Enzyme-linked immunosorbent assay for screening the plasma residues of tetracycline antibiotics in pigs.

The recommended therapeutic doses of three kinds of tetracyclines, oxytetracycline (OTC, withdrawal period, 10 days), chlortetracycline (CTC, withdrawal period, 5 days) and tetracycline (TC, withdrawal period, 5 days), were each administered to a group of 15 pigs. Blood was sampled before drug administration and during the withdrawal period. The concentration of tetracyclines in plasma, determined by semi-quantitative ELISA, was compared with that of internal standard (10 ppb as oxytetracycline). The absorbance ratio of internal standard to sample (B/Bs) was employed as an index to determine the tissue residues in pigs. All 45 plasma samples from nontreated pigs showed negative in the residue of any of three tetracycline antibiotics. OTC was detected in plasma of pigs treated until the 8th day, CTC until the 4th day, and TC was detected until the 3rd day of its withdrawal period. The present study showed that the semi-quantitative ELISA easily be adopted in predicting tissue residues for tetracycline antibiotics in live pigs.     

A model to study the effect of certification of planting material on the occurrence of leek rust

Based on a simple model, the possible effects of certification of planting material on the occurrence of leek rust in a region can be derived from information on the proportion of infected fields (v) and the proportion of newly planted fields with infected planting material (i) in that region. Ifv i, certification of planting material will be highly effective.     

Inhibition of chitin synthesis by two 1-(2,6-disubstituted benzoyl)-3-phenylurea insecticides. II

The knowledge of the biochemical mode of action of 1-(4-chlorophenyl)-3-(2,6-difluorobenzoyl)urea (diflubenzuron) is presented, explaining the insecticidal effect. Like its structural analog, 1-(2,6-dichlorobenzyl)-3-(3,4-dichlorophenyl)urea (Du 19111), it inhibits chitin synthesis in the cuticle of larvae. Virtually complete inhibition was demonstrable 15 min after the application of diflubenzuron. Neither diflubenzuron nor Du 19111 has any effect upon chitinase activity either in vivo or in vitro. The insecticidal effect upon the cuticle, therefore, must be explained as an inhibition of chitin synthesis and not as an activation of chitin degradation. In contrast to the action of Du 19111, no accumulation of N-acetylglucosamine occurs upon treatment of larvae with diflubenzuron. Similarities and differences in the mode of action of both compounds are discussed, together with other effects reported in the literature.     

云南省马铃薯晚疫病菌的交配型、抗药性及生理小种分布的研究

 从云南省陆良县、建水县和南涧县采集2000年秋播的马铃薯晚疫病标本,分离获得124个致病疫霉菌株,连同1999~2000年分离自昆明、曲靖等地的春播马铃薯晚疫病的10个菌株共134个,采用常规技术对这些菌株进行了交配型、抗药性及生理小种的研究。交配型测定结果为:陆良县的18个菌株中有3个为A₂交配型,其余15个菌株为A₁交配型,建水县和南涧县的106个菌株及昆明、曲靖1999~2000年的10个菌株都是A₁交配型。测定了83个菌株对瑞毒霉(metalaxyl)和烯酰吗啉(dimethomorph)的抗药性,结果有12.0%的菌株对瑞毒霉表现抗性,16.9%表现中抗,71.1%表现敏感,其中陆良、昆明和曲靖的抗瑞毒霉菌株的比例大于建水和南涧的抗药性菌株的比例;所测定的83个菌株都对烯酰吗啉表现敏感。生理小种鉴定结果表明,云南晚疫病菌为3.4、0、3和4生理小种,分别占鉴定菌株总数的48.0%、32.5%、15.6%和3.9%。但南涧仅发现3.4和0小种,而昆明有0、3、3.4和4小种,陆良有0、3和3.4小种,可见昆明和陆良地区的晚疫病菌生理小种比南涧地区的生理小种的组成更趋多样。     

Effects of Dietary Supplementation of Barodon on Growth Performance,Innate Immunity and Disease Resistance of Juvenile Olive Flounder,Paralichthys olivaceus,Against Streptococcus iniae

This study was conducted to evaluate the effects of dietary supplementation of Barodon, an anionic alkali mineral complex, on growth, feed utilization, humoral innate immunity and disease resistance of olive flounder. A basal experimental diet was used as a control and supplemented with 0.1, 0.2, 0.3, 0.4, or 0.5% Barodon. Triplicate groups of fish (26.4 ± 0.2 g) were fed one of the diets to apparent satiation twice daily for 10 wk. The growth performance was enhanced (P < 0.05) linearly and quadratically in fish fed diets containing Barodon compared with that in fish fed the control. Feed utilization was significantly improved by Barodon supplementation. Serum lysozyme and antiprotease activities were increased quadratically in Barodon fed groups. Also, significantly higher superoxide dismutase activity was found in Barodon‐fed fish. Dietary supplementation of 0.1–0.3% Barodon resulted in significant enhancement of fish disease resistance against Streptococcus iniae. The findings in this study indicate that dietary supplementation of Barodon can enhance growth, feed utilization, innate immunity, and disease resistance of olive flounder and that the optimum level seems to be 0.1% in diets.     

New technique of sex preselection for increasing female ratio in boar sperm model

In this study, we tried to optimize the porcine semen extender conditions to maximize the differences between live X chromosome-bearing (X) spermatozoa and to Y chromosome-bearing (Y) spermatozoa without a decline in the fertility rate at different pH conditions during storage. We observed the viability of X and Y boar spermatozoa in acidic (pH 6.2), original (pH 7.2), and alkaline condition (pH 8.2) for 5 days to investigate the effect of storage conditions on the X to Y spermatozoa ratio. The functional parameters of spermatozoa were also examined to evaluate sperm quality. Sperm motility was preserved at pH 7.2 and pH 6.2 for 3 days, while sperm motility at pH 8.2 decreased significantly after 2 days. Non-capacitated spermatozoa increased while capacitated spermatozoa decreased during storage. Sperm viability decreased significantly duration-dependent under all pH conditions, but there was no significant difference during storage at pH 6.2 and 7.2. The X: Y ratio of live spermatozoa in acidic condition was maximized (1.2:1) without affecting the sperm function and fertility-related protein expression after 2 days compared to original conditions. Moreover, insemination of sows using acidic extender increased the number of female pups on days 1 and 2 of preservation. These results indicate that the production of female offspring may increase when acidic BTS is used for 2 days without affecting the success rate of AI. Above all, this method is simple and economical compared to other methods.     

Association between weight change during initial chemotherapy and clinical outcome in dogs with multicentric lymphoma

The majority of the known prognostic factors in dogs with lymphoma have been evaluated before treatment commences or at the time of diagnosis. Prognostic factors evaluated during the initial phase of treatment are less described but may provide important clinical information. In this retrospective study, 82 canine lymphoma patients were categorized according to the weight change between diagnosis and after 5 weeks of chemotherapy. Dogs that gained greater than 5% or lost greater than 5% of initial body weight were categorized as increased‐ or decreased‐weight groups, respectively. Those in which weight changed less than 5% were categorized as the maintained‐weight group. The median progression‐free survival (PFS) in the increased‐weight group, maintained‐weight group and decreased‐weight group was 226, 256 and 129 days, respectively. The decreased‐weight group had significantly shorter PFS than the increased and maintained groups (P = .023, P = .003, respectively). The median survival time (ST) in the increased‐weight group, maintained‐weight group and decreased‐weight group was 320, 339 and 222 days, respectively. There was no significant difference in ST among the three groups (P = .128). In Cox‐regression results, weight change group and initial body weight were significant risk factors associated to PFS (P = .007, P = .001, respectively) while only patient's initial body weight was a significant risk factor to ST (P = .013). In conclusion, evaluation of initial body weight and weight changes over time can provide valuable information regarding PFS and ST in dogs with multicentric lymphoma.     

Comparison of antibody titers in rabbits following immunization with inactivated influenza virus via subarachnoidal or subcutaneous route

Rabbits were immunized with inactivated influenza virus via the subarachnoidal (SA) or subcutaneous (SC) route, and the antibody titers in cerebrospinal fluid (CSF) and serum were assayed. There were no nervous signs or morphological lesions related to SA immunization. In the SC group, the antibody titer was elevated in serum, but not elevated in CSF. In the SA group, the antibody titer was significantly elevated in serum and even in CSF, and their antibody titers were much greater than in the SC group. The present results suggest that intrathecal immunization is more effective than SC immunization at inducing a protective immune response against the transneural spread of viruses.