Stability of antimycobacterial drugs in susceptibility testing.
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Aqueous solutions of 0.02% isoniazid, 0.2% streptomycin, 0.2% para-aminosalicylate, and 0.5% ethambutol and ethylene glycol solutions of 0.5% ethionamide stored at 3 to 7 degrees C remained stable for 1 year, as did aqueous solutions of 0.05% ethionamide hydrochloride, 0.05% kanamycin, 0.05% viomycin, and 0.1% capreomycin stored at -20 degrees C. The ethambutol and capreomycin solutions were tested by microbiologic methods; the other solutions were tested by both spectrophotometric and microbiologic methods. Prepared susceptibility testing media made with cycloserine, rifampin, and the above solutions incorporated into Middlebrook 7H10 medium showed acceptable stability when stored at 3 to 7 degrees C for 1 month. During incubation of the test medium at 37 degrees C, approximately half of the activity of isoniazid, ethionamide, ethambutol, cycloserine, and rifampin was lost after periods ranging from 2 to 4 days for ethambutol to 2 weeks for rifampin. (+info)
Hepatitis B vaccine freezing in the Indonesian cold chain: evidence and solutions.
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OBJECTIVES: To document and characterize freezing temperatures in the Indonesian vaccine cold chain and to evaluate the feasibility of changes designed to reduce the occurrence of freezing. METHODS: Data loggers were used to measure temperatures of shipments of hepatitis B vaccine from manufacturer to point of use. Baseline conditions and three intervention phases were monitored. During each of the intervention phases, vaccines were removed progressively from the standard 2-8 degrees C cold chain. FINDINGS: Freezing temperatures were recorded in 75% of baseline shipments. The highest rates of freezing occurred during transport from province to district, storage in district-level ice-lined refrigerators, and storage in refrigerators in health centres. Interventions reduced freezing, without excessive heat exposure. CONCLUSIONS: Inadvertent freezing of freeze-sensitive vaccines is widespread in Indonesia. Simple strategies exist to reduce freezing - for example, selective transport and storage of vaccines at ambient temperatures. The use of vaccine vial monitors reduces the risk associated with heat-damaged vaccines in these scenarios. Policy changes that allow limited storage of freeze-sensitive vaccines at temperatures >2-8 degrees C would enable flexible vaccine distribution strategies that could reduce vaccine freezing, reduce costs, and increase capacity. (+info)
Influence of storage humidity on the in vitro inhalation properties of salbutamol sulfate dry powder with surface covered lactose carrier.
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The influence of storage humidity on the in vitro inhalation properties of salbutamol sulfate dry powder with surface covered lactose carrier was investigated. In the present study, drug/carrier powder mixtures were prepared consisting of micronized salbutamol sulfate and lactose carriers with different particle surface conditions prepared by surface covering. Lactose carrier surfaces were covered with vegetable magnesium stearate (Mg-St-V) by a high-speed elliptical-rotor-type powder mixer (Theta-Composer). These powder mixtures were aerosolized by a Jethaler), and the in vitro inhalation properties of salbutamol sulfate were evaluated by a twin impinger. Compared with the powder mixed with uncovered lactose carrier, the in vitro inhalation properties of the powder mixture prepared using the surface covered lactose carrier were little decreased with increased in relative humidity (RH), showing that the in vitro inhalation properties of salbutamol sulfate were improved at high RH. Using this surface covering technique would thus be valuable for storage humidity of dry powder inhalation (DPI) with lactose carrier particles. (+info)
Influence of a thickness and processing method on the linear dimensional change and water sorption of denture base resin.
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The purpose of this study was to evaluate the influence of a thickness and processing method on linear dimension change and water sorption in a denture base resin after storage in water for 24 hours, one week, and four weeks. Sixty wax specimens 65 mm long and 10 mm wide were fabricated in three thicknesses, 1.5, 3, and 4.5 mm. Three dimples were made in each wax specimen. A travelling microscope was used to measure the total distance from the uppermost dimple to the lowest dimple to the nearest 0.01 mm. Acrylic resin blocks were polymerized with 2 processing cycles (short and long-cured). Immediately after processing, all samples were measured by the same investigator. They were then weighed by an electronic precision balance capable of measuring to 0.001 g. Data were analyzed by analysis of variance. Thickness and time of storage were statistically significant on the dimensional change (linear and weight changes) of denture-base resin (p < 0.01), showing the influence of the processing method. (+info)
Effects of silane coupling agent amount on mechanical properties and hydrolytic durability of composite resin after hot water storage.
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The purpose of this study was to evaluate the effects of the silane coupling agent amount on the flexural properties and hydrolytic durability on an experimental composite resin for understanding the optimum amount of silanation. A spherical filler was silanated with 7 different amounts of gamma-MPTS, 0, 0.17, 0.34, 0.66, 1.36, 2.72 and 5.45 mass%. Photopolymerized experimental composite resins were made from a 70/30 mass% of UDMA/TEGDMA and a 65 mass% of different silanated amounts of filler. Bar-shaped specimens were prepared for a 3-point bending test in 37 degrees C water after 1-day water storage at 37 degrees C and after an additional 1, 7, and 28 days hot water storage in Soxhlet's extractor. The flexural strength and flexural modulus of unsilanated filler dramatically decreased after 28 days hot water storage while those of silanated filler showed a slight change. These results suggested that the silanated amount on the silica filler is not sensitive for flexural properties and hydrolytic stability of composite resin. (+info)
Spatial clustering of malaria and associated risk factors during an epidemic in a highland area of western Kenya.
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The epidemiology of malaria over small areas remains poorly understood, and this is particularly true for malaria during epidemics in highland areas of Africa, where transmission intensity is low and characterized by acute within and between year variations. We report an analysis of the spatial distribution of clinical malaria during an epidemic and investigate putative risk factors. Active case surveillance was undertaken in three schools in Nandi District, Western Kenya for 10 weeks during a malaria outbreak in May-July 2002. Household surveys of cases and age-matched controls were conducted to collect information on household construction, exposure factors and socio-economic status. Household geographical location and altitude were determined using a hand-held geographical positioning system and landcover types were determined using high spatial resolution satellite sensor data. Among 129 cases identified during the surveillance, which were matched to 155 controls, we identified significant spatial clusters of malaria cases as determined using the spatial scan statistic. Conditional multiple logistic regression analysis showed that the risk of malaria was higher in children who were underweight, who lived at lower altitudes, and who lived in households where drugs were not kept at home. (+info)
Keep in a cool place: exposure of medicines to high temperatures in general practice during a British heatwave.
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Exposure of medicines to high temperatures in storage or in transit could reduce their efficacy, and most licences specify storage at 25 degrees C or less. To assess whether this criterion was being met, maximum temperatures in a general practice drug cupboard and in drug bags placed in car boots were recorded for two weeks during a British heatwave (average peak daily ambient temperature 26 degrees C). Also, ten neighbouring dispensing pharmacies were questioned about their temperature-control policies. On every day of the study, maximum temperatures in the drug cupboard and in the car boots exceeded 25 degrees C. Mean daily maxima (range) were: drug cupboard 30.7 (27.5-37.0); silver car 37.5 (32.0-43.5); dark blue car 41.8 (35.0-49.5). None of the local dispensaries had air conditioning or kept a temperature log. In the course of a British summer, medicines were exposed to temperatures that might in theory have reduced their efficacy. This aspect of quality control deserves more attention. (+info)
Effects of heat and pH in silanation process on flexural properties and hydrolytic durabilities of composite resin after hot water storage.
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The objectives of this study were to evaluate the effect of heat application after silanation and the pH effect of silanated solution on flexural properties and hydrolytic durability of experimental composites. A spherical-shaped filler was silanated with 0.66 mass% of gamma-MPTS in 70 vol% ethanol solution. For the heating effect, the filler was heated after silanation for 3 hours at 50 degrees C, 80 degrees C and 110 degrees C. For the effect of pH, ethanol solution with HCl solution of pH 1, 2 and 4 were used. All fillers were mixed to make photopolymerized experimental composite resins. All specimens after immersion in 37 degrees water for 24 hours were additionally immersed in Soxhlet's extractor for another 1, 7 and 28 days. A three-point bending test was performed in 37 degrees C water. The heat application of 50 degrees C and 80 degrees C increased flexural strength while heat of 110 degrees C and pH showed no effects on flexural properties at p<0.05. (+info)