Biomedical subjects

H de Vries

Publications and source records attributed to H de Vries.

132 records · Page 8Linked to original sources

PubMedDate not supplied

Social influences on young adults' alcohol consumption: norms, modeling, pressure, socializing, and conformity.

This study aims to assess which types of social influence are correlated with young people's (15-24 years) heavy drinking (six or more glasses) in public drinking places during the weekend. Drinking in public drinking places can be defined as a "timeout" situation. Therefore we assumed that situational factors (e.g., importance of socializing and direct pressures on drinking) would contribute more to the explained variance than variables indicating cognitive social influences (e.g., social norms and modeling). Stepwise regression analyses showed that in total 25% of the variance was explained by social norms of family and peers (15%), importance of socializing in drinking situations (7%), modeling (2%) and group size (1%). The results show that both a cognitive factor and a situational factor appear to be most strongly correlated with young people's frequency of heavy drinking in public drinking places. Within the category of situational influences those variables indicating direct social pressures were only weakly related or not significant. Studies focusing on measuring the impact of social influences may profit from including the concept of the importance of socializing and conformity as an additional factor.

Adolescent↗

PubMedDate not supplied

Subtypes within the precontemplation stage of adolescent smoking acquisition.

The present study examined the existence of three possible subtypes within the precontemplation stage of smoking acquisition: committers, immotives, and progressives. The sample of the study included young people from six European countries (mean age = 13 years) who had never smoked regularly (n = 21 535). A cross-sectional design was used to assess cognitive determinants of smoking behavior: attitudes towards smoking, perceived social influences, and self-efficacy to remain a nonsmoker. Adolescents within the various stages of smoking acquisition were compared with regard to standardized T scores on these risk factors. The results showed that adolescents in the three subgroups of precontemplation differed from each other on every cognitive determinant tested, revealing a higher risk to start smoking among progressives than among immotives. Immotives revealed a higher risk to start smoking than committers. It is concluded that the use of subtypes within acquisition precontemplation in research on adolescent smoking may be a promising tool for investigating the initiation continuum and for improving the quality of both the implementation and evaluation of prevention programs.

Adolescent↗

PubMedDate not supplied

On the biogenesis of the myelin sheath: cognate polarized trafficking pathways in oligodendrocytes.

Oligodendrocytes, the myelinating cells of the central nervous system, are capable of transporting vast quantities of proteins and of lipids, in particular galactosphingolipids, to the myelin sheath. The sheath is continuous with the plasma membrane of the oligodendrocyte, but the composition of both membrane domains differs substantially. Given its high glycosphingolipid and cholesterol content the myelin sheath bears similarity to the lipid composition of the apical domain of a polarized cell. The question thus arises whether myelin components, like typical apical membrane proteins are transported by an apical-like trafficking mechanism to the sheath, involving a 'raft'-mediated mechanism. Indeed, the evidence indicates the presence of cognate apical and basolateral pathways in oligodendrocytes. However, all major myelin proteins do not participate in this pathway, and remarkably apical-like trafficking seems to be restricted to the oligodendrocyte cell body. In this review, we summarize the evidence on the existence of different trafficking pathways in the oligodendrocyte, and discuss possible mechanisms separating the oligodendrocyte's membrane domains.

Animals↗

PubMedDate not supplied

Singlet oxygen mediated photobinding of 8-methoxypsoralen to DNA and genotoxicity in E. coli.

Although oxygen dependent photoreactions of 8-methoxypsoralen (8-MOP) are known, damage to DNA is mostly considered to proceed via photocycloaddition to this biomacromolecule. In this study the survival of colony forming ability of E. coli K12/343, which is deficient in DNA-repair capability, appeared to be lower in D2O than in H2O after exposure to the combination of 8-MOP and UV-A. Photobinding to bacterial DNA was approximately 40% higher in D2O than in H2O. However this last difference was found only when the bacteria were kept in the reaction medium for 1 h at 37 degrees C after the irradiation was stopped and not when they were plated out immediately afterwards. The results indicate that in this bacterial test system 1O2 mediated photobinding of 8-MOP to DNA contributes to the genotoxic effect observed.

DNA Repair↗

PubMedDate not supplied

[Extracurricular activities of adolescents useful for smoking prevention programs. OCTOPUS team].

BACKGROUND: The cigarette smoking habit continues to be prevalent to a greater degree than would be desirable among teenagers. Innovative prevention programs are needed. This descriptive cross-sectional study sets out the behavior variables related to the cigarette smoking habit and the extracurricular activities in which teenagers are most frequently involved which are useful for setting out extracurricular prevention programs. METHODS: The data was collected by means of a questionnaire validated in a representative sample of school age youths (ages 10-11 and 13-14) from Asturias. The variables entailed in cigarette smoking were analyzed using the regression method. RESULTS: The starting smoker percentage is 14.5%-42.5%, regular smokers totaling 1.1% and 12.4%, respectively. Two models were constructed with the variables significantly related to smoking behavior, which are properly classified into smoker/non-smoker by 98.85% and 91.39% of the children, by ages. The environmental variables (availability of cigarettes and alcoholic beverages and regular visits to places entailing risk) are the major aspects comprising the model. The most common extracurricular activities are: watching TV, reading and listening to music and watching or playing sports. CONCLUSION: The findings provide keys to planning extracurricular activities tailored to fit in with the activities most popular among teens: TV commercials and ads on music media (CD's, tapes, etc.) and printed information mailed directly to teens at their homes, with messages conveyed by opinion-leaders among teens in the fields of sports, music and television.

Adolescent↗

PubMedDate not supplied

[Educational intervention in schools for the prevention of smoking: evaluation of the process. Project: OCTOPUS].

BACKGROUND: The published data on the effectiveness of programs in schools to prevent addiction to tobacco are not consistent. These programs have not been sufficiently studied, and their variables give rise to confusion. The aim of this study was to evaluate the process of educational action taken in schools. METHOD: Student leaders and teachers, who were trained and given guides, developed a socially based program. Two students selected at random from each class were interviewed, using a validated and directed questionnaire. A total of 318 children were interviewed. The Kappa Index was used to measure confidence, and the Inter-Class Coefficient of Correlation and Pearson's Coefficient were used together with analysis of individual differences to compare the data for program adjustment, as supplied by pupils and teachers. RESULTS: Mean adjustment per class was 30.07 points (48-100% adjustment). 26% of children were unable to mention any alternative to the advantages of smoking, 71.7% were unaware of the frequency of consumption amongst adults and 19.5% were unable to mention any of the tricks used in cigarette advertising. Less than half had performed psychodrama on this subject, as was required. The ICC was 0.21, Pearson's Coefficient was 0.25 (p = 0.02) and the interval of agreement between the descriptions of teachers and students was 6.93 points (-1.70 to 5.23). CONCLUSIONS: The degree to which implementation complied with the proposed model of program was insufficient. We found little agreement between the self-assessment of teachers and the score attained by pupils in compliance with the program. It is essential that this process be evaluated for its impact to be evaluated correctly.

Adolescent↗