Andrew Janke | The University of Queensland, Australia (original) (raw)

Papers by Andrew Janke

Neurology, 2007

Activation of effector T lymphocytes, mediated in part by costimulatory molecules, is an importan... more Activation of effector T lymphocytes, mediated in part by costimulatory molecules, is an important mechanism in the pathogenesis of immune-mediated diseases of the peripheral nervous system (PNS). To analyze the expression and distribution pattern of the inducible costimulator (ICOS), a recently identified costimulatory molecule implicated in T-cell activation, and its unique ligand (ICOS-L), in inflammatory disorders of the PNS. We studied RNA and protein expression in sural nerve biopsy specimens from patients with Guillain-Barré syndrome (GBS), chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), and vasculitic neuropathy (VN) vs patients with hereditary neuropathies (HNs) serving as a noninflammatory control using reverse-transcriptase PCR and immunohistochemistry. In addition, in vitro analysis was performed by flow cytometry. ICOS and ICOS-L mRNA was found to be significantly upregulated in samples from patients with GBS, CIDP, and VN compared to HNs. Immunohistochemistry identified T lymphocytes as the cellular source of ICOS, whereas macrophages expressed the corresponding ligand ICOS-L. Further analysis revealed that the distribution of ICOS-expressing T cells did not differ between acute and chronic inflamed PNS diseases. Correspondingly, the expression pattern of ICOS-L was similar in the inflamed tissues but differed significantly when compared to HNs. Inducible costimulator, expressed by T lymphocytes, and inducible costimulator ligand, expressed by macrophages within the peripheral nerve, might not only be relevant in inducing an acute immune response but might also be critically involved in perpetuating inflammation in chronically immune-mediated disorders of the peripheral nervous system.

The Journal of Neuroscience : The Official Journal of the Society for Neuroscience

We detected and mapped a dynamically spreading wave of gray matter loss in the brains of patients... more We detected and mapped a dynamically spreading wave of gray matter loss in the brains of patients with Alzheimer's disease (AD). The loss pattern was visualized in four dimensions as it spread over time from temporal and limbic cortices into frontal and occipital brain regions, sparing sensorimotor cortices. The shifting deficits were asymmetric (left hemisphere > right hemisphere) and correlated with progressively declining cognitive status (p < 0.0006). Novel brain mapping methods allowed us to visualize dynamic patterns of atrophy in 52 high-resolution magnetic resonance image scans of 12 patients with AD (age 68.4 +/- 1.9 years) and 14 elderly matched controls (age 71.4 +/- 0.9 years) scanned longitudinally (two scans; interscan interval 2.1 +/- 0.4 years). A cortical pattern matching technique encoded changes in brain shape and tissue distribution across subjects and time. Cortical atrophy occurred in a well defined sequence as the disease progressed, mirroring the se...

Magnetic Resonance in Medicine

This work describes the development of a model of cerebral atrophic changes associated with the p... more This work describes the development of a model of cerebral atrophic changes associated with the progression of Alzheimer's disease (AD). Linear registration, region-of-interest analysis, and voxel-based morphometry methods have all been employed to elucidate the changes observed at discrete intervals during a disease process. In addition to describing the nature of the changes, modeling disease-related changes via deformations can also provide information on temporal characteristics. In order to continuously model changes associated with AD, deformation maps from 21 patients were averaged across a novel z-score disease progression dimension based on Mini Mental State Examination (MMSE) scores. The resulting deformation maps are presented via three metrics: local volume loss (atrophy), volume (CSF) increase, and translation (interpreted as representing collapse of cortical structures). Inspection of the maps revealed significant perturbations in the deformation fields correspondi...

Research and Perspectives in Alzheimer’s Disease, 2004

Page 1. DYNAMIC MAPPING OF ALZHEIMER&amp;amp;#x27;S DISEASE 1 Paul M. Thompson, 1 Kiralee... more Page 1. DYNAMIC MAPPING OF ALZHEIMER&amp;amp;#x27;S DISEASE 1 Paul M. Thompson, 1 Kiralee M. Hayashi, 2 Greig de Zubicaray, 2 Andrew L. Janke, 1 Elizabeth R. Sowell, 2 Stephen E. Rose, 3 James Semple, 1 David Herman, 1 Michael S. Hong, ...

BioMed research international, 2014

The protective effect of education on cognitive and brain health is well established. While the d... more The protective effect of education on cognitive and brain health is well established. While the direct effects of individual cardiovascular disease (CVD) risk factors (i.e., hypertension, smoking, diabetes, and obesity) on cerebral structure have been investigated, little is understood about the possible interaction between the protective effect of education and the deleterious effects of CVD risk factors in predicting brain ageing and cognition. Using data from the PATH Through Life study (N = 266), we investigated the protective effect of education on cerebral structure and function and tested a possible mediating role of CVD risk factors. Higher education was associated with larger regional grey/white matter volumes in the prefrontal cortex in men only. The association between education and cognition was mediated by brain volumes but only for grey matter and only in relation to information processing speed. CVD risk factors did not mediate the association between regional volumes...

American journal of hypertension, 2015

Research on associations between blood pressure, brain structure, and cognitive function has prod... more Research on associations between blood pressure, brain structure, and cognitive function has produced somewhat inconsistent results. In part, this may be due to differences in age ranges studied and because of sex differences in physiology and/or exposure to risk factors, which may lead to different time course or patterns in cardiovascular disease progression. The aim of this study was to investigate the impact of sex on associations between blood pressure, regional cerebral volumes, and cognitive function in older individuals. In this cohort study, brachial blood pressure was measured twice at rest in 266 community-based individuals free of dementia aged 68-73 years who had also undergone a brain scan and a neuropsychological assessment. Associations between mean blood pressure (MAP), regional brain volumes, and cognition were investigated with voxel-wise regression analyses. Positive associations between MAP and regional volumes were detected in men, whereas negative associations...

Alzheimer's & Dementia, 2014

tivity theory will be employed for their analysis. The long term objective is to determine whethe... more tivity theory will be employed for their analysis. The long term objective is to determine whether an individual's capacity for compensatory atypical memory network activation is related to incidence of clinical dementia. Methods: This study forms one arm of the LAPSES study, a populationbased longitudinal investigation of psychiatric, cognitive, neurological and neuroimaging characteristics of individuals with early memory complaints. Our paradigm is a 3T fMRI delayed match-to-sample task focused on episodic and spatial memory retrieval, in which the number of active visuospatial elements which define 'easy', 'moderate' and 'hard' task difficulty conditions are matched across subjects in pretesting by application of 90%, 70% and 50% performance criteria, respectively. While the active visuospatial elements vary across task difficulty, the overall number of elements is held constant by employing 'filler' stimuli, thus matching the perceptual load within subjects across the experiment. Connectivity tools employed to characterize functionally active memory-dependent networks will include Principal Component Analysis and wavelet analysis. Results: Preliminary functional connectivity data from 10 individuals with early memory complaints will be presented, with a focus on differential network activation when undergoing tasks of contrasting difficulty level. Conclusions: The significance of differential network activation with respect to task gradient will be discussed in relation to clinical neuroscience and prognosis of dementia.

Proceedings / IEEE International Symposium on Biomedical Imaging: from nano to macro. IEEE International Symposium on Biomedical Imaging, 2002

We briefly describe a set of algorithms to detect and visualize effects of disease and genetic fa... more We briefly describe a set of algorithms to detect and visualize effects of disease and genetic factors on the brain. Extreme variations in cortical anatomy, even among normal subjects, complicate the detection and mapping of systematic effects on brain structure in human populations. We tackle this problem in two stages. First, we develop a cortical pattern matching approach, based on metrically covariant partial differential equations (PDEs), to associate corresponding regions of cortex in an MRI brain image database (N=102 scans). Second, these high-dimensional deformation maps are used to transfer within-subject cortical signals, including measures of gray matter distribution, shape asymmetries, and degenerative rates, to a common anatomic template for statistical analysis. We illustrate these techniques in two applications: (1) mapping dynamic patterns of gray matter loss in longitudinally scanned Alzheimer's disease patients; and (2) mapping genetic influences on brain stru...

The Journal of neuroscience : the official journal of the Society for Neuroscience, 2003

Lecture Notes in Computer Science, 2006

In model-based segmentation, automated region identification is achieved via registration of nove... more In model-based segmentation, automated region identification is achieved via registration of novel data to a pre-determined model. The desired structure is typically generated via manual tracing within this model. When model-based segmentation is applied to human cortical data, problems arise if left-right comparisons are desired. The asymmetry of the human cortex requires that both left and right models of a structure be composed in order to effectively segment the desired structures. Paradoxically, defining a model in both hemi-spheres carries a likelihood of introducing bias to one of the structures. This paper describes a novel technique for creating a symmetric average model in which both hemispheres are equally represented and thus left-right comparison is possible. This work is an extension of that proposed by Guimond et al. Hippocampal segmentation is used as a test-case in a cohort of 118 normal eld-erly subjects and results are compared with expert manual tracing.

Journal of Comparative Neurology, 2014

Brain atlases are a fundamental resource for neuroscience research. In the past few decades they ... more Brain atlases are a fundamental resource for neuroscience research. In the past few decades they have undergone a transition from traditional printed histological atlases to digital atlases made up of multiple data sets from multiple modalities, and atlases based on magnetic resonance imaging (MRI) have become widespread. Here we discuss the methods involved in making an MRI brain atlas, including registration of multiple data sets into a model, ontological classification, segmentation of a minimum deformation model, dissemination strategies, and applications of these atlases. Finally, we discuss possible future directions in the development of brain atlases.

ABSTRACT Magnetic resonance imaging (MRI) is widely used to study the population effects of covar... more ABSTRACT Magnetic resonance imaging (MRI) is widely used to study the population effects of covariates on brain morphometry. Inferences from these studies often require the simultaneous testing of millions of statistical hypotheses. Such scale of simultaneous testing is known to lead to large numbers of false positive results. False discovery rate (FDR) controlling procedures are commonly employed to mitigate against false positives. However, current methodologies in FDR control only account for the marginal significance of hypotheses and are not able to take into account spatial relationships, such as in MRI studies. In this article, we present a novel method for incorporating spatial dependencies in the control of FDR through the use of Markov random fields. Our method is able to automatically estimate the relationship between spatially dependent hypotheses by means of pseudo-likelihood techniques. We show that the our spatial FDR control method is able to outperform marginal methods in simulations of spatially dependent hypotheses. Our method is then applied to investigate the effect of aging on brain morphometry using data from the PATH study. The results of our investigation were found to be in correspondence with the brain aging literature.

Frontiers in Neuroinformatics, 2013

Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), 2005

This paper considers the problem of tissue classification in 3D MRI. More specifically, a new set... more This paper considers the problem of tissue classification in 3D MRI. More specifically, a new set of texture features, based on phase information, is used to perform the segmentation of the bones of the knee. The phase information provides a very good discrimination between the bone and the surrounding tissues, but is usually not used due to phase unwrapping problems. We present a method to extract textural information from the phase that does not require phase unwrapping. The textural information extracted from the magnitude and the phase can be combined to perform tissue classification, and used to initialise an active shape model, leading to a more precise segmentation.

Frontiers in Neuroinformatics, 2014

NeuroImage, Jan 15, 2008

Measures of structural brain change based on longitudinal MR imaging are increasingly important b... more Measures of structural brain change based on longitudinal MR imaging are increasingly important but can be degraded by intensity non-uniformity. This non-uniformity can be more pronounced at higher field strengths, or when using multichannel receiver coils. We assessed the ability of the non-parametric non-uniform intensity normalization (N3) technique to correct non-uniformity in 72 volumetric brain MR scans from the preparatory phase of the Alzheimer's Disease Neuroimaging Initiative (ADNI). Normal elderly subjects (n=18) were scanned on different 3-T scanners with a multichannel phased array receiver coil at baseline, using magnetization prepared rapid gradient echo (MP-RAGE) and spoiled gradient echo (SPGR) pulse sequences, and again 2 weeks later. When applying N3, we used five brain masks of varying accuracy and four spline smoothing distances (d=50, 100, 150 and 200 mm) to ascertain which combination of parameters optimally reduces the non-uniformity. We used the normaliz...

Frontiers in neuroinformatics, 2014

The Multi-modal Australian ScienceS Imaging and Visualization Environment (MASSIVE) is a national... more The Multi-modal Australian ScienceS Imaging and Visualization Environment (MASSIVE) is a national imaging and visualization facility established by Monash University, the Australian Synchrotron, the Commonwealth Scientific Industrial Research Organization (CSIRO), and the Victorian Partnership for Advanced Computing (VPAC), with funding from the National Computational Infrastructure and the Victorian Government. The MASSIVE facility provides hardware, software, and expertise to drive research in the biomedical sciences, particularly advanced brain imaging research using synchrotron x-ray and infrared imaging, functional and structural magnetic resonance imaging (MRI), x-ray computer tomography (CT), electron microscopy and optical microscopy. The development of MASSIVE has been based on best practice in system integration methodologies, frameworks, and architectures. The facility has: (i) integrated multiple different neuroimaging analysis software components, (ii) enabled cross-pla...

Surface Coatings International Part B-coatings Transactions, 2003

Summaries The self-organisation of semifluorinated segments was used to create polymers and bloc... more Summaries The self-organisation of semifluorinated segments was used to create polymers and block copolymers with ultra-low surface free energy. The aromatic polyester poly(p-phenylene oxydecyl-perfluorodecyl-isophthalate) showed an extremely low value ofγ sv of 9mN/m. It was proven that this low value was caused by an ordered surface structure. Introduction of these semifluorinated polyester segments into block copolymers with a basic structure (A–B)n