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Biomedical subjects

T N Robinson

Publications and source records attributed to T N Robinson.

At least 19 recordsLinked to original sources
PubMed2001

Effects of reducing children's television and video game use on aggressive behavior: a randomized controlled trial.

CONTEXT: The relationship between exposure to aggression in the media and children's aggressive behavior is well documented. However, few potential solutions have been evaluated. OBJECTIVE: To assess the effects of reducing television, videotape, and video game use on aggressive behavior and perceptions of a mean and scary world. DESIGN: Randomized, controlled, school-based trial. SETTING: Two sociodemographically and scholastically matched public elementary schools in San Jose, Calif. PARTICIPANTS: Third- and fourth-grade students (mean age, 8.9 years) and their parents or guardians. INTERVENTION: Children in one elementary school received an 18-lesson, 6-month classroom curriculum to reduce television, videotape, and video game use. MAIN OUTCOME MEASURES: In September (preintervention) and April (postintervention) of a single school year, children rated their peers' aggressive behavior and reported their perceptions of the world as a mean and scary place. A 60% random sample of children were observed for physical and verbal aggression on the playground. Parents were interviewed by telephone and reported aggressive and delinquent behaviors on the child behavior checklist. The primary outcome measure was peer ratings of aggressive behavior. RESULTS: Compared with controls, children in the intervention group had statistically significant decreases in peer ratings of aggression (adjusted mean difference, -2.4%; 95% confidence interval [CI], -4.6 to -0.2; P =.03) and observed verbal aggression (adjusted mean difference, -0.10 act per minute per child; 95% CI, -0.18 to -0.03; P =.01). Differences in observed physical aggression, parent reports of aggressive behavior, and perceptions of a mean and scary world were not statistically significant but favored the intervention group. CONCLUSIONS: An intervention to reduce television, videotape, and video game use decreases aggressive behavior in elementary schoolchildren. These findings support the causal influences of these media on aggression and the potential benefits of reducing children's media use.

Aggression↗
PubMed2001

Are perceived neighborhood hazards a barrier to physical activity in children?

BACKGROUND: We hypothesized that children's perceptions of more neighborhood hazards would be associated with less physical activity, less aerobic fitness, and a higher body mass index. OBJECTIVE: To examine the association between a hazardous neighborhood context and physical activity in children. METHODS: Fourth-grade students (n = 796) of diverse ethnic and economic backgrounds completed measures of neighborhood hazards, self-reported physical activity, physical fitness, height, and weight. Parents (n = 518) completed telephone interviews and provided data on their education level and occupation. RESULTS: As expected, children from families of lower socioeconomic status perceived significantly more neighborhood hazards. Contrary to our hypothesis, the perception of more hazards was significantly associated with more reported physical activity. This finding was not explained by school heterogeneity, alteration of the hazards measure, or differences in socioeconomic status. CONCLUSION: To further examine the relationship between neighborhood hazards and physical activity, we suggest that future studies include assessments of sedentary behavior, parental fear of violence, parental regulation of children's leisure activities, and cost and quality of available play areas and organized sports.

Acculturation↗
PubMed2001

The 30-second effect: an experiment revealing the impact of television commercials on food preferences of preschoolers.

OBJECTIVE: To examine whether televised food commercials influence preschool children's food preferences. DESIGN: In this randomized, controlled trial, preschool children viewed a videotape of a popular children's cartoon either with or without embedded commercials. Children were then asked to identify their preferences from pairs of similar products, one of which was advertised in the videotape with embedded commercials. Preschoolers' parents were interviewed to determine children's demographic characteristics and media use patterns. SUBJECTS: Forty-six 2- to 6-year-olds from a Head Start program in northern California. STATISTICAL ANALYSES: For demographic and media use characteristics, univariate data were examined and Student t and chi 2 tests were used to test for differences between the control and treatment groups. We calculated the Cochran Q statistic to assess whether the proportion of those choosing advertised food items was significantly higher in the treatment group than in the control group. RESULTS: Children exposed to the videotape with embedded commercials were significantly more likely to choose the advertised items than children who saw the same videotape without commercials (Qdiff = 8.13, df = 1, P < .01). CONCLUSIONS/APPLICATIONS: Even brief exposures to televised food commercials can influence preschool children's food preferences. Nutritionists and health educators should advise parents to limit their preschooler's exposure to television advertisements. Furthermore, advocates should raise the public policy issue of advertising and young children, especially given the recent epidemic of childhood obesity and the ever-changing media environment.

Advertising↗
PubMed2001

Television viewing and childhood obesity.

Children spend a substantial portion of their lives watching television. Investigators have hypothesized that television viewing causes obesity by one or more of three mechanisms: (1) displacement of physical activity, (2) increased calorie consumption while watching or caused by the effects of advertising, and (3) reduced resting metabolism. The relationship between television viewing and obesity has been examined in a relatively large number of cross-sectional epidemiologic studies but few longitudinal studies. Many of these studies have found relatively weak, positive associations, but others have found no associations or mixed results; however, the weak and variable associations found in these studies may be the result of limitations in measurement. Several experimental studies of reducing television viewing recently have been completed. Most of these studies have not tested directly the effects of reducing television viewing behaviors alone, but their results support the suggestion that reducing television viewing may help to reduce the risk for obesity or help promote weight loss in obese children. Finally, one school-based, experimental study was designed specifically to test directly the causal relationship between television viewing behaviors and body fatness. The results of this randomized, controlled trial provide evidence that television viewing is a cause of increased body fatness and that reducing television viewing is a promising strategy for preventing childhood obesity.

Adolescent↗
PubMed2001

Do adolescent smokers experience withdrawal effects when deprived of nicotine?

This is the first controlled prospective study of the effects of nicotine deprivation in adolescent smokers. Heart rate and subjective withdrawal symptoms were measured over an 8-hr period while participants smoked normally. Seven days later, participants were randomized to wear a 15-mg (16-hr) nicotine patch or a placebo patch for 8 hr, and they refrained from smoking during the session. Those wearing the placebo experienced a decrease in heart rate across sessions and an increase in subjective measures of nicotine withdrawal. Those wearing the active patch also reported significant increases for some subjective symptoms. Expectancy effects were also observed. The findings indicate that adolescent smokers experience subjective and objective changes when deprived of nicotine. As in previous research with adults, expectancies concerning the effects of nicotine replacement also influenced perceptions of withdrawal.

Administration, Cutaneous↗
PubMed2001

Overweight concerns and body dissatisfaction among third-grade children: the impacts of ethnicity and socioeconomic status.

OBJECTIVE: To examine the prevalence of overweight concerns and body dissatisfaction among third-grade girls and boys and the influences of ethnicity and socioeconomic status (SES). STUDY DESIGN: Nine hundred sixty-nine children (mean age, 8.5 years) attending 13 northern California public elementary schools completed assessments of overweight concerns, body dissatisfaction, and desired shape, height, and weight. RESULTS: The sample was 44% white, 21% Latino, 19% non-Filipino Asian American, 8% Filipino, and 5% African American. Twenty-six percent of boys and 35% of girls reported wanting to lose weight, and 17% of boys and 24% of girls reported dieting to lose weight. Among girls, Latinas and African Americans reported significantly more overweight concerns than Asian Americans and Filipinas, and Latinas reported significantly more overweight concerns than whites. White and Latina girls also reported greater body dissatisfaction than Asian American girls. Some differences persisted even after controlling for actual body fatness. Higher SES African American girls reported significantly more overweight concerns than lower SES African American girls, but higher SES white girls reported less overweight concerns than lower SES white girls. CONCLUSION: Overweight concerns and body dissatisfaction are highly prevalent among third-grade girls and boys, across ethnicity and SES. Young Latina and African American girls manifest equivalent or higher levels of disordered eating attitudes and behaviors as white and Asian American girls.

Black or African American↗
PubMed2001

Effects of reducing television viewing on children's requests for toys: a randomized controlled trial.

Previous attempts to reduce the effects of television advertising on children's purchase requests have had little success. Therefore, we tested the effects of a classroom intervention to reduce television, videotape, and video game use on children's toy purchase requests, in a school-based randomized controlled trial. Third- and fourth-grade children (mean age, 8.9 years) in two sociodemographically and scholastically matched public elementary schools were eligible to participate. Children in one randomly selected elementary school received an 18-lesson, 6-month classroom curriculum to reduce television, videotape, and video game use. In both schools, in September (before intervention) and April (after intervention) of a single school year, children and parents reported children's prior week's purchase requests for toys seen on television. After intervention, children in the intervention school were significantly less likely to report toy purchase requests than children in the control school, with adjusting for baseline purchase requests, gender, and age (odds ratio, 0.29; 95% confidence interval, 0.12-0.69). Among intervention school children, reductions in self-reported purchase requests were also associated with reductions in television viewing. There was no significant difference between schools in parent reports of children's requests for toy purchases. These findings suggest that reducing television viewing is a promising approach to reducing the influences of advertising on children's behavior.

Advertising↗
PubMed2001

TNF receptor I is required for induction of macrophage heat shock protein 70.

Expression of heat shock proteins (HSP) is an adaptive response to cellular stress. Stress induces tumor necrosis factor (TNF)-alpha production. In turn, TNF-alpha induces HSP70 expression. However, osmotic stress or ultraviolet radiation activates TNF-alpha receptor I (TNFR-I) in the absence of TNF-alpha. We postulated that TNF-alpha receptors are involved in the induction of HSP70 by cellular stress. Peritoneal Mphi were isolated from wild-type (WT), TNF-alpha knockout (KO), and TNFR (I or II) KO mice. Cells were cultured overnight and then heat stressed at 43 +/- 0.5 degrees C for 30 min followed by a 4-h recovery at 37 degrees C. Cellular HSP70 expression was induced by heat stress or exposure to endotoxin [lipopolysaccharide (LPS)] as determined by immunoblotting. HSP70 expression induced by either heat or LPS was markedly decreased in TNFR-I KO Mphi, whereas TNFR-II KO Mphi exhibited HSP70 expression comparable to that in WT mice. Expression of HSP70 after heat stress in TNF-alpha KO Mphi was also similar to that in WT mice, suggesting that induction of HSP70 by TNFR-I occurs independently of TNF-alpha. In addition, levels of steady-state HSP70 mRNA were similar by RT-PCR in WT and TNFR-I KO Mphi despite differences in protein expression. Furthermore, the effect of TNFR-I appears to be cell specific, since HSP70 expression in splenocytes isolated from TNFR-I KO was similar to that in WT splenocytes. These studies demonstrate that TNFR-I is required for the synthesis of HSP70 in stressed Mphi by a TNF-independent mechanism and support an intracellular role for TNFR-I.

Animals↗
PubMed2000

Are overweight children unhappy?: Body mass index, depressive symptoms, and overweight concerns in elementary school children.

BACKGROUND: It is commonly believed that overweight children are unhappy with their weight. However, population-based data addressing this association are lacking. OBJECTIVES: To evaluate the association between obesity and depressive symptoms in a diverse, school-based sample of preadolescent children, and to examine whether overweight concerns play a role in this association. DESIGN, SETTING, AND PARTICIPANTS: Third-grade students (N = 868, mean age, 8.4 years) attending 13 public elementary schools in Northern California were measured for weight and height, and were asked to complete self-report assessments of depressive symptoms and overweight concerns. RESULTS: A modest association between depressive symptoms and body mass index (BMI; calculated as weight in kilograms divided by the square of height in meters) was found for girls (r = 0.14, P<.01), but not for boys (r = 0.01, P<.78). Among girls, depressive symptoms were strongly associated with overweight concerns (r = 0.32, P<.001). After controlling for level of overweight concerns, BMI was no longer significantly associated with depressive symptoms among girls. In contrast, after controlling for BMI, overweight concerns remained significantly associated with depressive symptoms. CONCLUSIONS: This study provides cross-sectional evidence for a relationship between depressive symptoms and BMI in preadolescent girls, but not in preadolescent boys. This relationship seems to be explained by an excess of overweight concerns. Assessing overweight concerns may be a useful method to identify those overweight girls who are at highest risk for associated depressive symptoms.

Attitude to Health↗
PubMed2000

Does the camera add 10 pounds? Media use, perceived importance of appearance, and weight concerns among teenage girls.

PURPOSE: To examine the relationship between use of electronic media and perceived importance of appearance and weight concerns among adolescent girls. METHODS: Physical measures and self-report surveys were obtained from 837 ninth-grade girls attending pubs lic high schools in San Jose, California (mean age = 14.9 +/- 0.47 years; 36% Latino, 24% White, 22% Asian, 8% Black, 10% other). Correlational and multiple regression analyses were performed with ethnicity, body mass index (BMI), perceived importance of appearance, weight concerns, and media use (based on self-reported average weekly use of television, videotapes, video and computer games, and music videos). RESULTS: Total media use was not significantly related to perceived importance of appearance or weight concerns. When media use was separated into distinct media genres, only hours of watching music videos was related to perceived importance of appearance and weight concerns (r = 0.12, p < .001, and r = .08, p < .05, respectively). In multivariate analyses, after controlling for BMI and ethnicity, no media use variables were significantly associated with either perceived importance of appearance or weight concerns. CONCLUSIONS: Frequent music video use may be a risk factor for increased perceived importance of appearance and increased weight concerns among adolescent girls.

Adolescent↗
PubMed2000

Central exendin-4 infusion reduces body weight without altering plasma leptin in (fa/fa) Zucker rats.

OBJECTIVE: To investigate whether chronic administration of the long-acting glucagon-like peptide-1 receptor agonist exendin-4 can elicit sustained reductions in food intake and body weight and whether its actions require an intact leptin system. RESEARCH METHODS AND PROCEDURES: Male lean and obese Zucker (fa/fa) rats were infused intracerebroventricularly with exendin-4 using osmotic minipumps for 8 days. RESULTS: Exendin-4 reduced body weight in both lean and obese Zucker rats, maximum suppression being reached on Day 5 in obese (8%) and Day 7 in lean (16%) rats. However, epididymal white adipose tissue weight was not reduced, and only in lean rats was there a reduction in plasma leptin concentration. Food intake was maximally suppressed (by 81%) on Day 3 in obese rats but was reduced by only 18% on Day 8. Similarly, in lean rats food intake was maximally reduced (by 93%) on Day 4 of treatment and by 45% on Day 8. Brown adipose tissue temperature was reduced from Days 2 to 4. Plasma corticosterone was elevated by 76% in lean but by only 28% in obese rats. DISCUSSION: Chronic exendin-4 treatment reduced body weight in both obese and lean Zucker rats by reducing food intake: metabolic rate was apparently suppressed. These effects did not require an intact leptin system. Neither does the absence of an intact leptin system sensitize animals to exendin-4. Partial tolerance to the anorectic effect of exendin-4 in lean rats may have been due to elevated plasma corticosterone and depressed plasma leptin levels, but other counter-regulatory mechanisms seem to play a role in obese Zucker rats.

Adipose Tissue↗
PubMed2000

Selective mitochondrial KATP channel opening controls human myocardial preconditioning: too much of a good thing?

BACKGROUND: Paradoxically, patients with noninsulin-dependent diabetes mellitus experience a higher cardiovascular mortality rate than patients with insulin-dependent diabetes mellitus. We have shown that K(ATP) channel inhibition, with oral sulfonylureas, prevents myocardial preconditioning and may explain the paradox of cardiovascular death in patients with noninsulin-dependent diabetes mellitus. Cardiac preconditioning is an attractive protective strategy against any elective ischemia/reperfusion (I/R) injury. The relationship between the K(ATP) channels and human myocardial preconditioning has not previously been elucidated. METHODS: Human atrial trabeculae were harvested, placed in organ baths, and paced (1 Hz). Developed force was recorded during simulated 37 degrees C I/R (30/45 or 45/60 minutes). Before I/R, trabeculae were treated transiently with a selective mitochondrial K(ATP) channel opener for 5 minutes, followed by a 10-minute washout, or were exposed to the channel opener throughout ischemia. Recovery of function is expressed as percentage of baseline developed force. Conserved creatine kinase activity (units per gram of wet tissue) was measured at the end of reperfusion as an indicator of cellular protection. RESULTS: Transient mitochondrial K(ATP) channel opening provided protection from both I/R insults. Surprisingly, there was no protection afforded by continuous mitochondrial K(ATP) channel opening. CONCLUSIONS: Transient selective mitochondrial K(ATP) channel opening protects both viability and function of human myocardium against I/R injury, although prolonged opening of the mitochondrial K(ATP) channel does not. These results reinforce the concept of preconditioning as a transient event that must be completed before the onset of ischemia.

Adenosine Triphosphate↗
PubMed2000

Selective mitochondrial adenosine triphosphate-sensitive potassium channel activation is sufficient to precondition human myocardium.

OBJECTIVES: Recently, the mitochondrial adenosine triphosphate-sensitive potassium channel has been suggested to be the final common effector of myocardial preconditioning. The purpose of this study is to determine whether selective mitochondrial adenosine triphosphate-sensitive potassium channel activation alone can precondition human myocardium from an ischemia/reperfusion insult. METHODS: Isolated human right atrial trabeculae were placed in tissue baths, paced, and subjected to 30 minutes of normothermic hypoxia (ischemia) followed by 45 minutes of reoxygenation (reperfusion). Trabeculae were preconditioned with a selective mitochondrial adenosine triphosphate-sensitive potassium channel opener (diazoxide 30 micromol/L) or a nonselective purinergic agonist, adenosine (125 micromol/L), for 5 minutes (adenosine) followed by a 10-minute washout period. Developed force at end reperfusion (mean +/- standard error) was compared with baseline, and tissue creatine kinase and adenosine triphosphate levels were measured after ischemia/reperfusion. RESULTS: Trabeculae subjected to ischemia/reperfusion exhibited 30% +/- 2% of baseline developed force, whereas trabeculae subjected to selective adenosine triphosphate-sensitive potassium channel opening (diazoxide) and nonselective purinergic agonist (adenosine) recovered to 55% +/- 7% and 46% +/- 3% of baseline developed force, respectively. Tissue creatine kinase activity was preserved in both the diazoxide- and adenosine-treated trabeculae (5.4 +/- 12 and 5.4 +/- 14 micromol/L per gram wet tissue) compared with ischemia/reperfusion (1.8 +/- 0.2 U/mg wet tissue). Adenosine triphosphate levels at end reperfusion were also increased in the trabeculae treated with selective (diazoxide) and nonselective (adenosine) adenosine triphosphate-sensitive potassium channel opener (4.1 +/- 0.01 and 4. 4 +/- 0.2 micromol/L per gram wet tissue) compared with trabeculae subjected to ischemia/reperfusion (1.5 +/- 0.1 micromol/L per gram wet tissue). CONCLUSIONS: These results suggest that selective mitochondrial adenosine triphosphate-sensitive potassium channel activation preconditions human myocardium and the protection conferred is equal to that of adenosine preconditioning. Targeted openers of mitochondrial adenosine triphosphate- sensitive potassium channels promote constructive protection of myocellular energy levels, contractile function, and cellular viability in human myocardium after ischemia/reperfusion.

Adenosine↗
PubMed1999

Reducing children's television viewing to prevent obesity: a randomized controlled trial.

CONTEXT: Some observational studies have found an association between television viewing and child and adolescent adiposity. OBJECTIVE: To assess the effects of reducing television, videotape, and video game use on changes in adiposity, physical activity, and dietary intake. DESIGN: Randomized controlled school-based trial conducted from September 1996 to April 1997. SETTING: Two sociodemographically and scholastically matched public elementary schools in San Jose, Calif. PARTICIPANTS: Of 198 third- and fourth-grade students, who were given parental consent to participate, 192 students (mean age, 8.9 years) completed the study. INTERVENTION: Children in 1 elementary school received an 18-lesson, 6-month classroom curriculum to reduce television, videotape, and video game use. MAIN OUTCOME MEASURES: Changes in measures of height, weight, triceps skinfold thickness, waist and hip circumferences, and cardiorespiratory fitness; self-reported media use, physical activity, and dietary behaviors; and parental report of child and family behaviors. The primary outcome measure was body mass index, calculated as weight in kilograms divided by the square of height in meters. RESULTS: Compared with controls, children in the intervention group had statistically significant relative decreases in body mass index (intervention vs control change: 18.38 to 18.67 kg/m2 vs 18.10 to 18.81 kg/m2, respectively; adjusted difference -0.45 kg/m2 [95% confidence interval [CI], -0.73 to -0.17]; P = .002), triceps skinfold thickness (intervention vs control change: 14.55 to 15.47 mm vs 13.97 to 16.46 mm, respectively; adjusted difference, -1.47 mm [95% CI, -2.41 to -0.54]; P=.002), waist circumference (intervention vs control change: 60.48 to 63.57 cm vs 59.51 to 64.73 cm, respectively; adjusted difference, -2.30 cm [95% CI, -3.27 to -1.33]; P<.001), and waist-to-hip ratio (intervention vs control change: 0.83 to 0.83 vs 0.82 to 0.84, respectively; adjusted difference, -0.02 [95% CI, -0.03 to -0.01]; P<.001). Relative to controls, intervention group changes were accompanied by statistically significant decreases in children's reported television viewing and meals eaten in front of the television. There were no statistically significant differences between groups for changes in high-fat food intake, moderate-to-vigorous physical activity, and cardiorespiratory fitness. CONCLUSIONS: Reducing television, videotape, and video game use may be a promising, population-based approach to prevent childhood obesity.

Body Mass Index↗
PubMed1999

Ethnic variation in cardiovascular disease risk factors among children and young adults: findings from the Third National Health and Nutrition Examination Survey, 1988-1994.

CONTEXT: Knowledge about ethnic differences in cardiovascular disease (CVD) risk factors among children and young adults from national samples is limited. OBJECTIVE: To evaluate ethnic differences in CVD risk factors, the age at which differences were first apparent, and whether differences remained after accounting for socioeconomic status (SES). DESIGN: Third National Health and Nutrition Examination Survey, 1988-1994. SETTING: Eighty-nine mobile examination centers. PARTICIPANTS: A total of 2769 black, 2854 Mexican American, and 2063 white (non-Hispanic) children and young adults aged 6 to 24 years. MAIN OUTCOME MEASURES: Ethnicity and household level of education (SES) in relation to body mass index (BMI), percentage of energy from dietary fat, cigarette smoking, systolic blood pressure, glycosylated hemoglobin (HbA1c), and non-high-density lipoprotein cholesterol (non-HDL-C [the difference between total cholesterol and HDL-C]). RESULTS: The BMI levels were significantly higher for black and Mexican American girls than for white girls, with ethnic differences evident by the age of 6 to 9 years (a difference of approximately 0.5 BMI units) and widening thereafter (a difference of >2 BMI units among 18- to 24-year-olds). Percentages of energy from dietary fat paralleled these findings and were also significantly higher for black than for white boys. Blood pressure levels were higher for black girls than for white girls in every age group, and glycosylated hemoglobin levels were highest for black and Mexican American girls and boys in every age group. In contrast, smoking prevalence was highest for white girls and boys, especially for those from low-SES homes (77% of young men and 61% of young women, aged 18-24 years, from low-SES homes were current smokers). All ethnic differences remained significant after accounting for SES and age. CONCLUSION: These findings show strong ethnic differences in CVD risk factors among youths of comparable age and SES from a large national sample. The differences highlight the need for heart disease prevention programs to begin early in childhood and continue throughout young adulthood to reduce the risk of atherosclerosis.

Adolescent↗