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Biomedical subjects

D W Edington

Publications and source records attributed to D W Edington.

At least 37 records · Page 2Linked to original sources
PubMed1985

Tissue coenzyme Q (ubiquinone) and protein concentrations over the life span of the laboratory rat.

The coenzyme Q (ubiquinone) concentrations of a number of tissues have been determined over the life span of the male laboratory rat. Coenzyme Q increased between 2 and 18 months and decreased significantly at 25 months in the heart and kidney, and the gastrocnemius, oblique and deep aspect (red) vastus lateralis muscles. The coenzyme Q concentration of liver increased over the life span, while it remained relatively constant in brain, lung, and the superficial aspect (white) of the vastus lateralis muscle. Data are also included for organ weights and protein contents of tissues over the life span. The various roles of coenzyme Q in cellular electron transfer and its regulation, energy conservation in oxidative phosphorylation, and its clinical efficacy in diseases of energy metabolism are discussed. It is hypothesized that coenzyme Q serves as a free radical quencher in the mitochondrion, a major site of free radical formation, in addition to its other roles in cellular energy metabolism, and that its cellular diminution may contribute to the loss of cellular function accompanying ageing.

Aging↗
PubMed1984

Exercise-induced reversal of age-related declines of oxidative reactions, mitochondrial yield, and flavins in skeletal muscle of the rat.

The ability of gastrocnemius muscle homogenates to catalyze the oxidation of succinate, glutamate + malate, pyruvate + malate, palmitoyl-coenzyme A, decanoylcarnitine and palmitoylcarnitine in the presence of ADP decreased by approximately 32% in sedentary male Sprague-Dawley rats between the ages of 9 and 25 months. Following 21 weeks of treadmill training (running), such homogenates from 25-month-old animals catalyzed oxidations 55% more rapidly than those from 25-month-old sedentary rats, and 17% faster than those from 9-month-old sedentary rats. Total and peptide-bound flavin of gastrocnemius muscles also declined between 9 and 25 months of age and were elevated in the 25-month-old endurance trained rats to levels greater than both 9- and 25-month-old sedentary animals. The yield of protein in the mitochondrial fraction from the quadriceps femoris muscle decreased between 9 and 25 months and was restored to the 9-month level by endurance training. The kinetic characteristics of the isolated mitochondria were not influenced by age or exercise. These data indicate that 2-year-old rats retain the capacity to increase skeletal muscle oxidative capacity and mitochondrial population density in response to endurance training.

Aging↗
PubMed1983

Effects of dietary carnitine on myocardial palmitate oxidation in the aging rat.

Aging is associated with decreases in myocardial fatty acid oxidation and carnitine concentration. The purpose of this study was to investigate the effects of dietary carnitine manipulation on myocardial palmitate oxidation and carnitine content in young adult and middle-aged rats. Rats were fed either a carnitine-free or a carnitine-supplemented diet for nine weeks and killed at ages 6.5 and 18 months. Myocardial carnitine content was unaffected by age or diet. However, in 18 months rats fed a carnitine-free diet, myocardial palmitate oxidation was 77% higher, carnitine palmitoyltransferase activity 39% higher, and lipid droplet volume density 55% higher compared to 18 month rats fed a carnitine-supplemented diet. In 6.5 month rats, dietary carnitine had no effect on these variables. These results indicate that dietary carnitine restriction increases myocardial fatty acid metabolism in middle-aged but not in young adult rats.

Aging↗
PubMed1983

Myocardial protein synthesis during aging and endurance exercise in rats.

Rates of protein synthesis, and RNA and cytochrome c concentrations, were assayed in hearts of 9- and 25-month-old sedentary rats and 25-month-old rats trained to run 5 days/week for 21 weeks. Isolated working hearts were perfused with modified Krebs-Henseleit bicarbonate buffer labelled with [14C]phenylalanine. Protein synthesis rate decreased with age, as did RNA content and efficiency of protein synthesis, an indication of the activity per ribosome. None of these three parameters were altered by endurance training. Cytochrome c concentration, which also decreased significantly between 9 and 25 months, was increased in the 25-month-old endurance trained heart to the level of the 9-month-old sedentary heart. We conclude that the depressed protein synthetic system of aged animals is less of a liability in the endurance trained than in the sedentary animal as a consequence of the associated improvement in functional capacity that serves to minimize homeostatic disequilibrium in response to environmental challenges.

Aging↗
PubMed1983

Myocardial adaptations to endurance exercise in aged rats.

Isolated perfused working hearts of 25-mo-old male Sprague-Dawley rats trained to run for 16 wk were compared with hearts from 9- and 25-mo-old sedentary animals. Under low work load conditions, systolic and diastolic aortic pressures, aortic flow, and oxygen consumption of the three groups were similar. Under high work load, systolic pressure of trained old and 9-mo groups were higher than the 25-mo sedentary values, but diastolic pressures were similar. At a systolic pressure of 150 mmHg, coronary flow of the old trained heart was higher than that of the age-matched controls, although not equal to the 9-mo sedentary group. The oxygen consumption of the intact hearts under the latter conditions follows the same quantitative trend. Left ventricular cytochrome c concentrations and rates of oxidation of glutamate-malate, palmitoylcarnitine, and succinate were increased in the older rats by training but not to the level of the 9-mo old. These data indicate that appropriate exercise in aged animals improves myocardial function and aerobic energy metabolism.

Aging↗
PubMed1981

Selected biochemical parameters of two sizes of rat skeletal and heart muscle mitochondria at selected intervals of a 16-week endurance training program.

Increases in oxidative capacity of skeletal muscle which has undergone training is well documented. The concomitant shifts in mitochondrial size and cytochrome content have varied with different investigations. In this study the shifts in oxidative capacity, SDH activity, thiolase activity, was measured in two sizes of heart and skeletal muscle mitochondria of rats undergoing 4, 8, and 16 weeks of training. In addition cytochrome content was measured in both sizes of mitochondria of the skeletal muscle. The small mitochondria of skeletal muscle showed the significant gains in number during the first 8 weeks of training while the large mitochondria increased in number during the last 8 weeks of training. The oxygen consumption, SDH activity, thiolase activity and cytochrome content all showed varying peaks in activity and content in the different sizes of mitochondria over the 16 weeks of training. In evaluating training regimes' effects on skeletal muscle it appears important to take into consideration the shifts in size of mitochondria as well as oxidative capacity and enzymatic activity alterations. There were no alterations observed in mitochondrial size in cardiac tissue.

Acetyl-CoA C-Acyltransferase↗
PubMed1981

Effects of age and cardiac work in vitro on mitochondrial oxidative phosphorylation and (3H)-leucine incorporation.

Mitochondria isolated from in vitro perfused rat heart preparations were used to study the combined effects of age and physical stress. Age-related declines in oxidative phosphorylation catalyzed by mitochondria from nonperfused hearts were not observed. Low work load perfusion resulted in decreased respiration by mitochondria from 24-month-old hearts (p less than .01) but not 10-month old hearts, while high work load perfusion resulted in decreased respiration in both ages. However, the decrease by the 24-month-old hearts was significantly greater than those in the younger hearts (p less than .01). Compared to age-matched low work load hearts, 5- and 10-month-old high work load hearts increased mitochondrial protein synthesis by 86% and 93%, respectively, 15-month-old hearts increased by 60%, and 24-month-old hearts by 13%. The results of this study provide evidence that the ability of the heart to respond appropriately so as to adapt to stress decreases with age, becoming apparent in the laboratory rat between 10 and 15 months of age.

Aging↗
PubMedDate not supplied

A case study of 10-year health risk appraisal participation patterns in a comprehensive health promotion program.

Between 1990 and 1999, cumulative participation in a health risk appraisal (HRA) reached 79%, and participation in any health promotion program reached 94% of employees employed continuously by the Progressive Corporation during that time period. Participation rates in the HRA per year ranged from 14% to 36%. First time participants reached no higher than 2.6% after the sixth year. Non-participants tended to have higher mean but lower median costs.

Analysis of Variance↗
PubMedDate not supplied

Emerging research: a view from one research center.

The Health Management Research Center at the University of Michigan has assembled a database on health risks, medical care costs, an in some cases, productivity measures for over 2,000,000 individuals. For employees of its corporate consortium members, the database contains seven to eighteen years of data. Working with this data, the research team has observed a number of emerging trends. These trends have been stable in this data set for a number of years, but some of them are yet to be subjected to rigorous external peer review. The trends are summarized below. 1) Annual participation rates of 20% to 30% in Health Risk Appraisal are typical; over 10 years, 80% participate at least once, 60% at least twice and 40% at least three times. 2) Among the employers in the data base, excess risk factors account for 21% to 31% of medical care costs, with a mean of 25%. 3) Medical care costs increase as the number risk factors and age increase. As risk factors increase, medical costs increase; as risk factors decrease, medical care costs decrease. The mean cost increase per risk factor increased ($350) may be more than double the mean cost decrease per risk factor decreased ($150). 4) Cost savings greatest among those who participate in programs multiple times. 5) Absenteeism seems to be higher and other measures of productivity lower for those with health risk factors. 6) Programs designed to keep healthy people healthy in addition to reducing the risks of those with multiple risks will probably provide the greatest return to the employers. 7) Best results may be achieved by focusing efforts on employees who have clusters of risk factors associated with low perceived health status. 8) A corporate wellness score which combines risk factor levels and participation rates may provide a "corporate wellness score" which can be used to compare health status across employer. 9) Increased use of longitudinal data sets, fuzzy cut points for data categories and data mining techniques may allow breakthroughs in future analysis efforts.

Academies and Institutes↗
PubMedDate not supplied

Changes in health risks among the participants in the United Auto Workers--General Motors LifeSteps Health Promotion Program.

PURPOSE: To examine health risk changes among participants of a multicomponent worksite health promotion program. DESIGN: A study using health risk changes among health risk appraisal (HRA) participants linked to program participation records. Baseline risk and participation in multiple programs were examined in relation to risk change in multivariate models. SETTING: Worksite health promotion programming sponsored by the United Auto Workers (UAW) and General Motors (GM). SUBJECTS: Active employees (12,984) who voluntarily participated in an HRA in each of two program years. INTERVENTION: The nationwide program was a mailed HRA and a 1-800 nurse line. A pilot program (implemented in two cities) added screening, wellness programs, a materials resource, and, for high risk participants, health coaching and vouchers for medical office visits. MEASURES: Using 13 selected health risk factors from the HRA, changes in overall health risks were measured as program outcomes in three ways: one-directional, net, and risk status change. RESULTS: A greater decrease in the number of health risks was observed with increased program participation. The decrease was significantly related to the number of baseline risk factors and eligibility for high risk programs. Associated with program participation, the number of people at low risk status increased from 70.1% to 71.3% at year 2 among nationwide participants and from 52.4% to 58.9% among pilot participants. CONCLUSIONS: Participation was associated with a significant impact on health risk. Baseline risk of participants and eligibility for high risk programs were necessary factors to control when measuring program effects on health risk changes.

Health Promotion↗
PubMedDate not supplied

Associations between health risk appraisal scores and employee medical claims costs in a manufacturing company.

BACKGROUND: The bivariate relationships between 18 health-related measures on a health appraisal and prospective medical claims costs were examined among 1,838 employees for three consecutive years. METHODS: Employees were classified into high- or low-risk categories for each of the 18 health-related measures, and divided into high- or low-cost categories according to their averaged three-year medical costs respective to the mean of their sex/age subgroup. RESULTS: Average annual medical costs for the 18 health-related measures were $67 to $778 higher for the employees classified at high risk. The high-cost category was statistically associated with high-risk status in 11 of 18 health-related measures with a high-cost/high-risk to high-cost/low-risk ratio of 1.26 to 2.50. The average annual medical claims costs were also significantly related to number of high-risk classifications. DISCUSSION: This study provides strong statistical evidence that, regardless of age and sex, employees in this sample with positive behaviors cost less in medical claims from 11 of 18 health-related measures.

Adolescent↗