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NA Lisitsyn MV Rosenberg GA Launer LL Wagner VK Potapov TB Kolesnik ED Sverdlov 《Canadian Metallurgical Quarterly》1993,(3):26-29
We describe a novel technique for isolation of sequences that are present in one genome (tracer), but absent in another (driver). Tracer DNA, cleaved with Sau 3A and capped with a single stranded PCR adapter, is allowed to hybridize with an excess of sheared biotinylated driver; biotinylated DNA and its hybrids with the tracer are removed by phenol/chloroform extraction after incubation with streptavidin. After several rounds of subtraction the ends of self-annealed tracer molecules from the nonextractable fraction are filled-in with Tag polymerase and amplified, using the single stranded PCR adapter as a primer. The method has been applied to purification of fragments from a 2.9 kb plasmid added to E. coli DNA at equimolar quantity. Plasmid derived fragments (250-1000 bp), initially comprising 1/1400th part of tracer DNA, were purified to homogeneity after two rounds of subtraction followed by PCR. 相似文献
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MA Alpert BE Terry M Mulekar MV Cohen CV Massey TM Fan H Panayiotou V Mukerji 《Canadian Metallurgical Quarterly》1997,80(6):736-740
BACKGROUND: Prevention of hypothermia during abdominal surgery by insulating or heat-transferring methods has been the subject of numerous investigations. This study approaches the problem from a less discussed point of view, i.e. the effect of different surgical techniques on body temperature changes. METHODS: Body temperature was measured at 3 core and 6 skin points in 40 patients scheduled for cholecystectomy through open laparotomy or laparoscopy with pneumoperitoneum created and maintained with unwarmed carbon dioxide (CO2) insufflation. End-tidal CO2 was kept constant by adjustments of respiratory frequency. Anaesthesia, intravenous infusions, and draping of the patients were standardized. RESULTS: During the first 1 h of anaesthesia core temperatures decreased approximately by 0.7 degrees C and distal skin temperatures increased by 7 degrees C in both groups. At the end of surgery heat balance was similar in both groups. An increase of 2.5 1.min-1 in respiratory minute volume was needed to control end-tidal CO2 levels in the laparoscopy group during pneumoperitoneum which was maintained with a CO2 flow of 1.2 1.min-1 through the abdominal cavity. CONCLUSION: Laparoscopic technique with unwarmed carbon dioxide insufflation does not offer any advantage in terms of body temperature changes when compared to open surgery. 相似文献