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B Dennis

Publications and source records attributed to B Dennis.

At least 19 recordsLinked to original sources
PubMed2003

INTERMAP: background, aims, design, methods, and descriptive statistics (nondietary).

Blood pressure (BP) above optimal (< or =120/< or =80 mmHg) is established as a major cardiovascular disease (CVD) risk factor. Prevalence of adverse BP is high in most adult populations; until recently research has been sparse on reasons for this. Since the 1980s, epidemiologic studies confirmed that salt, alcohol intake, and body mass relate directly to BP; dietary potassium, inversely. Several other nutrients also probably influence BP. The DASH feeding trials demonstrated that with the multiple modifications in the DASH combination diet, SBP/DBP (SBP: systolic blood pressure, DBP: diastolic blood pressure) was sizably reduced, independent of calorie balance, alcohol intake, and BP reduction with decreased dietary salt. A key challenge for research is to elucidate specific nutrients accounting for this effect. The general aim of the study was to clarify influences of multiple nutrients on SBP/DBP of individuals over and above effects of Na, K, alcohol, and body mass. Specific aims were, in a cross-sectional epidemiologic study of 4680 men and women aged 40-59 years from 17 diverse population samples in China, Japan, UK, and USA, test 10 prior hypotheses on relations of macronutrients to SBP/DBP and on role of dietary factors in inverse associations of education with BP; test four related subgroup hypotheses; explore associations with SBP/DBP of multiple other nutrients, urinary metabolites, and foods. For these purposes, for all 4680 participants, with standardized high-quality methods, assess individual intake of 76 nutrients from four 24-h dietary recalls/person; measure in two timed 24-h urine collections/person 24-h excretion of Na, K, Ca, Mg, creatinine, amino acids; microalbuminuria; multiple nutrients and metabolites by nuclear magnetic resonance and high-pressure liquid chromatography. Based on eight SBP/DBP measurements/person, and data on multiple possible confounders, utilize mainly multiple linear regression and quantile analyses to test prior hypotheses and explore relations of multiple dietary and urinary variables to SBP/DBP of individuals. The 4680 INTERMAP participants are equally divided across four age/gender strata: diverse in ethnicity, education, occupation, physical activity; use of cigarettes, alcohol; diagnosed high BP, CVD, diabetes; CVD family history; women vary in parity, use of contraceptive medication and hormone replacement therapy.

Blood Pressure↗
PubMed2003

INTERMAP: the dietary data--process and quality control.

The aim of this report is to describe INTERMAP standardized procedures for assessing dietary intake of 4680 individuals from 17 population samples in China, Japan, UK and USA: Based on a common Protocol and Manuals of Operations, standardized collection by centrally trained certified staff of four 24 h dietary recalls, two timed 24-h urines, two 7-day histories of daily alcohol intake per participant; tape recording of all dietary interviews, and use of multiple methods for ongoing quality control of dietary data collection and processing (local, national, and international); one central laboratory for urine analyses; review, update, expansion of available databases for four countries to produce comparable data on 76 nutrients for all reported foods; use of these databases at international coordinating centres to compute nutrient composition. Chinese participants reported 2257 foods; Japanese, 2931; and UK, 3963. In US, use was made of 17,000 food items in the online automated Nutrition Data System. Average time/recall ranged from 22 min for China to 31 min for UK. Among indicators of dietary data quality, coding error rates (from recoding 10% random samples of recalls) were 2.3% for China, 1.4% for Japan, and UK; an analogous US procedure (re-entry of recalls into computer from tape recordings) also yielded low discrepancy rates. Average scores on assessment of taped dietary interviews were high, 40.4 (Japan) to 45.3 (China) (highest possible score: 48); correlations between urinary and dietary nutrient values--similar for men and women--were, for all 4680 participants, 0.51 for total protein, range across countries 0.40-0.52; 0.55 for potassium, range 0.30-0.58; 0.42 for sodium, range 0.33-0.46. The updated dietary databases are valuable international resources. Dietary quality control procedures yielded data generally indicative of high quality performance in the four countries. These procedures were time consuming. Ongoing recoding of random samples of recalls is deemed essential. Use of tape recorded dietary interviews contributed to quality control, despite feasibility problems, deemed remediable by protocol modification. For quality assessment, use of correlation data on dietary and urinary nutrient values yielded meaningful findings, including evidence of special difficulties in assessing sodium intake by dietary methods.

Adult↗
PubMed2003

Nutrient intakes of middle-aged men and women in China, Japan, United Kingdom, and United States in the late 1990s: the INTERMAP study.

The purpose of the study was to compare nutrient intakes among Chinese, Japanese, UK, and US INTERMAP samples, and assess possible relationships of dietary patterns to differential patterns of cardiovascular diseases between East Asian and Western countries. Based on a common Protocol and Manuals of Operations, high-quality dietary data were collected by four standardized 24-h dietary recalls and two 24-h urine collections from 17 population samples in China (three samples), Japan (four samples), UK (two samples), and USA (eight samples). There were about 260 men and women aged 40-59 years per sample--total N=4680. Quality of dietary interview and data entry were monitored and enhanced by extensive systematic ongoing quality control procedures at local, country, and international level. Four databases on nutrient composition of foods from the four countries were updated and enhanced (76 nutrients for all four countries) by the Nutrition Coordinating Center, University of Minnesota, in cooperation with Country Nutritionists. The mean body mass index was much higher for Western than East Asian samples. Macronutrient intakes differed markedly across these samples, with Western diet higher in total fat, saturated and trans fatty acids, and Keys dietary lipid score, lower in total carbohydrate and starch, higher in sugars. Based on extensive published data, it is a reasonable inference that this pattern relates to higher average levels of serum total cholesterol and higher mortality from coronary heart disease in Western than East Asian populations. The rural Chinese diet was lower in protein, especially animal protein, in calcium, phosphorus, selenium, and vitamin A. Dietary sodium was higher, potassium lower, hence Na/K ratio was higher in the Asian diet, especially for Chinese samples. This pattern is known to relate to risks of adverse blood pressure level and stroke. At the end of the 20th century, East Asian and Western diets remain significantly different in macro- and micronutrient composition. Both dietary patterns have aspects that can be regarded, respectively, as adverse and protective in relation to the major adult cardiovascular diseases. In both Asian and Western countries, public efforts should be targeted at overcoming adverse aspects and maintaining protective patterns for prevention and control of cardiovascular diseases.

Adult↗
PubMed2003

Higher blood pressure in middle-aged American adults with less education-role of multiple dietary factors: the INTERMAP study.

Extensive evidence exists that an inverse relation between education and blood pressure prevails in many adult populations, but little research has been carried out on reasons for this finding. A prior goal of the INTERMAP Study was to investigate this phenomenon further, and to assess the role of dietary factors in accounting for it. Of the 4680 men and women aged 40-59 years, from 17 diverse population samples in Japan, People's Republic of China, UK, and USA, a strong significant inverse education-BP relation was manifest particularly for the 2195 USA participants, independent of ethnicity. With participants stratified by years of education, and assessment of 100+ dietary variables from four 24-h dietary recalls and two 24-h urine collections/person, graded relationships were found between education and intake of many macro- and micronutrients, electrolytes, fibre, and body mass index (BMI). In multiple linear regression analyses with systolic BP (SBP) and diastolic BP (DBP) of individuals the dependent variables (controlled for ethnicity, other possible nondietary confounders), BMI markedly reduced size of education-BP relations, more so for women than for men. Several nutrients considered singly further decreased size of this association by > or =10%: urinary 24-h Na and K excretion, Keys dietary lipid score, vegetable protein, fibre, vitamins C and B6, thiamin, riboflavin, folate, calcium, magnesium, and iron. Combinations of these dietary variables and BMI attenuated the education-SBP inverse coefficient by 54-58%, and the education-DBP inverse coefficient by 59-67%, with over half these effects attributable to specific nutrients (independent of BMI). As a result, the inverse education-BP coefficients ceased to be statistically significant. Multiple specific dietary factors together with body mass largely account for the more adverse BP levels of less educated than more educated Americans. Special efforts to improve eating patterns of less educated strata can contribute importantly to overcoming this and related health disparities in the population.

Adult↗
PubMed2003

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↗
PubMed2001

Lattice effects observed in chaotic dynamics of experimental populations.

Animals and many plants are counted in discrete units. The collection of possible values (state space) of population numbers is thus a nonnegative integer lattice. Despite this fact, many mathematical population models assume a continuum of system states. The complex dynamics, such as chaos, often displayed by such continuous-state models have stimulated much ecological research; yet discrete-state models with bounded population size can display only cyclic behavior. Motivated by data from a population experiment, we compared the predictions of discrete-state and continuous-state population models. Neither the discrete- nor continuous-state models completely account for the data. Rather, the observed dynamics are explained by a stochastic blending of the chaotic dynamics predicted by the continuous-state model and the cyclic dynamics predicted by the discrete-state models. We suggest that such lattice effects could be an important component of natural population fluctuations.

Animals↗
PubMed1998

Resonant population cycles in temporally fluctuating habitats.

Experiments with the flour beetle Tribolium have revealed that animal numbers were larger in cultures grown in a periodically fluctuating volume of medium than in cultures grown in a constant volume of the same average size. In this paper we derive and analyze a discrete stage-structured mathematical model that explains this phenomenon as a kind of resonance effect. Habitat volume is incorporated into the model by the assumption that all rates of cannibalism (larvae on eggs, adults on eggs and pupae) are inversely proportional to the volume of the culture medium. We tested this modeling assumption by conducting and statistically analyzing laboratory experiments. For parameter estimates derived from experimental data, our model indeed predicts, under certain circumstances, a larger (cycle-average) total population abundance when the habitat volume periodically fluctuates than when the habitat volume is held constant at the average volume. The model also correctly predicts certain phase relationships and transient dynamics observed in data. The analyses involve a thorough integration of mathematics, statistical methods, biological details and experimental data.

Animals↗
PubMed1998

Provitamin A carotenoid intake and carotid artery plaques: the Atherosclerosis Risk in Communities Study.

We examined the cross-sectional association between intake of carotenoids with provitamin A activity and carotid artery plaques in 12,773 participants of the Atherosclerosis Risk in Communities Study aged 45-64 y. Usual diet was assessed with a 66-item food-frequency questionnaire. Plaques were examined by B-mode ultrasound of multiple carotid artery segments. In both women and men, those in the highest quintile of carotenoid consumption had a lower prevalence of plaques (women, 25.4%; men, 36.0%) than those in the lowest quintile of carotenoid consumption (women, 29.3%; men, 39.8%). The prevalence odds ratios contrasting extreme intake quintiles were 0.82 (95% CI: 0.70, 0.97) in women and 0.85 (95% CI: 0.72, 1.01) in men. The associations diminished slightly after potential confounders were adjusted for. In women, the inverse association was particularly strong for current smokers (adjusted odds ratio contrasting extreme quintiles: 0.67; 95% CI: 0.45, 0.98). In men, no such effect modification by smoking was seen. The inverse association was somewhat stronger in men aged 55-64 y than in those aged 45-54 y, whereas age made little difference in women. These findings, together with previous findings that carotenoid intake was unrelated to average carotid artery wall thickness, suggest that carotenoids may exert their influence later rather than earlier in the atherosclerotic process, and support the hypothesis that carotenoids or other plant-derived compounds may play a role in preventing arterial plaque formation.

Arteriosclerosis↗
PubMed1998

Effects of reducing dietary saturated fatty acids on plasma lipids and lipoproteins in healthy subjects: the DELTA Study, protocol 1.

Few well-controlled diet studies have investigated the effects of reducing dietary saturated fatty acid (SFA) intake in premenopausal and postmenopausal women or in blacks. We conducted a multicenter, randomized, crossover-design trial of the effects of reducing dietary SFA on plasma lipids and lipoproteins in 103 healthy adults 22 to 67 years old. There were 46 men and 57 women, of whom 26 were black, 18 were postmenopausal women, and 16 were men > or =40 years old. All meals and snacks, except Saturday dinner, were prepared and served by the research centers. The study was designed to compare three diets: an average American diet (AAD), a Step 1 diet, and a low-SFA (Low-Sat) diet. Dietary cholesterol was constant. Diet composition was validated and monitored by a central laboratory. Each diet was consumed for 8 weeks, and blood samples were obtained during weeks 5 through 8. The compositions of the three diets were as follows: AAD, 34.3% kcal fat and 15.0% kcal SFA; Step 1, 28.6% kcal fat and 9.0% kcal SFA; and Low-Sat, 25.3% kcal fat and 6.1% kcal SFA. Each diet provided approximately 275 mg cholesterol/d. Compared with AAD, plasma total cholesterol in the whole group fell 5% on Step 1 and 9% on Low-Sat. LDL cholesterol was 7% lower on Step 1 and 11% lower on Low-Sat than on the AAD (both P<.01). Similar responses were seen in each subgroup. HDL cholesterol fell 7% on Step 1 and 11% on Low-Sat (both P<.01). Reductions in HDL cholesterol were seen in all subgroups except blacks and older men. Plasma triglyceride levels increased approximately 9% between AAD and Step 1 but did not increase further from Step 1 to Low-Sat. Changes in triglyceride levels were not significant in most subgroups. Surprisingly, plasma Lp(a) concentrations increased in a stepwise fashion as SFA was reduced. In a well-controlled feeding study, stepwise reductions in SFA resulted in parallel reductions in plasma total and LDL cholesterol levels. Diet effects were remarkably similar in several subgroups of men and women and in blacks. The reductions in total and LDL cholesterol achieved in these different subgroups indicate that diet can have a significant impact on risk for atherosclerotic cardiovascular disease in the total population.

Adult↗
PubMed1997

Chaotic Dynamics in an Insect Population

A nonlinear demographic model was used to predict the population dynamics of the flour beetle Tribolium under laboratory conditions and to establish the experimental protocol that would reveal chaotic behavior. With the adult mortality rate experimentally set high, the dynamics of animal abundance changed from equilibrium to quasiperiodic cycles to chaos as adult-stage recruitment rates were experimentally manipulated. These transitions in dynamics corresponded to those predicted by the mathematical model. Phase-space graphs of the data together with the deterministic model attractors provide convincing evidence of transitions to chaos.

Journal Article↗
PubMed1995

Dietary antioxidants and carotid artery wall thickness. The ARIC Study. Atherosclerosis Risk in Communities Study.

BACKGROUND: Evidence that dietary antioxidants may prevent atherosclerotic disease is growing. The relationship between the intake of dietary and supplemental vitamin C, alpha-tocopherol, and provitamin A carotenoids and average carotid artery wall thickness was studied in 6318 female and 4989 male participants 45 to 64 years old int he Atherosclerosis Risk in Communities Study. METHODS AND RESULTS: Intake was assessed by use of a 66-item semiquantitative food-frequency questionnaire. Carotid artery intima-media wall thickness was measured as an indicator of atherosclerosis at multiple sites with B-mode ultrasound. Among men and women > 55 years old who had not recently begun a special diet, there was a significant inverse relationship between vitamin C intake and average artery wall thickness adjusted for age, body mass index, fasting serum glucose, systolic and diastolic blood pressures, HDL and LDL cholesterol, total caloric intake, cigarette use, race, and education (test for linear trend across quintiles of intake, P = .019 for women and P = .035 for men). An inverse relationship was also seen between wall thickness and alpha-tocopherol intake but was significant only in women (test for linear trend, P = .033 for women and P = .13 for men). There was a significant inverse association between carotene intake and wall thickness in older men (test for linear trend, P = .015), but the association weakened after adjustment for potential confounders. No significant relationships were seen in participants < 55 years old. CONCLUSIONS: These data provide limited support for the hypothesis that dietary vitamin C and alpha-tocopherol may protect against atherosclerotic disease, especially in individuals > 55 years old.

Antioxidants↗
PubMed1994

Dietary intake patterns and sociodemographic factors in the atherosclerosis risk in communities study. ARIC Study Investigators.

BACKGROUND: Comprehensive and up-to-date data on differences in dietary intake according to various sociodemographic factors are needed to understand the potential impact of dietary factors on disease risks in the United States. METHODS: Usual dietary intake assessed by a food frequency questionnaire was examined in relation to race, sex, and educational attainment using baseline data obtained from randomly selected samples of 15,800 middle-aged black and white men and women who participated in the Atherosclerosis Risk in Communities Study. RESULTS: In almost all comparisons, higher educational attainment was associated with recommended dietary intake patterns--lower per energy intakes of meats, eggs, chicken with skin, and whole milk and higher intakes of fruits, vegetables, fish, chicken without skin, and low-fat milk. As expected from these food intake patterns, higher educational attainment was associated with lower intakes of saturated fatty acid and cholesterol and with higher intakes of dietary fiber and various micronutrients. Compared with women's diets, men's diets were slightly more atherogenic (in whites only) based upon Keys score and had lower micronutrient levels. Although there were large differences in the food intakes between blacks and whites, the differences in nutrient intakes were generally smaller. However, intakes of cholesterol and vitamin A were somewhat higher and intakes of saturated fatty acid, calcium, and potassium were lower among blacks than in whites. CONCLUSIONS: This community-based study clearly demonstrated that regardless of race and sex, high educational attainment is associated with recommended dietary intake patterns. Continuing efforts to improve general educational level and to promote healthy dietary habits among those with low socioeconomic status are warranted.

Black or African American↗
PubMed1994

Neurocognitive abilities for a clinically depressed sample versus a matched control group of normal individuals.

Depressed patients have been reported to show deficits in tasks that demand memory, planning/sequencing, speeded responding, and effortful responding. Many studies of depressed patients have used inadequate instrumentation or poor control groups. In this investigation, the cognitive performance of 44 patients diagnosed as clinically depressed was compared with the performance of a control group of normal individuals that closely matched the clinical group on the variables of age, gender, race or ethnic group, and educational attainment. The groups were compared on the tasks that compose the Kaufman Adolescent and Adult Intelligence Test (KAIT), which includes reliable and valid measures of most pertinent areas of purported deficit in depressed patients. Multivariate analyses of variance indicated that the depressed and control groups did not differ significantly on KAIT variables, but the depressed patients did differ significantly from the control group on the delayed versus immediate recall of verbal information.

Adolescent↗
PubMed1993

Acquired lymphedema: a chart review of nine women's responses to intervention.

The medical records of nine women who had acquired lymphedema as a sequela to a modified radical mastectomy for breast cancer were analyzed to ascertain what factors, phenomena, or experiences in their lymphedema treatment may have influenced outcomes. The women were identified as having either successful or poor outcomes. Their conservative lymphedema treatment consisted of compression pumps, compression garments, and, in some cases, manual lymph drainage. The qualitative analysis of records implicated the following factors in the outcome of conservative lymphedema treatment for these women: (a) the amount of delay before starting compression treatment, (b) the size of the lymphedematous arm when treatment started, (c) the availability of social and financial supports, and (d) the presence of complicating health problems. The findings of this study cannot be generalized; however, further scientific inquiry into the phenomena that lie behind treatment outcome variations could lead to more effective treatment approaches.

Adult↗
PubMed1992

Emergency department complaint frequency: variation by patient median household income.

STUDY OBJECTIVE: To determine whether emergency department complaint frequency varies with patient median household income, as approximated by patient residence zip code. DESIGN: All patient visits and complaints received in one ED were reviewed. Median household income of patient residence zip codes was obtained from available demographic data. Patients were categorized into seven income categories. EXCLUSIONS: Cases in which zip codes could not be determined or zip code income data could not be obtained; complaints from physicians, not patients; and data from zip codes remote from the hospital. SETTING: Nine hundred twenty-nine-bed teaching hospital. TYPE OF PARTICIPANTS: All ED visits and all ED complaints over a four-year period. STATISTICAL ANALYSIS: Armitage's chi 2 test for trend of proportions was used to compare complaint frequencies in different income groups. RESULTS: A total of 277,210 patient visits and 675 complaints met study criteria. Complaint frequencies ranged from 1.65 to 3.14 per thousand visits. Higher-income patients were more likely to complain than lower-income patients (P = .0000058). CONCLUSION: In this setting, ED patients residing in higher median income zip codes are more likely to register complaints than those from lower-income zip codes. Complaint frequencies from hospitals with different demographics may not be comparable.

Emergency Service, Hospital↗
PubMed1991

HL7: facilitating multiple approaches to systems integration.

System interfaces of the 1980s are being replaced by system integration of the 1990s. Standards such as Health Level 7 (HL7) are facilitating this integration process. The authors dispel several persistent misconceptions about the HL7 standard and illustrate two working approaches to HL7-based networking.

Computer Communication Networks↗