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Hallucigenia
Hallucigenia, genus Hallucigenia sparsa, a spiny Cambrian lobopodian worm from the Burgess Shale about 508 million years old, famously first reconstructed upside down and back to front, with its true head identified in 2015 and claw anatomy linking it to velvet worms.
Hallucination
Hallucination: a sensory perception without an external stimulus, in any modality. Also called voice hearing (auditory). Occurs in ~9.6% of the general population lifetime, 80% in schizophrenia; not pathognomonic of any disorder.
Hallucinogen
Hallucinogens are drugs that profoundly alter perception, mood, and thought, including classic psychedelics (LSD, psilocybin, DMT), dissociatives (ketamine, PCP), MDMA, and atypical agents like ibogaine, with history, effects, risks, and regulation.
Hallucinogen dependence
Hallucinogen dependence is a disorder of dysregulated hallucinogen use, marked by impaired control, use taking precedence over other pursuits, and persistence despite harm; ICD-11 classifies it under code 6C49.2.
Hallucinogen intoxication
Hallucinogen intoxication (ICD-11 6C49.3) is a transient condition during or shortly after hallucinogen use, with perceptual, cognitive, and autonomic disturbances; managed mainly with reassurance and benzodiazepines, with hyperthermia and tachydysrhythmias as key dangers.
Hallucinogen persisting perception disorder
Hallucinogen persisting perception disorder (HPPD), formerly post-hallucinogen perception disorder or flashback syndrome, is a DSM-5 disorder (292.89, F16.983) of persistent re-experienced perceptual disturbances after hallucinogen use, with intact reality testing, roughly 4% estimated prevalence, and antipsychotics worsening symptoms.
Hallucinogen-induced anxiety disorder
Hallucinogen-induced anxiety disorder (ICD-11 6C49.61) is a substance-induced anxiety disorder with symptoms during or soon after hallucinogen intoxication, exceeding intoxication-level anxiety and not better explained by a primary disorder.
Hallucinogen-induced mood disorder
Hallucinogen-induced mood disorder (ICD-11 6C49.60) is mood disturbance, depressive, manic, or mixed, arising during or soon after hallucinogen intoxication, distinguished from primary mood disorders by resolution after cessation of use.
Hallucinogen-induced psychotic disorder
Hallucinogen-induced psychotic disorder (ICD-11 6C49.5): psychotic symptoms such as delusions and hallucinations arising during or soon after hallucinogen intoxication, with 26% pooled transition to schizophrenia.
Hallucinogenic bolete mushroom
Hallucinogenic bolete mushrooms, chiefly Lanmaoa asiatica of Yunnan and Boletus manicus of Papua New Guinea, cause hallucinations of little people when undercooked, with no identified psychedelic compound.
Hallucinogenic fish
Hallucinogenic fish, or ichthyoallyeinotoxism, is rare fish poisoning from species like Sarpa salpa (dreamfish, salema porgy), Siganus spinus, and Kyphosus, causing vivid hallucinations, nightmares, and delirium within minutes to 2 hours, lasting up to 24 hours.
Hallucinogenic snuff
Hallucinogenic snuff (yopo, cohoba, paricá) is a powdered tryptamine preparation inhaled nasally, made from Anadenanthera peregrina seeds rich in bufotenine; used ritually in South America and the pre-Columbian Caribbean for millennia.
Hallux rigidus
Hallux rigidus is osteoarthritis of the joint at the base of the great toe, causing pain, stiffness, and limited upward bending; it mainly develops after age 40.
Hallux valgus surgery
Hallux valgus surgery is a set of orthopedic procedures that realign a deviated big toe, or bunion, by cutting and repositioning bone, balancing soft tissue, or fusing a joint.
Halo blight
Halo blight, also called bacterial halo blight, is a worldwide bean disease caused by Pseudomonas syringae pv. phaseolicola; seedborne, toxin-driven yellow halos, favored by cool humid weather, controlled with certified seed and rotation.
Haloalkaliphilic archaea
Haloalkaliphilic archaea are microorganisms that require both high salt, at least 0.5 mol/L, and alkaline pH around 9, living in soda lakes such as Lake Natron.
Haloalkane Dehalogenase Enzyme
Haloalkane dehalogenases (HLDs, EC 3.8.1.5), also called DhlA, DhaA, LinB family enzymes, are α/β-hydrolase microbial enzymes that hydrolyze carbon-halogen bonds via an aspartate nucleophile, used in bioremediation, biocatalysis, biosensing, and HaloTag protein labeling.
Halobacteriaceae
Halobacteriaceae is a family of halophilic archaea found in salt lakes and brines. Established by N. E. Gibbons in 1974, it was historically the single family containing all archaeal halophiles.
Halobacteriales
Halobacteriales (Grant and Larsen 1989) is an order of extremely halophilic, chemoorganotrophic archaea in the class Halobacteria, type genus Halobacterium; synonyms Haloferacales and Natrialbales, divided by genome analysis into families such as Halobacteriaceae, Haloarculaceae, and Halococcaceae.
Halobacterium
Halobacterium: genus of extremely halophilic archaea (euryarchaeotes), type species H. salinarum, formerly H. halobium; source of bacteriorhodopsin, halorhodopsin, and sensory rhodopsins; type genus of class Halobacteria.
Halobacterium salinarum
Halobacterium salinarum, formerly H. halobium and H. cutirubrum, is an extremely halophilic archaeon from salted fish and salterns, model organism for bacteriorhodopsin, halorhodopsin, and sensory rhodopsins, with the first sequenced haloarchaeal genome (NRC-1).
Halobetasol propionate
Halobetasol propionate: ultra-high potency (class I) synthetic topical corticosteroid (Ultravate, Bryhali, Lexette, Duobrii combination) for plaque psoriasis; 0.05% and 0.01% formulations, two-week to eight-week use limits, 50 g/week cap.
Halobia
Halobia (Bronn, 1830) is a thin-shelled, flat Triassic bivalve genus, cousin of Daonella, used worldwide for Upper Triassic biostratigraphy; not the bacterium Nesterenkonia halobia.
Halocarpus
Halocarpus (monoao, pink pine, bog pine) is a genus of three New Zealand endemic podocarps segregated from Dacrydium by Quinn in 1982, in the Prumnopityoid clade, with inverted epimatium-enclosed seeds and aril-like collars.
Halofantrine
Halofantrine (Halfan, WR171669), a 9-phenanthrenemethanol antimalarial developed by WRAIR and FDA-approved in 1992, treats chloroquine-resistant falciparum and vivax malaria but is now little used because of QT prolongation and fatal cardiotoxicity.
Haloferacales
Haloferacales (Gupta et al. 2015) is an order of extremely halophilic archaea in the class Halobacteria, containing the families Haloferacaceae and Halorubraceae; since 2023 it is merged into Halobacteriales and treated as a synonym.
Haloferax
Haloferax: genus of extremely halophilic archaea in family Haloferacaceae, type species H. volcanii from the Dead Sea; model haloarchaeal genus producing bacterioruberin carotenoids and used in bioremediation and biotechnology.
Haloferax volcanii
Haloferax volcanii, formerly Halobacterium volcanii, is a Dead Sea halophilic archaeon and leading archaeal model organism, with a 2.848 Mb genome plus mini-chromosomes, polyploidy, facile genetics, and biotechnological enzymes.
Halomonas
Halomonas is a genus of salt-tolerant, Gram-negative bacteria established in 1980, with about 68 species that grow in high-salt conditions and serve in industrial biotechnology.
Haloperidol
Haloperidol (Haldol), a butyrophenone typical antipsychotic synthesized at Janssen in Belgium on 11 February 1958 as R-1625, acts via dopamine D2 blockade; WHO essential medicine since 1977 for psychosis, with EPS and QT risks.