The Evolution of Targeted Populations in a School-Based Tuberculin Testing Program

A review of tuberculosis surveillance data from a program of school-based tuberculin testing demonstrates the natural evolution of targeted populations. In the 7 years encompassed by this study, the prevalence of tuberculin reactivity ranged from 4.3 % to 6.1 % in the Amarillo public school populations which were tested. The initial screening was a sampling of all students in the school district. In subsequent years' screening, the targeted populations were increasingly refined to eliminate lower-risk populations. Children enrolled in "English as a Second Language" (ESL) classes were found to have an 8.5% tuberculosis infection rate. The purpose of this study was to alert nurses that culturally sensitive approaches are needed for successful future testing.     

An optical method of studying the shape and movement of the chest wall in recumbent patients

A method of optical mapping has been developed that allows the shape and motion of the chest wall to be studied in recumbent patients. It uses a single camera at a fixed viewpoint to determine the three dimensional coordinates of the visible surface of the body, and hence to measure the volume and shape of the visible segment. Measurements on different test objects (volumes 228-7807 ml) in different positions suggest a reproducibility of volume measurement of +/- 26 ml (SD) and a maximum volume error of 150 ml. Studies of computed tomography scans in inspiration and expiration show that it should be possible to capture 97% of respiratory motion by this method. The mean difference between optical and spirometric measurements of expired volume in six subjects was 0.25 (SD 0.2) 1. Within subject systematic errors of up to 10% were noted. The mean deviation about the regression line of optically measured expired volume on spirometric expired volume varied from 68 to 243 ml in the six subjects (mean 131 (SD 92) ml). To examine the potential of the optical technique, for rapid data acquisition it was used to construct a 24 point flow volume loop from a normal subject.     

Oxidation of amino acids by human neutrophils

We studied the oxidation of alanine and methionine by human neutrophils. Phagocytosis enhanced the decarboxylation of amino acids by human neutrophils. Decarboxylation of amino acids was dependent on the myeloper-oxidase system (MPO-H₂O₂-Cl^–). This was further confirmed using purified canine MPO. Human neutrophils and the MPO system were about 10 times more efficient in decarboxylating alanine than methionine. They also oxidized methionine to methionine sulfoxide. The fraction of methionine decarboxylated by human neutrophils or the MPO system was small compared to the fraction which was oxidized to methionine sulfoxide. Thus methionine was preferentially oxidized to methionine sulfoxide by the MPO system. However, once methionine was oxidized to methionine sulfoxide, it was readily decarboxylated by the MPO system. The results suggest that the thio group of methionine prevents its carboxylic group from being decarboxylated.     

Gas-phase ambient air contaminants exhibit significant dioxin-like and estrogen-like activity in vitro

Several adverse health effects, such as respiratory and cardiovascular morbidity, have been linked to exposure to particulate matter in ambient air; however, the biologic activity of gas-phase ambient organic air contaminants has not been examined as thoroughly. Using aryl hydrocarbon receptor (AHR)-based and estrogen receptor (ER)-based cell bioassay systems, we assessed the dioxin-like and estrogenic activities of gas-phase organic ambient air contaminants compared with those of particulate-phase contaminants using samples collected between seasons over 2 years from an urban and a rural location in the Greater Toronto Area, Canada. The concentration of the sum (Sigma) of polycyclic aromatic hydrocarbons, which was highest in the gas phase, was 10-100 times more abundant than that of Sigmapolychlorinated biphenyls, Sigmanitro-polycyclic aromatic hydrocarbons, and Sigmaorganochlorine pesticides, and 10(3) to 10(4) times more abundant than Sigmapolychlorinated dibenzo-p-dioxins/dibenzofurans. Gas-phase samples induced significant AHR- and ER-dependent gene expression. The activity of the gas-phase samples was greater than that of the particulate-phase samples in the estrogen assay and, in one case, in the AHR assay. We found no strong associations between either summer or winter seasons or urban or rural locations in the relative efficacy of the extracts in either the ER or AHR assay despite differences in chemical composition, concentrations, and abundance. Our results suggest that mechanistic studies of the health effects of ambient air must consider gas and particulate phases because chemicals present in both phases can affect AHR and ER signaling pathways.