Aldehyde dehydrogenase activity selects for the holoclone phenotype in prostate cancer cells.

Aldehyde dehydrogenase 1 (ALDH) activity is considered to be a marker of cancer stem cells (CSCs) in many tumour models, since these cells are more proliferative and tumourigenic than ALDH(Lo) cells in experimental models. However it is unclear whether all CSC-like cells are within the ALDH(Hi) population, or whether all ALDH(Hi) cells are highly proliferative and tumourigenic. The ability to establish a stem cell hierarchy in vitro, whereby sub-populations of cells have differing proliferative and differentiation capacities, is an alternate indication of the presence of stem cell-like populations within cell lines. In this study, we have examined the interaction between ALDH status and the ability to establish a stem cell hierarchy in PC3 prostate cancer cells. We demonstrate that PC3 cells contain a stem cell hierarchy, and isolation of ALDH(Hi) cells enriches for the most primitive holoclone population, however holoclone formation is not restricted to ALDH(Hi) cells. In addition, we show that ALDH activity undergoes phenotypic plasticity, since the ALDH(Lo) population can develop ALDH(Hi) populations comparable to parental cells within 2 weeks in culture. Furthermore, we show that the majority of ALDH(Hi) cells are found within the least primitive paraclone population, which is circumvented by culturing PC3 cells as spheroids in defined medium favouring stem cell characteristics. Although ALDH(Hi) status enriches for holoclone formation, this activity may be mediated by a minority of ALDH(Hi) cells.

Using ESEM and SEM to compare the performance of dentin conditioners.

A comparison of four dentinal conditioners was performed utilizing a traditional scanning electron microscope (SEM) and a new technology, the ElectroScan environmental scanning electron microscope (ESEM). Both ESEM and SEM analysis verified current theorized mechanisms of adhesion to dentin surfaces. ESEM images appeared to more closely approximate what one would expect cut and treated dentin surfaces look like. Increases in information from the "surfaces" of uncoated specimens and the reduction in specimen preparation time were associated with ESEM analysis.

Toxicity of aerosol propellants in the respiratory and circulatory systems. VI. Influence of cardiac and pulmonary vascular lesions in the rat.

Three propellants were selected for investigation in rats because of their non-uniform effect in mice and monkeys. Trichlorofluoromethane (FC 11) provoked arrhythmia in all three animal species, dichlorodifluoromethane (FC 12) in monkeys and rats but not in mice, and difluoroethane (FC 152a) only in rats. In rats the alterations in heart rate and electrocardiographic pattern during inhalation of these propellants are largely brought about by release of catecholamines from the adrenal gland, because adrenalectomy or prior injection of beta-adrenergic blocking drugs decreased the incidence of cardiac effects. Rats that have pulmonary vascular thrombosis or cardiac necrosis become more sensitive to proarrhythmic activity of these propellants.