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Douvilleiceras
Douvilleiceras is an extinct cosmopolitan ammonite genus (family Douvilleiceratidae) from the Lower to early Middle Albian, Early Cretaceous; type species D. mammillatum, a global marker fossil, known from France, Japan, South Africa, Canada, and Madagascar.
Dovecote
Dovecote (also culverhouse, columbarium, doocot): a structure for housing and breeding pigeons or doves. A medieval aristocratic privilege in England and France, built for meat, eggs, feathers, and manure; over 25,000 existed in England by the mid-17th century.
Doves as symbols
Doves as symbols: meanings attached to doves across cultures, from mother-goddess emblems of Asherah, Astarte, and Venus, to Noah's olive-branch dove, the Holy Spirit at Jesus' baptism, and the modern political peace dove after 1919.
Dowling-Degos disease
Dowling-Degos disease (DDD, dark dot disease, reticular pigment anomaly of flexures) is a rare autosomal dominant genodermatosis causing reticulate hyperpigmentation of flexures after puberty, caused by KRT5, POFUT1, POGLUT1, PSENEN, or GLMN mutations.
Down feather
Down feather (plumule): the soft, hookless insulating feather of birds, first in both ontogeny and feather evolution, providing most thermal insulation, nest lining for eiders, and commercial down under RDS/DOWNPASS welfare standards.
Down House
Down House in Downe, Kent, was Charles Darwin's home from 1842 to 1882, where he wrote On the Origin of Species. Grade I listed house with Grade II registered gardens, now an English Heritage museum.
Down syndrome
Down syndrome (trisomy 21): genetic condition from an extra chromosome 21 copy; ~1 in 640 US births; forms include free trisomy, Robertsonian translocation, mosaicism; features intellectual disability, heart defects, early Alzheimer's.
Downbeat nystagmus
Downbeat nystagmus (DBN), ICD-11 9C84.20, is the most common acquired central nystagmus: upward slow drift, downward quick phase, worsened by downgaze; caused by cerebellar or brainstem lesions, treated with aminopyridines.
Downregulation and upregulation
Downregulation and upregulation describe decreased or increased expression of a gene product or receptor. They occur at transcriptional, post-transcriptional, translational, and epigenetic levels, and for GPCRs reflect changes in total receptor number.
Downstream MEP pathway enzymes (IspD–IspH)
Downstream MEP pathway enzymes IspD-IspH convert MEP to IPP and DMAPP in bacteria and plants; IspG and IspH are oxygen-sensitive [4Fe-4S] reductases absent in humans and pursued as anti-infective drug targets.
Downstream signal transduction
Downstream signal transduction (Reactome R-HSA-186763) is a curated human pathway describing how autophosphorylated PDGF receptors recruit SH2-domain enzymes and adaptors such as PI3K, PLC-gamma, Src, SHP2, Ras GAP, and Grb2, initiating PI3K-AKT, RAS-MAPK, and related signaling branches.
Downward gaze deviation
Downward gaze deviation (ICD-11 9C83.12), also called downgaze palsy, is a conjugate downward eye deviation or supranuclear limitation of downward gaze; chronic isolated downgaze palsy with preserved vestibulo-ocular reflex points to progressive supranuclear palsy.
Downy mildew
Downy mildew: group of plant diseases caused by obligate oomycete water molds (Peronosporaceae: Bremia, Peronospora, Pseudoperonospora, Plasmopara), not fungi. Angular yellow leaf lesions above, gray-purple downy growth below; cool, wet conditions; needs different fungicides than powdery mildew.
Downy woodpecker
Downy woodpecker (Dryobates pubescens), also Pic mineur, the smallest North American woodpecker at about 6.5 inches, distinguished from the similar hairy woodpecker by a bill shorter than the head and black-spotted outer tail feathers; common feeder bird across most of the continent.
Doxacurium
Doxacurium (Nuromax, BW-A938U) is a long-acting nondepolarizing benzylisoquinolinium neuromuscular blocker, ED95 0.025 mg/kg, renal/biliary excretion, FDA-approved 1991, now discontinued.
Doxapram
Doxapram (Dopram) is an intravenous respiratory stimulant, first FDA-approved in 1965, acting on carotid chemoreceptors and medullary centers; used for postanesthesia and drug-induced respiratory depression, COPD hypercapnia, and refractory apnea of prematurity.
Doxazosin
Doxazosin (Cardura) is a quinazoline alpha-1 adrenergic blocker for hypertension and BPH symptoms. The ALLHAT trial stopped its hypertension arm in 2000 after doxazosin doubled heart failure risk versus chlorthalidone; it remains a second-line, BPH-focused drug.
Doxepin
Doxepin (Sinequan, Silenor) is a tricyclic antidepressant approved in 1969; at 3-6 mg it acts as a selective H1 antagonist for sleep-maintenance insomnia, and at higher doses treats depression and pruritus.
Doxercalciferol
Doxercalciferol (Hectorol) is a synthetic vitamin D2 analog prohormone activated hepatically by CYP27, used to suppress PTH in secondary hyperparathyroidism of stage 3-4 CKD and dialysis patients; US approved 1999, oral and injectable forms.
Doxifluridine
Doxifluridine (5'-DFUR, Furtulon, Ro 21-9738) is an oral fluoropyrimidine prodrug of 5-fluorouracil activated by thymidine phosphorylase; capecitabine is its liver-derived successor prodrug.
Doxofylline
Doxofylline, a xanthine bronchodilator introduced in 1987 as a theophylline alternative, treats asthma and COPD with bronchodilator and anti-inflammatory activity, a wider therapeutic window, no plasma monitoring, and weak PDE2A/A2A effects only.
Doxorubicin
Doxorubicin (Adriamycin) is an anthracycline chemotherapy antibiotic, FDA-approved 1974, that kills cancer cells via DNA intercalation and topoisomerase II inhibition; its dose-limiting toxicity is cumulative cardiotoxicity, mitigated by liposomal formulations and dexrazoxane.
Doxorubicin/gemcitabine regimen
The doxorubicin/gemcitabine regimen is a combination chemotherapy schedule pairing doxorubicin, an anthracycline, with gemcitabine, tested in advanced soft tissue sarcoma and studied earlier in metastatic breast cancer.
DOXY trial
DOXY (NCT03479502) was a Vanderbilt phase 4, triple-blind trial of three intra-articular 50 mg doxycycline injections versus 40 mg methylprednisolone for adhesive capsulitis, testing a Propionibacterium acnes hypothesis; planned 40 patients, ASES outcomes, ran 2018-2022 with enrollment listed as one patient.
Doxycycline
Doxycycline (Vibramycin) is a second-generation semisynthetic tetracycline antibiotic, FDA approved 1967, inhibiting protein synthesis at the ribosomal A site; used for acne, pneumonia, malaria prophylaxis, rickettsial disease, and CDC 2024 STI postexposure prophylaxis.
Doxylamine
Doxylamine (Decapryn, Unisom, Diclegis/Diclectin) is a first-generation ethanolamine H1 antihistamine, first approved in 1948, sold over the counter as a 25 mg sleep aid and combined with vitamin B6 to treat nausea and vomiting of pregnancy.
DPAGT1-CDG
DPAGT1-CDG (CDG-Ij, OMIM 608093) is a rare autosomal recessive congenital disorder of N-linked glycosylation from DPAGT1 mutations, causing hypotonia, intractable seizures, microcephaly, and fetal hypokinesia; same gene can cause congenital myasthenic syndrome.
DPANN
DPANN (Nanobdellati) is an archaeal superphylum of at least 10 phyla of ultrasmall, genome-reduced symbionts, named for Diapherotrites, Parvarchaeota, Aenigmarchaeota, Nanoarchaeota, and Nanohaloarchaeota; first member Nanoarchaeum equitans (2002).
DPM1-CDG
DPM1-CDG (CDG-Ie, OMIM 608799) is an ultra-rare autosomal recessive congenital disorder of glycosylation caused by DPM1 gene variants, with developmental delay, hypotonia, seizures, microcephaly, elevated CK, and fewer than 20 reported cases.
DPPOS trial
DPPOS, the Diabetes Prevention Program Outcomes Study, is the long-term follow-up since 2002 of the US trial that tested lifestyle change and metformin for preventing type 2 diabetes.