Thiamine uptake in isolated schizonts of<i>Eimeria tenella</i>and the inhibitory effects of amprolium

James, Stephanie

doi:10.1017/s0031182000000779

Cited by 27 publications

(23 citation statements)

References 21 publications

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“…According to Rogers (1962), amprolium cannot be pyrophosphorylated because it lacks the hydroxyethyl group of thiamine and therefore, these reactions cannot take place. Thiamine transport in the parasite is more sensitive to amprolium than thiamine transport in the host (James, 1980b). The amprolium resistant line showed decreased sensitivity to the inhibitory effects of the drug and this was thought to reflect changes at the molecular level in the unknown target receptor.…”

Section: Resistance Against Thiamine Mimicsmentioning

confidence: 96%

Anticoccidial drug resistance in fowl coccidia: the state of play revisited

Abbas

Iqbal

Blake

et al. 2011

World's Poultry Science Journal

131

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The development of drug resistance in Eimeria is common because of extensive use of anticoccidial drugs for the control of avian coccidiosis. The significance of chemotherapy is evident from the fact that, in spite of advancement in the field of immunological, biotechnological and genetic methods, prophylactic chemotherapy with anticoccidial drugs is still widely used for the control of coccidiosis. In such situations, new drugs should be available to replace the older ones against which resistance has developed, however it takes a long time to develop any new compounds. It is therefore currently necessary to develop strategies to minimise the emergence of resistance in Eimeria strains and to prolong the effect of available anticoccidial drugs. This paper summarises the resistance status of Eimeria species in different parts of the world and reviews different types of resistance, mechanism of resistance development, factors involved in the development and spread of resistance, management of resistant strains and strategies to preserve the efficacy of the available anticoccidial drugs. Use of vaccines, synthetic and botanical anticoccidials and educating farmers about recommended coccidiosis control practices are discussed in this review, along with the integration of currently available options for the management of drug resistance and, ultimately, the control of coccidiosis.

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Section: Resistance Against Thiamine Mimicsmentioning

confidence: 96%

Anticoccidial drug resistance in fowl coccidia: the state of play revisited

Abbas

Iqbal

Blake

et al. 2011

World's Poultry Science Journal

131

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“…1). Competitive inhibition between the two substances for a transport carrier has been reported across the intestinal border and the cell membranes of micro-organisms (Rindi & Ventura, 1972;James, 1980). Amprolium is used commercially in chicken rearing as a routine addition to the diet to inhibit coccal infections (Ryley & Betts, 1973 synthesized in the rumen.…”

Section: Discussionmentioning

confidence: 99%

“…In an attempt to resolve this problem the effect upon thiamine transport across the blood-brain barrier has been investigated of a close chemical analogue of the vitamin, 1-[(4-amino-2-propyl-5-pyrimidinyl)methyl]-2-picolinium chloride HCl (amprolium). This substance has been found to be a competitive inhibitor of the carrier-mediated transport of thiamine across the mucosa of the small intestine in the chick (Polin, Wynosky & Porter, 1963) as well as that of many other animal species (Rindi & Ventura, 1972), into rat brain slices (Sharma & Quastel, 1965), into isolated rat hepatocytes (Lumeng, Edmondson, Schenker & Li, 1979) and across the cell surface membranes of coccidial schizonts (James, 1980). A preliminary account of this work has been given (Greenwood & Pratt, 1981 [14C]thiamine, so as to raise the blood amprolium concentration above 0 4 mm for the duration of the influx measurement.…”

Section: Introductionmentioning

confidence: 99%

Inhibition of thiamine transport across the blood‐brain barrier in the rat by a chemical analogue of the vitamin.

Greenwood¹,

Pratt²

1983

The Journal of Physiology

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SUMMARY1. The flux of thiamine from the blood into the brain has been measured using a specially devised technique by which a steady raised level of the vitamin, with or without radioactive labelling, can be achieved rapidly and maintained in the bloodstream. This is done by a continuous injection, given at a rate which is adjusted by a pre-determined programme so as to replace the tracer at the rate at which it has been found to leave the circulation in previous experiments.2. A further programme was worked out to maintain, in a similar manner by a separate injection, a steady raised level in the bloodstream of a chemical analogue of thiamine, 1-[(4-amino-2-propyl-5-pyrimidinyl)methyl]-2-picolinium chloride HCl (amprolium).3. In the presence of a high concentration of amprolium the flux of thiamine across the blood-brain barrier was greatly reduced and no longer saturable by raising the blood thiamine concentration up to at least 10/sM. It was concluded that this analogue of thiamine inhibited the saturable component of thiamine transport across the barrier but not the non-saturable component.4. In a further series of experiments, progressively higher levels of thiamine were maintained in the bloodstream and the influx of the vitamin across the blood-brain barrier was measured. From kinetic analysis ofthe results, it was clear that the affinity of amprolium for the transport carrier was of a similar magnitude to that of thiamine itself. That the inhibition was competitive was shown by the way in which it could be overcome if the level of thiamine in the blood plasma was raised sufficiently above the normal.

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“…Amprolium seems especially efficacious during schizogony as then the demand of thiamine is at its highest (James 1980). There is a difference in sensitivity of the thiamine transport system of host and parasite (more sensitive) to amprolium.…”

Section: Products Affecting Cofactor Synthesismentioning

confidence: 99%