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Mechanisms of ageing and development (1)
Obesity surgery (1)
PLoS ONE (1)
McCarter, Roger (2)
Argyropoulos, George (1)
Bitto, Alessandro (1)
Chu, Xin (1)
Fu, Chunxiao (1)
Gerhard, Glenn S. (1)
Han, Eun-Soo (1)
Hickey, Morgen (1)
Hrelia, Silvana (1)
Ikeno, Yuji (1)
Kaeberlein, Matt (1)
Lerner, Chad (1)
Lorenzini, Antonello (1)
Malaguti, Marco (1)
Matzko, Michelle E. (1)
Matzko, Michelle Elizabeth (1)
McCarter, Roger J. M. (1)
Morrison, Melissa (1)
Perez, Viviana (1)
Roell, Michaela (1)
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Still, Christopher D. (1)
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Wood, G. Craig (1)
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Association of Ghrelin Receptor Promoter Polymorphisms with Weight Loss Following Roux-en-Y Gastric Bypass Surgery
Matzko, Michelle E.
Wood, G. Craig
Still, Christopher D.
Gerhard, Glenn S.
Ghrelin plays a role in appetite and has been hypothesized to play a role in the mechanism of Roux-en-Y gastric bypass (RYGB) surgery. Single nucleotide polymorphisms (SNPs) in the promoter region of its receptor gene (growth hormone secretagogue receptor type 1a—GHSR) have also been associated with weight loss outcomes following long-term dietary intervention in adults with impaired glucose tolerance. Our objectives were to evaluate changes in serum ghrelin levels and determine the effect of GHSR promoter polymorphisms on post-RYGB surgery weight loss.
Preoperative and 6-month postoperative serum ghrelin levels were measured in 37 patients with extreme obesity undergoing RYGB surgery. Total ghrelin was also measured in liver tissue collected intraoperatively. Association analysis between genotypes for SNPs rs9819506 and rs490683 in the promoter region of the GHSR gene and weight loss outcomes in the 30 months following surgery was performed in over 650 RYGB patients.
Serum ghrelin levels increased after RYGB surgery. Weight loss trajectories were significantly different using an additive model for both ghrelin SNPs, with patients homozygous for the rs490683 CC genotype exhibiting the most weight loss. Weight loss trajectories were also different using a dominant model. The rs490683 risk allele demonstrated decreased promoter activity in vitro.
The role of increased ghrelin levels in weight loss outcomes following RYGB surgery may be influenced by variation in the GHSR gene.
Ghrelin; SNP; RYGB; Weight loss
Long-Term IGF-I Exposure Decreases Autophagy and Cell Viability
Matzko, Michelle Elizabeth
A reduction in IGF-I signaling has been found to increase lifespan in multiple organisms despite the fact that IGF-I is a trophic factor for many cell types and has been found to have protective effects against multiple forms of damage in acute settings. The increase in longevity seen in response to reduced IGF-I signaling suggests that there may be differences between the acute and chronic impact of IGF-I signaling. We have examined the possibility that long-term stimulation with IGF-I may have a negative impact at the cellular level using quiescent human fibroblasts. We find that fibroblast cells exposed to IGF-I for 14 days have reduced long-term viability as judged by colony forming assays, which is accompanied by an accumulation of senescent cells. In addition we observe an accumulation of cells with depolarized mitochondria and a reduction in autophagy in the long-term IGF-I treated cultures. An examination of mice with reduced IGF-I levels reveals evidence of enhanced autophagy and fibroblast cells derived from these mice have a larger mitochondrial mass relative to controls indicating that changes in mitochondrial turnover occurs in animals with reduced IGF-I. The results indicate that chronic IGF-I stimulation leads to mitochondrial dysfunction and reduced cell viability.
Tissue specific and non-specific changes in gene expression by aging and by early stage CR
Mechanisms of ageing and development
Aging alters the expression of a variety of genes. Calorie restriction (CR), which extends life span in laboratory rodents, also changes gene expression. This study investigated changes in gene expression across 3 different tissues from the same mouse to examine how aging and early stage CR influence gene expression in different tissues of an organism. Expression profiling of heart, liver, and hypothalamus tissues was done in young (4–6 months) ad libitum fed (AL), young CR (2.5–4.5 months of CR), and old (26–28 months) AL male C57BL/6 mice. Aging significantly altered the expressions of 309, 1819, and 1085 genes in heart, liver, and hypothalamus tissues, respectively. In 9 genes, aging altered expression across all 3 tissues although the regulation directions did not agree across all 3 tissues for some genes. Early stage CR in young mice significantly changed the expressions of 192, 839, and 100 genes in heart, liver, and hypothalamus tissues, respectively, and 7 genes altered expression across all 3 tissues; 3 were up regulated and 4 were down regulated. The results of Gene Ontology (GO) Biological Process analysis indicated up regulation of antigen processing/presentation genes by aging and down regulation of stress response genes by early stage CR in all 3 tissues. The comparison of the results of aging and short term CR studies showed there were 389 genes, 18 GO biological processes, and 20 GO molecular functions in common.
Gene expression; Microarray; Aging; Calorie restriction
Results 1-3 (3)
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