Everything below concerns HPLC. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2025-12-09. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Solid storage temperature | -20 °C | Desiccated, protected from light |
| Solution stability | Hours to days at neutral pH | Acidic pH and low oxygen slow oxidation |
| Oxidized form | Glutathione disulfide (GSSG) | Formed by thiol oxidation |
| Typical analytical method | LC-MS/MS or enzymatic recycling | Choice depends on matrix and specificity |
| Thiol pKa | Approximately 9.2 | Influences reactivity at physiological pH |
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.
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.
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.
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.
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.
In May 1945, Czechoslovak troops took possession of the borderland. A Czechoslovak administrative commission composed exclusively of Czechs was established. Sudeten Germans were subjected to restrictive measures and conscripted for compulsory labor. On 15 June, however, Beneš called Czechoslovak authorities to order. In July, Czechoslovak representatives addressed the Potsdam Conference (the U.S., Britain and the Soviet Union) and presented plans for a "humane and orderly transfer" of the Sudeten German population. There were substantial exceptions from expulsions that applied to about 244,000 ethnic Germans who were allowed to remain in Czechoslovakia. The following groups of ethnic Germans were not deported:
Studies in biochemistry show that endogenous, bacterial chaperones of curli are capable of briefly interacting with Syn and controlling its aggregation. The clinical and pathological findings support the hypothesis that aSyn disease in PD occurs via a gut-brain pathway. For early diagnosis and early management in the phase of creation and propagation of aSyn, it is therefore of utmost importance to identify pathogenic aSyn in the digestive system, for example, by gastrointestinal tract (GIT) biopsies. According to a growing body of research, intestinal dysbiosis may be a major factor in the development of Parkinson's disease by encouraging intestinal permeability, gastrointestinal inflammation, and the aggregation and spread of asyn. Not just the CNS but other peripheral tissues, such as the GIT, have physiological aSyn expression as well as its phosphorylated variants. As suggested by Borghammer and Van Den Berge (2019), one approach is to recognise the possibility of PD subtypes with various aSyn propagation methods, including either a peripheral nervous system (PNS)-first or a CNS-first route. While the GI tract has been linked to other neurological disorders such autism spectrum disorder, depression, anxiety, and Alzheimer's disease, protein aggregation and/or inflammation in the gut represent a new topic of investigation in synucleinopathies.
In most prokaryotes (archaea, bacteria), a single RNA polymerase species transcribes all types of RNA. RNA polymerase "core" from the bacteria E. coli consists of five subunits: two alpha (α) subunits of 36 kDa, a beta (β) subunit of 150 kDa, a beta prime subunit (β′) of 155 kDa, and a small omega (ω) subunit. A sigma (σ) factor binds to the core, forming the holoenzyme. After transcription starts, the σ factor can unbind and let the core enzyme perform transcription. The core RNA polymerase complex forms a "crab claw" or "clamp-jaw" structure with an internal channel running along the full length. Eukaryotic and archaeal RNA polymerases have a similar core structure and work in a similar manner, although they have many extra subunits. The 2006 Nobel Prize in Chemistry was awarded to Roger D. Kornberg for creating detailed molecular images of RNA polymerase during various stages of the transcription process. All RNAPs contain metal cofactors, in particular zinc and magnesium cations which aid in the transcription process.
Two pharmacological agents intended to prevent scarring in mild idiopathic fibrosis are pirfenidone, which reduced reductions in the 1-year rate of decline in FVC and reduced the decline in distances on the 6-minute walk test, but had no effect on respiratory symptoms, and is nintedanib, which acts as an antifibrotic, mediated through the inhibition of a variety of tyrosine kinase receptors (including platelet-derived growth factor, fibroblast growth factor, and vascular endothelial growth factor). A randomized clinical trial showed it reduced lung-function decline and acute exacerbations. Preclinical studies on monoclonal antibodies that target the pulmonary endothelial aggregation receptor 1 (PEAR1) (which plays a crucial role in fibroblast activation and the progression of fibrosis) have shown promising results in slowing disease progression and improving lung function. Anti-inflammatory agents have only limited success in reducing the fibrotic process. Some other types of fibrosis, such as non-specific interstitial pneumonia, may respond to immunosuppressive therapy such as corticosteroids. But only a minority of patients respond to corticosteroids alone, so additional immunosuppressants, such as cyclophosphamide, azathioprine, methotrexate, penicillamine, and cyclosporine may be used. Colchicine has also been used with limited success. Nerandomilast (Jascayd) was approved for medical use in the United States in October 2025.
== In popular culture == Notes Left Behind, a non-fictional book published in 2009, is about a girl named Elena Desserich. Desserich left hundreds of notes to her family before she died of DIPG at age 6.
Sources: en.wikipedia.org
Official diplomatic recognition by other countries was key for Rhodesia as it was the only way it could regain the international legitimacy it had lost through UDI. Recognition by the UK itself through a bilateral settlement would be the "first prize", in Smith's words, as it would end sanctions and constitutional ambiguity and make foreign acceptance, at least in the West, far more likely. Considering their country a potentially important player in the Cold War as a "bastion against communism" in southern Africa, the RF posited that some Western countries might recognise UDI even without a prior Anglo-Rhodesian rapprochement. Specifically, it expected diplomatic recognition from South Africa and Portugal, and thought that France might recognise Rhodesia to annoy Britain and create a precedent for an independent Quebec. But although South Africa and Portugal gave economic, military and limited political support to the post-UDI government (as did France and other nations, to a lesser extent), neither they nor any other country ever recognised Rhodesia as a de jure independent state. Rhodesia's unsuccessful attempts to win Western support and recognition included offers to the US government in 1966 and 1967, ignored by Lyndon B. Johnson's administration, to provide Rhodesian troops to fight alongside the Americans and other anti-communist forces in Vietnam.
In response to Estadão, the Ministry of Communications released a statement with its position regarding the trip. The statement affirms that the minister had official commitments during the trip to the state of São Paulo:The minister fulfilled an official agenda on 26 and 27 January, participating in meetings with the operator Claro, where the company's investment plan in the country was presented; [he also participated in] a technical meeting with the team of the regional office of the affiliated Telebrás; a meeting with the regional manager of the affiliated agency Anatel; and [participated in] a visit and meeting with the BYD group in SP.In an exclusive interview with journalist Reinaldo Azevedo on BandNews FM, Lula declared:I tried this week to talk with Juscelino; minister Juscelino is traveling, he is abroad on ministry business discussing at the telecommunications meeting. I have already asked minister Rui Costa to summon him for Monday so that we can have a conversation because he has the right to prove his innocence, but if he cannot prove his innocence he cannot remain in the government. I guarantee everyone the presumption of innocence.Pressured by allies and opponents regarding the permanence or dismissal of the minister, the president met with Juscelino on 6 March to demand explanations from him regarding the accusations. After the meeting, Lula decided to keep the minister. On his official Twitter profile, Juscelino published:I have just left the Palácio do Planalto, where I had a very positive meeting with president Lula.
=== Russia === Russia re-elected Vladimir Putin as the president in 2012 Russian presidential election. The election was marred by claims of fraud, contributing to the 2011–2013 Russian protests. Under Putin, Russia engaged in a more aggressive foreign policy, with the 2014 Annexation of Crimea and intervention in Ukraine following the 2014 Ukrainian revolution, the 2015 intervention in the Syrian Civil War, and interference in the 2016 United States elections.
Radioactive primordial nuclides found in the Earth are residues from ancient supernova explosions that occurred before the formation of the Solar System. They are the fraction of radionuclides that survived from that time, through the formation of the primordial solar nebula, through planet accretion, and up to the present time. The naturally occurring short-lived radiogenic radionuclides found in today's rocks, are the daughters of those radioactive primordial nuclides. Another minor source of naturally occurring radioactive nuclides are cosmogenic nuclides, that are formed by cosmic ray bombardment of material in the Earth's atmosphere or crust. The decay of the radionuclides in rocks of the Earth's mantle and crust contribute significantly to Earth's internal heat budget.
The lambda particle is a type of subatomic particle in subatomic particle physics. Lambda is the set of logical axioms in the axiomatic method of logical deduction in first-order logic. Uppercase Lambda is often used as a stylized form of uppercase A, especially in science fiction. There is a poetical allusion to the use of Lambda as a shield blazon by the Spartans. Lambda is the von Mangoldt function in mathematical number theory. Lambda denotes the de Bruijn–Newman constant which is closely connected with Riemann's hypothesis. In statistics, lambda is used for the likelihood ratio. In statistics, Wilks's lambda is used in multivariate analysis of variance (MANOVA analysis) to compare group means on a combination of dependent variables. In the spectral decomposition of matrices, lambda indicates the diagonal matrix of the eigenvalues of the matrix. In computer science, lambda is the time window over which a process is observed for determining the working memory set for a digital computer's virtual memory management. In astrophysics, lambda represents the likelihood that a small body will encounter a planet or a dwarf planet leading to a deflection of a significant magnitude. An object with a large value of lambda is expected to have cleared its neighbourhood, satisfying the current definition of a planet. In crystal optics, lambda is used to represent a lattice period. In electrochemistry, lambda denotes the "equivalent conductance" of an electrolyte solution.
Sources: en.wikipedia.org
(2026) compare the morphology of the femoral neck in members of the genera Acratocnus, Megalocnus, Neocnus and Parocnus with those of extant xenarthrans, and reconstruct the locomotor behaviors of the studied extinct sloths, supporting the interpretation of Parocnus as primarily terrestrial. Feola et al. (2026) revise the fossil record of ground sloth footprints, and name new ichnotaxa Megatherichnidae, Falciformichnus and Megatherichnum agilis.
It's a little sarcastic, but it's pretty much about dealing with your mortality and life. Everybody's going to die someday. Instead of being afraid of it, that's the way it is: so enjoy the time you've got. Live as much as you can, have as much fun as possible. Face your fear and live. I had family members die at a fairly early age; so I've always had kind of a phobia about it. Death freaks me out. I think it freaks a lot of people out. It's the end of life, depending on your views. It's a pretty scary thing. "Them Bones" is trying to put that thought to rest. Use what you have left, and use it well." Cantrell was inspired to write "Dam That River" after a fight he had with Sean Kinney, in which Kinney broke a coffee table over his head. The lyrics to "Rain When I Die" were written by Cantrell and Staley about their respective girlfriends. "Sickman" came together after Staley asked Cantrell to "write him the sickest tune, the sickest, darkest, most fucked up and heaviest thing [Cantrell] could write." "Rooster" was written by Cantrell for his father, Jerry Cantrell Sr., who served in the Vietnam War and his childhood nickname was "Rooster". Cantrell described the song as "the start of the healing process between my Dad and I from all that damage that Vietnam caused." Discussing the title track "Dirt", Cantrell stated that "the words Layne put to it were so heavy, I've never given him something and not thought it was gonna be the most bad-assed thing I was going to hear." Staley said he wrote the song "to a certain person who basically buried my ass".
A submarine (often shortened to sub) is a watercraft capable of independent operation underwater. (It differs from a submersible, which has more limited underwater capability.) The term "submarine" is also sometimes used historically or informally to refer to remotely operated vehicles and robots, or to medium-sized or smaller vessels (such as the midget submarine and the wet sub). Submarines are referred to as boats rather than ships regardless of their size. Although experimental submarines had been built earlier, submarine design took off during the 19th century, and submarines were adopted by several navies. They were first used widely during World War I (1914–1918), and are now used in many navies, large and small. Their military uses include: attacking enemy surface ships (merchant and military) or other submarines; aircraft carrier protection; blockade running; nuclear deterrence; stealth operations in denied areas when gathering intelligence and doing reconnaissance; denying or influencing enemy movements; conventional land attacks (for example, launching a cruise missile); and covert insertion of frogmen or special forces. Their civilian uses include: marine science; salvage; exploration; and facility inspection and maintenance. Submarines can be modified for specialized functions such as search-and-rescue missions and undersea cable repair. They are also used in the tourism industry and in undersea archaeology. Modern deep-diving submarines derive from the bathyscaphe, which evolved from the diving bell.
Screening is used to find the apparent affinities of heterologous proteins displayed on the bacterial cell surface for target proteins. This method is usually combined with FACS, and the addition of a non-fluorescent target protein competitor is beneficial to obtaining more accurate binding affinities. Adding a competitor reduces the chance of target proteins rebinding, which would render the binding affinity less accurate. Cyclic peptides can be successfully displayed on bacterial cell surface. By DNA randomization millions of cyclic peptides displayed on cell surface can be screened against a protein target using high-throughput FACS. Antibody epitope mapping is used to find the specificity of an antibody. The epitope (antibody binding site of antigens) is expressed on the bacterial cell surface by expressing a region of the gene encoding the antigen. Flow cytometry with fluorescently-labelled antibodies is used to detect the amount of antibody binding to epitope.
They are all much shorter-lived than 41Ca; the most stable are 45Ca (half-life 163 days) and 47Ca (half-life 4.54 days). Isotopes lighter than 42Ca usually undergo beta plus decay to isotopes of potassium, and those heavier than 44Ca usually undergo beta minus decay to scandium; though near the nuclear drip lines, proton emission and neutron emission begin to be significant decay modes as well. Like other elements, a variety of processes alter the relative abundance of calcium isotopes. The best studied of these processes is the mass-dependent fractionation of calcium isotopes that accompanies the precipitation of calcium minerals such as calcite, aragonite and apatite from solution. Lighter isotopes are preferentially incorporated into these minerals, leaving the surrounding solution enriched in heavier isotopes at a magnitude of roughly 0.025% per atomic mass unit (amu) at room temperature. Mass-dependent differences in calcium isotope composition are conventionally expressed by the ratio of two isotopes (usually 44Ca/40Ca) in a sample compared to the same ratio in a standard reference material. 44Ca/40Ca varies by about 1–2‰ among organisms on Earth.
Sources: en.wikipedia.org
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.
Acidification lowers pH and slows thiol oxidation during handling. It also helps precipitate proteins that could interfere with detection. Typical choices include metaphosphoric acid and sulfosalicylic acid.
Dissolved oxygen reacts with the thiol group, forming glutathione disulfide. Neutral and alkaline conditions generally increase the oxidation rate. Light, metal ions, and repeated freezing and thawing can also reduce stability.
Common methods include enzymatic recycling assays, liquid chromatography, and mass spectrometry. Many protocols separate reduced glutathione from its oxidized disulfide form before detection.