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B Demers

Publications and source records attributed to B Demers.

10 recordsLinked to original sources
PubMed1998

Induction of type III secretion in Shigella flexneri is associated with differential control of transcription of genes encoding secreted proteins.

Shigella, the etiological agent of human bacillary dysentery, invades the colonic epithelium where it induces an intense inflammatory response. Entry of Shigella into epithelial cells involves a type III secretion machinery, encoded by the mxi and spa operons, and the IpaA-D secreted proteins. In this study, we have identified secreted proteins of 46 and 60 kDa as the products of virA and ipaH9.8, respectively, the latter being a member of the ipaH multigene family. Inactivation of virA did not affect entry into epithelial cells. Using lacZ transcriptional fusions, we found that transcription of virA and four ipaH genes, but not that of the ipaBCDA and mxi operons, was markedly increased during growth in the presence of Congo red and in an ipaD mutant, two conditions in which secretion through the Mxi-Spa machinery is enhanced. Transcription of the virA and ipaH genes was also transiently activated upon entry into epithelial cells. These results suggest that transcription of the virA and ipaH genes is regulated by the type III secretion machinery and that a regulatory cascade differentially controls transcription of genes encoding secreted proteins, some of which, like virA, are not required for entry.

Amino Acid Sequence↗
PubMed1993

Severe invasive group A streptococcal infections in Ontario, Canada: 1987-1991.

During the past few years, there has been an apparent increase in serious infections due to group A streptococci (GAS) worldwide. We describe our experience with severe invasive GAS infections in Ontario, Canada, during the past 5 years (February 1987 through December 1991). A case was defined as the isolation of GAS from blood or normally sterile tissue in association with hypotension (systolic blood pressure, < 90 mm Hg). Fifty cases were identified in patients ranging in age from 4 to 100 years (median age, 47 years); 29 (58%) of the patients died. A primary focus of infection was identified in 38 cases (76%), with soft tissue being the site involved most frequently (68%). No focus of infection was found in 12 patients, and 36 patients (72%) were bacteremic. Complications included acute respiratory distress syndrome (21 of 50), acute renal failure (20 of 50), hypocalcemia (19 of 24), elevated creatinine kinase values (21 of 27), coagulation abnormalities (15 of 21), and hepatitis (15 of 24). Eleven cases (22%) were nosocomial; one of these was secondary to another nosocomial case. Thirty-three isolates were available for M and T typing and for determination of the presence of the genes for streptococcal pyrogenic exotoxin (SPE). The most frequent types were M1T1 (10) and M12/T12 (8). Twelve isolates possessed the speA gene, and 16 isolates had the speC gene. Only three isolates possessed both speA and speC. All isolates possessed the speB gene.

Adolescent↗
PubMedDate not supplied

Approaching the RSV season with a nursing plan of action.

As the statistics show with year-in, year-out regularity, during November through March in the United States, approximately 90,000 infants and young children will be hospitalized with a severe lower respiratory infection attributable to the respiratory syncytial virus (RSV). This virus, discovered only as recently as 1956, appears to be ubiquitous, infecting virtually 100% of children by age 4. For most of them the resulting illness will be mild and easily vanquished by an intact immune system. For some, however, RSV infection confers considerable morbidity, and these infants and children are the concern of the symposium held in conjunction with Pediatric Nursing's 11th annual conference. The symposium addressed several aspects of RSV infection: Who is at risk and should be hospitalized? How can nurses contribute to the care of hospitalized patients? Are there environmental risks to health-care personnel from ribavirin aerosol, the antiviral treatment approved for RSV infection? Are there special considerations for mechanically ventilated patients? Speakers generally concluded that symptomatic treatment and antiviral therapy with ribavirin aerosol can reduce severe morbidity in severely infected patients with minimal occupation risk to health-care personnel.

Administration, Inhalation↗