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Biomedical subjects

J Böhler

Publications and source records attributed to J Böhler.

At least 37 records · Page 2Linked to original sources
PubMed1994

Bicarbonate-based dialysis solution preserves granulocyte functions.

OBJECTIVE: Intraperitoneal phagocytes play an important role in local defense in preventing continuous ambulatory peritoneal dialysis (CAPD) peritonitis. This study therefore investigates the effect of the conventional lactate-based dialysis solution-pH 5.2 (LBDS-pH 5.2) and a bicarbonate-based dialysis solution (BBDS) on various cell functions. DESIGN: We studied C5a-induced actin polymerization (AP) as a measure of the cytoskeletal alteration, phagocytosis of zymosan particles, and chemotaxis in neutrophils incubated in either LBDS-pH 5.2, LBDS-pH 7.4, or BBDS-pH 7.4, comparing the data with cells treated with phosphate-buffered saline-pH 7.4 (PBS-pH 7.4) as a control. SUBJECTS: Polymorphonuclear neutrophils (PMNs) were isolated from the blood of healthy donors and incubated with dialysis solution prior to the experiment. RESULTS: C5a-induced AP was dramatically inhibited in PMNs incubated in LBDS-pH 5.2, paralleled by a complete inhibition of phagocytosis and C5a-induced chemotaxis. In comparison, BBDS improved AP to values above the control and also nearly normalized phagocytosis. Chemotaxis markedly improved in cells treated with the low glucose-containing BBDS (Bic 20), containing high glucose concentrations (Bic 30). CONCLUSION: In comparison with conventional lactate-based dialysis solution-pH 5.2, bicarbonate-based dialysis solution at low osmolality better preserves neutrophil functions that involve the cytoskeleton.

Actins↗
PubMed1994

Carrier-status for nasal staphylococci does not predict infections in CAPD patients.

It has been reported that nasal carriage of staphylococci may contribute to infections of the continuous ambulatory peritoneal dialysis (CAPD) catheter exit site or cause peritonitis due to this pathogen. Recently, a nasal ointment to eradicate these bacteria in patients and staff has been marketed with the implication that this treatment may reduce infection rates. In this study, we investigated 37 patients treated with CAPD for a mean of 38.8 +/- 6.4 months. Presence of nasal carriage of staphylococci was assessed using standard nasal swab techniques and related to bacteria identified at the time of previous infections. Results were analyzed using Spearman rank order correlation and linear regression analysis. In 119.5 patient years at risk, 50 infections with staphylococci (24 episodes of peritonitis and 26 exit-site infections) were evaluated. Nineteen patients were carriers of S. aureus or S. epidermidis; 6 patients were carrying both species. There was no correlation of current nasal carriage of staphylococci with previous infection. Although 23 of 37 patients were carriers, 14 of these never had infections due to nasal staphylococci. Only in 14 of 50 infections were bacteria species the same in the nose and at the site of infection. We conclude that prospective trials demonstrating a reduction of CAPD-related infections are needed before general use of prophylactic nasal antibiotic treatment can be recommended in these patients.

Adult↗
PubMed1994

Effects of simvastatin on lipoprotein (a) and lipoprotein composition in patients with nephrotic syndrome.

The influence of simvastatin, a competitive inhibitor of 3-hydroxy-3-methyl glutaryl coenzyme A reductase, on quantitative and qualitative changes in lipoprotein metabolism was investigated in 18 patients (group I, 10 with primary kidney disease and group II, 8 with diabetic nephropathy) with nephrotic syndrome. Nephrotic patients exhibited severe hyperlipidemia (serum cholesterol 390 +/- 17 mg/dl and triglyceride 335 +/- 42 mg/dl; mean +/- SEM) and had significantly higher lipoprotein (a) [Lp(a)] levels (54 +/- 12 mg/dl; median 31 mg/dl, p < 0.01) compared with 20 healthy subjects (mean 12 +/- 1.8 mg/dl; median 7 mg/dl). Fifty-six percent of the patients and 15% of the controls had values greater than 30 mg/dl. Treatment with simvastatin in increasing doses over a period of three months (13 patients received 40 mg/day and 5 patients 20 mg/day at the end of the third month) reduced LDL-cholesterol in both groups of patients (35% and 54%) as well as apolipoprotein B (apoB) (31% and 46%) significantly, but Lp(a) levels were not influenced (57 +/- 21 vs 59 +/- 20 and 50 +/- 14 vs 53 +/- 16 mg/dl, respectively). On the other hand a complex change in lipoprotein composition occurred. The ratio of LDL apoB/LDL cholesterol-ester increased significantly (0.75 +/- 0.03 to 0.84 +/- 0.03 and 0.80 +/- 0.03 to 1.02 +/- 0.1, respectively) and cholesterol concentration in VLDL (64 +/- 16 to 39 +/- 7 and 74 +/- 18 to 55 +/- 74 mg/dl, respectively) was reduced.(ABSTRACT TRUNCATED AT 250 WORDS)

Female↗
PubMed1993

Effect of antihypertensive drugs on glomerular hyperfiltration and renal haemodynamics. Comparison of captopril with nifedipine, metoprolol and celiprolol.

Glomerular hyperfiltration and hypertension may contribute to the progression of chronic renal insufficiency regardless of the underlying disease. Protein restriction and antihypertensive treatment are used to slow the decline in renal function. However, little is known about the interaction of protein loading and antihypertensive treatment on glomerular haemodynamics in humans. This paper compares the renal haemodynamic effects of beta-adrenoceptor blockers with those of the calcium channel antagonist nifedipine and the ACE inhibitor captopril on resting glomerular filtration and during glomerular hyperfiltration. In two separate studies the effects of nifedipine, captopril, metoprolol, and celiprolol on renal haemodynamics have been investigated. In two groups of healthy volunteers (n = 13) inulin and PAH clearances were measured, first under fasting conditions and afterwards during aminoacid infusion. In fasting subjects nifedipine and metoprolol induced glomerular hyperfiltration, while celiprolol and captopril did not significantly affect GFR. Without premedication, and also after nifedipine, metoprolol and celiprolol, the aminoacid infusion significantly increased the GFR. After premedication with captopril, however, aminoacid-induced hyperfiltration was prevented. In fasting subjects captopril, celiprolol and metoprolol elevated PAH clearance. With our without premedication aminoacid infusion increased renal plasma flow compared to baseline on the control day. We conclude that in healthy subjects, acute administration of antihypertensive drugs results in different renal haemodynamic responses. In contrast to captopril and celiprolol, nifedipine and metoprolol induce glomerular hyperfiltration like protein loading. Thus, they may counteract the renal haemodynamic effects of protein restriction. Celiprolol behaves similarly to captopril, since it increases renal perfusion without inducing glomerular hyperfiltration, a pattern which might reflect lower glomerular pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Antihypertensive Agents↗
PubMed1993

Drug dosage in patients during continuous renal replacement therapy. Pharmacokinetic and therapeutic considerations.

The advantages of continuous haemofiltration and haemodialysis over intermittent haemodialysis for the treatment of acute renal failure are well recognised. In intensive care patients, 4 different continuous procedures, arteriovenous and venovenous haemofiltration (CAVH and CVVH) or haemodialysis (CAVHD and CVVHD), are employed. These effective detoxification treatments require knowledge of their influence on drug disposition. Data on kinetics of drugs during continuous treatment are scarce and limited almost exclusively to the oldest and least effective procedure (CAVH). Selected dialysis membranes may adsorb drugs, as in the case of aminoglycosides. In addition, elimination of substances with large molecular weights may vary depending on the pore size of the membrane, as in the case of vancomycin. Thus, even if drug dosages can be based on pharmacokinetic studies, selection of a dialysis membrane not studied may cause unpredictable drug concentrations. With these limitations in mind and considering the available literature on pharmacokinetics in patients with renal failure, general guidelines for drug dosage during continuous renal replacement therapy can be given. In haemofiltration, drug protein binding is the major factor determining sieving, i.e. the appearance of the drug in the ultrafiltrate. In haemodialysis, diffusion is added to ultrafiltration, and therefore the saturation of the combined dialysate and ultrafiltrate will decrease further with increasing dialysate flow rate. In continuous haemofiltration or haemodialysis the extracorporeal clearance can be calculated by multiplying the saturation value (estimated or, better, measured) with the ultrafiltrate and dialysate flow rate. Dividing the extracorporeal clearance by the total clearance (including the nonrenal clearance) gives the fraction of the dose removed due to extracorporeal elimination. Whether dosage recommendations available for anuric patients have to be modified or not can be decided on the basis of this value. In case of high nonrenal clearance, the degree of saturation is without clinical significance. Based on these considerations guidelines have been constructed for the effect of extracorporeal elimination on more than 120 different drugs commonly used in intensive care patients.

Drug Therapy↗
PubMed1993

Inhibition of C5a-induced actin polymerization, chemotaxis, and phagocytosis of human polymorphonuclear neutrophils incubated in a glucose-based dialysis solution.

Chemotaxis and phagocytosis are important functions of phagocytic cells, which are closely related to cytoskeletal reorganization. These functions may be abnormal in phagocytes of uremic patients undergoing continuous ambulatory peritoneal dialysis (CAPD). In order to examine whether these abnormalities result from treatment, we studied actin polymerization (AP), as an index of cytoskeletal alterations, chemotaxis, and phagocytosis in polymorphonuclear neutrophils (PMNs) of healthy subjects. Polymorphonuclear neutrophils were exposed to either a hepes buffer or a glucose-based dialysis solution (GBDS) of different pH's (5.2, 7.4) and different glucose concentrations (1.36%, 2.27%, 3.86%). After incubation for 0, 5, or 20 minutes, cells were activated with 10 nmol/L C5a-complement. AP was measured as filamentous (F) actin content by NBD phallacidin staining and FACS analysis. Chemotaxis of PMNs was measured in Boyden chambers. In addition, phagocytosis of zymosan particles was assessed. Prior exposure to GBDS pH 5.2 of each glucose concentration immediately and completely inhibited AP in response to 10 nmol/L C5a-complement, reduced chemotaxis (> 95%), and completely inhibited phagocytosis. The inhibition was pH-dependent, since GBDS pH 7.4 caused less inhibition of these functions. We conclude that glucose-based dialysis solutions are cytotoxic towards neutrophils and completely inhibit their ability to display responses requiring cytoskeletal reorganization.

Actins↗
PubMed1993

Mediators of complement-independent granulocyte activation during haemodialysis: role of calcium, prostaglandins and leukotrienes.

Granulocyte activation during haemodialysis using cuprophane membrane is mediated by complement-derived anaphylatoxins C3a and C5a. However, neutrophil degranulation induced by modified cellulosic membranes or synthetic membranes does not correlate with C3a or C5a concentrations. Incubation and recirculation experiments were performed to find out which messengers trigger neutrophil degranulation during blood contact with different membrane materials. During in vitro haemodialysis for 2 hours, PMMA and cuprophane induced pronounced degranulation of neutrophils. With PMMA this was associated with increased thromboxane B2 but low C3a levels, while with cuprophane membrane, marked complement activation but only little thromboxane B2 release was observed. Indomethacin (10 microM) nullified all thromboxane B2 response but could not influence elastase release, indicating that cyclo-oxygenase products are not involved in neutrophil degranulation under these conditions. During incubation of blood with dialysis membranes, inhibition of lipoxygenase by esculetin or of phospholipase A2 by hydrocortisone also had no effect on neutrophil degranulation. One messenger involved in granulocyte activation might be free cytosolic calcium. Application of different calcium channel blockers (verapamil, diltiazem, or nitrendipine) did not influence neutrophil degranulation in incubation experiments, in PMMA or cuprophane membranes. In contrast, chelation of plasmatic calcium by sodium citrate or EDTA blunted elastase release induced by these membranes. This study indicates that calcium is a key mediator required for neutrophil degranulation in complement-activating and non-complement-activating dialysis membranes, while activation of the prostaglandin or leukotriene cascade are not required.

Adult↗
PubMed1993

Renal functional reserve in elderly patients.

The concept of renal functional reserve (RFR) is used in the evaluation of renal function in health and disease. RFR is defined as the difference between glomerular filtration rate (GFR) at rest and the maximum GFR for example under stimulation by an amino acid infusion or a protein rich meal. GFR decreases normally with age by about 1 ml/min per year. The purpose of this study was to establish the effect of the GFR decrease with age on absolute and relative values of RFR. We investigated 12 hospitalized patients 60 to 85 years of age (mean 74 +/- 2.0 SEM) recovering from nonrenal disease. On two consecutive days, inulin and paraaminohippuric acid (PAH) clearance was performed over a period of 4 hours. On day A patients received 1 liter of a 5% glucose solution i.v. On day B an equal volume of an amino acid solution (2 mg/kg/min) was given. In these elderly patients baseline GFR without stimulation measured 73.2 +/- 7.9 ml/min per 1.73 m2 and stimulated GFR was 99.1 +/- 8.5 ml/min, a 35.3% increase (p < 0.025). Thus, renal functional reserve measured 25.9 +/- 8.7 ml/min. PAH clearance increased from 329.0 +/- 41.9 ml/min per 1.73 m2 to 438.8 +/- 50.3 ml/min (p < 0.025). These data confirm that baseline GFR is lower in the elderly compared to young adults. However, renal functional reserve is well maintained in elderly human subjects. This suggests that glomerulosclerosis of aging may not be the only explanation for the low baseline GFR in the elderly.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1992

Rebound of plasma vancomycin levels after haemodialysis with highly permeable membranes.

Vancomycin is usually given only once a week to haemodialysis (HD) patients. If highly permeable dialysis membranes are used, however, high clearance values have been reported, so the aim of the study was to determine whether high clearance of vancomycin resulted in sufficient drug elimination to induce subtherapeutic plasma levels after one week. In 18 chronic HD patients, treated with polysulfone dialyzers (1.2 m2), the pharmacokinetics of vancomycin were studied after administration of 1 g. Concentrations were determined by fluorescence polarisation immunoassay. At a blood flow of 219 ml.min-1, HD clearance of vancomycin was 62.3 ml.min-1. Immediately after dialysis plasma concentrations were 38% lower than predialysis levels. However, marked rebound in the vancomycin level was observed 5 h later, resulting in plasma levels only 16% lower than prior to dialysis. 3 HD treatments in 1 week removed about one third of the initial dose. After one week 15 of 18 patients still had a therapeutic plasma level (greater than 4 micrograms.ml-1). In conclusion, polysulfone membranes show high clearance of vancomycin. However, transfer of drug from blood to dialysate appears to be faster than from tissues to blood. Because of a marked rebound in plasma level after treatment, therapeutic drug concentrations will still be present in most patients after one week.

Female↗
PubMed1992

Effect of nifedipine and captopril on glomerular hyperfiltration in normotensive man.

Glomerular hyperfiltration and hypertension induced by extensive loss of renal parenchyma are suspected to accelerate progression of renal failure. Amino acid infusion or protein ingestion also modify renal hemodynamics and increase glomerular filtration rate (GFR). This phenomenon was used to study the influence of two commonly used antihypertensive agents, captopril and nifedipine, on renal hemodynamics at rest and during glomerular hyperfiltration. Thirteen healthy volunteers were studied on three separate days (days A, B, and C) in random sequence: inulin and p-amino hippurate (PAH) clearance were measured first under glucose infusion and afterwards under stimulation by amino acid infusion (0.35 mmol/kg/min; 4 mg/kg/min). Day A served as a control, where no medication was given. On day B, 10 mg nifedipine, and on day C, 25 mg captopril, were administered orally before study. Without premedication (= day A, control) GFR increased from 108.0 +/- 6.9 mL/min (SEM) to 131.7 +/- 7.0 mL/min (P less than 0.05). On day B (nifedipine), GFR before stimulation by amino acids was already elevated to 121.8 +/- 4.2 mL/min (P less than 0.05 compared with day A) and increased to 132.6 +/- 6.3 mL/min with infusion of amino acids, thus to the same range as on day A without medication. On day C, after captopril, GFR did not increase with infusion of amino acids (from 112.5 +/- 7.2 to 117.3 +/- 6.3 mL/min). Our results indicate the calcium channel antagonist nifedipine and the angiotensin-converting enzyme (ACE) inhibitor captopril differ in their effect on intrarenal hemodynamic parameters. Nifedipine induces hyperfiltration at rest and allows maximal hyperfiltration to develop under amino acid infusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Blood flow dependent granulocyte activation in membranes with and without complement activation.

Synthetic membranes activate the complement system to some degree but also clear complement fragments from the circulation by adsorption and/or filtration and dialysis, PAN and PMMA even lower preexisting plasma levels of C3a. Activation of granulocytes measured as elastase release does occur with all membranes and might be due to complement activation. However, in synthetic membranes no correlation exists between levels of complement fragment C3a and elastase release. Instead, even when PMMA membrane lowered preexisting plasma levels of the C3a below baseline, activation of granulocytes to a similar degree as known from cuprophane membranes was observed. This activation did occur with blood flow of 200 ml/min during recirculation, but not without blood flow during incubation of membrane material. We conclude that granulocyte activation in synthetic membranes does not require an activated complement system, but may be a blood flow dependent phenomenon.

Acrylic Resins↗
PubMed1991

Biocompatibility of four plasmapheresis membranes in patients treated for hypercholesterolemia.

Membrane plasma separation uses artificial polymers which might interact with blood components during treatment. In 7 patients treated for familial hypercholesterolemia with heparin-induced extracorporeal LDL precipitation (HELP), we studied 4 different synthetic plasma separation materials. The effect of membranes made from polyethylene, polymethylmethacrylate (PMMA), polypropylene and polysulfone on complement activation (C3a), granulocyte elastase release and granulocyte count were measured repeatedly during the treatment. Polyethylene and PMMA induced high levels of plasma elastase and marked granulocytopenia after 60 min of treatment, much later than during hemodialysis, where granulocyte nadir is known to occur already after 15 min. Polysulfone and polypropylene did not change granulocyte counts and caused only modest levels of elastase during plasmapheresis. Complement activation was present in all 4 membranes but with polyethylene, very high concentrations of C3a were detected. These data indicate that irritation of immune system components as granulocytes or the complement system do occur during plasmapheresis to different degrees depending on the membrane material used. Reinfusion of plasma after processing increases the amount of plasmatic activation products infused into the patient. This was the case, although the plasma processing procedure itself did not add activation products to the plasma. Activation patterns during plasma separation differ from those known to occur during hemodialysis despite use of the same polymer. Immunocompromised patients treated with plasmapheresis may react differently than these otherwise healthy subjects with familial hypercholesterolemia.

Biocompatible Materials↗