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51.
Effects of the administration of cadmium and zinc on the concentration of zinc in the thymus of rats
Paloma Huerta Paloma Galan Alberto J. Alcala Bartolome Ribas Jose M. Teijon 《Biological trace element research》1988,18(1):95-103
The zinc content of thymus glands of male Wistar rats has been determined during five weeks of treatment with ZnCl2 and CdCl2, and compared with a group of control rats. THymus gland extracts were chromatographed on columns of Sephadex G-75 and the zinc content of the one hundred fractions obtained were determined by atomic absorption spectrophotometry. The rats treated with ZnCl2 showed an increase in the thymus concentration of zinc bound to high and low molecular weight proteins. The rats treated with CdCl2 showed an increase in zinc concentration, as opposed to the control group, during the first three weeks of treatment, and thereafter show a toxic effect of cadmium on the gland, with ulterior regression of the latter, and a decrease in the concentration of zinc. 相似文献
52.
Occurrence of a Large Ca2+ -Independent Release of Glutamate During Anoxia in Isolated Nerve Terminals (Synaptosomes) 总被引:2,自引:0,他引:2
Isolated rat cerebral cortical synaptosomes made anoxic by addition of cyanide developed an inhibition of the Ca2+-dependent release of glutamate 2 min after the addition of the metabolic inhibitor when the intrasynaptosomal ATP/ADP ratio decreased below 1.7. In contrast, cyanide induced a continuous efflux of glutamate through a Ca2+-independent pathway that accounted for the release of 25% of total intrasynaptosomal glutamate in 5 min. The results suggest that a Ca2+-independent release of glutamate could be implicated in the neurotoxic action of this amino acid during anoxia. 相似文献
53.
M. Pilar López M. Jose Gómez-Lechón Jose V. Castell 《In vitro cellular & developmental biology. Plant》1988,24(6):511-517
Summary This study examines the factors involved in the rapid glycolysis and glycogenolysis that occur during the first stages of
hepatocyte culture: a) Shortly after seeding glycolysis, estimated as lactate released to culture medium, increased 10 times
in comparison to that reported in vivo. By 8 to 9 h of culture, hepatocytes were nearly glycogen-depleted even in the presence
of insulin. b) 6-Phosphofructo-2-kinase remained 100% active during this period. The proportion of the initial active phosphorylase
(87%) decreased to 57% by 7 h of culture. c) Fructose 2,6-bisphosphate content was initially similar to that found in liver
of fed animals, decreased after seeding and increased thereafter up to four times the initial concentration. In spite of changes
in the concentration of this activator, the glycolytic rate remained high and constant. d) ADP and AMP increased sharply after
cell plating, reaching values 1.7 and 3.5 times higher. The rise in AMP levels may be involved in the activation of glycolysis
and glycogenolysis, because this metabolite is known to act as an allosteric activator of phosphofrucktokinase and glycogen
phosphorylase. This metabolic situation resembles that of cells under hypoxia.
Part of this work was presented at the 38th Annual Meeting of the Tissue Culture Association, Washington, DC, May 1987. 相似文献
54.
M. Scuteri M. A. Sala de Miguel J. Blanco Viera E. Planes de Banchero 《Mycopathologia》1992,120(3):177-182
Seventeen strains of Penicillium spp. have been isolated from Poa huecu Parodi from the Zapala zone, exhibiting toxicity to sheet. The following strains have been identified: P. crustosum, cyclopium, notatum, palitans, puberulum, verrucosum, viridicatum and Penicillium spp. The toxigenic capacity of the strains was studied after growing them under suitable conditions. Toxins produced were analysed by thin layer chromatography (TLC). Penitrem A (PA) and Penitrem B (PB) neurotoxins were identified and quantitated in twelve strains; verruculogen (VERR) and fumitremorgen B (FTB) being present in one of them. The effect of these mycotoxins was studied in mice. Neurological symptoms characteristic of the intoxication by tremorgenic toxins and similar to those observed in sheep suffering from huecu's disease were observed. The possible role of these toxins as causative agents of huecu's disease is discussed. 相似文献
55.
Francisco J. Acosta Jose M. Serrano Jesus M. Barandica Francisco Lopez 《Journal of Insect Behavior》1992,5(3):337-346
The focal-animal technique assumes the continuous recording of the behavior of an individual during a certain time interval. The length of this interval (sampling unit) can be problematic when estimating the duration of behavioral acts. Two acts from the behavioral repertoire of the ant Leptothorax fuenteiwere focused on in this work at different ranges of temporal scales. Analyzing these acts we show the possibility of existence of a sampling artifact, in such a way that the estimates of the durations of the acts would be forced to depend upon the length of the sampling unit that is being used. 相似文献
56.
M. Rosario Rodicio Miguel A. Alvarez Keith F. Chater 《Molecular & general genetics : MGG》1991,225(1):142-147
Summary IS112
is a transposable element identified in Streptomyces albus G by its frequent mutagenic insertion into the genes for the SalI restriction-modification system. IS112 is present in several copies in the genome of S. albus G. Homologous sequences were detected in other Streptomyces strains. Sequence analysis revealed that IS112 has a length of 883 by with a GC content of 67.4%. The copy that was isolated contained imperfect inverted repeats (16/20 match) at its ends and was flanked by a 2 by duplication at the target site, which was located within the gene (salIR) for the Sall endonuclease. A long open reading frame (ORF) encoding a putative polypeptide of 256-253 amino acids spans almost the entire sequence. Significant homology was detected between this polypeptide and that corresponding to ORFB of IS493, an insertion sequence recently isolated from Streptomyces lividans 66.
相似文献
相似文献
57.
Pere Santamaria Michael T. Boyce-Jacino Alan L. Lindstrom Jose J. Barbosa Anthony J. Faras Stephen S. Rich 《Immunogenetics》1991,33(5-6):374-387
Nucleic acid sequences of the second exons of HLA-DRB1, –DRB3/4/5, –DQB1, and –DQA1 genes were determined from 43 homozygous cell lines, representing each of the known class II haplotypes, and from 30 unrelated Caucasian subjects, comprising 60 haplotypes. This systematic sequence analysis was undertaken in order to a) determine the existence of sequence microheterogeneity among cell lines which type as identical by methods other than sequencing; b) determine whether direct sequencing of class II genes will identify the presence of more extensive sequence polymorphism at the population level than that identified with other typing methods; c) accurately determine the molecular composition of the known class II haplotypes; and d) study their evolutionary relatedness by maximum parsimony analysis. The identification of seven previously unidentified haplotypes carrying five new allelic amino acid sequences suggests that sequence microheterogeneity at the population level may be more frequent than previously thought. Maximum parsimony analysis of these haplotypes allowed their evolutionary classification and indicates that the higher mutation rate at DRB1 compared to DQB1 loci in most haplotypic groups is inversed in specific haplotype lineages. Furthermore, the extent and localization of gene conversions and point mutations at class II loci in the evolution of these haplotypes is significantly different at each locus. Identification of additional HLA class II molecular microheterogeneity suggests that direct sequence analysis of class II HLA genes can uncover new allelic sequences in the population and may represent a useful alternative to current typing methodologies to study the effects of sequence allelism in organ transplantation.The nucleotide sequence data reported in this paper have been submitted to the GenBank nucleotide sequence database and have been assigned the accession numbers M35890 through M35953. 相似文献
58.
59.
Rafael Balaña Fouce Maria I. Escribano Jose M. Alunda 《Molecular and cellular biochemistry》1991,107(2):127-133
Summary The putrescine uptake/efflux regulation and their regulatory role on intracellular polyamine pools have been studied in the parasitic protozoa Leishmania infantum. Putrescine uptake was age-dependent with maximal values in logarithmic phase promastigotes and minimal in stationary phase. Moreover, putrescine uptake was activated in response to depletion of intracellular polyamines by alpha-difluoromethylornithine (DFMO) — a well known irreversible enzyme-activated inhibitor of ornithine decarboxylase. Kinetic studies of putrescine uptake induction showed a notable rise in Vmax without Km changes, suggesting a de novo synthesis of putrescine carriers. Putrescine uptake was able to replenish polyamine content and also to recover the proliferative rate in cells treated during 24 hours with DFMO. 相似文献
60.
The effect of ciprofibrate, a hypolipidemic drug, was examined in the metabolism of palmitic (C16:0) and lignoceric (C24:0) acids in rat liver. Ciprofibrate is a peroxisomal proliferating drug which increases the number of peroxisomes. The palmitoyl-CoA ligase activity in peroxisomes, mitochondria and microsomes from ciprofibrate treated liver was 3.2, 1.9 and 1.5-fold higher respectively and the activity for oxidation of palmitic acid in peroxisomes and mitochondria was 8.5 and 2.3-fold higher respectively. Similarly, ciprofibrate had a higher effect on the metabolism of lignoceric acid. Treatment with ciprofibrate increased lignoceroyl-CoA ligase activity in peroxisomes, mitochondria and microsomes by 5.3, 3.3 and 2.3-fold respectively and that of oxidation of lignoceric acid was increased in peroxisomes and mitochondria by 13.4 and 2.3-fold respectively. The peroxisomal rates of oxidation of palmitic acid (8.5-fold) and lignoceric acid (13.4-fold) were increased to a different degree by ciprofibrate treatment. This differential effect of ciprofibrate suggests that different enzymes may be responsible for the oxidation of fatty acids of different chain length, at least at one or more step(s) of the peroxisomal fatty acid -oxidation pathway. 相似文献