Medical Dictionary

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necrometer (ne-krom′e-ter)
An instrument for measuring a dead body or any of its parts or organs. [necro- + G. metron, measure]

necroparasite (nek-ro-par′a-sit)
SYN: saprophyte.

necropathy (ne-krop′a-the)
A tendency to tissue death or gangrene. [necro- + G. pathos, disease]

necrophagous (ne-krof′a-gus)
1. Living on carrion. 2. SYN: necrophilous. [necro- + G. phago, to eat]

necrophilia, necrophilism (nek-ro-fil′e-a, ne-krof′i-lizm)
1. A morbid fondness for being in the presence of dead bodies. 2. The impulse to have sexual contact, or the act of such contact, with a dead body, usually of males with female corpses. [necro- + G. phileo, to love]

necrophilous (ne-krof′i-lus)
Having a preference for dead tissue; denoting certain bacteria. SYN: necrophagous (2) . [necro- + G. philos, fond]

necrophobia (nek-ro-fo′be-a)
Morbid fear of corpses. [necro- + G. phobos, fear]

necropsy (nek′rop-se)
SYN: autopsy (1) . [necro- + G. opsis, view]

necrosadism (nek-ro-sad′izm)
Sexual gratification derived by mutilating corpses. [necro- + sadism]

necroscopy (ne-kros′ko-pe)
Rarely used term for autopsy. [necro- + G. skopeo, to examine]

necrose (ne-kroz′)
1. To cause necrosis. 2. To become the site of necrosis.

necrosectomy (ne-kro′sek-to-me)
Resection of necrotic tissue.

necrosis (ne-kro′sis)
Pathologic death of one or more cells, or of a portion of tissue or organ, resulting from irreversible damage; earliest irreversible changes are mitochondrial, consisting of swelling and granular calcium deposits seen by electron microscopy; most frequent visible alterations are nuclear: pyknosis, shrunken and abnormally dark basophilic staining; karyolysis, swollen and abnormally pale basophilic staining; or karyorrhexis, rupture and fragmentation of the nucleus. After such changes, the outlines of individual cells are indistinct, and affected cells may become merged, sometimes forming a focus of coarsely granular, amorphous, or hyaline material. [G. nekrosis, death, fr. nekroo, to make dead] acute massive liver n. a lesion in which there is extensive and rapid death of parenchymal cells of the liver, sometimes with fatty degeneration of the size of the organ; the n. may result from fulminant viral infection or chemical poisoning; associated with jaundice. SYN: acute parenchymatous hepatitis, acute yellow atrophy of the liver, Rokitansky disease (1) . acute retinal n. (ARN) a viral syndrome occurring in immunocompetent patients, characterized by peripheral retinal destruction that becomes circumferential and leads to retinal detachment. aseptic n. n. occurring in the absence of infection. avascular n. n. due to deficient blood supply. bridging hepatic n. area of liver n. that bridges adjacent portal areas and central veins; subsequent postnecrotic collapse and fibrosis is likely to result in cirrhosis. caseous n., caseation n. n. characteristic of certain inflammations ( e.g., tuberculosis, histoplasmosis), which represents n. with loss of separate structures of the various cellular and histologic elements; affected tissue manifests the friable, crumbly consistency and dull, opaque quality observed in cheese. SYN: caseous degeneration. central n. n. involving the deeper or inner portions of a tissue, or an organ or its units. coagulation n. a type of n. in which the affected cells or tissue are converted into a dry, dull, fairly homogeneous eosinophilic mass without nuclear staining, as a result of the coagulation of protein as occurs in an infarct; microscopically, the necrotic process involves chiefly the cells, and remnants of histologic elements ( e.g., elastin, collagen, muscle fibers) may be recognizable, as well as “ghosts” of cells and portions of cell membranes; may be caused by heat, ischemia, and other agents that destroy tissue, including enzymes that would continue to alter the devitalized cellular substance. colliquative n. obsolete term for liquefactive n.. contraction band n. SYN: contraction band. cystic medial n. loss of elastic and muscle fibers in the aortic media, with accumulation of mucopolysaccharide, sometimes in cystlike spaces between the fibers; a disease of unknown cause, which may be inherited and which predisposes to dissecting aneurysms. SYN: Erdheim disease, medionecrosis aortae idiopathica cystica, medionecrosis of the aorta, mucoid medial degeneration. epiphysial aseptic n. aseptic n. of bony epiphyses in children or adults probably due to ischemia; it may affect the upper end of the femur (Legg-Calvé-Perthes disease), the tibial tubercle (Osgood-Schlatter disease), the tarsal navicular bone or the patella (Köhler disease), the second metatarsal head (Freiberg disease), vertebral bodies (Scheuermann disease), or the capitellum of the humerus (Panner disease). fat n. the death of adipose tissue, characterized by the formation of small (1–4 mm), dull, chalky, gray or white foci; these represent small quantities of calcium soaps formed in the affected tissue when fat is hydrolyzed into glycerol and fatty acids. SYN: steatonecrosis. fibrinoid n. n. in which the necrotic tissue has some staining reactions resembling fibrin and becomes deeply eosinophilic, homogenous, and refractile. focal n. occurrence of numerous, relatively small or tiny, fairly well-circumscribed, usually spheroidal portions of tissue that manifest coagulative, caseous, or gummatous n. and are characteristically associated with agents that are hematogenously disseminated; frequently observed only in histologic sections, but the foci may be as large as 1–3 mm and macroscopically visible; arbitrarily, foci larger than that are usually not termed focal n.. ischemic n. n. caused by hypoxia resulting from local deprivation of blood supply, as by infarction. laminar cortical n. the breaking down of a definite cell layer in the cerebral cortex, encountered typically after temporary cardiac arrest or perinatal hypoxia. liquefactive n. a type of n. characterized by a fairly well-circumscribed, microscopically or macroscopically visible lesion that consists of the dull, opaque or turbid, gray-white to yellow-gray, soft or boggy, partly or completely fluid remains of tissue that became necrotic and was digested by enzymes, especially proteolytic enzymes liberated from disintegrating leukocytes; it is classically observed in abscesses, and frequently in infarcts of the brain. progressive emphysematous n. SYN: gas gangrene. progressive outer retinal n. (PORN) a viral syndrome occurring in AIDS patients, caused by herpesvirus and characterized by destruction of peripheral retina. renal papillary n. n. of renal papillae, occurring in acute pyelonephritis, especially in diabetics, or in analgesic nephropathy; renal failure may result. SYN: necrotizing papillitis. simple n. a stage of coagulation n.; the occurrence of a coarsely granular or hyaline change in the cytoplasm, and the lack of a recognizable nucleus, with the general configuration of the dead cells being relatively unchanged. subcutaneous fat n. of newborn indurated plaques and nodules appearing usually a few days or a few weeks after birth and usually resolving within a few months, characterized microscopically by birefringent needle-shaped crystals within necrotic fat cells; the condition remains localized, unlike sclerema neonatorum, although hypercalcemia may develop. suppurative n. liquefactive n. with pus formation. total n. 1. complete n. of the cytologic and histologic elements in a portion of tissue, as in caseous n.; 2. death of an entire organ or part. zonal n. n. predominantly affecting or limited to an anatomical zone, especially parts of the hepatic lobules defined according to proximity to either the portal tracts or central (hepatic) veins.

necrospermia (nek-ro-sper′me-a)
A condition in which there are dead or immobile spermatozoa in the semen. [necro- + G. sperma, seed]

necrosteon, necrosteosis (ne-kros′te-on, ne-kros-te-o′sis)
Gangrene of bone. [necro- + G. osteon, bone]

necrotic (ne-krot′ik)
Pertaining to or affected by necrosis.

necrotomy (ne-krot′o-me)
1. SYN: dissection. 2. Operation for the removal of a necrosed portion of bone (sequestrum). [necro- + G. tome, cutting] osteoplastic n. removal of a bone sequestrum through a hinged window of bone which is then replaced.

needle (ne′dl)
1. A slender, solid, usually sharp-pointed instrument used for puncturing tissues, suturing, or passing a ligature around or through a vessel. 2. A hollow n. used for injection, aspiration, biopsy, or to guide introduction of a catheter into a vessel or other space. 3. To separate the tissues by means of one or two needles, in the dissection of small parts. 4. To perform discission of a cataract by means of a knife n.. [M.E. nedle, fr. A.S. naedl] aneurysm n., artery n. a blunt-pointed, curved n., set in a handle, with the eye at the point, used for passing a ligature around an artery. aspirating n. a hollow n. used for withdrawing fluid from a cavity, when combined with an aspirator tube attached to one end. atraumatic n. an eyeless surgical n. with the suture permanently fastened into a hollow end. biopsy n. a hollow n. used to obtain a core of tissue for histologic study. cataract n. SYN: knife n.. cutting n. a surgical n. with angulated surface designed to puncture tough tissue. Deschamps n. a n. with a long shaft for passing sutures in the deep tissues. Emmet n. a strong n. with the eye in the point, having a wide curve, and set in a handle, used to pass a ligature around an undissected structure. exploring n. a strong n. with a longitudinal groove, which is thrust into a tumor or cavity to determine the presence of fluid, the latter escaping along the groove. Francke n. a small lancet-shaped, spring-activated n., used to evacuate a small effusion of blood. Frazier n. a n. for draining lateral ventricles of brain. Gillmore n. a device for obtaining the setting time of dental cement. Hagedorn n. a curved surgical n. flattened on the sides. hypodermic n. a hollow n., similar to but smaller than an aspirating n., attached to a syringe; used primarily for injection. knife n. a very narrow, n.-pointed knife used in discission of a cataract. SYN: cataract n.. lumbar puncture n. a n., provided with a stylet, for entering the spinal canal or cisterna magna, with a bore of at least 1 mm and 40 mm or more in length. Millner n. a fine, non-cutting n. with eye for thread frequently used for suture of skin. Salah sternal puncture n. a wide-bore n. for obtaining samples of red marrow from the sternum. spatula n. a minute n. with a flat (noncutting) concave surface, used by eye surgeons. stop-n. a surgical n., with the eye at the tip, the shank of which has a projecting shelf to arrest the n. when it has passed the desired distance through the tissues. Tuohy n. a n. with a lateral opening at the distal end, designed to cause a catheter passing through the n.'s lumen to exit laterally at a 45° angle; used to place catheters into the subarachnoid or epidural space. Veress n. a n. equipped with a spring loaded obturator that is used for insufflation of the abdomen in laparoscopic surgery.

needle-holder, needle-carrier, needle-driver
A hand-held instrument for grasping a needle in suturing. SYN: needle forceps.

Needles
J.W., U.S. dentist. See N. split cast method.

Needles
Carl F., U.S. pediatrician, *1935. See Melnick-N. osteodysplasty, Melnick-N. syndrome.

needling (ned′ling)
Discission of a soft or secondary cataract.

Neelsen
Friedrich K.A., German pathologist, 1854–1894. See Ziehl-N. stain.

neencephalon (ne-en-sef′a-lon)
Edinger term for the higher levels of the central nervous system superimposed upon the metameric or propriospinal system (paleencephalon). SYN: neoencephalon. [G. neos, new, + enkephalos, brain]

NEEP
Abbreviation for negative end-expiratory pressure.

nefopam hydrochloride (nef′o-pam)
An analgesic agent.

Neftel
William B., U.S. neurologist, 1830–1906.

negation (ne-ga′shun)
SYN: denial.

negative (neg′a-tiv)
1. Not affirmative; refutative; not positive; not abnormal. 2. Denoting failure of response, absence of a reaction, or absence of an entity or condition in question. [L. negativus, fr. nego, to deny]

negative G
Gravity in a foot-to-head direction in flying, or in standing on one's head; opposite of positive G.

negative S
SYN: flotation constant.

negativism (neg′a-tiv-izm)
A tendency to do the opposite of what one is requested to do, or to stubbornly resist for no apparent reason; seen in catatonic states and in toddlers.

negatron (neg′a-tron)
Term used for an electron to emphasize its negative charge in contradistinction to the positive charge carried by the otherwise similar positron.

Negri
Adelchi, Italian physician, 1876–1912. See N. bodies, under body, N. corpuscles, under corpuscle.

Negro
Camillo, Italian neurologist, 1861–1927. See N. phenomenon.

Neisser
Albert L.S., German physician, 1855–1916. See Neisseria, N. coccus, N. syringe.

Neisser
Max, German bacteriologist, 1869–1938. See N. stain.

Neisseria (ni-se′re-a)
A genus of aerobic bacteria (family Neisseriaceae) containing Gram-negative cocci which occur in pairs with the adjacent sides flattened. These organisms are parasites of animals. The type species is N. gonorrhoeae. [A. Neisser] N. catarrhalis former name for Moraxella catarrhalis. N. caviae a bacterial species found in the pharyngeal region of guinea pigs; may also be found in other animals. N. flava a bacterial species found in the mucous membranes of the human respiratory tract; easily confused with N. meningitidis. SYN: N. subflava. N. flavescens a bacterial species found in cerebrospinal fluid in cases of meningitis; probably occurs in the mucous membranes of the human respiratory tract. N. gonorrhoeae a bacterial species that causes gonorrhea and other infections in humans; the type species of the genus N.. SYN: gonococcus, Neisser coccus. N. haemolysans former name for Gemella haemolysans. See Gemella. N. meningitidis a bacterial species found in the nasopharynx of humans but not in other animals; the causative agent of meningococcal meningitis and meningicoccemia; virulent organisms are strongly Gram negative and occur singly or in pairs; in the latter case the cocci are elongated and are arranged with long axes parallel and facing sides kidney shaped; groups characterized by serologically specific capsular polysaccharides are designated by capital letters (the main serogroups being A, B, C, and D). SYN: meningococcus, Weichselbaum coccus. N. sicca a bacterial species found in the mucous membranes of the human respiratory tract. N. subflava SYN: N. flava.

neisseria, pl .neisseriae (ni-se′re-a, ni-se′re-e)
A vernacular term used to refer to any member of the genus N..

Nélaton
Auguste, French surgeon, 1807–1873. See N. catheter, N. fibers, under fiber, N. line, N. sphincter, Roser-N. line.

Nelson
Don H., U.S. internist, *1925. See N. syndrome, N. tumor.

nem
A nutritional unit defined as 1 gram breast milk of specific nutritional components having a caloric value equivalent to 23 calorie. [Ger. Nahrungseinheit Milch, milk nutrition unit]

nema-, nemat-, nemato-
Thread, threadlike. [G. nema]

nemathelminth (nem-a-thel′minth)
A member of the former phylum Nemathelminthes.

Nemathelminthes (nem′a-thel-min′thez)
Formerly considered a phylum to incorporate the pseudocelomate organisms, which now are divided into the distinct phyla Acanthocephala, Entoprocta, Rotifera, Gastrotricha, Kinorhyncha, Nematoda, and Nematomorpha. [nemat- + G. helmins, helminthos, worm]

nematicidal, nematocidal (nem′a-ti-si′dal -to-si′ dal)
Destructive to nematode worms.

nematicide, nematocide (ne-mat′i-sid -o-sid)
An agent that kills nematodes. [nematode + L. caedo, to kill]

nematization (nem′a-ti-za-shun)
Infestation by nematodes.

nematoblast (nem′ah-to-blast)
SYN: spermatid. [G., nema, thread + blastos, germ]

nematocyst (nem′a-to-sist)
A stinging cell of coelenterates consisting of a poison sac and a coiled barbed sting capable of being ejected and penetrating the skin of an animal on contact; of considerable consequence in large jellyfish and in the Portuguese man-of-war whose large numbers of these stinging cells can cause great pain and even death. SYN: cnida, cnidocyst. [nemato- + G. kystis, bladder]

Nematoda (nem-a-to′da)
The roundworms, a large phylum that includes many of the helminths parasitic in humans and a far greater number of plant-parasitic and free-living soil and aquatic nonparasitic species. For practical purposes, the parasitic nematodes may be placed in two groups, based on their adult habitat in the human body: 1) the intestinal roundworms ( e.g., the genera Ascaris, Trichuris, Ancylostoma, Necator, Strongyloides, Enterobius, and Trichinella); and 2) the filarial roundworms of the blood, lymphatic tissues, and viscera ( e.g., the genera Wuchereria, Mansonella, Loa, Onchocerca, and Dracunculus). [nemat- + G. eidos, form]

nematode (nem′a-tod)
A common name for any roundworm of the phylum Nematoda.

nematodiasis (nem′a-to-di′a-sis)
Infection with nematode parasites. cerebrospinal n. invasion of the central nervous system by wandering nematode larvae; e.g., Angiostrongylus cantonensis in rats and humans.

Nematodirella longispiculata (ne′ma-to-di-rel′a lon′gi-spik-u-la′ta)
One of the thread-necked trichostrongyle nematodes in the small intestine of sheep, goats, reindeer, moose, musk ox, and pronghorn.

nematoid (nem′a-toyd)
Relating to nematodes.

nematologist (nem-a-tol′o-jist)
A specialist in nematology.

nematology (nem-a-tol′o-je)
The science concerned with all aspects of nematodes, their biology, and their importance to humans. [nematode + G. logos, study]

nematospermia (nem′a-to-sper′me-a)
Spermatozoa with an elongated tail, as in humans, in contrast to spherospermia. [nemat- + G. sperma, seed]

Némethy
George, Hungarian-U.S. biochemist, *1934. See Adair-Koshland-N.-Filmer model, Koshland-N.-Filmer model.

neo-
New, recent. [G. neos]

neoadjuvant (ne-o-ad′joo-vant)
Chemotherapy or radiation given before cancer surgery. [neo- + adjuvant]

neoantigens (ne-o-an′ti-jenz)
SYN: tumor antigens, under antigen.

neoarsphenamine (ne′o-ar-sfen′a-men)
Formerly used as an antisyphilitic agent.

neoarthrosis (ne-o-ar-thro′sis)
SYN: nearthrosis.

Neoascaris vitulorum (ne-o-as′ka-ris vit-u-lo′rum)
The large roundworm occurring in the small intestine of cattle, water buffalo, and (rarely) sheep; although uncommon in the U.S., it is a serious cattle parasite in many other areas. Experimental infection has been produced in rodents and humans.

neobiogenesis (ne′o-bi-o-jen′e-sis)
The theory that life can originate from nonliving matter. [neo- + G. bios, life, + genesis, origin]

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