Lung injury induced by mycobacterial cell walls: Effects on connective tissue

Intravenous injection of cell walls from Mycobacterium bovis strain BCG results in increased lung mass in the rat 4 months after injection. Histologically, there is a simultaneous increase in interstitial material and the formation of granulomata. The granulomata do not show increased staining for collagen by a trichrome stain. Prominent reticulin is present in the granulomata as shown by a silver stain. Lung dry weight is significantly increased 4 months after the injection of 300 μg cell walls; the total amount of collagen is significantly increased, but its concentration (amount per mg dry weight) is similar to that of controls. At 6 months, lung collagen amounts in BCG-treated animals are not significantly different from those of controls. By 10 months the granulomata largely disappear, lung architecture returns to normal, and lung collagen amounts are at control levels. In this model of lung injury, increases in lung connective tissue proteins are not selective and they do not persist as the lung returns to normal histologically.     

MRSPAH: A simple microtitre plate test for rheumatoid factors of different classes

A simple and inexpensive microtitre plate test (the mixed reverse (solid-phase) passive antiglobulin haemadherence test, or MRSPAH) has been developed for the measurement of antiglobulins (RFs) of different classes. Results obtained for IgM RF by this test have been compared with results of latex and Rose-Waaler (DAT) tests on rheumatoid arthritis (RA) sera. Levels of RFs of IgM, IgG and IgA classes have been measured by MRSPAH using rabbit IgG as antigen in RAs and normal people. 94% of RA sera tested were above the upper limit of normal for IgM and/or IgA RF. There was a considerable overlap between IgG RF levels in RAs and normals, although the means of the two groups were significantly different.     

Asbestos body concentrations in human lung: predictions from asbestos body counts in tissue sections with a mathematical model

A mathematical model for predicting the concentration (Nv) of asbestos bodies (AB) in human tissue from the count (No) of these bodies in planar tissue sections is presented. The result is the equation Nv = No/[0.54 X A X (La + t)], giving the concentration of AB in numbers per gram of wet lung tissue. La, the average length (in microns) of the AB, is specific for each case; A is the area (square millimeters) of the tissue counted, and t is the thickness of the section (in microns). This equation fits experimental digestion results to a multiplicative error factor of less than 3. When an estimate of La, such as 51.6 microns, is used, the equation is less accurate but probably sufficiently accurate for the screening of lung specimens.