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41.
Elena Marcos Leonor Calvo José Antonio Marcos Ángela Taboada Reyes Tárrega 《European Journal of Forest Research》2010,129(1):25-30
We aimed to study tree effects on the chemical properties of forest soils. We compared soil features of three types of forest ecosystems, each with four stands (replicates): beech forests (Fagus sylvatica), oak forests (dominated by Quercus pyrenaica) and pine plantations (Pinus sylvestris). Five samples from the top 10 cm of soil were taken per stand, from which pH, organic matter content (O.M.), total nitrogen (N) and available calcium (Ca2+), magnesium (Mg2+), potassium (K+) and sodium (Na+) were determined. Litter layer depth was measured at each soil sampling point. We also measured tree density and crown diameters at each stand. Our results indicated that soil samples from the four pine plantation stands were more similar while oak and beech stands were characterised by great variability in terms of soil properties and leaf litter depth. Although the identity of the dominant tree species significantly influenced several topsoil chemical properties (increase in pH and available cations in oak forests and higher organic matter and total nitrogen in beech and pine ecosystems), there were other important factors affecting soil features that may be taken under consideration. Differences between soil properties of the three types of forest ecosystems were mainly related to the characteristics of the litter layer and less related to the tree layer structure. Finally, the establishment of pine plantations in naturally deciduous tree areas made the topsoil features more homogeneous. 相似文献
42.
Cortez Alcobedes Maria M. Boggio Gonzalo Guerra Ma. de Lourdes de Gavidia Magda Rodríguez Rojas Reyes Glenda C. Ferrer Elizabeth Lares Maria Alviarez Yenny Harrison Leslie J. S. Parkhouse R. Michael E. 《Tropical animal health and production》2010,42(3):531-537
There is a paucity of quantitative data on the status of porcine cysticercosis in Venezuela, information which is essential
for understanding the level of disease transmission. This study was, therefore, conducted in a typical small rural community
in Yaracuy State, Venezuela, where previous cases of human Taenia solium taeniasis/cysticercosis had been reported and where the free-ranging pig management practices and the lack of rudimentary
sanitary facilities indicated an obvious risk for transmission of the disease. Serum samples from 52 village pigs were screened
by enzyme-linked immunosorbent assays for anti-cysticercal antibodies (Ab-ELISA), using T. solium cyst fluid as the antigen and the HP10, monoclonal antibody-based, antigen trapping ELISA for parasite antigen (HP10 Ag-ELISA).
Significantly, a high proportion of the animals (65.4% for the Ab-ELISA and 42.3% for the HP10 Ag-ELISA) were sero-positive.
Five of the pigs, which were selected on that basis of positive tongue palpation, were killed for autopsy, and large numbers
of viable cysticerci were found in the carcases. This unequivocal documentation of porcine cysticercosis in Venezuelan pigs
presents clear evidence that T. solium is actively transmitted in Venezuela. Further detailed studies and implementation of appropriate control measures are therefore
indicated. 相似文献
43.
Parraguez VH Atlagich MA Urquieta B Galleguillos M De Los Reyes M Kooyman DL Araneda S Raggi LA 《Canadian journal of veterinary research》2010,74(3):193-199
Fetal weight and the placenta of sheep at high altitude (HA) are affected by hypoxia. Placental changes (an increase in placental size and vascularization) are greater in ewes from populations that have lived for several generations at HA than in those exposed during just 1 gestation. This study investigated placental expression of vascular endothelial growth factor (VEGF) and endothelial nitric oxide synthase (eNOS), 2 molecules involved in placental angiogenesis that could be upregulated by hypoxia. Two groups of ewes were maintained at HA (3589 m) during pregnancy: HA-native ewes (group HH) and ewes native to lowlands but moved to HA immediately after the diagnosis of pregnancy (group LH). A control group (LL) was kept at sea level. Near term, placentomes were removed, weighed, and processed for immunohistochemical detection of VEGF and eNOS, as well as for vascular area measurement. Placental weight was significantly higher in the HH group than in the LH and LL groups; between the latter 2 groups there was no significant difference. The placental area occupied by vasculature was significantly greater in both the HA groups than in the LH group; the number of placentomes was greatest in the LL group. The density of VEGF and eNOS in the placentome tissue was significantly greater in both HA groups than in the LL group. Although the density of VEGF was significantly lower in the HH group than in the LH group, no differences were observed in eNOS density between the HH and LH animals. These results demonstrate that chronic hypoxia upregulates the expression of placental VEGF and eNOS, suggesting an important role of these molecules in the placental response to HA hypoxia. In addition, an attenuated response to hypoxia in VEGF synthesis may be part of the long-term process of adaptation to HA. 相似文献
44.
Colín-González AL Ortiz-Plata A Villeda-Hernández J Barrera D Molina-Jijón E Pedraza-Chaverrí J Maldonado PD 《Plant foods for human nutrition (Dordrecht, Netherlands)》2011,66(4):348-354
Different garlic products reduce the cerebral ischemic damage due to their antioxidant properties. In this work, we investigated
the effect of aged garlic extract (AGE) on cyclooxygenase-2 (COX-2) protein levels and activity, and its role as a possible
mechanism of neuroprotection in a cerebral ischemia model. Animals were subjected to 1 h of ischemia plus 24 h of reperfusion.
AGE (1.2 ml/kg weight, i.p.) was administered at onset of reperfusion. To evaluate the damage induced by cerebral ischemia, the neurological deficit,
the infarct area, and the histological alterations were measured. As an oxidative stress marker to deoxyribonucleic acid,
8-hydroxy-2-deoxyguanosine (8-OHdG) levels were determined. Finally, as inflammatory markers, TNFα levels and COX-2 protein
levels and activity were measured. AGE treatment diminished the neurological alterations (61.6%), the infarct area (54.8%)
and the histological damage (37.7%) induced by cerebral ischemia. AGE administration attenuated the increase in 8-OHdG levels
(77.8%), in TNFα levels (76.6%), and in COX-2 protein levels (73.6%) and activity (30.7%) induced after 1 h of ischemia plus
24 h of reperfusion. These data suggest that the neuroprotective effect of AGE is associated not only to its antioxidant properties,
but also with its capacity to diminish the increase in TNFα levels and COX-2 protein expression and activity. AGE may have
the potential to attenuate the cerebral ischemia-induced inflammation. 相似文献
45.
Esquifino AI Chacón F Jimenez V Reyes Toso CF Cardinali DP 《Journal of circadian rhythms》2004,2(1):1
BACKGROUND: This work analyzes the effect of social isolation (a mild stressor) on the 24-h variation of pituitary-testicular function in young Wistar rats, assessed by measuring circulating levels of prolactin, FSH, LH and testosterone. METHODS: Animals were either individually caged or kept in groups (4-5 animals per cage) under a 12:12 h light-dark cycle (lights on at 0800 h) for 30 days starting on day 35 of life. Rats were killed at 4-h intervals during a 24-h cycle, beginning at 0900 h. RESULTS: Isolation brought about a decrease in prolactin, LH and testosterone secretion and an increase of FSH secretion. In isolated rats the 24-h secretory pattern of prolactin and testosterone became modified, i.e., the maximum in prolactin seen in control animals at the beginning of the activity span was no longer detected, whereas the maximum in circulating testosterone taking place at 1700 h in controls was phase-delayed to 2100 h in isolated rats. CONCLUSION: Social isolation affects the 24-h variation of pituitary-testicular function in young rats. Secretion of prolactin, LH and testosterone decreases, and secretion of FSH increases, in isolated rats. The maximum in prolactin seen in group-caged rats at the beginning of the activity span is not observed in isolated rats. The maximum in circulating testosterone taking place at the second part of the rest span in controls is phase-delayed to the light-dark transition in isolated rats. 相似文献
46.
47.
Pharmacokinetic study of enrofloxacin in Nile tilapia (Oreochromis niloticus) after a single oral administration in medicated feed
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J. A. Teles L. C. Castello Branco M. Del Bianchi F. Pilarski F. G. R. Reyes 《Journal of veterinary pharmacology and therapeutics》2016,39(2):205-208
The objective of this study was to evaluate the disposition kinetics of enrofloxacin (ENR) in the plasma and its distribution in the muscle tissue of Nile tilapia (Oreochromis niloticus) after a single oral dose of 10 mg/kg body weight via medicated feed. The fish were kept at a temperature between 28 and 30 °C. The collection period was between 30 min and 120 h after administration of the drug. The samples were analyzed by high‐performance liquid chromatography with a fluorescence detector (HPLC‐FLD). The ENR was slowly absorbed and eliminated from the plasma (Cmax = 1.24 ± 0.37 μg/mL; Tmax = 8 h; T1/2Ke = 19.36 h). ENR was efficiently distributed in the muscle tissue and reached maximum values (2.17 ± 0.74 μg/g) after 8 h. Its metabolite, ciprofloxacin (CIP), was detected and quantified in the plasma (0.004 ± 0.005 μg/mL) and muscle (0.01 ± 0.011 μg/g) for up to 48 h. After oral administration, the mean concentration of ENR in the plasma was well above the minimum inhibitory concentrations (MIC50) for most bacteria already isolated from fish except for Streptococcus spp. This way the dose used in this study allowed for concentrations in the blood to treat the diseases of tilapia. 相似文献
48.
The consequences of diet limitation in juvenile threespine stickleback: growth,lipid storage and the phenomenon of compensatory growth
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Many organisms exhibit compensatory growth (CG), an accelerated growth rate during recovery from periods of low nutrient resources. Despite numerous studies, many aspects of CG, particularly fine‐scale temporal effects early in life, remain poorly understood. We manipulated early‐life feeding regimens in threespine stickleback (Gasterosteus aculeatus) to study compensatory responses in growth rate and lipid storage during the first growing season. Laboratory‐reared stickleback, including ancestral oceanic and derived freshwater populations, were divided into three age‐specific dietary treatment groups – DPR1, DPR2 and DPR3 – which were exposed to a half‐ration nutrient deprivation for 30 days at the onset of 2, 3 and 4 months of age, respectively. We hypothesised that these month‐long periods of nutrient deprivation would result in strong, yet variable CG responses across stickleback populations and dietary treatments following a return to optimal ration levels. The youngest two age classes of fish (DPR1 &and DPR2) exhibited strong CG responses, matching growth rates and lipid generation levels seen in control fish fed an ad libitum diet. The oldest nutrient‐deprived group (DPR3) showed a reduced CG response, with body growth recovering only partially, and lipid levels exhibiting even less recovery. Our results demonstrate that compensatory growth responses in juvenile stickleback depend on the timing of deprivation during the first growing season and further that responses to late‐season deprivation have favoured development of a larger body frame entering the overwintering season over lipid regeneration. 相似文献
49.
Francisco Artés-Hernández Pedro A. Robles Perla A. Gómez Alejandro Tomás-Callejas Francisco Artés 《Postharvest Biology and Technology》2010,55(2):114-120
The effects of four pre-packaging UV-C illumination doses (1.6, 2.8, 4.8 and 7.2 kJ m?2) on quality changes of watermelon cubes stored up to 11 days at 5 °C were studied. Non-treated cubes were used as a control. Higher UV-C doses induced slightly higher CO2 production throughout the storage period, while no changes in C2H4 production were monitored. However, UV-C did not significantly affect the final gas partial pressures within modified atmosphere packages where levels of 3–6 kPa O2 and 13–17 kPa CO2 were reached for all treatments. UV-C decreased microbial counts just after illumination. After 11 days at 5 °C, mesophilic, psycrophilic and enterobacteria populations were significantly lower in UV-C treated watermelon. Slight changes in CIE colour parameters were observed. According to sensory quality attributes, control and low UV-C treated cubes (1.6 and 2.8 kJ m?2) can be stored for up to 11 days at 5 °C while the maximum shelf-life of moderate to high UV-C treated fruit was 8 days at 5 °C. Control cubes showed a 16% decrease in lycopene content after 11 days at 5 °C similar to that found for the high UV-C treatment. However low UV-C treated watermelon cubes preserved their initial lycopene content (2.8 kJ m?2) or it was slightly decreased (1.6 kJ m?2). UV-C radiation did not significantly affect the vitamin C content while catalase activity and total polyphenols content considerably declined throughout the storage period. However, total antioxidant capacity markedly increased, independently of UV-C doses. As a main conclusion, UV-C radiation can be considered a promising tool for keeping overall quality of fresh-cut watermelon. 相似文献
50.
The crude ethanol extract from the leaves of Zanthoxylum liebmannianum exhibited inhibitory effect on the reproduction of trophozoites of Entamoeba histolytica (IC(50)=3.48 microg/ml) and Giardia lamblia (IC(50)=58.00 microg/ml). From this extract, asarinin, hyperin, beta-sitosterol, and beta-sitosterol glucoside were isolated. Among them, asarinin was the most active with IC(50) values of 19.86 microg/ml for E. histolytica and 35.45 microg/ml for G. lamblia. The remaining compounds showed moderate activity against both parasites. 相似文献