72,234 articles
Hydrachnidia
Hydrachnidia (water mites; Hydrachnidiae, Hydracarina) are freshwater mites, nearly 6,000 species, the largest arachnid group in fresh water, with parasitic larvae and predatory adults, valuable but widely neglected bioindicators of stream and spring water quality.
Hydralazine
Hydralazine, a direct arteriolar vasodilator antihypertensive introduced in 1951, treats severe hypertension in pregnancy, resistant hypertension, and, with isosorbide dinitrate, Black patients with heart failure; key risk is drug-induced lupus.
Hydralazine/isosorbide dinitrate
Hydralazine/isosorbide dinitrate (BiDil) is a fixed-dose vasodilator combination for heart failure with reduced ejection fraction, best evidenced in self-identified Black patients by A-HeFT, which showed 43% lower mortality.
Hydramethylnon
Discovered by American Cyanamid in 1977, Hydramethylnon is a slow-acting Group 20A insecticide and mitochondrial complex III electron transport inhibitor used in popular household baits.
Hydranencephaly
Hydranencephaly is a rare congenital malformation in which the cerebral hemispheres are absent and replaced by a cerebrospinal fluid-filled sac, usually caused by blocked carotid arteries in the womb.
Hydrangea
Hydrangea, a genus of shrubs and climbers including H. macrophylla, arborescens, paniculata, and quercifolia; pH-sensitive flower color, old-wood versus new-wood pruning, and RHS trial results.
Hydrangea macrophylla (紫陽花)
Hydrangea macrophylla (紫陽花), bigleaf or French hydrangea, a Japanese deciduous shrub with mophead or lacecap flower heads; blue in acidic soil, pink in alkaline, blooming on old wood with reblooming cultivars like Endless Summer.
Hydrazino-Pictet–Spengler ligation
The hydrazino-Pictet–Spengler (HIPS) ligation is a bioconjugation reaction introduced in 2013 that couples aldehyde-tagged proteins to hydrazine-indole linkers, forming a stable carbon–carbon bond near neutral pH.
Hydrilla
Hydrilla (Hydrilla verticillata), or waterthyme, is an invasive submerged aquatic plant of Hydrocharitaceae with whorled serrated leaves, tubers, and turions; introduced via the aquarium trade, it infests 28 US states and is a Federal Noxious Weed.
Hydroa vacciniforme
Hydroa vacciniforme (Bazin's hydroa vacciniforme) is a rare childhood photodermatosis causing vesicles on sun-exposed skin that heal with permanent varioliform scars; severe EBV-associated forms (HVLPD) can progress to lymphoma.
Hydroa vacciniforme-like lymphoma
Hydroa vacciniforme-like lymphoma (HVLL), now hydroa vacciniforme lymphoproliferative disorder, is a rare EBV-positive T/NK-cell lymphoproliferative disease of childhood, mainly in Asia and Latin America, with ulcerative skin lesions and risk of systemic lymphoma.
Hydrobates
Hydrobates (Boie, 1822) is the genus of northern storm petrels, family Hydrobatidae; it absorbed Oceanodroma after genetic work showed paraphyly, and includes H. pelagicus, H. leucorhous, and H. castro.
Hydrobatidae
Hydrobatidae, the northern storm petrels (family Mathews, 1912, order Procellariiformes), small pelagic seabirds now placed in a single genus Hydrobates with about 18 species, split from the southern Oceanitidae.
Hydrobia
Hydrobia (W. Hartmann, 1821) is a genus of minute brackish-water hydrobiid mud snails of the northern Atlantic and Mediterranean; type species Hydrobia acuta, with former members like H. ulvae and H. ventrosa now split into Peringia and Ecrobia/Ventrosia.
Hydrobiidae
Hydrobiidae (mud snails, spring snails) is the largest family of freshwater gastropods, minute operculate Truncatelloidea snails of springs, subterranean, brackish and fresh waters; ~910–1200 species, ~180 genera, diversifying after the K–Pg boundary ~60 Ma.
Hydrocele
Hydrocele, also called hydrocele of the tunica vaginalis or canal of Nuck hydrocele in females, is serous fluid collection around the testis causing scrotal swelling; common in newborns, treated by hydrocelectomy or aspiration with sclerotherapy.
Hydrocele or spermatocele
Hydrocele or spermatocele (ICD-11 GB00; ICD-10 N43): scrotal fluid collections. Hydrocele is serous fluid in the tunica vaginalis or spermatic cord; spermatocele is an epididymal cyst containing dead sperm, usually painless and untreated.
Hydrocele testis
Hydrocele testis, fluid collection in the tunica vaginalis around the testis, causes painless scrotal swelling; common in newborns (at least 5%), often resolving by age 1, with communicating, noncommunicating, and filarial forms treated by observation, hydrocelectomy, or sclerotherapy.
Hydrocephalus
Hydrocephalus, "water on the brain," is abnormal CSF build-up in the brain's ventricles. Treated by shunt surgery or endoscopic third ventriculostomy (ETV), often with CPC; congenital, acquired, and NPH types.
Hydrocharitaceae
Hydrocharitaceae, the frog's-bit or tape-grass family (Najadaceae synonym), is a cosmopolitan family of 14 genera and about 136 fully aquatic monocot herbs in Alismatales, with 3 marine seagrass genera, water pollination, and an Asian Late Cretaceous origin.
Hydrochlorothiazide
Hydrochlorothiazide (HCTZ) is a thiazide-type diuretic inhibiting the renal NCC transporter, used for hypertension and edema; the most prescribed US thiazide (~31.8 million 2023 prescriptions), with electrolyte, metabolic, and small skin-cancer risks.
Hydrocodone
Hydrocodone (dihydrocodeinone) is a semi-synthetic opioid analgesic and antitussive, a full mu-opioid agonist, sold mainly in combination products like Vicodin and Tussionex; DEA Schedule II since October 2014, with about 136 million US prescriptions in 2011.
Hydrocodone/paracetamol
Hydrocodone/paracetamol, also called hydrocodone/acetaminophen and formerly sold as Vicodin, is a prescription tablet combining the opioid hydrocodone with acetaminophen, prescribed in the United States for severe pain.
Hydrocortamate
Hydrocortamate (CAS 76-47-1) is a synthetic glucocorticoid, a hydrocortisone diethylaminoacetate ester, glucocorticoid receptor agonist used topically for dermatoses; marketed as Magnacort 0.5% ointment, US-approved 1956, now discontinued.
Hydrocortisone
Hydrocortisone (cortisol) is the synthetic form of the adrenal glucocorticoid cortisol, used for cortisol replacement in adrenal insufficiency (15–25 mg/day divided) and as an anti-inflammatory; discovered as Compound F at Mayo Clinic, 1950 Nobel Prize context.
Hydrocotyle
Hydrocotyle (pennywort) is a cosmopolitan genus of creeping aquatic and wetland herbs in Araliaceae, transferred from Apiaceae after molecular work; about 130–180 species, with all annual species endemic to Australia.
Hydrocynus goliath
Hydrocynus goliath, the giant or goliath tigerfish, is a large piscivorous African freshwater fish (Alestidae) of the Congo basin and Lake Tanganyika, reaching 133 cm and 50 kg, IUCN Least Concern.
Hydroflumethiazide
Hydroflumethiazide (Saluron, Diucardin) is an oral thiazide diuretic and antihypertensive benzothiadiazine, C8H8F3N3O4S2, inhibiting the SLC12A3 sodium-chloride symporter; discontinued in the US.
Hydrogen breath test
The hydrogen breath test is a non-invasive diagnostic procedure measuring hydrogen and methane in exhaled air after a sugar substrate, detecting carbohydrate malabsorption or small intestinal bacterial overgrowth.
Hydrogen hypothesis
Proposed by William Martin and Miklós Müller in 1998, the Hydrogen hypothesis posits that the eukaryotic cell originated from a metabolic symbiosis. This process involved an archaeal host and a hydrogen-producing alphaproteobacterial symbiont.