| Marcus Gunn pupil | Relative afferent pupillary defect. Synonym: Gunn pupil. (05 Mar 2000) |
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| Marcus Gunn syndrome | <syndrome> An increase in the width of the eye lids during chewing, sometimes with a rhythmic elevation of the upper lid when the mouth is open and ptosis when the mouth is closed. Synonym: Gunn phenomenon, Gunn's syndrome, jaw-winking phenomenon, jaw-working reflex, Marcus Gunn phenomenon, Marcus Gunn syndrome. (05 Mar 2000) |
| Marcus Gunn's sign | <clinical sign> Compression of the underlying vein at arteriovenous crossings seen ophthalmoscopically in arteriolar sclerosis, on alternate stimulation with light, the pupil of an eye with optic nerve transmission defect constricts poorly or even dilates when stimulated (a relative afferent pupillary defect). Synonym: Marcus Gunn's sign. (05 Mar 2000) |
| mare | The female of the horse and other equine quadrupeds. Origin: OE. Mere, AS. Mere, myre, fem of AS. Mearh horse, akin to D. Merrie mare, G. Mahre, OHG. Marah horse, meriha mare, Icel. Marr horse, OCelt. Marka (Pausan. 19, 19,4), Ir. Marc, W. March. Cf. Marshal. <medicine> Sighing, suffocative panting, intercepted utterance, with a sense of pressure across the chest, occurring during sleep; the incubus; obsolete, except in the compound nightmare. "I will ride thee o' nights like the mare." (Shak) Origin: AS. Mara incubus; akin to OHG. & Icel. Mara; cf. Pol. Mora, Bohem. Mra. Source: Websters Dictionary (01 Mar 1998) |
| mare's-tail | 1. A long streaky cloud, spreading out like a horse's tail, and believed to indicate rain; a cirrus cloud. See Cloud. "Mackerel sky and mare's-tails Make tall ships carry low sails." (Old Rhyme) 2. <botany> An aquatic plant of the genus Hippuris (H.vulgaris), having narrow leaves in whorls. Source: Websters Dictionary (01 Mar 1998) |
| Marek disease | <disease> Infectious cancer of the lymphoid system (lymphomatosis) in chickens, caused by a contagious Herpes virus. An effective vaccine is now available. (18 Nov 1997) |
| marek's disease | A lymphoproliferative disease of fowl caused by a herpes virus. Lymphoid cell infiltrations are most common in the peripheral nerves and gonads, but widespread infiltrations may also be found in any of the visceral organs, skin, muscle, and the iris of the eye. The location of the lesions dictates the clinical signs, such as paralysis, general depression, and blindness. (12 Dec 1998) |
| Marek's disease virus | The herpesvirus that causes avian lymphomatosis (Marek's disease); is distinct from those causing other forms of leukosis. Synonym: avian lymphomatosis virus, fowl neurolymphomatosis virus, Marek's disease virus. (05 Mar 2000) |
| Marek, Josef | <person> Hungarian veterinarian and pathologist, 1867-1952. See: Marek's disease, Marek's disease virus. (05 Mar 2000) |
| marena | <zoology> A European whitefish of the genus Coregonus. Origin: NL. Salmo maraena, G. Marane, morane; so called from Lake Morin, in the March of Brandenburg, in Prussia. Source: Websters Dictionary (01 Mar 1998) |
| Marey's law | The pulse rate varies inversely with the blood pressure; i.e., the pulse is slow when the pressure is high; an expression of baroreceptor reflex influences on heart rate. (05 Mar 2000) |
| Marey, Etienne Jules | <person> French physiologist, 1830-1904. See: Marey's law. (05 Mar 2000) |
| marfan syndrome | <radiology> Connective-tissue disorder: autosomal dominant, 15% sporadic, cardiovascular system (probable cause of death in 93%), aortic aneurysm (mostly ascending), dilatation of aortic sinuses, aortic dissection, coarctation, musculoskeletal system, tall stature, long limbs, arachnodactyly, lax joints, scoliosis (60%) / kyphosis / pectus, eye, lens subluxation Cf: homocystinuria More info: Marfan syndrome (12 Dec 1998) |
| Marfan's disease | <syndrome> A hereditary condition of the connective tissue. Symptoms and signs include tall lean body type, irregular or unsteady gait, long extremities (including fingers and toes), abnormal joint flexibility, flat feet, stooped shoulders, dislocation of the optic lens and aneurysms of the aorta. Affects 1 in 50,000 people. Probably a collagen fibril assembly disorder since it can be mimicked in mice by aminonitriles that interfere with crosslinking. Inheritance: autosomal dominant. (06 Oct 1997) |
| Marfan's law | The healing of localised tuberculosis protects against subsequent development of pulmonary tuberculosis. (05 Mar 2000) |