Everything below concerns sample acidification. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2026-05-13. Numbers and descriptions here follow the published literature rather than marketing material.
Glutathione participates in detoxification reactions, amino acid transport, and the maintenance of protein thiols. It serves as a cofactor for several enzymes, including glutathione peroxidases and glutathione S-transferases. In research literature, altered glutathione status appears in studies of aging, infection, metabolic stress, and environmental exposure. Whether low glutathione is a cause, consequence, or marker of such conditions often remains unresolved. Direct measurement in blood or tissue provides a snapshot, but results depend on sample handling, timing, and the method used.
Glutathione is a small tripeptide made of glutamic acid, cysteine, and glycine. Its cysteine thiol group allows reversible oxidation and reduction, making it central to cellular redox chemistry. The reduced form, often abbreviated GSH, predominates inside most cells, while the oxidized disulfide form, GSSG, forms when two GSH molecules react. The ratio of GSH to GSSG is widely used as an indicator of oxidative stress in laboratory research, though it does not by itself diagnose a clinical condition.
Biosynthesis occurs in two ATP-dependent steps. The enzyme glutamate-cysteine ligase joins glutamate and cysteine, forming gamma-glutamylcysteine; glutathione synthetase then adds glycine to produce the complete tripeptide. Because the peptide bond from glutamate uses the gamma-carboxyl group, glutathione resists digestion by many ordinary peptidases. Tissues vary in synthesis capacity, and the liver generally contains high concentrations relative to many other organs. This uneven distribution contributes to organ-specific differences in redox buffering and affects how experimental results are interpreted across tissue types.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C10H17N3O6S | Reduced glutathione (GSH); oxidized form differs by disulfide linkage. |
| Molar mass | 307.32 g/mol | Calculated for the reduced tripeptide. |
| Appearance | White to off-white crystalline powder | Typical laboratory reagent description. |
| Solubility | Soluble in water | Aqueous solutions are acidic; solubility depends on pH and salt form. |
| CAS Registry Number | 70-18-8 | Refers to reduced L-glutathione; oxidized form has a different number. |
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.
Commercial glutathione is available in research-grade, food-grade, and supplement-grade forms, and purity specifications differ accordingly. Certificates of analysis commonly report identity by nuclear magnetic resonance or mass spectrometry, purity by HPLC, residual solvents, and heavy metals. Reference standards with assigned purity support calibration, while isotopically labeled glutathione can serve as an internal standard for mass spectrometry. For supplements, label claims may not be independently verified, and regulatory oversight varies by country. Verification often involves third-party testing for identity, potency, and contaminants.
Quantifying glutathione requires distinguishing GSH from GSSG and preventing oxidation during sample preparation. Common approaches include the enzymatic recycling assay, often called the Tietze method, which measures total glutathione after converting GSSG to GSH. HPLC with ultraviolet or fluorescence detection and LC-MS/MS can separate and quantify both forms, sometimes after derivatization of the thiol group. Blood, plasma, and tissue samples differ in matrix and baseline concentrations, so method validation must account for recovery, linearity, and interference. No single assay is universally standard.
Waschkies et al. studied the structure of dilute to concentrated freeze-casts from low (< 1 μm s−1) to extremely high (> 700 μm s−1) solidification velocities. From this study, they were able to generate morphological maps for freeze-cast structures made under various conditions. Maps such as these are excellent for showing general trends, but they are quite specific to the materials system from which they were derived. For most applications where freeze-casts will be used after freezing, binders are needed to supply strength in the green state. The addition of binder can significantly alter the chemistry within the frozen environment, depressing the freezing point and hampering particle motion leading to particle entrapment at speeds far below the predicted vc. Assuming, however, that we are operating at speeds below vc and above those which produce a planar front, we will achieve some cellular structure with both ice-crystals and walls composed of packed ceramic particles. The morphology of this structure is tied to some variables, but the most influential is the temperature gradient as a function of time and distance along the freezing direction. Freeze-cast structures have at least three apparent morphological regions. At the side where freezing initiates is a nearly isotropic region with no visible macropores dubbed the Initial Zone (IZ). Directly after the IZ is the Transition Zone (TZ), where macropores begin to form and align with one another. The pores in this region may appear randomly oriented.
Filter papers are widely used in laboratory experiments across many different fields, from biology to chemistry. The type of filter used will differ according to the purpose of the procedure and the chemicals involved. Generally, filter papers are used with laboratory techniques such as gravity or vacuum filtration. Historically, a type of soft, porous paper called charta emporetica was used in pharmacy as a filter and as packing paper.
==== Secret burial ==== In rare cases, a known person may be buried without identification, perhaps to avoid desecration of the corpse, grave robbing, or vandalism of the burial site. This may be particularly the case with infamous or notorious figures. In other cases, it may be to prevent the grave from becoming a tourist attraction or a destination of pilgrimage. Survivors may cause the deceased to be buried in a secret location or other unpublished place, or in a grave with a false name (or no name at all) on the marker. Following Walt Disney's cremation, his ashes were buried in a secret location in Forest Lawn Memorial Park Cemetery, California. Some burial sites at Forest Lawn, such as those of Humphrey Bogart, Mary Pickford and Michael Jackson, are secluded in private gated gardens or mausoleums with no public access. A number of tombs are also kept from the public eye. Forest Lawn's Court of Honor indicates that some of its crypts have plots which are reserved for individuals who may be "voted in" as "Immortals"; no amount of money can purchase a place. Photographs taken at Forest Lawn are not permitted to be published, and their information office usually refuses to reveal exactly where the remains of famous people are buried.
== Semantics of changing care: why "flexible" is replacing "intensive" therapy == Over the last two decades, the evidence that better glycemic control (i.e., keeping blood glucose and HbA1c levels as close to normal as possible) reduces the rates of many complications of diabetes has become overwhelming. As a result, diabetes specialists have expended increasing effort to help most people with diabetes achieve blood glucose levels as close to normal as achievable. It takes about the same amount of effort to achieve good glycemic control with a traditional two or three injection regimen as it does with flexible therapy: frequent glucose monitoring, attention to timing and amounts of meals. Many diabetes specialists no longer think of flexible insulin therapy as "intensive" or "special" treatment for a select group of patients but simply as standard care for most patients with type 1 diabetes.
Sources: en.wikipedia.org
In-N-Out Burgers, doing business as In-N-Out Burger, is an American regional chain of fast food restaurants with locations primarily in California and to a lesser extent the West Coast and Southwest. It was founded in Baldwin Park, California, in 1948 by Harry (1913–1976) and Esther Snyder (1920–2006). The chain is headquartered in Irvine, California, and has expanded outside Southern California into the rest of California, as well as into Arizona, Nevada, Utah, Texas, Oregon, Colorado, Idaho, Washington, and Tennessee, and is planning expansion into New Mexico. The current owner is Lynsi Snyder, the Snyders' only grandchild. As the chain has expanded, it has opened several distribution centers in addition to its original Baldwin Park location. The new facilities, located in Lathrop, California; Phoenix, Arizona; Draper, Utah; Dallas, Texas; and Colorado Springs, Colorado, will provide for potential future expansion into other parts of the country. In-N-Out Burger has chosen not to franchise its operations or go public; one reason is the prospect of food quality or customer consistency being compromised by excessively rapid business growth. The In-N-Out restaurant chain has developed a highly loyal customer base, and has been rated as one of the top fast food restaurants in several customer satisfaction surveys.
== ST == st – (s) Sotho language (ISO 639-1 code) ST (s) Saint Lucia (FIPS 10-4 country code) São Tomé and Príncipe (ISO 3166 digram) STA (i) Scheduled Time of Arrival Surveillance and Target Acquisition STAGE – (a) Scenario Toolkit And Generation Environment STANAG – (p) (NATO) Standardisation Agreement STAR (a) Scientific and Technical Aerospace Reports (NASA) Simulation of Tactical Alternative Responses Special Threat Analysis and Recognition STAT (a) Signal Transducers and Activators of Transcription (cell biology) Special Tertiary Admissions Test (Australia) STB - Surface Transportation Board STC – (i) Superior Temporal Cortex S&TCD – (i) CERDEC Space and Terrestrial Communications Directorate STD (s) São Tomé and Príncipe dobra (ISO 4217 currency code) (i) Sexually Transmitted Disease STDM – (i) Statistical Time Division Multiplexing STEM (a) Scanning transmission electron microscopy Science, technology, engineering, and mathematics (p) Spatiaotemporal Epidemiological Modeler (IBM-developed software) STENTOR – (p) Satellite de télécommunications pour expérimenter de nouvelles technologies en orbite (French, "Orbital New Technology Experimental Telecommunications Satellite") STFU (i) Southern Tenant Farmers Union Stuff You "Shut the fuck up!" STH – Sonic the Hedgehog STI (i) Sexually Transmitted Infection Subaru Tecnica International STK – (i) Satellite Tool Kit STM – (i) Short Term Memory STOL – (i) Short Take-Off and Landing STOVL – (i) Short Take-Off and Vertical Landing STP (s) São Tomé and Príncipe (ISO 3166 trigram) (i) Standard Temperature and Pressure STR – (i) Short Tandem Repeat (DNA analysis) STRATCOM – (p) United States Strategic Command STRICOM (p) U.S. Army Simulation, Training & Instrumentation Command (1992–) Strike Command (1962–1971) STRIVE – (a) Synthetic Tactical Real-time Interactive Virtual Environment STSM – (i) Senior Technical Staff Member Stuka – (p) Sturzkampfflugzeug (German WWII dive bomber)
While the first transfusions had to be made directly from donor to receiver before coagulation, it was discovered that by adding anticoagulant and refrigerating the blood it was possible to store it for some days, thus opening the way for the development of blood banks. John Braxton Hicks was the first to experiment with chemical methods to prevent the coagulation of blood at St Mary's Hospital, London in the late-19th century. His attempts, using phosphate of soda, however, proved unsuccessful. The Belgian doctor Albert Hustin performed the first non-direct transfusion on March 27, 1914, though this involved a diluted solution of blood. The Argentine doctor Luis Agote used a much less diluted solution in November of the same year. Both used sodium citrate as an anticoagulant. The First World War (1914–1918) acted as a catalyst for the rapid development of blood banks and transfusion techniques. Francis Peyton Rous and Joseph R. Turner at the Rockefeller University (then The Rockefeller Institute for Medical Research) made the first important discoveries that blood typing was necessary to avoid blood clumping (coagulation) and blood samples could be preserved using chemical treatment. Their first report in March 1915 showed that gelatine, agar, blood serum extracts, starch and beef albumin proved to be useless preservatives.
== Causes == Refeeding syndrome – This causes a demand for phosphate in cells due to the action of hexokinase, an enzyme that attaches phosphate to glucose to begin metabolism of glucose. Also, production of ATP when cells are fed and recharge their energy supplies requires phosphate. A similar mechanism is seen in the treatment of diabetic ketoacidosis, which can be complicated by respiratory failure in these cases due to respiratory muscle weakness. Respiratory alkalosis – Any alkalemic condition moves phosphate out of the blood into cells. This includes most common respiratory alkalemia (a higher than normal blood pH from low carbon dioxide levels in the blood), which in turn is caused by any hyperventilation (such as may result from sepsis, fever, pain, anxiety, drug withdrawal, and many other causes). This phenomenon is seen because in respiratory alkalosis carbon dioxide (CO2) decreases in the extracellular space, causing intracellular CO2 to freely diffuse out of the cell. This drop in intracellular CO2 causes a rise in cellular pH which has a stimulating effect on glycolysis. Since the process of glycolysis requires phosphate (the end product is adenosine triphosphate), the result is a massive uptake of phosphate into metabolically active tissue (such as muscle) from the serum. However, that this effect is not seen in metabolic alkalosis, for in such cases the cause of the alkalosis is increased bicarbonate rather than decreased CO2. Bicarbonate, unlike CO2, has poor diffusion across the cellular membrane and therefore there is little change in intracellular pH.
== Medical uses == Several treatment guidelines recommend adding ezetimibe in select high-risk persons in whom LDL goals cannot be achieved by maximally tolerated statin alone. Adding ezetimibe to statin treatment of high blood cholesterol has no effect on overall mortality or cardiovascular mortality, although it significantly reduces the risk of myocardial infarction and stroke. Combining ezetimibe with simvastatin had no effect on overall mortality but did lower the risk of heart attack or stroke in people with prior heart attack. Initiation of ezetimibe along with high-intensity statin therapy at the time of an acute coronary syndrome (ACS) event was associated with significantly better cholesterol reduction at day 7, 1-month, 3-months, and 1-year post-ACS event; which translated into significantly lower recurrent cardiovascular events (death from any cause, major ACS, non-fatal stroke, non-fatal myocardial infarction, and ischemic stroke) post the index event of ACS. Ezetimibe is indicated in the United States as an add-on to dietary measures to reduce levels of certain lipids in people with:
Sources: en.wikipedia.org
In 2022, an article in The New York Times reported several instances of women experiencing reduced clitoral sensitivity or inability to orgasm following various surgical procedures, including biopsies of the vulva, pelvic mesh surgeries (sling surgeries), and labiaplasties. The Times quoted several researchers who suggest that surgeons' lack of training in clitoral anatomy and nerve distribution may have been a factor. As it is part of the vulva, the clitoris is susceptible to pain (clitorodynia) from various conditions such as sexually transmitted infections and pudendal nerve entrapment. The clitoris may also be affected by vulvar cancer, although at a much lower rate. Clitoral phimosis (or clitoral adhesions) is when the prepuce cannot be retracted, limiting exposure of the glans.
=== Aquatic environments === Most PAHs are insoluble in water, which limits their mobility in the environment, although PAHs sorb to fine-grained organic-rich sediments. Aqueous solubility of PAHs decreases approximately logarithmically as molecular mass increases. Two-ringed PAHs, and to a lesser extent three-ringed PAHs, dissolve in water, making them more available for biological uptake and degradation. Further, two- to four-ringed PAHs volatilize sufficiently to appear in the atmosphere predominantly in gaseous form, although the physical state of four-ring PAHs can depend on temperature. In contrast, compounds with five or more rings have low solubility in water and low volatility; they are therefore predominantly in solid state, bound to particulate air pollution, soils, or sediments. In solid state, these compounds are less accessible for biological uptake or degradation, increasing their persistence in the environment.
The social organization of the earliest Paleolithic (Lower Paleolithic) societies remains largely unknown to scientists, though Lower Paleolithic hominins such as Homo habilis and Homo erectus are likely to have had more complex social structures than chimpanzee societies. Late Oldowan/Early Acheulean humans such as Homo ergaster/Homo erectus may have been the first people to invent central campsites or home bases and incorporate them into their foraging and hunting strategies like contemporary hunter-gatherers, possibly as early as 1.7 million years ago; however, the earliest solid evidence for the existence of home bases or central campsites (hearths and shelters) among humans only dates back to 500,000 years ago. Similarly, scientists disagree whether Lower Paleolithic humans were largely monogamous or polygynous. In particular, the Provisional model suggests that bipedalism arose in pre-Paleolithic australopithecine societies as an adaptation to monogamous lifestyles; however, other researchers note that sexual dimorphism is more pronounced in Lower Paleolithic humans such as Homo erectus than in modern humans, who are less polygynous than other primates, which suggests that Lower Paleolithic humans had a largely polygynous lifestyle, because species that have the most pronounced sexual dimorphism tend more likely to be polygynous. Human societies from the Paleolithic to the early Neolithic farming tribes lived without states and organized governments.
In fluid dynamics, the Darcy–Weisbach equation is an empirical equation that relates the head loss, or pressure loss, due to viscous shear forces along a given length of pipe to the average velocity of the fluid flow for an incompressible fluid. The equation is named after Henry Darcy and Julius Weisbach. Currently, there is no formula more accurate or universally applicable than the Darcy–Weisbach supplemented by the Moody diagram or Colebrook equation. The Darcy–Weisbach equation contains a dimensionless friction factor, known as the Darcy friction factor. This is also variously called the Darcy–Weisbach friction factor, friction factor, resistance coefficient, or flow coefficient.
Alongside many domestic obligations, more than 3,000 Canadian Armed Forces (CAF) personnel are deployed in multiple foreign military operations. The Canadian unified forces comprise the Royal Canadian Navy, Canadian Army, and Royal Canadian Air Force. The nation employs a professional, volunteer force of approximately 68,000 active personnel and 27,000 reserve personnel. Canada will spend 2% of its GDP on defence by the 2026 fiscal year, up from 1.3% and 1.4% in previous years. Peacekeeping is deeply embedded in Canadian culture and a distinguishing feature that Canadians feel sets their foreign policy apart from the United States. Canada has long been reluctant to participate in military interventions that are not sanctioned by the United Nations, such as the Vietnam War, the 2003 invasion of Iraq and the 2026 Iran war. Since the 21st century, Canadian direct participation in UN peacekeeping efforts has greatly declined. The large decrease was a result of Canada directing its participation to UN-sanctioned military operations through the North Atlantic Treaty Organization, rather than directly through the UN. The change to participation via NATO has resulted in a shift towards more militarized and deadly missions rather than traditional peacekeeping duties.
Sources: en.wikipedia.org
GSH is the reduced form of glutathione, with a free thiol group on cysteine. GSSG is the oxidized disulfide form, created when two GSH molecules become linked. The two forms exist together, and their balance is often reported as the GSH/GSSG ratio in laboratory studies.
Glutathione is synthesized inside cells from amino acids rather than being classified as an essential dietary nutrient. Dietary sources can provide glutathione or its precursors, but digestion and absorption alter what reaches tissues. Research continues on how dietary intake relates to cellular glutathione levels.
The liver has high glutathione concentrations and uses the compound in conjugation and antioxidant reactions. These reactions are relevant to the processing of drugs, pollutants, and normal metabolic byproducts. Studies often examine liver glutathione as a marker of oxidative stress or detoxification capacity.
Chromatographic methods can separate the two forms before detection. Enzymatic assays often measure total glutathione first and then use a separate procedure to estimate the oxidized fraction. The difference between total and oxidized amounts provides an indirect estimate of the reduced form.