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- Maghsoodi, N., et al.
(author)
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Elevated fasting and postprandial C-terminal telopeptide after Roux-en-Y gastric bypass
- 2017
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In: Annals of Clinical Biochemistry. - : SAGE Publications. - 0004-5632. ; 54:4, s. 495-500
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Journal article (peer-reviewed)abstract
- Background Roux-en-Y gastric bypass increases circulating bile acid concentrations, known mediators of postprandial suppression of markers of bone resorption. Long-term data, however, indicate that Roux-en-Y gastric bypass confers an increased risk of bone loss on recipients. Methods Thirty-six obese individuals, median age 44 (26-64) with median body mass index at baseline of 42.5 (40.4-46) were studied before and 15 months after Roux-en-Y gastric bypass. After an overnight fast, patients received a 400kcal mixed meal. Blood samples were collected premeal then at 30-min periods for 120min. Pre and postmeal samples were analysed for total bile acids, parathyroid hormone and C-terminal telopeptide. Results Body weight loss post Roux-en-Y gastric bypass was associated with a median 4.9-fold increase in peak postprandial total bile acid concentration, and a median 2.4-fold increase in cumulative food evoked bile acid response. Median fasting parathyroid hormone, postprandial reduction in parathyroid hormone and total parathyroid hormone release over 120min remained unchanged after surgery. After surgery, median fasting C-terminal telopeptide increased 2.3-fold, peak postprandial concentrations increased 3.8-fold and total release was increased 1.9-fold. Conclusions Fasting and postprandial total bile acids and C-terminal telopeptide are increased above reference range after Roux-en-Y gastric bypass. These changes occur in spite of improved vitamin D status with supplementation. These results suggest that post-Roux-en-Y gastric bypass increases in total bile acids do not effectively oppose an ongoing resorptive signal operative along the gut-bone axis. Serial measurement of C-terminal telopeptide may be of value as a risk marker for long-term skeletal pathology in patients post Roux-en-Y gastric bypass.
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- Rozen-Rechels, David, et al.
(author)
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Contrasting impacts of an alien invasive shrub on mammalian savanna herbivores revealed on a landscape scale
- 2017
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In: Diversity & distributions. - : John Wiley & Sons. - 1366-9516 .- 1472-4642. ; 23:6, s. 656-666
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Journal article (peer-reviewed)abstract
- Aim: Habitat loss and fragmentation is one of the main drivers of defaunation, that is the loss of large mammals. Biological invasions could be drivers of such phenomenon. However, their impact on large herbivore communities has not been studied to our knowledge. We made use of a landscape-scale control programme of one of the world's worst invaders, the shrub Chromolaena odorata, as a natural experiment to assess how this alien invader affects habitat use by 14 species of ungulates in an African savanna. Location: Hluhluwe-iMfolozi Park, KwaZulu-Natal, South Africa. Methods: At the height of the invasion in 2004, a large-scale control programme was initiated that successfully reduced densities of C.odorata across the park. We estimated mammalian herbivore habitat and patch use by dung counts and the presence and density of C.odorata along 24 line transects with a total length of 190km during the peak of the invasion (2004) and a decade after the initiation of a successful control programme (2014). To account for differences in herbivore assemblies between habitats and the preferential invasion of closed savanna woodlands, we analysed the recolonization of previously invaded patches by herbivores based on the change in dung abundance. Results: Herbivore species differed in how they responded to invaded patches of this non-native shrub. Grazers were the most negatively affected, especially those that avoid predators by running. Browsers were negatively impacted only at the highest invasive shrub densities. Some species, especially bushpig, positively selected invaded patches. Main conclusions: Large herbivores varied in their response to invasion with differences in impact depending on feeding strategy and predator avoidance strategy, but the majority of ungulates responded positively to the removal of this invasive shrub.
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