Assessment of the solubility and bioaccessibility of barium and aluminum in soils affected by mine dust deposition.

Barium is a heavy metal to which human and animal receptors may be exposed in various settings--for example, in mineral extraction industries where the mining and milling of ores occurs. Aluminum is also an element abundant in soil and dust to which human and animal receptors may be exposed in association with such industries. This study investigated the solubility and bioaccessibility of barium and aluminum in simulated gastric fluids using an in vitro test method previously validated for lead. Soil samples were collected from the vicinity of a mine and transport road that generated fugitive dust containing barium as barite (BaSO4). It was found that barium bioaccessibility in different tundra soil and fugitive dust source materials varied greatly, between 0.07 and 66.0%, depending on sample location, grain size, solid-to-fluid ratio used in the in vitro experiments, and the analytical method selected for determining total barium concentrations in the sample substrates. For X-ray fluorescence spectrometry (XRF) analytical methods and a solid-to-fluid ratio of 1:100, barium bioaccessibility from the barite-rich mine waste rock and gyro crusher ore dust source materials was very low (0.07-0.36%). By contrast, the bioaccessibility of barium in tundra soil samples affected by fugitive dust deposition ranged from 3.8 to 19.5%. The relative solubility of barium measured in the simulated gastric fluids of this study is consistent with time-dependent dissolution of barite in mine waste rock and ore dust, and the presence of more soluble chemical forms in tundra soil. Laboratory XRF analysis was the only analytical method used in this study that accurately characterized total barium concentrations for all sample substrates. Aluminum bioaccessibility was distinguished from barium bioaccessibility by its generally lower values and smaller dependence on grain size and solid-to-fluid ratios. The range of aluminum bioaccessibility values (0.31-4.0%) is consistent with the predominance of aluminum in relatively insoluble aluminosilicate minerals.

Antenatal ultrasound findings in a case of Uhl's anomaly.

A case of severe congenital Uhl's anomaly is described. Uhl's anomaly is a rare disorder characterized by near total absence of the right ventricular myocardium. Antenatal ultrasound and echocardiographic findings are presented and the differential diagnosis is discussed.

Expression of an unidentified immunoglobulin isotype on rabbit Ig-bearing lymphocytes.

A non-IgM immunoglobulin molecule was found on most rabbit Ig-bearing lymphocytes isolated from mesenteric lymph nodes. Membrane bound immunoglobulin light chains and heavy chains were detected by immunofluorescence and by rosetting with antibody-coated erythrocytes on mesenteric lymph node cells stripped of IgM by anti-IgM allotype antibodies. The percentage of cells bearing these residual immunoglobulin molecules was similar to the percentage of cells bearing immunoglobulin before "stripping" with anti-IgM antibody. These residual immunoglobulin molecules were not IgA nor IgG and are believed to be the rabbit analogue of human IgD.