Pediatric research
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Resting cardiac output is high relative to body weight during the neonatal period and there is a limited reserve for further increasing cardiac output. We assessed the effect on the circulation of reducing peripheral vascular resistance by infusing high doses of sodium nitroprusside in 1- and 3-week-old lambs. In a dose of 5 micrograms X kg-1 X min-1 over 1 h, nitroprusside caused a decrease in aortic and left atrial pressure, an increase in heart rate, and no significant changes in cardiac output or oxygen consumption. ⋯ Within 50 min aortic pressure gradually increased, but was still well below control levels, while cardiac output returned to control level and heart rate slowly increased. Distribution of cardiac output and organ blood flows was measured by the radionuclide microsphere method. Blood flows to the kidneys and to the skin fell markedly, but flows to other organs did not change significantly.
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Two patients with acrodermatitis enteropathica had abnormal lysosomal inclusion bodies in the intestinal epithelial cells while in relapse but fewer smaller ones after zinc therapy. The third patient with acrodermatitis enteropathica in remission on zinc therapy had no inclusion bodies. The smaller inclusion bodies were similar to those found in coeliac disease.
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Comparative Study
Mucus glycoproteins secreted by respiratory epithelial tissue from cystic fibrosis patients.
Tracheae, bronchi, nasal epithelial, and nasal polyp tissue slices were incubated in tissue culture with [3H]-glucosamine, and the rate of secretion of labeled mucus glycoproteins was measured. Secretion rates were at least 3- to 6-fold higher for all of the samples from nine patients with cystic fibrosis (CF) who were studied, as compared with values for tissue slices from eight young subjects not affected with this disease. The secreted glycoproteins were further purified into one neutral and three acidic fractions by ion-exchange chromatography on DEAE-cellulose. ⋯ All four of the labeled glycoprotein fractions secreted by cultured human bronchi cochromatographed with authentic mucus glycoproteins purified from sputum of cystic fibrosis subjects by the same techniques. The differences between mucus glycoproteins from cultured CF airway tissue and mucus glycoproteins from other patients' tissue included relatively increased rates of production, level of sulfation, and greater acidity. Further applications of these in vitro techniques should allow the determination of the enzymatic and biochemical causes of these observed differences in the absence of such potentially confounding variables as concurrent airway infection or of oropharyngeal secretions.
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Comparative Study
Improvement in lung mechanics as a function of age in the infant with severe bronchopulmonary dysplasia.
Pulmonary function tests were performed in two groups of infants with bronchopulmonary dysplasia; a group less than 7 months of age with severe ventilator-dependent respiratory failure (Group A), and a group 7-22 months of age during resolution of their disease (Group B). Group A patients had significantly elevated minute volume, low specific compliance, elevated inspiratory and expiratory pulmonary resistance, and low functional residual capacity. ⋯ Sequential studies of resistance and compliance over 4-5 months in two patients in the younger group demonstrated values that approached or achieved normal range. It is concluded that pulmonary mechanics improve with age in the infant with severe bronchopulmonary dysplasia.