Bordetella pertussis: caracterización epidemiológica y diagnóstico / Bordetella pertusis: epidemiologic characterization and diagnosis

La tos ferina es una enfermedad transmisible e inmunoprevenible que actualmente esta resurgiendo en países del primer mundo. La investigación tuvo como propósito determinar la circulación de Bordetella, pertussis en pacientes menores de 1 año, en el servicio de pediatría del Hospital Universitario de Caracas entre junio 2001- noviembre 2002. Se incluyeron pacientes menores de 1 año con síntomas sospechosos de tos ferina según la Organización Mundial de la Salud (OMS). Se realizó encuesta epidemiológica y clínica, cultivo de secreción nasofaríngea y serológica para Ig M. Durante 17 meses se identificaron 66 casos sospechosos de tos ferina, 35 fueron incluidos. Hubo confirmación bacteriológica en 8.6%, la negatividad del cultivo se correlacionó 100% con serología. Los confirmados tenían menos de 3 meses de edad, con antecedentes de contacto, ausencia de inmunización y clínica de tos paroxística, cianosis y vómito post-tusígeno. Se confirma la circulación de Bordetella pertussis y se establecen bases para el inicio el modelo del proyecto de vigilancia epidemiológica.

Caffeine effects on heart muscle energetics: species differences

The effects of caffeine (1mM) on energy expenditure and mechanical parameters in rat and toad perfused heart ventricles were examined at various stimulation frequencies. While in rat muscles caffeine significantly depressed developed tension and maximal rates of contraction and relaxation at all frequencies tested, in toad ventricle a slight positive inotropic effect was observed. Even though caffeine did not alter total contraction time in both preparations, in the rat ventricle the last part of relaxation was prolonged. In rat ventricle in the presence of caffeine, the ratios between active heat production per beat and either developed tension or tension time integral increased at all frequencies tested (+303 +/- 47 microJ.mN-1 x g-1 and +1.21 +/- 0.13 mJ.mN-1 x s-1 x g-1 respectively) indicating a decrease in contractile economy. In toad ventricle no changes on these ratios were observed. The fact that only in rat ventricle caffeine decreased muscle economy suggests that caffeine affects a system that is active in rat ventricle but it is not operative in toad ventricle. This gives support to the hypothesis that if in rat ventricle SR-Ca pump (1 ATP hydrolyzed/2 Ca transported) is inhibited by caffeine cytosolic Ca would have to be removed by alternative mechanisms such as Na-Ca exchanger or sarcolemmal Ca pump both with a higher rate of ATP hydrolysis (1 ATP hydrolyzed/Ca transported) with the consequent decrease in muscle economy. Resting heat production was increased by caffeine in both preparations and the magnitude of the increment (+3.0 +/- 0.6 mW.g-1 and +0.75 +/- 0.21 mW.g-1 for rat and toad ventricle respectively) also correlates with the different degree of SR activity in both species

Caffeine effects on heart muscle energetics: species differences

The effects of caffeine (1mM) on energy expenditure and mechanical parameters in rat and toad perfused heart ventricles were examined at various stimulation frequencies. While in rat muscles caffeine significantly depressed developed tension and maximal rates of contraction and relaxation at all frequencies tested, in toad ventricle a slight positive inotropic effect was observed. Even though caffeine did not alter total contraction time in both preparations, in the rat ventricle the last part of relaxation was prolonged. In rat ventricle in the presence of caffeine, the ratios between active heat production per beat and either developed tension or tension time integral increased at all frequencies tested (+303 +/- 47 microJ.mN-1 x g-1 and +1.21 +/- 0.13 mJ.mN-1 x s-1 x g-1 respectively) indicating a decrease in contractile economy. In toad ventricle no changes on these ratios were observed. The fact that only in rat ventricle caffeine decreased muscle economy suggests that caffeine affects a system that is active in rat ventricle but it is not operative in toad ventricle. This gives support to the hypothesis that if in rat ventricle SR-Ca pump (1 ATP hydrolyzed/2 Ca transported) is inhibited by caffeine cytosolic Ca would have to be removed by alternative mechanisms such as Na-Ca exchanger or sarcolemmal Ca pump both with a higher rate of ATP hydrolysis (1 ATP hydrolyzed/Ca transported) with the consequent decrease in muscle economy. Resting heat production was increased by caffeine in both preparations and the magnitude of the increment (+3.0 +/- 0.6 mW.g-1 and +0.75 +/- 0.21 mW.g-1 for rat and toad ventricle respectively) also correlates with the different degree of SR activity in both species (Au)