Persistence of gentamicin residues in milk after the intramammary treatment of lactating cows for mastitis

This study was designed to investigate persistence of gentamicin residues in milk after the intramammary treatment of lactating cows for mastitis. Milk samples were collected at a 1-d interval after the last administration from 34 individual cows that had received intramammary infusions of gentamicin. The doses and treatment times evaluated in this study represented those that have been applied by veterinarians in practice. The tetrazolium chloride assay was used to determine whether there were sig-nificant residues of the antibiotic in the samples. Persistence of detectable drug residues in milk from 33 cows (28 cows, <6 infusions at≤0.7 g gentamicin; and 5 cows, 2 infusions at 0.8 g gentamicin) did not exceed 5 d; but 1 cow (5 infusions at 0.8 g gentamicin) had detectable residues in its milk for 9 d. Our results suggest that a 5-d milk withdrawal period might be insufficient to secure the clearance of the contamination of gentamicin, because treatment times and dosages contribute to the antibiotic clearance. A larger scale of samples are needed for further investigations.     

Comparative effect of olive oil and fish oil supplementation in combating gentamicin induced nephrotoxicity in rats

The present study is related to the comparative effects of fish oil and olive oil supplementation on gentamicin induced nephrotoxicity in rats. Three treatment groups (Pretrement, Co-treatment and post treatment) were chosen for the study. Nephrotoxicity in rats was induced by intraperitonial administration of gentamicin (80 mg/kg/d) for 3,5,7,10,& 12 consecutive days. The animals were sacrificed 12 hrs after last treatment in each group. The maximum nephrotoxicity was developed on 10 days treatment of gentamicin. For each group a control group was taken without any oil or gentamicin treatment. Beneficial effects of oils were evidenced by reduced serum urea and creatinine concentrations in the group receiving oils compared to the non oil treatment animals receiving gentamicin only. Further, the changed values of alkaline phosphatase and acid phosphatase activity retumed to normal in kidney and liver tissue homogenates after fish and olive oil treatment. In this study, it was found that co-treatment of fish and olive oil is more effective antagonist of gentamicin induced nephrotoxicity. However fish oil was found to be more effective. Hypercholesteromia associated with gentamicin induced nephrotoxicity is also lowered by oil supplementations. The beneficial effects of these oils are due to counteracting effect of the biochemical alterations induced by the drug.     

庆大霉素功能组分的定量分析方法研究

针对目前庆大霉素功能组分含量检测方法的成本昂贵和使用仪器的限制,建立了一种快速经济准确的薄层色谱结合比色法,以甲醇-氯仿-25%氨水（1∶1∶1）为展开剂,碘蒸汽一次显色,收集斑点以乙酰丙酮及甲醛为显色剂,进行二次显色,并建立420nm处的浓度-吸光度曲线。结果表明,庆大霉素在2—100mg范围内线性关系良好r=0.9986,三组分含量测定误差分别为0.188%、0.265%、3.701%。本法仅使用最简便宜得的仪器与药品就能够对庆大霉素各功能组分进行定量分析测定,适合于工业分离中检测应用。