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171.
González-Robles A Castañón G Cristóbal-Ramos AR Lázaro-Haller A Omaña-Molina M Bonilla P Martínez-Palomo A 《Experimental parasitology》2006,114(3):133-140
In this study we report observations on the structural mechanisms of the cytopathic effect of Acanthamoeba castellanii trophozoites on cultured MDCK cell monolayers. Co-incubations were carried out for a maximum of 24h. The first evidence of damage to the cell monolayer was detected by measuring the transepithelial resistance of cell monolayers that interacted with the amoebae. At 6h, transepithelial resistance diminished to 51% and amoebae required 5-6h to produce evidence of structural injury at the light microscopy level. Following 12h of incubation, the cell monolayer was severely damaged. After making intimate contact with the surface of target cells, trophozoites detached cells from the substrate, lysed and by means of food-cups ingested the damaged cells. There was no morphological evidence of modifications in MDCK cell membranes, membrane fusion or junction formation between the amoeba and host plasma membrane. The lytic capacity of the amoebas appears to be the result of cytotoxic factors secreted by the amoebae since, when monolayers were incubated with conditioned medium, there was also a decrease in the transepithelial resistance. Besides, mechanical injury produced by the attachment and movement of the trophozoites may contribute to the disruption of the cell monolayer. As in other pathogenic amoebae, the cytopathic action of A. castellanii on the cell monolayers can subjectively be separated into four stages: adhesion, cytolysis, phagocytosis, and intracellular degradation. 相似文献
172.
Caspeta-Mandujano JM Granados Ramírez JG Peralta-Rodríguez JL 《The Journal of parasitology》2009,95(2):403-406
A new nematode species, Philometra poblana n. sp., is described based on specimens recovered from skin at the base of the pectoral fins of the cichlid Cichlasoma istlanum (Jordan and Snyder, 1899) from the water spring El Borbollon, in the State of Puebla, Mexico. The new species most closely resembles Philometra gymnosardae and Philometra ophisterni; however, P. poblana can be easily differentiated from the other species by the length of gravid females (7.10-10.43 vs. 14.8-27.0 and 28.67-39.30 mm, respectively), length of caudal projections (0.015-0.023 vs. 0.047 and 0.006-0.009 mm high, respectively), site of infection (skin at base of pectoral fins vs. abdominal cavity, both species), and the host species (Cichlidae vs. Synbranchidae and Scombridae). 相似文献
173.
Nabhen SL Perfume G Battistone MA Rossi A Abramoff T Bianciotti LG Vatta MS 《Neurochemical research》2009,34(5):953-963
The olfactory system in rats is part of the limbic region with extensive afferent connections with brain areas involved in
the regulation of behaviour and autonomic responses. The existence of the endothelin system and catecholaminergic neurons
in the olfactory bulb suggests that endothelins may modulate noradrenergic transmission and diverse olfactory mediated processes.
In the present work we studied the effect of endothelin-1 and -3 on neuronal norepinephrine release and the short-term regulation
of tyrosine hydroxylase in the olfactory bulb. Results showed that both endothelins increased tyrosine hydroxylase activity
through the activation of a non-conventional endothelin G-protein coupled receptor, coupled to the stimulation of protein
kinase A and C, as well as Ca2+/calmodulin-dependent protein kinase II. On the other hand, neither endothelin-1 nor endothelin-3 modified tyrosine hydroxylase
total protein levels, but both peptides increased the phosphorylation of serine residues of the enzyme at sites 19 and 40.
Furthermore, endothelins enhanced norepinephrine release in olfactory neurons suggesting that this event may contribute to
increased tyrosine hydroxylase activity by reducing the feedback inhibition. Taken together present findings show a clear
interaction between the endothelin system, and the catecholaminergic transmission in the olfactory bulb. Additional studies
are required to evaluate the physiological functions regulated by endothelins at this brain level. 相似文献
174.
175.
C. Ekaterina Rodríguez-Pérez Erika Calvo-Ochoa Ekaterina V. Kalashnikova Guadalupe Reyes-Cruz M. Teresa Romero-Ávila J. Adolfo García-Sáinz 《The international journal of biochemistry & cell biology》2009,41(6):1276-1283
Human α1D-adrenoceptors (truncated at the amino terminus (Δ1–79) to increase their membrane expression) were stably expressed in Rat-1 fibroblasts (1–1.5 pmol/mg protein). The receptors were functional as evidenced by a robust increase in intracellular calcium in response to noradrenaline. Using this cell line, the possibility that activation of receptor tyrosine kinases could modulate this adrenoceptor subtype was studied. It was observed that cell preincubation with insulin, IGF-I, EGF or PDGF markedly reduced the intracellular calcium increase observed in response to noradrenaline. Inhibitors of PI3K and PKC essentially blocked insulin-, IGF-I- and EGF-induced desensitizations. Interestingly, PDGF-induced α1D-adrenergic desensitization was only partially ameliorated by PI3K inhibitors and was not affected by those of PKC. Insulin, IGF-I, EGF and PDGF induced concentration-dependent increases in the phosphorylation state of α1D-adrenoceptors; phosphorylation took place on serine residues. Inhibitors of PI3K and PKC markedly reduced the effects of insulin, IGF-I and EGF on this parameter. These inhibitors only marginally reduced PDGF-induced α1D-adrenoceptors phosphorylation. The ability of IGF-I to induce α1D-adrenergic desensitization and phosphorylation was confirmed in cells expressing non-truncated rat α1D-adrenenoceptors. Our data indicate that the function and phosphorylation state of α1D-adrenoceptors is modulated by activation of receptor tyrosine kinases. Insulin, IGF-I and EGF actions take place through the action of PI3K and PKC; additional pathway(s) seem to participate in PDGF-induced α1D-adrenoceptor desensitization and phosphorylation. 相似文献
176.
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178.
Ma. Guadalupe Hernández-Linares Socorro Meza-Reyes María A. Fernández-Herrera 《Steroids》2010,75(3):240-244
We report the deacylation of (20R)-20-acetyl-23,24-dinorcholanic lactones by hydrazine hydrate, under microwave irradiation in high yields. The elimination of the 20-acetyl group proceeded with retention of configuration which contrast with other proved deacylation methods that yield a mixture of diastereoisomers. In this way, unnatural (20R)-23,24-dinorcholanic lactones can be produced rapidly on a large scale. Both (20R)- and (20S)-lactones were prepared starting from diosgenin, hecogenin and sarsasapogenin, in 72-80% overall yields. 相似文献
179.
José Raúl García-Lozano Cristina Abad Ana Escalera Belén Torres Olga Fernández Alicia García Julio Sánchez-Román José-Mario Sabio Norberto Ortego-Centeno Enrique Raya-Álvarez Antonio Núñez-Roldán Javier Martín María Francisca González-Escribano 《Human genetics》2010,128(2):221-229
Human HAVCR1 gene maps on 5q33.2, a region linked with susceptibility to allergic and autoimmune diseases. The aims of the present study were to define the haplotypes of HAVCR1 gene taking into account both HapMap Project SNP haplotypes and exon 4 variants, to investigate a possible relationship between these haplotypes and mRNA expression levels, and to assess whether HAVCR1 gene is involved in susceptibility to rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). Genotyping of three ins/del variants in the exon 4 was performed by fragment length analysis. Five tag SNPs genotypes and mRNA levels were determined using TaqMan assays. We defined four major haplotypes in our population: the two major haplotypes (named haplotypes A and B) bear both the 5383_5397del variant and the two most common SNP sets found in the CEU population. Quantification analysis revealed that genotype B/B had the highest median of mRNA expression levels (vs. BX + XX, p < 0.0001). Additionally, frequency of the genotype BB was significantly higher in RA patients than in controls (12.3 vs. 5.9% in controls, p = 0.0046, p c = 0.014, OR = 2.23, 95% CI 1.23–4.10). Our results support a relationship between HAVCR1 haplotypes and mRNA expression levels, and suggest an association of this gene with autoimmune diseases. 相似文献
180.