Abstract : The purpose of this project is to better understand the signal transduction pathways that mediate growth inhibition of breast cancer cells. In fibroblasts, the classical MAPK pathway (Ras/Raf-1/MEK/ERK) mediates the proliferative response by growth factors; while the novel MAPK pathway (Ras/Rac/MEKK1/JNKK1/JNK) may be involved in growth inhibition. A growth factor receptor ErbB-2, which is a critical regulator of the growth and differentiation of breast cells, is overexpressed in 25% of human mammary tumors. Interestingly, its ligand NDF (neu differentiation factor) can either induce the proliferation or differentiation of breast cancer cells. Using mammary carcinoma cells, which proliferate or differentiate upon NDF addition, the respective roles of the two MAPK cascades in controlling cell growth and differentiation are examined. As demonstrated in this report, both the JNK and the ERK cascades are activated at similar kinetics in the differentiative AU565 and the proliferative SKBR3 cells. However, JNK is marginally activated in the proliferative MCF7 cells and not activated in the differentiative MDAMB453 cells. In contrast, ERK is strongly activated by NDF in MCF7 cells, while it is only moderately activated in MDAMB453 cells. Thus, no correlation has been found between the activation profile of the JNK and ERK cascades and the growth responses of the above four mammary carcinoma cells.
Tracking of health-related fitness components in youth ages 9 to 12. Med. Sci. Sports Exerc., Vol. 30, No. 6. pp. 910-916, 1998. Purpose: The purpose of this study was to examine the tracking of multiple health-related fitness components in children from fourth to sixth grade. Methods: A battery of fitness tests was used to measure 414 children (213 boys, 201 girls, mean = 9.48 yr, ± 0.41) from three elementary schools in Southern California. Children were assessed during the fall and spring of each grade. Baseline scores were correlated (Spearman) with each subsequent time point. Results: For boys 3-yr correlations of body mass index (BMI) (0.89), skinfold thickness (0.80), sit-and-reach test (0.67), and the pull-up test (0.66) indicated high levels of tracking. Mile run (0.56), sit-up test (0.46), and waist-to-hip ratio (0.30) tracked moderately. For girls BMI (0.83), sum of skinfolds (0.75), sit-and-reach test (0.72), and the pull-up test (0.63) tracked highly, while mile run (0.42), sit-up test (0.47), and waist-to-hip ratio (0.42) tracked moderately. Conclusions: Results suggest that relative rankings of BMI, skinfold thickness, and sit-and-reach test performance are more likely to track during early adolescence. Measures of cardiovascular fitness, muscular strength, and endurance and fat distribution may be less likely to track into adolescence, possibly because they are more influenced by changes in physical activity or because tracking may be reduced by measurement error.
Measuring Physical Activity and Energy Expenditure Henry J. Montoye, Han C. G. Kemper, Wim H. M. Saris, and Richard A. Washburn Measurement is a cornerstone of every field of science. This is certainly true in exercise science where lamentations about the accuracy of physical activity measures, particularly field measures, are found throughout the literature. Any researcher or clinician who decides to measure physical activity or energy expenditure is immediately confronted by a bewildering array of options, and until now there has been no single place to go for guidance. Measuring Physical Activity and Energy Expenditure will rapidly become recognized as the invaluable guide that has been needed for a long time. The authors, Drs. Montoye, Kemper, Saris, and Washburn, are recognized leaders in the field who have contributed much to the literature. The international composition of the authors enhances the comprehensiveness of coverage. This group contains experts in assessing children, adults, and the elderly; and, collectively, they have experience in all the major measurement methods. Because they have had to develop or select measures for many studies, they know what kinds of information will be useful to other researchers. Part I contains two brief chapters that introduce the issues and provide an overview of the principles and methods of laboratory measures of energy expenditure. Part II is much more extensive and reviews field methods of assessment. There is a chapter devoted to each category of measures: doubly labeled water, behavioral observations, diaries, questionnaires and interviews, and motion sensors. One of the chapters surveys methods of estimating energy expenditure from physiologic responses to activity, and there is a brief conclusions chapter. There are 16 appendices that include reproductions of many data collection forms, which will be a great convenience to researchers. The outstanding feature of the book is the impressive use of tables to summarize studies and their results. The tables go a long way toward meeting the authors' stated goal of making the book practical. Every chapter has tables that present characteristics of measures, along with reliability and validity data, that allow comparisons across measures. These tables contain enough specific data to be used by themselves to select the best measures for a study. There is even a table in the last chapter that compares relevant characteristics of each category of measure. The text complements the tables and contains useful information on advantages and disadvantages, historical perspectives, and implementing and interpreting the measures and their results. The book is concise (less than 200 pages, including appendices), presents the state-of-the-science in an authoritative manner, and is well written. It makes a unique contribution to the entire field of exercise science, and it will be widely used This volume provides valuable assistance in choosing among existing assessment instruments, but it does not instruct us enough on how to improve on what is now available. This is a minor failing, but more of the author's insights and specific suggestions may have inspired some improved measures. While new and better measures are being developed and evaluated,Measuring Physical Activity and Energy Expenditure should improve the quality of physical activity research by helping researchers select the best measures for their studies.
No abstract is provided for this article.
Social Support is an important psychosocial mediator of physical activity, particularly in adolescents. However, a valid and reliable instrument to measure this mediator in Brazilian adolescents is not available. The purpose of this study was to evaluate psychometrically a Brazilian-Portuguese version of the Social Support for Exercise Behavior Scale with adolescents. Participants were 540 high-school students (57.5% boys) with ages ranging from 14 to 17 years. A sub-sample of 64 participants was randomly selected to assess one week test-retest reliability by intraclass correlation. Internal consistency reliability was assessed by Cronbach's alpha. Concurrent criterion validity was assessed by Spearman rank-order correlation between the social support scales and minutes per week of moderate to vigorous physical activity (MVPA), minutes of structured activities per week and minutes per week of walking for transport. Cronbach's alpha for subscales ranged from 0.78 to 0.81 and Intraclass coefficients ranged from 0.61 to 0.81. All social support subscales correlated significantly with at least two physical activity measures supporting validity. These social support scales showed adequate reliability and moderate validity with Brazilian adolescents. Objective physical activity measures are needed to evaluate further the validity.
