Faculty Bibliography

Approximately one in every two patients with pharmacoresistant temporal lobe epilepsy will not be rendered completely seizure-free after temporal lobe surgery. The reasons for this are unknown and are likely to be multifactorial. Quantitative volumetric magnetic resonance imaging techniques have provided limited insight into the causes of persistent postoperative seizures in patients with temporal lobe epilepsy. The relationship between postoperative outcome and preoperative pathology of white matter tracts, which constitute crucial components of epileptogenic networks, is unknown. We investigated regional tissue characteristics of preoperative temporal lobe white matter tracts known to be important in the generation and propagation of temporal lobe seizures in temporal lobe epilepsy, using diffusion tensor imaging and automated fibre quantification. We studied 43 patients with mesial temporal lobe epilepsy associated with hippocampal sclerosis and 44 healthy controls. Patients underwent preoperative imaging, amygdalohippocampectomy and postoperative assessment using the International League Against Epilepsy seizure outcome scale. From preoperative imaging, the fimbria-fornix, parahippocampal white matter bundle and uncinate fasciculus were reconstructed, and scalar diffusion metrics were calculated along the length of each tract. Altogether, 51.2% of patients were rendered completely seizure-free and 48.8% continued to experience postoperative seizure symptoms. Relative to controls, both patient groups exhibited strong and significant diffusion abnormalities along the length of the uncinate bilaterally, the ipsilateral parahippocampal white matter bundle, and the ipsilateral fimbria-fornix in regions located within the medial temporal lobe. However, only patients with persistent postoperative seizures showed evidence of significant pathology of tract sections located in the ipsilateral dorsal fornix and in the contralateral parahippocampal white matter bundle. Using receiver operating characteristic curves, diffusion characteristics of these regions could classify individual patients according to outcome with 84% sensitivity and 89% specificity. Pathological changes in the dorsal fornix were beyond the margins of resection, and contralateral parahippocampal changes may suggest a bitemporal disorder in some patients. Furthermore, diffusion characteristics of the ipsilateral uncinate could classify patients from controls with a sensitivity of 98%; importantly, by co-registering the preoperative fibre maps to postoperative surgical lacuna maps, we observed that the extent of uncinate resection was significantly greater in patients who were rendered seizure-free, suggesting that a smaller resection of the uncinate may represent insufficient disconnection of an anterior temporal epileptogenic network. These results may have the potential to be developed into imaging prognostic markers of postoperative outcome and provide new insights for why some patients with temporal lobe epilepsy continue to experience postoperative seizures.

Ninety-four unilateral CI patients with bimodal listening experience (CI plus HA in contralateral ear) completed a questionnaire that focused on attitudes toward hearing aid use postimplantation, patterns of usage, and perceived bimodal benefits in daily life. Eighty participants continued HA use and 14 discontinued HA use at the time of the questionnaire. Participant responses provided useful information for counseling patients both before and after implantation. The majority of continuing bimodal (CI plus HA) participants reported adapting to using both devices within 3 months and also reported that they heard better bimodally in quiet, noisy, and reverberant conditions. They also perceived benefits including improved sound quality, better music enjoyment, and sometimes a perceived sense of acoustic balance. Those who discontinued HA use found either that using the HA did not provide additional benefit over the CI alone or that using the HA degraded the signal from the CI. Because there was considerable overlap in the audiograms and in speech recognition performance in the unimplanted ear between the two groups, we recommend that unilateral CI recipients are counseled to continue to use the HA in the contralateral ear postimplantation in order to determine whether or not they receive functional or perceived benefit from using both devices together.

Growth factor withdrawal has been studied across different species and has been shown to have dramatic consequences on cell survival. In the nervous system, withdrawal of nerve growth factor (NGF) from sympathetic and sensory neurons results in substantial neuronal cell death, signifying a requirement for NGF for the survival of neurons in the peripheral nervous system (PNS). In contrast to the PNS, withdrawal of central nervous system (CNS) enriched Brain-derived neurotrophic factor (BDNF) has little effect on cell survival but is indispensible for synaptic plasticity. Given that most early events in neuropsychiatric disorders are marked by a loss of synapses, lack of BDNF may thus be an important part of a cascade of events that leads to neuronal degeneration. Here we review reports on the effects of BDNF withdrawal on CNS neurons and discuss the relevance of the loss in disease.

While current state of the art MR-PET scanners enable simultaneous MR and PET measurements, the acquired data sets are still usually reconstructed separately. We propose a new multi-modality reconstruction framework using second order Total Generalized Variation (TGV) as a dedicated multi-channel regularization functional that jointly reconstructs images from both modalities. In this way, information about the underlying anatomy is shared during the image reconstruction process while unique differences are preserved. Results from numerical simulations and in-vivo experiments using a range of accelerated MR acquisitions and different MR image contrasts demonstrate improved PET image quality, resolution, and quantitative accuracy.

Introduction: Sleep may play a role in AD pathogenesis, but the timing, role, and extent to which sleep disturbances in late-life are associated with increasing burden of AD neuropathology remains unclear. Sleep spindles have been implicated in sleep quality. Wakefulness is mediated by an arousal system beginning in the brainstem and continuing on to the diencephalon and innervating the thalamus, the region where sleep spindle oscillations are generated. In AD pathology, hyperphosphorylated tau (P-Tau) protein accumulates in the brainstem, from where it spreads to the entorhinal cortices, hippocampi and other brain regions. These tau aggregates may interfere with the sleep-wake cycle resulting in down-regulation of sleep spindles and associated sleep disruption. Increased CSF P-tau and T-tau levels are likely related to the formation of neurofibrillary tangles in the brainstem and limbic system (Braak stages I-IV). Methods: 49 cognitively normal (CDR=0) elderly (66.95 +/- 7.76 years) subjects completed a structural MRI, lumbar puncture (LP) and nocturnal polysomnography (NPSG) within 4.65 +/- 6.81 months of the LP. From the NPSG, spindle frequency and density were analyzed for stages NREM1, NREM2 and NREM3, using an automated optimization algorithm which decomposes the EEG as a sum of transient and oscillatory components. This was used to detect the spindles and a Fourier analysis was performed to evaluate the spindle frequency in Hz. Results: Spindle frequency and density in NREM2 sleep were inversely associated with CSF P-tau (r= -0.355, p<0.05; r=-0.476, p<0.05) and CSF T-tau (r=-0.405, p<.05; r=-0.542, p<.05) using partial correlation controlling for age and ApoE4 allele. There were no associations between spindle frequency or density and CSF P-tau or CSF T-tau in stages NREM1, NREM3. Conclusion: The association of spindle frequency and density in NREM2 to CSF P-tau and CSF T-tau in cognitively normal elderly suggest either that tau pathology may produce an early downstream effect on sleep spindles, or that changes in sleep spindles can identify a process relating to tau pathology. Whether the association of tau to spindles is a non-specific effect of tau on increasing sleep fragmentation in general remains an area of active investigation

Zinc participation is essential for all physiological systems, including neural functioning, where it participates in a myriad of cellular processes. Converging clinical, molecular, and genetic discoveries illuminate key roles for zinc homeostasis in association with clinical depression and psychosis which are not yet well appreciated at the clinical interface. Intracellular deficiency may arise from low circulating zinc levels due to dietary insufficiency, or impaired absorption from aging or medical conditions, including alcoholism. A host of medications commonly administered to psychiatric patients, including anticonvulsants, oral medications for diabetes, hormones, antacids, anti-inflammatories and others also impact zinc absorption. Furthermore, inefficient genetic variants in zinc transporter molecules that transport the ion across cellular membranes impede its action even when circulating zinc concentrations is in the normal range. Well powered clinical studies have shown beneficial effects of supplemental zinc in depression and it important to pursue research using zinc as a potential therapeutic option for psychosis as well. Meta-analyses support the adjunctive use of zinc in major depression and a single study now supports zinc for psychotic symptoms. This manuscript reviews the biochemistry and bench top evidence on putative molecular mechanisms of zinc as a psychiatric treatment.

Introduction Radiation Therapy (RT) for Head and Neck Cancer (HNC) can cause significant oral complications. However, modern techniques such as Intensity Modulated RT (IMRT) may reduce their incidence/severity. Objectives To assess severity of oral complications 6 months after modern RT for HNC. Methods OraRad is an ongoing 6-center prospective cohort study. Oral outcomes are evaluated before start of RT (baseline), and 6, 12, 18, 24 months after RT. For this analysis, we compared baseline vs. 6 month data using mixed linear models for continuous measures and generalized estimating equations for categorical measures. Data are presented as outcome mean (SD, number of subjects), unless otherwise stated. Results Stimulated whole salivary flow declined from 1.09 ml/min (0.67, 354) at baseline to 0.47 (0.47, 216) at 6 months (p < 0.0001). Maximal mouth opening reduced from 45.58 mm (10.40, 371) to 42.53 (9.52, 208) (p < 0.0001). 17 of 203 subjects (8.4%) had persistent oral mucositis at 6 months. Overall oral health-related quality of life score (1-4 scale) worsened from 1.48 (0.42, 371) to 1.86 (0.47, 211) (p < 0.0001). Contributing to this decline were subject-reported negative changes related to swallowing solid food, choking when swallowing, opening the mouth wide, dry mouth, sticky saliva, smell, and taste (p < 0.0001). At 6 months, there was greater frequency of using dental floss, and greater proportion using supplemental fluoride (p < 0.0001). Conclusions Despite use of IMRT, HNC patients continue to suffer significant oral complications of cancer therapy, with negative impact on oral health, function, and quality of life

INTRODUCTION: Alzheimer's disease (AD) is the most common cause of dementia. The search for new treatments is made more urgent given its increasing prevalence resulting from the aging of the global population. Over the past two decades, stem cell technologies have become an increasingly attractive option to both study and potentially treat neurodegenerative diseases. Several investigators reported a beneficial effect of different types of stem or progenitor cells on the pathology and cognitive function in AD models. Mouse models are among the most important research tools for AD treatment discovery. We aimed to explore the possible therapeutic potential of human umbilical cord mesenchymal stem cell xenografts in a transgenic (Tg) mouse model of AD. METHODS: APP/PS1 Tg AD model mice received human umbilical cord stem cells, directly injected into the carotid artery. To test the efficacy of the umbilical cord stem cells in this AD model, behavioral tasks (sensorimotor and cognitive tests) and immunohistochemical quantitation of the pathology was performed. RESULTS: Treatment of the APP/PS1 AD model mice, with human umbilical cord stem cells, produced a reduction of the amyloid beta burden in the cortex and the hippocampus which correlated with a reduction of the cognitive loss. CONCLUSION: Human umbilical cord mesenchymal stem cells appear to reduce AD pathology in a transgenic mouse model as documented by a reduction of the amyloid plaque burden compared to controls. This amelioration of pathology correlates with improvements on cognitive and sensorimotor tasks.