shelf life comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Last reviewed on 2026-01-30. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
Identity and purity are confirmed with reversed-phase high-performance liquid chromatography, typically monitored at 214 nanometres where the peptide bond absorbs. Mass spectrometry, either electrospray or MALDI-TOF, verifies molecular mass against the theoretical value and detects truncation or adduct formation. Amino acid analysis and peptide mapping provide additional confirmation when required. The most frequently reported impurities are deletion sequences from incomplete coupling, methionine sulfoxide from oxidation, and dimeric species formed through non-covalent aggregation. Impurity profiles depend strongly on the synthesis and purification route chosen by the producer.
Published research has focused mainly on neurological and cognitive endpoints in animal models, with proposed mechanisms involving brain-derived neurotrophic factor and related signalling pathways. A substantial share of the human data originates from a limited number of research groups, and independent replication in other countries remains sparse. Regulatory status reflects that distribution: the peptide is registered as a medicine in Russia and appears in some neighbouring markets, while elsewhere it is handled as a research chemical without approved therapeutic labelling. Questions about dose-response relationships, long-term effects, and comparability across studies are still open.
Lyophilised powder is normally kept at -20 °C in a desiccated container, with some suppliers recommending -80 °C for long-term archival storage. Repeated freeze-thaw cycles are the most common cause of avoidable loss, so aliquoting before freezing reduces variability between working sessions. Dissolved peptide is far less stable than the dry solid and is usually prepared fresh or held briefly at 4 °C. Aqueous solutions support both hydrolysis of the backbone and oxidation of the N-terminal methionine, and these two routes dominate degradation under ordinary laboratory conditions.
| Property | Value | Notes |
|---|---|---|
| Sequence | Met-Glu-His-Phe-Pro-Gly-Pro | Heptapeptide; ACTH(4-10) analog extended at C-terminus |
| Molecular mass | ~813.9 Da | Free peptide, unmodified |
| Appearance | White to off-white powder | Typical lyophilized solid |
| Solubility | Soluble in water and saline | Also soluble in common aqueous buffers |
| Storage (solid) | -20 °C, desiccated | Protect from moisture and repeated thawing |
Later generations of the molecule include an N-acetylated form and an amidated form, both marketed online alongside the parent peptide. These variants differ in terminal chemistry and stability, and they are frequently discussed in the same breath even though they have not been compared in controlled trials. Supply outside formal healthcare systems comes largely from laboratories that synthesize peptides to order. Purity and identity of these materials vary widely, and no single body oversees the international trade.
Semax is a synthetic heptapeptide developed in the Soviet Union during the 1980s by researchers at the Institute of Molecular Genetics in Moscow. It was designed as a truncated analog of adrenocorticotropic hormone, retaining only the fragment spanning residues four through ten. Investigators sought a peptide that would preserve the cognitive effects associated with ACTH while eliminating the hormonal stimulation of the adrenal cortex. The compound entered clinical use in Russia during the following decade.
稳定性主要由水解与氧化两条路径支配。肽键在中性或弱酸性条件下相对稳定，遇到强碱或长时间高温则明显断裂；甲硫氨酸侧链容易被氧化成亚砜，使主峰前移并拉低实际含量。金属离子、光照和反复冻融会进一步促进降解或聚集。冻干粉在低温避光条件下可存放较长时间，配制后的水溶液通常需要冷藏并尽快用完。
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。
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.
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.
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.
== Other animals == The prostate is found only in mammals. The prostate glands of male marsupials are proportionally larger than those of placental mammals. The presence of a functional prostate in monotremes is controversial, and if monotremes do possess functional prostates, they may not make the same contribution to semen as in other mammals. The structure of the prostate varies, ranging from tubuloalveolar (as in humans) to branched tubular. The gland is particularly well developed in carnivorans and boars, though in other mammals, such as bulls, it can be small and inconspicuous. In other animals, such as marsupials and small ruminants, the prostate is disseminate, meaning not specifically localisable as a distinct tissue, but present throughout the relevant part of the urethra; in other animals, such as red deer and American elk, it may be present as a specific organ and in a disseminate form. In some marsupial species, the size of the prostate gland changes seasonally. The prostate is the only accessory gland that occurs in male dogs. Dogs can produce in one hour as much prostatic fluid as a human can in a day. They excrete this fluid along with their urine to mark their territory. Additionally, dogs are the only species apart from humans seen to have a significant incidence of prostate cancer. The prostate is the only male accessory gland that occurs in cetaceans, consisting of diffuse urethral glands surrounded by a very powerful compressor muscle. The prostate gland originates with tissues in the urethral wall.
The lotus roots grow in pond or river bottom soil, while the leaves float on the water's surface or are held well above it. The leaf stalks (petioles) can be up to 200 cm (6 ft 7 in) long, allowing the plant to grow in water to that depth. The peltate leaf blade or lamina can have a diameter of 80–100 cm (2 ft 7 in – 3 ft 3 in). The leaves are spaced up to 2 m (6 ft 7 in) apart along the rhizome, which can grow as much as 20 m (66 ft) in one year. The internodes are not cylindrical but swollen in the middle.
== Niger, Chad, Benin, CAR == Amadou Boubacar Cissé – politician, former prime minister, former Minister of State for Planning, Regional Development, and Community Development, Niger Mamadou Tandja (Fula/Soninke)- former president, Niger Hama Amadou – politician, former prime minister and president of the National Assembly of Niger Amadou Cheiffou – politician, former prime minister of Niger Albadé Abouba – politician, former acting prime minister, Current Minister of State, Minister of Agriculture and Livestock. Niger Bibata Niandou Barry - former Minister of women Affairs. Salifou Modi - former chief of staff, Nigerien Army, Vice President of the National Council for the Safeguard of the Homeland (Military Junta). Aissa Diori - former first lady, Niger Amina Bazindre - former ambassador to romania, Hungary, Germany and Russia. Fatou Djibo - author, first Nigerian woman to drive a car. Bouli Ali Diallo - academic, activist. Abdou Abarry - Nigerian diplomat, former president united nations security council, special representative for Central Africa and Head of the United Nations Regional Office for Central Africa. Ide Oumarou - diplomat, government minister, and journalist, former secretary-general of the Organization of African Unity Abdel Kader Baba-Laddé (or General Baba Laddé or Mahamat Abdoul Kadre) – politician, Chad. Aïchatou Boulama Kané - first female governor of Niamey, former minister of foreign affairs.
Sample acquisition: the most commonly used samples for metagenomic sequencing are blood, stool, cerebrospinal fluid (CSF), urine, or nasopharyngeal swabs. Among these, blood and CSF are the cleanest, having less background noise, while the others are expected to have a great amount of commensals and/or opportunistic infections and thus have more background noise. Samples should be collected with much caution as surgical specimens could be contaminated during handling of the biopsy; for example, lumbar punctures to obtain CSF specimens may be contaminated during the procedure. RNA/DNA extraction: the DNA and the RNA of the sample is extracted by using an extraction kit. If there is a strong previous suspicion of the pathogen genome composition and since the amount of pathogen nucleic acid in more noise samples is overwhelmed by the RNA/DNA of other organisms, selecting an extraction kit of only RNA or DNA would be a more specific and convenient approach. Some commerciable available kits are for example RNeasy PowerSoil Total RNA kit (Qiagen), RNeasy Minikit (Qiagen), MagMAX Viral Isolation kit (ABI), Viral RNA Minikit (Qiagen). Optimization strategies for library preparation: because of high levels of background noise in metagenomic sequencing, several target enrichment procedures have been developed that aim to increase the probability of capturing pathogen-derived transcripts and/or genomes. Generally there are two main approaches that can be used to increase the amount of pathogen signal in a sample: negative selection and positive enrichment.
Sources: en.wikipedia.org
=== Serotonin reuptake inhibition === All SSRIs block the reuptake of serotonin through the serotonin transporter (SERT). This occurs in various anatomical sites, including the presynaptic terminals of serotonergic neurons in the central and peripheral nervous systems, enteric neurons and epithelial cells in the gastrointestinal tract, the pulmonary endothelium, and platelets. In the central nervous system, the majority of released serotonin is taken up by SERT. When this process is blocked, it stays in the synaptic gap longer than it normally would, and may repeatedly stimulate the receptors of the postsynaptic cell. In the short run, this leads to an increase in signaling across synapses in which serotonin is the primary neurotransmitter. On chronic dosing, the increased occupancy of post-synaptic serotonin receptors signals the pre-synaptic neuron to synthesize and release less serotonin. Serotonin levels within the synapse drop, then rise again, ultimately leading to downregulation of post-synaptic serotonin receptors. Other, indirect effects may include increased norepinephrine output, increased neuronal cyclic AMP levels, and increased levels of regulatory factors such as BDNF and CREB.
== Medical uses == Datopotamab deruxtecan is indicated for the treatment of adults with unresectable or metastatic, hormone receptor positive, human epidermal growth factor receptor 2-negative (IHC 0, IHC1+ or IHC2+/ISH-) breast cancer who have received prior endocrine-based therapy and chemotherapy for unresectable or metastatic disease. In June 2025, the US Food and Drug Administration (FDA) expanded the indication to include the treatment of adults with locally advanced or metastatic epidermal growth factor receptor-mutated non-small cell lung cancer who have received prior epidermal growth factor receptor-directed therapy and platinum-based chemotherapy. In May 2026, the FDA expanded the indication to include the treatment of adults with unresectable or metastatic triple-negative breast cancer who are not candidates for PD-1/PD-L1 inhibitor therapy.
Au-catalyzed Cys alkylation Cysteine-containing peptides have been shown to undergo 1,2-addition to allenes in the presence of gold(I) and/or silver(I) salts, producing hydroxyl substituted vinyl thioethers. The reaction with peptides proceeds with high yields and is selective for cysteines over other nucleophilic residues. However, the reactivity towards proteins is much decreased, potentially due to the coordination of gold to the protein backbone.
Most industries are located in the industrial-port area north of the estuary and east of the city of Le Havre. The largest industrial employer (2,400 employees) of the Le Havre region is the Renault public company in the commune of Sandouville. The second important sector for the industrial zone is petrochemicals. The Le Havre region has more than a third of French refining capacity. It provides about 50% of the production of basic plastics and 80% of additives and oils with more than 3,500 researchers working in private and public laboratories. Large firms in the chemical industry are mainly in the communes of Le Havre (Millenium Chemicals Le Havre), Montivilliers (TotalEnergies, Yara, Chevron Oronite SA, Lanxess, etc.) and Sandouville (Goodyear Chemicals Europe). A total of 28 industrial establishments manufacture plastics in the Le Havre area many of which are classed as SECESO. There are several firms in the aerospace industry: SAFRAN Nacelles, a supplier to Airbus, Boeing and other commercial air-framers, making jet engine nacelles and thrust reversers, is located in Harfleur and employs 1,200 people from the Le Havre area. Finally, Dresser-Rand SA manufactures equipment for the oil and gas industry and employs about 700 people. In the energy field, the EDF thermal power plant of Le Havre has an installed capacity of 1,450MW and operates using coal with 357 employees. The AREVA group announced the opening of a factory for building wind turbines: installed in the port of Le Havre, it should create some 1,800 jobs.
== Sticky-end ligation == Restriction enzymes can generate a wide variety of ends in the DNA they digest, but in cloning experiments most commonly used restriction enzymes generate a 4-base single-stranded overhang called the sticky or cohesive end (exceptions include NdeI which generates a 2-base overhang, and those that generate blunt ends). These sticky ends can anneal to other compatible ends and become ligated in a sticky-end (or cohesive end) ligation. EcoRI for example generates an AATT end, and since A and T have lower melting temperature than C and G, its melting temperature Tm is low at around 6°C. For most restriction enzymes, the overhangs generated have a Tm that is around 15°C. For practical purposes, sticky end ligations are performed at 12-16°C, or at room temperature, or alternatively at 4°C for a longer period. For the insertion of a DNA fragment into a plasmid vector, it is preferable to use two different restriction enzymes to digest the DNA so that different ends are generated. The two different ends can prevent the religation of the vector without any insert, and it also allows the fragment to be inserted in a directional manner. When it is not possible to use two different sites, then the vector DNA may need to be dephosphorylated to avoid a high background of recircularized vector DNA with no insert. Without a phosphate group at the ends the vector cannot ligate to itself, but can be ligated to an insert with a phosphate group.
Sources: en.wikipedia.org
=== Values of spin angular momentum === Nuclear spin is an intrinsic angular momentum that is quantized. This means that the magnitude of this angular momentum is quantized (i.e. S can only take on a restricted range of values), and also that the x, y, and z-components of the angular momentum are quantized, being restricted to integer or half-integer multiples of ħ, the reduced Planck constant. The integer or half-integer quantum number associated with the spin component along the z-axis or the applied magnetic field is known as the magnetic quantum number, m, and can take values from +S to −S, in integer steps. Hence for any given nucleus, there are a total of 2S + 1 angular momentum states. The z-component of the angular momentum vector (
=== Efficacy === 2,6-Dichloro-1,4-benzoquinone is primarily used in research due to its ability to participate in electron transfer reactions. In photosynthesis, it can act as an artificial electron acceptor in photosystem II. Researchers can measure and analyse electron transport activity in chloroplasts and other photosynthetic systems. The ability to accept electrons in place of natural quinones makes the compound useful for investigating the mechanisms of photosynthetic energy conversion and for evaluating the effects of inhibitors or environmental stress on photosynthetic organisms. In addition, 2,6-DCBQ can inhibit enzymes such as acetylcholinesterase in laboratory experiments and may exhibit antimicrobial or algal toxicity due to its reactive quinone structure. These characteristics are mainly of research interest rather than therapeutic application.
γ-Amino-β-hydroxybutyric acid (GABOB), also known as β-hydroxy-γ-aminobutyric acid (β-hydroxy-GABA), sold under the brand name Gamibetal among others, is an anticonvulsant which is used for the treatment of epilepsy in Europe, Japan, and Mexico. It is a GABA analogue, or an analogue of the neurotransmitter γ-aminobutyric acid (GABA), and has been found to be an endogenous metabolite of GABA.
Although councils had already suffered deep cuts under Labour in the 1970s, Heseltine was under pressure from Thatcher and from Conservative MPs and newspapers to cut more. Heseltine's initial suggestion, that councils who wanted to increase the rates be forced to submit to re-election, was rejected by the Cabinet, in favour of a proposal that such increases be put to referendum (in Coventry, voters had recently voted by over 7:1 for spending cuts rather than a supplementary rate increase). This proposal in turn was attacked by Conservative backbenchers, both as an infringement of council freedom and a risky precedent for national taxation, both in the Environment Committee and in the debate on a bill which Heseltine introduced and had to withdraw. Heseltine then banned supplementary rates and imposed stiffer sanctions on overspending councils. Thatcher's 1974 pledge to abolish the rates and replace them with a new form of local government funding was still in force. However, the 1979 manifesto made clear that income tax cuts took priority over rates reform. Thatcher also blocked the upward revaluation of property rating values in 1982. A review of rates reform was begun in 1981, in which his junior minister Tom King personally spoke to every single backbench Conservative MP to canvass opinion about the various options. A Green Paper was produced in December 1981, recommending that no single alternative to the rates suggested itself.
Sources: en.wikipedia.org
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.
Its sequence corresponds to the 4-10 region of corticotropin extended by three residues. This fragment lacks the region responsible for adrenal steroid release, so it is explored for neural rather than hormonal effects. The relationship explains the compound's classification among ACTH-derived peptides.
It holds approval in Russia for several neurological indications as a nasal spray or drop formulation. Regulatory agencies in the United States and the European Union have not approved it. Products sold elsewhere are generally labeled for research use only.
Reversed-phase HPLC gives the main purity figure, most often with UV detection near 214 nanometres. Mass spectrometry then confirms the molecular mass. Together the two methods distinguish a correct sequence from a closely related impurity.