reversed-phase HPLC is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Updated 2026-04-16. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
The compound was developed in the 1980s at the Institute of Molecular Genetics in Moscow, where it emerged from research on short ACTH fragments and their effects on the central nervous system. Russian pharmaceutical listings describe it as a nootropic and neuroprotective agent, most often formulated as nasal drops. It is not a marketed medicine in the United States or the European Union, and no pharmacopoeial monograph covers it. Consequently, most published clinical experience with the substance originates from a small number of research centres, mainly in Russia and neighbouring countries.
| Property | Value | Notes |
|---|---|---|
| Purity assay | RP-HPLC, UV 214 nm | Typical research grade 95 percent or higher |
| Mass confirmation | ESI-MS or MALDI-TOF | Compared with theoretical value |
| Main degradation route | Methionine oxidation | Sulfoxide formation in solution |
| Powder storage | -20 °C, desiccated | Amber vial, minimal headspace |
| Working solution | Sterile water or saline | Prepare fresh; avoid repeated thawing |
Dissolution is normally performed in water, phosphate-buffered saline, or normal saline, since the peptide is freely soluble in aqueous media and is rarely handled with strong organic solvents. Solution pH should be kept near neutral, because extreme acidity or alkalinity accelerates backbone hydrolysis and encourages oxidation of the methionine side chain. Once dissolved, the material is less stable than the dry powder and is commonly divided into single-use portions and frozen. Buffers containing primary amines, such as Tris, are often avoided because of possible side reactions.
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.
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.
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.
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.
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.
Headgear called a "scrum cap" in rugby, or simply "headgear" or ear guard in wrestling and other martial arts, that protects the ears is worn to help prevent this condition. A specialty ear splint can also be made to keep the ear compressed, so that the damaged ear is unable to fill thus preventing cauliflower ear. For some athletes, however, a cauliflower ear is considered a badge of courage or experience.
which reasonably match experimental data, the collisional integrals may be computed numerically or from correlations. In some cases, the collision integrals are regarded as fitting parameters, and are fitted directly to experimental data. This is a common approach in the development of reference equations for gas-phase viscosities. An example of such a procedure is the Sutherland approach for the single-component gas, discussed above. For gas mixtures consisting of simple molecules, Revised Enskog Theory has been shown to accurately represent both the density- and temperature dependence of the viscosity over a wide range of conditions.
Javits (1952), former ambassador and permanent U.S. representative to the Conference on Disarmament in Geneva 2001–2003; U.S. permanent representative to the Organisation for the Prohibition of Chemical Weapons 2003–2009 James D. Theberge (1952), former U.S. ambassador to Chile and Nicaragua G. Norman Anderson (1954), former U.S. ambassador to Sudan David J. Bardin (1954), deputy administrator of the Federal Energy Administration; commissioner of the New Jersey Department of Environmental Protection William Haddad (1954), political operative, lobbyist, and journalist, Peace Corps founding official, aide to the Kennedy family, and grandson-in-law of Franklin D. Roosevelt Richard E. Benedick (1955), president emeritus of the National Council for Science and the Environment, ambassador, and chief U.S. negotiator to the Montreal Protocol John L. Hirsch (1957), U.S. ambassador to Sierra Leone 1995–1998 Morton Halperin (1958), deputy assistant secretary of defense, director of policy planning for the U.S. State Department, and member of Richard Nixon's Enemies List Shelby Brewer (1959), assistant secretary of energy for nuclear energy 1981–1984 Benjamin Huberman (1959), acting director of the Office of Science and Technology Policy; acting science advisor to the president in 1981 Pat Mullins (1959), chairman of the Republican Party of Virginia Constantine Menges (1960), national security aide to Ronald Reagan James E.
The Academy of Clinical Laboratory Physicians and Scientists is a learned society for scientists in the fields of clinical pathology and laboratory medicine. It was founded on November 12, 1966, in Bethesda, Maryland by a group of fifty-one individuals, led by David Seligson, Jon Straumfjord, George Z. Williams, Ernest Cotlove, and Ellis Benson. The society's founding mission was to represent scientists in the fields of clinical pathology and laboratory medicine in both the United States and Canada. As of 2015, it had 295 active members, as well as an additional 127 associate members, 195 emeritus members, and 5 honorary members. Along with the American Society for Clinical Pathology, it co-sponsors the American Journal of Clinical Pathology.
==== Chronic non-cancer pain ==== Guidelines have suggested that the risks of opioids are likely greater than their benefits when used for most non-cancer chronic conditions including headaches, back pain, and fibromyalgia. Thus they should be used cautiously in chronic non-cancer pain. If used, the benefits and harm should be reassessed at least every three months. For treating chronic pain, opioids are an option after other less risky pain relievers have been considered, including paracetamol or nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen or naproxen. Some types of chronic pain, including the pain caused by fibromyalgia or migraine, are preferentially treated with non-opioid drugs. The efficacy of using opioids to lessen chronic neuropathic pain is uncertain. Opioids are contraindicated as a first-line treatment for headache because they impair alertness, bring risk of dependence, and increase the risk that episodic headaches will become chronic. Opioids can also cause heightened sensitivity to headache pain. When other treatments fail or are unavailable, opioids may be appropriate for treating headache if the patient can be monitored to prevent the development of chronic headache. Starting in the late 20th century, there was an increase in the use of opioids in the management of non-malignant chronic pain. This practice has led to a growing problem with addiction and misuse of opioids, the opioid epidemic.
Sources: en.wikipedia.org
Pulsed electric field (PEF) electroporation is a method for processing cells by means of brief pulses of a strong electric field. PEF holds potential as a type of low-temperature alternative pasteurization process for sterilizing food products. In PEF processing, a substance is placed between two electrodes, then the pulsed electric field is applied. The electric field enlarges the pores of the cell membranes, which kills the cells and releases their contents. PEF for food processing is a developing technology still being researched. There have been limited industrial applications of PEF processing for the pasteurization of fruit juices. To date, several PEF treated juices are available on the market in Europe. Furthermore, for several years a juice pasteurization application in the US has used PEF. For cell disintegration purposes especially potato processors show great interest in PEF technology as an efficient alternative for their preheaters. Potato applications are already operational in the US and Canada. There are also commercial PEF potato applications in various countries in Europe, as well as in Australia, India, and China.
A number of studies suggest that the inflated rates of depression and anxiety in transgender individuals may partially be because of systematic discrimination or a lack of support. Evidence suggests that these increased rates begin to normalize when transgender individuals are accepted as their identified gender and when they live within a supportive household. Many studies report extremely high rates of suicide within the transgender community. A United States study of 6,450 transgender individuals found that 41% of them had attempted suicide, as differing from the national average of 4.6%. The very same survey found that these rates were the most high for certain demographics, with transgender youth between the ages of 18 and 24 having the highest percent. Individuals in the survey who were multiracial, had lower levels of education, and those with a lower annual income were all more likely to have attempted. Specifically, transgender males as a group are the most likely to attempt suicide, more so than transgender females. Later surveys suggest that the rate of suicidal attempts for non-binary individuals is in between the two. Transgender adults who have "de-transitioned", meaning having gone back to living as their sex assigned at birth, are significantly more likely to attempt suicide than transgender adults who have never "de-transitioned". Several studies have shown the relation between minority stress and the heightened rate of depression and other mental illness among both transgender men and women.
=== Tourism === Areas where white sharks gather have been sites for ecotourism; operators offer guest viewing from boats or from underwater shark cages. Most operators use chum to attract the sharks to the vessels. Proponents argue that these tours provide public education, fund research, and increase the economic value of living sharks relative to fishing. A study in South Australia found that these encounters improved participants' knowledge and support for shark conservation. However, concerns persist regarding the impact of tourist interactions on shark behavior. At the Neptune Islands, researchers found that white sharks expended more energy during encounters with cage divers, but suggested population-level impacts are negligible if the frequency of encounters with any single shark is minimal. While intensive boat activity initially drove sharks away from the area, the population recovered following 2012 regulations that restricted the number of licensed operators and their days of operation. There is no strong evidence that chumming alters the feeding behavior of white sharks or conditions them to associate humans with food. The Mexican government banned white shark tourism at Guadalupe Island in January 2023. This decision followed reports of safety violations—such as swimming outside cages and improper chum handling—along with two incidents where sharks were harmed after being caught between the bars of the cages.
Most often, the diagnosis is made clinically. Dark field microscopy of samples taken from early lesions (particularly ulcerative lesions) may show the responsible bacteria; the spirochaetes are only 0.3 μm wide by 6–20 μm long, so light-field microscopy does not suffice. A microscopic examination of a biopsy of a yaw may show skin with clear epidermal hyperplasia (a type of skin thickening) and papillomatosis (a type of surface irregularity), often with focal spongiosis (an accumulation of fluid in a specific part of the epidermis). Immune system cells, neutrophils and plasma cells, accumulate in the skin, in densities that may cause microabscesses. Warthin–Starry or Levaditi silver stains selectively stain T. pallidum, and direct and indirect immunofluorescence and immunoperoxidase tests can detect polyclonal antibodies to T. pallidum's. Histology often shows some spatial features that distinguish yaws from syphilis (syphilis is more likely to be found in the dermis, not the epidermis, and shows more endothelial cell proliferation and vascular obliteration). Blood-serum (serological) tests are increasingly done at the point of care. They include a growing range of treponemal and nontreponemal assays. Treponemal tests are more specific, and are positive for anyone who has ever been infected with yaws; they include the Treponema pallidum particle agglutination assay. Nontreponemal assays can be used to indicate the progress of an infection and a cure, and positive results weaken and may become negative after recovery, especially after a case is treated early.
The role of some species of birds as pests has been well known, particularly in agriculture. Granivorous birds such as the queleas in Africa are among the most numerous birds in the world, and foraging flocks can cause devastation. Many insectivorous birds are also noted as beneficial in agriculture. Many early studies on the benefits or damages caused by birds in fields were made by analysis of stomach contents and observation of feeding behaviour. Modern studies aimed at managing birds in agriculture make use of a wide range of principles from ecology. Intensive aquaculture has brought humans into conflict with fish-eating birds such as cormorants. Large flocks of pigeons and starlings in cities are often considered as a nuisance, and techniques to reduce their populations or their impacts are constantly innovated. Birds are also of medical importance, and their role as carriers of human diseases such as Japanese encephalitis, West Nile virus, and influenza H5N1 have been widely recognized. Bird strikes and the damage they cause in aviation are of particularly great importance, due to the fatal consequences and the level of economic losses caused. The airline industry incurs worldwide damages of an estimated US$1.2 billion each year. Many species of birds have been driven to extinction by human activities. Being conspicuous elements of the ecosystem, they have been considered as indicators of ecological health. They have also helped in gathering support for habitat conservation.
Sources: en.wikipedia.org
These include agents that increase insulin release (sulfonylureas), agents that decrease absorption of sugar from the intestines (acarbose), agents that inhibit the enzyme dipeptidyl peptidase-4 (DPP-4) that inactivates incretins such as GLP-1 and GIP (sitagliptin), agents that make the body more sensitive to insulin (thiazolidinedione) and agents that increase the excretion of glucose in the urine (SGLT2 inhibitors). When insulin is used in type 2 diabetes, a long-acting formulation is usually added initially, while continuing oral medications. Some severe cases of type 2 diabetes may also be treated with insulin, which is increased gradually until glucose targets are reached.
Teleosts are economically important in different ways. They are captured for food around the world. A small number of species such as herring, cod, pollock, anchovy, tuna and mackerel provide people with millions of tons of food per year, while many other species are fished in smaller amounts. They provide a large proportion of the fish caught for sport. Commercial and recreational fishing together provide millions of people with employment. A small number of productive species including carp, salmon, tilapia and catfish are farmed commercially, producing millions of tons of protein-rich food per year. in 2016 the UN's Food and Agriculture Organization expected production to increase sharply so that by 2030, perhaps sixty-two percent of food fish would be farmed. Fish are consumed fresh, or may be preserved by traditional methods, which include combinations of drying, smoking, and salting, fermentation, and pickling in vinegar. Modern methods of preservation include freezing, freeze-drying, and heat processing (such as in the canning process). Frozen fish products include breaded or battered fillets, fish fingers and fishcakes. Fish meal is used as a food supplement for farmed fish and for livestock. Fish oils are made either from fish liver, especially rich in vitamins A and D, or from the bodies of oily fish such as sardine and herring, and used as food supplements and to treat vitamin deficiencies. Some smaller and more colourful species serve as aquarium specimens and pets. Sea wolves are used in the leather industry. Isinglass is made from thread fish and drum fish.
== Operation and features == Most freeze alarms combine a temperature sensor with either a local indicator or a remote communication module. A typical residential set-point is between 10–13 °C (50–55 °F), providing a margin above the freezing point of water. Early products such as the Honeywell “Winter Watchman” used a simple thermostat that closed a circuit to flash a lamp when indoor temperature dropped, alerting neighbours passing by. Contemporary units use solid-state sensors and microcontrollers, allowing adjustable thresholds, continuous logging, and multi-condition monitoring (e.g. power loss, humidity, water leaks, or smoke-alarm sound detection).
=== Anorexia and obesity === Ghrelin levels in the plasma of obese individuals are lower than those in leaner individuals, suggesting that ghrelin does not contribute to obesity, except in the cases of Prader–Willi syndrome-induced obesity, where high ghrelin levels are correlated with increased food intake. Those with anorexia nervosa have high plasma levels of ghrelin compared to both the constitutionally thin and normal-weight controls. In healthy individuals, levels of circulating ghrelin increase during the time of day from midnight to dawn. However, a study comparing obese and healthy men found that this nocturnal increase in ghrelin was absent in the obese population, suggesting alterations of circadian patterns in obese men. Ghrelin levels are high in people with cancer-induced cachexia. There is insufficient evidence to conclude either for or against use of ghrelin in managing cachexia associated with cancer.
=== Antifungal effect === Its antifungal effect is thought to derive from its ability to disrupt membrane transport by blocking the proton pump that energizes the transport mechanism. A study from 2011 showed that antifungal effects of zinc pyrithione work by copper toxicity mechanism that targets critical iron–sulphur proteins.
Sources: en.wikipedia.org
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.
The main chemical risks are methionine oxidation and backbone hydrolysis in solution. Moisture and repeated temperature cycling accelerate both processes. Dry powder held cold and desiccated is considerably more stable than any reconstituted preparation.
It holds a medicine registration in Russia, where it has been used clinically for decades. In most other countries it is treated as a research chemical. That split explains the uneven distribution of clinical literature.
It is described as a synthetic analogue of the ACTH(4–10) fragment, a short segment of adrenocorticotropic hormone. Its sequence differs from that fragment and includes two proline residues, which influence stability and behaviour in solution.