Evaluation of airborne asbestos exposure from routine handling of asbestos-containing wire gauze pads in the research laboratory.

Three independently conducted asbestos exposure evaluations were conducted using wire gauze pads similar to standard practice in the laboratory setting. All testing occurred in a controlled atmosphere inside an enclosed chamber simulating a laboratory setting. Separate teams consisting of a laboratory technician, or technician and assistant simulated common tasks involving wire gauze pads, including heating and direct wire gauze manipulation. Area and personal air samples were collected and evaluated for asbestos consistent with the National Institute of Occupational Safety Health method 7400 and 7402, and the Asbestos Hazard Emergency Response Act (AHERA) method. Bulk gauze pad samples were analyzed by Polarized Light Microscopy and Transmission Electron Microscopy to determine asbestos content. Among air samples, chrysotile asbestos was the only fiber found in the first and third experiments, and tremolite asbestos for the second experiment. None of the air samples contained asbestos in concentrations above the current permissible regulatory levels promulgated by OSHA. These findings indicate that the level of asbestos exposure when working with wire gauze pads in the laboratory setting is much lower than levels associated with asbestosis or asbestos-related lung cancer and mesothelioma.

Caveolin-1 immunohistochemical analysis in differentiating chromophobe renal cell carcinoma from renal oncocytoma.

Chromophobe renal cell carcinoma (ChRCC) and oncocytoma might mimic each other histologically. We studied the immunohistochemical staining pattern of caveolin-1 in 21 ChRCCs and 26 oncocytomas and compared it with cytokeratin (CK) 7 to evaluate its usefulness in differentiating these 2 neoplasms. All 21 ChRCCs (100%) were positive for caveolin-1, 20 of which were stained in 20% or more of the tumor cells. In contrast, only 3 (12%) of 26 oncocytomas showed positivity in fewer than 20% tumor cells and 23 (88%) of 26 were negative. In the nonneoplastic kidney, positive caveolin-1 staining was detected in the interstitial blood vessels and the parietal cells of the Bowman capsules but not in the tubular epithelium and glomerular and peritubular capillaries. All 21 ChRCCs (100%) were positive for CK7, with 18 (86%) stained in 20% or more of the tumor cells and 3 (14%) in fewer than 20%. Of 26 oncocytomas, 25 (96%) were positive for CK7, with 7 (27%) stained in 20% or more of the tumor cells and 18 (69%) in fewer than 20%. These results strongly suggest that caveolin-1 immunohistochemical analysis is useful for differentiating ChRCC from oncocytoma and is superior to CK7.

Expression of caveolin-1 and caveolin-2 in urothelial carcinoma of the urinary bladder correlates with tumor grade and squamous differentiation.

We immunohistochemically evaluated 94 cases of urothelial carcinoma (UC) of the urinary bladder for the expression of caveolin (Cav)-1 and Cav-2. Neither benign urothelium present in 22 cases nor flat carcinoma in situ present in 10 cases stained for Cav-1 or Cav-2. Thirty-five (37%) of 94 cases and 45 (51%) of 89 cases of UC stained positively for Cav-1 and Cav-2, respectively. The percentages of positive cases for Cav-1 in grades 1, 2, and 3 tumors were 0% (0/6), 0% (0/25), and 56% (35/63), respectively (P < .001), and for Cav-2, 0% (0/6), 13% (3/23), and 70% (42/60), respectively (P < .001). Multivariate analysis showed no significant correlation between tumor stage and Cav-1 or Cav-2 expression after correction for tumor grade. Eighty-two percent (14/17) of cases with squamous differentiation were positive for Cav-1 compared with 43% (20/46) of grade 3 tumors without squamous differentiation (P < .001). These results indicate a positive correlation of the expression of Cav-1 and Cav-2 with tumor grade and squamous features of UC and suggest that Cav-1 and Cav-2 be studied further for a possible role in tumor progression and squamous differentiation.