1
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O'Connor AE, Hatzenbiler DM, Flom LT, Bobadilla AC, Bruns DR, Schmitt EE. Physiological and Morphometric Differences in Resident Moderate-Altitude vs. Sea-Level Mice. Aerosp Med Hum Perform 2023; 94:887-893. [PMID: 38176033 PMCID: PMC10826331 DOI: 10.3357/amhp.6234.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2024]
Abstract
INTRODUCTION: High-altitude [>2400 m (7874 ft)] acclimatization has been well studied with physiological adaptations like reductions in body weight and exercise capacity. However, despite the significance of moderate altitude [MA, 1524-2438 m (5000-8000 ft)], acclimatization at this elevation is not well described. We aimed to investigate differences in mice reared at MA compared to sea level (SL). We hypothesized that MA mice would be smaller and leaner and voluntarily run less than SL mice.METHODS: C57BL/6 mice reared for at least three generations in Laramie, WY [2194 m (7198 ft), MA], were compared to C57BL/6J mice from Bar Harbor, ME [20 m (66 ft), SL]. We quantified body composition and exercise outputs as well as cardiopulmonary morphometrics. Subsets of MA and SL mice were analyzed to determine differences in neuronal activation after exercise.RESULTS: When body weight was normalized to tibia length, SL animals weighed 1.30 g ⋅ mm-1 while MA mice weighed 1.13 g · mm-1. Total fat % and trunk fat % were higher in MA mice with values of 41% and 39%, respectively, compared to SL mice with values of 28% and 26%, respectively. However, no differences were noted in leg fat %. MA animals had higher heart mass (119 mg) and lower lung mass (160 mg) compared to SL mice heart mass (100 mg) and lung mass (177 mg). MA mice engaged in about 40% less voluntary wheel-running activity than SL animals.DISCUSSION: Physiological differences are apparent between MA and SL mice, prompting a need to further understand larger scale implications of residence at moderate altitude.O'Connor AE, Hatzenbiler DM, Flom LT, Bobadilla A-C, Bruns DR, Schmitt EE. Physiological and morphometric differences in resident moderate-altitude vs. sea-level mice. Aerosp Med Hum Perform. 2023; 94(12):887-893.
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2
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Yusifov A, Borders MO, DeHoff MA, Polson SM, Schmitt EE, Bruns DR. Juvenile physical activity protects against isoproterenol-induced cardiac dysfunction later in life. J Appl Physiol (1985) 2023; 135:572-583. [PMID: 37439235 PMCID: PMC10538985 DOI: 10.1152/japplphysiol.00010.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Revised: 07/10/2023] [Accepted: 07/10/2023] [Indexed: 07/14/2023] Open
Abstract
Cardiovascular disease is an enormous public health problem, particularly in older populations. Exercise is the most potent cardioprotective intervention identified to date, with exercise in the juvenile period potentially imparting greater protection, given the plasticity of the developing heart. To test the hypothesis that voluntary wheel running early in life would be cardioprotective later in life when risk for disease is high, we provided male and female juvenile (3 wk old) mice access to a running wheel for 2 wk. Mice then returned to a home cage to age to adulthood (4-6 mo) before exposure to isoproterenol (ISO) to induce cardiac stress. Cardiac function and remodeling were compared with sedentary control mice, sedentary mice exposed to ISO, and mice that exercised in adulthood immediately before ISO. Early in life activity protected against ISO-induced stress as evidenced by attenuated cardiac mass, myocyte size, and fibrosis compared with sedentary mice exposed to ISO. ISO-induced changes in cardiac function were ameliorated in male mice that engaged in wheel running, with ejection fraction and fractional shortening reversed to control values. Adrenergic receptor expression was downregulated in juvenile male runners. This suppression persisted in adulthood following ISO, providing a putative mechanism by which exercise in the young male heart provides resilience to cardiac stress later in life. Together, we show that activity early in life induces persistent cardiac changes that attenuate ISO-induced stress in adulthood. Identification of the mechanisms by which early in life exercise is protective will yield valuable insights into how exercise is medicine across the life course.NEW & NOTEWORTHY Voluntary wheel running activity early in life induces persistent changes in the heart that attenuate isoproterenol-induced hypertrophy and fibrosis in adulthood. Though the mechanisms of this protection remain incompletely understood, activity-induced downregulation of adrenergic receptor expression early in life may contribute to later protection against adrenergic stress. Together these data suggest that efforts to maintain an active lifestyle early in life may have long-lasting cardioprotective benefits.
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Affiliation(s)
- Aykhan Yusifov
- Division of Kinesiology and Health, University of Wyoming, Laramie, Wyoming, United States
| | - Megan O Borders
- Division of Kinesiology and Health, University of Wyoming, Laramie, Wyoming, United States
| | - MacKenzie A DeHoff
- Division of Kinesiology and Health, University of Wyoming, Laramie, Wyoming, United States
| | - Sydney M Polson
- Division of Kinesiology and Health, University of Wyoming, Laramie, Wyoming, United States
| | - Emily E Schmitt
- Division of Kinesiology and Health, University of Wyoming, Laramie, Wyoming, United States
- WWAMI Medical Education Program, University of Wyoming, Laramie, Wyoming, United States
| | - Danielle R Bruns
- Division of Kinesiology and Health, University of Wyoming, Laramie, Wyoming, United States
- WWAMI Medical Education Program, University of Wyoming, Laramie, Wyoming, United States
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3
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Herzl E, Schmitt EE, Shearrer G, Keith JF. The Effects of a Western Diet vs. a High-Fiber Unprocessed Diet on Health Outcomes in Mice Offspring. Nutrients 2023; 15:2858. [PMID: 37447184 DOI: 10.3390/nu15132858] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Revised: 06/16/2023] [Accepted: 06/21/2023] [Indexed: 07/15/2023] Open
Abstract
Diet influences critical periods of growth, including gestation and early development. We hypothesized that a maternal/early life diet reflecting unprocessed dietary components would positively affect offspring metabolic and anthropometric parameters. Using 9 C57BL-6 dams, we simulated exposure to a Western diet, a high-fiber unprocessed diet (HFUD), or a control diet. The dams consumed their respective diets (Western [n = 3], HFUD [n = 3], and control [n = 3]) through 3 weeks of pregnancy and 3 weeks of weaning; their offspring consumed the diet of their mother for 4.5 weeks post weaning. Measurements included dual X-ray absorptiometry (DEXA) scans, feed consumption, body weight, blood glucose, and insulin and glycated hemoglobin (HbA1c) in the offspring. Statistical analyses included one-way ANOVA with Tukey's post hoc analysis. The offspring DEXA measures at 5 and 7.5 weeks post parturition revealed higher lean body mass development in the HFUD and control diet offspring compared to the Western diet offspring. An analysis indicated that blood glucose (p = 0.001) and HbA1c concentrations (p = 0.002) were lower among the HFUD offspring compared to the Western and control offspring. The results demonstrate that diet during gestation and early life consistent with traditional diet patterns may influence hyperglycemia and adiposity in offspring.
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Affiliation(s)
- Elizabeth Herzl
- Department of Family & Consumer Sciences, University of Wyoming, Laramie, WY 82071, USA
| | - Emily E Schmitt
- Division of Kinesiology & Health, University of Wyoming, Laramie, WY 82071, USA
- WWAMI Medical Education, University of Wyoming, Laramie, WY 82071, USA
| | - Grace Shearrer
- Department of Family & Consumer Sciences, University of Wyoming, Laramie, WY 82071, USA
- WWAMI Medical Education, University of Wyoming, Laramie, WY 82071, USA
| | - Jill F Keith
- Department of Family & Consumer Sciences, University of Wyoming, Laramie, WY 82071, USA
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4
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Yusifova M, Yusifov A, Polson SM, Todd WD, Schmitt EE, Bruns DR. Voluntary Wheel Running Exercise Does Not Attenuate Circadian and Cardiac Dysfunction Caused by Conditional Deletion of Bmal1. J Biol Rhythms 2023:7487304231152398. [PMID: 36802963 DOI: 10.1177/07487304231152398] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Abstract
Circadian misalignment occurs with age, jet lag, and shift work, leading to maladaptive health outcomes including cardiovascular diseases. Despite the strong link between circadian disruption and heart disease, the cardiac circadian clock is poorly understood, prohibiting identification of therapies to restore the broken clock. Exercise is the most cardioprotective intervention identified to date and has been suggested to reset the circadian clock in other peripheral tissues. Here, we tested the hypothesis that conditional deletion of core circadian gene Bmal1 would disrupt cardiac circadian rhythm and function and that this disruption would be ameliorated by exercise. To test this hypothesis, we generated a transgenic mouse with spatial and temporal deletion of Bmal1 only in adult cardiac myocytes (Bmal1 cardiac knockout [cKO]). Bmal1 cKO mice demonstrated cardiac hypertrophy and fibrosis concomitant with impaired systolic function. This pathological cardiac remodeling was not rescued by wheel running. While the molecular mechanisms responsible for the profound cardiac remodeling are unclear, it does not appear to involve activation of the mammalian target of rapamycin (mTOR) signaling or changes in metabolic gene expression. Interestingly, cardiac deletion of Bmal1 disrupted systemic rhythms as evidenced by changes in the onset and phasing of activity in relationship to the light/dark cycle and by decreased periodogram power as measured by core temperature, suggesting cardiac clocks can regulate systemic circadian output. Together, we suggest a critical role for cardiac Bmal1 in regulating both cardiac and systemic circadian rhythm and function. Ongoing experiments will determine how disruption of the circadian clock causes cardiac remodeling in an effort to identify therapeutics to attenuate the maladaptive outcomes of a broken cardiac circadian clock.
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Affiliation(s)
| | - Aykhan Yusifov
- Kinesiology & Health, University of Wyoming, Laramie, Wyoming
| | - Sydney M Polson
- Kinesiology & Health, University of Wyoming, Laramie, Wyoming
| | - William D Todd
- Department of Zoology and Physiology, University of Wyoming, Laramie, Wyoming
| | - Emily E Schmitt
- Kinesiology & Health, University of Wyoming, Laramie, Wyoming.,Wyoming WWAMI Medical Education, University of Wyoming, Laramie, Wyoming
| | - Danielle R Bruns
- Kinesiology & Health, University of Wyoming, Laramie, Wyoming.,Department of Zoology and Physiology, University of Wyoming, Laramie, Wyoming.,Wyoming WWAMI Medical Education, University of Wyoming, Laramie, Wyoming
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5
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Fullerton ZS, McNair BD, Marcello NA, Schmitt EE, Bruns DR. Exposure to High Altitude Promotes Loss of Muscle Mass That Is Not Rescued by Metformin. High Alt Med Biol 2022; 23:215-222. [PMID: 35653735 PMCID: PMC9526469 DOI: 10.1089/ham.2022.0015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 04/22/2022] [Indexed: 11/12/2022] Open
Abstract
Fullerton, Zackery S., Benjamin D. McNair, Nicholas A. Marcello, Emily E. Schmitt, and Danielle R. Bruns. Exposure to high altitude promotes loss of muscle mass that is not rescued by metformin. High Alt Med Biol. 23:215-222, 2022. Background: Exposure to high altitude (HA) causes muscle atrophy. Few therapeutic interventions attenuate muscle atrophy; however, the diabetic drug, metformin (Met), has been suggested as a potential therapeutic to preserve muscle mass with aging and obesity-related atrophy. The purpose of the present study was to test the hypothesis that HA would induce muscle atrophy that could be attenuated by Met. Methods: C57Bl6 male and female mice were exposed to simulated HA (∼5,200 m) for 4 weeks, while control (Con) mice remained at resident altitude (∼2,180 m). Met was administered in drinking water at 200 mg/(kg·day). We assessed muscle mass, myocyte cell size, muscle and body composition, and expression of molecular mediators of atrophy. Results: Mice exposed to HA were leaner and had a smaller hind limb complex (HLC) mass than Con mice. Loss of HLC mass and myocyte size were not attenuated by Met. Molecular markers for muscle atrophy were activated at HA in a sex-dependent manner. While the atrophic regulator, atrogin, was unchanged at HA or with Met, myostatin expression was upregulated at HA. In female mice, Met further stimulated myostatin expression. Conclusions: Although HA exposure resulted in loss of muscle mass, particularly in male mice, Met did not attenuate muscle atrophy. Identification of other interventions to preserve muscle mass during ascent to HA is warranted.
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Affiliation(s)
- Zackery S. Fullerton
- Division of Kinesiology and Health, University of Wyoming, Laramie, Wyoming, USA
| | - Benjamin D. McNair
- Division of Kinesiology and Health, University of Wyoming, Laramie, Wyoming, USA
| | - Nicholas A. Marcello
- Division of Kinesiology and Health, University of Wyoming, Laramie, Wyoming, USA
| | - Emily E. Schmitt
- Division of Kinesiology and Health, University of Wyoming, Laramie, Wyoming, USA
- Wyoming WWAMI Medical Education, Laramie, Wyoming, USA
| | - Danielle R. Bruns
- Division of Kinesiology and Health, University of Wyoming, Laramie, Wyoming, USA
- Wyoming WWAMI Medical Education, Laramie, Wyoming, USA
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6
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Abstract
Aging induces physiological and molecular changes in the heart that increase the risk for heart disease. Several of these changes are targetable by exercise. We hypothesize that the mechanisms by which exercise improves cardiac function in the aged heart differ from those in the young exercised heart.
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Affiliation(s)
| | - Benjamin D McNair
- Division of Kinesiology & Health, University of Wyoming, Laramie, WY
| | - Sydney M Polson
- Division of Kinesiology & Health, University of Wyoming, Laramie, WY
| | - Ross F Cook
- Division of Kinesiology & Health, University of Wyoming, Laramie, WY
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7
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Yusifov A, Chhatre VE, Koplin EK, Wilson CE, Schmitt EE, Woulfe KC, Bruns DR. Transcriptomic analysis of cardiac gene expression across the life course in male and female mice. Physiol Rep 2021; 9:e14940. [PMID: 34245129 PMCID: PMC8271347 DOI: 10.14814/phy2.14940] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 05/22/2021] [Accepted: 05/29/2021] [Indexed: 12/13/2022] Open
Abstract
Risk for heart disease increases with advanced age and differs between sexes, with females generally protected from heart disease until menopause. Despite these epidemiological observations, the molecular mechanisms that underlie sex‐specific differences in cardiac function have not been fully described. We used high throughput transcriptomics in juvenile (5 weeks), adult (4–6 months), and aged (18 months) male and female mice to understand how cardiac gene expression changes across the life course and by sex. While male gene expression profiles differed between juvenile‐adult and juvenile‐aged (254 and 518 genes, respectively), we found no significant differences in adult‐aged gene expression. Females had distinct gene expression changes across the life course with 1835 genes in juvenile‐adult and 1328 in adult‐aged. Analysis of differentially expressed genes (DEGs) suggests that juvenile to adulthood genes were clustered in cell cycle and development‐related pathways in contrast to adulthood‐aged which were characterized by immune‐and inflammation‐related pathways. Analysis of sex differences within each age suggests that juvenile and aged cardiac transcriptomes are different between males and females, with significantly fewer DEGs identified in adult males and females. Interestingly, the male–female differences in early age were distinct from those in advanced age. These findings are in contrast to expected sex differences historically attributed to estrogen and could not be explained by estrogen‐direct mechanisms alone as evidenced by juvenile sexual immaturity and reproductive incompetence in the aged mice. Together, distinct trajectories in cardiac transcriptomic profiles highlight fundamental sex differences across the life course and demonstrate the need for the consideration of age and sex as biological variables in heart disease.
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Affiliation(s)
- Aykhan Yusifov
- Kinesiology and Health, University of Wyoming, Laramie, WY, USA
| | | | - Eva K Koplin
- Kinesiology and Health, University of Wyoming, Laramie, WY, USA
| | - Cortney E Wilson
- Division of Cardiology, University of Colorado-Denver, Aurora, CO, USA
| | - Emily E Schmitt
- Kinesiology and Health, University of Wyoming, Laramie, WY, USA
| | - Kathleen C Woulfe
- Division of Cardiology, University of Colorado-Denver, Aurora, CO, USA.,Division of Geriatric Medicine, University of Colorado-Denver, Aurora, CO, USA
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8
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Yusifov A, Chhatre VE, Zumo JM, Cook RF, McNair BD, Schmitt EE, Woulfe KC, Bruns DR. Cardiac response to adrenergic stress differs by sex and across the lifespan. GeroScience 2021; 43:1799-1813. [PMID: 33651247 DOI: 10.1007/s11357-021-00345-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Accepted: 02/21/2021] [Indexed: 02/07/2023] Open
Abstract
The aging heart is well-characterized by a diminished responsiveness to adrenergic activation. However, the precise mechanisms by which age and sex impact adrenergic-mediated cardiac function remain poorly described. In the current investigation, we compared the cardiac response to adrenergic stress to gain mechanistic understanding of how the response to an adrenergic challenge differs by sex and age. Juvenile (4 weeks), adult (4-6 months), and aged (18-20 months) male and female mice were treated with the β-agonist isoproterenol (ISO) for 1 week. ISO-induced morphometric changes were age- and sex-dependent as juvenile and adult mice of both sexes had higher left ventricle weights while aged mice did not increase cardiac mass. Adults increased myocyte cell size and deposited fibrotic matrix in response to ISO, while juvenile and aged animals did not show evidence of hypertrophy or fibrosis. Juvenile females and adults underwent expected changes in systolic function with higher heart rate, ejection fraction, and fractional shortening. However, cardiac function in aged animals was not altered in response to ISO. Transcriptomic analysis identified significant differences in gene expression by age and sex, with few overlapping genes and pathways between groups. Fibrotic and adrenergic signaling pathways were upregulated in adult hearts. Juvenile hearts upregulated genes in the adrenergic pathway with few changes in fibrosis, while aged mice robustly upregulated fibrotic gene expression without changes in adrenergic genes. We suggest that the response to adrenergic stress significantly differs across the lifespan and by sex. Mechanistic definition of these age-related pathways by sex is critical for future research aimed at treating age-related cardiac adrenergic desensitization.
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Affiliation(s)
- Aykhan Yusifov
- Division of Kinesiology and Health, University of Wyoming, Laramie, WY, USA
| | | | - Jacob M Zumo
- School of Medicine, WWAMI Medical Education, University of Washington, Seattle, WA, USA
| | - Ross F Cook
- Division of Kinesiology and Health, University of Wyoming, Laramie, WY, USA
| | - Benjamin D McNair
- Division of Kinesiology and Health, University of Wyoming, Laramie, WY, USA
| | - Emily E Schmitt
- Division of Kinesiology and Health, University of Wyoming, Laramie, WY, USA.,School of Medicine, WWAMI Medical Education, University of Washington, Seattle, WA, USA
| | - Kathleen C Woulfe
- Divisions of Cardiology and Geriatric Medicine, University of Colorado-Denver, Aurora, CO, USA
| | - Danielle R Bruns
- Division of Kinesiology and Health, University of Wyoming, Laramie, WY, USA. .,School of Medicine, WWAMI Medical Education, University of Washington, Seattle, WA, USA.
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9
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McNair BD, Marcello NA, Smith DT, Schmitt EE, Bruns DR. Changes in Muscle Mass and Composition by Exercise and Hypoxia as Assessed by DEXA in Mice. ACTA ACUST UNITED AC 2020; 56:medicina56090446. [PMID: 32899136 PMCID: PMC7558449 DOI: 10.3390/medicina56090446] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 08/31/2020] [Accepted: 09/02/2020] [Indexed: 11/16/2022]
Abstract
Background and Objective: Skeletal muscle is critical for overall health and predicts quality of life in several chronic diseases, thus quantification of muscle mass and composition is necessary to understand how interventions promote changes in muscle quality. The purpose of this investigation was to quantify changes in muscle mass and composition in two distinct pre-clinical models of changes in muscle quality using a clinical dual X-ray absorptiometry (DEXA), validated for use in mice. Materials and Methods: Adult C57Bl6 male mice were given running wheels (RUN; muscle hypertrophy) or placed in hypobaric hypoxia (HH; muscle atrophy) for four weeks. Animals received weekly DEXA and terminal collection of muscle hind limb complex (HLC) and quadriceps weights and signaling for molecular regulators of muscle mass and composition. Results: HH decreased total HLC muscle mass with no changes in muscle composition. RUN induced loss of fat mass in both the quadriceps and HLC. Molecular mediators of atrophy were upregulated in HH while stimulators of muscle growth were higher in RUN. These changes in muscle mass and composition were quantified by a clinical DEXA, which we described and validated for use in pre-clinical models. Conclusions: RUN improves muscle composition while HH promotes muscle atrophy, though changes in composition in hypoxia remain unclear. Use of the widely available clinical DEXA for use in mice enhances translational research capacity to understand the mechanisms by which atrophy and hypertrophy promote skeletal muscle and overall health.
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10
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Loseke J, Schmitt EE, Dillon ME, Zamora M, Green CJ, Smith DT, Johnson EC. Exercise Heat Exposure Induced Changes In Genetic Expression Before And After Heat Acclimation In Humans. Med Sci Sports Exerc 2020. [DOI: 10.1249/01.mss.0000679940.04184.5a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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11
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Brown KD, Waggy ED, Nair S, Robinson TJ, Schmitt EE, Bruns DR, Thomas DP. Sex Differences in Cardiac AMP-Activated Protein Kinase Following Exhaustive Exercise. Sports Med Int Open 2020; 4:E13-E18. [PMID: 32232123 PMCID: PMC7101246 DOI: 10.1055/a-1115-6373] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 01/25/2020] [Accepted: 02/05/2020] [Indexed: 01/04/2023] Open
Abstract
Ischemic heart disease presents with significant differences between sexes. Endurance exercise protects the heart against ischemic disease and also distinctly impacts male and female patients through unidentified mechanisms, though some evidence implicates 5'-AMP-activated protein kinase (AMPK). The purpose of this investigation was to assess the impact of training and sex on cardiac AMPK activation following exhaustive exercise. AMPK activation was measured in trained and sedentary mice of both sexes. Trained mice ran on a treadmill at progressively increasing speeds and duration for 12 weeks. Trained and sedentary mice of both sexes were euthanized immediately following exhaustive exercise and compared to sedentary controls. Endurance training elicited adaptations indicative of aerobic adaptation including higher max running velocities and cardiac hypertrophy with no differences between males and females. AMPK activity was higher in male compared to females, and trained exhibited higher AMPK activity compared to sedentary mice. In response to training, male mice activated AMPK more robustly than female mice. Chronic exercise training increases the ability to activate cardiac AMPK in response to exhaustive exercise in a sex-specific manner. Understanding the interaction between exercise and sex is vital for use of exercise as medicine for heart disease in both men and women.
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Affiliation(s)
- Kevin D Brown
- Division of Kinesiology & Health, University of Wyoming, College of Health Sciences, Laramie, United States
| | - Edward D Waggy
- Division of Kinesiology & Health, University of Wyoming, College of Health Sciences, Laramie, United States
| | - Sreejayan Nair
- School of Pharmacy, University of Wyoming, Laramie, United States.,WWAMI Medical Education, University of Wyoming, Laramie, United States
| | | | - Emily E Schmitt
- Division of Kinesiology & Health, University of Wyoming, College of Health Sciences, Laramie, United States.,WWAMI Medical Education, University of Wyoming, Laramie, United States
| | - Danielle R Bruns
- Division of Kinesiology & Health, University of Wyoming, College of Health Sciences, Laramie, United States.,WWAMI Medical Education, University of Wyoming, Laramie, United States
| | - D Paul Thomas
- Division of Kinesiology & Health, University of Wyoming, College of Health Sciences, Laramie, United States
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12
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Yusifova M, McNair B, Cook RF, Schmitt EE, Bruns DR. Differential Cardiac Adaptation to Free‐Wheel Running in Old and Young Mice: Impact of the Cardiac Circadian Clock. FASEB J 2020. [DOI: 10.1096/fasebj.2020.34.s1.02609] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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13
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Abstract
The mammalian circadian clock governs physiological, endocrine, and metabolic responses coordinated in a 24-h rhythmic pattern by the suprachiasmatic nucleus (SCN) of the anterior hypothalamus. The SCN also dictates circadian rhythms in peripheral tissues like the kidney. The kidney has several important physiological functions, including removing waste and filtering the blood and regulating fluid volume, blood osmolarity, blood pressure, and Ca2+ metabolism, all of which are under tight control of the molecular/circadian clock. Normal aging has a profound influence on renal function, central and peripheral circadian rhythms, and the sleep-wake cycle. Disrupted circadian rhythms in the kidney as a result of increased age likely contribute to adverse health outcomes such as nocturia, hypertension, and increased risk for stroke, cardiovascular disease, and end organ failure. Regular physical activity improves circadian misalignment in both young and old mammals, although the precise mechanisms for this protection remain poorly described. Recent advances in the heart and skeletal muscle literature suggest that regular endurance exercise entrains peripheral clocks, and we propose that similar beneficial adaptations occur in the kidney through regulation of renal blood flow and fluid balance.
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Affiliation(s)
- Emily E Schmitt
- Division of Kinesiology and Health, University of Wyoming, Laramie, Wyoming
| | - Evan C Johnson
- Division of Kinesiology and Health, University of Wyoming, Laramie, Wyoming
| | - Musharraf Yusifova
- Division of Kinesiology and Health, University of Wyoming, Laramie, Wyoming
| | - Danielle R Bruns
- Division of Kinesiology and Health, University of Wyoming, Laramie, Wyoming
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14
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Pearson SJ, Roy Sarkar T, McQueen CM, Elswood J, Schmitt EE, Wall SW, Scribner KC, Wyatt G, Barhoumi R, Behbod F, Rijnkels M, Porter WW. ATM-dependent activation of SIM2s regulates homologous recombination and epithelial-mesenchymal transition. Oncogene 2018; 38:2611-2626. [PMID: 30531838 PMCID: PMC6450754 DOI: 10.1038/s41388-018-0622-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Revised: 11/13/2018] [Accepted: 11/18/2018] [Indexed: 12/15/2022]
Abstract
There is increasing evidence that genomic instability is a prerequisite for cancer progression. Here we show that SIM2s, a member of the bHLH/PAS family of transcription factors, regulates DNA damage repair through enhancement of homologous recombination, and prevents epithelial mesenchymal transitions (EMT) in an ATM dependent manner. Mechanistically, we found that SIM2s interacts with ATM and is stabilized through ATM-dependent phosphorylation in response to ionizing radiation (IR). Once stabilized, SIM2s interacts with BRCA1 and supports RAD51 recruitment to the site of DNA damage. Loss of SIM2s through the introduction of shSIM2 or the mutation of SIM2s at one of the predicted ATM phosphorylation sites (S115) reduces homologous recombination efficiency through disruption of RAD51 recruitment, resulting in genomic instability and induction of EMT. The EMT induced by the mutation of S115 is characterized by a decrease in E-cadherin and an induction of the basal marker, K14, resulting in increased invasion and metastasis. Together, these results identify a novel player in the DNA damage repair pathway and provides a link in DCIS progression to IDC through loss of SIM2s, increased genomic instability, EMT and metastasis.
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Affiliation(s)
- Scott J Pearson
- Department of Integrative Biosciences, College of Veterinary Medicine, Texas A&M University, College Station, TX, 77843, USA
| | - Tapasree Roy Sarkar
- Department of Integrative Biosciences, College of Veterinary Medicine, Texas A&M University, College Station, TX, 77843, USA
| | - Cole M McQueen
- Department of Integrative Biosciences, College of Veterinary Medicine, Texas A&M University, College Station, TX, 77843, USA
| | - Jessica Elswood
- Department of Integrative Biosciences, College of Veterinary Medicine, Texas A&M University, College Station, TX, 77843, USA
| | - Emily E Schmitt
- Department of Integrative Biosciences, College of Veterinary Medicine, Texas A&M University, College Station, TX, 77843, USA
| | - Steven W Wall
- Department of Integrative Biosciences, College of Veterinary Medicine, Texas A&M University, College Station, TX, 77843, USA
| | - Kelly C Scribner
- Department of Integrative Biosciences, College of Veterinary Medicine, Texas A&M University, College Station, TX, 77843, USA
| | - Garhett Wyatt
- Department of Integrative Biosciences, College of Veterinary Medicine, Texas A&M University, College Station, TX, 77843, USA
| | - Rola Barhoumi
- Department of Integrative Biosciences, College of Veterinary Medicine, Texas A&M University, College Station, TX, 77843, USA
| | - Fariba Behbod
- Department of Pathology and Laboratory Medicine, University of Kansas Medical Center, Kansas City, KS, 66160, USA
| | - Monique Rijnkels
- Department of Integrative Biosciences, College of Veterinary Medicine, Texas A&M University, College Station, TX, 77843, USA
| | - Weston W Porter
- Department of Integrative Biosciences, College of Veterinary Medicine, Texas A&M University, College Station, TX, 77843, USA. .,Veterinary Integrative Biosciences, Texas A&M University, College of Veterinary Medicine, College Station, TX, 77843, USA.
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McQueen CM, Schmitt EE, Sarkar TR, Elswood J, Metz RP, Earnest D, Rijnkels M, Porter WW. PER2 regulation of mammary gland development. Development 2018; 145:dev.157966. [PMID: 29490985 PMCID: PMC5897596 DOI: 10.1242/dev.157966] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Accepted: 02/19/2018] [Indexed: 12/24/2022]
Abstract
The molecular clock plays key roles in daily physiological functions, development and cancer. Period 2 (PER2) is a repressive element, which inhibits transcription activated by positive clock elements, resulting in diurnal cycling of genes. However, there are gaps in our understanding of the role of the clock in normal development outside of its time-keeping function. Here, we show that PER2 has a noncircadian function that is crucial to mammalian mammary gland development. Virgin Per2-deficient mice, Per2-/- , have underdeveloped glands, containing fewer bifurcations and terminal ducts than glands of wild-type mice. Using a transplantation model, we show that these changes are intrinsic to the gland and further identify changes in cell fate commitment. Per2-/- mouse mammary glands have a dual luminal/basal phenotypic character in cells of the ductal epithelium. We identified colocalization of E-cadherin and keratin 14 in luminal cells. Similar results were demonstrated using MCF10A and shPER2 MCF10A human cell lines. Collectively this study reveals a crucial noncircadian function of PER2 in mammalian mammary gland development, validates the Per2-/- model, and describes a potential role for PER2 in breast cancer.
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Affiliation(s)
- Cole M McQueen
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA
| | - Emily E Schmitt
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA
| | - Tapasree R Sarkar
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA
| | - Jessica Elswood
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA
| | - Richard P Metz
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA
| | - David Earnest
- Department of Neuroscience and Experimental Therapeutics, Texas A&M Health Science Center, College of Medicine, Bryan, TX 77807, USA
| | - Monique Rijnkels
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA
| | - Weston W Porter
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA
- Center for Biological Clocks Research, Texas A&M University, College Station, TX 77843, USA
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Abstract
INTRODUCTION Voluntary physical activity levels are regulated by sex hormones. The purpose of this study was to determine the effect of the endocrine disruptor benzyl butyl phthalate (BBP) on the regulation of physical activity in mice. METHODS Mouse dams were treated with 500 mg·kg·d of BBP or vehicle on gestation days 9-16. Pups were weaned and analyzed for voluntary physical activity levels, puberty development, sex hormone levels, and body composition during the 20-wk period. RESULTS Seventy-three offspring from BBP-treated dams were studied (n = 43 males and n = 30 females). Endocrine disruption was indicated by decreased anogenital distances in BBP-treated male offspring at 10 (P = 0.001) and 20 wk (P = 0.038) and delayed vaginal openings in BBP-treated female offspring (P = 0.001). Further, there was a significant decrease in serum testosterone concentration in male mice between control and BBP at 10 wk (P = 0.039) and at 20 wk (P = 0.022). In female mice, there was a significant increase in serum testosterone concentration in BBP mice at 20 wk (P = 0.002) and a significant increase in estrogen (estradiol) concentrations at 20 wk in the control female mice (P = 0.015). Overall, BBP mice ran significantly less distance (males, P = 0.008; females, P = 0.042) than controls. Other than a significant increase in BBP-treated males in fat mass at 20 wk (P = 0.040), there was no significant decrease in weight, lean mass, or fat mass in either female or male mice, regardless of treatment. CONCLUSION Maternal endocrine disruption altered hormone response, but not body composition in either sex of offspring, with a corresponding decreased activity throughout early adulthood in all offspring. These results suggest that exposure to common environmental endocrine disruptors in utero can reduce and alter physical activity levels in offspring.
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Affiliation(s)
- Emily E Schmitt
- 1Department of Health and Kinesiology, Texas A&M University, College Station, TX; and 2Interdisciplinary Faculty of Toxicology, Texas A&M University, College Station, TX
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Schmitt EE, Barhoumi R, Metz RP, Porter WW. Circadian Regulation of Benzo[a]Pyrene Metabolism and DNA Adduct Formation in Breast Cells and the Mouse Mammary Gland. Mol Pharmacol 2016; 91:178-188. [PMID: 28007926 DOI: 10.1124/mol.116.106740] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Accepted: 12/21/2016] [Indexed: 11/22/2022] Open
Abstract
The circadian clock plays a role in many biologic processes, yet very little is known about its role in metabolism of drugs and carcinogens. The purpose of this study was to define the impact of circadian rhythms on benzo-a-pyrene (BaP) metabolism in the mouse mammary gland and develop a circadian in vitro model for investigating changes in BaP metabolism resulting from cross-talk between the molecular clock and aryl hydrocarbon receptor. Female 129sv mice (12 weeks old) received a single gavage dose of 50 mg/kg BaP at either noon or midnight, and mammary tissues were isolated 4 or 24 hours later. BaP-induced Cyp1a1 and Cyp1b1 mRNA levels were higher 4 hours after dosing at noon than at 4 hours after dosing at midnight, and this corresponded with parallel changes in Per gene expression. In our in vitro model, we dosed MCF10A mammary cells at different times after serum shock to study how time of day shifts drug metabolism in cells. Analysis of CYP1A1 and CYP1B1 gene expression showed the maximum enzyme-induced metabolism response 12 and 20 hours after shock, as determined by ethoxyresorufin-O-deethylase activity, metabolism of BaP, and formation of DNA-BaP adducts. The pattern of PER-, BMAL-, and aryl hydrocarbon receptor-induced P450 gene expression and BaP metabolism was similar to BaP-induced Cyp1A1 and Cyp1B1 and molecular clock gene expression in mouse mammary glands. These studies indicate time-of-day exposure influences BaP metabolism in mouse mammary glands and describe an in vitro model that can be used to investigate the circadian influence on the metabolism of carcinogens.
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Affiliation(s)
- Emily E Schmitt
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine, Texas A&M University, College Station, Texas
| | - Rola Barhoumi
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine, Texas A&M University, College Station, Texas
| | - Richard P Metz
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine, Texas A&M University, College Station, Texas
| | - Weston W Porter
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine, Texas A&M University, College Station, Texas
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Ferguson DP, Dangott LJ, Vellers HL, Schmitt EE, Lightfoot JT. Differential protein expression in the nucleus accumbens of high and low active mice. Behav Brain Res 2015; 291:283-288. [DOI: 10.1016/j.bbr.2015.05.035] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2014] [Revised: 05/08/2015] [Accepted: 05/18/2015] [Indexed: 02/02/2023]
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Schmitt EE, Porter WW, Lightfoot JT. Endocrine-disruption And The Regulation Of Physical Activity And Mammary Gland Development In Mice. Med Sci Sports Exerc 2015. [DOI: 10.1249/01.mss.0000476610.52500.ee] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Schmitt EE, Vellers HL, Irwin CD, Lightfoot T. Endocrine-disruption And Regulation Of Physical Activity In Mice. Med Sci Sports Exerc 2014. [DOI: 10.1249/01.mss.0000493168.38133.fd] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Abstract
Physical inactivity contributes to cardiovascular disease, type II diabetes, obesity, and some types of cancer. While the literature is clear that there is genetic regulation of physical activity with existing gene knockout data suggesting that skeletal muscle mechanisms contribute to the regulation of activity, actual differences in end-protein expression between high- and low-active mice have not been investigated. This study used two-dimensional differential gel electrophoresis coupled with mass spectrometry to evaluate the proteomic differences between high-active (C57L/J) and low-active (C3H/HeJ) mice in the soleus and extensor digitorum longus (EDL). Furthermore, vivo-morpholinos were used to transiently knockdown candidate proteins to confirm their involvement in physical activity regulation. Proteins with higher expression patterns generally fell into the calcium-regulating and Krebs (TCA) cycle pathways in the high-active mice (e.g., annexin A6, P = 0.0031; calsequestrin 1; P = 0.000025), while the overexpressed proteins in the low-active mice generally fell into cytoskeletal structure- and electron transport chain-related pathways (e.g., ATPase, P = 0.031; NADH dehydrogenase, P = 0.027). Transient knockdown of annexin A6 and calsequestrin 1 protein of high-active mice with vivo-morpholinos resulted in decreased physical activity levels (P = 0.001). These data suggest that high- and low-active mice have unique protein expression patterns and that each pattern contributes to the peripheral capability to be either high- or low-active, suggesting that different specific mechanisms regulate activity leading to the high- or low-activity status of the animal.
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Affiliation(s)
- David P Ferguson
- Children's Nutritional Research Center, Baylor College of Medicine, Houston, Texas
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Abstract
Physical activity is associated with disease prevention and overall wellbeing. Additionally there has been evidence that physical activity level is a result of genetic influence. However, there has not been a reliable method to silence candidate genes in vivo to determine causal mechanisms of physical activity regulation. Vivo-morpholinos are a potential method to transiently silence specific genes. Thus, the aim of this study was to validate the use of Vivo-morpholinos in a mouse model for voluntary physical activity with several sub-objectives. We observed that Vivo-morpholinos achieved between 60–97% knockdown of Drd1-, Vmat2-, and Glut4-protein in skeletal muscle, the delivery moiety of Vivo-morpholinos (scramble) did not influence physical activity and that a cocktail of multiple Vivo-morpholinos can be given in a single treatment to achieve protein knockdown of two different targeted proteins in skeletal muscle simultaneously. Knocking down Drd1, Vmat2, or Glut4 protein in skeletal muscle did not affect physical activity. Vivo-morpholinos injected intravenously alone did not significantly knockdown Vmat2-protein expression in the brain (p = 0.28). However, the use of a bradykinin analog to increase blood-brain-barrier permeability in conjunction with the Vivo-morpholinos significantly (p = 0.0001) decreased Vmat2-protein in the brain with a corresponding later over-expression of Vmat2 coincident with a significant (p = 0.0016) increase in physical activity. We conclude that Vivo-morpholinos can be a valuable tool in determining causal gene-phenotype relationships in whole animal models.
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Affiliation(s)
- David P Ferguson
- Department of Health and Kinesiology, Texas A&M University, College Station, Texas, United States of America.
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Schmitt EE, Ferguson DP, Lightfoot JT. Knock‐down of Vmat2 in Mouse Right Striatum and Physical Activity. FASEB J 2012. [DOI: 10.1096/fasebj.26.1_supplement.1151.11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Ferguson DP, Schmitt EE, Lightfoot JT. The effect of Vivo‐Morpholino targeting Vmat2 on daily physical activity in mouse soleus compared to scrambledmorpholino control. FASEB J 2012. [DOI: 10.1096/fasebj.26.1_supplement.716.8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Downey PT, Ballard TM, Schmitt EE, Nebus PL. Cancer Rehabilitation: Observed Trends of Cancer Survivors' Physical Activity Levels Prior to Diagnosis and When Starting the Strides to Strength Group Exercise Program. Med Sci Sports Exerc 2011. [DOI: 10.1249/01.mss.0000401550.23123.e4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Schmitt EE, Hubbard TJ, Turner MJ. Fitness Facility Use Does Not Increase Step Activity in Independent Living Older Adults. Med Sci Sports Exerc 2010. [DOI: 10.1249/01.mss.0000385486.76004.5c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Ferguson DP, Moore-Harrison TL, Bowen RS, Hall KJ, Schmitt EE, Hamilton AT, Mosher A, Lightfoot JT. Heart Rate And Core Temperature Responses Of Pit Crew Athletes During Elite Automobile Races. Med Sci Sports Exerc 2009. [DOI: 10.1249/01.mss.0000355006.31037.68] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Davis JA, Miller PC, Cooper KL, Schmitt EE, Bixby WR, Hall EE. Relationships between Self-Efficacy and Exercise Performance during Treadmill Running. Med Sci Sports Exerc 2007. [DOI: 10.1249/01.mss.0000274625.10184.32] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Miller PC, Bailey EK, Cooper KL, Schmitt EE, Bixby WR, Hall EE. Affective Responses to Treadmill Running with Distraction and Stratified by Preference. Med Sci Sports Exerc 2007. [DOI: 10.1249/01.mss.0000274788.03492.92] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Vistnes LM, Schmitt EE, Ksander GA, Rose EH, Balkenhol WJ, Coleman CL. Evaluation of a prototype therapeutic system for prolonged, continuous topical delivery of homosulfanilamide in the management of Pseudomonas burn wound sepsis. Surgery 1976; 79:690-6. [PMID: 1273754] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The ability of homosulfanilimide (HS) delivered from two different dressing vehicles to limit bacterial proliferation was evaluated in burned animals deliberately infected with virulent Pseudomonas organisms. Treatment consisted of once daily topical application of one of two vehicles: (1) an experimental prototype system that utilized micronized HS in a hydrophobic, bioerodible, polymeric matrix, impregnated on a fabric backing; or (2) a commercially available dressing that contained the same mass of drug in a hydrophilic cream base impregnated on the same backing. Wounds on control animals were covered with fabric backing with or without the bioerodible matrix. The experimental system was designed to maintain a finite local concentration of HS on the burn wound for at least 24 hours. It is known that the cream base presents a rapidly decreasing concentration of drug to the burn surface. HS delivered from the experimental system produced a significant reduction in deaths compared with the HS delivered from the cream base. In addition, the new method of delivering HS provided better control of local and systemic infection, and better wound hydration and also promoted earlier eschar separation. The experimental system was at least as convenient to apply as the cream and had an advantage with respect to inspection of the wound, since it could be removed and reapplied easily.
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Capozza RC, Schmitt EE, Seńdelbeck LR. Development of Chronomers tm for narcotic antagonists. Natl Inst Drug Abuse Res Monogr Ser 1976:39-42. [PMID: 967234] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The object of this program is to prepare a bioerodable naltrexone delivery system which can be implanted subcutaneously in humans and which can relieve the narcotic antagonist over 1-6 months at relatively constant and sufficient rates to block the euphoric effect of morphine based drugs. The system is composed of naltrexone uniformly dispered in a solid hydropholic CHRONOMER TM matrix which undergoes predictable surface erosion when exposed to an aqueous medium. Kinetic studies in vitro have been carried out during the course of the program to determine the best composition for the system. Toxilogical studies conducted at ALZA during the past 2 years have not revealed limiting adverse effects of either the CHRONOMER TM materials or their hydrolysis products. The tail-flick test procedure was used to measure the effectiveness of naltrexone to antagonize the analgesis of morphine in rats. Naltrexone infused intravenously at doses of 4 and 16 ug/kg/hr resulted in, after 6 hours, 54 and 89% antagonism, respectively, against a 63.5% effective dose of morphine. Perliminary sterilization studies showed that no adverse effects to CHRONOMER TM/naltrexone systems occurred after exposure to 2.5 or 5.0 mrads of 60CO irradiation.
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