Subtyping obesity with microarrays: implications for the diagnosis and treatment of obesity.

OBJECTIVE: Obese patients respond differently to weight loss interventions. No efficient diagnostic tool exists to separate obese patients into subtypes as a means to improve prediction of response to interventions. We aimed to separate obese subjects into distinct subgroups using microarray technology to identify gene expression-based subgroups to predict weight loss. DESIGN: A total of 72 obese men and women without family history of diabetes were enrolled in the study; 52 were treated with ephedra and caffeine (E+C) and 20 with placebo for 8 weeks. Adipose and skeletal muscle tissue biopsies were performed at baseline. RNA sample pairs were labeled and hybridized to oligonucleotide microarrays. Quantile normalization and gene shaving were performed, and a clustering algorithm was then applied to cluster subjects based on their gene expression profile. Clusters were visualized using heat maps and related to weight changes. RESULTS: Cluster analysis of gene expression data revealed two distinct subgroups of obesity and predicted weight loss in response to the treatment with E+C. One cluster ('red') decreased to 96.87+/-2.35% body weight, and the second cluster ('green') decreased to 95.59+/-2.75% body weight (P<0.05). 'Red' cluster had less visceral adipose tissue mass (2.77+/-1.08 vs 3.43+/-1.49 kg; P<0.05) and decreased size of the very large fat cells (1.45+/-0.61 vs 2.16+/-1.74 microl; P<0.05) compared to 'green' cluster. Gene expression for both skeletal muscle and adipose tissue was also different between clusters. CONCLUSIONS: Our study provides the first evidence that the combined approach of gene expression profiling and cluster analysis can identify discrete subtypes of obesity, these subtypes have different physiological characteristics and respond differently to an adrenergic weight loss therapy. This brings us that into an era of personalized treatment in the obesity clinic.

Effect of in vitro docosahexaenoic acid supplementation to marine algae-adapted and unadapted rumen inoculum on the biohydrogenation of unsaturated fatty acids in freeze-dried grass.

The objective of this study was to examine the ruminal biohydrogenation of linoleic (18:2n-6) and linolenic (18:3n-3) acid during in vitro incubations with rumen inoculum from dairy cattle adapted or not to marine algae and with or without additional in vitro docosahexaenoic acid (DHA, 22:6n-3) supplementation. Treatments were incubated in 100-mL flasks containing 400 mg of freeze-dried grass, 5 mL of strained ruminal fluid, and 20 mL of phosphate buffer. Ruminal fluid was collected just before the morning feeding from 3 cows receiving a control diet (49% ryegrass silage, 39% corn silage, 1% straw, and 11% concentrate, fresh-weight basis) supplemented with marine algae for 21 d (adapted rumen fluid, aRF) or from the same cows receiving the control diet only for 14 d after marine algae supplementation was stopped (unadapted rumen fluid, uRF). In half of the incubation flasks, pure DHA (5 mg) was added as an oil-ethanol solution (100 mL). Incubations were carried out during 0, 0.5, 1, 2, 4, 6, and 24 h. After 24 h, in vitro addition of DHA resulted in greater amounts (mg/incubation) of 18:3n-3 (0.23, 0.43, 0.26, and 0.34 for aRF, aRF+DHA, uRF, and uRF+DHA), 18:2n-6 (0.14, 0.22, 0.15, and 0.20 for aRF, aRF+DHA, uRF, and uRF+DHA) and trans-11, cis-15-18:2 (0.27, 2.40, 0.06, and 2.21 for aRF, aRF+DHA, uRF, and uRF+DHA), whereas no effect of inoculum source was observed. Trans-11-18:1 accumulated after 24 h when aRF was incubated irrespective of in vitro DHA supplementation, whereas in incubations with uRF, accumulation of trans-11-18:1 only occurred when DHA was added (6.40, 4.35, 1.06, and 3.91 for aRF, aRF+DHA, uRF, and uRF+DHA). The increased amounts of trans-11-18:1 were due to the strong inhibition of the reduction to 18:0 because no 18:0 was formed when trans-11-18:1 accumulated after 24 h. The results of the current experiment shows hydrogenation of trans-11, cis-15-18:2 occurred in the absence of in vitro DHA only, whereas substantial hydrogenation of trans-11-18:1 to 18:0 only took place in incubations without DHA and with unadapted rumen inoculum, confirming the higher sensitivity of the latter process to DHA.

Introduction of gelatin microspheres into an injectable calcium phosphate cement.

For tissue engineered bone constructs, calcium phosphate cement (CPC) has a high potential as scaffold material because of its biocompatibility and osteoconductivity. However, in vivo resorption and tissue ingrowth is slow. To address these issues, microspheres can be incorporated into the cement, which will create macroporosity after in situ degradation. The goal of this study was to investigate the handling properties and degradation characteristics of CPC containing gelatin microspheres. Setting time and injectability were determined and an in vitro degradation study was performed. Samples were assayed on mass, compression strength, E-modulus, and morphology. A supplementary degradation test with gelatin microspheres was performed to investigate the influence of physical conditions inside the cement on microsphere stability. The gelatin microsphere CPCs were easy to inject and showed initial setting times of less than 3 min. After 12-weeks in vitro degradation no increase in macroporosity was observed, which was supported by the small mass loss and stabilizing mechanical strength. Even a clear densification of the composite was observed. Explanations for the lack of macroporosity were recrystallization of the cement onto or inside the gelatin spheres and a delayed degradation of gelatin microspheres inside the scaffold. The supplementary degradation test showed that the pH is a factor in the delayed gelatin microsphere degradation. Also differences in degradation rate between types of gelatin were observed. Overall, the introduction of gelatin microspheres into CPC renders composites with good handling properties, though the degradation characteristics should be further investigated to generate a macroporous scaffold.