This is a working overview of redox ratio, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2026-08-01 and is reviewed periodically as new material appears.
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.
Measuring glutathione requires attention to oxidation during sample handling, because GSH in biological samples can convert to GSSG or form mixed disulfides with proteins after collection. Acidic extraction, rapid cooling, and chelating agents are commonly used to limit such changes. Analytical methods usually distinguish free reduced glutathione, total glutathione, and protein-bound forms. Because these forms have different stability and reactivity, reported values depend heavily on the preparation protocol. No single preparation is universally suitable for every biological matrix or analytical goal.
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.
Interpreting glutathione measurements requires attention to pre-analytical variables. The GSSG concentration in a sample can rise artificially during storage or processing, making the GSH/GSSG ratio unreliable if not controlled. Reference ranges vary by specimen type, assay, and population, so comparisons across studies are difficult. Plasma glutathione is low and sensitive to hemolysis, while whole blood reflects primarily erythrocyte content. Many studies measure total glutathione rather than the reduced and oxidized forms separately, which limits conclusions about redox status.
Accurate measurement of glutathione begins with careful sample handling. Because GSH oxidizes rapidly to GSSG, samples must be processed quickly or frozen immediately. Acid precipitation with metaphosphoric acid or perchloric acid is common; it lowers pH, precipitates proteins, and helps preserve the reduced form. Chelating agents such as EDTA can limit metal-catalyzed oxidation. For whole blood, hemolysis releases glutathione from erythrocytes, so plasma and serum values differ substantially from whole blood values.
| 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 |
Storage recommendations for glutathione reagents usually specify a cool, dry, dark environment because the thiol oxidizes in air and light. Solid material is often kept desiccated at low temperature, while solutions are prepared fresh or stored frozen in aliquots. Repeated freeze-thaw cycles can accelerate degradation, and metal ions can catalyze oxidation. Quality control may include purity assays, water content, and identity confirmation. Stability limits are method-specific, so a stated shelf life applies only to defined conditions and packaging.
Laboratory measurement of glutathione requires attention to oxidation before analysis. Blood, tissue, or cell samples can lose reduced glutathione as it converts to GSSG or forms mixed disulfides with proteins. Acid extraction, rapid freezing, and thiol-blocking reagents are common strategies to preserve the original distribution. Reported concentrations therefore depend on collection protocol, extraction method, and the time between sampling and analysis. Comparisons across studies are most reliable when these pre-analytical variables are described.
Common analytical approaches include enzymatic recycling assays, high-performance liquid chromatography, and mass spectrometry. The enzymatic recycling assay uses glutathione reductase and a colorimetric or fluorometric reagent to amplify signal, which gives good sensitivity for total glutathione. Chromatographic methods can separate GSH from GSSG and related thiols, while mass spectrometry offers structural confirmation and multiplexing. Each approach has different requirements for calibration, internal standards, and validation. No single method captures every form of glutathione in every matrix.
In its reduced form, glutathione carries a sulfhydryl group that can donate electrons. This property lets it act as a major cellular antioxidant and redox buffer. Glutathione peroxidase uses it to reduce hydrogen peroxide and lipid peroxides, while glutathione reductase regenerates the reduced form using NADPH. The ratio of reduced glutathione to glutathione disulfide is widely used as an indicator of oxidative stress, though the ratio changes with compartment, cell type, and sample handling. Oxidized glutathione can also form mixed disulfides with proteins, affecting their activity.
Glutathione supports detoxification by conjugating reactive electrophiles through glutathione S-transferases. The resulting conjugates are processed and exported, often after further metabolism. It also stores cysteine, transports amino acids across membranes through the gamma-glutamyl cycle, and assists in the maturation of iron-sulfur clusters and some prostaglandins. In plants, animals, and many microbes, the molecule appears in similar roles, but concentrations vary enormously between tissues. Liver, kidney, and red blood cells tend to contain high amounts, while blood plasma contains much less.
Glutathione is a small tripeptide built from glutamate, cysteine, and glycine. The peptide bond between glutamate and cysteine uses the gamma-carboxyl group, a linkage that resists ordinary peptidases. Cells make it in two ATP-dependent steps: gamma-glutamylcysteine synthetase joins glutamate and cysteine, then glutathione synthetase adds glycine. The pathway is feedback-inhibited by glutathione itself, so intracellular levels tend to stay within a narrow range. Because cysteine is often limiting, sulfur amino acid supply influences how much glutathione a cell can produce.
Animal hearts are widely consumed as a type of offal. As they are almost entirely muscle, they are high in protein. They are often included in dishes with other internal organs, for example in the pan-Ottoman kokoretsi. Chicken hearts are considered to be giblets, and are often grilled on skewers; examples of this are Japanese hāto yakitori, Brazilian churrasco de coração, and Indonesian chicken heart satay. They can also be pan-fried, as in Jerusalem mixed grill. In Egyptian cuisine, they can be used, finely chopped, as part of stuffing for chicken. Many recipes combined them with other giblets, such as the Mexican pollo en menudencias and the Russian ragu iz kurinyikh potrokhov. As heart is a hard-working muscle, it makes for "firm and rather dry" meat, so is generally slow-cooked. Another way of dealing with toughness is to julienne the meat, as in Chinese stir-fried heart. Beef heart is valued for its high meat quality and low price, being commonly disregarded in conventional meat pricing. It can be cut into steaks, comparable in quality to the more expensive cuts of meat from the same animal, though it is distinguished by a lack of a discernible grain. It was historically eaten in the United States as a cost-saving measure, but is today also eaten as an independently desirable ingredient. Beef heart may be grilled or braised. In the Peruvian anticuchos de corazón, barbecued beef hearts are grilled after being tenderized through long marination in a spice and vinegar mixture. An Australian recipe for "mock goose" is actually braised stuffed beef heart.
=== Classical PKU === Classical PKU, and its less severe forms "mild PKU" and "mild hyperphenylalaninemia" are caused by a mutated gene for the enzyme phenylalanine hydroxylase (PAH), which converts phenylalanine to tyrosine, which is a conditionally essential amino acid for PKU patients, because without the enzyme PAH, tyrosine cannot be produced in the body through oxidation of Phe. PAH deficiency causes a spectrum of disorders, including classic phenylketonuria (PKU) and mild hyperphenylalaninemia (also known as "hyperPhe" or "mild HPA"), a less severe accumulation of phenylalanine. Compared to classic PKU patients, patients with "hyperPhe" have greater PAH enzyme activity and are able to tolerate larger amounts of phenylalanine in their diets. Without dietary intervention, mild HPA patients have blood Phe levels higher than those people with normal PAH activity. Currently, no international consensus exists on the definition of mild HPA, but it is most frequently diagnosed at blood Phe levels between 2 and 6 mg/dL. Phenylalanine is a large, neutral (hydrophobic) amino acid (LNAA). LNAAs compete for transport across the blood–brain barrier (BBB) via the large neutral amino acid transporter (LNAAT). If phenylalanine is in excess in the blood, it saturates the transporter. Excessive phenylalanine levels tend to decrease the levels of other LNAAs in the brain. As these amino acids are necessary for protein and neurotransmitter synthesis, Phe buildup disrupts the development of the brain, causing intellectual disability.
and Israeli efforts to supply the Contras with arms, the U.S. ignored Noriega's use of weapons-shipment networks to smuggle drugs into the U.S. Noriega was reported to have played a role in the Iran–Contra affair in the mid-1980s. There are varying reports about how much Noriega was paid by United States sources. In early 1990, Noriega biographer Frederick Kempe reported that the United States gave Noriega or his intelligence services annual payments in the range of $110,000 in 1976 increasing to $185,000 to $200,000 when he came to power during the Reagan administration. Dinges said that he could find no one willing to confirm persistent reports that he received a $200,000 per year stipend from the CIA. Prior to and during Noriega's trial, Noriega's lead attorney Frank A. Rubino claimed that Noriega had received $11 million in payments from the CIA. In January 1991, federal prosecutors filed a financial report indicating that Noriega had received a total of $322,000 from the United States Army and the CIA over a 31-year period from 1955 to 1986. They stated that the release of information was to rebut allegations from defense attorneys that Noriega had been paid "millions of dollars" from the CIA. These payments included a total of $76,039 as "gifts and incentives" from the CIA. Despite Noriega's alliance with the U.S., he also maintained close relationships with bitter enemies of the U.S., including Cuba, Libya, and Nicaragua.
=== Polished === Mirror polished stainless-steel belts to produce several types of thin film and ceramic sheets. The belts are available in thickness from 0.60 to 2.00 mm (0.02362 to 0.0787 in.) with thickness variation less than or equal to 80 μm. Polished steel belts are produced endlessly or as open-length belts.
Energy column The column labeled "energy" denotes the energy equivalent of (the mass of a neutron minus the mass per nucleon), that is of the mass defect with respect to the neutron, in MeV. Use of the neutron as reference guarantees all nuclides will have a positive value. Mathematically: mn − mnuclide / A. Note that this means that a higher "energy" value actually means that the nuclide has a lower energy. Inversely the mass is A (mn − E / k) where E is the energy, mn is 1.0086649159 and k = 931.4941037 MeV (energy equivalent of the dalton). Omitted if there is no experimental mass determination within 0.0001.
Sources: en.wikipedia.org
== Overview == Thyrotropic cells (also called thyrotropes, or thyrotrophs) are endocrine cells in the anterior pituitary which produce thyroid-stimulating hormone (TSH) in response to thyrotropin-releasing hormone (TRH) from the hypothalamus. Thyroid-stimulating hormone, or thyrotropin, triggers the release of thyroxine (T4) and triiodothyronine (T3) from the thyroid gland. Thyrotropes comprise around 5% of the anterior pituitary lobe cells.
However, as the stadtholders were officially appointed by, and served as first civil servants and generals for, the semi-independent provinces of the Dutch Republic, they cannot technically be viewed as monarchs, although they maintained a grand court and effectively behaved like monarchs in daily political practice. William the Silent had been stadtholder of four provinces. From his son Maurice onwards, that number rose to five. Meanwhile, their cousins of the House of Nassau-Dietz were appointed to the remaining two, Friesland and Groningen. In 1702, when the childless king-stadtholder William III died (who was also King of England), his title of Prince of Orange and his claims passed to this Frisian cousin line, making them the sole remaining branch of the House of Orange-Nassau. This succession maintained a cognatic line to William the Silent through his granddaughter Albertine Agnes of Nassau, who had married in 1652 into the Frisian cousin line. Following the French invasion in 1747, William IV, who emerged from this cousin line, was not only appointed stadtholder of all seven provinces, but the office was also formally made hereditary, although it had already largely been so in practice. His son, stadtholder William V, was forced into exile in England during the French Revolution and the following invasion of 1795. The French paradoxically introduced the formal concept of monarchy through Napoleon's brother, Louis Bonaparte, who ruled as king over the Netherlands.
=== Brain growth === Neuroanatomical studies and the association between autism and teratogens strongly suggest that autism affects brain development soon after conception. This anomaly appears to start a cascade of pathological events in the brain that are significantly influenced by environmental factors. Just after birth, the brains of children with autism tend to grow faster than usual, followed by normal or relatively slower growth in childhood. It is unknown whether early brain overgrowth occurs in all children with autism. It appears to be most prominent in the frontal and temporal lobes, which are associated with higher cognitive specializations such as social cognition, and language development. Hypotheses for the cellular and molecular bases of pathological early overgrowth include an excess of neurons that causes local overconnectivity in key brain regions, and disturbed neuronal migration during early gestation.
=== Geometry and hydrogen bonding === The amino acids in an α-helix are arranged in a right-handed helical structure where each amino acid residue corresponds to a 100° turn in the helix (i.e., the helix has 3.6 residues per turn), and a translation of 1.5 Å (0.15 nm) along the helical axis. Dunitz describes how Pauling's first article on the theme in fact shows a left-handed helix, the enantiomer of the true structure. Short pieces of left-handed helix sometimes occur with a large content of achiral glycine amino acids, but are unfavorable for the other normal, biological L-amino acids. The pitch of the alpha-helix (the vertical distance between consecutive turns of the helix) is 5.4 Å (0.54 nm), which is the product of 1.5 and 3.6. The most important thing is that the N-H group of one amino acid forms a hydrogen bond with the C=O group of the amino acid four residues earlier; this repeated i + 4 → i hydrogen bonding is the most prominent characteristic of an α-helix. Official international nomenclature specifies two ways of defining α-helices, rule 6.2 in terms of repeating φ, ψ torsion angles (see below) and rule 6.3 in terms of the combined pattern of pitch and hydrogen bonding. The α-helices can be identified in protein structure using several computational methods, such as DSSP (Define Secondary Structure of Protein).
That's exactly what I didn't want to happen." One of Staley's last shows with Alice in Chains was the MTV Unplugged performance in New York on April 10, 1996. The recording of Unplugged came after a long period of inactivity for the band; it was their first concert in two-and-a-half years. Staley made his last performance on July 3, 1996, in Kansas City, Missouri, while Alice in Chains was touring with Kiss.
Sources: en.wikipedia.org
== Traffic congestion == TomTom, the Dutch manufacturer of land navigation products, ranked Bangkok as the second-most traffic-clogged city of 189 cities studied worldwide. Mexico City topped the rankings. Other ASEAN cities listed were Jakarta, third, and Singapore at 55. The INRIX 2016 Global Traffic Scorecard ranked Thailand as the most congested nation of 38 studied for "average peak hours spent in congestion". Thais spent an average of 61 hours in 2016 stuck in traffic. Bangkok was ranked 11 of 100 cities for "peak hours spent in congestion", 64 hours. Based on 2015 data, Dutch navigation and digital mapping company, TomTom NV, ranked Bangkok number two in a listing of the 174 most traffic congested cities worldwide (1=most congested; 174=least congested). Mexico City ranked number one. No other ASEAN cities made the list.
==== Rocker Deformity ==== When operating on the upper vault of the nose, osteotomies may be performed to mobilize the nasal bones. These osteotomies should ideally have their superior limit at the nasofrontal suture, which is approximated by the medial canthus. If the osteotomy is carried too far superiorly into the frontal bone, a Rocker deformity may result, wherein the upper portion of the mobile bone flares outwards (or "rocks") when the inferior portion is medialized. Correction of a Rocker deformity would involve a transverse percutaneous osteotomy.
NAD-dependent deacetylase sirtuin 2 is an enzyme that in humans is encoded by the SIRT2 gene. SIRT2 is an NAD+ (nicotinamide adenine dinucleotide)-dependent deacetylase. Studies of this protein have often been divergent, highlighting the dependence of pleiotropic effects of SIRT2 on cellular context. The natural polyphenol resveratrol is known to exert opposite actions on neural cells according to their normal or cancerous status. Similar to other sirtuin family members, SIRT2 displays a ubiquitous distribution. SIRT2 is expressed in a wide range of tissues and organs and has been detected particularly in metabolically relevant tissues, including the brain, muscle, liver, testes, pancreas, kidney, and adipose tissue of mice. Of note, SIRT2 expression is much higher in the brain than all other organs studied, particularly in the cortex, striatum, hippocampus, and spinal cord.
===== Corynebacterium ===== Non-pathogenic species of the gram-positive Corynebacterium are used for the commercial production of various amino acids. The C. glutamicum species is widely used for producing glutamate and lysine, components of human food, animal feed and pharmaceutical products. Expression of functionally active human epidermal growth factor has been done in C. glutamicum, thus demonstrating a potential for industrial-scale production of human proteins. Expressed proteins can be targeted for secretion through either the general, secretory pathway (Sec) or the twin-arginine translocation pathway (Tat). Unlike gram-negative bacteria, the gram-positive Corynebacterium lack lipopolysaccharides that function as antigenic endotoxins in humans.
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.
Glutathione oxidizes quickly when cells are disrupted or when samples sit at room temperature. Rapid processing or immediate freezing minimizes the conversion of GSH to GSSG. This step helps ensure that the measured ratio reflects the original biological state.