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Biomedical subjects

R G Sargent

Publications and source records attributed to R G Sargent.

At least 37 records · Page 2Linked to original sources
PubMed1997

The impact of a required college health and physical education course on the health status of alumni.

The impact of a required college health and physical education course on selected health knowledge, attitudes, and behaviors of alumni was evaluated. The design was a cross-sectional study (mail out/mail back survey) using a stratified random sample of 2,000 college alumni. The overall response rate was 50%. Results were analyzed by college of graduation (college with a required health/physical education course versus no required course). Alumni who took the course were more likely to know their blood pressure, blood cholesterol, and recommended dietary fat intake than the comparison group were. They also reported that the course positively influenced their attitudes toward exercise, eating, and smoking They were more likely to engage in aerobic exercise and less likely to smoke; and they had lower intakes of dietary fat, cholesterol, and sodium. The results suggested that a required college course enhanced selected health-related knowledge, attitudes, and behaviors of alumni.

Adult↗
PubMed1997

Repair of site-specific double-strand breaks in a mammalian chromosome by homologous and illegitimate recombination.

In mammalian cells, chromosomal double-strand breaks are efficiently repaired, yet little is known about the relative contributions of homologous recombination and illegitimate recombination in the repair process. In this study, we used a loss-of-function assay to assess the repair of double-strand breaks by homologous and illegitimate recombination. We have used a hamster cell line engineered by gene targeting to contain a tandem duplication of the native adenine phosphoribosyltransferase (APRT) gene with an I-SceI recognition site in the otherwise wild-type APRT+ copy of the gene. Site-specific double-strand breaks were induced by intracellular expression of I-SceI, a rare-cutting endonuclease from the yeast Saccharomyces cerevisiae. I-SceI cleavage stimulated homologous recombination about 100-fold; however, illegitimate recombination was stimulated more than 1,000-fold. These results suggest that illegitimate recombination is an important competing pathway with homologous recombination for chromosomal double-strand break repair in mammalian cells.

Adenine Phosphoribosyltransferase↗
PubMed1997

A methodology for optimally designing console panels for use by a single operator.

A seven-step methodology is presented to determine a dimensionally correct optimal layout of a console panel for a single operator. This methodology integrates the steps in the layout design process and uses a mathematical optimization model from facility design to obtain the optimal panel layout. A major difference in this methodology from previous work is that the mathematical optimization model incorporates factors that are only partially included in previous mathematical models. In addition, it includes the areas of the panel components as a new factor. This methodology is illustrated by the design of a nuclear power plant console panel.

Anthropometry↗
PubMed1996

The influence of a (GT)29 microsatellite sequence on homologous recombination in the hamster adenine phosphoribosyltransferase gene.

Several DNA sequence elements are thought to stimulate homologous recombination, illegitimate recombination, or both in mammalian cells. Some are implicated by their recurrence around rearrangement breakpoints, others by their effects on recombination of extrachromosomal plasmids. None of these sequences, however, has been tested on the chromosome in a defined context. In this paper we show how the adenine phosphoribosyltransferase locus in CHO cells can be used to study the recombinogenic potential of defined DNA sequences. As an example we have measured the effect on homologous recombination of a dinucleotide repeat, (GT)29, which has been shown to stimulate homologous recombination in extrachromosomal vectors 3-20 fold. On the chromosome at the adenine phosphoribosyltransferase locus, however, this sequence shows no capacity to stimulate recombination or to influence the distribution of recombination events.

Adenine Phosphoribosyltransferase↗
PubMed1996

Patterns of tobacco and alcohol use among sedentary, exercising, nonathletic, and athletic youth.

Through a statewide random design, 7,846 9th to 12th grade students in 81 South Carolina public schools were selected to complete the Youth Risk Behavior Survey. Mantel-Haenszel Chi-Square, general linear models, and logistic regression were used to examine the relation between the independent variables of race, gender, and physical activity status with the dependent variables of tobacco and alcohol use while controlling for race, gender, and participation in physical education classes. The six physical activity levels ranged from sedentary nonathletes to athletes participating on two or more sports teams. Highly active athletes drank more frequently than did low-activity nonathletes (p = .002) and sedentary nonathletes (p = .006), and they were more likely to binge drink (p = .004). Athletic groups were less likely to smoke than were the nonathletic groups (p < .0001) with "sedentary nonathletes" the heaviest smokers of all groups. Athletes were more likely to use smokeless tobacco (p < .0001) than nonathletes although this difference disappeared when controlling for gender and race. This research supports other findings about prevalence of smokeless tobacco use among athletic youth. In addition, it reveals that athletic youth are at an increased risk of alcohol use and binge drinking. Possible factors such as the risk-taking tendencies of team sport athletes should be investigated.

Adolescent↗
PubMed1995

Efficient modification of the APRT gene by FLP/FRT site-specific targeting.

The FLP/FRT site-specific recombination system was established and characterized at the APRT gene in CHO cells. Targeting frequencies with FLP-stimulation were about 1 to 5 X 10(-5), which were 6-22-fold above gene targeting frequencies in the absence of FLP. Fifty two APRT+ cell lines were analyzed by Southern blotting: 56% were FLP-targeted integrants; 33% were APRT target convertants; 11% gave undefined patterns. In separate experiments we first enriched for integrants by screening for two additional markers carried on the targeting vector; 18 of 19 (95%) of the resulting cell lines were integrants. Intrachromosomal site-specific recombination was tested by reexposing integrants to FLP. Intrachromosomal popouts were stimulated over 200-fold, while homologous recombination in an adjacent interval was unchanged. The utility of this system was demonstrated by one-step FLP targeting to generate chromosomal substrates for homologous recombination, and by a two-step, FLP-and-run procedure to construct a chromosomal substrate for illegitimate recombination.

Adenine Phosphoribosyltransferase↗
PubMed1995

The relationship between diet, activity, and other factors, and postpartum weight change by race.

OBJECTIVE: To identify the impact of dietary intake and activity level on postpartum weight change. METHODS: White (n = 121) and black (n = 224) women, 7-12 months postpartum, participating in the Special Supplemental Feeding Program for Women, Infants, and Children were assessed for dietary intake, activity level, body weight, and other maternal characteristics. RESULTS: For both black and white women, the most important variables in predicting postpartum weight loss were pre-pregnancy weight, gestational weight gain, parity, and prenatal exercise. After these factors were controlled, race predicted that black women retained 6.4 lb more than white women. These results may be due to the finding that black women reported significantly higher mean energy intake (2039 versus 1552 kcal, P < .001), higher percent fat in diet (41 versus 38%, P < .001), and significantly lower amounts of prenatal and postpartum activity. CONCLUSION: Higher energy intake and lower activity levels in black postpartum mothers compared with white mothers may contribute to the significantly higher rates of obesity found in black mothers. This study suggests the need for intervention strategies in the prenatal and postpartum periods to help those at risk of retaining weight gained during pregnancy.

Adult↗
PubMed1994

Black and white females' perceptions of ideal body size and social norms.

Different cultural norms and standards for appropriate female body size might contribute to the disparity in obesity rates between black and white adult females (46.0% and 24.6% respectively). The purpose of this study was to measure adolescents' perceptions of ideal size and social norms regarding female body size as well as adolescents' perceptions of significant others' evaluation and expectations of the adolescents' body size. Subjects included 437 adolescent girls (247 white and 190 black) aged 13 to 19 (x = 14.9, SD = .979) from six randomly selected public schools. The subjects, heights and weights were measured. Responses to a body image questionnaire and a series of nine female body drawings (arranged ordinally, 1 to 9, from thinnest to heaviest) were analyzed using the General Linear Model and Logistic Regression. The female body size considered ideal by black females was significantly larger than the size selected as ideal by white females (x = 3.47 and x = 3.13 respectively, p < 0.001). Black females were two times more likely than white females to describe themselves as thinner than other girls their age (O.R. = 2.01, 95% C.I. 1.34, 3.01) and seven times as likely to say that they were not overweight (O.R. = 7.08, 95% C.I. 3.72, 13.45). White females wanted to be a smaller size than they currently were and felt encouraged by significant others to lose weight or reduce their size. Black females did not indicate as great a desire as whites to be smaller and they tended to feel that their size was considered satisfactory by significant others. Only subjects from the low SES group perceived that significant others wanted them to gain weight. The differences between black and white subjects' beliefs and perceptions about body size norms may explain, in part, why heavier body weights persist in some cultural groups.

Adolescent↗
PubMed1994

Black and white adolescent females' pre-pregnancy nutrition status.

The dietary intakes of energy, protein, calcium, and iron of 408 randomly selected nonpregnant, black and white female adolescents were analyzed to determine their pre-pregnancy nutritional status. Pre-pregnancy weight for height was calculated and used as an indicator of nutritional status. After controlling for race, socioeconomic status, and age, results indicated that black females had significantly higher mean intakes of energy (p = .0001), protein (p < .0001), calcium (p = .0205), and iron (p = .0001) than did white females. Distribution of white and black females in the percentages of RDA categories differed significantly for energy (p < .0001), protein (p < .0001), and iron (p < .0001). A higher percentage of white females were found in the three lower categories (< 100% of RDA) than of black females. No significant differences were found in the distribution of black and white females in the three Body Mass Index categories. A large proportion of both black and white females' intakes of energy, calcium, and iron were below the recommended allowances when categorized according to the percentages of recommended intakes. Thirty-seven percent of the black females and 42.6% of the white females were classified by their BMIs as being underweight. These findings suggest that the majority of black and white females surveyed had poor pre-pregnancy nutritional status.

Adolescent↗
PubMed1994

Dietary behaviors of South Carolina adolescents.

Data from studies conducted on South Carolina adolescents indicate caloric intake to be less than recommended, intakes of calcium, iron and fiber are also less than recommended. Protein intake and cholesterol intake appears to higher than recommended. When distribution of energy intake is assessed excessive amounts of fat are consumed while reduced intakes of carbohydrates are observed. General dietary practices indicate inadequate intakes of fruits, cooked vegetables, and salads, while excessive intakes of hamburgers, fried foods, and pastries are observed. These findings indicate S. C. adolescents are consuming a diet that increases risk for diet related diseases that may occur in adulthood.

Adolescent↗
PubMed1992

Thermogenic effects of pre-prandial and post-prandial exercise in obese females.

The thermogenic effects of pre- and postprandial exercise was examined in six obese premenopausal females. Using open circuit calorimetry, energy expenditure was measured for 3 hours following five separate treatments: Resting Control, Exercise Only (25 min cycle at 60% VO2 max), Meal Only (902 kcal mixed meal), Exercise-Meal, and Meal-Exercise. Meal Only, Exercise-Meal, and Meal-Exercise were significantly higher than Rest Only and Exercise Only treatments. However, Meal-Exercise resulted in the greatest energy expenditure. These results suggest that in obese female subjects exercise following a meal will produce the greatest thermogenic response and could possibly influence weight maintenance or weight loss if implemented in food and exercise patterns of behavior.

Adult↗
PubMed1992

Effect of iron supplementation on endurance capacity in iron-depleted female runners.

The purpose of this investigation was to examine the effects of oral iron supplementation on endurance performance in initially iron-depleted, nonanemic female distance runners. Eighteen iron-depleted (serum ferritin less than 20 ng.ml-1, hemoglobin greater than or equal to 12 g.dl-1) women (22-39 yr) performed a VO2max test and an endurance run to exhaustion. Subjects were pair-matched on the basis of endurance time and then randomly assigned to an iron supplement or a placebo group. Following supplementation, the iron group had a significantly higher (P = 0.03) mean serum ferritin concentration (23.4 vs 15.7 ng.ml-1) and lower (P = 0.04) mean total iron-binding capacity than the placebo group. Both groups increased their time to exhaustion (25.5% and 22.2% for the iron and placebo groups, respectively) but were not significantly different (P = 0.72) from each other. There were also no differences (P greater than 0.05) between the groups with respect to lactate concentrations and physiological measures taken during the two exercise tests. The results of this study suggest that 8 wk of oral iron supplementation improves iron status in iron-depleted female distance runners, but does not enhance endurance capacity.

Adult↗
PubMed1991

T4 phage ribonucleotide reductase. Allosteric regulation in vivo by thymidine triphosphate.

Based upon analyses of purified enzyme preparations, T4 bacteriophage-coded ribonucleotide reductase is considered to be relatively insensitive to control by allosteric inhibition. However, two factors suggest that CDP reduction to dCDP is feedback-controlled by dTTP in infected cells. First, the pool of 5-hydroxymethyldeoxycytidine triphosphate, which expands manyfold upon infection by a dCMP deaminase-deficient T4 mutant, shrinks to near-normal levels as a consequence of dTTP accumulation, and ribonucleotide reductase is the only apparent control point. Second, analysis of mutagenesis by 5-bromodeoxyuridine suggests that most induced mutations result from localized pool depletion of 5-hydroxymethyl-dCTP at replication sites, as if 5-bromo-dUTP were behaving like dTTP in inhibiting the CDP reductase activity of the phage enzyme. We found that CDP reductase activity in crude extracts of T4 phage-infected bacteria is sensitive to inhibition by either dTTP or 5-bromo-dUTP, at concentrations as low as 0.01 mM. However, in partially purified enzyme preparations that sensitivity is lost. Although we don't know the basis for this loss of feedback sensitivity, the results suggest that kinetic properties of enzymes in intact cells are determined by the cellular milieu in ways not apparent from analysis of purified enzymes.

Allosteric Regulation↗
PubMed1990

Dietary intake of women runners.

One hundred and three women who were habitual distance runners and 74 age-matched physically inactive women provided three-day diet records. Intergroup differences in intakes of energy nutrients, micronutrients, cholesterol and fiber were evaluated via analysis of variance and, to assess qualitative differences, via analysis of covariance with total caloric intake entered as the covariate. Women runners reported consuming more carbohydrate (192.4 vs 165.0 g.d-1) and less fat (57.5 vs 66.1 g.d-1) than did the inactive women (p less than .05). After controlling for the non-significant intergroup difference in caloric intake, these differences persisted and protein intake was lower in the runners. Cholesterol and saturated fat intakes were lower and fiber intake was greater in the runners, with and without control for differences in caloric intake. These data suggest that female runners, when compared to inactive counterparts, tend to follow dietary practices that conform more closely to the current recommendations of health authorities.

Adult↗
PubMed1989

Ribonucleotide reductase: a determinant of 5-bromodeoxyuridine mutagenesis in phage T4.

Mutagenesis by 5-bromodeoxyuridine (BrdUrd) can result from base-pairing errors either during replication of a BrdUrd-containing template or at the nucleotide incorporation step. Replication errors give rise predominantly to AT-to-GC transitions, while incorporation errors, in which 5-bromo-dUTP competes with dCTP at a template guanine site, should give rise to GC-to-AT transitions. The latter pathway should be sensitive to deoxyribonucleoside triphosphate (dNTP) pool fluctuations. Since dNTP pools are regulated through allosteric control of ribonucleotide reductase, the control of this enzyme should be a determinant of BrdUrd mutagenesis--if mutagenesis results largely from incorporation errors. Since T4 phage-encoded ribonucleotide reductase is insensitive to feedback inhibition, we established conditions under which phage DNA replication is dependent upon ribonucleotide reductase of the host, Escherichia coli. We examined BrdUrd mutagenesis of rII mutants known to revert to wild type either by AT-to-GC or GC-to-AT transition pathways. While both reversion pathways were stimulated under all conditions analyzed, the AT-to-GC pathway was stimulated more when the E. coli reductase was functioning, while the GC-to-AT pathway was more specifically enhanced when the T4 reductase was active. These results confirm that ribonucleotide reductase is a determinant of BrdUrd mutagenesis, but our observations, plus experiments showing that BrdUrd has relatively small effects upon dNTP pool sizes, indicate that the relationship between deoxyribonucleotide metabolism and BrdUrd mutagenesis is more complex than anticipated.

Bromodeoxyuridine↗
PubMed1989

Weight control and calorie expenditure: thermogenic effects of pre-prandial and post-prandial exercise.

The thermogenic effects of pre- and postprandial exercise was examined in seven lean active females. Energy expenditure was measured for 3 h via open circuit indirect calorimetry after four separate treatments: Exercise Only (25 min treadmill run at 60% VO2 max), Meal Only (910 kcal mixed meal), Exercise-Meal and Meal-Exercise. The thermogenic response to the Exercise-Meal treatment was similar to the Meal Only treatment. However, the Meal-Exercise treatment resulted in a greater energy expenditure than the Meal Only and Exercise-Meal treatments. The Exercise Only treatment showed the lowest thermogenic response. These data suggest that exercise following a meal would be more beneficial than exercise before a meal in increasing and maintaining an elevated energy expenditure.

Adult↗
PubMed1989

A study of factors associated with weight change in women who attempt smoking cessation.

This study investigated behavioral and attitudinal relationships over a 12-week time period in 48 women enrolled in a commercial smoking cessation program who were categorized as non-recidivists (NR), early recidivists (ER) and late recidivists (LR) to cigarette smoking. NR had significantly higher weight gains (F = 6.70), significantly higher levels of physical activity (F = 6.42), and significantly less concern of postsmoking cessation weight gain (F = 5.08) than either two groups of recidivists, (p less than or equal to .05). Other findings, although not significant, were that NR exhibited lower caloric intake and more frequent snacking behaviors than either ER or LR. These results indicate an overall stronger commitment to more positive health behaviors in the NR than those who returned to cigarette smoking.

Adult↗