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Biomedical subjects

D E House

Publications and source records attributed to D E House.

62 records · Page 4Linked to original sources
PubMedDate not supplied

The influence of vision on computerized neurobehavioral test scores: a proposal for improving test protocols.

Computerized tests of neurobehavioral function are frequently administered in neurotoxicological studies with little attention given to the optical properties of test stimuli or to the vision of subjects. Yet many test stimuli are small or briefly presented, and test endpoints often involve short reaction times. Stimulus detection and reaction time are known to be strongly dependent upon stimulus luminance, contrast, and size, as well as on the subject's visual abilities. The current study assessed the influence of visual contrast sensitivity on Neurobehavioral Evaluation System 2 (NES2) test results in three data sets. Analyses indicated that vision was associated with up to 24% of the variance (Hand Eye Coordination test) in NES2 scores, even when visual acuity was normal, and that vision often influenced the significance of group differences. It is suggested that researchers measure the luminance, contrast, and size of test stimuli, the distance from the subject's eyes to the monitor, and the subject's visual contrast sensitivity. The measurement and control of stimulus parameters and the inclusion of visual function scores in analysis models could reduce the variability among computerized test scores both within and between studies. Models that assess the influence of vision on computerized test results may help to identify the CNS domains and specialized functions adversely affected by neurotoxicant exposures.

Adolescent↗
PubMedDate not supplied

Lead absorption and psychological function in Zagreb (Croatia) school children.

A cross-sectional study was performed on 275 pupils from the third and fourth grade of three elementary schools (three urban areas with different traffic conditions) in Zagreb. Lead exposure was environmental, mostly through leaded gasoline. The difference in traffic density around the schools was consistent with biological indicators of lead absorption. The aim of the study was to clarify the relationship between characteristic biological indicators of lead absorption including indicators of hematological status with some psychological functions. Lead absorption in pupils was relatively low (mean blood lead: 70.8 +/- 17.88 microgram/L). Pupils' socio-economic status was evaluated by parents' education. The results obtained indicate that gender and school were associated with both biological and psychological variables. After adjusting for age, parental education, and gender, lead appears to have no association with cognitive or psycho-motor measures. The nonstandardized regression coefficients for blood lead-as a measure of the size of lead effect on VIQ, NIQ, and IQ-were -0.016, -0.031, and -0.025, respectively, all nonsignificant.

Child↗
PubMedDate not supplied

A survey of effects of gaseous and aerosol pollutants on pulmonary function of normal males.

A total of 231 normal male human subjects were exposed for 4 hr to air, ozone, nitrogen dioxide, or sulfur dioxide; to sulfuric acid, ammonium bisulfate, ammonium sulfate, or ammonium nitrate aerosols; or to mixtures of these gaseous and aerosol pollutants. Only one concentration of each pollutant was used. This study, therefore, represents a preliminary survey, intended to allow direct comparison of studies to plan future research. During exposure each subject had two 15-min exercise sessions on a treadmill at 4 mph and 10% grade. Environmental conditions were mildly stressful, i.e., temperature = 30 degrees C and relative humidity = 60%. A battery of 19 measurements of pulmonary function was performed just prior to exposure (air control); 2 hr into the exposure, following the first exercise session; 4 hr into the exposure, following the second exercise session; and 24 hr after exposure. Significant differences were noted in specific airway resistance (SRAW), forced vital capacity (FVC), and forced expiratory flow at 50% of FVC (FEF50) and in related measurements in those experimental groups exposed to ozone or to ozone plus aerosols. None of the aerosols alone, nitrogen dioxide or sulfur dioxide alone, or mixtures of nitrogen dioxide or sulfur dioxide with aerosols produced significant effects. A distribution analysis of subject responsivity to ozone gave a normal distribution among subjects not exposed to ozone, and a distribution shifted to the right and skewed to the right among those exposed to ozone alone or in mixture, with no evidence of bimodal distribution of ozone sensitivity.

Aerosols↗
PubMedDate not supplied

Exposure of humans to a volatile organic mixture. I. Behavioral assessment.

Exposure to a low-level mixture of volatile organic compounds, typical of those found in new buildings, has been reported to impair neurobehavioral function in persons who have experienced sick building syndrome (SBS). Sixty-six healthy young males who had no history of chemical sensitivity were exposed for 2.75 h to a complex mixture of volatile organic compounds at 0 and 25 mg/m3. Even though subjects reported more fatigue and more mental confusion following exposure to volatile organic compounds than to clean air, performance on 13 neurobehavioral tests was not affected. Practice or learning effects were observed if administration of many behavioral tests were repeated. Further studies are needed to clarify the relationship of exposure to volatile organic chemicals, neurobehavioral performance, and subject characteristics, e.g., age, gender, and chemical sensitivity.

Adolescent↗
PubMedDate not supplied

Exposure of humans to a volatile organic mixture. II. Sensory.

Time-course functions for symptoms of the sick building syndrome were derived from 66 healthy males who, during separate sessions, were exposed to clean air and to a volatile organic compound (VOC) mixture. The mixture contained 22 VOCs (25 mg/m3 total concentration) commonly found airborne in new or recently renovated buildings. Subjects rated the intensity of perceived irritation, odor, and other variables before, and twice during, 2.75-h exposure periods. Eye and throat irritation, headache, and drowsiness increased or showed no evidence of adaptation during exposure, whereas odor intensity decreased by 30%. These results indicate that irritation intensity and other symptoms are not related in any simple way to odor intensity, which suggests that the symptoms may not be a psychosomatic response to the detection of an aversive odor. Instead, subthreshold levels of VOCs may interact additively or hyperadditively and stimulate trigeminal nerve receptors. Also, air quality ratings improved by 18% during exposure, which suggests that both odor and irritation intensity may influence assessments of air quality.

Adolescent↗
PubMedDate not supplied

Effects of age, socioeconomic status, and menstrual cycle on pulmonary response to ozone.

The purpose of this study was to investigate the effects of age, socioeconomic status, and menstrual cycle phase on the pulmonary response to ozone exposure. Three hundred seventy-two healthy white and black young adults, between the ages of 18 and 35 y, were exposed only once to 0.0, 0.12, 0.18, 0.24, 0.30, or 0.40 ppm ozone for 2.3 h. Prior to and after exposure, pulmonary function tests were obtained. Prior to exposure, each subject completed a personal and family-history questionnaire. The responses to this questionnaire were used to investigate age, socioeconomic status, and menstrual cycle phase effects on pulmonary responsiveness to ozone. We concluded that the ages of subjects, within the age range studied, had an effect on responsiveness (i.e., decrements in forced expiratory volume in 1 s decreased as the subjects' ages decreased). Socioeconomic status, as reflected by education of fathers, also appeared to affect forced expiratory volume in 1-s responsiveness to ozone, with the middle socioeconomic group being the most responsive. The phase of menstrual cycle did not have an impact on individual responsiveness to ozone.

Adolescent↗
PubMedDate not supplied

Airborne exposures to PAH and PM2.5 particles for road paving workers applying conventional asphalt and crumb rubber modified asphalt.

Personal exposure monitoring was conducted for road paving workers in three states. A research objective was to characterize and compare occupational exposures to fine respirable particles (< 2.5 microns) and particle-bound polycyclic aromatic hydrocarbons (PAHs) for road paving workers applying conventional (petroleum derived) asphalt and asphalt containing crumb rubber from shredded tires. Workers not exposed to asphalt fume were also included for comparison (to support the biomarker component of this study). The rubber content of the crumb rubber modified (CRM) asphalt at the three study sites was 12, 15, and 20%. A comparison of some specific job categories from two sites indicates greater potential carcinogenic PAH exposures during CRM asphalt work, however, the site with the greatest overall exposures did not indicate any differences for specific jobs. A statistical analysis of means for fine particle, pyrene and total carcinogenic PAH personal exposure shows, with two exceptions, there were no differences in exposures for these three measurement variables. One site shows significantly elevated pyrene exposure for CRM asphalt workers and another site similarly shows greater carcinogenic PAH exposure for CRM asphalt workers. Conventional and CRM asphalt worker airborne exposures to the PAH carcinogen marker, BaP, were very low with concentrations comparable to ambient air in many cities. However, this study demonstrates that asphalt road paving workers are exposed to elevated airborne concentrations of a group of unknown compounds that likely consist of the carcinogenic PAHs benz(a)anthracene, chrysene and methylated derivatives of both. The research described in this article has been reviewed in accordance with U.S. Environmental Protection Agency policy and approved for publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.

Air Pollution↗