Soluble laminin and arginine-glycine-aspartic acid containing peptides differentially regulate type IV collagenase messenger RNA, activation, and localization in testicular cell culture

Rat testicular cells in culture produce several metalloproteinases including type IV collagenases (Sang et al. Biol Reprod 1990; 43:946-955, 956-964). We have now investigated the regulation of testicular cell type IV collagenase and other metalloprotemases in vitro. Soluble laminin stimulated Sertoli cell type IV collagenase mRNA levels. However, three peptides corresponding to different domains of the laminin molecule (CSRAKQAASIKVASADR, FALRGDNP, CLQDGDVRV) did not influence type IV collagenase mENA levels. Zyniographic analysis of medium collected from these cultures revealed that neither soluble laminin nor any of the peptides influenced 72-Wa type IV collagenase protein levels. However, peptide FALRGDNP resulted in both, a selective increase in two higher molecular-weight metalloprotemnases (83 kDa and 110 Wa and in an activation of the 72-Wa rat type IV collagenase. Interleukin-1, phorbol ester, testosterone, and FSH did not affect collagenase activation, lmmunocytochemical studies demonstrated that the addition of soluble laminin resulted in a redistribution of type IV collagenase from intracellular vesicles to the cell-substrate region beneath the cells. Peptide FALRGDNP induced a change from a vesicular to peripheral plasma membrane type of staining pattern. Zymography of plasma membrane preparations demonstrated triton-soluble gelatinases of 76 Wa, 83 Wa, and 110 Wa and a triton-insoluble gelatinase of 225 Wa, These results indicate that testicular cell type IV collagenase mRNA levels, enzyme activation, and distribution are influenced by laminin and RGD-containing peptides.

Evaluation of a community-based intervention to promote physical activity in youth : lessons from active winners

Purpose To test the effects of a community-based physical activity intervention designed to increase physical activity and to conduct an extensive process evaluation of the intervention. Design Quasi-experimental. Setting Two rural communities in South Carolina. One community received the intervention, and the other served as the comparison. Subjects Public school students who were in fifth grade at the start of the study (558 at baseline) were eligible to participate. A total of 436 students participated over the course of the study. Intervention The intervention included after-school and summer physical activity programs and home, school, and community components designed to increase physical activity in youth. The intervention took place over an 18-month period. Measures. Students reported after-school physical activity at three data collection points (prior to, during, and following the intervention) using the Previous Day Physical Activity Recall (PDPAR). They also completed a questionnaire designed to measure hypothesized psychosocial and environmental determinants of physical activity behavior The process evaluation used meeting records, documentation of program activities, interviews, focus groups, and heart rate monitoring to evaluate the planning and implementation of the intervention. Results There were no significant differences in the physical activity variables and few significant differences in the psychosocial variables between the intervention and comparison groups. The process evaluation indicated that the after-school and summer physical activity component of the intervention was implemented as planned, but because of resource and time limitations, the home, school, and community components were not implemented as planned. Conclusions The intervention did not have a significant effect on physical activity in the target population of children in the intervention community. This outcome is similar to that reported in other studies of community-based physical activity intervention.

Characterization and novel activation of 72-kDa metalloproteinase in retinal interphotoreceptor matrix and Y-79 cell culture medium

Analysis of bovine interphotoreceptor matrix and conditioned medium from human Y-79 retinoblastoma cells by gelatin SDS-PAGE zymography reveals abundant activity of a 72-kDa M(r) gelatinase. The 72-kDa gelatinase from either source is inhibited by EDTA but not aprotinin or NEM, indicating that it is a metalloproteinase (MMP). The 72-kDa MMP is converted to a 62-kDa species with APMA treatment after gelatin sepharose affinity purification typical of previously described gelatinase MMP-2. The latent 72-kDa gelatinase from either bovine IPM or Y-79 media autoactivates without APMA in the presence of calcium and zinc after 72 hr at 37°C, producing a fully active mixture of proteinase species, 50 (48 in Y-79 medium), 38 and 35 kDa in size. The presence of inhibitory activity was examined in both whole bovine IPM and IPM fractions separated by SDS-PAGE. Whole IPM inhibited gelatinolytic activity of autoactivated Y-79-derived MMP in a dose-dependent manner. Inhibitory activities are observed in two protein fractions of 27-42 and 20-25 kDa. Western blots using antibodies to human tissue inhibitor of metalloproteinase 1 and 2 (TIMP-1 and -2) reveal the presence of two TIMP-1-like proteins at 21 and 29 kDa in inhibitory fractions of the bovine IPM. TIMP-2 was not detected in the inhibitory IPM fractions, consistent with the observed autoactivation of bovine IPM 72-kDa gelatinase. Potential roles for this IPM MMP-TIMP system include physiologic remodelling of the neural retina-RPE cell interface and digestion of shed rod outer segment as well as pathological processes such as retinal detachment, PE cell migration, neovascularization and tumor progression. Cultured Y-79 cells appear to be a good model for studying the production and regulation of this proteinase system.

Effects of physical activity intervention in youth : a review

Effects of physical activity interventions in youth: A review. International SportMed Journal. Vol.2 No.5 2001. The purpose of this paper is to review the peer-reviewed literature pertinent to physical activity interventions for children and adolescents. In order to provide a more quantitative conclusion regarding the effectiveness of these interventions, a meta-analytic approach was utilized in which effect sizes (the efficacy of each intervention or magnitude of the intervention effect was expressed as a standardized effect size, which represents the influence of the treatment or intervention on the dependent variable) from each study are pooled to provide a global estimate of effectiveness. A search of the relevant peer-reviewed literature was conducted using several computer-based databases, including MEDLINE, PYSCHLIT, SOCIAL SCIENCE INDEX, and SPORTS DISCUS. Manual searches were also made using the reference lists from recovered articles. Applying strict criteria for quality of design and assessment of physical activity, 10 studies were located, yielding a total of 44 effect sizes. The mean effect size was 0.47 (95% C.I. 0.28 – 0.66) suggesting that interventions have produced moderate increases in physical activity behavior. Effect sizes ranged from –0.61 to 2.5. Interventions focusing on increasing the amount of physical activity performed during regular physical education were more effective than those targeting overall levels of physical activity. Interventions were almost entirely school-based. Accordingly, the development and evaluation of community-based approaches for promoting physical activity among young people, especially older adolescents, remains an urgent priority for future research.

Compliance with physical activity guidelines : prevalence in a population of children and youth

PURPOSE To use objective monitoring of physical activity to determine the percentages of children and youth in a population that met physical activity guidelines. METHODS A total of 375 students in grades 1–12 wore an accelerometer (CSA 7164) for seven consecutive days. Bouts of continuous activity and accumulation of minutes spent in physical activity at various intensities were calculated to determine how many students met three physical activity guidelines. RESULTS Over 90% of students met Healthy People 2010, Objective 22.6 and nearly 70% met the United Kingdom Expert Consensus Group guideline, both of which recommend daily accumulation of moderate physical activity. Less than 3% met Healthy People 2010, Objective 22.7, which calls for bouts of continuous vigorous physical activity. For the United Kingdom Expert Consensus Group guideline, compliance decreased markedly with age, but gender differences were not statistically significant. CONCLUSIONS Prevalence estimates for compliance with national physical activity guidelines varied markedly for the three guidelines examined. Objective monitoring of physical activity in youth appears to be feasible and may provide more accurate prevalence rates than self-report measures.

Correlates of physical activity behavior in rural youth

The purpose of this study was to identify correlates of physical activity behavior in a sample of rural, predominantly African American youth. Three hundred sixty-one fifth-grade students from two rural counties in South Carolina (69% African American, median age = II years) completed a questionnaire designed to measure beliefs and social influences regarding physical activity, physical activity self-efficacy, perceived physical activity habits of family members and friends, and access to exercise and fitness equipment at home. After school physical activity and television watching were assessed using the Previous Day Physical Activity Recall (PDPAR). Students were classified as physically active according to a moderate physical activity standard: two or more 30-min blocks at an intensity of 3 METs (metabolic equivalents) or greater, and a vigorous physical activity standard: one or more 30-min blocks at an intensity of 6 METs or greater According to the moderate physical activity standard, 34.9% of students were classified as low-active. Multivariate analysis revealed age, gender television watching, and exercise equipment at home to be significant correlates of low activity status. According to the vigorous physical activity standard, 32.1 % of the students were classified as low-active. Multivariate analysis revealed age, gender television watching, and self-efficacy with respect to seeking support for physical activity to be significant correlates of low activity status. In summary, gender and the amount of television watching were found to be the most important correlates of physical activity in rural, predominantly African American youth.

Sports participation and health-related behaviors among US youth

Objective To examine the relationship between sports participation and health-related behaviors among high school students. Design Cross-sectional design using data from the 1997 Centers for Disease Control and Prevention Youth Risk Behavior Survey. Participants A nationally representative sample of 14221 US high school students. Main Outcome Measures Prevalence of sports participation among males and females from 3 ethnic groups and its associations with other health behaviors, including diet, tobacco use, alcohol and illegal drug use, sexual activity, violence, and weight loss practices. Results Approximately 70% of male students and 53% of female students reported participating on 1 or more spores teams in school and/or nonschool settings; rates varied substantially by age, sex, and ethnicity. Male sports participants were more likely than male nonparticipants to report fruit and vegetable consumption on the previous day and less likely to report cigarette smelting, cocaine and other illegal drug use, and trying to lose weight. Compared with female nonparticipants, female sports participants were more likely to report consumption of vegetables on the previous day and less likely to report having sexual intercourse in the past 3 months. Among white males and females, several other beneficial health behaviors were associated with sports participation. A few associations with. negative health behaviors were observed in African American and Hispanic subgroups. Conclusion Sports participation is highly prevalent among US high school students, and is associated with numerous positive health behaviors and few negative health behaviors.

Objective measurement of physical activity in youth : current issues, future directions

Second-generation activity monitors have revolutionized the way in which we measure youth physical activity. Use of the monitors avoids the problems associated with self-report methods and allows for the estimation of physical activity patterns over time. This article examines important methodological issues related to the use of activity monitors in children and adolescents.

Secreted products and extracellular matrix from testicular peritubular myoid cells influence androgen-binding protein secretion by Sertoli cells in culture

Metabolic cooperation mediated by secreted factors between Sertoli cells and peritubular myoid cells has been well documented. We have confirmed that factors secreted by peritubular myoid cells modulate androgen-binding protein (ABP) secretion by Sertoli cells and shown further that this can also be achieved with peritubular myoid cell extracellular matrix (ECM). While peritubular myoid cell ECM potentiated the stimulatory effect of dibutyryl cyclic AMP on Sertoli cell ABP secretion, secreted factors did not, suggesting that the two components influence Sertoli cells through distinct mechanisms. We also tested other factors and other cell lines for effects on ABP production by Sertoli cells. The addition of human plasma fibronectin or conditioned medium from the basement membrane-producing Englebreth-Holm- Swarm sarcoma also stimulated ABP secretion by Sertoli cells. Cocultures of epithelial Sertoli cells with the cells of mesenchymal origin, such as testicular peritubular myoid cells, embryonic skin fibroblasts, and bladder smooth muscle cells, significantly stimulated ABP secretion by Sertoli cells, but co-culture with the epithelial-derived Martin-Darby canine kidney cell line had no effect on Sertoli cell-secreted ABP levels. Our data further define the epithelial-mesenchymal cell interaction that exists between Sertoli cells and peritubular myoid cells in the mammalian testis.

Sertoli cells as paracrine modulators of DNA synthesis in rat peritubular myoid cells in culture

To determine whether Sertoli cells influence DNA synthesis by rat peritubular myoid cells in vitro, the effects of Sertoli cells on [3H]thymidine incorporation by peritubular myoid cells in a coculture situation were examined. Incubation of testicular peritubular myoid cells with Sertoli cells in coculture induced a significant increase in [3H]thymidine incorporation by peritubular myoid cells. This indicates a cell-cell cooperation between Sertoli and peritubular myoid cells in the testis in terms of DNA synthesis. Secreted factors from Sertoli cells, as tested in a parabiotic culture situation, also increased [3H]thymidine incorporation by peritubular myoid cells. Moreover, in terms of total cellular protein, cocultures of Sertoli cells and peritubular myoid cells resulted in a significant increase when compared with the monocultures, and this coculture effect substituted for the stimulatory response of serum on peritubular myoid cell monoculture. This study investigated the cooperative role of Sertoli cells and peritubular myoid cells in paracrine regulation of testicular functions.