Ex vivo stimulation of renal tubular p-aminohippurate transport by dexamethasone and triiodothyronine in human renal cell carcinoma

This paper is the third of a long-term planned series of papers dealing with ex vivo investigations of drug transport in human kidney. The aims of this study are (a) to investigate whether or not human renal cell carcinoma (RCC) can actively accumulate p-aminohippurate (PAH) and (b) to test the response of RCC on dexamethasone or triiodothyronine (T3) using tissue slices ex vivo. By this approach, the accumulation capacity of RCC should be stimulated as a prerequisite for an increased uptake of anti-tumour drugs. Tissue slices of RCC samples of 30 patients were incubated for 24 h in Williams medium E containing 0.01–50 μM dexamethasone or T3. Thereafter, slices were placed in PAH-containing Cross–Taggart medium, and PAH uptake into kidney tissue was measured for 2h under standardised conditions as described previously. In intact human renal cortical slices, PAH uptake capacity, expressed as slice to medium ratio (Q _S/M), was about 2.8 ± 0.16 after 24 h of incubation and increased significantly in dexamethasone-containing medium in a concentration-dependent manner, up to ∼150%, whereas T3 did not influence PAH accumulation. On the other hand, in RCC the PAH accumulation capacity was completely abolished (Q _S/M∼1). However, after administration of dexamethasone, the accumulated amount of PAH increased significantly in RCC tissue in a concentration-dependent manner, up to ∼190%. T3 was without effect in RCC, too. Surprisingly, the dexamethasone-mediated stimulation could be differentiated into responders and non-responders, with maximal effects at different concentrations for each patient. Nevertheless, the maximal transport rates remained low in RCC, even under hormone influence. In conclusion, a moderate stimulation of tubular transport capacity can be shown ex vivo in human RCC. This phenomenon is only of a relatively low degree compared with intact renal tissue. However, in principle, the response of RCC on dexamethasone could form a basis for further therapeutic strategies to overcome multi-drug resistance in RCC patients. For this purpose, additional experiments analysing the expression of transporters of the ABC cassette-type are in progress. Received: 25 April 2000 / Accepted: 27 July 2000     

Ex vivo stimulation of renal transport of the cytostatic drugs methotrexate,cisplatin, topotecan (Hycamtin) and raltitrexed (Tomudex) by dexamethasone,T3 and EGF in intact human and rat kidney tissue and in human renal cell carcinoma

Previous experiments have shown that both in vivo and in vitro pre-treatment with various hormones increases the renal transport capacity for weak organic acids, such as PAH, in rats. The aim of the present study was to test whether or not accumulation of the anticancer drugs methotrexate (MTX), cisplatin (CP), raltitrexed (Tomudex) and topotecan (Hycamtin) can be increased in intact, healthy rat and human renal cortical slices and in human renal cell carcinoma (RCC). Intact, healthy human tissue was obtained from tumour bearing kidneys of patients suffering from RCC. Experiments were intended as a new approach to overcome so-called multidrug resistance. Kidney tissue slices were incubated for 24 h in William's medium E containing various concentrations of dexamethasone, T(3), or EGF. Thereafter slices were placed in anticancer drug containing Cross-Taggart medium and the drug uptake into kidney tissue was measured for 2 h. In intact rat and human renal tissue slices, the uptake of p-aminohippurate (PAH = reference substance) increased significantly after incubation in dexamethasone containing medium (134% and 156%, respectively). There were no stimulating effects of either T(3) or EGF on PAH accumulation. On the other hand, only the accumulation of MTX, but not of CP, raltitrexed or topotecan, was significantly enhanced after hormone pre-treatment both in intact renal tissue and in RCC. A stimulation of renal PAH accumulation can be performed ex vivo, as reported previously, both in intact rat and human renal cortical slices and in RCC. Discrepancies between the effects of dexamethasone and T(3) or EGF indicate different modes of action of these substances at the cellular level. Unfortunately, with the exception of MTX, the uptake of anticancer drugs can not be stimulated effectively ex vivo in human RCC tissue by the substances used. Evidently the transport of these anticancer drugs out of the kidney cells is more effective than their uptake.     

Tubular PAH transport capacity in human kidney tissue and in renal cell carcinoma: correlation with various clinical and morphological parameters of the tumor

In vitro accumulation ofp-aminohippurate (PAH) was investigated in intact human renal cortical slices of normal kidney tissue and in tissue slices of renal cell carcinoma (RCC). The technique used was established in preliminary experiments on rat kidney tissue slices. In principle, the accumulation capacity is comparable in renal tissue slices of both species (slice to medium accumulation ratios between 4 and 8). In man sex differences in accumulation capacity do not exist. But, as shown in detail for rats, accumulation capacity drops with age. Tissue slices of RCC are unable to accumulate PAH actively; slice to medium ratio reaches about 1 and indicates passive PAH uptake only. Surprisingly, in tumors of stage pTl PAH uptake is lowest, perhaps as a sign of PAH transport out of the cells. There is no difference between peripheral and central parts of RCC. Age and sex are without influence on PAH uptake in RCC tissue slices. Interestingly, the accumulation capacity of intact tissue of kidneys infested with RCC also depends on the severity of the tumor (stage, diameter), but not on grading and formation of metastases.     

Hormonal control of postnatal development of renal tubular transport of weak organic acids

We have postulated that the maturation of the renal transport mechanism for weak organic acids is controlled by thyroid and adrenal hormones. Administration of T₃ and T₄ (20 g/100 g body wt. for 3 days) to immature rats enhanced by 50% the accumulation of p-aminohippurate (PAH) in renal cortical slices of 5- to 30-day-old rats. The effect of T₃ was lower, while T₄ had no effect, in 50- and 105-day-old animals. Enhancement of PAH transport became apparent 24 h and disappeared by 9 days after the end of hormone treatment. Administration of a booster dose of T₃ (1 g/100 g body wt.) on day 9 brought the level of PAH accumulation to values similar to those observed 24 h after the end of the initial 3 days of T₃ administration. Dexamethasone administration (80 mg/100 g body wt. for 3 days) affected PAH uptake only in cortical slices obtained from 5-day-old rats. Changes in PAH accumulation did not correlate with changes in kidney weight or protein synthesis, indicating that they were mediated by the hormones rather than being consquent to growth.     

Experimental study of renal disorder caused by oxaliplatin in rat renal cortical slices

Background Oxaliplatin is a newly developed antitumor platinum complex that is known to have low nephrotoxicity. The inhibitory effects of oxaliplatin on several tubular functions were compared with those of cisplatin and carboplatin, using a renal cortical slice system.Methods and results Rat renal cortical slices were incubated with 0.25mM to 2.0mM of oxaliplatin, cisplatin, on carboplatin at 37°C for 120min. Para-amino hippuric acid (PAH) accumulation, gluconeogenesis, and ATP content in the rat renal slices were determined. PAH accumulation was not inhibited by carboplatin, but it was signific-antly inhibited by oxaliplatin and cisplatin. Inhibition of PAH accumulation by cisplatin was greater than that by oxaliplatin. Gluconeogenesis was not decreased by carboplatin, but it was suppressed by oxaliplatin and cisplatin in a dose-dependent manner. The decrease in gluconeogenesis induced by oxaliplatin was significantly greater than that induced by cisplatin. ATP content in the renal slices was decreased by oxaliplatin, cisplatin, and carboplatin to almost the same extent. As an in vivo experiment, 21.6mmole/kg of oxaliplatin, cisplatin, or carboplatin was injected into rats; then blood urea nitrogen (BUN) and serum creatinine were determined on day 4. Significantly elevated levels of BUN and serum creatinine were observed only in the rats injected with cisplatin.Conclusions Oxaliplatin did not cause nephrotoxicity in the in vivo study; however, the nephrotoxic pattern of oxaliplatin observed in the renal cortical-slice system resembled that of cisplatin. The reason why oxaliplatin is less nephrotoxic than cisplatin in vivo could not be fully elucidated in the present experiment using the renal cortical-slice system.     

Influence of vinblastine on DNA parameters and multidrug resistance in renal cell carcinoma in vitro

The purpose of this study was to investigate how the vinca alkaloid vinblastine influences DNA parameters and the mechanisms of multidrug resistance in renal cell carcinoma. After exposing cell cultures of human renal carcinoma to progressively increasing concentrations of vinblastine the cell lines were examined by flow cytometric DNA analysis to assess the S-phase and G₂/M-phase fraction and by a modified MTT assay. It was shown that the exposed cells became P-glycoprotein-positive by staining the cells with a monoclonal antibody (JSB-1). The flow cytometric analysis revealed, with prolonged vinblastine exposure, correlated increases in the S-phase and G₂/M-phase fractions (P = 0.0001). When vinblastine-free medium was used for culturing, the changed DNA characteristics returned to their original values. Comparing the DNA parameters with the IC₅₀ (concentration when cell growth is inhibited by 50%) we found a strong correlation between these parameters (P = 0.0001). In conclusion, DNA analysis of long-term vinblastine exposure may provide insight into events leading to multidrug resistance. Furthermore, analysis of the DNA profile might also be an important investigation before planning therapy with vinblastine for renal cell carcinoma. Received: 24 January 1997 / Accepted: 18 September 1997     

Effect of cyclosporine A on accumulation of tetraethylammonium and p-aminohippurate, and on lipid peroxidation in rat renal microsomes and cortical slices

The effect of cyclosporine A (CsA) on lipid peroxidation (LPO) was assessed in renal cortical slices and renal microsomes. Cortical slices were incubated with 1500 micrograms/ml CsA and microsomes with 0.5-20 micrograms/ml under identical conditions (pH 7.4, 37 degrees C) for 3 hours, and LPO monitored by the formation of malondialdehyde (MDA). CsA at concentrations of 3 micrograms/ml and higher caused a significant increase MDA in microsomes and renal cortical slices showed a time dependent release of MDA into the incubation medium. The influence of CsA on tetraethammonium (TEA) and p-aminohippurate (PAH) accumulation in renal cortical slices was investigated for up to 3 hours with concentration of CsA from 10 to 1000 micrograms/ml. CsA caused a time- and concentration-dependent decrease of TEA accumulation and higher concentrations of CsA decreased PAH accumulation in renal cortical slices. The results add further evidence to the suggestion that lipid peroxidation participate in CsA-induced impairment of kidney function.     

Nephrotoxic effects of ionic and nonionic contrast media on rat and human renal cortical slices

Background. Nephrotoxicity is a well-known adverse effect of radiographic contrast medium (CM). Recently, several kinds of low- osmolality nonionic CM have been developed. However, the nephrotoxic effects of nonionic CM compared with those of ionic CM have not been well evaluated. Methods. To compare the direct nephrotoxic effects of ionic and nonionic CM on renal epithelial cells, rat and human renal cortical slices were incubated with CM at 37°C for 120 min. Diatrizoate and iothalamate were employed as ionic CM. Iopamidol, iohexol, iomeprol, ioversol, iopromide, and ioxilan were employed as nonionic CM. Direct toxicity of CM was evaluated by the activities of N-acetyl-β-D-glucosaminidase (NAG) and γ-glutamyl-transferase (GGT) released from the renal slices into the incubation buffer. Results. In the experiment with rat renal slices, NAG and GGT activities in buffer solutions were increased dose-dependently by 30, 60, and 90 mg I/ml of CM. There was no significant difference in NAG or GGT release between ionic and nonionic CM at the concentration of 60 mg I/ml. In the experiment with human renal slices, incubation with 60 mg I/ml of diatrizoate, iothalamate, iomeprol, and iopromide did not affect NAG levels. Significantly greater increases in NAG levels, compared with the control, were observed after incubation with iopamidol, iohexol, ioxilan and ioversol. Nevertheless, the increases in NAG caused by some of the nonionic CM were very slight. GGT release from human renal slices was significantly greater than that of the control in all experimental groups. Again, there was no significant difference in renal toxicity between ionic and nonionic CM. Conclusions. Newly developed nonionic CM had almost the same degree of nephrotoxicity against rat and human renal epithelial cells as conventional ionic CM, when direct renal toxicity was evaluated by enzyme release in an in-vitro experimental system using renal cortical slices. Received: November 22, 2000 / Accepted: March 6, 2001     

CYP1A1 activity in renal cell carcinoma and in adjacent normal renal tissue

Cytochrome P450-isoenzyme, CYP1A1, is responsible for the metabolic activation of several precarcinogenic environmental chemicals to their carcinogenic intermediates. Microsomal CYP1A1 activity in renal cell carcinoma (RCC) and in normal renal tissue was determined by measuring spectrofluorometrically the hydroxylation rate of benzo[a]pyrene. The study included 50 patients who underwent nephrectomy for RCC. Tissue specimens were taken from renal tumours and, as a control, from macroscopic normal renal tissue adjacent to the tumours. Normal renal tissues that were adjacent to poorly differentiated grade 3 tumours and/or to metastatic RCC contained significantly higher CYP1A1 activities than renal tissues next to well-differentiated (P = 0.02) and/or organ-confined tumours (P = 0.001). In conclusion, those patients who had tumours that could be considered aggressive on the grounds of poor cell differentiation or a metastatic feature of tumour, had remarkably higher CYP1A1 activities in their kidneys than the patients with less aggressive renal tumours. Received: 25 March 1997 / Accepted: 19 September 1997     

Effect of Cyclosporine a on Accumulation of Tetraethylammonium and p-Aminohippurate,and on Lipid Peroxidation in Rat Renal Microsomes and Cortical Slices

The effect of cyclosporine A (CsA) on lipid peroxidation (LPO) was assessed in renal cortical slices and renal microsomes. Cortical slices were incubated with 1500 μg/ml CsA and microsomes with 0.5–20 μg/ml under identical conditions (pH 7.4,37d`C) for 3 hours, and LPO monitored by the formation of malondialdehyde (MDA). CsA at concentrations of 3 μg/ml and higher caused a significant increase MDA in microsomes and renal cortical slices showed a time dependent release of MDA into the incubation medium. The influence of CsA on tetraethammonium (TEA) and p-ami-nohippurate (PAH) accumulation in renal cortical slices was investigated for up to 3 hours with concentration of CsA from 10 to 1000 μg/ml. CsA caused a time-and concentration-dependent decrease of TEA accumulation and higher concentrations of CsA decreased PAH accumulation in renal cortical slices. The results add further evidence to the suggestion that lipid peroxidation participate in CsA-induced impairment of kidney function.     

Inhibition of gluconeogenesis and <Emphasis Type="Italic">p</Emphasis>-aminohipuric acid accumulation in rat renal cortical slices by ionic and nonionic contrast media

Background. Renal dysfunction is a well-recognized complication induced by contrast media (CM). Nonionic CM have been introduced into clinical use to replace conventional ionic CM in an effort to reduce toxicity. However, the nephrotoxic effects of nonionic CM have not been fully evaluated. We previously determined the activities of N-acetyl--d-glucosaminidase and -glutamyltransferase released from rat and human renal slices incubated with contrast media. Dose-dependent enzyme release from renal slices was observed, but there was no statistical difference in the increase of enzyme activities between ionic and nonionic CM. The present experiment was conducted to compare the effects of ionic and nonionic CM on the metabolic function of rat renal slices.Methods. Rat renal cortical slices were incubated with ionic CM (diatrizoate, iothalamate) and nonionic CM (iopamidol, iohexol) at 37°C for 90min. To examine the dose–response effects of CM on gluconeogenesis and p-aminohipuric acid (PAH) accumulation in the rat renal slices, slices were incubated with 30, 60, and 90mgI/ml of CM. The inhibitory effects of nonionic CM on gluconeogenesis and PAH accumulation were compared with those of ionic CM in an independent experiment, in which slices were incubated with CM at a concentration of 60mgI/ml. In addition, rat renal slices were incubated with mannitol instead of CM to investigate the effects of osmotic pressure on gluconeogenesis and PAH accumulation.Results. A dose-dependent reduction of gluconeogenesis in rat renal slices was demonstrated by both ionic CM and nonionic CM. The inhibition of PAH accumulation was dose-dependent with nonionic CM, but not with ionic CM. Gluconeogenesis and PAH accumulation within the renal slices were both inhibited according to the increase in osmotic pressure produced by mannitol. The reduction in gluconeogenesis and PAH accumulation within the rat renal slices incubated with 60mgI/ml of nonionic CM were significantly less than those resulting from the same concentration of ionic CM.Conclusions. Nonionic CM is less nephrotoxic than ionic CM with regard to gluconeogenesis and PAH accumulation in rat renal slices. These differences in nephrotoxic effect between ionic and nonionic CM may in part be attributable to differences in osmotic pressure.     

Acute renal failure after exercise in a patient with renal hypouricemia

A 22-year-old man had recurrent exercise-induced acute renal failure (ARF). He was found to have isolated renal hypouricemia: serum uric acid level was 0.7–1.0 mg/dl and fractional excretion of uric acid (FE_UA) was 37%–43%. He showed no suppression of FE_UA following the the administration of pyrazinamide, and no increase of FE_UA after benzbromarone, suggesting a subtotal defect. We investigated renal function, FE_UA, and serum nitric oxide after a treadmill exercise test in our patient and two control subjects. On the day after the exercise test, plain and enhanced abdominal computed tomography (CT) scans were performed in our patient. During the arterial phase, early equilibration phase, equilibration phase, and 2, 6, and 24 h after the injection of contrast medium, renal CT scans were performed at the same slice level. Although ARF was not induced by this level of exercise, the CT scans showed patchy contrast enhancement 2, 6, and 24 h after contrast medium administration. This finding suggests that patchy renal vasoconstriction may occur in patients with renal hypouricemia after strenuous exercise, even in the setting of normal creatinine clearance. Received: June 19, 1998 / Accepted: September 4, 1998     

Effect of tangerine juice on cyclosporine levels in renal transplant children

The aim of our study was to investigate the effect of tangerine juice on the pharmacokinetics of cyclosporine A (CsA), in children who had received a renal transplant. This placebo-controlled study was done on ten kidney transplant recipients with stable cyclosporine trough levels who received either tangerine (Unshio Satsuma) juice or water. Patients were given their morning doses of CsA and then 250 ml water or the juice, and 12 h, investigations of the pharmacokinetics (PK) were performed. The main outcome measures were peak concentration and time to peak and area under the concentration–time curve. Administration of CsA with tangerine juice compared with water did not increase significantly the area under the whole-blood concentration versus time curve from 0–12 h (AUC_0–12) of CsA, (tangerine juice 2,797 ± 1,361 (P = 0.5); water 3,053 ± 1,532). Co-administration of tangerine juice with CsA compared with water had no significant effects on the AUC_0–12, peak concentration (C_max) or time to C_max (t_max) of the CsA in pediatric renal transplantation.     

A preventive effect of a selective endothelin-A receptor antagonist, S-0139, on the erythropoietin-induced reduction of the renal cortical blood flow

We have confirmed that renal cortical blood flow (RCBF) is significantly decreased by recombinant human erythropoietin (EPO). Endothelin-1 (ET₁) is thought to be a mediator because its level increased significantly when EPO was administered. The present study was performed to clarify the effect of a selective ET-A receptor antagonist, S-0139, on EPO-induced RCBF reduction. Ten-week-old male Wistar rats, weighing about 250 g, were divided into five groups. Group 1 (n= 5), a control group, received normal saline solution (NSS). Group 2 (n= 5) received 200 U/kg body weight (BW) per hour of EPO. Group 3 (n= 5) received 400 U/kg BW per hour of EPO. Group 4 (n= 5) received both 200 U/kg BW per hour of EPO and 4 mg/kg BW per hour of S-0139. Group 5 (n= 5) received both 200 U/kg BW per hour of EPO and 40 mg/kg BW per hour of S-0139. Drugs were administered intravenously via the right femoral vein using a microinfusion pump for 4 h under urethane anesthesia. The RCBF was measured every 30 min by the hydrogen gas clearance method. When the 4 h had elapsed, the concentrations of plasma creatinine (Cr), ET1 and renin activity (RA) were measured. Compared with group 1, groups 2 and 3 showed significant (P < 0.001) decreases of RCBF, while the ET1 levels of these two groups increased significantly (P < 0.03). The ET1 of groups 4 and 5 also increased significantly (P < 0.03), however, the RCBF of these two groups did not decrease. No significant differences were observed in either Cr or RA between the five groups. EPO induces ET₁ secretion. The reduction of RCBF is due to ET₁-derived vasoconstriction. S-0139 has potential for preventing EPO-induced and ET₁-mediated RCBF reduction. Received: 28 January 1998 / Accepted: 9 April 1998     

Inhibitory effect of bikunin on calcium oxalate crystallization in vitro and urinary bikunin decrease in renal stone formers

Two proteins of 17 and 24 kDa, respectively, which were immunologically related to bikunin, were purified from urine of healthy men, using in the last step a trypsin CNBr-sepharose affinity column. These proteins strongly inhibited calcium oxalate (CaOx) crystallization in two in vitro models. In the first model, the presence of 8 μg/ml protein in a medium containing 0.76 mM CaCl₂ (with ⁴⁵Ca) and 0.76 mM ammonium oxalate inhibited the crystallization process by 80%, as estimated by supernatant radioactivity after 60 min of incubation. A similar inhibition was observed in the second turbidimetric model, where the CaOx crystallization kinetics were followed for 10 min at 620 nm in a medium containing 4 mM CaCl₂ and 0.5 mM Na₂Ox. These proteins were used as standard protein for the development of an enzyme-linked immunosorbent assay (ELISA) in urine. Mean (± SEM) urinary bikunin concentration in 18 healthy subjects was 5.01 ± 0.91 μg/ml. This was a concentration range of strong inhibitory activity in vitro. Bikunin values were nearly 50% lower (2.54 ± 0.42 μg/ml, P=0.007) in 31 CaOx renal stone formers (having weddelite crystals in their first morning urine) than in the healthy volunteers. A correlation was found between urinary bikunin and alpha-1 microglobulin concentrations in the control group (y=0.73x + 1.09, r ²=0.8) while no such correlation existed in the lithiasis group. In conclusion, bikunin exerts a strong inhibitory action of CaOx crystallization in vitro. Its involvement in urinary CaOx crystallization of stone formers is highly probable, based on the significant decrease in its urinary concentration in the majority of stone formers studied. Received: 16 December 1997 / Accepted: 23 June 1998     

Ambulatory blood pressure monitoring and renal functions in children with a solitary kidney

The aim of this study is to investigate the blood pressure (BP) profile, microalbuminuria, renal functions, and relations with remaining normal kidney size in children with unilateral functioning solitary kidney (UFSK). Sixty-six children with UFSK were equally divided into three groups: unilateral renal agenesis (URA), unilateral atrophic kidney (UAK), and unilateral nephrectomy (UNP). Twenty-two age-, weight-, and height-matched healthy children were considered as a control group. The serum creatinine level and first-morning urine microalbumin and creatinine concentrations were determined by the standard methods. Also, the BP profile was determined by ambulatory blood pressure monitoring (ABPM). We found that the serum creatinine level was higher and creatinine clearance was lower in each patient groups compared to those of the control group (p < 0.05). Compared with the controls, each group of patients had mean office, 24-h, daytime, and night-time systolic and diastolic BP values similar to those of the controls (p > 0.05). An inverse correlation was found between the renal size standard deviation scores (SDS) of normal kidneys and 24-h systolic and diastolic BP load SDS in all of the patients (p < 0.05; r = −0.372, r = −0.295, respectively). The observed relationship between renal size SDS and 24-h mean arterial pressure (MAP), systolic and diastolic BP load SDS suggests that children with UFSK should be evaluated by using ABPM for the risk of hypertension.     

Risk factors for renal scarring in children and adolescents with lower urinary tract dysfunction

Risk factors for renal scarring in children with lower urinary tract dysfunction (LUTD) were evaluated. The medical records of 120 patients were assessed concerning gender, presence of vesicoureteric reflux (VUR), bladder capacity, detrusor overactivity, residual urine, febrile urinary tract infection (UTI), bacteriuria, constipation, detrusor sphincter incoordination (DSI), high detrusor pressure at maximal cystometric capacity (PMCC), low compliance, and thickness and trabeculation of the bladder wall. Renal scarring was diagnosed by ^99mtechnetium-dimercaptosuccinic acid renal scan (DMSA). Renal scarring was detected in 38 patients (31%). VUR, UTI, decreased bladder capacity, urinary residue, and trabeculated and thick bladder wall were associated with scarring at univariate analysis. Multivariate analysis showed VUR (P < 0.0001) as the independent risk factor for renal scarring. Thickness of the bladder wall was a marginal risk factor (P  = 0.07). Although UTI was not a risk factor, it was associated with VUR (P  = 0.03). In our analysis, VUR was the main risk factor; however, renal scarring was probably due to multifactorial causes, as VUR was associated with UTI.     

Safety and efficacy of a biliary-excreted angiotensin converting enzyme (ACE) inhibitor,temocapril, in combination with amlodipine in advanced diabetic nephropathy

Background. Diabetic patients with moderate to advanced renal failure have severe hypertension and often require multiple antihypertensive agents to control it. Nevertheless, no standardized therapy has been established. This study was designed to examine the safety and efficacy of the biliary-excreted angiotensin converting enzyme inhibitor temocapril in those patients whose blood pressure was not adequately decreased by calcium channel blocker monotherapy. Methods. Twenty-seven patients who did not reach the therapeutic goal of blood pressure (140/90 mm Hg) with amlodipine monotherapy were assigned to receive temocapril (2 mg) and amlodipine (5 mg) for 3 months. Blood samples for hematological and biochemical examinations were taken every month during treatment. Twenty-four-hour urine was collected to measure urinary protein excretion. Trough plasma concentrations and pharmacokinetics were measured during temocapril treatment. Results. Blood pressure was significantly decreased (P < 0.05) from 158 ± 14/91 ± 9 to 148 ± 15/83 ± 8 mm Hg by the addition of temocapril. The peak serum concentration (Cmax) was 86.3 ± 22.7 μg/l at 3.9 ± 1.6 h (Tmax) after administration. Mean area under curve for 0 to 24 h (AUC_0–24 h) was 1179 ± 273 μg/l · h. Trough levels showed a steady state. After temocapril therapy, the slope of the reciprocal of creatinine decreased compared with that before the addition of temocapril. Urinary protein excretion significantly decreased from 3100 ± 1100 to 2300 ± 1100 mg/day. There was no significant change in hematological and biochemical data. Conclusions. The present findings suggest that temocapril can be safely used in patients with advanced diabetic nephropathy, and in combination with dihydropyridine calcium channel blockers it decreases blood pressure and effectively retards the aggravation of renal insufficiency for 3 months in those patients. Received: April 3, 2002 / Accepted: August 29, 2002 Correspondence to:G. Yasuda     

Enteric-coated mycophenolate sodium in de novo pediatric renal transplant patients

Data on the use of enteric-coated mycophenolic acid (EC-MPS) in pediatric transplantation cases are scarce. We undertook a 12-month, multicenter, open-label pilot study in which 16 de novo renal transplant patients aged 5–16 years received EC-MPS with cyclosporine A microemulsion (CsA-ME), steroids, and anti-interleukin-2 receptor antibody induction. The mean dose of EC-MPS was 916 ± 93 mg/m² per day during weeks 1–2, 810 ± 193 mg/m² per day during months 3–6, and 827 ± 153 mg/m² per day during months 6–12. The mean CsA C₂ level exceeded target range up to month 6 post-transplant. Efficacy failure (biopsy-proven acute rejection, graft loss, death or loss to follow-up) occurred in two patients: one patient with primary non-function underwent nephrectomy, and one patient experienced biopsy-proven acute rejection (Grade 1B, day 344) following EC-MPS dose reduction. There were no deaths. Creatinine clearance (Schwartz) was 103 ± 30 mL/min per 1.73 m² at month 6 and 100 ± 16 mL/min per 1.73 m² at month 12. The majority of adverse events were mild or moderate (101/126, 80.2%). In this pilot study, EC-MPS 450 mg/m² administered twice daily with CsA, steroids, and interleukin-2 antibody induction resulted in a low rate of rejection with good renal function in a pediatric population. However, a larger, controlled trial is required to confirm these results.     

A case of recurrent renal failure associated with metabolic alkalosis induced by protracted vomiting

We describe a case of recurrent deterioration of renal function in a 54-year-old man who was found to have metabolic alkalosis, with a maximum PaCO₂ of 73.9 mmHg and a bicarbonate concentration of 55.3 mmol/l. He had a gradual exacerbation of nausea and vomiting due to atrophic gastritis, with a scarred, deformed pyloric part of the stomach and a duodenal bulb secondary to chronic peptic ulcer. His metabolic alkalosis and deteriorated renal function were corrected by intravenous saline with or without potassium chloride. However, his recovered creatinine clearance was at most 60 l/day (41.6 ml/min). A renal biopsy revealed cellular infiltration of mononuclear cells and atrophic change in the tubulointerstitium, suggesting chronic interstitial nephritis. Latent renal insufficiency and dehydration induced by protracted vomiting may easily induce a rapid and recurrent deterioration of renal function, and control of vomiting seemed to be the cardinal measure. Initially, his nausea and vomiting seemed to be successfully controlled by medication, however, they later became persistent and surgical correction of the stomach was carried out. Postoperative recovery was smooth, and the patient's vomiting and recurrent deterioration of renal function finally settled.