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Alvares R.,University of Toronto | Gupta S.,University of Toronto | Gupta S.,Laboratory Medicine and Pathobiology | Macdonald P.M.,University of Toronto | Prosser R.S.,University of Toronto
Journal of Physical Chemistry B | Year: 2014

Bulk thermodynamic and volumetric parameters (δGmic°, δHmic°, δSmic°, δCp,mic °, δVmic°, and δκmic °) associated with the monomer-micelle equilibrium, were directly determined for a variety of common detergents [sodium n-dodecyl sulfate (SDS), n-dodecyl phosphocholine (DPC), n-dodecyl-β-d-maltoside (DDM), and 7-cyclohexyl-1-heptyl phosphocholine (CyF)] via 1H NMR spectroscopy. For each temperature and pressure point, the critical micelle concentration (cmc) was obtained from a single 1H NMR spectrum at a single intermediate concentration by referencing the observed chemical shift to those of pure monomer and pure micellar phases. This permitted rapid measurements of the cmc over a range of temperatures and pressures. In all cases, micelle formation was strongly entropically favored, while enthalpy changes were all positive, with the exception of SDS, which exhibited a modestly negative enthalpy of micellization. Heat capacity changes were also characteristically negative, while partial molar volume changes were uniformly positive, as expected for an aggregation process dictated by hydrophobic effects. Isothermal compressibility changes were found to be consistent with previous measurements using other techniques. Thermodynamic measurements were also related to spectroscopic studies of topology and micelle structure. For example, paramagnetic effects resulting from the addition of dioxygen provided microscopic topological details concerning the hydrophobicity gradient along the detergent chains within their respective micelles as detected by 1H NMR. In a second example, combined 13C and 1H NMR chemical shift changes arising from application of high pressure, or upon micellization, of CyF provided site-specific details regarding micelle topology. In this fashion, bulk thermodynamics could be related to microscopic topological details within the detergent micelle. © 2014 American Chemical Society. Source

Higgins V.,Pediatric Laboratory Medicine | Higgins V.,University of Toronto | Chan M.K.,Pediatric Laboratory Medicine | Nieuwesteeg M.,Pediatric Laboratory Medicine | And 6 more authors.
Clinical Biochemistry | Year: 2016

Objectives: The Canadian Laboratory Initiative on Pediatric Reference Intervals (CALIPER) has recently established pediatric age- and sex-specific reference intervals for over 85 biochemical markers on the Abbott Architect system. Previously, CALIPER reference intervals for several biochemical markers were successfully transferred from Abbott assays to Roche, Beckman, Ortho, and Siemens assays. This study further broadens the CALIPER database by performing transference and verification for 52 biochemical assays on the Roche cobas 6000 and the Roche Modular P. Design and methods: Using CLSI C28-A3 and EP9-A2 guidelines, transference of the CALIPER reference intervals was attempted for 16 assays on the Roche cobas 6000 and 36 on the Modular P. Calculated reference intervals were further verified using 100 healthy CALIPER samples. Results: Most assays showed strong correlation between assay systems and were transferable from Abbott to the Roche cobas 6000 (81%) and the Modular P (86%). Bicarbonate and magnesium were not transferable on either system and calcium and prealbumin were not transferable to the Modular P. Of the transferable analytes, 62% and 61% were verified on the cobas 6000 and the Modular P, respectively. Conclusions: This study extends the utility of the CALIPER database to two additional analytical systems, which facilitates the broad application of CALIPER reference intervals at pediatric centers utilizing Roche biochemical assays. Transference studies across different analytical platforms can later be collectively analyzed in an attempt to develop common reference intervals across all clinical chemistry instruments to harmonize laboratory test interpretation in diagnosis and monitoring of pediatric disease. © 2015 The Canadian Society of Clinical Chemists. Source

Kaths J.M.,Multi Organ Transplant Program | Spetzler V.N.,Multi Organ Transplant Program | Goldaracena N.,Multi Organ Transplant Program | Echeverri J.,Multi Organ Transplant Program | And 11 more authors.
Journal of Visualized Experiments | Year: 2015

Kidney transplantation has become a well-established treatment option for patients with end-stage renal failure. The persisting organ shortage remains a serious problem. Therefore, the acceptance criteria for organ donors have been extended leading to the usage of marginal kidney grafts. These marginal organs tolerate cold storage poorly resulting in increased preservation injury and higher rates of delayed graft function. To overcome the limitations of cold storage, extensive research is focused on alternative normothermic preservation methods. Ex vivo normothermic organ perfusion is an innovative preservation technique. The first experimental and clinical trials for ex vivo lung, liver, and kidney perfusions demonstrated favorable outcomes. In addition to the reduction of cold ischemic injury, the method of normothermic kidney storage offers the opportunity for organ assessment and repair. This manuscript provides information about kidney retrieval, organ preservation techniques, and isolated ex vivo normothermic kidney perfusion (NEVKP) in a porcine model. Surgical techniques, set up for the perfusion solution and the circuit, potential assessment options, and representative results are demonstrated. © 2015 Creative Commons Attribution-NonCommercial License. Source

Kaths J.M.,Toronto General Hospital | Echeverri J.,Toronto General Hospital | Echeverri J.,Autonomous University of Barcelona | Goldaracena N.,Toronto General Hospital | And 8 more authors.
Journal of Visualized Experiments | Year: 2016

Kidney transplantation is the treatment of choice for patients suffering from end-stage renal disease. It offers better life expectancy and higher quality of life when compared to dialysis. Although the last few decades have seen major improvements in patient outcomes following kidney transplantation, the increasing shortage of available organs represents a severe problem worldwide. To expand the donor pool, marginal kidney grafts recovered from extended criteria donors (ECD) or donated after circulatory death (DCD) are now accepted for transplantation. To further improve the postoperative outcome of these marginal grafts, research must focus on new therapeutic approaches such as alternative preservation techniques, immunomodulation, gene transfer, and stem cell administration. Experimental studies in animal models are the final step before newly developed techniques can be translated into clinical practice. Porcine kidney transplantation is an excellent model of human transplantation and allows investigation of novel approaches. The major advantage of the porcine model is its anatomical and physiological similarity to the human body, which facilitates the rapid translation of new findings to clinical trials. This article offers a surgical step-by-step protocol for an autotransplantation model and highlights key factors to ensure experimental success. Adequate pre- and postoperative housing, attentive anesthesia, and consistent surgical techniques result in favorable postoperative outcomes. Resection of the contralateral native kidney provides the opportunity to assess post-transplant graft function. The placement of venous and urinary catheters and the use of metabolic cages allow further detailed evaluation. For long-term follow-up studies and investigation of alternative graft preservation techniques, autotransplantation models are superior to allotransplantation models, as they avoid the confounding bias posed by rejection and immunosuppressive medication. © 2016 Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. Source

Park M.S.,Staff Paediatric Dentist | Tenenbaum H.C.,University of Toronto | Dror Y.,Laboratory Medicine and Pathobiology | Dror Y.,University of Manitoba | And 3 more authors.
Special Care in Dentistry | Year: 2014

The purpose of this cross-sectional study was to assess and compare the oral health of children with neutropenia, who are under the active care of a hematologist in a designated marrow failure and myelodysplasia program, to a healthy control group. Children aged 6-18 with neutropenia attending the Marrow Failure and Myelodysplasia Program at SickKids Hospital and controls attending the Children's Clinic, Faculty of Dentistry, University of Toronto were asked to participate in the study consisting of a patient questionnaire followed by a dental and radiographic examination. Fifteen patients with neutropenia (mean age 12.14 ± 4.04 years) and 26 healthy controls (mean age 11.61 ± 3.82 years) participated in this study. Patients with neutropenia reported significantly increased mouth sores (p <.008) and bleeding gums while brushing (p <.001). The dmft/t score was significantly lower for the neutropenia group (p <.009). The clinical examination also showed that there were no statistically significant differences with respect to ulcerations, gingival recession, tooth mobility, gingival inflammation, periodontal bone loss, DMFT/T scores, plaque, and calculus levels. Preliminary data demonstrates that pediatric patients who are under the active care of a hematologist do not present with an increased risk of oral diseases. ©2012 Special Care Dentistry Association and Wiley Periodicals, Inc. Source

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