Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0344329 (collapse)
 28,634 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Morphological alterations in the lungs of pheasants after prolonged high-dosage administration of bleomycin sulfate were studied by light and electron microscopy. Nontreated birds acted as controls, and their lungs showed no abnormalities. Lungs of bleomycin-treated pheasants revealed collapse alternating with overexpansion, marked cuboidalization of atrial epithelium, and incipient interstitial fibrosis. There were neither lymphoplasmacytic or eosinophilic infiltrates, nor evidence of vasculitis. Ultrastructurally, type 1 alveolar epithelial cells were either reactive or conspicuously absent in the air capillaries. Type 2 alveolar epithelial cells appeared hyperplastic with numerous lamellar bodies, many of which extruded into air spaces. Immature fibroblasts were noted in the vicinity of collagen fibrils or amorphous material resembling elastin. No immune deposits were present in basement membranes. These findings are consistent with a direct toxic effect of bleomycin to the pheasant lung rather than a drug hypersensitivity reaction. Reproduction of the bleomycin lesion in a nonmammalian species corroborates even further the high propensity of the drug to affect the lung.
 ...
PMID:Experimentally induced bleomycin sulfate pulmonary toxicity: histopathologic and ultrastructural study in the pheasant. 6 10

By light and electron microscopical examination it is shown that four structural components can contribute to obsolescent glomeruli: capillary basement membranes, enriched mesangium matrix, "vascular" hyalin and collagen fibers. Each of these components can bring about glomerular damage alone. One non-reactive form--a glomerular collapse with only basement membrane remnants--can be separated from three reactive forms: the accumulation of mesangium matrix (sclerosis or matrix-sclerosis), deposition of vascular hyalin (hyalinosis in the narrow sense), and fiber development within the former urinary space (fibrosis or fibro-sclerosis). The use of the term "fibrinoid" in place of the descriptive term "hyalin" is not supported by objective results. Knowledge of the various constituents which accumulate in the reactive types of glomerular obsolescence might be important in the diagnosis of the underlying disease, though mixed pictures were often observed. To avoid terminological overlap we suggest that the term "hyalinization" is replaced by "obsolescence" or "scarring" with specification of the structural components involved.
 ...
PMID:The obsolescent renal glomerulus--collapse, sclerosis, hyalinosis, fibrosis. A light- and electron microscopical study on human biopsies. 7 8

Hepatic fibrosis may result from collapse after hepatocellular necrosis or from new formation of connective tissue. Fibroplasia, particularly within the lobular parenchyma, is a dynamic process. Newer cellular and biochemical investigations clarified its various steps. The process begins with stimulation of cells to connective tissue formation and can be divided into (1) intracellular synthesis, (2) extracellular maturation, and (3) collagen breakdown. The turnover of the connective tissue in the liver is conspicuously increased in chronic hepatitis of any type, as indicated by an elevation of several cellular and metabolic parameters. They are particularly raised in chronic hepatitis and in alcoholic liver injury. Further development of these parameters in the future should facilitate the analysis of the dynamics of fibroplasia. The strongest stimuli for hepatic fibroplasia are hepatocellular necrosis and inflammation, but ethyl alcohol and steatosis are also stimulating, though to a lesser degree. This explains the particular elevation of the fibroplastic parameters in alcoholic hepatitis. It points, however, also to the possibility that cirrhosis might develop without significant hepatocellular necrosis and inflammation. Perihepatocellular, periductular, and septal fibrosis are the functionally most important localizations leading to additional hepatic injury. The initiation of these types of fibrosis by liver injury points to a vicious circle. Specific anti-fibroplastic therapy is still in infancy.
 ...
PMID:[Hepatic fibrosis--mechanism, dynamics and clinical consequences (author's transl)]. 20 39

Tooth germs grown in ascorbate deficient medium for up to 20 days underwent progressive and widespread changes. Proliferation and differentiation of preameloblasts and preodontoblasts progressed normally. Newly differentiated odontoblasts, however, became vacuolated when they began secreting: this suggested a metabolic disturbance. Failure to maintain differentiated odontoblasts, ameloblasts and pulpal cells resulted in aberrant dentin matrix, cessation of dentin production, and finally overall structural collapse with loss of normal morphology. Biochemical studies then were undertaken to define the lesion involved. The relative rate of collagen synthesis in ascorbate deficient cultures was comparable to that of ascorbate supplemented cultures, but the collagen was found to be underhydroxylated. In this state it would be unstable at 37 degrees and subject to preferential degradation. This correlates with the observation that a major fraction of the hydroxyproline in the scorbutic cultures was found in the medium as small molecular weight peptides. The overall effect of ascorbate deficiency was to deprive the tooth germ of the normal quality and quantity of collagen resulting in the characteristic histological and structural abnormalities observed. Flattening and deterioration due to structural failure most likely resulted from abnormal extracellular matrix synthesis in the supportive pulp and dentin due to the aberrant collagen.
 ...
PMID:The role of ascorbic acid on the structural integrity of developing tooth germs. 28 67

Pregnant rats received the lathyrogen beta-aminopropionitrile (1,500 mg/kg) intraperitoneally on day 16 (plug day = 0 day). Kyphoscoliosis was produced in a high incidence in the fetuses at the level of the upper thoracic spine as early as 24 hours after treatment. Although most of the affected newborns died within two weeks, survivors were studied until 20 weeks after birth. Survivors developed paraplegia in consequence of kyphoscoliosis. Both spinal deformity and motor disturbance were progressive. Biochemical and electron microscopic observations suggested that beta-aminopropionitrile treatment resulted in an inhibition of collagen formation in the spinal column and surrounding longitudinal ligaments of the fetuses six hours after the treatment. In addition, electron micrographs of vertebral bodies showed a decrease of proteoglycan granules in the extracellular matrix. Therefore, rupture and collapse of weakened ligaments and vertebral bodies might result in severe spinal deformity and spinal cord lesion.
 ...
PMID:Congenital kyphoscoliosis and spinal cord lesion produced in the rat by beta-aminopropionitrile. 56 28

Collagen in bulk was isolated in about 30% yield from the livers of normal human beings and from livers of persons with alcholic cirrhosis. Analyzed chemically and examined by electron microscopy, the collagen in each case was shown to consist of two types identical with, or resembling closely, type I and type III collagens of skin. The collagen from normal liver was predominantly type I, whereas, that from cirrhotic livers consisted or approximately equal amounts of the two types. By chromatography on carboxymethyl-cellulose, the type I collagen from the cirrhotic livers showed one alpha2chain and two alpha1 chains. The alpha1 chains were separable from one another, but gel electrophoretic patterns of peptides obtained from them after treatment with CNBr were almost identical, and resembled the pattern obtained with CNBr peptides of the alpha1 chain of rat skin type I collagen. The increased collagen of both types was responsible in part for the observed distortion of the architecture of the cirrhotic livers associated with increased rigidity of the stroma. The predominance of type III collagen in the areas of collapse of architecture where, as shown by others, few fibroblasts are present, suggests that hepatocytes might have an important function in fibrogenesis during the course of liver cirrhosis.
 ...
PMID:Increase in type I and type III collagens in human alcoholic liver cirrhosis. 106 Nov 56

Adult rats received, intraperitoneally, 20 mg/100 g body weight of cyclophosphamide and were killed 1, 2, 3, 4, 7, 14, 21, and 28 days thereafter. Lung samples were studied by light and electron microscopy. Light microscopy revealed septal and intraalveolar hemorrhages at 2 days and hyaline membranes at 4 days. At 1 to 2 weeks the alveoli were reepithelialized; beyond these intervals there was septal thickening with increased septal cells and interstitial substance. Electron microscopy showed capillary endothelial blebs, membranous pneumocyte injury and sloughing, and severe septal edema at 1 to 2 days. At 4 days some granular pneumocytes appeared altered. At 1 week the alveoli were reepithelialized by prominent granular pneumocytes. Beyond these intervals there was septal thickening with abundant septal cells, debris, collagen, elastin and microfibrils. Some septal elements showed features consistent with "contractile interstitial cells." There was also alveolar collapse indicated by "trapped" granular pneumocytes surrounded by septal cells and fibers. Occasional granular pneumocytes showed large intracytoplasmic cavities. Cyclophosphamide can induce severe injury involving all alveolar components. The partly denuded alveoli are reepithelialized by proliferating granular pneumocytes, thus confirming their importance in alveolar repair. The subsequent development of sclerosing alveolitis suggests that cyclophosphamide may offer a useful experimental model for the study of alveolar injury and repair. The role of the septal "contractile interstitial cells" in the development of septal fibrosis and the possibility that these lesions are reversible remain to be clarified.
 ...
PMID:Sclerosing alveolitis induced by cyclophosphamide. Ultrastructural observations on alveolar injury and repair. 121 23

In 26 dogs, a single subcutaneous injection of N-nitroso-N-methylurethane produced acute lung injury characterized by tachypnea cyanosis, increased static lung recoil, and decreased lung compliance. During the first few days, light microscopic examination revealed widespread interstitial and perivascular edema and alveolar collapse. At the same time, electron microscopy showed the major alteration to be widespread necrosis of both types of alveolar epithelial cells without significant injury to the vascular endothelium. During recovery, new epithelial cells appeared which probably were derived from granular pneumocytes. These cells developed into mature granular pneumocytes through a phase in which they resembled fetal granular pneumocytes. The late stage was characterized by a picture resembling diffuse interstitial fibrosis but which was due to irreversible closure of clusters of small airspaces with no apparent increase in collagen. Elastic recoil of the lungs, as reflected by peak inspiratory airway pressure, increased during the acute phase and showed a return toward normal that was coincident with the appearance of mature granular pneumocytes in the regenerating epithelium. Lung compliance decreased during the acute phase and in most animals returned toward normal during the recovery phase. These observations strongly suggest that the alteration in lung mechanics is related to epithelial necrosis and that recovery is related to epithelial regeneration.
 ...
PMID:Experimental acute alveolar injury in the dog. Morphologic--mechanical correlations. 125 90

In experimental intraoperative irradiation, 18 adult rabbits received a single, 50-Gy dose of x-radiation at a unilateral knee joint, and subsequent changes in the articular cartilage were examined over a 15-month period by histology, scanning electron microscopy, and autoradiography. Although the subchondral bone showed histologically typical findings of osteonecrosis three to nine months postirradiation, the articular cartilage revealed no obvious degenerative changes during the entire study period. Scanning electron microscopy revealed normal collagen architecture in the irradiated cartilage for as long as 15 months postirradiation. Autoradiography demonstrated active RNA synthesis by the irradiated chondrocytes during the same period. These results indicate that articular cartilage tissue tolerates intraoperative radiotherapy without sustaining serious degenerative changes, unless possible collapse or contracture disturbs its biomechanical integrity. The survival of articular cartilage can be advantageous for this type of limb-salvage surgery in the treatment of malignant bone tumors around a synovial joint.
 ...
PMID:Long-lasting tolerance of articular cartilage after experimental intraoperative radiation in rabbits. 137 Sep 32

The microstructure of the normal human femoral head was observed under light and electron microscope. Most of the trabeculae were seen in the form of arch structure, and the collagen fibers and mineral columns among the trabeculae were arranged in different directions. These findings provide a new explanation of the mechanism by which the femoral head can bear high stress without collapse.
 ...
PMID:The arch structure of trabeculae in normal femoral head and its biomechanical significance. 139 44


1 2 3 4 5 6 7 8 9 10 Next >>