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Dihuang Yinzi
地黄饮子 (Dihuang Yinzi), a classical Chinese medicine formula from Liu Wansu's Jin-dynasty Xuanming Lunfang; 12 herbs tonifying kidney yin and yang, originally for yinfei (speech loss, leg paralysis), now studied for Parkinson's disease and dementia.
Dihybrid cross
Dihybrid cross: a mating between two organisms identically hybrid for two traits, first performed by Mendel in 1865 pea experiments; yields a 9:3:3:1 F2 phenotypic ratio under independent assortment, altered by linkage or epistasis.
Dihydralazine
Dihydralazine (Nepresol), a hydralazine-family direct arteriolar vasodilator, half-life 4-5 h, used mainly for severe hypertension in pregnancy in Germany; declining due to frequent adverse effects.
Dihydroartemisinin-piperaquine
Dihydroartemisinin-piperaquine (DHA-PPQ, DP, Duo-Cotexin) is a fixed-dose artemisinin combination therapy for uncomplicated malaria: fast dihydroartemisinin plus long-acting piperaquine, superior to artemether-lumefantrine in Africa but failing in the Greater Mekong subregion.
Dihydrocapsiate
Dihydrocapsiate (DHC, DCT) is a non-pungent capsinoid analog of capsaicin from CH-19 Sweet peppers, formula C18H28O4; human trials show a small thermogenic effect near 50 kcal/day, and it is GRAS in the US and an authorized EU novel food.
Dihydrocodeine
Dihydrocodeine (DHC), a semisynthetic opioid derivative of codeine used for moderate to severe pain and cough, metabolized via CYP2D6 and CYP3A4, with limited efficacy evidence and addiction and respiratory-depression risks.
Dihydrodipicolinate reductase
Dihydrodipicolinate reductase (DapB, EC 1.17.1.8, 4-hydroxy-tetrahydrodipicolinate reductase) is a bacterial NAD(P)-dependent homotetrameric enzyme catalyzing HTPA-to-tetrahydrodipicolinate reduction, the second step of the diaminopimelate/lysine pathway and an antibiotic target.
Dihydroergotamine
Dihydroergotamine (DHE) is a semi-synthetic ergot alkaloid drug used for the acute treatment of migraine and cluster headache, first synthesized in 1943 and approved in 1946.
Dihydroetorphine
Dihydroetorphine (二氢埃托啡, DHE), a Chinese-developed etorphine-family opioid agonist over 1,000 times stronger than morphine, approved 1991 for severe pain, later restricted for abuse and dependence.
Dihydrofolate reductase
Dihydrofolate reductase, also known as DHFR, is an enzyme that produces the folate cofactor required for synthesizing purines and thymidylate, making it a key drug target.
Dihydrolipoamide dehydrogenase
Dihydrolipoamide dehydrogenase (DLD, E3, EC 1.8.1.4) is a homodimeric mitochondrial FAD enzyme, encoded on chromosome 7, that reoxidizes lipoamide in the PDH, α-ketoglutarate, branched-chain keto acid, and 2-oxoadipate dehydrogenase complexes; DLD mutations cause rare autosomal recessive E3 deficiency.
Dihydroorotase
Dihydroorotase (DHOase, EC 3.5.2.3), zinc metalloenzyme of de novo pyrimidine biosynthesis catalyzing reversible carbamoyl aspartate to dihydroorotate conversion; TIM-barrel amidohydrolase, type I and II, CAD domain in mammals, binuclear or mononuclear zinc center.
Dihydroorotate dehydrogenase
Dihydroorotate dehydrogenase (DHODH, PyrD) is an FMN flavoenzyme catalyzing the fourth, redox step of de novo pyrimidine biosynthesis; Class 1 (fumarate/NAD+) and Class 2 (ubiquinone, mitochondrial) forms are drug targets in arthritis, cancer, and malaria via leflunomide, teriflunomide, and DSM265.
Dihydropteroate synthase
Dihydropteroate synthase (DHPS) is an enzyme that joins p-aminobenzoic acid to a pterin in bacterial folate biosynthesis, making it the target of sulfonamide antibiotics, the oldest class of synthetic antibacterial drugs.
Dihydropteroate synthase type-3
Dihydropteroate synthase type-3 (Sul3, gene sul3) is a plasmid-borne sulfonamide-resistant DHPS enzyme, characterized in 2003 from E. coli plasmid pVP440 in Swiss pigs, 263 amino acids, spread via IS15Δ/26-flanked segments.
Dihydropyrimidine dehydrogenase deficiency
Dihydropyrimidine dehydrogenase deficiency (DPD deficiency, DPYD deficiency) is an autosomal recessive DPYD enzyme disorder causing neurological disease in some and severe, sometimes fatal fluoropyrimidine (5-FU, capecitabine) toxicity in others.
Dihydropyrimidinuria
Dihydropyrimidinuria, also called dihydropyrimidinase deficiency (DPYS deficiency, OMIM 222748), is a rare autosomal recessive pyrimidine metabolism disorder causing dihydrouracil and dihydrothymine accumulation, variable neurologic and gastrointestinal features, and fluoropyrimidine toxicity risk.
Dihydrotachysterol
Dihydrotachysterol (DHT, A.T. 10) is a half-synthetic vitamin D analog from ergosterol, introduced in 1933 for hypoparathyroidism; it needs no renal hydroxylation and is no longer sold in the US.
Dihydrotestosterone
Dihydrotestosterone (DHT, androstanolone), the most potent androgen, made from testosterone by 5α-reductase in prostate, testes, hair follicles, and adrenals; key in male sex development, BPH, and hair loss, acting mainly as a paracrine hormone.
Dihydroxy-acid dehydratase
Dihydroxy-acid dehydratase (DHAD, EC 4.2.1.9, gene ilvD/ILV3) is an Fe-S cluster enzyme of the IlvD/EDD superfamily that dehydrates dihydroxy acids into keto acid precursors of leucine, isoleucine, and valine, and is an antimicrobial drug target.
Dihydroxyacetone phosphate
Dihydroxyacetone phosphate (DHAP), also called glycerone phosphate, is a three-carbon phosphorylated sugar with formula C3H7O6P that serves as a central intermediate in glycolysis, gluconeogenesis, and lipid biosynthesis.
Dihydroxyacetone phosphate acyltransferase
Dihydroxyacetone phosphate acyltransferase (DHAPAT, GNPAT, EC 2.3.1.42) is a peroxisomal membrane enzyme that acylates DHAP to start plasmalogen synthesis; its deficiency causes rhizomelic chondrodysplasia punctata type 2.
Dik-dik
The dik-dik is a small antelope of the genus Madoqua, native to dry bushlands of eastern and southwestern Africa and named for the females' whistling alarm call.
Dikaryon
Dikaryon: a fungal cell or hypha with two genetically distinct haploid nuclei, one from each parent, in a 1:1 ratio; the persistent vegetative phase of most basidiomycetes, maintained by clamp connections until karyogamy in the basidium.
Dikegulac
Dikegulac (dikegulac-sodium, Atrinal, Atrimmec, Augeo, 调呋酸) is an atypical plant growth regulator, a vitamin C synthesis by-product, that chemically pinches plants by inhibiting DNA synthesis in apical meristems, promoting lateral branching; EU use ended 2007.
Dilated cardiomyopathy
Dilated cardiomyopathy (DCM), also called congestive or idiopathic cardiomyopathy, is heart-muscle disease with left ventricular dilatation and systolic dysfunction not explained by coronary, hypertensive, or valvular disease; prevalence about 1 in 250 adults, genetic in 25–40% of cases (TTN, LMNA, DSP, FLNC).
Dilated cardiomyopathy with ataxia
Dilated cardiomyopathy with ataxia (DCMA, 3-methylglutaconic aciduria type V) is a rare autosomal recessive mitochondrial disease from DNAJC19 mutations, concentrated in the Dariusleut Hutterite population, causing early-onset cardiomyopathy, long QT, cerebellar ataxia, and growth failure.
Dilated cardiomyopathy-hypergonadotropic hypogonadism syndrome
Dilated cardiomyopathy-hypergonadotropic hypogonadism syndrome, also called Malouf, Najjar, or cardiogenital syndrome (ORPHA:2229, OMIM 212112), is an ultra-rare disorder combining dilated cardiomyopathy with primary hypergonadotropic hypogonadism, often LMNA-related, prevalence under 1 per million.
Dilated fundus examination
A dilated fundus examination is an eye exam using dilating drops so the retina and optic disc can be inspected with an ophthalmoscope or slit lamp.
Dilation and curettage
Dilation and curettage (D&C), also called suction curettage when vacuum is used, is a gynecologic procedure dilating the cervix and removing endometrial tissue for miscarriage, abortion, retained products, or abnormal bleeding; WHO now recommends vacuum aspiration over sharp curettage.