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An investigation of intracellular xanthine dehydrogenase (XD)/xanthine oxidase (XO) activity in rat pulmonary microvascular endothelial cells has provide evidence for nitric oxide (NO) regulation. Cells exposed to L-arginine, a precursor of NO synthase, during normoxia and hypoxia showed an increase in XO and XD activities. On the other hand, L-NAME, another precursor of NO synthase, prevented a decline XD/XO activity during hypoxia-reoxygenation.

Summary: Chronic obstructive pulmonary disease (COPD) ranks fourth as a cause of death in the United States, behind heart disease, cancer, and stroke. Additionally, since serious co-morbidities are often present in patients with COPD, many die from other diseases such as cardiac disease or cancer. Not surprisingly, multiple factors, reflective of both respiratory disease process and the substantial co-morbidity, predict survival in the disease. As might be expected, physiologic derangements such as airflow obstruction, hypoxemia, lung hyperinflation, and exercise capacity predict survival in COPD. Anemia, cachexia and reductions in lean body mass also relate to prognosis. Perhaps less recognized is the more recent documentation that more subjective assessments, such as dyspnea and health related quality of life, are also important predictors of survival. The integration of some of the most important of these variables may provide a more comprehensive evaluation of disease severity. For example, a validated multi-dimensional disease rating that includes the body mass index (B), degree of airflow obstruction (0), dyspnea (D), and exercise capacity (E) (BODE Index) is capable of predicting COPD-related hospitalization and mortality more than its individual components. [Copyright &y& Elsevier]

Background: The 6-minute walk distance (6MWD) has been useful in the evaluation of men with COPD. Little is known about 6MWD in women with the disease., Objectives: Using healthy women as a reference, to evaluate the factors that help determine 6MWD in women with COPD. To explore if the 350 meters threshold differentiates survival in women as it does in men., Methods: Healthy women (n = 164) and with COPD (n = 223) were included in the study. Age, pack-years history, smoking status, comorbidities (Charlson Index), BMI, MRC dyspnea, spirometry and 6MWD were recorded in all participants and PaO(2) and IC/TLC in COPD women. The patients were prospectively followed and deaths registered. Factors predicting 6MWD were determined by multiple regression analysis. ROC analysis was used to calculate the best threshold value for the 6MWD with mortality as gold standard. Kaplan-Meier curves compared survival of patients that walked more or less than 350 m by age categories., Results: The 6MWD is decreased in women with COPD. Values decrease with age and GOLD stages. Age, BMI, smoking status, comorbidities, MRC and FEV(1%) are statistical significant predictors of 6MWD. A 350 m cut-off value has a good sensitivity and specificity to predict (73% and 80% respectively) and differentiate survival (p < 0.001 for log rank comparisons) in these patients., Conclusions: In women with COPD, the 6MWD decreases with age and GOLD stages. A 350 m distance is a valid threshold to differentiate survival. Further studies in different settings should confirm our findings.