Thomas E. Williamson

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The mechanism of the protective actions of sucralfate against ethanol-induced gastric mucosal damage in the rat has been investigated. In particular, the role of prostaglandins as mediators of such protection was assessed. Oral administration of sucralfate at a dose causing a significant reduction of ethanol-induced gastric damage (500 mg/kg) did not(More)
Non-avian dinosaurs went extinct 66 million years ago, geologically coincident with the impact of a large bolide (comet or asteroid) during an interval of massive volcanic eruptions and changes in temperature and sea level. There has long been fervent debate about how these events affected dinosaurs. We review a wealth of new data accumulated over the past(More)
Studies using a gastric chamber model demonstrated that sucralfate protected the rat gastric mucosa against hemorrhagic erosions induced by 40 percent ethanol and by acidified 80 mM sodium taurocholate. Protection required continuous contact of sucralfate with the gastric mucosa but it occurred without the production, by sucralfate alone, of significant(More)
The ability of a mild irritant to reduce ethanol-induced damage to the rat gastric mucosa was investigated using an ex vivo gastric chamber preparation. Exposure to 0.25 M hydrochloric acid (HCl) did not cause significant damage to the surface epithelium, but did reduce both the lesion area and the extent of superficial epithelial damage caused by(More)
The fossil record of late Campanian tyrannosauroids of western North America has a geographic gap between the Northern Rocky Mountain Region (Montana, Alberta) and the Southwest (New Mexico, Utah). Until recently, diagnostic tyrannosauroids from the Southwest were unknown until the discovery of Bistahieversor sealeyi from the late Campanian of New Mexico.(More)
Metatherians, which comprise marsupials and their closest fossil relatives, were one of the most dominant clades of mammals during the Cretaceous and are the most diverse clade of living mammals after Placentalia. Our understanding of this group has increased greatly over the past 20 years, with the discovery of new specimens and the application of new(More)
Primates underwent a period of diversification following the extinction of non-avian dinosaurs. Although the Order first appeared near the Cretaceous-Paleogene boundary, it is not until the Torrejonian (the second North American Land Mammal Age of the Paleocene) that a diversity of families began to emerge. One of the lithological units critical to(More)
BACKGROUND Taeniodonta is a clade of Late Cretaceous-Paleogene mammals remarkable for their relatively extreme cranial, dental, and postcranial adaptations and notable for being among the first mammals to achieve relatively large size following the Cretaceous-Paleogene mass extinction. Previous workers have hypothesized that taeniodonts can be divided into(More)
Palaechthonid plesiadapiforms from the Palaeocene of western North America have long been recognized as among the oldest and most primitive euarchontan mammals, a group that includes extant primates, colugos and treeshrews. Despite their relatively sparse fossil record, palaechthonids have played an important role in discussions surrounding adaptive(More)
We carried out a series of experiments to test the hypothesis that many examples of gastric cytoprotection result from the ability of protective agents to elevate mucosal secretion. Specifically, such protection would be effective against barrier breakers that act directly on the mucosal surface. We have previously observed that the protection found to(More)