clinicaltrials.gov Identifier: NCT00520858.

OBJECTIVE -The primary objective was to examine whether the combination of diet and aerobic exercise (DA) or diet and resistance exercise (DR) is associated with greater improvements in metabolic risk factors by comparison to diet only (DO) in obese women. A second objective considered whether reductions in metabolic risk factors are related to concurrent changes in abdominal and/or intermuscular fat distribution. RESEARCH DESIGN AND METHODS-A total of 38 premenopausal obese women were randomly assigned to one of three 16-week treatments: DO (n ϭ 13), DA (n ϭ 11), or DR (n ϭ 14). Plasma glucose, insulin, and lipid levels were measured in a fasting state and after a 75-g oral glucose challenge (oral glucose tolerance test [OGTT]). Total, abdominal subcutaneous, visceral, and intermuscular fat were measured by magnetic resonance imaging.RESULTS -Significant reductions (P Ͻ 0.02) in body weight (ϳ10 kg or 10%) and in total, abdominal subcutaneous, visceral, and intermuscular fat were observed within each group. Fasting and OGTT insulin, total cholesterol, LDL cholesterol, and apolipoprotein B also decreased within each group (P Յ 0.02). The changes in the body fat and metabolic variables were not different across treatment (P Ͼ 0.05). Visceral fat alone was related to the metabolic risk factors both before and after the treatment.CONCLUSIONS -Weight loss was associated with reductions in metabolic risk factors in obese women. The improvement in the metabolic profile was not enhanced by the addition of aerobic or resistance exercise. The findings reinforce the importance of diminished visceral fat in the treatment of insulin resistance. Diabetes Care 25:431-438, 2002T he prevalence of obesity and associated comorbidities is increasing (1,2), which underscores the importance of developing effective strategies for reducing obesity and the risk of metabolic disease in women. Diet-induced weight loss (3-5) as well as aerobic exercise (6 -8) and resistance exercise (7-9) are effective treatments for reducing metabolic risk factors in women. Although these observations suggest that the combination of diet and exercise would have a greater effect on metabolic risk factors than weight loss alone, the influence of diet and exercise combined in women is unclear. Whereas some studies report greater improvements in the plasma lipid profile in response to the combination of diet and exercise than diet alone (10 -12), others report no treatment differences (13-15). It is also reported that the addition of aerobic (16,17) or resistance (16) exercise does not enhance the reductions in plasma insulin and glucose levels in comparison to diet alone in obese women. These observations do not reflect those in a recent report in obese men wherein a twofold greater improvement in insulin action was observed in response to diet combined with aerobic or resistance exercise than diet alone (18). A rationale that explains the equivocal findings is unknown; however, taken together, these observations suggest that the utility of exercise to enha...

1,2), specifically the exchange between bulk water protons and water protons bound to the agent, or amide protons in the agent (3-16). Paramagnetic CEST (PARAC-EST) agents have many possible medical and biological applications (6,8 -15), including the measurement of tissue pH based on the pH dependence of the exchange rate of amide protons with bulk water protons (2,3,10,11,13), the measurement of tissue temperature using the linear dependence of the bound-water chemical shift on temperature (9,15), the measurement of enzymatic activity (8), protein targeting (16), and metabolite detection (6,12). The proton exchange processes between the bound water and/or amide protons of PARACEST agents and bulk water in solution have been thoroughly modeled by Woessner et al. (17) based on the modified Bloch equations with exchange terms using a two-or three-pool model. By fitting experimental CEST spectra to this model, the exchange rate between bulk water and bound water and/or amide protons, and the bound water chemical shift can be estimated. However, several additional factors can modulate the contrast obtained with PARACEST agents in vivo, including the magnetic field homogeneity, the asymmetry of the free water proton signal, radiation damping, and macromolecule magnetization transfer (MT) effects. The macromolecule MT effect in particular has a significant impact on contrast-to-noise ratios (CNRs) in biological systems and was not considered in the model proposed by Woessner et al. (17), limiting the applicability of the model in vivo.The macromolecule component of the biological system is a semisolid component with a very fast (Ͻ1 ms) T 2 relaxation time constant (18), which makes this component difficult to detect by conventional imaging methods. However, the T 2 of macromolecular protons can be estimated by fitting the Z-spectrum from the biological system to theoretical models (19,20). In addition, coupling (crossrelaxation or chemical exchange) between macromolecular protons and bulk water protons enables the transfer of saturation between pools (18). Therefore, selective saturation of the macromolecular protons can be observed by the effect on bulk water protons (21) and depends on the T 1 time constants of each pool along with the rate of MT between the pools.The MT effect can be exploited in vivo to observe the interaction between protons bound to macromolecules

The purpose of this investigation was to examine the effect of caffeine (an adenosine receptor antagonist) on whole-body insulin-mediated glucose disposal in resting humans. We hypothesized that glucose disposal would be lower after the administration of caffeine compared with placebo. Healthy, lean, sedentary (n ‫؍‬ 9) men underwent two trial sessions, one after caffeine administration (5 mg/kg body wt) and one after placebo administration (dextrose) in a double-blind randomized design. Glucose disposal was assessed using a hyperinsulinemic-euglycemic clamp. Before the clamp, there were no differences in circulating levels of methylxanthines, catecholamines, or glucose. Euglycemia was maintained throughout the clamp with no difference in plasma glucose concentrations between trials. The insulin concentrations were also similar in the caffeine and placebo trials. After caffeine administration, glucose disposal was 6.38 ؎ 0.76 mg/kg body wt compared with 8.42 ؎ 0.63 mg/kg body wt after the placebo trial. This represents a significant (P < 0.05) decrease (24%) in glucose disposal after caffeine ingestion. In addition, carbohydrate storage was 35% lower (P < 0.05) in the caffeine trial than in the placebo trial. Furthermore, even when the difference in glucose disposal was normalized between the trials, there was a 23% difference in the amount of carbohydrate stored after caffeine administration compared with placebo administration. Caffeine ingestion also resulted in higher plasma epinephrine levels than placebo ingestion (P < 0.05). These data support our hypothesis that caffeine ingestion decreases glucose disposal and suggests that adenosine plays a role in regulating glucose disposal in resting humans.

Weight loss induced by diet and aerobic or resistance exercise has similar positive effects on lowering fasting and OGTT insulin values that are greater than those with diet alone. Because changes in glucose and insulin were related to reductions in visceral and abdominal subcutaneous AT, we conclude that reduction in abdominal obesity consequent to diet and exercise-induced weight loss is important for attaining improvements in plasma insulin levels, observations that strengthen the concept that abdominal obesity has an important role in mediating insulin resistance.

Single-stranded deoxyribonucleic acid (ssDNA) thymidylic acid icosanucleotides (dT20) were synthesized on the surfaces of derivatized quartz optical fibers to create an optical DNA biosensor. The synthesis made use of an automated solid-phase synthesizer and phosphoramidite synthons. The covalently immobilized oligomers were found to hybridize with complementary ssDNA (cDNA) or ssRNA (cRNA) from solution, and the device was regenerable for multiple cycles of application. Hybridization on optical fibers was detected by the use of the fluorescent DNA stain ethidium bromide (EB). The procedure used hybridization assay techniques and provided a detection limit of 86 ng x mL(-1) cDNA and a sensitivity of 200% fluorescence intensity increase per 100 ng x mL(-1) of cDNA, with one cycle of hybridization analysis requiring 45 min. The sensor has been observed to be regenerable (minimum of five cycles) and to sustain full activity after prolonged storage times (1 year), harsh washing conditions (sonication), and sterilization (autoclaving). The extent of hybridization between the immobilized and complementary nucleic acid strands was determined by UV absorbance thermal denaturation studies wherein all 20 bases on each strand of the nucleic acid were found to be involved in duplex formation.

A promising approach to increase the specificity of photosensitisers used in photodynamic therapy has been through conjugation to monoclonal antibodies (MAb) directed against tumour-associated antigens. Many of the conjugations performed to date have relied on the activated ester method, which can lead to impure conjugate preparations and antibody crosslinking. Here, we report the development of photosensitiser -MAb conjugates utilising two porphyrin isothiocyanates. The presence of a single reactive isothiocyanate allowed facile conjugation to MAb FSP 77 and 17.1A directed against internalising antigens, and MAb 35A7 that binds to a non-internalising antigen. The photosensitiser -MAb conjugates substituted with 1 -3 mol of photosensitiser were characterised in vitro. No appreciable loss of immunoreactivity was observed and binding specificity was comparable to that of the unconjugated MAb. Substitution with photosensitiser had a minimal effect on antibody biodistribution in vivo for the majority of the conjugates, although a decreased serum half-life was observed using a cationic photosensitiser at the higher loading ratios. Tumour-to-normal tissue ratios as high as 33.5 were observed using MAb 35A7 conjugates. The internalising conjugate showed a higher level of phototoxicity as compared with the non-internalising reagent, using a cell line engineered to express both target antigens. These data demonstrate the applicability of the isothiocyanate group for the development of high-quality conjugates, and the use of internalising MAb to significantly increase the photodynamic efficiency of conjugates during photoimmunotherapy.

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