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251.
Ecdysone 20-hydroxylase activity has been detected in pupal wing discs of Pieris brassicae. This activity is due to an enzyme system located in microsomal fractions. Its apparent Km is 58 nM for ecdysone. The enzyme is inhibited by the reaction product 20-hydroxyecdysone with an apparent Ki of 2.6 μM. Its activity varied during pupal-adult development with a maximum on day 4, when ecdysone levels are the highest in the animal. Although low, the peak activity is sufficient to assure 25% of the conversion of endogenous ecdysone into 20-hydroxyecdysone in pupae. Ecdysone and 20-hydroxyecdysone levels were measured in hemolymph and whole animals; ecdysone appears to be mainly located in hemolymph, whereas 20-hydroxyecdysone seems to be equally distributed between hemolymph and tissues. All these findings are discussed in relation to the roles of ecdysone and 20-hydroxyecdysone during pupal-adult development. 相似文献
252.
253.
Paluck Robert J. Lieff Jonathan D. Esser Aristide H. 《Primates; journal of primatology》1970,11(2):185-194
Three young gibbons, who had minimal previous social contact with each other, were released together in a semi-natural environment. The individual and social behavior of the gibbons paralleled that of gibbons in the wild: of the total daytime, 71% was spent in foraging activities, 20% in social interaction, and 9% in inactivity.The tendency toward group formation proved strong in these gibbons; they were together an average of 68% of the time following their release. Group maintenance seemed based on a sharing of the dominance role for various activities, either equally among the three or in the form of a pair (the male and one of the females) being co-dominant. The male and small female became gradually isolated from the large female. Reciprocal initiation of sexual exploration and play were related to this pairing.The results of discrete activity observations by the simple method of simultaneously recording geographical location and activity of each gibbon, plus the continuous observation of social behavior, were remarkably consistent with gibbon observational data in an artificial setting and those obtained in long-term field investigations. In addition, the methodology permitted an analysis of some of the finer aspects of social behavior. 相似文献
254.
Alberto Bargiotti Giuseppe Cassinelli Sergio Penco Aristide Vigevani Federico Arcamone 《Carbohydrate research》1982,100(1)
Addition of methylmagnesium iodide to methyl 2,3,6-trideoxy-3-trifluoro-acetamido-α-l-threo-hexopyranosid-4-ulose (3) gave methyl 2,3,6-trideoxy-4-C-methyl-3-trifluoroacetamido-α-l-lyxo-hexopyranoside (4) and its l-arabino analogue, depending upon the reaction temperature and the solvent. The corresponding 4-O-methyl derivatives were obtained by treatment of 4 and 5 with diazomethane in the presence of boron trifluoride etherate. Treatment of 4 with thionyl chloride, followed by an alkaline work-up, gave methyl, 2,3,4,6-tetradeoxy-4-C-methylene-3-trifluoro-acetamido-α-l-threo-hexopyranoside (8), which was stereoselectively reduced to methyl 2,3,4,6-tetradeoxy-4-C-methyl-3-trifluoroacetamido-α-l-arabino-hexopyranoside. Epoxidation of 8 with 3-chloroperoxybenzoic acid gave the corresponding 4,41-anhydro-4-C-hydroxymethyl-l-lyxo derivative (10), which was also prepared by treatment of 3 with diazomethane. Azidolysis of 10, followed by catalytic hydrogenation and N-trifluoroacetylation, gave methyl 2,3,6-trideoxy-3-trifuloroacetamido-4-C-trifluoroacetamidomethyl-α-l-lyxo-hexopyranoside. 相似文献
255.
256.
OBJECTIVE--To assess the potentially increased risk of death or near death from asthma in asthmatic patients with psychosis. DESIGN--Case-control study. SETTING--The computerised health databases of the Canadian province of Saskatchewan. SUBJECTS--131 cases of death or near death from asthma identified within a cohort of asthmatic patients; 3930 matched non-cases. EXPOSURE AND OUTCOME MEASURES--The exposure of interest was the use of major tranquillisers in the period before an outcome event. Outcomes included death or near death from asthma. RESULTS--Crude analyses showed that asthmatic patients who had used major tranquillisers in the previous 12 months were at a 3.2 (95% confidence interval 1.4 to 7.5) times greater risk of death or near death from asthma than asthmatic patients who did not use major tranquillisers. Past users of major tranquillisers who had recently discontinued use were at a particularly high risk (relative risk 6.6; 2.5 to 17.6). Adjustment for use of antiasthma drugs and other confounders abolished this excess risk. CONCLUSIONS--Asthmatic patients who use major tranquillisers seem to be at an increased risk of death or near death from asthma. Physicians treating asthmatic patients with a history of use of major tranquillisers should exercise greater caution with regard to management of such patients. 相似文献
257.
258.
Gs and Gi protein subunits during cell differentiation in intestinal crypt-villus axis: regulation at the mRNA level 总被引:1,自引:0,他引:1
259.
Lamoureux M Fliss L Blais BW Messier S Holley RA Simard RE 《Journal of applied microbiology》1997,82(2):259-266
A microtitre plate nucleic acid probe hybridization system was developed for the detection of ribosomal RNA from thermophilic Campylobacter (Camp. jejuni, Camp. coli, Camp. lari and Camp. upsaliensis). A specific DNA probe obtained by amplification of 23S rRNA sequences using the polymerase chain reaction technique was immobilized on a microtitre plate, and used for hybridization with target 23S rRNA from cell lysates. The RNA-DNA hybrids thus formed in the wells were detected by an immunoenzymatic assay using a monoclonal antiRNA-DNA hybrid antibody. The sensitivity of this system was 2.7 x 10(4) cells ml(-1). This simple, sensitive and inexpensive hybridization and immunoenzymatic assay system should facilitate the detection of Campylobacter in food and clinical samples. 相似文献
260.