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Onfekafusp alfa

Onfekafusp alfa (Fibromun, L19-TNF, L19TNF) is Philogen's investigational immunocytokine fusing human TNF-alpha to the L19 scFv targeting ED-B fibronectin on tumor vessels; studied in sarcoma, melanoma, and glioma, not yet authorized.

Ongericimab

Ongericimab (JS002, Junshida 君适达) is Shanghai Junshi Biosciences' subcutaneous anti-PCSK9 monoclonal antibody; NMPA approved it in 2025 for primary hypercholesterolemia and mixed dyslipidemia, lowering LDL-C about 55–70%.

Onigiri (おにぎり)

Onigiri (おにぎり), also omusubi, is the Japanese hand-pressed rice ball, typically triangular, salted, nori-wrapped, and filled with umeboshi, salmon, or tuna mayo; a staple of bento and convenience stores with a history from Yayoi-era carbonized rice to the 1978 film-packaging era.

Onion

Onion (Allium cepa), bulb crop of the amaryllis family from central Asia, cultivated over 4,700 years; bulbing is day-length controlled; second only to tomato in global production.

Onion downy mildew

Onion downy mildew is a devastating disease of Allium crops such as onion, garlic, and leek, caused by the oomycete Peronospora destructor, which can cut yields by 25 to 75 percent.

Onion extract

Onion extract (Allium cepa L. bulb extract), a water extract of food-grade onion bulbs approved as an EU basic substance in 2021 for fungicide use in potatoes, tomatoes, and cucumbers; distinct from onion oil (repellent) and onion peel extract (antioxidant preservative candidate).

Onlay mesh repair

Onlay mesh repair is a ventral hernia repair technique in which prosthetic mesh is placed over the closed abdominal wall fascia, reinforcing a tension-free primary closure.

Onobrychis

Onobrychis (sainfoins), Fabaceae genus published by Miller in 1754, native Europe to Mongolia, Arabia, Ethiopia; about 130–208 species; includes forage legume sainfoin O. viciifolia, non-bloating, tannin-rich.

Onobrychis viciifolia

Onobrychis viciifolia (common sainfoin) is a perennial Fabaceae forage legume native to Central and SE Europe, non-bloating due to condensed tannins, drought tolerant via a deep taproot, and under study as a protein-rich perennial pulse crop.

Ononis

Ononis (restharrow), Fabaceae genus of about 88 annual/perennial herbs and shrubs, Mediterranean-centered, monadelphous stamens, dimorphic anthers, used in medicine and as forage.

Onradivir tablets

Onradivir tablets (昂拉地韦片, Anruiwei, ZSP1273) is a Chinese class 1 antiviral approved May 2025 for uncomplicated influenza A in adults; the first approved PB2 RNA polymerase inhibitor, dosed 0.6 g daily for 5 days.

Ontario Health

Ontario Health (Santé Ontario), agency created 2019 by the Government of Ontario to connect, coordinate and modernize health care; absorbed Cancer Care Ontario, Trillium Gift of Life Network and 14 LHINs; six regional teams, Ontario Health atHome subsidiary.

Ontario Ministry of Health

The Ontario Ministry of Health is the Ontario government department responsible for the province's publicly funded health-care system, managing OHIP, drug programs, and emergency health services.

Ontogenesis

Ontogenesis (ontogeny): the development of an individual organism from earliest stage to maturity, contrasted with phylogenesis; rooted in Haeckel's recapitulation law, now studied as developmental biology with evolutionary constraints.

Ontogeny

Ontogeny is an individual organism's development from fertilization to maturity. Known through Haeckel's biogenetic law "ontogeny recapitulates phylogeny" (1866), rejected in strict form but surviving as a partial trend studied in evo-devo.

Onur Boyman

Onur Boyman is a Swiss physician-scientist and professor of clinical immunology at the University of Zurich, known for cytokine immunotherapy and Long Covid complement research.

Onychectomy

Onychectomy, informally declawing or de-clawing, is the surgical amputation of a cat's third phalanges and attached claws, usually on the front paws, and is increasingly restricted by law.

Onychium

Onychium (claw ferns) is a genus of 12 accepted terrestrial fern species in Pteridaceae subfamily Pteridoideae, native from NE tropical Africa through tropical and subtropical Asia to N Australia, sister to Actiniopteris, with submarginal continuous sori protected by a reflexed false indusium.

Onychocytic matricoma

Onychocytic matricoma (acanthoma of the nail matrix) is a rare benign nail matrix tumor first described by Perrin in 2012, causing monodactylous longitudinal pachymelanonychia with nail plate thickening, purely epithelial histology, and mimicry of melanoma and onychocytic carcinoma.

Onychogalea fraenata

Onychogalea fraenata, the bridled nailtail wallaby, is an endangered macropod of inland eastern Australia, named for white bridle markings on its neck and thought extinct until rediscovered in 1973.

Onycholysis

Onycholysis, also called nail plate separation or detachment, is a common nail disorder in which the nail plate lifts off the nail bed, appearing white and opaque. Causes include trauma, psoriasis, fungal infection, thyroid disease, and drugs such as tetracyclines and taxanes.

Onychomatricoma

Onychomatricoma is a rare benign fibroepithelial tumor of the nail matrix, first described by Baran and Kint in 1992, causing yellow thickened overcurved nails with splinter hemorrhages, woodworm-like cavities, and coexisting onychomycosis; treated by surgical excision.

Onychomycosis

Onychomycosis (tinea unguium, nail fungus): fungal infection of the nail, mainly Trichophyton rubrum, causing 2–13% population prevalence. Diagnosed by KOH, culture, PCR, PAS; treated with terbinafine, itraconazole, or efinaconazole.

Onychomys

Onychomys (grasshopper mice), genus Baird 1857, three carnivorous rodent species of western North American deserts and prairies; eats scorpions, resists bark scorpion venom via Nav1.8, tribe Onychomyini reinstated 2023.

Onychophora

Onychophora (velvet worms, peripatus): terrestrial carnivorous invertebrate phylum with 13–43 pairs of unjointed lobopods, slime-gland prey capture, and a position within Panarthropoda close to arthropods.

Onyekachi Ifudu

Onyekachi Ifudu, also published as O. Ifudu, is a nephrologist and board-certified internist in Brooklyn, New York, known for 1990s research linking dialysis intensity to anemia control.

Ooblast

Ooblast (CL:0002239) is a Cell Ontology term for an early female germ cell stage, annotated in mouse at Theiler stage 21; it sits between oogonia and the primary oocyte within oogenesis.

Oocyte

Oocyte: a developing egg cell arrested in prophase I and metaphase II of meiosis before fertilization; basis of IVF and oocyte cryopreservation (vitrification), routine since ASRM's 2013 decision.

Oocyte cryopreservation

Oocyte cryopreservation, or egg freezing, is an assisted reproductive technology that freezes a woman's unfertilized eggs, used for fertility preservation before cancer therapy and elective age-related decline.

Oocyte donation

Oocyte donation is a fertility treatment in which eggs from a donor are fertilized in vitro and transferred to a recipient, pioneered at Monash in 1984.