Search

Calorie restriction-induced weight loss is accompanied by profound changes in adipose tissue characteristics. To determine the effect of weight loss on differentiation of preadipocytes and secretory capacity of in vitro differentiated adipocytes, we established cultures of these cells from paired subcutaneous adipose tissue biopsies obtained before and at the end of weight-reducing dietary intervention (DI) in 23 obese women. Based on lipid accumulation and the expression of differentiation markers, in vitro adipogenesis increased after weight loss and it was accompanied by enhanced expression of genes involved in de novo lipogenesis. This effect of weight loss was not driven by changes of peroxisome proliferator-activated receptor γ sensitivity to rosiglitazone. Weight loss also enhanced the expression of adiponectin and leptin while reducing that of monocyte chemoattractant protein 1 and interleukin-8 by cultured adipocytes. Thus, the weight-reducing (DI) increased adipogenic capacity of preadipocytes and shifted their secretion toward lower inflammatory profile. Reprogramming of preadipocytes could represent an adaptation to weight loss leading to partial restoration of preobese adipose tissue traits and thus contribute to the improvement of metabolic status. However, enhanced adipogenesis could also contribute to the unwanted weight regain after initial weight loss., Worsening of metabolic health in obesity is associated with the hypertrophy of adipoytes (1). Indeed, the recruitment of new and mall adipocytes improves insulin sensitivity (2). These cells have a [...]

OBJECTIVE--We investigated the regulation of adipose tissue gene expression during different phases of a dietary weight loss program and its relation with insulin sensitivity. RESEARCH DESIGN AND METHODS--Twenty-two obese women followed a dietary intervention program composed of an energy restriction phase with a 4-week very-low-calorie diet and a weight stabilization period composed of a 2-month low-calorie diet followed by 3-4 months of a weight maintenance diet. At each time point, a euglycemic-hyperinsulinemic clamp and subcutaneous adipose tissue biopsies were performed. Adipose tissue gene expression profiling was performed using a DNA microarray in a subgroup of eight women. RT-quantitative PCR was used for determination of mRNA levels of 31 adipose tissue macrophage markers (n = 22). RESULTS--Body weight, fat mass, and C-reactive protein level decreased and glucose disposal rate increased during the dietary intervention program. Transcriptome profiling revealed two main patterns of variations. The first involved 464 mostly adipocyte genes involved in metabolism that were downregulated during energy restriction, upregulated during weight stabilization, and unchanged during the dietary intervention. The second comprised 511 mainly macrophage genes involved in inflammatory pathways that were not changed or upregulated during energy restriction and downregulated during weight stabilization and dietary intervention. Accordingly, macrophage markers were upregulated during energy restriction and downregulated during weight stabilization and dietary intervention. The increase in glucose disposal rates in each dietary phase was associated with variation in expression of sets of 80-110 genes that differed among energy restriction, weight stabilization, and dietary intervention. CONCLUSIONS--Adipose tissue macrophages and adipocytes show distinct patterns of gene regulation and association with insulin sensitivity during the various phases of a dietary weight loss program., Obesityis a major risk factor for diabetes and cardiovascular disease. The excess of fat mass is linked to an impairment of insulin sensitivity through complex multifactorial and still poorly understood [...]

In this work, the low-density Al0.5NbTa0.8Ti1.5V0.2Zr RHEA prepared by mechanical alloying combined with hot uniaxial pressing (HP) was investigated. The alloy was subjected to different sintering temperatures on the range of 1200°C up to 1600°C, while keeping a constant densification time. The influence of the increase in sintering temperatures on the RHEAs’ microstructural features, composition and basic mechanical properties was explored by means of x-ray diffraction and scanning electron microscopy, hardness testing, density determination by Archimedes’ principle and elastic moduli by ultrasonic measurements. Full density samples were obtained in all sintering temperatures. The alloy has shown a homogeneous distribution of phases, with presence of dispersed oxides inside the matrix, leading to a fine grain size distribution due to grain-boundary pinning effect, even during the exposure of the alloy at the highest sintering temperature. The mentioned effect is responsible for the achievement of high-hardness in all conditions. Powder metallurgy has been shown to be an advantageous technique for production of alloys for high-temperature applications, as the inherent in-situ formed oxides homogeneously distributed within the matrix may be beneficially used as reinforcement, thus potentially enhancing the mechanical properties of the parts.