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The purpose of this experiment was to estimate the most effective doses of TFX, used in injection and in bath, for the stimulation of the activity of lymphocytes in common carp The study was performed on 9-month-old carps obtained after spring catches (in March). The fish were divided into 10 groups. Fish in groups I-IV were given TFX by intramuscular injection at doses of 20, 10, 0.5, and 0.2 mg/fish. Fish in groups VI-IX were bathed for 24, 48, and 96 hours in TFX at concentrations of 200, 100, 50, and 20 mg/l of water. Groups V and X were control. Blood samples were taken immediately after the administration of TFX in bath and after 2, 7, 14, and 28 days in groups I-IV and VIII-IX. The following parameters were determined: the number of leukocytes and lymphocytes in 1 μl of blood, the percentage of ANAE+ and E-rosette-forming cells, and the proliferative activity of lymphocyte cell cultures stimulated with Con A. Results: TFX at doses of 100, 200 mg/l of water and 10, 20 mg/fish administered by injection showed a suppressive effect on the parameters investigated. TFX at doses of 50, 20 mg/l of water and 0.5, 0.2 mg/fish caused an increase in the number of leukocytes and lymphocytes, a higher percentage of ANAE+ cells and rosette-forming cells, as well as a multiple increase in the proliferative activity of lymphocytes stimulated with Con A. The highest values were obtained after the administration of TFX in a 96-hour bath at a concentration of 50 mg/l of water.
The immune response in fish includes both cellular and humoral components. The aim of the study was to analyze the specific and adaptive immune response of carp using such parameters as the respiratory burst of blood phagocytes, lysosomal serum activity and the proliferative activity of lymphocytes induced by T-dependent mitogens PHA and Con A. Blood samples from 70 clinically healthy carp with body weights from 90 to 400 g were collected during a breeding season of 7 months, in March, April, May, June, July, September and October, The water temperatures in these months were, respectively, 4°C, 11°C, 16°C, 18°C, 22°C, 14°C, 8°C, and the fish were exposed to the stress being caught in March and October. The effect of low temperature and the stress factor (catching) on the leukocyte population was a reduction in the total number of white blood cells and lymphocytes and an increase in neutrophils. A negative relationship between the respiratory burst in neutrophils stimulated and water temperature was shown. The lowest values occurred at temperatures optimal for carp (18-22°C). Lysozyme activity in the samples increased from March to October and was the highest in autumn. The lowest proliferative activity of T lymphocytes was found in March, the highest in June and July. This study is the first to show the effect of suboptimal temperatures and the stress of being caught on defense mechanisms in 9 to16-month-old carp during the breeding season. The results suggest that these mechanisms are influenced by interaction between the endocrine and immune systems, in which the presumably elevated cortisol level has an immunomodulatory function.
The purpose of this experiment was to estimate the activity of antioxidant enzymes (SOD, GPx, CAT) in erythrocytes and phagocytes of carps (Cyprinus carpio L.) after intraperitoneal injection of LPS at a dose of 75 μg/100 g b.w. Enzyme activity was determined 3, 6 and 12 hours, as well as 3, 7, 14 and 28 days after LPS administration. After 3 and 6 hours, SOD in erythrocytes increased, respectively, to 188% and 142% of its control group level, and after 12 hours, SOD activity was significantly reduced (117%) and remained unchanged until the end of the experiment. From 12 hours after LPS administration until the end of the study, the PGx level was statistically significantly lower than in the control group, whereas the catalase activity was statistically significantly lower than in the control group in all study periods. In kidney phagocytic cells, SOD activity after 12 hours and 3 days was similar to that in the control group, and in the following study periods it amounted to 66-78% of the control values. Until the 14th day of observation, PGx activity was statistically significantly lower than it was in the control group. Catalase activity in kidney leukocytes was statistically significantly lower than in the control group during the entire experiment, and the lowest in the first study days, amounting to 48-42% of the control group value. The results indicate a long-term decrease in antioxidant enzyme activities in the experimental fish (lasting 14 or 28 days).
Bacterial infections are a serious problem for commercial farms of carp (Cyprinus carpio L.) in Poland. Given the absence of efficient vaccines, it is crucial to search for new agents enhancing the non-specific immune response of the fish. In the present study, immunomodulating effects of lipopolysaccharide extracted from the virulent (LPS-P) and non-virulent (LPS-NP) strains of Aeromonas hydrophila were studied. For that purpose, different concentrations of LPS-P and LPS-NP (25, 50, and 75 µg/100 g body weight) were administered to test animals through intraperitoneal injection. The non-specific immune response of the fish were studied at days 7, 14, 21, 28, and 60 after vaccination. Immunostimulated fish showed an increase in total leukocyte count, in the population of monocytes and neutrophils, and in immature cell count in the whole blood. Phagocytic activity and the production of reactive oxygen species were also elevated after vaccination. Moreover, vaccinated fish showed a significant increase in serum lysozyme. The results of the present study show that LPS-NP has a greater immunostimulatory effect than LPS-P at doses of 50 and 75 µg/100 g body weight. In addition, 7 days after vaccination with LPS-NP (50 µg/100 g body weight), fish were challenged with the virulent strain of A. hydrophila. The relative percentage of survival in groups 1 and 2 was 58.82% and 76. 47%, respectively, which indicates that the administration of LPS-NP makes C. carpio more resistant to infection by A. hydrophila
The aim of this study was to evaluate the effect of flumequine on the percentage of peripheral blood leukocytes of carp, alpha naphthyl acetate esterase (ANAE) activity and proliferative activity of lymphocytes stimulated with concanavalin A (Con A) and lipopolysaccharide (LPS). Flumequine was administered to 40 carp, weighing 150 ± 10 g, at a dose of 12 mg/kg, once (group I) and four times, every 2 days (group II). Among white blood cells in flumequine, treated fish (group II) observed a decrease in percentage of lymphocytes and an increase of neutrophiles. Identification of the ANAE esterase activity in fish lymphocytes of the control group showed the advantage of positive cells over the negative ones and amounted to 62.65 ± 3.22%. After administration of flumequine in group II fish, this value decreased to 44.75 ± 3.70%. The present study clearly demonstrated that both Con A and LPS induced lymphoid cell proliferation in vitro in group I. There was an increase in activity after stimulation of LPS and its reduction after Con A in group II. This indicates a stimulating effect of flumequine on B lymphocytes. The results of this study are not conclusive as to the positive effect of the drug on the immune system of fish and indicate the need for caution in its use.
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