Quantification of aryl hydrocarbon hydroxylase and 7-ethoxycoumarin O-deethylase activity in human placentae: development of a protocol suitable for studying effects of environmental exposures on human metabolism.

Several issues regarding measurement of placental AHH and 7ECD activity were studied, and standardized procedures that appeared more suitable than previous assay procedures for measurement of MFO induction in epidemiological studies were adopted. In the AHH assay, deletion of the rat-liver supernatant eliminated a possible extraneous contribution to measurement of low levels of AHH activity and did not substantially affect measurement of higher levels of activity. Increasing the protein concentration of placentae homogenate from 2 to 6 mg, and the length of the incubation time from 20 to 60 min, allowed for accumulation of more BaP products, potentially maximizing the detection of low levels of AHH activity. Use of tissue homogenates made the procedure more convenient and did not appear to interfere with interindividual comparisons of activity. Assay of homogenates of fresh and frozen tissue from the same placenta gave similar results, so that frozen tissue was adopted for convenience and replicability. Although a potential problem for specimens with high AHH activity, degradation of product(s) was modest in AHH assays of human placenta. The efficiency of extraction of fluorescent products declined with increasing protein concentrations in the reaction mixture of AHH assays, but it was stable for a range of product concentrations, and could be controlled by the use of a constant amount of protein per assay. Recovery of product for the 7ECD assay was more complete and was not affected by protein concentration. Additionally, the 7ECD activity was easily detected in every placenta, regardless of smoking exposure. However, in this study the AHH assay appeared to be better at discriminating between non-smokers and smokers. These observations, and the potential differences in the spectrum of agents causing induction of mixed-function oxidases, suggest that both assays are potentially useful measures of human MFO induction in clinical or epidemiological studies.

Prospective analysis of endoscopic vein harvesting.

BACKGROUND: Utilization of bridging vein harvesting (BVH) of saphenous vein grafts (SVG) for coronary artery bypass grafting (CABG) results in large wounds with great potential for pain and infection. Endoscopic vein harvesting (EVH) may significantly reduce the morbidity associated with SVG harvesting. METHODS: A prospective database of 200 matched patients receiving EVH and BVH was compared. The patients all underwent CABG done over a period of 4 months (April to August 2000). Patients were excluded if they had prior vein harvesting. RESULTS: The EVH and BVH group included 100 patients each with similar demographics. The patients in the EVH group had significantly fewer wound complications, mean days to ambulation, and total length of stay (P <0.05). There was no difference in harvest time or vein injuries. CONCLUSION: Endoscopic vein harvesting results in significantly fewer wound complications, decrease in days to ambulation, and the total length of stay. EVH is superior to BVH in patients undergoing CABG.

Dose requirements, assay procedures and tissue specificity for PCB inductation of P-450 dependent mono-oxygenase activity in the rat: implications for design of studies measuring in vivo induction of human placental mono-oxygenases.

Pregnant Sprague-Dawley and Fisher 344 rats were treated on day 15 of gestation with Aroclor 1254 in a single dose ranging from 0 to 500 mg kg-1 body weight and killed on day 18 of gestation. In the small groups of animals used for this study, no effect was observed on mean maternal liver or placental weight, or the number of fetal resorptions at any of the doses tested. Measurement of aryl hydrocarbon hydroxylase (AHH) and 7-ethoxycoumarin O-deethylase (7ECD) activity in tissue homogenates, however, showed that administration of Aroclor 1254 (15 mg kg-1 body weight or greater) induced mono-oxygenase activity in fetal liver. Both the AHH and 7ECD assay detected effects of PCBs with similar sensitivity, and the findings were comparable when homogenates were assayed instead of microsomes. These data were used to suggest technical approaches to the detection of mono-oxygenase induction in placental tissue human populations exposed to PCBs.