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Biomedical subjects

J Christoffersen

Publications and source records attributed to J Christoffersen.

50 records · Page 3Linked to original sources
PubMed1977

Single injection (51Cr)EDTA plasma clearance determination in children using capillary blood samples.

The reliability of a determination of the total [51Cr]EDTA plasma clearance (E) (and with it the glomerular filtration rate), by a simplified single injection method (injected dose: 4.5 muCi per kg b.w.) using capillary blood samples (0.2 ml), was investigated in twenty children. Clearance values determined from capillary blood samples did not differ significantly from those measured simultaneously from venous blood samples, the mean ratio +/-SD being 1.02 +/- 0.06 (n = 10). The reproducibility (total day-to-day variation) of E determined from capillary blood samples was 6.7% in children with decreased renal function (n = 3) and 6.9% in children with normal renal function (n = 7). The present data indicate that the use of capillary blood samples is an accurate and very precise approach for determination of E in children.

Child, Preschool↗
PubMed1975

LDH-isoenzymes in children. A comparison of values from capillary and venous blood.

A comparison has been made of serum values of LDH-isoenzymes obtained by simultaneous sampling of capillary and venous blood in 40 normal children. No satisfactory correlation between the paired values could be found. Evaluation of the pattern of serum LDH-isoenzymes in children therefore requires a reference, i.e. normal values of isoenzymes obtained by the same technique of blood sampling.

Capillaries↗
PubMedDate not supplied

The effect of window width on the demineralization of human dentine and enamel.

When lesion formation in dental enamel or dentine is studied in vitro, a well-defined area of the material, a 'window', is exposed to the demineralization medium. In the present experiments, we report the effect of window width on lesion formation in enamel and dentine. Rectangular windows, longest dimension always 5 mm and shortest dimension varying from 0.5 to 5 mm, were exposed to demineralization media. Lesions in dentine were formed by placing the specimens in an acidified unstirred 6% carboxymethyl cellulose (CMC) gel, an unstirred 0.5% CMC gel, a mildly stirred 0.5% CMC gel, or in a mildly stirred demineralization solution. Lesions in enamel were formed only in an unstirred acidified 6% CMC gel. pH in the demineralization media was 5.0 in all experiments. The microradiographic technique was used to assess lesion depth and mineral loss (vol% x microm) of lesions formed. Lesions formed in the unstirred gels were deeper, and there was a larger mineral loss, the narrower the window. There was no effect of window size on lesions formed in stirred systems. These effects can be explained by the strong dependence of concentration gradient in stirred gels just outside the exposed window on the window size. The phenomenon found here in vitro may at least partly explain why secondary caries may lead to localized, but relatively deep, lesions.

Carboxymethylcellulose Sodium↗