[Coccidiosis in lambs: observations in the preventive use of an amprolium-containing medicated feed]. / Coccidiose bij lammeren: waarnemingen bij het preventieve gebruik van een amprolium bevattend gemedicineerd krachtvoer.

The efficacy of preventive in-feed medication with amprolium (2000 ppm) was studied on a farm where clinical coccidiosis in unweaned lambs at pasture has been a problem for the past seven years. Both treated and untreated control lambs had access to the concentrates through creep feeding. In this clinical trial neither the treated group (15-17 mg of amprolium per kg body weight per day for three weeks) nor the control group showed clinical symptoms of coccidiosis. It seems likely that this is attributable to the feeding of concentrates. Nevertheless, the excretion of oocysts by the animals of the treated group was significantly lower than that of the control group. An outbreak of clinical coccidiosis in another group of lambs on this farm was successfully controlled by single drenching, 50 mg.kg-1, followed by the medicated feed. The pharmaceutical availability of amprolium in the concentrates was 95 +/- 1% immediately after preparation and the stability during storage under field conditions for two months was 100% +/- 2%.

The ultrastructural effect of amprolium medication on development of Eimeria adenoeides in turkeys.

The ultrastructural appearance of first-generation schizonts of Eimeria adenoeides was markedly altered in turkey poults fed 0.0125% amprolium-medicated feed. When compared with development seen in unmedicated control birds 48-72 hr postinoculation (PI), most of the schizonts present in the medicated birds were fragmented, contained enlarged nuclei, had swollen endoplasmic reticulum and Golgi apparatus, and showed no budding of merozoites. Other schizonts were almost completely degenerated and contained pyknotic nuclei, dense cytoplasm, and large intracytoplasmic vacuoles containing membrane whorls or lipid droplets. A few mature schizonts were seen in the medicated poults, and these did not appear to differ ultrastructurally from those seen in unmedicated control birds. Ultrastructurally normal second-generation schizonts and the sexual stages were also seen in small numbers in the medicated turkey poults 72-120 hr PI. Mature sexual stages were seen much earlier in medicated turkeys--at 96 hr PI--than in the unmedicated poults.

Clinical and biochemical findings in bovine cerebrocortical necrosis produced by oral administration of amprolium.

Purposing to get some hints on cause and early diagnosis for cerebrocortical necrosis (CCN), CCN was produced in three healthy calves by the oral administration of amprolium. All three calves showed central nervous signs characterized by ataxic gait, clonic spasm, astasia and opisthotonus, from 24 to 49 days after the start of daily administration of 321-418 mg/kg amprolium. They showed bradycardia from about 20 days before the appearance of the nervous signs, which was supposed to be a finding of primary change and to be useful for early diagnosis of CCN. At necropsy of the two calves, large necrotic lesion was found in the cerebral cortex, and tissue thiamine levels decreased significantly, especially in cerebrum and cerebellum. In the other calf, injection with 25 mg thiamine tetrahydrofurfuryl disulfide (TTFD) was proved to be effective for the recovery of clinical signs. No significant changes in thiamine level were recorded in the whole blood, but those in erythrocytes decreased slightly at about a week before the appearance of the clinical signs. No significant alteration of thiamine excretion was observed in urine. Those findings suggest that CCN in calves is caused by thiamine deficiency and that the blood thiamine levels cannot be used for diagnosis of CCN.

[Amprolium residues in eggs following administration of amprolium/ethopabate in laying hens and breeding hens]. / Residuen van amprolium in eieren na toediening van amprolium/ethopabaat aan leghennen en opfokleghennen.

Amprolium may be used as a coccidiostat in rearing hens and is a therapeutical agent used in laying hens. As a result of cross contamination, low amprolium levels may occur in feed. Feed containing a concentration of amprolium ranging from 5 to 250 mg/kg was therefore supplied to groups of laying hens. The amprolium residues in the yolks during and after treatment were subsequently determined. These levels varied from 1.75 mg/kg in the group fed 250 mg/kg to 0.2 mg/kg in the group fed 5 mg/kg. Amprolium levels in the whites of eggs were much lower than those in the yolks. The residues in yolks decreased below detectable levels (less than 0.005 mg/kg) within approximately ten days after treatment. Rearing hens in a tiered wire floor system were given amprolium in their feed until the first egg was laid. Amprolium residues in yolks were detected for well over a fortnight after the onset of laying. The amprolium residues determined in yolk did not exceed US tolerance levels of 8 mg/kg.

Thiamine uptake in isolated schizonts of Eimeria tenella and the inhibitory effects of amprolium.

The uptake of thiamine by isolated second-generation schizonts of Eimeria tenella and by host intestinal cells was found to consist of two components. One was passive and the other apparently an active process. The kinetic constants of the latter were compared in host (Km = 0.36 microM) and parasite (Km = 0.07 microM) and found to be significantly different. Both systems were competitively inhibited by amprolium but showed different affinities for the drug. (Host Ki = 323 microM; parasite Ki = 7.6 microM). Further differences were observed in schizonts of a drug-resistant line of E. tenella. These findings are discussed in terms of the inhibition of thiamine uptake being the basis of the anticoccidial activity of amprolium.

Amprolium for prophylaxis of ovine Sarcocystis.

The efficacy of amprolium against clinical sarcocystosis resulting from Sarcocystis ovicanis was determined in two experiments involving 40 lambs. In each experiment, four lambs were used in each of five test groups--uninoculated unmedicated, inoculated unmedicated, uninoculated medicated (100 mg/kg), inoculated medicated (100 mg/kg), and inoculated medicated (50 mg/kg). Amprolium was provided as a feed additive to each medicated group for 31 days beginning 1 day before oral inoculation with 100,000 S. ovicanis sporocysts. Data from deaths, body temperatures, weight gains, serum protein levels, hematocrits, hemoglobin values, LDH and SGOT values, postmortem examinations, and histological examinations indicated that amprolium at both levels tested reduced the number of deaths and severity of clinical signs of sarcocystosis in experimentally infected lambs as compared with unmedicated controls.

Determination of amprolium in feeds: collaborative study.

The official final action method, 42.028--42.032, for determining amprolium in feeds was modified by a change in the preparation of aluminum oxide for chromatography. A premix containing 0.5% amprolium was collaboratively studied by the modified and the official methods. Compared with the modified method, 87.7% of the drug was recovered from the premix by using the official method. The modification makes possible the assay of premixes as well as finished feeds. The official final action method has been modified to incorporate this change.

Efficacy and compatibility of amprolium and carbarsone against Coccidiosis and blackhead in turkeys.

Amprolium and carbarsone were tested separately and in combination for efficacy in prevention of occidiosis and histomoniasis, respectively. In these studies, amprolium at .0125% in the diet was efficacious in prevention of coccidiosis, and carbarsone had no deleterious effects when fed simultaneously at .0375%. Carbarsone at .0250% was efficacious in prevention of histomoniasis, and amprolium had no deleterious effects when fed concurrently at .025%. These results indicated that both drugs could be used in combination without interference of efficacy against the target diseases.

Eimeria tenella: experimental studies on the development of resistance to amprolium, clopidol and methyl benzoquate.

The development of resistance by the Houghton strain of Eimeria tenella to the anticoccidial drugs amprolium, clopidol and methyl benzoquate has been studied. Resistance to amprolium and clopidol developed more readily in experiments where a large number of coccidia were exposed to the drug, either by increasing the number of oocysts in the inoculum or by increasing the number of birds in the group. When 45 birds were given 2.0 X 10(6) oocysts, resistance to amprolium and clopidol appeared after 6 and 7 passages respectively. In previous experiments, under similar conditions, resistance to robenidine developed after 6 passages, suggesting little difference between these three drugs. Resistance to amprolium and clopidol arose gradually as the concentration of drug was increased, but resistance to methyl benzoquate appeared in a single step from sensitivity to high-level resistance. Both amprolium and clopidol-resistant lines showed an 8-fold reduction in drug sensitivity. Attempts to measure the degree of resistance by calculation of the ED50 were unsuccessful.

[Chemoprophylaxis and therapy of coccidiosis in the rock partridge, Alectoris graeca cypriatis]. / Khimioprofilaktika i terapiia na koktsidiozata po keklitsite Alektoris graeca cypriatis.

A number of coccidiostatica--amprolium (Merek Sharp & Dohme), both for the prevention and treatment, DOT Solubile (By-Gulden) and Esb3 (Ciba Geigy) for treatment--were tested with artificially raised rock partridges on an infected farm. The trials were carried out with a total of 12300 young (12-day-old) birds suffering from spontaneous outbreaks of coccidiosis and 60 such birds with experimental coccidiosis. The comparative study on the results obtained revealed that amprolium produced a good prophylactic effect and a low therapeutic one in cases of clinical coccidioses, used at the rate of 125 mg/kg and offered with the forage mixture. DOT at 30 g/10 1 of water had a pronounced therapeutic effect in the course of 5 days. The preparation Esb3 at the rate of 1 g per one liter of water for 3 days was tested in experimentally induced coccidiosis (E. kofoidi). It produced good therapeutic effects with the highest coccidiosis index ever noted on the second day following infection. It can be applied on occasions of E. kofoidi-induced coccidiosis.

Effect of three coccidiostatics against toxoplasmosis in mice.

Duocoxin, nicrazine and amprol plus showed no therapeutic effect in 50 mice each of which was infected with 25,000 organisms of a virulent Toxoplasma strain.

[Stability of glucose-6-phosphate dehydrogenase in aging of human diploid cells and the laboratory mouse]. / Izmenenie stabil'nosti gliukozo-6-fosfat-degidrogenazy pri starenii diploidnykh kletok cheloveka i laboratornykh myshei.

Glucose 6-phosphate dehydrogenase (E. C. 1.1.1.49) was found to be inactivated by 30% for 25 min the incubation at 37 degrees C in extracts of human diploid cells and mouse liver, and the stability of the enzyme was found to reduce in aging of human diploid cells and mouse. The stability of dehydrogenase of mice treated with "geroprotector", 2-ethyl-6-methyl-3-hydroxypyridine, exceeds the control level.

Nitrification in histosols: a potential role for the heterotrophic nitrifier.

Insufficient populations of Nitrosomonas and Nitrobacter were found in a Pahokee muck soil (Lithic medidaprit) to account for the nitrate concentration observed. To determine if heterotrophic nitrifiers could account for some of this discrepancy, a method was developed to measure the levels of heterotrophic nitrifiers in soil. A population of 4.1 X 10(5) Arthrobacter per g of dry fallow soil, capable of producing nitrite and/or nitrate from reduced nitrogenous compounds, was observed. Amendment of the much with 0.5% (wt/wt) sodium acetate and 0.1% (wt/wt) ammonium-nitrogen as ammonium sulfate (final concentrations) not only resulted in the usual increase in autotrophic nitrifiers, but also in a fourfold increase in the heterotrophic nitrifying Arrthrobacter. Amendment of like samples with N-Serve [2-chloro-6(trichloromethyl) pyridinel] prevented the increase in Nitrosomonas, but not that in the heterotrophic nitrifiers. Nitrate production in the presence of the inhibitor was diminished but not prevented. An Arthrobacter sp., isolated from the muck, produced nitrite when inoculated at high densities into sterile soil, unamended or amended with sodium acetate and/or ammomium sulfate. These data suggest that the heterotrophic population may be responsible for some of the nitrate produced in these Histosols.