Increased age, high body mass index and low HDL-C levels are related to an echolucent carotid intima-media: the METEOR study

INTRODUCTION

Echolucent plaques are related to a higher cardiovascular risk. Studies to investigate the relationship between echolucency and cardiovascular risk in the early stages of atherosclerosis are limited. We studied the relationship between cardiovascular risk factors and echolucency of the carotid intima-media in low-risk individuals.

METHODS

Data were analysed from the Measuring Effects on Intima-Media Thickness: an Evaluation of Rosuvastatin (METEOR) study, a randomized placebo-controlled trial including 984 individuals which showed that rosuvastatin attenuated the rate of change of carotid intima-media thickness (CIMT). In this post hoc analysis, duplicate baseline ultrasound images from the far wall of the left and right common carotid arteries were used for the evaluation of the echolucency of the carotid intima-media, measured by grey-scale median (GSM) on a scale of 0-256. Low GSM values reflect echolucent, whereas high values reflect echogenic structures. The relationship between baseline GSM and cardiovascular risk factors was evaluated using linear regression models.

RESULTS

Mean baseline GSM (± SD) was 84 ± 29. Lower GSM of the carotid intima-media was associated with older age, high body mass index (BMI) and low levels of high-density lipoprotein cholesterol (HDL-C) [beta -4.49, 95% confidence interval (CI) -6.50 to -2.49; beta -4.51, 95% CI -6.43 to -2.60; beta 2.45, 95% CI 0.47 to 4.42, respectively]. Common CIMT was inversely related to GSM of the carotid intima-media (beta -3.94, 95% CI -1.98 to -5.89).

CONCLUSION

Older age, high BMI and low levels of HDL-C are related to echolucency of the carotid intima-media. Hence, echolucency of the carotid intima-media may be used as a marker of cardiovascular risk profile to provide more information than thickness alone.

Working on the hot seat: urban bus operators

City bus operators suffer elevated health risks and striking levels of absenteeism and medical disability that may be related to occupational stress. This article provides a critical overview of findings on urban bus drivers' health status, paying particular attention to aspects of the physical and psychosocial job environment that may cause ill health. Methodological shortcomings in the research are discussed and preliminary ideas for salutagenic interventions are proposed.

Household crowding and social support: a quasiexperimental analysis

People often cope with crowded living conditions by socially withdrawing from their housemates. This coping strategy may overgeneralize, influencing social interactions with others outside the home. In a stressful laboratory situation, Ss from crowded homes, in comparison with uncrowded counterparts, are less likely to seek support from a confederate and rate the confederate as less supportive. Moreover, Ss from crowded homes are less likely to offer support to a confederate in need. These differences in social interaction behaviors appear to be attributable to crowded residents' social withdrawal.

Cerebral infarction verified by cranial computed tomography and prognosis for survival following transient ischemic attack

Of 564 consecutive patients with transient ischemic attack, 350 (62%) had cranial computed tomography performed. Except for date of admission and smoking history, there were few differences between the patients evaluated with computed tomography and the 214 who were not. Cerebral infarcts were found in 59 (17%) of the 350 tomographic evaluations. Previous clinically diagnosed stroke, older age, and male sex were all significantly associated with the occurrence of tomographically verified infarcts (p less than 0.05). After controlling for stroke history and other important covariates, patients with tomographically verified infarcts had significantly shorter survival times than did patients without evidence of infarction on computed tomography (p = 0.035). Thus, cranial computed tomography findings appear to have important prognostic value for estimating survival following transient ischemic attack.

Dynamic role of social support in the link between chronic stress and psychological distress

How a chronic environmental stressor can interfere with the buffering effects of social support by eroding social support was analyzed in this prospective, longitudinal study. A classic buffering effect of support was found after 2 months of exposure to the stressor, household crowding. Crowded residents with low perceived support had greater increases in psychological distress than did crowded residents with high perceived support. However, after 8 months exposure the buffering effect disappeared. Moreover, greater crowding had become directly associated with lower support, which in turn was associated with greater increases in psychological distress. All analyses controlled for prior distress. Under some types of chronic stress, the buffering effects of social support may be short-lived because the stressor eventually erodes social support.

Childhood social inequalities influences neural processes in young adult caregiving

Childhood poverty is associated with harsh parenting with a risk of transmission to the next generation. This prospective study examined the relations between childhood poverty and non-parent adults' neural responses to infant cry sounds. While no main effects of poverty were revealed in contrasts of infant cry versus acoustically matched white noise, a gender by childhood poverty interaction emerged. In females, childhood poverty was associated with increased neural activations in the posterior insula, striatum, calcarine sulcus, hippocampus, and fusiform gyrus, while, in males, childhood poverty was associated with reduced levels of neural responses to infant cry in the same regions. Irrespective of gender, neural activation in these regions was associated with higher levels of annoyance with the cry sound and reduced desire to approach the crying infant. The findings suggest gender differences in neural and emotional responses to infant cry sounds among young adults growing up in poverty.

Zinc absorption in the rat determined by radioisotope dilution

Zinc absorption in rats was examined by use of an isotope dilution technique. Young rats and mature rats fed varying levels of dietary zinc were injected intramuscularly with 65Zn. Nine days later, a zinc balance study was begun and continued for 5 days. The rats were then decapitated and the intestines and kidneys were removed and analyzed for zinc and 65Zn content. The feces were analyzed for zinc and 65Zn content and the specific activities of the intestines and kidneys were used to compute the contribution of endogenous zinc to total daily zinc excretion and thus calculate the true daily absorption of zinc. The zinc concentration of the intestines and kidneys did not differ significantly among groups but the specific radioactivity in these organs decreased as dietary zinc intake increased. Endogenous zinc excretion was greatest in mature rats and young rats fed the highest level of dietary zinc. Mature rats actually absorbed as much or more zinc than young rats fed the same dietary level of zinc. The results demonstrate that zinc homeostasis in rats is maintained by zinc secretion from the intestine rather than by regulation of zinc absorption.

Relative zinc availability in human breast milk, infant formulas, and cow's milk

The concentration and bioavailability of zinc was analyzed in 10 varieties of milk. The concentration of zinc averaged 4.1 microgram/ml in unprocessed (raw) cow's milk; fortified infant formulas contained about 3 to 5 microgram Zn/ml; human breast milk and processed cow's milk contained approximately 2 microgram Zn/ml; sweetened condensed milk contained 1.3 microgram Zn/ml, and reconstituted nonfat dry milk contained 0.4 microgram Zn/ml. The mean values for zinc bioavailability to rats were as follows: sweetened condensed milk = 66%; human breast milk 59.2%, processed cow's milk = 43.7 to 50.9%; unprocessed (raw) cow's milk = 42%; nonfat dry milk = 41.2%, and infant formulas = 26.8 to 39.5%. Assuming similar absorption of zinc in rats and humans, our experimental results provide some guidelines for estimating the quantity of zinc that would actually be absorbed from various types of milk.

Effect of iron, vitamin B-6 and picolinic acid on zinc absorption in the rat

True daily zinc absorption was determined in rats fed a high iron diet (220 ppm Fe; 16.5 ppm Zn), and adequate iron diet (30 ppm Fe) and a high iron diet with varying levels of pyridoxine-HCl (2-40 ppm). Zinc absorption in rats fed the high iron diet was significantly less than in rats fed the adequate iron diet. Zinc absorption in rats fed the high iron diet supplemented with picolinic acid (200 ppm) was markedly increased and did not differ from that in rats fed the adequate iron diet. True, daily zinc absorption increased as the level of dietary vitamin B-6 was increased. Zinc absorption was the least in rats fed 2 ppm vitamin B-6 and was greatest in rats fed 40 ppm vitamin B-6. The concentration of picolinic acid in the pancreas increased as the level of dietary vitamin B-6 was increased. Zinc absorption was significantly elevated in rats fed the high iron diet that contained either 4 or 10 ppm vitamin B-6 and 200 ppm picolinic acid. The turnover rate of 65Zn was determined in rats fed an adequate iron, marginal zinc diet (8.5 ppm Zn) with varying levels of vitamin B-6. The turnover of 65Zn was greatest in rats fed 2 ppm vitamin B-6 and least in rats fed 40 ppm vitamin B-6 or 2 ppm vitamin B-6 + 200 ppm picolinic acid. The results suggest that high levels of dietary iron inhibit zinc absorption via competition for binding with endogenous picolinic acid. The results provide further evidence to support the hypothesis that picolinic acid facilitates absorption of dietary zinc.

Identification of crystals deposited in brain and kidney after xylitol administration by biochemical, histochemical, and electron diffraction methods

The positive identification of crystals of calcium oxalate occurring in brain and kidney after xylitol administration is described. Biochemical, histochemical, conventional light and electron microscopical methods, including selected area electron diffraction, were used to characterize the crystals.

Effect of acute infection and endotoxemia on zinc absorption in the rat

Intestinal zinc absorption was found to be significantly increased during acute bacterial infection and endotoxemia in the rat. Although serum zinc concentrations were depressed, there was a significant accumulation of 65Zn in the livers of the stressed animals. This study demonstrates that acute inflammation produces a redistribution of zinc within the host, which results in both increased zinc absorption and retention.

Intensive lipid lowering may reduce progression of carotid atherosclerosis within 12 months of treatment: the METEOR study

BACKGROUND

In several statin trials, vascular event rates for treatment groups begin to separate 1 year after commencement of treatment. For atherosclerosis progression, the temporal sequence of the effect has not been defined. We used data from the Measuring Effects on intima media Thickness: an Evaluation Of Rosuvastatin (METEOR) trial to determine the earliest time point at which significant differences in atherosclerosis progression rates could be detected after initiation of statin therapy.

METHODS

The METEOR trial was a double-blind, randomized placebo-controlled trial that studied the effect of LDL-C lowering with 40 mg rosuvastatin on the rate of change of carotid intima media thickness (CIMT) measured by B-mode ultrasound amongst 984 low risk subjects. Ultrasound assessments were made at baseline and every 6 months up to 2 years.

RESULTS

Rosuvastatin treatment was associated with a 49% reduction in LDL-C-C, a 34% reduction in total cholesterol, an 8.0% increase in HDL-C and a 16% reduction in triglycerides (all P < 0.0001 compared with placebo). The difference in rate of mean maximum CIMT progression between the rosuvastatin and placebo groups (based on near and far wall measurements from both left and right common carotid and internal carotid segments and carotid bifurcation) was not statistically significant after 6 months (0.0023 mm year(-1) and 0.0106 mm year(-1), respectively P = 0.34). After 12 months, CIMT progression rates were significantly different between the groups: 0.0032 mm year(-1) and 0.0133 mm year(-1) in the rosuvastatin-treated and placebo-treated groups, respectively (P = 0.049). This divergence grew with further follow-up: -0.0009 mm year(-1) and 0.0131 mm year(-1) after 18 months (P < 0.001) and -0.0014 mm year(-1) and 0.0131 mm year(-1) after 24 months of treatment (P < 0.001). Results were stronger for the mean common CIMT progression (based on near and far wall measurements from both left and right common carotid segments).

CONCLUSION

Aggressive LDL-C lowering seems to exert its beneficial effect on atherosclerosis progression during the first 12 months of treatment. This parallels the timing of event reduction seen in clinical trials and suggests that the efficacy of lipid lowering treatment on CIMT progression can be evaluated in trials with a duration of 1 year, given sufficient sample size, high precision of measurements and a treatment effect comparable to that seen in METEOR.

Variability in ultrasonic measurements of arterial stiffness in the Atherosclerosis Risk in Communities study

Arterial stiffness is emerging as an important risk marker for cardiovascular disease. Ultrasound-based measurements of arterial stiffness are in use by several large epidemiological studies. The reliability of ultrasonic measurements of arterial stiffness was assessed as part of one of these, the Atherosclerosis Risk in Communities (ARIC) study. ARIC, a prospective, four-center epidemiological study, used B-mode ultrasound with an electronic tracking device to measure arterial stiffness of the carotid artery. Oscillometric blood pressure measures were obtained before and after the arterial wall tracking. Measurement variability was estimated in 36 volunteers who were scanned at three visits conducted at 7- to 14-day intervals. Between- and within-person components of variation were estimated for arterial diameter and blood-pressure measurements. The correlation (R) between repeated measurements for pulse pressure, the percent change in arterial diameter (strain), and the percent and absolute change in the arterial area were 0.69, 0.67, 0.66 and 0.81, respectively. The R for the stress-strain elastic modulus (Ep), arterial distensibility, and arterial compliance were 0.66, 0.67, and 0.77, respectively. The R for the pressure-adjusted diameter change (i.e., diameter change adjusted for diastolic and pulse pressures) was 0.75. In summary, the ultrasonic measurements of arterial stiffness employed in the ARIC study demonstrate excellent short-term repeatability, demonstrating their utility in field settings.

The role of planning skills in the income-achievement gap

The pervasive income-achievement gap has been attributed in part to deficiencies in executive functioning (EF). The development of EF is related to children's planning ability, an aspect of development that has received little attention. Longitudinal data from the National Institute of Child Health and Human Development study of early child care show that early childhood poverty (1 and 24 months) is significantly related to fifth grade, math, and reading achievement (n = 1,009). The ability to plan in Grade 3, indexed by the Tower of Hanoi task, mediates the income-achievement gap in math and to a lesser extent in reading. IQ was incorporated as a statistical control throughout.

Determination of zinc availability in foods by the extrinsic label technique

The absorption of intrinsic 65Zn and extrinsic 65Zn from corn and liver was measured in rats. No significant difference between the absorption of intrinsic- and extrinsic-label was observed. These results indicate that endogenous zinc and exogenous 65Zn enter a common pool prior to being absorbed from the intestine. Since extrinsic 65Zn enters a common pool with intrinsic zinc, whole-body absorption of extrinsic 65Zn can be used to obtain an accurate estimate of the availability of zinc in food. The availability of zinc in human breast milk, in cow's milk, in infant formulas, and in reconstituted dry milk was analyzed by use of the extrinsic label. The zinc in human breast milk was most available (59%) while the zinc in the infant formulas was the least available (26 to 37%). Zinc from both raw and cooked corn was more available than zinc from either cooked or uncooked rat liver.

The distribution of costs of care in mechanically ventilated patients with chronic obstructive pulmonary disease

OBJECTIVES

To delineate the costs of care of patients with Chronic Obstructive Pulmonary Disease (COPD) and respiratory failure and to compare them with those of other mechanically ventilated patients.

DESIGN

A post hoc analysis of a prospective investigation.

SETTING

Medical and coronary intensive care units (ICUs) of an 804-bed, university-based hospital.

PATIENTS

A total of 300 mechanically ventilated patients, 44 with COPD and 256 others, were included.

MEASUREMENTS AND MAIN RESULTS

Despite similar lengths of ICU stay (9 days) and mechanical ventilation (5.5 days COPD vs. 5 days other, p = .11), ICU respiratory care costs for patients with COPD were $2,422 ($1,157-$6,110) [median U.S. dollars (interquartile range)] vs. $1,580 ($738-$3,322) for the others (p = .01). Ventilator costs for COPD patients were $1,795 ($943-$5,782) vs. $1,574 ($613-$3,112) (p = .12). Total hospitalization respiratory care costs for COPD patients were higher, $4,064 ($2,422-$9,572) vs. $2,342 ($1,186-$4,591), (p = .0001), and 74.4% of the median difference in cost between COPD patients and others was accounted for by spontaneous nebulizers (p = .001), metered dose inhalers (p = .01), and pulse oximetry (p = .02). By using multiple linear regression analyses, we found that COPD remained associated with higher respiratory costs (p<.05). Respiratory Care was the third largest category of hospital costs after beds (27%) and pharmacy expenses (25%), and it comprised approximately 14% of total cost. Total hospital costs were large for both groups, but did not differ between COPD and the others [$24,217 ($16,211-$58,834) vs. $27,672 ($15,692-$53,766), respectively (p = .96)]. Linear regression analyses showed that only Acute Lung Injury score was significantly related to total ICU and hospital costs of care (p<.05).

CONCLUSIONS

Costs of ICU and non-ICU respiratory care for patients with COPD are higher than costs of care for other mechanically ventilated patients. Although the increased cost of bronchodilators and oximetry in these patients may serve as target areas for reductions in respiratory care costs, it may also be true that these modalities of therapy and management are necessary and need to be used with even greater intensity to achieve better outcomes. The predominant contributions of bed and pharmacy costs in all of our patients with respiratory failure support research efforts addressing these aspects of care.

Loosening the link between childhood poverty and adolescent smoking and obesity: the protective effects of social capital

Pervasive, lifelong inequalities in physical health begin in early childhood and are driven, in part, by social gradients in risk factors such as smoking and obesity. Yet not all low-income children have elevated physical-health risks as adults. The relation between income-to-needs ratio at age 9 and smoking prevalence and body fat (body mass index) at age 17 was examined in a sample of 196 rural adolescents. Income-to-needs ratio is the U.S. federal government's defined index of household income as a proportion of the poverty line. This is the first study to show that links between childhood poverty and subsequent physical-health outcomes can be loosened. At-risk youth in communities with a relatively rich array of social capital did not smoke more or have greater excess body fat compared with their more affluent counterparts.

Rapid intravenous infusion of amphotericin B: a pilot study

PURPOSE

The administration of amphotericin B in the conventional prolonged infusion over 4 to 6 hours is complicated by the acute toxicities of fevers and chills in 50% to 90% of patients and the chronic toxicities of increased creatinine levels and hypokalemia in 60% to 80% of patients. To determine the safety and toxicity of rapid infusions, we conducted a prospective, nonrandomized study in patients with clinical indications for antifungal therapy.

PATIENTS AND METHODS

Twenty-five granulocytopenic adults with acute leukemia and myelodysplastic syndromes were enrolled in a phase I trial using four sequentially shorter infusion durations: a standard infusion over 4 hours (n = 3) and shortened infusion durations at 3 hours (n = 3), 2 hours (n = 4), and 1 hour (n = 15). Toxicity was assessed by daily examinations of study subjects by one of the study investigators, by documentation of all infusion-related fevers and chills, and by daily monitoring of serum levels of creatinine, potassium, magnesium, and aspartate aminotransferase.

RESULTS

Temperatures greater than 38 degrees C occurred in 16 of 25 (64%) patients, but only two had temperatures exceeding 40 degrees C. Chills were observed in 13 of 25 (56%) patients, but only one had severe symptoms. Serum creatinine increased more than 0.5 mg/dL (44.20 mumol/L) above the pretreatment baseline in 17 of 25 (68%) patients, and the absolute creatinine level was greater than or equal to 2.0 mg/dL (176.8 mumol/L) in 10 of 25 (40%) patients. Serum potassium levels dropped below the normal limit of 3.5 mEq/L (3.5 mmol/L) in all patients, but no patient had potassium levels below 2.5 mEq/L (2.5 mmol/L). Intravenous potassium supplementation was administered to all patients and exceeded 100 mEq/d in 12 of 25 (48%) patients.

CONCLUSIONS

Rapid infusions of amphotericin B are safe, are associated with similar toxicity as prolonged infusions, and facilitate inpatient care by decreasing nursing time needed for administration and minimizing scheduling conflicts with other necessary intravenous medications. Shorter infusions also facilitate outpatient and home administration of amphotericin B.

Parental language and verbal responsiveness to children in crowded homes

This article is a secondary data analysis of the University of Kansas Language Acquisition Project, which intensively studied, on a regular basis, parent and child language from age 6 months to 30 months. The association between residential density and parent-child speech was examined. Parents in crowded homes speak in less complex, sophisticated ways with their children compared with parents in uncrowded homes, and this association is mediated by parental responsiveness. Parents in more crowded homes are less verbally responsive to their children. This in turn accounts for their simpler, less sophisticated speech to their children. This mediational pathway is evident with statistical controls for socioeconomic status. This model may help explain prior findings showing a link between residential crowding and delayed cognitive development.

Arterial distensibility and physical activity in the ARIC study

PURPOSE

Arterial distensibility decreases with age. This decrease may be associated with the initiation and/or progression of hypertension and atherosclerosis and may be attenuated by positive lifestyle habits, including habitual physical activity. We tested the hypothesis that self-reported sport, leisure, and work physical activity is associated with greater arterial distensibility (i.e., carotid artery pulsatile diameter changes).

METHODS

The Atherosclerosis Risk in Communities (ARIC) study assessed left common carotid arterial diameters and intimal-medial wall thickness (IMT) using B-mode ultrasound techniques, in 10,644 African-American and white men and women aged 45-64 yr and free of cardiovascular disease.

RESULTS

Work activity, but not sports or leisure activity, was weakly associated with greater arterial distensibility in an ANCOVA model adjusted for blood pressure and other covariates (diastolic arterial diameter, pulse pressure, pulse pressure squared, age, race, sex, smoking, dietary fat intake, height, education, and clinical center) (P for linear trend = 0.03). Vigorous sports activity was weakly positively associated with arterial distensibility (arterial diameter change (mean +/- SE in mm) 0.42 +/- 0.004 vs 0.41 +/- 0.002 for the 12.7% of participants reporting any vs no vigorous activity, P = 0.02), and this association was not attenuated by adjustment for IMT, body mass index, low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, or diabetes. Repeated analyses with traditional arterial stiffness indices showed similar findings for vigorous but not work activity.

CONCLUSION

In contrast to several smaller studies, these findings do not support the hypothesis that habitual physical activity has a strong, consistent positive effect on arterial distensibility.