ABSTRACT
CONTEXT: Challenged with a higher incidence of disease, reduced social support, and less access to physical activity facilities and services, rural older adults may find healthy active living a challenge. Despite these challenges, some rural older adults manage to achieve active lifestyles. PURPOSE: This study investigates the relative importance of 4 extra-individual correlates of physical activity to physical activity achievement in rural seniors. METHODS: Data were drawn from mail questionnaires completed by 454 adults age 65 and over in 7 rural North Carolina counties. FINDINGS: Results from an analysis of covariance indicate that respondents who approached CDC/ACSM recommended levels of physical activity were significantly more likely to report that they lived within walking distance to parks, perceived they had transportation to physical activity areas, had a partner with whom to be active, and felt activity facilities were safe. Next, 7 extra-individual correlates of physical activity were entered into a backward logistic regression. The resultant model predicting physical activity achievement among rural older adults included social support for physical activity, a safe environment for physical activity, and reported ability to walk to a local park. CONCLUSIONS: Interventions designed to provide social support, heighten safety at activity areas and improve park infrastructure may provide opportunities to increase physical activity among seniors.
Subject(s)
Exercise , Rural Population , Aged , Aged, 80 and over , Environment , Female , Humans , Logistic Models , Male , Multivariate Analysis , North Carolina , Physical Fitness , Rural Population/statistics & numerical dataABSTRACT
The cyclin-dependent kinase inhibitor p27 (Kip1) is an important cell cycle regulatory gene in breast cancer, and decreased p27 expression is associated with poor prognosis. Some investigations of its role in mammary development have demonstrated reduced cyclin D1 expression and consequent lack of lobuloalveolar development, but others have found increased cyclin E-Cdk2 activity and increased proliferation balanced by increased apoptosis. It is unclear at present why these apparently divergent results have been obtained. Mice with reduced p27 gene dosage alone do not develop mammary carcinomas but do display substantially shorter tumor latency upon overexpression of erbB2, consistent with a role for p27 as a mammary tumor suppressor gene. In this review we summarize these and other data addressing the role of p27 in normal mammary epithelium and experimental models of mammary carcinogenesis.
Subject(s)
Breast Neoplasms/genetics , Breast Neoplasms/physiopathology , Carcinoma/genetics , Carcinoma/physiopathology , Cell Cycle Proteins/genetics , Cell Cycle Proteins/pharmacology , Cell Cycle , Cell Transformation, Neoplastic , Mammary Glands, Human/growth & development , Tumor Suppressor Proteins/genetics , Tumor Suppressor Proteins/pharmacology , Animals , Apoptosis , Cell Proliferation , Cyclin-Dependent Kinase Inhibitor p27 , Disease Models, Animal , Enzyme Inhibitors , Female , Genes, Tumor Suppressor , Humans , Mammary Glands, Animal/pathology , Mammary Glands, Human/physiology , Mammary Neoplasms, Animal/genetics , Mammary Neoplasms, Animal/physiopathology , Mice , Prognosis , Receptor, ErbB-2/physiologyABSTRACT
Decreased expression of the cyclin-dependent kinase (CDK) inhibitor p27(Kip1) is common in breast cancer and is associated with poor prognosis. p27 is also an important mediator of steroidal regulation of cell cycle progression. We have therefore investigated the role of p27 in mammary epithelial cell proliferation. Examination of the two major functions of p27, assembly of cyclin D1-Cdk4 complexes and inhibition of Cdk2 activity, revealed that cyclin D1-Cdk4 complex formation was not impaired in p27-/- mammary epithelial cells in primary culture. However, cyclin E-Cdk2 activity was increased approximately 3-fold, indicating that the CDK inhibitory function of p27 is important in mammary epithelial cells. Increased epithelial DNA synthesis was observed during pregnancy in p27-/- mammary gland transplants, but this was paralleled by increased apoptosis. During pregnancy and at parturition, development and differentiation of p27+/+ and p27-/- mammary tissue were indistinguishable. These results demonstrate a role for p27 in both the proliferation and survival of mammary epithelial cells. However, the absence of morphological and cellular defects in p27-/- mammary tissue during pregnancy raises the possibility that loss of p27 in breast cancer may not confer an overall growth advantage unless apoptosis is also impaired.
