Dry deposition of 88Rb and 138Cs from a boiling water reactor plume.

Double tracer experiments were made in May 1981 at the Ringhals nuclear power plant in Sweden to investigate atmospheric-dispersion and dose models. Sulphurhexafluoride (SF6) and radioactive noble gases were released simultaneously from a 110-m stack and detected downwind at distances of 3-4 km. The experiments were made under near-neutral conditions. One-hour measurements at ground level yielded cross-wind profiles of SF6 concentrations and gamma radiation from the plume. In-situ gamma spectrometric measurements demonstrated a significant surplus of gamma rays from the noble gas daughters (88Rb and 138Cs) compared with those from the noble gases. This surplus was interpreted as due to dry deposition from the plume, and deposition velocities were estimated at 0.02-0.10 m s-1. These values are very high when compared with values recommended for calculating consequences of nuclear accidents. The high values are believed to be due to the very small size of the daughter particles.

Digital gene expression profiling of primary acute lymphoblastic leukemia cells.

We determined the genome-wide digital gene expression (DGE) profiles of primary acute lymphoblastic leukemia (ALL) cells from 21 patients taking advantage of 'second-generation' sequencing technology. Patients included in this study represent four cytogenetically distinct subtypes of B-cell precursor (BCP) ALL and T-cell lineage ALL (T-ALL). The robustness of DGE combined with supervised classification by nearest shrunken centroids (NSC) was validated experimentally and by comparison with published expression data for large sets of ALL samples. Genes that were differentially expressed between BCP ALL subtypes were enriched to distinct signaling pathways with dic(9;20) enriched to TP53 signaling, t(9;22) to interferon signaling, as well as high hyperdiploidy and t(12;21) to apoptosis signaling. We also observed antisense tags expressed from the non-coding strand of ~50% of annotated genes, many of which were expressed in a subtype-specific pattern. Antisense tags from 17 gene regions unambiguously discriminated between the BCP ALL and T-ALL subtypes, and antisense tags from 76 gene regions discriminated between the 4 BCP subtypes. We observed a significant overlap of gene regions with alternative polyadenylation and antisense transcription (P<1 × 10(-15)). Our study using DGE profiling provided new insights into the RNA expression patterns in ALL cells.

Are contact allergens stable in patch test preparations? Investigation of the degradation of d-limonene hydroperoxides in petrolatum.

Several of the products formed after oxidation of d-limonene exhibit strong contact allergenic properties. Some, e.g., the hydroperoxides, are unstable compounds. In this study, we have examined whether the limonene hydroperoxides are chemically stable in white petrolatum used for patch testing. We found that the stability of the hydroperoxides was strongly dependent on whether or not the petrolatum was stabilized with alpha-tocopheryl acetate. In the presence of this antioxidant, the hydroperoxides were degraded to a greater extent. The hydroperoxides were shown to be directly reduced to the corresponding alcohols by this agent. On the other hand, the compounds where shown to be stable in non-stabilized petrolatum throughout clinical patch testing for a period of 6 weeks, provided that the preparations were stored in a refrigerator when not used. Thus, it is recommended that vehicles without alpha-tocopheryl acetate are used when peroxy or hydroperoxy compounds are patch tested or used in sensitization experiments. However, it is important to limit the storage time so that optimal conditions are at hand. A fast method was developed to enable isolation and quantification of the hydroperoxides in white petrolatum. This analytical method may also be applicable to other compositions of patch test preparations.

The dual origin of the yeast mitochondrial proteome.

We propose a scheme for the origin of mitochondria based on phylogenetic reconstructions with more than 400 yeast nuclear genes that encode mitochondrial proteins. Half of the yeast mitochondrial proteins have no discernable bacterial homologues, while one-tenth are unequivocally of alpha-proteobacterial origin. These data suggest that the majority of genes encoding yeast mitochondrial proteins are descendants of two different genomic lineages that have evolved in different modes. First, the ancestral free-living alpha-proteobacterium evolved into an endosymbiont of an anaerobic host. Most of the ancestral bacterial genes were lost, but a small fraction of genes supporting bioenergetic and translational processes were retained and eventually transferred to what became the host nuclear genome. In a second, parallel mode, a larger number of novel mitochondrial genes were recruited from the nuclear genome to complement the remaining genes from the bacterial ancestor. These eukaryotic genes, which are primarily involved in transport and regulatory functions, transformed the endosymbiont into an ATP-exporting organelle.