Simplified methods for monitoring petroleum‐contaminated ground water and soil vapor

Portable meters and simplified gas Chromatographic (GC) techniques were investigated for monitoring volatile hydrocarbon (HC), CO₂, and O₂, concentrations in groundwater, exhaust gases, and soil vapor during in situ remediation using soil vapor extraction (SVE) and air sparging (AS). Results of groundwater samples analyzed in‐house using a headspace technique compared well to split samples analyzed by a certified analytical laboratory (r² = 0.94). SVE exhaust gas HC and CO₂ concentrations measured using a GT201 portable HC/O₂ meter and a RA‐411A meter (GasTech), respectively, were highly correlated with in‐house laboratory GC analyses (r² = 0.91). O₂ concentrations fell in a small range and meter analyses were not well correlated with laboratory analyses. Results of soil gas monitoring were not as well correlated as those for exhaust gases for HC, CO₂, or O₂, perhaps due to environmental conditions such as changes in relative humidity or the wider range of soil gas values. Overall, the meters were good indicators of vapor contamination, they greatly simplified estimates of total HC mass removal, and they allowed estimates of the biological contribution to contaminant removal during the remediation process.     

Changes in radiocaesium uptake and distribution in wheat during plant development: a solution culture study

Spring wheat plants were grown in a ¹³⁷Cs labelled nutrient solution, either in the presence or absence of NH₄ as a secondary N source. Between 11 and 64 days after sowing (DAS), plants were harvested on nine occasions. The plants supplied with NH₄ and NO₃ had lower root ¹³⁷Cs Activity Concentrations (AC) than those supplied with NO₃ only. Shoot AC were equal in both nutrition treatments. Shoot and root ¹³⁷Cs AC (dry weight basis) showed the same trends with plant age in both nutrition treatments. Shoot AC almost doubled between 11 and 28 DAS after which they gradually decreased concomitant with a similar decrease in K concentrations. Root AC were always higher than shoot AC and increased to a maximum at 35 DAS after which they fluctuated. Expressed on a tissue water basis, the ¹³⁷Cs AC varied less during plant age than did dry weight based AC. Furthermore, root and shoot AC expressed on a tissue water basis were almost equal. It is shown that the initial increase in ¹³⁷Cs AC in both root and shoot can largely be explained by the initial dilution of absorbed ¹³⁷Cs in the unlabelled seedling tissues. No correlation was found between K and ¹³⁷Cs distribution among ears, leaves, stems and roots in 64 old wheat plants. NH₄ as a secondary N source in a nitrate nutrient solution marginally affected ¹³⁷Cs distribution.Abbreviations AC activity concentrations - DAS days after sowing FAX no corresponding author: +3216321997     

Overlapping substrate specificities of benzaldehyde dehydrogenase (the xylC gene product) and 2-hydroxymuconic semialdehyde dehydrogenase (the xylG gene product) encoded by TOL plasmid pWW0 of Pseudomonas putida.

Two aldehyde dehydrogenases involved in the degradation of toluene and xylenes, namely, benzaldehyde dehydrogenase and 2-hydroxymuconic semialdehyde dehydrogenase, are encoded by the xylC and xylG genes, respectively, on TOL plasmid pWW0 of Pseudomonas putida. The nucleotide sequence of xylC was determined in this study. A protein exhibiting benzaldehyde dehydrogenase activity had been purified from cells of P. putida (pWW0) (J. P. Shaw and S. Harayama, Eur. J. Biochem. 191:705-714, 1990); however, the amino-terminal sequence of this protein does not correspond to that predicted from the xylC sequence but does correspond to that predicted from the xylG sequence. The protein purified in the earlier work was therefore 2-hydroxymuconic semialdehyde dehydrogenase (the xylG gene product). This conclusion was confirmed by the fact that this protein oxidized 2-hydroxymuconic semialdehyde (kcat/Km = 1.6 x 10(6) s-1 M-1) more efficiently than benzaldehyde (kcat/Km = 3.2 x 10(4) s-1 M-1). The xylC product, the genuine benzaldehyde dehydrogenase, was purified from extracts of P. putida (pWW0-161 delta rylG) which does not synthesize 2-hydroxymuconic semialdehyde dehydrogenase. The amino-terminal sequence of the purified protein corresponds to the amino-terminal sequence deduced from the xylC sequence. This enzyme efficiently oxidized benzaldehyde (kcat/Km = 1.7 x 10(7) s-1 M-1) and its analogs but did not oxidize 2-hydroxymuconic semialdehyde or its analogs.     

Health service accreditation: report of a pilot programme for community hospitals.

Voluntary accreditation in the United Kingdom is being used by health care providers to improve and market their services and by commissioners to define and monitor service contracts. In a three year pilot scheme in the south west of England, 43 out of 57 eligible community hospitals volunteered to be surveyed; 37 of them were ultimately accredited for up to two years by the hospital accreditation programme. The main causes for non-accreditation related to safety, clinical records, and medical organisation. Follow up visits in 10 hospitals showed that, overall, 69% of recommendations were implemented. An independent survey of participating hospitals showed the perceived benefits to include team building, review of operational policies, improvement of data systems, and the generation of local prestige. Purchasers are increasingly influenced by accreditation status but are mostly unwilling to finance the process directly. None the less, the concept may become an important factor moderating the quality of service in the new NHS.     

High-density lipoprotein binding to bovine adrenal cortex membranes

Binding studies were performed with bovine adrenal cortex membranes, human 125I-labelled high-density lipoprotein (HDL) and modified photoactivable derivatives of 125I-labelled HDL, namely 125I-labelled HDL-amidinophenylazide and 125I-labelled HDL-amidopropionyldithiophenylazide. The purity of the apolipoprotein composition of the 125I-labelled HDL and photoactivable 125I-labelled HDL used in the binding studies was determined by Coomassie blue and silver staining, and by measuring 125I-labelled cpm after SDS-polyacrylamide gel electrophoresis. About 45% of the 125I-labelled HDL binding to the membranes occurred in the presence of excess EDTA and only unlabelled HDL competed for the binding site. The 125I-labelled interaction with this binding site on the membranes did not require calcium. In addition, 40% of the 125I-labelled HDL binding was to an EDTA-sensitive site, and unlabelled HDL and low-density lipoprotein (LDL) competed for the binding site. Consequently, adrenal cortex membranes have binding sites which show cross reactivity for both HDL and LDL. Modification of 58% of the apolipoprotein lysine residues of 125I-labelled HDL with methylazidophenylimidate, a reagent which maintains the positive charge at lysine residues, had little affect on binding to EDTA-sensitive and insensitive sites. In contrast, modification of 35% of apolipoprotein lysine residues of 125I-labelled HDL with N-succinimidyl(4-azidophenyldithio)propionate, a reagent which converts charged amino lysines to amide bonds, showed binding properties which were almost totally inhibited by EDTA.     

Diffusible factors are responsible for differences in nuclease sensitivity among chromatins originating from different cell types

We have examined the kinetics of nuclease digestion of chromatin from committed and uncommitted cells in experiments where the nuclei are mixed and co-digested. Cultures of the sea urchin, Arbacia punctulata, were grown to the 16-cell stage in either [3H]thymidine or [14C]thymidine and the macromere, mesomere, and micromere cell types separated. After isolation, sets of nuclei with two different blastomere types (each having different radionucleotide tagging) were mixed and co-digested with micrococcal nuclease or DNase. I. The extent of digestion was monitored by solubility in 5% perchloric acid (PCA). We find no significant differences in initial digestion rates or limit digests among the different cell types when co-digested with either nuclease. Differences in nuclease sensitivity observed when nuclei are digested separately are abolished when nuclei are probed in a mixing experiment. The results support the hypothesis that phenotypic differences in digestibility among different cell types in vitro reflect differences in chromatin-condensing factors which can diffuse between nuclei.