Everything below concerns enzymatic recycling. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2026-06-08. Numbers and descriptions here follow the published literature rather than marketing material.
Several techniques are used for quantification. Enzymatic recycling assays rely on glutathione reductase and a colorimetric or fluorescent readout, offering sensitivity for total glutathione. High-performance liquid chromatography can separate GSH from GSSG and other thiols, often with UV, fluorescence, or electrochemical detection. Mass spectrometry provides structural confirmation and can quantify low-abundance species when paired with separation. Each approach has trade-offs in specificity, throughput, and equipment requirements, so method selection depends on the research question and available instrumentation.
Stability depends on pH, temperature, oxygen exposure, and trace metals. Aqueous solutions of reduced glutathione are susceptible to oxidation, especially when neutral or alkaline and exposed to air. Transition metal ions can catalyze thiol oxidation, so chelators and inert atmospheres are sometimes used in research settings. Standards are typically stored cold and desiccated, with limited freeze-thaw cycles. Questions remain about how closely in vitro stability data reflect the behavior of glutathione within intact cells and tissues.
Glutathione is a tripeptide composed of glutamate, cysteine, and glycine. It contains an unusual gamma-glutamyl bond between glutamate and cysteine, which resists cleavage by many peptidases. The reduced form, GSH, carries a thiol group on cysteine and is the dominant intracellular form in most cells. Its structure allows it to participate in redox reactions and to serve as a sulfur donor. The oxidized form, GSSG, consists of two GSH molecules joined by a disulfide bond.
In cells, glutathione helps maintain the reducing environment of the cytosol and supports enzymes that counteract reactive oxygen species. It acts as a cofactor for glutathione peroxidases, which reduce hydrogen peroxide and lipid peroxides, and for glutathione S-transferases, which conjugate electrophiles. The ratio of GSH to GSSG is often used as an indicator of oxidative stress, although the ratio can vary by compartment and cell type. Glutathione also stores cysteine, an amino acid that can be limiting for protein synthesis and antioxidant defense.
| Property | Value | Notes |
|---|---|---|
| Reduced form | GSH | Main intracellular thiol |
| Oxidized form | GSSG | Disulfide dimer of two GSH molecules |
| Common separation method | Reversed-phase HPLC | Often with ion-pairing or derivatization |
| Typical detection | Fluorescence or mass spectrometry | UV detection is also used in some assays |
| Storage of standards | -20 °C or below, desiccated | Limit freeze-thaw and moisture exposure |
Enzymatic recycling assays provide a complementary approach for total glutathione. In these methods, glutathione reductase reduces oxidized glutathione while a thiol-reactive reagent, such as 5,5'-dithiobis(2-nitrobenzoic acid), produces a colored product. The reaction cycles between reduced and oxidized forms, amplifying the signal. Spectrophotometric or fluorometric detection can then estimate concentration. Distinguishing reduced glutathione from glutathione disulfide often requires separate aliquots, masking agents, or chromatographic separation, and the choice affects reported values.
Storage conditions strongly influence glutathione stability. The solid reduced form is commonly kept desiccated at or below minus twenty degrees Celsius, protected from light and moisture. Aqueous solutions are less stable because the thiol group reacts with dissolved oxygen, and oxidation accelerates at neutral or alkaline pH. Acidic solutions and oxygen-free handling can slow degradation, but repeated freeze-thaw cycles should be avoided. Researchers often verify concentration before use, because apparent losses can arise from oxidation or water uptake.
Measuring glutathione in biological samples requires attention to oxidation and matrix effects. High-performance liquid chromatography with ultraviolet or fluorescence detection can separate reduced and oxidized forms after derivatization. Liquid chromatography with tandem mass spectrometry offers higher specificity and can quantify glutathione alongside related thiols. Because glutathione can oxidize during sample handling, many protocols use rapid acidification with metaphosphoric acid or sulfosalicylic acid. Internal standards help correct for losses during extraction and analysis.
Glutathione supports several cellular processes beyond direct antioxidant action. It serves as a cofactor for glutathione peroxidase and glutathione S-transferase enzymes, which reduce peroxides and conjugate electrophiles, respectively. The molecule also acts as a reservoir of cysteine, an amino acid that can limit protein synthesis and redox signaling. In human nutrition, oral glutathione is sold as a supplement, but how much intact glutathione reaches tissues after ingestion remains an active research question. Clinical claims about supplementation are not uniformly supported by controlled trials.
Glutathione is a small tripeptide built from glutamic acid, cysteine, and glycine. Its peptide bond between glutamate and cysteine involves the gamma-carboxyl group rather than the usual alpha-carboxyl group. This structure gives the molecule a reactive thiol on the cysteine residue. The reduced form, often abbreviated GSH, is the predominant intracellular species in many cell types. Because the thiol can donate electrons, glutathione participates in redox chemistry and in the conjugation of reactive molecules.
Cells synthesize glutathione through two ATP-dependent steps: glutamate-cysteine ligase joins glutamate and cysteine, and glutathione synthetase adds glycine to form the complete tripeptide. Breakdown occurs through gamma-glutamyl transpeptidase and subsequent peptidase reactions, forming the gamma-glutamyl cycle. Within cells, glutathione also forms a disulfide-linked dimer called GSSG when two GSH molecules react. The balance between GSH and GSSG is widely used as an indicator of oxidative conditions, although the ratio can vary by compartment and tissue.
For solid glutathione reagents, storage at low temperature and protection from moisture and light are typical precautions. Aqueous solutions can oxidize over time, and pH affects stability; alkaline conditions generally promote thiol oxidation. Some protocols prepare fresh solutions, while others use antioxidants or chelators to limit metal-catalyzed oxidation. Purity and counterion content can vary among commercial preparations, affecting concentration calculations. Certificates of analysis and validated assays help verify identity and purity.
Measuring glutathione in biological samples requires attention to oxidation, because GSH can convert to GSSG after sample collection. Blood and plasma samples are often treated with acid or alkylating agents to preserve the reduced form. Without stabilization, apparent GSH concentrations can fall while GSSG rises. Differences in sample type, handling delay, and deproteinization method can produce results that are not comparable across studies. Reporting preanalytical details is therefore important for interpreting findings.
Instead, the ionic current from an action potential at one node of Ranvier provokes another action potential at the next node; this apparent "hopping" of the action potential from node to node is known as saltatory conduction. Although the mechanism of saltatory conduction was suggested in 1925 by Ralph Lillie, the first experimental evidence for saltatory conduction came from Ichiji Tasaki and Taiji Takeuchi and from Andrew Huxley and Robert Stämpfli. By contrast, in unmyelinated axons, the action potential provokes another in the membrane immediately adjacent, and moves continuously down the axon like a wave.
There were several terrorist attacks in Xinjiang in 2013 and 2014; an attack in Ürümqi in April 2014 occurred just after the conclusion of a visit by Xi to Xinjiang. Following these attacks, CCP leaders held a secret meeting to find a solution, leading to Xi to launch the Strike Hard Campaign Against Violent Terrorism in 2014, which involved mass detention, and surveillance of ethnic Uyghurs there. The campaign included the detainment of 1.8 million people in internment camps, mostly Uyghurs but also including other ethnic and religious minorities, by 2020, and a birth suppression campaign that led to a large drop in the Uyghur birth rate by 2019. Human rights groups and former inmates have said Uyghurs and other minorities have been forcibly assimilated into China's majority ethnic Han society in the camps. This program has been called a genocide by some observers, while a report by the UN Human Rights Office said they may amount to crimes against humanity.
The epithelial cells are connected by tight junctions, forming the major electrical resistive barrier, and thus establishing an electrical gradient across the epithelium – the transepithelial potential (TEP). Breaking the epithelial barrier, as occurs in any wounds, creates a hole that breaches the high electrical resistance established by the tight junctions in the epithelial sheet, short-circuiting the epithelium locally. The TEP therefore drops to zero at the wound. However, normal ion transport continues in unwounded epithelial cells beyond the wound edge (typically <1 mm away), driving positive charge flow out of the wound and establishing a steady, laterally-oriented electric field (EF) with the cathode at the wound. Skin also generates a TEP, and when a skin wound is made, similar wound electric currents and fields arise, until the epithelial barrier function recovers to terminate the short-circuit at the wound. When wound electric fields are manipulated with pharmacological agents that either stimulate or inhibit transport of ions, the wound electric fields also increase or decrease, respectively. Wound healing can be speed up or slowed down accordingly in cornea wounds. How do electric fields affect wound healing? To heal wounds, cells surrounding the wound must migrate and grow directionally into the wound to cover the defect and restore the barrier. Cells important to heal wounds respond remarkably well to applied electric fields of the same strength that are measured at wounds.
Sources: en.wikipedia.org
=== Post–surgical recovery === Convalescence The rhinoplasty patient returns home after surgery, to rest, and allow the nasal cartilage and bone tissues to heal the effects of having been forcefully cut. Assisted with prescribed medications—antibiotics, analgesics, steroids—to alleviate pain and aid wound healing, the patient convalesces for about 1-week, and can go outdoors. Post-operatively, external sutures are removed at 4–5 days; the external cast is removed at 1-week; the stents are removed within 4–14 days; and the "panda eyes" periorbital bruising heal at 2-weeks. If an alar base reduction is performed conjunctively within the Rhinoplasty, these sutures need to be removed within 7–10 days post operatively. Throughout the first year post-operative, in the course of the rhinoplastic wounds healing, the tissues will shift moderately as they settle into being a new nose. Furthermore, as rhinoplasty climbs the ladder of surgical procedures performed to achieve an aspired appearance, especially amongst women, the relationship between body image and mental state must be examined in order to destigmatize motives behind the surgical intervention.
The two substrates of this enzyme are sn-glycerol 3-phosphate and oxidised nicotinamide adenine dinucleotide (NAD+). Its products are dihydroxyacetone phosphate, the reduced cofactor NADH, and a proton. This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-OH group of donor with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is sn-glycerol-3-phosphate:NAD+ 2-oxidoreductase. Other names in common use include alpha-glycerol phosphate dehydrogenase (NAD+), alpha-glycerophosphate dehydrogenase (NAD+), glycerol 1-phosphate dehydrogenase, glycerol phosphate dehydrogenase (NAD+), glycerophosphate dehydrogenase (NAD+), hydroglycerophosphate dehydrogenase, L-alpha-glycerol phosphate dehydrogenase, L-alpha-glycerophosphate dehydrogenase, L-glycerol phosphate dehydrogenase, L-glycerophosphate dehydrogenase, NAD+-alpha-glycerophosphate dehydrogenase, NAD+-dependent glycerol phosphate dehydrogenase, NAD+-dependent glycerol-3-phosphate dehydrogenase, NAD+-L-glycerol-3-phosphate dehydrogenase, NAD+-linked glycerol 3-phosphate dehydrogenase, NADH-dihydroxyacetone phosphate reductase, and glycerol-3-phosphate dehydrogenase (NAD+). This enzyme participates in glycerophospholipid metabolism.
Vaccine production and storage has great potential in transgenic plants. Vaccines are expensive to produce, transport, and administer, so having a system that could produce them locally would allow greater access to poorer and developing areas. As well as purifying vaccines expressed in plants it is also possible to produce edible vaccines in plants. Edible vaccines stimulate the immune system when ingested to protect against certain diseases. Being stored in plants reduces the long-term cost as they can be disseminated without the need for cold storage, don't need to be purified, and have long term stability. Also being housed within plant cells provides some protection from the gut acids upon digestion. However the cost of developing, regulating, and containing transgenic plants is high, leading to most current plant-based vaccine development being applied to veterinary medicine, where the controls are not as strict. Genetically modified crops have been proposed as one of the ways to reduce farming-related CO2 emissions due to higher yield, reduced use of pesticides, reduced use of tractor fuel and no tillage. According to a 2021 study, in EU alone widespread adoption of GE crops would reduce greenhouse gas emissions by 33 million tons of CO2 equivalent or 7.5% of total farming-related emissions.
Sandoz also marketed and sold pure psilocybin under the name Indocybin to clinicians and researchers worldwide. There were no reports of serious complications when psilocybin was used in this way. In the early 1960s, Harvard University became a testing ground for psilocybin through the efforts of Timothy Leary and his associates Ralph Metzner and Richard Alpert (who later changed his name to Ram Dass). Leary obtained synthesized psilocybin from Hofmann through Sandoz Pharmaceuticals. Some studies, such as the Concord Prison Experiment, suggested promising results using psilocybin in clinical psychiatry. But according to a 2008 review of safety guidelines in human hallucinogenic research, Leary's and Alpert's well-publicized termination from Harvard and later advocacy of hallucinogen use "further undermined an objective scientific approach to studying these compounds". In response to concerns about the increase in unauthorized use of psychedelic drugs by the general public, psilocybin and other hallucinogenic drugs were unfavorably covered in the press and faced increasingly restrictive laws. In the U.S., laws passed in 1966 that prohibited the production, trade, or ingestion of hallucinogenic drugs; Sandoz stopped producing LSD and psilocybin the same year. In 1970, Congress passed "The Federal Comprehensive Drug Abuse Prevention and Control Act" that made LSD, peyote, psilocybin, and other hallucinogens illegal to use for any purpose, including scientific research.
Sources: en.wikipedia.org
The first ionisation energy of an atom is the energy required to remove an electron from it. This varies with the atomic radius: ionisation energy increases left to right and down to up, because electrons that are closer to the nucleus are held more tightly and are more difficult to remove. Ionisation energy thus is minimized at the first element of each period – hydrogen and the alkali metals – and then generally rises until it reaches the noble gas at the right edge of the period. There are some exceptions to this trend, such as oxygen, where the electron being removed is paired and thus interelectronic repulsion makes it easier to remove than expected. In the transition series, the outer electrons are preferentially lost even though the inner orbitals are filling. For example, in the 3d series, the 4s electrons are lost first even though the 3d orbitals are being filled. The shielding effect of adding an extra 3d electron approximately compensates the rise in nuclear charge, and therefore the ionisation energies stay mostly constant, though there is a small increase especially at the end of each transition series. As metal atoms tend to lose electrons in chemical reactions, ionisation energy is generally correlated with chemical reactivity, although there are other factors involved as well.
Carbon dioxide can be used to extinguish flames by flooding the environment around the flame with the gas. It does not itself react to extinguish the flame, but starves the flame of oxygen by displacing it. Some fire extinguishers, especially those designed for electrical fires, contain liquid carbon dioxide under pressure. Carbon dioxide extinguishers work well on small flammable liquid and electrical fires, but not on ordinary combustible fires, because they do not cool the burning substances significantly, and when the carbon dioxide disperses, they can catch fire upon exposure to atmospheric oxygen. They are mainly used in server rooms. Carbon dioxide has also been widely used as an extinguishing agent in fixed fire-protection systems for local application of specific hazards and total flooding of a protected space. International Maritime Organization standards recognize carbon dioxide systems for fire protection of ship holds and engine rooms. Carbon dioxide-based fire-protection systems have been linked to several deaths, because it can cause suffocation in sufficiently high concentrations. A review of CO2 systems identified 51 incidents between 1975 and the date of the report (2000), causing 72 deaths and 145 injuries.
=== Medication === If monitoring reveals failing control of glucose levels with these measures, or if there is evidence of complications like excessive fetal growth, treatment with insulin might be necessary. This is most commonly fast-acting insulin given just before eating to blunt glucose rises after meals. Care needs to be taken to avoid low blood sugar levels due to excessive insulin. Insulin therapy can be normal or very tight; more injections can result in better control but require more effort, and there is no consensus that it has large benefits. A 2016 Cochrane review (updated in 2023) concluded that quality evidence is not yet available to determine the best blood sugar range for improving health for pregnant women with GDM and their babies. There is some evidence that certain medications by mouth might be safe in pregnancy, or at least, are less dangerous to the developing fetus than poorly controlled diabetes. When comparing which diabetes tablets (medication by mouth) work best and are safest, there is not enough quality research to support one medication over another. The medication metformin is better than glyburide. If blood glucose cannot be adequately controlled with a single agent, the combination of metformin and insulin may be better than insulin alone. Another review found good short term safety for both the mother and baby with metformin but unclear long term safety. People may prefer metformin by mouth to insulin injections. Treatment of polycystic ovarian syndrome with metformin during pregnancy has been noted to decrease GDM levels.
Following a Round 22 61-point demolition at the hands of lower-placed Hawthorn, Thompson's job was under immense pressure. After a very public review of the club, it was decided that Thompson should keep his job as senior coach. After a shaky start to the 2007 season that led many supporters to believe that nothing had changed from the 2006 season, Thompson led Geelong to a massive 15 match winning streak (the biggest in a single season in club history) and a 106-point win against the Kangaroos in the Qualifying Final which is the 5th biggest finals winning margin in AFL/VFL history. The 2007 season then culminated in one of the biggest, if not the best highlight of Thompson's career, in both a coaching and footballer's role. Thompson coached Geelong to win the AFL premiership in the 2007 AFL Grand Final by more than 100 points, which was the highest winning margin in Grand Final history, against Port Adelaide Football Club at the MCG on 29 September. It was the club's first premiership since 1963, the year of Thompson's birth. After the Essendon Football Club decided not to give Thompson's former mentor, Kevin Sheedy, a renewal of contract, there was speculation that Mark Thompson would take up the senior coaching role at Essendon for the 2008 season. However, with trade week quickly approaching, the club instead appointed Matthew Knights to the position. After Geelong's record-breaking win in the grand final, Geelong under Thompson were red hot favourite to repeat their 2007 success in the 2008 season and their form during the year did nothing to change that.
=== Mechanism of action === Alitretinoin is believed to be the endogenous ligand (a substance that naturally occurs in the body that activates this receptor) for retinoid X receptor, but it also activates the retinoic acid receptor. More specifically, alitretinoin is believed to act on intracellular nuclear receptors of the RAR and RXR subtypes. The activated receptors function as transcription factors, which subsequently influence cell proliferation and cell differentiation. Alitretinoin acts on both keratinocytes and dendritic cells. In keratinocytes, it reduces cytokine expression, while in dendritic cells it inhibits the upregulation of the maturation marker CD83 and the co-stimulatory molecules CD80 and CD86. Consequently, these dendritic cells exhibit diminished T cell activation capacity.
Sources: en.wikipedia.org
Common methods include enzymatic recycling assays, liquid chromatography, and mass spectrometry. Many protocols separate reduced glutathione from its oxidized disulfide form before detection.
The ratio compares reduced glutathione with its oxidized dimer. It is used as an indicator of redox status, although the value depends strongly on sample handling and analytical method.
Glutathione can oxidize quickly after a sample is collected. Acidification, cooling, and chelators are often used to reduce artifactual changes before analysis.
GSH is the reduced form with a free thiol group, while GSSG is the oxidized disulfide-linked dimer. Most assays distinguish the two because their balance reflects redox conditions. The names are not interchangeable.