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Rivas Zulay de Medina Hilda Ledo Gutiérrez Janio Gutiérrer Elizabeth 《Water, air, and soil pollution》2000,117(1-4):27-37
Nitrogen (N) and phosphorus (P) concentrations were determined in sediment samples along the bed of Catatumbo river in both Colombian and Venezuelan territories until the river outlet in Maracaibo lake. Total phosphorus was determined by digestion with HCl followed by analysis using the ascorbic acid method and total nitrogen was done using the standard microkjeldahl method plus nitrate-nitrite. Ammonium, orthophosphate and nitrate were determined using standard methods after extraction steps. The mean concentrations along the river bed were found in an interval of 0.035 and 1.492 mg g-1 dry sed. for nitrogen and 0.027 and 1.039 mg g-1 dry sed. for phosphorus at 95% confidence level. The mean molar ratio N/P in the river bed was 4.42 and 3.46 for river outlet zones in the lake, which indicates that nitrogen is the limiting nutrient. For comparison with previous results of lake sediments from sites near the river outlet it was concluded that Catatumbo river is a significant source of nutrients to the Maracaibo Lake system because sediment nutrients concentrations from Catatumbo river were higher than the ones in Maracaibo Lake. Statistic studies showed significant differences between countries, zones and similar behaviour in the river bed as related to the affluent rivers. 相似文献
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Carlos E.P. dos Santos Daniel G. Ubiali Caroline A. Pescador Régis A. Zanette Janio M. Santurio Luiz C. Marques 《Journal of Equine Veterinary Science》2014
A clinical epidemiological study was conducted among 34 rural properties located within the Brazilian Pantanal region and nearby areas between 2007 and 2010. The diagnosis of equine pythiosis was based on antibody detection (by enzyme-linked immunosorbent assay), polymerase chain reaction, histopathological analysis, and cultures positive for Pythium insidiosum. The majority of the affected animals (85%) were in the Pantanal biome, which had a higher disease prevalence (0.9%-66.7%) than that of the Cerrado (2.7%-33.3%). The disease was more prevalent in the rainy season (January-March), with an abrupt fall in the number of cases during the drought period (April–September; correlation of R2 = 0.77; P < .01). Generally, the average prevalence of equine pythiosis in both regions was 5%, with mortality and lethality rates of 1.3% and 23.1%, respectively, in the Pantanal and 2.3% and 45.5%, respectively, in the Cerrado. However, the treatment with immunotherapy may have underestimated these numbers, especially in the Pantanal. Animals older than 1 year were 8.09 times more affected by the disease than younger animals in the same environment (P < .05). A correlation between the anatomical area of the lesion and the type of skin color was also observed. Approximately 73% of the lesions were found in dark-pigmented areas, and animals with a dark coat color were affected more frequently. These findings highlight the importance of hematophagous insects in the epidemiology of pythiosis because these areas are preferred for blood feeding. 相似文献
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Argenta JS Alves SH Silveira F Maboni G Zanette RA Cavalheiro AS Pereira PL Pereira DI Sallis ES Pötter L Santurio JM Ferreiro L 《Veterinary microbiology》2012,157(1-2):137-142
The present study investigated the in vitro inhibitory activity of terbinafine, itraconazole, caspofungin, fluvastatin and ibuprofen against 15 isolates of Pythium insidiosum in double and triple combinations and determined in vivo correlations using rabbits with experimental pythiosis. The minimal inhibitory concentration (MIC) was determined in accordance with the Clinical and Laboratory Standards Institute M 38-A2 protocol (2008), and the in vitro interactions were evaluated using a checkerboard microdilution method. For the in vivo study, 20 rabbits inoculated with P. insidiosum zoospores were divided into four groups: group 1 was treated with terbinafine and itraconazole; group 2 was treated with terbinafine, itraconazole and fluvastatin; group 3 was treated with terbinafine and caspofungin; and group 4 was the control group. Combinations of terbinafine with caspofungin or ibuprofen were synergistic for 47% of the isolates, and antagonism was not observed in any of the double combinations. The triple combinations were mostly indifferent, but synergism and antagonism were also observed. In the in vivo study, the histological aspect of the lesions was similar among the groups, but group 2 showed the lowest amount of hyphae and differed significantly from the other groups. 相似文献
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Ledo Hilda Rivas Zulay Gutiérrez Janio Gutiérrez Elizabeth Ojeda Jesús Avila Hendrik 《Water, air, and soil pollution》2004,155(1-4):117-135
Ca, Mg, Fe, Mn and Al were determined in surficial sediment samples from Catatumbo River (including sediments from major tributaries) a binational basin shared by both Venezuela and Colombia in approximately 30% and 70%, respectively. The global mean concentration of the metals was Al > Fe > Mg > Ca > Mn (0.376; 0.304; 0.063; 0.042; 5.9 × 10-4 mmol g-1 dry weight). The objectives of this investigation were (1) to establish metal-concentration baselines, and (2) to determine spatial distribution of Ca, Mg, Fe, Mn and Al concentrations, in bed sediment samples from Catatumbo River (including sediments from major tributaries). As Catatumbo River is the main tributary to Lake Maracaibo system (South America's largest inland lake), its impact on the eutrophication process of Lake Maracaibo due to the formation of metal/phosphorus complexes is discussed. 相似文献
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