Everything below concerns shelf life. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2025-09-13. Where a claim depends on a specific study, the study is described rather than over-claimed.
Once dissolved, the peptide is considerably less stable than the solid. Aqueous solutions are usually prepared at neutral to slightly acidic pH, filtered, and divided into single-use aliquots before freezing. Repeated freeze-thaw cycles are a common cause of avoidable loss and are best prevented by never refreezing a thawed aliquot. Adsorption to plastic and glass surfaces can lower the measured concentration of dilute solutions, particularly below roughly 0.1 mg/mL. Buffer choice, salt content, and container material all influence how much peptide remains detectable after storage.
Identity and purity are established with standard peptide methods. Reversed-phase HPLC with ultraviolet detection near 214 nm resolves the parent peak from deletion and truncation byproducts, and reports typically quote a main-peak percentage. Mass spectrometry by electrospray or MALDI-TOF confirms the expected molecular mass, while amino acid analysis or peptide mapping can verify composition when the sequence itself is in question. A certificate of analysis that pairs a chromatogram with a mass spectrum is more informative than a purity figure alone. Counter-ion content and residual solvents are separate specifications and are frequently omitted.
Semax is normally supplied as a lyophilized powder, and that form is the most stable. Suppliers commonly recommend storage at -20 °C in a desiccated container protected from light, with short-term handling at room temperature limited to weighing and transfer. Powder that has absorbed moisture degrades faster, so vials should be warmed to ambient temperature before opening to prevent condensation on the contents. Hygroscopic behavior is typical of short hydrophilic peptides, and humidity control matters more than temperature alone for long-term retention.
Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro. Its design combines the ACTH(4-7) core fragment with a C-terminal Pro-Gly-Pro extension, a modification intended to improve stability and prolong activity. The molecule is hydrophilic, carries no lipid chains or glycosylation, and has a theoretical mass just over 810 daltons in its free form. All seven residues are proteinogenic amino acids, so no non-natural building blocks appear in the backbone. A free N-terminal methionine and C-terminal proline define the unmodified parent peptide.
The compound was developed during the 1980s at the Institute of Molecular Genetics in Moscow as part of research on fragments of adrenocorticotropic hormone. Early work examined short ACTH-derived sequences that retained neurotrophic effects while lacking the endocrine activity of the full hormone. Semax entered clinical use in Russia during the 1990s, where it received registration for several neurological indications. Outside that region it remained primarily a laboratory research material rather than an approved therapeutic. English-language literature on it grew more slowly and frequently cited the original Russian studies.
| Property | Value | Notes |
|---|---|---|
| Solid storage temperature | -20 °C or below | Desiccated and protected from light |
| Solution storage temperature | -80 °C as single-use aliquots | Avoid repeated freeze-thaw cycles |
| Purity assessment method | RP-HPLC, around 214 nm | Reported as main-peak area percent |
| Identity confirmation method | ESI-MS or MALDI-TOF | Measured mass compared with calculated mass |
| Common synonyms | ACTH(4-10) analog; Met-Glu-His-Phe-Pro-Gly-Pro | Also written as Semaxum in some sources |
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.
Pharmacological accounts link semax to melanocortin signalling and to modulation of neurotrophic factor expression, particularly brain-derived neurotrophic factor and nerve growth factor. Much of this evidence comes from rodent studies using intranasal delivery, a route chosen because it allows peptides to reach the central nervous system with limited systemic exposure. Whether the same mechanisms operate in humans at comparable magnitude remains an open question. The precise receptor or receptors responsible for the reported behavioural and neuroprotective effects have not been conclusively identified.
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.
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.
Semax is a synthetic peptide created in the Soviet Union during the early 1980s by researchers working in Moscow. It was built from the short adrenocorticotropic hormone fragment known as ACTH(4-10), and the chain was then extended with three additional amino acids. The resulting molecule was named semax and entered clinical use in Russia in 1994. It is generally described as a nootropic and neuroprotective agent rather than as a hormone analogue.
The parent fragment ACTH(4-10) carries the sequence Met-Glu-His-Phe-Arg-Trp-Gly. Semax replaces the arginine and tryptophan positions with a proline-glycine-proline tail, giving Met-Glu-His-Phe-Pro-Gly-Pro. That change removes residues associated with adrenal stimulation, so the peptide does not drive cortisol release the way full ACTH does. This distinction shapes how the compound is grouped in the literature, where it sits with neuropeptides and peptide neuromodulators rather than with corticosteroids.
== Synthesis == Phosphorimidazolide reagents have been synthesized from phosphate mono-esters. In one method, a phosphate mono-ester is dissolved in anhydrous pyridine or N,N-dimethylformamide (DMF) and activated using triphenylphosphine (PPh3) and 2,2’-Dithiodipyridine (2,2’-DTDP) in the presence of triethylamine (TEA) base and excess imidazole. In another method using fewer reagents, a phosphate mono-ester is dissolved in DMF and carbonyldiimidazole (CDI) is used to both remove an oxygen atom from the phosphate group and supply the imidazole substituent. The product of either reaction may be collected by precipitation using acetonitrile or acetone as antisolvent with sodium or lithium perchlorate to supply the sodium or lithium salt of the phosphorimidazolide respectively. Alternatively, the phosphorimidazolide may be isolated by reverse-phase flash column chromatography with TEAB buffer and acetonitrile.
The epithelial lining of the mucosa, differs along the gastrointestinal tract. The epithelium is described as stratified if it consists of multiple layers of cells, and simple if it is made up of one layer of cells. Terms used to describe the shape of the cells in it - columnar if column-shaped, and squamous if flat.
== Treatment == The main focus of treatment for AGAT deficiency is supplementation of creatine, with the goal of replenishing cerebral creatine to normal levels. This is done with oral creatine supplementation. Treatment is most effective if it is started early in life, before symptoms are apparent. Treatment in affected individuals does not reverse intellectual disability or improve cognitive function. For treatment at any age, even if intellectual disability was present, all individuals showed improvement in muscle weakness. In an asymptomatic sibling, who was started on treatment due to the earlier diagnosis of an affected sibling, early intervention with creatine supplementation resulted in improved outcomes when compared to their untreated siblings at the same age. In addition to clinical findings, the effectiveness of treatment can be monitored by following creatine levels in blood and urine as well as the creatine signal by MRS. As creatine is rapidly converted and excreted as creatinine, treatment must be life long to continue to benefit the patient. Treatment during the early years of brain development is most important for preserving brain function.
Sources: en.wikipedia.org
where aij is the number of atoms of element i in molecule j and b0i is the total number of atoms of element i, which is a constant, since the system is closed. If there are a total of k types of atoms in the system, then there will be k such equations. If ions are involved, an additional row is added to the aij matrix specifying the respective charge on each molecule which will sum to zero. This is a standard problem in optimisation, known as constrained minimisation. The most common method of solving it is using the method of Lagrange multipliers (although other methods may be used). Define:
The "Venus" figurines have been theorized, not universally, as representing a mother goddess; the abundance of such female imagery has inspired the theory that religion and society in Paleolithic (and later Neolithic) cultures were primarily interested in, and may have been directed by, women. Adherents of the theory include archaeologist Marija Gimbutas and feminist scholar Merlin Stone, the author of the 1976 book When God Was a Woman. Other explanations for the purpose of the figurines have been proposed, such as Catherine McCoid and LeRoy McDermott's hypothesis that they were self-portraits of woman artists and R.Dale Gutrie's hypothesis that served as "Stone Age pornography".
After the invasion, the Iraqi military looted over $1 billion in banknotes from Kuwait's Central Bank. At the same time, Saddam Hussein made the Kuwaiti dinar equal to the Iraqi dinar, thereby lowering the Kuwaiti currency to one-twelfth of its original value. In response, Sheikh Jaber al-Ahmad al-Sabah ruled the banknotes as invalid and refused to reimburse stolen notes, which became worthless because of a UN embargo. After the conflict ended, many of the stolen banknotes made their way back into circulation. The stolen banknotes are a collectible for numismatists.
== Taxonomy == The cabbage looper larva is a type of cabbage worm, a general term for a Lepidopteran pest that primarily feeds on crucifers. They closely resemble each other, in that they are all smooth and green, but they are not closely related in terms of phylogeny. In fact, none of the cabbage worms bear close phylogenetic relations, as they are all from different families. The cabbage looper is a member of the family Noctuidae, one of the largest families in Lepidoptera. It is related to other vegetable pests, like the cutworm and armyworms.
Sources: en.wikipedia.org
== Prognosis == Proper treatment of SAAM often results in full recovery. Recovery can occur even with persistently elevated creatine kinase (CK) levels. Conversely, some people with SAAM do not regain full muscle strength despite the normalization of their CK levels. Longitudinal analysis of a patient cohort revealed that the majority of patients (85%) over 60 years old recovered full strength within four years, compared to less than half of patients below 52 years old, indicating that age during disease onset may be an important prognostic determinant. Once strength recovers, immunosuppressive medications should be tapered. Relapse remains possible during tapering efforts, and some people require long-term immunosuppression. An affected person is more likely to experience permanent muscle damage if they do not receive adequate treatment for a long time. Muscle weakness occurs due to the replacement of some muscle with fatty tissue.
Cutaneous small-vessel vasculitis (CSVV) is inflammation of small blood vessels, usually accompanied by small lumps beneath the skin. The condition is also known as hypersensitivity vasculitis, cutaneous leukocytoclastic vasculitis, hypersensitivity angiitis, cutaneous leukocytoclastic angiitis, cutaneous necrotizing vasculitis and cutaneous necrotizing venulitis, It is the most common form of vasculitis seen in clinical practice, usually caused by inflammation of post-capillary venules in the dermis). "Leukocytoclastic" (literally meaning 'leukocyte-destroying') refers to the damage caused by nuclear debris from infiltrating neutrophils in and around the vessels.
Corneal transplantation, also known as corneal grafting, is a surgical procedure where a damaged or diseased cornea is replaced by donated corneal tissue (the graft). When the entire cornea is replaced it is known as penetrating keratoplasty and when only part of the cornea is replaced it is known as lamellar keratoplasty. Keratoplasty simply means surgery to the cornea. The graft is taken from a recently deceased individual with no known diseases or other factors that may affect the chance of survival of the donated tissue or the health of the recipient. The cornea is the transparent front part of the eye that covers the iris, pupil and anterior chamber. The surgical procedure is performed by ophthalmologists, physicians who specialize in eyes, and is often done on an outpatient basis. Donors can be of any age, as is shown in the case of Janis Babson, who donated her eyes after dying at the age of 10. Corneal transplantation is performed when medicines, keratoconus conservative surgery and cross-linking can no longer heal the cornea. This surgical procedure usually treats corneal blindness, with success rates of at least 41% as of 2021.
=== Physical === Most of the physical properties of astatine have been estimated (by interpolation or extrapolation), using theoretically or empirically derived methods. For example, halogens get darker with increasing atomic weight—fluorine is nearly colorless, chlorine is yellow-green, bromine is red-brown, and iodine is dark gray/violet. Astatine is sometimes described as probably being a black solid (assuming it follows this trend), or as having a metallic appearance (if it is a metalloid or a metal). Because it has a lower vapor pressure than iodine, astatine sublimes, as expected. Half of a given quantity of astatine will vaporize in approximately an hour if put on a clean glass surface at room temperature. The absorption spectrum of astatine in the middle ultraviolet region has lines at 224.401 and 216.225 nm, suggestive of 6p to 7s transitions. The structure of solid astatine is unknown. As an analog of iodine it may have an orthorhombic crystalline structure composed of diatomic astatine molecules, and be a semiconductor (with a band gap of 0.7 eV). Alternatively, if condensed astatine forms a metallic phase, as has been predicted, it may have a monatomic face-centered cubic structure; in this structure, it may well be a superconductor, like the similar high-pressure phase of iodine. Metallic astatine is expected to have a density of 8.91–8.95 g/cm3. Evidence for (or against) the existence of diatomic astatine (At2) is sparse and inconclusive.
Natural proteins can be engineered, for example, by directed evolution, novel protein structures that match or improve on the functionality of existing proteins can be produced. One group generated a helix bundle that was capable of binding oxygen with similar properties as hemoglobin, yet did not bind carbon monoxide. A similar protein structure was generated to support a variety of oxidoreductase activities while another formed a structurally and sequentially novel ATPase. Another group generated a family of G-protein coupled receptors that could be activated by the inert small molecule clozapine N-oxide but insensitive to the native ligand, acetylcholine; these receptors are known as DREADDs. Novel functionalities or protein specificity can also be engineered using computational approaches. One study was able to use two different computational methods: a bioinformatics and molecular modeling method to mine sequence databases, and a computational enzyme design method to reprogram enzyme specificity. Both methods resulted in designed enzymes with greater than 100 fold specificity for production of longer chain alcohols from sugar. Another common investigation is expansion of the natural set of 20 amino acids. Excluding stop codons, 61 codons have been identified, but only 20 amino acids are coded generally in all organisms. Certain codons are engineered to code for alternative amino acids including: nonstandard amino acids such as O-methyl tyrosine; or exogenous amino acids such as 4-fluorophenylalanine.
Sources: en.wikipedia.org
Each freeze-thaw cycle can degrade a fraction of the peptide and promote aggregation. Dividing a stock solution into single-use volumes removes repeated cycling as a variable. It also limits the time a thawed solution spends at room temperature.
A high main-peak percentage says little about identity, counter-ion content, or residual solvents. It also does not distinguish an isomer or a closely eluting analog. Mass confirmation and the accompanying documentation cover those gaps.
Salt form changes mass, solubility, and hygroscopicity, and acetate and trifluoroacetate salts behave differently in solution. Storage guidance still centers on -20 °C for powder and lower temperatures for solutions. The certificate should state which salt is present.
It is a synthetic seven-amino-acid peptide built from the ACTH(4-7) sequence plus a Pro-Gly-Pro tail. It belongs to the family of short ACTH fragments studied for nervous-system effects. Its backbone contains only standard amino acids.