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Applied and Environmental Microbiology (1)
Canadian Journal of Veterinary Research (1)
Journal of Epidemiology and Community Health (1)
Plante, C (2)
Baudouin, Y (1)
Fournier, M (1)
Goldberg, M S (1)
King, G. M. (1)
Kosatsky, T (1)
Mayer, L. M. (1)
Miller, R B (1)
O'Brien, P J (1)
Plante, C. J. (1)
Rosendal, S (1)
Ruhnke, H L (1)
Smargiassi, A (1)
Smits, B (1)
Year of Publication
Variation of daily warm season mortality as a function of micro-urban heat islands
Goldberg, M S
Journal of Epidemiology and Community Health
Little attention has been paid to how heat-related health effects vary with the micro-urban variation of outdoor temperatures. This study explored whether people located in micro-urban heat islands are at higher risk of mortality during hot summer days.
Data used included (1) daily mortality for Montreal (Canada) for June–August 1990–2003, (2) daily mean ambient outdoor temperatures at the local international airport and (3) two thermal surface images (Landsat satellites, infrared wavelengths). A city-wide temperature versus daily mortality function was established on the basis of a case-crossover design; this function was stratified according to the surface temperature at decedents’ place of death.
The risk of death on warm summer days in areas with higher surface temperatures was greater than in areas with lower surface temperatures.
This study suggests that measures aimed at reducing the temperature in micro-urban heat islands (eg, urban greening activities) may reduce the health impact of hot temperatures. Further studies are needed to document the variation of heat-related risks within cities and to evaluate the health benefits of measures aimed at reducing the temperature in micro-urban heat islands.
The Kinetics of Bacteriolysis in the Gut of the Deposit Feeder Arenicola marina
Mayer, L. M.
King, G. M.
Applied and Environmental Microbiology
A turbidimetric technique was used to measure the bacteriolytic activities of digestive fluids collected seasonally from the deposit-feeding polychaete Arenicola marina. Lysis of cultured sedimentary bacteria was monitored spectrophotometrically. The kinetics of the lytic reaction were characterized with respect to temperature, pH, reactant concentration, and time. Bacteriolysis generally followed saturation kinetics behavior and was apparently a first-order process with respect to the substrate (bacteria). Deviation from a simple Michaelis-Menten relationship, however, was observed at high substrate levels, at which inhibition of lysis was evident. The lytic rate decreased rapidly and sharply through time as the substrate was depleted. Lytic factors in the gut fluid acted as catalysts; rates increased with concentration of gut fluid, but no depletion in lytic capacity through time was observed. The lytic rate increased exponentially for all seasonal samples over the range of environmental temperatures (4 to 31(deg)C) but showed little relationship with pH under conditions likely to be experienced in situ. The lytic rate also varied among bacterial strains and with culture age.
Effects of Ureaplasma diversum on bovine oviductal explants: quantitative measurement using a calmodulin assay.
Ruhnke, H L
O'Brien, P J
Miller, R B
Canadian Journal of Veterinary Research
Calmodulin (CAM) acts as an intracellular regulator of calcium, an important mediator of many cell processes. We used the CAM assay and electron microscopy to investigate the effects of Ureaplasma diversum on bovine oviductal explants obtained aseptically from slaughtered cows. A stock suspension of U. diversum (treated specimens) and sterile broth (controls) was added to replicates of cultured explants and incubated at 38 degrees C in an atmosphere of 5.5% CO2 for 48 hours. Explants were examined for ciliary activity, extracellular CAM loss, and for histological and ultrastructural changes. Explants and their culture media were examined for changes in CAM concentration. All experiments were replicated three times. In addition, U. diversum, medium and broth were assayed for CAM content. The concentrations of CAM in explants and media changed significantly (p < 0.05) in samples which were inoculated with U. diversum when compared to controls. The controls and infected specimens did not differ histologically or ultrastructurally, but U. diversum was seen to be closely associated with infected explant tissue. In view of this close affinity it is assumed the loss of CAM from the oviductal cells was causally related, but this was not proven. The failure to show cell membrane injury on light and electron microscopic examination was probably related to the short duration of the experiment and may only point out the sensitivity of the CAM assay in detecting early cell membrane injury. Compromise in characteristics of the medium to support both, the viability of oviductal cells and U. diversum limited the experimental time to 48 hours.(ABSTRACT TRUNCATED AT 250 WORDS)
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