Publications by authors named "Lawrence Ko"

Purpose: To quantify daily bladder size and position variations during bladder cancer radiotherapy.

Methods And Materials: Ten bladder cancer patients underwent daily cone beam CT (CBCT) imaging of the bladder during radiotherapy. Bladder and planning target volumes (bladder/PTV) from CBCT and planning CT scans were compared with respect to bladder center-of-mass shifts in the x (lateral), y (anterior-posterior), and z (superior-inferior) coordinates, bladder/PTV size, bladder/PTV margin positions, overlapping areas, and mutually exclusive regions.

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Purpose: Nanotechnology is an emerging field with significant translational potential in medicine. In this study, we applied gold nanoparticles (GNP) to enhance radiation sensitivity and growth inhibition in radiation-resistant human prostate cancer cells.

Methods: Gold nanoparticles (GNPs) were synthesized using HAuCl4 as the gold particle source and NaBH4 as the reductant.

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Objectives: We evaluated the effect of the St Jude Medical sutureless anastomotic connector on endothelium-dependent and -independent saphenous vein graft relaxation, as well as on clinical outcomes and graft patency in patients.

Methods: Human saphenous vein grafts were assigned to control or connector groups (loaded for 1 or 5 minutes; n = 18). Isometric dose-response curves to endothelium-dependent and -independent (sodium nitroprusside) vasodilators were constructed in saphenous vein grafts precontracted with phenylephrine.

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Objectives: We have previously demonstrated an importance of endothelin-1 in diabetic patients undergoing bypass surgery. Recent evidence suggests that cardiomyocytes might also produce endothelin-1, which might directly impair myocyte contractility by increasing intracellular calcium levels. Because hyperglycemia is a potent stimulus of endothelin-1 production, we hypothesized that increased production, action, or both of endothelin-1 might be a mediator of direct cardiomyocyte injury in diabetes.

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Objectives: Evidence has accrued to suggest that diabetic patients face an increased risk of ischemic events and low output syndrome and might mount an inordinate response to ischemia and reperfusion. Because hyperglycemia is a potent stimulus for endothelin-1 production, we hypothesized that increased production, action, or both of endothelin-1 in diabetes might represent an important mediator of endothelial dysfunction in patients with that disease. To this aim, we compared the effects of cardioplegic arrest and reperfusion on coronary sinus effluent endothelin-1 levels and atrial arteriolar vascular responses in diabetic and case-matched nondiabetic patients undergoing coronary artery bypass grafting.

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Background: Angiotensin II and endothelin-1 are potent endothelium-derived contracting factors. The effects of acute endothelin antagonism on endothelial function in saphenous vein from patients treated with and without angiotensin-converting enzyme inhibitors were compared.

Methods: Vascular segments of saphenous vein were obtained perioperatively from 14 patients on angiotensin-converting enzyme inhibitors and 29 controls.

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Protective effects of L-arginine were evaluated in a human ventricular heart cell model of low-volume anoxia and reoxygenation independent of alternate cell types. Cell cultures were subjected to 90 min of low-volume anoxia and 30 min of reoxygenation. L-Arginine (0-5.

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