Extracellular Tau Paired Helical Filaments Differentially Affect Tau Pathogenic Mechanisms in Mitotic and Post-Mitotic Cells: Implications for Mechanisms of Tau Propagation in the Brain.

The release of paired helical filaments (PHFs) from neurons into the extracellular space may contribute to the propagation of tau pathology across brain regions in Alzheimer's disease (AD) and other tauopathies. The majority of available mechanistic studies exploring the pathologic role of extracellular PHFs are conducted in proliferating cell lines. Here, we compare how extracellular PHFs induce tauopathy in mitotic cells and in post-mitotic brain neurons. In a mitotic cell line (HEK 293T), extracellular exposure to AD PHFs leads to an intracellular "aggresomal" type deposition of tau, coincidental with redistribution of dynein, a retrograde motor protein. We also observed that PHFs impaired proteasome degradation, but not autophagy. Exposure of cells to proteasome inhibitors was sufficient to induce intracellular tau aggregate formation as well as reorganization of dynein and the intermediate filament protein, vimentin. Thus, in mitotic cells, extracellular PHFs promote cellular tau aggregation, in part, by interfering with cellular proteasome degradation processes. In contrast with our observations with proliferating cells, exposure of post-mitotic primary neuronal cultures to AD PHFs did not promote "aggresomal" tau deposition, but instead resulted in a widespread accumulation of phosphorylated tau-immunoreactive swellings in neuritic processes, characterized by disturbed cytoskeletal organization of dynein and vimentin. Collectively, our observations suggest that extracellular PHFs may contribute to the propagation of tau pathology by independent mechanisms in post-mitotic and mitotic brain cells. These outcomes indicate that in addition to post-mitotic brain neurons, mitotic brain cells should also be considered as targets for therapeutic interventions to attenuate propagation of tauopathy.

Hip Fracture Surgery and Survival in Centenarians.

BACKGROUND: Hip fracture (HF) is increasingly frequent with advancing age. Studies describing the HF incidence rate and survival after surgery in centenarians are scanty. To fill this gap, we performed a large population-based investigation on Lombardy centenarians (Italy). METHODS: Retrospective observational cohort study based on information from the Healthcare Utilization Database. Among the cohort of 7,830 residents that reached 100 years of age between 2004 and 2011, incidence rate of HF was calculated. Two hundred fifty-nine patients were discharged alive from a hospital after HF and surgical repair (HF cohort). For each HF cohort member, a control was randomly selected from the initial cohort to be matched for gender and date of birth, and who did not experience HF from the date of their hundredth birthday until the date of hospital discharge of the corresponding HF cohort member. The survival curves and the hazard functions of HF and control cohort were calculated within 2 years. RESULTS: Over a mean follow-up of 1.85 years, HF incidence rate was 23.1 per 1,000 centenarians per year. Survival probability was significantly lower in HF cohort than in control cohort (31.5 vs 48.1%, p < .001). Hazard functions showed an increased risk of death in HF cohort than in control cohort, especially in the 3 months after surgery. CONCLUSION: Survival analysis exhibited an excess mortality in the first 3 months among HF cohort members, but not beyond this period. Every effort to counteract HF is warranted, including prevention of falls and high quality of care, especially in the early postsurgical time.

Recommendations for Development of New Standardized Forms of Cocoa Breeds and Cocoa Extract Processing for the Prevention of Alzheimer's Disease: Role of Cocoa in Promotion of Cognitive Resilience and Healthy Brain Aging.

It is currently thought that the lackluster performance of translational paradigms in the prevention of age-related cognitive deteriorative disorders, such as Alzheimer's disease (AD), may be due to the inadequacy of the prevailing approach of targeting only a single mechanism. Age-related cognitive deterioration and certain neurodegenerative disorders, including AD, are characterized by complex relationships between interrelated biological phenotypes. Thus, alternative strategies that simultaneously target multiple underlying mechanisms may represent a more effective approach to prevention, which is a strategic priority of the National Alzheimer's Project Act and the National Institute on Aging. In this review article, we discuss recent strategies designed to clarify the mechanisms by which certain brain-bioavailable, bioactive polyphenols, in particular, flavan-3-ols also known as flavanols, which are highly represented in cocoa extracts, may beneficially influence cognitive deterioration, such as in AD, while promoting healthy brain aging. However, we note that key issues to improve consistency and reproducibility in the development of cocoa extracts as a potential future therapeutic agent requires a better understanding of the cocoa extract sources, their processing, and more standardized testing including brain bioavailability of bioactive metabolites and brain target engagement studies. The ultimate goal of this review is to provide recommendations for future developments of cocoa extracts as a therapeutic agent in AD.

Novel application of brain-targeting polyphenol compounds in sleep deprivation-induced cognitive dysfunction.

Sleep deprivation produces deficits in hippocampal synaptic plasticity and hippocampal-dependent memory storage. Recent evidence suggests that sleep deprivation disrupts memory consolidation through multiple mechanisms, including the down-regulation of the cAMP-response element-binding protein (CREB) and of mammalian target of rapamycin (mTOR) signaling. In this study, we tested the effects of a Bioactive Dietary Polyphenol Preparation (BDPP), comprised of grape seed polyphenol extract, Concord grape juice, and resveratrol, on the attenuation of sleep deprivation-induced cognitive impairment. We found that BDPP significantly improves sleep deprivation-induced contextual memory deficits, possibly through the activation of CREB and mTOR signaling pathways. We also identified brain-available polyphenol metabolites from BDPP, among which quercetin-3-O-glucuronide activates CREB signaling and malvidin-3-O-glucoside activates mTOR signaling. In combination, quercetin and malvidin-glucoside significantly attenuated sleep deprivation-induced cognitive impairment in -a mouse model of acute sleep deprivation. Our data suggests the feasibility of using select brain-targeting polyphenol compounds derived from BDPP as potential therapeutic agents in promoting resilience against sleep deprivation-induced cognitive dysfunction.

Shared genetic etiology underlying Alzheimer's disease and type 2 diabetes.

Epidemiological evidence supports the observation that subjects with type 2 diabetes (T2D) are at higher risk to develop Alzheimer's disease (AD). However, whether and how these two conditions are causally linked is unknown. Possible mechanisms include shared genetic risk factors, which were investigated in this study based on recent genome wide association study (GWAS) findings. In order to achieve our goal, we retrieved single nucleotide polymorphisms (SNPs) associated with T2D and AD from large-scale GWAS meta-analysis consortia and tested for overlap among the T2D- and AD-associated SNPs at various p-value thresholds. We then explored the function of the shared T2D/AD GWAS SNPs by leveraging expressional quantitative trait loci, pathways, gene ontology data, and co-expression networks. We found 927 SNPs associated with both AD and T2D with p-value ≤0.01, an overlap significantly larger than random chance (overlapping p-value of 6.93E-28). Among these, 395 of the shared GWAS SNPs have the same risk allele for AD and T2D, suggesting common pathogenic mechanisms underlying the development of both AD and T2D. Genes influenced by shared T2D/AD SNPs with the same risk allele were first identified using a SNP annotation variation (ANNOVAR) software, followed by using Association Protein-Protein Link Evaluator (DAPPLE) software to identify additional proteins that are known to physically interact with the ANNOVAR gene annotations. We found that gene annotations from ANNOVAR and DAPPLE significantly enriched specific KEGG pathways pertaining to immune responses, cell signaling and neuronal plasticity, cellular processes in which abnormalities are known to contribute to both T2D and AD pathogenesis. Thus, our observation suggests that among T2D subjects with common genetic predispositions (e.g., SNPs with consistent risk alleles for T2D and AD), dysregulation of these pathogenic pathways could contribute to the elevated risks for AD in subjects. Interestingly, we found that 532 of the shared T2D/AD GWAS SNPs had divergent risk alleles in the two diseases. For individual shared T2D/AD SNPs with divergent alleles, one of the allelic forms may contribute to one of the diseases (e.g., T2D), but not necessarily to the other (e.g., AD), or vice versa. Collectively, our GWAS studies tentatively support the epidemiological observation of disease concordance between T2D and AD. Moreover, the studies provide the much needed information for the design of future novel therapeutic approaches, for a subpopulation of T2D subjects with genetic disposition to AD, that could benefit T2D and reduce the risk for subsequent development of AD.

Impaired mitochondrial energy metabolism as a novel risk factor for selective onset and progression of dementia in oldest-old subjects.

Recent evidence shows that Alzheimer disease (AD) dementia in the oldest-old subjects was associated with significantly less amyloid plaque and fibrillary tangle neuropathology than in the young-old population. In this study, using quantitative (q) PCR studies, we validated genome-wide microarray RNA studies previously conducted by our research group. We found selective downregulation of mitochondrial energy metabolism genes in the brains of oldest-old, but not young-old, AD dementia cases, despite a significant lack of classic AD neuropathology features. We report a significant decrease of genes associated with mitochondrial pyruvate metabolism, the tricarboxylic acid cycle (TCA), and glycolytic pathways. Moreover, significantly higher levels of nitrotyrosylated (3-NT)-proteins and 4-hydroxy-2-nonenal (HNE) adducts, which are indexes of cellular protein oxidation and lipid peroxidation, respectively, were detected in the brains of oldest-old subjects at high risk of developing AD, possibly suggesting compensatory mechanisms. These findings support the hypothesis that although oldest-old AD subjects, characterized by significantly lower AD neuropathology than young-old AD subjects, have brain mitochondrial metabolism impairment, which we hypothesize may selectively contribute to the development of dementia. Outcomes from this study provide novel insights into the molecular mechanisms underlying clinical dementia in young-old and oldest-old AD subjects and provide novel strategies for AD prevention and treatment in oldest-old dementia cases.

Role of intestinal microbiota in the generation of polyphenol-derived phenolic acid mediated attenuation of Alzheimer's disease ß-amyloid oligomerization.

SCOPE: Grape seed polyphenol extract (GSPE) is receiving increasing attention for its potential preventative and therapeutic roles in Alzheimer's disease (AD) and other age-related neurodegenerative disorders. The intestinal microbiota is known to actively convert many dietary polyphenols, including GSPE, to phenolic acids. There is limited information on the bioavailability and bioactivity of GSPE-derived phenolic acid in the brain. METHODS AND RESULTS: We orally administered GSPE to rats and investigated the bioavailability of 12 phenolic acids known to be generated by microbiota metabolism of anthocyanidins. GSPE treatment significantly increased the content of two of the phenolic acids in the brain: 3-hydroxybenzoic acid and 3-(3´-hydroxyphenyl)propionic acid, resulting in the brain accumulations of the two phenolic acids at micromolar concentrations. We also provided evidence that 3-hydroxybenzoic acid and 3-(3´-hydroxyphenyl)propionic acid potently interfere with the assembly of ß-amyloid peptides into neurotoxic ß-amyloid aggregates that play key roles in AD pathogenesis. CONCLUSION: Our observation suggests important contribution of the intestinal microbiota to the protective activities of GSPE (as well as other polyphenol preparations) in AD. Outcomes from our studies support future preclinical and clinical investigations exploring the potential contributions of the intestinal microbiota in protecting against the onset/progression of AD and other neurodegenerative conditions.

Simultaneous bilateral femoral neck fracture and end-stage renal disease in a 76-year-old woman: a case report.

Hip fracture is a common occurrence in the elderly. Due to the growing demand for the specific care of these patients, we established the Orthogeriatric Unit (OGU) at San Gerardo University Hospital (Italy) in 2007. However, simultaneous bilateral femoral neck fractures among the geriatric population (those aged ≥65 years) are rarely reported in the literature. Reporting the rare case of a frail 76-year-old woman admitted with bilateral hip fracture and end-stage renal disease, we explain the important role played by the OGU and its flexible multidisciplinary approach for providing comprehensive care to patients with multimorbidity and clinical complexity. The team of geriatricians, orthopedic surgeons, anesthesiologists, and, in this case, a nephrologist, helped in the careful planning and timing of the single-step surgical repair, decided the appropriate type of anesthesia, and optimized outcomes. After a prompt evaluation of the patient, the OGU approach can achieve clinical stabilization prior to intervention. Along with a strict follow-up in the postoperative phase, this could result in a significant reduction of complications and mortality rates and an early start to a tailored rehabilitation process. We strongly suggest employing facilities with multidisciplinary teams for cases involving complex patients at short-term high risk for poor clinical outcomes. Indeed, the usual single-specialist model of care is gradually being abandoned worldwide.

Roles of resveratrol and other grape-derived polyphenols in Alzheimer's disease prevention and treatment.

Alzheimer's disease (AD) is a devastating disorder that strikes 1 in 10 Americans over the age of 65, and almost half of all Americans over 85 years old. The odds of an individual developing AD double every five years after the age of 65. While it has become increasingly common to meet heart attack or cancer survivors, there are no AD survivors. There is mounting evidence that dietary polyphenols, including resveratrol, may beneficially influence AD. Based on this consideration, several studies reported in the last few years were designed to validate sensitive and reliable translational tools to mechanistically characterize brain bioavailable polyphenols as disease-modifying agents to help prevent the onset of AD dementia and other neurodegenerative disorders. Several research groups worldwide with expertise in AD, plant biology, nutritional sciences, and botanical sciences have reported very high quality studies that ultimately provided the necessary information showing that polyphenols and their metabolites, which come from several dietary sources, including grapes, cocoa etc., are capable of preventing AD. The ultimate goal of these studies was to provide novel strategies to prevent the disease even before the onset of clinical symptoms. The studies discussed in this review article provide support that the information gathered in the last few years of research will have a major impact on AD prevention by providing vital knowledge on the protective roles of polyphenols, including resveratrol. This article is part of a Special Issue entitled: Resveratrol: Challenges in translating pre-clinical findings to improved patient outcomes.