Oral cytology in cannabis smokers.

The effects of cannabis/methaqualone/tobacco smoking on the epithelial cells of the tongue, buccal mucosa and floor of the mouth were examined. Oral mucosal smears for detection of cellular changes were taken from 4 sites in 16 patients. The tongue blade scraping technique was used. The sites sampled included the buccal mucosa (left and right sides), the posterior dorsum of the tongue and the anterior floor of the mouth. Tobacco smoking and non-smoking controls were also examined. The only significant difference between cannabis users and controls was the greater prevalence of bacterial cells in the smears taken from cannabis users. However, there were also greater numbers of degenerate and atypical squamous cells in cannabis smokers than in cigarette-smoking and non-smoking controls. Epithelial cells in smears taken from cannabis users and tobacco-smoking controls also showed koilocytic changes, which were not seen in smears taken from non-smoking controls. Koilocytosis is indicative of human papilloma virus infection, although no apparent lesions were seen in the patients from whom smears had been taken. It would appear that there is a greater tendency towards damaged and immature surface epithelial cells in cannabis smokers.Articl

Eroding abodes and vanished bridges: historical biogeography of the substrate specialist pebble-mound mice (Pseudomys).

Aim: To determine whether the pronounced ecological importance of pebble mounds to pebble-mound mice (Pseudomys) is manifest in their continental biogeography.\ud \ud Location: Northern Australia.\ud \ud Methods: A GIS-based comparison was made between the habitats contained within the potential climatic distributions of mice, representing a null hypothesis of no habitat selection, and their actual distributions based on all known location records.\ud \ud Results: All species had a clear preference for hilly, rocky landscapes with a surficial cover dominated by bedrock. Simple vegetation communities with relatively open eucalypt overstorey and grassy understorey were preferred. Highly degraded rocks and aggradational surfaces and plains were avoided. The extent of the summer monsoon may be important in determining the southern limits of the group's distribution. Major disjunctions between species were attributable to the presence of clay plains and sand sheets.\ud The behavioural requirement of pebble-mound mice for mounds determines their population distribution pattern and the distribution of the different species within the genus.\ud \ud Main conclusions: The behavioural need for pebble mounds drives the distributional pattern of populations and species of pebble-mound mice. The initial spread of pebble-mound mice probably occurred during the late Pliocene or earliest Pleistocene. There has predominantly been degradation of the potential distribution of the group since that time due to the stability of Australian landscapes and Pleistocene planation and sand sheet development over large areas of northern Australia. This process is ongoing, and past regions of rocky contact between current distributions have disappeared, while the distributional limits of several species are steadily being reduced by erosion of hills and the spread of dune fields