Search

Introduction: Objective and accessible markers for Alzheimer's disease (AD) and other dementias are critically needed. Methods: We identified NMDAR2A, a protein related to synaptic function, as a novel marker of central nervous system (CNS)‐derived plasma extracellular vesicles (EVs) and developed a flow cytometry‐based technology for detecting such plasma EVs readily. The assay was initially tested in our local cross‐sectional study to distinguish AD patients from healthy controls (HCs) or from Parkinson's disease (PD) patients, followed by a validation study using an independent cohort collected from multiple medical centers (the Alzheimer's Disease Neuroimaging Initiative). Cerebrospinal fluid AD molecular signature was used to confirm diagnoses of all AD participants. Results: Likely CNS‐derived EVs in plasma were significantly reduced in AD compared to HCs in both cohorts. Integrative models including CNS‐derived EV markers and AD markers present on EVs reached area under the curve of 0.915 in discovery cohort and 0.810 in validation cohort. Discussion: This study demonstrated that robust and rapid analysis of individual neuron‐derived synaptic function–related EVs in peripheral blood may serve as a helpful marker of synaptic dysfunction in AD and dementia. [ABSTRACT FROM AUTHOR]

Edgerton, Dale S., Sylvain Cardin, Doss Neal, Ben Farmer, Margaret Lautz, Catherine Pan, and Alan D. Cherrington. Effects of hyperglycemia on hepatic gluconeogenic flux during glycogen phosphorylase inhibition in the conscious dog. Am J Physiol Endocrinol Metab 286:E510-E522, 2004. First published November 25, 2003; 10.1152/ajpendo.00211.2003.--The aim of these studies was to investigate the effect of hyperglycemia with or without hyperinsulinemia on hepatic gluconeogenic flux, with the hypothesis that inhibition would be greatest with combined hyperglycemia/hyperinsulinemia. A glycogen phosphorylase inhibitor (BAY R3401) was used to inhibit glycogen breakdown in the conscious overnight-fasted dog, and the effects of a twofold rise in plasma glucose level (HI group) accompanied by 1) euinsulinemia (HG group) or 2) a fourfold rise in plasma insulin were assessed over a 5-h experimental period. Hormone levels were controlled using somatostatin with portal insulin and glucagon infusion. In the HG group, net hepatic glucose uptake and net hepatic lactate output substantially increased. There was little or no effect on the net hepatic uptake of gluconeogenic precursors other than lactate (amino acids and glycerol) or on the net hepatic uptake of free fatty acids compared with the control group. Consequently, whereas hyperglycemia had little effect on gluconeogenic flux to glucose 6-phosphate (G-6-P), net hepatic gluconeogenic flux was reduced because of increased hepatic glycolytic flux during hyperglycemia. Net hepatic glycogen synthesis was increased by hyperglycemia. The effect of hyperglycemia on gluconeogenic flux to G-6-P and net hepatic gluconeogenic flux was similar. We conclude that, in the absence of appreciable glycogen breakdown, the increase in glycolytic flux that accompanies hyperglycemia results in decreased net carbon flux to G-6-P but no effect on gluconeogenic flux to G-6-P. hyperinsulinemia; gluconeogenesis; glycogenolysis; hepatic glucose production

Infusion of glucose into the hepatic artery blocks the stimulatory effect of the 'portal signal' on net hepatic glucose uptake (NHGU) during portal glucose delivery. We hypothesized that hepatic artery ligation (HAL) would result in enhanced NHGU during peripheral glucose infusion because the arterial glucose concentration would be perceived as lower than that in the portal vein. Fourteen dogs underwent HAL ~16 days before study. Conscious 42-h-fasted dogs received somatostatin, intraportal insulin, and glucagon infusions at fourfold basal and at basal rates, respectively, and peripheral glucose infusion to create hyperglycemia. After 90 min (period 1), seven dogs ([HAL.sub.po]) received intraportal glucose (3.8 mg*[kg.sup.-1]*[min.sup.-1]) and seven ([HAL.sub.pe]) continued to receive only peripheral glucose for 90 min (period 2). These two groups were compared with nine non-HAL control dogs (control) treated as were [HAL.sub.pe.] During period 2, the arterial plasma insulin concentrations (24 [+ or -] 3, 20 [+ or -] 1, and 24 [+ or -] 2 [micro]U/ml) and hepatic glucose loads (39.1 [+ or -] 2.5, 43.8 [+ or -] 2.9, and 37.7 [+ or -] 3.7 mg*[kg.sup.- 1]*[min.sup.-1]) were not different in [HAL.sub.pe], [HAL.sub.po], and control, respectively. [HAL.sub.po] exhibited greater (P < 0.05) NHGU than [HAL.sub.pe] and control (3.1 [+ or -] 0.3, 2.0 [+ or -] 0.4, and 2.0 [+ or -] 0.1 mg*[kg.sup.-1]*[min.sup.-1], respectively). Net hepatic carbon retention was approximately twofold greater (P < 0.05) in [HAL.sub.po] than in [HAL.sub.pe ]and control. NHGU and net hepatic glycogen synthesis during peripheral glucose infusion were not enhanced by HAL. Even though there exists an intrahepatic arterial reference site for the portal vein glucose concentration, the failure of HAL to result in enhanced NHGU during peripheral glucose infusion suggests the existence of one or more comparison sites outside the liver. liver glucose uptake; portal vein

Abstract Background Many studies have shown that mitochondrial dysfunction, complex I inhibition in particular, is involved in the pathogenesis of Parkinson's disease (PD). Rotenone, a specific inhibitor of mitochondrial complex I, has been shown to produce neurodegeneration in rats as well as in many cellular models that closely resemble PD. However, the mechanisms through which complex I dysfunction might produce neurotoxicity are as yet unknown. A comprehensive analysis of the mitochondrial protein expression profile affected by rotenone can provide important insight into the role of mitochondrial dysfunction in PD. Results Here, we present our findings using a recently developed proteomic technology called SILAC (stable isotope labeling by amino acids in cell culture) combined with polyacrylamide gel electrophoresis and liquid chromatography-tandem mass spectrometry to compare the mitochondrial protein profiles of MES cells (a dopaminergic cell line) exposed to rotenone versus control. We identified 1722 proteins, 950 of which are already designated as mitochondrial proteins based on database search. Among these 950 mitochondrial proteins, 110 displayed significant changes in relative abundance after rotenone treatment. Five of these selected proteins were further validated for their cellular location and/or treatment effect of rotenone. Among them, two were confirmed by confocal microscopy for mitochondrial localization and three were confirmed by Western blotting (WB) for their regulation by rotenone. Conclusion Our findings represent the first report of these mitochondrial proteins affected by rotenone; further characterization of these proteins may shed more light on PD pathogenesis.