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Biomedical subjects

C E Davis

Publications and source records attributed to C E Davis.

At least 55 records · Page 3Linked to original sources
PubMed1998

Thermal inactivation of Escherichia coli O157:H7, Salmonella senftenberg, and enzymes with potential as time-temperature indicators in ground turkey thigh meat.

The USDA Food Safety and Inspection Service has proposed to amend cooking regulations to require that any thermal process used for poultry products be sufficient to cause a 7 D reduction in salmonellae. Several enzymes have been suggested as potential indicators of heat processing in poultry, yet no relationship between the inactivation rates of these enzymes and salmonellae had been determine. The thermal inactivation kinetics of endogenous muscle proteins. Escherichia coli O157:H7 and Salmonella senftenberg were compared in ground turkey thigh meat in thermal death time studies. Bacteria counts were determined and muscle extracts were assayed for residual enzyme activity or protein concentration D and zeta values were calculated using regression analysis. S. senftenberg had higher D values at all temperatures and was more heat resistant than E. coli. The zeta values of E. coli on Petrifilm Coliform Count plates and phenol red sorbitol agar plates were 6.0 and 5.7 degrees C, respectively. The zeta values of S. senftenberg were 5.6 and 5.4 degrees C on Petrifilm and agar, respectively. Lactate dehydrogenase (LDH) was the most heat stable protein at 64 degrees C. LDH, glyceraldehyde-3-phosphate dehydrogenase, creatine kinase, triose phosphate isomerase (TPI), acid phosphatase, serum albumin, and immunoglobulin G had zeta values of 3.8,4.3,4.8,5.8,6.3,6.7, and 8.6 degrees C, respectively , in turkey containing 4.3% fat. The zeta values for TPI decreased to 5.4 degrees C in thigh meat containing 9.8% fat. Temperature function of TPI was most similar to that of S. senftenberg, suggesting it might function as an endogenous time-temperature integrator to monitor adequacy of processing when a performance standard based on this pathogen is implemented.

Acid Phosphatase↗
PubMed1998

Evaluation of a rapid method for measurement of catalase activity in cooked beef and sausage.

Catalase (CAT) activity in ground beef and pork was determined on samples cooked from 60 to 71.1 degrees C. One-gram samples of ground round (4% fat), hamburger (24% fat), and commercial pork sausage (38%fat) were cooked in a controlled-temperature waterbath at 65, 68.3 and 71 degrees C. Chilled samples were immersed in direct contact with the cooking water; the test samples were removed every 15 s and immediately immersed in an ice-water bath (O to 1 degrees C) to quick-chill the samples to prevent temperature over-run. Samples retained high (HMB value 20+, over range) CAT activity through 90, 60, and 45 s at 65, 68.3, and 71 degrees C, respectively, before showing rapid activity decreases. Four USDA-FSIS approved meat patty heating processes (66.1 degrees C, 41 s; 67.2 degrees C, 26 s; 68.3 degrees C, 16 s; and 69.4 degrees C, 10 s) were analyzed for CAT activity in meat frozen prior to cooking was slightly lower (P < 0.05) than in degrees C meat. CAT activity decreased (P < 0.05) among meat treated at 66.1 degrees C for 41 s, at 67.2 degrees C for 26 s, and at 68.3 degrees C for 16 s, but the treatment at 68.3 degrees C for 16 s was not different (P < 0.05) from that at 69.4 degrees C for 10 s. These results show this rapid (20 to 25 min) CAT activity test could be used to establish activity values at specific end-point temperatures for model heat-processed ground beef or sausage products and may be useful to USDA FSIS process inspectors and food processors in quality assurance and HACCP (hazard analysis critical control points) programs for thermal input verification.

Animals↗
PubMed1997

Circulating adhesion molecules VCAM-1, ICAM-1, and E-selectin in carotid atherosclerosis and incident coronary heart disease cases: the Atherosclerosis Risk In Communities (ARIC) study.

BACKGROUND: Recruitment of circulating leukocytes at sites of atherosclerosis is mediated through a family of adhesion molecules. The function of circulating forms of these adhesion molecules remains unknown, but their levels may serve as molecular markers of subclinical coronary heart disease (CHD). METHODS AND RESULTS: To determine the ability of circulating vascular cell adhesion molecule-1 (VCAM-1), endothelial-leukocyte adhesion molecule-1 (E-selectin), and intercellular adhesion molecule-1 (ICAM-1) to serve as molecular markers of atherosclerosis and predictors of incident CHD, we studied 204 patients with incident CHD, 272 patients with carotid artery atherosclerosis (CAA), and 316 control subjects from the large, biracial Atherosclerosis Risk In Communities (ARIC) study. Levels of VCAM-1 were not significantly different among the patients with incident CHD, those with CAA, and control subjects. Higher levels of E-selectin and ICAM-1 were observed for the patients with CHD (means [ng/mL]: E-selectin, 38.4; ICAM-1, 288.7) and those with CAA (E-selectin, 41.5; ICAM-1, 283.6) compared with the control subjects (E-selectin, 32.8; ICAM-1, 244.2), but the distributions were not notably different between the patients with CHD and CAA. Results of logistic regression analyses indicated that the relationship of ICAM-1 and E-selectin with CHD and CAA was independent of other known CHD risk factors and was most pronounced in the highest quartile. The odds of CHD and CAA were 5.53 (95% CI, 2.51-12.21) and 2.64 (95% CI, 1.40-5.01), respectively, for those with levels of ICAM-1 in the highest quartile compared with those in the lowest quartile. Odds of CAA were 2.03 (95% CI, 1.14-3.62) for those with levels of E-selectin in the highest quartile compared with those in the lowest quartile. CONCLUSIONS: These data indicate that plasma levels of ICAM-1 and E-selectin may serve as molecular markers for atherosclerosis and the development of CHD.

Arteriosclerosis↗
PubMed1997

Estimating the mean hazard ratio parameters for clustered survival data with random clusters.

We consider a latent variable hazard model for clustered survival data where clusters are a random sample from an underlying population. We allow interactions between the random cluster effect and covariates. We use a maximum pseudo-likelihood estimator to estimate the mean hazard ratio parameters. We propose a bootstrap sampling scheme to obtain an estimate of the variance of the proposed estimator. Application of this method in large multi-centre clinical trials allows one to assess the mean treatment effect, where we consider participating centres as a random sample from an underlying population. We evaluate properties of the proposed estimators via extensive simulation studies. A real data example from the Studies of Left Ventricular Dysfunction (SOLVD) Prevention Trial illustrates the method.

Adult↗
PubMed1997

Comparison of attitudes and behaviors related to nutrition, body size, dieting, and hunger in Russian, black-American, and white-American adolescents.

Attitudes and behaviors related to nutrition are known to differ between white-American and black-American adolescents, however, little is known about teenagers from Russia. We hypothesized that, compared with white-American or black-American teenagers, Russian teenagers would prefer a larger body size, be less likely to diet, and be less concerned about being overweight. Self-administered questionnaires were completed by 196 students in Moscow, 326 white-American, and 239 black-American adolescents who attended school in North Carolina (mean age = 16). Ideal body mass index (BMI) was calculated from measured height and the response to the question, "What do you consider to be your ideal weight?" Mean ideal BMI was higher in black-American boys (25.1) and girls (21.4) than in white-American boys (22.1) and girls (19.2), and Russian boys (21.8) and girls (19.1). After controlling for BMI, black-American girls were less than half as likely to report dieting compared with white-American girls. There were no significant differences among white-American girls and Russian girls, and there were no ethnic differences between boys in the prevalence of dieting. White-American girls and black-American girls were much more likely to identify being overweight as an important nutritional concern than were Russian girls (odds ratios > 10), and there were no ethnic differences among boys. We conclude that preferences for body size, the prevalence of dieting, and concerns about being overweight were similar in Russian and white-American teens, with the exception of Russian teenaged girls who were less likely than American girls to identify being overweight as an important concern. Overall, weight-related attitudes and behaviors in Russian teenagers were more similar to those of white-American teenagers than those of black-American teenagers.

Adolescent↗
PubMed1997

Familial components of the multiple metabolic syndrome: the ARIC study.

The association of a parental history of diabetes mellitus and hypertension with the multiple metabolic syndrome (MMS) was studied in a population survey of middle-aged adults. The eligible population was drawn from the baseline examination of the Atherosclerosis Risk in Communities Study, a population-based, bi-ethnic, multi-centre cohort study. The MMS was defined as a multivariate, categorical phenotype of co-occurring diabetes, hypertension, and dyslipidaemia. MMS cases (n = 356) were compared to disorder-free control subjects (n = 6797) with respect to their parental history of diabetes and hypertension. MMS cases were more likely to report a history of diabetes in both parents (odds ratio [OR] 4.7, 95 % confidence interval (CI) 1.5-14.7) or a history of hypertension in both parents (OR 1.9, 95 % CI 1.1-3.0) than control subjects, adjusting for BMI, waist-to-hip ratio, age, gender, and ethnicity/centre. A parental history of diabetes and hypertension in both parents was associated with the greatest increase in odds of MMS (OR 8.3, 95 % CI 3.0-22.8). A dose-response relationship between the number of parental disorders (one; two; three to four) and the odds of MMS was observed (OR 1.2, 95 % CI 0.9-1.7; OR 2.0, 95 % CI 1.4-2.8; OR 4.0, 95 % CI 2.5-6.2). Based on the marked associations observed between a parental history of MMS components and the clustering of these metabolic disorders in the offspring generation, we conclude that genetic and/or non-genetic familial influences play a role in the development of the multiple metabolic syndrome.

Case-Control Studies↗
PubMed1997

Secondary endpoints can be validly analyzed, even if the primary endpoint does not provide clear statistical significance.

Response variables from clinical trials are often divided into those considered primary and those considered secondary to the purposes of the study. If the difference between treatment groups on primary outcomes is not significant, the interpretation of significant differences in secondary response variables may be difficult because of multiple comparisons. It is proposed that the comparison on the primary outcome use a significance level of alpha and that the secondary endpoints be evaluated using a significance level alpha/(k + 1), where k is the number of secondary outcomes to be evaluated. Examples from recently completed clinical trials illustrate the use of this rule.

Clinical Trials as Topic↗
PubMed1997

Changes over time in blood lipids and their correlates in Polish rural and urban populations: the Poland-United States Collaborative Study in cardiopulmonary disease epidemiology.

PURPOSE: The purpose of this manuscript is to examine changes in blood lipid levels and related factors between 1983 and 1987 in two selected Polish populations, to evaluate these changes and their association with other coronary heart disease (CHD) risk factors, and to examine the nutrient intake changes for consistency with observed lipid changes. METHODS: Men and women, aged 35-64 were screened from Warsaw and rural Tarnobrzeg province, Poland-the Pol-MONICA screening sites. An independent random sample of 5132 screened in 1983-84 and a second independent random sample of 2596 screened in 1987-88 were compared. A 25% cohort of the 1983-84 sample was also rescreened in 1987-88 (n = 1236) and 24-hour dietary recall information on this cohort was used to evaluate nutrient intake changes and their relationship to the lipid changes. RESULTS: For the random samples, the total cholesterol increased by 5.1 mg/dL (rural) and by 7.9 mg/dL (urban) for women; there were no significant changes among men. Low-density lipoprotein cholesterol (LDL-C) increased for all site and gender subgroups by 5.4-8.7 mg/dL. Among rural men and women, high-density lipoprotein cholesterol (HDL-C) decreased by 3.4 and 3.3 mg/dL, respectively, whereas it increased by 3.3 mg/dL among urban women and did not change among urban men. Total triglycerides (TG) increased by 9.5 mg/dL for rural men, with no significant change for rural women. For urban men and women, TG decreased by 29.5 and 21.8 mg/dL respectively. In the cohort, changes in dietary intake (decreases in energy from fat, Keys index and increases in the polyunsaturated to saturated fats ratio) were related to a decrease in TC at both sites and to a decrease or smaller increase in LDL-C for rural men. CONCLUSIONS: The observed changes were generally unfavorable, with a decrease in the proportion of persons with desirable lipid levels. At both sites nutritional changes were favorable, including a drop in total energy intake. Less pronounced were changes in percentages of total energy from fats, where the only significant decrease was for rural women; however, improvements in dietary fat composition and declines in cholesterol consumption were found. These favorable changes in diet were not strong enough or were not in effect long enough to counter the unfavorable changes in blood lipids.

Adult↗
PubMed1997

Development of the multiple metabolic syndrome in the ARIC cohort: joint contribution of insulin, BMI, and WHR. Atherosclerosis risk in communities.

PURPOSE: The natural history of the multiple metabolic syndrome (MMS) and its predictors has rarely been addressed in population samples. This study evaluated the predictive role of fasting serum insulin, body mass index (BMI), and waist-to-hip ratio (WHR) on the development of incident MMS components (diabetes, hypertension, and dyslipidemias) over the course of three years. METHODS: The study population comprised the cohort of middle-aged African American and European American men and women of the Atherosclerosis Risk in Communities Study (1987-1992). RESULTS: Among 6113 individuals free of MMS components at baseline, high insulin (> 14 microU/ ml) was independently predictive of the development of one or more MMS components (OR:1.5, 95% CI:1.2-1.8), as was a BMI > or = 30 (OR:1.7, 95% CI:1.4-2.0), and a high WHR (> 0.98) (OR:1.5, 95% CI:1.3-1.8) adjusting statistically for age, gender, and ethnicity/center. These associations were markedly stronger for combinations of MMS components (two or more) than for isolated components. CONCLUSIONS: The findings confirm earlier reports on the predictive role of insulin, BMI, and WHR, and suggest that these antecedent factors may be integral to the development of combinations of disorders, i.e., the particular clustering identified as the MMS.

Analysis of Variance↗
PubMed1997

Racial differences in risk factors for atherosclerosis. The ARIC Study. Atherosclerosis Risk in Communities.

This paper describes black/white differences in risk factors for atherosclerosis in the large multicenter Atherosclerosis Risk in Communities (ARIC) Project sponsored by the National Heart, Lung, and Blood Institute. It is based on data collected at baseline in ARIC's four geographically distinct clinical centers. Participants were randomly selected (4264 black and 11,479 white men and women, ages forty-five to sixty-four years at entry). There were striking differences in obesity between black and white women, higher fasting glucose and greater prevalence of diabetes in blacks, and lower high-density lipoprotein values in white men. Not unexpectedly, blood pressure in black participants exceeded that in whites. Clustering of multiple risk factors was more common in the black population. Conversely, prevalence of no risk factors was greatest among whites. In conclusion, while African-Americans and Caucasians share much the same group of risk factors for atherosclerosis, there are clinically important racial differences in emphasis.

Arteriosclerosis↗
PubMed1996

Sex difference in high density lipoprotein cholesterol in six countries.

It is known that women have higher levels of high density lipoprotein (HDL) cholesterol than men. The authors examined the association between HDL cholesterol and biologic sex in 8,631 women and 10,690 men aged 45-54 years from six countries studied between 1972 and 1989. The variation in the sex difference for HDL cholesterol was significant; the smallest difference (0.06 mmol/liter) was seen in China and the largest (0.40 mmol/liter) in Canada. Adjustment for differences in body mass index, smoking, alcohol use, and heart rate reduced but did not eliminate the variability. The sex difference in HDL cholesterol levels, usually assumed to be due to biologic factors, differs across cultures and may be related to environmental factors.

Arteriosclerosis↗
PubMed1996

Blood pressure and heart rate response during exercise in men and women in the USA and Russia lipid research clinics prevalence study.

Examination of blood pressure (BP) and heart rate (HR) measurements at rest and during exercise in samples of USA and Russian middle-aged men and women show significant differences between countries for both genders. Russian men had higher resting systolic blood pressure (SBP) than USA men but lower SBP at both stages of exercise. Russian women had significantly higher resting SBP than USA women at rest and also during exercise. Russian men and women had significantly lower HR at rest and during exercise than USA men and women. Differences between countries were also noted for mean body weight, height, lipid levels, percentages of smokers and several other variables, and it was postulated that differences in these factors might be responsible in part for differences in SBP and HR during exercise. After adjustment for these variables, differences in SBP during exercise between USA and Russian men remained, but differences between USA and Russian women disappeared. For both genders, differences in HR during exercise remained after adjustment. Mortality analyses in USA and Russian men indicated that stage 2 SBP response during exercise was generally not a significant mortality risk factor after adjustment for age, BMI, TC, smoking and resting SBP. In a similar model, stage 2 HR response during exercise was also a non-significant risk factor in mortality.

Adult↗
PubMed1996

Clustering of dyslipidemia, hyperuricemia, diabetes, and hypertension and its association with fasting insulin and central and overall obesity in a general population. Atherosclerosis Risk in Communities Study Investigators.

Clustering of elevated triglycerides, decreased high-density lipoprotein cholesterol (HDL-C), hyperuricemia, diabetes, and hypertension has been related to insulin resistance/high insulin levels and central and/or overall obesity. The extent to which these abnormalities cluster and whether hyperinsulinemia, central adiposity, and overall obesity each independently associate with this clustering were evaluated in 14,481 US whites and African-Americans 45 to 64 years of age. With the exception of hypertension, abnormalities rarely existed in isolated form. Clustering greatly exceeded chance association (P < .001). Although this clustering was greater in relative terms (ratio of observed to expected cluster frequency) in the lean and less centrally obese, it was greater in absolute terms (observed minus expected cluster frequency as a percent of total population) in the more centrally and more generally obese. The greatest excesses were found for clusters that included both hypertriglyceridemia and low HDL-C. Multiple logistic regression models showed strong and independent graded relationships of clusters with quintiles of fasting insulin (fifth quintile odds ratio, 10 to 54, P < .001) and to a lesser degree with quintiles of the waist to hip ratio (2.2 to 5.4, P < .001 for most) and of body mass index (1.6 to 4.5, P < .05 for most). In conclusion, all abnormalities cluster in excess of that predicted by chance, with clusters showing remarkable and graded independent associations with fasting hyperinsulinemia and to a lesser extent with central and overall obesity. Thus, a metabolic syndrome occurs in both lean and obese middle-aged US adults.

Cluster Analysis↗
PubMed1996

Poland and United States Collaborative Study on Cardiovascular Epidemiology. A comparison of HDL cholesterol and its subfractions in populations covered by the United States Atherosclerosis Risk in Communities Study and the Pol-MONICA Project.

HDL cholesterol (HDL-C) levels are inversely related to coronary heart disease (CHD) risk, and HDL-C distributions vary among countries. Poland is one of the few developed countries in which CHD rates are increasing at the same time that US rates have been falling, but whether these differences are explained by differences in risk factors such as HDL-C has not been determined. To examine this possibility, levels of HDL-C and its subfractions were compared in US and Polish urban and rural men and women aged 45 to 64 years. Age-adjusted HDL-C means were 0.20 mmol/L higher in urban Polish men and 0.37 mmol/L higher in rural Polish men than in their US counterparts (P < .0001); means in urban Polish women were 0.06 mmol/L higher (P < .05) and in rural Polish women 0.09 mmol/L higher (P < .001) than in their US counterparts. Adjustment for age, education, alcohol intake, smoking, BMI, heart rate, and menopause status (in women) had little effect on differences. Means of HDL2 and HDL3 levels showed similar between-country differences, although differences were minimal for HDL2 in urban men and women, and HDL3 means did not differ between rural women. BMI was inversely related to HDL-C and both subfractions in all gender-country-site strata (P < .001), and alcohol was directly related to HDL-C (P < .001) in all strata except Polish women. Cigarette smoking was negatively related to HDL-C and both subfractions in all US samples except HDL2 in urban men, whereas in Polish samples, significant associations were found only in urban women for HDL-C and in rural and urban women for HDL3. Age, heart rate, and education showed inconsistent or no association with HDL-C and its subfractions in either country. This profile of HDL-C and its subfractions in Polish samples contrasts sharply with the opposite trend in CHD mortality rates, which suggests either that other risk factors may account for the trends or that the relationship between HDL-C and CHD may differ between the two countries.

Age Factors↗
PubMed1996

Race and gender differences in the association of Lp(a) with carotid artery wall thickness. The Atherosclerosis Risk in Communities (ARIC) Study.

The association of lipoprotein(a) [Lp(a)] with preclinical atherosclerotic disease is not well established in any race group, particularly African Americans. This report examined the association of Lp(a) with preclinical extracranial carotid atherosclerosis in middle-aged black and white participants in the Atherosclerosis Risk in Communities (ARIC) Study. Study participants (15 124: 2417 black women, 1522 black men, 5907 white women, and 5278 white men) who were 45 to 64 years old at baseline were examined during the period 1987 to 1989. Carotid intimal-medial far-wall thickness was determined by B-mode ultrasonography and expressed as the overall wall thickness mean at six sites to approximate atherosclerosis in the carotid system. Lp(a) was measured as its total protein component, Lp(a) protein, by a double-antibody ELISA for apolipoprotein(a) detection. Mean Lp(a) protein levels were higher in blacks than whites (169.1 and 147.0 microgram/mL in black women and black men, respectively, compared with 86.6 and 75.1 micrograms/mL in white women and white men). Mean carotid wall thickness (in millimeters) varied by race and gender: 0.798 in white men, 0.779 in black men, 0.718 in black women and 0.695 in white women. Multivariable-adjusted Lp(a) protein was independently associated with wall thickness (in millimeters) in white men and black men; among women, however, this association appeared to be stronger when smoking and diabetes were present. A 100-microgram/mL difference in Lp(a) protein was associated with 0.049- and 0.043-mm higher wall thickness values in black men and white men, respectively. Among white women who smoked, the difference in wall thickness was 0.051 mm compared with 0.032 mm for former/never smokers and 0.21 mm in black female diabetics compared with 0.031 mm in black female nondiabetics. These results suggest that Lp(a) is associated with preclinical carotid atherosclerosis in both blacks and whites, but that this association may be affected by the presence of other cardiovascular risk factors, particularly in women.

Age Factors↗
PubMed1995

Association of fibrinolytic parameters with early atherosclerosis. The ARIC Study. Atherosclerosis Risk in Communities Study.

BACKGROUND: Thrombosis, provoked by a rupture of an atherosclerotic plaque, plays a crucial role in precipitating a coronary heart disease event. Its role at the early stage of atherosclerosis has, however, been unclear, but it has been hypothesized that thrombosis or defective fibrinolysis contributes to the progression of atherosclerotic lesions. METHODS AND RESULTS: We studied the association of plasminogen activator inhibitor antigen (PAI-1), tissue-type plasminogen activator antigen (TPA), and D-dimer with early atherosclerosis in a cross-sectional case-control study involving 457 pairs chosen from the biracial cohort of the Atherosclerosis Risk in Communities (ARIC) Study. As examined by B-mode ultrasound, patients (cases) had intima-media thickness of carotid arteries above the 90th percentile and control subjects had thickness below the 75th percentile of the ARIC cohort. Persons with a history of heart disease, stroke, or claudication were excluded from the case-control selection. PAI-1, TPA, and D-dimer were higher in patients than in control subjects (P < or = .001, Wilcoxon signed rank statistic). In conditional logistic regression analyses, the odds ratios of carotid atherosclerosis were, for PAI-1, for example, 1.22, 1.54, and 1.60 in the second, third, and fourth quartiles compared with the first quartile (P < .0001, test of linear trend, adjusting for age, systolic blood pressure, total cholesterol, acetylsalicylic acid use, and time of blood draw). Corresponding tests for D-dimer and TPA also showed an increasing trend (P < .0001). CONCLUSIONS: The findings support the hypothesis that thrombosis and fibrinolysis play a role at the early stage of the atherosclerotic process.

Arteriosclerosis↗