Supravital Staining of Mammalian Brain with Intraarterial Methylene Blue Followed by Pressurized Oxygen

In 25-day-old rats, injected intraperitoneally with 0.2 ml aliquots of 6% methylene blue in saline over 1 hr followed by a single 4-6 ml intra-arterial injection; O₂ pressurized to 45 lb/in² was used to improve reblueing of 1.5-2 mm slices of cerebellum, thus increasing staining selectivity. Factors believed to influence this selectivity for axonal elements and fine dendrites are the rapidity and pressure (about 300 mm Hg) of the terminal intra-arterial injection, the hyperbaric O₂ treatment of tissue slabs for 1 hr as a substiute for room air, and immersion in 6% ammonium molybdate for 1 hr before return to atmospheric conditions.     

Spontaneous regression of cancer: New insights

Suppression of oncogene expression and of host- or tumour-expressed growth factors and receptors may precipitate spontaneous regression or dormancy in human cancer. Loss of oncogenes necessary for progressive proliferation can lead to differentiation changes. Both natural factors and chemical agents can trigger such a change, and of the naturally occurring agents, growth factors and immunological factors have been most studied. We may find new clues to biological methods of prolonging arrest of cancer, by looking for cytogenetic abnormalities, alterations in oncogene expression and immunocytological composition, in patients showing prolonged dormancy of cancer.     

Landscape correlates of forest plant invasions: A high‐resolution analysis across the eastern United States

Aim

Invasive species occurrence is often related to the anthropogenic context of a given area. Quantifying the effects of roads is of particular interest as roads are a major vector for invasion. Our objective was to further quantify the effects of roads on forest plant invasion through a macroscale, high‐resolution investigation to assist effective invasion control and mitigation.

Location

Eastern United States.

Methods

Using invasive plant data from 23,039 forest inventory plots in 13 ecological provinces, we employed logistic regression to relate the odds of invasion to distance from a road, with adjustments for broadscale differences attributable to ecological provinces, and local scale differences in productivity, forest fragmentation and land use.

Results

The overall proportion (P) of invaded plots was 0.58 (0.65 for plots within 50 m of a road), and the highest odds (P/1 ? P) of invasion were found in relatively more productive, fragmented forest in landscapes with more than 10% agriculture or developed land cover. Wald chi‐square statistics indicated the best predictor of the odds of invasion was ecological province, followed by land use, productivity, forest fragmentation and distance from a road. Depending on the province, the adjusted odds of invasion decreased by up to 23% (typically 4%–10%) per 100 m distance from a road. The adjusted probability of invasion approached zero in only three provinces, for the least productive, least fragmented forest that was at least 2,000 m from a road in landscapes with less than 10% agricultural or developed land cover.

Main conclusions

In the eastern United States, the existence of a nearby road is less important than the landscape context associated with the road. A purely road‐mediated effect has little practical meaning because anthropogenic activities and roads are pervasive and confounded.