Life and health

Chaetetida

Chaetetida: an order name for hypercalcified demosponge fossils with calcareous calicle tubules and silica spicules, once classed as corals; living relatives include Ceratoporella nicholsoni and Acanthochaetetes wellsi.

Chaetodipus

Chaetodipus (coarse-haired pocket mice), genus Merriam 1889 of Heteromyidae, Perognathinae; about 17–21 arid-adapted granivorous rodent species of western US and Mexican deserts, including C. baileyi and C. spinatus.

Chaetomium

Chaetomium, a genus of ascomycete fungi (Chaetomiaceae) established by Kunze in 1817 with type species Chaetomium globosum; cellulose-degrading saprotes, indoor moulds, biocontrol agents, and sources of over 100 bioactive secondary metabolites.

Chaetophractus

Chaetophractus (Fitzinger, 1871) is a South American genus of hairy armadillos in Euphractinae, classically with three species; C. nationi was synonymized with C. vellerosus, and the genus is now considered paraphyletic.

Chaetura

Chaetura, the spine-tailed swifts, a New World genus of Apodidae with 9-11 species including the Chimney Swift and Vaux's Swift; monophyletic, South American origin, unsettled species limits.

Chafing (skin)

Chafing (skin) is irritation from repeated rubbing of skin against skin, clothing, or material; friction plus moisture causes red rash, blisters, and possible infection, treated with barrier ointments and prevented with moisture-wicking clothing.

Chagaladya ghrta

Chagaladya ghrta (Chāgalādya ghṛta, छागलादिघृत), also Chagaladi Ghrita, is a classical Ayurvedic medicated ghee whose main ingredient is goat meat; AFI formulation AFI000284, dose 3 g, used for tuberculosis, cough, chest pain, and emaciation.

Chagas disease

Chagas disease, also known as American trypanosomiasis or mal de Chagas, is a tropical parasitic disease caused by Trypanosoma cruzi and spread by triatomine "kissing bugs". About 6.5 million people are infected, mostly in Latin America.

Chai Ge Jie Ji Tang

Chai Ge Jie Ji Tang (柴葛解肌汤), a Ming-dynasty TCM formula from Tao Hua's Shang Han Liu Shu, releases the muscle layer and clears heat for wind-cold turning to fever; distinct from the Yi Xue Xin Wu variant.

Chaihu Guizhi Tang

柴胡桂枝汤 (Chaihu Guizhi Decoction, 柴胡桂枝湯), a nine-herb classic formula from the Shanghan Lun combining Xiao Chaihu Tang and Guizhi Tang; harmonizes Shaoyang, listed in China's second batch of Ancient Classic Formulas, used today for neuropsychiatric, digestive, and respiratory conditions.

Chaihu Qinggan Tang

柴胡清肝汤 (Chaihu Qinggan Tang; Japanese 柴胡清肝湯, saikoseikantō) is a classical Chinese herbal formula from 《外科正宗》 and 《医宗金鉴》 combining Four Substances and Coptis Detoxification decoctions with bupleurum, traditionally for early temple/ear abscesses (鬓疽) from liver-gallbladder wind-heat; distinct from 小柴胡汤 and 柴胡疏肝散.

Chalazion

Chalazion (meibomian cyst): a chronic sterile lipogranuloma of the eyelid from obstructed meibomian or Zeis glands. Treated with warm compresses, triamcinolone injection, or incision and curettage; recurrent lesions need biopsy.

Chalcides

Chalcides (cylindrical skinks, barrel skinks), a genus of Scincidae skinks from North Africa, southern Europe, and the Canary Islands, with reduced limbs, live birth, and about 24-33 species.

Chalcididae

Chalcididae (Latreille, 1817) is a family of parasitoid wasps in Chalcidoidea, about 1,500 species in 87 genera, recognized by swollen hind femora, parasitizing mainly Lepidoptera larvae and pupae and used in biological control.

Chalcites

Chalcites, the Australasian bronze-cuckoos (Horsfield's, shining, little bronze-cuckoo and allies), a genus split from Chrysococcyx in 2020s checklists; obligate brood parasites with mimetic nestlings and host-specific races.

Chalcone isomerase

Chalcone isomerase (CHI, EC 5.5.1.6), also called chalcone-flavanone isomerase, is the plant enzyme catalyzing stereospecific cyclization of chalcones to (2S)-flavanones in flavonoid biosynthesis; type I and type II forms differ in isoliquiritigenin use.

Chalcone synthase

Chalcone synthase (CHS, EC 2.3.1.74), a type III polyketide synthase, catalyzes the first committed step of flavonoid biosynthesis, condensing p-coumaroyl-CoA and malonyl-CoA into naringenin chalcone; homodimeric, Cys164-His303 catalytic pair, ancestor of stilbene synthase.

Chalinolobus

Chalinolobus (wattled bats, lobe-lipped bats) is a genus of vespertilionid bats, tribe Vespertilionini, mostly Australian and New Zealand; seven-plus species including endangered C. neocaledonicus and C. dwyeri, plus C. orarius described in 2024.

Sep 29, 2026

Challenge testing

Challenge testing is a diagnostic procedure in which a suspected food or drug is given under medical supervision to confirm or exclude allergy when other tests are unclear.

ChallengeII trial

ChallengeII (NCT01083095) was a Colombian early Phase 1 trial establishing a Plasmodium vivax sporozoite mosquito-bite challenge model in 18 volunteers, infecting 17 of 18 with 2-10 Anopheles albimanus bites.

Chamaecrista

Chamaecrista (L.) Moench, a genus of about 350–379 legume species (Fabaceae, Cassiinae) of herbs and shrubs native to the tropics and subtropics; nodulating, buzz-pollinated, extrafloral-nectary-bearing plants distinct from Cassia and Senna.

Chamaecyparis

Chamaecyparis, false cypress or white-cedar, is a genus of seven Cupressaceae conifer species native to North American coasts, Japan, and Taiwan, told from Cupressus by flattened branchlets, small first-year cones, and 2–4 seeds per scale.

Chamaecyparis eureka

Chamaecyparis eureka is an extinct Eocene cypress (Cupressaceae) described by Kotyk, Basinger, and McIver in 2003 from Axel Heiberg Island, Canadian Arctic; known from foliage and seed cones, most similar to Chamaecyparis pisifera, once the genus's oldest fossil.

Chamaecyparis lawsoniana

Chamaecyparis lawsoniana, Port-Orford-cedar or Lawson cypress, a Cupressaceae conifer native to SW Oregon and NW California, valued for aromatic timber and ornamental cultivars, threatened by Phytophthora lateralis root rot and rated Near Threatened.

Chamaecyparis obtusa

Chamaecyparis obtusa (ヒノキ, hinoki cypress), Japanese-Taiwanese evergreen cypress; sacred timber tree used since the Nara era, Japan's second-largest plantation species, IUCN Near Threatened, with many dwarf cultivars.

Chamaedorea

Chamaedorea, the largest neotropical palm genus with about 108 accepted species from Mexico to South America, comprises small dioecious rainforest understory palms; C. elegans is the parlour palm houseplant and xate leaves are a major Guatemalan forest product.

Chamaedorea elegans

Chamaedorea elegans, the parlor palm (also Neanthe bella), is a small dioecious solitary palm native from Mexico to Honduras, a Victorian-era houseplant tolerating low light, with over 400 million seeds traded yearly.

Chamaeleo

Chamaeleo (Laurenti, 1768) is the most widespread chameleon genus, with 14 species across Africa and Eurasia, originating in southern Africa during the Eocene and diversifying through the Oligocene and Miocene.

Chamaeleon

Chamaeleon Cass. is a small Asteraceae genus of spiny carline-thistle-like plants published by Cassini in 1827, native from the Mediterranean to Pakistan, with five accepted species including C. gummifer; some authorities merge it into Carlina.