Search PubMed⌕ Search

Biomedical subjects

J M Flack

Publications and source records attributed to J M Flack.

At least 55 records · Page 3Linked to original sources
PubMed1995

Cardiac function in smokers and nonsmokers: the CARDIA study. The Coronary Artery Risk Development in Young Adults Study.

OBJECTIVES: This study assessed clinical and echocardiographic measures of cardiac function at rest in smokers and nonsmokers to determine the associations of cigarette smoking with various measures of left and right ventricular performance. BACKGROUND: Whereas the immediate cardiovascular effects of cigarette smoking have been well described, the long-term effects in an otherwise healthy cohort have not. Of particular interest were associations with heart rate, left ventricular end-systolic stress and left ventricular mass because higher levels of these measures would suggest increased myocardial oxygen consumption. METHODS: In year 5 of the Coronary Artery Risk Development in Young Adults (CARDIA) study, 3,366 smokers and nonsmokers (ex-smokers were excluded) underwent echocardiography as well as assessment of heart rate, anthropometric measurements and blood pressure. Participants ranged in age from 23 to 35 years and were equally distributed by race and gender. Echocardiographic measures included pulsed Doppler pulmonary artery acceleration time (a decrease suggests increased pulmonary artery pressure), left ventricular mass, left ventricular end-systolic stress and left ventricular fractional shortening. RESULTS: All comparisons were between smokers and nonsmokers. Heart rate at rest was significantly higher in smokers by 1.5 to 5 beats/min in all race/gender groups except black men. In men who smoked, pulmonary artery acceleration time was significantly lower by 4 to 8 ms. Except for black male smokers, there was a trend toward increased left ventricular mass (3 to 8 g) in all race/gender groups, significant in black women. Left ventricular end-systolic stress was significantly higher in women who smoked (4 to 6 dynes/cm2). There were no differences for systolic blood pressure or left ventricular fractional shortening. CONCLUSION: In an assessment of cardiovascular function at rest in young adults, quantifiable differences between smokers and nonsmokers that predict increased rest myocardial oxygen consumption in smokers were found. Some of these differences were gender specific.

Adolescent↗
PubMed1995

Epidemiology of minority health.

Collecting epidemiologic data by ethnicity and race is a highly useful undertaking; but "bench mark" comparisons relative to majority Americans should not take priority over defining the determinants of health status within a minority group. Thus, it is necessary to identify factors contributing to the measured health status and to modify the environment, lifestyles, and behaviors to diminish the likelihood of undesirable health outcomes. This article presents an overview of the health status of African Americans, Asians and Pacific Islanders, and Hispanics. The goals are to provide a framework for the rational interpretation of both health status data and its determinants both within and between minority groups. This approach recognizes the heterogeneity of health status that exists within a minority group and encourages investigators to place more emphasis on the within-group health status differentials as they search for modifiable factors that underlie the risk for undesirable health outcomes.

Adolescent↗
PubMed1995

Alcohol consumption and physical fitness among young adults.

The relationship between alcohol consumption and physical fitness was analyzed using data from the baseline examination of the Coronary Artery Disease Risk Development In Young Adults study (CARDIA), a longitudinal study of the evolution of risk factors for cardiovascular disease in Black and White men and women aged 18-30 years. Two parameters of submaximal exercise treadmill testing were evaluated: time to heart rate 130 and duration of the treadmill test. In men and women qualified for treadmill testing, time to reach heart rate 130 was positively associated with ethanol intake. The relationship between fitness and ethanol intake persisted in sex-specific analysis after adjustment for age, ethnicity, systolic blood pressure, sum of subscapular and triceps skinfolds, and physical activity level. The magnitude and strength of the relationship were greater in women than in men. A negative interaction between ethanol intake and smoking status was evident. Linear regression coefficients in men were 0.29 sec to heart rate 130/ml ethanol/day in nonsmokers and -0.06 sec to heart rate 130/ml ethanol/day in smokers. Linear regression coefficients in women were 1.07 sec to heart rate 130/ml ethanol/day in nonsmokers and 0.23 sec to heart rate 130/ml ethanol/day in smokers. Men and women who smoked showed 31 sec longer time to heart rate 130, regardless of ethanol intake. Mean daily ethanol intake was positively associated with duration of treadmill testing in women, but weakly associated with duration in men. These results show increased physical fitness as ethanol intake increased in women and nonsmoking men and mildly decreased physical fitness as ethanol consumption increases among men who smoke.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

Concentrations of Lp(a) in black and white young adults: relations to risk factors for cardiovascular disease.

The purpose of this report is to compare the distribution of total lipoprotein(a) [Lp(a)] mass in a population-based sample of blacks and whites, and to investigate the association of Lp(a) with other cardiovascular risk factors. A cross-sectional study design was used. Black and white men and women (n = 4125), aged 23-35 from the Coronary Artery Risk Development in Young Adults Study had the following data collected: Lp(a), lipids and lipoproteins, other metabolic parameters, anthropometry, physical activity, dietary intake, cigarette use, and alcohol use. Blacks had concentrations of Lp(a) approximately three-fold higher than whites. Medians were: black men 21.5 mg/dL, black women 23.9 mg/dL, white men 6.1 mg/dL, and white women 6.4 mg/dL. Lp(a) concentrations were higher in women than in men. Lp(a) was not consistently associated with smoking, alcohol consumption, physical activity, dietary fat, or obesity. In stepwise regression analyses in both blacks and whites, Lp(a) was consistently associated with low-density lipoprotein (LDL) cholesterol, fibrinogen, and apoB; regression models explained about 7% of the variance in Lp(a). In whites, Lp(a) tended to be higher in those with a positive family history of myocardial infarction. The large differences in Lp(a) between blacks and whites, and the absence of association with many other variables are consistent with previous suggestions that Lp(a) concentration is in large part genetically determined. The association of Lp(a) with LDL and fibrinogen, two strong risk factors for cardiovascular disease (CVD), could represent part of the mechanism of the CVD risk associated with Lp(a) in other studies. Longitudinal data are needed to determine the extent to which Lp(a) will independently predict disease, especially in diverse ethnic groups.

Adult↗
PubMed1994

Urinary albumin and N-acetyl-beta-D-glucosaminidase excretions in mild hypertension.

Renal effects of mild hypertension and therapy have not been established. Since urinary albumin and N-acetyl-beta-D-glucosaminidase excretions reflect renal effects of hypertension, they were related to blood pressure, other cardiovascular risk factors, cardiac target organ effects, and response to therapy in mild hypertension (diastolic blood pressure 85-99 mm Hg). Participants were from two clinics of the Treatment of Mild Hypertension Study (TOMHS), a multicenter randomized, double-blind, controlled trial. Participants received nutritional-hygienic therapy and one of five active drugs or placebo. Urinary albumin and N-acetyl-beta-D-glucosaminidase excretions were assessed prospectively using office "spot" collections from one clinic (n = 213) and retrospectively using overnight collections from the other clinic (n = 210). Relationships were determined between protein excretions and blood pressure, age, gender, race, blood glucose, cholesterol concentrations, and indices of body mass and left ventricular mass and function at baseline. Treatment effects were assessed after 3 to 12 months. Spot and overnight albumin excretions related positively to baseline systolic blood pressure by univariate analyses. Spot albumin excretion related positively to systolic blood pressure, age, creatinine clearance, and left ventricular function while overnight albumin excretion related positively to left ventricular mass and female gender by multiple regression analyses. Spot, but not overnight, albumin excretion declined significantly with active drug therapy. N-acetyl-beta-D-glucosaminidase excretion did not relate to blood pressure or decline with therapy. The combined results suggest albumin excretion correlates with blood pressure, decreases with antihypertensive drug therapy, and is associated with greater left ventricular function and mass, as well as glomerular filtration rate, even at mild levels of hypertension.

Acetylglucosaminidase↗
PubMed1994

Metabolic correlates of theophylline therapy: a concentration-related phenomenon.

OBJECTIVE: To determine the relationship of serum theophylline concentration with electrolyte and glucose abnormalities across a broad range of theophylline concentrations. DESIGN: Retrospective review of a computerized laboratory database between June 1, 1984 and June 1, 1986. SETTING: A midwestern university medical center. PATIENTS: Eight hundred sixty-nine patients with serum theophylline concentrations of > 5.5 mumol/L and a random unmatched sample (control group) of 350 in- and outpatient adults and children with no history of reactive airways disease or theophylline exposure. RESULTS: Patients with measurable theophylline had a higher risk of hypokalemia, hyponatremia, hyperglycemia, hypophosphatemia, and hypomagnesemia compared with the unexposed control group. Unadjusted odds ratios (OR) were: (1) hypokalemia OR = 4.2 (95 percent CI 2.2 to 7.9); (2) hyponatremia OR = 5.4 (95 percent CI 2.0 to 12.9); (3) hypomagnesemia OR = 1.6 (95 percent CI 1.0 to 2.5); (4) hyperglycemia OR = 2.3 (95 percent CI 1.7 to 3.0); and (5) hypophosphatemia OR = 2.7 (95 percent CI 1.2 to 5.3). A linear concentration-response relationship was documented between serum theophylline concentration and all metabolic disturbances. CONCLUSIONS: Measurable theophylline was associated with increased risk for glucose and electrolyte abnormalities in a concentration-related fashion across a broad range of theophylline concentrations from 5.5 to > or = 110 mumol/L.

Case-Control Studies↗
PubMed1994

Treatment of hypertension in the presence of coexisting medical conditions.

Treating hypertension reduces morbidity and mortality. Unfortunately, hypertension often exists in patients with other medical conditions. In these patients, the selection of an antihypertensive agent is often influenced by the presence of the coexisting condition. Conversely, the treatment of the coexisting medical condition may be influenced by the presence of hypertension. Given the vast array of antihypertensive medications available today, appropriate treatment of both hypertension and coexisting conditions can be achieved with careful selection of medications. This review discusses factors to consider when treating elderly patients with hypertension with the following coexisting conditions: dyslipidaemia, glucose intolerance, sexual dysfunction, cardiovascular disease, pulmonary disease, renal disease and neuropsychiatric disorders. Hypothyroidism, hyperthyroidism and various states of high cardiac output may cause hypertension. These conditions should be identified, since they are often treatable with subsequent resolution of the hypertension.

Aged↗
PubMed1993

Plasma fibrinogen: levels and correlates in young adults. The Coronary Artery Risk Development in Young Adults (CARDIA) Study.

Sufficient evidence exists that plasma fibrinogen is a risk factor for cardiovascular disease to prompt a search for fibrinogen determinants. The authors measured fibrinogen in 4,193 participants in the Coronary Artery Risk Development in Young Adults (CARDIA) Study with three objectives: to describe fibrinogen levels in young adults, to determine if correlates of fibrinogen in older adults apply to younger adults, and to examine several additional hypothesized correlates. Fibrinogen (overall mean +/- standard deviation = 263 +/- 57 mg/dl) was greater in women than in men and in blacks than in whites; it was associated positively with cigarette smoking, body mass index, low density lipoprotein cholesterol, triglycerides, and blood pressure, and negatively with physical activity, high density lipoprotein cholesterol, and ethanol intake. Socioeconomic stress indicators and negative personality traits hypothesized as being associated with fibrinogen, possibly through adrenergic mechanisms, proved weak correlates. Parental history of diabetes was correlated positively with fibrinogen, in part because those with a positive parental history had greater body mass. Diabetes mellitus, lipoprotein(a), left ventricular mass, and oral contraceptive use were also positively correlated with fibrinogen concentration. Thus, even in young adults, fibrinogen is associated positively with most risk factors for atherosclerotic cardiovascular disease. This has implications for the role of fibrinogen as a risk factor and, potentially, for cardiovascular disease prevention.

Adolescent↗
PubMed1993

Treatment of Mild Hypertension Study. Final results. Treatment of Mild Hypertension Study Research Group.

OBJECTIVE: To compare six antihypertensive interventions for the treatment of mild hypertension. DESIGN: Randomized, double-blind, placebo-controlled clinical trial. SETTING: Four hypertension screening and treatment centers in the United States. PARTICIPANTS: Hypertensive men and women, aged 45 to 69 years, with diastolic blood pressure less than 100 mm Hg. INTERVENTION: Sustained nutritional-hygienic advice to all participants to reduce weight, dietary sodium intake, and alcohol intake, and increase physical activity. Participants were randomly allocated to take (1) placebo (n = 234); (2) chlorthalidone (n = 136); (3) acebutolol (n = 132); (4) doxazosin mesylate (n = 134); (5) amlodipine maleate (n = 131); or (6) enalapril maleate (n = 135). MAIN OUTCOME MEASURES: Blood pressure, quality of life, side effects, blood lipid levels and analysis of other serum components, echocardiographic and electrocardiographic changes, and incidence of cardiovascular events over an average of 4.4 years of follow-up. RESULTS: Blood pressure reductions were sizable in all six groups, and were significantly greater for participants assigned to drug treatment than placebo (-15.9 vs -9.1 mm Hg for systolic blood pressure and -12.3 vs -8.6 mm Hg for diastolic blood pressure; P < .0001). After 4 years, 59% of participants assigned to placebo and 72% of participants given drug treatment continued on their initial medication as monotherapy. A smaller percentage of participants assigned to the drug-treatment groups died or experienced a major nonfatal cardiovascular event than those assigned to the placebo group (5.1% vs 7.3%; P = .21). After including other clinical events, the percentage of participants affected was 11.1% for those in the drug-treatment groups and 16.2% for those in the placebo group (P = .03). Incidence rates of most resting electrocardiographic abnormalities were lower and quality of life was improved more for those assigned to drug-treatment groups rather than the placebo group. Differences among the five drug treatments did not consistently favor one group in terms of regression of left ventricular mass, blood lipid levels, and other outcome measures. CONCLUSIONS: As an initial regimen, drug treatment in combination with nutritional-hygienic intervention was more effective in preventing cardiovascular and other clinical events than was nutritional-hygienic treatment alone. Drug-treatment group differences were minimal. Pending results from large-scale clinical trials to evaluate drug treatments for their effect on cardiovascular clinical events, these findings support the recommendations of the new fifth Joint National Committee report regarding treatment choices for people with stage 1 ("mild") hypertension.

Acebutolol↗
PubMed1993

Ethnicity and renal disease: lessons from the Multiple Risk Factor Intervention Trial and the Treatment of Mild Hypertension Study.

Hypertension, particularly severe hypertension, has proven to be a risk factor for renal disease. Whether the relationship of blood pressure (BP) and high renal disease exists across a wide range of BP levels has been less clear. Compared with whites, blacks have a higher rate of end-stage renal disease from a multiplicity of causes, including hypertension, most prominently in younger age groups. To examine ethnic patterns of renal disease across BPs spanning the range of "normal" to "elevated," data were summarized from three large studies: (1) 12-year mortality for the 347,978 men (22,471 black and 325,507 white) without prior myocardia infarction (MI) screened for the Multiple Risk Factor Intervention Trial (MRFIT) who have been followed an average of 12 years for cause-specific mortality, (2) the baseline and 6-year change in renal function in 5,524 hypertensive men (463 black and 5,061 white) randomized in the MRFIT, and (3) the baseline and 1-year change in creatinine level are compared in 902 black and white men and women (177 black and 725 white) with mild hypertension in the Treatment of Mild Hypertension Study (TOMHS). In the MRFIT screenees, there was a monotonic increase in the risk of renal mortality at higher BP levels, even within the "normal range," both in black and white men. Blacks had higher baseline creatinine levels in both the MRFIT and TOMHS. In the MRFIT hypertensive patients, 6-year change in creatinine predicts coronary heart disease and all-cause mortality while the baseline creatinine level did not. Comparisons of randomized groups in the MRFIT or TOMHS did not demonstrate improved renal function with more aggressive BP lowering, but in MRFIT average on-treatment DBP < 95 mm Hg was associated with more favorable slopes of reciprocal creatinine. At 1 year, no gender-specific ethnic differences in creatinine change were observed in TOMHS. In the MRFIT hypertensive men, 6-year creatinine change was slightly more favorable in white men than in black men (-0.088 mumol/l v +3.09 mumol/L, P = 0.004). These data demonstrate (1) a graded and continuous relationship between BP and renal disease in blacks and whites across a wide BP range, (2) that creatinine change predicts subsequent mortality, at least in hypertensive men treated with diuretic-based pharmacologic regimen, and (3) possibly different pattern of creatinine change in response to antihypertensive drug therapy in blacks and whites.

Adult↗
PubMed1993

Chlorthalidone attenuates the reduction in total cholesterol and small, dense LDL cholesterol subclass associated with weight loss.

Thiazide diuretics are known to raise total and LDL cholesterol. To assess whether chlorthalidone affected levels of putatively atherogenic small, dense LDL (LDL 3), we conducted a 12 week double blind randomized, placebo controlled clinical trial in 34 nonsmoking men aged 35 to 57 years with mild hypertension (DBP 90 to 104 mm Hg). Our a priori hypothesis that chlorthalidone raised LDL 3 levels was not confirmed. However, the fall in LDL 3 (P = .03) and total cholesterol (P = .08) associated with weight loss was attenuated by chlorthalidone. Since weight loss is commonly prescribed during the clinical management of hypertensives with concomitant hypercholesterolemia, consideration should be given to the attenuating effect of chlorthalidone on cholesterol reduction in the management of these patients.

Adult↗
PubMed1993

Echocardiographic correlates of left ventricular structure among 844 mildly hypertensive men and women in the Treatment of Mild Hypertension Study (TOMHS).

BACKGROUND: Echocardiography provides a noninvasive means of assessing left ventricular (LV) structure and evidence of LV wall remodeling in hypertensive persons. The relation of demographic, biological, and other factors with LV structure can be assessed. METHODS AND RESULTS: LV structure was assessed by M-mode echocardiograms for 511 men and 333 women with mild hypertension (average blood pressure, 140/91 mm Hg). Measurements of LV wall thicknesses and internal dimensions were made, and estimates of LV mass indexes and other derivations of structure were calculated. LV hypertrophy criteria were based on previously reported echocardiographic population studies of normal subjects. These measures were compared by age, sex, race, body mass index, systolic blood pressure, antihypertensive drug use, physical activity, alcohol intake, cigarette smoking, and urinary sodium excretion. Despite virtual absence of ECG-determined LV hypertrophy, 13% of men and 20% of women had echocardiographically determined LV hypertrophy indexed by body surface area (g/m2), and 24% of men and 45% of women had LV hypertrophy indexed by height (g/m). Black participants had slightly higher mean levels of wall thickness than nonblack participants but similar LV mass. Systolic blood pressure and urinary sodium excretion were significantly and independently associated with LV mass index and LV hypertrophy using both g/m2 and g/m. Body mass index was significantly related to LV mass index and LV hypertrophy using g/m. Smoking was significantly associated with LV mass index, i.e., using continuous measurement but not using the dichotomy for LV hypertrophy. CONCLUSIONS: This study of a large population of men and women with mild primary hypertension, largely without ECG evidence of LV hypertrophy, showed a substantial percentage of participants with echocardiographically determined LV hypertrophy. LV mass indexes correlated positively with systolic blood pressure, body mass index, urinary sodium excretion, and smoking.

Aging↗
PubMed1993

Hypertension therapy in the elderly.

Hypertension in the elderly (persons 60 years of age or older) is a major clinical and public health problem. Blood pressure-related morbidity from cardiovascular disease increases steeply after 50 years of age and, with advancing age, becomes increasingly concentrated among persons with clinical hypertension. The data supporting treatment of all forms of hypertension in the elderly are robust. This review focuses on the rationale for treatment, specific treatment strategies, and age-related hemodynamic and pathophysiologic aberrations in the aged individual with hypertension.

Aged↗
PubMed1993

Psychosocial correlates of body fat distribution in black and white young adults.

We examined the association of fat distribution with a number of personality attributes and behaviours in a sample of 5115 young blacks and whites. Body fat distribution, measured by the ratio of waist-to-hip circumferences (WHR), was significantly and positively associated with cigarette smoking and negatively associated with education in all of the race and sex groups. WHR was positively associated with alcohol consumption in men and black women and with marijuana use in women. A number of psychosocial factors assessing personality attributes and behaviours were also examined, including the Cook-Medley hostility score, type A/B behaviour pattern, life events, social support, financial situation, and diagnosis of a nervous, emotional or mental disorder. In age- and BMI-adjusted analyses, only the Cook-Medley hostility score and a financial situation score were significantly and positively associated with WHR in all race and sex groups. In multivariate linear regression, these psychosocial factors were associated with WHR in some of the race and sex groups, accounting for less than 1% of the variation in WHR in any one group. These results suggest that fat distribution is weakly associated with these personality attributes and behaviours.

Adipose Tissue↗
PubMed1992

A test of the John Henryism hypothesis: cholesterol and blood pressure.

The personality predisposition "John Henryism" (JH) is a self-perception that one can meet demands of the environment through hard work and determination. The JH scale measures "efficacy of mental and physical vigor, commitment to hard work, and determination to reach one's goals." Previous research found an increased prevalence of hypertension among African-Americans with high JH scores and low socioeconomic status (SES). Six hundred fifty-three adult African-Americans in a church-based cardiovascular risk factor screening program completed the JH questionnaire. The prevalence of cholesterol greater than or equal to 240 mg/dl was highest (27%) among the high-JH/low-SES group when adjusted for age, sex, and body mass index. High JH/low SES was not associated with a greater prevalence of high blood pressure. Findings of this study suggest the need for additional research on John Henryism, socioeconomic factors, and cardiovascular risk among randomly selected samples of geographically and economically diverse African-Americans.

Adult↗
PubMed1992

Antibiotic use in urban whites and blacks: the Minnesota Heart Survey.

OBJECTIVE: To assess racial differences in the use of antibiotics, including penicillins, erythromycins, tetracyclines, sulfas, and cephalosporins. DESIGN: Population-based surveys, conducted from 1985 to 1987. SETTING: The seven-county metropolitan area of Minneapolis-St. Paul, MN. PARTICIPANTS: 3127 whites (response rate 68 percent) and 1047 blacks (response rate 65 percent), aged 35-74 years. RESULTS: White women (26 percent of 1625) were more likely to report having taken an antibiotic in the past year than were white men (18 percent of 1502), black women (18 percent of 590), or black men (15 percent of 457). Reported antibiotic usage decreased with increasing age. Black men were more likely than white men to report the use of tetracyclines or sulfas; otherwise, white men reported higher usage prevalences. White women reported higher usage prevalences of all drug classes than black women. CONCLUSIONS: Significant independent predictors of antibiotic use were younger age, white race, and female gender. Potential explanations for these differences include differences in patient access, physician-prescribing behaviors, or both.

Adult↗