necrosis


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necrosis

1. the death of one or more cells in the body, usually within a localized area, as from an interruption of the blood supply to that part
2. death of plant tissue due to disease, frost, etc.

Necrosis

 

the death within the living organism of individual organs or their component tissues or cells.

A necrosis is classified according to the pathological condition that causes it. Thus, frostbite and burns can cause traumatic necrosis; neurotropic necrosis arises with syringomyelia and the nervous form of leprosy; infarcts and gangrene are associated with circulatory, or ischemic, necrosis; caseous necroses occurring in tuberculosis and syphilis are forms of septic necrosis; and fibrinoid necrosis associated with allergic diseases is a type of allergic necrosis.

Necrosis is accompanied by characteristic changes in the cell and in the intercellular substances. The nucleus shrinks and coagulates, a process known as pycnosis, and the cytoplasm breaks up into clumps. The cell eventually lyses, that is, it degenerates and dissolves. The lysis is due to the activation of the lysosomal hydrolytic enzymes, such as ribonuclease, deoxyribonuclease, and acid phosphatase. The activation of the lysosomes occurs as a result of an increase in the permeability of the cell membranes, changes in the osmotic equilibrium, and acidosis—an abnormal increase in the intracellular hydrogen-ion concentration. Fibrinoid changes appear in the connective tissue, and nerve fibers become fragmented and disintegrate into clumps.

The clinical and morphological manifestations and further consequences of necrosis depend on the localization and distribution of the necrosis and on the mechanisms and conditions of origin. The following types of advanced necrotic conditions can develop: dry necrosis, such as Zenker’s degeneration of infected muscles; colliquative, or liquefactive, necrosis, which occurs for example, when a focus of softening arises in the brain in response to cerebral hemorrhage; gangrene; and bed sores. Necrotic tissue tears away; then, either connective tissue grows through it or the necrotic tissue undergoes autolytic or purulent liquefaction. Finally, the necrotic tissue becomes encapsulated and petrified.

The two most serious consequences of necrosis are a loss of function owing to the death of the structural elements of the necrotic tissues or organs and poisoning caused by the actual presence of a necrotic focus and by the inflammation that arises in response to this presence.

V. V. SEROV

necrosis

[nə′krō·səs]
(medicine)
Death of a cell or group of cells as a result of injury, disease, or other pathologic state.
References in periodicals archive ?
Disrupted muscle fibers undergo focal or total necrosis depending upon the magnitude of the damage15.
However, the study population in most of the previous studies included patients with infected necrosis, whereas the current study comprised PCD as a bridge to surgery even in the absence of documented infection.
Improvement rates of symptoms of patients with complete necrosis after UAE were remarkably higher than those of patients with incomplete necrosis.
Depending on the size of necrosis in the cecum and the presence of peritonitis findings, partial cecum resection of the retained cecum, segmental colon resection, or right hemicolectomy may be performed.
The walled-off pancreatic necrosis was diagnosed on the basis of the revised Atlanta classification from 2012 [4, 5].
A specific PET imaging parameter termed "metabolic tumor/necrosis ratio" was developed to quantify the presence of coagulative tumor cell necrosis in LMS/STUMP (Figure 1(a)) and calculated with an automated approach (Figure 1(b)) as follows:
Recent literature suggests that RIP3 binds to the apoptosis-inducing factor (AIF) nuclear pathway which is also involved in the process of procedural necrosis [14].
The exact incidence of uterine necrosis after UAE is difficult to ascertain with only a handful of cases reported in literature [6, 10].
Nodular-cystic fat necrosis. A reevaluation of the so-called mobile encapsulated lipoma.
(12) Since subcutaneous fat necrosis does not occur in all neonates with the two predisposing factors found in our patient, additional predisposing factors most likely exist.
Based on various studies, this protein is used in form of spray or direct injection into the plant and Usually 24h after the entrance of NLP into the vascular system of plant, the signaling cascades initiated within the plant which leads to higher expression of 1-Amino Cyclopropane-1-Carboxylate Synthase and ACC oxidase enzymes, ethylene production, MAP kinase activation, phytoalexin synthesis and intracellular calcium increase, which eventually cause extensive necrosis of plant tissue (Wang et al.