Helping You Find Full Text Journal Articles

Search Results:

Author: Bernard Ng (56)


Feb
2018

The authors sought to evaluate the plaque-modifying effects of low-dose colchicine therapy plus optimal medical therapy (OMT) in patients post-acute coronary syndrome (ACS), as assessed by coronary computed tomography angiography (coronary CTA).
Colchicine therapy has been postulated to have beneficial anti-inflammatory effects in patients with ACS, translating into reduction in future adverse cardiovascular events. However, whether favorable plaque modification underpins this is yet unproven.

View Full Text PDF Listings View primary source full text article PDFs.

Dec
1969

Altered brain connectivity has been described in people with Parkinson's disease and in response to dopaminergic medications. However, it is unclear whether dopaminergic medications primarily 'normalize' disease related connectivity changes or if they induce unique alterations in brain connectivity. Further, it is unclear how these disease- and medication-associated changes in brain connectivity relate differently to specific motor manifestations of disease, such as bradykinesia/rigidity and tremor.

View Full Text PDF Listings View primary source full text article PDFs.

Nov
2017

Randomized trials have conclusively shown higher rates of chronic graft--host disease with filgrastim-stimulated apheresis peripheral blood as a donor source than unstimulated bone marrow. The Canadian Blood and Marrow Transplant Group conducted a phase 3 study of adults who received either filgrastim-stimulated apheresis peripheral blood or filgrastim-stimulated bone marrow from human leukocyte antigen-identical sibling donors. Because all donors received the identical filgrastim dosing schedule, this study allowed for a controlled evaluation of the impact of stem cell source on development of chronic graft--host disease.

View Full Text PDF Listings View primary source full text article PDFs.

Oct
2017

The nicotinic system plays an important role in cognitive control and is implicated in several neuropsychiatric conditions. However, the contributions of genetic variability in this system to individuals' cognitive control abilities are poorly understood and the brain processes that mediate such genetic contributions remain largely unidentified. In this first large-scale neuroimaging genetics study of the human nicotinic receptor system (two cohorts, males and females, fMRI total= 1586, behavioral total= 3650), we investigated a common polymorphism of the high-affinity nicotinic receptor α4β2 (rs1044396 on thegene) previously implicated in behavioral and nicotine-related studies (albeit with inconsistent major/minor allele impacts).

View Full Text PDF Listings View primary source full text article PDFs.

Oct
2017

We report a multi-omic resource generated by applying quantitative trait locus (xQTL) analyses to RNA sequence, DNA methylation and histone acetylation data from the dorsolateral prefrontal cortex of 411 older adults who have all three data types. We identify SNPs significantly associated with gene expression, DNA methylation and histone modification levels. Many of these SNPs influence multiple molecular features, and we demonstrate that SNP effects on RNA expression are fully mediated by epigenetic features in 9% of these loci.

View Full Text PDF Listings View primary source full text article PDFs.

Oct
2017

To test the ability of a multicriteria decision analysis (MCDA) model to incorporate disparate data sources of varying quality along with clinical judgement in a benefit-risk assessment of six well-known pain-relief drugs.
Six over-the-counter (OTC) analgesics were evaluated against three favourable effects and eight unfavourable effects by seven experts who specialise in the relief of pain, two in a 2-day facilitated workshop whose input data and judgements were later peer-reviewed by five additional experts.
Ibuprofen salts and solubilised emerged with the best benefit-risk profile, followed by naproxen, ibuprofen acid, diclofenac, paracetamol and aspirin.

View Full Text PDF Listings View primary source full text article PDFs.

Jul
2017

A stepwise process (SP) was developed for sustainable energy production from food waste (FW). The process comprised of hydrothermal treatment followed by oil upgrading. Synthetic food waste was primarily used as feedstock in the hydrothermal reactor under subcritical water conditions.

View Full Text PDF Listings View primary source full text article PDFs.

Dec
2015

In its original form, the amyloid cascade hypothesis of Alzheimer's disease holds that fibrillar deposits of amyloid are an early, driving force in pathological events leading ultimately to neuronal death. Early clinicopathological investigations highlighted a number of inconsistencies leading to an updated hypothesis in which amyloid plaques give way to amyloid oligomers as the driving force in pathogenesis. Rather than focusing on the inconsistencies, amyloid imaging studies have tended to highlight the overlap between regions that show early amyloid plaque signal on positron emission tomography and that also happen to be affected early in Alzheimer's disease.

View Full Text PDF Listings View primary source full text article PDFs.

Feb
2016

A fundamental means for understanding the brain's organizational structure is to group its spatially disparate regions into functional subnetworks based on their interactions. Most community detection techniques are designed for generating partitions, but certain brain regions are known to interact with multiple subnetworks. Thus, the brain's underlying subnetworks necessarily overlap.

View Full Text PDF Listings View primary source full text article PDFs.

Jan
2016

There is a recent interest in using functional magnetic resonance imaging (fMRI) for decoding more naturalistic, cognitive states, in which subjects perform various tasks in a continuous, self-directed manner. In this setting, the set of brain volumes over the entire task duration is usually taken as a single sample with connectivity estimates, such as Pearson's correlation, employed as features. Since covariance matrices live on the positive semidefinite cone, their elements are inherently inter-related.

View Full Text PDF Listings View primary source full text article PDFs.

Dec
2015

Washout is an important diagnostic imaging feature of hepatocellular carcinoma (HCC) on computed tomography (CT). The primary aim of this study is to evaluate the prevalence and the interobserver variation in the detection of portal venous phase (PVP) washout of HCCs using CT in a transplant population. The secondary aim is to evaluate factors influencing the detection of PVP washout.

View Full Text PDF Listings View primary source full text article PDFs.

Dec
1969

Combining imaging modalities to synthesize their inherent strengths provides a promising means for improving brain subnetwork identification. We propose a multimodal integration technique based on a sex-differentiated formulation of replicator dynamics for identifying subnetworks of brain regions that exhibit high inter-connectivity both functionally and structurally. Our method has a number of desired properties, namely, it can operate on weighted graphs derived from functional magnetic resonance imaging (tMRI) and diffusion MRI (dMRI) data, allows for subnetwork overlaps, has an intrinsic criterion for setting the number of subnetworks, and provides statistical control on false node inclusion in the identified subnetworks via the incorporation of stability selection.

View Full Text PDF Listings View primary source full text article PDFs.

Dec
1969

Despite that diagnosis of neurological disorders commonly involves a collection of behavioral assessments, most neuroimaging studies investigating the associations between brain and behavior largely analyze each behavioral measure in isolation. To jointly model multiple behavioral scores, sparse multiresponse regression (SMR) is often used. However, directly applying SMR without statistically controlling for false positives could result in many spurious findings.

View Full Text PDF Listings View primary source full text article PDFs.

Aug
2015

Resting-state functional magnetic resonance imaging (rs-fMRI) has become an increasingly important tool in mapping the functional networks of the brain. This tool has been used to examine network changes induced by cognitive and emotional states, neurological traits, and neuropsychiatric disorders. However, noise that remains in the rs-fMRI data after preprocessing has limited the reliability of individual-subject results, wherein scanner artifacts, subject movements, and other noise sources induce non-neural temporal correlations in the blood oxygen level-dependent (BOLD) timeseries.

View Full Text PDF Listings View primary source full text article PDFs.

View Full Text PDF Listings View primary source full text article PDFs.

Dec
1969

We present a Riemannian approach for classifying fMRI connectivity patterns before and after intervention in longitudinal studies. A fundamental difficulty with using connectivity as features is that covariance matrices live on the positive semi-definite cone, which renders their elements inter-related. The implicit independent feature assumption in most classifier learning algorithms is thus violated.

View Full Text PDF Listings View primary source full text article PDFs.

Mar
2016

Rumination, an internal cognitive state characterized by recursive thinking of current self-distress and past negative events, has been found to correlate with the development of depressive disorders. Here, we investigated the feasibility of using connectivity for distinguishing different emotional states induced by a novel free-streaming, subject-driven experimental paradigm. Connectivity between 78 functional regions of interest (ROIs) within 14 large-scale networks and 6 structural ROIs particularly relevant to emotional processing were used for classifying 4 mental states in 19 healthy controls.

View Full Text PDF Listings View primary source full text article PDFs.

View Full Text PDF Listings View primary source full text article PDFs.

Feb
2015

The aim of this study was to validate a novel technique that predicts stopping of disease-modifying anti-rheumatic drugs (DMARDs) and biologic agents (BA) from the Veterans Affairs (VA) database and compare infection risks of rheumatoid arthritis patients who stopped versus continued DMARDs/BA perioperatively. We identified 6,024 patients on 1 DMARD or BA in the perioperative period between 1999 and 2009. Time gap between medication stop date and the next start date predicted drug stoppage (X).

View Full Text PDF Listings View primary source full text article PDFs.

Jul
2014

To enhance local water security, the Singapore government promotes two water conservation policies: the use of eco-friendly toilets to reduce yellow water (YW) disposal and the installation of water efficient devices to minimize gray water (GW) discharge. The proposed water conservation policies have different impacts on the environmental performance of local wastewater management. The main purpose of this study is to examine and compare the impacts of different domestic wastewater streams and the effectiveness of two water conservation policies by means of life cycle assessment (LCA).

View Full Text PDF Listings View primary source full text article PDFs.

Dec
1969

Functional magnetic resonance imaging (fMRI) has been widely used for inferring brain regions that tend to work in tandem and grouping them into subnetworks. Despite that certain brain regions are known to interact with multiple subnetworks, few existing techniques support identification of subnetworks with overlaps. To address this limitation, we propose a novel approach based on replicator dynamics that facilitates detection of sparse overlapping subnetworks.

View Full Text PDF Listings View primary source full text article PDFs.

Dec
1969

There is a recent trend towards integrating resting state functional magnetic resonance imaging (RS-fMRI) and diffusion MRI (dMRI) for brain connectivity estimation, as motivated by how estimates from these modalities are presumably two views reflecting the same underlying brain circuitry. In this paper, we show on a cohort of 60 subjects that conventional functional connectivity (FC) estimates based on Pearson's correlation and anatomical connectivity (AC) estimates based on fiber counts are actually not that highly correlated for typical RS-fMRI (approximately 7 min) and dMRI (approximately 32 gradient directions) data. The FC-AC correlation can be significantly increased by considering sparse partial correlation and modeling fiber endpoint uncertainty, but the resulting FC-AC correlation is still rather low in absolute terms.

View Full Text PDF Listings View primary source full text article PDFs.

Jan
2014

The purpose of this study is to explore patient factors associated with differences in methotrexate (MTX) dosing and to compare patient factors and MTX-dosing patterns between those who remained on MTX monotherapy and those who were switched or had additional therapy. A retrospective cohort of 7,017 patients with newly diagnosed rheumatoid arthritis (RA) was identified in the United States Department of Veterans Affairs administrative databases between 1 October 1999 and 30 September 2009. Regression analyses were used to study the association of MTX start and maximum dose attained with various patient characteristics and compare differences between groups who had therapeutic change (having switched to or added another anti-rheumatic agent or having steroids increased by 2.

View Full Text PDF Listings View primary source full text article PDFs.

Apr
2013

Source-separating urine from other domestic wastewaters promotes a more sustainable municipal wastewater treatment system. This study investigated the feasibility and potential issues of applying a urine source-separation system in tropical urban settings. The results showed that source-separated urine underwent rapid urea-hydrolysis (ureolysis) at temperatures between 34-40 degrees C, stale/fresh urine ratios greater than 40%, and/or with slight fecal cross-contamination.

View Full Text PDF Listings View primary source full text article PDFs.

Dec
1969

To evaluate the trends in patterns of disease-modifying antirheumatic drugs (DMARDs) and biological agents use from 1999 to 2009 and to identify patient characteristics associated with different patterns of their use in a national sample of Veterans with rheumatoid arthritis (RA).
A retrospective cohort study.
Administrative databases of the USA Department of Veterans Affairs.

View Full Text PDF Listings View primary source full text article PDFs.

Apr
2013

The extent of vascular invasion is a key factor determining the resectability of non-metastatic pancreatic adenocarcinoma. The purpose of this study is to determine the diagnostic accuracy of computed tomography (CT), endoscopic ultrasound (EUS), and magnetic resonance imaging (MRI) in the pre-operative evaluation of vascular invasion in pancreatic adenocarcinoma, with surgery as the reference standard.
A search of the MEDLINE database for relevant articles in the English language published between January 2000 and February 2009 was performed.

View Full Text PDF Listings View primary source full text article PDFs.

Dec
1969

Despite the clear potential benefits of combining fMRI and diffusion MRI in learning the neural pathways that underlie brain functions, little methodological progress has been made in this direction. In this paper, we propose a novel multimodal integration approach based on sparse Gaussian graphical model for estimating brain connectivity. Casting functional connectivity estimation as a sparse inverse covariance learning problem, we adapt the level of sparse penalization on each connection based on its anatomical capacity for functional interactions.

View Full Text PDF Listings View primary source full text article PDFs.

Dec
1969

The estimation of intra-subject functional connectivity is greatly complicated by the small sample size and complex noise structure in functional magnetic resonance imaging (fMRI) data. Pooling samples across subjects improves the conditioning of the estimation, but loses subject-specific connectivity information. In this paper, we propose a new sparse group Gaussian graphical model (SGGGM) that facilitates joint estimation of intra-subject and group-level connectivity.

View Full Text PDF Listings View primary source full text article PDFs.

Dec
1969

Inference of brain activation through the analysis of functional magnetic resonance imaging (fMRI) data is seriously confounded by the high level f noise in the observations. To mitigate the effects of noise, we propose incorporating anatomical connectivity into brain activation detection as motivated by how the functional integration of distinct brain areas is facilitated via neural fiber pathways. In this work, we formulate activation detection as a probabilistic graph-based segmentation problem with fiber networks estimated from diffusion MRI (dMRI) data serving as a prior.

View Full Text PDF Listings View primary source full text article PDFs.

May
2013

Reply: To PMID 22623324.

Arthritis Care Res (Hoboken) 2013 May;65(5):836-8
Bernard Ng, Fawad Aslam, Hong-Jen Yu

View Full Text PDF Listings View primary source full text article PDFs.

Oct
2012

The accuracy of the diagnosis is vital when administrative databases are used for pharmacoepidemiologic and outcome studies. Data pertaining to the utility of databases for rheumatoid arthritis (RA) are sparse and variable. We assessed the utility of various diagnostic algorithms to identify RA patients within the Veterans Health Administration (VHA) databases.

View Full Text PDF Listings View primary source full text article PDFs.

May
2012

Modeling brain activation in fMRI using group MRF.

IEEE Trans Med Imaging 2012 May 27;31(5):1113-23. Epub 2012 Jan 27.
Bernard Ng, Ghassan Hamarneh, Rafeef Abugharbieh
Noise confounds present serious complications to functional magnetic resonance imaging (fMRI) analysis. The amount of discernible signals within a single dataset of a subject is often inadequate to obtain satisfactory intra-subject activation detection. To remedy this limitation, we propose a novel group Markov random field (GMRF) that extends each subject's neighborhood system to other subjects to enable information coalescing.

View Full Text PDF Listings View primary source full text article PDFs.

Mar
2012

Functional magnetic resonance imaging (fMRI) is increasingly used for studying functional integration of the brain. However, large inter-subject variability in functional connectivity, particularly in disease populations, renders detection of representative group networks challenging. In this paper, we propose a novel technique, "group replicator dynamics" (GRD), for detecting sparse functional brain networks that are common across a group of subjects.

View Full Text PDF Listings View primary source full text article PDFs.

Dec
1969

A growing interest has emerged in studying the correlation structure of spontaneous and task-induced brain activity to elucidate the functional architecture of the brain. In particular, functional networks estimated from resting state (RS) data were shown to exhibit high resemblance to those evoked by stimuli. Motivated by these findings, we propose a novel generative model that integrates RS-connectivity and stimulus-evoked responses under a unified analytical framework.

View Full Text PDF Listings View primary source full text article PDFs.

May
2012

The aim of this study was to evaluate the accuracy of multidetector computed tomography (MDCT) in the detection of parathyroid adenoma and hyperplasia in the setting of primary hyperparathyroidism.
Records of 48 patients with biochemically confirmed primary hyperparathyroidism, who underwent preoperative imaging with 16- or 64-slice contrast-enhanced MDCT and subsequent successful parathyroidectomy over a 3-year period, were reviewed. Two radiologists, blinded to the operative and histologic findings, independently evaluated multiplanar computed tomographic images for all patients.

View Full Text PDF Listings View primary source full text article PDFs.

Dec
1969

Many current medical image analysis problems involve learning thousands or even millions of model parameters from extremely few samples. Employing sparse models provides an effective means for handling the curse of dimensionality, but other propitious properties beyond sparsity are typically not modeled. In this paper, we propose a simple approach, generalized sparse regularization (GSR), for incorporating domain-specific knowledge into a wide range of sparse linear models, such as the LASSO and group LASSO regression models.

View Full Text PDF Listings View primary source full text article PDFs.

Dec
1969

To estimate the incidence and examine the pattern of post-thoracotomy pulmonary complications (PPC) that are amenable to physiotherapy treatment and to estimate the effect size of a pre-thoracotomy physiotherapy education session compared to no preoperative physiotherapy for reducing PPC.
Forty-two patients undergoing thoracotomy participated in this two-group retrospective-prospective cohort study. The preop group (n=22) received physiotherapy education prior to surgery and the no preop group (n=20) did not receive preoperative physiotherapy education.

View Full Text PDF Listings View primary source full text article PDFs.

Dec
1969

Due to the complex noise structure of functional magnetic resonance imaging (fMRI) data, methods that rely on information within a single subject often results in unsatisfactory functional segmentation. We thus propose a new graph-theoretic method, "Group Random Walker" (GRW), that integrates group information in detecting single-subject activation. Specifically, we extend each subject's neighborhood system in such a way that enables the states of both intra- and inter-subject neighbors to be regularized without having to establish a one-to-one voxel correspondence as required in standard fMRI group analysis.

View Full Text PDF Listings View primary source full text article PDFs.

Jun
2010

Intra-articular hyaluronic acid has been used in treatment of patients with knee osteoarthritis. Though its effect on pain has been well studied, it is not clear how it affects the articular cartilage. This is a preliminary study to evaluate the kinetics of urinary collagen type-II C-telopeptide (CTX-II) as a biomarker of collagen breakdown in response to intra-articular hyaluronic acid injection in patients with symptomatic knee osteoarthritis.

View Full Text PDF Listings View primary source full text article PDFs.

Jun
2010

"You never asked doc., I do fish".

Clin Rheumatol 2010 Jun 1;29(6):691-3. Epub 2009 Sep 1.
Fawad Aslam, Bernard Ng
Joint pains and swellings are routine complaints in rheumatology clinics. Infectious diseases may mimic common rheumatic conditions and thus need to be ruled out before initiating any immunosuppressive treatment. Mycobacterium marinum is an organism that can present with a typical arthritis picture.

View Full Text PDF Listings View primary source full text article PDFs.

Dec
1969

Many studies in Asia have demonstrated that Asian populations may require lower cut-off levels for body mass index (BMI) and waist circumference to define obesity and abdominal obesity respectively, compared to western populations. Optimal cut-off levels for body mass index and waist circumference were determined to assess the relationship between the two anthropometric- and cardiovascular indices. Receiver operating characteristics analysis was used to determine the optimal cut-off levels.

View Full Text PDF Listings View primary source full text article PDFs.

Dec
1969

Functional magnetic resonance imaging (fMRI) has become increasingly used for studying functional integration of the brain. However, the large inter-subject variability in functional connectivity renders detection of representative group networks very difficult. In this paper, we propose a new iterative method that we refer to as "group replicator dynamics," for detecting sparse functional networks that are common across subjects within a group.

View Full Text PDF Listings View primary source full text article PDFs.

Jan
2010

Previous fMRI motor studies in Parkinson's disease (PD) have suggested that L-dopa may "normalize" areas of hypo- and hyperactivity. However, results from these studies, which were largely based on analyzing BOLD signal amplitude, have been conflicting. Examining only amplitude changes at distinct loci may thus be inadequate in fully capturing the activation changes induced by L-dopa.

View Full Text PDF Listings View primary source full text article PDFs.

Jun
2009

Motor symptoms of Parkinson's disease (PD) do not appear until the majority of dopaminergic cells in the substantia nigra pars compacta are lost, suggesting significant redundancy or compensation in the motor systems affected by PD. Using functional magnetic resonance imaging, we examined whether compensation in PD is manifested by changes in amplitude and/or spatial extent of activity within normal networks (active motor reserve) and/or newly recruited regions [novel area recruitment (NAR)]. Ten PD subjects off and on medication and 10 age-matched controls performed a visually guided sinusoidal force task at 0.

View Full Text PDF Listings View primary source full text article PDFs.

Feb
2009

A novel approach is proposed for quantitatively characterizing the spatial patterns of activation statistics in functional magnetic resonance imaging (fMRI) activation maps. Specifically, we propose using 3-D invariant moment descriptors, as opposed to the traditionally-employed magnitude-based features such as mean voxel statistics or percentage of activated voxels, to characterize the task-specific spatial distribution of activation statistics within a given region of interest (ROI). The proposed method is applied to real fMRI data collected from 21 healthy subjects performing previously-learned right-handed finger tapping sequences that are either externally guided (EG) by a cue or internally guided (IG)--tasks expected to incur subtle differences in motor-related cortical and subcortical ROIs.

View Full Text PDF Listings View primary source full text article PDFs.

Dec
1969

We propose a novel method for functional segmentation of fMRI data that incorporates multiple functional attributes such as activation effects and functional connectivity, under a single framework. Similar to PCA, our method exploits the structure of the correlation matrix but with neighborhood information adaptively integrated to encourage detection of spatially contiguous clusters yet without falsely pooling non-active voxels near the functional boundaries. In addition, our method adaptively combines PCA and replicator dynamics, which we show to be equivalent to non-negative sparse PCA, based on the sparsity of the activation pattern.

View Full Text PDF Listings View primary source full text article PDFs.

Jul
2008

This study assessed self-reported adherence in patients with rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) from underserved healthcare settings. We conducted a cross-sectional survey of 102 ethnically diverse patients--70 with RA and 32 with SLE--attending rheumatology clinics at publicly funded hospitals in Houston, Texas; 43% were Hispanic, 32% African-American, and 25% White. Treatment adherence was evaluated using the compliance questionnaire rheumatology (CQR; 0, low adherence and 100, high adherence) and the questionnaire of the Adult AIDS Clinical Trials Group (AACTG).

View Full Text PDF Listings View primary source full text article PDFs.

Dec
1969

We present a new functional magnetic resonance imaging (fMRI) analysis method that incorporates both spatial and temporal dynamics of blood-oxygen-level dependent (BOLD) signals within a region of interest (ROI). 3D moment descriptors are used to characterize the spatial changes in BOLD signals over time. The method is tested on fMRI data collected from eight healthy subjects performing a bulb-squeezing motor task with their right-hand at various frequencies.

View Full Text PDF Listings View primary source full text article PDFs.

Dec
1969

In region of interest (ROI) based functional magnetic resonance imaging (fMRI) group analysis, errors in delineation of an ROI or inclusion of non-active voxels within an ROI can bias the statistical results. Addressing these concerns, this paper presents a new fMRI processing method that simultaneously refines ROI delineation and spatially denoises fMRI activation statistics within the ROI. The underlying assumption is that activation statistics within a small neighborhood are spatially correlated, thereby exhibit similar levels of influence on the overall ROI's response.

View Full Text PDF Listings View primary source full text article PDFs.

Oct
2007

The activation or the inhibition of melanocyte-specific receptors offers novel means of augmenting normal melanocyte function, skin color, and photoprotection, or treating melanocytic disorders, namely at this time, metastatic melanoma. Melanocyte-specific receptors include melanocortin-1 (MCR1) and melatonin receptors. Other receptors that play an important role in melanoma progression are G-protein couple receptors such as Frizzled 5 and receptor tyrosine kinases such as c-Kit and hepatocyte growth factor (HGF) receptor.

View Full Text PDF Listings View primary source full text article PDFs.

Back to top