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.