Fibrosis of the lung and pleura and long-term exposure to wollastonite.

OBJECTIVES: The purpose of this study was to determine whether long-term exposure to wollastonite causes fibrosis of the lung and pleura in humans. METHODS: Forty-nine workers (mean exposure 25 years) in a Finnish limestone-wollastonite mine and mill were examined. Their work histories and symptoms of chronic bronchitis were recorded. The chest radiographs were classified according to the classification of the International Labour Office (1980); a radiographic follow-up from 1981 to 1990 was included. Spirometry and diffusion capacity were measured. Four workers underwent high-resolution computed tomography (HRCT) and bronchoalveolar lavage (BAL). Lung tissue specimens were available for 2 workers. Mineral fibers and asbestos bodies were analyzed from the BAL fluid and lung tissue specimens, which were also analyzed for lung fibrosis. RESULTS: Two workers (4%) had small irregular lung opacities (ILO 1/0), 1 worker (2%) ILO 0/1 of the s/t type. HRCT revealed no parenchymal fibrosis in the 2 workers with the ILO 1/0 classification. Of the 9 workers (18%) with pleural plaques, 5 had been exposed to asbestos. Multivariate logistic regression analyses revealed no association of plaques with the duration of wollastonite or asbestos exposure. Wollastonite fibers or bodies were not found in any of the 4 workers who underwent BAL, nor in either of the workers whose lung tissue specimens were available. CONCLUSIONS: No evidence was found that long-term exposure to wollastonite causes parenchymal fibrosis of the lung and pleura. Furthermore, the findings indicate that wollastonite fibers are poorly retained in human lungs.

Decrease of plasma prekallikrein and kallikrein inhibitors during intravenous phlebography.

Complex contact activation systems may have major involvement in side effects of i.v. contrast media. To investigate this, quantitative measurements of several factors (plasma prekallikrein, kallikrein inhibitory activity, haematocrit, alpha-2-macroglobulin, antithrombin III, alpha-1-antitrypsin and beta-thromboglobulin) were made before and after i.v. contrast phlebography in two groups of patients (each containing 21 patients) with no thrombosis, using a high- (meglumine iodamide) and a low-osmolality (ioxaglate) contrast medium. A statistically significant decrease in plasma prekallikrein was observed after the high-osmolality contrast medium, which is a sign of the activation of the kallikrein-kinin system and an indicator of the activation of the intrinsic coagulation. These events may play an important role in the adverse effects of contrast media.

Sonography in differential diagnosis of deep venous thrombosis of the leg.

The lower extremities of 60 consecutive symptomatic patients were examined first by ultrasound (US) and then by phlebography. Deep venous thrombosis was found in 17 patients by means of venography. A hematoma was detected by US in six legs without thrombosis. A popliteal cyst was observed by US in five cases; one patient had a concurrent deep venous thrombosis. It was concluded that symptomatic patients with a negative phlebography should be examined by US for correct diagnosis and treatment, although US cannot replace phlebography.

99mTc-plasmin test in deep vein thrombosis of the leg.

A 99mTc-plasmin test and phlebography were performed on 45 consecutive unselected patients with suspected deep vein thrombosis of the leg. Phlebography showed thrombosis in 15 cases. In fourteen of these patients there was a positive result in the plasmin test. Eleven other patients had a positive plasmin test result as well. The most common causes for a false-positive result in the plasmin test in the diagnosis of deep vein thrombosis were acute inflammatory disease and disturbance in venous flow without fresh thrombosis. The sensitivity of the plasmin test in the diagnosis of deep vein thrombosis was 93% and the specificity was 63%. It is concluded that the plasmin test can be used for the screening of deep vein thrombosis.

Improvement of x-ray intensifying screen efficiency by special design of the screen.

An investigation of light diffusion in x-ray intensifying screens and the prospects for improvement by confining light spread with a special structure are reported. Light diffusion in CaWO4 screens was studied theoretically using computer simulation. The proportion and spatial distribution of light emerging from different depths in the screen were calculated. The introduction of narrow gaps in the screens made it possible to improve these proportions and distributions. The gaps improved the line spread functions, the screen efficiencies, and the average contribution of the absorbed quanta to the light output.

Thermography in deep venous thrombosis of the leg.

Thermography, a fast, simple, and sensitive method, was compared with conventional contrast medium phlebography in the diagnosis of acute deep venous thrombosis of the lower extremities in 141 patients. In 84% of the cases, the results with both techniques agreed. Thermograms showed the pathologic findings in 38 of 41 cases with deep thrombosis. In the three cases with false-negative findings, only the anterior surfaces of the legs were studied. In 19 cases, pathologic thermograms were recorded in the absence of deep thrombosis; the main reasons for findings were posttraumatic, postoperative, and postthrombotic states, and insufficiency of the perforant veins. If a patient has no previous history of a venous or other intervening disease, thermography with a negative finding excludes deep venous thrombosis. If it is used as a primary method, it can replace many phlebographies in the diagnosis of acute deep venous thrombosis.