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Biomedical subjects

S A French

Publications and source records attributed to S A French.

At least 37 records · Page 2Linked to original sources
PubMed2000

Ca(2+) activation of heart mitochondrial oxidative phosphorylation: role of the F(0)/F(1)-ATPase.

Ca(2+) has been postulated as a cytosolic second messenger in the regulation of cardiac oxidative phosphorylation. This hypothesis draws support from the well-known effects of Ca(2+) on muscle activity, which is stimulated in parallel with the Ca(2+)-sensitive dehydrogenases (CaDH). The effects of Ca(2+) on oxidative phosphorylation were further investigated in isolated porcine heart mitochondria at the level of metabolic driving force (NADH or Deltapsi) and ATP production rates (flow). The resulting force-flow (F-F) relationships permitted the analysis of Ca(2+) effects on several putative control points within oxidative phosphorylation, simultaneously. The F-F relationships resulting from additions of carbon substrates alone provided a model of pure CaDH activation. Comparing this curve with variable Ca(2+) concentration ([Ca(2+)]) effects revealed an approximate twofold higher ATP production rate than could be explained by a simple increase in NADH or Deltapsi via CaDH activation. The half-maximal effect of Ca(2+ )at state 3 was 157 nM and was completely inhibited by ruthenium red (1 microM), indicating matrix dependence of the Ca(2+) effect. Arsenate was used as a probe to differentiate between F(0)/F(1)-ATPase and adenylate translocase activity by a futile recycling of ADP-arsenate within the matrix, catalyzed by the F(0)/F(1)-ATPase. Ca(2+) increased the ADP arsenylation rate more than twofold, suggesting a direct effect on the F(0)/F(1)-ATPase. These results suggest that Ca(2+) activates cardiac aerobic respiration at the level of both the CaDH and F(0)/F(1)-ATPase. This type of parallel control of both intermediary metabolism and ATP synthesis may provide a mechanism of altering ATP production rates with minimal changes in the high-energy intermediates as observed in vivo.

Adenosine Triphosphate↗
PubMed1999

Prospective study of intentionality of weight loss and mortality in older women: the Iowa Women's Health Study.

Several epidemiologic investigations have suggested that weight loss is associated with increased mortality risk but have not examined whether the weight loss was intentional or unintentional. The authors examined whether the association between weight loss and mortality differs by whether the weight loss was intentional or unintentional as part of the Iowa Women's Health Study, a prospective cohort study of health risk factors in postmenopausal women. Women aged 55-69 years completed questions about intentional and unintentional weight losses since age 18 years via mail survey in 1992 and were followed through 1995. One or more intentional weight loss episodes of 20 or more pounds (> or =9.1 kg) during adulthood was not significantly associated with higher total or cardiovascular disease mortality risk compared with never losing > or =20 pounds. One or more unintentional weight loss episodes of 20 or more pounds was associated with a 26-57% higher total mortality risk and a 51-114% higher cardiovascular disease mortality risk, compared with never losing 20 or more pounds. Associations between unintentional weight loss and increased mortality risk were confined mostly to women with prevalent disease, hypertension, or diabetes. Patterns of association did not vary by overweight status. These findings suggest that the association between weight loss and increased mortality risk observed in epidemiologic studies may be due to unintentional weight loss that reflects existing disease and not due to intentional weight loss.

Aged↗
PubMed1999

Weight-related attitudes and behaviors in fourth grade American Indian children.

OBJECTIVE: American Indian children have a high prevalence of obesity, yet little is known about weight-related attitudes and the prevalence of dieting in this population. This study assessed weight concerns, body size perceptions, weight reduction attempts, and weight loss methods in fourth grade American Indian children. RESEARCH METHODS AND PROCEDURES: Participants (n = 304) attended one of eight schools in the Pathways Feasibility Study. Question and answer choices were read to children by trained staff, and children marked their own answers. RESULTS: Thirty-eight percent of the children reported that they had tried to lose weight. The most common strategy for weight reduction was exercising more. Girls were more likely than boys to be dissatisfied with their body size (48% of girls vs. 34% of boys desired a slimmer body size; 22% of girls vs. 15% of boys desired a larger body size; p<0.001). Children who had tried to lose weight were more likely to indicate that the size they most desired and the most healthy size were smaller than their perceived size (p<0.001). Children who reported trying to lose weight were also more likely to want to be skinnier and to be unhappy about their weight than were children who did not report trying to lose weight (p<0.001 for both). DISCUSSION: We conclude that weight loss attempts and weight-related concerns are prevalent in American Indian children at a young age.

Arizona↗
PubMed1999

Weight control behaviors among adult men and women: cause for concern?

OBJECTIVES: To examine gender differences in weight control behaviors; their duration and the consistency of their use over a 3-year period; and variations of these behaviors by body mass index (BMI). RESEARCH METHODS AND PROCEDURES: The study population included 714 women and 229 men participating in a community-based weight gain prevention program who completed surveys about their weight control behaviors annually for 3 years. General dieting behaviors (e.g., current, regular, and past dieting), dietary restraint (using Restrained Eating subscale of the Three-Factor Eating Questionnaire), and specific weight control practices (e.g., increasing exercise, skipping meals, and taking laxatives) were assessed. RESULTS: Women were more likely than men to report weight control behaviors, with particularly strong associations found between gender and "history of dieting" (odds ratio = 8.1) and "participation in an organized weight loss program" (odds ratio = 11.7). Among both genders, exercise was the most frequently reported specific weight loss practice (66% of women and 53% of men), followed by decreasing fat intake (62% of women and 48% of men). The use of at least one unhealthy weight control behavior over the past year was reported by 22% of the women and 17% of the men. Gender differences were not found for duration of use of most of the specific weight control practices over the past year, or for consistency of general dieting behaviors and dietary restraint over time. Although both gender and BMI were strongly associated with dieting behaviors, interactions between gender and BMI on prevalence rates of dieting were not significant. DISCUSSION: Although weight control behaviors were more prevalent among women than men, in general, large gender differences were not found in the types of behaviors used and the duration and consistency of their use. The high percentages of adults using healthy methods of weight control was encouraging. However, there is still cause for concern, in that unhealthy weight control practices were also reported by a significant percentage of the population.

Adult↗
PubMed1999

Mistreatment due to weight: prevalence and sources of perceived mistreatment in women and men.

OBJECTIVE: Previous research has documented prejudicial attitudes and discrimination against overweight people. Yet the extent to which overweight people themselves perceive that they have been mistreated because of their weight has not been carefully studied. The purpose of this study was to examine the prevalence of perceived mistreatment due to weight and sources of perceived mistreatment. METHODS AND PROCEDURES: A non-clinical sample of healthy adults (187 men and 800 women) enrolled in a weight gain prevention program comprised the study population. A self-administered questionnaire was used to measure perceived mistreatment due to weight. RESULTS: Overall, 22% of women and 17% of men reported weight-related mistreatment. The most commonly reported sources of mistreatment among women were strangers (12.5%) and a spouse or loved one (11.9%). Men were most likely to report mistreatment by a spouse or loved one (10.2%) and friends (7.5%). Somewhat surprisingly, sex differences in perceived weight-related mistreatment were significant only for stranger as the source. Perceived weight-related mistreatment was positively associated with body mass index (BMI) (r = 0.39, p<0.0001). Reported mistreatment was nearly ten times as pervalent among individuals in the highest quartile of the BMI distribution (42.5%) than among those in the lowest BMI quartile (5.7%), but was significantly greater than zero in all but the very lean. DISCUSSION: Perceived mistreatment due to weight is a common experience and is not restricted to the morbidly obese. Results are discussed in light of the sociocultural value for thinness.

Adult↗
PubMed1999

Stage of change as a predictor of success in weight control in adult women.

Weight change over 3 years was examined in a large and heterogeneous sample of women as a function of stage of change for weight control. Women were classified into Precontemplation, Contemplation, Preparation, and Action stages on the basis of reports of current and past weight control behaviors and future intentions. Stage of change did not predict success in weight control. Mean weight changes over 3 years were 1.1 kg, 1.0 kg, 2.1 kg, and 2.3 kg for Precontemplation, Contemplation, Preparation, and Action stages, respectively. The findings call into question the generality of the stages-of-change classification system across behavioral domains.

Adult↗
PubMed1999

Is dieting good for you?: Prevalence, duration and associated weight and behaviour changes for specific weight loss strategies over four years in US adults.

OBJECTIVES: This present study describes weight control strategies used by a heterogeneous sample of US adults and their associations with weight and behaviour change over time. DESIGN: A prospective cohort study. PARTICIPANTS: Participants for this study were 1120 US adults recruited from the community who enrolled in a three-year intervention study to examine methods for preventing age-related weight gain. MEASURES: Measured body weight and self-reported behaviours related to body weight (dieting practices, dietary intake and physical activity) were completed annually for four years. RESULTS: Over 70% reported using each of the following dieting strategies at least once in four years: increase exercise (82.2%); decrease fat intake (78.7%); reduce food amount (78.2%); and reduce calories (73.2%). Cumulative duration of use of these behaviours was brief (for example, even the most common behaviours were used only 20% of the time). Global reports of dieting were not predictive of weight change over time. However, a dose-response relationship was observed between reported duration of use of several specific weight loss strategies over the four years and change in behaviours and weight gain. CONCLUSIONS: These findings suggest that public health recommendations for weight control may need to place greater emphasis on persistence of weight control behaviours.

Adult↗
PubMed1999

Television viewing, physical inactivity and obesity.

This study examined the relationship between TV viewing and three year change in BMI among a community-based sample of 176 men, 428 high-income women and 277 low-income women who were aged 20-45 years at baseline. Cross-sectionally, TV viewing was positively associated with BMI among women, but not among men. This relationship was strongest among low-income women, with only a marginal relationship among high-income women. There were no significant relationships between change in BMI and number of hours of TV viewing at baseline, average number of hours of TV viewing over the three year follow-up, or change in number of hours of TV viewing from baseline to three years. These findings suggest the link between obesity and TV viewing is complex, and that TV viewing may not be the simple marker of sedentariness we may have hoped.

Adult↗
PubMed1999

Prevalence and correlates of binge eating in a nonclinical sample of women enrolled in a weight gain prevention program.

OBJECTIVES: The aims of the present study were to examine the prevalence and correlates of binge eating in a nonclinical sample of women and to examine whether associations differed by overweight status. DESIGN: Cross-sectional comparison of women based on self-reported binge eating status (large amount of food eaten and feelings of lack of control during these eating episodes) and overweight status (measured body weight: overweight defined as body mass index (BMI) > or = 27.3 kg/m2). PARTICIPANTS: Subjects were 817 women aged 20-45y from the community who enrolled in a three year prospective intervention study to examine methods for preventing age-related weight gain. MEASURES: Body weight was measured at baseline and three-year follow-up. Self-report measures of binge eating, dieting practices, eating and exercise behaviours, depression, self-esteem and stressful life events were collected at the three-year follow-up. RESULTS: The prevalence of binge eating in the past six months was 9% among normal weight women and 21% among overweight women. The frequency of binge eating was low (> 50% of binge eaters binged less than once per week) and did not significantly differ by body weight status. Compared to non-binge eaters, binge eaters reported more dieting practices, more extreme attitudes about weight and shape, and higher levels of depression and stressful life events. Binge eating was not related to habitual eating and exercise behaviours. In multivariate models, weight/shape importance (odds ratio (OR) = 3.33; 95% confidence intervals (95% CI) = 2.10, 5.29), depression (OR = 1.73; 95% CI = 1.07, 2.79) and history of intentional weight loss episodes (OR = 1.68; 95% CI = 1.03, 1.13) were independently associated with increased odds of binge eating. CONCLUSIONS: Binge eating is about twice as prevalent among overweight women, compared to normal weight women, in a nonclinical sample, but has similar correlates (that is, dieting, depression, weight/shape preoccupation). Prospective research is needed to determine whether there are causal associations between binge eating, depression, dieting and weight gain.

Adult↗
PubMed1999

Development of a questionnaire to assess knowledge, attitudes, and behaviors in American Indian children.

One aim of the Pathways study is to improve the knowledge, attitudes, and behaviors of American Indian children in grades 3-5 regarding physical activity and diet in. This article describes the development of a culturally sensitive, age-appropriate questionnaire to assess these variables. The questionnaire was designed to be administered in the classroom in two 30-min sessions. Questions were developed to assess 4 key areas: physical activity, diet, weight-related attitudes, and cultural identity. Potential questions were written after review of relevant literature and existing questionnaires. Numerous and extensive revisions were made in response to input from structured, semistructured, and informal data collection. Questions were pretested in 32 children in grades 3-5 by using semistructured interviews. Test-retest reliability and the internal consistency of scales were examined in 371 fourth-grade children and subsequently in 145 fourth-grade children. Questions were reviewed by American Indians from the communities involved in the Pathways study several times during the developmental process. The process described here serves as one model for the development of a culturally appropriate tool to assess knowledge, attitudes, and behaviors in American Indian children.

Asian People↗
PubMed1999

Comparison of commercial Amies transport systems with in-house Amies medium for recovery of Neisseria gonorrhoeae.

Microbiologists are still encumbered by the variable performance of Amies charcoal transport medium in recovery of Neisseria gonorrhoeae. The objective of this study was to evaluate and select a good quality commercial system to replace our in-house preparation. We adsorbed 0.1 ml of a suspension from 30 gonococcal isolates onto each swab type and replaced the swab into the transport medium. We plated the swabs to New York City medium at 0, 24, 48, 72, and 96 h. We compared the survival of each isolate in the commercial Amies transport systems with that in our in-house Amies transport medium. The best recovery was observed with Copan transport systems. Some systems are inadequate and unacceptable for culture of gonococci.

Culture Media↗
PubMed1999

Preventing weight gain in adults: the pound of prevention study.

OBJECTIVES: This study examined whether weight gain with age could be prevented through the use of a low-intensity intervention. METHODS: Participants, 228 men and 998 women recruited from diverse sources, were randomized to one of the following groups: (1) no-contact control, (2) education through monthly newsletters, or (3) education plus incentives for participation. All participants were weighed and completed questionnaires about behaviors and attitudes related to weight at baseline and annually for 3 years thereafter. RESULTS: Individuals in intervention groups reported favorable changes over time in frequency of weighting and healthy dieting practices relative to those in the control group. These behavior changes were in turn related to a reduced rate of weight gain over time. However, weight gain over 3 years did not differ significantly by treatment group. CONCLUSIONS: This low-intensity educational approach to weight gain prevention sustained interest over a lengthy time period and was associated positively with behavior change, but it was not strong enough to significantly reduce weight gain with age.

Adult↗
PubMed1998

Agreement between survey and interview measures of weight control practices in adolescents.

OBJECTIVE: The present study examined agreement between survey and interview measures of weight control practices in a nonclinical sample of adolescents. METHOD: Surveys were administered in three school health classes. Clinical interviews were conducted in a student subsample (N = 43). RESULTS: Survey-based prevalences for eating behaviors in the past month were: trying to lose weight, 44%; binge eating, 41%; vomiting, 4.7%; laxative use, 0%; and fasting, 14%. Interview-based prevalences were 30%, 11.6%, 0%, 0% and 0%, respectively. Sensitivity was high for all behaviors assessed. However, positive predictive values were low. DISCUSSION: Surveys may be useful as preliminary screening tools for prevention programs, but may yield inflated estimates of unhealthy weight control practices in nonclinical adolescent populations. Research is needed to examine whether adolescents overreport weight control practices on surveys or whether they are less willing to disclose such practices in a private interview.

Adolescent↗
PubMed1998

Correction for inner filter effects in turbid samples: fluorescence assays of mitochondrial NADH.

Fluorescent determinations of NADH in porcine heart mitochondria were subject to significant errors caused by alterations in inner filter effects during numerous metabolic perturbations. These inner filter effects were primarily associated with changes in mitochondrial volume and accompanying light scattering. The observed effects were detected in a standard commercial fluorometer with emission orthogonal to the excitation light path and, to a lesser extent, in a light path geometry detecting only the surface fluorescence. A method was developed to detect and correct for inner filter effects on mitochondrial NADH fluorescence measurements that were independent of the optical path geometry using an internal fluorescent standard and linear least-squares spectral analysis. A simple linear correction with the inner fluorescence reference was found to adequately correct for inner filter effects. This approach may be useful for other fluorescence probes in isolated mitochondria or other light-scattering media.

Adenosine Diphosphate↗
PubMed1998

Epidemic obesity in the United States: are fast foods and television viewing contributing?

OBJECTIVES: This study examined the association between TV viewing, fast food eating, and body mass index. METHODS: Associations between hours of TV viewing, frequency of eating at fast food restaurants, body mass index, and behaviors were assessed cross sectionally and longitudinally over 1 year in 1059 men and women. RESULTS: Fast food meals and TV viewing hours were positively associated with energy intake and body mass index in women but not in men. TV viewing predicted weight gain in high-income women. CONCLUSIONS: Secular increases in fast food availability and access to televised entertainment may contribute to increasing obesity rates in the United States.

Adult↗