This is a working overview of HPLC, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-05-01. Anything still debated is marked as such rather than presented as settled.
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.
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.
For solid glutathione reagents, storage at low temperature and protection from moisture and light are typical precautions. Aqueous solutions can oxidize over time, and pH affects stability; alkaline conditions generally promote thiol oxidation. Some protocols prepare fresh solutions, while others use antioxidants or chelators to limit metal-catalyzed oxidation. Purity and counterion content can vary among commercial preparations, affecting concentration calculations. Certificates of analysis and validated assays help verify identity and purity.
Measuring glutathione in biological samples requires attention to oxidation, because GSH can convert to GSSG after sample collection. Blood and plasma samples are often treated with acid or alkylating agents to preserve the reduced form. Without stabilization, apparent GSH concentrations can fall while GSSG rises. Differences in sample type, handling delay, and deproteinization method can produce results that are not comparable across studies. Reporting preanalytical details is therefore important for interpreting findings.
| 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 |
Glutathione serves as a cofactor for several enzymes, including glutathione peroxidase and glutathione S-transferase. These enzymes help reduce hydrogen peroxide and lipid peroxides, and they conjugate reactive electrophiles for excretion. The molecule also acts as a reservoir for cysteine, an amino acid that is prone to oxidation. In addition, glutathione participates in the metabolism of nitric oxide, leukotrienes, and prostaglandins. Its roles extend to cell signaling, apoptosis, and the regulation of protein function through S-glutathionylation.
Glutathione is a tripeptide composed of glutamate, cysteine, and glycine, and it is the most abundant non-protein thiol in most living cells. The reduced form, GSH, carries a sulfhydryl group that can donate electrons, while the oxidized form, GSSG, forms when two GSH molecules link via a disulfide bond. The balance between these two forms helps define the cellular redox environment, and their ratio is often used as an indicator of oxidative stress. Because the sulfhydryl group is reactive, glutathione participates in many cellular processes, including detoxification and protein regulation.
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.
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 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.
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.
In living systems, glutathione occurs in millimolar concentrations in many cell types, while extracellular levels are generally much lower. The liver holds a substantial share of the body's total pool, and the molecule participates in reduction, detoxification, and amino acid transport. It also serves as a cofactor for enzymes such as glutathione peroxidase and glutathione S-transferase. Because the cysteine residue supplies a reactive thiol, glutathione can donate electrons and become oxidized. Cells regenerate reduced glutathione through glutathione reductase using NADPH.
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.
The availability of furikake in Japan increased starting shortly after September 1948, when Nissin Foods began to manufacture it on a large scale to address pervasive malnourishment. The product was commercialized on the basis that it provided a good source of protein and calcium. Furikake was made widely available as it was dispensed to those serving in the Japanese military starting in World War I. The term furikake was used generically to describe the product starting in 1959 with the formation of the National Furikake Association. Since 1959, furikake products are usually differentiated by their particular ingredients, such as salmon furikake and sesame-and-salt furikake. In the same year, Marumiya Foods developed "Noritama," a sweetened egg added to Kore Wa Umai which became popular as furikake for children. In 1963, Noritama with a sticker of 8 Man became explosively popular, and furikake was transformed from a luxury food for adults to a popular food for children. In 1970, Mishima Shokuhin marketed a new furikake, made by reusing the red shiso used to color pickled plums, under the product name Yukari. The name comes from the desire to create a connection ("縁" (yukari) in Japanese) with customers. In the 1980s, furikake became strongly associated with children's food, and its use rapidly declined after the age of 12. In 1989, Nagatanien began selling "furikake for adults" using ingredients with a luxurious taste and pungent flavor. The initial varieties were "Salmon," "Bonito," and "Wasabi."
Ultraviolet radiation (UV; sometimes called ultraviolet light) is electromagnetic radiation of wavelengths of 100–400 nanometers, shorter than that of visible light, but longer than vacuum ultraviolet and extreme ultraviolet, radiation bands that overlaps UV but shares some properties with soft X-rays. UV radiation is present in sunlight and constitutes about 10% of the total electromagnetic radiation output from the Sun. It is also produced by electric arcs, Cherenkov radiation, and specialized lights, such as mercury-vapor lamps, tanning lamps, and black lights. The photons of ultraviolet have greater energy than those of visible light, from about 3.1 to 12 electron volts, around the minimum energy required to ionize atoms. Although long-wavelength ultraviolet is not considered an ionizing radiation because its photons lack sufficient energy, it can induce chemical reactions and cause many substances to glow or fluoresce. Many practical applications, including chemical and biological effects, are derived from the way that UV radiation can interact with organic molecules. These interactions can involve exciting orbital electrons to higher energy states in molecules potentially breaking chemical bonds. In contrast, the main effect of longer wavelength radiation is to excite vibrational or rotational states of these molecules, increasing their temperature. UV damages DNA and sterilizes surfaces with which it comes into contact. For humans, suntan and sunburn are familiar effects of exposure of the skin to UV, along with an increased risk of skin cancer.
A link between the sympathetic nervous system and the lungs was shown in 1887 when Grossman showed that stimulation of cardiac accelerator nerves reversed muscarine-induced airway constriction. In experiments in the dog, where the sympathetic chain was cut at the level of the diaphragm, Jackson showed that there was no direct sympathetic innervation to the lung, but bronchoconstriction was reversed by the release of adrenaline from the adrenal medulla. An increased incidence of asthma has not been reported for adrenalectomized patients; those with a predisposition to asthma will have some protection from airway hyper-reactivity from their corticosteroid replacement therapy. Exercise induces progressive airway dilation in normal subjects that correlates with workload and is not prevented by beta-blockade. The progressive airway dilation with increasing exercise is mediated by a progressive reduction in resting vagal tone. Beta blockade with propranolol causes a rebound in airway resistance after exercise in normal subjects over the same time course as the bronchoconstriction seen with exercise-induced asthma. The reduction in airway resistance during exercise reduces the work of breathing.
After oral administration, bupropion is rapidly and completely absorbed, reaching the peak blood plasma concentration after 1.5 hours (tmax). Sustained-release (SR) and extended-release (XL) formulations have been designed to slow down absorption, resulting in tmax of 3 hours and 5 hours, respectively. Absolute bioavailability of bupropion is unknown but is presumed to be low, at 5–20%, due to the first-pass metabolism. As for the relative bioavailability of the formulations, the XL formulation has lower bioavailability (68%) compared to the SR formulation and immediate release bupropion. Bupropion is metabolized in the body by a variety of pathways. The oxidative pathways are by cytochrome P450 isoenzymes CYP2B6 leading to R,R- and S,S-hydroxybupropion and, to a lesser degree, CYP2C19 leading to 4'-hydroxybupropion. The reductive pathways are by 11β-hydroxysteroid dehydrogenase type 1 in the liver and AKR7A2/AKR7A3 in the intestine leading to threo-hydrobupropion and by yet unknown enzyme leading to erythro-hydrobupropion. The metabolism of bupropion is highly variable: the effective doses of bupropion received by persons who ingest the same amount of the drug may differ by as much as 5.5 times (with a half-life of 12–30 hours), while the effective doses of hydroxybupropion may differ by as much as 7.5 times (with a half-life of 15–25 hours). Based on this, some researchers have advocated monitoring of the blood level of bupropion and hydroxybupropion.
== Other salvage pathways == L-methionine salvage is the pathway that regenerates methionine from its downstream products. A version of the pathway uses methylthioadenosine (MTA), forming the so-called MTA cycle with its synthesizing reaction. This sulphur-recycling action is found in humans, and seems to be universal among aerobic life. Nicotinate salvage is the process of regenerating nicotinamide adenine dinucleotide from nicotinic acid. This pathway is important for controlling the level of oxidative stress in cells. The human gene NAPRT encodes the main enzyme in the pathway. Cancer cells, which have increased NAD requirements, tend to upregulate the pathway. Salvage pathways also exist for ceramide, cobalamin, cell wall components, and tetrahydrobiopterin in various organisms.
Sources: en.wikipedia.org
On television, d'Abo played Ta'Ra, an alien medical officer in the science fiction miniseries Something Is Out There (1988), which was followed by a six-episode NBC mini-series of the same name, and she played Anne Summerton in the TV adaptation of Jeffrey Archer's novel Not a Penny More, Not a Penny Less (1990) directed by Clive Donner. D'Abo had a supporting role as a pretentious stained-glass artist in the low-budget British comedy Leon the Pig Farmer (1992). She appeared in the 1994 film The Browning Version and starred in Timelock (1996). D'Abo has had roles in various low-budget, straight-to-video action, horror and fantasy films such as Tomcat: Dangerous Desires (1992), as well as guest roles on television shows Tales from the Crypt (1993), Red Shoe Diaries (1992) and Murder, She Wrote (1992). She reunited with her James Bond director John Glen for a guest-starring role on the television series Space Precinct and for the feature film The Point Men (2001). Glen later said that he cast her in three different projects was because she was one of his favourite actresses. She played the mother of Lara (played by Keira Knightley) in the television miniseries version of Doctor Zhivago (2002), and she was Queen Hecuba in the Emmy-nominated miniseries Helen of Troy (2003). She had a small role in the French film L'Enfer (Hell, 2005), directed by Danis Tanovic whose stars included fellow Bond Girl Carole Bouquet. D'Abo and John Cork wrote the book Bond Girls Are Forever, published in 2002, which is a tribute to the women who have played the role of a Bond girl.
Angelica sinensis, commonly known as dong quai (simplified Chinese: 当归; traditional Chinese: 當歸; pinyin: dāngguī; Jyutping: dong1 gwai1; Pe̍h-ōe-jī: tong-kui) or female ginseng, is a herb belonging to the family Apiaceae, indigenous to China. A. sinensis grows in cool high altitude mountains in East Asia. There is no scientific evidence that A. sinensis is effective for any medicinal purpose.
=== Cardiovascular disease === The primary health risk identified for trans fat consumption is an elevated risk of coronary artery disease (CAD). A 1994 study estimated that over 30,000 cardiac deaths per year in the United States are attributable to the consumption of trans fats. By 2006 upper estimates of 100,000 deaths were suggested. Major evidence for the effect of trans fat on CAD comes from the Nurses' Health Study – a cohort study that has been following 120,000 female nurses since its inception in 1976. In this study, Hu and colleagues analyzed data from 900 coronary events from the study's population during 14 years of followup. He determined that a nurse's CAD risk roughly doubled (relative risk of 1.93, CI: 1.43 to 2.61) for each 2% increase in trans fat calories consumed (instead of carbohydrate calories). By contrast, for each 5% increase in saturated fat calories (instead of carbohydrate calories) there was a 17% increase in risk (relative risk of 1.17, CI: 0.97 to 1.41). "The replacement of saturated fat or trans unsaturated fat by cis (unhydrogenated) unsaturated fats was associated with larger reductions in risk than an isocaloric replacement by carbohydrates." Hu also reports on the benefits of reducing trans fat consumption. Replacing 2% of food energy from trans fat with non-trans unsaturated fats more than halves the risk of CAD (53%). By comparison, replacing a larger 5% of food energy from saturated fat with non-trans unsaturated fats reduces the risk of CAD by 43%.
Kittens require a high-calorie diet that contains more protein than the diet of adult cats. Young orphaned kittens require cat milk every two to four hours, and they need physical stimulation to defecate and urinate. Cat milk replacer is manufactured to feed young kittens because cow's milk does not provide all the necessary nutrients. Human-reared kittens tend to be very affectionate with humans as adults and sometimes more dependent on them than kittens reared by their mothers, but they can also show volatile mood swings and aggression. Depending on the age at which they were orphaned and how long they were without their mothers, these kittens may be severely underweight and can have health problems later in life, such as heart conditions. The compromised immune system of orphaned kittens — due to the absence of antibodies normally found in the mother's milk — can make them especially susceptible to infections, often necessitating antibiotics.
The HTR, a behavioral proxy of psychedelic-like effects, appears to be mediated by activation of intracellularly expressed serotonin 5-HT2A receptors in a population of mPFC neurons that do not also express the serotonin transporter (SERT) and hence cannot be activated by serotonin. In contrast to serotonin, serotonergic psychedelics are more lipophilic than serotonin and are able to readily enter these neurons and activate the serotonin 5-HT2A receptors within them. Artificial expression of the SERT in this population of neurons in animals resulted in a serotonin releasing agent that doesn't normally produce the HTR being able to do so. Although serotonin itself is non-hallucinogenic, at very high concentrations achieved pharmacologically (e.g., injected into the brain or with massive doses of 5-HTP) it can produce psychedelic-like effects in animals by being metabolized by indolethylamine N-methyltransferase (INMT) into more lipophilic N-methylated tryptamines like N-methylserotonin and bufotenin (N,N-dimethylserotonin). In addition to their hallucinogenic effects, serotonergic psychedelics may also produce a variety of other effects, including psychoplastogenic (i.e., neuroplasticity-enhancing), antidepressant, anxiolytic, empathy-enhancing or prosocial effects, anti-obsessional, anti-addictive, anti-inflammatory and immunomodulatory effects, analgesic effects, and/or antimigraine effects.
Sources: en.wikipedia.org
=== Adrenal glands === The fetal adrenal cortex can be identified within four weeks of gestation. The adrenal cortex originates from the thickening of the intermediate mesoderm. At five to six weeks of gestation, the mesonephros differentiates into a tissue known as the genital ridge. The genital ridge produces the steroidogenic cells for both the gonads and the adrenal cortex. The adrenal medulla is derived from ectodermal cells. Cells that will become adrenal tissue move retroperitoneally to the upper portion of the mesonephros. At seven weeks of gestation, the adrenal cells are joined by sympathetic cells that originate from the neural crest to form the adrenal medulla. At the end of the eighth week, the adrenal glands have been encapsulated and have formed a distinct organ above the developing kidneys. At birth, the adrenal glands weigh approximately eight to nine grams (twice that of the adult adrenal glands) and are 0.5% of the total body weight. At 25 weeks, the adult adrenal cortex zone develops and is responsible for the primary synthesis of steroids during the early postnatal weeks.
== Academic career == Broadbent initially trained as an electronic engineer at the University of Canterbury, completing a Bachelor of Engineering degree with Honours (Electrical and Electronic). She worked at companies Transpower, Électricité de Tahiti, and Robotechnology before continuing her education with a graduate Diploma of Arts from Massey University, and Master of Arts and Doctor of Philosophy degrees at the University of Auckland. Her 2002 master's thesis was on the effects of stress, social support and beliefs on wound healing following surgery. Her PhD thesis, completed in 2005, was titled New approaches to the assessment of illness perceptions. Broadbent was promoted to full professor at the University of Auckland in 2019. Broadbent has worked on how robots might help in school situations, both in the classroom and the sick bay, and also how might robots help patients managing chronic lung condition COPD. About 75% of patients in a controlled trial found that having robot assistance at home helped with medication adherence and companionship. Her work on how writing can help recovery from injury and weightloss surgery has been featured in Scientific American Mind, Time magazine, and The Guardian.
=== Hyperglycemia hyperosmolar state (HHS) === hyperosmolar non-ketotic state (HONK) or Hyperglycemia hyperosmolar state (HHS) is an acute complication sharing many symptoms with DKA, but an entirely different origin and different treatment. Oppositely, the prevalence of HHS is common in individuals with T2D. Furthermore, it showcases approximately ten times greater mortality rate than the observed in DKA. Both DKA and HHS occur when insulin becomes less effective, either due to a shortage of insulin secretion ( as in DKA), or lack of proper insulin action (as in HHS). For a person with very high blood glucose levels (usually considered to be above 30 mmol/L (600 mg/dL), that will result in osmotic diuresis, water is osmotically drawn out of cells into the blood and the kidneys eventually begin to dump glucose into the urine. This results in a loss of water (which contains electrolytes and glucose) that will increase blood osmolarity. If the fluid is not replaced, by mouth or intravenously, will ultimately result in dehydration (which in HHS typically becomes worse than DKA). Also causes electrolyte imbalances which are always dangerous. A decline in consciousness levels is primarily attributed to an increase in plasma osmolality. Lethargy may ultimately progress to a coma which is more common in T2D than T1D. HHS, unlike DKA, does not result in significant ketosis and acidosis, or there may be only a very minimal. This is because the presence of a small quantity of insulin suppresses the release of counterregulatory hormones and limits the production of ketones.
It was inspired by the documentary Bond Girls Are Forever, which she produced with Planetgrande, featuring d'Abo and other Bond girls, including Ursula Andress, Honor Blackman, Jill St. John, Maud Adams, Lois Chiles, Judi Dench, Rosamund Pike, Eva Green, Halle Berry, and Carey Lowell. The documentary appeared on the American AMC network in 2002, timed to coincide with the theatrical release of Die Another Day. It was later included as a gift with the purchase of Die Another Day on DVD by some retailers. In 2006, a new version of the documentary, updated to include interviews with cast from Casino Royale (2006) was again aired on the AMC network and later released as a bonus feature on the March 2007 Blu-ray disc and DVD release of Casino Royale. In 2004 she wrote and, with Cabin Creek Films, co-produced the documentary film Bearing Witness, about five female war reporters featuring Marie Colvin and Janine di Giovanni, which Barbara Kopple and Marijana Wotton directed for A&E. The feature documentary premiered at the Tribeca Film Festival. In 2007, she had surgery for a brain hemorrhage; after recovering, she was inspired to meet other people who had similar experiences. She then worked on and produced a 2011 documentary on the topic titled Rupture: A Matter of Life and Death. In 2009, she had a supporting role in the British period fantasy-thriller Dorian Gray. She appeared in the 2014 Indian film Tigers directed by Danis Tanovic, and made her return to the horror genre in 2025 with the British film The Baby in the Basket. D'Abo is signed to Models 1.
A 2017 literature review indicated there are numerous potential carcinogens of colorectal tissue in red meat, particularly those in processed red meat products, such as N-nitroso compounds, polycyclic aromatic hydrocarbons (PAHs), and heterocyclic amines (HCAs). Cooking meat with "high-temperature methods, such as pan frying or grilling directly over an open flame", also causes formation of PAHs and HCAs.
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.
Preanalytical factors such as sample type, time to processing, and stabilization method can change GSH and GSSG amounts. Analytical method and calibration also contribute to variation. Comparing absolute values across studies requires caution.