Effects of thermocycling on the margins of transitional acrylic resin crowns.

Transitional resin crowns were subjected to thermocycling and examined for marginal integrity since disturbance of the marginal seal is detrimental. Two groups of 10 crowns, one with a chamfer and the second with a shoulder finish line, were subjected to two series of 2500 thermocycles. In the first series, the crowns received cold thermocycling and in the second, hot thermocycling.

Microvascular transport and endothelial cell alterations preceding skeletal muscle damage in ischemia and reperfusion injury.

We determined the leakage of macromolecules using FITC-dextran-150 as a tracer and measured the extent of no-reflow phenomenon by video field analysis. The cremaster muscle of anesthetized rats was fashioned as a single layer, splayed on a lucite chamber and suffused with bicarbonate solution at 35 degrees C. After a 1 hour period of baseline data collection, ischemia was produced by cross-clamping the cremasteric vascular pedicle for periods of 30 minutes and 2 hours in separate experiments.

The microscopic appearance and effect of toothbrushing on extrinsically stained metal-ceramic restorations.

To clarify the nature and longevity of the extrinsic stain layer of metal-ceramic restorations, a series of experiments were undertaken. It was found, with microscopic examination, that there is little or no diffusion of the stain into the underlying porcelain and that at a thickness of 22 microns the extrinsic stain layer is grossly evident to an observer. Using a fluoride dentifrice caused no significant loss of either stain or surface integrity with 120,000 brush strokes (equivalent to 8.

An ultrastructural morphometric comparison of the peripheral with the hilar air-blood barrier of dog lung.

Excised and isolated perfused lungs are frequently used as models for studies of fluid flow and membrane transport. Regional variations of the air and blood vascular compartments of the lung have been recognized to result from gravitational effects. This ultrastructural morphometric study considered the components of the air-blood barriers of the peripheral and hilar regions of excised dog lungs.

Morphological changes in lipid droplets within cells of the duodenal transition zone in suckling rats.

This ultrastructural study compares the lipid droplets within epithelial cells at the bases of the duodenal villi in the transition zone between crypts and the lateral portions of the adjacent villi in newborn rats suckled 24 h, 10 days and 15 days and contrasts with cells in similar locations in newborn unsuckled and weaned rats. The mean diameters and numbers of lipid droplets per field decreased when cells from rats at 10 and 15 days of age were compared to those at 24 h of age. The range of sizes also narrowed.