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Biomedical subjects

D Bellinger

Publications and source records attributed to D Bellinger.

At least 55 records · Page 3Linked to original sources
PubMed1987

Longitudinal analyses of prenatal and postnatal lead exposure and early cognitive development.

In a prospective cohort study of 249 children from birth to two years of age, we assessed the relation between prenatal and postnatal lead exposure and early cognitive development. On the basis of lead levels in umbilical-cord blood, children were assigned to one of three prenatal-exposure groups: low (less than 3 micrograms per deciliter), medium (6 to 7 micrograms per deciliter), or high (greater than or equal to 10 micrograms per deciliter). Development was assessed semiannually, beginning at the age of six months, with use of the Mental Development Index of the Bayley Scales of Infant Development (mean +/- SD, 100 +/- 16). Capillary-blood samples obtained at the same times provided measures of postnatal lead exposure. Regression methods for longitudinal data were used to evaluate the association between infants' lead levels and their development scores after adjustment for potential confounders. At all ages, infants in the high-prenatal-exposure group scored lower than infants in the other two groups. The estimated difference between the overall performance of the low-exposure and high-exposure groups was 4.8 points (95 percent confidence interval, 2.3 to 7.3). Between the medium- and high-exposure groups, the estimated difference was 3.8 points (95 percent confidence interval, 1.3 to 6.3). Scores were not related to infants' postnatal blood lead levels. It appears that the fetus may be adversely affected at blood lead concentrations well below 25 micrograms per deciliter, the level currently defined by the Centers for Disease Control as the highest acceptable level for young children.

Child Development↗
PubMed1987

Pregnancy hypertension, blood pressure during labor, and blood lead levels.

Pregnancy hypertension, blood pressure during labor, and the umbilical cord blood lead concentration were assessed in 3851 women for whom additional demographic, medical, and personal information was available. Lead levels correlated with both systolic (Pearson r = 0.081, p = 0.0001) and diastolic (r = 0.051, p = 0.002) blood pressures during labor. The incidence of pregnancy hypertension increased with lead level. Multivariate models of pregnancy hypertension and systolic blood pressure as a function of maternal age, parity, hematocrit, ponderal index, race, and diabetes were improved by including lead as a predictor variable. At these observed levels of exposure (mean blood lead, 6.9 +/- 3.3 [SD] micrograms/dl), lead appears to have a small but demonstrable association with pregnancy hypertension and blood pressure at the time of delivery, but not with preeclampsia.

Adult↗
PubMed1986

Correlates of low-level lead exposure in urban children at 2 years of age.

The blood lead levels of a large number of US preschool children approach the value regarded as the upper limit of normal. To reduce the number of children whose levels increase into the range thought to be toxic, the antecedents and correlates of levels in the 0- to 25-micrograms/dL range must be identified. In a large longitudinal study of middle and upper-middle class children living in metropolitan Boston, we evaluated how well five sets of variables predicted children's blood lead levels at 2 years of age: environmental lead sources, mouthing activity, home environment/care giving, prior developmental status, and sociodemographic characteristics. A series of bivariate and multivariate analyses indicated that only environmental lead sources and, to a lesser extent, mouthing activity accounted for significant portions of the variance in blood lead levels. Environmental lead sources were not significantly related to the home environment/care-giving variables or to sociodemographic characteristics. The most promising approach for achieving community-wide reductions in children's blood lead levels is reduction in the amount of lead in the proximate environment.

Analysis of Variance↗
PubMed1985

Environmental correlates of infant blood lead levels in Boston.

From a blood lead survey of 11,837 births, 249 newborns were enrolled in a 2-year, longitudinal study. Their blood leads (PbB) were measured semiannually, and their homes were visited for repeated collections of dust, soil, indoor air, tap water, and paint. Recent refinishing activity and the sizes of nearby streets were recorded. Overall mean PbB was 7.2 micrograms/dl (SD = 5.3) at birth. PbB did not vary systematically with age. Each subject's average postnatal PbB correlated highly with the amount of lead in dust (r = 0.4, P less than 0.0001) and soil (r = 0.3, P less than 0.001), and with the lead in paint (r = 0.2, P less than 0.01). Dust, soil and air lead levels correlated with one another. Refinishing activity in the presence of lead paint was associated with elevations of PbB. Water lead, proximate traffic, weight of recovered dust, race, maternal age and education, and sex were not predictive of PbB. Multivariate models of PbB were constructed that become increasingly predictive with age (r2 = 20 to 37%). Indoor dust lead, lead in soil, refinishing activity, and season were the independent variables.

Air Pollutants↗
PubMed1985

Methodological issues in modeling the relationship between low-level lead exposure and infant development: examples from the Boston Lead Study.

This paper addresses several methodological issues relevant to an assessment of the association between low-level lead exposure and early development. In particular, we discuss methods for choosing, from a large pool of candidates, the covariates to control when estimating this association. We examine the issue of confounding and explain why adjusting increased, rather than decreased, the estimate of the association between blood lead level and development at 6 months of age in our sample. A step-by-step description of our strategy for model building is presented. Finally, we demonstrate the robustness of the findings by showing that the magnitude and standard error of the estimated lead effect is not affected appreciably by the method of selecting covariates to be controlled for or by the characterization of lead as a continuous, ordinal, or dichotomous variable. Although these issues arose in the course of analyses of data collected by the Boston lead study (D. Bellinger, H. Needleman, A. Leviton, C. Waternaux, M. Rabinowitz, and M. Nichols (1984), Neurobehav. Tox. Teratol., 6, 387-402), they apply to other current prospective lead studies as well.

Analysis of Variance↗
PubMed1985

Home refinishing, lead paint, and infant blood lead levels.

We measured the blood lead levels of 249 infants semi-annually from birth to two years of age; we sampled the home paint and recorded any recent home refinishing activity. Mean blood lead from birth to age 2 years did not vary systematically with age but did correlate significantly with the amount of lead in the indoor paint (p less than .01). Refinishing activity in homes with high lead paint was associated with elevations of blood lead averaging 69 per cent.

Adult↗
PubMed1980

Electrocardiographic studies in African green monkeys (Cercopithecus aethiops).

Electrocardiograms obtained as part of a pre-experimental clinical examination were analyzed for a newly purchased group of 46 male African green vervets. In general, they were similar to electrocardiograms reported for other Old World species. An unexpectedly high prevalence (17%) of electrocardiogram abnormalities was found in this young (4--6 years of age) vervet population. The main abnormalities were nonspecific T wave flattening, left axis deviation, peaked P waves, RSR' patterns, and abnormally deep Q waves.

Animals↗
PubMedDate not supplied

Low-level lead exposure, social class, and infant development.

A prospective cohort study was conducted to assess the association between early development and low-level prenatal and postnatal lead exposure. Infants' performance between 6 and 24 months on the Mental Development Index of the Bayley Scales of Infant Development declined with increasing concentration of lead in blood, but the decline varied with children's age at exposure, level of exposure, and socioeconomic status. Within the second year of life, the performance of children in lower socioeconomic strata was adversely affected at lower levels of prenatal exposure (blood lead levels of 6 to 7 micrograms/dl) than was the performance of children in higher socioeconomic strata. However, even the performance of these advantaged infants was lower when cord blood lead level exceeded 10 micrograms/dl, well below the figure currently regarded as the maximum permissable level for young children. Exploratory analyses suggested that early postnatal blood lead levels between 10 and 25 micrograms/dl were also associated with lower Mental Development Index scores, but only among children in lower socioeconomic strata.

Aging↗
PubMedDate not supplied

Attentional correlates of dentin and bone lead levels in adolescents.

In an effort to determine whether specific aspects of attention are impaired by lead, the performance of 79 subjects (aged 19 and 20 y) on a neuropsychologically based battery of tests of attention was examined in relation to lead levels in deciduous teeth (dentin), current blood, and tibia and patella bones measured by K-X-ray fluorescence. Dentin lead levels averaged 14 micrograms/g. Most bone lead levels were less than 10 micrograms/g. Dentin lead levels were related inversely to scores on two of four attention factors: focus-execute (ability to select and respond to critical information) and shift (ability to shift focus adaptively). Few significant associations were observed between bone lead levels and performance. Five individuals with the ALA-D 1-2 isozyme phenotype tended to achieve more optimal scores. Executive and self-regulation functions may be among the cognitive skills targeted by lead.

Adolescent↗
PubMedDate not supplied

Longitudinal relationship between dentin lead levels in childhood and bone lead levels in young adulthood.

A retrospective cohort study was conducted to examine the relationship between tooth lead in children and bone lead levels in young adults. Members of a cohort of young adults were reassessed 13 y after initial examination at an ambulatory clinical research center. Dentin lead levels were measured by anodic stripping voltammetry during the years 1975-1978, and bone lead levels of the tibia and patella were measured by K-x-ray fluorescence technique during 1989 and 1990. A total of 63 subjects who had no history of chelation or had no missing information on potential confounders were studied. The median follow-up interval was 13.2 y. Dentin lead levels averaged 13.4 micrograms/g (standard deviation [SD] = 10.7 micrograms/g, range = 2.9-51.8 micrograms/g), and bone lead levels averaged 1.3 micrograms/g (SD = 4.4 micrograms/g, range = -9-13 micrograms/g) for tibia and 5.4 micrograms/g (SD = 8.4 micrograms/g, range = -10-25 micrograms/g) for patella. The authors controlled for age, sex, race, and mother's socioeconomic status, and dentin lead levels were predictive of higher tibia, patella, and mean bone lead levels in 32 subjects (follow-up interval of 11.8-13.2 y). A correction for measurement errors in dentin lead measurements was made, and it was determined that a 10-micrograms/g increase in dentin lead levels in childhood was predictive of a 1-microgram/g increase in tibia lead levels, a 5-micrograms/g increase in patella lead levels, and a 3-micrograms/g increase in mean bone lead levels among the young adults. It was concluded, therefore, that lead exposure in early life may be used to predict elevated body burden up to 13 y later.

Adolescent↗
PubMedDate not supplied

Processing of rapid auditory stimuli in school-age children referred for evaluation of learning disorders.

Tallal hypothesized that reading disabled children have a domain-general deficit in processing rapidly occurring auditory stimuli that degrades speech perception, thereby limiting phonologic awareness and thus reading acquisition. She predicted they would be disproportionately affected by rapidly presented auditory stimuli. In this study, one hundred 7- to 11-year-old children with learning impairment (LI) and 243 non-learning impaired (NLI) children were evaluated on a two-tone auditory discrimination paradigm. LI committed more errors, but effects of timing were comparable. The same result was obtained for a subsample of good and poor readers. Task performance predicted reading, spelling, and calculation. Neural processes underlying perception of speech and other auditory stimuli may be less effective in poor readers; however, contrary to Tallal's hypothesis, rate may not be specifically affected.

Achievement↗
PubMedDate not supplied

Coronary atherosclerosis in the pig. Induced plaque injury and platelet response.

The thrombogenic potential of atherosclerotic diet-induced coronary atherosclerotic plaques was investigated in normal swine and in bleeder swine with homozygous von Willebrand disease. Fourteen paired normal and bleeder swine were placed on a 1% cholesterol diet for 1 to 16 weeks. Serum cholesterol was elevated in all animals at sacrifice. Foam cell deposits developed in all major epicardial coronary arteries, and lesions progressed over time from small subendothelial foam cell deposits to fibrous cap lesions that contained foam cells, elastic fibers, collagen, degenerative material, and smooth muscle cells. Balloon catheter injury resulted in platelet deposition, largely in a monolayer or as small platelet clumps devoid of fibrin. Lipid debris was present in injured areas of the subendothelium but did not induce thrombus formation. When the injury involved the media, platelet-fibrin thrombi were formed. Lipid was not present in these thrombi. Morphometric analysis of platelet deposition on ballooned atherosclerotic vessels showed similar numbers of platelets in both phenotypes. However, the attached platelets in bleeder pigs showed significantly less spreading than did those in the normal animals. The results show that injury to intimal foam cell and mixed cellular lesions in coronary arteries of cholesterol-fed swine does not promote the development of platelet-fibrin thrombus formation. In contrast, when the injury extended to the media, mixed thrombi were formed.

Animals↗