Evaluation of Granada agar plate for detection of Streptococcus agalactiae in urine specimens from pregnant women

The Granada agar plate (GAP; Biomedics SL, Madrid, Spain) was evaluated for the detection of group B streptococci (GBS) in urine specimens from pregnant women submitted for testing for asymptomatic bacteriuria and was compared with blood agar (BA [Columbia agar with 5% sheep blood]; bioMérieux, Marcy l'Etoile, France). The GAP detected 103 out of 105 GBS, whereas BA detected only 50. Use of the GAP could be a good method for the detection of GBS in urine specimens from pregnant women.     

Comparing bacterial genomes through conservation profiles

We constructed two-dimensional representations of profiles of gene conservation across different genomes using the genome of Escherichia coli as a model. These profiles permit both the visualization at the genome level of different traits in the organism studied and, at the same time, reveal features related to the genomes analyzed (such as defective genomes or genomes that lack a particular system). Conserved genes are not uniformly distributed along the E. coli genome but tend to cluster together. The study of gene distribution patterns across genomes is important for the understanding of how sets of genes seem to be dependent on each other, probably having some functional link. This provides additional evidence that can be used for the elucidation of the function of unannotated genes. Clustering these patterns produces families of genes which can be arranged in a hierarchy of closeness. In this way, functions can be defined at different levels of generality depending on the level of the hierarchy that is studied. The combined study of conservation and phenotypic traits opens up the possibility of defining phenotype/genotype associations, and ultimately inferring the gene or genes responsible for a particular trait.     

NADPH oxidase-mediated oxidative stress: genetic studies of the p22(phox) gene in hypertension

Increased vascular production of reactive oxygen species, especially superoxide anion, significantly contributes to the oxidative stress associated with hypertension. An enhanced superoxide production causes an increased inactivation of nitric oxide that diminishes nitric oxide bioavailability, thus contributing to endothelial dysfunction and hypertrophy of vascular cells. It has been shown that NADPH oxidases play a major role as the most important sources of superoxide anion in phagocytic and vascular cells. Several experimental observations have described an enhanced superoxide generation as a result of NADPH oxidase activation in hypertension. Although these enzymes respond to stimuli such as vasoactive factors, growth factors, and cytokines, recent data suggest a significant role of the genetic background in the modulation of the expression of its different components. Several polymorphisms have been identified in the promoter and in the coding region of CYBA, the gene that encodes the essential subunit of the NADPH oxidase p22phox, some of which seem to influence significantly the activity of these enzymes in the context of cardiovascular diseases. Among CYBA polymorphisms, genetic investigations have provided a novel marker, the -930(A/G) polymorphism, which determines the genetic susceptibility of hypertensive patients to oxidative stress.     

Recurrence of bronchioloalveolar carcinoma in donor lung after lung transplantation: microsatellite analysis demonstrates a recipient origin

Bronchioloalveolar carcinoma is a distinctive subtype of pulmonary adenocarcinoma, without effective therapy, although there have recently been some attempts to use lung transplantation. However, a high post-transplantation local recurrence rate is described with some controversy regarding the possible involved mechanisms, the main possibilities being the lymphatic spread and aerosolization. Presented herein is a case of a bilateral lung transplantation for a bilateral and pneumonic form of non-mucinous bronchioloalveolar carcinoma in a 43-year-old woman. The histological analysis of mediastinal lymph nodes during surgery did not show neoplastic cells. Thirty-five months after transplantation several nodular opacities in donor lungs were detected. Three pulmonary wedge resections were performed showing a non-mucinous bronchioloalveolar carcinoma with the same histological characteristics as the primary. Again, the mediastinal lymph nodes were tumor free. A complete microsatellites molecular analysis was performed to compare the primary and recurrent carcinoma using capillary electrophoresis, showing that the recurrent tumor was generated in a recipient cellular clone. The absence of lymph node metastasis and the molecular evidence of the recipient origin of the neoplasm supports the contamination of the new lungs at the time of implantation as being the reason for the high incidence of recurrence after lung transplantation in this kind of disease.     

Expression and function of alpha 4/beta 7 integrin on human natural killer cells.

In this report we have analysed the expression and function of the alpha 4/beta 7 heterodimer in human natural killer (NK) cells. The expression of alpha 4 beta 7 is induced in NK cells upon activation as the anti alpha 4 beta 2 ACT-1 monoclonal antibody (mAb) family stained a minority of peripheral blood NK cells, whereas it strongly reacted with in vitro long-term interleukin-2 (IL-2)-activated NK cells. Incubation with ACT-1 on its F(ab) fragments induced a strong homotypic adhesion of NK cells, comparable to than stimulated by the anti-alpha 4 HPI 7 mAb. Cell cell interaction induced by the ACT-1 mAb was only prevented by another anti-alpha 4 mAb (HP2.1) that recognizes a different epitope. In alpha 4 beta 7-mediated cell aggregation the alpha 4 beta 7 heterodimer was redistributed to intercellular contact sites thus, suggesting a direct involvement of this integrin in the formation of cell clusters. In NK cells attached to Fibronectin (FN38) or vascular cell adhesion molecule-1 (VCAM-1), both alpha 4 beta 7 and alpha 4 beta 7 integrins were redistributed at the ventral cellular membrane forming discrete contact sites. The ACT-1 mAb only partially blocked NK cell binding to FN38, but in combination with the anti-beta 7 mAb LIAI 2, NK cell binding to FN38 was completely inhibited. In contrast. ACT-1 did not modify NK cell adhesion to VCAM-1 thus supporting the theory that the alpha 4 beta 7 binding sites for both ligands appear to be different. Our results indicate that upon IL-2-activation, expression of functional alpha 4 beta-integrin is induced on NK cells potentially participating in their interaction with both extracellular matrix and endothelial cells.     

Synthesis and function of the mitochondrial intron —encoded bI4 RNA maturase from Saccharomyces cerevisiae

Summary We have analyzed the expression and function of the intron-encoded bI4 maturase when frame-shift mutations in the upstream exon alter the translational process. By constructing secondary cis-acting mutations within the b14 intron, we observed (1) that the bI4 maturase is still translated in the presence of the upstream mutation, albeit in very low amounts, and (2) that the limited amounts of bI4 maturase made under these conditions is no longer able to promote the splicing process of the aI4 intron. These observations, which further strengthen the maturase model, strongly suggest that bI4 maturase acts sequentially on the bI4 intron and then on the aI4 intron.     

Prevalences, genotypes, and risk factors for HIV transmission in South America

HIV cross-sectional studies were conducted among high-risk populations in 9 countries of South America. Enzyme-linked immunosorbent assay screening and Western blot confirmatory testing were performed, and env heteroduplex mobility assay genotyping and DNA sequencing were performed on a subset of HIV-positive subjects. HIV prevalences were highest among men who have sex with men (MSM; 2.0%-27.8%) and were found to be associated with multiple partners, noninjection drug use (non-IDU), and sexually transmitted infections (STIs). By comparison, much lower prevalences were noted among female commercial sex workers (FCSWs; 0%-6.3%) and were associated mainly with a prior IDU and STI history. Env subtype B predominated among MSM throughout the region (more than 90% of strains), whereas env subtype F predominated among FCSWs in Argentina and male commercial sex workers in Uruguay (more than 50% of strains). A renewed effort in controlling STIs, especially among MSM groups, could significantly lessen the impact of the HIV epidemic in South America.     

Reduced expression of surface glycoproteins in mouse fibroblasts persistently infected with human respiratory syncytial virus (HRSV)

Summary.  BCH4 cells, persistently infected with Human Respiratory Syncytial Virus (HRSV), were obtained by Fernie et al. [12] after infection of a BALB/c mouse embryo cell line with the Long strain of HRSV. To understand the basis of HRSV persistence, the expression of HRSV RNAs and proteins was evaluated in BCH4 cells and infected parental BALB/c and fully permissive HEp-2 cells. Production of viral mRNAs was severely impaired in BCH4 cells. In addition, the expression level of the surface glycoproteins F and G was markedly reduced relative to internal viral proteins. However, virus recovered from BCH4 cells could lytically infect HEp-2 cells and expressed normal levels of surface glycoproteins. No evidence of defective genomes or interfering particles was found in BCH4 cells. Taken together, these data indicate that reduction of both viral mRNA accumulation and surface glycoprotein biosynthesis are at the basis of HRSV persistence in BCH4 cells. Accepted November 3, 2000     

Enteroadherent Escherichia coli as a cause of diarrhea among children in Mexico.

Enteropathogenic Escherichia coli (EPEC) often exhibits localized adherence or diffuse adherence to HEp-2 cells. We recently provided evidence that HEp-2 cell-adherent or enteroadherent E. coli (EAEC) not belonging to EPEC serogroups was the cause of diarrhea among U.S. travelers to Mexico. In the present study, we looked for EAEC and EPEC in stool specimens from 154 children with acute diarrhea and 137 well children seen at several outpatient clinics in Guadalajara, Mexico. EAEC showing localized adherence (EAEC-L) was isolated from 13.0% of the patients and 0.7% of the controls (P less than 0.0001). EAEC showing diffuse adherence (EAEC-D) was recovered from 20.8% of the patients and 7.3% of the controls (P less than 0.001). EPEC was isolated from 4.5 and 6.7% of the patients and controls, respectively. Among all enteropathogens, only enterotoxigenic E. coli occurred as commonly (21.4%) as EAEC-D and EAEC-L did in children with diarrhea. Of the EAEC-L strains isolated from children with diarrhea, 20% belonged to recognized EPEC serogroups, and 3.1% of EAEC-D strains belonged to recognized EPEC serogroups. This study suggests that EAEC may be an important pediatric enteropathogen in Mexican children with diarrhea and further supports the observation that adherence to HEp-2 cells may be a marker of virulence independent of EPEC serogroup among E. coli strains.