No abstract

Tuberculin conversion among health care workers was strongly associated with inadequate ventilation in general patient rooms and with type and duration of work, but not with ventilation of respiratory isolation rooms.

Delayed diagnosis of active pulmonary tuberculosis (TB) among hospitalized patients is common and believed to contribute significantly to nosocomial transmission. This study was conducted to define the occurrence, associated patient risk factors, and outcomes among patients and exposed workers of delayed diagnosis of active pulmonary TB. Among 429 patients newly diagnosed to have active pulmonary TB between June 1992 and June 1995 in 17 acute-care hospitals in four Canadian cities, initiation of appropriate treatment was delayed 1 week or more in 127 (30%). This was associated with atypical clinical and demographic patient characteristics, and after adjustment for these characteristics, with admission to hospitals with low TB admission rate of 0.2-3.3 per 10,000 admissions (odds ratio [OR]: 7.4; 95% confidence interval [CI]: 3.2,17.5) or intermediate TB admissions of 3.4-9.9/10,000 (OR: 2.3; CI: 1.6,3.2) as well as potentially preventable (late) intensive care unit admission (OR: 16.8; CI: 2.0,144) and death (OR: 3.3; CI: 1.7,6.5]). In hospitals with low TB admission rates, initially missed diagnosis, smear-positive patients undergoing bronchoscopy, late intensive care unit admission (OR: 2.3; CI: 0.1,56), and death (OR: 3.8; CI: 1.2,12.1) were more common than in hospitals with high TB admissions (> 10/ 10,000); a similar trend was seen in hospitals with intermediate TB admissions. Even after adjustment for workers' characteristics and ventilation in patients' rooms tuberculin conversions were disproportionately high in hospitals with low and intermediate TB admission rates and significantly higher in hospitals with overall TB mortality rate above 10% (OR: 2.5; CI: 1.6,3.7). In the hospitals studied, as the rate of TB admissions decreased, the likelihood of poor outcomes and risk of transmission of TB infection per hospitalized patient with TB increased. Institutional risk of TB transmission was poorly correlated with number of patients with TB and better correlated with indicators of patient care such as delayed diagnosis and treatment and overall TB-related patient mortality.

In animal cells, myo-inositol is an important regulatory molecule in several physiological and biochemical processes, including signal transduction and membrane biogenesis. However, the fundamental biological functions of myo-inositol are still far from clear in plants. Here, we report the genetic characterization of three Arabidopsis thaliana genes encoding D-myo-inositol-3-phosphate synthase (MIPS), which catalyzes the rate-limiting step in de novo synthesis of myo-inositol. Each of the three MIPS genes rescued the yeast ino1 mutant, which is defective in yeast MIPS gene INO1, and they had different dynamic expression patterns during Arabidopsis embryo development. Although single mips mutants showed no obvious phenotypes, the mips1 mips2 double mutant and the mips1 mips2 mips3 triple mutant were embryo lethal, whereas the mips1 mips3 and mips1 mips2 +/2 double mutants had abnormal embryos. The mips phenotypes resembled those of auxin mutants. Indeed, the double and triple mips mutants displayed abnormal expression patterns of DR5:green fluorescent protein, an auxin-responsive fusion protein, and they had altered PIN1 subcellular localization. Also, membrane trafficking was affected in mips1 mips3. Interestingly, overexpression of PHOSPHATIDYLINOSITOL SYNTHASE2, which converts myoinositol to membrane phosphatidylinositol (PtdIns), largely rescued the cotyledon and endomembrane defects in mips1 mips3. We conclude that myo-inositol serves as the main substrate for synthesizing PtdIns and phosphatidylinositides, which are essential for endomembrane structure and trafficking and thus for auxin-regulated embryogenesis.

No abstract

Live-cell pH measurements: An environment-sensitive fluorophore (green) was site-specifically introduced on HdeA, an acid-resistant chaperone showing pH-mediated conformational changes under low pH conditions. A survey of the attachment sites led to the discovery of one position on HdeA at which the attached fluorophore showed a strong fluorescence increase upon acidification.

This manuscript has been reproduoed from the microfilm rnaster. UMI films the text directly from the original or copy submitted. Thus. some thesis and dissertation copies are in typewriter face, while others may be from any type of cornputer printer.The quality of this reproduction is dependent upon the quality of the copy submitted. Broken or indistinct print. colored or poor quality illustrations and photographs, print bleedthrough, substandard margins, and improper alignment can adversely affect reproduction.In the unlikely event that the author did not send UMI a wmplete manuscript and there are missing pages, these will be noted. Also, if unauthorized copyright rnaterial had to be removed, a note will indicate the deletion.Oversize materials (e-g., maps, drawings, charts) are reproduoed by sedioning the original. beginning at the upper lefl-hand corner and continuing from left to right in equal sections with small overlaps. Each original is also photographed in one exposure and is induded in reduced f o m at the back of the book.Photographs induded in the original manuscript have been reproduced xerographically in this copy. Higher quality 6" x 9" black and white photographie prints are available for any photographs or illustrations appearing in this copy for an additional charge. Contact UMI directly to order. Canada canadaThe author has granted a nonexclusive licence allowing the National Libmy of Canada to reproduce, loan, distribute or sell copies of this thesis in microfonn, paper or electronic formats.The author retains ownership of the copyright in this thesis. Neither the thesis nor substantial extracts fkom it may be printed or otherwise reproduced without the author's permission.L'auteur a accordé une licence non exclusive permettant à la Bibliothèque nationale du Canada de reproduire, prêter, distribuer ou vendre des copies de cette thèse sous la forme de microfiche/fdm, de reproduction sur papier ou sur format électronique.L'auteur conserve la propriété du droit d'auteur qui protège cette thèse. Ni la thèse ni des extraits substantiels de celle-ci ne doivent être imprimés ou autrement reproduits sans son autorisation. A RISK INDEX FOR STERNAL SURGICAL WOUND INFECTION AFTERCAmIovASCULAR SURGERY Masters of Science, Epidemiology Mïchele Kohli Graduate Department of Community HealthUniversity of TorontoThe purpose of this study was to look at factors that increase the risk of stemal wgicai wound infection d e r cardiovasmlar surgery and to develop a clinical index to identie patients who are at high risk of infection. This study was based on data fiom 1 1,508 cardiac nirgery patients at the Toronto Hospital and emplo yed stepwise logistic regression techniques. The data were split into 3 groups so that validation could be done on new, independent data sets. The study found that reoperation due to complication, diabetes, more than 3 days in the intensive care unit and use of the interna1 mammary artery for revascularization were significant risk factors and these factors were included in the index. ...

A new strategy for quantitatively detecting micrococcal nuclease (MNase) is proposed using electrostatic interaction-based fluorescence resonance energy transfer (FRET) between positively charged QDs and negatively charged dye-labeled single-stranded DNA (dye-ssDNA). Herein, we have made our attempt to develop a strategy where the variation of FRET efficiency is due to the change of the electrostatic interaction between QDs and the ssDNA that result from the cleavage of dye-ssDNA by a single-strand-specific nuclease. To demonstrate the feasibility of this design, positively charged QDs (lysozyme modified QDs, Lyz-QDs) are prepared as the energy donor, with the fluorescent dye 6-carboxy-X-rhodamine (ROX) that is labeled to ssDNA serving as the energy acceptor. The ROX-labeled probe ssDNA (ROX-ssDNA) is absorbed to the surface of the QDs through electrostatic interaction, which results in resonance energy transfer between the QDs and the dye. In the presence of MNase which cleaves the ROX-ssDNA into small fragments, the weakened interaction between QDs and the shortened ssDNA causes the decrease of FRET efficiency. At given amounts of donor and acceptor, the ratio of fluorescence intensity of QDs to ROX changes in a MNase concentration-dependent manner. Under optimized conditions, the ratio is linear with MNase concentration over the range of 8 x 10(-3) to 9.0 x 10(-2) unit mL(-1), with a limit of detection of 1.6 x 10(-3) unit mL(-1). This new detection strategy features straightforward design and easy operation, which is capable of expanding the application of the positively charged QDs-based FRET in DNA-related bioassays.