The short version of aliquot fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2026-05-25. Anything still debated is marked as such rather than presented as settled.
Identity and purity are commonly assessed by reversed-phase high-performance liquid chromatography, with ultraviolet detection near 214 nanometers for the peptide backbone. Mass spectrometry, either electrospray or matrix-assisted laser desorption, confirms molecular mass and detects truncation or modification products. Amino acid analysis can verify composition. Because the sequence contains no strongly absorbing aromatic residue apart from phenylalanine, detection wavelengths are chosen carefully. Purity values above 95 percent are typical for research-grade material.
Quality documentation for research-grade peptide usually includes a certificate of analysis stating purity, identity, and residual counterion content. Batch-to-batch variation in purity and salt form is a recognized issue, and comparisons across suppliers require attention to the exact counterion, for example acetate versus trifluoroacetate. Sequence verification by tandem mass spectrometry provides stronger evidence than a single mass measurement. For any study reporting biological results, the analytical method and the measured purity should be stated explicitly. Independent verification of supplier claims is considered good practice.
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 purity | ≥95% by HPLC | Research-grade material |
| Detection wavelength | 214 nm | Peptide bond absorbance |
| Reconstitution medium | Sterile water or saline | Prepare fresh or aliquot immediately |
| Storage (solution) | -80 °C, single-use aliquots | Avoid repeated freeze-thaw cycles |
| Common salt form | Acetate or trifluoroacetate | Affects mass and solubility |
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.
The mechanisms attributed to semax are inferred from animal and cell studies rather than traced to one confirmed target. The most frequently cited pathway involves increased expression of brain-derived neurotrophic factor and nerve growth factor in hippocampal and cortical tissue. Some work points to engagement of melanocortin receptors, particularly MC4, which the parent ACTH fragment can activate. Effects on dopaminergic and serotonergic signalling have also been reported. No single account explains all observed results, and the relative weight of each pathway remains unsettled.
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.
Regulatory status varies sharply by country. Semax is registered for medical use in Russia, where it appears in formularies as a nasal solution, and it also holds registration in a small number of neighbouring states. It has no approval from the United States Food and Drug Administration or the European Medicines Agency, and it is not a scheduled controlled substance in most jurisdictions. Elsewhere it circulates mainly as laboratory material, so purity documentation comes from suppliers rather than from a national pharmacopoeia.
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.
Purity assessment relies mainly on reversed-phase high-performance liquid chromatography, which separates the target heptapeptide from truncated sequences, deletion analogues, and oxidised forms. Mass spectrometry, usually coupled to liquid chromatography, confirms identity through the expected molecular ion and reveals modifications such as methionine sulfoxide formation. Amino acid analysis can verify composition, and tandem mass spectrometry supports sequence confirmation. Ultraviolet detection near 254 to 280 nanometres is convenient because the phenylalanine and histidine residues absorb in that region. Nuclear magnetic resonance is rarely used for routine release testing.
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.
A light-emitting diode (LED) is an electronic component that uses a semiconductor to emit light when current flows through it. Electrons in the semiconductor recombine with electron holes, thereby releasing energy in the form of photons. The color of the light (corresponding to the energy of the photons) is determined by the energy required for electrons to cross the band gap of the semiconductor. White light is obtained by using multiple semiconductors or a layer of light-emitting phosphor on the semiconductor device. Appearing as practical electronic components in 1962, the earliest LEDs emitted low-intensity infrared (IR) light. Infrared LEDs are used in remote-control circuits, such as those used with a wide variety of consumer electronics. The first visible-light LEDs were of low intensity and limited to red. Early LEDs were often used as indicator lamps, replacing small incandescent bulbs, and in seven-segment displays. Later developments produced LEDs available in visible, ultraviolet (UV), and infrared wavelengths with high, low, or intermediate light output; for instance, white LEDs suitable for room and outdoor lighting. LEDs have also given rise to new types of displays and sensors, while their high switching rates have uses in advanced communications technology. LEDs have been used in diverse applications such as aviation lighting, fairy lights, strip lights, automotive headlamps, advertising, stage lighting, general lighting, traffic signals, camera flashes, lighted wallpaper, horticultural grow lights, and medical devices.
Ribosomes are essential for protein synthesis in all living organisms. Prokaryotic and eukaryotic ribosomes both contain a scaffold of ribosomal RNA (rRNA) on which are arrayed an extensive variety of ribosomal proteins (RP). Ribosomopathies can arise from abnormalities of either rRNA or the various RPs. The nomenclature of rRNA subunits is derived from each component's Svedberg unit, which is an ultracentrifuge sedimentation coefficient, that is affected by mass and also shape. These S units of the rRNA subunits cannot simply be added because they represent measures of sedimentation rate rather than of mass. Eukaryotic ribosomes are somewhat larger and more complex than prokaryotic ribosomes. The overall 80S eukaryotic rRNA structure is composed of a large 60S subunit (LSU) and a small 40S subunit (SSU). In humans, a single transcription unit separated by 2 internally transcribed spacers encodes a precursor, 45S. The precursor 45S rDNA is organized into 5 clusters (each has 30-40 repeats) on chromosomes 13, 14, 15, 21, and 22. These are transcribed in the nucleolus by RNA polymerase I. 45S is processed in the nucleus via 32S rRNA to 28S and 5.8S, and via 30S to 18S, as shown in the diagram. 18S is a component of the ribosomal 40S subunit. 28S, 5.8S and 5S, which is transcribed independently, are components of 60S. The 5S DNA occurs in tandem arrays (~200-300 true 5S genes and many dispersed pseudogenes); the largest is on chromosome 1q41-42. 5S rRNA is transcribed by RNA polymerase III.
=== Scientific societies === William H. Stein was a member of several scientific societies, including the: National Academy of Sciences (elected to membership in 1960), American Academy of Arts and Sciences (elected to membership in 1960), American Society of Biological Chemists, Biochemical Society of London, American Chemical Society, American Association for the Advancement of Science, and Harvey Society of New York.
=== Brain injury === There are similarities in what happens in the brain over time in Parkinson's disease and after a traumatic brain injury (TBI). PD is a progressive disorder, while TBI is an acute event that can be followed by both short- and long-term changes. Mechanisms common to both include changes in protein regulation, increased protein misfolding, protein aggregation, inflammation, and neurodegeneration. A history of TBI is reported as a risk factor for developing PD, but how mechanisms interact and whether TBI affects PD onset, development or progression are unclear.
"Any substance or combination of substances presented as having properties for treating or preventing disease in human beings; or" "Any substance or combination of substances which may be used in or administered to human beings either with a view to restoring, correcting, or modifying physiological functions by exerting a pharmacological, immunological or metabolic action or to making a medical diagnosis." In the US, a "drug" is:
Sources: en.wikipedia.org
== Antideuterium and the antideuteron == An antideuteron is the antimatter counterpart of the deuteron, consisting of an antiproton and an antineutron. The antideuteron was first produced in 1965 at the Proton Synchrotron at CERN and the Alternating Gradient Synchrotron at Brookhaven National Laboratory. A complete atom, with a positron orbiting the nucleus, would be called antideuterium, but as of 2019 antideuterium has not yet been created. The symbol used for antideuterium is D, that is, D with an overbar.
== Awards == JWD received the Thailand Sustainability Investment (THSI) award in 2018, 2019, 2020 and 2021 The award is granted to the listed companies with excellent performance in corporate governance and social responsibility.
According to the United States House Select Committee on Strategic Competition between the United States and the Chinese Communist Party, the Chinese government directly subsidizes producers of fentanyl precursors and analogues through tax rebates and other incentives. Since 2019, the Chinese government has removed online records of subsidies for fentanyl-related producers. In 2016, federal legislation loosened the de minimis exemption, which permitted parcels under $800 in value to enter the country duty-free with minimal inspection. The change in the de minimis eligibility led to the rapid growth in parcels coming from China, including those containing fentanyl. Deaths from fentanyl in 2016 increased by 540 percent across the United States since 2013. This accounts for almost "all the increase in drug overdose deaths from 2015 to 2016", according to a study published in the Journal of the American Medical Association. Readily available fentanyl killed 70,000 people in 2021 alone. Fentanyl-laced heroin has become a big problem for major cities, including Philadelphia, Detroit and Chicago. Its use has caused a spike in deaths among users of heroin and prescription painkillers, while becoming easier to obtain and conceal. Some arrested or hospitalized users are surprised to find that what they thought was heroin was actually fentanyl. According to former CDC director Tom Frieden in 2016:
===== Liver ===== In 2022, researchers proposed a new method for printing vascularized human liver tissue. This new method consisted of using a 3D printer capable of holding seven different bioinks, with the ability to switch rapidly between these different bioinks to print different structures and shapes in the liver tissue. Due to the overall complexity of the organ, they were unable to print an entire liver but were still able to successfully print pieces of densely vascularized liver tissue.
=== NAADP binding proteins === IP3 binds directly to its cognate IP3 receptor which is therefore a true ligand-gated ion channel. In contrast, NAADP does not appear to bind directly to TPCs but requires an intermediate unknown accessory protein(s). In sea urchin egg homogenate and T-cells, the binding protein(s) may be smaller than TPCs themselves, judging by photoaffinity labelling with [32P]azido-NAADP. Therefore, the NAADP receptor was believed to be a multi-protein complex on acidic vesicles. In spite of a decade of graft using conventional biochemical purification, these proteins remained elusive. Recently, two different NAADP-binding proteins have finally been identified that are essential for TPC activation: LSm12 and JPT2.
Sources: en.wikipedia.org
Following this, the European Green Party presented the European Parliament copies of contracts signed by two European companies and representatives of the President of Somalia, to accept 10 million tonnes of toxic waste for $80 million. According to reports by the United Nations Environment Programme (UNEP), the waste resulted in abnormally high cases of respiratory infections, mouth ulcers, mouth bleeding, abdominal haemorrhages and unusual skin infections among the inhabitants of and around the northeastern towns of Hobyo and Benadir. These diseases were consistent with radiation sickness. UNEP adds that the situation posed a very serious environmental hazard to Somalia and the broader eastern Africa sub-region.
Paul, and Stephen Walt concede that traditional balancing is not occurring, but argue nevertheless that rivals to the US are engaging in 'soft balancing.'More recent scholarly work has engaged the debate on soft balancing. Kai He suggested a new analytical framework, a negative balancing model, to explain why states do not form alliances or conduct arms races to balance against power or threats as they may have done in the past. He describes negative balancing as any strategy or diplomatic efforts aimed to undermine a rival's power. In contrast, positive balancing is actions or policies designed to strengthen a state's own power in world politics.
Intracerebroventricular injection (often abbreviated as ICV injection) is a route of administration for drugs via injection into the cerebral ventricles so that it reaches the cerebrospinal fluid (CSF). This route of administration is often used to bypass the blood-brain barrier because it can prevent important medications from reaching the central nervous system. This injection method is widely used in diseased mice models to study the effect of drugs, plasmid DNA, and viral vectors on the central nervous system. In humans, ICV injection can be used for the administration of drugs for various reasons. Examples include the treatment of Spinal Muscular Atrophy (SMA), the administration of chemotherapy in gliomas, and the administration of drugs for long-term pain management. ICV injection is also used in the creation of diseased animal models specifically to model neurological disorders.
=== Specific diseases === A common cause for hyperprolactinemia is prolactinomas and other tumors arising near the pituitary. These adjacent tumors, such as those that cause acromegaly, can physically compress the pituitary stalk and block the flow of dopamine from the hypothalamus to the pituitary gland, causing prolactin levels to increase. Other causes include chronic kidney failure, hypothyroidism, liver cirrhosis, bronchogenic carcinoma and sarcoidosis. Hyperprolactinemia develops in one-third of individuals with chronic kidney disease due to impaired renal clearance and regulation. Some women with polyendocrine metabolic ovarian syndrome may have mildly elevated prolactin levels. Premenstrual dysphoric disorder appears to be also correlated with elevated prolactin levels. In men, hyperprolactinemia leads to hypoactive sexual desire and, occasionally, erectile dysfunction. However, the link between erectile dysfunction and prolactin levels is not conclusive. When prolactin levels return to normal in these individuals, sexual desire fully recovers; however, erectile dysfunction only partially recovers. Nonpuerperal mastitis may induce transient hyperprolactinemia (neurogenic hyperprolactinemia) of about three weeks' duration; conversely, hyperprolactinemia may contribute to nonpuerperal mastitis. Some inflammatory conditions, such as rheumatoid arthritis and systemic lupus erythematosus, are also linked to higher prolactin levels in certain regions.
Sources: en.wikipedia.org
Solid peptide is best kept frozen at about minus 20 degrees Celsius in a sealed container with desiccant. It should be allowed to reach room temperature before opening to prevent condensation. Repeated warming and cooling of the same vial is discouraged.
Reversed-phase liquid chromatography establishes purity, while mass spectrometry confirms molecular mass. The two techniques are normally used together. Retention time alone is not sufficient evidence of identity.
Different counterions change the mass per unit of peptide and can shift chromatographic behavior. Two samples of equal stated purity may therefore not be directly comparable. Reports should specify the counterion whenever quantitative comparisons are made.
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.