's Festival (2020). His television work includes recurring roles as Arnie Ross in Taxi (1978-1983), Jeff Engels in The Cosby Show (1987–1991), Grand Nagus Zek in Star Trek: Deep Space Nine (1993–1999), Cyrus Rose in Gossip Girl (2008–2012), and Father Frank Ignatius in Evil (2022–2024). Shawn is also a playwright; his plays include the Obie Award–winning Aunt Dan and Lemon (1985), The Designated Mourner (1996), Grasses of a Thousand Colors (2008), and What We Did Before Our Moth Days (2026). With Andre Gregory, he wrote and starred in the 1981 drama My Dinner with Andre. He played the title role in A Master Builder (2013), a film adaptation of Henrik Ibsen's 1892 play. Haymarket Books published his books Essays (2009) and Night Thoughts (2017).
=== Characters and setting === Decay is set in the same location and timeframe as Half-Life. Half-Life takes place at a laboratory called the Black Mesa Research Facility, situated in a remote desert in New Mexico. In Half-Life, the player takes on the role of Gordon Freeman, a scientist involved in an accident that opens an inter-dimensional portal to the borderworld of Xen, allowing the alien creatures of Xen to attack the facility. The player guides Freeman in an attempt to escape the facility and close the portal, ultimately traveling to Xen to do so. Like the previous expansions, Decay shows the story of Half-Life from the perspective of a different set of protagonists. In Decay, players assume the roles of Colette Green and Gina Cross, two doctors who work in the same labs as Freeman, analyzing anomalous materials and specimens retrieved from Xen in prior teleportation experiments. After the experiment that causes the alien invasion takes place, Green and Cross must work with two ranking members of the science team, Dr. Richard Keller and Dr. Rosenberg, to contain and stabilize the deteriorating situation in Black Mesa.
The isotopic compositions of ice cores from continental ice sheets and alpine glaciers have been developed as temperature proxies since the 1950s. Samuel Epstein was one of the first to show the applicability of this proxy by measuring oxygen isotopes in Antarctic snow, and also pointed out complications in the stable isotope-temperature correlation caused by the history of the air masses from which the snow formed. Ice cores in Greenland and Antarctica can be thousands of meters thick and record snow isotopic composition of the past few glacial-interglacial cycles. Ice cores can be dated by layer counting on the top and ice flow modeling at depth, with additional age constraints from volcanic ash. Cores from Greenland and Antarctica can be aligned in age at high-resolution by comparing globally well-mixed trace gas (e.g. CH4) concentrations in the air bubbles trapped in the cores. Some of the first ice core records from Greenland and Antarctica with age estimates go back to the last 105 years, and showed a depletion in δD and δ18O in the last ice age. The ice core record has since been extended to the last 800,000 years in Antarctica, and at least 250,000 years in Greenland. One of the best δD-based ice core temperature records is from the Vostok ice core in Antarctica, which goes back to 420,000 years. The δD-temperature (of the inversion layer where snow forms) conversion in east Antarctica based on modern spatial gradient of δD (9‰/°C) is ΔTI=(ΔδDice-8Δδ18Osw)/9, which takes into account variations in seawater isotopic composition caused by global ice volume changes.
Sources: en.wikipedia.org
Semax is based on the ACTH(4-10) fragment, a seven-amino-acid segment of adrenocorticotropic hormone. The synthetic peptide retains the core sequence while removing regions associated with endocrine activity. This modification is intended to isolate effects on the nervous system.
It is registered for clinical use in Russia and a few other countries, typically as a nasal drop formulation. It does not hold approval from the United States Food and Drug Administration or the European Medicines Agency. Outside those markets it is generally handled as a research chemical.
The compound was developed in Moscow and the earliest studies were conducted there, so the primary literature is largely in Russian-language journals. Translation and indexing have been incomplete, which limits access for outside researchers. Independent groups have since published some work, but the total volume remains modest.
It is associated with the melanocortin receptor family, particularly subtypes found in the central nervous system. This interaction is separate from the adrenal pathway activated by full-length ACTH.