A magnetically focused molecular beam source for deposition of spin-polarised molecular surface layers.

Separating molecular spin isomers is a challenging task, with potential applications in various fields ranging from astrochemistry to magnetic resonance imaging. A new promising method for spin-isomer separation is magnetic focusing, a method which was shown to be capable of producing a molecular beam of ortho-water. Here, we present results from a modified magnetic focusing apparatus and show that it can be used to separate the spin isomers of acetylene and methane. From the measured focused profiles of the molecular beams and a numerical simulation analysis, we provide estimations for the spin purity and the significantly improved molecular flux obtained with the new setup. Finally, we discuss the spin-relaxation conditions which will be needed to apply this new source for measuring nuclear magnetic resonance signals of a single surface layer.

Hospitalizations associated with salmonellosis among seniors in Canada, 2000-2010.

Salmonella is one of the most prevalent bacteria associated with enteric illness in Canada and seniors are considered a vulnerable population more likely to develop severe illness. In the coming decades, hospitalizations and deaths associated with Salmonella in seniors could represent a challenge due to an aging population in Canada. The numbers of non-typhoidal (NT) Salmonella-related hospitalizations from the Canadian Hospitalization Morbidity Database were analysed for a period of 10 years for seniors. Hospitalization rate calculations and descriptive analyses were performed on variables associated with the burden of hospitalization and compared with the adult age group. Estimates of hospitalizations and deaths associated with domestically acquired Salmonella (accounting for under-reporting) were also calculated. This study found that 50% of the NT Salmonella-related hospitalization and 82% of the deaths recorded in the Canadian adult population occurred in seniors. The length of hospitalization stay was also longer in seniors (7 days) than other adults (4 days). We estimated that each year, 535 hospitalizations and 27 deaths are related to domestically acquired Salmonella in seniors. Senior populations represent a substantial percentage of Salmonella-related hospitalizations and deaths in Canada and the burden associated with those hospitalizations is also greater. This should be considered when developing estimates of medical costs and implementing prevention activities.

Intuitive wireless control of a robotic arm for people living with an upper body disability.

Assistive Technologies (ATs) also called extrinsic enablers are useful tools for people living with various disabilities. The key points when designing such useful devices not only concern their intended goal, but also the most suitable human-machine interface (HMI) that should be provided to users. This paper describes the design of a highly intuitive wireless controller for people living with upper body disabilities with a residual or complete control of their neck and their shoulders. Tested with JACO, a six-degree-of-freedom (6-DOF) assistive robotic arm with 3 flexible fingers on its end-effector, the system described in this article is made of low-cost commercial off-the-shelf components and allows a full emulation of JACO's standard controller, a 3 axis joystick with 7 user buttons. To do so, three nine-degree-of-freedom (9-DOF) inertial measurement units (IMUs) are connected to a microcontroller and help measuring the user's head and shoulders position, using a complementary filter approach. The results are then transmitted to a base-station via a 2.4-GHz low-power wireless transceiver and interpreted by the control algorithm running on a PC host. A dedicated software interface allows the user to quickly calibrate the controller, and translates the information into suitable commands for JACO. The proposed controller is thoroughly described, from the electronic design to implemented algorithms and user interfaces. Its performance and future improvements are discussed as well.

Growth of acanthamoeba on human corneal epithelial cells and keratocytes in vitro.

Acanthamoebic keratitis, a potentially devastating infection usually associated with contact lens wear, has been recognized with increasing frequency in recent years. Once the Acanthamoeba organisms gain access to the human cornea, it is not clear which constituents of the corneal milieu provide a substrate for their growth. The growth of Acanthamoeba polyphaga was investigated on cultured monolayers of human corneal epithelial cells, stromal keratocytes, and stromal homogenate suspensions. Growth was determined through organism counts and observation of cytopathic effects on tissue culture dishes. Compared with tissue culture media controls, acanthamoebic growth was supported by cultured epithelial cells and keratocytes but not stromal homogenates. These results suggest that in acanthamoebic keratitis the organisms depend on the cellular components of the cornea as substrates for growth. This in vitro model may also provide further information on the pathogenesis of keratitis and a system for drug sensitivity testing.

Indications for keratoepithelioplasty.

Thirteen patients with ocular surface failure were treated by keratoepithelioplasty using allografts of corneal limbal epithelial cells from donor eyes. The ocular surface was stabilized with long-term healing of persistent epithelial defects in five of eight eyes followed up for 4 to 19 months. The procedure was performed on an additional 5 patients with superficial keratopathies. Three of those five procedures resulted in a stable and clear optical surface. These results suggest that epithelial transplantation may be a useful option in the care of chronic ocular surface failure unresponsive to conventional medical management.

Successful treatment of Pseudomonas meningitis and septicemia in a leukemic neutropenic adult.

Pseudomonas aeruginosa is thought to be one of the main species of bacteria producing infection in leukemic patients, especially in those with neutropenia. Although bacteremia is frequent, hematogenous spread causing secondary meningitis is rarely seen. The mortality rate is extremely high. This is believed to be the first report of a successfully treated secondary meningitis caused by Pseudomonas aeruginosa in an adult leukemic patient with a decreased neutrophil count. The patient was treated with intravenous Carbenicillin and gentamicin, and intrathecal gentamicin. The good clinical response was supported by a prompt return of the CSF to normal and by appropriate CSF antimicrobial concentration and bacteriostatic activity.

Biologic activity of metronidazole in plasma and urine of volunteers with normal or impaired renal function.

In this study, we have compared a bioassay procedure with high-pressure liquid chromatography (HPLC) for the determination of metronidazole levels in serum and urine. Plasma and urine of volunteers with normal or impaired renal function were obtained at various intervals after a single intravenous dose of 500 mg metronidazole. In plasma of normal volunteers 30 hours after dosing, the bioassay gave results comparable to the total values of the parent compound plus metabolites. In patients with renal failure, the course of the plasma regression curve of metronidazole as measured by the bioassay procedure was intermediate between the values of metronidazole alone and the total values of parent compound plus metabolites. Recovery of metronidazole activity in urine, as determined by this bioassay method, was somewhat less than one half (in normal volunteers) to one quarter (in patients with renal failure) of metronidazole plus metabolites as measured by HPLC. These discrepancies might be explained by the lower antibacterial activity of the hydroxy (congruent to 40%) and acetic acid (congruent to 2%) metabolites as compared with that of the parent compound in the test system used.

Management of intra-abdominal infections. The case for intraoperative cultures and comprehensive broad-spectrum antibiotic coverage. The Canadian Intra-abdominal Infection Study Group.

OBJECTIVE: To test the hypothesis that comprehensive broad-spectrum empirical antimicrobial therapy is superior to limited-spectrum empirical antimicrobial therapy in intra-abdominal infections. DESIGN: Prospective, randomized, double-blinded study. SETTING: University-affiliated hospitals in Canada. PATIENTS: Two hundred thirteen patients with intra-abdominal infections and planned operative or percutaneous drainage. INTERVENTION: Limited-spectrum empirical antimicrobial therapy consisted of cefoxitin sodium, 2 g, intravenously, every 6 hours (n = 109). Comprehensive broad-spectrum empirical antimicrobial therapy consisted of a combination of imipenem and cilastatin sodium, 500 mg, intravenously, every 6 hours (n = 104). MAIN OUTCOME MEASURES: Failure to cure the intra-abdominal infection (persistence of infection or death). RESULTS: Of initial isolates, 98% were sensitive to imipenem plus cilastin sodium compared with 72% for cefoxitin. No difference was found in the failure rate between treatment groups. Among various reasons for failure (including technical), 12 of 80 patients in the limited-spectrum empirical antimicrobial therapy group had resistant organisms at a second intervention compared with 1 of 74 in the comprehensive broad-spectrum empirical antimicrobial therapy group (P < .003, chi 2). One death in the limited-spectrum empirical antimicrobial therapy group was due to autopsy-proved disseminated Pseudomonas aeruginosa (blood, peritoneum, lung, and pleural fluid) that was resistant to cefoxitin, and the other was associated with peritonitis due to cefoxitin-resistant Enterobacter cloacae. One death in the comprehensive broad-spectrum empirical antimicrobial therapy group was associated with peritonitis from Clostridium perfringens that was sensitive to imipenem plus cilastin sodium, and the other was associated with peritonitis from Pseudomonas aeruginosa that was resistant to imipenem plus cilastin sodium. CONCLUSION: Treatment failure of intra-abdominal infection may be due, in part, to the presence of resistant pathogens at the site of infection. Therefore, routine culture of these sites seems worthwhile and empirical therapy should be as comprehensive as possible and should cover all potential pathogens.

Aprotinin treatment of pseudomonal corneal infection.

Pseudomonas aeruginosa produces proteolytic enzymes capable of causing severe corneal degradation. In this study we tested aprotinin, a broad-spectrum protease inhibitor, on rabbit corneas infected with P. aeruginosa to determine whether any benefit could be derived. Corneas treated with aprotinin and tobramycin topically and subconjunctivally were not clinically better than corneas treated with tobramycin alone.

Survival of Acanthamoeba in contact lens rinse solutions.

Acanthamoeba may cause a severe keratitis in contact lens wearers. Since most sterilization techniques require rinsing the lenses prior to insertion, contaminated solutions represent a potential vector for transmission of Acanthamoeba. The ability of rinse solutions to sustain an inoculum of Acanthamoeba polyphaga was investigated. A. polyphaga was exposed to 0.1% benzalkonium chloride, 0.001% thimerosal/0.1% edetate disodium, 0.1% edetate disodium, saline, tap water, and distilled water. The status of the organism was evaluated with direct microscopic counts and cultures to confirm viability. Incubation with 0.1% edetate disodium, saline, tap water, and distilled water resulted in the maintenance of reduced populations of viable organisms for 7 days. Benzalkonium chloride preserved saline and solutions containing thimerosal with edetate rendered the Acanthamoeba nonviable.

A prospective randomized trial of imipenem-cilastatin versus clindamycin/tobramycin in the treatment of intra-abdominal and pelvic infections.

OBJECTIVE: A Canadian multicentre clinical trial in the treatment of intra-abdominal and pelvic infections to compare the efficacy and safety of monotherapy using imipenem-cilastatin (imipenem) (500 mg intravenously every 6 h) versus combination therapy with clindamycin/tobramycin (clindamycin 600 mg intravenously every 6 h and tobramycin 1.7 mg/kg intravenously every 8 h). METHODS: Two hundred and fifty patients were entered (88 definite and 162 possible infections) and all were evaluable for analysis of adverse events and intention to treat analysis of efficacy. Dichotomous outcomes used were: cured versus noncured (improved, failed, relapsed). RESULTS: No statistically significant differences were found with the intention to treat analysis (P=0.88) or with definite infections (P=0.81). For overall bacteriological response, no significant differences were noted (P=0.1). Eleven and 15 patients on imipenem and clindamycin/tobramycin, respectively, were colonized with bacteria. Enterococci colonized four of 11 imipenem cases and five of 15 clindamycin/tobramycin cases while fungi colonized six patients on imipenem and four on clindamycin/tobramycin. Five patients on imipenem and seven on clindamycin/tobramycin developed superinfection. In the imipenem group, one case had a bacterial superinfection while four cases were due to Candida albicans. Seven of seven superinfections on clindamycin/tobramycin were bacterial. Three bacteria initially sensitive to the assigned study drug developed resistance. In two patients on imipenem, Enterococcus faecalis and Pseudomonas aeruginosa became resistant after 14 and 10 days of therapy, respectively. On clindamycin/tobramycin, one instance of Bacteroides fragilis resistance after eight days of therapy was seen. Eighty-three adverse events occurred; 47 in the imipenem group and 36 in the clindamycin/tobramycin group. This resulted in discontinuation of antibacterial therapy in 13 patients, seven of whom were on imipenem and six on clindamycin/tobramycin. Comparison of adverse effects showed statistically significant differences for nausea (P=0.02) and hepatotoxicity (P=0.05) occurring with greater frequency in the imipenem and clindamycin/tobramycin groups, respectively. CONCLUSIONS: These data support the conclusion that monotherapy with imipenem (500 mg intravenously every 6 h) is as efficacious as clindamycin/tobramycin for treatment of intra-abdominal and pelvic infections. Both regimens are well tolerated.

A complication of BCG vaccine: A case of localized cutaneous abscess due to Mycobacterium bovis.

The attenuated bacille Calmette-Guérin (BCG) vaccine is administered to prevent tuberculosis. Complications of vaccination are uncommon. A case of cutaneous abscess due to BCG is presented in a 24-year-old woman. The abscess developed at the inoculation site four weeks after vaccination. Routine Gram stain and bacterial cultures of the pus were negative. The auramine stain was positive. Mycobacterial cultures were positive after 14 and 18 days, using the BACTEC 12B bottle and Löwenstein-Jensen media, respectively. The mycobacteria were identified as Mycobacterium bovis, vaccinal strain by high-performance liquid chromatography and DNA probe assays.

Summary: Assessing the public health risks of microbial contamination in recreational waters by satellite imagery.

BACKGROUND: Fecal contamination of recreational waters may lead to gastroenteritis, respiratory infections, dermatitis and ear infections. In addition to directly testing waters for contamination, the World Health Organization (WHO) recommends the assessment of environmental factors known to influence water quality as part of monitoring efforts. Measurement of these factors using satellite imagery may be helpful in Canada where monitoring over large areas or difficult to access locations is needed. OBJECTIVE: To assess the added value of using satellite imagery as part of monitoring and managing microbial risks associated with recreational waters in Canada. METHODS: Satellite images were used to calculate five environmental indices that may affect the risk of contamination of recreational waters: agricultural land, urban areas (impervious surfaces), forest and wetlands. Statistical models including these indices were then compared with the average contamination level of beaches in southern Quebec, Canada. Various satellite sensors were compared against criteria of accuracy and performance. OUTCOMES: Satellite imagery classification performed well for the study area. Two of the variables were significantly associated with higher coliform levels: agricultural land and urban areas. In the context of this assessment, the Landsat-5 sensor offered the best cost-benefit ratio. CONCLUSION: Satellite imagery can be used to identify environmental factors associated with a higher risk of fecal contamination of recreational waters in Canada and may supplement current monitoring and risk assessment efforts.

Agroenvironmental determinants associated with the presence of antimicrobial-resistant Escherichia coli in beach waters in Quebec, Canada.

Exposure to microorganisms resistant to antimicrobials may constitute a health risk to human populations. It is believed that one route of exposure occurs when people engage in recreational activities in water contaminated with these microorganisms. The main objective of this study was to explore population-level and environmental determinants specifically associated with the presence of antimicrobial resistant (AMR) generic Escherichia coli isolated from recreational waters sampled from beaches located in southern Quebec, Canada. Water samples originated from the Quebec provincial beach surveillance program for the summers of 2004 and 2005. This study focused on three classes of determinants, namely: agricultural, population-level and beach characteristics for a total of 19 specific factors. The study was designed as a retrospective observational analysis and factors were assessed using logistic regression methods. From the multivariable analysis, the data suggested that the percentage of land used for spreading liquid manure was a significant factor associated with the presence of AMR E. coli (OR=27.73). Conceptually, broad factors potentially influencing the presence of AMR bacteria in water must be assessed specifically in addition to factors associated with general microbial contamination. Presence of AMR E. coli in recreational waters from beaches in southern Quebec may represent a risk for people engaging in water activities and this study provides preliminary evidence that agricultural practices, specifically spreading liquid manure in agricultural lands nearby beaches, may be linked to the contamination of these waters by AMR E. coli.

Screening of Neisseria gonorrhoeae for tolerant response to beta-lactam antibiotics.

Minimal inhibitory concentrations (MICs) and minimal bactericidal concentrations (MBCs) of penicillin, ampicillin, cefoxitin, and cefuroxime were determined for 103 beta-lactamase-negative Neisseria gonorrhoeae clinical isolates belonging to five different auxotypes. MBC determinations were base on killing 99.9% of the inoculum after 24 h of incubation. The MBC/MIC ratio was less than or equal to 8 for ampicillin, cefoxitin, and cefuroxime in all 103 strains. Two isolates which were very susceptible to penicillin (MIC, less than or equal to 0.015 micrograms/ml) had MBCs which were considerably greater than the MICs (MBC/MIC ratios, 32 and 64) for penicillin. A beta-lactamase-negative resistant subpopulation having the same auxotype as the total population was isolated from each of these two strains. Killing curve studies were in agreement with the existence of susceptible and resistant subpopulations, which may explain the high MBC/MIC ratios.

Auxotypes of Neisseria gonorrhoeae isolated from localized and disseminated infections in Montreal.

A survey recently made in the United States on the regional distribution of auxotypes of Neisseria gonorrhoeae suggested that isolates from different geographic areas often differ in auxotype. A subsequent auxotyping study in Montreal of 901 isolates of N. gonorrhoeae, 15 from patients with disseminated gonococcal infection, proved interesting in many regards. Gonococcal genetic medium, modified by the addition of other amino acids, was used. Most (93%) of the strains isolated from patients with localized infection belonged to one of the following three phenotypes: arginine-, hypoxanthine- and uracil-dependent (44%); prototrophic (33%); and proline-dependent (16%). Of the 15 strains responsible for disseminated infection 14 required arginine, hypoxanthine and uracil for growth.

Stability of imipenem in Mueller-Hinton agar stored at 4 degrees C.

The purpose of the present study was to measure the stability of imipenem in Mueller-Hinton agar stored at 4 degrees C over time. MICs for Staphylococcus aureus ATCC 25923, Streptococcus faecalis ATCC 29212, Escherichia coli ATCC 25922, and Pseudomonas aeruginosa ATCC 27853 were determined in triplicate daily for up to 15 days. The calculated mean time to observe a shift of one dilution in MIC endpoints was 4.33 +/- 1.25 days. For routine work, imipenem agar dilution plates should be prepared within 48 to 72 h of the test.