Effect of mild hyperglycemia +/- meta-iodo-benzylguanidine on the radiation response of R3230 Ac tumors.

The effects of glucose or meta-iodo-benzylguanidine (MIBG) on oxygen utilization (QO2) of several tumor cell lines were studied using a Clark-type electrode chamber. For in vivo studies, rats bearing R3230 Ac rat mammary adenocarcinomas were utilized. To evaluate changes in tumor oxygenation induced by glucose or MIBG, intratumoral pO2 and skeletal muscle pO2 were measured using Eppendorf Histography. To find the effect of mild hyperglycemia (i.p., 1 g/kg) +/- MIBG (i.p., 20 mg/kg) on the radiation response, a growth delay assay was used. Glucose alone produced a approximately 20% inhibition of QO2 in several tumor cells we tested except Q7 tumor cells. MIBG inhibited QO2 in R3230 Ac tumors. The median tumor pO2 for glucose + MIBG was increased from 5.3 mm Hg to 13.8 mm Hg. We hypothesized that combined treatment with glucose + MIBG significantly enhanced radiation-induced tumoricidal effects on R3230 Ac tumors, mainly due to reduction in QO2 and increase in tumor pO2

Real-time magnetic resonance imaging and quantification of lipoprotein metabolism in vivo using nanocrystals

Semiconductor quantum dots and superparamagnetic iron oxide nanocrystals have physical properties that are well suited for biomedical imaging. Previously, we have shown that iron oxide nanocrystals embedded within the lipid core of micelles show optimized characteristics for quantitative imaging. Here, we embed quantum dots and superparamagnetic iron oxide nanocrystals in the core of lipoproteins--micelles that transport lipids and other hydrophobic substances in the blood--and show that it is possible to image and quantify the kinetics of lipoprotein metabolism in vivo using fluorescence and dynamic magnetic resonance imaging. The lipoproteins were taken up by liver cells in wild-type mice and displayed defective clearance in knock-out mice lacking a lipoprotein receptor or its ligand, indicating that the nanocrystals did not influence the specificity of the metabolic process. Using this strategy it is possible to study the clearance of lipoproteins in metabolic disorders and to improve the contrast in clinical imaging