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Biomedical subjects

G Silva

Publications and source records attributed to G Silva.

At least 73 records · Page 4Linked to original sources
PubMed1979

Inhibition of urinary kallikrein excretion by semi-purified renin in the rat.

1. Rat kidney extracts obtained at successive stages of a purification procedure, which allows the separation of renin and kallikrein, were used in order to investigate their effect upon urinary excretion of kallikrein, sodium, potassium and water in hyperhydrated rats. 2. Only the purified fraction containing renin reduced kallikrein excretion. The decrease of kallikrein coincided with a considerable increase in sodium, potassium and water excretion. 3. The natriuretic effect of renin extract did not depend on the presence of kallikrein. The injection of a mixture of renin and kallikrein attenuated the effect of renin alone, indicating that both enzymes exert antagonistic actions on the excretion of electrolytes and water by the kidneys. 4. A purified fraction of kidney extract containing no kallikrein and only traces of renin activity, had a stimulatory effect on kallikrein, water and electrolyte excretion.

Animals↗
PubMed1979

Distribution of ventilation in normal children.

Measurements of closing volume and the distribution fo ventilation by both single-breath (SBN2) and multiple-breath nitrogen washout methods were obtained in 376 healthy boys and girls, ages 6 to 18 years. A closing volume could be demonstrated in 39 percent of the subjects, and closing volume expressed as percentage of vital capacity did not change with height. Closing capacity expressed as percentage of total lung capacity showed a slight decrease with height. The slope of phase III of the SBN2 curve decreased with height. Single compartment N2 washout curves were observed in 72 percent of the subjects, and the incidence of single compartment curves increased with age. In those subjects with two compartment N2 washout curves, the relative compartmental ventilation became more even with increasing height. Our observations suggest that parallel units among peripheral airways grow at different rates.

Adolescent↗
PubMed1978

Effects of terbutaline aerosol in reversible airway obstruction.

Aerosol terbutaline is an effective bronchodilator agent with at least a seven-hour duration of action in patients with reversible obstruction of the airways. Inhalation of up to 1.5 mg of this drug is not associated with significant alterations of pulse rate and blood pressure. Although a dose-related improvement of specific airway conductance was demonstrated 30 minutes after administration of the drug, no such effect was observed in measurements of the forced expiratory volume in one second.

Aerosols↗
PubMed1978

Accuracy of Drager and Wright ventilation meters.

Simple compact mechanical ventilation meters for bedside monitoring are in wide-spread use in this country. We investigated the accuracy of two such ventilation meters, the Drager Volumeter and the Wright Respirometer. Volume measurements on 16 units were made at fixed flow rates between 6 and 12 l/min. Both types of spirometer showed similar magnitudes and patterns of inaccuracy. For 14 used units, the mean deviation from the actual value was the smallest between the flow rates of 15 and 30 l/min, with a mean systematic underestimation of about 15 per cent and maximum variability among individual units (S.D. 10--12 per cent) at lower flow rates. Measurements at flow rates above 120 l/min were unsatisfactory due to locking of the ventilation meter mechanism. The single new Drager Volumeter tested was relatively accurate at all flow rates measured, whereas the single new Wright Respirometer tested showed inaccuracies comparable to the mean values of the used units. We conclude that these devices are satisfactory to monitor patients on continuous mechanical ventilation but may not be adequate for bedside spirometry.

Evaluation Studies as Topic↗
PubMed1977

Long-term effects of metaproterenol in asthmatic children.

Oral metaproterenol was administered daily for 3 months to asthmatic children. The study was designed to determine whether chronic tolerance developed to this drug. Initial and final crossovers on the first 2 and the last 2 days of the investigation to a test dose of metaproterenol and placebo failed to show tolerance as indicated by improvement in lung volumes and dynamic mechanics of breathing after metaproterenol. Forced expiratory volume in 1 sec was the test most consistent in demonstrating bronchodilation; the action of metaproterenol. Forced expiratory volume in 1 sec was the test most consistent in demonstrating bronchodilation; the action of metaproterenol appeared to last at least 5 hours as measured by this test. T of distribution of ventilation, e.g., single- and multiple-breath nitrogen washout tests, were not consistently altered by metaproterenol. These tests did not appear to be sufficiently sensitive to detect improvement even when airway resistance decreased and forced expiratory volume in 1 sec increased toward the normal range.

Asthma↗
PubMed1975

Ascending aorta-right pulmonary artery anastomosis in children with complex cardiac malformations. Long-term results in 30 cases.

In this report, we shall analyze the results obtained with palliative treatment in 30 patients with congenital heart disease who were operated upon at the University Hospital of Caracas during the period 1968 to 1972. In all cases, an ascending aorta-right pulmonary artery anastomosis was performed. Although we believe that the Blalock-Taussig and Potts shunt are satisfactory operations in some cases, at the present time we prefer the aorta-right pulmonary branch anastomosis in Fallots tetralogy and other congenital heart diseases such as single ventricle. In Fallot's tetralogy, particularly, this procedure provides better results, because the anastomosis can be closed through the aorta when these patients are later subjected to total correction with extracorporeal circulation.

Adolescent↗