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Biomedical subjects

J Kovarik

Publications and source records attributed to J Kovarik.

At least 91 records · Page 5Linked to original sources
PubMed1992

Increased levels of plasma amylin in advanced renal failure.

Amylin, a 37 amino acid polypeptide, has been suggested to play a prominent role in the pathogenesis of insulin resistance in type II diabetes mellitus. Various studies have demonstrated most recently that amylin is cosecreted with insulin. No data are available on the elimination of amylin from the circulation. We therefore tested plasma levels of amylin, insulin and C-peptide in 49 non-obese, non-diabetic patients (27 male/22 female) with various degree of renal impairment (Group A: CCr less than 20 ml/min, n = 20; Group B: CCr 20-89 ml/min, n = 18; and Group C: CCr greater than 80 ml/min, n = 9). We found a significant increase of plasma amylin when kidney function, expressed by creatinine clearance fell below 20 ml/min (17.9 +/- 1.7 vs. 12.2 +/- 0.8 vs. 8.8 +/- 1.2 pg/ml; p = 0.0005). Plasma amylin correlated closely with serum C-peptide (r = .764; p = 0.0001), and to a lesser extent with insulin (r = .595; p = 0.0001) underlining its postulated cosecretion with these peptides. The data indicate that amylin might be eliminated by renal mechanisms. Our data show that besides type II diabetes mellitus, advanced renal failure is another clinical situation with enhanced plasma amylin levels. Whether amylin plays any pathogenetic role in renal patients remains to be elucidated.

Amyloid↗
PubMed1991

Increased Fc-receptor-mediated clearance via reticuloendothelial system in patients with nephrotic syndrome.

Reticuloendothelial phagocytic cell function, which is an important participant in host defense, was investigated by studying the Fc-receptor-mediated clearance of IgG-anti-RhD-sensitized radiolabelled autologous erythrocytes in patients with nephrotic syndrome known to have an increased risk of infectious complications due to hypogammaglobulinemia. Patients with serum IgG concentrations less than 500 mg/dl had a significantly accelerated Fc-receptor-mediated clearance (t1/2 = 52 +/- 3.6 min) compared to patients with IgG levels greater than 500 mg/dl (t1/2 = 93 +/- 17 min) or healthy controls (t1/2 = 100 +/- 7.5 min). Serum IgG concentrations correlated significantly with Fc-receptor-mediated clearance (t1/2: r = 0.70; p = 0.035) in patients with nephrotic syndrome. These results indicate that Fc-receptor-mediated clearance by the reticuloendothelial system is enhanced in patients with nephrotic syndrome with low serum IgG concentrations and may, at least in part, compensate for reduced opsonic antibody concentration.

Adult↗
PubMed1991

Bone metabolism in patients with functioning kidney grafts: increased serum levels of osteocalcin and parathyroid hormone despite normalisation of kidney function.

In order to study bone metabolism after renal transplantation we measured serum levels of parathyroid hormone (PTH) and osteocalcin (OC), a specific biochemical parameter of bone formation, in 30 patients with functioning kidney grafts and 30 sex- and age matched control subjects. Serum levels of OC and PTH were markedly elevated in the kidney transplantation patients when compared with the control subjects (p less than 0.0001). Elevated levels of OC and PTH were present even in patients with very well functioning transplants. In the kidney transplantation patients, a significant positive correlation between serum OC and serum PTH levels could be found. Our data give evidence of persistent hyperparathyroidism and increased bone turnover in patients after renal transplantation.

Adult↗
PubMed1991

Determination of cyclosporine by a competitive binding assay with cyclophilin.

A competitive protein-binding assay for cyclosporine based on use of the intracellular cyclosporine-binding protein cyclophilin (CYP) was used to measure cyclosporin A (CsA) and its bioactive metabolites in whole blood. CYP from cytoplasmic extracts or erythrocyte lysates was applied in the binding assay with use of [3H]CsA as tracer and charcoal adsorption for separating bound from free tracer. Binding affinities of various CsA analogs and metabolites correlated well with their reported in vitro immunosuppressive activities. The assay detected as little CsA as 50 micrograms/L (1 g = 0.832 mmol of CsA), analytical recovery was greater than 80%, and CVs were less than 8% for intra-assay and less than 11% for interassay precision in the range of 150-1000 micrograms/L. We used this assay to measure CsA concentrations in blood and compared the results with those measured by HPLC or by CsA-specific (monoclonal) and CsA-nonspecific (polyclonal) radioimmunoassays. Binding assay results were, in nearly all cases, less than those measured by the nonspecific RIA and frequently greater than 20% above the values determined by the CsA-specific assays. Individual patients had pronounced differences in the relative proportions of CsA, CYP-binding (bioactive) metabolites, and cross-reacting CsA metabolites. Because the presence of bioactive metabolites may considerably contribute to the immunosuppressive activity of CsA, we consider the binding assay clinically useful for measuring CsA in biological fluids.

Administration, Oral↗
PubMed1990

[OKT 3 treatment of kidney transplant recipients].

Anti-rejection therapy with the monoclonal antibody OKT 3 was effective in the treatment of acute rejection episodes in 66% (47/71) of OKT 3 treated kidney graft recipients. The success of OKT 3 therapy, however, appeared to be dependent on certain variables. Reversal of rejection differed significantly according to the indication, namely if patients were treated first line, as opposed to rescue therapy. Vascular components of rejection and/or severe interstitial rejection, as well as acute tubular necrosis were associated with a worse reversal rate. Non-responders to OKT 3 presented with significantly lower serum OKT 3 trough levels during the first three days of the treatment course. The presence of more than one of these risk factors was shown to decrease the reversal rate of rejection significantly. The variables appeared to exert their influence in an additive fashion. Administration of OKT 3 led to the induction of an acute phase reaction, which could be detected within one day after start of therapy. The incidence of both bacterial and viral infection was increased dramatically in OKT 3 treated patients as compared with graft recipients who were not treated with monoclonal or polyclonal antilymphocyte antibodies. The findings demonstrate that OKT 3 is of value in the treatment of acute rejection episodes but provide evidence of differential indications for OKT 3 therapy, which must be taken into account to optimize control of rejection and avoid unnecessary side effects where the drug is not indicated.

Antibodies, Monoclonal↗
PubMed1990

[The significance of erythropoietin for nephrology].

The analysis of the structure of erythropoietin and the subsequent production of recombinant human erythropoietin opened a new era in the understanding of the pathogenesis and therapy of renal anaemia. From the diagnostic point of view sufficiently accurate radioimmunoassays are currently available to throw new light on the pathogenesis of renal anaemia, and enable pharmacokinetic studies of the recombinant hormone to be carried on. For the first time a causal therapy is available for renal anaemia. The following review summarizes the consequences of these innovations on the different aspects of nephrology.

Anemia↗
PubMed1990

[Experiences and clinical results following 99 kidney transplantations with kidneys from relatives].

99 living related kidney transplantations were performed between January 1967 and December 1988. At the time of observation 4 of 94 organ donors had died; there was no correlation between unilateral nephrectomy and the patient's death. Intraoperative (2.9%) and postoperative (25%) complications did not result in severe physical consequences for the organ donors. Hypertension was found in 2 donors. There was no decrease in function of the remaining kidneys. The 3-year organ survival of the transplanted kidney was 60% with "conventional immunosuppression" and 93% with cyclosporin. No association was found between HLA DR-matching and graft survival. Rejection episodes occurred significantly more often in the HLA DR-mismatched grafts.

Adolescent↗
PubMed1990

Influence of HLA phenotypes on the inhibition of in vitro alloreactivity by cyclosporine.

Interindividual variations in the immunosuppressive effect of Cyclosporine have been observed in clinical organ transplantation. Searching for an in vitro correlate we investigated a possible relation between inhibition of alloresponsiveness by CsA and the HLA phenotypes of the responder or stimulator in mixed lymphocyte reactions. Peripheral blood mononuclear cells from 28 healthy volunteers were used as responder or stimulator cells (gamma-irradiated) and the inhibitory effect of graded amounts of CsA was determined in 130 criss-cross combinations. Sensitivity of alloresponsiveness to the drug was expressed as the dose causing 50% inhibition (ED50) and was read from the inhibition curves generated after four-parameter logistic curve fitting. ED50 ranged from 0.35 ng/ml to 33.4 ng/ml and correlated only weakly with the magnitude of the response (r = 0.12). In MLC with HLA DR4-positive responder cells, ED50 was significantly lower (Pc = 0.0035, Kruskal Wallis) when compared with MLC with responder cells of other DR haplotypes. For HLA DR5-positive responder cells ED50 was significantly higher (Pc = 0.042) when compared with DR5-negative responder cells. No significant correlation between ED50 and any particular haplotype of the stimulator cells could be observed. Sensitivity to CSA did not differ in MLC with 1 or 2 mismatches in the HLA-DR locus. In summary, we found that sensitivity of in vitro alloreactivity was different for particular HLA DR phenotypes, which may have important implications for the immunosuppressive therapy of transplanted patients with cyclosporine.

Cyclosporins↗
PubMed1990

Evaluation of arteriovenous fistulas and pseudoaneurysms in renal allografts following percutaneous needle biopsy. Color-coded Doppler sonography versus duplex Doppler sonography.

One hundred one patients with renal allografts were studied by two independent observers using duplex Doppler sonography (DDS) and color-coded Doppler sonography (CCDS). In all patients, single or multiple percutaneous needle biopsies of the transplant had been performed 1 to 30 days before. In 6 patients CCDS following the biopsy demonstrated an area of combined red and blue color-coded blood flow within the renal parenchyma (n = 5) or within the sinus (n = 1); the Doppler waveform was abnormal in these areas with signals above and below the zero line indicating turbulent blood flow. Consecutive intraarterial digital subtraction angiography (DSA) revealed the presence of an arteriovenous fistula (n = 4) or of a pseudoaneurysm (n = 2). In one patient, gross hematuria with obstruction of the bladder occurred as a complication of a pseudoaneurysm within the renal sinus; the bleeding could not be stopped by embolization of the lesion and the kidney had to be removed. DDS demonstrated the lesion in only one of the six patients. Thus, CCDS is the method of choice for noninvasive detection of vascular lesions due to percutaneous biopsy.

Adolescent↗
PubMed1990

Pharmacodynamics of cefepime.

The microbiological activity of cefepime was assessed in vitro against 232 clinical isolates coupled with a pharmacokinetic evaluation at steady state in six patients receiving 1 g every 12 h. MIC90s were less than or equal to 0.25 mg/l for Enterobacteriaceae and streptococci. 1 mg/l for Staphylococcus aureus and 8 mg/l for Pseudomonas aeruginosa. Mean serum concentrations in patients were 62.5 +/- 2.7 mg/l (end infusion) and 1.1 +/- 0.8 mg/l (at 12 h) with an elimination half-life 2.72 +/- 0.59 h. These data together with those published for currently marketed cephalosporins were integrated to generate an Intensity Index incorporating both the magnitude and duration that drug concentrations exceed the MIC during steady-state dosing. Cefepime demonstrated comparable or superior indices to cefazolin against Gram-positive microorganisms and to cefuroxime and ceftazidime against Gram-negatives. Serum bacteriostatic and bactericidal activity from the kinetic samples corresponded with the duration that serum cefepime concentrations exceeded the MIC and MBC, respectively, for selected strains. This pharmacodynamic evaluation suggests that cefepime 1 g every 12 h potentially provides inhibitory serum concentrations for the majority of common Enterobacteriaceae, streptococci and S. aureus over the dosing interval but that higher doses or more frequent administration may be necessary for some pseudomonal infections.

Bacteria↗