Race, socioeconomic status, and cause-specific mortality

PURPOSE

Life expectancy for black Americans is five to eight years less than for Whites. The socioeconomic status (SES) of Blacks is also less than for Whites, and SES is associated with early mortality. This paper estimates the proportion of the racial difference in mortality attributable to SES by specific causes of death.

METHODS

Data on 453,384 individuals in the National Longitudinal Mortality Study were used to estimate the hazard ratio associated with black race, with and without adjustment for income and education (measures of SES), in 38 strata defined by cause of death and age.

RESULTS

For women, SES accounted for much (37-67%) of the black excess mortality for accidents, ischemic heart disease (ages 35-54), diabetes, and homicide; but not for hypertension, infections, and stomach cancers (11-17%). For men, SES accounted for much of the excess risk (30-55%) for accidents, lung cancer, stomach cancer, stroke, and homicide; but not for prostate cancer, pulmonary diseases, hypertension, and cardiomyopathy (0-17%).

CONCLUSIONS

These results confirm those specific causes of death likely to underlie the overall excess mortality of Blacks, and identify those causes where SES may play a large role.

Environmental tobacco smoke and measures of subclinical vascular disease

Assessing the relationship of exposure to environmental tobacco smoke (ETS) with subclinical measures of atherosclerotic disease supplements the epidemiologic data on fatal and nonfatal cardiovascular events. In addition, such assessment offers the opportunity to study smaller populations (including subgroups within larger studies) through improved statistical precision relative to the analysis of the relationship of ETS and clinical events and provides insights into the mechanisms of the harmful effects of ETS. In this article we review the published literature on the relationship of ETS with several indices of subclinical atherosclerosis including carotid artery intimal-medial thickness, brachial artery endothelial functioning, and silent cerebral infarctions. In each of these domains, exposure to ETS is associated with evidence of increased subclinical vascular disease.

Why is environmental tobacco smoke more strongly associated with coronary heart disease than expected? A review of potential biases and experimental data

Despite exposure levels estimated to be equivalent to smoking only 0. 1-1.0 cigarettes per day, exposure to environmental tobacco smoke (ETS) is estimated to increase the risk of death from coronary heart disease (CHD) between 25 and 35% above the risk of nonexposed persons. This surprisingly large risk associated with a seemingly small exposure has raised doubts about the validity of attributing the increased CHD risk to ETS exposure. This paper reviews various biases that have been hypothesized to account for the increased CHD risk associated with ETS in the epidemiologic studies and characterizes the adverse effects of ETS on thrombosis, vascular endothelium, and exercise tolerance observed in experimental studies of humans and laboratory animals. None of the identified factors that has been proposed to introduce a spurious association between ETS and heart disease seem to invalidate the epidemiologic findings, either separately or in combination. In addition, experimental studies of ETS and heart disease demonstrate that acute exposure of humans and other species to ETS affects platelet function, vascular endothelium, and myocardial exercise tolerance at exposure concentrations widely prevalent in the workplace. Because exposure to ETS affects multiple physiologic pathways, it appears biologically plausible that ETS could cause the substantial increase in CHD risk that has been observed in epidemiologic studies.

Prospective associations of fasting insulin, body fat distribution, and diabetes with risk of ischemic stroke. The Atherosclerosis Risk in Communities (ARIC) Study Investigators

OBJECTIVE

We tested the hypothesis that diabetes, body fat distribution, and (in nondiabetic subjects) fasting insulin levels are positively associated with ischemic stroke incidence in the general population.

RESEARCH DESIGN AND METHODS

As part of the Atherosclerosis Risk in Communities (ARIC) Study, we measured diabetes by using fasting glucose criteria, waist and hip circumferences, and fasting insulin levels with a radioimmunoassay in > 12,000 adults aged 45-64 years who had no cardiovascular disease at baseline. We followed them for 6-8 years for ischemic stroke occurrence (n = 191).

RESULTS

After adjustment for age, sex, race, ARIC community, smoking, and education level, the relative risk of ischemic stroke was 3.70 (95% CI 2.7-5.1) for diabetes, 1.74 (1.4-2.2) for a 0.11 increment of waist-to-hip ratio, and 1.19 (1.1-1.3) for a 50-pmol/l increment of fasting insulin among nondiabetic subjects. Ischemic stroke incidence was not statistically significantly associated with BMI (comparably adjusted relative risk = 1.15, 95% CI 0.97-1.36). With adjustment for other stroke risk factors (some of which may mediate the effects of diabetes, fat distribution, and hyperinsulinemia), the relative risks for diabetes, waist-to-hip ratio, and fasting insulin level were 2.22 (95% CI 1.5-3.2), 1.08 (0.8-1.4), and 1.14 (1.01-1.3), respectively.

CONCLUSIONS

Diabetes is a strong risk factor for ischemic stroke. Aspects of insulin resistance, as reflected by elevated waist-to-hip ratios and elevated fasting insulin levels, may also contribute to a greater risk of ischemic stroke.

Application of membrane filtration for removal of diminutive bioburden organisms in pharmaceutical products and processes

In this report, we present results of a recent investigation in our laboratories demonstrated the effect of process conditions and/or drug product composition on the ability of 0.2 micron and 0.22 micron sterilizing grade filters to fully retain Ralstonia (formerly Burkholderia, formerly Pseudomonas) pickettii. R. pickettii is a opportunistic pathogen widely distributed in nature as well as clinical specimens and there have been several reports of nosocomial infections due to intrinsic manufacture-related R. pickettii contamination in filter-sterilized parenteral fluids. This study documents the penetration of 0.2 micron nylon 66 and 0.22 micron modified PVDF sterilizing grade filters by R. pickettii (grown and challenged) in a drug solution under conditions that simulated a pharmaceutical filling operation. Penetration was not observed for every filter disc tested, and this may be explained, in part, by the stochastic nature (i.e., governed by the rules of probability) of the retention mechanisms involved. Scanning electron microscopy revealed significant changes in the microorganism's size and morphology as a result of exposure to the drug solution; these changes are consistent with those reported for bacteria subjected to nutrient deprivation. The SEM analyses of R. pickettii challenge suspensions in the drug solution showed that the average cell length decreased from 1.25 +/- 0.27 microns to 0.84 +/- 0.17 micron between zero and 24 hours. In addition, significant changes were observed in the size (length) distributions, with approximately 35% of the cells at 24 hours being smaller than any cell observed at the start of the challenge. These data suggest that the significant reduction in bioburden size and morphology that occurred as a result of exposure to the drug solution may play a role in the reduced ability of the 0.2 micron and 0.22 micron filters tested in this study to retain these organisms. Under the same test conditions where penetration of 0.2/0.22 micron filters was observed, 0.1 micron rated membrane filters qualified with both B. diminuta and Acholeplasma laidlawii mycoplasma consistently provided sterile effluent. Bacterial penetration of 0.2 (or 0.22) micron sterilizing grade filters was not observed under identical test conditions with either R. pickettii in a standardized solution (saline lactose broth) routinely used in challenge testing filters, or with the standard test organism, B. diminuta, in the drug solution. This study thus supports the renewed emphasis on both product- and process specific validation as well as routine bioburden monitoring expressed by regulatory agencies, and the use of enhanced bacterial removal efficiency 0.1 micron rated filters to provide enhanced sterility assurance in pharmaceutical processes.

Effect of leptin on cytochrome P-450, conjugation, and antioxidant enzymes in the ob/ob mouse

Leptin is a hormone that is secreted by adipocytes and regulates body weight through its effect on satiety and energy metabolism. The ob/ob mouse is deficient in this protein and is characterized by obesity and other metabolic disorders. This study investigated the alterations of several hepatic cytochrome P-450 (CYP), conjugation, and antioxidant enzymes in lean and ob/ob mice and the role leptin plays in the modulation of these enzymes. Lean and ob/ob male mice were injected with leptin (100 microg) or PBS for 15 days. Liver microsomes from ob/ob mice, when compared with lean controls, displayed significantly reduced chlorzoxazone 6-hydroxylation activity (27%); however, 7alpha- and 16alpha- testosterone hydroxylation and pentoxyresorufin O-dealkylation activities were significantly higher (47%, 22%, and 39%, respectively). Leptin administration corrected alterations seen with all P-450 activities. Dealkylation of ethoxyresorufin and omega-hydroxylation of lauric acid activities from ob/ob and lean mice were not statistically different; however, leptin exposure significantly increased ethoxyresorufin activity in lean mice (14%) and decreased the activity in ob/ob mice (36%). UDP-glucuronosyl-transferase and glutathione S-transferase activities were not altered. The antioxidant enzymes, catalase (11%) and glutathione peroxidase (26%), as well as glutathione reductase (17%), were lower in the ob/ob mice and leptin treatment corrected these alterations. The results of this study demonstrate alterations in constitutive expression of CYP2B, CYP2E, CYP2A, catalase, glutathione peroxidase, and glutathione reductase in ob/ob mice that were restored to lean control values following leptin treatment. Additionally, CYP3A activity was increased following leptin treatment in ob/ob mice. The mechanism for the observed alterations may be due to direct leptin effects or via indirect alterations in insulin, corticosterone, and/or growth hormone.

Stroke incidence and survival among middle-aged adults: 9-year follow-up of the Atherosclerosis Risk in Communities (ARIC) cohort

BACKGROUND AND PURPOSE

Although stroke mortality rates in the United States are well documented, assessment of incidence rates and case fatality are less well studied.

METHODS

A cohort of 15 792 men and women aged 45 to 64 years from a population sample of households in 4 US communities was followed from 1987 to 1995, an average of 7. 2 years. Incident strokes were identified through annual phone contacts and hospital record searching and were then validated.

RESULTS

Of the 267 incident definite or probable strokes, 83% (n=221) were categorized as ischemic strokes, 10% (n=27) were intracerebral hemorrhages, and 7% (n=19) were subarachnoid hemorrhages. The age-adjusted incidence rate (per 1000 person-years) of total strokes was highest among black men (4.44), followed by black women (3.10), white men (1.78), and white women (1.24). The black versus white age-adjusted rate ratio (RR) for ischemic stroke was 2.41 (95% CI, 1.85 to 3.15), which was attenuated to 1.38 (95% CI, 1.01 to 1.89) after adjustment for baseline hypertension, diabetes, education level, smoking status, and prevalent coronary heart disease. There was a tendency for the adjusted case fatality rates to be higher among blacks and men, although none of the case fatality comparisons across sex or race was statistically significant.

CONCLUSIONS

After accounting for established baseline risk factors, blacks still had a 38% greater risk of incident ischemic stroke compared with whites. Identification of new individual and community-level risk factors accounting for the elevated incidence of stroke requires further investigation and incorporation into intervention planning.

Why do we have a stroke belt in the southeastern United States? A review of unlikely and uninvestigated potential causes

Although there is widespread recognition of a region with high stroke mortality in the southeastern United States that has persisted over the past 50 years (ie, the "stroke belt"), there is little agreement as to its underlying cause(s). Herein, we review data supporting 10 potential causes for the stroke belt, and assess: (1) the likelihood that each is the contributing factor to the excess mortality, and (2) areas of investigation where data are lacking and that require additional research efforts.

Communication between older adults and their physicians about urinary incontinence

BACKGROUND

Urinary incontinence (UI) is a common but undertreated condition in older adults. The study objective was to determine older patients' characteristics related to communication patterns with their physicians about UI.

METHODS

Telephone surveys of a sample of patients age 60 and older who visited a primary care provider (PCP) for any reason within the past 2 months were conducted. Participating physicians included general internists and family physicians from 41 primary care practices located in the 17 counties of northwest North Carolina whose 435 incontinent and 711 continent patients completed the surveys. The main outcome measures were patients' frequency and amount of urinary leakage, being asked about incontinence, and initiating a discussion of incontinence if not asked by their PCP.

RESULTS

Age and gender were significant independent predictors of incontinence. PCPs were significantly more likely to assess incontinent women than incontinent men (21% vs 10%, p = .053). The older cohorts of older adults were significantly more likely to be symptomatic for UI than their younger counterparts. However, the younger cohorts were more likely to be screened for incontinence by their physicians.

CONCLUSIONS

Despite the publication of guidelines on improving the screening and management of UI, the problem remains common and underdetected in older adults. Physicians don't ask and patients don't tell. Interventions are needed to remind physicians to screen high risk patients and to encourage patients with UI to communicate with their physicians.

Characterization of cytochrome P450 and glutathione S-transferase activity and expression in male and female ob/ob mice

OBJECTIVE

To characterize the effect(s) of gender, age (glycemic status) and obese state, on hepatic biotransformation activities, expression of cytochrome P450 (CYP450) mRNAs and glutathione transferase activity in the ob/ob mouse.

DESIGN

Male and female, ob/ob or ob/+ mice were killed at 3-4 months or 7-8 months of age. Hepatic microsomes, cytosol and RNA were prepared from each animal.

ANIMALS

Male and female ob/ob and ob/+ mice, 3-4 or 7-8 months of age.

MEASUREMENTS

CYP450 form-specific activities of CYP1A1/1A2, CYP3A and CYP2B were estimated by determining the 0-dealkylation of alkoxyresorufin substrates (ethoxy-EROD, benzoxy-BROD and pentoxy-resorufin, PROD, respectively). CYP2E1-dependent, 4-nitrophenol hydroxylase (PNP-OH) and CYP3A-dependent erythromycin N-demethylase (ERY-DM) were also measured in hepatic microsomes. CYP1A2, CYP2E1 and CYP3A protein in microsomal fractions was determined by ELISA. Glutathione transferase activity (GST) was determined in hepatic cytosol and CYP1A2 and CYP2E1 mRNA was estimated by Northern blot analysis.

RESULTS

Female mice, regardless of glycemic status, showed an obesity enhanced level of CYP2E1-dependent PNP-OH activity and CYP2E1 protein as shown by ELISA. These increases were observed to be independent of the diabetic state, since 7-8 month-old mice had blood glucose levels identical to lean mice. The mRNA level of CYP2E1 in female mice also exhibited age-and obesity-influenced decreases in expression. No significant differences in CYP2E1 activity or expression were observed in male mice. CYP3A-dependent ERY-DM activity was significantly higher in young males, regardless of phenotype. CYP3A and CYP2B activities did not differ among any animals; however, CYP1A activity, while depressed in obese animals of both genders, was significantly different in old animals. Glutathione S-transferase activity was lower in obese male mice, whereas no difference was observed between lean and obese females

CONCLUSION

This study supports earlier observations in man and rats that the obese state produces alterations in the expression of important oxidation and conjugation pathways. In addition, this report more thoroughly examines the role of gender and glycemic status on biotransformation activities in the ob/ob mouse as demonstrated by increased CYP2E1 protein and CYP2E1-dependent activity in obese females, decreased CYP1A2 protein and CYP1A2-dependent activity in obese animals, and obesity had no effect of glutathione transferase in female mice, in contrast with the previously reported obesity-dependent decrease of this activity in male mice.

Characterization of nuclear protein binding (AP-1, GR, and STAT) in the genetically obese (fa/fa) Zucker rat

There is evidence to suggest that obese populations have an increased susceptibility to various pathologic disorders. Both AP-1 and STAT nuclear binding proteins have been suggested to play a role in certain obesity-related diseases. The objective of our studies reported herein was to compare constitutive binding activity of nuclear proteins (AP-1, GR, and STAT), that may be relevant to obesity-related diseases in the obese (fa/fa) Zucker rat to lean (Fa/?) littermates. AP-1, GR, and STAT liver nuclear protein binding activity was analyzed using the electrophoretic mobility shift assay (EMSA). EMSA analysis of liver nuclear protein from obese and lean Zucker rats revealed high constitutive AP-1 binding activity in the obese animals. AP-1 binding activity in the obese rats was not further elevated by treatment with phenobarbital, a known inducer of AP-1 binding activity. No differences were observed in GR binding to a consensus GRE between obese and lean animals; however, STAT binding activity to a consensus GAS element was lower in liver tissue from obese Zucker rats. Our findings presented herein suggest that the fa/fa Zucker rat may be a suitable obese rodent model for studying the roles AP-1 and STAT may play in the pathologies of these diseases.

Effect of postmenopausal hormone therapy on glucose and insulin concentrations. PEPI Investigators. Postmenopausal Estrogen/Progestin Interventions

OBJECTIVE

To characterize the long-term impact of four hormone therapy regimens on insulin and glucose concentrations measured during a standard oral glucose tolerance test.

RESEARCH DESIGN AND METHODS

The Postmenopausal Estrogen/Progestin Intervention Study was a 3-year placebo-controlled randomized trial to assess effects of four hormone regimens on cardiovascular risk factors. This efficacy analysis describes glucose and insulin concentrations from 788 adherent women at baseline and at 1 and 3 years' postrandomization.

RESULTS

When compared with women taking placebo, those taking conjugated equine estrogen (CEE) at 0.625 mg/day with or without a progestational agent had mean fasting insulin levels that were 16.1% lower, mean fasting glucose levels 2.2 mg/dl lower, and mean 2-h glucose levels 6.4 mg/dl higher (each nominal P < 0.05). No significant differences were apparent between women taking CEE only versus the three progestin regimens: medroxyprogesterone acetate (MPA) at 2.5 mg daily (continuous MPA), MPA at 10 mg on days 1-12 (cyclical MPA), and micronized progesterone (MP) (cyclical) at 200 mg on days 1-12. The impact of hormone therapy on insulin and glucose depended on baseline levels of fasting insulin and 1-h glucose (P < 0.05). However, the treatment effects on carbohydrate metabolism appeared to be consistent across participant subgroups formed by lifestyle, clinical, and demographic characteristics.

CONCLUSIONS

Oral hormone therapy involving 0.625 mg/day of CEE may modestly decrease fasting levels of insulin and glucose. Postchallenge glucose concentrations are increased, however, which may indicate delayed glucose clearance.

The effect of high dose endotoxin on CYP3A2 expression in the rat

PURPOSE

The purpose of our research was two-fold: 1) to further characterize the downregulation of CYP3A2 mRNA, protein, and activity during an acute phase response (APR); 2) most importantly, to relate the time-dependent activation of nuclear proteins to putative DNA binding sequences within the CYP3A2 5'-flanking region, with the loss in CYP3A2 expression.

METHODS

Rats were injected (2.0 mg/animal, i.p.) with LPS and sacrificed at 1, 2, 4, 6, 8, 24, 48, and 72 hours. Hepatic nuclear protein was isolated and analyzed for binding activity to AP-1, NFkappaB, and NF-IL6 consensus sequences. Hepatic CYP3A2 mRNA levels were determined by solution hybridization and CYP3A2 protein, CYP3A2 activity, and total P450 were measured in hepatic microsomes.

RESULTS

Computer analysis of the 5'-flanking region of CYP3A2 revealed the presence of 5 NF-IL6 and 4 AP-1 putative DNA binding sites. The strongest increase in AP-1 binding activity occurred between 6 and 24 hr, and the alteration in binding complexes to an NF-IL6 oligonucleotide occurred between 4 and 24 hr. Maximum loss in CYP3A2 mRNA occurred at 8 hr post-LPS injection and remained lowered at the 24 hr timepoint. CYP3A2 protein was significantly decreased at 24, 48, and 72 hours post-LPS treatment with corresponding decreases in CYP3A2 activity and total P450.

CONCLUSIONS

The changes in NF-IL6 and AP-1 binding after LPS treatment, which appears to correlate with the changes in CYP3A2 mRNA, combined with the presence of putative NF-IL6 and AP-1 sites located in the CYP3A25'-flanking region, may indicate a potential role for NF-IL6 and AP-1 in CYP3A2 downregulation during an APR.

Alfentanil decreases the excitatory phenomena of sodium methohexital

STUDY OBJECTIVE

To evaluate the effects of alfentanil or lidocaine on the excitatory phenomena (myoclonus, cough, hiccough) caused by methohexital anesthesia and on the hemodynamic changes induced by retrobulbar block.

DESIGN

Prospective, randomized, placebo-controlled, double-blind study.

SETTING

University-affiliated, tertiary-care hospital.

PATIENTS

60 ASA physical status II and III patients who were admitted for elective cataract extractions and intraocular lens implantations.

INTERVENTIONS

Patients were randomly assigned to one of three groups. After adequate preoxygenation in the holding area, Group 1 received alfentanil 5 micrograms/kg intravenously (i.v.), Group 2 received lidocaine 1 mg/kg i.v. and Group 3 received the placebo (saline) i.v. Immediately after the bolus injection of the study solution, sodium methohexital 1.5 mg/kg was injected i.v. over 30 seconds. As soon as the eyelid reflex was lost, the retrobulbar block was placed over 5 seconds.

MEASUREMENTS AND MAIN RESULTS

Occurrences of excitatory phenomena were recorded by an independent observer who was blinded as to treatment allocation. Other side effects such as oculocardiac reflex, nausea, vomiting, itching, or chest wall rigidity were recorded. Vital signs were recorded at baseline and 1, 3, and 5 minutes after placement of the block. In the alfentanil group, the incidence of myoclonus or cough was significantly less than in the lidocaine or placebo groups. Alfentanil also decreased systolic and diastolic blood pressure significantly at 1, 3, and 5 minutes after retrobulbar block. Changes in heart rate were not significantly different from baseline.

CONCLUSION

A small dose of alfentanil (5 micrograms/kg i.v.) decreases myoclonus and cough induced by sodium methohexital anesthesia i.v., resulting in improved quality of induction of anesthesia. Alfentanil also attenuates the cardiovascular responses caused by placement of a retrobulbar block.

Ability of alternative indices of insulin sensitivity to predict cardiovascular risk: comparison with the "minimal model". Insulin Resistance Atherosclerosis Study (IRAS) Investigators

INTRODUCTION

Although recognition of insulin sensitivity as a risk factor for cardiovascular disease is growing, a deeper understanding of its role is impeded by the cost and complexity of currently available measures. This report evaluates previously described alternative indices of insulin sensitivity with the goal of identifying a reliable, but logistically simpler, alternative.

METHODS

Data from 1460 participants in the Insulin Resistance Atherosclerosis Study (IRAS) were used to assess the proportion of the relationship between a recognized measure of insulin sensitivity (Bergman's SI) and cardiovascular risk factors that is contained in each of nine alternative measures.

RESULTS

A number of the alternative indices contained a substantial proportion of the information available in Bergman's SI. The Galvin's index and the homeostasis model were most promising. However, there remained a significant amount of the information in Bergman's SI that was not contained in any of the alternative indices.

DISCUSSION

There are simpler alternative indices of insulin sensitivity for use in epidemiological studies, but each alternative is associated with some loss of information. It may be possible that this loss can be overcome with an increased sample size; however, using the alternative indices may also confound the assessment of insulin sensitivity with other underlying factors (i.e., hyperinsulinemia). The alternative indices are not recommended for the clinical assessment of insulin sensitivity for an individual patient or subject.

Cigarette smoking and other risk factors for silent cerebral infarction in the general population

BACKGROUND AND PURPOSE

Silent cerebral infarctions (SCIs) have a prevalence between 10% and 40% in the transient ischemic attack population and have been associated with increased mortality and morbidity; however, little is known about the prevalence and risk factors for SCI in the general population. This report focuses on the role of cigarette smoking and other risk factors for SCI in the general population.

METHODS

MRI scans were performed on 1737 participants selected from the general population as part of the Atherosclerosis Risk in Communities Study. Smoking status and other major cerebrovascular risk factors were assessed, and associations between smoking status and SCIs were established with the use of ANCOVA.

RESULTS

Overall, the prevalence of SCI in this population aged 55 to 70 years was 11%. Cigarette smoking had an ordered association (P=0.029) with the presence of SCI, with the odds ratio (OR) of nonsmoking participants exposed to environmental tobacco smoke being 1.06 (95% confidence interval [CI], 0.64 to 1.75) times as great as for nonsmokers not exposed; the OR of past smokers was 1.16 (95% CI, 0.74 to 1.83) times greater, and the OR of current smokers was 1.88 (95% CI, 1.13 to 3.13) times greater. An increased prevalence was also noted among black, older, and hypertensive participants.

CONCLUSIONS

This report is among the first to examine the risk factors for SCI in the general population and finds a relatively high overall prevalence (11%). There is an ordered relationship between increasing exposure to cigarette smoke and the presence of SCI that parallels the relationship between smoking and carotid atherosclerosis. The magnitude of the association with smoking is substantial compared with the effect of hypertension and other traditional cerebrovascular risk factors. The reduction in prevalence of SCI between current and past smokers and the trend that increased pack-years of smoking is related to increased prevalence of SCI are both additional arguments for smoking avoidance and cessation.

Cigarette smoking and progression of atherosclerosis: The Atherosclerosis Risk in Communities (ARIC) Study

CONTEXT

Cigarette smoking is a powerful risk factor for incident heart disease and stroke, but the relationship of active and passive smoking with the progression of atherosclerosis has not been described.

OBJECTIVE

To examine the impact of active smoking and exposure to environmental tobacco smoke (ETS) on the progression of atherosclerosis.

DESIGN

A longitudinal assessment of the relationship between smoking exposure evaluated at the initial visit and the 3-year change in atherosclerosis.

SETTING

A population-based cohort of middle-aged adults from 4 communities in the United States.

PARTICIPANTS

A total of 10914 participants from the Atherosclerosis Risk in Communities (ARIC) study enrolled between 1987 and 1989.

MAIN OUTCOME MEASURE

Change in atherosclerosis from baseline to the 3-year follow-up as indexed by intimal-medial thickness of the carotid artery assessed by ultrasound and adjusted for demographic characteristics, cardiovascular risk factors, and lifestyle variables.

RESULTS

Exposure to cigarette smoke was associated with progression of atherosclerosis. Relative to never smokers and after adjustment for demographic characteristics, cardiovascular risk factors, and lifestyle variables, current cigarette smoking was associated with a 50% increase in the progression of atherosclerosis (mean progression rate over 3 years, 43.0 microm for current and 28.7 microm for never smokers, regardless of ETS exposure), and past smoking was associated with a 25% increase (mean progression rate over 3 years, 35.8 microm for past smokers and 28.7 microm for never smokers). Relative to those not exposed to ETS, exposure to ETS was associated with a 20% increase (35.2 microm for those exposed to ETS vs 29.3 microm for those not exposed). The impact of smoking on atherosclerosis progression was greater for subjects with diabetes and hypertension. Although more pack-years of exposure was independently associated with faster progression (P<.001), after controlling for the number of pack-years, the progression rates of current and past smokers did not differ (P=.11).

CONCLUSIONS

Both active smoking and ETS exposure are associated with the progression of an index of atherosclerosis. Smoking is of particular concern for patients with diabetes and hypertension. The fact that pack-years of smoking but not current vs past smoking was associated with progression of atherosclerosis suggests that some adverse effects of smoking may be cumulative and irreversible.

Assessing differences in clinical trials comparing surgical vs nonsurgical therapy: using common (statistical) sense

The statement of hypotheses and choice of statistical tests in clinical trials that compare surgical with nonsurgical treatment are complicated by the likelihood of excess risk in the surgical group during the perioperative period but lower risk after that compared with the more uniform risk in the nonsurgical group. Commonly used statistical survival analyses implicitly assume a constant ratio of risks in the 2 groups during the follow-up period. However, the changing pattern of risk for one treatment but not the other implies that the assessment of the relative efficacy of the treatments varies with the length of the follow-up. As such, determining whether survival curves for the 2 groups are different may not translate easily into selecting the best treatment. Alternative statements of the hypothesis based on consideration of the time horizon of patients and on clinical judgment may be more consistent with the goals of the study. Regardless of the choice of a statistical test, the choice of treatment is a decision specific to the individual patient and should be influenced by the patient's life expectancy, attitude toward taking risks, quality of life, and cost considerations. When the survival curves cross, there is a trade-off between the risk of surgery and the increase in life expectancy among the survivors of surgery. Accordingly, assessment of differences in outcomes in clinical trials comparing surgical vs nonsurgical therapy should provide both a conclusion about whether 1 treatment can reasonably be considered best for most patients and should provide information to the individual patient and physician on the expected outcome to aid in the decision-making process.

Insulin sensitivity and intake of vitamins E and C in African American, Hispanic, and non-Hispanic white men and women: the Insulin Resistance and Atherosclerosis Study (IRAS)

Elevated fasting insulin concentrations and insulin resistance have been associated with non-insulin-dependent diabetes mellitus (NIDDM), obesity, atherosclerosis, and hypertension. Vitamin E supplementation in persons with and without NIDDM may be related to greater insulin sensitivity (SI). The cross-sectional associations of the intake of vitamins E and C with SI and insulin concentrations were evaluated among African American, Hispanic, and non-Hispanic white men and women with a wide spectrum of glucose tolerance included in the Insulin Resistance and Atherosclerosis Study (IRAS) (n = 1151). Insulin sensitivity was measured by minimal model analysis of a 12-sample, insulin-modified, frequently sampled intravenous glucose tolerance test. Nutrient intake (including vitamin supplement use) was assessed with a food-frequency questionnaire modified to include foods consumed by the three ethnic groups. Linear-regression models were used, including rank of SI and the log of fasting insulin as the outcome variables. Pearson correlation coefficients for vitamins E and C in relation to rank SI were r = 0.07 (P = 0.01) and r = 0.07 (P = 0.02), respectively. After adjustment for total energy and BMI these associations were no longer statistically significant and did not differ between ethnic groups. Results were similar when vitamins E and C were combined in categories of low and high antioxidant intake. Models replicated with log of fasting insulin as the outcome variable also did not produce significant associations with vitamins E or C. Thus, these cross-sectional analyses do not support the hypothesis of improved SI with increased intake of vitamins E and C.

An estrogen receptor binding site within the human galanin gene

Regulation of galanin gene expression in the anterior pituitary (AP) is positively influenced by estrogen in rodents and undetermined in humans. The objective of this study was to investigate the mechanism behind estrogen induction of galanin by identifying any putative estrogen receptor (ER) binding sequences within the human galanin promoter that may function as estrogen response elements (ERE). Two regions, gERE1 and gERE2, were identified in the galanin 5'-flanking sequence with similarity to the full 13-base ERE consensus previously defined in the vitellogenin gene (vERE). Both sequences were tested in mobility shift assays for the ability to bind nuclear proteins isolated from rat AP tissue or MtTW-10 pituitary tumors. Only the distal sequence at -527 (gERE1) yielded an ERE-specific DNA/protein complex distinguished by mobility and cross-competition with vERE. The gel mobility pattern of the DNA/protein complex was comparable between the pituitary tissue and tumor extracts. However, DNA/protein affinity estimations demonstrated a greater affinity of pituitary proteins for gERE1 over the vERE sequence. Evidence that the human ER (hER) does recognize the gERE1 sequence in the human galanin gene was provided by electrophoretic mobility shift assays (EMSAs) with Sf9 extracts enriched in recombinant hER. In addition, antibodies specific for the hER recognized the gERE1/protein complex in supershift experiments. Enhancer activity by gERE1 was detected in transient transfections of the rat GH3 pituitary cell line, resulting in a 4-fold induction of expression driven by the heterologous thymidine kinase promoter in the presence of estrogen. Evidence for ER regulation of the gERE1 enhancer was demonstrated by: 1) inhibition of enhancement using the specific ER antagonist ICI 164,384; and 2) enhancement in HeLa cells that was dependent upon coexpression with hER. Enhancement by gERE1 was half the magnitude as that from the vERE element and may reflect a difference in affinity or composition of the ER complex between the two sequences. These data demonstrate the presence of a functional ERE sequence within the human galanin gene that could potentially function as a regulatory element for estrogen action in the AP.

Relationship of a novel polymorphic marker near the human obese (OB) gene to fat mass in healthy women

The cloning of the murine obese (ob) gene and its human homologue has recently been reported. Mutations in the mouse ob gene result in hereditary obesity; however, the role of variations of OB in the regulation of bodyweight in humans has yet to be determined. The contribution of putative genetic variations in the human OB gene to total and regional fat mass in a normal twin population has been analyzed through linkage and association with a novel polymorphic marker, located in proximity to this gene. The polymorphic dinucleotide repeat, isolated from a P1 clone containing the human OB gene, was physically localized by long-range restriction mapping to within 30 kilobases of the OB locus. The marker was genotyped in a population of 47 healthy female/female dizygotic (DZ) twin pairs for which direct measures of central abdominal and whole body fat had been obtained by dual X-ray absorbtiometry. Possible linkage between the microsatellite marker and whole-body (p = 0.008), but not central abdominal (p = 0.09), fat deposits was indicated. No association between fat depot phenotype and marker genotype was detected. These results suggest that genetic variation in or close to the human OB gene may play a role in the size of body fat stores in healthy women.