HPLC comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Last reviewed on 2026-05-14. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
Because GSH is central to redox balance, its status is studied in aging, liver disease, neurodegenerative conditions, and metabolic disorders. Observational studies often report lower GSH or higher GSSG in affected tissues, but such associations do not establish that raising glutathione changes disease outcomes. Oral glutathione is digested into amino acids, and whether intact absorption occurs remains debated; precursors such as N-acetylcysteine and cysteine donors are also investigated. Regulatory agencies generally treat glutathione as a dietary supplement, not an approved drug, and clinical claims require evidence from controlled trials.
Glutathione is a small tripeptide composed of glutamate, cysteine, and glycine, with the unusual gamma-glutamyl linkage between glutamate and cysteine. Its cysteine thiol group makes it a major non-enzymatic antioxidant in cells. The reduced form, GSH, predominates in most intracellular compartments, while the oxidized disulfide form, GSSG, is produced when GSH reduces reactive oxygen species. Intracellular concentrations often reach millimolar levels, whereas plasma concentrations are much lower, typically in the low micromolar range. This gradient reflects active synthesis, transport, and consumption rather than passive distribution.
| 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. |
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.
Glutathione supports several cellular processes beyond direct antioxidant action. It serves as a cofactor for glutathione peroxidase and glutathione S-transferase enzymes, which reduce peroxides and conjugate electrophiles, respectively. The molecule also acts as a reservoir of cysteine, an amino acid that can limit protein synthesis and redox signaling. In human nutrition, oral glutathione is sold as a supplement, but how much intact glutathione reaches tissues after ingestion remains an active research question. Clinical claims about supplementation are not uniformly supported by controlled trials.
Glutathione is a small tripeptide built from glutamic acid, cysteine, and glycine. Its peptide bond between glutamate and cysteine involves the gamma-carboxyl group rather than the usual alpha-carboxyl group. This structure gives the molecule a reactive thiol on the cysteine residue. The reduced form, often abbreviated GSH, is the predominant intracellular species in many cell types. Because the thiol can donate electrons, glutathione participates in redox chemistry and in the conjugation of reactive molecules.
Cells synthesize glutathione through two ATP-dependent steps: glutamate-cysteine ligase joins glutamate and cysteine, and glutathione synthetase adds glycine to form the complete tripeptide. Breakdown occurs through gamma-glutamyl transpeptidase and subsequent peptidase reactions, forming the gamma-glutamyl cycle. Within cells, glutathione also forms a disulfide-linked dimer called GSSG when two GSH molecules react. The balance between GSH and GSSG is widely used as an indicator of oxidative conditions, although the ratio can vary by compartment and tissue.
== Medical uses == ACE inhibitors were initially approved for the treatment of hypertension and can be used alone or in combination with other anti-hypertensive medications. Later, they were found useful for other cardiovascular and kidney diseases including:
=== Head and neck cancer === Tobacco smoking is the main risk factor for head and neck cancer. Cigarette smokers have a lifetime increased risk for head and neck cancer that is 5 to 25 times higher than the general population. The person who used to smoke's risk of developing head and neck cancer begins to approach the risk in the general population 15 years after smoking cessation. In addition, people who smoke have a worse prognosis than those who have never smoked. Furthermore, people who continue to smoke after a diagnosis of head and neck cancer have the highest probability of dying compared to those who have never smoked. This effect is seen in patients with HPV-positive head and neck cancer as well. Passive smoking, both at work and at home, also increases the risk of head and neck cancer. Using tobacco together with alcohol is an especially strong risk factor for head and neck cancer, causing 72% of all cases. This rises to 89% when looking specifically at laryngeal cancer. Smokeless tobacco (including products where tobacco is chewed) is also a cause of oral cancer. Cigar and pipe smoking are also important risk factors for oral cancer and have a dose-dependent relationship, with more consumption leading to higher chances of developing cancer. The use of electronic cigarettes may also lead to the development of head and neck cancers due to the substances like propylene glycol, glycerol, nitrosamines, and metals contained therein, which can cause damage to the airways.
=== 22 March === Zelenskyy visited Ukrainian troops fighting in Bakhmut and handed out medals to wounded soldiers. Russia started moving their T-54/55 tanks from a reserve base. These tanks were from the late 1940s and were the oldest tanks still kept in reserve. It is believed by observers that these were likely being moved to the front.
=== Allergy === Molecular diagnostics is increasingly used in allergology, especially for food and respiratory allergy. Conventional diagnosis is based on clinical history, skin-prick testing and measurement of serum allergen-specific IgE to whole allergen extracts. Molecular-based allergy diagnostics, also called component-resolved diagnostics, measures IgE to individual allergen molecules rather than only to extracts. This can help distinguish genuine sensitization from cross-reactivity, refine assessment of clinical risk in some allergies, and support decisions about allergen immunotherapy. Multiplex platforms, such as Allergy Explorer (ALEX), can test IgE reactivity to many allergen extracts and molecular components in a single assay. Precision allergy molecular diagnosis (PAMD®) is a broader diagnostic approach using molecular IgE profiles to guide prognosis, risk assessment and personalized management, although results must be interpreted together with the patient’s clinical history.
For example, dynorphin that is made in magnocellular vasopressin neurons of the supraoptic nucleus is important in the patterning of electrical activity. Dynorphin produced in magnocellular oxytocin neurons is a negative feedback inhibitor of oxytocin secretion. Dynorphin produced in the arcuate nucleus and in orexin neurons of the lateral hypothalamus affects the control of appetite.
Sources: en.wikipedia.org
Keeping the temperatures sufficiently low is accomplished with specially designed containers and dry ice, but dry ice is only allowed in limited quantities on airplanes as the gases released via sublimation may be toxic. In the United States, the Federal Aviation Administration (FAA) limits the amount of dry ice on a Boeing 777-224 to 3,000 lb (1,400 kg), but it temporarily allowed United Airlines to transport up to 15,000 lb (6,800 kg)—nearly 1 million doses—between Brussels and Chicago. The Centers for Disease Control and Prevention (CDC) tasked McKesson Corporation with vaccine distribution in the U.S.; the company handled all major vaccines except Pfizer's. American Airlines, Boeing, and Delta Air Lines are also working to increase dry ice transportation capacity, and American, Delta, and United each operate their own cold storage networks in the US. FedEx and UPS have installed ultra-cold freezers at air cargo hubs in Europe and North America, and UPS can manufacture 1,200 lb (540 kg) of dry ice per hour.
== Etymology == The term tempe is thought to be derived from the Old Javanese tumpi, a whitish food made of fried batter made from sago or rice flour which resembles rempeyek. The historian Denys Lombard also suggests that it could be linked to a later term tape or tapai which means 'fermentation'. In the western world, tempeh rather than tempe is the most common spelling, to emphasise that the final "e" is pronounced. The first known usage of this spelling is in an 1896 German article. Other spellings, such as témpé, were also used, but tempeh has become the standard spelling in English since the 1960s.
==== 2019 ==== The lifespan of Caenorhabditis elegans (free-living nematodes) was increased by 5–6 times (by 400–500%) using simultaneous impact in IIS and TOR pathways. This is equivalent to how a human would live 400–500 years. The study was done by the MDI Biological Laboratory in collaboration with the Buck Institute for Research on Aging and Nanjing University. Scientists at the Mayo Clinic report the first successful use of senolytics, a new class of drug with potential anti-aging benefits, to remove senescent cells from human patients with a kidney disease. By combining doses of lithium, trametinib and rapamycin into a single treatment, researchers extend the lifespan of fruit flies (Drosophila) by 48%. Researchers at Harvard Medical School identify a link between neural activity and human longevity. Neural excitation is linked to shorter life, while suppression of overactivity appears to extend lifespan. Scientists at the Riken Center for Integrative Medical Sciences and Keio University use single-cell RNA analysis to find that supercentenarians have an excess of cytotoxic CD4 T-cells, a type of immune cell. This phenomenon was first demonstrated in mice
== Properties == An Affibody molecule consists of three alpha helices with 58 amino acids and has a molar mass of about 6 kDa. A monoclonal antibody, for comparison, is 150 kDa, and a single-domain antibody, the smallest type of antigen-binding antibody fragment, 12–15 kDa. Affibody molecules have been shown to withstand high temperatures (90 °C (194 °F)) or acidic and alkaline conditions (pH 2.5 or pH 11, respectively). Affibody molecules have ashort plasma half-life because of their small size.While this is advantageous for imaging,as the unbound tracer is rapidly cleared from the bloodstream, a longer plasma half-life is generally preferred for therapeutic applications. One approach to extend the plasma half-life of small molecules, such as affibody molecules,is to link them to an albumin-binding domain (ABD). A highly effective ABD is the 46-amino acid G148-GA3 domain, which is derived from streptococcal protein G, along with its engineered variant ABD035. This version has a strong femtomolar affinity for human serum albumin (HSA) [28]. The ABD can help prolong the serum half-life by forming a complex with serum albumin (SA) in the bloodstream, increasing the size of the complex and preventing it from being filtered by the kidneys. Binders with an affinity of down to sub-nanomolar have been obtained from native library selections, and binders with picomolar affinity have been obtained following affinity maturation. Affibody molecules conjugated to weak electrophiles bind their targets covalently.
=== Welfare === The 2019–20 budget spent $230 million on a new Quincy Veterans Home, and $21 million on the Chicago Veterans Home. In July 2019, Pritzker signed House Bill 3343, creating a food program for the elderly, the disabled, and the homeless. Such individuals may collect their benefits from a private business that has a contract with the Illinois Department of Human Services (IDHS) to provide meals with discounts. This is the state implementation of the federal Supplemental Nutrition Assistance Program (SNAP). The IDHS was to initiate this program no later than January 1, 2020. On July 12, 2026, Pritzker signed HB4456, which expands eligibility for the federal Low-Income Home Energy Assistance Program to households with an annual income below 300% of the federal poverty line, up from 200%. Later that month, his administration announced the Families Receiving Emergency Support for Hunger program, under which the state government would disperse $400 in nutritional assistance to each of over 100,000 people who were kicked off of SNAP between May and July 2026 due to changes to program eligibility administered by the One Big Beautiful Bill Act.
Sources: en.wikipedia.org
== Further reading == Alexander, Mark, and John Sparry. Jump Commander: In Combat with the 82nd Airborne in World War II. Philadelphia: Casemate, 2010. ISBN 1-935149-28-8 OCLC 506253036 Angress, Werner T. Witness to the Storm: A Jewish Journey from Nazi Berlin to the 82nd Airborne, 1920–1945. Durham, NC: Miriam Angress, 2012. ISBN 1-4774-5701-1 OCLC 804824030 Anzuoni, Robert P. I'm the 82nd Airborne Division!: A History of the All American Division in World War II After Action Reports. Atglen, PA : Schiffer Publishing, 2005. ISBN 0-7643-2347-4 OCLC 62555533 Anzuoni, Robert P. The All American: An Illustrated History of the 82nd Airborne Division, 1917 to the Present. Atglen, PA: Schiffer Pub, 2001. ISBN 0-7643-1321-5 OCLC 49935879 Barry, Robert F. Power Pack: The Dominican Republic, 1965–1966. Portsmouth, Va: Messenger, 1965. OCLC 6655474 Baugh, James Emory. From Skies of Blue: My Experiences with the Eighty-Second Airborne During World War II. New York: iUniverse, 2003. ISBN 0-595-74982-8 OCLC 64584040 Breuer, William B. Drop Zone, Sicily: Allied Airborne Strike, July 1943. Novato, CA: Presidio, 1983. ISBN 0-89141-196-8 OCLC 9945654 Burriss, T. Moffatt. Strike and Hold: A Memoir of the 82nd Airborne in World War II. Washington, D.C.: Brassey's, 2000. ISBN 1-57488-258-9 OCLC 43903491 Caraccilo, Dominic J. The Ready Brigade of the 82nd Airborne in Desert Storm: A Combat Memoir by the Headquarters Company Commander. Jefferson, N.C.: McFarland, 1993. ISBN 0-89950-829-4 OCLC 27265069 Carter, Ross S. Those Devils in Baggy Pants. Cutchogue, NY: Buccaneer Books, 1996.
Genera surviving today comprise 56% of the genera in Baltic amber fossils (early Oligocene), and 92% of the genera in Dominican amber fossils (apparently early Miocene). Termites live in colonies and are sometimes called "white ants", but termites are only distantly related to ants. They are the sub-order Isoptera, and together with cockroaches, they form the order Blattodea. Blattodeans are related to mantids, crickets, and other winged insects that do not undergo complete metamorphosis. Like ants, termites are eusocial, with sterile workers, but they differ greatly in the genetics of reproduction. The similarity of their social structure to that of ants is attributed to convergent evolution. Velvet ants look like large ants, but are wingless female wasps.
=== Cell cycle === TGF-β plays a crucial role in the regulation of the cell cycle by blocking progress through G1 phase. TGF-β causes synthesis of p15 and p21 proteins, which block the cyclin:CDK complex responsible for retinoblastoma protein (Rb) phosphorylation. Thus, TGF-β blocks advancement through the G1 phase of the cycle. In doing so, TGF-β suppresses expression of c-myc, a gene which is involved in G1 cell cycle progression.
In Mexico, Applied Biosystems collaborated with the National Institute of Genomic Medicine of Mexico (Instituto Nacional de Medicina Genomica or INMEGEN), and established an Applied Biosystems Sequencing and Genotyping Unit at INMEGEN. In 2006, Applied Biosystems acquired the Research Products Division of Ambion, a supplier of RNA-based reagents and products. That year, with the Influenza A Subtype H5N1 "avian flu" strain scare, the company launched a global initiative to identify and track such infectious diseases. In 2006, Applied Biosystems also acquired Agencourt Personal Genomics, located in Beverly, MA, to commercialize Agencourt's SOLiD sequencing system. In 2007, ABI Solid Sequencing, a next-gen DNA sequencing platform, was announced. Mark Stevenson was appointed president and chief operating officer of Applied Biosystems. In November 2008, Applied Biosystems merged with Invitrogen, forming Life Technologies, which was acquired by Thermo Fisher Scientific in 2014.
== Chemistry == Afamelanotide has the amino acid sequence; Ac-Ser-Tyr-Ser-Nle-Glu-His-D-Phe-Arg-Trp-Gly-Lys-Pro-Val-NH2. It is also known as [Nle4,D-Phe7]-α-MSH, which is abbreviated to NDP-MSH or NDP-α-MSH. Afamelanotide is the international nonproprietary name.
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.
GSH is the reduced, thiol-containing form of glutathione, while GSSG is the oxidized disulfide dimer formed when two GSH molecules react. Cells maintain a high GSH-to-GSSG ratio under normal conditions. A shift toward GSSG is often interpreted as oxidative stress, though sample handling can affect the measured ratio.