Determination of triglyceride in the human myocardium by magnetic resonance spectroscopy: reproducibility and sensitivity of the method
ABSTRACT The primary aim of this investigation was to determine the reliability and sensitivity of 1H magnetic resonance spectroscopy (1H-MRS) as a method for quantifying myocardial triglyceride (TG) content in humans over time and in response to metabolic perturbations. Three separate experiments were designed to quantify myocardial TG content 1) over a 90-day period, 2) after a high-fat meal, and 3) after a 48-h fast. Proton spectra were collected from a 10 x 20 x 30-mm3 voxel placed within the intraventricular septum, with measurements acquired at end-systole and end-expiration, using cardiac triggering and respiratory gating. Minimal variation was observed between myocardial TG content determined 90 days apart (r = 0.98, CV = 5%), whereas TG values were unaffected by a high-fat meal despite a significant twofold increase (P < 0.05) in serum TG. In contrast, myocardial TG content increased threefold (P < 0.05) after a 48-h fast despite a 25% reduction in serum TG. Body mass index was significantly related to myocardial TG (r = 0.58, P < 0.05) and the change in myocardial TG after a 48-h fast (r2 = 0.60). 1H-MRS is a reliable method for the determination of myocardial TG in humans and is relatively unaffected by the consumption of one high-fat meal but sensitive to changes following a prolonged fast.
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ABSTRACT: Endocrinologists are encountering patients with obesity-related complications such as metabolic syndrome (MetS) and type 2 diabetes mellitus (T2DM) on a daily basis. Nonalcoholic fatty liver disease (NAFLD) is a liver condition characterized by insulin resistance, hepatic steatosis and frequently T2DM. This is now the most common chronic liver condition in adults and is present in the majority of obese subjects. Liver fat accumulation may range from simple steatosis to severe steatohepatitis with hepatocyte necroinflammation (or nonalcoholic steatohepatitis [NASH]). Although the natural history is incompletely understood, NAFLD may lead to serious medical consequences ranging from cirrhosis and hepatocellular carcinoma to earlier onset of T2DM and cardiovascular disease (CVD). The diagnosis of NAFLD may be challenging because signs and symptoms are frequently absent or nonspecific, and thus easily missed. Liver aminotransferases may be helpful if elevated, but most times are normal in the presence of the disease. Liver imaging may assist in the diagnosis (ultrasound or MRI and spectroscopy) but a definitive diagnosis of NASH still requires a liver biopsy. This may change in the near future as novel biomarkers become available. Treatment of NAFLD includes aggressive management of associated cardiovascular risk factors and many times control of T2DM. Pioglitazone and vitamin E appear promising for patients with NASH, although long-term studies are unavailable. In summary, this review hopes to address the common clinical dilemmas that endocrinologists face in the diagnosis and management of NAFLD and increase awareness of a potentially serious medical condition.Therapeutic advances in endocrinology and metabolism 10/2011; 2(5):211-25. DOI:10.1177/2042018811419157
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ABSTRACT: Aging is associated with progressive changes in total and regional fat distribution that have negative health consequences. Indeed, a preferential increase in abdominal fat, in particular visceral fat, combined with a decrease in lower body subcutaneous fat are commonly cited in the literature. These age-related changes in body composition can occur independent of changes in total adiposity, body weight or waist circumference, and represent a phenotype closely associated with increased morbidity and mortality risk. Tissues such as the heart, liver and skeletal muscle in the elderly have increased fat deposition, which increases risk for insulin resistance and cardiovascular disease. Furthermore, aging is associated with increased fat content within bone marrow, which exposes the elderly to fracture risk beyond that associated with low bone mineral density alone. Many of the age-associated body compositional changes cannot be detected by simple anthropometric measures alone, and the influence of gender, race or ethnicity, and physical activity patterns on these changes is unclear. This review will explore some of these age-related changes in total and regional fat distribution. Consideration will also be given to the strengths and limitations associated with some of the anthropometric methodologies employed for assessing these changes.Ageing research reviews 08/2009; 8(4):339-48. DOI:10.1016/j.arr.2009.06.001 · 7.63 Impact Factor
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ABSTRACT: It is well known that a stacked microstrip antenna enables the construction of a broadband planar antenna. A coplanar waveguide (CPW) is also used as an efficient feeding system for a microstrip antenna (MSA), since it enables the realization of series and shunt connections of active devices without through-holes. For this reason, a stacked microstrip antenna fed by a coplanar waveguide with dogbone slot (stacked CPW-MSA) is proposed, and its design technique and radiation properties are presented. Various experiments were carried out in the C-band to estimate the performance of the antenna. A broadband bandwidth of 21% (VSWR ⩾ 2.0) was achieved using the antenna. The simulated results obtained from the IE3D simulator agreed well with the experimental results. Therefore, this type of stacked CPW-MSA is considered to be an effective model for a broadband planar antennaAntennas and Propagation Society International Symposium, 2001. IEEE; 02/2001