Intraoperative Ventricular Opening has No Effect on Complication Development Following BCNU Wafer Implantation for Malignant Glioma.

OBJECTIVE: To evaluate the safety profile of bis-chloroethyl-nitrosourea (BCNU) wafer implantation after malignant glioma resection with or without ventricular opening (VO). METHODS: This single-center retrospective study included 66 consecutive patients with BCNU wafer implantation after malignant glioma resection between March 2013 and August 2021. The patients were categorized into 2 groups based on whether VO occurred during the malignant glioma resection. Fifty-eight patients had glioblastoma, and 8 had anaplastic astrocytoma or oligodendroglioma. Forty-eight patients underwent an initial treatment, and 18 underwent recurrent surgeries. Infection, hydrocephalus, subcutaneous fluid collection, chronic subdural hematoma, early seizure after surgery within 1 month, symptomatic edema surrounding the resected cavity, cyst formation, and postoperative hemorrhage were defined as adverse events (AEs). RESULTS: Thirty-three patients underwent resection with VO, and 33 without. The median survival time was 28 months in the initial treatment group and 11.5 months in the recurrent treatment group. The with and without VO groups had similar median survival times. Postoperative AEs occurred in 7/33 patients (21.2%) with VO and 10/33 (30.3%) without VO, with no difference between them (P = 0.574). CONCLUSIONS: This study showed that VO during surgery with BCNU wafer implantation might not influence the occurrence of postoperative AEs. If VO happens, BCNU wafer implantation can be performed safely with accurate closing of the ventricle.

Organ-Specific Tumor Response to Pembrolizumab in Advanced Urothelial Carcinoma After Platinum-Based Chemotherapy.

BACKGROUND: To evaluate the organ-specific therapeutic effect of pembrolizumab after the failure of platinum-based chemotherapy for advanced urothelial carcinoma (UC). MATERIALS AND METHODS: Patients with advanced UC who received pembrolizumab after the failure of platinum-based chemotherapy and who had measurable disease were retrospectively analyzed. The objective response rate (ORR) and organ-specific response rate (OSRR) were evaluated according to Response Evaluation Criteria in Solid Tumors, version 1.1. RESULTS: We analyzed 69 patients (male, n=51; median age, 71 years) with 226 metastases. The ORR was 23.2%. In total, 32, 31, 16, 14, 13 and 7 patients had measurable lung (OSSR 31.3%), lymph node (OSSR 29.0%), local recurrence (OSSR 12.5%), primary tumor organ (OSSR 7.1%), liver (OSSR 23.1%) and bone (OSSR 28.6%) disease, respectively. The median overall survival (OS) for pembrolizumab was 10.9 months (95% confidence interval, 5.9­13.7 months). Regarding organ-specific OS, a Log rank test significant differences in OS were confirmed between patients with and without primary tumor organ disease (p=0.046) and liver metastasis (p<0.001). CONCLUSION: Metastases and primary tumor organ disease showed different tumor responses to pembrolizumab. The most prominent tumor response was found in lung metastasis and the least response was found in primary organ sites. The mechanisms of these different responses were unclear and there does not appear to be a constant trend between tumor shrinkage and OS in tumor sites. Further studies are needed.

Paclitaxel and carboplatin chemotherapy after platinum-based chemotherapy and pembrolizumab for metastatic urothelial carcinoma.

Pembrolizumab has been available for the treatment of radical resectable urothelial carcinoma (UC) when it is exacerbated after chemotherapy since December 2017 in Japan. However, the efficacy of chemotherapy for cases progressing after pembrolizumab is unclear. The present study compared the outcomes and toxicities in patients with metastatic UC after failure of platinum-based chemotherapy and pembrolizumab, who were selected to receive paclitaxel and carboplatin (TC) chemotherapy, with those in patients who received the best supportive care (BSC). A total of 36 patients received pembrolizumab for metastatic UC at four institutions between January 2018 and August 2019. Of the 21 patients who progressed after pembrolizumab, 7 received TC chemotherapy (TC group) and 14 selected BSC (BSC group). The median observation period was 4.1 months. The 7 aforementioned patients who received TC chemotherapy (4 male and 3 female; median age, 62 years; range, 57-79 years) were analyzed in the present study. The ECOG performance status was 0 in three patients, 1 in one patient, 2 in two patients and 3 in one patient. Two patients had upper urinary tract UC, two had bladder UC and three had both types of UC. Six patients had visceral metastasis. The number of chemotherapy regimens before pembrolizumab was one in four patients, two in two patients and three in one patient. The objective response rate was 28.6% (partial response, 2 patients; stable disease, 4 patients; progressive disease, 1 patient), the median progression-free survival time was 3.4 months and the median overall survival time was 10.9 months (vs. 2.7 months in BSC group; P=0.0156). Although grade ≥3 adverse events developed in five patients, there were no treatment-associated deaths. The present results suggested that TC chemotherapy may be a preferred option for patients who require aggressive treatment after the failure of platinum-based chemotherapy and pembrolizumab.

The Risk Factors of Febrile Urinary Tract Infection After Ureterorenoscopic Lithotripsy.

We aimed to evaluate the risk factors for febrile urinary tract infection (fUTI) following ureterorenoscopic lithotripsy (URSL) for upper urinary tract stones. We retrospectively reviewed the data of 109 patients with upper urinary tract stones who underwent URSL at our hospital from October 2016 to March 2019. We divided the patients into two groups: those who developed fUTI after URSL (fUTI group) and those who did not (non-fUTI group). The retrospectively collected data, including age, sex, body mass index (BMI), mobility, diabetes mellitus, operative duration, preoperative ureteral stent placement, number of stones, stone diameter, CT value of stone, stone location, preoperative UTI, preoperative urine culture, preoperative pyelonephritis, and stone-free status were compared between the two groups. Postoperative fUTI occurred in three of the 109 patients (2.8%). Comparing the two groups, a significant risk factor for developing fUTI after URSL was a low BMI. However, in our study, only three cases developed fUTI after URSL; thus, a multivariate analysis could not be performed. One of the three cases in which fUTI occurred was accompanied by anorexia nervosa and an extremely low BMI of 11 kg/m². In summary, even though we had only 3 fUTI patients and did not perform multivariate analysis, our data suggested a significant risk factor for developing fUTI was a low BMI. Increasing the sample size, and further study seem desirable.

Treating Japanese Patients With Pembrolizumab for Platinum-Refractory Advanced Urothelial Carcinoma in Real-World Clinical Practice.

BACKGROUND: Since December 2017, pembrolizumab has been approved in Japan as a second-line treatment for radical unresectable urothelial carcinoma (UC) that has become exacerbated after chemotherapy by the international randomized phase 3 trial, KEYNOTE-045. The aim of this study was to evaluate the oncological efficacy and safety of pembrolizumab after failure of platinum-based chemotherapy in Japanese patients with advanced UC in real-world clinical practice. METHODS: A total of 34 patients who received pembrolizumab after the failure of platinum-based chemotherapy for advanced urothelial carcinoma at four institutions between January 2018 and August 2019 were retrospectively evaluated. In all patients, UC was histopathologically diagnosed, and disease progression after platinum-based chemotherapy was radiologically confirmed. RESULTS: The median follow-up period was 7.7 months. The objective response rate, median progression-free survival, and median overall survival were 20.6%, 3.3 months, and 11.7 months, respectively. Regarding the toxicities associated with pembrolizumab, adverse events (AEs) of any grade occurred in 61.8%, and grade 3 AEs occurred in 23.5%; grade ≥ 4 AEs did not occur in any patients. Univariate analyses revealed that the Eastern Cooperative Oncology Group Performance Status, neutrophil/lymphocyte ratio, liver metastases, and time from previous chemotherapy were prognostic variables. Multivariate analyses revealed that liver metastases (positive: hazard ratio, 4.23; 95% confidence interval, 1.48 - 12.08; P < 0.01) and time from previous chemotherapy (≥ 3 months: hazard ratio, 5.06; 95% confidence interval, 1.43 - 17.91; P = 0.01) were independent prognostic factors. CONCLUSIONS: In this real-world clinical study, these findings concerning the efficacy and safety of pembrolizumab for advanced UC in Japanese patients were comparable to those of the open-label, international, phase 3 trial KEYNOTE-045. Liver metastases and time from previous chemotherapy were independent prognostic factors in the present study.

Efficacy and safety of sequential use of everolimus in Japanese patients with advanced renal cell carcinoma after failure of first-line treatment with vascular endothelial growth factor receptor tyrosine kinase inhibitor: a multicenter phase II clinical trial.

OBJECTIVE: Many studies have shown the efficacy of everolimus after pretreatment with vascular endothelial growth factor receptor-tyrosine kinase inhibitors. We investigated the efficacy and safety of everolimus as a second-line treatment after the failure of vascular endothelial growth factor receptor-tyrosine kinase inhibitor therapy in Japanese patients with advanced renal cell carcinoma. METHODS: This was an open-label, multicenter, phase II trial conducted in Japan through the central registration system. A total of 57  patients were enrolled. Patients were administered 10 mg of everolimus q.d. orally. The primary efficacy endpoint was progression-free survival achieved by administration of everolimus. RESULTS: The median progression-free survival of patients administered everolimus was 5.03 months (95% confidence interval: 3.70-6.20). The median overall survival was not reached. The objective response rate was 9.4% (95% confidence interval: 3.1-20.7). The progression-free survival in the group of <100% relative dose intensity was 6.70 months (95% confidence interval: 4.13-11.60), and that in the group of 100% relative dose intensity was 3.77 months (hazard ratio: 2.79, 95% confidence interval: 2.77-5.63). The commonly observed adverse events and laboratory abnormalities were stomatitis (49.1%), hypertriglyceridemia (26.4%), interstitial lung disease (26.4%), anemia (22.6%) and hypercholesterolemia (22.6%). CONCLUSION: The median progression-free survival was almost similar to that recorded in the RECORD-1 study, whereas prolongation of overall survival was observed in the present study compared with the RECORD-1 study. The treatment outcomes of first-line vascular endothelial growth factor receptor-tyrosine kinase inhibitor therapy and second-line everolimus treatment in Japanese patients were successfully established in the present study.

Predictive factors of late biochemical recurrence after radical prostatectomy.

OBJECTIVE: To assess the characteristics of biochemical recurrence in the late period (>5 years after radical prostatectomy) and the differences in the predictors of biochemical recurrence in different periods, we conducted a multicenter retrospective study. METHODS: We reviewed 478 men who underwent radical prostatectomy for clinically localized prostate cancer. All of the patients were followed up for at least 5 years. The cohort was then divided into three groups; no recurrence group, recurrence <5 years after surgery group and recurrence ≥5 years after surgery group. The background characteristics of each group were compared using the χ2 test. A Cox multivariate regression analysis was performed to determine the predictors of biochemical recurrence in each period. RESULTS: Biochemical recurrence occurred in 135 men. In 113 (84%) of the patients, biochemical recurrence occurred at <5 years after surgery; in 22 (16%), it occurred at ≥5 years after surgery. The proportion of men with a low preoperative prostate-specific antigen level was significantly larger in the latter group (P = 0.0023). A preoperative prostate-specific antigen level and a positive surgical margin were significant predictors of biochemical recurrence at <5 years after surgery (hazard ratio: 1.03 and 3.20). A positive surgical margin was also a significant predictor of biochemical recurrence at ≥5 years after surgery (hazard ratio: 3.03); however, a high preoperative prostate-specific antigen level was not. CONCLUSIONS: Biochemical recurrence occurred at ≥5 years after surgery in 16% of the patients. A positive surgical margin predicted biochemical recurrence in both the early and late periods.

Randomized controlled study of natural interferon α as adjuvant treatment for stage II or III renal cell carcinoma.

BACKGROUND: The prophylactic effect of postoperative interferon on recurrence and distant metastasis in stage II or III renal cell carcinoma is unclear. In most studies, interferon has been administered for 6 months or less. Therefore, we performed a clinical study of the efficacy of 1-year postoperative administration of natural interferon α, which is generally used in Japan. METHODS: The subjects were patients diagnosed with stage II or III renal cell carcinoma who underwent radical nephrectomy. The subjects were randomly allocated to receive an intramuscular injection of natural interferon α (3 million to 6 million units) 3 times a week for 1 year or to receive follow-up observation until recurrence or metastasis occurred. Chest and abdominal CT were performed once yearly for all patients. The primary endpoint was progression-free survival. RESULTS: From September 2001 to August 2006, a total of 107 patients were registered, but 7 subsequently withdrew from the study. Therefore, 100 patients were included in the analysis. The primary endpoint of progression-free survival did not differ significantly between the groups that received natural interferon α or follow-up observation (p = 0.456, log-rank test). However, peak hazards of progression in the interferon group were delayed for about 6-10 months compared with the observation group. CONCLUSION: Progression-free survival showed no improvement after administration of natural interferon α to patients with stage II or III renal cell carcinoma for 1 year after radical nephrectomy. The peak hazards of progression might be delayed by about 6 months by interferon administration.

Ureterosciatic hernia successfully treated by ureteral stent placement.

A 76-year-old woman with history of cholecystectomy, hysterectomy, and vesicourethral suspension presented with acute lumbar backache and discomfort in the lower abdomen and severe nausea, with frequent vomiting, but without any associated fever. Physical examination revealed knocking tenderness at the left costal-vertebral angle. The patient's serum white blood cell count was 14,900/mm(3) and the results of other laboratory tests, including urinalysis, were normal. Non-enhanced computed tomography revealed left hydroureteronephrosis and obstruction of the distal left ureter with herniation into the sciatic foramen. A left ureteral stent was inserted with a double-J stent. The stent was removed after 2 months and thereafter the patient did not experience any recurrence.

Late recurrence of renal cell carcinoma: retrospective and collaborative study of the Japanese Society of Renal Cancer.

OBJECTIVES: To evaluate in collaboration the clinical features of late recurrence of renal cell carcinoma (RCC). Late recurrence is one of the specific biologic behaviors of RCC; however, the clinical and pathologic features of the late recurrence of RCC are not fully understood. METHODS: A total of 470 patients who had undergone curative treatment of RCC and had not developed recurrence within 10 years of follow-up were documented from 13 institutions of the board members of the Japanese Society of Renal Cancer. Multivariate analysis with Cox proportional hazards model was used to determine the pathologic and clinical factors affecting the late recurrence and survival of patients with RCC ≥10 years after surgery. Survival analysis was performed using the Kaplan-Meier method. RESULTS: During the 10-28-year (median 13.2) observation period, 30 patients (6.4%) developed a late recurrence. The disease-free survival rate at 15 and 20 years was 89.5% and 78.4%, respectively. Multivariate analysis showed that lymph node metastasis was the only factor to predict for late recurrence (P = .0334). Age at nephrectomy was the only prognostic factor for overall survival on multivariate analysis (P < .0001). Of the 470 patients, 30 had developed late recurrence in 44 sites, including the lung (36.4%), kidney (25%), and bone (13.6%), followed by the brain, pancreas, adrenal gland, lymph nodes, and liver. Late recurrences in the lung or kidney were observed at any time ≥10 years after nephrectomy. CONCLUSIONS: Late recurrence of RCC after initial treatment is not a rare event, and lifelong follow-up is necessary.

Injection-site granulomas resulting from the administration of both leuprorelin acetate and goserelin acetate for the treatment of prostatic cancer.

Although injection-site granulomas caused by leuprorelin acetate have been reported, there have been no reports of granulomas caused by both leuprorelin acetate and goserelin acetate. An 81-year-old man presented with subcutaneous nodules of the abdominal wall and upper arm, where 11.25 mg of leuprorelin acetate had been injected for the treatment of prostate cancer. Because of these nodules, treatment was changed to goserelin acetate. Nevertheless, he presented with another subcutaneous nodule at the injection site. Histological examination showed that these nodules consisted of numerous giant cells that were CD3-positive T lymphocytes and CD68-positive histiocytes associated with granulomatous changes. The granulomas had likely been caused by delayed-type hypersensitivity to leuprorelin acetate injection. The granuloma that formed after goserelin acetate injection might thus have developed owing to the immunogenicity of the previous leuprorelin acetate injections. The patient underwent surgical castration. The present case suggests that both leuprorelin acetate and goserelin acetate can cause injection-site disorders.

Injection-site granulomas due to the administration of leuprorelin acetate for the treatment of prostatic cancer.

Luteinizing hormone-releasing hormone (LH-RH) analogues have become the main focus of androgen deprivation therapy for prostatic cancer. The occurrence of injection-site granulomas due to the administration of LH-RH analogues has been thought to be a rare reaction. We herein report a rare case presenting injection-site granuloma due to the administration of leuprorelin acetate, mimicking metastatic nodule. A 90-year-old man presented with subcutaneous nodules at the injection-site of leuprorelin acetate 11.25 mg (for 3-month use). Ultrasound examination and computed tomography (CT) revealed two nodules in the bilateral abdominal walls mimicking metastatic nodule. Although he was surgically treated because of the possibility of malignancy, in the end, no evidence of malignancy was found. We should keep in mind that LH-RH analogues may cause injection-site granulomas mimicking metastatic nodule, and therefore we must inform patients undergoing the administration of leuprorelin acetate that it may cause injection-site granuloma and thus when a patient demonstrates a subcutaneous nodule it is essential to confirm whether or not he has received an injection of the LH-RH analogue at the site of nodule.

Incidence rate of injection-site granulomas resulting from the administration of luteinizing hormone-releasing hormone analogues for the treatment of prostatic cancer.

PURPOSE: Granulomas resulting from the administration of luteinizing hormone-releasing hormone analogues (LH-RH analogues) are thought to be very rare. We report on our clinical experience with injection-site granulomas that result from the administration of LH-RH analogues, and we evaluate the incidence rate of these granulomas. MATERIALS AND METHODS: We used the clinical records of 118 patients who were administered LH-RH analogues in 2005. We describe the clinical data of patients who experienced injection-site granulomas and evaluated the incidence rate. RESULTS: Five patients demonstrated injection-site granulomas due to LH-RH analogue administration. The incidence rate was 4.2% (5 of 118 patients). Most of the granulomas occurred after the first or second administration of 11.25mg of leuprorelin acetate. CONCLUSION: The occurrence of granulomas resulting from the administration of LH-RH analogues was thought to be very rare. Our study, however, revealed a higher incidence rate than expected, especially for leuprorelin acetate.

Collecting duct (Bellini duct) renal cell carcinoma: a nationwide survey in Japan.

PURPOSE: Collecting duct carcinoma, a rare type of renal cell carcinoma, remains poorly understood. To analyze the nature of collecting duct carcinoma a retrospective survey was performed in Japan. MATERIALS AND METHODS: This survey was done from August 2001 to April 2003. A total of 281 institutions throughout Japan were requested to document all cases of collecting duct carcinoma. All pertinent clinical information was compiled, including patient age, sex, mode of presentation, evaluation modality, preoperative laboratory data, surgery type, macroscopic and microscopic findings, and survival data. Two urological pathologists reviewed microscopic slides of all tumor specimens to confirm collecting duct carcinoma. RESULTS: Two pathologists confirmed collecting duct carcinoma in 81 of the 120 cases documented as collecting duct carcinoma. Mean patient age was 58.2 years and males comprised 71.6% of all patients. The mode of presentation was classified as symptomatic in 65.4% of cases, incidental in 24.7% and not available in 9.9%. Regional lymph node metastasis was histologically detected in 44.2% of patients who underwent lymph node dissection, while 32.1% of the population had distant metastasis at presentation. Although postoperative adjuvant therapy against metastasis or recurrence was performed in 25 patients, no obvious responses were identified except in 1 with lung metastases, who showed a partial response to combined gemcitabine and carboplatin therapy. At a median followup of 15 months 1, 3, 5 and 10-year disease specific survival was 69.0%, 45.3%, 34.3% and 13.7%, respectively. CONCLUSIONS: We report what is to our knowledge the largest known series of collecting duct carcinoma. Since advanced or recurrent collecting duct carcinoma is resistant to standard treatment modalities, new treatment strategies are needed for advanced collecting duct carcinoma.

In vivo growth of transitional and renal cell carcinoma cell lines can be suppressed by the adenovirus-mediated expression of a soluble form of vascular endothelial growth factor receptor.

Antiangiogenic therapy is a promising strategy for the treatment of cancer since tumor development and metastases require angiogenesis. Vascular endothelial growth factor (VEGF) is one of the most important factors in tumor angiogenesis. In the present study, we investigated the antitumor effect of an adenovirus (AdVEGF-ExR) expressing the extracellular domain of the human VEGF receptor (flt-1) using two different urological tumor/mouse systems. RENCA, a renal cell carcinoma of BALB/c origin, and MBT-2, a poorly differentiated transitional carcinoma of C3H/He origin, were used. Both types of tumor were in vitro infected with AdVEGF-ExR and inoculated subcutaneously into the abdomens of syngenenic mice, and tumor growth was measured twice weekly. In some experiments, BALB/c mice with established RENCA tumors were injected intramuscularly with AdVEGF-ExR as a therapeutic model. The cytotoxicity of spleen cells from the tumor-rejected mice was assessed by 51Cr-release assay. Although the in vitro cell growth of either MBT-2 or RENCA was not affected by infection with AdVEGF-ExR, the in vivo growth of both AdVEGF-ExR-infected tumors was significantly suppressed in the syngeneic mice. In addition, although 2 of 5 mice rejected the AdVEGF-ExR-infected RENCA, tumor-specific cytotoxic T lymphocytes were not generated from their spleen cells, thus suggesting no cellular immune response. In a therapeutic model, intramuscular injections of AdVEGF-ExR at a remote site also significantly suppressed the growth of the subcutaneously established RENCA. These results indicate that the adenovirus-mediated expression of a soluble VEGF receptor can be an effective therapy for urological cancer treatment; however, such VEGF-targeted gene therapy is not necessarily accompanied by subsequent antitumor T cell immunity.

The change of the split renal function before and after a nephrectomy using Tc-mercaptoacetyltriglycine (MAG3).

OBJECTIVE: We examined the change in the renal function in the normal side kidney before and after a nephrectomy, by means of a newly developed diuretic renography technique utilizing Tc 99m-mercaptoacetyltriglycine (MAG3). MATERIALS AND METHODS: Forty patients who underwent a nephrectomy were evaluated using MAG3 diuretic renography. We measured the effective renal plasma flow (ERPF) and Tmax time before and after a nephrectomy. The effects of the patient age and the preoperative ERPF of ill side kidney on the post operative ERPF were then assessed statistically. RESULTS: The ERPF increased by an average of 44.8 ml/min at 2 weeks after a nephrectomy, but it decreased by an average of 24.3 ml/min at 3 months after a nephrectomy. The Tmax time decreased by an average of 0.58 min at 2 weeks, but thereafter increased by an average of 0.58 min at 3 months after a nephrectomy. The correlation coefficient between the rate of increase in the ERPF and the patient age was 0.197. CONCLUSIONS: The rise of renal function in terms of ERPF and the Tmax time was observed at 2 weeks post-nephrectomy. However, this effect disappeared at 3 months post-nephrectomy. These data demonstrated that the rise in the renal function of the normal-side kidney in such patients was only temporary.

Tumor doubling time of renal cell carcinoma measured by CT: collaboration of Japanese Society of Renal Cancer.

OBJECTIVE: This study was conducted to examine the natural history of renal cell carcinoma (RCC). METHODS: Inclusion criteria were the following: (1) patients who received diagnostic imaging of the kidney (CT, MRI) at two points in time before the diagnosis of RCC or patients who were followed, without treatment, after a diagnosis of RCC; and (2) patients in whom changes in tumor size were followed by the same modality of diagnostic imaging and who did not receive any treatment which could exert anti-tumor activity on the primary or metastatic lesions. The tumor doubling time (DT) and the growth rate of maximum tumor diameter (R) were determined. DT was calculated using the equation DT = (T - T(0)) x log2/logV - logV(0) (where T - T(0) indicates the length of time between two measurements and V(0) and V denote the tumor volume at two points of measurement). R was calculated using the equation R = (phi - f(0))/(T - T(0)) x 100 (where phi(0) and f indicate the maximum diameter at two points). Fifty-six cases registered with the Japanese Society of Renal Cancer were included in the evaluation. RESULTS: DT was 603.1 +/- 510.1 days, which did not correlate with V(0). R was 0.263 +/- 0.346 cm/day x 100. In cases where the tumor diameter was >/=4 cm, a significant correlation was noted between f(0) and R. CONCLUSIONS: Elucidation of the natural history of RCC will contribute to facilitation of differential diagnosis and determination of optimum therapeutic strategy.

Inhibition of gluconeogenesis and p-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-beta- d-glucosaminidase and gamma-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 degrees C for 90 min. 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 90 mg I/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 60 mg I/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 60 mg I/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.