72,234 articles
Hydrosalpinx
Hydrosalpinx is a fallopian tube blocked at its far end and swollen with fluid, most often after pelvic inflammatory disease, and a known cause of infertility.
Hydrostatic shock
Hydrostatic shock, also called hydraulic shock, is the contested hypothesis that a bullet's ballistic pressure wave injures tissue remote from the wound track; critics attribute remote damage to temporary cavitation instead.
Hydrotherapy
Hydrotherapy (aquatic physiotherapy, balneotherapy): therapeutic external use of water, from cold immersion (11–15 °C) and warm baths (38–40 °C) to pool exercise. Small trial benefits for osteoarthritis and fibromyalgia pain; not FDA-regulated; no cure claims proven.
Hydroureter
Hydroureter is the abnormal enlargement of the ureter, the tube carrying urine from kidney to bladder, most often caused by a blockage; it occurs at all ages.
Hydroxocobalamin
Hydroxocobalamin (Cyanokit, Cobalin-H, Neo-Cytamen) is a manufactured vitamin B12 (cobalamin) form given by injection for B12 deficiency and, at 5 g IV, as a cyanide-poisoning antidote; preferred in the UK over cyanocobalamin for longer retention.
Hydroxyamphetamine
Hydroxyamphetamine (4-hydroxyamphetamine, Paredrine, Paremyd with tropicamide) is an indirect sympathomimetic amine that releases norepinephrine to dilate the pupil and localize Horner's syndrome lesions; now largely superseded by apraclonidine.
Hydroxycamptothecin
Hydroxycamptothecin (10-hydroxycamptothecin, HCPT, 10-羟基喜树碱), a topoisomerase I-inhibiting alkaloid from Camptotheca acuminata, about 30 times more active than camptothecin but limited by lactone instability and poor water solubility.
Hydroxycarbamide
Hydroxycarbamide (hydroxyurea), a ribonucleotide reductase inhibitor synthesized in 1869, FDA-approved 1967 as an antineoplastic and 1998 for sickle cell anemia; raises HbF, reduces pain crises, mainstay disease-modifying SCD drug.
Hydroxychloroquine
Hydroxychloroquine (Plaquenil, HCQ), a 4-aminoquinoline DMARD derived from chloroquine and quinine, treats rheumatoid arthritis, lupus, skin conditions, and malaria; large trials found no COVID-19 benefit, and retinopathy is the main long-term risk.
Hydroxycut
Hydroxycut, also sold as Hydroxycut Advanced and Hydroxycut Hardcore, is an Iovate/MuscleTech weight loss supplement brand recalled in 2009 after 23 FDA-reported liver injury cases and one death, with reformulated products still on sale.
Hydroxyethylthiazole kinase
Hydroxyethylthiazole kinase (ThiM, EC 2.7.1.50), encoded by thiM, is a ribokinase-family trimeric enzyme that phosphorylates 4-methyl-5-beta-hydroxyethylthiazole with ATP and Mg2+ as the key salvage step of bacterial, archaeal, and plant thiamine biosynthesis.
Hydroxykynureninuria
Hydroxykynureninuria, also known as xanthurenic aciduria or kynureninase deficiency, is a very rare inherited disorder of tryptophan metabolism with large urinary losses of xanthurenic acid, kynurenine, and 3-hydroxykynurenine.
Hydroxyl radical footprinting
Hydroxyl radical footprinting is a structural probing method in which hydroxyl radicals cleave nucleic acid backbones or oxidize protein side chains, mapping binding sites, folding, and conformational change in solution.
Hydroxylamine reductase
Hydroxylamine reductase (EC 1.7.99.1), the activity annotated to hybrid cluster protein (HCP, prismane protein), reduces NH2OH to NH3 and H2O via a hybrid [4Fe-2S-2O] cluster; its physiological relevance is debated.
Hydroxylamine reductase/Ni-containing CO dehydrogenase
IPR004137, Hydroxylamine reductase/Ni-containing CO dehydrogenase (HCP/CODH), is an InterPro protein family uniting hybrid cluster proteins (prismane protein) and anaerobic nickel CO dehydrogenases sharing a prismane-like scaffold and related Fe-S-O/Ni-Fe clusters.
Hydroxylation
Hydroxylation: adding a hydroxyl group to a compound where none existed before; carried out biologically by P450 monooxygenases via radical rebound, and in collagen by ascorbate-dependent prolyl and lysyl hydroxylases.
Hydroxymethylglutaryl-CoA synthase
Hydroxymethylglutaryl-CoA synthase (HMG-CoA synthase, EC 2.3.3.10) is an enzyme condensing acetyl-CoA and acetoacetyl-CoA into HMG-CoA; cytosolic HMGCS1 serves cholesterol synthesis, mitochondrial HMGCS2 controls ketogenesis, and HMGCS2 deficiency is a rare ketogenesis disorder.
Hydroxyphenyl salicylamide
Hydroxyphenyl salicylamide (N-(4-hydroxyphenyl)salicylamide, oxaphenamide, osalmid; CAS 526-18-1) is a salicylanilide fungicide, EU ID 134, not approved in the EU since the 2002/2076/EC decision, with a 0.01 mg/kg default MRL.
Hydroxyprogesterone caproate
Hydroxyprogesterone caproate (17-OHPC; Delalutin, Makena, Proluton Depot) is a synthetic long-acting progestin ester given weekly by intramuscular injection. FDA approved it in 2011 to prevent recurrent preterm birth and withdrew that approval in April 2023; the EU suspended it in 2024.
Hydroxyproline O-arabinosyltransferase-like domain
Hydroxyproline O-arabinosyltransferase-like (HPAT-like) domain, InterPro IPR056508/Pfam PF23452: catalytic domain of plant GT95 glycosyltransferases that add the first L-arabinose to hydroxyproline residues on extensins and CLE peptides.
Hydroxystilbamidine
Hydroxystilbamidine (2-hydroxy-4,4'-stilbenedicarboxamidine, CAS 495-99-8) is a stilbenoid aromatic diamidine. Its isethionate salt, approved in 1953 and now discontinued, treated blastomycosis and leishmaniasis; the dye remains a histochemical stain and neuroanatomic tracer.
Hydroxyurea therapy
Hydroxyurea (hydroxycarbamide) therapy is oral drug treatment that inhibits ribonucleotide reductase and raises fetal hemoglobin, the mainstay disease-modifying drug for sickle cell disease since FDA approval in 1998.
Hydroxyzine
Hydroxyzine (Atarax, Vistaril) is a first-generation sedating antihistamine used for itching, anxiety, and surgical sedation, in use since 1955, with a small but definite QT-prolongation risk that led to 2015 EMA dose restrictions.
Hydrozoa
Hydrozoa, a class of Cnidaria (hydras, hydroids, hydromedusae, siphonophores), alternates polyp and medusa stages; over 2,700 species in two clades, Trachylina and Hydroidolina.
Hyejung Won
Hyejung Won (원혜정) is a South Korean neurogeneticist and tenured associate professor at UNC-Chapel Hill, known for H-MAGMA and a 2019 NIH New Innovator Award.
Hyena
Hyena (family Hyaenidae): four species, spotted, striped, brown hyena, and aardwolf, in Africa, SW Asia, and India; bone-cracking scavengers and hunters, spotted hyena lives in primate-like clans up to 130.
Hyeryun Choe
Hyeryun Choe is a virologist at Boston Children's Hospital and Harvard Medical School known for identifying the HIV-1 coreceptors CCR3 and CCR5 and studying virus entry.
HyFerr study
HyFerr (Candidate Gene for Hyperferritinemia, NCT05659017) is an observational genetic study at the University of Milano Bicocca and San Gerardo Hospital, Monza, sequencing a candidate gene in 100 patients with unexplained hyperferritinemia without iron overload; it yielded biallelic STAB1 variants as a novel cause.
Hygiene
Hygiene: conditions and practices maintaining health and preventing disease spread, covering hand hygiene, environmental cleaning, and WASH. Key facts: WHO-5 hospital strategy, 80% global basic hygiene coverage in 2024, 394,000 diarrhoea deaths from unsafe hand hygiene.
Hygiene hypothesis
Hygiene hypothesis: Strachan's 1989 proposal that reduced early-life microbial exposure impairs immune maturation, raising allergy and autoimmune risk; revised as the old friends and biodiversity hypotheses.