Detecting metabolic differences in fetal and adult sheep adipose and skeletal muscle tissues

The primary metabolic pathway required to produce ATP differs as a result of tissue type, developmental stage and substrate availability. We utilized molecular and histological techniques to define the metabolic status in foetal and adult, adipose and skeletal muscle tissues. Redox ratios of these tissues were also determined optically by two‐photon microscopy. Adult perirenal adipose tissue had a higher optical redox ratio than fetal perirenal adipose tissue, which aligned with glycolysis being used for ATP production; whereas adult skeletal muscle had a lower optical redox ratio than fetal skeletal muscle, which aligned with oxygen demanding oxidative phosphorylation activity being utilized for ATP production. We have compared traditional molecular and microscopy techniques of metabolic tissue characterization with optical redox ratios to provide a more comprehensive report on the dynamics of tissue metabolism.     

A computer model of temperature distribution inside a lossy sphere after microwave radiation

The temperature distribution inside a lossy sphere resulting from the absorption of microwave energy was approximated by successive numerical iterations, of the thermal energy equation. Heat transfer within the sphere by conduction was considered. In the model energy was not dissipated by convection but was contained in the sphere for over 200 seconds. Exposure of a 5-cm sphere to 3,000 MHz at 30 mW/cm² for 200 seconds was calculated to produce a temperature rise of 0.56°C near the front surface.     

Phosphate transport processes in eukaryotic cells

Conclusion Much more work has been done on P_i transport processes, even in the last five years, than we have been able to mention in the space available. We have restricted our discussion to studies on mechanisms of transport or transport regulation, identification of transport proteins and their essential amino acids, and isolation, purification, and reconstitution of P_i transport systems. Many valuable studies on the physiology of P_i transport and its regulation and P_i transport in nonepithelial cells have also been conducted. Transport of P_i into and out of organelles other than the mitochondrion is gaining well-deserved attention, as are transport processes in fungi and plants. It is hoped that in another five years many P_i transport processes will be understood in true molecular terms and that this will increase our knowledge of cellular bioenergetics and metabolism.     

In utero substrate restriction by placental insufficiency or maternal undernutrition decreases optical redox ratio in foetal perirenal fat

Intrauterine growth restriction (IUGR) can result from reduced delivery of substrates, including oxygen and glucose, during pregnancy and may be caused by either placental insufficiency or maternal undernutrition. As a consequence of IUGR, there is altered programming of adipose tissue and this can be associated with metabolic diseases later in life. We have utilised two sheep models of IUGR, placental restriction and late gestation undernutrition, to determine the metabolic effects of growth restriction on foetal perirenal adipose tissue (PAT). Two-photon microscopy was employed to obtain an optical redox ratio, which gives an indication of cell metabolism. PAT of IUGR foetuses exhibited higher metabolic activity, altered lipid droplet morphology, upregulation of cytochrome c oxidase subunit genes and decreased expression of genes involved in growth and differentiation. Our results indicate that there are adaptations in PAT of IUGR foetuses that might be protective and ensure survival in response to an IUGR insult.