Biomedical subjects

E Louise Thomas

Publications and source records attributed to E Louise Thomas.

10 recordsLinked to original sources

PubMed2006

Effect of nutritional counselling on hepatic, muscle and adipose tissue fat content and distribution in non-alcoholic fatty liver disease.

AIM: To assess the effectiveness of the current UK clinical practice in reducing hepatic fat (IHCL). METHODS: Whole body MRI and (1)H MRS were obtained, before and after 6 mo nutritional counselling, from liver, soleus and tibialis muscles in 10 subjects with non-alcoholic fatty liver disease (NAFLD). RESULTS: A 500 Kcal-restricted diet resulted in an average weight loss of 4% (-3.4 kg,) accompanied by significant reductions in most adipose tissue (AT) depots, including subcutaneous (-9.9%), abdominal subcutaneous (-10.2%) and intra-abdominal-AT (-11.4%). Intramyocellular lipids (IMCL) were significantly reduced in the tibialis muscle (-28.2%). Decreases in both IHCL (-39.9%) and soleus IMCL (-12.2%) content were also observed, although these were not significant. Several individuals showed dramatic decreases in IHCL, while others paradoxically showed increases in IHCL content. Changes in body composition were accompanied by improvements in certain liver function tests: serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT). Significant correlations were found between decreases in IHCL and reductions in both intra-abdominal and abdominal subcutaneous AT. Improvements in liver function tests were associated with reductions in intra-abdominal AT, but not with changes in IHCL. CONCLUSION: This study shows that even a very modest reduction in body weight achieved through lifestyle modification can result in changes in body fat depots and improvements in LFTs.

Adipose Tissue, White↗

PubMed2006

Determinants of adiposity during preweaning postnatal growth in appropriately grown and growth-restricted term infants.

The distribution and quantity of adipose tissue are markers of morbidity risk in children and adults. Poor intrauterine growth and accelerated postnatal growth are believed to add to these risks. The aim of this study was to assess adipose tissue content and distribution at birth and 6 wk in relation to intrauterine growth restriction, postnatal growth, and infant diet. We measured weight, length, and head circumference and adipose content and distribution using magnetic resonance imaging at 6 wk of age in appropriately grown for gestational age (AGA) and growth-restricted (GR) infants and compared this with birth data. By 6 wk, GR infants showed complete catch-up in comparison to AGA infants in relation to head growth and adiposity. Catch-up in length and weight was not complete. Accelerated linear growth, but not accelerated weight gain, was associated with a highly significant increase in adiposity (r = 0.57, p = 0.001) regardless of AGA/GR status. The highest adiposity at 6 wk, allowing for baseline variables and linear growth, was seen in exclusively breast-fed GR infants (mean, 95% confidence interval: 33.5%, 29.51-37.5). Adipose tissue distribution remained constant and was unrelated to growth and diet. Reduced birth adiposity (B = -0.185, p = 0.003), but not low birth head size (B = 0.32, p = 0.093), was a significant predictor of accelerated postnatal head growth (R(2) = 0.29, adjusted R(2) = 0.23, p = 0.012). Increasing adiposity appears to be an inevitable accompaniment of accelerated linear growth. Low total adipose tissue quantity at birth appears to direct nutrition toward head growth. Adipose tissue may be involved in the signaling of catch-up growth.

Adipose Tissue↗

PubMed2006

Critical role for peptide YY in protein-mediated satiation and body-weight regulation.

Dietary protein enhances satiety and promotes weight loss, but the mechanisms by which appetite is affected remain unclear. We investigated the role of gut hormones, key regulators of ingestive behavior, in mediating the satiating effects of different macronutrients. In normal-weight and obese human subjects, high-protein intake induced the greatest release of the anorectic hormone peptide YY (PYY) and the most pronounced satiety. Long-term augmentation of dietary protein in mice increased plasma PYY levels, decreased food intake, and reduced adiposity. To directly determine the role of PYY in mediating the satiating effects of protein, we generated Pyy null mice, which were selectively resistant to the satiating and weight-reducing effects of protein and developed marked obesity that was reversed by exogenous PYY treatment. Our findings suggest that modulating the release of endogenous satiety factors, such as PYY, through alteration of specific diet constituents could provide a rational therapy for obesity.

Animals↗

PubMed2005

Excess visceral and hepatic adipose tissue in Turner syndrome determined by magnetic resonance imaging: estrogen deficiency associated with hepatic adipose content.

Obesity, predominantly centrally distributed, is common in women with Turner syndrome (TS) and is thought to contribute to the increased risk of atherosclerosis; however, insulin concentrations are unexpectedly low. To explore this discrepancy, we assessed fat content and distribution by magnetic resonance imaging (MRI) and bioelectrical impedance (BI). Six nondiabetic, estrogen-treated women with TS were compared with six age-matched normal controls of similar body mass index. Clinical history, anthropometric measurements, biochemical markers, and MRI and BI measures of adiposity were assessed. TS women had increased intrahepatocellular lipids (IHCL) on MRI. After height adjustment, they also had an excess of total and visceral compared with sc adipose tissue (AT) than controls, without elevated insulin concentrations. BI and MRI measures correlated strongly for total and sc, but not visceral, AT in TS. IHCL was associated with cumulative estrogen-deficient years (r = 0.928; P = 0.008). Women with TS depart from the classical picture of metabolic syndrome despite an excess of total and visceral AT on MRI. Elevated IHCL in TS is associated with estrogen deficiency. BI may be useful to estimate total body fat, but does not reliably localize fat depots in TS.

Adipose Tissue↗

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

Elevated fasting plasma ghrelin in prader-willi syndrome adults is not solely explained by their reduced visceral adiposity and insulin resistance.

Plasma ghrelin is elevated in Prader-Willi syndrome (PWS). This might contribute to obesity or GH deficiency in such patients. Visceral adiposity and insulin resistance are reduced in PWS, which might lead to hyperghrelinemia. We measured fasting plasma ghrelin in control female (n = 39), PWS female (n = 12), and PWS male (n = 6) adults. In controls and PWS, ghrelin was negatively correlated with visceral adiposity, fasting insulin, and homeostasis model insulin resistance index. There was no significant correlation with serum IGF-I in PWS. In stepwise linear regression, visceral adiposity (P < 0.02) had a stronger inverse correlation with ghrelin than sc fat depots in controls and PWS, possibly through hyperinsulinemia, as the correlations with insulin resistance were even stronger (P < 0.01). PWS females had significantly (P < 0.001) elevated ghrelin (mean +/- SD, 661 +/- 360 pg/ml), compared with both nonobese (363 +/- 163) and obese (191 +/- 66) controls. Ghrelin was increased 3.4- to 3.6-fold in PWS females adjusting for total adiposity, 3.2- to 3.4-fold adjusting for visceral adiposity, and 3.0-fold adjusting for insulin resistance. Fasting plasma glucagon-like peptide-1 was normal in PWS females. The hyperghrelinemia in PWS adults is therefore not solely explained by their reduced visceral adiposity and relative hypoinsulinemia. Its cause and consequences await further elucidation.

Adipose Tissue↗

PubMed2003

Carbohydrate-induced manipulation of insulin sensitivity independently of intramyocellular lipids.

Subjects with insulin resistance have been shown to have higher storage levels of intramyocellular lipid (IMCL) than their insulin-sensitive counterparts. It has been proposed that elevated IMCL stores may be the main cause of insulin resistance. The aim of the present study was to ascertain whether there is a causal relationship between IMCL storage and insulin resistance. IMCL storage was assessed using magnetic resonance spectroscopy and insulin sensitivity was assessed by performing an oral glucose tolerance test. A 4-week intervention of reduction of dietary glycaemic index was used to manipulate insulin sensitivity in a cohort of healthy volunteers; the effects of this intervention on IMCL were measured after 4 weeks of intervention. Significant improvements in the insulin sensitivity index occurred following the dietary intervention (baseline 7.8 (sem 1.11) v. post-intervention 9.7 (sem 1.11), P=0.02). However, there were no changes in IMCL storage levels, suggesting that insulin sensitivity can be manipulated independently of IMCL. This suggests that in healthy volunteers, insulin sensitivity is independent of IMCL storage and the high storage levels that have been found in insulin-resistant subjects may occur as a consequence rather than a cause of insulin resistance.

Adult↗

PubMed2003

Human metabolic syndrome resulting from dominant-negative mutations in the nuclear receptor peroxisome proliferator-activated receptor-gamma.

We previously reported a syndrome of severe hyperinsulinemia and early-onset hypertension in three patients with dominant-negative mutations in the nuclear hormone receptor peroxisome proliferator-activated receptor (PPAR)-gamma. We now report the results of further detailed pathophysiological evaluation of these subjects, the identification of affected prepubertal children within one of the original families, and the effects of thiazolidinedione therapy in two subjects. These studies 1) definitively demonstrate the presence of severe peripheral and hepatic insulin resistance in the affected subjects; 2) describe a stereotyped pattern of partial lipodystrophy associated with all the features of the metabolic syndrome and nonalcoholic steatohepatitis; 3) document abnormalities in the in vivo function of remaining adipose tissue, including the inability of subcutaneous abdominal adipose tissue to trap and store free fatty acids postprandially and the presence of very low circulating levels of adiponectin; 4) document the presence of severe hyperinsulinemia in prepubertal carriers of the proline-467-leucine (P467L) PPAR-gamma mutation; 5) provide the first direct evidence of cellular resistance to PPAR-gamma agonists in mononuclear cells derived from the patients; and 6) report on the metabolic response to thiazolidinedione therapy in two affected subjects. Although the condition is rare, the study of humans with dominant-negative mutations in PPAR-gamma can provide important insight into the roles of this nuclear receptor in human metabolism.

Abdomen↗

PubMed2002

Digenic inheritance of severe insulin resistance in a human pedigree.

Impaired insulin action is a key feature of type 2 diabetes and is also found, to a more extreme degree, in familial syndromes of insulin resistance. Although inherited susceptibility to insulin resistance may involve the interplay of several genetic loci, no clear examples of interactions among genes have yet been reported. Here we describe a family in which five individuals with severe insulin resistance, but no unaffected family members, were doubly [corrected] heterozygous with respect to frameshift/premature stop mutations in two unlinked genes, PPARG and PPP1R3A these encode peroxisome proliferator activated receptor gamma, which is highly expressed in adipocytes, and protein phosphatase 1, regulatory subunit 3, the muscle-specific regulatory subunit of protein phosphatase 1, which are centrally involved in the regulation of carbohydrate and lipid metabolism, respectively. That mutant molecules primarily involved in either carbohydrate or lipid metabolism can combine to produce a phenotype of extreme insulin resistance provides a model of interactions among genes that may underlie common human metabolic disorders such as type 2 diabetes.

Adult↗

PubMed2002

Resting metabolic rate, plasma leptin concentrations, leptin receptor expression, and adipose tissue measured by whole-body magnetic resonance imaging in women with Prader-Willi syndrome.

BACKGROUND: Obesity in Prader-Willi syndrome (PWS) may be related to abnormalities in the adipocyte-leptin-hypothalamic pathway and may be exacerbated by reductions in the resting metabolic rate (RMR). OBJECTIVE: We compared body composition, body-composition- adjusted RMR, and adiposity-adjusted plasma leptin between women with PWS and control women. We also examined leptin receptor expression in the PWS group. DESIGN: We studied body composition using whole-body magnetic resonance imaging and measured plasma leptin by radioimmunoassay in 45 control women aged 18-56 y and in 13 women with PWS aged 20-38 y. RMR was measured by indirect calorimetry in 41 control women and in 8 women with PWS. Age, body composition, and regional adipose tissue (AT) depots were corrected for by multiple regression analysis. Messenger RNA expression of the leptin receptor was examined by reverse transcriptase-polymerase chain reaction in lymphocytes. RESULTS: In the PWS group, fat mass was greater after correction for fat-free mass, and RMR was normal after correction for both fat-free mass and fat mass. Leptin was influenced primarily by subcutaneous AT volume in both subject groups. Leptin concentrations were not significantly different between the 2 groups after adjustment for age and AT content or distribution. Full-length leptin receptor messenger RNA was expressed in the lymphocytes of the PWS group. CONCLUSIONS: Differences in RMR in women with PWS are explained by abnormal body composition, suggesting that energy expenditure is normal at the tissue level in PWS. There is no evidence that defective leptin production causes obesity in PWS, and leptin receptor deficiency is not a primary consequence of the gene defects leading to leptin resistance.

Adipose Tissue↗