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41.
Kinetics of Drug-Induced Changes in Dopamine and Serotonin Metabolite Concentrations in the CSF of the Rat 总被引:5,自引:4,他引:1
Cerebrospinal fluid (CSF) was removed at a constant flow rate of 1 microliter/min from the third ventricle of anesthetized rats. Every 15 min, CSF dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), and 5-hydroxyindoleacetic acid (5-HIAA) concentrations were determined by direct injection of CSF into a liquid chromatographic system coupled with electrochemical detection. Mean CSF concentrations of DOPAC, HVA, and 5-HIAA were 1.29 microM, 0.88 microM, and 2.00 microM, respectively. In order to determine the turnover rates of dopamine (DA) and serotonin, experiments using monoamine oxidase (MAO) inhibition were performed. Tranylcypromine (20 mg/kg i.p.) induced a sharp exponential decrease of CSF DOPAC, HVA, and 5-HIAA, with respective half-lives of 15.60 min, 16.91 min, and 77.23 min. Their respective turnover rates were 3.74, 2.22, and 1.18 nmol X ml-1 X h-1. m-Hydroxybenzylhydrazine (NSD-1015, 100 mg/kg i.p.) and monofluoromethyl-DOPA (100 mg/kg i.p.), two decarboxylase inhibitors, induced a slow exponential decrease of all three CSF metabolites. alpha-Methyl-p-tyrosine (250 mg/kg i.p.) also induced a slow exponential decrease of DOPAC and HVA. These decreases of CSF DOPAC and HVA induced by DA synthesis inhibitors may reflect the turnover of DA in vivo. Haloperidol (0.5 mg/kg i.p.) considerably enhanced CSF DOPAC and HVA without affecting 5-HIAA, confirming that dopaminergic receptors modulate DA neurotransmission in vivo. Haloperidol administered 1.5 h after NSD-1015 did not increase DOPAC and HVA, in contrast to reserpine (5 mg/kg i.p.) injected under the same conditions.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
42.
Microbial metabolism of chlorosalicylates: effect of prolonged subcultivation on constructed strains
Miguel Angel Rubio Karl-Heinrich Engesser Hans-Joachim Knackmuss 《Archives of microbiology》1986,145(2):123-125
The hybrid strain Pseudomonas sp. WR4016 was subcultivated with increasing concentrations of 5-chlorosalicylate (510 mM) as sole carbon source over a period of 9 months. At intervals of approximately 3 months derivative strains WR4017, WR4018 and WR4019 were isolated which exhibited higher growth rates and increased substrate tolerance. Comparative analysis of the turnover rates of the key enzymes in chlorosalicylate degradation showed that the adaptation process did not result from structural modifications of these proteins. Instead, balanced over-production of the salicylate hydroxylase and catechol 1,2-dioxygenase prevented the accumulation of toxic chlorocatechols and accounted for the reduction of the doubling times with 4- or 5-chlorosalicylate. A comparative analysis of a genetically engineered chlorosalicylate degrader PL300-1 showed similar regulatory patterns as the most advanced isolate WR4019 from the adaptation series. 相似文献
43.
In the use of age structured population models for agricultural applications such as the modeling of crop-pest interactions it is often essential that the model take into account the distribution in maturation rates present in some or all of the populations. The traditional method for incorporating distributed maturation rates into crop and pest models has been the so-called distributed delay method. In this paper we review the application of the distributed delay formalism to the McKendrick equation of an age structured population. We discuss the mathematical properties of the system of ordinary differential equations arising out of the distributed delay formalism. We then discuss an alternative method involving modification of the Leslie matrix. 相似文献
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45.
Survival of the parasitic protozoan, Babesia bigemina, in blood cooled at widely different rates to ? 196°C. International Journal for Parasitology4: 169–172. The infectivity of Babesia bigemina in blood containing 2 m DMSO was tested in 99 cattle after the blood had been cooled to ? 196°C at eight rates ranging from 0·73–3070°C/min. Blood cooled at each rate was infective; 95 of the recipients became infected, the exceptions being four of the seven cattle inoculated with blood cooled at 3070° C/min. The infectivity of blood cooled at 39, 82 and 212°C/min was higher than that of blood cooled at slower or faster rates. Least depression of infectivity occurred at 82°C/min. 相似文献
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47.
Normal and mutant human adenosine deaminase genes 总被引:2,自引:0,他引:2
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49.
Summary A few years ago we presented a stationary Markov model of gene evolution according to which only homologous genes from not
too divergent species obeying the condition of being stationary may behave as reliable molecular clocks. A compartmentalized
model of the nuclear genome in which the genes are distributed in compartments, the isochores, defined by their G+C content
has been proposed recently. We have found that only homologous gene pairs that are stationary, and belong to the same isochore,
can be used consistently for the determination of phylogeny and base substitution rate. In particular, for the rodent-human
couple, only about half of the homologous gene pairs are stationary. Stationary genes evolve at the third silent codon position
with the same velocity independent of the genes and base composition. By contrast, nonstationary genes display apparent rate
values (pseudovelocities) that are significantly higher. Our results cast doubt upon recent claims of a large acceleration
in the rate of molecular evolution in rodents. 相似文献
50.
Predicting variability in catch-per-effort in Atlantic cod, Gadus morhua, trap and gillnet fisheries
The relationships between catch rates and fish abundance, hydrographic conditions and fishing effort, for Atlantic cod caught by trapnets (fixed gear) and gillnets (non-fixed gear) in the northern Gulf of St Lawrence have been quantified. Daily changes in trap catch rates were accounted for by changes in salinity, currents and mean local cod densities in 1985 ( R 2 = 0.78), and predicted 1986 trap catch rate changes (by 1985 model) were correlated significantly with those observed ( r = 0.60, P < 0.05). In contrast, the daily changes in 1985 gillnet catch rates were determined by currents, maximum (not mean) local cod densities, and fishing effort (negative) ( R 2 = 0.68), while predicted 1986 gillnet catch rates (by 1985 model) were significantly correlated with those observed ( r = 0.35, P < 0.05). Seasonal catchability coefficients of the traps were similar in 1985 and 1986, but for gillnets this index was an order of magnitude higher in 1986 than in 1985. 相似文献