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R Cameron

Publications and source records attributed to R Cameron.

120 records · Page 7Linked to original sources
PubMedDate not supplied

Dispositional risk factors for smoking-stage transitions: a social influences program as an effect modifier.

A cognitive-developmental model postulates three predominant adolescent dispositions (self-definition, social compliance, and affect regulation) which may impede or facilitate transitions in stages of smoking. The purpose of the present prospective study was to build on the findings supporting this model. One hundred schools were randomly assigned to either receive or not receive a social influences smoking prevention program. A baseline survey, including smoking behavior and dispositional items, was administered in the sixth grade in 1990, interventions were delivered in the sixth and seventh grades, and a survey was administered following the seventh grade intervention. Principal component patterns, based on dispositional items, were very similar for grades 6 and 7, did not vary by gender, and the components (rebelliousness, rejection of adult authority, personal dissatisfaction, and peer approval) were correlated. All smoking-stage transitions were positively related to rebelliousness for boys. The relationship of the dispositional scores with smoking-stage transitions was more complex for girls. Receiving the program modified the effects of the dispositional risk scores, particularly for girls.

Adolescent↗
PubMedDate not supplied

Radiosensitizing effects of nicotinamide on a C3H mouse mammary adenocarcinoma. A study on per os drug administration.

Nicotinamide is an inhibitor of adenosine diphosphate ribosyl transferase (ADPRT) which is involved in the mechanism of DNA repair after high doses of ionizing radiation. C3H mice with transplanted mammary adenocarcinomas were treated with low doses of nicotinamide, 10 mg/kg, 5 days a week, and in combination with ionizing radiation, 30 Gy, using different drug dose schedules. Mice given nicotinamide in combination with irradiation took a longer time to reach a tumor volume of 1,000 mm3 and a higher complete response rate (i.e. defined as total disappearance of the tumor for at least 7 days) than those given radiation alone. This was true whether nicotinamide was given daily from one week before tumor transplantation until the animal was killed or from transplantation day until day of irradiation. In addition, nicotinamide given per os at a dose between the recommended maximum daily allowance for human subjects (20 mg/70 kg), and the therapeutic allowance (1 g-12 g daily) 5 days a week for 9 weeks, showed a radiosensitizing effect without any histologically detectable damage to the normal tissues of the mouse, including bone marrow, intestine and the liver.

Adenocarcinoma↗
PubMedDate not supplied

A comparison between instructional experience and performance of teachers and nurses delivering a smoking prevention program.

This paper focuses on the implementation evaluation strategy of a smoking prevention program and examines differences in instructional experience and implementation of the grade six curriculum in relation to provider type. Arbaseline, nurses (n = 40), compared with teachers (n = 39), reported (a) less previous classroom teaching experience, (b) greater reliance on lecturing and audio/visual materials, (c) less use of small group classroom activities, and (d) less confidence using small group and role playing methods in the classroom. More nurses than teachers believed smoking to be a significant problem in the schools. Nurses had less confidence than teachers in their ability to teach the smoking prevention curriculum. Nonetheless, behavioural observation indicated that nurses implemented the curriculum more completely. However, teachers, at least those who received workshop training, showed some evidence of greater utilization of teaching styles thought to be desirable.

Adult↗
PubMedDate not supplied

Progression of human endometrial adenocarcinoma heterotransplanted into nude mice from hormone-sensitive to hormone resistant growth.

We have used a human tumor nude mouse model involving heterotransplantation and serial passage of an estrogen receptor (ER) positive, progesterone receptor (PgR) negative human endometrial adenocarcinoma. The effects of estradiol treatment on tumor growth, ER activation and PgR induction were investigated two and four years after heterotransplantation. In Experiment I, two years after initial heterotransplantation, tumor growth and proliferative rate showed a dose-related decrease, ER was activated by estradiol treatment (measured through an increased amount of ER bound with high affinity to nuclear element(s) (ERhs) and PgR was induced. Two years later (Experiment II), the amount of ER1s (ER measured in cytosolic fraction) as well as of ERhs was lower than at the beginning of Experiment I. ER could again be activated by estradiol treatment and PgR was also induced. However, in this experiment no effect either of tumor growth or of proliferative rate was observed during the estradiol treatment. Our study therefore indicates that an estrogen non-sensitive growth can develop during serial passages in intact, non-treated female nude mice, although the capacity for ER activation and PgR induction is maintained.

Adenocarcinoma↗
PubMedDate not supplied

Estradiol induced changes in tumor growth and steroid receptor content in a heterotransplanted human endometrial adenocarcinoma.

To study the importance of estrogen availability to growth pattern and other tumor characteristic such as estrogen receptor (ER) and progesterone receptor (PgR) content and histopathology, we have used a human tumor-nude mouse model, in which an ER- and PgR-positive and estradiol-sensitive (stimulated) human endometrial adenocarcinoma was heterotransplanted and serially passed in female (non-oophorectomized) nude mice over a period of one year. Pieces from this tumor were transplanted into oophorectomized nude mice, randomly divided into two groups, one with and one without estradiol treatment (preparation phase). After four weeks, pieces from both these groups were again transplanted into oophorectomized nude mice, each group being randomly allocated to two subgroups, one with and one without estradiol treatment (experimental phase). Tumor growth was measured during the experimental phase, whereas both ER and PgR content and histopathology were analyzed after the experimental phase. Our findings indicate that even short-term growth under estradiol-poor conditions can trigger such progressive changes as reduced steroid receptor content, development of a less differentiated tumor and tendency to enhanced tumor growth. On the other hand, estradiol-rich conditions enhanced ER activation, PgR induction and tumor differentiation in the same tumor line. The estrogenic conditions under which a tumor grows may thus be crucial determinants of tumor progression.

Adenocarcinoma↗
PubMedDate not supplied

Toward the development of self-help health behaviour change programs: weight loss by correspondence.

The goal of this study was to evaluate a correspondence weight control program, and to assess the impact of three program elements (weekly homework, interim weigh-ins, and participation deposits) individually and in combination. All treated participants received 15 weekly standard lessons by mail. Three program features were varied factorially: a) homework assignments, b) interim weigh-ins and c) a deposit refunded contingent on returning homework and/or attending interim weigh-ins. Participants were assigned randomly to active treatment conditions or a delayed treatment control group. Among treated males (N = 14), initial average weight loss and BMI reduction were 9.6 kg and 3.1 respectively; average net weight loss and BMI reduction at one year follow-up were 5.8 kg and 1.9 respectively. Among treated females (N = 128), initial average weight loss and BMI reduction were 3.1 kg and 1.2 respectively; average net weight loss and BMI reduction at one year were 2.3 kg and .88 respectively. Women in all treated groups, except lessons only, showed a greater BMI reduction than untreated controls at the end of treatment. Women in conditions including both homework and interim weigh-ins had greater initial BMI reductions (M = 1.6) than those who received lessons only (M = .76). At one year, net BMI reductions were comparable across all treated groups. Of the 42 women initially registered in conditions that included both homework and weigh-ins, 12 who denied joining other programs lost at least 4.5 kg (M = 7.1) during treatment, and 7 had a net loss of at least 4.5 kg (M = 8.0) at one year without apparent involvement in any other program.

Adult↗
PubMedDate not supplied

Estrogen receptor activation in relation to previous estrogen treatment in carcinoma corporis uteri heterotransplanted into nude mice.

The interaction between estradiol and its receptor in human endometrial adenocarcinoma was investigated in a human tumor-nude mice model. Estradiol treatment was found to activate estrogen receptor (ER), estimated through the measurement of ER in the nuclear fraction. The receptor activation in the tumors was significantly higher in tumors previously treated with estradiol than in previously non-treated tumors. The activation seems also to be dependent on the estrogen dose. We concluded, that previous influence of estradiol may change the sensitivity of estrogen receptor positive tumors for its hormone, and therefore the measurement of the receptor content alone does not seem to be a sufficient marker for the prediction of the receptor activation process.

Adenocarcinoma↗
PubMedDate not supplied

The dissemination of chronic disease prevention programs: linking science and practice.

A strong partnership between researchers and providers is crucial to advance the science of dissemination and to support dissemination of effective chronic disease prevention programs. We reflect on our experience in three recent studies, (a) COMMIT, (b) a National Survey of School Smoking Prevention Programs, and (c) an ongoing study of Training of Providers of Smoking Prevention Programs to identify specific ways in which research and provider communities might collaborate. We propose that a national working group of researchers and providers be established to support (a) dissemination of programs by creating and continuously updating an inventory of 'tested' methods and protocols for use in key community intervention channels (health care offices, worksites, etc.) and (b) dissemination research by establishing a shared set of research priorities and mechanisms to stimulate researcher-provider partnership during the research process.

Canada↗