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Description
Cardiovascular disease (CVD) is the number one cause of death in the United States and type 2 diabetes (T2D) and obesity lead to cardiovascular disease. Obese adults are more susceptible to CVD compared to their non-obese counterparts. Exercise training leads to large reductions in the risk of CVD and T2D.

Cardiovascular disease (CVD) is the number one cause of death in the United States and type 2 diabetes (T2D) and obesity lead to cardiovascular disease. Obese adults are more susceptible to CVD compared to their non-obese counterparts. Exercise training leads to large reductions in the risk of CVD and T2D. Recent evidence suggests high-intensity interval training (HIT) may yield similar or superior benefits in a shorter amount of time compared to traditional continuous exercise training. The purpose of this study was to compare the effects of HIT to continuous (CONT) exercise training for the improvement of endothelial function, glucose control, and visceral adipose tissue. Seventeen obese men (N=9) and women (N=8) were randomized to eight weeks of either HIT (N=9, age=34 years, BMI=37.6 kg/m2) or CONT (N=8, age=34 years, BMI=34.6 kg/m2) exercise 3 days/week for 8 weeks. Endothelial function was assessed via flow-mediated dilation (FMD), glucose control was assessed via continuous glucose monitoring (CGM), and visceral adipose tissue and body composition was measured with an iDXA. Incremental exercise testing was performed at baseline, 4 weeks, and 8 weeks. There were no changes in weight, fat mass, or visceral adipose tissue measured by the iDXA, but there was a significant reduction in body fat that did not differ by group (46±6.3 to 45.4±6.6%, P=0.025). HIT led to a significantly greater improvement in FMD compared to CONT exercise (HIT: 5.1 to 9.0%; CONT: 5.0 to 2.6%, P=0.006). Average 24-hour glucose was not improved over the whole group and there were no group x time interactions for CGM data (HIT: 103.9 to 98.2 mg/dl; CONT: 99.9 to 100.2 mg/dl, P>0.05). When statistical analysis included only the subjects who started with an average glucose at baseline > 100 mg/dl, there was a significant improvement in glucose control overall, but no group x time interaction (107.8 to 94.2 mg/dl, P=0.027). Eight weeks of HIT led to superior improvements in endothelial function and similar improvements in glucose control in obese subjects at risk for T2D and CVD. HIT was shown to have comparable or superior health benefits in this obese sample with a 36% lower total exercise time commitment.
ContributorsSawyer, Brandon J (Author) / Gaesser, Glenn A (Thesis advisor) / Shaibi, Gabriel (Committee member) / Lee, Chong (Committee member) / Swan, Pamela (Committee member) / Buman, Matthew (Committee member) / Arizona State University (Publisher)
Created2013
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Description
Purpose: The purpose of this study was to examine the acute effects of two novel intermittent exercise prescriptions on glucose regulation and ambulatory blood pressure. Methods: Ten subjects (5 men and 5 women, ages 31.5 ± 5.42 yr, height 170.38 ± 9.69 cm and weight 88.59 ± 18.91 kg) participated

Purpose: The purpose of this study was to examine the acute effects of two novel intermittent exercise prescriptions on glucose regulation and ambulatory blood pressure. Methods: Ten subjects (5 men and 5 women, ages 31.5 ± 5.42 yr, height 170.38 ± 9.69 cm and weight 88.59 ± 18.91 kg) participated in this four-treatment crossover trial. All subjects participated in four trials, each taking place over three days. On the evening of the first day, subjects were fitted with a continuous glucose monitor (CGM). On the second day, subjects were fitted with an ambulatory blood pressure monitor (ABP) and underwent one of the following four conditions in a randomized order: 1) 30-min: 30 minutes of continuous exercise at 60 - 70% VO2peak; 2) Mod 2-min: twenty-one 2-min bouts of walking at 3 mph performed once every 20 minutes; 3) HI 2-min: eight 2-min bouts of walking at maximal incline performed once every hour; 4) Control: a no exercise control condition. On the morning of the third day, the CGM and ABP devices were removed. All meals were standardized during the study visits. Linear mixed models were used to compare mean differences in glucose and blood pressure regulation between the four trials. Results: Glucose concentrations were significantly lower following the 30-min (91.1 ± 14.9 mg/dl), Mod 2-min (93.7 ± 19.8 mg/dl) and HI 2-min (96.1 ± 16.4 mg/dl) trials as compared to the Control (101.1 ± 20 mg/dl) (P < 0.001 for all three comparisons). The 30-min trial was superior to the Mod 2-min, which was superior to the HI 2-min trial in lowering blood glucose levels (P < 0.001 and P = 0.003 respectively). Only the 30-min trial was effective in lowering systolic ABP (124 ± 12 mmHg) as compared to the Control trial (127 ± 14 mmHg; P < 0.001) for up to 11 hours post exercise. Conclusion: Performing frequent short (i.e., 2 minutes) bouts of moderate or high intensity exercise may be a viable alternative to traditional continuous exercise in improving glucose regulation. However, 2-min bouts of exercise are not effective in reducing ambulatory blood pressure in healthy adults.
ContributorsBhammar, Dharini Mukeshkumar (Author) / Gaesser, Glenn A (Thesis advisor) / Shaibi, Gabriel (Committee member) / Buman, Matthew (Committee member) / Swan, Pamela (Committee member) / Lee, Chong (Committee member) / Arizona State University (Publisher)
Created2013
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Description
The effects of aging on muscular efficiency are controversial. Proponents for increased efficiency suggest that age-related changes in muscle enhance efficiency in senescence. Exercise study results are mixed due to varying modalities, ages, and efficiency calculations. The present study attempted to address oxygen uptake, caloric expenditure, walking economy, and gross
et

The effects of aging on muscular efficiency are controversial. Proponents for increased efficiency suggest that age-related changes in muscle enhance efficiency in senescence. Exercise study results are mixed due to varying modalities, ages, and efficiency calculations. The present study attempted to address oxygen uptake, caloric expenditure, walking economy, and gross
et cycling efficiency in young (18-59 years old) and older (60-81 years old) adults (N=444). Walking was performed at three miles per hour by 86 young (mean = 29.60, standard deviation (SD) = 10.50 years old) and 121 older adults (mean = 66.80, SD = 4.50 years old). Cycling at 50 watts (60-70 revolutions per minute) was performed by 116 young (mean= 29.00, SD= 10.00 years old) and 121 older adults (m = 67.10 SD = 4.50 years old). Steady-state sub-maximal gross
et oxygen uptake and caloric expenditures from each activity and rest were analyzed. Net walking economy was represented by net caloric expenditure (kilocalories/kilogram/min). Cycling measures included percent gross
et cycling efficiency (kilo-calorie derived). Linear regressions were used to assess each measure as a function of age. Differences in age group means were assessed using independent t-tests for each modality (alpha = 0.05). No significant differences in mean oxygen uptake nor walking economy were found between young and older walkers (p>0.05). Older adults performing cycle ergometry demonstrated lower gross
et oxygen uptakes and lower gross caloric expenditures (p< 0.05).
ContributorsFlores, Michelle (Author) / Gaesser, Glenn A (Committee member) / Campbell, Kathryn D (Committee member) / Angadi, Siddhartha S (Committee member) / Arizona State University (Publisher)
Created2014
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Description
The shape of glucose response and one hour (1-hr) glucose during an oral glucose tolerance test (OGTT) are emerging biomarkers for type 2 diabetes. The purpose of this study was two-fold: (1) to investigate the utility of these novel biomakers to differentiate type 2 diabetes risk in Latino youth, and

The shape of glucose response and one hour (1-hr) glucose during an oral glucose tolerance test (OGTT) are emerging biomarkers for type 2 diabetes. The purpose of this study was two-fold: (1) to investigate the utility of these novel biomakers to differentiate type 2 diabetes risk in Latino youth, and (2) to examine the genetic determinants in a Latino population.

Data from the ASU Arizona Insulin Registry (AIR) registry and the USC Study of Latino Adolescents at Risk for diabetes project were used to test the cross-sectional and prospective utility of novel biomarkers to identify youth at risk for type 2 diabetes. Pediatric and adult data from the ASU AIR registry were assessed to examine the association of single nucleotide polymorphisms (SNPs) with type 2 diabetes risk. Three KCNQ1 SNPs (rs151290; rs2237892; rs2237895) were examined as novel genetic variants for type 2 diabetes in Latinos.

Latino youth with a biphasic response in the AIR registry exhibited significantly better β-cell function (P < 0.05) compared to youth with a monophasic response. Additionally, Latino youth with a 1-hr glucose ≥155 mg/dL exhibited a significantly greater decline in β-cell function over 8 years compared with the <155 mg/dL group (β=-327.8±126.2, P = 0.01). Moreover, a 1-hr glucose ≥155 mg/dL was associated with a 2.5 times greater risk for developing prediabetes over time (P = 0.0001). 1-hr glucose was the most powerful predictor of prediabetes (area under the receiver operating characteristic curve=0.73) when compared to the traditional biomarkers including HbA1c (0.58), fasting (0.67), and 2-hr glucose (0.64). Two KCNQ1 SNPs (rs151290 and rs2237892) exhibited significant associations with type 2 diabetes risk factors. For the novel glycemic markers, 15 SNPs were associated with the glucose response curve, while 18 SNPs were associated with 1-hr glucose.

These data suggest that glucose response curve and 1-hr glucose during an OGTT independently differentiate type 2 diabetes risk among Latino youth. Furthermore, it was successful to replicate the association of type 2 diabetes risk with 2 KCNQ1 SNPs in a Latino population. Data suggest that novel glycemic biomarkers are influenced by genetic background in this high-risk population.
ContributorsKim, Joon Young (Author) / Shaibi, Gabriel Q (Thesis advisor) / Mandarino, Lawrence J (Committee member) / Coletta, Dawn K (Committee member) / De Filippis, Elena A (Committee member) / Arizona State University (Publisher)
Created2015
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Description
In adults, consuming a high-fat meal can induce endothelial dysfunction while exercise may mitigate postprandial endothelial dysfunction. Whether exercise is protective against postprandial endothelial dysfunction in obese youth is unknown. The purpose of this study was to determine if high-intensity interval exercise (HIIE) performed the evening prior to a high-fat

In adults, consuming a high-fat meal can induce endothelial dysfunction while exercise may mitigate postprandial endothelial dysfunction. Whether exercise is protective against postprandial endothelial dysfunction in obese youth is unknown. The purpose of this study was to determine if high-intensity interval exercise (HIIE) performed the evening prior to a high-fat meal protects against postprandial endothelial dysfunction in obese adolescent males. Fourteen obese adolescent males (BMI%tile=98.5±0.6; 14.3±1.0yrs) completed the study. After initial screening, participants arrived, fasted at 9:00 in the morning where brachial artery flow-mediated dilation (FMD) was measured using duplex ultrasound after 20min of supine rest (7.0±3.0%) and completed a maximal exercise test on a cycle ergometer (VO2peak=2.6±0.5 L/min). Participants were randomized and completed 2 conditions: a morning high-fat meal challenge with evening prior HIIE (EX+M) or a morning high-fat meal challenge without prior exercise (MO). The EX+M condition included a single HIIE session on a cycle ergometer (8 X 2min at ≥90%HRmax, with 2min active recovery between bouts, 42min total) which was performed at 17:00 the evening prior to the meal challenge. In both conditions, a mixed-meal was tailored to participants body weight consisting of 0.7g of fat/kg of body weight consumed (889±95kcal; 65% Fat, 30% CHO). FMD was measured at fasting (>10hrs) and subsequently measured at 2hr and 4hr after high-fat meal consumption. Exercise did not improve fasting FMD (7.5±3.0 vs. 7.4±2.8%, P=0.927; EX+M and MO, respectively). Despite consuming a high-fat meal, FMD was not reduced at 2hr (8.4±3.4 vs. 7.6±3.9%; EX+M and MO, respectively) or 4hr (8.8±3.9 vs. 8.6±4.0%; EX+M and MO, respectively) in either condition and no differences were observed between condition (p(condition*time)=0.928). These observations remained after adjusting for baseline artery diameter and shear rate. We observed that HIIE, the evening prior, had no effect on fasting or postprandial endothelial function when compared with a meal only condition. Future research should examine whether exercise training may be able to improve postprandial endothelial function rather than a single acute bout in obese youth.
ContributorsRyder, Justin Ross (Author) / Shaibi, Gabriel Q (Thesis advisor) / Gaesser, Glenn A (Committee member) / Vega-Lopez, Sonia (Committee member) / Crespo, Noe C (Committee member) / Katsanos, Christos (Committee member) / Arizona State University (Publisher)
Created2014
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Description
Among the general US population, cardiovascular disease (CVD) is the main cause of mortality for Mexican-Americans. CVD is less prevalent among Mexican-Americans than non-Hispanic Whites or African Americans. However, there is limited research regarding the factors associated with increased CVD risk among Mexican-Americans. Thus, this cross-sectional study was

Among the general US population, cardiovascular disease (CVD) is the main cause of mortality for Mexican-Americans. CVD is less prevalent among Mexican-Americans than non-Hispanic Whites or African Americans. However, there is limited research regarding the factors associated with increased CVD risk among Mexican-Americans. Thus, this cross-sectional study was conducted to evaluate the effects of non-biological factors (income, education, employment, acculturation) and diet on CVD risk factors in 75 Mexican-American adults (26 males, 49 females; age=37.6±9.3 y, BMI=28.9±5.3 kg/m2, systolic BP=117±11 mmHg, diastolic BP=73±9 mmHg, LDL cholesterol=114±32 mg/dL, HDL cholesterol=44±11 mg/dL, triglycerides=115±61 mg/dL, serum glucose=92±7 mg/dL). Aside from collecting anthropometric measurements, blood pressure, and measuring fasting blood lipids, glucose, and insulin, information about participants' socioeconomic status, income, employment, education, and acculturation were gathered using a survey. Diet data was collected using the Southwestern Food Frequency Questionnaire. Weight, BMI, and waist circumference were significantly greater for those with a monthly income of <$3000 than for those earning >$3000 (81±15 kg vs. 71±15 kg; 29.8±4.6 kg/m2 vs. 26.5±5.1 kg/m2; 98±12 cm vs. 89±14 cm; respectively) and with an education level of high school graduate or less than for those with some college (84±16 kg vs. 72±14 kg; 30.6±4.2 kg/m2 vs. 26.9±4.9 kg/m2; 100±11 cm vs. 91±13 cm; respectively). HDL-C was higher for those with a monthly income of >$3000 than those earning <$3000 (49±12 mg/dL vs. 41±10 mg/dL), those with some college education than those with high school or less (47±10 mg/dL vs. 37±9 mg/dL), and for those employed than those not employed (46±10 mg/dL vs. 40±12 mg/dL). There was no association between acculturation and CVD risk factors. Percent of energy consumed from fat was greater and percent of energy from carbohydrates was lower in those earning <$3000 monthly than those earning >$3000 (32±5% vs. 29±3%; 52±8% vs. 56±4%; respectively). Greater acculturation to the Anglo culture was negatively correlated with body fat percentage (r=-0.238, p=0.043) and serum glucose (r=-0.265, p=0.024). Overall, these results suggest that factors related to sociocultural and socioeconomic status may affect cardiometabolic disease risk in Mexican-Americans living in the Phoenix metropolitan area.
ContributorsFarr, Kristin Jennette (Author) / Vega-Lopez, Sonia (Thesis advisor) / Shaibi, Gabriel Q (Committee member) / Mayol-Kreiser, Sandra N (Committee member) / Arizona State University (Publisher)
Created2011
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Description
Mexican Americans have an increased risk for type 2 diabetes and premature cardiovascular disease (CVD). The association of hyperglycemia with traditional CVD risk factors in this population has been established, but there is limited data regarding other non-traditional CVD risk factors. Thus, this cross-sectional study was conducted to evaluate CVD

Mexican Americans have an increased risk for type 2 diabetes and premature cardiovascular disease (CVD). The association of hyperglycemia with traditional CVD risk factors in this population has been established, but there is limited data regarding other non-traditional CVD risk factors. Thus, this cross-sectional study was conducted to evaluate CVD risk among Mexican Americans by measuring concentrations of lipids, high-sensitivity C-reactive protein (hsCRP), and cholesterol in low-density-lipoprotein (LDL) and high-density-lipoprotein (HDL) subfractions. Eighty overweight/obese Mexican-American adults participating in the Maricopa Insulin Resistance Initiative were randomly selected from each of the following four groups (n = 20 per group): nomolipidemic
ormoglycemic controls (NC), dyslipidemic
ormoglycemic (DN), dyslipidemic/prediabetic (DPD) and dyslipidemic/diabetic (DD). Total cholesterol (TC) was 30% higher among DD than in NC participants (p<0.0001). The DPD group had 27% and 12% higher LDL-C concentrations than the NC and DN groups, respectively. Similarly, LDL-C was 29% and 13% higher in DD than in NC and DN participants (p=0.013). An increasing trend was observed in %10-year CVD risk with increasing degree of hyperglycemia (p<0.0001). The NC group had less cholesterol in sdLDL particles than dyslipidemic groups, regardless of glycemic status (p<0.0001). When hyperglycemia was part of the phenotype (DPD and DD), there was a greater proportion of total and HDL-C in sHDL particles in dyslipidemic individuals than in NC (p=0.023; p<0.0001; respectively). Percent 10-year CVD risk was positively correlated with triglyceride (TG) (r=0.384, p<0.0001), TC (r=0.340, p<0.05), cholesterol in sdLDL(r=0.247; p<0.05), and TC to HDL-C ratio (r=0.404, p<0.0001), and negatively correlated with HDL-C in intermediate and large HDL(r=-0.38, p=0.001; r=0.34, p=0.002, respectively). The TC/HDL-C was positively correlated with cholesterol in sdLDL particles (r=0.698, p<0.0001) and HDL-C in sHDL particles (r=0.602, p<0.0001), and negatively correlated with cholesterol in small (r=-0.35, p=0.002), intermediate (r=-0.91, p<0.0001) and large (r=-0.84, p<0.0001) HDL particles, and HDL-C in the large HDL particles (r=-0.562, p<0.0001). No significant association was found between %10-year CVD risk and hsCRP. Collectively, these results corroborate that dyslipidemic Mexican-American adults have higher CVD risk than normolipidemic individuals. Hyperglycemia may further affect CVD risk by modulating cholesterol in LDL and HDL subfractions.
ContributorsNeupane, Srijana (Author) / Vega-Lopez, Sonia (Thesis advisor) / Shaibi, Gabriel Q (Committee member) / Johnston, Carol S (Committee member) / Arizona State University (Publisher)
Created2011
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Description
Heart failure is a major worldwide health concern and is the leading cause of hospitalization among elderly Americans. Approximately 50% of those diagnosed with heart failure have heart failure with preserved ejection fraction (HFPEF). HFPEF presents a therapeutic dilemma because pharmacological strategies that are effective for the treatment of heart

Heart failure is a major worldwide health concern and is the leading cause of hospitalization among elderly Americans. Approximately 50% of those diagnosed with heart failure have heart failure with preserved ejection fraction (HFPEF). HFPEF presents a therapeutic dilemma because pharmacological strategies that are effective for the treatment of heart failure and reduced ejection fraction have failed to show benefit in HFPEF. Long term moderate intensity exercise programs have been shown to improve diastolic function in patients HFPEF. High intensity interval training (HIIT) has been shown to improve diastolic function in patients with heart failure and reduced ejection fraction. However, the effects of high intensity interval training in patients with HFPEF are unknown. Fourteen patients with HFPEF were randomized to either: (1) a novel program of high-intensity aerobic interval training (n = 8), or (2) a commonly prescribed program of moderate-intensity (MOD) aerobic exercise training (n = 6). Before and after four weeks of exercise training, patients underwent a treadmill graded exercise test for the determination of peak oxygen uptake (VO2peak), a brachial artery reactivity test for assessment of endothelium-dependent flow-mediated dilation (BAFMD), aortic pulse wave velocity assessment as an index of vascular stiffness and two-dimensional echocardiography for assessment of left ventricular diastolic and systolic function. I hypothesized that (1) high-intensity aerobic interval training would result in superior improvements in FMD, aortic pulse wave velocity, VO2peak, diastolic function and, (2) changes in these parameters would be correlated with changes in VO2peak. The principal findings of the study were that a one month long high intensity interval training program resulted in significant improvements in diastolic function as measured by two-dimensional echocardiography [pre diastolic dysfunction (DD) grade - 2.13 + 0.4 vs. post DD grade - 1.25 + 0.7, p = 0.03]. The left atrial volume index was reduced in the HIIT group compared to MOD ( - 4.4 + 6.2 ml/m2 vs. 5.8 + 10.7 ml/m2, p = 0.02). Early mitral flow (E) improved in the HIIT group (pre - 0.93 + 0.2 m/s vs. post - 0.78 + 0.3 m/s, p = 0.03). A significant inverse correlation was observed between change in BAFMD and change in diastolic dysfunction grade (r = - 0.585, p = 0.028) when all the data were pooled. HIIT appears to be a time-efficient and safe strategy for improving diastolic function in patients with heart failure and preserved ejection fraction. These data may have implications for cardiovascular risk reduction in this population.
ContributorsAngadi, Siddhartha (Author) / Gaesser, Glenn A (Thesis advisor) / Mookadam, Farouk (Committee member) / Swan, Pamela (Committee member) / Vega-Lopez, Sonia (Committee member) / Lee, Chong (Committee member) / Arizona State University (Publisher)
Created2012
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Description
ABSTRACT Despite significant advancements in drug therapy, cardiovascular disease (CVD) is still the leading cause of death in the United States. Given this, research has begun to seek out alternative approaches to reduce CVD risk. One of these alternative approaches is Vitamin D supplementation. Current research has shown a link

ABSTRACT Despite significant advancements in drug therapy, cardiovascular disease (CVD) is still the leading cause of death in the United States. Given this, research has begun to seek out alternative approaches to reduce CVD risk. One of these alternative approaches is Vitamin D supplementation. Current research has shown a link between Vitamin D status and CVD risk in both healthy and diseased populations. Among the possible mechanisms is a positive effect of Vitamin D on vascular endothelial function, which can be measured with noninvasive techniques such as flow-mediated dilation (FMD) of conduit vessels using high-resolution ultrasound. This dissertation is comprised of two studies. The first examines whether Vitamin D supplementation can improve FMD in older adults within a time period (two weeks) associated with peak increases in plasma Vitamin D concentrations after a single-dose supplementation. The second examines the effect of Vitamin D supplementation in people with Rheumatoid Arthritis (RA). The reason for looking at an RA population is that CVD is the leading cause of early mortality in people with RA. In the first study 29 Post-Menopausal Women received either 100,000 IU of Vitamin D3 or a Placebo. Their FMD was measured at baseline and 2 weeks after supplementation. After 2 weeks there was a significant increase in FMD in the Vitamin D group (6.19 + 4.87 % to 10.69 + 5.18 %) as compared to the Placebo group (p=.03). In the second study, 11 older adults with RA were given 100,000 IU of Vitamin D or a Placebo. At baseline and one month later their FMD was examined as well as plasma concentrations of Vitamin D and tumor necrosis factor-alpha; (TNF-alpha;). They also filled out a Quality of Life Questionnaire and underwent a submaximal exercise test on the treadmill for estimation of maximum oxygen uptake (VO2max). There was no significant change in FMD in Vitamin D group as compared to the Placebo group (p=.721). Additionally, there was no significant improvement in either plasma Vitamin D or TNF-alpha; in the Vitamin D group. There was however a significant improvement in predicted VO2max from the submaximal exercise test in the group receiving Vitamin D (p=.003). The results of these studies suggest that a single 100,000 IU dose of Vitamin D can enhance FMD within two week in older adults, but that a similar dose may not be sufficient to increase FMD or plasma Vitamin D levels in older adults with RA. A more aggressive supplementation regimen may be required in this patient population.
ContributorsRyan, Dana Meredith (Author) / Gaesser, Glenn A (Thesis advisor) / Rizzo, Warren (Committee member) / Martin, Keith (Committee member) / Larkey, Linda (Committee member) / Chisum, Jack (Committee member) / Arizona State University (Publisher)
Created2012