Resin corrosion cast (Mercox) in experimental evaluation of small vessel anastomosis

This study focuses on obtaining more information about the site of anastomosis, with three-dimensional examination using methylmethacrylate resin (Mercox) corrosion casts. Seventy microvascular anastomoses were performed in Wistar albino rats, divided into two groups before sacrifice. In Group 1 (35), Mercox was injected into the vessels, whereas in Group 2 (35), the tissues were prepared without injecting Mercox. Both groups were compared under the scanning electron microscope (SEM). The SEM preparation in Group 1 was simple, easy, and artifacts were significantly minimized. The anastomotic site could be well appreciated in three-dimensional views. Clear negative imprints of the endothelial surface were achieved without any breakage in the Mercox corrosion cast, and it can be reliably used in the evaluation of small vessel anastomosis.     

Simultaneous non-parametric confidence intervals for survival probabilities from censored data

In medical studies with censored data Kaplan and Meier's product limit estimator has frequent use as the estimate of the survival function. Simultaneous confidence intervals for the survival function at various time points constitute a useful addition to the analysis. This study compares several such methods. We consider in a simulation investigation two whole curve confidence bands and four methods based on the Bonferroni inequality. The results show that three Bonferroni-type methods are essentially equivalent, all being better than the other methods when the number of time points is small (3 or 5).     

Silicosis in a grey iron foundry. The persistence of an ancient disease

An industrial hygiene and medical survey was conducted in an iron foundry to study the occurrence of silicosis. Breathing zone exposures to respirable crystalline silica had been very high in 1977 [1 045 micrograms/m3 (geometric mean) for coremakers and 198 micrograms/m3 for fettlers]; exposures in 1980 and 1982 were substantially lower. A radiographic evaluation of 188 workers revealed silicosis in 18 (9.6%). Eight had category 1 profusion of small rounded pulmonary lesions (by the 1980 classification of the International Labour Office); two had category 2; and eight had category 3. Two had progressive massive fibrosis. Four workers without silicosis in 1977 had developed lesions by 1980. The prevalence increased from 1.5% among workers employed less than 20 years to 53% among longer term workers. No association was found between the prevalence of silicosis and cigarette smoking. Chronic cough was more common in workers with heavy current dust exposure than in those with light exposure, more common in smokers than in nonsmokers, and more common in silicotics than in nonsilicotics. A multiplicative interaction existed between dust exposure and smoking in the etiology of cough. Silicosis continues to exist in American foundries. Cigarette smoking does not contribute to the causation of silicosis, but it aggravates the attendant respiratory symptoms.