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G H Schaap

Publications and source records attributed to G H Schaap.

11 recordsLinked to original sources
PubMed1989

Effects of chronic and acute protein administration on renal function in patients with chronic renal insufficiency.

In 6 volunteers with normal renal function, we investigated the effects of various kinds of protein (soy, lactoprotein and beef) and various amounts of an intravenously administered amino acid solution on glomerular filtration (GFR) and effective renal plasma flow (ERPF). As for the protein-induced changes in renal function, rises in GFR and ERPF were lowest with soy protein, and highest with beef (baseline GFR, 110 +/- 5; soy, 122 +/- 5; beef, 131 +/- 5 ml/min/1.73 m2; mean +/- SEM). High doses of intravenous amino acids induced a rise in GFR comparable to that after beef (132 +/- 5 ml/min/1.73 m2). In a combined test a liquid mixed meal together with intravenously administered amino acids induced a comparable increase of the GFR (baseline 114 +/- 5 versus 129 +/- 5 ml/min/1.73 m2). When investigating 9 patients with chronic renal insufficiency after 4 weeks of low protein intake (LP) and after 4 weeks of high protein intake (HP), GFR and ERPF rose significantly under baseline conditions (GFR-LP41 +/- 9 versus GFR-HP 45 +/- 9 ml/min/1.73 m2, p less than 0.02; ERPF-LP 169 +/- 39 versus ERPF-HP 180 +/- 40 ml/min/1.73 m2, p less than 0.02; paired Wilcoxon). At the end of both dietary periods a comparable rise in renal function could be induced through acute stimulation (GFR-LP 20 +/- 5, GFR-HP 16 +/- 4; ERPF-LP 23 +/- 7, ERPF-HP 22 +/- 3%).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

99mTc-MAG3: dynamic studies in patients with renal disease.

Animal studies have suggested that 99mTc-mercapto-acetylglycyl-glycyl-glycine (99mTc-MAG3) might be suitable for the determination of the renal plasma flow (RPF) because of its high renal clearance. In this study 131I-orthoiodohippurate (131I-OIH) and 99mTc-MAG3 (labeling always greater than 95%) were administered simultaneously in 11 patients (creatinine clearance ranging from 14 to 130 ml/min per 1.73 m2) to measure effective RPF(ERPF) using the standard technique (UV/P). Glomerular filtration rate (GFR; clearance of 125I-thalamate, 125I-OT) was also measured. The mean ratio of 99mTc-MAG3 clearance to 131I-IOH clearance was 0.55 +/- 0.02 (SEM), P less than 0.01, n = 16, and was independent of GFR and ERPF. To study this difference in renal handling of the radiopharmaceuticals, renal extractions by the right kidney were determined in another six patients after a single shot of the agents. Renal extraction of 99mTc-MAG3 was 0.60 +/- 0.03 after 5 min, and 0.41 +/- 0.08 after 30 min. Renal extraction of 131I-OIH amounted to 0.86 +/- 0.04 and 0.77 +/- 0.03, respectively. Using renal extractions of 0.41 and 0.77, respectively, it appeared that calculated renal plasma flows measured simultaneously with 99mTc-MAG3 and 131I-OIH were similar. Protein binding 30 min after the priming dose was 66% for 99mTc-MAG3 and 47% for 123I-OIH. We conclude that in spite of a high renal clearance (ratio to 125I-OT clearance 2.69 +/- 0.27), 99mTc-MAG3 seems unsuitable for an accurate determination of the RPF.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Effects of protein intake variation and omega-3 polyunsaturated fatty acids on renal function in chronic renal disease.

Fifteen patients with chronic renal disease of various origin were investigated after 4 weeks protein restriction, after 4 weeks high protein intake and finally, after 8 weeks dietary supplementation with omega-3 polyunsaturated fatty acids (PUFA's), while adhering to a high protein intake. The highest values for effective renal plasma flow and glomerular filtration rate were observed after 8 weeks dietary supplementation with omega-3 PUFA's without a relationship with baseline values. Calculated renal resistance fell after omega-3 PUFA supplementation. Whether long term dietary supplementation with omega-3 PUFA's will influence the progression of chronic renal insufficiency in man needs further study.

Adult↗
PubMed1987

The effect of a high protein intake on renal function of patients with chronic renal insufficiency.

In 30 patients with chronic renal disease, glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) were measured after 4 weeks of protein restriction and subsequently after adhering to a high protein intake for the same period. Twenty-four patients adhered to their advised diets according to the 24-hour urea excretion. These 24 patients showed a significant increase in GFR, ERPF and proteinuria (n = 15) during a high protein intake, even if their renal function was markedly impaired. It is concluded that although in patients with markedly impaired renal function a meat meal or an infusion of amino acids does not change renal function anymore, prolonged high protein intake is accompanied by an increase in GFR, poorly dependent on GFR after prolonged protein restriction.

Adult↗
PubMed1984

Fluorescence polarization of six membrane probes in embryonal carcinoma cells after differentiation as measured on a FACS II cell sorter.

Fluorescence polarization measurements on a FACS II cell sorter were compared with static measurements on a spectrofluorimeter using calibration solutions and Hoechst 33258-labeled cells. For the flow cytometric measurements on the FACS we used a pseudodepolarizer for normalization of the output of the two photomultipliers. The results showed that fluorescein and fluoresceinated bovine serum albumin (BSA) solutions gave identical values on both instruments. The mean value for fluorescence polarization of Hoechst 33258-labeled cells as measured on the FACS was the same as the value obtained with the spectrofluorimeter. Subsequently the fluorescence polarization of six different membrane probes was determined using differentiating embryonal carcinoma cells as a model system. Differentiation was induced by treatment of the cells with retinoic acid together with cyclic AMP. With diphenylhexatriene (DPH) the fluorescence polarization increased from I/I = 1.55 to 1.74 upon differentiation. With a charged analog of DPH (TMA-DPH) fluorescence polarization increased from I/I = 1.87 to 2.02. No appreciable changes in fluorescence polarization were observed in this cell system when anthroyloxysterate probes (12-AS, 9-AS, 6-AS, 2-AS) were used.

Animals↗
PubMed1984

Gene expression in flow sorted mouse teratocarcinoma X human fibroblast heterokaryons.

Mouse teratocarcinoma cells and primary human fibroblasts were fluorescently labelled with fluorescein isothiocyanate (FITC)- and trimethylrhodamine isothiocyanate (TRITC)-stearylamine respectively. After fusion populations highly enriched for red-green heterokaryons (around 80%) were isolated from the fusion mixture using a FACS II cell sorter. To study gene expression in the early hybrids [35S] methionine-labelled proteins synthesized by the sorted cells at two and three days after fusion were analysed by two-dimensional gel electrophoresis. Three spots were denser in gels of the fused cells than in those of 1:1 mixtures of parental cells. For one of these proteins it could be demonstrated that this reflects the enhanced synthesis of a mouse-specific protein present only in small amounts in teratocarcinoma cells. All three proteins were synthesized in relatively large amounts by differentiated mouse cells. Collagen (type I) synthesis by the sorted hybrid cells was studied by analysing the [3H] proline-labelled material secreted into the medium. Analysis by sodium dodecyl sulphate (SDS)-gel electrophoresis and two-dimensional nonequilibrium pH gradient electrophoresis showed that the material secreted by the fused cells five days after fusion was the same as that secreted by the human fibroblasts. No evidence was obtained for synthesis of mouse alpha 2(I) collagen. The amount of collagen produced by the sorted cells five days after fusion was about half the amount produced by the human fibroblasts. Immunofluorescence studies also showed that collagen synthesis was not suppressed after fusion both in heterokaryons and synkaryons. In conclusion, we did not find evidence for activation of a previously completely silent mouse gene in the fused cells. The results show, however, that the fused cells do resemble the differentiated fibroblasts rather than the undifferentiated teratocarcinoma cells.

Animals↗
PubMed1983

Flow sorting in the study of cell-cell interaction.

Undifferentiated mouse teratocarcinoma cells were cocultivated with differentiated mouse endoderm cells in order to study the possible induction of teratocarcinoma cell differentiation. A difference in DNA content between the two cell types was experimentally introduced to enable the reisolation of the teratocarcinoma cells after cocultivation. Pseudotetraploid (2s) endoderm cell lines were produced from pseudodiploid (1s) cells by treatment of these cells with cytochalasin B and flow sorting of tetraploid cells, using Hoechst 33342 as a viable DNA stain, with subsequent cloning of sorted single cells. In model experiments, where mixtures of 1s teratocarcinoma and 2s endoderm cells were stained with Hoechst 33342, the teratocarcinoma cells could be reisolated with a purity of about 97%. After a cocultivation period of 24 days viable teratocarcinoma cells could be isolated from the cocultivation mixture with a purity of 95%. Two dimensional analysis of the protein pattern of these cells indicated that cocultivation did not induce a differentiated (endoderm) pattern. Therefore according to this analysis the teratocarcinoma cells were not induced to differentiate during a 24 day cocultivation period. The method described offers excellent possibilities for studying cell-cell interaction in vitro.

Animals↗
PubMed1965

[Enteroviruses].

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Enterovirus↗