Beach, Thomas G.

ABSTRACT There has been controversy as to whether there is an underlying neurodegenerative process of the cerebellum in essential tremor (ET). The aim of this study was to examine whether ET is associated with Purkinje cell (PC) loss. Prospectively categorized ET and control subjects who were longitudinally examined in the Arizona Study for Aging and Neurodegenerative Disorders and came to autopsy between 1998 and 2013 underwent standardized neuropathological assessment of the brain. PC linear density of the cerebellar hemisphere was calculated in a blinded manner. There were 56 ET cases and 62 age‐matched controls free of dementia and other neurodegenerative disorders included in the study. Mean PC linear density was 3.80 ± 0.81 cells per mm for tremor cases and 3.82 ± 0.91 cells per mm for controls ( Δ 0.02; 95% confidence interval [CI]: −0.30‐0.34). PC counts were not associated with tremor duration (r = 0.06; 95% CI: −0.21‐0.32). These data demonstrate that ET is not associated with cerebellar PC loss. © 2014 International Parkinson and Movement Disorder Society

ABSTRACT Parkinson's disease (PD) biomarkers are needed to enhance therapeutics research and to understand PD pathogenesis. Methods that simultaneously measure hundreds of small molecular‐weight compounds—metabolomic analysis–“fingerprint” disease‐specific alterations in individual compounds or metabolic pathways. Beyond a nontargeted search for PD biomarkers, we hypothesized that PD cerebrospinal fluid would show increased formation of the excitotoxin 3‐hydroxykynurenine and diminished concentration of the antioxidant glutathione. Cerebrospinal fluid was collected at <4 hours postmortem from 48 pathologically‐verified PD subjects and 57 comparably‐aged controls. Assays involved ultra‐high‐performance liquid and gas chromatography linked to mass spectrometry. We used univariate techniques to determine fold‐changes in concentrations of biochemicals; false‐discovery rates were calculated to exclude spurious findings. Data was modeled using a Support Vector Machine for analyzing compounds selected by Welch's t test. Classification accuracy was determined by cross‐validation. Of 243 structurally‐identified biochemicals,19 compounds differentiated PD from controls at a 20% false‐discovery level. In PD, mean 3‐hydroxykynurenine concentration was increased by one‐third, and mean oxidized glutathione was decreased by 40% (for each, P < .01). Four of the 19 compounds differentiating PD from controls were N‐acetylated amino acids, suggesting a generalized alteration in N‐acetylation activity. The Support Vector Machine classification model distinguished between groups at 83% sensitivity and 91% specificity for the learning data, and at 65% and 79% from cross‐validation. In this study, the first for metabolomic profiling of PD cerebrospinal fluid, we found several novel biomarkers and offer new directions for recognizing disease‐specific biochemical indicators. The findings support involvement of excitotoxicity and oxidative stress in the pathogenesis of PD. © 2013 International Parkinson and Movement Disorder Society

Missense mutations in LRRK2 (leucine-rich repeat kinase 2) are a major cause of PD (Parkinson's disease). Several antibodies against LRRK2 have been developed, but results using these polyclonal antibodies have varied widely leading to conflicting conclusions. To address this challenge, the Michael J. Fox Foundation for Parkinson's Research generated a number of monoclonal antibodies targeting epitopes across the LRRK2 protein. In the present paper, we report optimized protocols and results for ten monoclonal antibodies for immunoblotting, immunohistochemistry, immunoprecipitation and kinase activity assays, in rat, mouse and human brain tissue. Several efficacious antibodies were identified, but results demonstrate that the mouse monoclonal N241A/34 is suitable for most applications, with the best overall rabbit monoclonal antibody being c41-2. These antibodies produced a dominant band of the expected size via immunoblotting and a lack of labelling in tissue derived from LRRK2-knockout animals under optimized conditions. A significant proportion of LRRK2 protein localizes to insoluble fractions and no evidence of truncated LRRK2 protein was detected in any fraction from rodent or human tissues. An assay was developed for the robust detection of LRRK2 kinase activity directly from frozen mouse and human brain tissue, but precipitous declines in activity were observed that corresponded to increasing post-mortem intervals and processing times. Finally, we demonstrate the highest levels of brain-localized LRRK2 in the striatum, but note differential expression patterns between rat and mouse in both striatum and cortex. Anti-LRRK2 monoclonal antibodies that are unlimited in availability together with the proposed standardized protocols should aid in the definition of LRRK2 function in both health and disease.

Abstract A consensus panel from the United States and Europe was convened recently to update and revise the 1997 consensus guidelines for the neuropathologic evaluation of Alzheimer's disease (AD) and other diseases of brain that are common in the elderly. The new guidelines recognize the pre‐clinical stage of AD, enhance the assessment of AD to include amyloid accumulation as well as neurofibrillary change and neuritic plaques, establish protocols for the neuropathologic assessment of Lewy body disease, vascular brain injury, hippocampal sclerosis, and TDP‐43 inclusions, and recommend standard approaches for the workup of cases and their clinico‐pathologic correlation.

BackgroundMultiple lines of evidence suggest that cardiovascular co‐morbidities hasten the onset of Alzheimer's disease (AD) or accelerate its course.MethodsTo evaluate the utility of cerebral vascular physical function and/or condition parameters as potential systemic indicators of AD, transcranial Doppler (TCD) ultrasound was used to assess cerebral blood flow and vascular resistance of the 16 arterial segments comprising the circle of Willis and its major tributaries.ResultsOur study showed that decreased arterial mean flow velocity and increased pulsatility index are associated with a clinical diagnosis of presumptive AD. Cerebral blood flow impairment shown by these parameters reflects the global hemodynamic and structural consequences of a multifaceted disease process yielding diffuse congestive microvascular pathology, increased arterial rigidity, and decreased arterial compliance, combined with putative age‐associated cardiovascular output declines.ConclusionsTCD evaluation offers direct physical confirmation of brain perfusion impairment and might ultimately provide a convenient and a noninvasive means to assess the efficacy of medical interventions on cerebral blood flow or reveal incipient AD. In the near term, TCD‐based direct assessments of brain perfusion might offer the prospect of preventing or mitigating AD simply by revealing patients who would benefit from interventions to improve circulatory system function.