The effects of enrofloxacin on hepatic microsomal mixed function oxidases in broiler chickens.
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Biomedical subjects
Publications and source records attributed to A Shlosberg.
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The influence of microsomal mixed function oxidases (MFO) on the biotransformation of pesticides was investigated in experiments with perfusion of isolated rat livers and in whole animals. The pesticides examined were 3 organophosphorus insecticides (OP): S-propyl-O-phenyl-O-ethylthiophosphate (heterophos), a mixture of O,O-dimethyl-O-cyclohexylthionphosphate and O,S-dimethyl-O-cyclohexylthiolphosphate (cyclophos), and dithiophosphonate. The indices of NADPH-dependent hydroxylating systems measured in the microsomal fraction of rat liver homogenates were the activity of aniline hydroxylase, aminopyrine demethylase and the amount of cytochrome P-450. It was shown that not only did the specific chemical structure of the OP and induction or inhibition of MFO determine OP activation and detoxification (and thus its biological action), but also the route and frequency of exposure could influence these parameters.
A feral Griffon vulture (Gyps fulvus) was found with tremors, weakness, digit and wing flexion, and an inability to fly. A zero blood cholinesterase activity and a favorable response to treatment with pralidoxime hydrochloride indicated exposure to an anticholinergic pesticide. The bird died after 7 d, and traces of the organophosphate insecticide ethyl parathion were found in the liver and from a blue discolored skin area of the neck. Continuous exposure to ethyl parathion through dermal absorption was presumed the cause of death of the vulture.
An experimental feeding trial was conducted in order to substantiate an hypothesis on the aetiology of a previously unrecorded cardiomyopathic syndrome in beef cattle in Israel. It was believed that residues of the ionophore maduramicin (Cygro; American Cyanamid) in poultry litter fed to cattle, after the maduramicin had been incorporated into broiler feed as a coccidiostat, were the cause of the cardiomyopathy. Three groups of 5 heifers were fed for several weeks (1) poultry litter from a field case, containing 4.8 ppm maduramicin; (2) poultry litter to which maduramicin was added to give a concentration of 12 ppm; (3) poultry litter with no maduramicin (control). Clinical, biochemical, necropsy and histopathological findings showed that maduramicin residues are cardiotoxic, even at the lower level of maduramicin fed, which is commonly encountered in poultry litter in Israel.
1. This work examined the effect of using three different feeding regimens in the prophylaxis and treatment of ascites in fastgrowing broilers stressed by exposure to cold (less than 10 degrees C), itself a potent inducer of ascites. 2. Broilers were exposed to cold in tiered cages in a semi-open poultry shed from the age of 24, 29 or 34 d and from day 35 they were given one of three types of food (pellets, pellets with high energy content, mash). Total mortality and mortality with ascites were recorded and erythrocyte packed cell volume (PCV) and relative weight of the right ventricle were measured (both reliable indices of ascites development). 3. Despite relatively low ambient temperatures and consequent high mortality from ascites, the mash diet was effective both in preventing ascites (prophylaxis) and in treating existing ascites.
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Sprouted barley grains, the waste product of malt extract production, were incriminated as the cause of a lethal (96% mortality) neurotoxic syndrome in sheep fed the grains. Clinical manifestations, comprising tremors, lameness, abnormal gait, paralysis and death indicated a tremorgenic mycotoxicosis. Whilst 50% of the flock died within 17 days, mortality continued over more than 5 months. Pathological findings were limited to neuronal degeneration and necrosis in the midbrain. Germinating grains were shown to be contaminated with growth of Aspergillus clavatus.
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Sheep were dosed with natural and synthetic anticoagulants to prolong prothrombin time (PT) in the one stage PT test. The stability of subsequent values of PT of up to 40 seconds was measured at various times over a 24 hour period in plasma and whole blood stored at 0, 20 and 30 degrees C, representing ideal to unsuitable conditions of sample preparation and storage. In contrast to cautions in the literature, the various treatments had little influence on PT. These findings should encourage the use of PT in field diagnosis and research in sheep by surmounting the tenet of the difficulty in effectively preserving blood samples for PT determinations.
Feedlot calves given monensin in their feed developed an excessive mortality which peaked 3-4 mo after monensin was withdrawn. Typically the calves died suddenly and necropsy revealed areas of paleness in the skeletal muscles (early cases) and in the myocardium (more chronic cases). Histology (in 19 calves) showed swollen myocytes with loss of striation and sarcoplasmic vacuolization, followed by the appearance of necrotic fibres and infiltration with macrophages and neutrophils, and finally local and generalized fibrosis. Calcification was not evident. A differential diagnosis ruled out an etiology of nutritional and toxicological origin, thus leaving the probability of atypical (chronic) monensin toxicosis.
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Several plants causing poisoning in herbivores in Israel have an association with human health. Ferula communis (giant fennel) contains a potent anticoagulant and induces severe haemorrhagic diathesis in grazing ewes, or similar changes in utero in lambs. These and other teratogenic changes have been seen in babies from mothers receiving the anticoagulant warfarin during pregnancy. The Ferula interaction in sheep may be used as a model to study this embryotoxicity in man. Ammi majus (bishops weed) causes severe ophthalmic changes, in particular pigmentary retinopathy in photosensitized domestic fowl. The photoactive principle is currently used in the treatment of psoriasis in man, and such patients should be examined for possible ocular toxicity. Trigonella foenum-graecum (fenugreek) caused myopathy in ruminants and is ingested by certain ethnic groups. Oxalis pes-caprae (Bermuda buttercup) causes large-scale oxalate poisoning in sheep and is avidly eaten by children.
An account is given of three major functions of veterinary toxicology in relation to environmental health. These are: 1) Environmental (epidemiological) toxicology with reference to mass intoxications in domestic animals and wildlife and their role in the early detection of detrimental environmental quality caused by toxic chemicals. 2) Comparative pharmacology and toxicology: The impact of animal poisonings on discoveries in human health or on the development of novel concepts in these disciplines. 3) Regulatory toxicology: The role of the veterinary profession is emphasized in the safeguarding of food with special reference to meat inspection regulations and biological residues in edible tissues.
Healthy turkeys receiving 80 ppm monensin in their feed were injected at 26, 40 and 61 days of age with tiamulin at dosages of 12.5 and 25 mg/kg body weight. The aim of the study was to develop a regime for medicating with tiamulin turkeys receiving monensin in their feed, and which would circumvent the known toxicity created by the simultaneous administration of the two drugs. One injection of 12.5 mg/kg tiamulin up to the age of 61 days or 2 injections of 12.5 mg/kg tiamulin up to 40 days of age caused no mortality or adverse reaction.
An outbreak of hepatic cirrhosis in a flock of young geese was investigated. The affected geese were cyanotic with purple beaks, shanks and footwebs. On post mortem examination severe atrophy of the liver was seen and, histologically, extensive areas of necrosis, cirrhosis and bile duct proliferation were prominent. Liver function tests and serum enzyme levels confirmed that the liver damage was extensive. The findings are compared with those found in aflatoxicosis of other avian species.