Barriers and Facilitators of Adolescent Health in Rural Kenya.

PURPOSE: The purpose of this research was to identify perceived barriers and facilitators of health from the perspective of rural Kenyan adolescents and to characterize the cultural context that shapes these barriers and facilitators. DESIGN: Following a semistructured interview guide, qualitative focus group interviews were conducted at day schools with 64 upper-primary and secondary students in rural central Kenya. Participants provided written parental consent and individual assent for study participation. RESULTS: Findings were organized into seven categories (individual, family, peer, school, community, institutional, and cultural) according to a social-ecological framework to highlight the multiple social and environmental contexts that shape health the experiences rural Kenyan youth. CONCLUSIONS: The prevalence and complexity of factors that shape the health experiences of young people in rural Kenya displayed in these findings adds context to the importance of utilizing multipronged approaches to improving adolescent health by focusing on the social contextual determinants of health behaviors and outcomes.

Estimation of the impact on children's health of environmental tobacco smoke in England and Wales.

In this paper, the population attributable risk (PAR), a measure of the excess risk of disease associated with a risk factor, is calculated for some of the common adverse health effects that have been associated with exposure of children to environmental tobacco smoke (ETS): childhood lower respiratory illness, chronic middle ear disease, asthma and sudden infant death syndrome (SIDS). Published data on both risk estimates and the percentage of children exposed to ETS in the home (prevalence of ETS) have been utilised. The percentage of childhood lower respiratory illness and middle ear disease typically attributable to ETS from either parent smoking ranged from 9% for asthma prevalence and for referral for glue ear, to 25% for hospital admission for lower respiratory illness. Where data were available to calculate PARs separately for mother only smoking and father only smoking, the PARs were generally larger for mothers only smoking, due mainly to higher odds ratios for mothers only smoking. The PAR for SIDS attributable to ETS from mother only smoking was 11%. Although based on a small number of studies, the PAR for SIDS attributable to smoking of fathers only was similar to that attributable to the smoking of mothers only, largely due to the higher prevalence of households where only the father smokes. This study has shown that the impact of ETS on childhood illness can be considerable, emphasising the importance of the need to develop effective strategies for reducing the risk of ETS exposure in the home and elsewhere.

Reducing domestic exposure to environmental tobacco smoke: a review of attitudes and behaviours.

This paper reviews research on attitudes and behaviours towards environmental tobacco smoke (ETS), with a special focus on child health and the indoor environment. Research needs and ways forward to encourage reductions in domestic ETS levels are discussed. Published material was identified through online literature searches (Medline, Toxline, Cancerlit, Biosis, Embase, Enviroline, Sociological Abstracts, Social Science Citation Index, Academic Index and Psychinfo). The literature search strategy employed search terms such as "passive smoking" or "environmental tobacco smoke" with "attitude" or "awareness" and other synonyms. Additional publications were identified by citation chasing and expert advice. Focusing on the UK, studies that provided survey-derived data about attitudes and behaviours in relation to ETS exposure in the indoor environment were selected for review. Published studies from other countries were also included when they provided information pertinent to this review. Most people are aware of the health risks associated with ETS exposure, and there is a high level of support for smoking restrictions in public places to protect non-smokers from ETS. However, although there is concern among both non-smoking and smoking parents about children and second-hand smoke, many people allow children to be exposed to ETS in the home. The review suggests that traditional health promotion campaigns have had only limited success in encouraging ETS risk reduction measures in the home. Because ETS is a public health priority, particularly in relation to child health, the barriers to the uptake of such measures need to be explored in detail to inform the future promotion of reductions in domestic levels of ETS.

Benzene in the environment: an assessment of the potential risks to the health of the population.

OBJECTIVES: Benzene has long been recognised as a carcinogen and recent concern has centred on the effects of continuous exposure to low concentrations of benzene both occupationally and environmentally. This paper presents an overview of the current knowledge about human exposure to benzene in the United Kingdom population based on recently published data, summarises the known human health effects, and uses this information to provide a risk evaluation for sections of the general United Kingdom population. METHOD: Given the minor contribution that non-inhalation sources make to the overall daily intake of benzene to humans, only exposure from inhalation has been considered when estimating the daily exposure of the general population to benzene. Exposure of adults, children, and infants to benzene has been estimated for different exposure scenarios with time-activity patterns and inhalation and absorption rates in conjunction with measured benzene concentrations for a range of relevant microenvironments. Exposures during refuelling and driving, as well as the contribution of active and passive tobacco smoke, have been considered as part of the characterisation of risk of the general population. RESULTS: Infants (<1 years old), the average child (11 years old), and non-occupationally exposed adults, receive average daily doses in the range of 15-26, 29-50, and 75-522 microg of benzene, respectively, which correspond to average ranges to benzene in air of 3.40-5.76 microg/m(3), 3.37-5.67 microg/m(3), and 3.7-41 microg/m(3) for infants, children, and adults, respectively. Infants and children exposed to environmental tobacco smoke have concentrations of exposure to benzene comparable with those of an adult passive smoker. This is a significant source of exposure as a 1995 United Kingdom survey has shown that 47% of children aged 2-15 years live in households where at least one person smokes. The consequence of exposure to benzene in infants is more significant than for children or adults owing to their lower body weight, resulting in a higher daily intake for infants compared with children or non-smoking adults. A worst case scenario for exposure to benzene in the general population is that of an urban smoker who works adjacent to a busy road for 8 hours/day-for example, a maintenance worker-who can receive a mean daily exposure of about 820 microg (equal to an estimated exposure of 41 microg/m(3)). The major health risk associated with low concentrations of exposure to benzene has been shown to be leukaemia, in particular acute non-lymphocytic leukaemia. The lowest concentration of exposure at which an increased incidence of acute non-lymphocytic leukaemia among occupationally exposed workers has been reliably detected, has been estimated to be in the range of 32-80 mg/m(3). Although some studies have suggested that effects may occur at lower concentrations, clear estimates of risk have not been determined, partly because of the inadequacy of exposure data and the few cases. CONCLUSIONS: Overall the evidence from human studies suggests that any risk of leukaemia at concentrations of exposure in the general population of 3.7-42 microg/m(3)-that is at concentrations three orders of magnitude less than the occupational lowest observed effect level-is likely to be exceedingly small and probably not detectable with current methods. This is also likely to be true for infants and children who may be exposed continuously to concentrations of 3.4-5.7 microg/m(3). As yet there is no evidence to suggest that continuous exposures to these environmental concentrations of benzene manifest as any other adverse health effect.

Decrease in susceptibility toward induction of apoptosis and alteration in G1 checkpoint function as determinants of resistance of human lung cancer cells against the antisignaling drug UCN-01 (7-Hydroxystaurosporine).

7-Hydroxystaurosporine (UCN-01) is a protein kinase inhibitor that is under development as an anticancer agent in the United States and Japan. Long-term exposure of human A549 non-small cell lung cancer cells to UCN-01 furnished cells (A549/UCN) with acquired resistance against UCN-01. In this study, the sensitivity of these cells toward the growth-arresting properties of certain conventional cytotoxic agents was explored. Cells were not cross-resistant against adriamycin, Taxol, staurosporine, and UCN-02, but they displayed 14- and 4.4-fold resistance against cisplatin and mitomycin C, respectively. Previous studies on the mechanism(s) of action of UCN-01 suggest that induction of apoptosis and G1 phase accumulation are important for its anticancer activity; therefore, we compared induction of apoptosis and cell cycle distribution caused by UCN-01 in wild-type A549 and A549/UCN cells using flow cytometry. UCN-01 (0.4 microM) induced apoptosis (62% terminal deoxynucleotidyl transferase-mediated nick end labeling-positive cells) in A549 cells, but not in A549/UCN cells. The percentages of cells that accumulated in G1 when exposed to UCN-01 (0.4 microM) were 22% in A549 cells and 67% in A549/UCN cells. These results suggest that acquired resistance of cancer cells against UCN-01 is characterized by attenuation of apoptosis induction associated with reinforcement of the G1 checkpoint and that apoptosis regulation is drastically altered in A549/UCN cells as compared with A549 cells. Cyclin-dependent kinase (CDK) inhibitor proteins p21 and p27 in A549/UCN cells were up-regulated, which was accompanied by overexpression of G1 cyclins D1 and E, but UCN-01 hardly affected levels of these proteins. In contrast, cyclin A, cyclin B1, retinoblastoma, and CDK2 proteins were apparently down-regulated, without changes in CDK4/6. UCN-01 hardly affected the expression level of cyclin B1 and induced dephosphorylation of retinoblastoma in both cell types. UCN-01 induced down-regulation of cyclin A level and CDK2 activity accompanied with its dephosphorylation in A549/UCN cells, but not in A549 cells. The antiapoptotic protein bcl-2 was apparently up-regulated in A549/UCN cells, however, bcl-xL, another antiapoptotic protein, was down-regulated, without changes in bak and bax. Taken together, these results are consistent with the notion that induction of apoptosis and block of cell cycle in G1 are important determinants of the sensitivity of cancer cells to UCN-01 and suggest that inhibition of CDK2 activity accompanied by its dephosphorylation and decrease of expression level of cyclin A might play an important role in the G1 phase accumulation induced by UCN-01.

Characterisation of novel human lung carcinoma cell lines selected for resistance to anti-neoplastic analogues of staurosporine.

The staurosporine analogues CGP 41251, UCN-01 and Ro 31-8220 are specific inhibitors of protein kinase C (PKC). CGP 41251 and UCN-01 exert anti-neoplastic activity against human tumours grown in rodents, and CGP 41251 reverses multidrug resistance. The hypothesis was tested that these agents can induce drug resistance and alter cellular levels of target kinases. Human-derived A549 lung carcinoma cells were exposed for 6 months to CGP 41251, UCN-01 or Ro 31-8220 at gradually increasing concentrations. Cells acquired resistance against these agents, 4.3-fold against CGP 41251 (A549/CGP cells), 4.0-fold against UCN-01 (A549/UCN cells) and 14-fold against Ro 31-8220 (A549/Ro cells). Cells were neither collaterally cross-resistant towards the PKC inhibitors nor resistant against the growth-inhibitory properties of 12-O-tetradecanoylphorbol-13-acetate. However, cross-resistance was observed in A549/CGP cells against staurosporine (13-fold) and in A549/Ro cells against doxorubicin (26-fold). All 3 cell types expressed multidrug resistance-associated protein, and A549/Ro cells expressed P-glycoprotein, as adjudged by Western blot analysis. Phorbol ester-stimulated PKC activity in these cells was decreased by between 57% and 96% compared to wild-type A549 cells. Levels of the PKC isoenzymes alpha and theta in all 3 resistant cell types and of PKC-epsilon in A549/UCN cells were concomitantly reduced. Cells regained drug sensitivity after culture in the absence of drug for 6 (A549/Ro cells), 5 (A549/CGP cells) and 1 (A549/UCN cells) months. Our results suggest the following features of this type of anti-signalling drug: (i) they can induce drug resistance, (ii) they may be potentially useful in combination because of the lack of cross-resistance between them and (iii) they can down-regulate PKC, which may have pharmacological or toxicological consequences.

Cellular relocalisation of protein kinase C-theta caused by staurosporine and some of its analogues.

The microbial product staurosporine is a protein kinase C (PKC) inhibitor with some phorbol ester-agonistic properties. It is known to cause the translocation of the PKC isoenzymes epsilon and delta from the cellular cytosol to the membrane and nucleus. We tested the hypothesis that it also affects the cellular localisation of the novel PKC isoenzyme theta, and that staurosporine analogues, some of which are currently under clinical evaluation as potential anticancer drugs, have a similar effect. Their ability to alter PKC-theta distribution was studied in human-derived A549 lung carcinoma cells. Western blot analysis and confocal microscopy after indirect immunofluorescence staining showed that staurosporine (100 nM), like the phorbol ester 12-O-tetradecanoylphorhol-13-acetate (25 nM) caused the translocation of PKC-theta from the cytosol to the membrane and the nucleus. The bisindolylmaleimide GF 109203X mimicked staurosporine, but had a weaker effect. Ro 31-8220 and UCN-01 decreased cytosolic PKC-theta only at 1 microM. CGP 41251 had no effect on PKC-theta in either experimental design. The results show that some, but not all, staurosporine analogues share the partial phorbol ester-agonistic PKC-translocatory activity of the parent molecule.

Differential effects of staurosporine analogues on cell cycle, growth and viability in A549 cells.

Staurosporine is a potent but non-specific kinase inhibitor. It has served as synthetic template for a variety of analogues, the indolocarbazoles, UCN-01 and CGP 41251, and the bisindolylmaleimides, Ro 31-8220 and GF 109203X, were investigated as growth inhibitors of human-derived A549 human lung adenocarcinoma cells. They were compared with respect to (1) effect on the cell cycle, (2) time dependency of growth arrest and (3) cytotoxic potency. Cells were exposed for 1, 2 and 4 days, or for 6, 12 and 24 h in the case of cycle-synchronised cells, to staurosporine analogues at concentrations at which they inhibited growth by 80% after 4 day exposure. Staurosporine and UCN-01 retarded cells in G0/1, and CGP 41251 appeared to inhibit cell growth without cell cycle specificity. Ro 31-8220 slowed progression of synchronised cells through the cycle; over a longer time period it induced a weak block in G2/M. GF 109203X induced potent G2/M arrest in synchronised cells. This was not so apparent in asynchronous cells, which by day 4 were slowed in G0/1 instead. Growth arrest induced by these inhibitors was more potent after incubation for 4 rather than 2 days. Incubation for 1 day followed by maintenance in drug-free medium for 3 days was sufficient to exert some cytostasis. The differences between cytotoxic and cytostatic concentrations, the former measured by release from cells of lactate dehydrogenase, were 15 000-fold for staurosporine, 300-fold for UCN-01, approximately 400-fold for CGP 41251, 25-fold for Ro 31-8220 and approximately 4-fold for GF 109203X. The results show that PKC-selective staurosporine analogues differ with respect to the mechanisms by which they interfere with the cell cycle. The necessity of long-term exposure for effective growth inhibition and the considerable margin between cytostatic and acute cytotoxic indolocarbazole concentrations are findings which might influence the planning and interpretation of clinical trials of these kinase inhibitors.

Comparison of ability of protein kinase C inhibitors to arrest cell growth and to alter cellular protein kinase C localisation.

Inhibitors of protein kinase C (PKC) such as the staurosporine analogues UCN-01 and CGP 41251 possess antineoplastic properties, but the mechanism of their cytostatic action is not understood. We tested the hypothesis that the ability of these compounds to arrest growth is intrinsically linked with their propensity to inhibit PKC. Compounds with varying degrees of potency and specificity for PKC were investigated in A549 and MCF-7 carcinoma cells. When the log values of drug concentration which arrested cell growth by 50% (IC50) were plotted against the logs of the IC50 values for inhibition of cytosolic PKC activity, two groups of compound could be distinguished. The group which comprised the more potent inhibitors of enzyme activity (calphostin C, staurosporine and its analogues UCN-01, RO 31-8220, CGP 41251) were the stronger growth inhibitors, whereas the weaker enzyme inhibitors (trimethylsphingosine, miltefosine, NPC-15437, H-7, H-7I) affected proliferation less potently. GF 109203X was exceptional in that it inhibited PKC with an IC50 in the 10(-8) M range, yet was only weakly cytostatic. To substantiate the role of PKC in the growth inhibition caused by these agents, cells were depleted of PKC by incubation with bryostatin 1 (1 microM). The susceptibility of these enzyme-depleted cells towards growth arrest induced by staurosporine, RO 31-8220, UCN-01 or H-7 was studied. The drug concentrations which inhibited incorporation of [3H]thymidine into PKC-depleted A549 cells by 50% were slightly, but not significantly, lower than significantly, lower than those observed in control cells. These results suggest that PKC is unlikely to play a direct role in the arrest of the growth of A549 and MCF-7 cells mediated by these agents. Staurosporine is not only a strong inhibitor of PKC but also mimics activators of this enzyme in that it elicits the cellular redistribution of certain PKC isoenzymes. The ability of kinase inhibitors other than staurosporine to exert a similar effect was investigated. Calphostin C, H-7, H-7I, miltefosine, staurosporine, UCN-01, RO 31-8220, CGP 41251 or GF 109203X were incubated for 30 min with A549 cells in the absence or presence of the PKC activator 12-O-tetradecanoyl phorbol-13-acetate. The subcellular distribution of PKC-alpha-, -epsilon and -zeta was measured by Western blot analysis. None of the agents affected PKC-alpha or -zeta.(ABSTRACT TRUNCATED AT 400 WORDS)

Establishment of a murine leukaemia cell line resistant to the growth-inhibitory effect of bryostatin 1.

Bryostatin 1 is a novel macrocyclic lactone activator of protein kinase C (PKC) which has clinical potential as an anti-cancer agent. The mechanism of action of this agent is unknown, but protein kinase C has been implicated. In order to investigate this possibility, we have developed P388 sublines resistant to bryostatin 1, by continuous challenge of the parent cell line with increasing incremental concentrations of the drug over 4 months. Cell lines were established at monthly intervals yielding four sublines: P388/BR/A, which were removed at 1 month; P388/BR/B, obtained after 2 months; P388/BR/C, obtained after 3 months; and P388/BR/D, which were established after 4 months. All four P388/BR sublines show an equal degree of resistance to the growth inhibitory effects of bryostatin 1, with a relative resistance ratio (RR) IC50 of approximately 4,000. The ability of the cytosol of cells to phosphorylate PKC-specific substrate is decreased by 41% for BR/A, 57% for BR/B 80% for BR/C and 94% for BR/D compared with the parental cell line, even when grown in the absence of bryostatin 1 for up to 4 weeks. Similar decreases are seen for cytosolic phorbol ester binding and whole-cell PKC isoenzyme expression. All four P388/BR sublines show high and equal levels of cross-resistance to the PKC activatory phorbol ester, phorbol 12-myristate 13-acetate (PMA). There is no loss of resistance to either bryostatin 1 or PMA up to 3 months after termination of exposure of the sublines to bryostatin 1. There was no significant degree of cross-resistance to daunorubicin in the bryosatin 1-resistant cell lines, P388/BR/A, B, C or D, when compared with the parent cell line, P388.