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Biomedical subjects

G Howard

Publications and source records attributed to G Howard.

At least 91 records · Page 5Linked to original sources
PubMed1995

The relationship of active and passive smoking to carotid atherosclerosis 12-14 years later.

BACKGROUND: Active and passive smoking have been found to be associated with clinical atherosclerotic disease. To explore the effects of smoking on atherogenesis, we investigated the relationship of past and current active and passive smoking to carotid atherosclerosis in middle-aged adults. METHODS: The study population consisted of 2,073 middle-aged residents of Washington County, Maryland. Information on active smoking and exposure to environmental tobacco smoke (ETS) was obtained from a 1975 census and from the baseline visit of the Atherosclerosis Risk in Communities (ARIC) Study in 1987-1989. Carotid artery intimal-medial wall thickness, measured by B-mode ultrasound methods in 1987-1989, was used as an indicator of carotid atherosclerosis. Mean intimal-medial wall thickness (IMT) was adjusted for age, gender, cardiovascular risk factors, and education using multiple linear regression. RESULTS: The lowest mean IMT was found among never smokers who had never been exposed to ETS (mean +/- standard error: 0.706 +/- 0.013 mm). Exposure to ETS in one or both time periods was associated with increased IMT among never smokers (ETS in 1975 only: 0.731 +/- 0.022; ETS in 1987-1989 only: 0.738 +/- 0.011; ETS in both periods: 0.734 +/- 0.012). Active smoking in 1975 was also associated with increased IMT. The greatest mean intimal-medial wall thickness was found among persons who were current smokers in both time periods (0.807 +/- 0.009). CONCLUSIONS: Both past and current passive and active smoking are associated with increased carotid intimal-medial wall thickness.

Arteriosclerosis↗
PubMed1995

The insulin resistance atherosclerosis study (IRAS) objectives, design, and recruitment results.

The Insulin Resistance Atherosclerosis Study (IRAS) is the first epidemiologic study designed to assess the relationships between insulin resistance, insulinemia, glycemia, other components of the insulin resistance syndrome, and prevalent cardiovascular disease (CVD) in a large multiethnic cohort. Over 1600 men and women were recruited from four geographic areas to represent a range of glucose tolerance (normal, impaired, and diabetic) and ethnicity (hispanic, non-Hispanic white, and African-American). Insulin resistance was assessed directly using the frequently sampled intravenous glucose tolerance test with minimal model analysis. Intimal-medial carotid artery wall thickness, an indicator of atherosclerosis, was measured using B-mode ultrasonography. Prevalent CVD was assessed by questionnaire and resting electrocardiography. This report describes the design of the study and provides the recruitment results. Forthcoming cross-sectional analyses will help to disentangle the association between insulin resistance and CVD, apart from the concomitant hyperinsulinemia and related CVD risk factors.

Adult↗
PubMed1995

Distribution and correlates of plasma fibrinogen in middle-aged women. Initial findings of the Postmenopausal Estrogen/Progestin Interventions (PEPI) study.

Fibrinogen levels have been reported in cohort and case-control studies to be positively related to the development of coronary heart disease. This report presents the distribution and determinants of fibrinogen in women enrolling in a 3-year randomized trial of hormone replacement therapy (HRT), the Postmenopausal Estrogen/Progestin Interventions (PEPI) trial. Fasting plasma fibrinogen levels were measured in 874 postmenopausal women, aged 45 to 65 years, who had not used HRT for at least 3.5 months. Mean (+/- SD) fibrinogen level was 2.83 +/- 0.45 g/L. There was a significant positive association between fibrinogen and age (P = .03). Significantly higher (P < .005) fibrinogen levels were seen in current smokers versus nonsmokers (2.94 versus 2.81 g/L), in women who reported consuming fewer than 12 alcoholic drinks in the 12 months before the baseline visit versus higher consumption (2.90 versus 2.79 g/L), and in women who reported never versus ever having used HRT (2.90 versus 2.77 g/L). Self-reported leisure time physical activity (LTPA) was negatively associated (P = .0001) with fibrinogen levels as follows: inactive (2.84 g/L), light (2.89 g/L), moderate (2.80 g/L), and heavy (2.60 g/L), with significantly (P = .0001) lower levels in women who reported heavy LTPA versus each of the other categories and in women reporting moderate versus light LTPA. A strong positive correlation was found between fibrinogen and body mass index (BMI) (r = .32; P < .0001). In a model that included age, smoking, alcohol intake, prior HRT, LTPA, and BMI, LTPA was no longer a statistically significant predictor of fibrinogen level, while associations with other variables remained significant.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1995

Role of social class in excess black stroke mortality.

BACKGROUND AND PURPOSE: It has been suggested that a substantial proportion of the excess stroke mortality among black Americans may be attributable to relatively lower socioeconomic status (SES) in this group. In this report we provide the first quantitative estimates of the proportion of excess black stroke mortality attributable to SES for a large population-based cohort. METHODS: We used data from the National Longitudinal Mortality Study for persons 45 years and older (73,400 white men, 87,528 white women, 6522 black men, and 8816 black women). Sex-specific proportional hazards model were used to estimate excess black stroke mortality with and without adjustment for education and income (measures of SES). The contribution of SES to the excess black stroke risk was estimated from the difference in regression coefficients for race in these models. RESULTS: In men, low SES was associated with increased stroke mortality (P < or = .0001) and accounted for 14% to 46% of the excess black stroke risk (P < .05). However, we could find no association between SES and stroke mortality in women, and SES did not account for a significant proportion of the excess stroke mortality in black women. CONCLUSIONS: Although SES proved to account for a statistically significant proportion of excess male black stroke mortality, overall SES explained less than one quarter of the observed excess between ages 45 and 65. In women, SES did not significantly reduce the estimated excess black stroke mortality. Although SES may be playing a role in excess black stroke mortality, a substantial proportion of the excess appears attributable to other sources, including cerebrovascular risk factors that are unrelated to SES, unmeasured lifestyle influences, social resources, and genetic factors.

Black or African American↗
PubMed1995

Arterial wall thickness is associated with prevalent cardiovascular disease in middle-aged adults. The Atherosclerosis Risk in Communities (ARIC) Study.

BACKGROUND AND PURPOSE: This study was done to assess the relationship between prevalent cardiovascular disease and arterial wall thickness in middle-aged US adults. METHODS: The association of preexisting coronary heart disease, cerebrovascular disease, and peripheral vascular disease with carotid and popliteal intimal-medial thickness (IMT) (measured by B-mode ultrasound) was assessed in 13,870 black and white men and women, aged 45 to 64, during the Atherosclerosis Risk in Communities (ARIC) Study baseline examination (1987 through 1989). Prevalent disease was determined according to both participant self-report and measurements at the baseline examination (including electrocardiogram, fasting blood glucose, and medication use). RESULTS: Across four race and gender strata, mean carotid far wall IMT was consistently greater in participants with prevalent clinical cardiovascular disease than in disease-free subjects. Similarly, the prevalence of cardiovascular disease was consistently greater in participants with progressively thicker IMT. The greatest differences in carotid IMT associated with prevalent disease were observed for reported symptomatic peripheral vascular disease (0.09 to 0.22 mm greater IMT in the four race-gender groups). CONCLUSIONS: These data document the substantially greater arterial wall thickness observed in middle-aged adults with prevalent cardiovascular disease. Both carotid and popliteal arterial IMT were related to clinically manifest cardiovascular disease affecting distant vascular beds, such as the cerebral, peripheral, and coronary artery vascular beds.

Age Factors↗
PubMed1995

Is the stroke belt disappearing? An analysis of racial, temporal, and age effects.

BACKGROUND AND PURPOSE: The stroke risk among white residents of the coastal plain of North Carolina, South Carolina, and Georgia (the "Stroke Belt") has been reported to be between 1.3 and 2.0 times the national average. In this study we examined (1) whether a similar excess risk exists for blacks in this region, (2) whether this regional excess stroke risk has decreased over time, and (3) whether the regional excess risk is consistent across ages from 45 to more than 85 years. METHODS: Using data from the Compressed Mortality File, we estimated the annual relative stroke mortality risk for black and white men and women in a region of 153 coastal plain counties and compared these rates to those for the remainder of the United States. RESULTS: The relative geographic excess risk of stroke death was similar for black residents and white residents of the Stroke Belt for both men and women. Despite the decline in stroke mortality, the relative increased risk of stroke death in the region has remained constant from 1968 to 1991; however, the pattern of excess risk across age differed significantly between race/sex groups. CONCLUSIONS: These data show that the Stroke Belt continues to exist for blacks and whites and for men and women. Although the specific causes of the Stroke Belt remain unknown, the public health impact is staggering, with a greater than 40% excess risk of stroke mortality and more than 1200 excess stroke deaths annually.

Age Factors↗
PubMed1995

Genetic influences on bone density: physiological correlates of vitamin D receptor gene alleles in premenopausal women.

Common vitamin D receptor (VDR) gene alleles have recently been shown to contribute to the genetic variability in bone mass and bone turnover, however, the physiological mechanisms involved are unknown. To examine this, the response to 7 days of 2 micrograms oral 1,25-dihydroxyvitamin D[1,25-(OH)2D] (calcitriol) stimulation was assessed in 21 premenopausal women, homozygous for one or other of the common VDR alleles (bb, n = 11; BB, n = 10). Indices of bone turnover and calcium homeostasis were measured during 2 weeks. Baseline osteocalcin, 1,25-(OH)2D, type I collagen carboxyterminal telopeptide, and inorganic phosphate levels were significantly higher and spinal bone mineral density was significantly lower in the BB allelic group. After calcitriol administration, similar levels of 1,25-(OH)2D were attained throughout the study in both genotypic groups. The increase in serum osteocalcin levels in the BB group was significantly less than that in the bb group (11% vs. 32%, P = 0.01). The genotype-related baseline difference in osteocalcin levels was not apparent at the similar serum 1,25-(OH)2D levels. By contrast, the baseline differences in phosphate and type I collagen carboxyterminal telopeptide persisted throughout the study. Serum ionized calcium levels did not differ between genotypes, nor did it move out of normal range values. However, parathyroid hormone was less suppressed in the low bone density group (38% vs. 11%, P = 0.01). These data indicate that the VDR alleles are associated with differences in the vitamin D endocrine system and may have important implications in relation to the pathophysiology of osteoporosis.

Adult↗
PubMed1994

Active and passive smoking are associated with increased carotid wall thickness. The Atherosclerosis Risk in Communities Study.

BACKGROUND: Active cigarette smoking has been established as a potent risk factor for carotid atherosclerosis in clinical populations; however, neither the role of active smoking in general populations nor the impact of environmental tobacco smoke has been well described. METHODS: The association between carotid artery wall thickness and cigarette smoking was studied in 12,953 black and white men and women, aged 45 to 65 years, examined in the Atherosclerosis Risk in Communities Study. Participants were classified as current smokers (n = 3525), past smokers (n = 4315), never smokers reporting weekly exposure to environmental tobacco smoke (ETS or "passive smoking") of at least 1 hour (n = 3339), or never smokers reporting no weekly exposure to ETS (n = 1774). Carotid artery intimal-medial thickness (IMT) was measured by B-mode ultrasound. RESULTS: Increased IMT was observed in each category, in order from smallest to greatest increase: never smokers not exposed to ETS, never smokers exposed to ETS, past smokers, and current smokers. The larger IMT observed in the nonsmoking group exposed to ETS compared with the nonsmokers not exposed persisted after control for diet, physical activity, body mass index, alcohol intake, education, and major cardiovascular risk factors. Among past and current smokers, increased pack-years of exposure was associated with increased IMT. Among nonsmoking men exposed to ETS, there was a significant increase in IMT with increasing number of hours per week of ETS exposure. CONCLUSIONS: These data confirm the strong relationship between active smoking and carotid artery IMT and provide initial evidence that passive smoking exposure is related to greater IMT. Increasing exposure to cigarette smoke (either pack-years of active smoking or hours of ETS) was significantly related to increased IMT.

Aged↗
PubMed1994

Predictive value of induction of psychogenic seizures by suggestion.

Induction by suggestion has previously been reported to be effective in the diagnosis of psychogenic seizures (PS). However, the sensitivity and specificity of this procedure has not previously been studied. Results of induction of PS by suggestion were analyzed in 93 patients with purely PS. The diagnosis of PS was based on the recording of a clinical event on video-electroencephalography, the absence of clinical or electroencephalography the absence of clinical or electroencephalographic evidence of epilepsy, and the subsequent followup and withdrawal of anticonvulsants supporting the diagnosis of PS. A control-group was composed of 20 patients with epilepsy in which induction was tried. Both groups were comparable for age, sex, and educational level. Induction was performed following a standardized protocol. The test was carried out placing a colored patch on the neck. The test was considered positive when the induced clinical events were typical, according to a witness familiar with the patient's seizures. Induction was positive in 72 of 93 cases with PS and in none with epilepsy. Sensitivity of this test for the diagnosis of PS was 77.4%, specificity 100%, positive predictive value 100%, and negative predictive value 48.7%.

Adolescent↗
PubMed1994

Ethnic differences in stroke mortality between non-Hispanic whites, Hispanic whites, and blacks. The National Longitudinal Mortality Study.

BACKGROUND AND PURPOSE: Although US blacks are known to have an excess stroke mortality compared with US whites, little is known about the stroke burden of the Hispanic white population. This report will provide estimates of the relative burden of stroke mortality in the US black and Hispanic population relative to the white population and examine the consistency of this relation across age. METHODS: Data were from participants aged > 45 years from the National Longitudinal Mortality Study. There were 1844 stroke deaths among 239,734 non-Hispanic whites, 46 deaths among 12,527 Hispanic whites, and 234 deaths among 23,468 black participants. Standard statistical methods were used to examine the ethnic differences in stroke mortality. RESULTS: The hazard ratios for black men and women (relative to non-Hispanic whites) were nearly identical, at > 4.0 at age 45 but marginally < 1.0 by age 85. For both Hispanic men and women, the hazard ratios (relative to non-Hispanic whites) were approximately 1.0 at age 45 but were marginally significantly < 1.0 at older ages. The ethnic differences in stroke death rates reveal differences in age distributions of age at fatal stroke between these groups. Approximately 6% of fatal strokes for non-Hispanic whites occurred before age 60, whereas > 15% occurred in both Hispanic whites and blacks. CONCLUSIONS: These results suggest that (1) for Hispanics, stroke risk is similar to that for non-Hispanic whites at young ages but is marginally lower at older ages, (2) the excess stroke mortality in blacks mainly occurs at younger ages (between 45 and 55 years), and (3) the relation between stroke risk for blacks and Hispanics relative to whites is similar by sex. The impact of age on relative stroke mortality would argue against simple age adjustment for describing ethnic differences in stroke mortality. Finally, proportionally, more strokes occur at older ages in non-Hispanic whites than in either US blacks or Hispanic whites.

Age Factors↗