The short version of Tietze assay fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2025-10-13 and is reviewed periodically as new material appears.
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.
Glutathione reference materials are sensitive to oxygen, light, and elevated temperature. Solid material is typically stored desiccated at -20 °C or below, while solutions require tighter control because thiol oxidation proceeds faster in liquid form. Aqueous solutions are often prepared fresh, kept cold, and protected from air; some protocols add acid or chelating agents to slow metal-catalyzed oxidation. Repeated freeze-thaw cycles can accelerate degradation and should be avoided. Stability data vary by matrix, so laboratories usually verify performance with their own storage conditions.
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.
For solid glutathione, storage conditions affect shelf life. The reduced form is typically kept cool, dry, and protected from air and light. Moisture can promote oxidation, while elevated temperatures accelerate degradation. Suppliers often specify storage at or below freezing, sometimes under inert gas. Solutions are less stable than powders and may require preparation shortly before use. Buffers and chelating agents can slow oxidation, but they do not eliminate it. Published stability data vary with matrix, pH, and container.
Quality control for glutathione focuses on identity, purity, and oxidation state. Certificates of analysis may report assay value, water content, and the presence of GSSG or other impurities. Chromatographic purity is often expressed as a percentage of peak area. Reference standards help laboratories compare results across instruments and batches. Because glutathione is a small, polar molecule, separation from cysteine, gamma-glutamylcysteine, and related thiols can be challenging. Verification often combines more than one analytical technique.
Measuring glutathione requires attention to sample preparation because the molecule oxidizes readily. Blood, tissue, and cell samples are often treated with acid to precipitate proteins and stabilize the thiol. Without such steps, GSH can convert to GSSG or form mixed disulfides during storage. Analytical methods include spectrophotometric assays, high-performance liquid chromatography, and mass spectrometry. Each approach has different sensitivity, specificity, and susceptibility to interference from related compounds in complex matrices.
| Property | Value | Notes |
|---|---|---|
| Typical storage temperature | -20 °C or below | Desiccated solid; protect from light |
| Solubility | Soluble in water | Forms acidic solutions |
| Typical analytical method | LC-MS/MS | High specificity for thiols |
| Detection wavelength | 210–220 nm | For HPLC-UV of underivatized glutathione |
| Common synonyms | GSH; reduced glutathione | GSH refers to the reduced form |
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.
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.
Glutathione is most stable as a dry powder stored cool and dry, but its thiol group is readily oxidized in solution. Aqueous preparations at neutral or alkaline pH lose GSH faster because the thiolate form reacts with dissolved oxygen and metal ions. Acidic conditions, chelating agents, and oxygen exclusion can slow oxidation, while repeated freeze-thaw cycles promote degradation. Light exposure and trace metals also contribute to loss. Laboratories typically validate stability for their own matrices because degradation rates depend on pH, temperature, concentration, and container materials.
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.
{\displaystyle {\begin{aligned}z:\ &\rho \left({\partial _{t}u_{z}}+u_{r}{\partial _{r}u_{z}}+{\frac {u_{\varphi }}{r}}{\partial _{\varphi }u_{z}}+u_{z}{\partial _{z}u_{z}}\right)\\&\quad =-{\partial _{z}p}\\&\qquad +\mu \left({\frac {1}{r}}\partial _{r}\left(r{\partial _{r}u_{z}}\right)+{\frac {1}{r^{2}}}{\partial _{\varphi }^{2}u_{z}}+{\partial _{z}^{2}u_{z}}\right)\\&\qquad +{\frac {1}{3}}\mu \partial _{z}\left({\frac {1}{r}}{\partial _{r}\left(ru_{r}\right)}+{\frac {1}{r}}{\partial _{\varphi }u_{\varphi }}+{\partial _{z}u_{z}}\right)\\&\qquad +\rho g_{z}.\end{aligned}}}
Afghanistan: The Foreign Ministry stipulated that the Assad regime was the "cause of war and instability" and congratulated Tahrir al-Sham. Canada: Prime Minister Justin Trudeau said that the fall of the Assad dictatorship "ends decades of brutal oppression" and said that Canada is monitoring the transition closely. China: The Foreign Ministry stated that it "is closely following the development of the situation in Syria and hopes that Syria returns to stability as soon as possible" and urged all parties to ensure the safety of Chinese citizens in Syria. European Union: EU foreign policy chief Kaja Kallas called the end of Assad's rule a "positive and long-awaited development" and stated she was in close contact with regional ministers. She emphasized that rebuilding Syria would be "long and complicated". France: President Emmanuel Macron commented on social media: "The barbaric state has fallen. At last. I pay tribute to the Syrian people, to their courage, to their patience." He added that France would remain committed to security in the Middle East. Germany: Foreign Minister Annalena Baerbock described the end of the Assad regime as "a big relief for millions of people in Syria" while warning that "the country must not fall into the hands of other radicals". Indonesia: The Ministry of Foreign Affairs reported that the Embassy of Indonesia in Damascus attacked by stray bullets from the Syrian Opposition Forces and causing minor damages to the building on 9 December 2024. No casualties and injured reported from the attack.
Oclacitinib, sold under the brand name Apoquel among others, is a veterinary medication used in the control of atopic dermatitis and pruritus from allergic dermatitis in dogs at least 12 months of age. Chemically, it is a synthetic cyclohexylamino-pyrrolopyrimidine Janus kinase inhibitor (JAK inhibitor) that is relatively selective for JAK1. It inhibits signal transduction when the JAK is activated and thereby helps downregulate expression of inflammatory cytokine. Oclacitinib was approved for use in the United States in 2013 and in the European Union in 2023. A flavored chewable form was approved for use in the United States in 2023.
In response, the Malian army mobilised and launched an offensive, recapturing Anéfis after clashes with the MNLA on June 4, 2013. Amid fears of escalation, the French military intervened to de-escalate tensions and prevent further clashes in the lead-up to the presidential elections.
Sources: en.wikipedia.org
A report by the Public Accounts Committee finds that only 10% of the money promised to reduce inequality under the Levelling Up scheme had actually been spent. The Animal Welfare (Import of Dogs, Cats and Ferrets) Bill, introduced as a private member's bill, passes its first reading in the House of Commons after securing the backing of the UK government. The bill aims to ban the import of puppies, kittens and ferrets under the age of six months into the UK. Apple agrees to pay a £385m settlement on a lawsuit led by Norfolk County Council, which was started over allegations Apple CEO Tim Cook defrauded shareholders in a pension company administered by the Council by covering up lower demand for iPhones in China. 16 March – Vaughan Gething is elected to lead Welsh Labour, and will become First Minister of Wales. He will be Wales's first black leader, and the first black person to lead a country in Europe. With Gething's win it means that three of the four governments in the UK will have non-white leaders. A group calling itself the South Devon Primary, which aims to unseat Conservative MPs in South Devon at the next election, chooses Liberal Democrat Caroline Voaden as a candidate for one of its constituencies. Traditional Unionist Voice leader Jim Allister announces a formal "partnership" with Reform UK at the next general election. 17 March – Transport Secretary Mark Harper tells the BBC that the Conservative Party welcomes members "whatever their race".
In a 2017 interview with the journalist Claudio Dantas Sequeira from O Antagonista, Bolsonaro said that his views are directly aligned with the centrist to right-wing United States citizens' views on gun ownership, abortion, gender politics, and trade, despite the "left-leaning media frenzy" against him. He reiterated that he intends to reverse some disarmament laws, improve public security, and also improve trade ties with the United States, which he said were broken during Luiz Inácio Lula da Silva's and Dilma Rousseff's administrations. During his long political career, Bolsonaro expressed views regarded as being far-right. He has made statements that some people considered insulting, homophobic, violence-inciting, misogynistic, sexist, racist, or anti-refugee. Other controversial political stances expressed by Bolsonaro have been the defence of the death penalty, which is banned under the Constitution of Brazil of 1988, and of radical interventionism in Brazil by the military, along with an imposition of a Brazilian military government. The journalist Glenn Greenwald called Bolsonaro "the most misogynistic, hateful elected official in the democratic world". News.com.au wondered whether Bolsonaro was "the world's most repulsive politician". The news magazine The Economist referred to him as a "radical", "religious nationalist", a "right-wing demagogue", and "apologist of dictators".
The chemistry of calcium is that of a typical heavy alkaline earth metal. For example, calcium spontaneously reacts with water more quickly than magnesium but less quickly than strontium to produce calcium hydroxide and hydrogen gas. It also reacts with the oxygen and nitrogen in air to form a mixture of calcium oxide and calcium nitride. When finely divided, it spontaneously burns in air to produce the nitride. Bulk calcium is less reactive: it quickly forms a hydration coating in moist air, but below 30% relative humidity it may be stored indefinitely at room temperature. Besides the simple oxide CaO, calcium peroxide, CaO2, can be made by direct oxidation of calcium metal under a high pressure of oxygen, and there is some evidence for a yellow superoxide Ca(O2)2.Calcium hydroxide, Ca(OH)2, is a strong base, though not as strong as the hydroxides of strontium, barium or the alkali metals. All four dihalides of calcium are known. Calcium carbonate (CaCO3) and calcium sulfate (CaSO4) are particularly abundant minerals. Like strontium and barium, as well as the alkali metals and the divalent lanthanides europium and ytterbium, calcium metal dissolves directly in liquid ammonia to give a dark blue solution. Due to the large size of the calcium ion (Ca2+), high coordination numbers are common, up to 24 in some intermetallic compounds such as CaZn13. Calcium is readily complexed by oxygen chelates such as EDTA and polyphosphates, which are useful in analytic chemistry and removing calcium ions from hard water.
Sources: en.wikipedia.org
== Systemic effects == An infectious organism can escape the confines of the immediate tissue via the circulatory system or lymphatic system, where it may spread to other parts of the body. If an organism is not contained by the actions of acute inflammation, it may gain access to the lymphatic system via nearby lymph vessels. An infection of the lymph vessels is known as lymphangitis, and infection of a lymph node is known as lymphadenitis. When lymph nodes cannot destroy all pathogens, the infection spreads further. A pathogen can gain access to the bloodstream through lymphatic drainage into the circulatory system. When inflammation overwhelms the host, systemic inflammatory response syndrome is diagnosed. When it is due to infection, the term sepsis is applied, with the terms bacteremia being applied specifically for bacterial sepsis and viremia specifically to viral sepsis. Vasodilation and organ dysfunction are serious problems associated with widespread infection that may lead to septic shock and death.
Naval Postgraduate School academic Edward A. Olsen, British politician David Alton, York University professor Hyun Ok Park, and University of Southern California professor David C. Kang used the term to refer to tensions between North Korea and South Korea, which have been divided since the end of World War II in 1945. They interchangeably called it the "Korean Cold War". In August 2019, the North Korean government said that further US–South Korean military cooperation would prompt North Korea to "trigger a new cold war on the Korean Peninsula and in the region." China's Defense Ministry spokesman Geng Yansheng, The Diplomat editor Shannon Tiezzi, and The Guardian columnist Simon Tisdall used the term to refer to tensions between China and Japan.
=== Milk pasteurization by microwave === When storage conditions of milk are controlled, milk tends to have a very good flavor. However, oxidized flavor is a problem that affects the taste and safety of milk in a negative way. To prevent the growth of pathogenic bacteria and extend the shelf life of milk, pasteurization processes were developed. Microwaved milk has been studied and developed to prevent oxidation compared to traditional pasteurized milk methods, and it has been concluded that milk has a better quality when it has microwaved milk pasteurization.
=== Differential diagnosis === IBM is often initially misdiagnosed as polymyositis. A course of prednisone is typically completed with no improvement and eventually, sIBM is confirmed. sIBM weakness comes on over months or years and progresses steadily, whereas polymyositis has an onset of weeks or months. Muscular dystrophy (e.g., limb girdle muscular dystrophy) must be considered as well. sIBM can be mistaken for physical deconditioning. Hereditary myopathies can mimic sIBM, both in signs and symptoms and in the appearance of muscle biopsies. A small percentage of those initially diagnosed with sIBM are later found to have pathogenic mutations in the genes VCP and SQSTM1, which are known to cause hIBM. IBM has a distinctive pattern of muscle involvement that distinguishes it among inflammatory myopathies. Characteristic of IBM is weakness of finger flexion, knee extension, and ankle dorsiflexion. Other inflammatory myopathies cause a proximal muscle weakness pattern, such as weakness of hip flexion, abduction, and extension, as well as shoulder abduction. IBM and other inflammatory myopathies both cause bicep/tricep weakness.
Sources: en.wikipedia.org
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.
Blood contains glutathione, but concentrations differ between plasma and red blood cells. Careful separation and rapid processing are needed because ex vivo oxidation and hemolysis can alter results.
An enzymatic recycling assay uses glutathione reductase and a thiol-reactive reagent to generate a signal proportional to total glutathione. It is convenient for many samples but may not distinguish reduced and oxidized forms without additional steps.
Common methods include spectrophotometric enzyme cycling assays, HPLC with UV or fluorescence detection, and LC-MS/MS. Detection often requires derivatization because glutathione lacks a strong chromophore. Method choice depends on the sample type and the required sensitivity.