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Biomedical subjects

R A Danielson

Publications and source records attributed to R A Danielson.

8 recordsLinked to original sources
PubMed1977

Quantitative analysis of renal medullary anatomy in rats and rabbits.

The mean renal tubular diameters, number of tubules per unit of cross-sectional area, and fraction of the total volume occupied by each medullary structure were determined at various levels of the renal medulla of the rat and rabbit. Statistical estimates of anatomic variables were made using spatial sampling techniques on histologic sections. Osmotic diuresis and renal venous occlusion were used to allow fixation of renal tubules and blood vessels in an open state. The distribution of volume fractions of medullary structures are similar in rats and rabbits. Diameters of outer medullary tubular segments and inner medullary thin limbs of Henle are also similar in rats and rabbits. Marked differences between rats and rabbits, however, are seen in the size and number of collecting ducts in the inner medulla. Rabbit inner medullary collecting ducts increase in diameter and decrease in number in the papillary direction relatively closer to the cortex than do those of the rat. Luminal diameters of papillary collecting ducts are more than twice as great in the rabbit as in the rat. An additional finding was that short loops of Henle in the rabbit have their bends relatively closer to the cortex than those of the rat. The quantitative anatomic data derived in this study, when combined through mathematical modeling with knowledge of transport properties of renal tubular membranes, should lead to a clearer understanding of renal function.

Animals↗
PubMed1976

Facilitation of exchange transfusions with Scribner shunts in Reye's syndrome.

Scribner shunts were placed in nine patients, who had clinical and laboratory evidence of Reye's syndrome and ranged in age from four to fifteen years, to facilitate repeated, rapid exchanges of large volumes of blood. A method of inserting the Scribner shunt is described. Over a period of 30 to 90 minutes, 3 to 8 units of blood were easily exchanged without hemodynamic or mechanical difficulties. There were no infections; all shunts were removed from survivors after four to eight days without permanent sequelae.

Adolescent↗
PubMed1976

Maximal cardiac output in angina patients before abd after coronary artery surgery.

Ten patients with angina pectoris underwent multistage maximal treadmill exercise with hemodynamic measurements before, and again 6 months following coronary artery surgery. Subjectively, 9 patients experienced a total and one patient partial relief from angina, and all patients noted improved exercise tolerance following surgery. Objectively, significant improvement was found in duration of exercise, maximal oxygen intake in maximal cardiac output, maximal heart rate, and maximal pressure-rate product. Surgery did not significantly affect systemic or pulmonary arterial pressures during exercise. Despite these improvements, maximal cardiac output did not return to normal levels following surgery, due to an unexpected but significant reduction in stroke volume.

Angina Pectoris↗
PubMed1975

Effects of dietary protein restriction and glucocorticoid administration on urea excretion in rats.

Rats were sampled for clearance studies under anesthesia after 0, 2, 4, 7 and 14 days of dietary protein restriction. Mean fractional urea excretion decreased between day 2 and day 7 of protein restriction after a two-day lag in response. Seven-day administration of dexamethasone in protein-restricted rats caused a significant increase in mean fractional urea excretion. Adrenalectomized rats fed a normal diet had fractional urea excretion values resembling those in protein-restricted rats. Chronic administration of dexamethasone in adrenalectomized rats caused a consistent increase in fractional urea excretion. Fractional urea excretion values were no lower in protein-restricted adrenalectomized rats fed a normal diet. The mean plasma corticosterone concentration (measured 6 to 8 PM) was decreased in rats fed a low protein diet relative to rats fed a high protein diet. The results suggest that glucocorticoids may play a role in the tubular regulation of urea excretion either by a direct effect on the renal tubule or through some intermediate factor. A mediating role of glomerular filtration rate in glucocorticoid-induced changes of fractional urea excretion could not be ruled out, however.

Adrenalectomy↗
PubMedDate not supplied

Operating room scheduling by computer.

The surgical operating room schedule has been produced automatically for more than 2 years in our large teaching hospital. In order to apply computer technology to the complex surgical scheduling problem a special programming approach was devised. We discuss this approach under the headings of Expand, Sort, Order and Assign. Consistent, reliable schedules, unaffected by weekends and holidays, are produced by a clerk trained to use a computer terminal. Our program is adapttable to other institutions once the scheduling parameters and operating priorities are delineated.

Anesthesiology↗