ZD4054, a potent endothelin receptor A antagonist, inhibits ovarian carcinoma cell proliferation

Endothelin-1 (ET-1) is present at high concentrations in ovarian cancer ascites and is overexpressed in primary and metastatic ovarian carcinomas. In these tumors, the presence of ET-1 correlates with tumor grade, enhanced neovascularization, and with vascular endothelial growth factor (VEGF) expression. ET-1 acts as an autocrine factor selectively through ET(A) receptor (ET(A)R), predominantly expressed in ovarian carcinoma cells resulting in increased VEGF production and VEGF-mediated angiogenic effects. Previous results demonstrated that in ovarian carcinoma cells, activation of the ET-1/ET(A)R axis promotes cell proliferation, neovascularization, and invasion, which are the principal hallmarks of tumor progression. The present study was designed to investigate the in vitro effects of trans, trans-2(4-methoxydhenyl)-4-(1-3-benzodiazol-5-yl)-1-(dibutylaminocarbonylmethyl)-pyrrolidine-3-carboxylic acid (ZD4054), an orally active specific ET(A)R antagonist, on the ET-1-induced mitogenic effect in OVCA 433 and HEY ovarian carcinoma cell lines secreting ET-1 and expressing ET(A)R and ET(B)R mRNA. We show that ET(A)R blockade by ZD4054 inhibits ET-1-induced mitogenic effects, while the ET(B)R antagonist, BQ 788, is ineffective. In conclusion, our data demonstrate that ZD4054 is capable in inhibiting the proliferative activity of ET-1, indicating that this specific ET(A)R antagonist may be a potential candidate in developing novel treatment of ovarian carcinoma.     

Endothelin-1 is required during epithelial to mesenchymal transition in ovarian cancer progression

In a range of human cancers, tumorigenesis is promoted by activation of the endothelin A receptor (ET(A)R)/endothelin-1 (ET-1) axis. ET-1 and ET(A)R are overexpressed in primary and metastatic ovarian carcinomas, and high levels of ET-1 are detectable in patient ascites, suggesting that ET-1 may promote tumor dissemination. Moreover, in these tumors, engagement of ET(A) receptor by ET-1 triggers tumor growth, survival, angiogenesis, and invasiveness. Thus, ET-1 enhances the secretion of matrix metalloproteinases, disrupts intercellular communications, and stimulates cell migration and invasion. Therefore, we investigated the role of the ET-1/ET(A)R autocrine axis in promoting epithelial to mesenchymal transition (EMT) in ovarian tumor cells, a key event in cancer metastasis, in which epithelial cells depolarize, disassemble cell-cell contacts, and adopt an invasive phenotype. Here, we examine the potential role of ET-1 in regulating cell morphology and behavior and epithelial and mesenchymal proteins employing an in vitro 3-D culture system. We found that in 3-D serum-free collagen I gel cultures, HEY and OVCA 433 ovarian carcinoma cells undergo fibroblast-like morphologic changes between 3 and 5 days of ET-1 treatment. In these cells, ET-1 induces loss of adherens and tight-junction protein expression, E-cadherin, beta-catenin, and zonula occludens-1, and gain of N-cadherin and vimentin expression. These results confirm the ability of ET-1 to promote EMT, a metastable process involving sustained loss of epithelial markers and gain of mesenchymal markers. Collectively, these findings provide evidence of a critical role for the ET-1/ET(A)R axis during distinct steps of ovarian carcinoma progression, thus underlining this axis as a potential target in the treatment of ovarian cancer.     

Colleters in Bathysa nicholsonii K. Schum. (Rubiaceae): ultrastructure, secretion protein composition, and antifungal activity

Colleters are secretory structures well distributed in many organs of Angiosperms. Ultrastructurally, the colleters secretory cell presents an enhanced endoplasmic reticulum, Golgi apparatus, and mitochondria. Secretion synthesis, transportation, and passage through outer cell wall is poorly characterized. This study characterized the anatomy and ultrastructure of BATHYSA NICHOLSONII (Rubiaceae) colleters and evaluated the presence of protein in the secretion and its antifungal property. Samples were collected and prepared according to usual techniques in light and electron microscopy, electrophoresis, and fungal growth inhibition assay. Colleters are of a standard type, cylindrical and elongated, formed by one secretory epidermal palisade layer, and a central axis formed by parenchymatic cells and a vascular trace. Epidermal cells have dense cytoplasm with abundant ribosome, a nucleus, enhanced endoplasmic reticulum and Golgi apparatus. The outer cell wall presented morphologically distinct layers. The presence of secretory cavities was noted in all outer cell wall extents. Secretion preparations analyzed by SDS-PAGE showed that B. NICHOLSONII secretion is a mixture of proteins with molecular masses covering a range of approximately 66 to 24 kDa. This preparation presented an inhibitory effect on the fungi spore growth.     

Ecologists can enable communities to implement malaria vector control in Africa

Background

Malaria imposes significant costs on households and the poor are disproportionately affected. However, cost data are often from quantitative surveys with a fixed recall period. They do not capture costs that unfold slowly over time, or seasonal variations. Few studies investigate the different pathways through which malaria contributes towards poverty. In this paper, a framework indicating the complex links between malaria, poverty and vulnerability at the household level is developed and applied using data from rural Kenya.

Methods

Cross-sectional surveys in a wet and dry season provide data on treatment-seeking, cost-burdens and coping strategies (n = 294 and n = 285 households respectively). 15 case study households purposively selected from the survey and followed for one year provide in-depth qualitative information on the links between malaria, vulnerability and poverty.

Results

Mean direct cost burdens were 7.1% and 5.9% of total household expenditure in the wet and dry seasons respectively. Case study data revealed no clear relationship between cost burdens and vulnerability status at the end of the year. Most important was household vulnerability status at the outset. Households reporting major malaria episodes and other shocks prior to the study descended further into poverty over the year. Wealthier households were better able to cope.

Conclusion

The impacts of malaria on household economic status unfold slowly over time. Coping strategies adopted can have negative implications, influencing household ability to withstand malaria and other contingencies in future. To protect the poor and vulnerable, malaria control policies need to be integrated into development and poverty reduction programmes.     

Biology and thermal exigency of Aedes aegypti (L.) (Diptera: Culicidae) from four bioclimatic localities of Paraíba

The present work aimed at estimating the thermal requirements for the development and the number of generations per year of Aedes aegypti (L.) under natural conditions. The life cycle of A. aegypti populations was studied at constant temperatures of 18, 22, 26, 30 and 34 degrees C, and 12 h photophase. The development period, egg viability and larval and pupal survival were evaluated daily as well as adult longevity and fecundity. The low threshold temperature of development (Tb) and the thermal constant (K) were determined. The number of generations per year in laboratory and field were also estimated. The favorable temperature to A. aegypti development is between 21 degrees C and 29 degrees C, and to longevity and fecundity is between 22 degrees C and 30 degrees C. The egg to adult basal temperature, thermal constant and the number of generations in field were, in order, 9.5, 8.5, 3.4, 7.1, 13.5 degrees C; 244.5, 273.9, 298.5, 280.9 and 161.8 degree-days; and 21.9, 23.8, 24.2, 21.1 and 22.1 generations in populations from Boqueir?o, Brejo dos Santos, Campina Grande, Itaporanga and Remígio.     

Isolation of Helicobacter pylori from the intestinal mucosa of patients with Crohn's disease

BACKGROUND: Helicobacter species are associated with inflammatory bowel disease in rodents and in nonhuman primates. Therefore, we prospectively investigated the presence of Helicobacter species in the intestinal mucosa of patients with and without Crohn's disease by culture and polymerase chain reaction (PCR) assays. MATERIALS AND METHODS: Mucosal fragments were obtained from the ileum, different colon regions, and rectum of 43 patients with Crohn's disease and of 74 patients without inflammatory bowel disease. RESULTS: Helicobacter pylori strains, identified by 16S rRNA gene sequencing, were more frequently isolated and PCR-detected in the intestinal mucosa of patients with ulcerative colitis-like Crohn's disease than in intestinal mucosa of the control group. Otherwise, anti-H. pylori immunoglobulin G levels were significantly lower in fibrostenosing and fistulating Crohn's disease subgroups. No other Helicobacter species were found in the intestinal mucosa of the patients. CONCLUSIONS: Although our results suggest an association between the presence of H. pylori in the intestine and ulcerative colitis-like phenotype of Crohn's disease, H. pylori infection in the actual causality of Crohn's disease is still to be determined.     

Uridine diphosphate-glucose transport into the endoplasmic reticulum of Saccharomyces cerevisiae: in vivo and in vitro evidence

It has been proposed that synthesis of beta-1,6-glucan, one of Saccharomyces cerevisiae cell wall components, is initiated by a uridine diphosphate (UDP)-glucose-dependent reaction in the lumen of the endoplasmic reticulum (ER). Because this sugar nucleotide is not synthesized in the lumen of the ER, we have examined whether or not UDP-glucose can be transported across the ER membrane. We have detected transport of this sugar nucleotide into the ER in vivo and into ER-containing microsomes in vitro. Experiments with ER-containing microsomes showed that transport of UDP-glucose was temperature dependent and saturable with an apparent Km of 46 microM and a Vmax of 200 pmol/mg protein/3 min. Transport was substrate specific because UDP-N-acetylglucosamine did not enter these vesicles. Demonstration of UDP-glucose transport into the ER lumen in vivo was accomplished by functional expression of Schizosaccharomyces pombe UDP-glucose:glycoprotein glucosyltransferase (GT) in S. cerevisiae, which is devoid of this activity. Monoglucosylated protein-linked oligosaccharides were detected in alg6 or alg5 mutant cells, which transfer Man9GlcNAc2 to protein; glucosylation was dependent on the inhibition of glucosidase II or the disruption of the gene encoding this enzyme. Although S. cerevisiae lacks GT, it contains Kre5p, a protein with significant homology and the same size and subcellular location as GT. Deletion mutants, kre5Delta, lack cell wall beta-1,6 glucan and grow very slowly. Expression of S. pombe GT in kre5Delta mutants did not complement the slow-growth phenotype, indicating that both proteins have different functions in spite of their similarities.     

Preliminary study on genetic variability of Dicrocoelium dendriticum determined by random amplified polymorphic DNA

Genetic variability of adult specimens of Dicrocoelium dendriticum has been studied using random amplified polymorphic DNA (RAPD). The worms were collected from the infected livers of different sheep from several localities in León province (NW Spain). DNA fragments were amplified by means of decamer primer oligonucleotides of arbitrary sequence. Some primers produce complex and highly variable patterns of amplified DNA in D. dendriticum. Intra- and inter-population genetic variability of adult parasites were analyzed, scoring polymorphic and monomorphic reproducible bands by means of the Jaccard similarity, and dendrograms showing genetic relationships between individuals were obtained using the FITCH method. Genetic variability seems to be high in this parasite and genetic similarity within a population (worms infecting a single animal) is similar to the average similarity between worms from different sheep. These results suggest that each sheep is infected by numerous genetically different parasites from one or more populations of infected ants.     

Central benzodiazepine involvement in clonidine cardiovascular actions

It is well known that the GABAergic and noradrenergic systems play an important role in blood pressure and heart rate regulation. Benzodiazepines and beta-carbolines, respectively, increase or decrease the probability of chloride-channel opening induced by GABA. The aim of this study was to determine, in conscious rats, the interaction existing between the central alpha2-adrenoceptor stimulation induced by clonidine and the facilitation or impairment of benzodiazepine receptor activity through the administration of either diazepam, a benzodiazepine receptor agonist, or methyl 6,7-dimethoxy-4-ethyl-beta-carboline-3-carboxylate (DMCM), an inverse benzodiazepine agonist. Clonidine (5-10 microg, intracerebroventricularly) reduced heart rate and increased mean blood pressure by activation of central alpha2-adrenoceptors. Diazepam (2 mg/kg, intravenously (i.v.)) induced an increase in heart rate, while DMCM (0.3 mg/kg, i.v.) elicited a bradycardic effect. The bradycardic effects induced by both clonidine and DMCM were antagonized by the prior administration of methylatropine (1.5 mg/kg, i.v.). DMCM (0.3 mg/kg, i.v.) prevented the clonidine effects on heart rate and mean blood pressure, while diazepam (2 mg/kg, i.v.) failed to modify these effects. Our results suggest that the bradycardic effects of clonidine are mediated by a vagal stimulation and are related to the activation of a GABAergic pathway.