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

Hyperoxia causes a reproducible pattern of lung injury and repair in rodents, in which proliferation of alveolar epithelial cells (AEC) and fibroblasts is observed during recovery. We postulated that if quiescent cells are stimulated to reenter the cell cycle, then cyclin expression and cyclin-dependent protein kinase activity would be reactivated in AEC during the repair process after hyperoxic lung injury. To test this hypothesis, we exposed adult rats to short-term hyperoxia, followed by recovery for various times in room air. Cellular proliferation in vivo was confirmed by 1) flow cytometric analysis of DNA content (FACS) of freshly isolated AEC and 2) immunohistochemistry of proliferating cell nuclear antigen (PCNA) and bromodeoxyuridine (BrdU) incorporation into DNA on lung sections. The percentage of freshly isolated AEC in S phase and G2/M phase on FACS analysis increased twofold to a maximum of 16.5%, after 48 h in 100% oxygen and 48 h recovery in air. Cyclins A and D and p34cdc2 protein expression were also increased during the recovery period; while p33cdk2 and p34cdk4 increased only slightly. p34cdc2 histone H1 kinase activity, both in whole lung and in AEC, decreased initially after 48 h in oxygen. However, a marked increase in p34cdc2 kinase activity was observed at 48 h recovery in whole lung and returned to baseline by 72 h. In isolated and cultured AEC, p34cdc2 kinase activity was maximal at 24 h of recovery in air. We conclude that cyclins A and D and p34cdc2 protein expression and p34cdc2 kinase activity are increased in vivo during recovery from hyperoxic lung injury in both adult rat lungs and in AEC isolated from these lungs. We speculate that the induction of cyclin-dependent protein kinase activity is a key event in mediating the proliferative cellular repair response to lung injury.
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PMID:Induction of A- and D-type cyclins and cdc2 kinase activity during recovery from short-term hyperoxic lung injury. 753 63

Lung tumors induced by 4-(methylnitrosamine)-1-(3-pyridyl)-1-butanone (NNK) with or without hyperoxia have frequent K-ras mutations but only rare p53 mutations, suggesting that this may be a model for non-small cell lung cancers. The goals of the present study were (1) to characterize the histopathology of lung tumors induced in hamsters by NNK with or without O2 and (2) as a corollary, to quantitate the pulmonary neuroendocrine cell hyperplasia in the different treatment groups early and late in the treatment period. Lung tumors induced by NNK with or without O2 were 71% adenomas, 22% adenocarcinomas, approximately 4% bronchoalveolar carcinomas, and approximately 4% squamous/adenosquamous carcinomas. One-half of all tumors were positive for the Clara cell antigen CC10 and 21% of NNK-induced tumors were mucin positive, compared with 2% of NNK/O2-induced tumors (P = 0.003). Immunostaining for PGP9.5 was positive in 5% of tumors induced by NNK alone, but in none of NNK/O2-induced tumors (P = 0.024). Abundant proliferating cell nuclear antigen occurred in 55% of NNK-induced tumors, compared with 19% of NNK/O2-induced tumors (P = 0.009). These data indicate that NNK with or without O2 induces non-neuroendocrine lung tumors. Hyperoxia appears to inhibit cell proliferation and suppress mucinous and partial neuroendocrine differentiation in some of these tumors.
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PMID:Histochemical characterization of non-neuroendocrine tumors and neuroendocrine cell hyperplasia induced in hamster lung by 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone with or without hyperoxia. 767 85

Infants dying with bronchopulmonary dysplasia (BPD) demonstrate increased numbers of pulmonary neuroendocrine cells (PNEC). These infants also possess altered airway epithelial and smooth muscle dimensions reminiscent of oxygen-exposed animals. Because the pathogenesis of BPD involves oxygen toxicity, we hypothesized that chronic hyperoxia would induce both airway remodeling and PNEC hyperplasia. To test this theory, we compared the small airway morphology of 21-d-old rats subsequently exposed to 2 wk of > 95% O2 (Ox; n = 12) with that of normoxic controls (Con; n = 12). In paraffin-embedded sections, airways < 1500 microns cut in cross-section were analyzed using light microscopy and image analysis software. The degree of epithelial and smooth muscle hyperplasia was assessed with proliferating cell nuclear antigen (PCNA). PNEC content was assessed via immunohistochemical staining for calcitonin gene-related peptide (CGRP) and the number of solitary PNEC (PNECsol) and PNEC clusters (neuroepithelial bodies, NEB) counted per section. We found that oxygen exposure increased epithelial and smooth muscle wall thickness (epithelium: Con, 12.3 +/- 1.4 versus Ox, 14.8 +/- 1.4 microns, p < 0.05; smooth muscle: Con, 7.0 +/- 1.0 versus Ox, 10.0 +/- 1.0 microns, p < 0.05). The changes in wall dimensions were accompanied by a 20% increase in fractional PCNA labeling of the epithelium but not the smooth muscle. Both PNECsol and NEB number increased in the Ox group (PNECsol Con, 3.6 +/- 2.6 versus Ox, 6.3 +/- 3.1/100 mm epithelium, p < 0.05; NEB Con, 7.1 +/- 4.0 versus 11.9 +/- 3.6/100 mm epithelium, p < 0.05). These findings document an association between hyperoxia, airway remodeling, and PNEC hyperplasia and imply that PNEC products may contribute to the pathogenesis of oxygen-related pulmonary diseases such as BPD.
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PMID:Hyperoxia-induced airway remodeling and pulmonary neuroendocrine cell hyperplasia in the weanling rat. 938 Apr 50

Vascular endothelial cell apoptosis has previously been shown to play a role in the pathogenesis of hypertension-induced vessel deletion and damage. In the present in vitro study we analyse several possible relevant causative factors of vascular endothelial cell apoptosis, namely, serum deprivation and nutrient depletion, oxidative stress in the forms of hypoxia, hyperoxia or free radical damage, and altered levels of transforming growth factor-beta1 (TGF-beta1) protein. An established cell line, bovine aortic endothelial cells (BAEC), was maintained in complete growth medium (RPMI-1640 plus 15% fetal calf serum and antibiotics, abbreviated as RPMI) in 25cm2 flasks or in 12-well plates on glass coverslips. Confluent but actively-growing cultures were treated with either hypoxia (PO2 of RPMI = 50mmHg), serum-free media (SFM), SFM plus hypoxia, hyperoxia (PO2 of RPMI = 450mmHg), hydrogen peroxide (H2O2, 1mM) in SFM, or TGF-beta1 protein (10ng/mL) in SFM. Appropriate control cultures were used. BAEC were collected 48h or 72h after all treatments except for TGF-beta1 and H2O2 treatments that were collected at 16-18h. Cell death was assessed using morphological characteristics or in situ end labeling (ISEL), cell proliferation assessed using proliferating cell nuclear antigen (PCNA), and TGF-beta1 expression assessed using transcript levels or immunohistochemistry. All treatments significantly increased levels of apoptosis over control cultures (P<0.05), and decreased levels of cell proliferation. Treatment with TGF-beta1 protein or SFM plus hypoxia induced greatest levels of apoptosis. TGF-beta1 protein and transcript levels were decreased in treated cultures, results suggesting that a paracrine source of TGF-beta1 protein would be needed as a cause of endothelial cell apoptosis in viva. Future therapies against inappropriate vessel deletion in disease states may use the known gene-driven nature of apoptosis to modify this sort of cell death in endothelial cells.
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PMID:Apoptosis in vascular endothelial cells caused by serum deprivation, oxidative stress and transforming growth factor-beta. 1059 59

Little is known about cell-cycle checkpoint activation by oxidative stress in mammalian cells. The effects of hyperoxia on cell-cycle progression were investigated in asynchronous human T47D-H3 cells, which contain mutated p53 and fail to arrest at G1/S in response to DNA damage. Hyperoxic exposure (95% O(2), 40-64 h) induced an S-phase arrest associated with acute inhibition of Cdk2 activity and DNA synthesis. In contrast, exit from G2/M was not inhibited in these cells. After 40 h of hyperoxia, these effects were partially reversible during recovery under normoxic conditions. The inhibition of Cdk2 activity was not due to degradation of Cdk2, cyclin E or A, nor impairment of Cdk2 complex formation with cyclin A or E and p21(Cip1). The loss of Cdk2 activity occurred in the absence of induction and recruitment of cdk inhibitor p21(Cip1) or p27(Kip1) in cyclin A/Cdk2 or cyclin E/Cdk2 complexes. In contrast, Cdk2 inhibition was associated with increased Cdk2-Tyr15 phosphorylation, increased E2F-1 recruitment, and decreased PCNA contents in Cdk2 complexes. The latter results indicate a p21(Cip1)/p27(Kip1)-independent mechanism of S-phase checkpoint activation in the hyperoxic T47D cell model investigated.
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PMID:Hyperoxia induces S-phase cell-cycle arrest and p21(Cip1/Waf1)-independent Cdk2 inhibition in human carcinoma T47D-H3 cells. 1077 7

Parathyroid hormone-related protein (PTHrP) is a growth inhibitor for alveolar type II cells and could be a regulatory factor for alveolar epithelial cell proliferation after lung injury. We investigated lung PTHrP expression in rats exposed to 85% oxygen. Lung levels of PTHrP were significantly decreased between 4 and 8 days of hyperoxia, concurrent with increased expression of proliferating cell nuclear antigen and increased incorporation of 5-bromo-2'-deoxyuridine (BrdU) into DNA in lung corner cells. PTHrP receptor was present in both normal and hyperoxic lung. To test whether the fall in PTHrP was related to cell proliferation, we instilled PTHrP into lungs on the fourth day of hyperoxia. Eight hours later, BrdU labeling in alveolar corner cells was 3.2 +/- 0.4 cells/high-power field in hyperoxic PBS-instilled rats compared with 0.5 +/- 0.3 cells/high-power field in PTHrP-instilled rats (P < 0. 01). Thus PTHrP expression changes in response to lung injury due to 85% oxygen and may regulate cell proliferation.
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PMID:Parathyroid hormone-related protein reduces alveolar epithelial cell proliferation during lung injury in rats. 1089 18

Telomerase expression and activity were examined in the developing lung and in the adult lung during repair after injury. Both whole lung tissue and primary cultures of type 2 alveolar epithelial cells (AEC2) isolated from fetal and adult rodents were analyzed for 1) telomerase expression by immunohistochemistry and 2) telomerase activity with a telomerase repeat amplification protocol. We found that telomerase was expressed in a temporally regulated manner in fetal lung through the late stages of gestation, with peak expression just before birth. Expression persisted for a brief period in neonates, then decreased to nearly undetectable levels by postnatal day 9. Telomerase expression and activity were reinduced in normally quiescent adult lung by in vivo treatment with hyperoxia. In populations of AEC2 isolated from both developing and repairing lungs, telomerase expression and activity showed a strong correlation with the proliferation marker proliferating cell nuclear antigen. It has been suggested that telomerase expression and activity are hallmarks of stem or progenitor cells. Our observations suggest that a telomerase-positive subpopulation is present within the general AEC2 population. Telomerase may act as a marker for the proliferative status of this subpopulation.
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PMID:Telomerase in alveolar epithelial development and repair. 1107 9

Inflammation may contribute to lung injury and impaired alveolar development in bronchopulmonary dysplasia. We treated hyperoxia-exposed newborn rats with antibodies to the neutrophil chemokine cytokine-induced neutrophil chemoattractant-1 (CINC-1) during 95% O2 exposure to reduce adverse effects of hyperoxia-induced inflammation on lung development. Rats were exposed at birth to air, 95% O2, or 95% O2 + anti-CINC-1 (injected on days 3 and 4). Bromodeoxyuridine (BrdU) was injected 6 h before death. Anti-CINC-1 treatment improved weight gain but not survival at day 8. Anti-CINC-1 reduced bronchoalveolar lavage neutrophils at day 8 to levels equal to air controls. Total detectable lung CINC-1 was reduced to air control levels. Lung compliance was improved by anti-CINC-1, achieving air control levels in the 10-microg anti-CINC-1 group. Anti-CINC-1 preserved proliferating cell nuclear antigen expression in airway epithelium despite 95% O2 exposure. BrdU incorporation was depressed by hyperoxia but preserved by anti-CINC-1 to levels similar to air control. Alveolar volume and surface density were decreased by hyperoxia but preserved by anti-CINC-1 to levels equal to air control. Blockade of neutrophil influx in newborns may avert early lung injury and avoid alveolar developmental arrest that contributes to bronchopulmonary dysplasia.
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PMID:Anti-neutrophil chemokine preserves alveolar development in hyperoxia-exposed newborn rats. 1143 8

The final stage of lung development, alveolarization, continues after birth in humans and rodents. Clinical interventions, such as oxygen therapy, in the first week of life can adversely impact alveolar formation. We compared alveolarization in the rat neonate under normal vs. hyperoxic conditions, examining gelatinase, transforming growth factor (TGF)-beta, and the protease urokinase-type plasminogen activator (uPA) activities in whole lung and cultured type II alveolar epithelial cells (AEC2). The dynamic induction of gelatinase, TGF-beta, and uPA activities seen in neonatal lungs during the first days of life was significantly impacted by hyperoxia. In whole lung, gelatinase and TGF-beta activities were increased, while uPA activity was decreased. At the level of the epithelium, AEC2 isolated from hyperoxic rat pups early in life secreted less active TGF-beta, less active gelatinases, and less active uPA than control neonatal AEC2. AEC2 from hyperoxic pups also expressed increased levels of proliferating cell nuclear antigen early in life compared with control neonatal AEC2, suggesting that oxygen-induced proliferation and/or repair were occurring. The developmental profile of neonatal lung was perturbed within a day of initiating oxygen treatment, suggesting that putative palliative treatments should be coadministered with oxygen therapy.
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PMID:Dynamics of metalloproteinase-2 and -9, TGF-beta, and uPA activities during normoxic vs. hyperoxic alveolarization. 1222 51

This study investigates molecular mechanisms underlying cell cycle arrest when cells are exposed to high levels of oxygen (hyperoxia). Hyperoxia has previously been shown to increase expression of the cell cycle regulators p53 and p21. In the current study, we found that p53-deficient human lung adenocarcinoma H1299 cells failed to induce p21 or growth arrest in G(1) when exposed to 95% oxygen. Instead, cells arrested in S and G(2). Stable expression of p53 restored induction of p21 and G(1) arrest without affecting mRNA expression of the other Cip or INK4 G(1) kinase inhibitors. To confirm the role of p21 in G(1) arrest, we created H1299 cells with tetracycline-inducible expression of enhanced green fluorescent protein (EGFP), EGFP fused to p21 (EGFp21), or EGFP fused to p27 (EGFp27), a related cell cycle inhibitor. The amino terminus of p21 and p27 bind cyclin-dependent kinases (Cdk), whereas the carboxy terminus of p21 binds the sliding clamp proliferating cell nuclear antigen (PCNA). EGFp21 or EGFp27, but not EGFP by itself, restored G(1) arrest during hyperoxia. When separately overexpressed, the amino-terminal Cdk and carboxy-terminal PCNA binding domains of p21 each prevented cells from exiting G(1) during exposure. These findings demonstrate that exposure in vitro to hyperoxia exerts G(1) arrest through p53-dependent induction of p21 that suppresses Cdk and PCNA activity. Because PCNA also participates in DNA repair, these results raise the possibility that p21 also affects repair of oxidized DNA.
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PMID:The Cdk and PCNA domains on p21Cip1 both function to inhibit G1/S progression during hyperoxia. 1293 10


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