[Evaluation of the tetracycline residues in pasteurized milks distributed in Tehran by HPLC method]

With developing new methods of animal husbandry and increasing the prevalence of diseases, using of antibiotics becomes common in assurance of growth and prevention of systemic diseases and mastitis in dairy herds. Ignorance or negligence of withdrawal time or using more antibiotics than prescribed, are two common causes of antibiotic residues. Due to the harmful effects of drug residues on human health, it is important to monitor their residues in foods. 56 pasteurized milk samples of different brands have gathered from Tehran retailers haphazardly. Screening test performed by Delvotest kit and the positive samples referred for HPLC test. The results of screening test showed the presence of different kinds of antibiotics in 33.93% of samples. HPLC determined that 26.3% of positive samples [8.93% of total samples] were contaminated by tetracyclines more than Maximum Residue Level/Limit [MRL] and other samples had other antibiotics. According to dairy per capita consumption of Iranians, these rates of contamination affect considerable part of population especially vulnerable groups like children, pregnant women, elderly and patients. This research shows the necessity of legislative and food inspecting organizations to control and minimize these kinds of contaminations. More research is recommended on other dairy foods

Paraoxonase inhibition by propranolol

There are many evidences that human serum paraoxonase activity modifies plasma lipid profile and paraoxonase has an antiatherogenic property. Non-selective beta-blockers affect plasma lipid profile too, but they have atherogenic property when patients take these drugs in long term. In this study the effect of propranolol, a non-selective beta-blocker, on paraoxonase activity was investigated. Lineweaver-Burk and secondary plots were drawn and showed that propranolol is a mixed non-competitive inhibitor of paraoxonase