David K Johnson

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NADPH oxidase is a major enzymatic source of oxygen free radicals in stimulated endothelial cells (ECs). The ortho-methoxy-substituted catechol, apocynin (4-hydroxy-3-methoxyacetophenone), isolated from the traditional medicinal plant Picrorhiza kurroa, inhibits the release of superoxide anion (O2*-) by this enzyme. The compound acts by blocking the(More)
BACKGROUND White matter lesions (WMLs) are prevalent in nondemented aging and in Alzheimer disease (AD). Their relationship with cognition in the earliest stages of AD is unknown. OBJECTIVE To assess the relationship between WMLs and cognition in nondemented aging and in early-stage AD. DESIGN Cross-sectional study. SETTING Alzheimer Disease Research(More)
OBJECTIVE To examine body composition in individuals with early AD and without dementia and its relation to cognition and brain volume. DESIGN Cross-sectional case-control study. PARTICIPANTS Individuals without dementia (Clinical Dementia Rating, 0; n = 70) and with early-stage AD (Clinical Dementia Rating, 0.5 or 1; n = 70) in the Alzheimer and Memory(More)
OBJECTIVE To investigate the cognitive decline in dementia with Lewy bodies (DLBs) and characterize the contribution of Lewy bodies (LBs) to cognitive impairment in the presence of concurrent Alzheimer disease (AD). METHODS Cognitive deficits and rates of progression attributable to DLB and AD neuropathology were investigated in three groups of(More)
Exposure to atherogenic levels of low-density lipoprotein (LDL) causes elevated reactive oxygen species (ROS) production by human endothelial cells (ECs). NADPH oxidase is thought to be the main source of ROS generated by LDL-activated ECs. The mechanism by which this lipoprotein activates endothelial NADPH oxidase is incompletely understood. To gain(More)
OBJECTIVES To examine short-term changes in depression and anxiety after receiving a dementia diagnosis. DESIGN Pre/post survey design. SETTING Alzheimer's Disease Research Center. PARTICIPANTS Ninety individuals and their companions. MEASUREMENTS Fifteen-item Geriatric Depression Scale and 20-item "state" version of the State-Trait Anxiety(More)
OBJECTIVES To determine the association of weight loss and the onset of dementia of the Alzheimer type (DAT) and to characterize the rate of weight change over time in older adults (aged 65-95 years) who develop DAT vs those who remain without dementia. DESIGN Rates of weight change were investigated in older adult research participants (N = 449) who were(More)
BACKGROUND Detection of the earliest cognitive changes signifying Alzheimer disease is difficult. OBJECTIVE To model the cognitive decline in preclinical Alzheimer disease. DESIGN Longitudinal archival study comparing individuals who became demented during follow-up and people who remained nondemented on each of 4 cognitive factors: global, verbal(More)
In order to study the major cellular source of reactive oxygen species (ROS) in perturbed human endothelial cells (EC), the effect of thrombin, a phospholipase A2 activator, on cultured EC ROS generation has been investigated. EC were incubated with 0.1-1 unit/ml thrombin and cellular superoxide anion (O(-)2) release and hydrogen peroxide (H2O2) production(More)
OBJECTIVE To re-examine proposed models of cognitive test performance that concluded separate factor structures were required for people with Alzheimer disease (AD) and older adults without dementia. METHODS Five models of cognitive test performance were compared using multistep confirmatory factor analysis in 115 individuals with autopsy-confirmed AD and(More)