Yngvar Willassen

A routine method for the determination of aluminium in human tissue samples using standard addition and graphite furnace atomic absorption spectrophotometry

Abstract Aluminium in human tissue samples has been determined by atomic absorption spectrophotometry using the nitrous oxide-acetylene flame and the graphite furnace atomizer. The two methods are compared. Flameless atomic absorption was found superior when standard addition was applied. A routine method is thus described in detail in which aluminium levels down to 0.1 mg/kg of freeze-dried tissue and 0.01 mg/liter of serum can be determined.

Diameter of the afferent arteriole in the dog kidney estimated by the microsphere method.

Microspheres with diameters of from 10 to 30 mum were injected into the renal arteries of three anesthetized dogs. The six kidneys were studied by light microscopy. The diameters of the spheres trapped in the afferent arterioles and of all spheres recovered in the kidneys were recorded. On the basis of the distribution of diameters in these two populations of spheres, the average diameter of the afferent arteriole and the distribution of the afferent arteriolar diameters were estimated. The average diameter of the afferent arterioles was 16.3 mum (S.D. 2.2 mum), without any difference between three cortical layers of equal thickness. The mean diameter of spheres trapped in the interlobular arteries was 25.7 mum (S.D. 2.6). It is suggested that the pressure drop along some interlobular arteries may be of physiological importance, affecting the autoregulation of blood flow in the renal cortex.

Intrarenal venous and cortical catheter pressures in the dog kidney.

To examine the validity of intrarenal venous pressure (IRVP) as a measure of peritubular capillary pressure when obtained with a method applicable in man, IRVP was measured with a 0.9 mm o.d. catheter introduced retrograde into interlobar veins of anesthetized dogs and was compared with a modified needle pressure (cortical catheter pressure = RCCP) measured simultaneously in the same kidneys. In twelve dogs with a mean experimental kidney control sodium excretion of 91 +/- 15 (SEM) micronmol/min IRVP averaged 16.0 +/- 1.1 mmHg and was significantly lower than the average RCCP of 22.6 +/- 1.1 mmHg (P less than 0.001). These pressures compare well with the reported micropuncture pressures in the peritubular capillaries and proximal tubules, respectively, at comparable levels of sodium excretion. IRVP fell significantly during reduction of renal perfusion pressure within the range of autoregulation of renal blood flow and increased during elevation of renal pelvic pressure (PP). At at PP of 60 mmHg, when urine flow had stopped, the PP-IRVP gradient was 22.7 +/- 3.1 and increased to 36.7 +/- 3.8 (P less than 0.001) at a PP of 80. Acute renal vein constriction always increased IRVP before renal vein pressure reached the preceeding control level of IRVP. Increased urine flow during saline volume expansion and furosemid infusion was associated with increased IRVP. The results when compared with micropuncture data indicate that IRVP is a satisfactory expression of peritubular capillary pressure in the experimental conditions included in the study.

Distribution of Radioisotope-Labeled Microparticles in the Renal Cortex of Dogs in Hemorrhagic Hypotension

Isotope-labeled microspheres with an average diameter of 15 μ and 25 μ, and isotope-labeled macroalbumin (131MA) were injected into the aorta of 26 dogs before or after the animals were bled to hemorrhagic hypotension. The localization of the microspheres was studied by microscopical examination and the intrarenal distribution of the radioactivity was measured. No significant effect of the hemorrhagic hypotension upon the distribution of radioactivity or the number of microspheres in different cortical layers was observed in normal kidneys. In surgically manipulated kidneys the hypotension provoked a relative increase of the radioactivity in the middle and juxta-medullar parts of the renal cortex. In the early phase of hemorrhagic hypotension the fraction of spheres with a diameter greater than 20 μ recovered in the glomeruli increased from zero to 6.3% when compared with normotensive animals; this indicates a dilatation of the afferent arterioles in this phase of hemorrhagic hypotension.

Postglomerular vascular hydrostatic and oncotic pressures during acute saline volume expansion in normotensive man

The importance of the peritubular physical factors as mediators of the natriuretic response to saline volume expansion was examined in twenty normotensive, hydropenic indivduals. Intrarenal venous pressure (IRVP), used as a measure of peritubular capillary hydrostatic pressure, and efferent arteriolar colloid osmotic pressure, calculated from arterial colloid osmotic pressure and the filtration fraction, were measured before and during sustained volume expansion with 0.9% NaCl, increasing the body weight by 3% and plasma volume about 20%. During expansion there was a significant increase in urine flow from 1.1 +/0 0.1 to 3.1 +/- 0.4 ml/min and sodium excretion from 161 +/- 12 to 551 +/- 61 microEq/min. Efferent colloid osmotic pressure fell from 31.9 +/- 0.6 to 23.6 +/- 0.5 mmHg (P less than 0.001) while IRVP changed from 24.8 +/- 0.8 to 25.1 +/- 0.9 mmHg (P greater than 0.10). In eight individuals IRVP increased during saline loading but later fell during sustained expansion. Glomerular filtration rate and renal blood flow did not change significantly. It is concluded that increase in peritubular capillary hydrostatic pressure is not necessary either to induce or to maintain the natriuresis of a moderate saline volume expansion. Although the fall in postglomerular vascular colloid osmotic pressure is a possible mediator of the natriuretic response, the change in peritubular transcapillary net driving force produced by a modest saline volume expansion is probably small.

Screening for Hematuria, Glucosuria and Proteinuria in People Aged 55-64 Technical, Clinical and Cost-benefit Experience from a Pilot Study

A total of 754 persons randomly selected from the age group 55-64 years were invited by letter to take part in a screening for hematuria, proteinuria and glucosuria. Each person was asked to provide one sample of morning urine and immediately mail it to the laboratory. A total of 413 persons (55%) responded. Two dipsticks: BM-Test-5L and a new single strip for hematuria determination preliminary named BM 33075 were used, both manufactured by Boehringer Mannheim GmbH. The test strips gave positive reaction for hematuria in 21 persons (5.1%), for proteinuria in 14 persons (3.4%), and for glucosuria in six persons (1.5%). All persons with positive tests were invited to follow-up investigations. In the hematuria group we found one person with a malignant disease, 13 with benign conditions and in seven persons we found no reason for the hematuria. Among those with proteinuria one person had a nephritis. Four persons with glucosuria knew about their diabetes mellitus. The cost of the screening was NOK 99 per participant.