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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.
Hydroxynorketamine
Hydroxynorketamine (HNK) is a hydroxylated metabolite of ketamine, formed in the body after ketamine administration. Twelve stereoisomers exist; the (2R,6R) form is studied as a rapid-acting antidepressant without dissociation.
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
Hydroxyproline is a non-proteinogenic amino acid made by post-translational hydroxylation of proline by prolyl hydroxylase. It stabilizes collagen, the main protein of connective tissue, and occurs in plant cell walls.
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.
Hydroxypropyl cellulose
Hydroxypropyl cellulose (HPC, CAS 9004-64-2), a non-ionic cellulose ether soluble in water below its 45°C LCST and in organic solvents; used as a food thickener, pharmaceutical excipient, and the discontinued Lacrisert dry-eye insert.
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.
Hydroxytyrosol
Hydroxytyrosol is a phenolic compound found principally in olives and olive oil, formed from oleuropein during ripening and valued for antioxidant, anti-inflammatory, and antibacterial properties in laboratory studies.
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.
Hydrus
Hydrus (abbreviation Hyi) is a small far-southern constellation, the Male Water Snake, distinct from Hydra, introduced by Johann Bayer in 1603 with brightest star Beta Hydri.
Hye Kyung C. Timken
Hye Kyung C. Timken is an American physical chemist who spent a 38-year career at Chevron developing refining catalysts, including the ISOALKY ionic liquid alkylation technology.
Hye Ryung Byon
Hye Ryung Byon (변혜령) is a South Korean chemist and professor at KAIST who works on lithium batteries, redox flow batteries, and electrocatalysts, after leading a research unit at RIKEN.
Hyecho
Hyecho (혜초) was a Silla Buddhist monk of the eighth century who traveled from Tang China to India by sea and back through Central Asia, writing the travelogue Wang ocheonchukguk jeon.
Hyecho Palus
Hyecho Palus (혜초) is an IAU-named walled plain on Pluto, approved January 3, 2020, southwest of Sputnik Planitia, containing Wright Mons and Piccard Mons; named for a Korean traveler (704–787).
Hyegong of Silla
Hyegong of Silla (혜공왕) was the 36th king of Unified Silla, reigning from 765 to 780. He took the throne as an eight-year-old and died by assassination in 780.
Hyein
Hyein (이혜인), born Lee Hye-in in 2008, is a South Korean singer and the youngest member of the girl group NewJeans, debuting with them in 2022 under the label ADOR.
Hyejong of Goryeo
Hyejong of Goryeo (혜종, 惠宗), personal name Wang Mu, was the dynasty's second king (r. 943–945), eldest son of Taejo and Queen Janghwa of Naju; his reign was consumed by Wang Gyu's plots and ended with his half-brother Jeongjong taking the throne.
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 is a subquadratic, attention-free neural network architecture for sequence modeling, introduced in 2023 by Stanford's Hazy Research group, whose long convolutions run in O(N log N) time and seeded the genomic model HyenaDNA.
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.
Hyena Road
Hyena Road: 2015 Canadian war film written, directed by and starring Paul Gross, about building Route Hyena in Kandahar and tracking the legendary mujahideen fighter the Ghost; premiered at TIFF 2015.
Hyenas
Hyenas (Hyènes, 1992) is Djibril Diop Mambéty's second and final feature, a Wolof-language Senegalese adaptation of Dürrenmatt's The Visit, in which a rich woman offers her village a fortune to kill her former lover; screened in Competition at Cannes 1992.
Hyeokgeose of Silla
Hyeokgeose of Silla, or Park Hyeokgeose, is the legendary founder and first ruler of Silla, said to have reigned from 57 BCE to 4 CE.
Hyeon Jeong Hwa
Hyeon Jeong Hwa (현정화, Hyun Jung-hwa), born 1969 in Busan, is a retired South Korean table tennis player: 1988 Olympic women's doubles gold with Yang Yeong-Ja, 1992 double bronze, and the only Korean World Championships Grand Slam winner.
Hyeon Suk Shin
Hyeon Suk Shin (신현석) is a South Korean materials chemist known for ultralow-dielectric amorphous boron nitride and single-crystal hexagonal boron nitride, and director of the IBS Center for 2D Quantum Heterostructures since 2024.
Hyeongjo
Hyeongjo (형조), also called Chugwan or Chojo, was the Joseon dynasty board administering law, litigation, criminal judgment, and slave matters, abolished in the 1894 Gabo Reform.
Hyeonjong of Goryeo
Hyeonjong of Goryeo (현종), born Wang Sun in 992, was the eighth king of Goryeo, reigning from 1009 to 1031 after a coup, and won a decisive victory over the Khitan at Guju in 1018.