Project ASPIRE: an Interactive, Multimedia Smoking Prevention and Cessation curriculum for culturally diverse high school students

A Smoking Prevention Interactive Experience (ASPIRE) is an innovative, computer-based smoking prevention and cessation intervention delivered to a culturally diverse population of high school students. Founded in the Transtheoretical Model of Change, five main and two "booster" sessions comprise the interactive intervention. Here we describe the intervention and the baseline characteristics from our study sample of 1,574 10th graders from 16 high schools in Houston, Texas. Environmental and behavioral smoking risk factors were assessed, and the two intervention groups were comparable with respect to most measured variables. The intervention program holds considerable promise in its ability to reduce smoking among teens.

Impact of A Smoking Prevention Interactive Experience (ASPIRE), an interactive, multimedia smoking prevention and cessation curriculum for culturally diverse high-school students

Few studies have examined the long-term efficacy of computer-based smoking prevention and cessation programs. We analyzed the long-term impact of A Smoking Prevention Interactive Experience (ASPIRE), a theoretically sound computer-based smoking prevention and cessation curriculum for high school students. Sixteen predominantly minority, inner-city high schools were randomly assigned to receive the ASPIRE curriculum or standard care (receipt of the National Cancer Institute's Clearing the Air self-help booklet). A total of 1160 students, 1098 of whom were nonsmokers and 62 smokers at baseline, were included. At 18-month follow-up, among baseline nonsmokers, smoking initiation rates were significantly lower in the ASPIRE condition (1.9% vs. 5.8%, p < .05). Students receiving ASPIRE also demonstrated significantly higher decisional balance against smoking and decreased temptations to smoke. Differences between groups in self-efficacy and resistance skills were not significant. There was a nonsignificant trend toward improved smoking cessation with ASPIRE, but low recruitment of smokers precluded conclusions with respect to cessation. ASPIRE demonstrated the potential for an interactive multimedia program to promote smoking prevention. Further studies are required to determine ASPIRE's effects on cessation.

Molecular and functional analysis of glutamine uptake in human hepatoma and liver-derived cells

Human hepatoma cells take up glutamine at rates severalfold faster than the system N-mediated transport rates observed in normal human hepatocytes. Amino acid inhibition, kinetic, Northern blotting, RT-PCR, and restriction enzyme analyses collectively identified the transporter responsible in six human hepatoma cell lines as amino acid transporter B(0) (ATB(0)), the human ortholog of rodent ASCT2. The majority of glutamine uptake in liver fibroblasts and an immortalized human liver epithelial cell line (THLE-5B) was also mediated by ATB(0). The 2.9-kb ATB(0) mRNA was equally expressed in all cell lines, whereas expression of the system A transporters ATA2 and ATA3 was variable. In contrast, the system N isoforms (SN1 and SN2) were expressed only in well-differentiated hepatomas. ATB(0) mRNA was also expressed in cirrhotic liver and adult and pediatric liver cancer biopsies but was not detectable in isolated human hepatocytes or fetal liver. Although the growth of all hepatomas was glutamine dependent, competitive inhibition of ATB(0)-mediated glutamine uptake blocked proliferation only in poorly differentiated cells lacking SN1 or SN2 expression and exhibiting low glutamine synthetase mRNA levels.

Effect of radial artery harvesting on tissue perfusion and function of the hand

This study was designed to measure the degree to which hand and forearm blood flow is reduced following harvesting of the radial artery in myocardial revascularization surgery and determine whether there is an effect on hand function. Twenty patients who had the radial artery used for myocardial revascularization underwent bilateral blood flow assessment of hands and forearms using Technetium-99m human serum albumin and clinical evaluation of hand function. Mean tissue perfusion in ml/100 ml/min +/- SD was as follows: donor hand 21.9 +/- 5.6, non-donor hand 25.5 +/- 6.1 (P = 0.00043), donor arm (hand and forearm) 17.5 +/- 3.7 and non-donor arm (hand and forearm) 21 +/- 5.1 (P = 0.000681). No clinical evidence of hand claudication was detected. This study suggests that removal of the radial artery reduces the tissue perfusion of the hand and forearm but does not affect hand function in the short term. The use of radial artery grafts in patients at risk of developing peripheral vascular disease should be carefully considered

Nicotine dependence, withdrawal symptoms, and adolescents' readiness to quit smoking

The purpose of this study was to characterize nicotine dependence and nicotine withdrawal symptoms among adolescent smokers and to investigate associations between these key factors and adolescents' readiness to quit smoking. A total of 5624 high school students participated in a school-based survey. Of 1111 adolescents who were current or former smokers, the following stage-of-change distribution for smoking cessation was observed: precontemplation, 52.5%; contemplation, 16.0%; preparation, 7.5%; action, 13.2%; and maintenance, 10.8%. Among current smokers, 18.1% were substantially dependent on nicotine, 45.2% had moderate dependence, and 36.7% had no dependence. Higher proportions of current smokers than successful quitters reported withdrawal symptoms with their most recent quit attempts. Precontemplators exhibited significantly higher mean nicotine dependence scores than did students in the contemplation or preparation stages (F(2,837) = 12.03; p < 0.0001). A similar trend was observed for withdrawal-symptom scores across the stages of change. The nicotine dependence and withdrawal-symptom scores were significantly correlated (r = 0.44, p < 0.001). Nicotine dependence and nicotine withdrawal appear to interfere with adolescents' abilities and readiness to quit smoking, suggesting a potential role for nicotine replacement therapy in the treatment of tobacco use and dependence among adolescents.

Tumor-influenced amino acid transport activities in zonal-enriched hepatocyte populations

Cancer influences hepatic amino acid metabolism in the host. To further investigate this relationship, the effects of an implanted fibrosarcoma on specific amino acid transport activities were measured in periportal (PP)- and perivenous (PV)-enriched rat hepatocyte populations. Na(+)-dependent glutamate transport rates were eightfold higher in PV than in PP preparations but were relatively unaffected during tumor growth. System N-mediated glutamine uptake was 75% higher in PV than in PP preparations and was stimulated up to twofold in both regions by tumor burdens of 9 +/- 4% of carcass weight compared with hepatocytes from pair-fed control animals. Excessive tumor burdens (26 +/- 7%) resulted in hypophagia, loss of PV-enriched system N activities, and reduced transporter stimulation. Conversely, saturable arginine uptake was enhanced fourfold in PP preparations and was induced twofold only after excessive tumor burden. These data suggest that hepatic amino acid transporters are differentially influenced by cancer in a spatial and temporal manner, and they represent the first report of reciprocal zonal enrichment of system N and saturable arginine uptake in the mammalian liver.

Combinatorial library of serine and cysteine protease inhibitors that interact with both the S and S' binding sites

A combinatorial library of 400 inhibitors has been synthesized and screened against several serine and cysteine proteases including plasmin, cathepsin B, and papain. The inhibitors are based upon a cyclohexanone nucleus and are designed to probe binding interactions in the S2 and S2' binding sites. This methodology has led to the discovery of inhibitor 15A, which incorporates Trp at both the P2 and P2' positions and has an inhibition constant against plasmin of 5 microM. Data from screening of the library shows that plasmin has a strong specificity for Trp at the S2 subsite and prefers to bind hydrophobic and aromatic amino acids such as Ile, Phe, Trp, and Tyr at the S2' subsite. In contrast, the S2' subsites of cathepsin B and papain do not show a strong preference for any particular amino acid.

Protein kinase C regulates nutrient uptake and growth in hepatoma cells

BACKGROUND

Human hepatoma cells extract glutamine at rates severalfold greater than normal hepatocytes through a high-affinity transporter encoded by the ATB0 gene, which contains two putative phosphorylation sites for protein kinase C (PKC). The studies presented here were undertaken to determine whether System B0-mediated glutamine uptake regulates hepatoma growth and whether PKC regulates the activity of this transporter.

METHODS

SK-Hep cells were treated with the PKC activator phorbol 12-myristate 13-acetate (PMA) and the initial-rate transport of glutamine and other nutrients measured at specific times thereafter. Growth rates were monitored during culture +/- PMA or an excess of system B0 substrates relative to glutamine.

RESULTS

PMA treatment exerted a rapid (half-life approximately 15 minutes) concentration-dependent inhibition of glutamine uptake rates to 50% of control values via a posttranslational mechanism that decreased transporter maximum velocity. This effect persisted after 24 hours and was abrogated by the PKC inhibitor staurosporine. PMA also significantly decreased amino acid transport System y+ and System L activities but no System A. Chronic treatment with PMA (PKC depletion) inhibited SK-Hep growth, as did attenuation of System B0-mediated glutamine uptake with other B0 substrates.

CONCLUSIONS

System B0-mediated glutamine uptake regulates hepatoma cell growth, whereas PKC influences both processes.