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Chemical Safety
Chemical safety: controlling exposure to hazardous substances via the NIOSH hierarchy of controls, OSHA PELs and HazCom/GHS safety data sheets, laboratory chemical hygiene, and EPA and EU chemical regulation.
Chemical senses
Chemical senses: olfaction (smell), gustation (taste), and trigeminal chemesthesis, the sensory systems detecting airborne, ingested, and irritant chemicals, their receptors, brain integration into flavor, and clinical dysfunction.
Chemical sympathectomy
Chemical sympathectomy is the percutaneous destruction of sympathetic nerves with alcohol or phenol, relieving ischemic and neuropathic pain, vasospastic disease, and excessive sweating, though relief is temporary.
Chemiluminescent assay
A chemiluminescent assay is a laboratory method that measures hormones, antibodies, or tumor markers through light emitted by a chemical reaction, first reported in 1978.
Chemiluminescent immunoassay
Chemiluminescent immunoassay (CLIA) is a laboratory diagnostic method that detects antigens or antibodies using a light-emitting label; first reported in 1985, it displaced radioimmunoassay and is fully automated.
Chemistry of ascorbic acid
Chemistry of ascorbic acid (vitamin C, C6H8O6): a water-soluble lactone acid, pKa 4.17, readily oxidized via ascorbate radical to dehydroascorbic acid; isolated as hexuronic acid by Szent-Györgyi, structure solved and synthesized by Haworth (1937 Nobel).
Chemo-photodynamic therapy
Chemo-photodynamic therapy, or chemophototherapy, is a combination cancer treatment pairing chemotherapy with photodynamic therapy, where light activates a photosensitizer to kill tumor cells synergistically; the interaction was first demonstrated in 1983.
Chemohormonal therapy
Chemohormonal therapy is a cancer treatment combining chemotherapy with hormonal therapy, principally six cycles of docetaxel added to androgen deprivation therapy, which prolongs survival in metastatic hormone-sensitive prostate cancer.
Chemoprevention trial
A chemoprevention trial is a clinical trial testing whether a drug, vitamin, or other agent can prevent or delay cancer in at-risk people or survivors.
Chemoprophylaxis
Chemoprophylaxis is the administration of a drug to prevent disease rather than treat it, taken before or after exposure, as in malaria prophylaxis for travelers and isoniazid preventive therapy for tuberculosis.
Chemoradiotherapy
Chemoradiotherapy, or chemoradiation therapy, is a cancer treatment in which chemotherapy drugs are given during the same period as radiation therapy, improving survival in head and neck, lung, cervical, and other cancers.
Chemosensitivity assay
A chemosensitivity assay, also called chemosensitivity testing, is a laboratory method measuring how cultured tumor cells respond to chemotherapy drugs, used to guide individualized treatment and drug development.
Chemosis
Chemosis (conjunctival chemosis) is edema and ballooning of the conjunctiva, usually from infection, allergy, injury, or eyelid surgery such as blepharoplasty; treated by addressing the cause, with cold packs, lubrication, and medications.
Chemotherapy
Chemotherapy, often called chemo, is a cancer treatment in which drugs kill malignant cells or stop them from dividing, given by mouth, injection, infusion, or topical cream.
Chemotherapy, Cancer, Regional Perfusion
Chemotherapy, cancer, regional perfusion (MeSH D010478): cancer drug therapy via an extracorporeal circuit isolating the tumor-bearing area, chiefly isolated limb perfusion with melphalan and TNFα for extremity melanoma and sarcoma, delivering 10-20 times systemic doses.
Cherenkov luminescence imaging
Cherenkov luminescence imaging is an optical method that photographs the faint light emitted when radioactive tracers decay in tissue, a low-cost complement to PET and SPECT.
Cherry angioma
Cherry angioma, also called Campbell de Morgan spot or senile angioma, is a benign red skin growth of dilated capillaries, 1 to 5 mm, common after age 30 and in 75% of adults over 75, treated by laser or electrosurgery if needed.
Cheryl R. Blanchard
Cheryl R. Blanchard is an American bioengineer and medical-device executive elected to the National Academy of Engineering in 2015, later CEO of Microchips Biotech and Anika Therapeutics.
Chest CT
Chest CT is a cross-sectional imaging method that shows lungs and chest structures in more detail than a chest X-ray, commonly used in emergency settings.
Chest hair
Chest hair: terminal body hair growing on the male chest after puberty under DHT stimulation; a secondary sex trait varying by ethnicity, studied in Caucasian and Chinese men, and commonly removed by shaving or waxing.
Chest pain
Chest pain: pain or discomfort in the anterior chest prompting cardiac concern; also called angina when ischemic. Second most common US ED complaint; evaluated via ECG, troponin, HEART/EDACS scores, and CCTA.
Chest pain on breathing
Chest pain on breathing (pleuritic chest pain, ICD-11 MD30.0) is sharp pain worsening with deep breaths, caused by parietal pleura inflammation; pulmonary embolism is the most common life-threatening cause, viral infection the most common benign one.
Chest radiograph
Chest radiograph (chest X-ray, CXR): the most commonly performed diagnostic X-ray exam, imaging heart, lungs, airways, and chest bones with a small radiation dose, typically PA plus lateral views in about 15 minutes, used for pneumonia, heart failure, and lung cancer.
Chest tube
Chest tube (thoracostomy tube): flexible tube drained into the pleural space to remove air or fluid in pneumothorax, effusion, empyema, hemothorax; sizes in French units, triangle-of-safety insertion, pigtail vs large-bore evidence.
Chest wall reconstruction
Chest wall reconstruction is the surgical restoration of skeletal stability, airtight closure, and soft-tissue coverage of the chest wall after tumor resection, trauma, infection, or correction of congenital defects.
Chest wall resection
Chest wall resection is the removal of a full-thickness portion of the chest wall, including muscle and bone, performed mainly for tumors and followed by reconstruction.
Chevron osteotomy
The chevron osteotomy is a V-shaped cut of the first metatarsal that shifts the bone's head sideways to correct hallux valgus, the bunion deformity, in mild to moderate cases.
Cheyne–Stokes respiration
Cheyne–Stokes respiration (CSR), periodic breathing with crescendo–decrescendo hyperventilation alternating with central apnea, 45–90 second cycles; seen in 25–50% of heart failure patients, first described by Cheyne (1818) and Stokes (1854).
Chiari malformation
Chiari malformation (Arnold-Chiari malformation): hindbrain defect where cerebellar tonsils herniate ≥3-5 mm below the foramen magnum, type 1 most common, prevalence 0.24-2.6%, treated by posterior fossa decompression with or without duraplasty.
CHIEDZA trial
The CHIEDZA trial, led from Harare and the London School of Hygiene & Tropical Medicine, tested community-based HIV and sexual health services for 16 to 24-year-olds in Zimbabwe from 2019 to 2022.