Comparison of workplace protection factors for different biological contaminants

This study compared workplace protection factors (WPFs) for five different contaminants (endotoxin, fungal spores, (1→3)-β-D-glucan, total particle mass, and total particle number) provided by an N95 elastomeric respirator (ER) and an N95 filtering facepiece respirator (FFR). We previously reported size-selective WPFs for total particle numbers for the ER and FFR, whereas the current article is focused on WPFs for bioaerosols and total particle mass. Farm workers (n = 25) wore the ER and FFR while performing activities at eight locations representing horse farms, pig barns, and grain handling facilities. For the determination of WPFs, particles were collected on filters simultaneously inside and outside the respirator during the first and last 15 min of a 60-min experiment. One field blank per subject was collected without actual sampling. A reporting limit (RL) was established for each contaminant based on geometric means (GMs) of the field blanks as the lowest possible measurable values. Depending on the contaminant type, 38-48% of data points were below the RL. Therefore, a censored regression model was used to estimate WPFs (WPF(censored)). The WPF(censored) provided by the two types of respirators were not significantly different. In contrast, significant differences were found in the WPF(censored) for different types of contaminants. GMs WPFs(censored) for the two types of respirators combined were 154, 29, 18, 19, and 176 for endotoxin, fungal spore count, (1→3)-β-D-glucan, total particle mass, and total particle number, respectively. The WPF(censored) was more strongly associated with concentrations measured outside the respirator for endotoxin, fungal spores, and total particle mass except for total particle number. However, when only data points with outside concentrations higher than 176×RL were included, the WPFs increased, and the association between the outside concentrations and the WPFs became weaker. Results indicate that difference in WPFs observed between different contaminants may be attributed to differences in the sensitivity of analytical methods to detect low inside concentrations, rather than the nature of particles (biological or non-biological).     

Missense mutations in the ABCB6 transporter cause dominant familialpseudohyperkalemia

Familial Pseudohyperkalemia (FP) is a dominant red cell trait characterized by increased serum [K⁺] in whole blood stored at or below room temperature, without additional hematological abnormalities. Functional gene mapping and sequencing analysis of the candidate genes within the 2q35–q36 critical interval identified—in 20 affected individuals among three multigenerational FP families—two novel heterozygous missense mutations in the ABCB6 gene that cosegregated with disease phenotype. The two genomic substitutions altered two adjacent nucleotides within codon 375 of ABCB6, a porphyrin transporter that, in erythrocyte membranes, bears the Langereis blood group antigen system. The ABCB6 R375Q mutation did not alter the levels of mRNA or protein, or protein localization in mature erythrocytes or erythroid precursor cells, but it is predicted to modestly alter protein structure. ABCB6 mRNA and protein levels increase during in vitro erythroid differentiation of CD34⁺ erythroid precursors and the erythroleukemia cell lines HEL and K562. These data suggest that the two missense mutations in residue 375 of the ABCB6 polypeptide found in affected individuals of families with chromosome 2‐linked FP could contribute to the red cell K⁺ leak characteristic of this condition. Am. J. Hematol. 2013. © 2012 Wiley Periodicals, Inc.     

Accuracy of the chest radiograph to identify bilateral pulmonary infiltrates consistent with the diagnosis of acute respiratory distress syndrome using computed tomography as reference standard

Purpose

The purpose of the study is to evaluate the diagnostic accuracy of the anteroposterior chest radiograph to detect pulmonary abnormalities consistent with acute respiratory distress syndrome (ARDS).

Materials and methods

Ninety patients who met criteria for ARDS regardless of the radiographic one and had near simultaneous chest radiograph and computed tomography (CT) performed were identified. These radiologic studies were reviewed blindly and independently by 2 radiologists for the presence or absence of bilateral pulmonary abnormalities consistent with ARDS using defined radiologic criteria. Disagreements were resolved by consensus. Using the chest CT interpretation as reference standard, the chest radiograph diagnostic parameters were calculated.

Results

Sensitivity (Se) was 0.73; specificity, 0.70; positive and negative predictive values were 0.88 and 0.47, respectively. Female sex was associated with higher Se and lower specificity. When patients were divided according to disease distribution by CT, the Se was significantly lower for focal as compared with diffuse.

Conclusions

The accuracy of the portable chest radiograph to detect pulmonary abnormalities consistent with ARDS is significantly limited. These findings suggest that the use of the chest radiograph results mainly in underrecognition of the syndrome, particularly when disease is not diffusely distributed, but also in overdiagnosis.