401 results on '"Owens, Christopher"'
Search Results
2. Havana Syndrome: Directed Attack or Cricket Noise?
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Mothershead, Jerry L., Dembek, Zygmunt F., Hann, Todd A., Owens, Christopher G., and Wu, Aiguo
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Company legal issue ,Military and naval science - Abstract
In late 2016, 21 American and Canadian diplomatic personnel stationed in Havana, Cuba, experienced unusual and unexplained health problems. Although symptoms varied among those affected, the onset of illness was [...]
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- 2023
3. Beliefs of University Employees Leaving During a Fire Alarm: A Theory-based Belief Elicitation
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Owens, Christopher, Le, Aurora B., Smith, Todd D., and Middlestadt, Susan E.
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- 2023
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4. Health Belief Model, Demographic, and Sexual Behavioral Factors Associated with Mpox Vaccination Among Men who have Sex with Men
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Owens, Christopher, primary and Hubach, Randolph Duane, additional
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- 2024
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5. Isotropic 3D black blood MRI of abdominal aortic aneurysm wall and intraluminal thrombus.
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Zhu, Chengcheng, Haraldsson, Henrik, Faraji, Farshid, Owens, Christopher, Gasper, Warren, Ahn, Sinyeob, Liu, Jing, Laub, Gerhard, Hope, Michael D, and Saloner, David
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Humans ,Aortic Valve Stenosis ,Aortic Aneurysm ,Abdominal ,Thrombosis ,Image Interpretation ,Computer-Assisted ,Imaging ,Three-Dimensional ,Magnetic Resonance Angiography ,Image Enhancement ,Sensitivity and Specificity ,Reproducibility of Results ,Anisotropy ,Algorithms ,Aged ,Male ,3D black blood ,Abdominal aortic aneurysm ,Blood suppression ,Intra-luminal thrombus ,Vessel wall MRI ,Rare Diseases ,Biomedical Imaging ,Clinical Research ,Cardiovascular ,Bioengineering ,Biomedical Engineering ,Clinical Sciences ,Cognitive Sciences ,Nuclear Medicine & Medical Imaging - Abstract
IntroductionThe aortic wall and intraluminal thrombus (ILT) have been increasingly studied as potential markers of progressive disease with abdominal aortic aneurysms (AAAs). Our goal was to develop a high resolution, 3D black blood MR technique for AAA wall and ILT imaging within a clinically acceptable scan time.MethodsTwenty two patients with AAAs (maximal diameter 4.3±1.0cm), along with five healthy volunteers, were imaged at 3T with a 3D T1-weighted fast-spin-echo sequence using variable flip angle trains (SPACE) with a preparation pulse (DANTE) for suppressing blood signal. Volunteers and ten patients were also scanned with SPACE alone for comparison purposes. The signal to noise ratio (SNR) and the aortic wall/ILT to lumen contrast to noise ratio (CNR) were measured. Qualitative image scores (1-4 scale) assessing the inner lumen and outer wall boundaries of AAA were performed by two blinded reviewers. In patients with ILT, the ratio of ILT signal intensity (ILTSI) over psoas muscle SI (MuscleSI) was calculated, and the signal heterogeneity of ILT was quantified as standard deviation (SD) over the mean.ResultsAll subjects were imaged successfully with an average scan time of 7.8±0.7minutes. The DANTE preparation pulse for blood suppression substantially reduced flow artifacts in SPACE with lower lumen SNR (8.8 vs. 21.4, p0.05). ILT was present in ten patients, with relatively high signal and a wide SD (average ILTSI/MuscleSI 1.42±0.48 (range 0.75-2.11)) and with SD/mean of 27.7%±6.6% (range 19.6%-39.4%).ConclusionHigh resolution, 3D black blood MRI of AAAs can be achieved in a clinical accepted scan time with reduction of flow artifacts using the DANTE preparation pulse. Signal characteristics of ILT can be quantified and may be used for improved patient-specific risk stratification.
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- 2016
6. Accuracy of TrUE-Net in comparison to established white matter hyperintensity segmentation methods: an independent validation study
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Strain, Jeremy F., primary, Rahmani, Maryam, additional, Dierker, Donna, additional, Owens, Christopher, additional, Jafri, Hussain, additional, Vlassenko, Andrei G., additional, Womack, Kyle, additional, Fripp, Jurgen, additional, Tosun, Duygu, additional, Benzinger, Tammie L.S., additional, Wiener, Michael W., additional, Masters, Colin, additional, Lee, Jin-Moo, additional, Morris, John C., additional, and Goyal, Manu S., additional
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- 2023
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7. Use of a rapid triage assessment tool to discriminate the need for hospitalisation in patients with severe COVID-19 infection presenting to an outpatient clinic: a single-centre, prospective cohort study
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Owens, Christopher, primary, Lamb, Chris, additional, Sanchez, Julio, additional, Quintero, Mariana, additional, and Lopez-Yunez, Alfredo, additional
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- 2023
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- View/download PDF
8. Measurement of brachial artery endothelial function using a standard blood pressure cuff
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Maltz, Jonathan S, Tison, Geoffrey H, Alley, Hugh F, Budinger, Thomas F, Owens, Christopher D, and Olgin, Jeffrey
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Engineering ,Biomedical Engineering ,Aging ,Clinical Research ,Bioengineering ,Cardiovascular ,Adult ,Blood Pressure Determination ,Brachial Artery ,Endothelium ,Vascular ,Female ,Humans ,Male ,Middle Aged ,Reference Standards ,Signal Processing ,Computer-Assisted ,Time Factors ,Ultrasonic Waves ,Vasodilation ,endothelial function ,arterial function ,cardiovascular disease ,smooth muscle ,reactive hyperemia ,atherosclerosis ,Electrical and Electronic Engineering ,Medical Physiology ,Medical physiology ,Biomedical engineering - Abstract
The integrity of endothelial function in major arteries (EFMA) is a powerful independent predictor of heart attack and stroke. Existing ultrasound-based non-invasive assessment methods are technically challenging and suitable only for laboratory settings. EFMA, like blood pressure (BP), is both acutely and chronically affected by factors such as lifestyle and medication. Consequently, laboratory-based measurements cannot fully gauge the effects of medical interventions on EFMA. EFMA and BP have, arguably, comparable (but complementary) value in the assessment of cardiovascular health. Widespread deployment of EFMA assessment is thus a desirable clinical goal. To this end, we propose a device based on modifying the measurement protocol of a standard electronic sphygmomanometer. The protocol involves inflating the cuff to sub-diastolic levels to enable recording of the pulse waveform before and after vasodilatory stimulus. The mechanical unloading of the arterial wall provided by the cuff amplifies the distension that occurs with each pulse, which is measured as a pressure variation in the cuff. We show that the height of the rising edge of each pulse is proportional to the change in lumen area between diastole and systole. This allows the effect of vasodilatory stimuli on the artery to be measured with high sensitivity. We compare the proposed cuff flow-mediated dilation (cFMD) method to ultrasound flow-mediated dilation (uFMD). We find significant correlation (r = 0.55, p = 0.003, N = 27) between cFMD- and uFMD-based metrics obtained when the release of a 5 min cuff occlusion is employed to induce endothelial stimulus via reactive hyperemia. cFMD is approximately proportional to the square of uFMD, representing a typical increase in sensitivity to vasodilation of 300-600%. This study illustrates the potential for an individual to conveniently measure his/her EFMA by using a low-cost reprogrammed home sphygmomanometer.
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- 2015
9. A New Testament.
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OWENS, CHRISTOPHER
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- 2024
10. Vascular inflammation in a growing iliac artery aneurysm.
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Hope, Michael D, Gasper, Warren J, Rapp, Joseph, Owens, Christopher D, Haraldsson, Henrik, and Saloner, David
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Humans ,Iliac Aneurysm ,Inflammation ,Positron-Emission Tomography ,Magnetic Resonance Imaging ,Middle Aged ,Male ,Multimodal Imaging ,vascular inflammation ,aneurysm ,PET/MRI ,macrophage imaging ,Biomedical Imaging ,Bioengineering ,Cardiovascular ,Clinical Sciences ,Nuclear Medicine & Medical Imaging - Abstract
We have used a multimodality imaging approach to assess the inflammatory component of a growing iliac artery aneurysm in a 53-year-old man who presented with related ureteral obstruction. Research suggests that episodic and heterogeneous inflammatory processes are important for the progression of aneurysms. The combined PET and MRI evaluation of inflammation that we present here is a novel approach to vascular imaging that is well suited for emerging hybrid PET/MRI systems.
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- 2015
11. Ferumoxytol-enhanced magnetic resonance angiography is a feasible method for the clinical evaluation of lower extremity arterial disease.
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Walker, Joy P, Nosova, Emily, Sigovan, Monica, Rapp, Joseph, Grenon, Marlene S, Owens, Christopher D, Gasper, Warren J, and Saloner, David A
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Lower Extremity ,Kidney ,Humans ,Gadolinium DTPA ,Contrast Media ,Magnetic Resonance Angiography ,Glomerular Filtration Rate ,Risk Factors ,Prospective Studies ,Feasibility Studies ,Pilot Projects ,Predictive Value of Tests ,Aged ,Middle Aged ,San Francisco ,Male ,Renal Insufficiency ,Ferrosoferric Oxide ,Peripheral Arterial Disease ,Cardiovascular ,Biomedical Imaging ,Patient Safety ,Clinical Research ,Kidney Disease ,4.2 Evaluation of markers and technologies ,4.1 Discovery and preclinical testing of markers and technologies ,Detection ,screening and diagnosis ,Clinical Sciences ,Cardiovascular System & Hematology - Abstract
BackgroundRenal toxicity from conventional, iodinated, intravenous contrast agents is a common complication in patients with peripheral artery disease (PAD). Similarly, the potential for serious side effects prevents the use of gadolinium-based agents in many patients with depressed renal function. Ferumoxytol-enhanced magnetic resonance angiography (Fe-MRA) is a novel technique that uses an intravenous, ultrasmall, superparamagnetic, iron oxide preparation, currently approved by the Food and Drug Administration for the treatment of iron deficiency anemia in adults with chronic kidney disease. Our objective was to determine the feasibility of Fe-MRA for clinical decision making in PAD patients.MethodsThis was a prospective pilot study assessing 10 patients with suspected arterial occlusive disease with contrast-enhanced MRA of the aorta and lower extremities. Of those, 5 had renal insufficiency and were imaged with Fe-MRA, whereas the remainder underwent gadolinium-enhanced MRA. Qualitative and quantitative evaluations of deidentified images at each arterial station were independently performed by 4 blinded vascular surgeons.ResultsAll patients were men, with an average age of 68 ± 4 years. The 2 groups had similar incidences of diabetes, hypertension, hyperlipidemia, and coronary artery disease. Patients undergoing Fe-MRA had significantly decreased renal function (estimated glomerular filtration rate, 35.4 vs. 77.6; P = 0.02). There were no adverse events during contrast administration in either group. No difference was found in the overall quality of the ferumoxytol versus the gadolinium studies (7.1 ± 2.0 vs. 7.4 ± 2.4, P = 0.67). Similarly, reviewers felt comfortable basing clinical decisions on the images 89% of the time with both the ferumoxytol and gadolinium groups (P = 1.00).ConclusionsThis is the first report of an important alternative to conventional computed tomography angiography and MRA in PAD patients, particularly in the setting of renal insufficiency. Fe-MRA provides a useful tool in patients with suspected lower extremity PAD without the potential risks of gadolinium.
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- 2015
12. Vein graft failure
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Owens, Christopher D, Gasper, Warren J, Rahman, Amreen S, and Conte, Michael S
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Prevention ,Cardiovascular ,Animals ,Graft Occlusion ,Vascular ,Hemodynamics ,Humans ,Hyperplasia ,Ischemia ,Lower Extremity ,Neointima ,Risk Factors ,Stress ,Mechanical ,Time Factors ,Treatment Failure ,Vascular Grafting ,Vascular Remodeling ,Veins ,Wound Healing ,Medical and Health Sciences ,Cardiovascular System & Hematology - Abstract
After the creation of an autogenous lower extremity bypass graft, the vein must undergo a series of dynamic structural changes to stabilize the arterial hemodynamic forces. These changes, which are commonly referred to as remodeling, include an inflammatory response, the development of a neointima, matrix turnover, and cellular proliferation and apoptosis. The sum total of these processes results in dramatic alterations in the physical and biomechanical attributes of the arterialized vein. The most clinically obvious and easily measured of these is lumen remodeling of the graft. However, although somewhat less precise, wall thickness, matrix composition, and endothelial changes can be measured in vivo within the healing vein graft. Recent translational work has demonstrated the clinical relevance of remodeling as it relates to vein graft patency and the systemic factors influencing it. By correlating histologic and molecular changes in the vein, insights into potential therapeutic strategies to prevent bypass failure and areas for future investigation are explored.
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- 2015
13. Relationship between kidney disease and endothelial function in peripheral artery disease
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Chong, Karen C, Owens, Christopher D, Park, Meyeon, Alley, Hugh F, Boscardin, W John, Conte, Michael S, Gasper, Warren J, and Grenon, S Marlene
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Prevention ,Nutrition ,Aging ,Cardiovascular ,Kidney Disease ,Clinical Research ,Renal and urogenital ,Aged ,Brachial Artery ,Comorbidity ,Cross-Sectional Studies ,Endothelium ,Vascular ,Female ,Glomerular Filtration Rate ,Humans ,Intermittent Claudication ,Kidney ,Kidney Diseases ,Linear Models ,Male ,Middle Aged ,Multivariate Analysis ,Peripheral Arterial Disease ,Predictive Value of Tests ,Prognosis ,Risk Factors ,San Francisco ,Vasodilation ,Veterans Health ,Medical and Health Sciences ,Cardiovascular System & Hematology - Abstract
ObjectiveWe have previously shown that peripheral artery disease (PAD) is associated with marked impairment of endothelial function (EF). Given that poor EF is associated with functional status of PAD patients as well as with increased morbidity and mortality in patients undergoing vascular procedures, determination of factors associated with poor EF in a PAD cohort is important. We hypothesized that decreased kidney function is associated with impaired EF in patients with PAD.MethodsThis was a cross-sectional study of PAD patients presenting to a vascular surgery outpatient clinic at the San Francisco Veterans Affairs Medical Center including patients enrolled in the OMEGA-PAD I trial (NCT01310270) and the OMEGA-PAD Cohort. Brachial artery flow-mediated vasodilation was performed to assess EF. Kidney function was characterized by estimated glomerular filtration rate with the abbreviated Modification of Diet in Renal Disease formula. Linear regression was performed to assess the relationship between EF and kidney function in claudicants.ResultsNinety-seven patients with intermittent claudication participated in this study. Mean age was 69 ± 8 years, 97% were male, and 79% were white. Comorbidities included hypertension (91%), dyslipidemia (87%), coronary artery disease (42%), and diabetes mellitus (38%). Mean ankle-brachial index was 0.73 ± 0.14 and mean flow-mediated vasodilation was 7.0% ± 3.8%, indicating impaired EF. Linear regression showed an association between kidney function and EF (by 10 mL/min/1.73 m(2); β, 0.12; confidence interval, 0.05-0.20; P = .001). After multivariable regression adjusting for age, race, log tumor necrosis factor α, hypertension, dyslipidemia, and diabetes, estimated glomerular filtration rate remained significantly associated with EF (P = .033).ConclusionsIn patients with PAD, decreased kidney function is associated with endothelial dysfunction. Further longitudinal studies are needed to better understand the impact of kidney function on PAD progression and the role of endothelial dysfunction in this process.
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- 2014
14. Clinical correlates of red blood cell omega-3 fatty acid content in male veterans with peripheral arterial disease
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Nosova, Emily V, Chong, Karen C, Alley, Hugh F, Harris, William S, Boscardin, W John, Conte, Michael S, Owens, Christopher D, and Grenon, S Marlene
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Aging ,Tobacco Smoke and Health ,Clinical Research ,Heart Disease ,Complementary and Integrative Health ,Tobacco ,Prevention ,Cardiovascular ,Nutrition ,Metabolic and endocrine ,Good Health and Well Being ,Age Factors ,Aged ,Ankle Brachial Index ,Biomarkers ,Body Mass Index ,Chi-Square Distribution ,Cross-Sectional Studies ,Dietary Supplements ,Docosahexaenoic Acids ,Eicosapentaenoic Acid ,Erythrocyte Membrane ,Female ,Humans ,Linear Models ,Male ,Middle Aged ,Multivariate Analysis ,Obesity ,Peripheral Arterial Disease ,Prospective Studies ,Risk Factors ,Smoking ,Veterans Health ,Medical and Health Sciences ,Cardiovascular System & Hematology - Abstract
ObjectiveDespite available medical therapies, patients with peripheral arterial disease (PAD) remain at high risk for cardiovascular events. The n-3 polyunsaturated fatty acids (PUFA), derived from marine sources, have been shown to improve cardiovascular mortality. The Omega-3 Index (O3I), a proportion of the n-3 PUFA eicosapentaenoic acid and docosahexaenoic acid in the red blood cell membrane, correlates with cardiovascular risk. Previous investigations have found that n-3 PUFA supplementation, fish consumption, older age, and smoking history affect the O3I in different patient populations, although similar correlations have never been explored in PAD. We hypothesized that in our PAD cohort, blood content of omega-3 fatty acids would directly and positively correlate with a history of fish oil supplementation and older age and inversely correlate with a smoking history and obesity.MethodsThis cross-sectional study included 111 patients who had an ankle-brachial index of
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- 2014
15. Short-term physical inactivity impairs vascular function
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Nosova, Emily V, Yen, Priscilla, Chong, Karen C, Alley, Hugh F, Stock, Eveline O, Quinn, Alex, Hellmann, Jason, Conte, Michael S, Owens, Christopher D, Spite, Matthew, and Grenon, S Marlene
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Cardiovascular ,Clinical Research ,Heart Disease ,Prevention ,2.1 Biological and endogenous factors ,Aetiology ,Bed Rest ,Biomarkers ,Blood Pressure ,Endothelium ,Vascular ,Female ,Healthy Volunteers ,Humans ,Hydroxyeicosatetraenoic Acids ,Inflammation ,Male ,Sedentary Behavior ,Vascular Stiffness ,Young Adult ,Arterial stiffness ,Endothelial dysfunction ,Physical inactivity ,Clinical Sciences ,Surgery - Abstract
BackgroundSedentarism, also termed physical inactivity, is an independent risk factor for cardiovascular diseases. Mechanisms thought to be involved include insulin resistance, dyslipidemia, hypertension, and increased inflammation. It is unknown whether changes in vascular and endothelial function also contribute to this excess risk. We hypothesized that short-term exposure to inactivity would lead to endothelial dysfunction, arterial stiffening, and increased vascular inflammation.MethodsFive healthy subjects (four men and one woman) underwent 5 d of bed rest (BR) to simulate inactivity. Measurements of vascular function (flow-mediated vasodilation to evaluate endothelial function; applanation tonometry to assess arterial resistance), inflammation, and metabolism were made before BR, daily during BR, and 2 d after BR recovery period. Subjects maintained an isocaloric diet throughout.ResultsBR led to significant decreases in brachial artery and femoral artery flow-mediated vasodilation (brachial: 11 ± 3% pre-BR versus 9 ± 2% end-BR, P = 0.04; femoral: 4 ± 1% versus 2 ± 1%, P = 0.04). The central augmentation index increased with BR (-4 ± 9% versus 5 ± 11%, P = 0.03). Diastolic blood pressure increased (58 ± 7 mm Hg versus 62 ± 7 mm Hg, P = 0.02), whereas neither systolic blood pressure nor heart rate changed. 15-Hydroxyeicosatetraenoic acid, an arachidonic acid metabolite, increased but the other inflammatory and metabolic biomarkers were unchanged.ConclusionsOur findings show that acute exposure to sedentarism results in decreased endothelial function, arterial stiffening, increased diastolic blood pressure, and an increase in 15-hydroxyeicosatetraenoic acid. We speculate that inactivity promotes a vascular "deconditioning" state characterized by impaired endothelial function, leading to arterial stiffness and increased arterial tone. Although physiologically significant, the underlying mechanisms and clinical relevance of these findings need to be further explored.
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- 2014
16. Vitamin D deficiency is associated with mortality and adverse vascular access outcomes in patients with end-stage renal disease
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Walker, Joy P, Hiramoto, Jade S, Gasper, Warren J, Auyang, Philip, Conte, Michael S, Rapp, Joseph H, Lovett, David H, and Owens, Christopher D
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Cardiovascular ,Kidney Disease ,Clinical Research ,Prevention ,Nutrition ,Good Health and Well Being ,Age Factors ,Aged ,Aged ,80 and over ,Arteriovenous Shunt ,Surgical ,Blood Vessel Prosthesis ,Calcifediol ,Calcium ,Catheterization ,Central Venous ,Cholesterol ,Coronary Disease ,Follow-Up Studies ,Humans ,Hyperlipidemias ,Kaplan-Meier Estimate ,Kidney Failure ,Chronic ,Middle Aged ,Proportional Hazards Models ,Retrospective Studies ,Risk Factors ,Serum Albumin ,Vitamin D Deficiency ,Medical and Health Sciences ,Cardiovascular System & Hematology - Abstract
BackgroundPlasma 25 hydroxycholecalciferol (vitamin D) deficiency has been associated with adverse cardiovascular outcomes in epidemiologic studies. Chronic kidney disease is associated with loss of 1α-hydroxylase and consequently vitamin D deficiency. We hypothesized that vitamin D deficiency was associated with increased mortality and increased vascular access failure in patients undergoing permanent vascular access for end-stage renal disease.MethodsThis retrospective cohort study analyzed 128 patients undergoing permanent vascular access surgery between 2003 and 2012 for whom concurrent plasma vitamin D levels were also available. Levels were considered deficient at
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- 2014
17. Walking disability in patients with peripheral artery disease is associated with arterial endothelial function
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Grenon, S Marlene, Chong, Karen, Alley, Hugh, Nosova, Emily, Gasper, Warren, Hiramoto, Jade, Boscardin, W John, and Owens, Christopher D
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Biomedical and Clinical Sciences ,Clinical Sciences ,Clinical Research ,Atherosclerosis ,Cardiovascular ,4.2 Evaluation of markers and technologies ,Detection ,screening and diagnosis ,Aged ,Ankle Brachial Index ,Arterial Pressure ,Biomarkers ,Brachial Artery ,C-Reactive Protein ,Case-Control Studies ,Chi-Square Distribution ,Cholesterol ,HDL ,Cholesterol ,LDL ,Cross-Sectional Studies ,Disability Evaluation ,Endothelium ,Vascular ,Female ,Humans ,Intermittent Claudication ,Linear Models ,Male ,Middle Aged ,Multivariate Analysis ,Peripheral Arterial Disease ,Predictive Value of Tests ,Risk Factors ,Self Report ,Severity of Illness Index ,Vasodilation ,Walking ,Medical and Health Sciences ,Cardiovascular System & Hematology ,Cardiovascular medicine and haematology ,Clinical sciences - Abstract
ObjectivePatients with peripheral artery disease (PAD) have varying degrees of walking disability that do not completely correlate with ankle-brachial index (ABI) or angiographic anatomy. We hypothesized that endothelial function (EF) is an independent predictor of symptom severity in PAD patients.MethodsThis was a cross-sectional study of 100 PAD patients presenting to a vascular surgery clinic. All patients received ABI testing and brachial artery flow-mediated, endothelium-dependent vasodilation (FMD) to assess arterial EF. Symptom severity and walking disability reported by Rutherford category was based on the patient's self-report during the clinic visit and recorded by the investigator-vascular surgeons. Demographic, biochemical, and physiologic parameters were entered into regression equations to determine association with symptom severity.ResultsPatients were a mean age of 66 ± 8 years, and 43% had diabetes. Mean FMD was 7.4%, indicating impaired EF. EF progressively declined as Rutherford category increased (P = .01). Brachial artery FMD, ABI, systolic blood pressure, C-reactive protein, low-density lipoprotein, high-density lipoprotein, β-blocker use, and a history of diabetes or coronary artery disease were all associated with Rutherford category (all P < .05). Multivariable regression showed EF (P < .02) and ABI (P < .0001) were independently associated with walking disability. When the cohort was restricted to claudicant patients (n = 73), EF remained associated with walking disability after adjustment for other covariates (P = .0001).ConclusionsSymptom severity in PAD is multifactorial, reflecting impaired hemodynamics and vascular dysfunction. This is the first report demonstrating that walking disability in PAD is associated with arterial EF. The mechanistic link underlying these observations remains to be defined.
- Published
- 2014
18. Safety and feasibility of adjunctive dexamethasone infusion into the adventitia of the femoropopliteal artery following endovascular revascularization
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Owens, Christopher D, Gasper, Warren J, Walker, Joy P, Alley, Hugh F, Conte, Michael S, and Grenon, S Marlene
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Cardiovascular ,Bioengineering ,Patient Safety ,Clinical Trials and Supportive Activities ,Genetics ,Atherosclerosis ,Biomedical Imaging ,Clinical Research ,6.1 Pharmaceuticals ,Evaluation of treatments and therapeutic interventions ,Adventitia ,Aged ,Angioplasty ,Balloon ,Anti-Inflammatory Agents ,Blood Flow Velocity ,Chronic Disease ,Constriction ,Pathologic ,Dexamethasone ,Female ,Femoral Artery ,Humans ,Infusions ,Intralesional ,Male ,Middle Aged ,Peripheral Arterial Disease ,Pilot Projects ,Popliteal Artery ,Prospective Studies ,Radiography ,Regional Blood Flow ,San Francisco ,Secondary Prevention ,Stents ,Time Factors ,Treatment Outcome ,Ultrasonography ,Doppler ,Duplex ,Vascular Patency ,Medical and Health Sciences ,Cardiovascular System & Hematology - Abstract
ObjectiveRestenosis following endovascular treatment of the femoropopliteal segment is associated with the inflammatory response produced in the artery wall at the time of the procedure. Although local drug delivery to the superficial femoral and popliteal arteries promises improved patency, data are currently limited. We hypothesized that improved percutaneous delivery of an anti-inflammatory compound into the adventitia of the femoropopliteal at the time of endovascular treatment would be safe, feasible, and decrease the inflammatory response.MethodsThis was a prospective, investigator-initiated, phase I, first-in-man study testing the safety and feasibility of percutaneous adventitial delivery of dexamethasone. Following successful intervention, an adventitial microinfusion catheter was advanced over a 0.014-inch wire to the treated segment. Its microneedle (0.9 mm long × 140-μm diameter) was deployed into the adventitia to deliver dexamethasone (4 mg/mL) mixed with contrast agent (80:20 ratio), providing fluoroscopic visualization. The primary safety outcome measure was freedom from vessel dissection, thrombosis, or extravasation while the primary efficacy outcome was duplex-determined binary restenosis defined as a peak systolic velocity ratio >2.5.ResultsTwenty patients with Rutherford clinical category 2-5 enrolled in this study. The mean age was 66, and 55% had diabetes mellitus. Treated lesion length was 8.9 ± 5.3 cm, and 50% were chronic total occlusions. Eighty percent of treated lesions were in the distal superficial femoral or popliteal arteries. All lesions were treated by balloon angioplasty with provisional stenting (n = 6) for suboptimal result. Three patients were treated with atherectomy as well. A mean of 1.6 ± 1.1 mg (0.5 ± 0.3 mL) of dexamethasone sodium phosphate was injected per centimeter of lesion length. In total, a mean of 12.1 ± 6.1 mg of dexamethasone was injected per patient. The mean number of injections required per lesion was 3.0 ± 1.3 cm, minimum one and maximum six injections. There was 100% technical success of drug delivery and no procedural or drug-related adverse events. The mean Rutherford score decreased from 3.1 ± .7 (median, 3.0) preoperatively to .5 ± .7 at 6 months (median, 0.0; P < .00001). Over this same time interval, the index leg ankle-brachial index increased from .68 ± .15 to .89 ± .19 (P = .0003). The preoperative C-reactive protein in this study was 6.9 ± 8.5 indicating severe baseline inflammation, which increased to 14.0 ± 23.1 mg/L (103% increase) at 24 hours following the procedure. However, this increase did not reach statistical significance of P = .14. Two patients met the primary efficacy end point of loss of primary patency by reoccluding their treated segment of the index lesion during the follow-up period.ConclusionsAdventitial drug delivery via a microinfusion catheter is a safe and feasible alternative to intimal-based methods for adjunctive treatment in the femoropopliteal segment. The 6-month preliminary results suggest perivascular dexamethasone treatment may improve outcomes following angioplasty to the femoral and popliteal arteries, and support further clinical investigation of this approach.
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- 2014
19. Adventitial Nab-Rapamycin Injection Reduces Porcine Femoral Artery Luminal Stenosis Induced by Balloon Angioplasty via Inhibition of Medial Proliferation and Adventitial Inflammation
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Gasper, Warren J, Jimenez, Cynthia A, Walker, Joy, Conte, Michael S, Seward, Kirk, and Owens, Christopher D
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Bioengineering ,Cardiovascular ,Adventitia ,Angioplasty ,Balloon ,Animals ,Arteritis ,Cell Movement ,Cell Proliferation ,Constriction ,Pathologic ,Disease Models ,Animal ,Dose-Response Relationship ,Drug ,Femoral Artery ,Fibrosis ,Injections ,Intra-Arterial ,Leukocytes ,Male ,Nanoparticles ,Sirolimus ,Swine ,Tunica Media ,coronary restenosis ,drug delivery systems ,peripheral arterial disease ,sirolimus ,Cardiorespiratory Medicine and Haematology ,Clinical Sciences ,Public Health and Health Services ,Cardiovascular System & Hematology - Abstract
BackgroundEndovascular interventions on peripheral arteries are limited by high rates of restenosis. Our hypothesis was that adventitial injection of rapamycin nanoparticles would be safe and reduce luminal stenosis in a porcine femoral artery balloon angioplasty model.Methods and resultsEighteen juvenile male crossbred swine were included. Single-injury (40%-60% femoral artery balloon overstretch injury; n=2) and double-injury models (endothelial denudation injury 2 weeks before a 20%-30% overstretch injury; n=2) were compared. The double-injury model produced significantly more luminal stenosis at 28 days, P=0.002, and no difference in medial fibrosis or inflammation. Four pigs were randomized to the double-injury model and adventitial injection of saline (n=2) or 500 μg of nanoparticle albumin-bound rapamycin (nab-rapamycin; n=2) with an endovascular microinfusion catheter. There was 100% procedural success and no difference in endothelial regeneration. At 28 days, nab-rapamycin led to significant reductions in luminal stenosis, 17% (interquartile range, 12%-35%) versus 10% (interquartile range, 8.3%-14%), P=0.001, medial cell proliferation, P
- Published
- 2013
20. Association between n-3 polyunsaturated fatty acid content of red blood cells and inflammatory biomarkers in patients with peripheral artery disease
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Grenon, S Marlene, Conte, Michael S, Nosova, Emily, Alley, Hugh, Chong, Karen, Harris, William S, Vittinghoff, Eric, and Owens, Christopher D
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Complementary and Integrative Health ,Nutrition ,Prevention ,Cardiovascular ,Clinical Research ,Inflammatory and immune system ,Aged ,Ankle Brachial Index ,Biomarkers ,Brachial Artery ,C-Reactive Protein ,Cross-Sectional Studies ,Endothelium ,Vascular ,Erythrocytes ,Fatty Acids ,Omega-3 ,Humans ,Inflammation Mediators ,Linear Models ,Logistic Models ,Male ,Middle Aged ,Peripheral Arterial Disease ,Predictive Value of Tests ,Prognosis ,Vasodilation ,Medical and Health Sciences ,Cardiovascular System & Hematology - Abstract
ObjectiveThe n-3 polyunsaturated fatty acids are dietary components derived from fish oil with beneficial cardiovascular effects that may relate in part to anti-inflammatory properties. Peripheral artery disease (PAD) is characterized by a marked proinflammatory state. We hypothesized that the n-3 polyunsaturated fatty acids content of red blood cells (omega-3 index) would be correlated with biomarkers of inflammation and vascular function in a PAD cohort.MethodsThis was a cross-sectional study of subjects who presented to an outpatient vascular surgery clinic for evaluation of PAD. We used linear regression to evaluate the independent association between the omega-3 index, inflammatory biomarkers (C-reactive protein [CRP], intercellular adhesion molecule-1, interleukin-6, and tumor-necrosis-factor-α) and endothelial function (brachial artery flow mediated dilation).Results64 subjects (61 claudicants and three with critical limb ischemia) were recruited for the study. The mean CRP level was 5.0 ± 5.0 mg/L, and the mean omega-3 index was 5.0% ± 1.8%. In an unadjusted model, the omega-3 index was negatively associated with CRP (38% increase in CRP for one standard deviation decrease in the omega-3 index; P = .007), which remained significant after adjustment for age, body mass index, smoking, ankle-brachial index, and high-density lipoprotein (33%; P = .04). There was also evidence for independent associations between the omega-3 index and IL-6 (P = .001). There were no significant associations between the omega-3 index and vascular function tests.ConclusionsIn a cohort of patients with PAD, the omega-3 index was inversely associated with biomarkers of inflammation even after adjustment for covariates including the ankle-brachial index. Because patients with PAD have a high inflammatory burden, further studies should be conducted to determine if manipulation of omega-3 index via dietary changes or fish oil supplementation could improve inflammation and symptoms in these patients.
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- 2013
21. n-3 Polyunsaturated fatty acids supplementation in peripheral artery disease: the OMEGA-PAD trial
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Grenon, S Marlene, Owens, Christopher D, Alley, Hugh, Chong, Karen, Yen, Priscilla K, Harris, William, Hughes-Fulford, Millie, and Conte, Michael S
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Prevention ,Clinical Trials and Supportive Activities ,Clinical Research ,Cardiovascular ,Nutrition ,Complementary and Integrative Health ,Heart Disease ,Atherosclerosis ,6.1 Pharmaceuticals ,Prevention of disease and conditions ,and promotion of well-being ,3.3 Nutrition and chemoprevention ,Evaluation of treatments and therapeutic interventions ,Good Health and Well Being ,Aged ,Clinical Protocols ,Cohort Studies ,Dietary Supplements ,Double-Blind Method ,Endothelium ,Vascular ,Fatty Acids ,Omega-3 ,Female ,Humans ,Inflammation ,Male ,Middle Aged ,Peripheral Arterial Disease ,fatty acids ,peripheral artery disease ,randomized controlled trials ,Clinical Sciences ,Cardiovascular System & Hematology - Abstract
Despite current consensus guidelines recommending intensive cardiovascular risk factor management for peripheral artery disease (PAD), patients suffering from PAD continue to experience significant morbidity and mortality. This excess morbid burden is at least partially related to impaired vascular function and systemic inflammation. Interventions bridging this gap are critical. Dietary supplementation of n-3 polyunsaturated fatty acids (n-3 PUFA) has been shown to improve endothelial function and reduce inflammation in different cohorts, as well as to decrease cardiovascular events in secondary prevention trials in patients with coronary artery disease. Their effects in the PAD population are, however, less well understood. The OMEGA-PAD trial is a double-blinded, randomized, placebo-controlled trial that examines the impact of a high-dose, short-duration dietary oral supplementation of n-3 PUFA on vascular function and inflammation in patients with established PAD. The purpose of this article is to provide a detailed description of the design and methods of the OMEGA-PAD trial, and a summary of baseline characteristics of the cohort.
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- 2013
22. Sport and physical activity participation and sedentary behaviour among adolescents : exploring the transition from compulsory education
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Owens, Christopher Stephen, James, David, Crone, Diane, and De Ste Croix, Mark
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796 ,GV557 Sports - Abstract
The move out of compulsory education is a key transition period in adolescents' lives. The aim of the present study was to investigate physical activity and sedentary behaviour (using 'screen time' as the proxy measure) among adolescents during the transition from completing compulsory education to entering further education, training or (un)employment. A prospective population-based longitudinal design was adopted, using a large cohort of adolescents in Gloucestershire. A questionnaire was administered to participants at two time points (baseline and follow-up). At baseline, 2204 Year 11 pupils (aged 14 to 17 years) and at follow-up, 886 participants from the baseline sample (aged 15 to 17 years) completed the questionnaire. ( For all statistical analyses performed, two sets of analysis were conducted. Analysis one included the final sample of participants (n = 663) who had an associated output area (OA) code to include in statistical analyses and analysis two included the final sample of participants (n = 834) who did not have an associated OA code included in statistical analyses. Since the overall findings for each analysis were similar, only findings from analysis one are presented. For physical activity, there was a significant change in the number of participants meeting guidelines at baseline but not meeting guidelines at follow-up. For screen time status, there was no significant change between baseline and follow-up. Binary logistic regression (BLR) revealed that for gender, in comparison to males, females were 52.4% less likely to meet guidelines for physical activity at follow-up. Meanwhile, BLR revealed that there were no significant associations with screen time status at follow-up. Further BLR for the decline in physical activity through the transition, revealed that for gender, in comparison to males, females were 42.4% less likely to move from meeting guidelines at baseline to not meeting guidelines at follow-up (i.e., physical activity decline was associated with being male). The findings of the present study have demonstrated: i) a decline in physical activity through the transition; ii) the high proportion of adolescents not meeting guidelines for screen time at either baseline or follow-up; and iii) associations between gender and physical activity during this transitional period. There is a need for future research to longitudinally examine adolescents' physical activity and sedentary behaviour during this transitional period.
- Published
- 2012
23. Peripheral artery disease and risk of cardiovascular events in patients with coronary artery disease: Insights from the Heart and Soul Study
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Grenon, S Marlene, Vittinghoff, Eric, Owens, Christopher D, Conte, Michael S, Whooley, Mary, and Cohen, Beth E
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Biomedical and Clinical Sciences ,Cardiovascular Medicine and Haematology ,Clinical Sciences ,Clinical Research ,Heart Disease ,Prevention ,Cardiovascular ,Heart Disease - Coronary Heart Disease ,Atherosclerosis ,Detection ,screening and diagnosis ,Aetiology ,4.2 Evaluation of markers and technologies ,2.1 Biological and endogenous factors ,Aged ,Biomarkers ,Coronary Artery Disease ,Disease Progression ,Female ,Humans ,Incidence ,Inflammation Mediators ,Male ,Middle Aged ,Multivariate Analysis ,Peripheral Arterial Disease ,Prognosis ,Proportional Hazards Models ,Prospective Studies ,Risk Factors ,San Francisco ,Time Factors ,coronary disease ,peripheral artery disease ,Cardiovascular System & Hematology ,Cardiovascular medicine and haematology ,Clinical sciences - Abstract
Among patients with coronary artery disease (CAD), those with peripheral artery disease (PAD) have a greater vulnerability to cardiovascular (CV) events than those with CAD alone. In a prospective cohort study of patients with CAD, we evaluated potential mechanisms that might explain the adverse CV outcomes associated with PAD. We performed a prospective cohort study of 1018 patients with stable CAD who were recruited from 2000 to 2002. Incident symptomatic PAD events were adjudicated during a follow-up period of 7.2 ± 2.6 years. We used Cox proportional hazards models to evaluate the association between incident symptomatic PAD events and subsequent risk of CV events or death. Models were adjusted for demographics, traditional risk factors, inflammation, insulin resistance and health behaviors. Among the 1018 patients, 50 patients who did not report a history of PAD at baseline suffered incident symptomatic PAD events during the follow-up period. Those patients had a higher risk of subsequent CV events and death compared to those who did not develop PAD. After adjustment for traditional risk factors, symptomatic PAD events remained associated with a 70% increased risk of subsequent CV events (adjusted HR 1.7; 95% CI 1.0, 2.9; p = 0.04) and an 80% increased risk of death (adjusted HR 1.8; 95% CI 1.2, 2.7; p = 0.006). Inflammatory biomarkers were the strongest risk factor contributing to the excess risk. In a contemporary cohort of patients with CAD, incident symptomatic PAD events were associated with an increased risk for subsequent CV events. The increased vulnerability to CV events was partially explained by shared CV risk factors and inflammation.
- Published
- 2013
24. A single nucleotide polymorphism in the p27Kip1 gene is associated with primary patency of lower extremity vein bypass grafts
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Conte, Michael S, Owens, Christopher D, Belkin, Michael, Creager, Mark A, Edwards, Karen L, Gasper, Warren J, Kenagy, Richard D, LeBoeuf, Renee C, Sobel, Michael, and Clowes, Alexander
- Subjects
Bioengineering ,Cardiovascular ,Genetics ,Clinical Research ,Aged ,Critical Illness ,Cyclin-Dependent Kinase Inhibitor p27 ,Female ,Gene Frequency ,Genetic Association Studies ,Genetic Predisposition to Disease ,Graft Occlusion ,Vascular ,Humans ,Intermittent Claudication ,Ischemia ,Lower Extremity ,Male ,Middle Aged ,Multivariate Analysis ,Peripheral Arterial Disease ,Phenotype ,Polymorphism ,Single Nucleotide ,Promoter Regions ,Genetic ,Proportional Hazards Models ,Retrospective Studies ,Risk Factors ,Time Factors ,Treatment Outcome ,Ultrasonography ,Doppler ,Duplex ,United States ,Vascular Grafting ,Vascular Patency ,Veins ,Medical and Health Sciences ,Cardiovascular System & Hematology - Abstract
ObjectiveFactors responsible for the variability in outcomes after lower extremity vein bypass grafting (LEVBG) are poorly understood. Recent evidence has suggested that a single nucleotide polymorphism (SNP) in the promoter region of the p27(Kip1) gene, a cell-cycle regulator, is associated with coronary in-stent restenosis. We hypothesized an association with vein graft patency.MethodsThis was a retrospective genetic association study nested within a prospective cohort of 204 patients from three referral centers undergoing LEVBG for claudication or critical ischemia. The main outcome measure was primary vein graft patency.ResultsAll patients were followed up for a minimum of 1 year with duplex graft surveillance (median follow-up, 893 days; interquartile range, 539-1315). Genomic DNA was isolated and SNP analysis for the p27(Kip1)-838C>A variants was performed. Allele frequencies were correlated with graft outcome using survival analysis and Cox proportional hazards modeling. The p27(Kip1)-838C>A allele frequencies observed were CA, 53%; CC, 30%; and AA, 17%, satisfying Hardy-Weinberg equilibrium. Race (P = .025) and history of coronary artery disease (P = .027) were different across the genotypes; all other baseline variables were similar. Primary graft patency was greater among patients with the -838AA genotype (75% AA vs 55% CA/CC at 3 years; P = .029). In a Cox proportional hazards model including age, sex, race, diabetes, critical limb ischemia, redo (vs primary) bypass, vein type, and baseline C-reactive protein level, the p27(Kip1)-838AA genotype was significantly associated with higher graft patency (hazard ratio for failure, 0.4; 95% confidence interval, 0.17-0.93). Genotype was also associated with early (0-1 month) changes in graft lumen diameter by ultrasound imaging.ConclusionsThese data suggest that the p27(Kip1)-838C>A SNP is associated with LEVBG patency and, together with previous reports, underscore a central role for p27(Kip1) in the generic response to vascular injury.
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- 2013
25. Vascular Remodeling in Autogenous Arterio-Venous Fistulas by MRI and CFD
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Sigovan, Monica, Rayz, Vitaliy, Gasper, Warren, Alley, Hugh F, Owens, Christopher D, and Saloner, David
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Fluid Mechanics and Thermal Engineering ,Engineering ,Biomedical Engineering ,Biomedical Imaging ,Bioengineering ,Clinical Research ,Kidney Disease ,Aged ,Aged ,80 and over ,Arm ,Arteriovenous Shunt ,Surgical ,Hemodynamics ,Humans ,Hydrodynamics ,Imaging ,Three-Dimensional ,Magnetic Resonance Angiography ,Male ,Middle Aged ,Postoperative Complications ,Renal Dialysis ,Computational fluid dynamics ,Magnetic resonance imaging ,Vascular access ,Hemodialysis fistula ,Vascular remodeling ,WSS - Abstract
Hemodynamic parameters play an important role in regulating vascular remodeling in arterio-venous fistula (AVF) maturation. Investigating the changes in hemodynamic parameters during AVF maturation is expected to improve our understanding of fistula failure, but very little data on actual temporal changes in human AVFs is available. The present study aimed to assess the feasibility of using a noncontrast-enhanced MRI protocol combined with CFD modeling to relate hemodynamic changes to vascular remodeling following native AVF placement. MR angiography (MRA) and MR velocimetry (MRV) data was acquired peri-operatively, 1 month, and 3 months later in three patients. Vascular geometries were obtained by segmentation of the MRA images. Pulsatile flow simulations were performed in the patient specific vascular geometries with time-dependent boundary conditions prescribed from MRV measurements. A principal result of the study is the description of WSS changes over time in the same patients. The disturbed flow observed in the venous segments resulted in a variability of the WSS distribution and could be responsible for the non-uniform remodeling of the vessel. The artery did not show regions of disturbed flow upstream from the anastomosis, which would be consistent with the uniform remodeling. MRI use demonstrated the ability to provide a comprehensive evaluation of clinically relevant information for the investigation of upper extremity AVFs. 3D geometry from MRA in combination with MRV provides the opportunity to perform detailed CFD analysis of local hemodynamics in order to determine flow descriptors affecting fistula maturation.
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- 2013
26. Thirty-day vein remodeling is predictive of midterm graft patency after lower extremity bypass
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Gasper, Warren J, Owens, Christopher D, Kim, Ji Min, Hills, Nancy, Belkin, Michael, Creager, Mark A, and Conte, Michael S
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Clinical Research ,Cardiovascular ,Aged ,Biomarkers ,Boston ,C-Reactive Protein ,Female ,Genetic Testing ,Graft Occlusion ,Vascular ,Humans ,Inflammation Mediators ,Kaplan-Meier Estimate ,Linear Models ,Longitudinal Studies ,Lower Extremity ,Male ,Middle Aged ,Multivariate Analysis ,Peripheral Arterial Disease ,Proportional Hazards Models ,Prospective Studies ,Time Factors ,Treatment Outcome ,Ultrasonography ,Doppler ,Duplex ,Vascular Patency ,Veins ,Medical and Health Sciences ,Cardiovascular System & Hematology - Abstract
ObjectiveSuccessful adaptation of a vein graft to an arterial environment is incompletely understood. We sought to investigate whether early vein graft remodeling is predictive of subsequent patency.MethodsA prospective longitudinal study was conducted of 67 patients undergoing lower extremity bypass with autogenous vein between February 2004 and April 2008. Preoperative blood samples were drawn for biomarkers. During the bypass operation, a 5-cm index segment of the graft was registered for serial lumen diameter measurements at 0, 1, 3, 6, 9, and 12 months using duplex ultrasound imaging. The imaging substudy analysis included patients with at least two ultrasound assessments.ResultsPatients (55% male) were a median age of 70 years (interquartile range [IQR], 59-76 years), 40% had diabetes mellitus, 49% had critical limb ischemia, 75% were taking a statin, and 91% were taking an antiplatelet medication. Median follow-up was 32 months (IQR, 15-47 months). The median baseline high-sensitivity C-reactive protein level (hsCRP) was 3.2 mg/L (IQR, 1.4-9.7 mg/L). The average intraoperative, postimplantation vein lumen diameter was 3.9±1.0 mm, increasing to 4.7±1.1 mm at 1 month, an average 24%±27% change per patient. By 3 months, the average lumen diameter was 5.1±1.6 mm, with little subsequent change observed to 12 months. Nonwhite race, baseline hsCRP ≥5 mg/L, statin use, and initial lumen diameter were significantly associated with early (0- to 1-month) vein remodeling in a multivariable regression model. The primary patency rate for the cohort was 60%±6.3% at 2 years. Initial lumen diameter of the index segment was not associated with primary patency, whereas larger lumen diameter achieved at 1 month (≥5.1 mm) was positively associated with primary patency (log-rank, P=.03). Early (30-day) remodeling behavior was used to divide patients into "poor remodelers" (+25% change, n=30). Early remodeling category was significantly associated with primary patency rate at 2 years (log-rank, P=.02). A multivariable Cox proportional hazards model showed that modest remodelers (hazard ratio, 3.9; 95% confidence interval, 1.02-15; P=.04) and poor remodelers (hazard ratio, 13; 95% confidence interval; P=.008) had significantly higher hazard ratios for graft failure than robust early remodelers.ConclusionsEarly remodeling of the arterialized vein appears to predict midterm bypass graft patency. In addition to baseline diameter, race, inflammation, hsCRP, and statin use are associated with early adaptive remodeling, but the mechanisms for these observations are not understood.
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- 2013
27. USPIO-enhanced MR Angiography of Arteriovenous Fistulas in Patients with Renal Failure
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Sigovan, Monica, Gasper, Warren, Alley, Hugh F, Owens, Christopher D, and Saloner, David
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Biomedical and Clinical Sciences ,Clinical Sciences ,Clinical Research ,Biomedical Imaging ,Kidney Disease ,Anastomosis ,Surgical ,Arteriovenous Anastomosis ,Contrast Media ,Dextrans ,Female ,Humans ,Image Enhancement ,Magnetic Resonance Angiography ,Magnetite Nanoparticles ,Male ,Renal Insufficiency ,Reproducibility of Results ,Sensitivity and Specificity ,Medical and Health Sciences ,Nuclear Medicine & Medical Imaging ,Clinical sciences - Abstract
PurposeTo determine the feasibility of using ferumoxytol-enhanced magnetic resonance (MR) angiography to depict the vasculature of hemodialysis fistulas and improve image quality compared with nonenhanced time-of-flight (TOF) MR angiography.Materials and methodsThe study was institutional review board approved and was in compliance with HIPAA regulations. All participants provided written informed consent. TOF and first-pass ferumoxytol-enhanced MR angiography were performed in 10 patients with upper extremity autogenous fistulas. Ferumoxytol was administered as a bolus solution containing 430 μmol of elemental iron. A qualitative comparison was performed on maximum intensity projection images. Lumen depiction was evaluated by using a five-point scale. The uniformity of intraluminal signal intensity was measured as the ratio between the mean signal intensity of the entirety of the imaged fistula and its standard deviation. The contrast-to-noise ratio (CNR) between intraluminal signal and adjacent tissue was evaluated as a function of image acquisition time. Lumen depiction scores, luminal signal heterogeneity, and CNR efficiency were compared between TOF and ferumoxytol-enhanced MR angiography by using a Wilcoxon-Mann-Whitney test.ResultsFlow artifacts were greatly reduced by the use of ferumoxytol-enhanced MR angiography. Ferumoxytol-enhanced MR angiography had significantly better performance than TOF MR angiography as measured with the following: lumen depiction scores in all segments (mean, 4.7±0.1 [standard error of the mean]; vs 3.0±0.3 for arterial inflow, 4.1±0.3 vs 1.9±0.3 for arterial outflow, 3.7±0.3 vs 1.8±0.2 for anastomosis, and 4.5±0.2 vs 2.1±0.2 for venous outflow; P
- Published
- 2012
28. Sex-based differences in the inflammatory profile of peripheral artery disease and the association with primary patency of lower extremity vein bypass grafts
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Hiramoto, Jade S, Owens, Christopher D, Kim, Ji Min, Boscardin, John, Belkin, Michael, Creager, Mark A, and Conte, Michael S
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Cardiovascular ,Clinical Research ,Heart Disease ,Aged ,C-Reactive Protein ,Female ,Fibrinogen ,Humans ,Male ,Middle Aged ,Multivariate Analysis ,Peripheral Arterial Disease ,Proportional Hazards Models ,Prospective Studies ,Sex Factors ,Vascular Patency ,Vascular Surgical Procedures ,Medical and Health Sciences ,Cardiovascular System & Hematology - Abstract
ObjectiveThis study was conducted to determine if there are sex-based differences in the inflammatory phenotype of patients undergoing lower extremity bypass (LEB) and if they correlate with clinical outcomes.MethodsThis was a retrospective analysis of a prospective cohort of 225 patients (161 men and 64 women) who underwent autogenous vein LEB between February 2004 and May 2008. Fasting baseline blood samples were obtained before LEB, and the inflammatory biomarkers high-sensitivity C-reactive protein (CRP) and fibrinogen were assessed. All patients underwent ultrasound graft surveillance. CRP levels were dichotomized at 5 mg/L and fibrinogen levels at 600 mg/dL.ResultsThere were no significant differences in age, race, history of hypertension or diabetes mellitus, body mass index, or coronary artery disease between men and women. Men were more likely to be current smokers (P = .02), have a history of hypercholesterolemia (P = .02), and be taking statins (P = .02). Women were more likely to present with critical limb ischemia (P = .03) and had higher median baseline CRP levels (5.15 mg/L; interquartile range [IQR], 1.51-18.62 mg/L) than men (2.70; IQR, 1.24-6.98 mg/L; P = .02). Median follow-up was 893 days (IQR, 539-1315 days). A multivariable Cox proportional hazards model for primary vein graft patency showed a significant interaction between sex and CRP (P = .03) and fibrinogen (P = .02). After adjustment for key covariates, primary vein graft patency was significantly less in women with CRP >5 mg/L compared with women with CRP 600 mg/dL vs women with fibrinogen
- Published
- 2012
29. Proving correctness of modular functional programs
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Owens, Christopher, Gilmore, Stephen., and Anderson, Stuart
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004.01 - Abstract
One reason for studying and programming in functional programming languages is that they are easy to reason about, yet there is surprisingly little work on proving the correctness of large functional programs. In this dissertation I show how to provide a system for proving the correctness of large programs written in a major functional programming language, ML. ML is split into two parts: the Core (in which the actual programs are written), and Modules (which are used to structure Core programs). The dissertation has three main themes: Due to the detail and complexity of proofs of programs, a realistic system should use a computer proof assistant, and so I first discuss how such a system can be coded in a generic proof assistant (I use Paulson's Isabelle). I give a formal proof system for proving properties of programs written in the functional part of Core ML. The Modules language is one of ML's strengths: it allows the programmer to write large programs by controlling the interactions between its parts. In the final part of the dissertation I give a method of proving correctness of ML Modules programs using the well-known data reification method. Proofs of reification using this method boil down to proofs in the system for the Core.
- Published
- 1999
30. Evaluating Johnson and Johnson COVID-19 Vaccination Outcomes in a Low-Income Hispanic Population
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Lamb, Christopher, primary, Owens, Christopher, additional, Gamboa, Wendy, additional, and Lopez-Yunez, Alfredo, additional
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- 2023
- Full Text
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31. Pharmacist Knowledge and Perceptions of Homeopathy: A Survey of Recent Pharmacy Graduates in Practice
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Millward, Jordin, primary, McKay, Kasidy, additional, Holmes, John T., additional, and Owens, Christopher T., additional
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- 2022
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32. Problem-Solving Stereotypes for an Intelligent Assistant
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Owens, Christopher
- Abstract
This paper examines the role of case-based reasoning in a problem-solving assistant system, which differs from an autonomous problem solver in that it shares the problem-solving task with a human partner. The paper focuses on the criteria driving the system designer's (or the system's) choice of cases, of representation vocabulary, and of indexing terms, and upon how the assumption of a human in the problem-solving loop influences these criteria. It presents these theoretical considerations in the context of work in progress on lOPS, a case-based intelligent assistant for airline irregular operations scheduling.
- Published
- 1992
33. A Functional Taxonomy of Abstract Plan Failures
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Owens, Christopher
- Abstract
To reason about a plan failure requires an appropriate explanation of the failure. Such explanations, as has been argued elsewhere, can be generated by instantiating and adapting abstract knowledge structures. But the two fundamental goals in reasoning about failure, recovering from the failure and repairing the knowledge that led to the failure, require qualitatively different types of explanation. This paper presents an abstract taxonomization of failures, oriented toward the latter problem. Each abstract failure type in the taxonomy is tied to heuristics for recognizing occurrences of failures of that type and for identifying the knowledge that can be repaired to avoid future occurrences of the same failure.
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- 1991
34. Representing abstract plan failures
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Owens, Christopher
- Published
- 1990
35. The COVID-19 Pandemic in a Hispanic Population: A Primary Care Perspective
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Owens, Christopher D., primary, Pertuz, Gerardo M., additional, Sanchez, Julio C., additional, Ayala, Jorge, additional, Pimentel, Lindsey H., additional, Lamb, Christopher, additional, Lopez Mayo, Yelyt E., additional, and Yunez, Alfredo Lopez, additional
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- 2022
- Full Text
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36. Beliefs about Staying Home: Findings from a Nationally Representative Probability Sample of U.S. Adults in the Early Days of the COVID-19 Epidemic
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Owens, Christopher, primary, Middlestadt, Susan E, additional, Dickinson, Stephanie, additional, Hunter-Mullis, Kristina, additional, and Macy, Jonathan T, additional
- Published
- 2022
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37. Diagnosis, classification, and treatment of femoropopliteal artery in-stent restenosis
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Ho, Karen J. and Owens, Christopher D.
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- 2017
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38. Statins and other agents for vascular inflammation
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Owens, Christopher D.
- Published
- 2012
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39. Risk factors for clinical failure after stent graft treatment for femoropopliteal occlusive disease
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Johnston, Paul C., Vartanian, Shant M., Runge, Sara J., Hiramoto, Jade S., Eichler, Charles M., Owens, Christopher D., Schneider, Darren B., and Conte, Michael S.
- Published
- 2012
- Full Text
- View/download PDF
40. An integrated biochemical prediction model of all-cause mortality in patients undergoing lower extremity bypass surgery for advanced peripheral artery disease
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Owens, Christopher D., Kim, Ji Min, Hevelone, Nathanael D., Gasper, Warren J., Belkin, Michael, Creager, Mark A., and Conte, Michael S.
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- 2012
- Full Text
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41. Genetic structure and domestication history of the grape
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Myles, Sean, Boyko, Adam R., Owens, Christopher L., Brown, Patrick J., Grassi, Fabrizio, Aradhya, Mallikarjuna K., Prins, Bernard, Reynolds, Andy, Chia, Jer-Ming, Ware, Doreen, Bustamante, Carlos D., Buckler, Edward S., and Schaal, Barbara A.
- Published
- 2011
42. Updated Clinical Evaluation of the CLUNGENE® Rapid COVID-19 Antibody Test
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Lamb, Christopher C., primary, Haddad, Fadi, additional, Owens, Christopher, additional, Lopez-Yunez, Alfredo, additional, Carroll, Marion, additional, and Moncrieffe, Jordan, additional
- Published
- 2021
- Full Text
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43. Proceedings of Thematic Sessions of the Twenty-Eighth Annual Meeting of the Society of Architectural Historians
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Massey, James C., Overby, Osmund, Dickey, John M., Reeves, F. Blair, DeLony, Eric N., Shepherd,, Raymond V., Downing, Antoinette F., Hotchkiss, Horace, House, Corbit-Sharp, House, Wilson-Warner, Gorr, Louis F., Schlereth, Thomas J., Richman, Irwin, Cotter, John L., Celoria, Miguel, Cosans, Elisabeth, Moran, Geoffrey P., Frank, Richard C., Fry, Bruce W., Kelso, William M., Graham, Roy Eugene, Carson, Cary, Milner, John D., Peterson, Charles E., Friary, Donald R., Moss,, Roger W., Stevens, John R., Candee, Richard M., Miller, Amelia F., Glassie,, Henry, Owens, Christopher, Heckscher, Morrison H., Garvan, Beatrice B., Garvin, James L., Mooz, R. Peter, Schless, Nancy Halverson, Wheaton, Rodd L., Crouch, Dora P., Garr, Daniel, Robinson, Willard B., Brown, Elizabeth M., Sears, Joan N., de Montêquin, François-Auguste, Reps, John, Pierson,, William H., Creese, Walter L., Floyd, Margaret Henderson, Tucci, Douglass S., Smith, Margaret S., MacDougall, Elisabeth B., Bruno, Claudia Lazzaro, Lowry, Bates, Morawinska, Agnieszka, Wiebenson, Dora L., Betts, Richard J., Senkevitch,, Anatole, White, Charles W., Evenson, Norma, and Stamm, Gunther
- Published
- 1975
- Full Text
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44. Abstracts of Papers Presented at the Twenty-Fifth Annual Meeting of the Society of Architectural Historians
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Brooks, H. Allen, Collins, George R., Michels, Eileen, Weisman, Winston R., Serenyi, Peter, Teitelman, Edward, Ross, Marion Dean, Walton, Elisabeth, Owens, Christopher, Hildebrand, Grant, Eaton, Leonard K., Reasoner, Barnabas, Peters, Richard C., Tobriner, Stephen, Gebhard, David, Thompson, Elisabeth K., Moore, Charles W., Hazlehurst, F. Hamilton, Darnall, Margaretta Jean, Swain, Richard O., MacDougall, Elisabeth, Freeman, John, King, Richard, Bony, Jean, Morris, Richard, Barnes,, Carl F., Hess, Gary, van der Meulen, Jan, Gebhard, David S., Glaeser, Ludwig, Lisle,, Forrest F., Church, Mary Kathleen, Beach, John, Scherer, Herbert, Kotas, J., Davidson, J. LeRoy, Begley, Wayne E., Asher, Frederick M., Myer, Prudence R., Huntington, John C., Spink, Walter M., Kline, Ruth Capelle, Craig, Robert M., Jernow, Stanley Kenneth, Pearson, Marjorie, Menocal, Narciso G., Wander, Steven H., Jansen, Virginia, and Malone, Carolyn
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- 1972
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45. The Role of Self-Efficacy and Injunctive Norms in Helping Older Adults Decide to Stay Home During the COVID-19 Pandemic
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Macy, Jonathan T., primary, Owens, Christopher, additional, Mullis, Kristina, additional, and Middlestadt, Susan E., additional
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- 2021
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46. Beliefs about Social Distancing During COVID-19 Stay-At-Home Orders: A Theory-Based Salient Belief Elicitation
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Owens, Christopher, primary, Struble, Nicole, additional, Currin, Joseph M, additional, Giano, Zachary, additional, and Hubach, Randolph D, additional
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- 2021
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47. Pharmacy Practice in High-Volume Community Settings: Barriers and Ethical Responsibilities
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Owens, Christopher T., primary and Baergen, Ralph, additional
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- 2021
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48. Nurturing Babies During the COVID-19 Lockdown: Resilience, Art and Creativity The Talent 25 Longitudinal (Sub-sample Study Executive Summary)
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Nijhof, Dewy, Ochieng, Rebecca, Daxini, Amar, Diawal-Bot, Diretnan, Owens, Christopher, and Ochieng, B.
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- 2020
49. Clinical outcome of fractures of the talar body
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Ebraheim, Nabil A., Patil, Vishwas, Owens, Christopher, and Kandimalla, Yugandhar
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- 2008
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50. Indigenous microbial surrogates in wastewater used to understand public health risk expressed in the Disability-Adjusted Life Year (DALY) metric
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Owens, Christopher EL, primary, Cox, Peter T, additional, Byleveld, Paul M, additional, Osborne, Nicholas J, additional, and Rahman, Md Bayzidur, additional
- Published
- 2021
- Full Text
- View/download PDF
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