Life and health

Chelidonium majus

Chelidonium majus (greater celandine, Bai Qu Cai), a Papaveraceae perennial of Europe to West Siberia, contains 94 isoquinoline alkaloids with antimicrobial and antitumor activity but documented hepatotoxicity and negative oral benefit-risk.

Chelodina

Chelodina, snake-necked turtles (Fitzinger 1826), a genus of side-necked chelid freshwater turtles from Australia, New Guinea, and Indonesia, with subgenera Chelodina, Macrochelodina, Macrodiremys, and Chelydera.

Chelon auratus

Chelon auratus, the golden grey mullet (formerly Liza aurata), is a Mugilidae fish of the eastern Atlantic, Mediterranean, and Black Sea, identified by a golden gill-cover spot, commercially fished, and IUCN Near Threatened since 2022.

Chelon labrosus

Chelon labrosus, the thicklip grey mullet (Mugil labrosus, Mugil chelo), is an eastern Atlantic and Mediterranean mullet identified by a thick papillose upper lip; grows to 75 cm, IUCN Near Threatened since 2022.

Chelone

Chelone (turtlehead) is a genus of six perennial wetland herbs in Plantaginaceae, native from southeastern Canada to the eastern and central United States, with two-lipped white to purple flowers pollinated by bumblebees.

Cheloniceras

Cheloniceras, extinct Aptian ammonite genus (Douvilleiceratidae, Cheloniceratinae) established by Hyatt 1903, type species Ammonites cornuelianus d'Orbigny 1841; tuberculate, ribbed shell known from Europe, Africa, Japan, and the Americas.

Oct 20, 2026

Cheloniidae

Cheloniidae is the family of hard-shelled sea turtles, six extant species in five genera (loggerhead, green, hawksbill, Kemp's and olive ridley, flatback), sister to Dermochelyidae within Chelonioidea, shells covered in keratin scutes.

Chelonoidis

Chelonoidis (Fitzinger, 1835) is a tortoise genus holding the Galapagos giant tortoises plus mainland South American species like C. carbonarius; 15 species, 2 extinct, with disputed species-versus-subspecies taxonomy for the Galapagos taxa.

Chelonoidis carbonarius

Chelonoidis carbonarius, the red-footed tortoise (jabuti piranga), is a South American Testudinidae tortoise of savanna and cerrado habitats, sister to C. denticulatus, a seed disperser and game species, IUCN Endangered since 2025.

Chelonoidis denticulatus

Chelonoidis denticulatus, the yellow-footed tortoise (Jabuti-Tinga), is a Testudinidae tortoise of Amazonian South America, up to 82 cm and 60 kg, omnivorous, IUCN Vulnerable and heavily hunted for consumption.

Chelsea Flower Show

RHS Chelsea Flower Show, also called the Great Spring Show, is the Royal Horticultural Society's annual May flower show at the Royal Hospital Chelsea, London, held since 1913 except wartime years and 2020, with about 157,000 visitors.

Chelydra

Chelydra, the typical snapping turtles, is a genus of three large freshwater turtle species: C. serpentina, C. rossignonii, and C. acutirostris, split from one polytypic species by 1996 mtDNA evidence.

Chemexfoliation

Chemexfoliation (chemical peel, chemabrasion): applying a chemical solution such as TCA, glycolic, or salicylic acid to dissolve skin layers for acne, melasma, and photoaging; classified superficial, medium, deep; FDA warns against unsupervised use.

Chemical ablation

Chemical ablation is a medical treatment that destroys abnormal tissue, such as tumors, cysts, or cardiac conduction pathways, by injecting a chemically toxic agent, usually absolute ethanol.

Chemical castration

Chemical castration, or medical castration/androgen deprivation therapy, uses drugs such as GnRH agonists to suppress sex hormone production, mainly for prostate and breast cancer and, controversially, to reduce sex offenders' libido; it is generally reversible.

Chemical defenses of sponges

Sponges use chemical defenses, secondary metabolites that deter predators, inhibit microbes and fouling organisms, and suppress competitors; sponges have yielded more than 5000 such compounds, more than any other marine group.

Chemical ecology of gastropods

Chemical ecology of gastropods is the study of how snails and slugs use dissolved, airborne, and contact-transmitted molecules to find food and mates, avoid predators, and defend themselves.

Chemical Evolution

Chemical evolution: the prebiotic stage between chemistry and biological evolution, where selection acts on molecular physicochemical properties; central to origin-of-life research (Oparin-Haldane, Miller-Urey, RNA world), distinct from galactic chemical evolution in astronomy.

Chemical exchange saturation transfer imaging

Chemical exchange saturation transfer (CEST) imaging is an MRI technique that detects low-concentration metabolites and proteins through the water signal, introduced by Ward, Aletras, and Balaban in 2000.

Chemical exchange saturation transfer MRI

Chemical exchange saturation transfer (CEST) MRI is an imaging technique that detects tissue pH and millimolar metabolites, with clinical studies in stroke, cancer, and osteoarthritis.

Chemical gastritis

Chemical gastritis, also called reactive gastritis, reactive gastropathy, or type C gastritis, is stomach lining injury from chemical irritants such as NSAIDs, alcohol, and bile, with minimal inflammation; it affects about 15 percent of people in the United States.

Chemical hazard

Chemical hazard: the intrinsic capacity of a chemical to harm health or cause physical danger, classified under GHS and OSHA HazCom; distinct from risk, which includes exposure.

Chemical Hypophysectomy

Chemical hypophysectomy, or pituitary neuroadenolysis, destroys the pituitary by stereotactic trans-sphenoidal alcohol injection to relieve refractory cancer pain; developed by Greco and Moricca in the late 1950s, it gave roughly 75-85% relief but was displaced by intrathecal opioids and radiosurgery.

Oct 22, 2026

Chemical inducers of dimerization

Chemical inducers of dimerization are cell-permeable small molecules that bind two proteins at once, letting researchers switch protein interactions on or off in living cells within minutes.

Chemical meningitis

Chemical meningitis, also called drug-induced aseptic meningitis (ICD-11 8E40.1), is rare sterile meningeal inflammation caused by drugs such as NSAIDs or antibiotics, or by contrast agents and neurosurgical procedures, with normal CSF glucose and recovery after stopping the cause.

Chemical oesophagitis

Chemical oesophagitis (caustic or corrosive oesophagitis, ICD-11 DA24.20) is esophageal inflammation from ingested acids or alkalis. Alkalis injure the esophagus most, strictures form in about 25%, endoscopy within 24 hours grades injury.

Chemical Phenomena

Chemical phenomena: processes and properties arising from the composition, structure, and interactions of atoms and molecules; a MeSH descriptor (G02, D055598) covering chemical reactions and physicochemical processes.

Chemical poisoning

Chemical poisoning: disease caused by toxic chemical agents in animals; toxicosis, poisoning, and intoxication are synonyms. A non WOAH-listed wildlife disease, voluntarily reported; 191 cases in 2011, mostly birds, from pesticides, lead, and rodenticides.

Chemical restraint

Chemical restraint is medication given against a patient's will, not part of standard treatment, to control movement or behavior, most often benzodiazepines or antipsychotics; no consensus definition exists across jurisdictions.