Everything below concerns liquid chromatography. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2026-05-29. Numbers and descriptions here follow the published literature rather than marketing material.
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.
Common analytical approaches include enzymatic recycling assays, high-performance liquid chromatography, and mass spectrometry. The enzymatic recycling assay uses glutathione reductase and a colorimetric or fluorometric reagent to amplify signal, which gives good sensitivity for total glutathione. Chromatographic methods can separate GSH from GSSG and related thiols, while mass spectrometry offers structural confirmation and multiplexing. Each approach has different requirements for calibration, internal standards, and validation. No single method captures every form of glutathione in every matrix.
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 typically starts with rapid acid extraction to prevent oxidation and enzymatic degradation. Common methods include enzymatic recycling assays, high-performance liquid chromatography, and liquid chromatography coupled with mass spectrometry. The recycling assay uses glutathione reductase and a thiol-reactive colorimetric or fluorescent reagent, measuring total glutathione after converting disulfide forms. Chromatographic methods can separate reduced and oxidized forms, which helps when the redox ratio is the target. Choice of method affects sensitivity, specificity, and the amount of sample needed.
Samples for glutathione analysis require careful handling because the compound oxidizes readily and can be consumed by enzymes after collection. Blood is often treated with acid or thiol-blocking agents soon after draw, and plasma should be separated quickly from red blood cells. Tissues are usually snap-frozen or extracted immediately. Aqueous solutions of glutathione are less stable than dry powder and degrade faster at neutral or alkaline pH, in light, or with dissolved oxygen. Repeated freeze-thaw cycles also reduce reliability.
Quality control for glutathione materials checks identity, assay, purity, water content, and disulfide content. Commercial products vary from research-grade powder to dietary supplements, and labels may not distinguish reduced from oxidized forms. In the United States, oral glutathione is commonly sold as a dietary supplement rather than an approved drug, while injectable forms fall under different rules and may require a prescription. Regulatory status differs by country. Analytical certificates, when available, help verify what a material contains, but independent testing remains important for interpretation.
| Property | Value | Notes |
|---|---|---|
| Typical storage temperature | -20 °C or below | For solid reagent and frozen aliquots; protect from moisture and light. |
| Common analytical method | HPLC with UV or fluorescence detection | Separates GSH and GSSG after derivatization or direct detection. |
| Alternative method | LC-MS/MS | Provides high specificity and can quantify multiple thiols. |
| Total glutathione assay | Enzymatic recycling | Uses glutathione reductase and a chromogen or fluorogen. |
| Key stability risk | Oxidation to GSSG | Air, light, and trace metals promote conversion. |
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.
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.
==== Absorption ==== Modafinil is readily absorbed with oral administration. The oral bioavailability of modafinil is unknown. No value is established because modafinil is water-insoluble and cannot be administered intravenously. However, based on excretion studies, at least 40 to 65% of a dose of modafinil is absorbed. The pharmacokinetics of modafinil are linear or dose-proportional over a range of 200 to 800 mg orally. The time to peak levels of modafinil is typically 2 to 4 hours. Food slightly slows the absorption of modafinil, by 0.5 to 1 hour, but does not affect the total area under the curve (AUC). Modafinil reached steady-state levels after 2 to 4 days of once-daily administration. There is 1.5-fold accumulation of modafinil with continuous administration. Modafinil and armodafinil show similar peak levels and times to peak levels in directly comparative studies. Due to armodafinil having a longer elimination half-life than esmodafinil however, armodafinil constitutes 90% of modafinil levels at steady state with modafinil therapy.
=== 23 January === The El-Jeili oil refinery caught fire with smoke being seen from Omdurman and Khartoum Bahri. The SAF claimed that the RSF had set fire to the facility, while the RSF claimed that it caught fire due to incendiary barrel bombs dropped by the Sudanese Air Force. Two people were killed by RSF shelling on the Abu Shouk IDP camp. An indefinite strike was launched by employees of the Bashair Hospital in Khartoum after an RSF member opened fire inside the facility the previous day.
In the US, medical residencies traditionally require lengthy hours of their trainees. Early residents literally resided at the hospitals, often working in unpaid positions during their education. During this time, a resident might always be "on call" or share that duty with just one other physician. The American public, and the medical education establishment, recognized that such long hours were counter-productive, since sleep deprivation increases rates of medical errors. This was noted in a landmark study on the effects of sleep deprivation and error rate in an intensive-care unit. The Accreditation Council for Graduate Medical Education (ACGME) has limited the number of work-hours to 80 hours weekly (averaged over 4 weeks), overnight call frequency to no more than one overnight every third day, and 10 hours off between shifts. Still, a review committee may grant exceptions for up to 10%, or a maximum of 88 hours, to individual programs. Until early 2017, duty periods for postgraduate year 1 could not exceed 16 hours per day, while postgraduate year 2 residents and those in subsequent years can have up to a maximum of 24 hours of continuous duty. After early 2017, all years of residents may work up to 24-hour shifts. While these limits are voluntary, adherence has been mandated for the purposes of accreditation, though lack of adherence to hour restrictions is not uncommon.
Sources: en.wikipedia.org
The Gravity Gun is first given to Gordon Freeman by his ally in the anti-Combine resistance, Alyx Vance, after which he uses it as both a weapon and tool. Certain objects in the game world, such as saw blades, can be used as de facto "ammunition", and the Zombie Chopper achievement rewards the player for beating the Ravenholm segment - an abandoned town infested by headcrab zombies - using only the Gravity Gun. Late in the game, Freeman is captured by the Combine and forced to relinquish all his weapons. However, in a sudden plot twist, the Gravity Gun is accidentally supercharged by the energy field meant to destroy it, turning blue and becoming capable of grabbing and throwing living objects, including the Combine themselves. This allows Freeman to escape and defeat the malevolent Doctor Breen.
== Treatment of drug addiction == SCH-221510 might be an option in the treatment of certain drug addictions: it is able to decrease ethanol self-administration and was able to decrease self-administration of remifentanil, a fentanyl analogue, in a study,
== Etymology == The term sponge derives from the Ancient Greek word σπόγγος spóngos. The scientific name Porifera is a neuter plural of the Modern Latin term porifer, which comes from the roots porus meaning "pore, opening", and -fer meaning "bearing or carrying".
As of 2026, there is no cure or effective treatment for CJD. Some of the symptoms, like twitching, can be managed, but otherwise treatment is palliative care. Psychiatric symptoms like anxiety and depression can be treated with sedatives and antidepressants. Myoclonic jerks can be handled with clonazepam or sodium valproate. Opiates can help with pain. Seizures are very uncommon but can nevertheless be treated with antiepileptic drugs. In 2022, results of an early-stage trial of PRN100, a monoclonal antibody against PrP, were reported: the drug appeared safe and reached the brain, but treated patients did not show clearly improved survival compared to historical controls. While not curative, this trial demonstrated the feasibility of immunotherapy for prion disease. In 2025, preclinical research demonstrated that oral, low-dose treatment with the antiretroviral medication efavirenz extended survival and slowed disease progression in a humanized mouse model of sporadic CJD (sCJD). The drug acts as an allosteric activator of the brain-specific cholesterol-metabolizing enzyme CYP46A1. This mechanism promotes brain cholesterol turnover, reduces the neurotoxic accumulation of pathological prion proteins (PrPSc), and alleviates metabolic lipid alterations in the brain.
Sources: en.wikipedia.org
== Medical uses == In the US, gabapentin is indicated for the treatment of postherpetic neuralgia and as an adjunctive therapy in the treatment of partial-onset seizures without secondary generalization in people with epilepsy. Gabapentin is recommended for use in focal seizures and neuropathic pain. Gabapentin is prescribed off-label in the US and the UK, for example, for the treatment of non-neuropathic pain, anxiety disorders, sleep problems and bipolar disorder. In recent years, gabapentin has seen increased use, particularly in the elderly. There is concern regarding gabapentin's off-label use due to the lack of strong scientific evidence for its efficacy in multiple conditions, its proven side effects and its potential for misuse and physical/psychological dependency. Some harms, including nervous system harms, have been underreported in published trials of gabapentin, potentially resulting in the underestimation of harms in guidelines for the use of gabapentin.
Ethylene glycol is first metabolized to glycolaldehyde by alcohol dehydrogenase. Glycolaldehyde then undergoes further oxidation to glycolate, glyoxylate, and oxalate. Glycolate and oxalate are the primary toxins responsible for the metabolic acidosis, and for the renal damage, seen in ethylene glycol poisoning. Methanol is first metabolized to formaldehyde by alcohol dehydrogenase. Formaldehyde then undergoes further oxidation, via formaldehyde dehydrogenase, to become formic acid. Formic acid is the primary toxin responsible for the metabolic acidosis, and for the visual disturbances, associated with methanol poisoning. By competitively inhibiting the first enzyme, alcohol dehydrogenase, in the metabolism of ethylene glycol and methanol, fomepizole slows the production of the toxic metabolites. The slower rate of metabolite production allows the liver to process and excrete the metabolites as they are produced, limiting the accumulation in tissues such as the kidney and eye. As a result, much of the organ damage is avoided.
Under circumstances in which CENPA is lost from a chromosome a fail-safe mechanism has been described in human cells in which CENPB recruits CENPA via a satellite DNA binding domain to repopulate the centromere with CENPA nucleosomes. CENPA interacts directly with the inner kinetochore through proteins including CENPC and CENPN. Through this interaction the microtubules are able to accurately segregate chromosomes during mitosis.
Sources: en.wikipedia.org
Pre-analytical handling, extraction chemistry, and detection method all influence reported glutathione values. Oxidation during sample processing can shift the measured GSH/GSSG ratio. Standardized protocols and reference materials help reduce, but do not eliminate, these differences.
Total glutathione typically refers to the combined amount of reduced glutathione and glutathione disulfide, expressed in glutathione equivalents. Assays that measure total glutathione do not distinguish GSH from GSSG unless a separation step is included. Researchers often pair a total assay with a specific GSSG measurement to estimate the redox ratio.
Glutathione reference standards are generally stored cold, dry, and protected from light. Weighed portions should be prepared promptly and used within validated stability windows. Purity and water content can affect the accuracy of calibration curves.
Common approaches include enzymatic recycling assays, HPLC, and LC-MS/MS. Acid extraction and rapid processing limit oxidation before analysis.