Late-onset posttraumatic septal hematoma and abscess formation in a six-year-old Tamil girl--case report and literature review

Nasal septal hematoma with abscess (NSHA) is an uncommon complication of trauma and studies on children are especially rare. We discuss the case of a 6-year-old girl, who was initially evaluated independently by three doctors for minor nasal trauma but had to be re-hospitalized 6 days later with NSHA. Although septal hematoma had initially been excluded (5, 7 and 24 hours after trauma), a secondary accumulation of blood seems to have occured. Delayed hematoma formation has been described in the orbit as a result of possible venous injuries after endoscopic sinus surgery. However, such an observation is new for septal hematoma in children. Thus, we recommend re-evaluation for septal hematoma 48h to 72h after paediatric nasal trauma. Such a scheduled re-examination offers a chance to treat delayed subperichondral hematoma on time before almost inevitable superinfection leads to abscess formation and destruction of the nasal infrastructure. We suggest that parents should be vigilant for delayed nasal obstruction as possible herald of hematoma accumulation within the first week.

Subverting the subject position : toward a new discourse about students as writers and engineering students as technical communicators

There is ample evidence of a longstanding and pervasive discourse positioning students, and engineering students in particular, as “bad writers.” This is a discourse perpetuated within the academy, the workplace, and society at large. But what are the effects of this discourse? Are students aware faculty harbor the belief students can’t write? Is student writing or confidence in their writing influenced by the negative tone of the discourse? This dissertation attempts to demonstrate that a discourse disparaging student writing exists among faculty, across disciplines, but particularly within the engineering disciplines, as well as to identify the reach of that discourse through the deployment of two attitudinal surveys—one for students, across disciplines, at Michigan Technological University and one for faculty, across disciplines at universities and colleges both within the United States and internationally. This project seeks to contribute to a more accurate and productive discourse about engineering students, and more broadly, all students, as writers—one that focuses on competencies rather than incompetence, one that encourages faculty to find new ways to characterize students as writers, and encourages faculty to recognize the limits of the utility of practitioner lore.

Sphingosine 1-phosphate (S1P) induces COX-2 expression and PGE2 formation via S1P receptor 2 in renal mesangial cells

Understanding the mechanisms of sphingosine 1-phosphate (S1P)-induced cyclooxygenase (COX)-2 expression and prostaglandin E2 (PGE2) formation in renal mesangial cells may provide potential therapeutic targets to treat inflammatory glomerular diseases. Thus, we evaluated the S1P-dependent signaling mechanisms which are responsible for enhanced COX-2 expression and PGE2 formation in rat mesangial cells under basal conditions. Furthermore, we investigated whether these mechanisms are operative in the presence of angiotensin II (Ang II) and of the pro-inflammatory cytokine interleukin-1β (IL-1β). Treatment of rat and human mesangial cells with S1P led to concentration-dependent enhanced expression of COX-2. Pharmacological and molecular biology approaches revealed that the S1P-dependent increase of COX-2 mRNA and protein expression was mediated via activation of S1P receptor 2 (S1P2). Further, inhibition of Gi and p42/p44 MAPK signaling, both downstream of S1P2, abolished the S1P-induced COX-2 expression. In addition, S1P/S1P2-dependent upregulation of COX-2 led to significantly elevated PGE2 levels, which were further potentiated in the presence of Ang II and IL-1β. A functional consequence downstream of S1P/S1P2 signaling is mesangial cell migration that is stimulated by S1P. Interestingly, inhibition of COX-2 by celecoxib and SC-236 completely abolished the migratory response. Overall, our results demonstrate that extracellular S1P induces COX-2 expression via activation of S1P2 and subsequent Gi and p42/p44 MAPK-dependent signaling in renal mesangial cells leading to enhanced PGE2 formation and cell migration that essentially requires COX-2. Thus, targeting S1P/S1P2 signaling pathways might be a novel strategy to treat renal inflammatory diseases.

Enterococcus faecalis rnjB is required for pilin gene expression and biofilm formation.

Pili in Gram-positive bacteria play a major role in the colonization of host tissue and in the development of biofilms. They are promising candidates for vaccines or drug targets since they are highly immunogenic and share common structural and functional features among various Gram-positive pathogens. Numerous publications have helped build a detailed understanding of pilus surface assembly, yet regulation of pilin gene expression has not been well defined. Utilizing a monoclonal antibody developed against the Enterococcus faecalis major pilus protein EbpC, we identified mutants from a transposon (Tn) insertion library which lack surface-exposed Ebp pili. In addition to insertions in the ebp regulon, an insertion in ef1184 (dapA) significantly reduced levels of EbpC. Analysis of in-frame dapA deletion mutants and mutants with the downstream gene rnjB deleted further demonstrated that rnjB was responsible for the deficiency of EbpC. Sequence analysis revealed that rnjB encodes a putative RNase J2. Subsequent quantitative real-time PCR (qRT-PCR) and Northern blotting demonstrated that the ebpABC mRNA transcript level was significantly decreased in the rnjB deletion mutant. In addition, using a reporter gene assay, we confirmed that rnjB affects the expression of the ebpABC operon. Functionally, the rnjB deletion mutant was attenuated in its ability to produce biofilm, similar to that of an ebpABC deletion mutant which lacks Ebp pili. Together, these results demonstrate the involvement of rnjB in E. faecalis pilin gene expression and provide insight into a novel mechanism of regulation of pilus production in Gram-positive pathogens.

Studies of subcellular localization and complex formation of the Agrobacterium tumefaciens transport ATPase VirB11

The VirB11 ATPase is an essential component of an Agrobacterium tumefaciens type IV bacterial secretion system that transfers oncogenic nucleoprotein complexes to susceptible plant cells. This dissertation investigates the subcellular localization and homo-oligomeric state of the VirB11 ATPase in order to provide insights about the assembly of the protein as a subunit of this membrane-associated transfer system. Subcellular fractionation studies and quantitative immunoblot analysis demonstrated that $\sim$30% of VirB11 partitioned as soluble protein and $\sim$70% was tightly associated with the bacterial cytoplasmic membrane. No differences were detected in VirB11 subcellular localization and membrane association in the presence or absence of other transport system components. Mutations in virB11 affecting protein function were mapped near the amino terminus, just upstream of a region encoding a Walker 'A' nucleotide-binding site, and within the Walker 'A' motif partitioned almost exclusively with the cytoplasmic membrane, suggesting that an activity associated with nucleotide binding could modulate the affinity of VirB11 for the cytoplasmic membrane. Merodiploid analysis of VirB11 mutant and truncation derivatives provided strong evidence that VirB11 functions as a homo- or heteromultimer and that the C-terminal half of VirB11 contains a protein interaction domain. A combination of biochemical and molecular genetic approaches suggested that VirB11 and the green fluorescence protein (GFP) formed a mixed multimer as demonstrated by immunoprecipitation experiments with anti-GFP antibodies. Second, a hybrid protein composed of VirB11 fused to the N-terminal DNA-binding domain of bacteriophage $\lambda$ cI repressor conferred immunity to $\lambda$ superinfection, demonstrating that VirB11 self-association promotes dimerization of the chimeric repressor. A conserved Walker 'A' motif, though required for VirB11 function in T-complex export, was not necessary for VirB11 self-association. Sequences in both the N- and the C-terminal halves of the protein were found to contribute to self-association of the full length protein. Chemical cross-linking experiments with His$\sb6$ tagged VirB11 suggested that VirB11 probably assembles into a higher order homo-oligomeric complex. ^

Exploring Hoogsteen and reversed-Hoogsteen duplex and triplex formation with tricyclo-DNA purine sequences

The duplex- and triplex-formation properties of the tricyclo-DNA purine decamer 5'p-gagaaggaaa-3' as a single strand or as part of a hairpin duplex with corresponding parallel and antiparallel pyrimidine DNA and RNA complements, as well as with antiparallel purine DNA and RNA complements, were investigated by UV melting curve analysis, circular dichroism spectroscopy, and gel mobility shift experiments. It was found that tricyclo-DNA forms very stable duplexes with the pyrimidine RNA and DNA complements not only in the Watson-Crick pairing mode, but also in the Hoogsteen one. Below pH 6.0, the tc-DNA/DNA and tc-DNA/RNA Hoogsteen duplexes were found to be more stable than the corresponding Watson-Crick DNA duplexes. Triplexes of the hairpin structure with parallel pyrimidine complements revealed even stronger Hoogsteen pairing relative to the duplexes, presumably due to structural preorganization phenomena. Triplex formation with antiparallel pyrimidine and purine third strands (reversed-Hoogsteen motif) could not be observed and seem to be unstable