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951.
Atomic structure of a fragment of human CD4 containing two immunoglobulin-like domains. 总被引:72,自引:0,他引:72
J H Wang Y W Yan T P Garrett J H Liu D W Rodgers R L Garlick G E Tarr Y Husain E L Reinherz S C Harrison 《Nature》1990,348(6300):411-418
The structure of an N-terminal fragment of CD4 has been determined to 2.4 A resolution. It has two tightly abutting domains connected by a continuous beta strand. Both have the immunoglobulin fold, but domain 2 has a truncated beta barrel and a non-standard disulphide bond. The binding sites for monoclonal antibodies, class II major histocompatibility complex molecules, and human immunodeficiency virus gp120 can be mapped on the molecular surface. 相似文献
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Summary Male Fischer F-344 rats were given ethanol in the drinking water and/or by single oral administration. Following this, the animals received p.o. 100 ng/kg of the hepatocarcinogen [3H]aflatoxin B1 (AFB1). 24 h later, the level of DNA-bound AFB1 was determined in the liver and was found not to be affected by any type of ethanol pretreatment. A cocarcinogenic effect of ethanol in the liver is therefore unlikely to be due to an effect on the metabolic activation and inactivation processes governing the formation of DNA-binding AFB1 metabolites.To whom correspondence should be addressed.Acknowledgment. We thank the European Science Foundation for the Toxicology Research Fellowship awarded to M.M. 相似文献
954.
Organophosphate-mediated inhibition of choline acetyltransferase activity in rat brain tissue 总被引:1,自引:0,他引:1
Administration of the organophosphate compound soman in rats resulted in an inhibition of choline acetyltransferase activity in almost all brain regions examined. Enzyme activity was inhibited by 20-50% in various brain regions 30 min after soman injection (94-120 micrograms/kg). Enzyme activity in two regions decreased with time to a near zero level by 3 h after injection. 相似文献
955.
W. J. Richardson 《Cellular and molecular life sciences : CMLS》1990,46(4):416-425
Summary Migratory flights are strongly affected by wind, and birds have developed many adaptations to cope with wind effects. By day, overland migrants at high altitudes may often allow crosswinds to drift their tracks laterally from the preferred heading. In contrast, many birds at low altitude adjust their headings to compensate for drift, and may overcompensate to allow for previous drift. The relative motion of landscape features is probably used to sense drift, at least by day. By night, some overland migrants compensate fully for drift but others do not; no pattern is obvious. Over the sea, compensation is rarely if ever total; wave patterns may allow partial compensation. Other adaptations can include reduction of drift by flying at times and/or altitudes without strong crosswinds. Some birds recognize the need to change course to allow for previous wind displacement, and reorient at least roughly toward the original route or destination. Some juveniles en route to previously-unvisited wintering grounds seem to have this ability, but corroboration is needed. Such reorientation may not require a true navigation ability. However, some birds have unexplained abilities to sense the wind while aloft. 相似文献
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