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1.
C F Nassar E W Khairallah M G Nasser Z M Habbal 《Comparative biochemistry and physiology. A, Comparative physiology》1988,89(2):197-201
1. The effect of colchicine, cytochalasin-B and procaine on calcium transport across the rat small intestine was investigated. The results obtained show the following: 2. Colchicine and cytochalasin-B at different concentrations inhibited significantly (P less than 0.001) calcium accumulation in rat intestinal cells, whereas procaine at different concentrations increased significantly (P less than 0.001) calcium accumulation in the rat small intestine. 3. Unidirectional influx of calcium across the rat small intestine was significantly inhibited (P less than 0.01) in the presence of colchicine and cytochalasin-B in the preincubation medium. Procaine, on the other hand, caused a significant increase (P less than 0.01) in the unidirectional influx of calcium across the rat intestinal cells. 4. The cell water content was not altered in the presence of the different drugs indicating that the changes in calcium transport across the rat intestinal cells are not due to alterations in the structure of the cell membrane. 相似文献
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An amplified enzyme-linked immunosorbent assay (A-ELISA) for detecting and quantifying hepatitis A virus in estuarine water samples is described. The test was five times more sensitive than a standard ELISA and at least two times more sensitive than radioimmunoassay. Test sensitivity was unaffected by the procedures used to concentrate the virus in estuarine samples or by the presence of humic and tannic acids in test samples. Nonspecific reactions were not encountered with a number of enteroviruses or with a rotavirus. A high sensitivity and specificity combined with speed, low cost, and freedom from radiolabels made the A-ELISA useful for detecting hepatitis A virus in environmental samples. The virus was detected in 3 of 20 estuarine water samples examined by A-ELISA. 相似文献
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Regulated enzymes of aromatic amino acid synthesis: control, isozymic nature, and aggregation in Bacillus subtilis and Bacillus licheniformis 总被引:3,自引:0,他引:3
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Several regulated enzymes involved in aromatic amino acid synthesis were studied in Bacillus subtilis and B. licheniformis with reference to organization and control mechanisms. B. subtilis has been previously shown (23) to have a single 3-deoxy-d-arabinoheptulosonate 7-phosphate (DAHP) synthetase but to have two isozymic forms of both chorismate mutase and shikimate kinase. Extracts of B. licheniformis chromatographed on diethylaminoethyl (DEAE) cellulose indicated a single DAHP synthetase and two isozymic forms of chorismate mutase, but only a single shikimate kinase activity. The evidence for isozymes has been supported by the inability to find strains mutant in these activities, although strains mutant for the other activities were readily obtained. DAHP synthetase, one of the isozymes of chorismate mutase, and one of the isozymes of shikimate kinase were found in a single complex in B. subtilis. No such complex could be detected in B. licheniformis. DAHP synthetase and shikimate kinase from B. subtilis were feedback-inhibited by chorismate and prephenate. DAHP synthetase from B. licheniformis was also feedback-inhibited by these two intermediates, but shikimate kinase was inhibited only by chorismate. When the cells were grown in limiting tyrosine, the DAHP synthetase, chorismate mutase, and shikimate kinase activities of B. subtilis were derepressed in parallel, but only DAHP synthetase and chorismate mutase were derepressible in B. licheniformis. Implications of the differences as well as the similarities between the control and the pattern of enzyme aggregation in the two related species of bacilli were discussed. 相似文献
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Thirty-two genera of microorganisms were identified with one of six distinctive control patterns for the enzyme 3-deoxy-d-arabino-heptulosonate-7-phosphate synthetase. These patterns included sequential feedback inhibition, isoenzyme feedback inhibition, cumulative feedback inhibition, and three (apparent) simple one-effector patterns. Documentation is provided of an overwhelming tendency for control patterns to be strongly conserved among the member species of the various genera that were examined. 相似文献
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Experiments were designed to test the hypotheses that ovarian follicular response to superstimulatory treatment initiated during Wave 1 is equivalent to that of Wave 2, and recovery rate and quality of ova embryos derived from follicles of Wave 1 are equivalent to those derived from follicles of Wave 2. In a preliminary experiment (Experiment 1), heifers were given Folltropin-V (20 mg NIH-FSH-P1, im, bid for 5 d) beginning the day after emergence of the first (n=10) or second (n=10) follicular wave of the estrous cycle, equivalent to approximately Day 1 and Day 10, respectively (Day 0=ovulation). Luteolysis was induced with cloprostenol (500 mug im, bid) on the fourth day of treatment. Fewer (P<0.05) ovulations per heifer were induced in the Wave 1 group than in the Wave 2 group (4.6+/-1.0 vs 9.1+/-1.3). However, the interval from wave emergence to initiation of treatment was found, in retrospect, to have been longer (P<0.05) in the Wave 1 group, i.e., treatment was initiated relatively later with respect to wave emergence. Experiment 2 was designed to correct this disparity and to initiate the same treatment protocol on the day of wave emergence rather than the day after (n=21 per Wave group). There was no difference between Wave 1 and Wave 2 groups in the interval from wave emergence to initiation of treatment (0.4+/-0.1 d), the number of ovulations detected by ultrasonography (6.6+/-1.0 vs 8.2+/-1.7), the number of CL detected at slaughter (6.5+/-0.9 vs 8.1+/-1.8), the total number of ova embryos recovered (5.2+/-0.7 vs 5.1+/-0.8), or the number of fertilized embryos collected (2.8+/-0.6 vs 3.0+/-0.6). In addition, there was no difference between groups in the proportion of heifers that ovulated in either experiment; collectively, luteolysis and ovulation was induced in 58 of 60 heifers. The results supported the general hypothesis that follicles and oocytes of the first and second follicular waves are equivalent in the response to superstimulatory treatment. Regardless of which follicular wave, initiation of treatment near the time of wave emergence appears critical for maximal superovulatory response. Because of the consistency in the time of emergence of Wave 1 (day of ovulation) and equivalence in superovulatory response, use of Wave 1 rather than subsequent follicular waves may be more convenient and time-sparing in superovulation programs; the day of estrus (day before ovulation) may be used as a consistent point of reference for the start of treatment. 相似文献
8.
Superovulatory response to a single subcutaneous injection of Folltropin-V in beef cattle 总被引:1,自引:0,他引:1
A series of 4 experiments were designed to evaluate the feasibility of superstimulation in beef cattle with a single sc injection of the porcine pituitary extract, Folltropin-V. In the preliminary study (Experiment 1), superovulatory response of cows (n=7) treated with a single sc injection of 400 mg NIH-FSH-P1 Folltropin-V was not different than that of cows (n=8) superstimulated with twice daily im injections over 4 d, or a single sc injection plus an injection of eCG (n=12). Experiments 2 and 3 were designed to determine the optimal site of a single sc injection. In Experiment 2, cows (n=25) with body condition scores (BCS) of 1 to 2 were used. The mean number of CL counted and ova/embryos collected was lower (P<0.05) in cows treated with the single sc injection in the neck region than in cows treated with a single sc injection behind the shoulder, or with the twice daily im injection treatment. In Experiment 3, cows (n=49) with BCS of 3 to 5 were used. There were no differences in the number of CL, total ova/embrvos collected, fertilized ova and transferable embryos whether treatments were given in the neck region or behind the shoulder, or whether the cows were implanted or not implanted with Syncro-Mate-B. Experiment 4 was designed to determine the optimal superstimulatory dosage of Folltropin-V administered by a single sc injection. Superovulatory response of cows treated with the higher doses (400 mg, 600 mg or 800 mg NIH-FSH-P1) was higher (P<0.05) than those treated with 200 mg NIH-FSH-P1. The number of unovulated (>/=10 mm) follicles at the time of ova/embryo collection was higher (P<0.05) in the 600 and 800 mg groups, and progesterone concentration at estrus was higher (P<0.05) in cows treated with 800 mg than with 400 or 200 mg. It was concluded that a single, bolus sc injection of 400 mg NIH-FSH-P1 of Folltropin-V is as efficacious as the 4-d, twice daily im treatment protocol for inducing superovulation in beef cows. The amount of subcutaneous fat and site of injection appeared to affect the efficacy of a single sc injection; a single bolus sc injection of Folltropin-V behind the shoulder resulted in the most predictable superovulatory response. 相似文献
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Two experiments were designed to evaluate the responsiveness of beef heifers to superstimulatory treatments administered during the first follicular wave. Heifers were examined daily (Experiment 1) or twice daily (Experiment 2) by ultrasonography to determine the status of follicular wave development and the day of initiation of superstimulatory treatment. Heifers in both experiments were superstimulated with a total dose of 10 ml Folltropin (equivalent to 200 mg of NIH-FSH-P1), divided into 10 equal intramuscular injections over 5 days. On the last day of treatment, heifers received 500 mug of cloprostenol after each injection of Folltropin to induce luteolysis. In the respective groups, superstimulatory treatments were initiated on Day -1, Day 0 (day of ovulation) or Day +1 for Experiment 1, and on Day -1, Day 0, Day +1 or Day +2 for Experiment 2. In Experiment 1, the number of ovulations in each ovary was assessed by ultrasonography and by counting the number of corpora lutea (CL) in each ovary at slaughter. The correlation between both techniques for assessing ovulatory response was high (r= 0.98; P< 0.0001), and there was no significant difference in the mean number of ovulations detected by ultrasound (5.7+/-1.1) versus the mean number of CL counted at slaughter (6.2+/-1.2). In Experiment 1, the mean (+/- SEM) number of CL counted at slaughter in heifers treated on Day -1 (9.4+/-3.8) and Day 0 (7.3+/-1.6) was higher (P< 0.05) than that of heifers treated on Day +1 (0.7+/-0.3). The mean number of follicles >/=7 mm in diameter on the last day of treatment was also higher (P<0.05) in the Day -1 group compared with the Day +1 group; the Day 0 group was intermediate. In Experiment 2, the mean number of ovulations was higher (P< 0.05) in the Day 0 group (18.4+/-3.4) than the Day -1 (9.5+/-2.3), Day +1 (6.7+/-2.2) or Day +2 (6.5+/-2.3) groups. Heifers in the Day -1, and Day 0 groups had more (P< 0.05) follicles >/=7 mm at the end of treatment compared with heifers in the Day +1 or the Day +2 group. The stated hypothesis was supported: exogenous FSH treatment initiated at the time of wave emergence, near the expected time of the endogenous wave-eliciting FSH surge, has a positive effect on the superstimulatory response. A higher superstimulatory response was elicited when treatments were initiated on the day of, or the day before, wave emergence compared with that of later treatments. 相似文献