RESUMO
The seroprevalence of porcine circovirus type 2 (PCV2) in the swine population of Trinidad and Tobago was studied, focusing on the association between the seroprevalence of the virus and each of four variables: gender, age, group, farm size, and geographic location. Farms were classified as large (>1000 sows) or small (2 pigs to 250 sows); three age groups-nursery pigs (3 to 10 weeks, n=82), grower (11 to 22 weeks, n=107), and breeding animals(n=85) were studied. A multistage sampling design with non-proportional sampling between strata (farm sizes) was employed. A total of 274 serum samples were tested, collected from three large farms (n=109) and 109 randomly chosen small farms (n=165). Samples were tested using the PCV type 2 indirect fluorescent antibody test kit by VMRD (USA). Sixty-one percent of the farms tested were positive (2 large farms, 66 small farms). The overall seroprevalence of PCV2 was 62.0% (170/274) and after adjusting for non-proportional sampling between strata, was 70.3% ...
Assuntos
Animais , Circovirus , Trinidad e Tobago , Suínos , Sorologia , Estudos SoroepidemiológicosRESUMO
The seroprevalence of porcine circovirus type 2 (PCV2) in the swine population of Trinidad and Tobago was studied, focusing on the association between the seroprevalence of the virus and each of four variables: gender, age, group, farm size, and geographic location. Farms were classified as large (>1000 sows) or small (2 pigs to 250 sows); three age groups-nursery pigs (3 to 10 weeks, n=82), grower (11 to 22 weeks, n=107), and breeding animals(n=85) were studied. A multistage sampling design with non-proportional sampling between strata (farm sizes) was employed. A total of 274 serum samples were tested, collected from three large farms (n=109) and 109 randomly chosen small farms (n=165). Samples were tested using the PCV type 2 indirect fluorescent antibody test kit by VMRD (USA). Sixty-one percent of the farms tested were positive (2 large farms, 66 small farms). The overall seroprevalence of PCV2 was 62.0% (170/274) and after adjusting for non-proportional sampling between strata, was 70.3% ...
Assuntos
Animais , Circovirus , Trinidad e Tobago , Suínos , Sorologia , Estudos SoroepidemiológicosRESUMO
Venezuelan equine encephalitis virus (VEEV) may cause encephalitis in humans, for which no FDA-approved antiviral treatment is available. Carbocyclic cytosine (carbodine) has broad-spectrum activity but toxicity has limited its utility. It was anticipated that one of the enantiomers of carbodine would show enhanced activity and reduced toxicity. The activity of the d-(-) enantiomer of carbodine [(-)-carbodine] was evaluated by infectious cell culture assay and was found to have a 50% effective concentration (EC50) of 0.2 microg/ml against the TC-83 vaccine strain of VEEV in Vero cells, while the l-(+) enantiomer had no activity. Virus titer inhibition correlated with intracellular cytidine triphosphate reduction after treatment with (-)-carbodine, as determined by HPLC analysis. Pre-treatment with 200 mg/(kgd) resulted in significant improvement in survival, virus load in the brain, weight change, and mean day-to-death in a mouse model of TC-83 VEEV disease. A single dose of (-)-carbodine resulted in a slight extension of mean time to death in mice infected with wild-type VEEV. Post-virus exposure treatment with (-)-carbodine was effective in significantly improving disease parameters in mice infected with TC-83 VEEV when treatment was initiated as late as 4 days post-virus installation (dpi). It is remarkable that (-)-carbodine is effective when initiated after the establishment of brain infection.
Assuntos
Antivirais/farmacologia , Citidina/análogos & derivados , Vírus da Encefalite Equina Venezuelana/efeitos dos fármacos , Encefalomielite Equina Venezuelana/tratamento farmacológico , Animais , Chlorocebus aethiops , Citidina/farmacologia , Citidina Trifosfato/metabolismo , Encefalomielite Equina Venezuelana/virologia , Feminino , Humanos , Camundongos , Camundongos Endogâmicos C3H , Camundongos Endogâmicos ICR , Células VeroRESUMO
Tropical river sardine, Caquetaia kraussii, captured from La Aguá lagoon (Sucre State, Venezuela) were acclimatized for four weeks at 22, 24, 30 and 32 degrees C and at 0, 5, 10, 15 and 17@1000 salinity. To evaluate effects of thermal response to acclimatization level, the fish were transferred suddenly from lower temperatures (22 and 24 degrees C) to higher ones (32 and 30 degrees C) respectively. Then thermal resistance time was measured at the lethal temperature of 40.9 degrees C for 30 days. We considered that acclimatization process completed when resistance time was stabilized at the new temperature regime. For the saline effect, the concentrations of sodium and potassium were measured in the tissues at each treatment: gills, white muscle, gut and heart. The results showed that thermal tolerance increased rapidly in 3 h with a 6 degrees C rise in temperature (from 24 to 30 degrees C) and in 24 h with a 10 degrees C rise (22 to 32 degrees C). With decreasing temperatures, the acclimatization level reached its lowest in 11 days with a 6 degrees C decreases (from 30 to 24 degrees C) and in 14 days with a 10 degrees C decrease (32 to 22 degrees C). Caquetaia kraussii regulates as much sodium as potassium in gills and white muscle tissues at all salinity levels tested; however, gut and heart tissues showed significantly different regulations among salinities examined.
Assuntos
Animais , Aclimatação/fisiologia , Água Doce/química , Peixes , Temperatura , VenezuelaRESUMO
Tropical river sardine, Caquetaia kraussii, captured from La Aguá lagoon (Sucre State, Venezuela) were acclimatized for four weeks at 22, 24, 30 and 32 degrees C and at 0, 5, 10, 15 and 17@1000 salinity. To evaluate effects of thermal response to acclimatization level, the fish were transferred suddenly from lower temperatures (22 and 24 degrees C) to higher ones (32 and 30 degrees C) respectively. Then thermal resistance time was measured at the lethal temperature of 40.9 degrees C for 30 days. We considered that acclimatization process completed when resistance time was stabilized at the new temperature regime. For the saline effect, the concentrations of sodium and potassium were measured in the tissues at each treatment: gills, white muscle, gut and heart. The results showed that thermal tolerance increased rapidly in 3 h with a 6 degrees C rise in temperature (from 24 to 30 degrees C) and in 24 h with a 10 degrees C rise (22 to 32 degrees C). With decreasing temperatures, the acclimatization level reached its lowest in 11 days with a 6 degrees C decreases (from 30 to 24 degrees C) and in 14 days with a 10 degrees C decrease (32 to 22 degrees C). Caquetaia kraussii regulates as much sodium as potassium in gills and white muscle tissues at all salinity levels tested; however, gut and heart tissues showed significantly different regulations among salinities examined.
Assuntos
Aclimatação/fisiologia , Peixes/fisiologia , Água Doce/química , Temperatura , Animais , VenezuelaRESUMO
Physiological response of tropical organisms to salinity changes was studied for some marine, estuarine and freshwater fishes (Astyanax bimaculatus, Petenia karussii, Cyprinodon dearborni, and Oreochromis mossambicus), marine and freshwater crustaceans (Penaeus brasiliensis, Penaeus schmitti and Macrobrachium carcinus), and marine bivalves (Perna perna, Crassostrea rhizophorae, and Arca zebra) collected from Northeast Venezuela. They were acclimated for four weeks at various salinities, and (1) placed at high salinities to determine mean lethal salinity, (2) tested by increasing salinity 5@1000 per day to define upper lethal salinity tolerance limit, or (3) observed in a saline gradient tank to determine salinity preference. Acclimation level was the most significant factor. This phenomenon is important for tropical aquatic organisms in shallow waters, where they can adapt to high salinity during the dry season and cannot lose their acclimation level at low salinity during abrupt rain. For saline adaptation of tropical organisms, this behavior will contribute to their proliferation and distribution in fluctuating salinity environments.
Assuntos
Adaptação Fisiológica/fisiologia , Bivalves/fisiologia , Crustáceos/fisiologia , Peixes/fisiologia , Animais , Comportamento Animal , Água Doce , Água do Mar , Temperatura , Clima Tropical , VenezuelaRESUMO
The concentration of copper, cadmium and lead in superficial sediment, water and the fish Cyprinodon dearborni was determined in two coastal lagoons of Sucre State, Venezuela. Chacopata lagoon is hyper saline while Los Patos lagoon is hypo saline and receives significant wastewater from Cumaná city. Water, sediment and fish samples were collected in February 1998. In the laboratory, samples underwent acid digestion and were analyzed by atomic absorption spectophotometry. The mean values of the metals in C. dearborni from the Chacopata lagoon were: 159.26 +/- 210.68 microg/g for Cu, 44.71 +/- 45.58 microg/g for Cd, and 9.31 +/- 23.34 microg/g for Pb, while for Los Patos lagoon the mean values were: 64.88 +/- 16.30, 19.48 +/- 5.81 and 22.85 +/- 20.00, respectively. In the water column, the metal concentration ranges were: 2.3-11.6, 3.9-5.4 and 21-32 mg/l for copper, cadmium and lead, respectively. These results suggest that metal levels in sediment, water column and organisms in both lagoons do not differ, except for lead, even though only Los Patos receives waste water.
Assuntos
Animais , Água Doce/química , Metais Pesados/análise , Peixes Listrados/metabolismo , Peso Corporal , Sedimentos Geológicos/química , Cádmio/análise , Cádmio/farmacocinética , Chumbo/análise , Chumbo/farmacocinética , Cobre/análise , Cobre/farmacocinética , Monitoramento Ambiental , Metais Pesados/farmacocinética , Peixes Listrados/anatomia & histologia , Espectrofotometria Atômica , VenezuelaRESUMO
Benthic test species used in toxicity assays are the best indicators of sediment toxicity because they live in direct contact with sediments and the water column. Mercury chloride is one the most toxic metallic salts. Its strong affinity for particles explains the high Hg content found in benthic populations. The genus Emerita is abundantly found in Venezuelan coasts and is a good bioaccumulator of pollutants, but the toxicological assays performend on this genus are scarce. The present experimental test reports on the distribution of mercury in the water column and sediment, using static bioassay in short term (24 hr) and the ability of Emerita portoricensis to bioconcentrate mercury under experimental conditions. Our results suggest that the Hg transference from water to sediment is enhanced in the presence of Emerita. The kinetic uptake of Hg in Emerita portoricensis shows a mechanism of rapid absorption reaching high metal concentrations in short exposure times.
Assuntos
Animais , Decápodes/metabolismo , Mercúrio/farmacocinética , Poluentes Químicos da Água/farmacocinética , Exposição Ambiental , Monitoramento Ambiental/métodos , Distribuição Tecidual , VenezuelaRESUMO
Bauxite explotation of the Orinoco River in recent years is an important source of heavy metals discharge in the ecosystem, changing the natural biochemical flow of these elements and their concentrations in water, sediment and organisms. Iron and copper concentrations were measured in the fish Plagioscion squamosissimus in the Orinoco river, by sampling the fish population for three months (September-November 1998) in the main channel of the middle Orinoco (07 degrees 38' 21.2[quot ] N; 66 degrees 19' 10.9" W) and in Castillero lagoon (7 degrees 39' 09" N; 66 degrees 09' 00" W) with 2 and 4 cm mesh sizes. The internal organs of 30 fishes per month and site were stove-dried at 80 degrees C, pulverized and dried in disecator for 30 min to use as indicators with the acid digestion method for predicting the effect of heavy metals. We found relatively high values of iron and copper concentrations in fishes of the lagoon, and high seasonal variations in the iron concentration.
Assuntos
Animais , Cobre/análise , Peixes , Ferro/análise , Monitoramento Ambiental/métodos , Poluição Química da Água/análise , Rios/química , Mineração , Peixes/metabolismo , Fatores de Tempo , VenezuelaRESUMO
The green mussel, Perna viridis, became widespread in the northern coast of Sucre State since its arrival to Venezuela in 1993. RNA/DNA and Protein/DNA ratios were used to study the effect of starvation on its instantaneous growth. The mussels were collected in La Esmeralda and Chacopata, acclimatized in the laboratory for four weeks and maintained for another six weeks in two groups: one fed ad libitum and another without food (this later group was later fed for two additional weeks). Protein (colorimetric method), and nucleic acid concentrations (RNA and DNA, fluorometric method with ethidium bromide) were measured in adductor muscle, digestive gland and gills. The instantaneous growth was assessed using RNA/DNA and Protein/DNA rations. These indexes were always higher in the fed organisms. Animals from Chacopata were in better physiological condition that those from La Esmeralda during the abstinence time (six weeks). Muscle was the best tissue to determine instantaneous growth. The RNA/DNA ratio is a reliable index to determine the physiological condition and instantaneous growth of this species.