Expression of αvβ6integrin in oral leukoplakia

The distribution of αvβ6integrin was examined in oral leukoplakia, lichen planus and squamous cell carcinomas using immunohistochemistry. Controls included oral mucosal wounds, chronically inflamed and normal oral mucosa. Integrins β1, β3, β4, β5, fibronectin and tenascin were also studied. The integrin αvβ6was highly expressed throughout the whole lesion of 90% of the squamous cell carcinomas but was not present in any of the normal specimens. αvβ6integrin was also expressed in 41% of the leukoplakia specimens, and 85% of the lichen planus samples, but in none of the tissues with inflammatory hyperplasia or chronic inflammation. The expression of β1 integrins was localized in the basal layer, and that of the β4at the cell surface facing the basement membrane of all specimens. The integrins β3and β5were absent from all normal and leukoplakia specimens. Fibronectin and tenascin were present in the connective tissue underneath the epithelium of all the sections, and their expression was similar in both αvβ6-positive and αvβ6-negative tissues. A group of 28 leukoplakia patients were followed 1–4 years after first diagnosis. In this group, initially αvβ6integrin-positive leukoplakia specimens had high tendency for disease progression while αvβ6-negative specimens did not progress. These results suggest that the expression of αvβ6integrin could be associated in the malignant transformation of oral leukoplakias. © 2000 Cancer Research Campaig

Applicability of heat transfer and solidification simulations in investigating microstructural banding in continuously cast steel

Abstract Microstructural banding is observed as alternating microstructures in cast steel products, parallel to cast/rolling direction. Banding, causing hardenability issues and anisotropy of mechanical properties, is considered to originate from the interdenritic segregation during the solidification of steel. In this study, a three-dimensional heat transfer model (3DHTM) was used to simulate the steady-state local temperatures in a casting strand of 0.34C low alloy carbon steel, taking into account both primary and secondary cooling as well as other casting parameters. The calculated temperature profiles for a set of selected locations along the strand were used as input data for a solidification and microstructure model (SMM) for the continuous casting of steel. To assess the microstructure of the cast bloom, the prior austenite grain size, dendrite arm spacing, and the magnitude of elemental microsegregation between the dendrites were calculated with the selected temperature profiles for the steel grade. For validation purposes, bloom and bar samples were prepared from industrial trials. The calculated results are compared to the microstructural characterization of austenite grain size, and local elemental concentrations obtained with electron probe microanalyzer (EPMA). Based on the results, elemental microsegregation and microstructural banding is assessed, affected by casting parameters and the total composition of steel. Additionally, a brief discussion of the segregation between the bloom and bar samples is presented