Biomedical subjects

Jimmy Bell

Publications and source records attributed to Jimmy Bell.

4 recordsLinked to original sources

PubMed2006

MAGfect: a novel liposome formulation for MRI labelling and visualization of cells.

Cellular entry of imaging probes, such as contrast agents for magnetic resonance imaging (MRI), is a key requirement for many molecular imaging studies, particularly imaging intracellular events and cell tracking. Here, we describe the successful development and in vitro analysis of MAGfect, a novel liposome formulation containing a lipidic gadolinium contrast agent for MRI, Gd-DOTA-Chol , designed to enter and label cells. Liposome formulation and cell incubation time were optimised for maximum cellular uptake of the imaging probe in a variety of cell lines. MRI analysis of cells incubated with MAGfect showed them to be highly MRI active. This formulation was examined further for cytotoxicity, cell viability and mechanism of cell labelling. One of the key advantages of using MAGfect as a labelling vehicle arises from its potential for additional functions, such as concomitant drug or gene delivery and fluorescent labelling. The gadolinium liposome was found to be an effective vehicle for transport of plasmid DNA (pDNA) into cells and expression levels were comparable to the commercial transfection agent Trojene.

Cells↗

PubMed2004

Altered adiposity after extremely preterm birth.

The quantity and distribution of adipose tissue are markers of morbidity risk. The third trimester of human development is a period of rapid adipose tissue deposition. Preterm infants may be at risk of altered adiposity. We measured anthropometric indices and quantified total, subcutaneous, and intraabdominal adipose tissue volumes using whole-body magnetic resonance adipose tissue imaging in 38 infants born at <32 wk gestational age, when they reached term, and 29 term-born infants. The preterm infants at term were significantly lighter and shorter than the term-born infants, but there was no significant difference in head circumference SD score or total adiposity. The preterm infants had a highly significant decrease in subcutaneous adipose tissue and significantly increased intraabdominal adipose tissue. Accelerated postnatal weight gain was accompanied by increased total and subcutaneous adiposity. Illness severity was the principal determinant of increased intraabdominal adiposity. Our data provide evidence of causal pathways linking accelerated postnatal growth with increased total and subcutaneous adiposity, and illness severity with altered adipose tissue partitioning. We suggest that these observations may in part explain the associations between small size at birth and later disease. Preterm infants may be at risk in later life of metabolic complications through increased and aberrant adiposity.

Adipose Tissue↗

PubMed2004

Nuclear receptor corepressor RIP140 regulates fat accumulation.

Nuclear receptors and their coactivators have been shown to function as key regulators of adipose tissue biology. Here we show that a ligand-dependent transcriptional repressor for nuclear receptors plays a crucial role in regulating the balance between energy storage and energy expenditure. Mice devoid of the corepressor protein RIP140 are lean, show resistance to high-fat diet-induced obesity and hepatic steatosis, and have increased oxygen consumption. Although the process of adipogenesis is unaffected, expression of certain lipogenic enzymes is reduced. In contrast, genes involved in energy dissipation and mitochondrial uncoupling, including uncoupling protein 1, are markedly increased. Therefore, the maintenance of energy homeostasis requires the action of a transcriptional repressor in white adipose tissue, and ligand-dependent recruitment of RIP140 to nuclear receptors may provide a therapeutic target in the treatment of obesity and related disorders.

Adaptor Proteins, Signal Transducing↗

PubMed2004

Adipose tissue magnetic resonance imaging in the newborn.

Infancy is a period of rapid adipose tissue accumulation, and influences during early development are plausible determinants of altered adiposity. The distribution, as well as the quantity of adipose tissue, is a marker of health and disease. Previous methods for the assessment of body composition in infants have been indirect and thus unable to determine adipose quantity reliably, nor assess adipose tissue distribution. Adipose tissue magnetic resonance imaging is direct, non-invasive, radiation free and suitable for serial examinations in infancy. Adipose tissue depots are quantified individually and summated to provide an accurate measure of depot-specific and total adiposity. We have adapted this technique for application to newborns and, to date, have imaged over 100 term and preterm infants.

Adipose Tissue↗