PubMed Health⌕ Search

Biomedical subjects

F A Zantvoort

Publications and source records attributed to F A Zantvoort.

17 recordsLinked to original sources
PubMed1996

The impact of HLA-A matching on long-term survival of renal allografts.

An important contribution of HLA-A antigen matching in renal transplantation was reported initially, hut later publications showed a minor or absent role. We analyzed the contribution of HLA-A locus matching to graft survival in 17,672 first renal transplants from unrelated, nonliving donors. We show that an independent HLA-A matching effect still exists. Due to its relative weakness and late appearance, large numbers and longer follow-up periods are required. The HLA-A matching effect is a significant factor in first renal allograft survival up to 6 years after transplantation, with an increasing effect over time. This is in contrast to the strong, short-lived, effects of HLA-DR and -B matching, which can only be detected up to 6 months and 2 years after transplantation, respectively. A clear additive beneficial effect of HLA-A matching is shown in the group without B and DR mismatches. Therefore, prospective matching for the HLA-A antigens remains important for renal allograft survival.

Graft Survival↗
PubMed1994

[The HLA system. An introduction].

The cellular identity is determined by the cell surface antigens. The recognition of self and non-self in vertebrates is mainly controlled by antigens and coded for by the major histocompatibility complex (MHC). Upon recognition of a foreign antigen, the immune system does not only initiate a reaction with the help of cytotoxic T-cells, phagocytes and humoral antibodies; memory cells are also generated, enabling a very swift and powerful response after repeated exposure to the same foreign antigens. These characteristics, although essential for the survival of the organism in a hostile environment, can markedly limit the life of useful and potentially lifesaving organ transplants.

Graft Rejection↗
PubMed1994

[Automatic ultrasound-guided fine needle biopsy of the transplanted kidney. Risks and uses].

Renal allograft biopsy is very valuable in the assessment of graft dysfunction, but complications are frequent and graft loss has even been described. Between 1991 and 1993, a total of 133 graft biopsies were done. We used an automated biopsy gun with a fine-caliber core needle (diameter 1.2 mm) under ultrasound guidance. Histological diagnosis was possible in 95.5% of the biopsies. On average 5.5 glomerula per specimen were obtained. This method proved to be safe, surgical intervention becoming necessary in 2 cases (1.5%).

Adolescent↗
PubMed1992

Factors affecting the long-term outcome following non-living kidney transplantation.

The aims of the study were threefold: (1) to analyse the long-term overall kidney graft survival within Eurotransplant for the period 1971-1987; (2) to examine the effect of matching for HLA over the years, with the aid of half-lives after the first post-transplant year; and (3) to take prognostic factors into account for the period 1981-1987, comparing their influence on the long-term outcome of the graft and to predict half-lives for various combinations of factors.

Adolescent↗
PubMed1992

Factors contributing to long-term kidney graft survival in Eurotransplant.

We examined the graft survival of 12,883 first unrelated kidney grafts from nonliving donors, transplanted between 1 January 1971 and 31 December 1987 within 52 renal transplantation centers participating in the Eurotransplant organization. The 5-year graft survival increased from 38.8% for the period 1971-1975 to 66.0% for the period 1981-1987 for patients treated with cyclosporine, whereas the half-life increased by only 2 years, from 9.7 years to 11.6 years over the same period, based on grafts functioning at 1 year posttransplantation. Results per HLA locus showed considerable improvements within mismatch groups over the entire period. Large differences between mismatch groups for the early years were observed, but within the cyclosporine era only HLA-B showed a statistically significant difference in half-lives (13.2 versus 9.0 years, for 0 and 2 mismatches respectively, P = 0.013). When other prognostic factors were taken into account, it was revealed by means of an exponential model that number of HLA-B mismatches, donor and recipient age and sex, and recipient diagnosis of diabetes had significant effects on the long-term outcome of the grafts. Depending on the combination of these parameters, estimates of half-life varied from 4.9 to 14.5 years. These results show that matching for HLA-B is still of benefit in the longer term and that other prognostic factors play an important role in predicting the late outcome of renal allografts.

Adolescent↗
PubMed1991

Prognostic indices to predict survival of first and second renal allografts.

In order to predict kidney graft survival, the influence of independent prognostic factors can be examined multivariately and the factors combined into a prognostic index. Data on 7121 patients receiving an unrelated first and 1033 patients receiving an unrelated second transplant from nonliving donors, between 1 January 1984 and 31 December 1987, were analyzed to ascertain the most important prognostic variables up to 4.5 years posttransplantation. Factors found to be significant for graft survival were donor and recipient age and sex, recipient blood group, whether the recipient was diabetic, cold ischemic period, number of HLA-B and - DR mismatches, highest percent panel-reactive antibody, transplant center, and--for second transplants--duration of first graft. A risk score for graft failure, based on the prognostic factors, was developed using these factors and five risk groups (from excellent to very poor prognosis) were identified. This index was tested on an independent data set and showed a good fit when compared with the observed Kaplan-Meier graft survival: patients allocated by the risk score into the "excellent prognosis" group had an observed one-year graft survival of 90.4%, compared with a predicted value of 90.3% for first transplants. Corresponding results for second transplants were 86.2% (observed) and 86.0% (predicted). For the "very poor" prognosis group, the results were 73.4% (observed) and 74.4% (predicted), for first transplants, and 60.9% (observed) and 60.1% (predicted), for second transplants. A prognostic index can therefore identify patients likely to have a high or low graft survival, leading to improved decision-making and aiding the choice of patient management once a recipient has been transplanted.

ABO Blood-Group System↗
PubMed1990

The effect of HLA matching on kidney graft survival in separate posttransplantation intervals.

The effect of matching for the HLA antigens has been well established as important in the prognosis of kidney grafts. By analyzing the effect of matching on first transplants from unrelated donors in specific intervals up to 3 years posttransplantation, we show that the effect of HLA-DR matching is strongest in the first 5 months following transplantation (relative risks of graft failure 1.31 and 1.77 for 1 and 2 HLA-DR mismatches, respectively, compared with no mismatches). For patients whose grafts remained functioning after 5 months, there was no significant further improvement in graft survival to 3 years (relative risks 1.16 and 0.98 for 1 and 2 HLA-DR mismatches, respectively, compared with no mismatches)--i.e., the gain in graft survival by matching for HLA-DR appears to be due to its influence in the first 5 months following transplantation. For HLA-B, the matching effect was evident both before and after 5 months (relative risks 1.11 and 1.27 for 1 and 2 HLA-B mismatches, respectively, compared with no mismatches and modelled as constant over the 3-year period), whereas no effect of HLA-A matching was evident in the period up to 3 years.

Graft Survival↗
PubMed1987

Evaluation of a microcomputer program (OPT) for parameter optimisation in clinical pharmacokinetics: gentamicin and tobramycin.

1. Several nomograms and computer programs are available to aid in aminoglycoside dosing. 2. Due to the variability in the relationship between dosage and serum drug levels, monitoring through the acquisition of serum drug levels is mandatory. 3. All clinical data, including serum drug levels, are subject to errors. 4. The program we have evaluated, OPT, calculates the most likely set of pharmacokinetic parameter estimates for individual patients by applying Bayes' theorem and the principle of Maximum Likelihood Estimation. Through a feedback process all available data are used, taking possible errors into account. 5. Our study shows that OPT is able to predict serum aminoglycoside levels accurately in the routine clinical setting. It may thus contribute to the quality of aminoglycoside therapy.

Adolescent↗
PubMed1986

Chronic effect of ketanserin in mild to moderate essential hypertension.

Ketanserin, an antagonist highly selective for 5-hydroxytryptamine (serotonin) type 2 (S2) receptors, was given as monotherapy in a dose of 40 mg b.i.d. to 24 subjects with mild to moderate essential hypertension. Its effects were evaluated in a placebo-controlled double-blind crossover study. The effect on blood pressure in 18 subjects was monitored by 24-hour ambulatory intra-arterial measurements. Systolic and diastolic intra-arterial pressures were significantly lowered by ketanserin both during the day and at night, whereas heart rate was unchanged. Cuff pressure readings (triplicate measurements) with the London School of Hygiene sphygmomanometer and an automatic device (12 measurements in 1 hour) in the outpatient clinic also showed a significant effect on both supine and standing pressures. No postural hypotension was noted. Ketanserin had no effect on endogenous creatinine clearance, serum cholesterol levels, and the plasma levels of norepinephrine, renin, and aldosterone. The only side effect that was significantly more common with ketanserin than with placebo treatment was an increase in body weight. Ketanserin may have a place in the treatment of mild to moderate essential hypertension.

Adult↗