Enzootic occurrence of chloramphenicol-resistant Salmonella typhimurium var copenhagen in calf population

Chloramphenicol (CP)-resistant Salmonella typhimurium var copenhagen was frequently isolated (44.1 to 76.7%) from dead, diseased, and healthy calves on 3 farms in 1973 in northern Japan. On 2 of the farms, CP-resistant salmonella appeared suddenly during an epizootic of salmonella infection, and persisted. Of 87 CP-resistant to tetracycline (TC), streptomycin (SM), and sulfonamides (SA), and the remaining 13 isolates from dead calves on a farm were resistant to TC, SM, SA, and kanamycin (KM). Resistance patterns of all CP-resistant isolates were transferred completely.

Modification by drugs of the secretagogue effect of dopamine on the pancrease

1 The specific stimulating action of dopamine and L-DOPA on exocrine pancreatic secretion was further investigated in the isolated blood-perfused canine pancreas.2 6-Hydroxydopamine (100 mug, i.a.) stimulated the secretion but was far less potent than dopamine. Epinine (0.3-1 mg. i.a.), alpha-methyldopamine (10-300 mug, i.a.) and octopamine (10-300 mug, i.a.) were ineffective.3 alpha-Methyldopa (30 mg, i.a.) inhibited the stimulating effect of L-DOPA (1-3 mg) on pancreatic secretion.4 Apomorphine (1 mg, i.a.) attenuated dopamine-induced (1-30 mug) pancreatic secretion but did not antagonize secretin-induced (0.03-0.3 units) or pancreozymin-induced (0.3-1 units) secretion.5 These observations suggest that L-DOPA is probably converted to dopamine to stimulate the exocrine pancreas, and that dopamine interacts with the specific receptors.6 The noradrenaline and dopamine content of the canine pancreas was estimated in controls and in dogs treated with secretin, reserpine, L-DOPA or alpha-methyldopa. The values for dopamine and noradrenaline in controls were 139 +/- 6 and 375 +/- 40 ng/g tissue (n=13), respectively. Reserpine reduced the noradrenaline content of the pancreatic tissue without affecting the dopamine content. L-DOPA or secretin caused a significant increase in the dopamine, but not in the noradrenaline content. It is suggested that dopamine has a physiological function in the pancreas which is independent of that of the noradrenaline-containing nerve fibres.

Effects of enzyme inhibitors of catecholamine metabolism and of haloperidol on the pancreatic secretion induced by L-DOPA and by dopamine in dogs

1. Effects of inhibitors of DOPA decarboxylase, dopamine beta-hydroxylase and monoamine oxidase, and haloperiodol on the secretion of pancreatic juice induced by L-DOPA and dopamine were studied in preparations of the isolated blood-perfused canine pancreas.2. The increased secretion induced by the infusion of L-DOPA (100 mug/min) was completely antagonized by Ro 4-4602 (300 mug), a DOPA decarboxylase inhibitor.3. The secretogogue effect of dopamine (1-10 mug) intra-arterially was not affected by Ro 4-4602, but was enhanced by the infusion of fusaric acid (100 mug/min), a dopamine beta-hydroxylase inhibitor.4. The increase in the secretion induced by dopamine (1-10 mug) was enhanced by treatment with nialamide (100 mg/kg), a monoamine oxidase inhibitor, given intravenously.5. Haloperidol (1 mg) intra-arterially attenuated the dopamine-induced pancreatic secretion.6. It is concluded that L-DOPA is converted to dopamine in the acinar cells which causes an increase in the secretion of pancreatic juice, thus the intracellular level of dopamine may be controlled by enzymatic equilibrium.