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Biomedical subjects

C E Davis

Publications and source records attributed to C E Davis.

At least 19 recordsLinked to original sources

The relationship between unsupervised time after school and physical activity in adolescent girls.

BACKGROUND: Rising obesity and declining physical activity levels are of great concern because of the associated health risks. Many children are left unsupervised after the school day ends, but little is known about the association between unsupervised time and physical activity levels. This paper seeks to determine whether adolescent girls who are without adult supervision after school are more or less active than their peers who have a caregiver at home. METHODS: A random sample of girls from 36 middle schools at 6 field sites across the U.S. was selected during the fall of the 2002-2003 school year to participate in the baseline measurement activities of the Trial of Activity for Adolescent Girls (TAAG). Information was collected using six-day objectively measured physical activity, self-reported physical activity using a three-day recall, and socioeconomic and psychosocial measures. Complete information was available for 1422 out of a total of 1596 respondents.Categorical variables were analyzed using chi square and continuous variables were analyzed by t-tests. The four categories of time alone were compared using a mixed linear model controlling for clustering effects by study center. RESULTS: Girls who spent more time after school (> or = 2 hours per day, > or = 2 days per week) without adult supervision were more active than those with adult supervision (p = 0.01). Girls alone for > or = 2 hours after school, > or = 2 days a week, on average accrue 7.55 minutes more moderate to vigorous physical activity (MVPA) per day than do girls who are supervised (95% confidence interval ([C.I]). These results adjusted for ethnicity, parent's education, participation in the free/reduced lunch program, neighborhood resources, or available transportation. Unsupervised girls (n = 279) did less homework (53.1% vs. 63.3%), spent less time riding in a car or bus (48.0% vs. 56.6%), talked on the phone more (35.5% vs. 21.1%), and watched more television (59.9% vs. 52.6%) than supervised girls (n = 569). However, unsupervised girls also were more likely to be dancing (14.0% vs. 9.3%) and listening to music (20.8% vs. 12.0%) (p < .05). CONCLUSION: Girls in an unsupervised environment engaged in fewer structured activities and did not immediately do their homework, but they were more likely to be physically active than supervised girls. These results may have implications for parents, school, and community agencies as to how to structure activities in order to encourage teenage girls to be more physically active.

Journal Article↗

High rates of obesity and cardiovascular disease risk factors in lower middle class community in Pakistan: the Metroville Health Study.

OBJECTIVES: To describe the distribution of over weight and body mass index, waist circumference and waist/ hip ratio, correlate obesity measures to coronary heart disease risk factors in comparison to Pakistan National Survey (PNS). METHODS: The Metroville Health Study (MHS) was an urban risk factor reduction intervention study in Metroville Karachi. Base line data was used which was not a random sample. Demographic data including serum cholesterol, glucose, haemoglobin, and blood pressure were collected. RESULTS: In MHS high cholesterol was 16% and 24% in men and women respectively, and 25% had hypertension. Self-reported diabetes was 8%, over-weight/obesity 34% and 49% for men and women, compared to 16% and 25% for PNS, while high risk waist-hip ratio (WHR) was present in 41% and 72% of men and women respectively. Under-weight in Metroville men was 12% and 9% in women, compared to 26% and 27% in PNS. The anthropometry variables were significantly correlated with each other while weight was significantly correlated with TC and waist circumference (WC). CONCLUSION: Obesity was alarmingly prevalent in urban Metroville in comparison to PNS. Cardio Vascular Disease (CVD) risk factors were prevalent in Metroville and TC and WC were significantly correlated with obesity measures. For prevention of increasing CVD in urban communities, targeted programs of intervention are required.

Adolescent↗

Blood pressure and hypertension distribution in a lower middle class urban community in Pakistan.

OBJECTIVE: To determine the awareness level, blood pressure profile and its correlates in Metroville Health Study and to compare the results with those of Pakistan National Health Survey and National Health and Nutrition Examination Survey of USA. METHODS: Sample consisted of 400 households of Metroville, included after informed consent. Demographic data was collected and Blood pressure, Cholesterol, Blood Glucose, Height and weight were measured. Obesity was calculated as BMI. The results were compared with those of the Pakistan National Health Survey and National Health and Nutrition Examination Survey of USA. RESULTS: For both sexes and all age groups, hypertension was more prevalent in MHS than Pakistan National Health Survey (PNHS) and U.S. MHS hypertensives were more likely to be aware of and treated for their condition than hypertensives of PNHS, but less likely than U.S. hypertensives. Systolic and diastolic blood pressure (DBP) rose with increased age in all three populations. Blood pressure also rose with increased body mass index (BMI) in MHS as well as PNHS and NHANES, with little differences in the degree of rise among them. A one-kg/Height (in m approximately) increment in BMI was associated with a 0.40-0.67 mmHg increment in systolic pressure in men and a 0.56-0.74 mmHg increment in women. The main difference between USA and two Pakistani surveys was the level of DBP, which was significantly higher in Pakistani Surveys than NHANES, for both men and women. CONCLUSIONS: The prevalence of Hypertension in Metroville was high. It showed a quantitative relationship to increasing age and BMI. Hypertension and obesity were the major public health problems in the lower middle class community of Metroville. It is recommended that awareness should be increased and preventive measures implemented.

Adolescent↗

Statistical approaches to effectiveness measurement and outcome-driven re-randomizations in the Clinical Antipsychotic Trials of Intervention Effectiveness (CATIE) studies.

The design of the Clinical Antipsychotic Trials of Intervention Effectiveness (CATIE) schizophrenia and Alzheimer's disease studies pose several statistical challenges, including issues related to performing multiple comparisons, defining effectiveness outcomes, and collecting and analyzing data from a design with multiple outcome-driven re-randomizations. We discuss the CATIE strategy for addressing many hypotheses within the context of one clinical trial while controlling the overall type I error rate. We provide motivation for the use of two effectiveness outcomes: time to all-cause discontinuation and composite endpoints that combine outcomes from multiple domains, such as efficacy, safety, cost-effectiveness, and quality of life. Methods for statistical analysis of an outcome-driven re-randomization trial are compared and evaluated. We describe analysis within each phase, analysis based on the first randomization or treatment algorithms, and repeated measures modeling. Finally, strategies are described for designing an electronic data collection system for trials with repeated outcome-driven re-randomizations.

Algorithms↗

Efficacy of CVD risk factor modification in a lower-middle class community in Pakistan: the Metroville Health Study.

The Metroville Health Study aimed to reduce consumption of total cooking fats by 33%, salt by 25% and replace ghee with vegetable oil in a lower middle class urban community in Pakistan. Households (n=403) were randomly assigned to Intervention and Control groups. A baseline screening collected data on CVD risk factors, knowledge and attitudes and household consumption of cooking fats and salt. Intervention households received information about CVD and regular visits by social workers who measured cooking fats and salt and counselled cooks on the goals of intervention. Two years later, 291 households were re-screened. Intervention households reduced consumption of fats and salt compared to differences were total fat, 48% (p<0.0001); ghee, 37% (p=0.005); vegetable oil, 33% (p=0.0001); and salt, 41% (p=0.011). Household visits by trained social workers were effective in achieving reductions in consumption of cooking fat and salt in a lower class urban community.

Cardiovascular Diseases↗

Hypertensive retinopathy and incident coronary heart disease in high risk men.

BACKGROUND/AIM: Although routine ophthalmoscopy is recommended in the evaluation of people with hypertension, the prognostic significance of retinopathy is unknown. The purpose of this study is to determine if hypertensive retinopathy predicts coronary heart disease (CHD). METHODS: A prospective cohort study involving 560 hypertensive, hyperlipidaemic, middle aged men enrolled in the Lipid Research Clinic's Coronary Primary Prevention Trial. Signs of hypertensive retinopathy (generalised and focal arteriolar narrowing, arteriovenous nicking, widened arteriolar light reflex, retinal haemorrhage and exudates, microaneurysms, and disc swelling) were evaluated by direct funduscopy during a baseline examination by study physicians. Incident CHD events were ascertained from hospital records, necropsy reports, and death certificates, and reviewed by a masked panel of cardiologists. RESULTS: There were 51 definite CHD events (definite CHD deaths or myocardial infarctions) during a median follow up of 7.8 years. After adjusting for age, blood pressure, electrocardiographic manifestations of left ventricular hypertrophy, cholesterol levels and treatment, glucose and creatinine levels, and smoking status in proportional hazards analysis, the presence of hypertensive retinopathy predicted a doubling of the risk of definite CHD events (relative risk 2.1; 95% confidence interval (CI) 1.0 to 4.2 ). The presence of either generalised or focal arteriolar narrowing predicted almost a tripling of the risk (relative risk 2.9; 95% CI 1.3 to 6.2). Associations were similar for stage 1 hypertension (systolic and diastolic blood pressures of 140-159 and 90-99 mm Hg, respectively) and for other CHD end points. CONCLUSION: Hypertensive retinopathy predicts CHD in high risk men, independent of blood pressure and CHD risk factors. The data support the concept that retinal microvascular changes are markers of blood pressure damage and may be useful in risk stratification and in the tailoring of hypertension treatment decisions.

Coronary Disease↗

Serum cholesterol changes from 1983-1984 to 1993-1994 in the People's Republic of China.

BACKGROUND AND AIM: Increasing cardiovascular disease (CVD) mortality in the People's Republic of China (PRC) led to the 1981 establishment of the PRC-USA Study of Cardiovascular and Cardiopulmonary Epidemiology which, among other objectives, is concerned with the correlates of CVD morbidity and mortality in Chinese populations among other objectives. This report describes changes in total cholesterol (TC) levels in four PRC populations from 1983 to 1993 and identifies factors related to the changes. METHODS AND RESULTS: Population screenings carried out in 1983-1984, 1987-1988 and 1993-1994 involved the collection of demographic data, specimens (including blood), medical history and physical examination data. The data from cohort and independent samples were used to assess TC changes in urban and rural men and women over the decade, with and without adjustment for age and body mass index (BMI) changes. For Guangzhou men and women, the cohort analyses (aged 35-54 at baseline) showed increases in TC of 10-20 mg/dL after adjustment for age and changes in BMI; the independent sample analyses (aged 35-44) also showed higher average TC levels in 1993-1994 than in 1983-1984. For the Beijing cohorts, the results showed decreases in TC during the decade in men, an increase in TC in urban women and no change in rural women; the independent sample analyses indicated declines in TC for Beijing men and women. Possible reasons for the Guangzhou TC increases are economic growth, and dietary and BMI changes. The mean age-adjusted BMI significantly increased (5-10%) over the 10-year period in all of the studied groups. CONCLUSIONS: TC increased 10-20 mg/dL in Guangzhou men and women, probably as a result of socioeconomic development during the decade. The inconsistent patterns of TC changes in Beijing require further study.

Adult↗

Imputation strategies for missing data in a school-based multi-centre study: the Pathways study.

Pathways is a multi-centre school-based trial sponsored by the National Heart, Lung, and Blood Institute testing the efficacy of an obesity prevention intervention in American Indian children. During the study's protocol development, we prepared an analysis plan that accounted for missing data. In this paper, we present a case study of the process we used to decide upon the final analysis plan. The primary endpoint of the Pathways study is a comparison of per cent body fat between treatment and usual care groups at the end of a three-year intervention. Other studies on children and Native Americans have had moderate to large amounts of missing data. As a result we were concerned that missing data in Pathways would affect the type I error rate and power of the test of our primary endpoint. We present results from our evaluation of three alternative procedures in this paper. The first is a multiple imputation procedure in which we replace missing values with resampled values from the observed data. The second is based on the Wilcoxon rank sum test; missing data in the intervention group receive the worst ranks. In the third, we use a multiple imputation procedure and replace missing values with predicted values from a regression equation with the coefficients estimated from observed follow-up data and baseline values. We found that the multiple imputation procedure that replaces missing values with predicted values had the best properties of the procedures we considered. The results from our simulation study showed that, for missing data patterns that are relevant to the Pathways study, this procedure has high power and maintains the type I error rate. Published in 2001 by John Wiley & Sons, Ltd.

Analysis of Variance↗

Fluorescence emission spectral shift measurements of membrane potential in single cells.

Previous measurements of transmembrane potential using the electrochromic probe di-8-ANEPPS have used the excitation spectral shift response by alternating excitation between two wavelengths centered at voltage-sensitive portions of the excitation spectrum and recording at a single wavelength near the peak of the emission spectrum. Recently, the emission spectral shift associated with the change in transmembrane potential has been used for continuous membrane potential monitoring. To characterize this form of the electrochromic response from di-8-ANEPPS, we have obtained fluorescence signals from single cells in response to step changes in transmembrane potentials set with a patch electrode, using single wavelength excitation near the peak of the dye absorption spectrum. Fluorescence changes at two wavelengths near voltage-sensitive portions of the emission spectrum and shifts in the complete emission spectrum were determined for emission from plasma membrane and internal membrane. We found that the fluorescence ratio from either dual-wavelength recordings, or from opposite sides of the emission spectrum, varied linearly with the amplitude of the transmembrane potential step between -80 and +60 mV. Voltage dependence of difference spectra exhibit a crossover point near the peak of the emission spectra with approximately equal gain and loss of fluorescence intensity on each side of the spectrum and equal response amplitude for depolarization and hyperpolarization. These results are consistent with an electrochromic mechanism of action and demonstrate how the emission spectral shift response can be used to measure the transmembrane potential in single cells.

Cell Line↗

Neural substrates of facial emotion processing using fMRI.

We identified human brain regions involved in the perception of sad, frightened, happy, angry, and neutral facial expressions using functional magnetic resonance imaging (fMRI). Twenty-one healthy right-handed adult volunteers (11 men, 10 women; aged 18-45; mean age 21.6 years) participated in four separate runs, one for each of the four emotions. Participants viewed blocks of emotionally expressive faces alternating with blocks of neutral faces and scrambled images. In comparison with scrambled images, neutral faces activated the fusiform gyri, the right lateral occipital gyrus, the right superior temporal sulcus, the inferior frontal gyri, and the amygdala/entorhinal cortex. In comparisons of emotional and neutral faces, we found that (1) emotional faces elicit increased activation in a subset of cortical regions involved in neutral face processing and in areas not activated by neutral faces; (2) differences in activation as a function of emotion category were most evident in the frontal lobes; (3) men showed a differential neural response depending upon the emotion expressed but women did not.

Adult↗

Multi-country comparison of plasma lipid relationship to years of schooling in men and women.

BACKGROUND: The association between coronary heart disease (CHD) and social status has differed among societies in strength and direction. As years of schooling is a major determinant of socioeconomic status and dyslipidaemia a major CHD determinant, the purpose of this investigation is to estimate the association of years of schooling with plasma lipids and lipoproteins among samples from five countries representing different cultures, socio-political systems and stages of economic development. METHODS: Men and women from Chinese, Polish, Russian, Israeli and US samples were studied. Years of schooling were analysed both as a multi-category ordinal variable and divided into two strata: less than the equivalent of high school and greater than or equal to high school equivalence. Fasting plasma cholesterol, low density lipoprotein (LDL) cholesterol, high density lipoprotein (HDL) cholesterol and triglycerides were compared across years of schooling strata within each country. Lipid levels were computed unadjusted and then adjusted for age and lipid risk factor variables. RESULTS: Total cholesterol, LDL cholesterol, and triglycerides varied directly with years of schooling in Chinese, Polish and Russian men, and in contrast varied inversely with years of schooling among US white men. The HDL cholesterol varied inversely with years of schooling for Chinese, Polish, and Russian men, but varied directly with years of schooling among US white men. The lipid differences between men of high versus low years of schooling were not explained by age, body mass index, smoking, alcohol consumption or blood pressure medication use. Findings were less consistent for women and for Israelis and US blacks of both genders. CONCLUSIONS: Lipid and lipoprotein levels consistent with atherogenicity varied directly with years of schooling in Chinese, Polish, and Russian samples. Opposite trends were present in US whites. These findings are consistent with a hypothesized influence of social status on CHD risk differing among populations in relation to stages in societal economic development.

Asia↗

Acid phosphatase activity and color changes in consumer-style griddle-cooked ground beef patties.

The U.S. Department of Agriculture and the Food and Drug Administration have issued temperature requirements to help consumers cook beef patty products that are free of pathogens. Verification of end-point temperature (EPT) is needed in cooked meat products due to concerns over outbreaks of Escherichia coli O157:H7. Acid phosphatase (ACP) activity was studied as a potential method for determination of EPT in ground beef patties cooked nonfrozen, patties frozen 7 days and thawed at room temperature 4 h in a refrigerator or by microwave, and patties made from ground beef frozen in store packages, then thawed in a refrigerator overnight. Pressed-out meat juices were analyzed from patties (n = 314) cooked to 57.2 degrees C (135 degrees F). 65.6 degrees C (150 degrees F), 71.1 degrees C (160 degrees F), and 79.4 degrees C (175 degrees F) target EPTs. Expressed meat juice and internal meat patty color decreased in redness as EPT increased. Freezing whole packs with slow refrigerator or room temperature thawing caused significantly greater loss of redness in expressed cooked meat juice than did other handling methods. Log10 ACP had a significant linear (R2 = 0.99) response to EPT. Results show that the 3- to 5-min ACP test could be used to verify EPT in griddle-cooked hamburger patties.

Acid Phosphatase↗

Total synthesis of (+/-)-cameroonanol.

[reaction: see text]The structure and relative stereochemistry of the novel silphiperfolane-type sesquiterpene cameroonan-7alpha-ol (1) were confirmed by a total synthesis of (+/-)-1 from 3,3,5-trimethylbicyclo[3.3.0]oct-1(8)-en-2-one (6) by means of a Sakurai reaction with (Z)-crotylsilane, free radical hydrobromination, base-induced cyclization, and LiAlH4 reduction.

Indicators and Reagents↗

Haemostasis and carotid artery wall thickness in non-insulin dependent diabetes mellitus.

The purpose of this study was to examine the associations of carotid artery intima-media wall thickness (IMT) with hemostatic proteins and cardiovascular risk factors (CVRFs) in participants with and without non-insulin dependent diabetes mellitus (NIDDM). IMT measurements were determined by high resolution B-mode ultrasound imaging of the carotid arteries in 921 participants with NIDDM and 11,964 non-diabetic participants aged 45-64 years. Fasting glucose, serum lipids and activated partial thromboplastin time, factor VIII fibrinogen, factor VII, antithrombin III, protein C, and von Willebrand factor measurements were made. Compared to non-diabetic participants, participants with NIDDM had a more adverse pattern of CVRFs and a more procoagulatory profile. Participants with NIDDM had 0.06 mm (8.1%) higher mean IMT compared to non-diabetic participants after adjusting for age and gender (P < 0.001). However, only plasma fibrinogen concentrations showed statistically significant positive associations with IMT in both groups. After adjusting for CVRFs and fibrinogen, mean IMT remained 0.04 mm (5.4%) higher in diabetic compared to non-diabetic participants. Despite the more procoagulatory profile in participants with NIDDM, only plasma fibrinogen concentrations were independently associated with mean IMT. The association of NIDDM with mean IMT was only partly explained by CVRFs.

Age Distribution↗

Estimation of body fat from anthropometry and bioelectrical impedance in Native American children.

OBJECTIVE: Obesity, as measured by body mass index, is highly prevalent in Native American children, yet there are no valid equations to estimate total body fatness for this population. This study was designed to develop equations to estimate percentage body fat from anthropometry and bioelectrical impedance as a critical part of Pathways, a multi-site study of primary prevention of obesity in Native American children. DESIGN: Percentage fat was estimated from deuterium oxide dilution in 98 Native American children (Pima/Maricopa, Tohono O'odham and White Mountain Apache tribes) between 8 and 11 y of age. The mean fat content (38.4%+/-8. 1%) was calculated assuming the water content of the fat-free body was 76%. Initial independent variables were height, weight, waist circumference, six skinfolds and whole-body resistance and reactance from bioelectrical impedance (BIA). RESULTS: Using all-possible-subsets regressions with the Mallows C (p) criterion, and with age and sex included in each regression model, waist circumference, calf and biceps skinfolds contributed least to the multiple regression analysis. The combination of weight, two skinfolds (any two out of the four best: triceps, suprailiac, subscapular and abdomen) and bioelectrical impedance variables provided excellent predictability. Equations without BIA variables yielded r2 almost as high as those with BIA variables. The recommended equation predicts percentage fat with a root mean square error=3.2% fat and an adjusted r2=0.840. CONCLUSION: The combination of anthropometry and BIA variables can be used to estimate total body fat in field studies of Native American children. The derived equation yields considerably higher percentage fat values than other skinfold equations in children.

Adipose Tissue↗

Weight gain and its correlates in Poland between 1983 and 1993.

BACKGROUND: Weight gain and its unfavorable consequences on coronary heart disease (CHD) risk have been observed worldwide. Determinants of weight gain were studied in a Polish cohort of 1042 men and women age 35-64 at baseline. Participants were randomly selected from an urban population in Warsaw and a rural population in Tarnobrzeg Province surveyed by investigators in Krakow. The surveys, part of the Pol-MONICA project, were conducted in 1983-1984, 1987-1988, and 1992-1993. The purpose of this report is to gain insight into the dynamics of weight gain in this population that could be helpful in identifying high-risk groups for intervention, and to determine if economic changes that took place shortly after the second survey had any impact on weight gain. METHODS: Weight, height and demographic characteristics were measured at each visit according to Pol-MONICA standard protocol. Body mass index (BMI) was calculated as kg/m2. Years of schooling, 7-day alcohol history and smoking history were self-reported. RESULTS: Sixty percent of the cohort gained some weight, averaging 0.3-0.7kg/y. Weight gain was highest in younger rural women, in urban men and in rural women with low education. In multiple linear regression, low education was related to a 1.29 kg greater weight gain (P<0.01), ex-smoking status was related to a 2.54 kg greater weight gain (P<0.001), and younger age was related to a 1.14 kg greater weight gain (P<0.001). CONCLUSION: Our results indicate a need to target intervention programs at young low SES adults. Developing effective means of reaching these vulnerable groups is a critical research goal.

Adult↗

Nosocomial transmission of Mycobacterium bovis bacille Calmette-Guerin to children receiving cancer therapy and to their health care providers.

A previous report of nosocomial infection due to Mycobacterium bovis bacille Calmette-Guerin (BCG) implicated contamination of chemotherapy solutions reconstituted under the same biosafety hood as BCG vaccine used for bladder cancer therapy. We report 3 similar BCG infections in children and describe evidence of respiratory transmission to health care workers (HCWs) from 1 patient. These children were receiving chemotherapy for leukemia when they presented with active tuberculosis. Each isolate was identified biochemically and by both gas-liquid chromatography and major polymorphic tandem repeat-polymerase chain reaction. Pulsed-field gel electrophoresis showed that 2 isolates were identical strains and identical to the Tice and Connaught strains licensed in the United States for bladder chemotherapy. The third isolate differed by a single fragment after DraI restriction. One patient with heavily positive sputum exposed numerous HCWs. Of 41 HCWs, 2 (5%) converted their purified protein derivatives (PPD) skin test. These data underscore the risk of nosocomial BCG transmission by contamination of chemotherapy solutions and demonstrate the potential for transmission to HCWs from patients with active pulmonary disease.

Adolescent↗

Rising levels of cardiovascular mortality in Mississippi, 1979-1995.

BACKGROUND: Cardiovascular disease rates are improving in the United States, but not for certain subgroups, especially some African Americans. The objective of the study is to assess current levels and trends in cardiovascular disease mortality in Mississippi. METHODS: Mortality statistics from the U.S. vital statistics system for the period 1979-95 were used. Comparison of age-adjusted mortality rates in Mississippi with the other states for the year 1995 and with the nation as a whole over the period of 1979-95 was performed. RESULTS: Mississippians had the highest age-adjusted cardiovascular disease morality rates in the nation in 1995. Overall, the cardiovascular rates in Mississippi were 37% higher than for the U.S. African American men and women from Mississippi had especially high cardiovascular mortality rates, approximately 50% and 70% higher than their white counterparts, respectively. The higher burden of cardiovascular disease in African Americans from Mississippi was especially marked in the younger age groups. Since about 1984-85, cardiovascular mortality rates in Mississippi have been increasing for African Americans, whereas nationally they have been decreasing. In contrast, cardiovascular mortality rates for whites in Mississippi have been declining, but at a much slower rate than seen nationally. The wide divergence in trends for African American and white men and women over that period in Mississippi has lead to an estimated 19,400 excess cardiovascular deaths. Virtually identical trends were found for heart disease. CONCLUSIONS: Cardiovascular diseases are a major public health problem in Mississippi that is especially severe in African American residents, and the problem is growing worse each year. It is important to identify the determinants of and solutions for this enormous public health problem in Mississippi.

Adult↗