Antimicrobial resistance among Brazilian Corynebacterium diphtheriae strains

The increasing problems with multidrug resistance in relation to Corynebacterium, including C. diphtheriae, are examples of challenges confronting many countries. For this reason, Brazilian C. diphtheriae strains were evaluated by the E-Test for their susceptibility to nine antibacterial drugs used in therapy. Resistance (MIC < 0.002; 0.38 microg/ml) to penicillin G was found in 14.8% of the strains tested. Although erythromycin (MIC90 0.75 microg/ml) and azithromycin (MIC90 0.064 microg/ml) were active against C. diphtheriae in this study, 4.2% of the strains showed decreased susceptibility (MIC 1.0 microg/ml) to erythromycin. Multiple resistance profiles were determined by the disk diffusion method using 31 antibiotics. Most C. diphtheriae strains (95.74%) showed resistance to mupirocin, aztreonam, ceftazidime, and/or oxacillin, ampicillin, penicillin, tetracycline, clindamycin, lincomycin, and erythromycin. This study presents the antimicrobial susceptibility profiles of Brazilian C. diphtheriae isolates. The data are of value to practitioners, and suggest that some concern exists regarding the use of penicillin.     

Direct Detection by In Situ PCR of the amoA Gene in Biofilm Resulting from a Nitrogen Removal Process

Ammonia oxidation is a rate-limiting step in the biological removal of nitrogen from wastewater. Analysis of microbial communities possessing the amoA gene, which is a small subunit of the gene encoding ammonia monooxygenase, is important for controlling nitrogen removal. In this study, the amoA gene present in Nitrosomonas europaea cells in a pure culture and biofilms in a nitrifying reactor was amplified by in situ PCR. In this procedure, fixed cells were permeabilized with lysozyme and subjected to seminested PCR with a digoxigenin-labeled primer. Then, the amplicon was detected with an alkaline phosphatase-labeled antidigoxigenin antibody and HNPP (2-hydroxy-3-naphthoic acid-2′-phenylanilide phosphate), which was combined with Fast Red TR, and with an Alexa Fluor 488-labeled antidigoxigenin antibody. The amoA gene in the biofilms was detected with an unavoidable nonspecific signal when the former method was used for detection. On the other hand, the amoA gene in the biofilms was detected without a nonspecific signal, and the cells possessing the amoA gene were clearly observed near the surface of the biofilm when Alexa Fluor 488-labeled antidigoxigenin antibody was used for detection. Although functional gene expression was not detected in this study, detection of cells in a biofilm based on their function was demonstrated.     

Determination of Pyrimidine Dimers in Escherichia coli and Cryptosporidium parvum during UV Light Inactivation, Photoreactivation, and Dark Repair

UV inactivation, photoreactivation, and dark repair of Escherichia coli and Cryptosporidium parvum were investigated with the endonuclease sensitive site (ESS) assay, which can determine UV-induced pyrimidine dimers in the genomic DNA of microorganisms. In a 99.9% inactivation of E. coli, high correlation was observed between the dose of UV irradiation and the number of pyrimidine dimers induced in the DNA of E. coli. The colony-forming ability of E. coli also correlated highly with the number of pyrimidine dimers in the DNA, indicating that the ESS assay is comparable to the method conventionally used to measure colony-forming ability. When E. coli were exposed to fluorescent light after a 99.9% inactivation by UV irradiation, UV-induced pyrimidine dimers in the DNA were continuously repaired and the colony-forming ability recovered gradually. When kept in darkness after the UV inactivation, however, E. coli showed neither repair of pyrimidine dimers nor recovery of colony-forming ability. When C. parvum were exposed to fluorescent light after UV inactivation, UV-induced pyrimidine dimers in the DNA were continuously repaired, while no recovery of animal infectivity was observed. When kept in darkness after UV inactivation, C. parvum also showed no recovery of infectivity in spite of the repair of pyrimidine dimers. It was suggested, therefore, that the infectivity of C. parvum would not recover either by photoreactivation or by dark repair even after the repair of pyrimidine dimers in the genomic DNA.     

Cloning of an immunoglobulin family adhesion molecule selectively expressed by endothelial cells

To gain fundamental information regarding the molecular basis of endothelial cell adhesive interactions during vascular formation, we have cloned and characterized a unique cell adhesion molecule. This molecule, named endothelial cell-selective adhesion molecule (ESAM), is a new member of the immunoglobulin superfamily. The conceptual protein encoded by cDNA clones consists of V-type and C2-type immunoglobulin domains as well as a hydrophobic signal sequence, a single transmembrane region, and a cytoplasmic domain. Northern blot analysis showed ESAM to be selectively expressed in cultured human and murine vascular endothelial cells and revealed high level expression in lung and heart and low level expression in kidney and skin. In situ hybridization analysis indicated that ESAM is primarily expressed in the developing vasculature of the embryo in an endothelial cell-restricted pattern. Epitope-tagged ESAM was shown to co-localize with cadherins and catenins in cell-cell junctions. In aggregation assays employing ESAM-expressing Chinese hamster ovary cells, this novel molecule was shown to mediate cell-cell adhesion through homophilic interactions. The endothelial cell-selective expression of this immunoglobulin-like adhesion molecule coupled with its in vitro functional profile strongly suggests a role in cell-cell interactions that is critical for vascular development or function.     

The Schizosaccharomyces pombe spo20(+) gene encoding a homologue of Saccharomyces cerevisiae Sec14 plays an important role in forespore membrane formation

The Schizosaccharomyces pombe spo20-KC104 mutation was originally isolated in a screen for sporulation-deficient mutants, and the spo20-KC104 mutant exhibits temperature-sensitive growth. Herein, we report that S. pombe, spo20(+) is essential for fission yeast cell viability and is constitutively expressed throughout the life cycle. We also demonstrate that the spo20(+) gene product is structurally homologous to Saccharomyces cerevisiae Sec14, the major phosphatidylinositol transfer protein of budding yeast. This structural homology translates to a significant degree of functional relatedness because reciprocal complementation experiments demonstrate that each protein is able to fulfill the essential function of the other. Moreover, biochemical experiments show that, like Sec14, Spo20 is a phosphatidylinositol/phosphatidylcholine-transfer protein. That Spo20 is required for Golgi secretory function in vegetative cells is indicated by our demonstration that the spo20-KC104 mutant accumulates aberrant Golgi cisternae at restrictive temperatures. However, a second phenotype observed in Spo20-deficient fission yeast is arrest of cell division before completion of cell separation. Consistent with a direct role for Spo20 in controlling cell septation in vegetatively growing cells, localization experiments reveal that Spo20 preferentially localizes to the cell poles and to sites of septation of fission yeast cells. We also report that, when fission yeasts are challenged with nitrogen starvation, Spo20 translocates to the nucleus. This nuclear localization persists during conjugation and meiosis. On completion of meiosis, Spo20 translocates to forespore membranes, and it is the assembly of forespore membranes that is abnormal in spo20-KC104 cells. In such mutants, a considerable fraction of forming prespores fail to encapsulate the haploid nucleus. Our results indicate that Spo20 regulates the formation of specialized membrane structures in addition to its recognized role in regulating Golgi secretory function.     

Acute phase proteins, body temperature and urinary melatonin under the influence of bright and dim light intensities during the daytime

Concentrations of five acute phase proteins: C-reactive protein (CRP), alpha 1-antichymotrypsin (ACT), transferin (Tf), alpha 2-macroglobulin (alpha 2-M) and haptoglobin (Hp) as well as glycosylation profiles of alpha 1-antichymotrypsin (ACT) were studied in sera samples with 7 healthy volunteers under the influence of two different light intensities during the daytime dim (100 lx) and bright (3000 lx) light. Concentration of transferin (negative proteins) under the influence of bright light during the daytime decreased significantly. Other proteins have the tendency to increase (positive proteins) under the influence of daytime bright light. The microheterogeneity of ACT did not change under the influence of different light intensities. Melatonin and rectal temperature were also measured simultaneously. Rectal temperature decreased to be lower during the first half of the night and urinary melatonin secretion rate increased to be higher during the night when the subjects spent time under the bright light during the day. Thus, it is concluded that the diurnal bright light exposure may activate some parameters of acute phase proteins, increase nocturnal melatonin secretion and accelerate a fall of rectal temperature during first half period of night sleep.