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991.
The paper deals with the hydrodynamics of artificial heart valves (AHVs) used in clinical practice. It reviews and analyzes the studies of AHV hydrodynamics, as well as the hydrodynamic beds which stimulate physiological flow through the valve. Photochronic imaging (PCI) is proposed for examination of AHV hydrodynamic characteristics under model physiological flow. The hydrodynamics of different AHVs was tested on the beds simulating blood flow through AHVs by employing PCI. PCI involved preparation of model photochronic solution that simulates blood, colour labels by using laser radiation. In the model photochronic solution, 10(-6)-10(-9)-sec laser radiation gave rise to linear colour labels whose movement was recorded by a speed camera in the flow behind the valve. The profiles of speed behind the valves, the dimensions of congestive areas, the positions of flow detachment and regurgitation flow were calculated by a speed shooting in different periods of valvular performance. PCI defined congestive areas behind the valves, the areas of closed circulations, the sizes of reversing flow areas and examined the time course of flow behind the valves as a whole. The paper is of interest for AHV designers and cardiac surgeons who apply various AHVs. 相似文献
992.
AG Ferreira Zandoná M Analoui BB Beiswanger RL Isaacs AH Kafrawy GJ Eckert GK Stookey 《Canadian Metallurgical Quarterly》1998,32(3):210-218
Metabolism of xenobiotics such as alcohol and organic solvents can be divided roughly into two types: functional and conjugation reactions. Cytochrome P450 (CYP) is the primary group of enzymes involved in the former. Therefore, CYP analysis is essential for the study of the metabolism and toxicity of these chemicals. Of the isozymes, CYP2E1 is a low-km isozyme and has a high affinity for volatile hydrocarbons of low molecular mass, and is primarily involved in the metabolism of alcohol and organic solvents. There are many methods for analysis of CYPs including CYP2E1. The measurement of the metabolic rate of the target chemical in the liver is the most common. When combined with monoclonal or polyclonal antibody to CYP, contribution of the isozymes to the metabolism can be resolved, and the expression level is also identified by western blot analysis. The use of the reconstituted system of purified CYP isozymes is useful to determine the true activity (specific activity), but not common especially in that of human tissue. There are sometimes species differences in the enzymatic character of CYP isoforms, which causes difficulties in extrapolating to humans. In these case, the use of a cDNA expression system of human CYPs can cover the difficulties. The use of transgenic animals can answer the contribution of each CYP isoform in the in vivo metabolism and toxicity. The genotype of each isozyme is analyzed by PCR method, which can identify the polymorphism as well as the susceptibility to the chemicals. 相似文献
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996.
HJ Broxterman P Sonneveld N Feller GJ Ossenkoppele DC W?hrer CA Eekman M Schoester J Lankelma HM Pinedo B L?wenberg GJ Schuurhuis 《Canadian Metallurgical Quarterly》1996,87(11):4809-4816
We have compared multiple assays for the P-glycoprotein (Pgp/MDR1) phenotype in fresh and thawed adult acute leukemia to validate and quantitate measures for the expression and function of Pgp. The results are related to the Pgp-expressing KB8 and KB8-5 call lines. The most sensitive assay was the measurement of modulation of the rhodamine 123 (R123) fluorescence by 2 micromol/L PSC833, followed by the modulation of the probe calcein-AM. We also found a good intralaboratory and interlaboratory correlation between the values of the R123/PSC833 assay for fresh as well as thawed samples. In addition, the affects of PSC833 on 3H-daunorubicin (DNR) accumulation, DNR fluorescence, and 3H-vincristine accumulation were very similar. The correlation between the DNR/PSC833 and R123/PSC833 test was r = .86 (N = 51). The modulation of drug accumulation by 8 micromol/L verapamil was the some as the PSC833 effect for DNR (117%, N = 21), but was higher for vincristine in every single case (161% v 121%, N = 22; P< .001), indicating additional verapamil effects, not related to Pgp. The correlation of the staining of viable cells for Pgp with the monoclonal antibody MRK16 was r = .77 (N = 52) for the R123/PSC833 functional test and r = .84 (N = 50) for the DNR/PSC833 test. From these results it could be calculated that a maximal increase of the mean DNR accumulation of about 50% can be achieved by blocking Pgp pump activity with PSC833 in leukemic blast samples with the highest mean Pgp expression. Subpopulations of blast calls with higher Pgp activity are likely to be present. Their relevance has to be studied further. The methods outlined here allow the reliable, quantitative monitoring of the Pgp/MDR1 phenotype in leukemias in multicentered, clinical Pgp modulation studies. 相似文献
997.
998.
RJ Hamill ED Houston PR Georghiou CE Wright MA Koza RM Cadle PA Goepfert DA Lewis GJ Zenon JE Clarridge 《Canadian Metallurgical Quarterly》1995,122(10):762-766
OBJECTIVE: To investigate an outbreak of Burkholderia (formerly Pseudomonas) cepacia respiratory tract colonization and infection in mechanically ventilated patients. DESIGN: A retrospective case-control and bacteriologic study. SETTING: Veterans Affairs medical center. PATIENTS: 42 mechanically ventilated patients who developed respiratory tract colonization or infection with B. cepacia and 135 ventilator-dependent controls who were not colonized and did not develop infections. MEASUREMENTS: Clinical and demographic data; benzalkonium chloride concentrations and pH levels in albuterol sulfate solutions; repetitive-element polymerase chain reaction (PCR)-mediated molecular fingerprinting on eight patient isolates and three environmental B. cepacia isolates that were available for study. RESULTS: 42 patients had B. cepacia respiratory tract colonization or infection. Observation of intensive care unit and respiratory care personnel showed faulty infection control procedures (for example, the same multiple-dose bottle of albuterol was used for many mechanically ventilated patients). More case patients (39 [92.9%]) than controls (95 [70.4%]; P = 0.006) received nebulized albuterol, and case patients (67.5 treatments) received more treatments than controls (18 treatments; P < 0.001). In-use albuterol solutions had pH values that were unstable, and benzalkonium chloride concentrations declined over time to levels capable of supporting bacterial growth. Medication nebulizers and in-use bottles of albuterol harbored B. cepacia. Molecular fingerprints of patient isolates and environmental B. cepacia isolates were identical using repetitive-element PCR. No further isolates of B. cepacia were identified after institution of appropriate infection control procedures. CONCLUSIONS: Multiple-dose medications and reliance on benzalkonium chloride as a medication preservative provide a mechanism for nosocomial spread of microorganisms, particularly if infection control procedures are not carefully followed. Repetitive-element PCR is a useful fingerprinting technique for molecular epidemiologic studies of B. cepacia. 相似文献
999.
1000.
MV Soghikian VG Valentine GJ Berry HR Patel RC Robbins J Theodore 《Canadian Metallurgical Quarterly》1996,15(9):881-887
BACKGROUND: Cytomegalovirus infection threatens pulmonary allograft survival and function. This retrospective study details the experience of ganciclovir prophylaxis against cytomegalovirus infection and its sequelae. METHODS: Eight-nine lung and heart-lung transplant recipients with positive cytomegalovirus serology were analyzed. The 37 recipients who underwent transplantation before September 1989 received no prophylaxis. The 52 subsequent recipients received ganciclovir prophylaxis. RESULTS: Thirty-six non-prophylaxed versus 42 prophylaxed patients had cytomegalovirus events with cumulative incidences of 100% and 86% (p < < 0.01), and median onsets of 37 +/- 21 versus 85 +/- 35 days, respectively (p < < 0.01); 22 non-prophylaxed versus 27 prophylaxed patients had cytomegalovirus pneumonitis with cumulative incidences of 60% and 55% (p < < 0.01), and median onsets of 34 +/- 14 and 84 +/- 26 days, respectively (p < < 0.01). Respiratory failure caused by cytomegalovirus pneumonitis developed in nine of the non-prophylaxed versus two of the prophylaxed patients (p < < 0.01). The significant estimated survival benefit in patients who received prophylaxis (p = 0.04) was not apparent when reanalysis was performed after exclusion of patients with respiratory failure (p = 0.36). Ganciclovir prophylaxis produced a significant delay in the development of obliterative bronchiolitis with a median time to onset of 1072 +/- 280 days versus 432 +/- 189 days for the non-prophylaxis cohort (p < < 0.01). CONCLUSIONS: Ganciclovir prophylaxis (1) improves recipient survival by reducing the severity of disease and essentially eliminating respiratory failure caused by cytomegalovirus pneumonitis, (2) reduces the incidence and delays the onset of cytomegalovirus events and pneumonitis, and (3) delays the onset of obliterative bronchiolitis. 相似文献