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.

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%.

A prospective reevaluation of transient ischemic attacks as a risk factor for death and fatal or nonfatal cardiovascular events

BACKGROUND AND PURPOSE

Transient ischemic attack (TIA) is generally considered a risk factor for death and cardiovascular events. This assumption is based on comparisons of the survival of the TIA population with that of the general population. Such comparisons may provide biased estimates of the risk associated with TIA because the general population is usually more healthy than TIA patients.

METHODS

Using a prospective case-control study design, we report the comparison of a TIA population (n = 280) and a control group (n = 399) with a comparable cardiovascular risk factor burden. Proportional hazards analysis was used to compare survival time and time to fatal or nonfatal stroke and/or myocardial infarction for the two study groups. Comparisons were made without adjustment for risk factors and after adjustment for age, race, sex, and major cardiovascular risk factors.

RESULTS

Before adjustment for age-race-sex or risk factors, TIA proved to be a risk factor for early mortality, stroke, and myocardial infarction (P < .05). Adjustment for age-race-sex disparities between the case and control groups explained much of the differences in mortality, as the hazard ratio was reduced from 2.2 to 1.4. However, adjustment for age-race-sex or age-race-sex and risk factors did not markedly reduce the role of TIA as a risk factor for stroke or myocardial infarction.

CONCLUSIONS

Although TIA proved to be a risk factor for stroke or myocardial infarction, it apparently plays a smaller role in the risk of death.

MtTW-10 pituitary tumor cells: galanin gene expression and peptide secretion

The peptide galanin is synthesized within and secreted from specific cell types of the rat anterior pituitary gland. The small size of the rat anterior pituitary gland is somewhat limiting for studying the regulation of galanin gene expression and peptide synthesis/secretion. We examined the mammotropic rat pituitary tumor MtTW-10 as a possible model system to study galanin. The objectives of this study were to 1) determine if galanin is secreted from MtTW-10 cells in vitro in a regulated manner, 2) characterize the molecular forms of immunoreactive galanin secreted by MtTW-10 cells, and 3) assess whether galanin gene expression in MtTW-10 tumors is regulated by estradiol. MtTW-10 pituitary tumors were transplanted to female Wistar-Furth rats that were implanted with estradiol-filled capsules. Cells were harvested from the MtTW-10 tumors and cultured for 4 days. When examined by electron microscopy, the MtTW-10 cells maintained in culture were irregular in shape with microvilli on their surface and contained numerous large secretory granules. Immunoreactive galanin, PRL, and GH were secreted from the cells in a time-dependent fashion during static incubations. LH, ACTH, and TSH were undetectable in the culture medium. Somatostatin (10 and 100 nM) inhibited galanin, PRL, and GH release in a dose-dependent manner. In contrast, dopamine, TRH, LH-releasing hormone, CRH, and GH-releasing hormone at concentrations of 10-100 nM failed to alter hormone secretion. Only high concentrations of dopamine (1 microM) inhibited the secretion of galanin, PRL, and GH. HPLC fractionation of peptides secreted by MtTW-10 cells cultures showed that approximately 84% of the galanin immunoreactivity coeluted with synthetic rat galanin. In tumor-bearing rats, plasma levels of immunoreactive galanin were 10-fold higher after estradiol treatment than levels in ovariectomized controls. Galanin mRNA levels were increased 20-fold by estradiol in MtTW-10 tumors, as determined by solution hybridization, and peptide levels were elevated nearly 100-fold. We conclude that 1) galanin is secreted from MtTW-10 cells in vitro, and its secretion is inhibited by somatostatin; and 2) estradiol increases galanin gene expression and peptide secretion in MtTW-10 tumors in vivo. These data show that MtTW-10 tumors may be useful to study the regulation of pituitary galanin gene expression, peptide synthesis, and secretion.

Decline in stroke mortality in North Carolina. Description, predictions, and a possible underlying cause

Data from the National Center for Health Statistics were used to describe the decline in age-adjusted stroke mortality rates from 1962 to 1987 for North Carolina and for six regions of the state. For the state as a whole, stroke mortality decreased from 0.0050 to 0.0018 (64% decrease) for white males, 0.0039 to 0.0016 (59% decrease) for white females, 0.0072 to 0.0030 (58% decrease) for black males, and 0.0064 to 0.0025 (61% decrease) for black females. Under the hypothesis that the rate of decline in stroke mortality will slow and approach a "floor," a four-parameter logistic model was fit to the data. This model suggests that most of the decline in North Carolina stroke rates had occurred by 1987 and that the rates are now approaching the floor. For example, the estimated 1987 white male stroke mortality rate was 0.00190 and the floor 0.00176, suggesting only a 7% decline in the future. Similar percentage differences between 1987 levels and the floor were estimated for the three other race-gender groups. This analysis also suggested that while the absolute disparity by sex and race decreased between 1962 and 1987, the ratio of black to white mortality rates and the ratio of male to female mortality rates remained relatively constant. Estimates of 1-year case-fatality rates from two surveys of hospitalized stroke patients in a high-mortality five-county region of North Carolina decreased from 51% in 1970 to 38% in 1980. This decrease in stroke fatality rate is sufficient to account for 64% of the decrease in mortality estimated for this region over the same period.

Carotid artery intimal-medial thickness distribution in general populations as evaluated by B-mode ultrasound. ARIC Investigators

BACKGROUND AND PURPOSE

B-mode ultrasound is a widely used technique for the clinical and epidemiological assessment of carotid atherosclerosis. This article provides a description of the distribution of carotid atherosclerosis in the general population.

METHODS

Intimal-medial arterial wall thickness was measured by B-mode real-time ultrasound as an index of atherosclerotic involvement in the extracranial carotid arteries as part of the population-based Atherosclerosis Risk in Communities (ARIC) study. The distribution was described by race-sex strata, in which 759 to 4952 individuals were imaged depending on strata and location in the carotid system.

RESULTS

Median wall thickness ranged between 0.5 and 1 mm at all ages; fewer than 5% of ARIC participants had values exceeding 2 mm. Individuals tended to have a larger wall thickness in the carotid bifurcation than in the common carotid artery. Internal carotid artery values were more variable, with higher proportions of both large and small wall thicknesses than in the common carotid. The proportion of individuals with a large wall thickness was greatest at the bifurcation and smallest at the common carotid artery. Men had uniformly larger wall thickness than women. Cross-sectional analysis suggests that age-related increases in wall thickness average approximately 0.015 mm/y in women and 0.018 mm/y in men in the carotid bifurcation, 0.010 mm/y for women and 0.014 mm/y for men in the internal carotid artery, and 0.010 mm/y in both sexes in the common carotid artery.

CONCLUSIONS

Estimates provided for wall thickness percentiles can serve as "nomograms" by age, race, and sex.

In vitro validation of color velocity imaging and spectral Doppler for velocity determination

Color velocity imaging (CVI) is a new non-Doppler ultrasound technique for vascular color flow imaging. Using information contained in the two-dimensional B-mode, gray-scale image to determine velocity, CVI offers potential advantages over Doppler color flow imaging methods. In order to be used clinically, velocity determination with CVI must be validated by other current methods. A Doppler string phantom was studied with a Philips CVI ultrasound system. Velocity measurements were obtained by both CVI and duplex Doppler spectral analysis for constant string speeds from 10 to 200 cm/sec, at intervals of 10 cm/sec. Twenty separate estimates were obtained with each method, at each string speed. Linear regression assessed the relationship between estimated and actual string velocities, with CVI and spectral Doppler analysis yielding highly valid results (CVI = -0.713 + 1.000997 x phantom; r 2 = 0.9979). At all string speeds tested, the averaged estimated and the actual velocities for both methods were within the 95% confidence estimates. The range for the CVI 95% confidence limits from the regression line varied from +/-1.07 cm/sec at the lowest speed of 10 cm/sec (11.6%) to +/-7.72 cm/sec at 200 cm/sec (3.87%). Based on in vitro testing, CVI is as accurate as Doppler spectral analysis for the estimation of flow velocity.

1993--the year of living safely

The Employment Bill aims to safeguard the rights of pregnant workers and those victimised at work on the grounds of health and safety. Gillian Howard, a barrister and industrial relations consultant, examines the new regulations.

The antiemetic effect of lorazepam after outpatient strabismus surgery in children

The high incidence of postoperative emesis after strabismus surgery in pediatric outpatients can be reduced by the prophylactic administration of droperidol 75 micrograms/kg intravenously. However, this may be associated with profound sedation, delayed discharge, dysphoria, agitation, and extrapyramidal symptoms in this population. Because lorazepam used as an antiemetic in children during chemotherapy decreased the incidence of nausea and vomiting, we compared the antiemetic effects of lorazepam and droperidol in a randomized, double-blind, placebo-controlled study of 129 healthy children undergoing surgical correction of strabismus. The children, aged 1-13 yr, were randomly allocated into three groups. The children in group 1 received droperidol 75 micrograms/kg intravenously; those in group 2 received lorazepam 10 micrograms/kg intravenously; and those in group 3 received placebo. Anesthesia consisted of halothane, nitrous oxide in oxygen, and atracurium. Study drugs were administered intravenously after induction of anesthesia but before surgery. In children 3-13 yr old, administration of either lorazepam or droperidol was associated with a lower (P < 0.024) incidence of postoperative vomiting. There was no difference between the antiemetic effect of lorazepam and that of droperidol. The incidence of postoperative agitation was greater in the droperidol group (P < 0.001) than in the lorazepam and placebo groups. Postdischarge vomiting was less (P < 0.009) in children younger than 3 yr of age. Lorazepam, similar to droperidol, has an antiemetic effect in outpatient children 3-13 yr old undergoing strabismus correction, but it is associated with less postoperative agitation than is droperidol.

Implementing the framework directive

The Management of Health and Safety Regulations will be operative from the beginning of 1993. While duties for employers are similar to those laid out by previous legislation, Gillian Howard suggests that aspects of the new Regulations will see a new role for occupational health practitioners.

Regulation of galanin gene expression in the rat anterior pituitary gland by the somatostatin analog SMS 201-995

In addition to inducing pituitary tumors in rats, estrogen (E2) markedly increases galanin and PRL gene expression. We previously showed that galanin secretion from pituitary cells in vitro is inhibited by dopamine and somatostatin and stimulated by TRH. The objectives of these in vivo studies were to assess whether the long-acting somatostatin analog SMS 201-995 alters 1) immunoreactive galanin or PRL levels in the anterior pituitary, neurointermediate lobe, hypothalamus, or plasma, 2) pituitary galanin and PRL mRNA levels, and 3) the development of E2-induced pituitary tumors. Ovariectomized Fischer 344 rats were implanted with E2-filled or empty Silastic capsules and treated with or without SMS 201-995 (1.5 mg) via Alzet miniosmotic pumps. Two or 6 weeks later, immunoreactive galanin and PRL levels were determined by RIA. In ovariectomized rats, the somatostatin analog lowered the anterior pituitary content of galanin by 50%, but had no effect on PRL concentrations. E2 increased galanin and PRL levels in the anterior pituitary by 220- and 4-fold, respectively. Concomitant E2 and SMS 201-995 treatment further increased galanin and PRL in the anterior pituitary by 60-80%, but decreased plasma galanin and PRL levels. Likewise, the administration of SMS 201-995 for 2 and 6 weeks inhibited the E2-induced growth of the anterior pituitary. Galanin and PRL mRNA levels were quantified by solution hybridization. Galanin mRNA levels were reduced to undetectable levels in ovariectomized rats treated with SMS 201-995. Furthermore, a 10-fold increase in galanin mRNA levels seen in the presence of E2 was inhibited 80% by SMS 201-995. PRL mRNA levels in E2-treated rats were unchanged by SMS 201-995. We conclude that SMS 201-995 1) lowers plasma galanin and PRL levels in E2-treated rats, 2) elevates the anterior pituitary contents of galanin and PRL in E2-exposed rats, probably through decreased secretion of the hormones, and 3) reduces galanin mRNA levels in E2-treated and untreated ovariectomized rats. Overall, these results establish the differential regulation of galanin and PRL gene expression in vivo by SMS 201-995. Moreover, the data demonstrate that somatostatin receptor agonists may have therapeutic potential for some prolactinomas.

Glutathione S-transferase expression in the human testis and testicular germ cell neoplasia

Glutathione S-transferase (GST) isoenzyme expression is altered in a variety of neoplasms and the enzymes are implicated in metabolism of carcinogens and resistance to drugs, including cisplatin. We have studied GST Alpha, Pi, Mu and microsomal isoenzyme expression by immunohistochemistry in normal and cryptorchid testes, intratubal germ cell neoplasia (ITGCN), seminoma and non-seminomatous germ cell tumours. In 16 stage II-IV malignant teratoma intermediate (MTI) both orchidectomy and post-treatment residual surgical masses were studied. All four isoenzymes were strongly expressed in Leydig and Sertoli cells. GST Pi was absent from normal spermatogonia but strongly expressed by the neoplastic germ cells of ITGCN and seminoma. GST Pi was strongly expressed in all elements of teratoma, irrespective of differentiation. There were no qualitative differences in expression between primary and post-chemotherapy metastases. GST Alpha expression in teratoma correlated with epithelial differentiation. GSTs may be important in normal spermatogenesis and protection of germ cells from teratogens and carcinogens. They may have a role in testicular tumour drug resistance but this role is not well defined. GST Pi is a new marker for ITGCN.

Dopaminergic regulation of galanin gene expression in the rat anterior pituitary gland

Estrogen dramatically increases galanin mRNA and peptide levels in the rat anterior pituitary gland. We recently reported that galanin secretion in vitro from estrogen-exposed anterior pituitary cells is regulated by hypothalamic factors; dopamine and somatostatin inhibit galanin secretion, and thyrotrophin-releasing hormone stimulates galanin release. To determine whether galanin is regulated by a dopaminergic mechanism in vivo, we used ovariectomized Fischer 344 rats treated with 17ß-estradiol-containing or empty Silastic capsules. Rats were also administered bromocriptine, a dopamine receptor agonist, haloperidol, a dopamine receptor antagonist, or placebo for 2 weeks. Galanin peptide levels were measured in the anterior pituitary, neurointermediate lobe, medial basal hypothalamus, and plasma by radioimmunoassay. Plasma and pituitary prolactin levels were also determined. Bromocriptine decreased gaianin peptide levels in the anterior pituitary gland of ovariectomized rats by 30%, but had no effect on galanin in the neurointermediate lobe or medial basal hypothalamus. In contrast, haloperidol had no effect on galanin in the anterior pituitary or medial basal hypothalamus of ovariectomized rats, but decreased galanin peptide levels in the neurointermediate lobe. In the anterior pituitary gland of estrogen-treated rats, bromocriptine increased and haloperidol decreased both galanin and prolactin levels. Galanin mRNA levels were quantified in the anterior pituitary gland by solution hybridization. Bromocriptine increased galanin mRNA levels 3-fold in the anterior pituitary, whereas haloperidol had no effect. Galanin mRNA levels in the anterior pituitary were elevated 10-fold by estrogen. Bromocriptine reduced galanin mRNA levels in the pituitary by 50% in estrogen-treated rats, where again haloperidol had no effect. Estrogen increased plasma galanin levels 4-fold compared to ovariectomized rats and this effect was reduced 60% by bromocriptine and increased 20% by haloperidol. We conclude 1) galanin synthesis and release from the estrogen-exposed anterior pituitary gland is inhibited by a dopaminergic mechanism in vivo, 2) dopamine regulates galanin gene expression in the ovariectomized rat, 3) the changes in galanin peptide levels in the anterior pituitary of rats treated with estrogen and dopamine receptor ligands are primarily due to alterations in peptide secretion, and 4) galanin release from the neurointermediate lobe may also be regulated by a dopaminergic mechanism in vivo. These data, in conjunction with previous studies, provide evidence for the co-regulation of galanin and prolactin in estrogen-treated rats, and further discriminate between the regulation of galanin in the hypothalamus and pituitary gland.

Intracerebroventricular LHRH relieves behavioral deficits due to vomeronasal organ removal

Contact between the sexes in many species is known to produce hormonal changes in the male [increases in serum luteinizing hormone (LH) and/or testosterone] that can be interpreted as due to an intracerebral release of LH-releasing hormone (LHRH). In some circumstances, these hormonal changes appear to depend on an intact vomeronasal sensory system. Exogenous LHRH is also known to facilitate mating behavior in several species. We show here that LHRH delivered into the cerebral ventricles can restore some mating behavior lost when the vomeronasal organs are removed from sexually inexperienced male hamsters. The results are consistent with our working hypothesis that intracerebral LHRH release is an intermediate in the facilitation of mating behavior by vomeronasal sensory input.