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Copyright of Revista Chilena de Cirugia is the property of Sociedad de Cirujanos de Chile and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Introduction The prevalence of high levels of stress as well as its multilevel consequences is well documented amongst students in the health sciences, and particularly in dentistry. However, investigations of perceived stress amongst Spanish-speaking student groups are sparse. This study aimed to (i) describe the translation, adaptation and psychometric properties of a Spanish version of the Dental Environment Stressors questionnaire and (ii) to examine the perceived sources of stress and their associations with the students' study year and gender in two dental schools in Latin America. Materials and methods All students officially registered in the dental schools of the University of San Sebastian ( USS) in Chile and the Catholic University of Cordoba ( CUC) in Argentina were invited to participate in the study. The DES30 questionnaire was adapted in Spanish using translation/back-translation, an expert bilingual committee, and consensus building. Cronbach's alpha was used to measure the instrument's internal consistency, and iterated principal factor analysis with promax rotation was employed to explore its underlying factor structure. Descriptive, bivariate and multivariate methods were used to examine the patterns of association between individual stressors, factor scores and students' characteristics. Results Three hundred and four students comprised the study's analytical sample, with two-thirds of those being female. The DES30- Sp demonstrated good internal consistency ( Cronbach's α = 0.89). A four-factor solution emerged and included 'academic workload', 'clinical training', 'time constraints' and 'self-efficacy beliefs' factors. 'Fear of failing a course or a year', 'examinations and grades' and 'lack of time for relaxation' were amongst the top individual-item stressors reported by students in both schools. Amongst this group of undergraduate dental students, those in Argentina, in higher study year, and females reported higher perceived stress. Conclusions Increased workload, time constraints and some aspects of clinical training were the top stressors of approximately 300 Chilean and Argentinean dental undergraduates. Some variations between schools, males and females and study years were noted. The Spanish version of the DES30 questionnaire performed well, but future studies should evaluate the instrument's properties in larger and more diverse dental student populations. [ABSTRACT FROM AUTHOR]

Rationale: Sildenafil, a phosphodiesterase-5 inhibitor, could be useful for treating pulmonary hypertension (PH) in chronic obstructive pulmonary disease (COPD). However, vasodilators may inhibit hypoxic pulmonary vasoconstriction and impair gas exchange in this condition. Objectives: To assess the acute hemodynamic and gas exchange effects of sildenafil in patients with COPD-associated PH. Methods: We conducted a randomized, dose comparison trial in 20 patients with COPD-associated PH. Eleven patients were assigned to 20 mg, and 9 patients to 40 mg, of sildenafil. Pulmonary hemodynamics and gas exchange, including ventilation-perfusion (Va/Q) relationships, were assessed at rest and during constant-work rate exercise, before and 1 hour after sildenafil administration. Measurements and Main Results: Both sildenafil doses reduced the mean pulmonary arterial pressure (PAP) at rest and during exercise, without differences between them. Overall, PAP decreased -6 mm Hg (95% confidence interval [95% CI], -7 to -4) at rest and -11 mm Hg (95% CI, -14 to -8) during exercise. After sildenafil, Pa(O(2)) decreased -6 mm Hg (95% CI, -8 to -4) at rest because of increased perfusion in units with low Va/Q ratio, without differences between doses. No change in Pa(O(2)) (95% CI, -3 to 0.2 mm Hg) or Va/Q relationships occurred during exercise after sildenafil. Changes induced by sildenafil in Pa(O(2)) and Va/Q distributions at rest correlated with their respective values at baseline. Conclusions: In patients with COPD-associated PH, sildenafil improves pulmonary hemodynamics at rest and during exercise. This effect is accompanied by the inhibition of hypoxic vasoconstriction, which impairs arterial oxygenation at rest. The use of sildenafil in COPD should be done cautiously and under close monitoring of blood gases. Clinical trial registered with www.clinicaltrials.gov (NCT00491803). [ABSTRACT FROM AUTHOR]

Alterations in pulmonary vessel structure and function are highly prevalent in patients with COPD. Vascular abnormalities impair gas exchange and may result in pulmonary hypertension, which is one of the principal factors associated with reduced survival in COPD patients. Changes in pulmonary circulation have been identified at initial disease stages, providing new insight into their pathogenesis. Endothelial cell damage and dysfunction produced by the effects of cigarette smoke products or inflammatory elements is now considered to be the primary alteration that initiates the sequence of events resulting in pulmonary hypertension. Cellular and molecular mechanisms involved in this process are being extensively investigated. Progress in the understanding of the pathobiology of pulmonary hypertension associated with COPD may provide the basis for a new therapeutic approach addressed to correct the imbalance between endothelium-derived vasoactive agents. The safety and efficacy of endothelium-targeted therapy in COPD-associated pulmonary hypertension warrants further investigation in randomized clinical trials. [ABSTRACT FROM AUTHOR]