Urinary cytology is increasingly accepted as a diagnostic tool in the detection and follow‐up of patients with bladder cancer. Its potential value has been reduced, however, by the relative inexperience of most pathologists in the examination of urinary specimens, and by the lack of cellular criteria specifically reflecting the morphology of low‐grade papillary and flat lesions of bladder epithelium. The cytologic features of urothelial lesions, including papillary transitional cell carcinomas and flat urothelial dysplasias have been studied in both experimental systems and clinical situations and their application to a selected patient population is presented. Overall, the cytohistologic correlation for patients with bladder cancer was 92%. Positive cells reflecting the morphology of the tumor occurred in 62% of patients with grade I transitional cell carcinomas, and cells suspicious for malignancy were identified in an additional 14% of these individuals. Using the criteria presented, a positive cytology can correlate with a papillary grade I bladder tumor, and should not necessarily indicate the presence of another neoplasm. Dysplastic cells in cytologic specimens are often identified in patients having urothelial dysplasia as the most serious bladder lesion, but the cytologic diagnosis of dysplasia may represent an under‐interpretation of a lowgrade papillary bladder tumor. The cells of urothelial neoplasms, including low‐grade transitional cell carcinomas and dysplasias, differ morphologically both from normal and reactive/reparative elements, and can be detected in cytologic samples. The changes are often subtle and require experience and a cautious approach for accurate interpretation.

To our knowledge our study represents the largest group of spinal cord injured patients to undergo biopsy evaluation after chronic catheter use. A spectrum of inflammatory and proliferative pathological conditions were identified, which were predominantly inflammatory and squamous. The need to survey ongoing transitional mucosal changes in this population is underscored by the spectrum of histological abnormalities and the significant occurrence of malignant pathologies in our patients.

SummaryNewborn puppies were paired (n = 21 pairs) at birth, given gentamicin (5 mg/kg/day for 7 days and then 7.5 mg/kg/day) or saline intramuscularly (IM) and studied at 10, 20, or 30 days of age. Peak gentamicin concentrations correlated neither with total body water nor extracellular fluid volume. The ratio of outer/inner cortical gentamicin concentrations increased with therapy (n = 0.579; P < 0.01). Pathologic changes in proximal tubular cells of superficial and juxtamedullary cortices corresponded to tissue accumulation of gentamicin. Inulin clearance was lower but not statistically different in gentamicin puppies at 20 and 30 days, but tubular reabsorption of phosphate was lower at 30 davs ( P < 0.02).Plasma creatinine decreased during the first month of fife in both control and gentamicin puppies (n = -0.370; P < 0.02) and was not different between puppies even at 20 and 30 days when tubular damage was marked. No differences in urine sediment, osmolarity, glucose, and protein concentrations were noted between paired animals. Mean values of gentamicin half-life in gentamicin (control) puppies decreased from 80.3 (84.0) min at 10 days to 45.3 (50.3) min a t 20 days, but increased to 61.0 (40.0; P < 0.05) min at 30 days. Similar studies in older puppies and adult animals given gentamicin resulted in an increase in plasma creatinine and gentamicin half-life within 10 days.

To our knowledge our study represents the largest group of spinal cord injured patients to undergo biopsy evaluation after chronic catheter use. A spectrum of inflammatory and proliferative pathological conditions were identified, which were predominantly inflammatory and squamous. The need to survey ongoing transitional mucosal changes in this population is underscored by the spectrum of histological abnormalities and the significant occurrence of malignant pathologies in our patients.

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