Thyroid dysfunction effect on cardiac stimulation and sensing parameters

We report our findings in a chronic canine study performed to evaluate the effects of thyroid funciton alteration on atrial and ventricular pacing parameters. Each of five dogs with normal, healthy myocardia, received four unipolar Medtronic contempory pacing leads - model 4011 Target Tip and model 4023 Capsure SP ventricular leads, model 6957 atrial screw-in and an additional lead, either model 4523 Capsure SP or model 4511 Target Tip passive fixation lead. Baseline electrical data and blood levelof T3, T4, electrogram amplitude and slew rate in both the atrium and the ventricle for each electrode type studied during hypothyroid vs hyperthyroid states. Minor decreases in ventricular thresholds were identified. Hyperthyroid induction did not chage either sensing or stimulation parameters from the euthyroid vaseline values.

Immigrant and native ethnic enterprises in Mexican American neighborhoods: differing perceptions of Mexican immigrant workers.

This study uses original data from a large sample of businesses located in Mexican ethnic neighborhoods (barrios) in Texas and California to analyze how perceptions of the economic roles of Mexican immigrant workers differ among 3 employer groups: native ethnic, immigrant ethnic, and non-ethnic. It was found that the immigrant ethnic employer group depends more on Mexican immigrants as workers and as consumers than does the native ethnic group, which tends in many ways to be more like the non-ethnic group. Differences between results for localities on the border with Mexico and those for non-border localities are also discussed.

Broviac catheter-related Malassezia furfur sepsis in five infants receiving intravenous fat emulsions.

Malassezia furfur, a lipophilic fungus commonly found on the skin of healthy adult, was isolated from Broviac catheter blood cultures in five sick infants who were receiving fat emulsions intravenously. The most common manifestations of sepsis included apnea and bradycardia, low-grade fever, interstitial pneumonia, elevated neutrophil band counts, and thrombocytopenia. All infants recovered without antifungal therapy after removal of the Broviac catheters. Early onset of fungemia after catheter placement in these five infants and the recovery of M. furfur from the skin of nearly 33% of hospitalized premature neonates indicate that contamination of the Broviac catheter at time of placement may be the most likely origin of infection.

Cerebral blood flow in the newborn lamb with polycythemia and hyperviscosity.

We measured hematocrit, whole blood viscosity, arterial oxygen content, and cerebral blood flow in seven newborn lambs in which polycythemia and hyperviscosity were induced by partial exchange transfusion with packed red blood cells from a donor lamb. After the exchange transfusion, the hematocrit, whole blood viscosity, and arterial oxygen content were significantly elevated, whereas cerebral blood flow was reduced from baseline measurements. Sodium nitrite was then infused to reduce the arterial oxygen content to baseline values while the hematocrit and viscosity remained elevated. Under this condition, cerebral blood flow returned to baseline values. Oxygen delivery to the brain remained constant throughout the study. These results indicate that the reduction of cerebral blood flow in neonatal polycythemia and hyperviscosity is a physiologic response to increased arterial oxygen content and not a result of hyperviscosity.

Effects of maternal ritodrine administration on neonatal renal function.

Because of its effects on the cardiovascular and renin-angiotensin systems and on fluid and electrolyte homeostasis, maternal administration of ritodrine to inhibit preterm labor may cause significant alterations in renal function in the newborn infant. We determined inulin clearance, plasma renin activity, urinary arginine vasopressin excretion, and serum and urine electrolyte concentrations and osmolalities at 12 to 36 hours of life and at 6 days of life in 15 infants whose mothers had received ritodrine and in 15 infants whose mothers did not (control infants). At the time of each study, plasma ritodrine concentrations were obtained in the infants whose mothers received ritodrine. The infants whose mothers had received ritodrine had significantly lower inulin clearances and higher plasma renin activity and urinary arginine vasopressin excretion on day 1 but not on day 6. Gestational age was inversely correlated with plasma ritodrine concentration, plasma renin activity, and urinary arginine vasopressin excretion. There were no overt clinical signs of renal failure in any of the infants, and no differences in serum and urine electrolyte values, osmolality, fractional sodium excretion, or urine flow rate were observed between the groups.