Publications by authors named "Nuwan Nanayakkara"

Article Synopsis
  • * Our research involved 49 participants across different health groups (healthy, hypertensive, and hypertensive with type 2 diabetes), revealing that healthy individuals had higher CVR amplitude than those with hypertension plus diabetes.
  • * We found that measuring CVR lag using this method is a more sensitive indicator of vascular issues than amplitude alone, as the lag was significantly shorter in hypertensive patients compared to healthy controls.
View Article and Find Full Text PDF
Article Synopsis
  • The study investigates the link between traumatic brain injury (TBI) history and grey matter loss in patients with mild cognitive impairment (MCI).
  • At baseline, patients with a history of TBI showed reduced grey matter in key brain areas and exhibited greater declines in cortical thickness over two years compared to those without TBI.
  • The results indicate that MCI patients with TBI histories are at higher risk for accelerated neurodegeneration, particularly in areas affected by mechanical injury, emphasizing the need for targeted interventions.
View Article and Find Full Text PDF

Type 2 diabetes mellitus (T2DM) and hypertension are risk factors for cerebral small vessel disease (SVD); however, few studies have characterised their relationships with MRI-visible perivascular spaces (PVS). MRI was used to quantify deep (d) and periventricular (p) white matter hyperintensities (WMH), lacunes, PVS in the white matter (wmPVS) or basal ganglia (bgPVS), and diffusion metrics in white matter. Patients with T2DM had greater wmPVS volume and there were greater wmPVS volumes in patients with T2DM and hypertension together.

View Article and Find Full Text PDF

Background: Acute change in gait speed while performing a mental task [dual-task gait cost (DTC)], and hyperintensity magnetic resonance imaging signals in white matter are both important disability predictors in older individuals with history of stroke (poststroke). It is still unclear, however, whether DTC is associated with overall hyperintensity volume from specific major brain regions in poststroke.

Methods: This is a cohort study with a total of 123 older (69 ± 7 years of age) participants with history of stroke were included from the Ontario Neurodegenerative Disease Research Initiative.

View Article and Find Full Text PDF

Background And Purpose: The pathophysiology of Parkinson's disease (PD) negatively affects brain network connectivity, and in the presence of brain white matter hyperintensities (WMHs) cognitive and motor impairments seem to be aggravated. However, the role of WMHs in predicting accelerating symptom worsening remains controversial. The objective was to investigate whether location and segmental brain WMH burden at baseline predict cognitive and motor declines in PD after 2 years.

View Article and Find Full Text PDF

Background Cerebral small vessel disease is associated with higher ratios of soluble-epoxide hydrolase derived linoleic acid diols (12,13-dihydroxyoctadecenoic acid [DiHOME] and 9,10-DiHOME) to their parent epoxides (12(13)-epoxyoctadecenoic acid [EpOME] and 9(10)-EpOME); however, the relationship has not yet been examined in stroke. Methods and Results Participants with mild to moderate small vessel stroke or large vessel stroke were selected based on clinical and imaging criteria. Metabolites were quantified by ultra-high-performance liquid chromatography-mass spectrometry.

View Article and Find Full Text PDF
Article Synopsis
  • The study investigates the tissue microstructure of normal-appearing white matter (NAWM) in the brain of stroke patients using diffusion tensor imaging (DTI) to understand its impact on cognitive outcomes.
  • It compares DTI metrics like fractional anisotropy (FA) and mean diffusivity (MD) across different types of cerebral tissue, including vascular lesions and healthy tissues, in a group of 152 people with cerebrovascular disease (CVD).
  • The findings reveal that DTI metrics significantly differ between vascular lesions and healthy tissues, with FA in NAWM being inversely associated with hypertension and other cerebrovascular risk factors, suggesting the potential of DTI in assessing brain health and vascular anomalies.
View Article and Find Full Text PDF

We propose a novel image analysis framework to automate analysis of X-ray microtomography images of sintering ceramics and glasses, using open-source toolkits and machine learning. Additive manufacturing (AM) of glasses and ceramics usually requires sintering of green bodies. Sintering causes shrinkage, which presents a challenge for controlling the metrology of the final architecture.

View Article and Find Full Text PDF

Purpose: Magnetic resonance imaging (MRI) scanner-specific geometric distortions may contribute to scanner induced variability and decrease volumetric measurement precision for multi-site studies. The purpose of this study was to determine whether geometric distortion correction increases the precision of brain volumetric measurements in a multi-site multi-scanner study.

Methods: Geometric distortion variation was quantified over a one-year period at 10 sites using the distortion fields estimated from monthly 3D T1-weighted MRI geometrical phantom scans.

View Article and Find Full Text PDF

The measure of White Blood Cells (WBC) in the blood is an important indicator of pathological conditions. Computer vision based methods for differential counting of WBC are increasing due to their advantages over traditional methods. However, most of these methods are proposed for single WBC images which are pre-processed, and do not generalize for raw microscopic images with multiple WBC.

View Article and Find Full Text PDF

Diabetes mellitus is a major health problem which needs regular glucose monitoring for management of the disease. Invasive blood glucose measuring systems with acceptable accuracy are currently used for measurements. Several non- invasive blood glucose measurement techniques are reported in research literature, but most of them are not commercially available due to low accuracy or dependency on individual physiological parameters.

View Article and Find Full Text PDF

The processing of brain diffusion tensor imaging (DTI) data for large cohort studies requires fully automatic pipelines to perform quality control (QC) and artifact/outlier removal procedures on the raw DTI data prior to calculation of diffusion parameters. In this study, three automatic DTI processing pipelines, each complying with the general ENIGMA framework, were designed by uniquely combining multiple image processing software tools. Different QC procedures based on the RESTORE algorithm, the DTIPrep protocol, and a combination of both methods were compared using simulated ground truth and artifact containing DTI datasets modeling eddy current induced distortions, various levels of motion artifacts, and thermal noise.

View Article and Find Full Text PDF

Introduction: Trebananib, a peptide-Fc fusion protein, blocks angiogenesis by inhibiting binding of angiopoietin-1/2 to the receptor tyrosine kinase Tie2. Trebananib plus trastuzumab and paclitaxel was evaluated in human epidermal growth factor receptor 2-positive breast cancer in an open-label phase 1b clinical study.

Patients And Methods: Women with human epidermal growth factor receptor 2-positive breast cancer received weekly paclitaxel (80 mg/m), trastuzumab (8 mg/m then 6 mg/kg every 3 weeks), and intravenous trebananib (10 mg/kg or 30 mg/kg weekly) beginning week 2.

View Article and Find Full Text PDF

Background: Hypertension (HT) is identified as a highly prevalent cardiovascular risk factor and also as a separate disease entity, leading to significant mortality and morbidity. The rate of HT is increasing worldwide with a faster rate identified in developing countries. Thus, it is important to evaluate epidemiological patterns of chronic HT in a developing country like Sri Lanka.

View Article and Find Full Text PDF

Loss of ejaculation can follow transurethral resection of the prostate (TURP). Periverumontanal prostate tissue is preserved in ejaculation-preserving TURP (ep-TURP). Knowledge of ejaculatory duct anatomy in relation to the prostatic urethra can help in ep-TURP.

View Article and Find Full Text PDF

Objective: Treatment options for patients with recurrent ovarian carcinoma are diverse, and different therapies are recommended based on platinum-free interval (PFI). Data examining the association between platinum sensitivity, treatment strategy, and outcomes are limited, particularly for partially platinum-sensitive (PPS) patients. This study characterized clinical features and outcomes in patients with recurrent ovarian carcinoma in the context of sensitivity to platinum-based therapy.

View Article and Find Full Text PDF

Objective: To examine the tolerability and antitumor activity of trebananib plus pegylated liposomal doxorubicin (PLD) or topotecan in recurrent platinum-resistant or partially platinum-sensitive ovarian cancer.

Methods: In this open-label phase 1b study, patients received trebananib 10 mg/kg or 15 mg/kg IV QW plus PLD 50 mg/m(2) (cohorts A1 and A3, respectively) or topotecan 4 mg/m(2) (cohorts B1 and B3, respectively). Endpoints were dose-limiting toxicity (DLT; primary); treatment-emergent adverse events (AEs), overall response rate, anti-trebananib antibodies, and pharmacokinetics (secondary).

View Article and Find Full Text PDF

Atherosclerosis at the carotid bifurcation can result in cerebral emboli, which in turn can block the blood supply to the brain causing ischemic strokes. Noninvasive imaging tools that better characterize arterial wall, and atherosclerotic plaque structure and composition may help to determine the factors which lead to the development of unstable lesions, and identify patients at risk of plaque disruption and stroke. Carotid magnetic resonance (MR) imaging allows for the characterization of carotid vessel wall and plaque composition, the characterization of normal and pathological arterial wall, the quantification of plaque size, and the detection of plaque integrity.

View Article and Find Full Text PDF

Atherosclerosis at the carotid bifurcation resulting in cerebral emboli is a major cause of ischemic stroke. Most strokes associated with carotid atherosclerosis can be prevented by lifestyle/dietary changes and pharmacological treatments if identified early by monitoring carotid plaque changes. Registration of 3-D ultrasound (US) images of carotid plaque obtained at different time points is essential for sensitive monitoring of plaque changes in volume and surface morphology.

View Article and Find Full Text PDF

Background: The production of oxidative stress as a result of postprandial hyperglycaemia is now recognized as an important contributing factor in the development of diabetes complications. The objective of this study was to examine the effects of pramlintide on plasma concentrations of glucose and several markers of oxidative stress in patients with type 2 diabetes following a standardized meal.

Methods: This was a randomized, single-blind, placebo-controlled, crossover study conducted at two clinical research centres in the United States.

View Article and Find Full Text PDF

Estimation of prostate location and volume is essential in determining a dose plan for ultrasound-guided brachytherapy, a common prostate cancer treatment. However, manual segmentation is difficult, time consuming and prone to variability. In this paper, we present a semi-automatic discrete dynamic contour (DDC) model based image segmentation algorithm, which effectively combines a multi-resolution model refinement procedure together with the domain knowledge of the image class.

View Article and Find Full Text PDF

Context: First-phase insulin secretion (within 10 min after a sudden rise in plasma glucose) is reduced in type 2 diabetes mellitus (DM2). The incretin mimetic exenatide has glucoregulatory activities in DM2, including glucose-dependent enhancement of insulin secretion.

Objective: The objective of the study was to determine whether exenatide can restore a more normal pattern of insulin secretion in subjects with DM2.

View Article and Find Full Text PDF

Purpose: Hemodialysis vascular access dysfunction is an enormous clinical problem that causes great morbidity and costs well over one billion dollars per annum. The vast majority of hemodialysis vascular access dysfunction occurs as a result of venous stenosis and thrombosis at the graft-vein anastomosis. At a cellular level, this venous stenosis is the result of venous neointimal hyperplasia (VNH).

View Article and Find Full Text PDF