A practical reference on LC-MS/MS: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2026-03-18. Anything still debated is marked as such rather than presented as settled.
In cells, glutathione exists mainly in a reduced form called GSH. When two GSH molecules react, they form oxidized glutathione, or GSSG, which contains a disulfide bond. The ratio of GSH to GSSG is often used as an indicator of oxidative stress. Enzymes such as glutathione peroxidase and glutathione reductase help cycle the molecule between these two states. This cycling supports antioxidant defense, detoxification of reactive molecules, and regulation of certain signaling pathways.
Glutathione is present in most tissues, with especially high concentrations in the liver. It also serves as a cofactor for some enzymes and helps transport amino acids across cell membranes. In plants and microorganisms, glutathione contributes to stress responses and metal handling. The molecule is synthesized in two ATP-dependent steps, first producing gamma-glutamylcysteine and then adding glycine. Because cysteine availability often limits synthesis, dietary and metabolic factors can influence glutathione levels. Research continues to examine how these levels relate to health and disease.
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.
Several analytical methods can quantify glutathione, including high-performance liquid chromatography (HPLC) with UV or fluorescence detection for separating GSH and GSSG. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) offers higher specificity and sensitivity, often detecting nanomolar concentrations. The enzymatic recycling assay, often called the Tietze method, measures total glutathione by coupling reduction of GSSG to a colorimetric or fluorometric readout. Capillary electrophoresis and electrochemical detection are also used in specialized laboratories. Each method has distinct advantages and limitations regarding throughput, cost, and susceptibility to interference.
| Property | Value | Notes |
|---|---|---|
| Common name | Glutathione | Tripeptide of glutamate, cysteine, and glycine |
| Reduced form | GSH | Dominant intracellular thiol |
| Oxidized form | GSSG | Disulfide-linked dimer |
| Molar mass | 307.32 g/mol | For reduced glutathione |
| Functional motif | Gamma-glutamyl-cysteinyl-glycine | Gamma linkage resists many peptidases |
Synthesis occurs in two ATP-dependent steps: glutamate-cysteine ligase joins glutamate and cysteine to form gamma-glutamylcysteine, and glutathione synthetase adds glycine to complete the tripeptide. The pathway is feedback-inhibited by GSH and limited by cysteine availability, so cysteine supply often constrains production. Once formed, GSH participates in redox buffering, xenobiotic conjugation, and protein glutathionylation. Glutathione peroxidase uses GSH to reduce hydrogen peroxide and lipid peroxides, yielding GSSG, while glutathione reductase regenerates GSH using NADPH. Glutathione S-transferases conjugate electrophiles to GSH, supporting detoxification and excretion.
Because GSH is central to redox balance, its status is studied in aging, liver disease, neurodegenerative conditions, and metabolic disorders. Observational studies often report lower GSH or higher GSSG in affected tissues, but such associations do not establish that raising glutathione changes disease outcomes. Oral glutathione is digested into amino acids, and whether intact absorption occurs remains debated; precursors such as N-acetylcysteine and cysteine donors are also investigated. Regulatory agencies generally treat glutathione as a dietary supplement, not an approved drug, and clinical claims require evidence from controlled trials.
Functionally, glutathione supports redox balance by donating electrons and becoming oxidized. It also serves as a cofactor for enzymes such as glutathione peroxidases and glutathione S-transferases. These enzymes participate in peroxide reduction and in conjugation reactions that help process reactive molecules. Separate from antioxidant roles, glutathione can modify protein cysteines through S-glutathionylation, influencing enzyme activity and signaling. Research continues to examine how these chemical roles translate into whole-organism effects.
Glutathione is a tripeptide composed of glutamate, cysteine, and glycine. Its glutamate-cysteine linkage uses the gamma-carboxyl group of glutamate, a feature that resists standard peptidases. The cysteine residue provides a thiol group, which gives the molecule its reducing character. In cells, glutathione is often the most abundant small-molecule thiol, with concentrations varying widely by tissue and compartment. It exists mainly in a reduced form called GSH, while oxidation produces a disulfide-linked dimer called GSSG.
Irradiation of food is the exposure of food to ionizing radiation. Multiple types of ionizing radiation can be used, including beta particles (high-energy electrons) and gamma rays (emitted from radioactive sources such as cobalt-60 or cesium-137). Irradiation can kill bacteria, molds, and insect pests, reduce the ripening and spoiling of fruits, and at higher doses induce sterility. The technology may be compared to pasteurization; it is sometimes called "cold pasteurization", as the product is not heated. Irradiation may allow lower-quality or contaminated foods to be rendered marketable. National and international expert bodies have declared food irradiation as "wholesome"; organizations of the United Nations, such as the World Health Organization and Food and Agriculture Organization, endorse food irradiation. Consumers may have a negative view of irradiated food based on the misconception that such food is radioactive; in fact, irradiated food does not and cannot become radioactive. Activists have also opposed food irradiation for other reasons, for example, arguing that irradiation can be used to sterilize contaminated food without resolving the underlying cause of the contamination. International legislation on whether food may be irradiated or not varies worldwide from no regulation to a full ban. Approximately 500,000 tons of food items are irradiated per year worldwide in over 40 countries. These are mainly spices and condiments, with an increasing segment of fresh fruit irradiated for fruit fly quarantine.
Barcodes – The barcode was invented in 1948. However, NASA developed a type of barcode label that could endure in space environments. Cordless power tools – The first cordless power tool was unveiled by Black & Decker in 1961. These were used by NASA and a number of spinoff products came out of those projects such as portable cordless vacuums. Magnetic resonance imaging (MRI), best known as a device for body scanning. NASA contractor JPL developed digital signal processing, which has applications in medical imaging used by MRIs. However, JPL works like a department of NASA. Microchip – The first hybrid integrated circuit was developed by Texas Instruments in 1958, and then the silicon integrated circuit microchip was invented by Robert Noyce at Fairchild Semiconductor in 1959. The impact of NASA was in creating a massive impetus for development in this area. Quartz clocks – The first quartz clock was invented in 1927. However, in the late 1960s, NASA partnered with a company to make a highly accurate quartz clock. Smoke detectors – NASA's connection to the modern smoke detector is that it developed one with adjustable sensitivity as part of the Skylab project; this development helps with nuisance tripping. Space Pen – An urban legend states that NASA spent a large amount of money to develop a pen that would write in space (the result purportedly being the Fisher Space Pen), while the Soviets used pencils. While NASA did spend funds to create a pen to work in space, the project was cancelled due to public opposition, and U.S.
When NAD+ levels are low, nicotinic acid mononucleotide (NaMN) can bind to the allosteric region and inhibit SARM1 activity, thus explaining the potent axon protection provided by treating neurons with the NaMN precursor nicotinic acid riboside (NaR) while inhibiting NAMPT. Chemical screening approaches have also identified covalent inhibitors of SARM1's allosteric ARM domain region. Other pro-degeneration signaling pathways, such as the MAP kinase pathway, have been linked to SARM1 activation. MAPK signaling has been shown to promote the loss of NMNAT2, thereby promoting SARM1 activation. SARM1 activation also triggers the MAP kinase cascade, indicating some form of feedback loop may exist.
transactivation An experimental approach to artificially control gene expression by introducing a transactivator gene under the control of an inducible promoter into a genome. The transactivator encodes a transcription factor capable of acting in trans upon one or more other genes by recognizing and specifically binding their promoters; thus by inducing the transactivator gene, the expression of many other genes can be experimentally manipulated.
Carbon nanotubes are used in multiple industrial and consumer applications. These include battery components, polymer composites, to improve the mechanical, thermal and electrical properties of the bulk product, and as a highly absorptive black paint. Many other applications are under development, including field effect transistors for electronics, high-strength fabrics and biosensors for biomedical and agricultural applications.
Sources: en.wikipedia.org
=== 7 July === Russian forces claimed to have taken the settlement of Chyhari (part of Pivdenne) in Donetsk Oblast. Four people were killed after their vehicle struck a Russian-planted mine in Kharkiv Oblast. Russian officials claimed that Iskander ballistic missiles destroyed two Patriot missile launchers in Odesa. The Ukrainian Air Force confirmed the attack but provided no further information. The Ukrainian military claimed to have shot down a Russian Su-25 fighter jet over Donetsk Oblast. Russian officials claimed that falling debris from Ukrainian drones set fire to a warehouse in Voronezh Oblast which contained explosives. Another drone was reported shot down over Belgorod Oblast. Explosions were reported at a number of locations around occupied Melitopol, including the Melitopol Air Base, the railway station and other areas. Locals said that Russian air defence was activated during the incident.
It should be clearly understood that the major role of the profession is patient care and that research, management and all the other aspects will come as side issues and not be the predominating factor in the career path. The work of biomedical scientists and clinical scientists have impact on the diagnosis and treatment of almost every patient admitted to hospitals in the United Kingdom. The United Kingdom is facing a shortage of qualified clinical and biomedical scientists. The Royal College of Pathologists and the Royal College of Physicians have pointed out the need for increased government funding for medical training programs to prevent diagnostic facilities and medical infrastructure from being overwhelmed. MSF claims that these workers have lost out financially since the decision of the then health minister Kenneth Clarke to exclude them from the pay review body in 1984.
The use of N-terminal Fmoc deprotection scheme is truly orthogonal under SPPS conditions. Fmoc deprotection is a base-catalyzed elimination reaction that typically uses 20–50% piperidine in DMF. The revealed alpha-amine functionality is therefore neutral, and consequently no neutralization of the peptide-resin is required, as in the case of the Boc/Bzl approach. The lack of electrostatic repulsion between the peptide chains can lead to increased risk of aggregation with Fmoc/tBu SPPS however. Because the liberated fluorenyl group is a chromophore, Fmoc deprotection can be monitored by UV absorbance of the reaction mixture, a strategy which is employed in automated peptide synthesizers. The ability of the Fmoc group to be cleaved under relatively mild basic conditions while being stable to acid allows the use of side chain protecting groups such as Boc and tBu that can be removed in milder acidic final cleavage conditions (TFA) than those used for final cleavage in Boc/Bzl SPPS (HF). Scavengers such as water and triisopropylsilane (TIPS) are most commonly added during the final cleavage in order to prevent side reactions with reactive cationic species released as a result of side chain deprotection. Nevertheless, many other scavenger compounds could be used as well. The resulting crude peptide is obtained as a TFA salt, which is potentially more difficult to solubilize than the fluoride salts generated in Boc SPPS. Fmoc/tBu SPPS is less atom-economical, as the fluorenyl group has a much higher mass than the Boc group.
In 2000, crews organized by Jack Horner discovered five Tyrannosaurus skeletons near the Fort Peck Reservoir. In 2001, a 50% complete skeleton of a juvenile Tyrannosaurus was discovered in the Hell Creek Formation by a crew from the Burpee Museum of Natural History. Dubbed Jane (BMRP 2002.4.1), the find was thought to be the first known skeleton of a pygmy tyrannosaurid, Nanotyrannus, but other researchers considered it as the most complete juvenile T. rex; currently exhibited at the Burpee Museum of Natural History, Jane is now re-described as the holotype of N. lethaeus. In 2002, a skeleton nicknamed "Wyrex", discovered by amateur collectors Dan Wells and Don Wyrick, had 114 bones and was 38% complete. The dig was concluded in 2004 by the Black Hills Institute with the first live online Tyrannosaurus excavation. In 2006, Montana State University revealed that it possessed the largest Tyrannosaurus skull yet discovered (from a specimen named MOR 008), measuring 5 feet (152 cm) long. Subsequent comparisons indicated that the longest head was 136.5 centimetres (53.7 in) (from specimen LACM 23844) and the widest head was 90.2 centimetres (35.5 in) (from Sue).
Sources: en.wikipedia.org
== Approvals and clinical trials == In Germany, CXL has been used in patients with keratoconus since 1998, and in Italy, routine interventions have been successfully performed since 2005. The standard (Dresden) CXL protocol with epithelium removal, is approved for use throughout Europe. In the United States, clinical trials commenced only in 2008. Based on three 12-month clinical trials, the US Food and Drug Administration approved riboflavin ophthalmic solution and Avedro's KXL system for crosslinking on 18 April 2016, for the treatment of progressive keratoconus, and on 19 July 2016, for corneal ectasia after refractive surgery, making them the first FDA approved treatment for keratoconus and post-LASIK ectasia.
Many types of breeder reactor are possible: A "breeder" is simply a nuclear reactor designed for very high neutron economy with an associated conversion ratio higher than 1.0. In principle, almost any reactor design could be tweaked to become a breeder. For example, the reduced-moderation water reactor concept uses mixed-oxide fuel in a tight lattice to increase the conversion ratio. Aside from water-cooled, there are many other types of breeder reactor currently envisioned as possible. These include molten-salt cooled, gas cooled, and liquid-metal cooled designs in many variations. Almost any of these basic design types may be fueled by uranium, plutonium, many minor actinides, or thorium, and they may be designed for many different goals, such as creating more fissile fuel, long-term steady-state operation, or active burning of nuclear wastes. Extant reactor designs are sometimes divided into two broad categories based upon their neutron spectrum, which generally separates those designed to use primarily uranium and transuranics from those designed to use thorium and avoid transuranics. These designs are:
=== 2025 elections === On October 5, 2024, Duterte announced that he will run for mayor of Davao City, with his son, incumbent Mayor Sebastian Duterte, as his running mate for vice mayor in 2025. He also rejected calls for him to run for senator, citing his old age. Duterte officially filed his candidacy on October 7; however, on November 7, he welcomed the candidacy of his former cabinet secretary, former Civil Service Commission chairperson Karlo Nograles as Davao City mayor, adding he is retired and wishes to give the position to the next generation. In May 2025, Duterte was elected as mayor despite his detention at The Hague by the ICC. However, he was unable to take his oath on the start of his term on June 30, 2025, due to his imprisonment. As a result, his son Sebastian, who was elected vice mayor, became acting mayor. On January 23, 2026, Sebastian was sworn in as mayor of Davao City, following his father's failure to take the oath of office within the six-month prescribed period due to his detention.
Liver cirrhosis makes it hard for blood to flow in the portal venous system. This resistance creates a backup of blood and increases pressure. This results in portal hypertension. Effects of portal hypertension include:
Riboflavin, also known as vitamin B2, is a vitamin found in food and sold as a dietary supplement. It is essential to the formation of two major coenzymes, flavin mononucleotide and flavin adenine dinucleotide. These coenzymes are involved in energy metabolism, cellular respiration, and antibody production, as well as normal growth and development. The coenzymes are also required for the metabolism of niacin, vitamin B6, and folate. Riboflavin is prescribed to treat corneal thinning, and taken orally, may reduce the incidence of migraine headaches in adults. Riboflavin deficiency is rare and is usually accompanied by deficiencies of other vitamins and nutrients. It may be prevented or treated by oral supplements or by injections. As a water-soluble vitamin, any riboflavin consumed in excess of nutritional requirements is not stored; it is either not absorbed or is absorbed and quickly excreted in urine, causing the urine to have a bright yellow tint. Natural sources of riboflavin include meat, fish and fowl, eggs, dairy products, green vegetables, mushrooms, and almonds. Some countries require its addition to grains. In its purified, solid form, it is a water-soluble yellow-orange crystalline powder. In addition to its function as a vitamin, it is used as a food coloring agent. Biosynthesis takes place in bacteria, fungi and plants, but not animals. Industrial synthesis of riboflavin was initially achieved using a chemical process, but current commercial manufacturing relies on fermentation methods using strains of fungi and genetically modified bacteria.
Sources: en.wikipedia.org
Glutathione is a tripeptide made from glutamate, cysteine, and glycine. Its cysteine residue provides a thiol group that is central to its redox activity. The glutamate-cysteine bond forms through the gamma-carboxyl group of glutamate.
Reduced glutathione, GSH, can donate electrons and become oxidized to GSSG. The balance between these forms reflects the cell's redox environment. A shift toward GSSG is commonly interpreted as evidence of oxidative stress, though the ratio can vary by tissue and method.
Glutathione occurs in nearly all cell types, with notable amounts in the liver. It is also present in the lungs, kidneys, and red blood cells. Concentrations differ among tissues and change with age, diet, and disease states.
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.