Medical Conditions Terminology in Category Q

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Quinolone Anti-Infective Agents

A group of synthetic antimicrobial agents which usually contain a 4-quinolinone ring structure. A few compounds belonging to this group have related nitrogen heterocyclic ring structures such as naphthyridine or phthalazine groups. All compounds in this group are substituted with an oxo group at the 4-position. The second-generation quinolones are also substituted with a 1-piperazinyl group at the 7-position and a fluorine moiety at the 6-position. The quinolones inhibit the A subunit of DNA gyrase and thus interfere with the ability of the enzyme to repair bacterial DNA breaks during replication. The compounds have a broad spectrum of activity against a variety of aerobic bacteria.

Quinic Acid

An acid which is found in cinchona bark and elsewhere in plants. (From Stedman, 26th ed)

QH(2)-Ferricytochrome-c Oxidoreductase

An 11-subunit enzyme complex that acts as an electron transferring protein in the mitochondrial respiratory chain. The enzyme complex catalyzes the oxidation of ubiquinol to ubiquinone and ferrocytochrome c in the presence of ferricytochrome c. It contains cytochromes b-562, b-566, and c1 as well as an iron ferredoxin. EC 1.10.2.2.

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QH(2)-Cytochrome-c Reductase

An 11-subunit enzyme complex that acts as an electron transferring protein in the mitochondrial respiratory chain. The enzyme complex catalyzes the oxidation of ubiquinol to ubiquinone and ferrocytochrome c in the presence of ferricytochrome c. It contains cytochromes b-562, b-566, and c1 as well as an iron ferredoxin. EC 1.10.2.2.

QB Protein

A system consisting of proteins and cofactors which facilitates light energy and electron transfer in plants.

QALY

A measurement index derived from a modification of standard life-table procedures and designed to take account of the quality as well as the duration of survival. This index can be used in assessing the outcome of health care procedures or services. (BIOETHICS Thesaurus, 1994)

Q beta Phage

A bacteriophage genus of the family LEVIVIRIDAE, whose viruses contain the longer version of the genome and have no separate cell lysis gene.

Quadriplegia

Severe or complete loss of motor function in all four limbs which may result from BRAIN DISEASES; SPINAL CORD DISEASES; PERIPHERAL NERVOUS SYSTEM DISEASES; NEUROMUSCULAR DISEASES; or rarely MUSCULAR DISEASES. The locked-in syndrome is characterized by quadriplegia in combination with cranial muscle paralysis. Consciousness is spared and the only retained voluntary motor activity may be limited eye movements. This condition is usually caused by a lesion in the upper BRAIN STEM which injures the descending cortico-spinal and cortico-bulbar tracts.

Quadriparesis

Severe or complete loss of motor function in all four limbs which may result from BRAIN DISEASES; SPINAL CORD DISEASES; PERIPHERAL NERVOUS SYSTEM DISEASES; NEUROMUSCULAR DISEASES; or rarely MUSCULAR DISEASES. The locked-in syndrome is characterized by quadriplegia in combination with cranial muscle paralysis. Consciousness is spared and the only retained voluntary motor activity may be limited eye movements. This condition is usually caused by a lesion in the upper BRAIN STEM which injures the descending cortico-spinal and cortico-bulbar tracts.

Quadrantanopsia

Partial or complete loss of vision in one half of the visual field(s) of one or both eyes. Subtypes include altitudinal hemianopsia, characterized by a visual defect above or below the horizontal meridian of the visual field. Homonymous hemianopsia refers to a visual defect that affects both eyes equally, and occurs either to the left or right of the midline of the visual field. Binasal hemianopsia consists of loss of vision in the nasal hemifields of both eyes. Bitemporal hemianopsia is the bilateral loss of vision in the temporal fields. Quadrantanopsia refers to loss of vision in one quarter of the visual field in one or both eyes.