Eating out, weight and weight gain. A cross-sectional and prospective analysis in the context of the EPIC-PANACEA study.

OBJECTIVE: The aim of this study was to examine the association of body mass index (BMI) and weight gain with eating at restaurants and similar establishments or eating at work among 10 European countries of the European Prospective Investigation into Cancer and Nutrition (EPIC) study. SUBJECTS: This study included a representative sample of 24,310 randomly selected EPIC participants. METHODS: Single 24-h dietary recalls with information on the place of consumption were collected using standardized procedures between 1995 and 2000. Eating at restaurants was defined to include all eating and drinking occasions at restaurants, cafeterias, bars and fast food outlets. Eating at work included all eating and drinking occasions at the workplace. Associations between eating at restaurants or eating at work and BMI or annual weight changes were assessed using sex-specific linear mixed-effects models, controlling for potential confounders. RESULTS: In southern Europe energy intake at restaurants was higher than intake at work, whereas in northern Europe eating at work appeared to contribute more to the mean daily intake than eating at restaurants. Cross-sectionally, eating at restaurants was found to be positively associated with BMI only among men (ß=+0.24, P=0.003). Essentially no association was found between BMI and eating at work among both genders. In a prospective analysis among men, eating at restaurants was found to be positively, albeit nonsignificantly, associated with weight gain (ß=+0.05, P=0.368). No association was detected between energy intake at restaurants and weight changes, controlling for total energy intake. CONCLUSION: Among men, eating at restaurants and similar establishments was associated with higher BMI and possibly weight gain.

A cross-sectional analysis of physical activity and obesity indicators in European participants of the EPIC-PANACEA study.

OBJECTIVES: Cross-sectional data suggest a strong association between low levels of physical activity and obesity. The EPIC-PANACEA (European Prospective Investigation into Cancer-Physical Activity, Nutrition, Alcohol, Cessation of Smoking, Eating out of home And obesity) project was designed to investigate the associations between physical activity and body mass index (BMI) and waist circumference based on individual data collected across nine European countries. METHODS: In the European Prospective Investigation into Cancer and Nutrition (EPIC), 519 931 volunteers were recruited between 1992 and 2000, of whom 405 819 had data on main variables of interest. Height, body weight and waist circumference were measured using standardized procedures. Physical activity was assessed using a validated four-category index reflecting a self-reported usual activity during work and leisure time. The associations between physical activity and BMI and waist circumference were estimated using multilevel mixed effects linear regression models, adjusted for age, total energy intake, smoking status, alcohol consumption and educational level. RESULTS: A total of 125 629 men and 280 190 women with a mean age of 52.9 (s.d. 9.7) and 51.5 (s.d. 10.0) years, respectively were included. The mean BMI was 26.6 kg/m(2) (s.d. 3.6) in men and 25.0 kg/m(2) (s.d. 4.5) in women. Fifty percent of men and 30% of women were categorized as being active or moderately active. A one-category difference in the physical activity index was inversely associated with a difference of 0.18 kg/m(2) in the mean BMI (95% confidence interval, CI, 0.11, 0.24) and 1.04-cm (95% CI 0.82, 1.26) difference in waist circumference in men. The equivalent figures for women were 0.31 kg/m(2) (95% CI 0.23, 0.38) and 0.90 cm (95% CI 0.71, 1.08), respectively. CONCLUSIONS: Physical activity is inversely associated with both BMI and waist circumference across nine European countries. Although we cannot interpret the association causally, our results were observed in a large and diverse cohort independently from many potential confounders.

Biochemical identification of a direct physical interaction between the CD4:p56lck and Ti(TcR)/CD3 complexes.

The CD4 and CD8 antigens function in synergy with the TcR/CD3 complex in the generation of intracellular signals leading to T cell proliferation. The association of the protein-tyrosine kinase p56lck with CD4 and CD8 provides a potential mechanism in the generation of intracellular signals. Several studies have shown that CD4 can co-modulate with TcR/CD3 suggesting that these receptor complexes may associated on the surface of the T cell. Nevertheless, it has proven difficult to formally demonstrate a direct physical interaction between the CD4 and TcR/CD3 complexes using biochemical techniques. In this study, we have used the sensitivity of the in vitro kinase assay to show a direct physical linkage between the CD4:p56lck complex and various CD3 subunits. Immunoprecipitation of CD4 from cell lysates derived from the T lymphoblastoid line HPB-ALL results in the co-purification of p56lck with an additional polypeptide at 20 kDa. Re-precipitation analysis and isoelectric focusing demonstrated that this band corresponds to the CD3 epsilon chain. An alternative approach which involves the labeling of microsomal membranes with [gamma-32P]ATP revealed the presence of CD3 epsilon and zeta chains in anti-CD4 immunoprecipitates. By contrast, we were unable to demonstrate the association of the CD4:p56lck and TcR/CD3 complex in resting peripheral blood lymphocytes. These data indicate that the CD4:p56lck and TcR/CD3 complexes have the ability to form stable complexes on the surface of certain T cell lines.

Molecular analysis of the interaction of p56lck with the CD4 and CD8 antigens.

The CD4 and CD8 antigens on the surface of T cells appear to bind to major histocompatibility complex (MHC) class II and I antigens, respectively. These antigens also synergize with the Ti(TcR)/CD3 complex in the potentiation of T-cell proliferation. Our earlier work demonstrated that the CD4 and CD8 receptors are coupled to a protein-tyrosine kinase termed p56lck from normal and transformed T lymphocytes. The p56lck protein is a member of the src family and its homology with receptor-kinases such as the epidermal growth factor receptor (EGFR) make it an important candidate in signal transduction. In this paper, we show in transfectants that p56lck interacts with the cytoplasmic tail of the CD4 antigen. Murine p56lck can interact across species with the human CD4 receptor. Furthermore, peptide competition studies showed that a specific sequence within the cytoplasmic tail of CD4 interacts with the kinase. Cysteine residues also appear to play key roles in this interaction. Lastly, we show biochemically that the CD4:p56lck complex can physically associate with the epsilon chain of the CD3 complex on HPB-ALL transformed T cells. This interaction may provide a bridge by which events related to ligand binding to Ti(TcR)/CD3 may trigger T cells via the CD4/CD8:p56lck complex.