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Human health and medicine

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Acetabular reconstruction

Acetabular reconstruction is the surgical rebuilding of the hip socket (acetabulum) after bone loss, using impaction bone grafting, jumbo cups, cages, or 3D-printed components to restore bone stock.

Acetabuloplasty

Acetabuloplasty is a pelvic osteotomy that reshapes or augments the hip socket to improve femoral head coverage in children and young adults with acetabular dysplasia.

Acetabulum

The acetabulum, or cotyloid cavity, is the cup-shaped socket of the hip bone, formed where the ilium, ischium, and pubis meet, that holds the femoral head in the hip joint.

Acetarsone

Acetarsone (acetarsol, stovarsol), a pentavalent organoarsenical antiprotozoal drug discovered by Ernest Fourneau in 1921, used against amebiasis and syphilis, now withdrawn from the market.

Acetazolamide

Acetazolamide (Diamox) is a sulfonamide carbonic anhydrase inhibitor discovered in 1950, FDA-approved for epilepsy in 1953, used for glaucoma, edema, epilepsy, and acute mountain sickness prevention; common side effects include paraesthesias, dysgeusia, polyuria, and fatigue.

Acetazolamide-responsive myotonia

Acetazolamide-responsive myotonia, also called painful or atypical myotonia congenita, is a rare autosomal dominant SCN4A (Nav1.4) sodium channelopathy causing childhood-onset painful, potassium-triggered myotonia without weakness, dramatically improved by acetazolamide.

Acetohexamide

Acetohexamide (Dymelor, Cyclamide) is a first-generation, intermediate-acting oral sulfonylurea for type 2 diabetes, metabolized to the more potent active metabolite hydroxyhexamide; discontinued in the US market.

Acetophenazine

Acetophenazine (Tindal, Tindal Maleate) is a discontinued piperazine-substituted phenothiazine antipsychotic, ATC N05AB07, first approved in 1961 by Schering, acting as a D1/D2 receptor blocker.

Acetrizoic acid

Acetrizoic acid (urokonic acid, Urokon), 3-acetamido-2,4,6-triiodobenzoic acid, is the first monomeric ionic X-ray contrast agent, synthesized by Wallingford in 1953; nephrotoxic high-osmolar agent, now discontinued.

Acetylcholine

Acetylcholine (ACh), the first neurotransmitter identified, is a choline ester acting at nicotinic ion-channel and muscarinic GPCR receptors in CNS, autonomic, and neuromuscular synapses; degraded by acetylcholinesterase; central to Alzheimer's and schizophrenia drug development.

Acetylcholine receptor

Acetylcholine receptor: cell-surface proteins activated by acetylcholine, divided into ionotropic nicotinic and G-protein-coupled muscarinic (M1-M5) receptors; targets of nicotine, myasthenia gravis antibodies, and the 2024 antipsychotic KarXT.

Acetylcholinesterase inhibitor

An acetylcholinesterase inhibitor (AChE inhibitor), also called an anticholinesterase, is a drug or toxin that blocks the enzyme breaking down acetylcholine, used in Alzheimer's disease.

Acetylcysteine

Acetylcysteine (N-acetylcysteine, NAC; Mucomyst, Fluimucil, Acetadote) is a sulfhydryl mucolytic drug, patented 1960, and the standard antidote for acetaminophen overdose, dosed 300 mg/kg IV.

Acetyldigitoxin

Acetyldigitoxin (Acylanid, alpha-acetyldigitoxin) is a cardiac glycoside, an acetyl derivative of digitoxin prepared from lanatoside A of Digitalis lanata, used for fast digitalization in heart failure and rate control in atrial arrhythmias; ATC C01AA01, now discontinued.

Acexamic acid

Acexamic acid (6-acetamidohexanoic acid, CAS 57-08-9) is a medium-chain fatty acid drug used as a wound-healing (cicatrizing) agent; its zinc salt treats gastric and duodenal ulcers.

Achalasia-microcephaly syndrome

Achalasia-microcephaly syndrome (OMIM 200450, ORPHA:929), also called Asherson syndrome, is an extremely rare autosomal recessive disorder combining microcephaly, intellectual disability, and esophageal achalasia, first described in 1978 in northwest Mexico, with fewer than 10 reported cases.

Achilles tendinitis

Achilles tendinitis, also called Achilles tendinopathy, is a degenerative overload injury of the Achilles tendon causing heel and calf pain. Treated mainly with calf exercise therapy; fluoroquinolones and aging raise risk.

Achilles tendon

Achilles tendon, or calcaneal tendon (tendo calcaneus), the thickest tendon, connecting calf muscles to the heel bone; named by Verheyen in 1693; rupture treated operatively or nonoperatively with differing re-rupture and complication rates.

Achilles tendon repair

Achilles tendon repair is the surgical treatment for a ruptured Achilles tendon, done by open, percutaneous, or mini-open techniques that rejoin the torn tendon ends with sutures.

Achilles tendon rupture

Rupture of the Achilles tendon, a tear of the calf-to-heel tendon, typically 2–6 cm above the calcaneus during sports; treated operatively or nonoperatively with functional rehabilitation, recovery 4–6 months.

Achlorhydria

Achlorhydria, also called total gastric acid absence (ICD-11 DA41.3), is the complete lack of stomach hydrochloric acid, usually from pernicious anemia, PPIs, or H. pylori, causing malabsorption, B12 and iron deficiency, and gastric cancer risk.

Achondrogenesis

Achondrogenesis: a group of lethal skeletal dysplasias (types 1A TRIP11, 1B SLC26A2, 2 COL2A1) causing deficient endochondral ossification, extreme micromelia, small thorax, and perinatal death; about 1 in 40,000-60,000 newborns.

Achromatopsia

Achromatopsia (ACHM, rod monochromatism, total color blindness) is a rare autosomal recessive retinal disorder of cone photoreceptors causing color blindness, low acuity, photophobia, and nystagmus; mainly caused by CNGA3 and CNGB3 variants, with gene therapy trials underway.

Aciclovir

Aciclovir (acyclovir, Zovirax) is an acyclic nucleoside antiviral for cold sores, shingles, chickenpox, genital herpes, and HSV eye infections; activated by viral thymidine kinase, it inhibits herpesvirus DNA polymerase with 300-3000-fold selectivity.

Acid hypersecretion

Acid hypersecretion (ICD-11 DA41.2), basal overproduction of gastric acid causing peptic ulcer and steatorrhoea; idiopathic when BAO >10 mmol/h without hypergastrinemia; treated mainly with PPIs.

Acid-Base Equilibrium

Acid-base equilibrium, or acid-base homeostasis, is the physiological steady state of hydrogen ion concentration maintained by buffers, lungs, and kidneys, analyzed via Henderson-Hasselbalch or Stewart approaches.

Acidosis

Acidosis: pathologic acid accumulation or alkali loss lowering blood pH, classified as respiratory (CO2 retention from hypoventilation) or metabolic (low bicarbonate); diagnosed by blood gas, anion gap, and compensation formulas.

Acinar cell carcinoma of pancreas

Acinar cell carcinoma of the pancreas (PACC) is a rare malignant exocrine pancreatic tumor of enzyme-producing acinar cells, about 1–2% of adult pancreatic cancers, with low KRAS mutation rates, trypsin/BCL10-positive immunohistochemistry, and a prognosis better than PDAC but worse than neuroendocrine tumors.

Acinar cystic transformation of the pancreas

Acinar cystic transformation of the pancreas, also called acinar cell cystadenoma, is a rare benign cystic lesion of the pancreas, first described in 2002 and reclassified as non-neoplastic in 2019.

ACIOS study

ACIOS (African Critical Illness Outcomes Study), NCT06051526, a Lancet-published 2023 point prevalence study of 19,872 adults in 180 hospitals across 22 African nations: 12.5% critically ill, 20.7% 7-day mortality, most in general wards with unmet essential care.