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H Dieperink

Publications and source records attributed to H Dieperink.

At least 37 records · Page 2Linked to original sources
PubMed1987

Nephrotoxicity of cyclosporin A in humans: effects on glomerular filtration and tubular reabsorption rates.

The contention that cyclosporin A (CyA) nephrotoxicity may be due to renal afferent arteriolar constriction was inferred from rat studies showing CyA to increase renal vascular resistance, to reduce glomerular filtration rate (GFR) and delivery of tubular fluid from the end of the proximal tubule to the loop of Henle (Vprox), and to increase proximal fractional reabsorption. In order to test whether the mechanism of human CyA nephrotoxicity is similar to its rat analogue, and whether CyA treatment causes prolonged renal malfunction after drug withdrawal, renal function was investigated with clearance techniques including lithium clearance (CLi) as a measure of Vprox. The subjects were patients (n = 11) with previously normal renal function, given CyA in the treatment of ocular manifestation of extrarenal disease, or bone-marrow transplant recipients. Nine out of these eleven patients were investigated before and during CyA treatment: GFR (P less than 0.05) and Vprox (P less than 0.005) decreased while proximal fractional reabsorption increased (P less than 0.01). In six patients investigated before CyA was given, and re-examined a mean of 273 days (range 84-384 days) after CyA withdrawal, CLi was reduced (P less than 0.05) while mean GFR was not significantly lowered (0.5 greater than P greater than 0.2). In one of these six patients GFR was reduced to a subnormal value of 26 ml min-1 (1.73 m2 body surface)-1. In conclusion, human and rat CyA nephrotoxicity have the same pattern of renal functional deterioration. Cyclosporin A nephrotoxicity was evident in patients investigated a mean of 9 months after CyA withdrawal.

Absorption↗
PubMed1987

Cataractogenic effect of cyclosporin A: a new adverse effect observed in the rat.

In a study designed to test the long-term nephrotoxic effects of cyclosporin A (CyA), 11 of 13 rats given CyA, 25 mg/kg per day for 8 months, developed cataract. None of the 15 rats given CyA 12.5 mg/kg per day, nor of the controls given vehicle only (n = 10), developed this lesion. In a subsequent study, 15 rats were given CyA 25 mg/kg per day, 15 were given 12.5 mg/kg per day, and 10 controls were given the vehicle only. After 16 weeks, three rats of the group on CyA 25 mg/kg per day had developed cataract. The SPF Sprague-Dawley rats were maintained on a controlled breeding diet (Ewos R3). Perforating eye lesions or infections were not observed, but one rat without opacity of the lens had antibodies against sialodacryoadenitis virus. Thus, in the rat, high-dose CyA has significant cataractogenic effects when administered for 15%-25% of the rat life-span.

Animals↗
PubMed1986

Excessive hypercalcaemia and mixed connective tissue disease.

A 23-year-old female with extreme hypercalcaemia was treated with calcitonin, mitramycin and parathyroidectomy and normocalcaemia was achieved after 4 weeks. Nevertheless, the patient later died of cutaneous necrosis, impaired circulation and multiple organ failure. Serum immunoreactive parathyroid hormone was in the normal range and parathyroid tissue normal. Mixed connective tissue disease was diagnosed on the basis of high titers of antibody to extractable nuclear antigen, moderately elevated levels of antibody to nuclear antigen and only marginal elevation of anti-double standed DNA. The role of Cl. difficile toxin in the blood and an acinic cell tumour is unclear.

Adult↗
PubMed1986

Nephrotoxicity of cyclosporin A. A lithium clearance and micropuncture study in rats.

Renal function was studied in rats treated with cyclosporin A (CyA). Peroral CyA 25 mg kg-1 day-1 depressed glomerular filtration rate (GFR) from 1284 +/- 429 to 500 +/- 228 microliters min-1 g-1 kidney weight (KW) (P less than 0.01). Absolute rate of proximal tubular reabsorption (APR) decreased from 1075 +/- 437 to 468 +/- 203 microliters min g KW-1 (P less than 0.01). Proximal tubular fractional reabsorption (PFR) was 67.7 and 68.5% measured with the TT/OT and fractional lithium-clearance methods, respectively. Amiloride had no effect on lithium-clearance in CyA treated rats. Acute isotonic volume expansion increased GFR and APR towards normal, while PFR remained increased. Increased sodium clearance did not normalize renal function. CyA intravenously (12.5 mg kg-1) depressed GFR and APR acutely, while PFR increased. Proximal intratubular pressures were low normal (mean 11.6 mmHg). Proximal transit times were prolonged (mean 25.2 s, P less than 0.01). Renal morphology was normal. The data are evidence against a primary tubular damage of CyA, and makes it less likely that the major lesion is located to the glomerular membrane. The results suggest that CyA nephrotoxicity mainly is due to a haemodynamic effect.

Amiloride↗
PubMed1986

Antagonist capacities of nifedipine, captopril, phenoxybenzamine, prostacyclin and indomethacin on cyclosporin A induced impairment of rat renal function.

Experimental evidence indicates that cyclosporin A (CyA) nephrotoxicity is due to renal arteriolar constriction, reducing renal blood flow, glomerular filtration rate (GFR), and delivery of tubular fluid from the end of the proximal tubule to the loop of Henle. The proximal tubular fractional reabsorption (PFR) is increased. Therefore, the impact on renal function of vasodilating agents was studied in rats given CyA. Conscious catheterized rats and clearance techniques were used. In acute experiments a preexisting CyA-nephrotoxicity was resistant to infusion of phenoxybenzamine, prostacyclin, captopril, nifedipine and indomethacin. Concomitant treatment with captopril and CyA did not improve renal function, while concomitant treatment with CyA and nifedipine improved GFR to 1.13 +/- 0.34 ml min-1 g-1 kidney weight (gKW) (n = 19, P less than 0.05), as compared to CyA and placebo treated controls (n = 12, 0.83 +/- 0.32 ml min-1 g-1 KW). Nifedipine also reduced FPR (88.6 +/- 5.1% vs. 83.2 +/- 5.6%. P less than 0.01), and increased lithium clearance from 99 +/- 54 to 184 +/- 64 microliters min-1 g-1 KW (P less than 0.001). The results are further evidence that CyA nephrotoxicity includes renal vasoconstriction, and indicates that calcium entry blockade is nephroprotective in the case of CyA toxicity.

Animals↗
PubMed1986

Cyclosporine A: effectiveness and toxicity in a rat model.

In an effort ot elucidate the effectiveness of Cyclosporine A (CyA) relative to the toxicity, Lewis to Sprague-Dawley first and second set skin transplantation and evaluation of the renal function with clearance methods was performed. CyA 12.5 mg/kg/day delayed first set rejection from 12.3 to 15.4 days (p less than 0.001), and second set from 10.5 to 12.1 days (p less than 0.05); 25 mg/kg/day prolonged the survival times to 18.3 (p less than 0.01) and 19.5 (p less than 0.002) days, respectively. The majority of the skin grafts were still not rejected at the end of the 3 weeks CyA 25 mg/kg/day treatment in contrast to the results during 12.5 mg/kg; the second set skin graft survival was significantly better (p less than 0.01) during the higher dosage. It is concluded, that CyA is not fully immunosuppressive at the 12.5 mg/kg/day dosage. In the doses 12.5 and 25 mg/kg GFR (inulin clearance [Cin]) was reduced to 80 and 48%, respectively, of the control value; the lithium clearance (CLi) was reduced to 69 and 27%. Proximal fractional reabsorption, as calculated from 1-CLi/Cin, was increased from a control value of 82% to 86 and 92% (p less than 0.02) in the 12.5 and 25 mg/kg/day group, respectively, suggesting that CyA nephrotoxicity is due to a decrease in the glomerular ultrafiltration pressure rather than being secondary to proximal tubular damage. In conclusion, in this model there does not seem to exist a therapeutic window between nephrotoxicity and the immunological effectiveness of CyA.

Animals↗
PubMed1986

Ketoconazole and cyclosporine A: combined effects on rat renal function and on serum and tissue cyclosporine A concentration.

The effects of ketoconazole (Kcnz) on cyclosporine A (CyA) serum levels and CyA-nephrotoxicity were studied. To rats later anesthetized with pentobarbital sodium, CyA 12.5 and Kcnz 20 mg/kg/day (n = 20), or CyA 12.5 mg/kg and Kcnz-vehicle (n = 21), was dosed. To rats anesthetized with etomidate (n = 14), CyA 12.5 mg/kg and Kcnz-carrier was dosed. S-CyA was monitored during 14 days, and then the rats were investigated with clearance (C) methods (inulin [(in), lithium (Li)], sodium, and potassium), and liver (L) and kidney (K) CyA was measured. Kcnz increased S-CyA, L-CyA and K-CyA (+50 -80%). There were significant (p less than 0.05) correlations between S- and L- or K-CyA. Kcnz increased CyA nephrotoxicity: Mean Cin was 1.012 ml/min/gKW (kidney weight) after CyA treatment (a subnormal value), but decreased to 0.556 ml/min/gKW in the group also given Kcnz (p less than 0.001). CLi decreased from 0.135 to 0.048 ml/min/gKW (p less than 0.001), and absolute proximal tubular reabsorption decreased from 0.877 to 0.508 ml/min/gKW (p less than 0.001), while the fractional reabsorption in the proximal tubule (FPR), expressed as a percentage of GFR, increased from 86.9 to 91.6% (p less than 0.005). Thus, after Kcnz treatment to rats given CyA 12.5 mg/kg/day, their renal function was indistinguishable from that in rats given CyA 25 mg/kg/day.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia↗