Centre for Advanced Imaging Publications - UQ eSpace

A beta ACCUMULATION CORRELATES WITH COGNITIVE DECLINE: RESULTS FROM THE AIBL LONGITUDINAL STUDY

2011-09-11T00:00:00Z

Abnormal topological organization of structural brain networks in schizophrenia

2012-11-15T11:01:26Z

Schizophrenia is a debilitating mental disorder characterized by disturbances of thought and emotion as well as neurocognitive deficits. It is hypothesized that the core symptoms of schizophrenia arise from the inability to integrate neural processes segregated across distributed brain regions. Graph theory allows us to verify this hypothesis at large-scale structural network level. In this study, a sample of 101 schizophrenic patients and 101 healthy controls was included. We sought to investigate the abnormality of network topological organization in patients with schizophrenia by using the cortical thickness measurement from magnetic resonance imaging. Brain networks were constructed by thresholding cortical thickness correlation matrices of 78 regions and analyzed using graph theoretical approaches. Compared to healthy controls, patients showed increased characteristic path length and clustering coefficient in the structural cortical networks. Moreover, schizophrenia patients were associated with reduced nodal centrality in several regions of the default network and increased nodal centrality mainly in primary cortex and paralimbic cortex regions. These findings suggest that the structural networks of schizophrenic patients have a less optimal topological organization, resulting in reduced capacity to integrate information across brain regions.

Accuracy of clinical signs, SEP, and EEG in predicting outcome of hypoxic coma A meta-analysis

2011-02-22T00:00:00Z

Accurate estimation of local fractal dimension in natural images using Fourier-wavelet transform

2009-10-01T00:00:00Z

A commonly carried genetic variant in the delta opioid receptor gene, OPRD1, is associated with smaller regional brain volumes: replication in elderly and young populations.

2013-03-20T09:18:54Z

Delta opioid receptors are implicated in a variety of psychiatric and neurological disorders. These receptors play a key role in the reinforcing properties of drugs of abuse, and polymorphisms in OPRD1 (the gene encoding delta opioid receptors) are associated with drug addiction. Delta opioid receptors are also involved in protecting neurons against hypoxic and ischemic stress. Here, we first examined a large sample of 738 elderly participants with neuroimaging and genetic data from the Alzheimer's Disease Neuroimaging Initiative. We hypothesized that common variants in OPRD1 would be associated with differences in brain structure, particularly in regions relevant to addictive and neurodegenerative disorders. One very common variant (rs678849) predicted differences in regional brain volumes. We replicated the association of this single-nucleotide polymorphism with regional tissue volumes in a large sample of young participants in the Queensland Twin Imaging study. Although the same allele was associated with reduced volumes in both cohorts, the brain regions affected differed between the two samples. In healthy elderly, exploratory analyses suggested that the genotype associated with reduced brain volumes in both cohorts may also predict cerebrospinal fluid levels of neurodegenerative biomarkers, but this requires confirmation. If opiate receptor genetic variants are related to individual differences in brain structure, genotyping of these variants may be helpful when designing clinical trials targeting delta opioid receptors to treat neurological disorders.

A comparative study of the effects of UV- and gamma-radiation on copolymers of acrylonitrile/butadiene

2007-08-13T00:00:00Z

The radiolysis of nitrile rubbers with different acrylonitrile/butadiene composition and the homopolymers, poly(butadiene) (PBD) and poly(acrylonitrile) (PAN) has been investigated and compared with the photolysis of the same polymers. A significantly different mechanism of degradation was found for the two types of radiation. The results obtained by ESR, FTIR and measurements of soluble fractions of irradiated samples, indicated that the acrylonitrile units of the nitrile rubbers are more sensitive units to gamma-radiation, with the effects of irradiation increasing with the acrylonitrile content. The reactions observed were consumption of double bonds, crosslinking, and cyclization with the formation of conjugated double bonds. No chain-scission reactions were detected. In contrast to gamma-irradiation, the effects of photolysis were centred at the butadiene units, and increases in the acrylonitrile content resulted in a proportional decrease in the sensitivity of the copolymers. Crosslinking and chain scission were identified as the main effects of photolysis of NBR rubbers. (C) 1999 Society of Chemical Industry.

A comparison of semantic feature analysis and phonological components analysis for the treatment of naming impairments in aphasia

2012-10-30T16:11:28Z

Therapy for naming impairments post-stroke typically involves semantic and/or phonologically-based tasks. However, the relationship between individuals' locus of breakdown in word retrieval and their response to a particular treatment approach remains unclear, and direct comparisons of treatments with different targets (semantics, phonology) yet similar formats are lacking. This study examined eight people with aphasia who each received 12 treatment sessions; half the sessions involved a semantically-based treatment task, Semantic Feature Analysis (SFA), and the other half involved a phonologically-based treatment task, Phonological Components Analysis (PCA). Pre-therapy baseline accuracy scores were compared to naming accuracy post-treatment and at follow-up assessment. Seven of the eight participants showed significant improvements in naming items treated with PCA, with six of these seven participants maintaining improvements at follow-up. Four of the eight participants showed significant improvements for items treated with SFA, with three of the four maintaining improvements at follow-up. The semantic therapy was not beneficial for participants with semantic deficits. In contrast, the phonological therapy was beneficial for most participants, despite differences in underlying impairments. Understanding the relationship between an individual's locus of breakdown in word retrieval and response to different treatment tasks has the potential to optimise targeted treatment.

A comparison of the BOLD fMRI response to achromatic, L/M opponent and S-cone opponent cardinal stimuli in human visual cortex: II. chromatic vs achromatic stimuli

2009-12-10T00:00:00Z

A comparison of the BOLD fMRI response to achromatic, L/M opponent and S-cone opponent cardinal stimuli in human visual cortex: I. perceptually matched vs contrast matched stimuli

2009-12-10T00:00:00Z

A core metabolic enzyme mediates resistance to phosphine gas

2012-11-09T14:16:50Z

A cortical potential reflecting cardiac function

2012-10-30T11:30:28Z

Emotional trauma and psychological stress can precipitate cardiac arrhythmia and sudden death through arrhythmogenic effects of efferent sympathetic drive. Patients with preexisting heart disease are particularly at risk. Moreover, generation of proarrhythmic activity patterns within cerebral autonomic centers may be amplified by afferent feedback from a dysfunctional myocardium. An electrocortical potential reflecting afferent cardiac information has been described, reflecting individual differences in interoceptive sensitivity (awareness of one's own heartbeats). To inform our understanding of mechanisms underlying arrhythmogenesis, we extended this approach, identifying electrocortical potentials corresponding to the cortical expression of afferent information about the integrity of myocardial function during stress. We measured changes in cardiac response simultaneously with electroencephalography in patients with established ventricular dysfunction. Experimentally induced mental stress enhanced cardiovascular indices of sympathetic activity (systolic blood pressure, heart rate, ventricular ejection fraction, and skin conductance) across all patients. However, the functional response of the myocardium varied; some patients increased, whereas others decreased, cardiac output during stress. Across patients, heartbeat-evoked potential amplitude at left temporal and lateral frontal electrode locations correlated with stress-induced changes in cardiac output, consistent with an afferent cortical representation of myocardial function during stress. Moreover, the amplitude of the heartbeat-evoked potential in the left temporal region reflected the proarrhythmic status of the heart (inhomogeneity of left ventricular repolarization). These observations delineate a cortical representation of cardiac function predictive of proarrhythmic abnormalities in cardiac repolarization. Our findings highlight the dynamic interaction of heart and brain in stress-induced cardiovascular morbidity.

Action word meaning representations in cytoarchitectonically defined primary and premotor cortices

2009-09-03T00:00:00Z

Recent models of language comprehension have assumed a tight coupling between the semantic representations of action words and cortical motor areas. We combined functional MRI with cytoarchitectonically defined probabilistic maps of left hemisphere primary and premotor cortices to analyse responses of functionally delineated execution- and observation-related regions during comprehension of action word meanings associated with specific effectors (e.g., punch, bite or stomp) and processing of items with various levels of lexical information (non body part-related meanings, nonwords, and visual character strings). The comprehension of effector specific action word meanings did not elicit preferential activity corresponding to the somatotopic organisation of effectors in either primary or premotor cortex. However, generic action word meanings did show increased BOLD signal responses compared to all other classes of lexical stimuli in the pre-SMA. As expected, the majority of the BOLD responses elicited by the lexical stimuli were in association cortex adjacent to the motor areas. We contrast our results with those of previous studies reporting significant effects for only 1 or 2 effectors outside cytoarchitectonically defined motor regions and discuss the importance of controlling for potentially confounding lexical variables such as imageability. We conclude that there is no strong evidence for a somatotopic organisation of action word meaning representations and argue the pre-SMA might have a role in maintaining abstract representations of action words as instructional cues.

Active fibers: Matching deformable tract templates to diffusion tensor images

2009-09-04T00:00:00Z

Reliable quantitative analysis of white matter connectivity in the brain is an open problem in neuroimaging, with common solutions requiring tools for fiber tracking, tractography segmentation and estimation of intersubject correspondence. This paper proposes a novel, template matching approach to the problem. In the proposed method, a deformable fiber-bundle model is aligned directly with the subject tensor field, skipping the fiber tracking step. Furthermore, the use of a common template eliminates the need for tractography segmentation and defines intersubject shape correspondence. The method is validated using phantom DTI data and applications are presented, including automatic fiber-bundle reconstruction and tract-based morphometry.

Active site heterogeneity in dimethyl sulfoxide reductase from Rhodobacter capsulatus revealed by raman spectroscopy

2007-08-14T00:00:00Z

Raman spectroscopy has been used to investigate the structure of the molybdenum cofactor in DMSO reductase from Rhodobacter capsulatus. Three oxidized forms of the enzyme, designated 'redox cycled', 'as prepared', and DMSORmodD, have been studied using 752 nm laser excitation. In addition, two reduced forms of DMSO reductase, prepared either anaerobically using DMS or using dithionite, have been characterized. The 'redox cycled' form has a single band in the Mo=O stretching region at 865 cm(-1) consistent with other studies. This oxo ligand is found to be exchangeable directly with (DMSO)-O-18 or by redox cycling. Furthermore, deuteration experiments demonstrate that the oxo ligand in the oxidized enzyme has some hydroxo character, which is ascribed to a hydrogen bonding interaction with Trp 116. There is also evidence from the labeling studies for a modified dithiolene sulfur atom, which could be present as a sulfoxide. In addition to the 865 cm(-1) band, an extra band at 818 cm(-1) is observed in the Mo=O stretching region of the 'as prepared' enzyme which is not present in the 'redox cycled' enzyme. Based on the spectra of unlabeled and labeled DMS reduced enzyme, the band at 818 cm(-1) is assigned to the S=O stretch of a coordinated DMSO molecule. The DMSORmodD form, identified by its characteristic Raman spectrum, is also present in the 'as prepared' enzyme preparation but not after redox cycling. The complex mixture of forms identified in the 'as prepared' enzyme reveals a substantial degree of active site heterogeneity in DMSO reductase.

Acupuncture effects on Carpal Tunnel Syndrome: Pilot brain imaging study

2009-12-10T00:00:00Z

Acupuncture mediated brain activity demonstrated with fMRI at 4 Tesla

2009-12-09T00:00:00Z

Acute effects of nicotine administration during prospective memory, an event related fMRI study

2012-10-23T16:06:45Z

We previously demonstrated that stimulating neuronal nicotinic acetylcholine receptors modulates prospective memory (PM), the ability to remember and implement a prior intention. Here we used fMRI to explore the neuronal correlates of acute nicotinic (1 mg) modulation during PM, employing a double blind, valence-matched placebo-controlled design, and a solely event-related analysis. Eight healthy adults completed on two occasions (1 week washout) a simple attentional task containing infrequent PM trials. PM activated bilateral parietal, prefrontal (BA10) and anterior cingulate, and deactivated genual cingulate and medial prefrontal regions. Further, acute nicotine administration decreased activity within a largely overlapping right parietal region. This data validates a purely event-related approach to exploring PM, and suggests procholinergic modulation of PM by parietal rather than BA10/frontal regions.

Acute quantitative EEG correlates with 30 day outcome from ischemic cortical stroke

2009-12-10T11:24:19Z

Acute tryptophan depletion attenuates conscious appraisal of social emotional signals in healthy female volunteers

2012-10-23T16:19:08Z

Addressing population aging and Alzheimer's disease through the Australian Imaging Biomarkers and Lifestyle study: Collaboration with the Alzheimer's Disease Neuroimaging Initiative

2011-08-22T18:35:23Z

A density functional study of the electronic structure and spin Hamiltonian parameters of mononuclear thiomolybdenyl complexes

2008-04-10T00:00:00Z

The electron paramagnetic resonance spin Hamiltonian parameters of mononuclear thiomolybdenyl complexes based upon the tris(pyrazolyl)borate ligand, together with their molybdenyl analogues, are calculated using density functional theory. The electronic g matrix and Mo-95 hyperfine matrix are calculated as second-order response properties from the coupled-perturbed Kohn-Sham equations. The scalar relativistic zero-order regular approximation (ZORA) is used with an all-electron basis and an accurate mean-field spin-orbit operator which includes all one- and two-electron terms. The principal values and relative orientations of the g and A interaction matrices obtained from the experimental spectra in a previous EPR study are compared with those obtained from unrestricted Kohn-Sham calculations at the BP86 and B3LYP level, and the latter are found to be in good quantitative agreement. A quasi-restricted approach is used to analyze the influence of the various molecular orbitals on g and A. In all complexes the ground state magnetic orbital is d(X)2(-Y)2-based and the orientation of the A matrix is directly related to the orientation of this orbital. The largest single contribution to the orientation of the g matrix arises from the spin-orbit coupling of the d(YZ)-based lowest-unoccupied molecular orbital into the ground state. A number of smaller, cumulative charge-transfer contributions augment the d-d contributions. A comparison of the theoretical EPR parameters obtained using both crystallographic and gas-phase geometry-optimized structures of Tp*MoO(bdt) (Tp* = hydrotris(3,5-dimethylpyrazol-1-yl)borate, bdt = 1,2-benzenedithiolate) suggests a correspondence between the metal-dithiolate fold angle and the angle of noncoincidence between g and A.

A detailed study on the use of polynomial functions for modeling geometric distortion in magnet resonance imaging

Wang, Deming og Yang, Zhengyi — 2009-03-31T00:00:00Z

The use of polynomial functions for modeling geometric distortion in magnetic resonance imaging (MRI) that arises from scanner's hardware imperfection is studied in detail. In this work, the geometric distortion data from four representative MRI systems were used. Modeling of these data using polynomial functions of the fourth, fifth, sixth, and seventh orders was carried out. In order to investigate how this modeling performed for different size and shape of the volume of interest, the modeling was carried out for three different volumes of interest (VOI): a cube, a cylinder, and a sphere. The modeling's goodness was assessed using both the maximum and mean absolute errors. The modeling results showed that (i) for the cube VOI there appears to be an optimal polynomial function that gives the least modeling errors and the sixth order polynomial was found to be the optimal polynomial function for the size of the cubic VOI considered in the present work; (ii) for the cylinder VOI, all four polynomials performed approximately equally well but a trend of a slight decrease in the mean absolute error with the increasing order of the polynomial was noted; and (iii) for the sphere VOI, the maximum absolute error showed some variations with the order of the polynomial, with the fourth order polynomial producing the smallest maximum absolute errors. It is further noted that extrapolation could lead to very large errors so any extrapolation needs to be avoided. A detailed analysis on the modeling errors is presented. ©2008 American Association of Physicists in Medicine

Adiabatic nano-focusing of plasmons by metallic tapered rods in the presence of dissipation

Vogel, Michael W. og Gramotnev, Dmitri K. — 2011-02-14T16:05:50Z

A digital pediatric brain structure atlas from T1-weighted MR images

2011-10-12T20:00:09Z

Human brain atlases are indispensable tools in model-based segmentation and quantitative analysis of brain structures. However, adult brain atlases do not adequately represent the normal maturational patterns of the pediatric brain, and the use of an adult model in pediatric studies may introduce substantial bias. Therefore, we proposed to develop a digital atlas of the pediatric human brain in this study. The atlas was constructed from T1-weighted MR data set of a 9-year old, right-handed girl. Furthermore, we extracted and simplified boundary surfaces of 25 manually defined brain structures (cortical and subcortical) based on surface curvature. We constructed a 3D triangular mesh model for each structure by triangulation of the structure’s reference points. Kappa statistics (cortical, 0.97; subcortical, 0.91) indicated substantial similarities between the mesh-defined and the original volumes. Our brain atlas and structural mesh models (www.stjude.org/brainatlas) can be used to plan treatment, to conduct knowledge and model-driven segmentation, and to analyze the shapes of brain structures in pediatric patients.

A discussion of the factors influencing the polymerization processs in polymer gel dosimeters

Whittaker, A. K. — 2007-08-24T00:00:00Z

Administration of diazepam during status epilepticus reduces development and severity of epilepsy in rat

2011-03-30T11:37:30Z

Advanced paternal age alters brain development and behaviour in C57BL/6J mice

2010-06-30T00:00:00Z

Advances in structural and molecular neuroimaging in Alzheimer's disease

2011-10-12T11:04:00Z

A fast multi-resolution differential evolution method for multimodal image registration

2013-03-12T14:34:07Z

A new method of finding optimal variables using self-adaptive differential evolution derived multi-modal image registration is proposed. The method features multi-resolution images achieved through down-sampling at different stages of the transformation model variable optimization process. The performance of the method is illustrated by registering magnetic resonance images to histological sections. We provide an investigation of the impact of the down-sampling factor and convergence criteria. Our findings show that given appropriately down-sampled images, and by using the proposed approach, it is possible to find optimal registration transformation model variables faster than if appropriate down-sampling is not used.

A Flexible flow model for gradient coil design for the purpose of clinical MRI

2010-03-02T00:00:00Z

In this work a gradient coil design technique is outlined that uses a numerical wave equation solution methodology along with an optimization technique to obtain the propagating wave fronts through an inhomogeneous porous media, which essentially determines the winding patterns of the different gradient coils in the appropriate coordinate system. It is shown that such an approach is flexible and can be used to design quality gradient coils with large imaging regions. The quality of the gradient coils is measured through a number of key variables, and these are compared to the Siemens Sonata gradient coil set.

Ageing-induced solubility loss in milk protein concentrate powder: effect of protein conformational modifications and interactions with water

2011-10-19T10:01:56Z

A genetic analysis of cortical thickness in 372 twins

2011-03-09T00:00:00Z

Imaging genetics is a new field of neuroscience that blends methods from computational anatomy and quantitative genetics to identify genetic influences on brain structure and function. Here we analyzed brain MRI data from 372 young adult twins to identify cortical regions in which gray matter volume is influenced by genetic differences across subjects. Thickness maps, reconstructed from surface models of the cortical gray/white and gray/CSF interfaces, were smoothed with a 25 mm FWHM kernel and automatically parcellated into 34 regions of interest per hemisphere. In structural equation models fitted to volume values at each surface vertex, we computed components of variance due to additive genetic (A), shared (C) and unique (E) environmental factors, and tested their significance. Cortical regions in the vicinity of the perisylvian language cortex, and at the frontal and temporal poles, showed significant additive genetic variance, suggesting that volume measures from these regions may provide quantitative phenotypes to narrow the search for quantitative trait loci that influence brain structure. ©2010 IEEE.

A Genome-Wide Association Study Identifies Five Loci Influencing Facial Morphology in Europeans

2012-11-16T14:26:30Z

Age of onset of blindness affects brain anatomical networks constructed using diffusion tensor tractography

2012-11-22T12:10:59Z

Studying blindness with various onset ages may elucidate the ways that unimodal sensory deprivation at different periods of development shape the human brain. In order to determine the effect of the onset age on brain anatomical networks, we extended a previous study of 17 early blind (EB) subjects with an additional 97 subjects with various onset ages. We constructed binary anatomical networks of these subjects and sighted controls (SC) using diffusion tensor tractography and calculated the topological properties of the network. Based on onset age, the subjects were divided into congenitally blind (CB), EB, adolescent-blind (AB), and late-blind (LB) subgroups. The LB subjects demonstrated a greater connectivity density and a higher global efficiency, similar to the SC. The CB and EB subgroups showed large group differences from the other groups in their topological networks, specifically, a reduced connectivity density and a decreased global efficiency compared with the SC, especially in the frontal and occipital cortices. Additionally, significant correlations were found between age of onset and the topological properties of the anatomical network in the blind. Our results suggest that visual experience during an early period of development is critical for establishing an intact efficient anatomical network in the human brain.

A high-field fMRI study of auditory mismatch processing in healthy volunteers: Implications for auditory sensory memory dysfunction in schizophrenia

2009-12-09T00:00:00Z

A H-1 MRS study of probable Alzheimer's disease and normal aging: Implications for longitudinal monitoring of dementia progression

2007-08-13T00:00:00Z

In order to evaluate the capability of H-1 MRS to monitor longitudinal changes in subjects with probable Alzheimer's disease (AD), the temporal stability of the metabolite measures N-acetylaspartate and N-acetylas-partylglutamate (NA), total Creatine (Cr), myo-Inositol (mI), total Choline (Chol), NA/Cr, mI/Cr, Chol/Cr and NA/mI were investigated in a cohort of normal older adults. Only the metabolite measures NA, mi, Cr, NA/Cr, mI/Cr, and NA/mI were found to be stable after a mean interval of 260 days. Relative and absolute metabolite measures from a cohort of patients with probable AD were subsequently compared with data from a sample of normal older adult control subjects, and correlated with mental status and the degree of atrophy in the localized voxel. Concentrations of NA, NA/Cr, and NA/mI were significantly reduced in the AD group with concomitant significant increases in mi and mI/Cr. There were no differences between the two groups in measures of Cr, Chol, or Chol/Cr. Significant correlations between mental status as measured by the Mini-Mental State Examination and NA/mI, mI/Cr and NA were found. These metabolite measures were also significantly correlated with the extent of atrophy (as measured by CSF and GM composition) in the spectroscopy voxel. (C) 1999 Elsevier Science Inc.

A hybrid approach for resolving the electromagnetic fields inside a waveguide loaded with a lossy medium

Vegh, Viktor og Turner, Ian W. — 2011-09-10T16:19:07Z

A hybrid technique for computing the power distribution generated in a lossy medium during microwave heating

Vegh, V. og Turner, I. W. — 2007-08-15T00:00:00Z

A knowledge-guided active contour method of segmentation of cerebella on MR images of pediatric patients with medulloblastoma

2011-09-05T18:04:26Z

A knowledge-guided active model method of cortical structure segmentation on pediatric MR images

2011-09-05T18:03:30Z

A knowledge-guided active model method of skull segmentation on T1-weighted MR images

2011-09-05T18:02:31Z

Skull is the anatomic landmark for patient set up of head radiation therapy. Skull is generally segmented from CT images because CT provides better definition of skull than MR imaging. In the mean time, radiation therapy is planned on MR images for soft tissue information. This study utilized a knowledge-guided active model (KAM) method to segmented skull on MR images in order to enable radiation therapy planning with MR images as the primary planning dataset. KAM utilized age-specific skull mesh models that segmented from CT images using a conditional region growing algorithm. Skull models were transformed to given MR images using an affine registration algorithm based on normalized mutual information. The transformed mesh models actively located skull boundaries by minimizing their total energy. The preliminary validation was performed on MR and CT images from five patients. The KAM segmented skulls were compared with those segmented from CT images. The average image similarity (kappa index) was 0.57. The initial validation showed that it was promising to segment skulls directly on MR images using KAM.

A lagrangian formulation for statistical fluid registration

2010-04-08T00:00:00Z

We defined a new statistical fluid registration method with Lagrangian mechanics. Although several authors have suggested that empirical statistics on brain variation should be incorporated into the registration problem, few algorithms have included this information and instead use regularizers that guarantee diffeomorphic mappings. Here we combine the advantages of a large-deformation fluid matching approach with empirical statistics on population variability in anatomy. We reformulated the Riemannian fluid algorithm developed in [4], and used a Lagrangian framework to incorporate 0th and 1st order statistics in the regularization process. 92 2D midline corpus callosum traces from a twin MRI database were fluidly registered using the non-statistical version of the algorithm (algorithm 0), giving initial vector fields and deformation tensors. Covariance matrices were computed for both distributions and incorporated either separately (algorithm 1 and algorithm 2) or together (algorithm 3) in the registration. We computed heritability maps and two vector and tensor-based distances to compare the power and the robustness of the algorithms.

Alterations of myocardial sympathetic innervation in response to hypoxia

2010-11-26T13:52:39Z

Alterations of pulmonary zinc homeostasis and cytokine production following traumatic brain injury in rats

2013-04-23T09:40:41Z

Previous studies have shown that labile zinc and inflammatory mediators participate in many pathophysiological processes. The present study investigated the effects of traumatic brain injury (TBI) on the levels of labile zinc and certain proinflammatory factors in rat lung. Male Wistar rats were randomly assigned to 7 groups as follows: normal group, group with sham operation, and TBI groups that were sacrificed respectively at 1, 6, 24, and 72 hr, and on day 7 post-injury. Pulmonary labile zinc, tumor necrosis factor alpha (TNF-α), interleukin (IL)-8, and wet/dry weight ratio were measured at the specified time intervals. TBI caused a gradual increase of pulmonary labile zinc as demonstrated by fluorescence staining with Zinpyr-4 (ZP4). The levels of TNF-α and IL-8 and the lung wet/dry weight ratios were higher in the TBI groups compared to the normal and sham-operated groups (p <0.05). There were highly positive correlations between the intensity of ZP4 fluorescence and the pulmonary levels of TNF-α and IL-8. The results suggest that TBI induces rapid increases of labile zinc and inflammatory mediators in lung, which may participate in the pathogenesis of acute lung injury.

Alterations to cortico-striatal-thalamic connectivity with levodopa

2009-12-09T00:00:00Z

Altered spontaneous activity in Alzheimer's disease and mild cognitive impairment revealed by Regional Homogeneity

2012-01-22T12:44:48Z

Alzheimer's disease (AD), the most prevalent cause of dementia in the elderly, is characterized by progressive cognitive and intellectual deficits. Most patients with mild cognitive impairment (MCI) are thought to be in a very early stage of AD. Resting-state functional magnetic resonance imaging reflects spontaneous brain activities and/or the endogenous/background neurophysiological process of the human brain. Regional Homogeneity (ReHo) can provide a fast method for mapping regional activity across the whole brain. Little has been previously published about where or how spontaneous activity differs between MCI and AD, although many previous fMRI studies have shown that the activity pattern is altered in MCI/AD. In the present study, we first used the ReHo method to explore differences in regional spontaneous activities throughout the whole brain between normal controls (NC) and people with MCI and with AD. A one-way ANOVA was performed to determine the regions in which the ReHo differs between the three groups, and then a post hoc analysis was performed to evaluate differences in the pattern among the three groups. Finally a correlation analysis was done between the ReHo index of these regions and clinical variables in order to evaluate the relationship between ReHo and cognitive measures in the AD and MCI groups. An exploratory classification analysis also demonstrated that ReHo measures were able to correctly separate subjects in 71.4% of the cases. Altered brain spontaneous activations were found in the medial prefrontal cortex, the bilateral posterior cingulate gyrus/precuneus and the left inferior parietal lobule (IPL) in both MCI and AD. In MCI, the ReHo index in the left IPL was higher than that of the NC, which could indicate the presence of a compensatory mechanism in MCI. More obviously, the correlation analysis indicated that the lower the memory and other cognitive abilities, the lower the ReHo in patients with MCI and AD. Combining our findings with the results in earlier studies, we propose that the spontaneous activity pattern in the resting state could potentially be used as a clinical marker for MCI/AD.

Altered spontaneous activity in anisometropic amblyopia subjects: revealed by resting-state fMRI

2012-11-15T15:56:58Z

Altered structural brain connectivity in healthy carriers of the autism risk gene, CNTNAP2

2012-03-15T10:48:15Z

Alzheimer's disease risk gene, GAB2, is associated with regional brain volume differences in 755 young healthy twins

2012-07-26T10:59:42Z

A magnetic resonance imaging-based workflow for planning radiation therapy for prostate cancer

2011-10-12T11:04:14Z