Pedro Zeinsteger

Hematological indicators of liver damage during the subclinical phase of fasciolosis in steers from Northeastern Argentina

The aim of this study was to determine eventual changes in blood parameters that characterize liver damage during the subclinical phase (asymptomatic) of liver fluke disease in cattle from Northeastern Argentina. Blood samples of 56 apparently healthy half-blood Brahman × Angus steers from slaughterhouses of enzootic areas of fasciolosis were collected and later analyzed. After death, from the total of animals, it was found that 29 harbored slight amount of fasciolas in the hepatic parenchyma. With conventional laboratory techniques, erythrogram, leukogram, proteinogram, and enzymogram (alkaline phosphatase, gamma-glutamyltransferase (GGT), and aspartate aminotransferase (AST)) were determined, as well as concentrations of iron, glucose, bilirubin, and prothrombin time. Parasitized animals revealed higher values for leukocytes, eosinophils, gamma globulins, and GGT activity when compared to controls (P < 0.05). Such parameters are inflammatory indicators attributable to an incipient cholangitis that characterizes the subclinical phase of distomatosis. Changes that may indicate cholestasis or liver dysfunction were not verified.

Bioequivalence Study of Two Long-Acting Formulations of Oxytetracycline Following Intramuscular Administration in Bovines

The aim of this study was to evaluate the bioequivalence of two commercial long-acting formulations based on oxytetracycline (OTC) hydrochloride between the reference formulation (Terramycin LA, Pfizer) and a test formulation (Cyamicin LA, Fort Dodge Saude Animal). Both formulations were administered in a single intramuscular route at a dose of 20 mg OTC/kg of body weight in clinically healthy bovines. The study was carried out according to a one-period parallel design. Plasma samples were analyzed by high-pressure liquid chromatography. The limit of quantitation was 0.050 μg/mL with an accuracy of 101.67% with a coefficient of variation of 13.15%. Analysis of variance and 90% confidence interval tests were used to compare the bioavailability parameters (maximum plasma concentration, Cmax, and the area under the concentration-versus-time curve extrapolated to infinity, AUC0–∞) of both products. In the case of the time to maximum concentration (Tmax), non-parametric tests based on Wilcoxon’s signed rank test were preferred. The comparison of the mean AUC0–∞ values did not reveal any significant differences (311.40 ± 93.05 μg h/mL and 287.71 ± 45.31 μg h/mL, respectively). The results were similar for the Tmax (3.58 ± 0.90 h versus 3.42 ± 0.51 h). However, when comparing the mean Cmax some significant differences were found (8.73 ± 3.66 μg/mL and 10.43 ± 3.84 μg/mL, respectively). The 90% confidence intervals for the ratio of AUC0–∞ and Tmax values for the reference and test product are within the interval 80–125%, but the 90% confidence intervals for the ratio of Cmax falls outside the proposed interval. It was concluded that Cmax of test product are not within the 20% of those of the reference, thus suggesting that test OTC is not bioequivalent to the reference formulation.

Antioxidant properties of Calendula officinalis L. (Asteraceae) on Fe2+-initiated peroxidation of rat brain mitochondria

In the study reported here, the effect of Calendula officinalis L. (Asteraceae) extract (CO) on the polyunsaturated fatty acid composition, chemiluminescence, and Peroxidizability Index (PI) of mitochondria isolated from brain rat was analyzed. After incubation of mitochondria in an ascorbate (0.4 mM)-Fe++ (2.15 µM) system (180 min at 37 °C), it was observed that the total cpm/mg protein originated from light emission: chemiluminescence was lower in brain mitochondria obtained from CO group than in the control group (without extract supplementation). Moreover, it was observed that the extract was reduced, concentration dependent, of chemiluminescence, measured as total cpm. The fatty acid composition of brain mitochondria from control group was profoundly modified when subjected to non-enzymatic lipoperoxidation with a considerable decrease of arachidonic acid C20:4ω6 and docosahexaenoic acid C22:6ω3. As consequence, the PI, a parameter based on the maximal rate of oxidation of specific fatty acids was higher in the CO group than in the control group. The simultaneous analysis of PI, chemiluminescence, and fatty acid composition indicates that CO may act as an antioxidant protecting rat brain mitochondria from peroxidative damage.

Repellent and Lethal Activities of Extracts From Fruits of Chinaberry (Melia azedarach L., Meliaceae) Against Triatoma infestans

Triatoma infestans is the principal vector of Trypanosoma cruzi, parasite responsible of Chagass Disease transmission in Argentina. Pyrethroids have become common pesticides for the control of T. infestans but increasing resistance encourages the search of new alternatives and the use of natural products for biological control arises as a new strategy. Melia azedarach L. is originated from the Himalayas region and several compounds are part of its rich phytochemistry. Folk medicine of the plant is due to its repellent and insecticidal activities. Aims of this work were to evaluate the repellent activity of methanolic and acetonic extracts from fruits of M. azedarach by means of the area preference method of fifth and first nymph stages as well as to test the acute lethal effect of the more repellent extract by means of direct application on cuticle on both stages. For repellence, qualitative filter papers were divided into two halves, one treated with methanolic (ME) or acetonic (AC) extract and the other without treatment. Controls were impregnated half with methanol or acetone and half without the solvents. One nymph was located in each Petri or well and repellence percentage was determined. For the lethal effect, fasted and fed to repletion 5th stage nymphs were topically administered with different concentrations of AC and deaths were registered after 24, 48, 72, 96, and 120 h. Phytochemical analysis of extracts was performed as well. AC demonstrated high repellent activity (100%, both stages), whereas ME extract activity was slight (10–21%). AC extract was selected for lethal assays due to early repellent activity. Fed to repletion nymphs were more sensitive to the lethal activity of the extract when compared to fasted nymphs (LD50: 11.5 vs. 23.1 μg/insect, respectively). Phytochemistry assays of extracts showed a higher concentration of flavonoids, alkaloids and triterpenes for AC. Considering these results, next assays will include the test of Melia azedarach extract on T. infestans that are resistant to pyrethroids for a possible synergism between AC and the pesticides.