A method for quantitative characterization of growth in the 3-D structure of rat pulmonary arteries

Understanding mechanisms causing pulmonary vascular disease (PVD) frequently requires a thorough understanding of the underlying structural changes in the pulmonary circulation. Animal models have been used extensively to study different forms of PVD but conventional experimental techniques are limited in their ability to allow the study of the whole pulmonary vasculature at once. In this study, we introduce novel techniques of arterial casting, high-resolution imaging and tree analysis to study the pulmonary circulation in rodent models. Male Sprague-Dawley rats were used at 20, 36, 52, 100 and 160 days of age. A technique involving arterial casting with Microfil silicone polymer, high-resolution micro-computed tomography (micro-CT) at 12.5 μm resolution and image data analysis involving segmentation and skeletonization was developed to both qualitatively and quantitatively describe the changes in the pulmonary vasculature with increasing age. Parameters identified to affect the quality of pulmonary arterial casting included polymer flow rate, total injected volume, polymer viscosity and polymerization time. By optimizing these parameters, we successfully created arterial casts of the pulmonary circulation in rats of different ages and demonstrated the feasibility of quantitatively characterizing the changes in the number of vessels with postnatal growth. These preliminary data suggest that the number of vessels with lumen diameters of 50-200 μm increases rapidly in both lungs between 52 and 100 days of age. With this new technique, the pulmonary vasculature can now be studied in a whole lung animal model to better understand the global effects of disease on vascular structure.     

Mandatory Procedures and Fairness in Mental Impairment Hearings

Uncertainty has attended procedures for adjudging unfitness to stand trial in Victoria pursuant to the Crimes (Mental Impairment and Unfitness to be Tried) Act 1997 (Vic) and how “special hearings” should be conducted when a person is determined to be unfit to stand trial but does not wish to pursue the defence of not guilty because of mental impairment. In R v Langley [2008] VSCA 81, (2009) 19 VR 90 the Victorian Court of Appeal clarified the procedures to be employed at jury trials on such matters and quashed a decision not in conformity with proper procedures, making clear that denial of fairness to such accused persons has the potential to result in appealable error.     

Differential effects of PPARgamma agonists on the metabolic properties of gliomas and astrocytes

Recent studies show that thiazolinediones (TZDs), agonists of the peroxisome proliferator-activated receptor gamma (PPARgamma), induce apoptosis in glioma and glioblastoma cells. Here we compared the effects of troglitazone (Trog), a TZD with low affinity for binding to PPARgamma but with potent metabolic effects, on survival and metabolism in GL261 glioma cells versus primary astrocytes. Trog dose-dependently induced cell death in GL261 cells (with over 90% death at 30 microM) but did not cause any toxicity in astrocytes at the same doses. Measurements of glucose and lactate levels after incubation with Trog (30 microM) indicated an overall increase of glucose consumption and lactate production in both cell types. In astrocytes the ratio of lactate produced to glucose utilized was not significantly altered by Trog, while in glioma cells this ratio was decreased by about 40%. Trog dose-dependently reduced mitochondrial membrane potential (DeltaPsi(m)) in both cell types; and the loss of DeltaPsi(m) was greater in the tumor cells (90% loss at 20 microM) than in astrocytes (70% loss at 20 microM). These results suggest that differences in metabolic responses could contribute to the selective resistance of astrocytes to cytotoxic effects of Trog. TZDs such as Trog should therefore be considered for testing in treatment of gliomas.