freeze-thaw 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 2025-08-24. Numbers and descriptions here follow the published literature rather than marketing material.
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.
Glutathione is a tripeptide composed of glutamate, cysteine, and glycine. The peptide bond between glutamate and cysteine uses the gamma-carboxyl group of glutamate rather than the alpha-carboxyl group. This unusual linkage protects the molecule from many common peptidases. The cysteine side chain carries a thiol group that can undergo reversible oxidation. Because of this thiol, glutathione participates in redox reactions and helps maintain the reducing environment inside most cells in living systems.
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.
Quality control for glutathione measurements includes calibration with authenticated standards, internal standards where available, blank correction, and spike recovery checks. Because glutathione can form during sample processing or degrade before analysis, pre-analytical handling is a major source of variability. Interlaboratory comparisons often show differences in reported values due to method-specific calibration and detection principles. Interpretive thresholds are context-dependent, and no single reference range applies across all tissues or matrices. Researchers generally report both reduced and oxidized forms, along with the method and sample handling details.
Quantification of glutathione in biological or food samples commonly uses liquid chromatography coupled to ultraviolet, fluorescence, electrochemical, or mass spectrometric detection. Because the thiol group oxidizes readily, samples are often acidified or derivatized immediately after collection to stabilize reduced glutathione. Enzymatic recycling assays and colorimetric kits offer higher throughput but generally lower specificity than chromatographic methods. Mass spectrometry can distinguish glutathione from related thiols and allow simultaneous measurement of oxidized forms. Reported concentrations depend strongly on sample type, extraction procedure, and analytical platform.
| 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 |
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.
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.
Commercial glutathione is produced by microbial fermentation or chemical synthesis, then purified. Reduced and oxidized grades are offered separately, with purity specifications often exceeding 98 percent. The compound appears in foods such as fresh fruits, vegetables, and meats, although cooking and processing can lower amounts. Oral, topical, and inhaled forms are discussed in research and consumer contexts, but absorption and tissue delivery remain active areas of study. Regulatory status varies by country and intended use.
Glutathione is a small sulfur-containing peptide built from glutamic acid, cysteine, and glycine. Its distinctive feature is a gamma-glutamyl bond between glutamate's side-chain carboxyl group and cysteine's amino group. This linkage resists ordinary peptidases and helps the molecule remain stable inside cells. The reduced thiol form, often abbreviated GSH, is the dominant intracellular species. The oxidized disulfide dimer, GSSG, forms when two reduced molecules link through their cysteine sulfur atoms. The balance between these forms is a common redox indicator.
== Magnet programs and centers == Magnet programs were first implemented in PGCPS in 1985, to fulfill a court-ordered desegregation mandate. Up until as late as the late 80s, Prince George's County had been predominantly white in terms of racial demographics. In order to desegregate mostly all-White schools in the school system, PGCPS created several magnet programs that eventually were instituted in over fifty schools, spread throughout the county. By the late 1990s, the population demographics of the county had shifted towards a mostly African American majority. Magnet programs (as they were set up) were costing PGCPS approximately $14 million per year, to operate. The programs were costly and this was exacerbated by the fact that the school system's operating budget was greater than the final budget the school system had traditionally been allotted, an issue that had plagued the school system for years. Since the county's population now primarily consisted of African Americans, and due to the expense of operating the Magnet Schools Program, courts began to investigate the justification of PGCPS's magnet program. In 2004, a court ruled to discontinue court-ordered busing which had existed in the county, for over 30 years, based primarily on the fact that desegregation was no longer an issue in the predominantly Black Prince George's County. With the ending of the court-ordered busing, also came changes to the school system's Magnet Schools Program. The program had gained national attention, as it was one of the largest in the country.
Watch manufacture was becoming streamlined; the Japy family of Schaffhausen, Switzerland, led the way in this, and soon afterwards the newborn American watch industry developed much new machinery, so that by 1865 the American Watch Company (afterwards known as Waltham) could turn out more than 50,000 reliable watches each year. This development drove the Swiss out of their dominating position at the cheaper end of the market, compelling them to raise the quality of their products and establish themselves as the leaders in precision and accuracy instead.
It is characterized by mild summers with only 1 to 3 months above 10 °C or 50 °F and cold, snowy, extremely windy winters below −3 °C or 26.6 °F, although usually above −10 °C or 14 °F. The chain ranges from temperate to sub-Arctic climate types, and the vegetative cover consequently ranges from tundra in the north to dense spruce and larch forests on the larger southern islands. The highest elevations on the islands are Alaid Volcano (highest point: 2,339 m or 7,674 ft) on Atlasov Island at the northern end of the chain and Tyatya volcano (1,819 m or 5,968 ft) on Kunashir Island at the southern end. Landscape types and habitats on the islands include many kinds of beach and rocky shores, cliffs, wide rivers and fast gravelly streams, forests, grasslands, alpine tundra, crater lakes and peat bogs. The soils are generally productive, owing to the periodic influxes of volcanic ash and, in certain places, owing to significant enrichment by seabird guano. However, many of the steep, unconsolidated slopes are susceptible to landslides and newer volcanic activity can entirely denude a landscape. Only the southernmost island has large areas covered by trees, while more northerly islands have no trees, or spotty tree cover.
Alpha-synuclein has been shown to interact with Dopamine transporter, Parkin (ligase), Phospholipase D1, SNCAIP, Tau protein. Beta amyloid Synuclein Contursi Terme - the village in Italy where a mutation in the α-synuclein gene led to a family history of Parkinson's disease Anti-α-synuclein drug Media related to Alpha-synuclein at Wikimedia Commons alpha-Synuclein at the U.S. National Library of Medicine Medical Subject Headings (MeSH) Human SNCA genome location and SNCA gene details page in the UCSC Genome Browser.
Tranexamic acid is a medication used to treat or prevent excessive blood loss from major trauma, postpartum bleeding, surgery, tooth removal, nosebleeds, and heavy menstruation. It is also used for hereditary angioedema. It is taken either by mouth, injection into a vein, or by intramuscular injection. Tranexamic acid is a synthetic analog of the amino acid lysine. It serves as an antifibrinolytic by reversibly binding four to five lysine receptor sites on plasminogen. This decreases the conversion of plasminogen to plasmin, preventing fibrin degradation and preserving the framework of fibrin's matrix structure. Tranexamic acid has roughly eight times the antifibrinolytic activity of an older analogue, ε-aminocaproic acid. Tranexamic acid also directly inhibits the activity of plasmin with weak potency (IC50 = 87 mM), and it can block the active-site of urokinase plasminogen activator (uPA) with high specificity (Ki = 2 mM), one of the highest among all the serine proteases. Side effects are rare; they include changes in color vision, seizures, blood clots, and allergic reactions. Tranexamic acid appears to be safe for use during pregnancy and breastfeeding. Tranexamic acid was first made in 1962 by Japanese researchers Shosuke and Utako Okamoto. It is on the World Health Organization's List of Essential Medicines. Tranexamic acid is available as a generic drug.
Sources: en.wikipedia.org
Currently, no over-the-counter weight-loss supplements have met criteria for recommended use by physicians. Dexatrim claims to provide a powerful benefit for weight loss despite the lack of scientific data to support their claims. Dexatrim further provides a disclaimer that no claims of efficacy and safety made by Dexatrim have been approved by the FDA. Although available OTC, the active ingredients in Dexatrim products carry risk of side effects, adverse reactions and adverse drug interactions, particularly if used at high-recommended or higher-than-recommended doses and/or for prolonged periods. The Dexatrim product itself carries a warning about the possible side effects of Dexatrim in patients with a history of high blood pressure, and also recommends the advice of a qualified physician before taking Dexatrim. In addition, the use of Dexatrim or other OTC weight-loss supplements presents a possible factor in establishing disruptive eating patterns, increases the risk that individuals will use these OTC supplements in lieu of seeking proper medical and nutritional consultation, and presents increased psychological risks associated with unsuccessful weight-loss attempts.
Antimony-125 decays with a half-life of over two years to 125mTe which itself decays with a half-life of almost two months via isomeric transition to the ground state. While its relatively short half-life and the significant gamma emissions (144.77 keV) of its daughter nuclide make usage in an RTG less attractive, Sb-125 could deliver a relatively high power density of 3.4 Wthermal/g. Fluoride volatility can recover antimony as the mildly volatile (solid at room temperature) antimony trifluoride or the more volatile (boiling point 422.6 K (149.5 °C; 301.0 °F)) antimony pentafluoride.
Taurine given to a range of animal species is found to boost health and extend lifespan by up to 12%. 12 June – A time-use study provides the first comprehensive bird's-eye view of what humans currently spend their time on. The "global human day" framework enables better understanding, across fields of research, of the global human system in contexts such as technological change, civilization sustainability, global challenges or goals, societal changes, and economic time allocation. It identifies some factors of variations and activities "for which there is significant potential for change". 14 June Teams of researchers report creations of synthetic human model embryos from stem cells, without the need for sperm or egg cells (see also 1 August 2022), challenging legal, ethical, and biological concepts. Scientists report evidence that the planet Earth may have formed in just three million years, much faster than the 100 million years thought earlier. Astronomers report that the presence of phosphates on Enceladus, a moon of the planet Saturn, has been detected, completing the discovery of all the basic chemical ingredients for life on the moon. IBM computer scientists report that a quantum computer produced better results for a physics problem than a conventional supercomputer. A machine learning model is trained to recognise the key features of chemicals with senolytic activity. It finds three chemicals – ginkgetin, periplocin and oleandrin – able to remove senescent cells without damaging healthy cells.
Ghana has a universal health care system, National Health Insurance Scheme (NHIS), which is strictly designated for Ghanaian nationals. Health care is variable throughout Ghana and in 2012, more than 12 million Ghanaian nationals were covered by the NHIS. Urban centres are served and contain most of the hospitals, clinics, and pharmacies. There are more than 200 hospitals, and Ghana is a destination for medical tourism. In 2010, there were 0.1 physicians per 1,000 people and as of 2011, 0.9 hospital beds per 1,000 people. In 2010, 5.2% of Ghana's GDP was spent on health. In 2020, the WHO announced Ghana became the second country in the WHO African Region to attain regulatory system "maturity level 3", the second-highest in the four-tiered WHO classification of National medicines regulatory systems. Life expectancy at birth in 2021 was 68.6 for a female and 63.7 for a male. In 2013, infant mortality was to 39 per 1,000 live births. Sources vary on life expectancy at birth; the World Health Organization (WHO) estimated 64 years for women and 62 years for men born in 2016. The fertility rate declined from 3.99 (2000) to 3.28 (2010) with 2.78 in urban region and 3.94 in rural region. The United Nations reports a fertility decline from 6.95 (1970) to 4.82 (2000) to 3.93 live births per woman in 2017. As of 2012, the HIV/AIDS prevalence was estimated at 1.40% among adults aged 15–49.
Sources: en.wikipedia.org
The strictest criterion to define a vacuum is a region of space and time where all the components of the stress–energy tensor are zero. This means that this region is devoid of energy and momentum, and by consequence, it must be empty of particles and other physical fields (such as electromagnetism) that contain energy and momentum.
The United Nations High Commission for Refugees rejects the comments. Dr Mike McKean, vice-president for policy at the Royal College of Paediatrics and Child Health, says that public health messaging suggesting vaping is 95% safer than smoking is ineffective as a growing number of children are using e-cigarettes and experiencing health problems, and that messaging should have made it clearer that vaping should be for adults trying to give up smoking. Five Bulgarian nationals accused of being part of a Russian spy ring appear in court in central London and are remanded in custody. 27 September The Rosebank oil and gas field off Shetland, the UK's largest untapped oil field, is granted consent by regulators, amid widespread concerns over its contribution to climate change. GB News suspends Laurence Fox as a presenter while it investigates comments he made on the channel about Ava Evans, a female journalist. Later in the day, Dan Wootton is suspended over the same incident. The UK's first drugs consumption room gets the go-ahead in Glasgow, allowing heroin and cocaine addicts to use the substances under supervision. A report by the Education Select Committee draws attention to the increased number of absences from schools in England, which has doubled since the COVID-19 pandemic; data for 2022–23 shows an average of 22.3% of school pupils were absent, compared to between 10% and 12% in the years prior to the pandemic. A combination of mental health issues and the cost of living crisis are attributed to the increase.
This is a timeline of women in science, spanning from ancient history up to the 21st century. While the timeline primarily focuses on women involved with natural sciences such as astronomy, biology, chemistry, and physics, it also includes women from the social sciences (e.g. sociology, psychology), and the formal sciences (e.g. mathematics, computer science), as well as notable science educators and medical scientists. The chronological events listed in the timeline relate to both scientific achievements and gender equality within the sciences.
=== May === 1 May – MSPs vote 70–58 to defeat a motion of no confidence in the Scottish Government. 2 May – John Swinney is set to become the next SNP leader and first minister after Kate Forbes confirms she will not seek the party's leadership. 5 May – John Swinney warns that any bid to challenge his election as leader would delay rebuilding the party amid reports party activist Graeme McCormick is set to put his name forward. He subsequently announces he will not launch a challenge and endorses Swinney. 6 May – John Swinney is confirmed as Leader of the Scottish National Party after being unopposed in the leadership election, and begins his second tenure in the post. 7 May – John Swinney wins the backing of the Scottish Parliament to become Scotland's seventh First Minister, and will be sworn into office the next day. 8 May – John Swinney is sworn in as Scotland's seventh first minister at a ceremony at the Court of Session in Edinburgh. Swinney appoints Kate Forbes as Scotland's Deputy First Minister. Plans to redevelop Glasgow's Met Tower as a digital technology hub are cancelled, with the company behind the redevelopment citing "significant changes" to economic conditions and the construction market. 9 May – Swinney confirms to the BBC that the SNP's strategy of using the next general election as a mandate for a second referendum on Scottish independence remains. 10 May – Food Standards Scotland confirms a case of BSE has been found on a farm in Ayrshire, but says there is no risk to the public as the animal did not enter the food chain.
=== Artificial ligaments === One of the most often torn ligaments in the body is the anterior cruciate ligament (ACL). The ACL is one of the ligaments crucial to knee stability and persons who tear their ACL often undergo reconstructive surgery, which can be done through a variety of techniques and materials. One of these techniques is the replacement of the ligament with an artificial material. Artificial ligaments are a synthetic material composed of a polymer, such as polyacrylonitrile fiber, polypropylene, PET (polyethylene terephthalate), or polyNaSS poly (sodium styrene sulfonate).
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.
Acidification lowers pH and helps prevent oxidation of the thiol group during extraction and storage. It can also precipitate proteins and stabilize the reduced form before analysis.