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Biomedical subjects

G Ziv

Publications and source records attributed to G Ziv.

At least 91 records · Page 5Linked to original sources
PubMed1980

Availability and usage of new antibacterial drugs in Europe.

The present-day availability and usage of established and new antibacterial drugs approved for clinical and therapeutic purposes in food-producing animals and poultry in the United States and Europe were compared. Presently, 42 such drugs are approved in Europe, 13 of which were approved since Dec 31, 1974. In the United States, 17 such drugs are currently approved, only four were approved since Dec 31, 1974. Most drug products approved in Europe contain two or more antibacterial agents, whereas most of the products approved in the United States are single drug entities. Drugs approved in Europe but not in the United States include sulfonamide and trimethoprim combinations, nafcillin, oxacillin, metampicillin, cephoxazole, cephalonium, cephacetrile, cephalexin, gentamicin, rifamycin SV, nifuroquine, tiamulin, chloramphenicol, colistin, and polymyxin B. Pharmacologic and clinical features of several of these drugs are briefly described.

Animal Diseases↗
PubMed1978

A study of chloramphenicol distribution and residues in dairy cows.

Distribution and residues of chloramphenicol were examined in 29 normal and 15 emergency-slaughtered dairy cows after parenteral injection of 3 chloramphenicol base formulations, using microbiological and chemical assay procedures. Five qualitative test methods for antibiotic residues failed to detect the presence of the drug even in samples collected within 18 hours of treatment at a dose level of 37 mg/kg, and in emergency-slaughtered cows known to have been treated with chloramphenicol before slaughter. The limited usefulness of these methods for the detection of chloramphenicol residues is stressed by observations indicating the presence of chemically measurable concentrations of the drugs (or its metabolites) in the muscle, kidney, liver, bile, and urine 65 hours after treatment. Quantitative microbiological assay procedures for chloramphenicol (sensitivity limits 1.0 microgram/ml tissue fluid) conducted on specimens of kidney and liver samples of cows treated with chloramphenicol (doses approximately 10 to 40 mg/kg intramuscularly) 1/2 ; 1; 3 1/2; 12; 18; 46; and 65 hours earlier were all negative. However, chemical assay procedures (sensitivity limits 0.2 to 3 microgram/ml or mu/g tissue) for chloramphenicol and some of its metabolites detected the drug in these samples as well as in the meat. Chloramphenicol is apparently extensively metabolized in adult bovines. The extended persistence of "chloramphenicol" residues in the carcass is due to the relatively slow elimination rate of the metabolized drug and the poor and slow absorption rate from the intramuscular injection site after treatment, with preparations containing chloramphenicol base dissolved in organic solvents. Examples are given of the predicting of of pre-slaughter carcass withdrawal times on the basis of arbitrary drug tolerance or detection levels.

Animals↗
PubMed1978

Tissue distribution and residues of oxytetracycline in normal and emergency-slaughtered ruminants.

The concentration of oxytetracycline (OCT) in the blood, kidneys urine and meat was determined in a group of clinically normal dairy cows slaughtered at different times after treatment. Drug concentrations were similarly determined in a group of emergency-slaughtered dairy cows and calves. Distribution pattern of the drug in the body, expressed as muscle-drip-to-serum and kidney-cortex-to-serum ratios of the drug concentrations were determined in clinically normal cows and these ratios were compared with the corresponding ratios found in the emergency-slaughtered cows. Attempts were also made to relate changes in the expected ratios to the clinical and pathological findings in the emergency-slaughtered cows. High and persistent levels of the drug in the serum and a slower drug elimination from the body were the main characteristic findings in the sick cows. Drug persistence could not be related to specific tissue uptake or to better drug distribution, although the actual drug concentration in the muscle and the kidney of cows with different clinical pathological findings varied widely and was quite unpredictable. It is concluded that the kinetics of the oxytetracycline residues follow the same pattern as the drug residues in the serum, and these principles seem to apply in normal and in emergency-slaughtered dairy cows.

Animals↗
PubMed1977

Tissue distribution and residues of aminoglycoside antibiotics in normal dairy cows.

The concentration and persistence of streptomycin, dihydostreptomycin (DHS), neomycin, and kanamycin in the body organs of normal dairy cows following intravenous (i.v.) and intramuscular (i.m.) injections were determined by qualitative and quantitative assay methods. The most sensitive qualitative procedure, i.e. Bacillus subtilis BGA at pH 8.0, failed to detect kanamycin in the meat of cows slaughtered 4 hours after i.m. and 6 hours after i.v. injections. This test, however, was positive for the kidneys of cows slaughtered 144 hours after the i.m. administration of neomycin. Low concentrations of neomycin were measured in the meat of cows slaughtered 2 hours and 7 hours after injection. Treatment with streptomycin i.v. resulted in significantly lower renal cortex drug levels than after the i.v. administration of other drugs. Injection of neomycin in a formulation containing benzylpenicillin procaine resulted in higher neomycin concentrations in the renal cortex compared to the levels of the drug found after i.v. injection of the drug. Results are discussed the possible role played by drug interaction on the persistence of aminoglycoside antibiotics in the kidneys after treatment with different dosage forms of these drugs.

Aminoglycosides↗
PubMed1977

Tissue distribution and residues of beta-lactam antibiotics in normal dairy cows.

Tissue residues and concentrations of benzylpenicillin, cloxacillin, ampicillin, amoxycillin, cephapirin, and cephacetrile were determined in normal dairy cows after parenteral administration of several forms of these drugs. Assay methods included the Sarcina lutea Kidney Test of Van Schothorst, the Bacillus subtilis BGA Tests at pH 6.0 and 8.0, the Escherichia coli Test and a Sarcina lutea Test performed at pH 8.0 of the agar, and specific quantitative assay methods. The E. coli test method demonstrated an insensitivity for the beta-lactam antibiotic residues. Identical results in residue testing of meat and kidney were obtained with the B. subtilis BGA tests and S. lutea test at pH 8.0, and these test methods replicated each other. The S. lutea Kidney Test was very often positive at times after treatment when the antibiotics were no longer detected in the meat. The qualitative and quantitative residue data from the renal cortex were higher than the data obtained from the muscle meat. The concentration relationship between renal cortex and muscle meat dependent on the formulation and type of drug used, and on the time of sampling after treatment. After treatment with products containing ampicillin trihydrate and procaine penicillin an unexpectedly long persistence of these drugs in the renal cortex was observed. It is suggested that, in the case of beta-lactam antibiotics, meat tests are more accurate indicators for the residue status of the carcass.

Animals↗
PubMed1977

Comparative clinical pharmacology of amikacin and kanamycin in dairy calves.

The in vitro susceptibility of Escherichia coli, Salmonella sp, Pasteurella multocida, and Pseudomonas aeruginosa strains isolated from young calves and their environment to kanamycin and its semisynthetic derivative--amikacin, was compared by the tube dilution method. The minimal inhibitory concentration of amikacin was two- to fourfold lower than the minimal inhibitory concentration of kanamycin for the Salmonella group B, Ps aeruginosa and P multocida strains examined, whereas the E coli and Salmonella group D strains were eqaully susceptible to the 2 antibiotics. The concentrations of amikacin and kanamycin in the serum of calves after single intramuscular injections at 10, 25, and 50 mg/kg were determined, and differences between the 2 antibiotics were not observed. Intramuscular dosage schedules were calculated, based on the sensitivity of the different bacterial strains and the duration of effective serum drug concentrations.

Amikacin↗
PubMed1977

Distribution of lactate dehydrogenase isoenzymes in normal and inflamed bovine udders and milk.

The patterns of distribution of lactate dehydrogenase (LDH) isoenzymes were determined in normal and inflamed bovine udder tissues, in normal and mastitic milk-leucocytes and serum. LDH1 was the most common isoenzyme found in all the types of tissues examined, normal tissues contained the lowest proportions of LDH5 whereas the inflamed tissues and leucocytes from mastitic milk showed a higher proportion of LDH4 and LDH5. It seems that the origin of the elevated LDH in mastitic milk is the leucocytes and the parenchyma cells of the udder. The significance of the shift in the molecular forms of LDH isoenzymes is discussed in relation to possible alternations in energy metabolism in the inflamed bovine mammary gland.

Animals↗
PubMed1976

The effect of storage at 4 degrees C on antibiotic residues in kidney and meat tissues of dairy cows.

A method is described for the quantitative assay of antibiotic residues in the body of slaughtered farm animals by means of 3 types of agar media and 3 test organisms. With the help of programmed calculation procedures, data from large-scale tests for antibiotic residues could be analyzed accurately and rapidly. The concentrations of penicillin G, ampicillin, amoxycillin, cloxacillin, cephapirin, cephacetrile, neomycin, kanamycin, and oxytetracycline in the kidney, and also of tylosin in meat from the diaphragm muscle of cattle treated parenterally with these antibiotics were measured periodically in samples kept at 4 degrees C for up to 7 days after slaughter. The concentrations of penicillin G, ampicillin, amoxycillin and the cephalosporins in the kidney decreased rapidly upon storage whereas the levels of the other antibiotics remained essentially unchanged. Antibiotic stability in the meat was considerably greater than in the kidney upon storage for 4 days, and neomycin meat tissue levels were not reduced during storage for up to 144 hours. Results are discussed in relation to the conduct of the official qualitative Sarcina lutea Kidney Test and the most desirable procedure for preparing meat samples for assay.

Animals↗