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At least 19 recordsLinked to original sources
PubMed1979

Lasalocid in prevention of turkey coccidiosis.

Lasalocid was tested at graded feed concentrations in controlled battery experiments against single and mixed Eimeria species infections in 2-week-old turykey poults. Eimeria meleagrimitis, E. gallopavonis, E. adenoeides, and E. dispersa infected poults medicated with lasalocid at concentrations of 0.15, .0125, .01, .0075, and .005% were heavier, converted feed more efficiently, showed lower lesion scores (ADI), shed fewer oocysts, and showed reduced or no mortality as compared to the infected, unmedicated controls. Lasalocid activity was similar against the few field isolates tested. Lasalocid responses were dose related, the higher the concentration, the greater the effect. The optimum dose level in these battery studies was approximately .0125%. Lasalocid fed at two times the optimum dose level to poults for a four week period did not have any adverse effect on growth or feed conversion performance.

Animals↗
PubMed1979

Effects of lasalocid and monensin against experimentally induced coccidiosis in confinement-reared lambs from weaning to market weight.

Lasalocid and monensin were incorporated into pelleted feed and evaluated as anticoccidials in confinement-reared lambs from weaning to market weight. A total of 69 lambs were allotted to 3 equal groups that received unmedicated feed (100 mg/kg of food) or monensin-medicated feed (17 to 33 mg/kg). Each lamb was inoculated orally with a suspension of 24,000 oocysts (Eimeria spp) 24 and 52 days after the start of the experiment. Lasalocid and monensin were highly effective (greater than 99%) in eliminating oocysts of 5 species of ovine coccidia used in the inoculum. Treated lambs gained an average of 6 kg more weight (P less than 0.05) per animal than the untreated control lambs and consumed significantly (P less than 0.05) less feed for each kilogram gained. No statistical differences existed between treated groups (P greater than 0.05).

Animals↗
PubMed1978

NMR kinetic studies of the ionophore X-537A-mediated transport of manganous ions across phospholipid bilayers.

Nuclear magnetic resonance spectroscopy has been applied as a method for studying manganous ions transport across the membrane of phosphatidylcholine vesicles. The rates of the ionophore X-537A (lasalocid A)-mediated Mn2+ transport have been measured as a function of ionophore concentration, pH of the vesicle suspension, and temperature. The translocation was found to occur via a neutral complex composed of one manganous ion bound in two ionized X-537A molecules (Mn X2). The activation energy for the overall transport process was determined to be 22 +/- 5 kcal/mol. Also a pKa of 5.0 +/- 0.2 was determined for the ionophore acid dissociation equilibrium in the vesicle suspension.

Anti-Bacterial Agents↗
PubMed1979

Enhancement of the anticoccidial activity of polyether antibiotics in chickens by tiamulin.

The anticoccidial activities of monensin and lasalocid have been studied separately and in combination with tiamulin, a new pleuromutilin derivative. Combinations of constant tiamulin concentration (.0125%) in drinking water with various levels of polyether anticoccidials (6.3 to 125 ppm) in feed and conversely of constant levels of anticoccidials with various concentrations of tiamulin were used. The prophylactic efficacy of these combined treatments in battery raised broiler chickens infected with Eimeria tenella was evaluated. Assessment of the parameters mortality, weight gain, dropping scores, lesion scores, and oocyst output showed that simultaneous application of tiamulin significantly improved the anticoccidial activity of the polyethers. As tiamulin alone is without anticoccidial activity, this phenomenon was considered to result from an interaction between tiamulin and the polyethers leading to a slower metabolic degradation of the latter. Thus tissue levels adequate for maximum anticoccidial activity would be attained with lower polyether dose levels. Experiments using isolated perfused rat liver showed that elimination of monensin was reduced by 60% in the presence of tiamulin.

Animals↗
PubMed1979

Eimeria tenella: anticoccidial action of drugs in birds with surgically closed ceca.

Surgical ligation of chick ceca was used to study the role of absorption and extraintestinal transport in the action of anticoccidial drugs. The administration of drugs in the feed was started after ligation of one of the paried ceca. Birds were inoculated orally with oocysts of Eimeria tenella before cecal ligation or were given bilateral cecal injections of sporozoites after ligation. Cecal lesions caused by the coccidia were evaluated and compared on day 6 postinoculation. Lesions in ligated and unligated ceca were reduced by feeding robenidine (33 ppm), arprinocid (70 ppm), zoalene (125 ppm), aklomide (250 ppm), clopidol (125 ppm), nicarbazin (125 ppm), monensin (120 ppm), salinomycin (60 ppm), and lasalocid (75 ppm). The lesions were more severe in the ligated cecum than in the intact cecum, whether in nonmedicated or medicated birds, but the differences were statistically significant only upon treatment with amprolium, aklomide, robenidine, and clopidol. Generally, however, all drugs except amprolium, significantly reduced the lesions in the ligated cecum in comparison with the control, nonmedicated ligated cecum. Therefore, we concluded that the systemic absorption of most anticoccidial drugs contributes significantly to their efficacy against coccidia in the intestinal mucosa.

Absorption↗
PubMed1979

Factors influencing the assessment of anticoccidial activity in cell culture.

A comparative study has been made of the factors influencing the assessment of anticoccidial potency in vitro against Eimeria tenella using established anticoccidials and arprinocid and some of its analogues. Drugs whose potency depended upon medium composition were amprolium, lasalocid and halofuginone. There was a difference in strain sensitivity with robenidine. Host cell type had an important effect on potency of monensin, decoquinate, arprinocid and its analogues. Arprinocid was active in chick liver cell systems but totally inactive in chick kidney cell systems, although its N-oxide was active in both cell types. Arprinocid-containing medium, conditioned by supporting the growth of chick embryo liver cell cultures, had an anticoccidial effect on E. tenella growing in chick kidney cells. It is deduced that the anticoccidial activity of arprinocid in the chick is due to a metabolite.

Adenine↗
PubMedDate not supplied

Biotransformation of prochiral 2-phenyl-1,3-di(4-pyridyl)-2-propanol to a chiral N-oxide metabolite.

The prochiral compound, 2-phenyl-1,3-di(4-pyridyl)-2-propanol (PPP) labeled with 3H in the phenyl ring, was administered to rats, dogs, and a human subject. Paper chromatography of the urine indicated that a major metabolite common to all three species was excreted. This metabolite was isolated from the urine of chronically dosed dogs and was identified by mass, nuclear magnetic resonance (NMR), and infrared spectrometry as the N-oxide, 2-phenyl-1-(4-pyridyl)-3-(4-pyridyl-1-oxide)-2-propanol. In addition, polarimetry indicated that this metabolite was levorotatory. Examination of the enantiomeric purity of a crystallized sample of the metabolite by NMR spectroscopy of resolvable diastereomeric salts formed with lasalocid revealed the presence of only the levorotatory enantiomer. Accordingly, this metabolic N-oxide formation in the dog was at least stereoselective, and perhaps stereospecific. The N-oxidation of PPP was also demonstrated in vitro with 9000 g supernatant fraction of rat liver fortified with an NADPH generating system, and this reaction was inducible by phenobarbital, indicating that it is mediated by the cytochrome P-450 mixed-function oxidase system. This study, in addition to providing another example of the pyridyl N-oxidation pathway, illustrates the necessity of considering the stereochemical aspects of the metabolism of prochiral drugs.

1-Propanol↗
PubMed1979

Determination of virginiamycin in feeds.

Virginiamycin was extracted from the feed by ethanol-pH 2.5 phosphate buffer (1 + 1). The pH during extraction was adjusted (when necessary) to between 4 and 5. Sample dilutions and the standard dose response line were prepared to contain ethanol pH 6 phosphate buffer (2 + 8), and the test organism was Sarcina lutea. Three feeds (a poultry ration, a swine finishing ration, and a swine starter ration) showed virginiamycin recovery of 88.8--108.9% when standard solutions were added at concentrations of 4.54--90.8 g/ton. The coefficient of variation (4--20%) was larger for low potency feeds (10 g/ton) compared to the higher feeds (100 g/ton). Similarly, excellent recovery was obtained when the swine starter feed was fortified by a commercial premix. Amprolium, roxarsone, and monensin can be present at 20 times the concentration of virginiamycin with little or no interference in the antibiotic determination. Lasalocid at 10 times the concentration of virginiamycin caused a slightly positive bias (recovery, 107.4%).

Animal Feed↗
PubMed1979

[Stability of a number of antibiotics, coccidiostats and growth-stimulating substances during manufacture and storage of (medicated) feed pellets (author's transl)].

The effect of processing and storage on the stability of a number of antibiotics, coccidiostats and growth-stimulating substances, viz. lasalocid, monensin-Na, avoparcin, olaquindox, carbadox, sulfadimidine-Na and lincomycin in (medicated) feeds was studied. Mixtures containing the additives were conditioned by steam at a temperature of 80 degrees C, and pelleted. After each stage in processing and following storage of the pellets for a month, the concentrations of antibiotics, etc., were determined and compared with the concentrations as calculated in the original feed mixtures. The results suggested that none of these substances were very susceptible to the conditions of processing applied. All samples of stored pellets were found to contain at least 90 per cent of the concentrations present in the original feed mixtures, the combined negative effects of processing and storage hardly being beyond the margin of accuracy of the analyses.

Animal Feed↗
PubMed1979

Bacterial lipopolysaccharide depresses spontaneous, evoked, and ionophore-induced transmitter release at the neuromuscular junction.

The neurotoxocity of RNA-free lipopolysaccharide (LPS) extracted from Salmonella Typhimurium (SR-11) was tested at the frog neuromuscular junction using intracellular recording techniques. Spontaneous miniature endplate potential (MEPP) frequency was reduced to 45% of control after 60 minutes in the presence of 10 and 50 micrograms LPS/ml Ringer's solution. Elevation of extracellular [Ca] to 10 mM converted the MEPP frequency response to a biphasic pattern of early acceleration followed by late depression. Evoked endplate potentials (EEPs) were reduced in quantal content until phasic release of transmitter was abolished, while MEPP amplitude and endplate resting potential remained constant. Effects of the potent cation ionophore X537A on MEPP frequency were blocked by 45 minutes of pre-exposure to LPS. Because of its extremely lipophilic character, LPS apparently alters the physical structure of the presynaptic terminal membrane, eventually reducing resting and phasic Ca influx, and isolating the presynaptic terminal from ionophore action.

Animals↗
PubMed1979

Ultrastructural changes in neurohaemal tissue of the stick insect, Carausius morosus, induced by the ionophores Br-X-537 A and A-23187.

The antibiotic ionophores Br-X-537A and A-23187 alter the ultrastructure of neurohaemal tissue on the transverse nerve of the stick insect, Carausius morosus. Br-X-537A induces dramatic changes in the ultrastructural appearance of all three types of neurosecretory fibres present in the neurohaemal tissue. The neurosecretory granules become more electron-lucent and the mitochondria become more electron-opaque. The bounding membrane of the granules is frequently ruptured. A-23187, on the other hand, has no effect on two of the three types of fibres, but does produce an increase in the number of exocytotic profiles in the third. The two ionophores therefore have different effects on the same tissue. The results are discussed in the light of previous work with the use of these ionophores.

Animals↗