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Alzheimer's disease (AD), currently the single leading cause of death still on the rise, almost always coexists alongside vascular cognitive impairment (VCI). In fact, the ischemic disease affects up to 90% of AD patients, with strokes and major infarctions representing over a third of vascular lesions. Studies also confirmed that amyloid plaques, typical of AD, are much more likely to cause dementia if strokes or cerebrovascular damage also exist, leading to the term "mixed pathology" cognitive impairment. Although its incidence is expected to grow, there are no satisfactory treatments. There is hence an urgent need for safe and effective therapies that preserve cognition, maintain function, and prevent the clinical deterioration that results from the progression of this irreversible, neurodegenerative disease. To our knowledge, this is the first study to investigate the effects of long-term treatment with C21, a novel angiotensin II type 2 receptor (AT2R) agonist, on the development of "mixed pathology" cognitive impairment. This was accomplished using a unique model that employs the fundamental elements of both AD and VCI. Treatment with C21/vehicle was started 1 h post-stroke and continued for 5 weeks in mice with concurrent AD pathology. Efficacy was established through a series of functional tests assessing various aspects of cognition, including spatial learning, short-term/working memory, long-term/reference memory, and cognitive flexibility, in addition to the molecular markers characteristic of AD. Our findings demonstrate that C21 treatment preserves cognitive function, maintains cerebral blood flow, and reduces Aβ accumulation and toxic tau phosphorylation in AD animals post-stroke., (© 2022. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Although the exact etiology of Alzheimer's disease (AD) is poorly understood, experimental and clinical evidences suggest the contribution of neuroinflammation in the pathogenesis of AD. Pathologically, AD brain is characterized by an imbalance in redox status, elevated endoplasmic reticulum (ER) stress, synaptic dysfunction, inflammation, and progressive neurodegeneration. It has been noted that continuous accumulation of amyloid-beta (Aβ) and intracellular neurofibrillary tangles (NFTs) in AD brain trigger ER stress, which contributes to neurodegeneration. Similarly, experimental evidences supports the hypothesis that thioredoxin-interacting protein (TXNIP), an endogenous regulator of redox regulator thioredoxin (TRX), is activated by ER stress and contributes to activation of NLRP3 (NOD-like receptor protein 3) inflammatory cascade in hippocampus of the AD brain. Hippocampus of postmortem human AD and aged matched non-AD controls were analyzed for the expression ER stress markers and TXNIP-NLRP3 inflammasome at cellular and molecular levels. We found higher expression of TXNIP at protein and transcript levels in close association with pathological markers of AD such as Aβ and NFTs in AD hippocampus. In addition, our results demonstrated that TXNIP was co-localized in neurons and microglia. Moreover, expression of binding immunoglobulin protein (BiP), activated eukaryotic initiation factor-2α (eIf2α) and C/EBP homology protein (CHOP), proteins involved the development of ER stress, were elevated in AD hippocampus. Further, elevated expression of effector molecules of NLRP3 inflammasome activation such as apoptosis associated speck-like protein (ASC), cleaved caspase-1 and cleaved interleukin-1β were observed in the AD hippocampus. The study suggests that TXNIP could be a link that connect ER stress with neuroinflammation. Thus, TXNIP can be a possible therapeutic target to mitigate the progression of neuroinflammation in the pathogenesis of AD., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Immune system hypersensitivity is believed to contribute to mental frailty in the elderly. Solid evidence indicates NOD-like receptor pyrin domain containing-3 (NLRP3)-inflammasome activation intimately connects aging-associated chronic inflammation (inflammaging) to senile cognitive decline. Thioredoxin interacting protein (TXNIP), an inducible protein involved in oxidative stress, is essential for NLRP3 inflammasome activity. This study aims to find whether TXNIP/NLRP3 inflammasome pathway is involved in senile dementia. According to our studies on sex-matched mice, TXNIP was significantly upregulated in aged animals, paralleled by the NLRP3-inflammasome over-activity leading to enhanced caspase-1 cleavage and IL-1β maturation, in both sexes. This was closely associated with depletion of the anti-aging and cognition enhancing protein klotho, in aged males. Txnip knockout reversed age-related NLRP3-hyperactivity and enhanced thioredoxin (TRX) levels. Further, TXNIP inhibition along with verapamil replicated TXNIP/NLRP3-inflammasome downregulation in aged animals, with FOXO-1 and mTOR upregulation. These alterations concurred with substantial improvements in both cognitive and sensorimotor abilities. Together, these findings substantiate the pivotal role of TXNIP to drive inflammaging in parallel with klotho depletion and functional decline, and delineate thioredoxin system as a potential target to decelerate senile dementia., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)

Alzheimer's disease (AD), a progressive neurodegenerative disorder characterized by memory loss and cognitive decline, is a major cause of death and disability among the older population. Despite decades of scientific research, the underlying etiological triggers are unknown. Recent studies suggested that gut microbiota can influence AD progression; however, potential mechanisms linking the gut microbiota with AD pathogenesis remain obscure. In the present study, we provided a potential mechanistic link between dysbiotic gut microbiota and neuroinflammation associated with AD progression. Using a mouse model of AD, we discovered that unfavorable gut microbiota are correlated with abnormally elevated expression of gut NLRP3 and lead to peripheral inflammasome activation, which in turn exacerbates AD-associated neuroinflammation. To this end, we observe significantly altered gut microbiota compositions in young and old 5xFAD mice compared to age-matched non-transgenic mice. Moreover, 5xFAD mice demonstrated compromised gut barrier function as evident from the loss of tight junction and adherens junction proteins compared to non-transgenic mice. Concurrently, we observed increased expression of NLRP3 inflammasome and IL-1β production in the 5xFAD gut. Consistent with our hypothesis, increased gut-microbial-inflammasome activation is positively correlated with enhanced astrogliosis and microglial activation, along with higher expression of NLRP3 inflammasome and IL-1β production in the brains of 5xFAD mice. These data indicate that the elevated expression of gut-microbial-inflammasome components may be an important trigger for subsequent downstream activation of inflammatory and potentially cytotoxic mediators, and gastrointestinal NLRP3 may promote NLRP3 inflammasome-mediated neuroinflammation. Thus, modulation of the gut microbiota may be a potential strategy for the treatment of AD-related neurological disorders in genetically susceptible hosts.

Alzheimer's disease (AD) is a progressive neurodegenerative disease that accounts for a majority of dementia cases. AD is characterized by progressive neuronal death associated with neuropathological lesions consisting of neurofibrillary tangles and senile plaques. While the pathogenesis of AD has been widely investigated, significant gaps in our knowledge remain about the cellular and molecular mechanisms promoting AD. Recent studies have highlighted the role of DNA damage, particularly DNA double-strand breaks (DSBs), in the progression of neuronal loss in a broad spectrum of neurodegenerative diseases. In the present study, we tested the hypothesis that accumulation of DNA DSB plays an important role in AD pathogenesis. To test our hypothesis, we examined DNA DSB expression and DNA repair function in the hippocampus of human AD and non-AD brains by immunohistochemistry, ELISA, and RT-qPCR. We observed increased DNA DSB accumulation and reduced DNA repair function in the hippocampus of AD brains compared to the non-AD control brains. Next, we found significantly increased levels of DNA DSB and altered levels of DNA repair proteins in the hippocampus of 5xFAD mice compared to non-transgenic mice. Interestingly, increased accumulation of DNA DSBs and altered DNA repair proteins were also observed in cellular models of AD. These findings provided compelling evidence that AD is associated with accumulation of DNA DSB and/or alteration in DSB repair proteins which may influence an important early part of the pathway toward neural damage and memory loss in AD.

Background: Forearm fracture risk can be estimated via factor-of-risk: the ratio of applied impact force to forearm fracture load. Simple techniques are available for estimating impact force associated with a fall; estimating forearm fracture load is more challenging. Our aim was to assess whether failure load estimates of sections of the distal radius (acquired using High-Resolution peripheral Quantitative Computed Tomography and finite element modeling) offer accurate and precise estimates of forearm fracture load., Methods: We scanned a section of the distal radius of 19 cadaveric forearms (female, mean age 83.7, SD 8.3), and 34 women (75.0, 7.7). Sections were converted to finite element models and failure loads were acquired for different failure criteria. We assessed forearm fracture load using experimental testing simulating a fall on the outstretched hand. We used linear regression to derive relationships between ex vivo forearm fracture load and finite element derived distal radius failure load. We used derived regression coefficients to estimate forearm fracture load, and assessed explained variance and prediction error. We used root-mean-squared coefficients of variation to assess in vivo precision errors of estimated forearm fracture load., Findings: Failure load estimates of sections of the distal radius, used in conjunction with derived regression coefficients, explained 89-90% of the variance in experimentally-measured forearm fracture load with prediction errors <6.8% and precision errors <5.0%., Interpretation: Failure load estimates of distal radius sections can reliably estimate forearm fracture load experienced during a fall. Forearm fracture load estimates can be used to improve factor-of-risk predictions for forearm fracture., (Copyright © 2020. Published by Elsevier Ltd.)

Postelection surveys regularly overestimate voter turnout by 10 points or more. This article provides the first comprehensive documentation of the turnout gap in three major ongoing surveys (the General Social Survey, Current Population Survey, and American National Election Studies), evaluates explanations for it, interprets its significance, and suggests means to continue evaluating and improving survey measurements of turnout. Accuracy was greater in face-to-face than telephone interviews, consistent with the notion that the former mode engages more respondent effort with less social desirability bias. Accuracy was greater when respondents were asked about the most recent election, consistent with the hypothesis that forgetting creates errors. Question wordings designed to minimize source confusion and social desirability bias improved accuracy. Rates of reported turnout were lower with proxy reports than with self-reports, which may suggest greater accuracy of proxy reports. People who do not vote are less likely to participate in surveys than voters are., Competing Interests: Declaration of Conflicting Interests The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Off-axis loading associated with a fall onto the outstretched hand has been hypothesized to induce distal radius failure at lower magnitudes than axially directed loading commonly used in biomechanical models for estimating fracture risk. However, this hypothesis has not been tested with side-to-side experimental testing. The objective of this study was to compare distal radius failure loads between forearm pairs experimentally tested in an axial or off-axis loading configuration. We acquired 18 pairs of cadaveric forearms from 18 female donors (mean age (standard deviation): 84.4 (7.9) years). Each forearm pair was tested to failure using either an axial compression test (vertical orientation with 0° dorsal inclination, 3°-6° radial inclination) or an off-axis test corresponding to the hand position during a fall (15° dorsal inclination, 3°-6° radial inclination). Failure testing was performed at 3 mm/s onto the palm of the hand until fracture occurred. Of the 18 pairs, 11 sustained a distal radius fracture. We compared failure loads between the two groups using a paired t test. Results indicated that failure load under off-axis loading was 29% lower than failure load under axial compressive loading (mean difference: -0.31 kN; 95% confidence interval: -0.47 to -0.16 kN, P = .001). In conclusion, off-axis loading associated with a fall onto the outstretched hand resulted in a 29% lower failure load. Integrating an off-axis loading configuration into current biomechanical models of distal radius bone strength may prevent overestimating of failure load and may offer a clinically relevant option to estimate distal radius fracture risk and monitor therapy efficacy., (© 2020 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.)

Converging evidence demonstrates an important role for gangliosides in brain function and neurodegenerative diseases. Exogenous GM1 is broadly neuroprotective, including in rodent, feline, and primate models of Parkinson's disease, and has shown positive effects in clinical trials. We and others have shown that inhibition of the ganglioside biosynthetic enzyme GD3 synthase (GD3S) increases endogenous levels GM1 ganglioside. We recently reported that targeted deletion of St8sia1, the gene that codes for GD3S, prevents motor impairments and significantly attenuates neurodegeneration induced by 1-methy-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). The current study investigated the effects of GD3S inhibition on the neurotoxicity and parkinsonism induced by MPTP. Mice were injected intrastriatally with a lentiviral-vector-mediated shRNA construct targeting GD3S (shGD3S) or a scrambled-sequence control (scrRNA). An MPTP regimen of 18 mg/kg x 5 days reduced tyrosine-hydroxylase-positive neurons in the substantia nigra pars compacta of scrRNA-treated mice by nearly two-thirds. In mice treated with shGD3S the MPTP-induced lesion was approximately half that size. MPTP induced bradykinesia and deficits in fine motor skills in mice treated with scrRNA. These deficits were absent in shGD3S-treated mice. These results suggest that inhibition of GD3S protects against the nigrostriatal damage, bradykinesia, and fine-motor-skill deficits associated with MPTP administration., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Alzheimer's disease (AD) is the most common form of age-associated dementia characterized by amyloid-β plaques and neurofibrillary tangles. Recent studies have demonstrated that thioredoxin-interacting protein (TXNIP), an endogenous regulator of redox/glucose induced stress and inflammation, is now known to be upregulated in stroke, traumatic brain injury, diabetes and AD. We hypothesized that TXNIP overexpression sustains neurodegeneration through activation of the nucleotide binding and oligomerization domain-like receptor protein 3 in human AD brains. We analyzed TXNIP and the components of the NLRP3 inflammasome in the cortex of postmortem human brain samples by western blotting, real-time PCR, and immunohistochemical techniques in comparison with age-matched non-demented controls. Our results demonstrate that TXNIP protein as well as its mRNA levels in the cortex was significantly upregulated in AD compared to control brains. Moreover, using double immunofluorescence staining, TXNIP and interlukin-1β (IL-1β) were co-localized near Aβ plaques and p-tau. These results suggest an association between TXNIP overexpression levels and AD pathogenesis. Further, a significant increased expression of cleaved caspase-1 and IL-1β, the products of inflammasome activation, was detected in the cortex of AD brains. Together, these findings suggest that TXNIP, an upstream promising new therapeutic target, is a molecular link between inflammation and AD. The significant contribution of TXNIP to AD pathology suggests that strategies focusing on specific targeting of the TXNIP-NLRP3 inflammasome may lead to novel therapies for the management of AD and other age-related dementias.

We demonstrate interferometric scattering (iSCAT) microscopy, a method capable of detecting single unlabeled proteins secreted from individual living cells in real time. In this protocol, we cover the fundamental steps to realize an iSCAT microscope and complement it with additional imaging channels to monitor the viability of a cell under study. Following this, we use the method for real-time detection of single proteins as they are secreted from a living cell which we demonstrate with an immortalized B-cell line (Laz388). Necessary steps concerning the preparation of microscope and sample as well as the analysis of the recorded data are discussed. The video protocol demonstrates that iSCAT microscopy offers a straightforward method to study secretion at the single-molecule level.

Environmental exposure to air pollution has been linked to a number of health problems including organ rejection, lung damage and inflammation. While the deleterious effects of air pollution in adult animals are well documented, the long-term consequences of particulate matter (PM) exposure during animal development are uncertain. In this study we tested the hypothesis that environmental exposure to PM 2.5 μm in diameter in utero promotes long term inflammation and neurodegeneration. We evaluated the behavior of PM exposed animals using several tests and observed deficits in spatial memory without robust changes in anxiety-like behavior. We then examined how this affects the brains of adult animals by examining proteins implicated in neurodegeneration, synapse formation and inflammation by western blot, ELISA and immunohistochemistry. These tests revealed significantly increased levels of COX2 protein in PM2.5 exposed animal brains in addition to changes in synaptophysin and Arg1 proteins. Exposure to PM2.5 also increased the immunoreactivity for GFAP, a marker of activated astrocytes. Cytokine concentrations in the brain and spleen were also altered by PM2.5 exposure. These findings indicate that in utero exposure to particulate matter has long term consequences which may affect the development of both the brain and the immune system in addition to promoting inflammatory change in adult animals., (Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Cellular secretion of proteins into the extracellular environment is an essential mediator of critical biological mechanisms, including cell-to-cell communication, immunological response, targeted delivery, and differentiation. Here, we report a novel methodology that allows for the real-time detection and imaging of single unlabeled proteins that are secreted from individual living cells. This is accomplished via interferometric detection of scattered light (iSCAT) and is demonstrated with Laz388 cells, an Epstein-Barr virus (EBV)-transformed B cell line. We find that single Laz388 cells actively secrete IgG antibodies at a rate of the order of 100 molecules per second. Intriguingly, we also find that other proteins and particles spanning ca. 100 kDa-1 MDa are secreted from the Laz388 cells in tandem with IgG antibody release, likely arising from EBV-related viral proteins. The technique is general and, as we show, can also be applied to studying the lysate of a single cell. Our results establish label-free iSCAT imaging as a powerful tool for studying the real-time exchange between cells and their immediate environment with single-protein sensitivity.

The growth of academic international medicine (AIM) as a distinct field of expertise resulted in increasing participation by individual and institutional actors from both high-income and low-and-middle-income countries. This trend resulted in the gradual evolution of international medical programs (IMPs). With the growing number of students, residents, and educators who gravitate toward nontraditional forms of academic contribution, the need arose for a system of formalized metrics and quantitative assessment of AIM- and IMP-related efforts. Within this emerging paradigm, an institution's "return on investment" from faculty involvement in AIM and participation in IMPs can be measured by establishing equivalency between international work and various established academic activities that lead to greater institutional visibility and reputational impact. The goal of this consensus statement is to provide a basic framework for quantitative assessment and standardized metrics of professional effort attributable to active faculty engagement in AIM and participation in IMPs. Implicit to the current work is the understanding that the proposed system should be flexible and adaptable to the dynamically evolving landscape of AIM - an increasingly important subset of general academic medical activities., Competing Interests: There are no conflicts of interest.

Induction of neuroprotective heat-shock proteins via pharmacological Hsp90 inhibitors is currently being investigated as a potential treatment for neurodegenerative diseases. Two major hurdles for therapeutic use of Hsp90 inhibitors are systemic toxicity and limited central nervous system permeability. We demonstrate here that chronic treatment with a proprietary Hsp90 inhibitor compound (OS47720) not only elicits a heat-shock-like response but also offers synaptic protection in symptomatic Tg2576 mice, a model of Alzheimer's disease, without noticeable systemic toxicity. Despite a short half-life of OS47720 in mouse brain, a single intraperitoneal injection induces rapid and long-lasting (>3 days) nuclear activation of the heat-shock factor, HSF1. Mechanistic study indicates that the remedial effects of OS47720 depend upon HSF1 activation and the subsequent HSF1-mediated transcriptional events on synaptic genes. Taken together, this work reveals a novel role of HSF1 in synaptic function and memory, which likely occurs through modulation of the synaptic transcriptome.

Parkinson's disease is a debilitating neurodegenerative condition for which there is no cure. Converging evidence implicates gangliosides in the pathogenesis of several neurodegenerative diseases, suggesting a potential new class of therapeutic targets. We have shown that interventions that simultaneously increase the neuroprotective GM1 ganglioside and decrease the pro-apoptotic GD3 ganglioside - such as inhibition of GD3 synthase (GD3S) or administration of sialidase - are neuroprotective in vitro and in a number of preclinical models. In this study, we investigated the effects of GD3S deletion on parkinsonism induced by 1-methyl-4phenyl-1,2,3,6-tetrahydropyridine (MPTP). MPTP was administered to GD3S-/- mice or controls using a subchronic regimen consisting of three series of low-dose injections (11 mg/kg/day × 5 days each, 3 weeks apart), and motor function was assessed after each. The typical battery of tests used to assess parkinsonism failed to detect deficits in MPTP-treated mice. More sensitive measures - such as the force-plate actimeter and treadmill gait parameters - detected subtle effects of MPTP, some of which were absent in mice lacking GD3S. In wild-type mice, MPTP destroyed 53% of the tyrosine-hydroxylase (TH)-positive neurons in the substantia nigra pars compacta (SNc) and reduced striatal dopamine 60.7%. In contrast, lesion size was only 22.5% in GD3S-/- mice and striatal dopamine was reduced by 37.2%. Stereological counts of Nissl-positive SNc neurons that did not express TH suggest that neuroprotection was complete but TH expression was suppressed in some cells. These results show that inhibition of GD3S has neuroprotective properties in the MPTP model and may warrant further investigation as a therapeutic target., (© 2017 John Wiley & Sons Ltd and International Behavioural and Neural Genetics Society.)

Fluorescence intermittency or blinking is observed in nearly all nanoscale fluorophores. It is characterized by universal power-law distributions in on- and off-times as well as 1/f behaviour in corresponding emission power spectral densities. Blinking, previously seen in confined zero- and one-dimensional systems has recently been documented in two-dimensional reduced graphene oxide. Here we show that unexpected blinking during graphene oxide-to-reduced graphene oxide photoreduction is attributed, in large part, to the redistribution of carbon sp 2 domains. This reclustering generates fluctuations in the number/size of emissive graphenic nanoclusters wherein multiscale modelling captures essential experimental aspects of reduced graphene oxide's absorption/emission trajectories, while simultaneously connecting them to the underlying photochemistry responsible for graphene oxide's reduction. These simulations thus establish causality between currently unexplained, long timescale emission intermittency in a quantum mechanical fluorophore and identifiable chemical reactions that ultimately lead to switching between on and off states.

Recent advances in semiconductor nanostructure syntheses provide unprecedented control over electronic quantum confinement and have led to extensive investigations of their size- and shape-dependent optical/electrical properties. Notably, spectroscopic measurements show that optical bandgaps of one-dimensional CdSe nanowires are substantially (approximately 100 meV) lower than their zero-dimensional counterparts for equivalent diameters spanning 5-10 nm. But what, exactly, dictates the dimensional crossover of a semiconductor's electronic structure? Here we probe the one-dimensional to zero-dimensional transition of CdSe using single nanowire/nanorod absorption spectroscopy. We find that carrier electrostatic interactions play a fundamental role in establishing dimensional crossover. Moreover, the critical length at which this transition occurs is governed by the aspect ratio-dependent interplay between carrier confinement and dielectric contrast/confinement energies.

In Parkinson's disease, cognitive deficits manifest as fronto-striatally-mediated executive dysfunction, with impaired attention, planning, judgment, and impulse control. We examined changes in executive function in mice lesioned with subchronic 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) using a 3-choice serial reaction-time (SRT) task, which included measures of sustained attention and impulse control. Each trial of the baseline SRT task comprised a pseudo-random pre-cue period ranging from 3 to 8 s, followed by a 1-s cue duration. MPTP impaired all measures of impulsive behavior acutely, but with additional training their performance normalized to saline control levels. When challenged with shorter cue durations, MPTP-lesioned mice had significantly slower reaction times than wild-type mice. When challenged with longer pre-cue times, the MPTP-lesioned mice exhibited a loss of impulse control at the longer durations. In lesioned mice, striatal dopamine was depleted by 54% and the number of tyrosine-hydroxylase-positive neurons in the substantia nigra pars compacta was reduced by 75%. Serotonin (5-HT) was unchanged in the striatum and prefrontal cortex (PFC), but the ratio of 5-hydroxyindolacetic acid (5-HIAA) to 5-HT was significantly reduced in the MPTP group in the PFC. In lesioned mice, prefrontal 5-HIAA/5-HT was significantly correlated with the executive impairments and striatal norepinephrine was associated with slower reaction times. None of the neurochemical measures was significantly associated with behavior in saline-treated controls. Taken together, these results show that prefrontal 5-HT turnover may play a pivotal role in MPTP-induced executive dysfunction., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Dextromethorphan (DXM) is a widely available antitussive that has, at elevated dose levels, euphoric and dissociative effects. This article presents the reported patterns and preferences of DXM use, and perceptions of DXM use among adult members of an online DXM community. Analyses were conducted of quantitative and qualitative responses from nine female and 43 male individuals, aged 18-63 years old. All respondents reported illegal and DXM drug use, beginning, on average, at 15.7 and 17.1 years of age, respectively. The majority of respondents first heard about DXM online or from a friend, preferred to use DXM alone, ingested substances concurrently with DXM to modify its effects, had not been to an emergency room or arrested because of their DXM use, and used DXM for its dissociative and mind-altering effects. DXM was perceived as safe and in no need of further regulation with only 14% of respondents mentioning DXM's addictive qualities. Findings from this sample of adult DXM users reveal a sophisticated subculture in which users report using DXM specifically to induce changes to their mental state and use a variety of substances to modify or enhance DXM's effects.

We provide, for the first time, direct experimental evidence for heterogeneous blinking in reduced graphene oxide (rGO) during photolysis. The spatially resolved intermittency originates from regions within individual rGO sheets and shows 1/f-like power spectral density. We describe the evolution of rGO blinking using the multiple recombination center (MRC) model that captures common features of nanoscale blinking. Our results illustrate the universal nature of blinking and suggest a common microscopic origin for the effect.

The structure of dendritic spines determines synaptic efficacy, a plastic process that mediates information processing in the vertebrate nervous system. Aberrant spine morphology, including alterations in shape, size, and number, are common in different brain diseases. Because of this, accurate and unbiased characterization of dendritic spine structure is vital to our ability to explore and understand their involvement in neuronal development, synaptic plasticity, and synaptic failure in neurological diseases. Investigators have attempted to elucidate the precise structure and function of dendritic spines for more than a hundred years, but their fundamental role in synaptic plasticity and neurological diseases remains elusive. Limitations and ambiguities in imaging techniques have exacerbated the challenges of acquiring accurate information about spines and spine features. However, recent advancements in molecular biology, protein engineering, immuno-labeling techniques, and the use of super-resolution nano-microscopy along with powerful image analysis software have provided a better understanding of dendritic spine architecture. Here we describe the pros and cons of the classical staining techniques used to study spine morphology, and the alteration of dendritic spines in various neuropathological conditions. Finally, we highlight recent advances in super-resolved nanoscale microscopy, and their potentials and pitfalls when used to explore dendritic spine dynamics., (Copyright © 2015 Elsevier Ireland Ltd and the Japan Neuroscience Society. All rights reserved.)

Background: Cerebral infarction due to thrombosis leads to the most common type of stroke and a likely cause of age-related cognitive decline and dementia. Endothelial nitric oxide synthase (eNOS) generates NO, which plays a crucial role in maintaining vascular function and exerting an antithrombotic action. Reduced eNOS expression and eNOS polymorphisms have been associated with stroke and Alzheimer's disease (AD), the most common type of dementia associated with neurovascular dysfunction. However, direct proof of such association is lacking. Since there are no reports of complete eNOS deficiency in humans, we used heterozygous eNOS(+/-) mice to mimic partial deficiency of eNOS, and determine its impact on cerebrovascular pathology and perfusion of cerebral vessels., Results: Combining cerebral angiography with immunohistochemistry, we found thrombotic cerebral infarctions in eNOS(+/-) mice as early as 3-6 months of age but not in eNOS(+/+) mice at any age. Remarkably, vascular occlusions in eNOS(+/-) mice were found almost exclusively in three areas: temporoparietal and retrosplenial granular cortexes, and hippocampus this distribution precisely matching the hypoperfused areas identified in preclinical AD patients. Moreover, progressive cerebral amyloid angiopaphy (CAA), blood brain barrier (BBB) breakdown, and cognitive impairment were also detected in aged eNOS(+/-) mice., Conclusions: These data provide for the first time the evidence that partial eNOS deficiency results in spontaneous thrombotic cerebral infarctions that increase with age, leading to progressive CAA and cognitive impairments. We thus conclude that eNOS(+/-) mouse may represent an ideal model of ischemic stroke to address early and progressive damage in spontaneously-evolving chronic cerebral ischemia and thus, study vascular mechanisms contributing to vascular dementia and AD.

Physical exercise may provide protection against the cognitive decline and neuropathology associated with Alzheimer's disease, although the mechanisms are not clear. In the present study, APP/PSEN1 double-transgenic and wild-type mice were allowed unlimited voluntary exercise for 7months. Consistent with previous reports, wheel-running improved cognition in the double-transgenic mice. Interestingly, the average daily distance run was strongly correlated with spatial memory in the water maze in wild-type mice (r(2)=.959), but uncorrelated in transgenics (r(2)=.013). Proteomics analysis showed that sedentary transgenic mice differed significantly from sedentary wild-types with respect to proteins involved in synaptic transmission, cytoskeletal regulation, and neurogenesis. When given an opportunity to exercise, the transgenics' deficiencies in cytoskeletal regulation and neurogenesis largely normalized, but abnormal synaptic proteins did not change. In contrast, exercise enhanced proteins associated with cytoskeletal regulation, oxidative phosphorylation, and synaptic transmission in wild-type mice. Soluble and insoluble Aβ40 and Aβ42 levels were significantly decreased in both cortex and hippocampus of active transgenics, suggesting that this may have played a role in the cognitive improvement in APP/PSEN1 mice. β-secretase was significantly reduced in active APP/PSEN1 mice compared to sedentary controls, suggesting a mechanism for reduced Aβ. Taken together, these data illustrate that exercise improves memory in wild-type and APP-overexpressing mice in fundamentally different ways., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Laser reduction of graphene oxide (GO) offers unique opportunities for the rapid, nonchemical production of graphene. By tuning relevant reduction parameters, the band gap and conductivity of reduced GO can be precisely controlled. In situ monitoring of single layer GO reduction is therefore essential. In this report, we show the direct observation of laser-induced, single layer GO reduction through correlated changes to its absorption and emission. Absorption/emission movies illustrate the initial stages of single layer GO reduction, its transition to reduced-GO (rGO) as well as its subsequent decomposition upon prolonged laser illumination. These studies reveal GO's photoreduction life cycle and through it native GO/rGO absorption coefficients, their intrasheet distributions as well as their spatial heterogeneities. Extracted absorption coefficients for unreduced GO are α405 nm ≈ 6.5 ± 1.1 × 10(4) cm(-1), α520 nm ≈ 2.1 ± 0.4 × 10(4) cm(-1), and α640 nm ≈ 1.1 ± 0.3 × 10(4) cm(-1) while corresponding rGO α-values are α405 nm ≈ 21.6 ± 0.6 × 10(4) cm(-1), α520 nm ≈ 16.9 ± 0.4 × 10(4) cm(-1), and α640 nm ≈ 14.5 ± 0.4 × 10(4) cm(-1). More importantly, the correlated absorption/emission imaging provides us with unprecedented insight into GO's underlying photoreduction mechanism, given our ability to spatially resolve its kinetics and to connect local rate constants to activation energies. On a broader level, the developed absorption imaging is general and can be applied toward investigating the optical properties of other two-dimensional materials, especially those that are nonemissive and are invisible to current single molecule optical techniques.

A recent study reported lower anxiety in the 5xFAD transgenic mouse model of Alzheimer's disease, as measured by reduced time on the open arms of an elevated plus maze. This is important because all behaviors in experimental animals must be interpreted in light of basal anxiety and response to novel environments. We conducted a comprehensive anxiety battery in the 5xFAD transgenics and replicated the plus-maze phenotype. However, we found that it did not reflect reduced anxiety, but rather abnormal avoidance of the closed arms on the part of transgenics and within-session habituation to the closed arms on the part of wild-type controls. We noticed that the 5xFAD transgenics did not engage in the whisker-barbering behavior typical of mice of this background strain. This is suggestive of abnormal social behavior, and we suspected it might be related to their avoidance of the closed arms on the plus maze. Indeed, transgenic mice exhibited excessive home-cage social behavior and impaired social recognition, and did not permit barbering by wild-type mice when pair-housed. When their whiskers were snipped the 5xFAD transgenics no longer avoided the closed arms on the plus maze. Examination of parvalbumin (PV) staining showed a 28.9% reduction in PV+ inhibitory interneurons in the barrel fields of 5xFAD mice, and loss of PV+ fibers in layers IV and V. This loss of vibrissal inhibition suggests a putatively aversive overstimulation that may be responsible for the transgenics' avoidance of the closed arms in the plus maze., (© 2014 John Wiley & Sons Ltd and International Behavioural and Neural Genetics Society.)

We show the general functionalization of cotton fabrics using solution-synthesized CdSe and CdTe nanowires (NWs). Conformal coatings onto individual cotton fibers have been achieved through various physical and chemical approaches. Some involve the electrostatic attraction of NWs to cotton charged positively with a Van de Graaff generator or via 2,3-epoxypropyltrimethylammonium chloride treatments. Resulting NW-functionalized textiles consist of dense, conformal coatings and have been characterized for their UV-visible absorption as well as Raman activity. We demonstrate potential uses of these functionalized textiles through two proof-of-concept applications. The first entails barcoding cotton using the unique Raman signature of the NWs. We also demonstrate the surface-enhancement of their Raman signatures using codeposited Au. A second demonstration takes advantage of the photoconductive nature of semiconductor NWs to create cotton-based photodetectors. Apart from these illustrations, NW-functionalized cotton textiles may possess other uses in the realm of medical, anticounterfeiting, and photocatalytic applications.

Supercontinuum spatial modulation spectroscopy is a facile tool for conducting single molecule/particle extinction spectroscopy throughout the visible and near infrared (420-1100 nm). The technique's capabilities are benchmarked using individual Au nanoparticles (NPs) as a standard since they are well studied and display a prominent plasmon resonance in the visible. Extinction spectra of individual Au NPs with diameters (d) ranging from d ~ 8 to 40 nm are resolved with extinction cross sections (σ(ext)) of σ(ext) ~ 1 × 10(-13)-1 × 10(-11) cm(2). Corresponding signal-to-noise ratios range from ~30 to ~1400. The technique's limit of detection is determined to be 4.3 × 10(-14) cm(2) (4.3 nm(2)). To showcase supercontinuum spatial modulation spectroscopy's broader applicability, extinction spectra are acquired for other model systems, such as individual single-walled carbon nanotubes (SWCNTs) and CdSe nanowires. We show for the first time extinction spectra of individual (8,3) and (6,5) SWCNTs. For both chiralities, their E11 [(8,3) 1.30 eV (952 nm); (6,5) 1.26 eV (986 nm)] and E22 [(8,3) 1.86 eV (667 nm); (6,5) 2.19 eV (567 nm)] excitonic resonances are seen with corresponding cross sections of σ(ext) ~ 10(-13) cm(2) μm(-1).

In order to examine the potential involvement of gangliosides in AD (Alzheimer's disease), we compared the ganglioside compositions of the brains of a double-transgenic (Tg) mouse model [APP (amyloid precursor protein)/PSEN1 (presenilin)] of AD and a triple mutant mouse model with an additional deletion of the GD3S (GD3-synthase) gene (APP/PSEN1/GD3S(-/-)). These animals were chosen since it was previously reported that APP/PSEN1/GD3S(-/-) triple-mutant mice performed as well as WT (wild-type) control and GD3S(-/-) mice on a number of reference memory tasks. Cholinergic neuron-specific gangliosides, such as GT1aα and GQ1bα, were elevated in the brains of double-Tg mice (APP/PSEN1), as compared with those of WT mice. Remarkably, in the triple mutant mouse brains (APP/PSEN1/GD3S(-/-)), the concentration of GT1aα was elevated and as expected there was no expression of GQ1bα. On the other hand, the level of c-series gangliosides, including GT3, was significantly reduced in the double-Tg mouse brain as compared with the WT. Thus, the disruption of the gene of a specific ganglioside-synthase, GD3S, altered the expression of cholinergic neuron-specific gangliosides. Our data thus suggest the intriguing possibility that the elevated cholinergic-specific ganglioside, GT1aα, in the triple mutant mouse brains (APP/PSEN1/GD3S(-/-)) may contribute to the memory retention in these mice.

Erythropoietin (Epo) is neuroprotective in a number of preparations, but can lead to unacceptably high and even lethal hematocrit levels. Recent reports show that modified Epo variants confer neuroprotection in models of glaucoma and retinal degeneration without raising hematocrit. In this study, neuroprotective effects of two Epo variants (EpoR76E and EpoS71E) were assessed in a model of Parkinson's disease. The constructs were packaged in recombinant adeno-associated viral (rAAV) vectors and injected intramuscularly. After 3 weeks, mice received five daily injections of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and were killed 5 weeks later. The MPTP-lesioned mice pretreated with rAAV.eGFP (negative control) exhibited a 7- to 9-Hz tremor and slower latencies to move on a grid test (akinesia). Both of these symptomatic features were absent in mice pretreated with either modified Epo construct. The rAAV.eGFP-treated mice lesioned with MPTP exhibited a 41% reduction in tyrosine hydroxylase (TH)-positive neurons in the substantia nigra. The rAAV.EpoS71E construct did not protect nigral neurons, but neuronal loss in mice pretreated with rAAV.EpoR76E was only half that of rAAV.eGFP controls. Although dopamine levels were normal in all groups, 3,4-dihydroxyphenylacetic acid (DOPAC) was significantly reduced only in MPTP-lesioned mice pretreated with rAAV.eGFP, indicating reduced dopamine turnover. Analysis of TH-positive fibers in the striatum showed normalized density in MPTP-lesioned mice pretreated with rAAV.EpoS71E, suggesting that enhanced sprouting induced by EpoS71E may have been responsible for normal behavior and dopaminergic tone in these mice. These results show that systemically administered rAAV-generated non-erythropoietic Epo may protect against MPTP-induced parkinsonism by a combination of neuroprotection and enhanced axonal sprouting., (© 2012 The Authors. Genes, Brain and Behavior © 2012 Blackwell Publishing Ltd and International Behavioural and Neural Genetics Society.)

The electrostatic alignment and directed assembly of semiconductor nanowires into macroscopic, centimeter-long yarns is demonstrated. Different morphologies can be produced, including longitudinally segmented/graded yarns or mixed composition fibers. Nanowire yarns display long range photoconductivities and open up exciting opportunities for potential use in future nanowire-based textiles or in solar photovoltaics., (Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Graphene oxide (GO) is an important precursor in the production of chemically derived graphene. During reduction, GO's electrical conductivity and band gap change gradually. Doping and chemical functionalization are also possible, illustrating GO's immense potential in creating functional devices through control of its local hybridization. Here we show that laser-induced photolysis controllably reduces individual single-layer GO sheets. The reaction can be followed in real time through sizable decreases in GO's photoluminescence efficiency along with spectral blueshifts. As-produced reduced graphene oxide (rGO) sheets undergo additional photolysis, characterized by dramatic emission enhancements and spectral redshifts. Both GO's reduction and subsequent conversion to photobrightened rGO are captured through movies of their photoluminescence kinetics. Rate maps illustrate sizable spatial and temporal heterogeneities in sp(2) domain growth and reveal how reduction "flows" across GO and rGO sheets. The observed heterogeneous reduction kinetics provides mechanistic insight into GO's conversion to chemically derived graphene and highlights opportunities for overcoming its dynamic, chemical disorder.

The origin of sizable absorption polarization anisotropies (ρabs) in one-dimensional (1D) semiconductor nanowires (NWs) has been debated. Invoked explanations employ either classical or quantum mechanical origins, where the classical approach suggests dielectric constant mismatches between the NW and its surrounding environment as the predominant source of observed polarization sensitivities. At the same time, the confinement-influenced mixing of states suggests a sizable contribution from polarization-sensitive transition selection rules. Sufficient evidence exists in the literature to support either claim. However, in all cases, these observations stem from excitation polarization anisotropy (ρexc) studies, which only indirectly measure ρabs. In this manuscript, we directly measure the band edge extinction polarization anisotropies (ρext) of individual CdSe NWs using single NW extinction spectroscopy. Observed polarization anisotropies possess distinct spectral features and wavelength dependencies that correlate well with theoretical transition selection rules derived from a six-band k·p theory used to model the electronic structure of CdSe NWs.

Here we show the first direct extinction spectra of single one-dimensional (1D) semiconductor nanostructures obtained at room temperature utilizing a spatial modulation approach. (1) For these materials, ensemble averaging in conventional extinction spectroscopy has limited our understanding of the interplay between carrier confinement and their electrostatic interactions. (2-4) By probing individual CdSe nanowires (NWs), we have identified and assigned size-dependent exciton transitions occurring across the visible. In turn, we have revealed the existence of room temperature 1D excitons in the narrowest NWs.

Converging evidence shows that GD3 ganglioside is a critical effector in a number of apoptotic pathways, and GM1 ganglioside has neuroprotective and noötropic properties. Targeted deletion of GD3 synthase (GD3S) eliminates GD3 and increases GM1 levels. Primary neurons from GD3S-/- mice are resistant to neurotoxicity induced by amyloid-β or hyperhomocysteinemia, and when GD3S is eliminated in the APP/PSEN1 double-transgenic model of Alzheimer's disease the plaque-associated oxidative stress and inflammatory response are absent. To date, no small-molecule inhibitor of GD3S exists. In the present study we used sialidase from Vibrio cholerae (VCS) to produce a brain ganglioside profile that approximates that of GD3S deletion. VCS hydrolyzes GD1a and complex b-series gangliosides to GM1, and the apoptogenic GD3 is degraded. VCS was infused by osmotic minipump into the dorsal third ventricle in mice over a 4-week period. Sensorimotor behaviors, anxiety, and cognition were unaffected in VCS-treated mice. To determine whether VCS was neuroprotective in vivo, we injected kainic acid on the 25th day of infusion to induce status epilepticus. Kainic acid induced a robust lesion of the CA3 hippocampal subfield in aCSF-treated controls. In contrast, all hippocampal regions in VCS-treated mice were largely intact. VCS did not protect against seizures. These results demonstrate that strategic degradation of complex gangliosides and GD3 can be used to achieve neuroprotection without adversely affecting behavior.

The accumulation of Aβ (amyloid β-protein) is one of the major pathological hallmarks in AD (Alzheimer's disease). Gangliosides, sialic acid-containing glycosphingolipids enriched in the nervous system and frequently used as biomarkers associated with the biochemical pathology of neurological disorders, have been suggested to be involved in the initial aggregation of Aβ. In the present study, we have examined ganglioside metabolism in the brain of a double-Tg (transgenic) mouse model of AD that co-expresses mouse/human chimaeric APP (amyloid precursor protein) with the Swedish mutation and human presenilin-1 with a deletion of exon 9. Although accumulation of Aβ was confirmed in the double-Tg mouse brains and sera, no statistically significant change was detected in the concentration and composition of major ganglio-N-tetraosyl-series gangliosides in the double-Tg brain. Most interestingly, Chol-1α antigens (cholinergic neuron-specific gangliosides), such as GT1aα and GQ1bα, which are minor species in the brain, were found to be increased in the double-Tg mouse brain. We interpret that the occurrence of these gangliosides may represent evidence for generation of cholinergic neurons in the AD brain, as a result of compensatory neurogenesis activated by the presence of Aβ.

Vitamin C is a powerful antioxidant and its levels are decreased in Alzheimer's patients. Even sub-clinical vitamin C deficiency could impact disease development. To investigate this principle we crossed APP/PSEN1 transgenic mice with Gulo knockout mice unable to synthesize their own vitamin C. Experimental mice were maintained from 6 weeks of age on standard (0.33 g/L) or reduced (0.099 g/L) levels of vitamin C and then assessed for changes in behavior and neuropathology. APP/PSEN1 mice showed impaired spatial learning in the Barnes maze and water maze that was not further impacted by vitamin C level. However, long-term decreased vitamin C levels led to hyperactivity in transgenic mice, with altered locomotor habituation and increased omission errors in the Barnes maze. Decreased vitamin C also led to increased oxidative stress. Transgenic mice were more susceptible to the activity-enhancing effects of scopolamine and low vitamin C attenuated these effects in both genotypes. These data indicate an interaction between the cholinergic system and vitamin C that could be important given the cholinergic degeneration associated with Alzheimer's disease., (Copyright 2009 Elsevier Inc. All rights reserved.)

Gangliosides have been shown to be necessary for beta-amyloid (Abeta) binding and aggregation. GD3 synthase (GD3S) is responsible for biosynthesis of the b- and c-series gangliosides, including two of the four major brain gangliosides. We examined Abeta-ganglioside interactions in neural tissue from mice lacking the gene coding for GD3S (St8sia1), and in a double-transgenic (APP/PSEN1) mouse model of Alzheimer's disease cross-bred with GD3S-/- mice. In primary neurons and astrocytes lacking GD3S, Abeta-induced cell death and Abeta aggregation were inhibited. Like GD3S-/- and APP/PSEN1 double-transgenic mice, APP/PSEN1/GD3S-/- "triple-mutant" mice are indistinguishable from wild-type mice on casual examination. APP/PSEN1 double-transgenics exhibit robust impairments on a number of reference-memory tasks. In contrast, APP/PSEN1/GD3S-/- triple-mutant mice performed as well as wild-type control and GD3S-/- mice. Consistent with the behavioral improvements, both aggregated and unaggregated Abeta and associated neuropathology were almost completely eliminated in triple-mutant mice. These results suggest that GD3 synthase may be a novel therapeutic target to combat the cognitive deficits, amyloid plaque formation, and neurodegeneration that afflict Alzheimer's patients.

The present study investigated the relationships among oxidative stress, beta-amyloid and cognitive abilities in the APP/PSEN1 double-transgenic mouse model of Alzheimer's disease. In two experiments, long-term dietary supplements were given to aged APP/PSEN1 mice containing vitamin C alone (1 g/kg diet; Experiment 1) or in combination with a high (750 IU/kg diet, Experiments 1 and 2) or lower (400 IU/kg diet, Experiment 2) dose of vitamin E. Oxidative stress, measured by F(4)-neuroprostanes or malondialdehyde, was elevated in cortex of control-fed APP/PSEN1 mice and reduced to wild-type levels by vitamin supplementation. High-dose vitamin E with C was less effective at reducing oxidative stress than vitamin C alone or the low vitamin E+C diet combination. The high-dose combination also impaired water maze performance in mice of both genotypes. In Experiment 2, the lower vitamin E+C treatment attenuated spatial memory deficits in APP/PSEN1 mice and improved performance in wild-type mice in the water maze. Amyloid deposition was not reduced by antioxidant supplementation in either experiment.

Alzheimer's disease is a progressive and fatal neurodegenerative disease characterized by a build up of amyloid beta (Abeta) deposits, elevated oxidative stress, and deterioration of the cholinergic system. The present study investigated short-term cognitive-enhancing effects of acute intraperitoneal (i.p.) Vitamin C (ascorbate) treatment in APP/PSEN1 mice, a mouse model of Alzheimer's disease. Middle-aged (12 months) and very old (24 months) APP/PSEN1 bigenic and wild-type mice were treated with ascorbate (125 mg/kg i.p.) or the vehicle 1 h before testing on Y-maze spontaneous alternation and Morris water maze tasks. Very old mice performed more poorly on cognitive tasks than middle-aged mice. Ascorbate treatment improved Y-maze alternation rates and swim accuracy in the water maze in both wild-type and APP/PSEN1 mice. Abeta deposits and oxidative stress both increased with age, and acetylcholinesterase (AChE) activity was significantly reduced in APP/PSEN1 compared to wild-type mice. However, the short course of acute ascorbate treatment did not alter Alzheimer-like neuropathological features of plaque deposition, oxidative stress, or AChE activity. These data suggest that ascorbate may have noötropic functions when administered parenterally in high doses and that the mode of action is via an acute, pharmacological-like mechanism that likely modulates neurotransmitter function.

The effects of abnormally high or low stress on learning are well established. The Barnes maze and Morris water maze are two commonly used tests of spatial memory, of which the water maze is considered more stressful; however, until now this has not been demonstrated empirically. In the present study, mice matched for performance on commonly used anxiety tasks were trained on either the Barnes maze or water maze or received no cognitive testing. Water-maze training induced greater increases in plasma corticosterone than did Barnes maze training, assessed 30 min after the final session. Importantly, spatial learning was inversely correlated with corticosterone levels in the water maze but not the Barnes maze, suggesting that performance on the water maze may be more affected by test-induced stress even within wild-type subjects of the same age and gender. These findings are important when considering the appropriate cognitive tasks for any experiment in which stress responses may differ systematically across groups.

Recent studies have revealed that disruption of vitamin A signaling observed in Alzheimer's disease (AD) leads to beta-amyloid (Abeta) accumulation and memory deficits in rodents. The aim of the present study was to evaluate the therapeutic effect of all-trans retinoic acid (ATRA), an active metabolite of vitamin A, on the neuropathology and deficits of spatial learning and memory in amyloid precursor protein (APP) and presenilin 1 (PS1) double-transgenic mice, a well established AD mouse model. Here we report a robust decrease in brain Abeta deposition and tau phosphorylation in the blinded study of APP/PS1 transgenic mice treated intraperitoneally for 8 weeks with ATRA (20 mg/kg, three times weekly, initiated when the mice were 5 months old). This was accompanied by a significant decrease in the APP phosphorylation and processing. The activity of cyclin-dependent kinase 5, a major kinase involved in both APP and tau phosphorylation, was markedly downregulated by ATRA treatment. The ATRA-treated APP/PS1 mice showed decreased activation of microglia and astrocytes, attenuated neuronal degeneration, and improved spatial learning and memory compared with the vehicle-treated APP/PS1 mice. These results support ATRA as an effective therapeutic agent for the prevention and treatment of AD.

Oxidative stress is implicated in the cognitive deterioration associated with normal aging as well as neurodegenerative disorders such as Alzheimer's and Parkinson's diseases. We investigated the effect of ascorbic acid (vitamin C) on oxidative stress, cognition, and motor abilities in mice null for gulono-gamma-lactone oxidase (Gulo). Gulo-/- mice are unable to synthesize ascorbic acid and depend on dietary ascorbic acid for survival. Gulo-/- mice were given supplements that provided them either with ascorbic acid levels equal to- or slightly higher than wild-type mice (Gulo-sufficient), or lower than physiological levels (Gulo-low) that were just enough to prevent scurvy. Ascorbic acid is a major anti-oxidant in mice and any reduction in ascorbic acid level is therefore likely to result in increased oxidative stress. Ascorbic acid levels in the brain and liver were higher in Gulo-sufficient mice than in Gulo-low mice. F(4)-neuroprostanes were elevated in cortex and cerebellum in Gulo-low mice and in the cortex of Gulo-sufficient mice. All Gulo-/- mice were cognitively normal but had a strength and agility deficit that was worse in Gulo-low mice. This suggests that low levels of ascorbic acid and elevated oxidative stress as measured by F(4)-neuroprostanes alone are insufficient to impair memory in the knockouts but may be responsible for the exacerbated motor deficits in Gulo-low mice, and ascorbic acid may have a vital role in maintaining motor abilities.

Gangliosides are expressed in the outer leaflet of the plasma membrane of the cells of all vertebrates and are particularly abundant in the nervous system. Ganglioside metabolism is closely associated with the pathology of Alzheimer's disease (AD). AD, the most common form of dementia, is a progressive degenerative disease of the brain characterized clinically by progressive loss of memory and cognitive function and eventually death. Neuropathologically, AD is characterized by amyloid deposits or "senile plaques," which consist mainly of aggregated variants of amyloid beta-protein (Abeta). Abeta undergoes a conformational transition from random coil to ordered structure rich in beta-sheets, especially after addition of lipid vesicles containing GM1 ganglioside. In AD brain, a complex of GM1 and Abeta, termed "GAbeta," has been found to accumulate. In recent years, Abeta and GM1 have been identified in microdomains or lipid rafts. The functional roles of these microdomains in cellular processes are now beginning to unfold. Several articles also have documented the involvement of these microdomains in the pathogenesis of certain neurodegenerative diseases, such as AD. A pivotal neuroprotective role of gangliosides has been reported in in vivo and in vitro models of neuronal injury, Parkinsonism, and related diseases. Here we describe the possible involvement of gangliosides in the development of AD and the therapeutic potentials of gangliosides in this disorder.

Consumption of a diet that significantly elevates homocysteine (homocysteinemia) induces cell death in the CA3 hippocampal subfield in amyloid precursor protein (APP) over-expressing transgenic mice but not in wild-type controls. We assessed behavioral and other neuropathological effects of a homocysteinemia-inducing diet in aged APP-overexpressing mice. Starting at 16-18 months of age, mice were fed either a treatment diet lacking folate, choline, and methionine, and supplemented with homocysteine, or a control diet containing normal amounts of folate, choline and methionine but no homocysteine. After 5 months on the experimental diets, performance on a delayed non-matching-to-position working-memory task was unimpaired. In contrast, spatial reference memory in the water maze was impaired in transgenic mice on the treatment diet. Transgenic mice had higher homocysteine levels than wild-type mice even when fed the control diet, suggesting an effect of genotype on homocysteine metabolism. Methyl-donor deficiency did not alter amyloid deposition in the transgenic mice. These results suggest that disrupted homocysteine metabolism may induce Abeta-associated memory impairments and neurodegeneration in APP overexpressing mice.

Cholinergic neurons elaborate a hemicholinium-3 (HC-3) sensitive choline transporter (CHT) that mediates presynaptic, high-affinity choline uptake (HACU) in support of acetylcholine (ACh) synthesis and release. Homozygous deletion of CHT (-/-) is lethal shortly after birth (Ferguson et al. 2004), consistent with CHT as an essential component of cholinergic signaling, but precluding functional analyses of CHT contributions in adult animals. In contrast, CHT+/- mice are viable, fertile and display normal levels of synaptosomal HACU, yet demonstrate reduced CHT protein and increased sensitivity to HC-3, suggestive of underlying cholinergic hypofunction. We find that CHT+/- mice are equivalent to CHT+/+ siblings on measures of motor co-ordination (rotarod), general activity (open field), anxiety (elevated plus maze, light/dark paradigms) and spatial learning and memory (Morris water maze). However, CHT+/- mice display impaired performance as a result of physical challenge in the treadmill paradigm, as well as reduced sensitivity to challenge with the muscarinic receptor antagonist scopolamine in the open field paradigm. These behavioral alterations are accompanied by significantly reduced brain ACh levels, elevated choline levels and brain region-specific decreased expression of M1 and M2 muscarinic acetylcholine receptors. Our studies suggest that CHT hemizygosity results in adequate baseline ACh stores, sufficient to sustain many phenotypes, but normal sensitivities to physical and/or pharmacological challenge require full cholinergic signaling capacity.

The clinical diagnosis of cervical neoplasia by spectroscopic methods is potentially a reliable, fast and cost-effective alternative to the conventional smear test. However, it is currently limited by significant inter-patient variation in the spectroscopic properties of the cervix. Characterisation of suitable in vitro models of the spectroscopic changes that take place during neoplastic progression may prove to be a significant step towards the successful development of reliable in vivo systems. In this study, we used organotypic epithelial raft culture as an in vitro model of cervical tissue to analyse changes in the fluorescence properties of surface squamous epithelium that are associated with the development of neoplastic disease. Collagen plugs lined by primary human keratinocytes (PHKs) were used to model the normal cervical epithelium, and plugs lined by cells of the SiHa line were used as a model of neoplastic cervical tissue. Fluorescence emission spectra of these rafts were recorded at excitation wavelengths in the 250-330 nm range, complementing previous work published at longer wavelengths. Normalised, truncated emission spectra were analysed using multivariate principal component analysis. We successfully distinguished between in vitro models of normal and neoplastic cervical tissue and demonstrated a differential effect of acetic acid, which enhances the discrimination of normal from neoplastic tissue. Identification of these differences between in vitro organotypic epithelial rafts may ultimately aid the discrimination of cervical lesions in vivo., ((c) 2007 Wiley-Liss, Inc.)

Mice co-expressing the Swedish amyloid precursor protein mutation (APP(Swe)) and exon 9 deletion (DeltaE9) of the PSEN1 gene begin to develop amyloid plaques at 6-7 months of age. We demonstrate here a spatial learning deficit in 7-month-old APP(Swe) + PSEN1DeltaE9 bigenic mice using an adaptation of the Barnes maze. Mice were first trained on a cued target followed by a hidden-target condition. Although bigenic mice quickly learned the cued-target version of the task, they were significantly impaired when switched to the hidden-target version. In contrast, a separate group of double-transgenic mice trained first on the spatial hidden-target version of the task were unimpaired relative to wild-type controls. We propose that processes such as general rule learning, context learning and exploratory habituation exert a greater influence when the testing environment is novel and overshadow the spatial memory deficit in naive bigenic mice. However, when cued-target training is conducted first, these processes habituate and the spatial learning deficit is unmasked. Seven-month-old APP(Swe) + PSEN1DeltaE9 mice were unimpaired on tests of memory that did not involve learning the rules governing spatial associations.