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Query: UMLS:C0242706 (hyperoxia)
 5,219 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Oxygen toxicity is attributed to the reaction of oxygen metabolites with cellular components leading to cell destruction. Activation of latent human neutrophil interstitial collagenase by reactive oxygen species has been demonstrated. The potential role of collagenases in hyperoxic lung injury has not been investigated. We studied the effect of hyperoxia on newborn rat lung water content, morphology and ultrastructure, interstitial (type I) and type IV collagenase gene expression and type I and IV collagenolytic activity. We observed that hyperoxia causes pulmonary edema, alters newborn rat lung morphology in a sequential manner and produces ultrastructural alterations, induces type I and increases type IV collagenase mRNA expression, and increases type I and IV collagenolytic activity. A role for type I and IV collagenase in hyperoxic newborn lung injury or in the recovery following the injury is proposed.
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PMID:Hyperoxia induces interstitial (type I) and increases type IV collagenase mRNA expression and increases type I and IV collagenolytic activity in newborn rat lung. 799 51

Subacute hyperoxia may cause basement membrane disruption and subsequent fibrosis. To test the role of extracellular matrix degradation in hyperoxic damage, we analyzed the expression of gelatinases A and B and tissue inhibitors of metalloproteinases (TIMP)-1 and TIMP-2 in rats exposed to 85% O2. Oxygen-exposed rats were studied at 1, 3, 5, and 7 days, and compared with air-breathing rats. Lung mRNAs assayed by Northern and in situ hybridization showed an up-regulation of lung gelatinases A and B from the 3rd day on. Gelatinase A was localized in alveolar macrophages and in interstitial and alveolar epithelial cells. Gelatinase B mRNA and protein were localized in macrophages and bronchiolar and alveolar epithelial cells. Increased gelatinase A and B activities were demonstrated in bronchoalveolar lavage. TIMP-1 and TIMP-2 were constitutively expressed, and only TIMP-1 displayed a moderate increase with hyperoxia. To elucidate transcriptional mechanisms for increased gelatinase B expression after hyperoxia, nuclear transcription factor-kappabeta activation was explored. Oxidative stress significantly increased the lung expression of nuclear transcription factor-kappabeta (p65) protein, and nuclear transcription factor-kappabeta activation and increased levels of gelatinases A and B were found in isolated type II alveolar cells obtained from hyperoxic rats. Conceivably, subacute hyperoxia induces excessive gelatinase activity, which may contribute to lung damage.
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PMID:Gelatinases A and B are up-regulated in rat lungs by subacute hyperoxia: pathogenetic implications. 973 32

In this study, we examined the sequential expression of several matrix metalloproteinases (MMPs), tissue inhibitors of metalloproteinases (TIMPs), and growth factors as well as the presence of apoptosis in a model of pulmonary fibrosis induced in rats with paraquat and hyperoxia. Animals showing neither clinical nor morphological changes with this double aggression were classified as "resistant". Rats were killed at 1, 2, 3, and 6 wk, and lungs were used for collagen content, gene expression by real-time PCR, gelatinolytic activity by zymography, apoptosis by in situ DNA fragmentation, and protein localization by immunohistochemistry. Our results showed a significant decrease of collagenases MMP-8 and MMP-13, with an increase of TIMP-1 and transforming growth factor-beta. Immunoreactive TIMP-1 was increased in experimental rats and primarily localized in alveolar macrophages. Expression of gelatinases MMP-2 and MMP-9 mRNAs was not affected, but lung zymography revealed an increase in progelatinase B, progelatinase A, and its active form. Epithelial apoptosis was evident from the first week, whereas at later periods, interstitial cell apoptosis was also noticed. Resistant animals behave as controls. These findings suggest that an imbalance between collagenases and TIMPs, excessive gelatinolytic activity, and epithelial apoptosis participate in the fibrotic response in this experimental model.
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PMID:Unbalanced collagenases/TIMP-1 expression and epithelial apoptosis in experimental lung fibrosis. 1288 63