Tyler Leonard - Academia.edu (original) (raw)
Papers by Tyler Leonard
PurposeTo investigate the long-term prognostic value of coronary CT angiography (cCTA)-derived pl... more PurposeTo investigate the long-term prognostic value of coronary CT angiography (cCTA)-derived plaque information on major adverse cardiac events (MACE) in patients with and without diabetes mellitus. Methods64 patients with diabetes (63.3±10.1 years, 66% male) and suspected coronary artery disease (CAD) who underwent cCTA were matched with 297 patients without diabetes according to age, sex, cardiovascular risk factors, statin and antithrombotic therapy. Major adverse cardiac events (MACE) were recorded. cCTA-derived risk scores and plaque measures were assessed. The discriminatory power to identify MACE was evaluated using multivariable regression analysis and concordance indices (CIs).ResultsAfter a median follow-up of 5.4 years, MACE occurred in 31 patients (8.6%). In patients with diabetes, cCTA risk scores and plaque measures were significantly higher compared to non-diabetic patients (all p<0.05). The following plaque measures were predictors of MACE using multivariable Co...
Journal of Thoracic Imaging, 2021
Background: Symptoms of chest pain in diabetic patients can vary substantially. To date, informat... more Background: Symptoms of chest pain in diabetic patients can vary substantially. To date, information is sparse regarding the incremental value of coronary computed tomographic angiography (CCTA) above coronary artery calcium score (CACS) and conventional risk factors in diabetic patients with no symptoms or non-typical chest pain. Methods: From the prospective CONFIRM registry of 35,281 patients with CCTA, 1,295 diabetic patients with no symptoms or nontypical chest pain (atypical or non-cardiac chest pain) were identified. Obstructive coronary artery disease (CAD) defined as coronary stenosis ≥50% and number of obstructive vessels were evaluated by CCTA. Patients were followed for a primary composite endpoint of major adverse cardiovascular events (MACE) that consisted of all-cause death, non-fatal myocardial infarction and late target vessel revascularization (≥90 days). The incremental value of CCTA for prognostication, discrimination by C-statistic, and reclassification by integrated discrimination improvement (IDI) were assessed. Results: Mean age was 59.8±9.9 years and 55% were male. After a mean follow-up of 3.0±1.7 years, 103 (8.8%) diabetic patients experienced MACE (45 deaths, 15 non-fatal myocardial infarction, and 55 late revascularization). After adjustment for CAD risk factors and log CACS, obstructive CAD (HR 3.61, 95% CI: 1.34-3.33) and increasing number of obstructive vessels (HR 1.77, 95% CI: 1.44-2.15, P trend < 0.001) were significantly associated with MACE. Beyond the baseline model including age, gender and log CACS (C-statistic 0.77), CCTA improved discrimination (C-statistic 0.78 and 0.80 respectively) and risk reclassification (IDI 0.01 and 0.05 respectively) by obstructive CAD and number of obstructive vessels, P<0.05 for all. Conclusions: In diabetic patients with no symptoms or non-typical chest pain, CCTA-derived surrogates of CAD severity provide incremental prognostic value beyond CACS for prediction of MACE.
It discloses a high-quality single crystal silicon carbide wafer having a spiral 1c potential (sc... more It discloses a high-quality single crystal silicon carbide wafer having a spiral 1c potential (screw dislocation) densities of about three inches or more in diameter and less than about 2000 cm
Hematopoietic stem and progenitor cells (HSPCs) are an ideal platform for studying extrinsic cues... more Hematopoietic stem and progenitor cells (HSPCs) are an ideal platform for studying extrinsic cues on stem cell behavior and for developing material systems than can act as stem cell niche analogs. Regulation of HSPC fate decisions (quiescence, self-renewal, differentiation) is thought to be partially regulated via extrinsic (cell-cell, cell-matrix, soluble regulator) cues presented by distinct microenvironments, termed niches, in the bone marrow. Here we describe development of biomaterial systems that enable independent assessment of the effects of cell-matrix and cell-cell cues on HSPC biophysical parameters and early fate decisions (proliferation, viability, differentiation). For these experiments we isolated HSPCs as Lin-cKit+Sca1+ (LSK) cells from murine tibial and femoral bone marrow via flow cytometry. We created type I collagen coated (100μg/ml), two-dimensional polyacrylamide (PA) gels and three-dimensional type I collagen hydrogels (1.45, 2.9 mg/ml) to assess the effect of...
Laser assisted dry etching is a materials processing technique capable of producing highly anisot... more Laser assisted dry etching is a materials processing technique capable of producing highly anisotropic etch features with precise etch depth control and little contamination. The technique is simple: laser radiation is combined with a gaseous chemical etchant to remove material in pattern selected regions. The advantages of laser etching include the removal of etch products with photonic energy instead of
PurposeTo investigate the long-term prognostic value of coronary CT angiography (cCTA)-derived pl... more PurposeTo investigate the long-term prognostic value of coronary CT angiography (cCTA)-derived plaque information on major adverse cardiac events (MACE) in patients with and without diabetes mellitus. Methods64 patients with diabetes (63.3±10.1 years, 66% male) and suspected coronary artery disease (CAD) who underwent cCTA were matched with 297 patients without diabetes according to age, sex, cardiovascular risk factors, statin and antithrombotic therapy. Major adverse cardiac events (MACE) were recorded. cCTA-derived risk scores and plaque measures were assessed. The discriminatory power to identify MACE was evaluated using multivariable regression analysis and concordance indices (CIs).ResultsAfter a median follow-up of 5.4 years, MACE occurred in 31 patients (8.6%). In patients with diabetes, cCTA risk scores and plaque measures were significantly higher compared to non-diabetic patients (all p<0.05). The following plaque measures were predictors of MACE using multivariable Co...
Journal of Thoracic Imaging, 2021
Background: Symptoms of chest pain in diabetic patients can vary substantially. To date, informat... more Background: Symptoms of chest pain in diabetic patients can vary substantially. To date, information is sparse regarding the incremental value of coronary computed tomographic angiography (CCTA) above coronary artery calcium score (CACS) and conventional risk factors in diabetic patients with no symptoms or non-typical chest pain. Methods: From the prospective CONFIRM registry of 35,281 patients with CCTA, 1,295 diabetic patients with no symptoms or nontypical chest pain (atypical or non-cardiac chest pain) were identified. Obstructive coronary artery disease (CAD) defined as coronary stenosis ≥50% and number of obstructive vessels were evaluated by CCTA. Patients were followed for a primary composite endpoint of major adverse cardiovascular events (MACE) that consisted of all-cause death, non-fatal myocardial infarction and late target vessel revascularization (≥90 days). The incremental value of CCTA for prognostication, discrimination by C-statistic, and reclassification by integrated discrimination improvement (IDI) were assessed. Results: Mean age was 59.8±9.9 years and 55% were male. After a mean follow-up of 3.0±1.7 years, 103 (8.8%) diabetic patients experienced MACE (45 deaths, 15 non-fatal myocardial infarction, and 55 late revascularization). After adjustment for CAD risk factors and log CACS, obstructive CAD (HR 3.61, 95% CI: 1.34-3.33) and increasing number of obstructive vessels (HR 1.77, 95% CI: 1.44-2.15, P trend < 0.001) were significantly associated with MACE. Beyond the baseline model including age, gender and log CACS (C-statistic 0.77), CCTA improved discrimination (C-statistic 0.78 and 0.80 respectively) and risk reclassification (IDI 0.01 and 0.05 respectively) by obstructive CAD and number of obstructive vessels, P<0.05 for all. Conclusions: In diabetic patients with no symptoms or non-typical chest pain, CCTA-derived surrogates of CAD severity provide incremental prognostic value beyond CACS for prediction of MACE.
It discloses a high-quality single crystal silicon carbide wafer having a spiral 1c potential (sc... more It discloses a high-quality single crystal silicon carbide wafer having a spiral 1c potential (screw dislocation) densities of about three inches or more in diameter and less than about 2000 cm
Hematopoietic stem and progenitor cells (HSPCs) are an ideal platform for studying extrinsic cues... more Hematopoietic stem and progenitor cells (HSPCs) are an ideal platform for studying extrinsic cues on stem cell behavior and for developing material systems than can act as stem cell niche analogs. Regulation of HSPC fate decisions (quiescence, self-renewal, differentiation) is thought to be partially regulated via extrinsic (cell-cell, cell-matrix, soluble regulator) cues presented by distinct microenvironments, termed niches, in the bone marrow. Here we describe development of biomaterial systems that enable independent assessment of the effects of cell-matrix and cell-cell cues on HSPC biophysical parameters and early fate decisions (proliferation, viability, differentiation). For these experiments we isolated HSPCs as Lin-cKit+Sca1+ (LSK) cells from murine tibial and femoral bone marrow via flow cytometry. We created type I collagen coated (100μg/ml), two-dimensional polyacrylamide (PA) gels and three-dimensional type I collagen hydrogels (1.45, 2.9 mg/ml) to assess the effect of...
Laser assisted dry etching is a materials processing technique capable of producing highly anisot... more Laser assisted dry etching is a materials processing technique capable of producing highly anisotropic etch features with precise etch depth control and little contamination. The technique is simple: laser radiation is combined with a gaseous chemical etchant to remove material in pattern selected regions. The advantages of laser etching include the removal of etch products with photonic energy instead of