University of Manitoba

About: University of Manitoba is a education organization based out in Winnipeg, Manitoba, Canada. It is known for research contribution in the topics: Population & Health care. The organization has 31888 authors who have published 66592 publications receiving 2095493 citations.

Association Between Intermittent Hypoxemia or Bradycardia and Late Death or Disability in Extremely Preterm Infants

Abstract: Importance Extremely preterm infants may experience intermittent hypoxemia or bradycardia for many weeks after birth. The prognosis of these events is uncertain. Objective To determine the association between intermittent hypoxemia or bradycardia and late death or disability. Design, Setting, and Participants Post hoc analysis of data from the inception cohort assembled for the Canadian Oxygen Trial in 25 hospitals in Canada, the United States, Argentina, Finland, Germany, and Israel, including 1019 infants with gestational ages of 23 weeks 0 days through 27 weeks 6 days who were born between December 2006 and August 2010 and survived to a postmenstrual age of 36 weeks. Follow-up assessments occurred between October 2008 and August 2012. Exposures Episodes of hypoxemia (pulse oximeter oxygen saturation Main Outcomes and Measures The primary outcome was a composite of death after 36 weeks’ postmenstrual age, motor impairment, cognitive or language delay, severe hearing loss, or bilateral blindness at 18 months’ corrected age. Secondary outcomes were motor impairment, cognitive or language delay, and severe retinopathy of prematurity. Results Downloaded saturation and pulse rate data were available for a median of 68.3 days (interquartile range, 56.8-86.0 days). Mean percentages of recorded time with hypoxemia for the least and most affected 10% of infants were 0.4% and 13.5%, respectively. Corresponding values for bradycardia were 0.1% and 0.3%. The primary outcome was ascertained for 972 infants and present in 414 (42.6%). Hypoxemic episodes were associated with an estimated increased risk of late death or disability at 18 months of 56.5% in the highest decile of hypoxemic exposure vs 36.9% in the lowest decile (modeled relative risk, 1.53; 95% CI, 1.21-1.94). This association was significant only for prolonged hypoxemic episodes lasting at least 1 minute (relative risk, 1.66; 95% CI, 1.35-2.05 vs for shorter episodes, relative risk, 1.01; 95% CI, 0.77-1.32). Relative risks for all secondary outcomes were similarly increased after prolonged hypoxemia. Bradycardia did not alter the prognostic value of hypoxemia. Conclusions and Relevance Among extremely preterm infants who survived to 36 weeks’ postmenstrual age, prolonged hypoxemic episodes during the first 2 to 3 months after birth were associated with adverse 18-month outcomes. If confirmed in future studies, further research on the prevention of such episodes is needed.

Interactions between cancer cells and the endothelium in metastasis.

Abstract: The haematogenous phase of cancer metastasis facilitates the transport of metastatic cells within the blood and incorporates a sequence of interactions between circulating intravascular cancer cells and the endothelium of blood vessels at the sites of tumour cell arrest. Initial interactions involve mechanical contact and transient adhesion, mediated by endothelial selectins and their ligands on the neoplastic cells. This contact initiates a sequence of activation pathways that involves cytokines, growth factors, bioactive lipids, and reactive oxygen species produced by either the cancer cell or the endothelium. These molecules elicit expression of integrin adhesion molecules in cancer cells and the endothelium, matrix metalloproteinases, and chemotactic factors that promote the attachment of tumour cells to the vessel wall and/or transvascular penetration. Induction of endothelial free radicals can be cytotoxic to cancer cells. Collectively, the sum of these interactions constitutes an interdependent relationship, the outcome of which determines the fate of the metastatic process.

Epidemic Clonal Groups of Escherichia coli as a Cause of Antimicrobial-Resistant Urinary Tract Infections in Canada, 2002 to 2004

Abstract: The extent to which clonal spread contributes to emerging antimicrobial resistance in Escherichia coli is incompletely defined. To address this question within a recent, nationally representative strain collection, three established drug-resistant E. coli clonal groups (i.e., clonal group A, E. coli O15:K52:H1, and sequence type 131 [ST131]) were sought among 199 E. coli urine isolates recovered from across Canada from 2002 to 2004, with stratification by resistance to trimethoprim-sulfamethoxazole (TS) and fluoroquinolones (FQs). The isolates' clonal backgrounds, virulence genotypes, and macrorestriction profiles were assessed. The three clonal groups were found to account for 37.2% of isolates overall, but accounted for 0% of TS-susceptible (TS-S) and FQ-susceptible (FQ-S) isolates, 20% of TS-resistant (TS-R) and FQ-S isolates, 60% of TS-S and FQ-R isolates, and 68% of TS-R and FQ-R isolates (P < 0.001). E. coli ST131, the most prevalent clonal group, accounted for 23.1% of isolates overall and for 44% of the FQ-R isolates. Nearly all ST131 isolates were FQ-R (96%) but, notably, cephalosporin susceptible (98%). Although the distinctive virulence profiles of the FQ-R clonal group isolates were less extensive than those of the susceptible isolates, they were significantly more extensive than those of the other FQ-R isolates. These findings indicate that among the E. coli urine isolates studied, resistance to TS and FQs has a prominent clonal component, with the O15:K52:H1 clonal group and especially E. coli ST131 being the major contributors. These clonal groups appear to be more virulent than comparably resistant isolates, possibly contributing to their success as emerging multi-drug-resistant pathogens.

The Crystal Chemistry of Sulfate Minerals

Abstract: Sulfur is the fifteenth most abundant element in the continental crust of the Earth (260 ppm), and the sixth most abundant element in seawater (885 ppm). Sulfur (atomic number 16) has the ground-state electronic structure [Ne]3 s 2 3p 4 , and is the first of the group VIB elements in the periodic table (S, Se, Te, Po). In minerals, sulfur can occur in the formal valence states S2−, S, S4+, and S6+, corresponding to the sulfide minerals, native sulfur , the sulfite minerals, and the sulfate minerals. In the sulfide minerals, S2− functions as a simple anion (e.g. CuFeS2, chalcopyrite) and as a compound S2 anion (e.g. FeS2, pyrite). In the sulfosalts, S2− functions as a component of a complex anion (e.g. AsS3 in tennantite, Cu12As4S13). In the sulfite minerals, S4+ has four valence electrons available for chemical bonding, and occurs in triangular pyramidal coordination with O. In the sulfate minerals, S6+ has six valence electrons available for bonding, and occurs in tetrahedral coordination with O. In addition, there are the thiosulfate minerals, in which S is in the hexavalent state, but is coordinated by three O2− anions and one S2− anion. Chemists frequently write the thiosulfate group as S2O3; however, we write it as SO3S to emphasize that one of the S atoms is an anion and is involved in a tetrahedral group. Although the focus of this chapter is the sulfate minerals, we will deal also with the sulfite and thiosulfate minerals, as they occur in the same types of geochemical environments. We adopt a pragmatic approach to matters involving chemical bonding. We use bond-valence theory …