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Biomedical subjects

R Vanholder

Publications and source records attributed to R Vanholder.

At least 199 records · Page 11Linked to original sources
PubMed1989

General planning of an artificial organ center.

There is an increasing need for research and development centers to deal with design and evaluation of organ replacement systems, the improvement of older devices, and the study of biocompatibility problems. Special attention, in this article, is focused on the determinant role of the background of the investigators involved in a given center and the selection of research programs to be pursued. Financial and architectural aspects are discussed in general terms. Appropriate planning of artificial organ centers should allow conceptualizing research and development that will exert a practical impact on patient care locally and worldwide.

Animals↗
PubMed1989

Hemodiafiltration.

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Blood Pressure↗
PubMed1989

The inhibition of thromboxane synthesis has no influence on HgCl2-induced acute renal failure in the rat.

Renal function parameters and urinary thromboxane B2-excretion were studied in the rat in HgCl2-induced acute renal failure. Studies were performed before and 3 h after the inhibition of thromboxane synthesis alone, after HgCl2 alone, or after the combination of HgCl2 and thromboxane-synthesis inhibition. Thromboxane-synthesis inhibition alone by indomethacin (5 mg/kg i.v.), imidazole (25 and 50 mumol/kg per min i.v.) and dazoxiben (5 mg/kg i.v.) had no effect on glomerular filtration rate (GFR) or para-aminohippuric acid clearance (CPAH), whereas urinary thromboxane excretion was suppressed. Only the administration of the selective blockers imidazole and dazoxiben resulted in a marked increase in urinary volume (V) and fractional sodium excretion (FENa). HgCl2 alone (2 mg/kg i.v.) caused a decrease in GFR and CPAH with -38% (P less than 0.01), and urinary thromboxane B2 excretion increased from 20.3 +/- 1.5 to 30.6 +/- 2.6 pg/min. (P less than 0.01). The administration of indomethacin, imidazole (50 mumol/kg per min) and dazoxiben prevented the increase in thromboxane B2 excretion 3 h after HgCl2 to values of 3.3 +/- 1.2, 6.9 +/- 0.6 and 13.0 +/- 1.6 pg/min respectively (P less than 0.01 versus control for all values). Despite this, the decrease in GFR and CPAH after HgCl2 could not be prevented. A decrease of GFR with -44, -54, -57 and -32% and of CPAH with -37, -49, -57 and -27% were observed for indomethacin, imidazole 25 and 50 mumol/kg per min and dazoxiben respectively. This evolution was not significantly different from what was observed with mercury alone. Selective thromboxane synthesis inhibition resulted in a decrease of serum free ionised calcium.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Kidney Injury↗
PubMed1989

[Influence of age on the indications for continuous ambulatory peritoneal dialysis].

A retrospective 10 year analysis of the reasons for admitting patients in a university hospital CAPD or hemodialysis program is performed. More specifically, the influence of age as indicator has been investigated. It appears that since 1983, the CAPD population becomes progressively younger and the hemodialysis population older. This is mainly due to preferential admission in CAPD of young diabetics and because of patients preference. The reasons for dropout and prognosis after transfer to another mode of treatment are discussed.

Adolescent↗
PubMed1988

[Biocompatibility].

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Biocompatible Materials↗
PubMed1988

Development of anti-N-like antibodies during formaldehyde reuse in spite of adequate predialysis rinsing.

The development of anti-N-like antibodies has been demonstrated with formaldehyde reuse of hemodialyzers. It has been recommended to pursue a postrinsing venous effluent formaldehyde concentration in the range of or below 2 to 10 ppm, in order to prevent the development of these anti-N-like antibodies. In the present study, we evaluated formaldehyde reuse in a population of 50 patients and whether the strict control of predialysis effluent formaldehyde concentration below 2 to 3 ppm could prevent the development of anti-N-like antibodies. Five of 50 patients (10%) became positive 6 to 14 months after the start of formaldehyde reuse, indicating that even a careful control of effluent formaldehyde concentration cannot prevent the occurrence of this abnormality.

Adult↗
PubMed1988

Drug protein binding in chronic renal failure: evaluation of nine drugs.

In this study, changes of protein binding of nine drugs were evaluated. In addition, theophylline and phenytoin, the two drugs with the most substantial and progressive decrease in protein binding, were further studied by high performance liquid chromatography (HPLC)-fractions of ultrafiltrate of normal and uremic serum, in an attempt to identify substances causing drug protein binding inhibition. There was a marked decline of the protein binding of theophylline, phenytoin and methotrexate (dialyzed patients vs. normals: -20.1, -16.0 and -15.1%, respectively). There was a rise in the protein binding of propranolol, cimetidine and clonidine. The changes observed for diazepam, prazosin and imipramine were less marked. For phenytoin, theophylline, methotrexate and diazepam, protein binding was inversely correlated to the serum creatinine (r = 0.87, 0.80, 0.79 and 0.67, P less than 0.001), and a less pronounced but still significant positive correlation was found for clonidine (r = 0.46, P less than 0.01). Ultrafiltrate, obtained during a hemofiltration session, inhibited protein binding of theophylline and phenytoin in a dose dependent way. After separation of this ultrafiltrate by HPLC, it appeared that for both theophylline and phenytoin at least a part of this inhibitory activity corresponded to the elution zone of hippuric acid. For theophylline two other inhibitory zones were further recognized: one corresponding to the elution zone of NaCl and one in which the responsible substance remained unidentified. Hippuric acid in solution inhibited protein binding of theophylline and phenytoin in a dose dependent way. In conclusion, protein binding of several drugs currently used in renal failure is affected in parallel with renal function, which might affect the therapeutic effectiveness of the drugs.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Proteins↗
PubMed1988

Single-needle membrane plasmapheresis. In vivo comparison of plasma separator performances.

Plasma filtration characteristics of three hollow fiber plasma separation filters (Plasmaflo Hi-05, Extraplex BL 550 and CPS-10) were studied in a single-needle setting by means of the double headpump. Plasma exchange was carried out in 12 patients during a total number of 59 sessions. For each filter, a mean total ultrafiltration volume of +/- 3,000 ml was obtained over a period from 92 to 121 min. The lowest and highest obtained mean filtration flows were 26.7 +/- 2.5 and 36.6 +/- 1.7 ml/min for Extraplex BL 550 and CPS-10, respectively (p less than 0.01). The pre- and postplasmapheresis pressures, measured in the bubble trap chamber as an indirect estimation of transmembrane pressure, were lower for the Plasmaflo Hi-05 than for the two other filters under study; pressures remained unaltered during the session. Blood pressure showed a minor but significant decline during plasmapheresis with the Plasmaflo filter. A reduction after plasmapheresis by more than 40% of the immunoglobulins IgE, IgG, IgM and IgA, and of complement factors C3 and C4 was seen for each of the filters and no significant differences between the filters were observed. An additional study on 6 filters with constant blood flow and TMP showed minor differences in the transmembrane pressure necessary to obtain a given filtration volume per unit of time and similar sieving coefficients for immunoglobulins. This study demonstrates that with this single-needle technique a satisfying immunoglobulin extraction performance was obtained for each of the filter types studied; however, there existed minor but significant differences in the patient hemodynamic status according to the membrane used.

Blood Pressure↗
PubMed1988

Search for optimizing dialysis therapy. I. Acute effects of hemodiafiltration with a highly permeable membrane and a large dose of convection and diffusion.

Based on the concept that an optimisation of dialysis therapy might be achieved by increasing the removal of small metabolic substances as well as low molecular weight proteins, hemodialfiltration (HDF) was modified. In 9 ESRD patients, HDF was performed acutely for 4 h, where 60 liters of substitution fluid were infused per patient. Two polysulphone F60 membranes in line were used as hemodialfilters. As compared to conventional hemodialysis (HD), performed with a cuprophane dialyser, HDF resulted in higher extraction indices for small solutes assessed by HPLC. Due to the large amount of convection applied, HDF was followed by significant decreases of low molecular weight proteins ranging from 9.5 kdaltons (iPTH, p less than 0.01) to 17 kdaltons (myoglobin, p less than 0.01). Analysis of the protein pattern of the serum revealed a nonlinear function in the decrease of plasma proteins after HDF. It is concluded that even though the detoxification efficacy of the described HDF method is by far superior to conventional HD in quality and quantity, the efficacy is still far from that of excretory renal function. Thus, to further improve efficacy with respect to the catabolic renal function for low molecular weight proteins, membranes for HDF or hemofiltration barriers but should surpass the sieving properties of the glomerulus in the low molecular protein range.

Adult↗
PubMed1988

Hexachlorobenzene and 1,1-di(4-chlorophenyl)-2,2-dichloroethene in serum of uremic patients and healthy persons: determination by capillary gas chromatography and electron capture detection.

The concentrations of organochlorine pesticides in serum have been determined by GC and electron capture detection. Studies were performed in 7 nondialyzed, 10 dialyzed and 6 healthy persons. Only hexachlorobenzene (HCB) and 1,1-di(4-chlorophenyl)-2,2-dichloroethene (p,p'-DDE) were consistently present. No interference by other pesticides or polychlorinated biphenyls was found by checking with GC-MS. For the nondialyzed uremic patients the average HCB concentration was 16.2 nmol/l (sigma = 6.7, n = 7), and the p,p'-DDE level 26.4 nmol/l (sigma = 31.4, n = 7). For the dialyzed uremic patients the average HCB level was 15.5 nmol/l (sigma = 11.2, n = 10) before dialysis and 17.2 nmol/l (sigma = 14.4, n = 8) after dialysis, the concentration of p,p'-DDE was 27.0 nmol/l (sigma = 38.4, n = 10) before dialysis and 28.0 nmol/l (sigma = 37.4, n = 8) after dialysis. For the healthy persons the average concentration of HCB was 7.7 nmol/l (sigma = 1.8, n = 6) and the concentration of p,p'-DDE was 20.1 nmol/l (sigma = 10.4, n = 6). HCB concentrations were significantly higher in serum of dialyzed and nondialyzed uremic patients than in controls (Wilcoxon's test).

Adult↗
PubMed1988

Correlation of a colorimetric and a HPLC method for the determination of serum hippuric acid concentrations in uremia.

Hippuric acid has been recognized as a potential marker of uremic toxicity in chronic renal failure. However, in most studies, serum hippuric acid concentrations have been determined by sophisticated methods, such as high-performance liquid chromatography. The present study was undertaken to evaluate whether the less complicated colorimetric determination method could replace such methods. Based on 21 different samples, the results obtained by both methods appeared to be correlated to each other in a highly significant way (total hippuric acid: r = 0.99, p less than 0.001; free hippuric acid; r = 1.00, p less than 0.001). Mean total and free hippuric acid concentrations and mean percent protein binding, obtained with both determination methods, were also identical. It is concluded that both the colorimetric method and high-performance liquid chromatography are equally reliable for the study of the concentration of hippuric acid in uremic serum and of its importance as a marker of the clinical and biochemical epiphenomena of uremic toxicity.

Chromatography, High Pressure Liquid↗
PubMed1988

Cefodizime: a new cephalosporin with apparent immune-stimulating properties in chronic renal failure.

In vitro experiments suggest that cefodizime, a new cephalosporin, causes an increase in phagocytic capacity. We therefore evaluated the effect of cefodizime on the phagocytic system in haemodialysis patients by an estimation of the 14CO2 production during glucose metabolisation by phagocytic cells, in the resting state, and after zymosan and latex. The production of 14CO2 after latex increased in five of six patients (mean +/- SD: from 17,932 +/- 11,859 before to 21,183 +/- 7849 d.p.m. at the end of treatment). The corresponding data after zymosan were 48,381 +/- 24,891 and 70,176 +/- 15,140 d.p.m. The improved 14CO2 production after stimulation persisted for 2 further weeks. These results suggest a stimulation in vivo of the depressed phagocytic system of the uraemic patient by cefodizime.

Cefotaxime↗
PubMed1988

Uremic toxins.

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Hemofiltration↗
PubMed1988

Are the classical markers sufficient to describe uremic solute accumulation in dialyzed patients? Hippurates reconsidered.

Interdependencies of accumulated solutes, analyzed by liquid chromatography in dialyzed and non-dialyzed patients, were studied by multivariate statistical analysis. In principal component analysis, three principal components (PC1-PC3) were retained from the data on 22 accumulated compounds in dialyzed patients, whereas only one principal component was retained from analogous data of a non-dialyzed patient group. PC1 in the dialyzed patient group comprises concentrations of hippuric acid, p-hydroxyhippuric acid, tryptophan, and five unidentified fluorescent solutes in serum. Concentrations of the classical markers urea, uric acid, creatinine, and phosphate were closely related to PC2 in these patients. Indoleacetic acid and two unidentified fluorescent compounds constitute PC3. The compounds associated with the groups found by principal component analysis may be characterized by chemical structure and by the mechanism of their excretion via the remaining nephrons of dialyzed patients. In the non-dialyzed group, most of the solutes could be described by a single PC. This PC and PC1 from the dialyzed group correlated significantly with residual renal function, and with total ultraviolet absorbance and total fluorescence emission. The data suggest that it is of value to introduce a marker of uremic solute retention in addition to urea, to account for renal-function-related "organic-acid-like" compounds that are excreted by renal tubular secretion in dialyzed patients. The hippurates may serve this purpose.

Chromatography, High Pressure Liquid↗
PubMed1987

Retention patterns.

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Chromatography, Gel↗