Scholarly Works, Human Nutrition, Foods, and Exercise

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An accountability evaluation for the industry's responsible use of brand mascots and licensed media characters to market a healthy diet to American children
Kraak, Vivica; Story, M. (Wiley-Blackwell, 2015-06-01)
Adjust your own oxygen mask before helping those around you: an autoethnography of participatory research
Steketee, Abby M.; Archibald, Thomas G.; Harden, Samantha M. (2020-09-03)
Background There is a need to unpack the empirical, practical, and personal challenges within participatory approaches advocated to optimize implementation. The unpredictable, chaotic nature of participatory approaches complicates application of implementation theories, methods, and strategies which do not address researchers’ situatedness within participatory processes. As an implementation scientist, addressing one’s own situatedness through critical reflection is important to unearth how conscious and unconscious approaches, including ontological and epistemological underpinnings, influence the participatory context, process, and outcomes. Therefore, the aim of this exploratory work is to investigate the heretofore blind spot toward the lived experience of implementation researchers within the participatory process. Methods We developed an integrated research-practice partnership (IRPP) to inform the implementation of a gestational weight gain (GWG) control program. Within this IRPP, one investigator conducted a 12-month autoethnography. Data collection and triangulation included field notes, cultural artifacts, and systematic timeline tracking. Data analysis included ethnographic-theoretical dialogue and restorying to synthesize key events and epiphanies into a narrative. Results Analysis revealed the unpredicted evolution of the GWG program into a maternal health fair and three themes within the researchers’ lived experience: (1) permeable work boundaries, (2) individual and collective blind spots toward the ontological and epistemological underpinnings of implementation paradigms, and (3) maladaptive behaviors seemingly reinforced by the research culture. These themes contributed to the chaos of implementation and to researchers’ experience of inadequate recovery from cognitive, emotional, and practical demands. These themes also demonstrated the importance of contextual factors, subjectivity, and value-based judgments within implementation research. Conclusion Building on extant qualitative research guidelines, we suggest that researchers anchor their approach to implementation in reflexivity, intentionally and iteratively reflecting on their own situatedness. Through this autoethnography, we have elucidated several strategies based on critical reflection including examining philosophical underpinnings of research, adopting restorative practices that align with one’s values, and embracing personal presence as a foundation of scientific productivity. Within the predominant (post-) positivism paradigms, autoethnography may be criticized as unscientifically subjective or self-indulgent. However, this work demonstrates that autoethnography is a vehicle for third-person observation and first-person critical reflection that is transformative in understanding and optimizing implementation contexts, processes, and outcomes.
Adult Cranberry Beverage Consumers Have Healthier Macronutrient Intakes and Measures of Body Composition Compared to Non-Consumers: National Health and Nutrition Examination Survey (NHANES) 2005–2008
Duffey, Kiyah J.; Sutherland, Lisa A. (MDPI, 2013-12-04)
Flavonoids, present in high levels in cranberries, are potent bioactives known for their health-promoting benefits, but cranberry beverages (CB) are not typically recommended as part of a healthy diet. We examine the association between CB consumption with macronutrient intake and weight status. Data for US adults (≥19 years, n = 10,891) were taken from the National Health and Nutrition Examination Survey (NHANES) Survey 2005–2008. Total CB consumption was measured over two non-consecutive 24-h dietary recalls. Linear and logistic regression models adjusting for important covariates were used to examine predicted differences between CB consumers and non-consumers on macronutrient and anthropometric outcomes. Results are weighted to be nationally representative. CB consumers (n = 581) were older (>50 year) non-Hispanic black females. They consumed an average 221 mL (7.5 oz) CB per day. In fully adjusted models CB consumers (vs. non-consumers) had higher carbohydrates and total sugars and lower percent energy from protein and total fat (all p < 0.001), but no difference in total energy. A significantly higher proportion of CB consumers were predicted to be normal weight (BMI < 25 kg/m2; p = 0.001) and had to have lower waist circumferences (p = 0.001). Although there was not a significant trend across level of CB intake, low and middle level CB consumers compared to non-consumers were more likely to be normal weight (p < 0.001) and less likely to be overweight/obese (BMI ≥ 25 kg/m2, p < 0.001). Despite having slightly higher daily macronutrient intakes, CB consumers have more desirable anthropometric measures compared to non-consumers.
Advances in Nutrition Science and Integrative Physiology: Insights From Controlled Feeding Studies
Davy, Kevin P.; Davy, Brenda M. (Frontiers, 2019-10-29)
Nutrition science is a highly impactful but contentious area of biomedical science. Establishing cause and effect relationships between the nutrients and/or diets we consume and the avoidance of or risk of disease is extremely challenging. As such, evidence-based nutrition is best served by considering the totality of evidence across multiple study types including nutritional epidemiological studies, randomized controlled trials of behavioral interventions, and controlled feeding studies. The purpose of the present review is to provide an overview for those conducting research outside of clinical nutrition on how controlled feeding studies can be used to gain insight into integrative physiology/metabolism as well as to inform dietary guidelines. We discuss the rationale, basic elements, and complexities of conducting controlled feeding studies and provide examples of contributions of controlled feeding studies to advances in nutrition science and integrative physiology. Our goal is to provide a resource for those wishing to leverage the experimental advantage provided by controlled feeding studies in their own research programs.
Aging, resistance training, and diabetes prevention
Flack, Kyle D.; Davy, Kevin P.; Hulver, Matthew W.; Winett, Richard A.; Frisard, Madlyn I.; Davy, Brenda M. (2010-12-15)
With the aging of the baby-boom generation and increases in life expectancy, the American population is growing older. Aging is associated with adverse changes in glucose tolerance and increased risk of diabetes; the increasing prevalence of diabetes among older adults suggests a clear need for effective diabetes prevention approaches for this population. The purpose of paper is to review what is known about changes in glucose tolerance with advancing age and the potential utility of resistance training (RT) as an intervention to prevent diabetes among middle-aged and older adults. Age-related factors contributing to glucose intolerance, which may be improved with RT, include improvements in insulin signaling defects, reductions in tumor necrosis factor-α, increases in adiponectin and insulin-like growth factor-1 concentrations, and reductions in total and abdominal visceral fat. Current RT recommendations and future areas for investigation are presented.
Altered Expression of Human Mitochondrial Branched Chain Aminotransferase in Dementia with Lewy Bodies and Vascular Dementia
Ashby, Emma L.; Kierzkowska, Marta; Hull, Jonathon; Kehoe, Patrick G.; Hutson, Susan M.; Conway, Myra E. (2017-01)
Cytosolic and mitochondrial human branched chain aminotransferase (hBCATc and hBCATm, respectively) play an integral role in brain glutamate metabolism. Regional increased levels of hBCATc in the CA1 and CA4 region of Alzheimer's disease (AD) brain together with increased levels of hBCATm in frontal and temporal cortex of AD brains, suggest a role for these proteins in glutamate excitotoxicity. Glutamate toxicity is a key pathogenic feature of several neurological disorders including epilepsy associated dementia, AD, vascular dementia (VaD) and dementia with Lewy bodies (DLB). To further understand if these increases are specific to AD, the expression profiles of hBCATc and hBCATm were examined in other forms of dementia including DLB and VaD. Similar to AD, levels of hBCATm were significantly increased in the frontal and temporal cortex of VaD cases and in frontal cortex of DLB cases compared to controls, however there were no observed differences in hBCATc between groups in these areas. Moreover, multiple forms of hBCATm were observed that were particular to the disease state relative to matched controls. Real-time PCR revealed similar expression of hBCATm mRNA in frontal and temporal cortex for all cohort comparisons, whereas hBCATc mRNA expression was significantly increased in VaD cases compared to controls. Collectively our results suggest that hBCATm protein expression is significantly increased in the brains of DLB and VaD cases, similar to those reported in AD brain. These findings indicate a more global response to altered glutamate metabolism and suggest common metabolic responses that might reflect shared neurodegenerative mechanisms across several forms of dementia.
Angiotensin II suppresses autophagy and disrupts ultrastructural morphology and function of mitochondria in mouse skeletal muscle
Silva, Kleiton Augusto Santos; Ghiarone, Thaysa; Grant, DeAna; White, Tommi; Frisard, Madlyn I.; Chandrasekar, Bysani; Delafontaine, Patrice; Yoshida, Tadashi; Schreiber, Kathy; Sukhanov, Sergiy (2019-06-01)
Angiotensin II (ANG II)-induced skeletal muscle wasting is characterized by activation of the ubiquitin-proteasome system. However, the potential involvement of proteolytic system macroautophagy/autophagy in this wasting process remains elusive. Autophagy is precisely regulated to maintain cell survival and homeostasis; thus its dysregulation (i.e., overactivation or persistent suppression) could lead to detrimental outcomes in skeletal muscle. Here we show that infusion of ANG II for 7 days in male FVB mice suppressed autophagy in skeletal muscle. ANG II blunted microtubule-associated protein 1 light chain 3B (LC3B)-I-to-LC3B-II conversion (an autophagosome marker), increased p62/SQSTM1 (an autophagy cargo receptor) protein expression, and decreased the number of autophagic vacuoles. ANG II inhibited UNC-51-like kinase 1 via inhibition of 5=-AMP-activated kinase and activation of mechanistic target of rapamycin complex 1, leading to reduced phosphorylation of beclin-1Ser14 and Autophagy-related protein 14Ser29, suggesting that ANG II impairs autophagosome formation in skeletal muscle. In line with ANG II-mediated suppression of autophagy, ANG II promoted accumulation of abnormal/damaged mitochondria, characterized by swelling and disorganized cristae and matrix dissolution, with associated increase in PTEN-induced kinase 1 protein expression. ANG II also reduced mitochondrial respiration, indicative of mitochondrial dysfunction. Together, these results demonstrate that ANG II reduces autophagic activity and disrupts mitochondrial ultrastructure and function, likely contributing to skeletal muscle wasting. Therefore, strategies that activate autophagy in skeletal muscle have the potential to prevent or blunt ANG II-induced skeletal muscle wasting in chronic diseases. NEW & NOTEWORTHY Our study identified a novel mechanism whereby angiotensin II (ANG II) impairs mitochondrial energy metabolism in skeletal muscle. ANG II suppressed autophagosome formation by inhibiting the UNC-51-like kinase 1(ULK1)-beclin-1 axis, resulting in accumulation of abnormal/damaged and dysfunctional mitochondria and reduced mitochondrial respiratory capacity. Therapeutic strategies that activate the ULK1-beclin-1 axis have the potential to delay or reverse skeletal muscle wasting in chronic diseases characterized by increased systemic ANG II levels.
Applying a Multi-Dimensional Digital Food and Nutrition Literacy Model to Inform Research and Policies to Enable Adults in the U.S. Supplemental Nutrition Assistance Program to Make Healthy Purchases in the Online Food Retail Ecosystem
Consavage Stanley, Katherine; Harrigan, Paige B.; Serrano, Elena L.; Kraak, Vivica (MDPI, 2021-08-06)
The United States (U.S.) Department of Agriculture (USDA)-administered Supplemental Nutrition Assistance Program (SNAP) made substantial changes in response to the coronavirus disease 2019 (COVID-19) pandemic. These changes highlight the need to identify the digital literacy skills and capacities of SNAP adults to purchase healthy groceries online. We conducted a scoping review of four electronic databases, Google and Google Scholar to identify studies that measured food and nutrition literacy outcomes for U.S. adults. We applied a multi-dimensional digital food and nutrition literacy (MDFNL) model to assess six literacy levels and components. Of 18 studies published from 2006–2021, all measured functional and interactive literacy but no study measured communicative, critical, translational, or digital literacy. Six studies examined SNAP or SNAP-Education outcomes. Adults with higher food or nutrition literacy scores had better cognitive, behavioral, food security and health outcomes. We suggest how these findings may inform research, policies, and actions to strengthen the multi-dimensional literacy skills of SNAP participants and SNAP-eligible adults to support healthy purchases in the online food retail ecosystem.
Assessing the Internal and External Validity of Mobile Health Physical Activity Promotion Interventions: A Systematic Literature Review Using the RE-AIM Framework
Blackman, Kacie C. A.; Zoellner, Jamie M.; Berrey, Leanna M.; Alexander, Ramine C.; Fanning, Jason; Hill, Jennie L.; Estabrooks, Paul A. (JMIR Publications, 2013)
Background: Mobile health (mHealth) interventions are effective in promoting physical activity (PA); however, the degree to which external validity indicators are reported is unclear. Objective: The purpose of this systematic review was to use the RE-AIM (reach, effectiveness, adoption, implementation, and maintenance) framework to determine the extent to which mHealth intervention research for promoting PA reports on factors that inform generalizability across settings and populations and to provide recommendations for investigators planning to conduct this type of research. Methods: Twenty articles reflecting 15 trials published between 2000 and 2012 were identified through a systematic review process (ie, queries of three online databases and reference lists of eligible articles) and met inclusion criteria (ie, implementation of mobile technologies, target physical activity, and provide original data). Two researchers coded each article using a validated RE-AIM data extraction tool (reach, efficacy/effectiveness, adoption, implementation, maintenance). Two members of the study team independently abstracted information from each article (inter-rater reliability >90%) and group meetings were used to gain consensus on discrepancies. Results: The majority of studies were randomized controlled trials (n=14). The average reporting across RE-AIM indicators varied by dimension (reach=53.3%, 2.67/5; effectiveness/efficacy=60.0%, 2.4/4; adoption=11.1%, 0.7/6; implementation=24.4%, 0.7/3; maintenance=0%, 0/3). While most studies described changes in the primary outcome (effectiveness), few addressed the representativeness of participants (reach) or settings (adoption) and few reported on issues related to maintenance and degree of implementation fidelity. Conclusions: This review suggests that more focus is needed on research designs that highlight and report on both internal and external validity indicators. Specific recommendations are provided to encourage future mHealth interventionists and investigators to report on representativeness, settings, delivery agents for planned interventions, the extent to which protocol is delivered as intended, and maintenance of effects at the individual or organizational level.
An Assessment of Government Capacity Building to Restrict the Marketing of Unhealthy Food and Non-Alcoholic Beverage Products to Children in the Region of the Americas
Rincón-Gallardo Patiño, Sofía; da Silva Gomes, Fabio; Constantinou, Steven; Lemaire, Robin Hargroder; Hedrick, Valisa E.; Serrano, Elena L.; Kraak, Vivica (MDPI, 2021-08-06)
The Pan American Health Organization (PAHO) Strategic Plan 2020–2025 committed to reduce children’s consumption of energy-dense nutrient-poor food and beverage products high in fat, sugar and salt (HFSS) and promote healthy eating patterns to reduce malnutrition in all forms. This paper describes the capacity-building needs in PAHO’s Member States to restrict the marketing of HFSS food and beverages to children. We asked Ministries of Health officials or national institutes/departmental representatives (n = 35) to complete a 28-item web-based survey (January to July 2020). Capacity-building needs were assessed using an adapted version of the World Health Organization’s government capacity-building framework with three modules: public health infrastructure, policies and information systems. Notable achievements for the PAHO’s Plan of Action were identified. State representatives reported strong infrastructure and information systems; however, policy improvements are needed to increase comprehensive national responses. These include using a constitutional health and human rights approach within the policies, policies that document conflict of interest from non-state actors, and strengthening regulatory oversight for digital media platforms. These findings provide baseline data and we suggest priorities for further action to strengthen national governments’ capacity-building and to accelerate the development, implementation, and monitoring systems to restrict the marketing of HFSS food and non-alcoholic beverages to children in the region of the Americas.
The Availability of Competitive Foods and Beverages to Middle School Students in Appalachian Virginia Before Implementation of the 2014 Smart Snacks in School Standards
Mann, Georgianna Rhodes; Kraak, Vivica; Serrano, Elena L. (Centers for Disease Control and Prevention, 2015-09)
The study objective was to examine the nutritional quality of competitive foods and beverages (foods and beverages from vending machines and à la carte foods) available to rural middle school students, before implementation of the US Department of Agriculture’s Smart Snacks in School standards in July 2014. In spring 2014, we audited vending machines and à la carte cafeteria foods and beverages in 8 rural Appalachian middle schools in Virginia. Few schools had vending machines. Few à la carte and vending machine foods met Smart Snacks in School standards (36.5%); however, most beverages did (78.2%). The major challenges to meeting standards were fat and sodium content of foods. Most competitive foods (62.2%) did not meet new standards, and rural schools with limited resources will likely require assistance to fully comply.
Baicalein Protects against Type 2 Diabetes via Promoting Islet β-Cell Function in Obese Diabetic Mice
Fu, Y.; Luo, J.; Jia, Z.; Zhen, W.; Zhou, K.; Gilbert, Elizabeth R.; Liu, D.; Lee, H. (Hindawi, 2014)
In both type 1 (T1D) and type 2 diabetes (T2D), the deterioration of glycemic control over time is primarily caused by an inadequate mass and progressive dysfunction of β-cell, leading to the impaired insulin secretion. Here, we show that dietary supplementation of baicalein, a flavone isolated from the roots of Chinese herb Scutellaria baicalensis, improved glucose tolerance and enhanced glucose-stimulated insulin secretion (GSIS) in high-fat diet (HFD-) induced middle-aged obese mice. Baicalein had no effect on food intake, body weight gain, circulating lipid profile, and insulin sensitivity in obese mice. Using another mouse model of type 2 diabetes generated by high-fat diet (HFD) feeding and low doses of streptozotocin injection, we found that baicalein treatment significantly improved hyperglycemia, glucose tolerance, and blood insulin levels in these middle-aged obese diabetic mice, which are associated with the improved islet β-cell survival and mass. In the in vitro studies, baicalein significantly augmented GSIS and promoted viability of insulin-secreting cells and human islets cultured either in the basal medium or under chronic hyperlipidemic condition. These results demonstrate that baicalein may be a naturally occurring antidiabetic agent by directly modulating pancreatic β-cell function.
Beginning With the End in Mind: Contextual Considerations for Scaling-Out a Community-Based Intervention
Balis, Laura E.; Strayer, Thomas E., III; Ramalingam, NithyaPriya S.; Harden, Samantha M. (Frontiers, 2018-12-10)
Introduction: A number of effective physical activity programs for older adults exist, but are not widely delivered within community settings, such as the Cooperative Extension System. The purpose of this paper was to determine if an evidence-based intervention (EBI) developed in one state Extension system could be scaled-out to a new state system. Methods and results: The RE-AIM (reach, effectiveness, adoption, implementation, maintenance) framework was used to guide an iterative evaluation of three translational stages. Stage 1: Before program adoption, Extension health educators were surveyed and interviewed to assess physical activity programming perceptions and factors that may influence their decision to attend training or deliver the program in practice. Results indicated that a virtual, scalable training protocol would be necessary and that training needed to include hands-on instruction and be catered to those who were less confident in physical activity program delivery. Stage 2: Training attendees were surveyed pre- and post-training on factors related to the adoption-decision making process and contacted post-training to assess program delivery status. Training did not influence perceptions of the program, intent to deliver, or confidence in delivering the program. Stage 3: During program implementation, the program was evaluated through the RE-AIM framework by surveying across three key stakeholder groups: (1) program participants, (2) potential delivery personnel, and (3) Extension administrators. Findings indicate that the program has the potential to reach a large and representative proportion of the target audience, especially in rural areas. However, adoption and implementation rates among Extension health educators and community partners were low and data collection for effectiveness, implementation, and maintenance was a challenge. Conclusion: Overall, the results indicate initial struggles to translating and evaluating the program in a large, rural state. Implications for practice include making system-level changes to increase physical activity program adoption rates among Extension health educators and improve data collection and program evaluation through this community-based organization. More work is needed to identify infrastructure support and capacity to scale-out EBIs.
The Benefits of Vitamin D Supplementation for Athletes: Better Performance and Reduced Risk of COVID-19
Grant, William B.; Lahore, Henry; Rockwell, Michelle S. (MDPI, 2020-12-04)
The COVID-19 pandemic is having major economic and personal consequences for collegiate and professional sports. Sporting events have been canceled or postponed, and even when baseball and basketball seasons resumed in the United States recently, no fans were in attendance. As play resumed, several players developed COVID-19, disrupting some of the schedules. A hypothesis now under scientific consideration is that taking vitamin supplements to raise serum 25-hydroxyvitamin D [25(OH)D] concentrations could quickly reduce the risk and/or severity of COVID-19. Several mechanisms have been identified through which vitamin D could reduce the risks of infection and severity, death, and long-haul effects of COVID-19: (1) inducing production of cathelicidin and defensins to reduce the survival and replication of the SARS-CoV-2 virus; (2) reducing inflammation and the production of proinflammatory cytokines and risk of the “cytokine storm” that damages the epithelial layer of the lungs, heart, vascular system, and other organs; and (3) increasing production of angiotensin-converting enzyme 2, thus limiting the amount of angiotensin II available to the virus to cause damage. Clinical trials have confirmed that vitamin D supplementation reduces risk of acute respiratory tract infections, and approximately 30 observational studies have shown that incidence, severity, and death from COVID-19 are inversely correlated with serum 25(OH)D concentrations. Vitamin D supplementation is already familiar to many athletes and sports teams because it improves athletic performance and increases playing longevity. Thus, athletes should consider vitamin D supplementation to serve as an additional means by which to reduce risk of COVID-19 and its consequences.
The benefits, challenges, and strategies of adults following a local food diet
Byker Shanks, Carmen; Rose, Nick; Serrano, Elena L. (2010)
Supported in part by a variety of popular books, websites, and other media, the interest in local food is building dramatically, and a growing number of people are increasing their purchases of local food. This paper describes a study that explored the perceived benefits and challenges of following a diet consisting exclusively of local food in southwestern Virginia, as well as the strategies for coping with its limitations. Nineteen individuals participated in a four-week Local Food Diet Challenge, which included eating only foods produced from within 100 miles of the participants' homes. Part of a larger study looking at the nutritional impacts of a local food diet, this study included a pre-diet questionnaire that gathered participants' demographic characteristics, shopping patterns, eating behaviors, and attitudes toward local foods; consumption-reporting forms during the diet period; and a post-diet focus-group discussion for participants to share their experiences in following the local food diet. In this paper we report the major themes that emerged in the focus groups and offer recommendations for locavores and organizations attempting to maximize local food consumption.
Blastocyst Injection of Wild Type Embryonic Stem Cells Induces Global Corrections in Mdx Mice
Stillwell, Elizabeth; Vitale, Joseph; Zhao, Qingshi; Beck, Amanda; Schneider, Joel S.; Khadim, Farah; Elson, Genie; Altaf, Aneela; Yehia, Ghassan; Dong, Jia-hui; Liu, Jing; Mark, Willie; Bhaumik, Mantu; Grange, Robert W.; Fraidenraich, Diego (PLOS, 2009-03-11)
Duchenne muscular dystrophy (DMD) is an incurable neuromuscular degenerative disease, caused by a mutation in the dystrophin gene. Mdx mice recapitulate DMD features. Here we show that injection of wild-type (WT) embryonic stem cells (ESCs) into mdx blastocysts produces mice with improved pathology and function. A small fraction of WT ESCs incorporates into the mdx mouse nonuniformly to upregulate protein levels of dystrophin in the skeletal muscle. The chimeric muscle shows reduced regeneration and restores dystrobrevin, a dystrophin-related protein, in areas with high and with low dystrophin content. WT ESC injection increases the amount of fat in the chimeras to reach WT levels. ESC injection without dystrophin does not prevent the appearance of phenotypes in the skeletal muscle or in the fat. Thus, dystrophin supplied by the ESCs reverses disease in mdx mice globally in a dose-dependent manner.
Branded Marketing and Media Campaigns to Support a Healthy Diet in the United States, 1999-2016: Insights to Inform the Partnership for a Healthier America’s Fruits & Veggies (FNV) Campaign
Kraak, Vivica; Englund, Tessa R.; Zhou, Mi; Duffey, Kiyah J. (2017-03)
Introduction Obesity and diet-related non-communicable diseases (NCD) are serious public health challenges that have created an enormous financial burden on the United States (U.S) health care system. The United States spends an estimated $190 billion annually on obesity-related costs, representing about 20 percent of all medical spending. Childhood obesity is responsible for more than $14 billion dollars in direct medical costs...
Building Healthy Meals Together
Farris, Alisha; Serrano, Elena L. (Virginia Cooperative Extension, 2014-07-07)
This publication helps teach you and your kids the building blocks of a balanced meal and a healthy life with food and physical activity.
Calcineurin activation influences muscle phenotype in a muscle-specific fashion
Talmadge, Robert J.; Otis, Jeffrey S.; Rittler, Matthew R.; Garcia, Nicole D.; Spencer, Shelly R.; Lees, Simon J.; Naya, Francisco J. (2004-07-28)
Background The calcium activated protein phosphatase 2B, also known as calcineurin, has been implicated as a cell signaling molecule involved with transduction of physiological signals (free cytosolic Ca2+) into molecular signals that influence the expression of phenotype-specific genes in skeletal muscle. In the present study we address the role of calcineurin in mediating adaptations in myosin heavy chain (MHC) isoform expression and muscle mass using 3-month old wild-type (WT) and transgenic mice displaying high-level expression of a constitutively active form of calcineurin (MCK-CN* mice). Results Slow muscles, e.g., soleus, were significantly larger (by ~24%), whereas fast muscles, e.g., medial gastrocnemius (MG) and tibialis anterior were significantly smaller (by ~26 and ~16%, respectively) in MCK-CN* mice compared to WT. The masses of mixed phenotype muscles, such as the plantaris and the extensor digitorum longus, were not significantly changed from WT. The soleus, plantaris, MG and diaphragm displayed shifts toward slower MHC isoforms, e.g., soleus from WT mice contained ~52% MHC-I, ~39% MHC-IIa, and ~9% MHC-IIx, whereas MCK-CN* mice had ~67% MHC-I, ~26% MHC-IIa, and ~7% MHC-IIx. The specific isoforms that were either up or down-regulated were muscle-specific. For instance, the proportion of MHC-IIa was decreased in the soleus and diaphragm, but increased in the plantaris and MG of MCK-CN* mice. Also, the proportion of MHC-IIx was unchanged in the soleus, decreased in the diaphragm and increased in the plantaris and MG of MCK-CN* relative to WT mice. Fast to slow shifts in fiber type proportions were evident for the plantaris, but not the soleus. Fast, but not slow, plantaris fibers of MCK-CN* mice had higher oxidative and lower glycolytic properties than WT. Conclusion These data suggest that calcineurin activation can influence muscle phenotype and that the specific influence of calcineurin activation on the phenotypic and mass characteristics of a muscle is dependent upon the original phenotypic state of the muscle.
Calcium : build strong bones
Serrano, Elena L.; Sablik, Anna (Virginia Cooperative Extension, 2003)

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