Baylor Research Institute

Ejaz, A., L. Martinez-Guino, A. B. Goldfine, F. Ribas-Aulinas, V. De Nigris, S. Ribo, A. Gonzalez-Franquesa, P. M. Garcia-Roves, E. Li, J. M. Dreyfuss, W. Gall, J. K. Kim, T. Bottiglieri, F. Villarroya, R. E. Gerszten, M. E. Patti and C. Lerin (2016). “Dietary Betaine Supplementation Increases Fgf21 Levels to Improve Glucose Homeostasis and Reduce Hepatic Lipid Accumulation in Mice.” Diabetes. Feb 8. [Epub ahead of print]

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Identifying markers of human insulin resistance may permit development of new approaches for treatment and prevention of type 2 diabetes. To this end, we analyzed the fasting plasma metabolome in metabolically characterized human volunteers across a spectrum of insulin resistance. We demonstrate that plasma betaine levels are reduced in insulin resistant humans, and correlate closely with insulin sensitivity. Moreover, betaine administration to diet-induced obese mice prevents the development of impaired glucose homeostasis, reduces hepatic lipid accumulation, increases white adipose oxidative capacity, and enhances whole-body energy expenditure. In parallel with these beneficial metabolic effects, betaine supplementation robustly increased hepatic and circulating Fgf21 levels. Betaine administration failed to improve glucose homeostasis and liver fat content in Fgf21-/- mice, demonstrating that Fgf21 is necessary for betaine’s beneficial effects. Together, these data indicate that dietary betaine increases Fgf21 levels to improve metabolic health in mice, and suggest that betaine supplementation merits further investigation as a supplement for treatment or prevention of type 2 diabetes in humans.

Shen, J. S., A. Busch, T. S. Day, X. L. Meng, C. I. Yu, P. Dabrowska-Schlepp, B. Fode, H. Niederkruger, S. Forni, S. Chen, R. Schiffmann, T. Frischmuth and A. Schaaf (2016). “Mannose receptor-mediated delivery of moss-made alpha-galactosidase A efficiently corrects enzyme deficiency in Fabry mice.” J Inherit Metab Dis 39(2): 293-303.

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Enzyme replacement therapy (ERT) is an effective treatment for several lysosomal storage disorders (LSDs). Intravenously infused enzymes are taken up by tissues through either the mannose 6-phosphate receptor (M6PR) or the mannose receptor (MR). It is generally believed that M6PR-mediated endocytosis is a key mechanism for ERT in treating LSDs that affect the non-macrophage cells of visceral organs. However, the therapeutic efficacy of MR-mediated delivery of mannose-terminated enzymes in these diseases has not been fully evaluated. We tested the effectiveness of a non-phosphorylated alpha-galactosidase A produced from moss (referred to as moss-aGal) in vitro and in a mouse model of Fabry disease. Endocytosis of moss-aGal was MR-dependent. Compared to agalsidase alfa, a phosphorylated form of alpha-galactosidase A, moss-aGal was more preferentially targeted to the kidney. Cellular localization of moss-aGal and agalsidase alfa in the heart and kidney was essentially identical. A single injection of moss-aGal led to clearance of accumulated substrate in the heart and kidney to an extent comparable to that achieved by agalsidase alfa. This study suggested that mannose-terminated enzymes may be sufficiently effective for some LSDs in which non-macrophage cells are affected, and that M6P residues may not always be a prerequisite for ERT as previously considered.

Driver, S., A. M. Warren, M. Reynolds, S. Agtarap, R. Hamilton, Z. Trost and K. Monden (2016). “Identifying predictors of resilience at inpatient and 3-month post-spinal cord injury.” J Spinal Cord Med 39(1): 77-84.

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Objectives To identify (1) changes in psychosocial factors, (2) relationships between psychosocial factors, and (3) significant predictors of resilience in adults with spinal cord injury (SCI) during inpatient rehabilitation and at 3-month post-discharge. Design Cross sectional with convenience sample based on inclusion/exclusion criteria. Setting Inpatient rehabilitation hospital and community-based follow-up. Participants Individuals with a SCI. Interventions Not applicable. Outcome measures Demographic, resilience, self-efficacy for managing a chronic health issue, depression, social roles/activity limitations, and pain. Results The final sample consisted of 44 respondents (16 women and 28 men). Results of repeated measure analyses of variance indicated no significant changes in variables between inpatient and 3-month follow-up. Bivariate correlations revealed associations between resilience and self-efficacy at inpatient (r = 0.54, P < 0.001), and resilience and depression (r = -0.69, P < 0.001) and self-efficacy (r = 0.67, P < 0.001) at 3-month follow-up. Hierarchical regression analyses a significant model predicting resilience at inpatient stay (R = 0.61; adjusted R(2) = 0.24, P = 0.023), and at 3-month follow-up (R = 0.83; adjusted R(2) = 0.49, P = 0.022). Self-efficacy was the strongest predictor at inpatient stay (beta = 0.46, P = 0.006) and depression was strongest at 3-month follow-up (beta = -0.80, P = 0.007). Conclusion Results suggest that although resilience appears to be stable from inpatient to 3-month follow-up, different factors are stronger predictors of resilience across time. Based on current results, an assessment of self-efficacy during inpatient rehabilitation and an identification of depression at 3-month follow-up may be important factors to help identify those at risk of health issues overtime.

Fernandez, H., J. Weber, K. Barnes, L. Wright and M. Levy (2016). “Financial Impact of Liver Sharing and Organ Procurement Organizations’ Experience With Share 35: Implications for National Broader Sharing.” Am J Transplant 16(1): 287-291.

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The Share 35 policy for organ allocation, which was adopted in June 2013, allocates livers regionally for candidates with Model for End-Stage Liver Disease scores of 35 or greater. The authors analyzed the costs resulting from the increased movement of allografts related to this new policy. Using a sample of nine organ procurement organizations, representing 17% of the US population and 19% of the deceased donors in 2013, data were obtained on import and export costs before Share 35 implementation (June 15, 2012, to June 14, 2013) and after Share 35 implementation (June 15, 2013, to June 14, 2014). Results showed that liver import rates increased 42%, with an increased cost of 51%, while export rates increased 112%, with an increased cost of 127%. When the costs of importing and exporting allografts were combined, the total change in costs for all nine organ procurement organizations was $11 011 321 after Share 35 implementation. Extrapolating these costs nationally resulted in an increased yearly cost of $68 820 756 by population or $55 056 605 by number of organ donors. Any alternative allocation proposal needs to account for the financial implications to the transplant infrastructure.

Arning, E. and T. Bottiglieri (2016). “Quantitation of S-Adenosylmethionine and S-Adenosylhomocysteine in Plasma Using Liquid Chromatography-Electrospray Tandem Mass Spectrometry.” Methods Mol Biol 1378: 255-262.

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We describe a simple stable isotope dilution method for accurate determination of S-adenosylmethionine (SAM) and S-adenosylhomocysteine (SAH) in plasma as a diagnostic test. SAM and SAH are key metabolic intermediates of methionine metabolism and the methylation cycle. Determination of SAM and SAH in plasma was performed by high performance liquid chromatography coupled with electrospray positive ionization tandem mass spectrometry (HPLC-ESI-MS/MS). Calibrators (SAM and SAH) and internal standards ((2)H3-SAM and (2)H4-SAH) were included in each analytical run for calibration. Sample preparation involved combining 20 muL sample with 180 muL of internal standard solution consisting of heavy isotope labeled internal standards in mobile phase A and filtering by ultracentrifugation through a 10 kd MW cutoff membrane. Sample filtrate (3 muL) was injected by a Shimadzu Nexera LC System interfaced with a 5500 QTRAP((R)) (AB Sciex). Chromatographic separation was achieved on a 250 mm x 2.0 mm EA:faast column from Phenomenex. Samples were eluted at a flow rate of 0.20 mL/min with a binary gradient with a total run time of 10 min. The source operated in positive ion mode at an ion spray voltage of +5000 V. SAM and SAH resolved by a gradient to 100 % methanol with retention times of 6.0 and 5.7 min, respectively. The observed m/z values of the fragment ions were m/z 399 –> 250 for SAM, m/z 385 –> 136 for SAH, m/z 402 –> 250 for (2)H3-SAM, m/z 203 –> 46. The calibration curve was linear over the ranges of 12.5-5000 nmol/L for SAM and SAH.