Oral dosage regimen in the nonlinear pharmacokinetics of sulphadimethoxine in pigs

An oral high dosage regimen of sulphadimethoxine (SDM) was examined in pigs. The dose (50 mg/kg) in the therapeutic range, showed nonlinear pharmacokinetics, and administered by drench once a day for 4 days. The unbound plasma concentration-time profile was compared with that of the dosage regimen based on nonlinear pharmacokinetics, where a pharmacokinetic model and parameters were used except for the first order absorption rate constant (ka) and bioavailability (F). F and ka were obtained from oral and intravenous administration of 20 and 10 mg/kg of SDM. The unbound plasma concentration was observed almost within the setting range by the dosage regimen through the experimental period. This result suggested that the dosage regimen, based on the nonlinear pharmacokinetic model, resulted in an appropriate effect in the clinical use.     

Effect of Toxoplasma lysate antigen (TLA) on feline cytotoxicity against FeLV positive lymphoma cells

The cytotoxic activities of feline spleen cells treated with Toxoplasma lysate antigen (TLA) were assayed against feline leukemia virus (FeLV)-producing lymphoma. FL74 cells, and xenogeneic target lymphoma, mouse YAC-1 cells. The TLA treatments were performed in vivo alone, in vitro alone, and in vivo plus in vitro, respectively. In vivo plus in vitro treatments with TLA induced a marked augmentation in cytotoxic activity of spleen cells to FL74 cells. The treatment with TLA in vivo alone showed an enhancement of cytotoxic activity but in vitro alone did not. The cytotoxic effects of TLA-treated spleen cells obtained from the cats which had been previously immunized with live FL74 cells were similar to those of spleen cells from non-immunized cats treated with TLA. However, no increase of cytotoxicity was shown in the response to mouse YAC-1 cells regardless of TLA treatments. These results indicated that the in vivo TLA treatment augmented the cytotoxicity of feline spleen cells against FeLV-producing lymphoma cell.     

Effect of 50 kilobase-plasmid, pKDSC50, of Salmonella choleraesuis RF-1 strain on pig septicemia.

Salmonella choleraesuis strains with and without 50-kilobase plasmid (pKDSC50) were intravenously inoculated into Yorkshire pigs. By the inoculation of 7.2 x 10(5) - 3.5 x 10(7) cells, RF-1 strain with pKDSC50, but not 31N-1 strain without the plasmid, caused a septicemia. The inoculation of 8.7 x 10(9) RF-1 cells killed pigs at 2-4 day postinfection with severe hemorrhage on the whole body. Pigs with a similar number of 31N-1 cells (8.3 x 10(9) cells), showed milder hemorrhage, and they died at 6 day postinfection. These results indicated that pKDSC50 is required for RF-1 strain to express the full virulence causing a heavy cutaneous pig septicemia.     

Improvement of the Culture Conditions for In Vitro Production of Cattle Embryos in a Portable CO2 Incubator

The effects of different concentrations of growth hormone (GH) on in vitro maturation (IVM), fertilization (IVF) and culture (IVC) of bovine oocyte/embryos in CR1aa or CR2aa media using a simple CO₂ incubator were investigated. The IVM/IVF/IVC of oocytes were carried out in the presence of 0, 50, 100 and 200 ng/ml GH in the medium. The proportion of metaphase II oocytes was significantly higher (p < 0.05) in 200 ng/ml compared with 0 ng/ml GH in CR1aa medium (59 versus 85%, respectively), but this effect was not observed under CR2aa. Higher concentrations of GH yielded lower rates of unfertilized ova and thus superior cleavage rates (36.5 ± 0.2 and 63.5 ± 2.0% versus 17.5 ± 0.2 and 82.5 ± 1.5% or 40.4 ± 0.6 and 59.6 ± 1.4% versus 16.6 ± 1.2 and 83.4 ± 6.2% for 0 and 200 ng/ml GH in portable or ordinary incubator, respectively) in CR1aa. This dose‐dependent effect was also observed in the percentages of transferable embryos, although not statistically different (17.2 ± 1.7 versus 27.3 ± 1.8% and 16.6 ± 3.1 versus 26.0 ± 1.4%, for 0 versus 200 ng/ml GH in portable and ordinary incubator, respectively). In contrast to the CR1aa, different concentrations of GH in CR2aa medium did not increase either fertilization or cleavage rates. In fact, higher concentrations of GH in this medium negatively affected the rate of transferable embryos. Hence, percentages of transferable embryos obtained in the portable incubator under 0 or 50 ng/ml GH were higher (p < 0.05) compared with those obtained in 100 or 200 ng/ml GH (35.4 ± 5.7 or 40.5 ± 5.4% versus 22.4 ± 2.4 or 15.5 ± 2.1%, respectively). There was however, no significant difference in the rate of transferable embryos in an ordinary incubator employing CR2aa medium, but the trend was more or less similar to that observed in the portable incubator. Despite the fact that relatively fewer oocytes were employed for the culture in the ordinary incubator, overall results observed employing the simple portable CO₂ incubator were within the range of those obtained in an ordinary incubator; implying that the simple portable incubator can effectively be employed for the in vitro production of bovine embryos under field conditions.