Biomedical subjects
H D McCurdy
Publications and source records attributed to H D McCurdy.
Anthelmintic efficacy of febantel combined with praziquantel in dogs.
Ninety-four dogs were randomly assigned to 1 of 6 groups (5 treated and 1 untreated control) for evaluation of anthelmintic efficacy. Three anthelmintic formulations were studied: a febantel paste, a praziquantel paste, and a combination paste containing both active ingredients. Treated dogs were dosed once daily for 3 days. The minimal effective dosages in combination were established as 10 mg of febantel and 1 mg of praziquantel/kg of body weight. At those dosages for the combination, 99.5% to 100% of the major nematodes and cestodes identified (ie, Ancylostoma caninum, Trichuris vulpis, Toxocara canis, Dipylidium caninum, and Taenia pisiformis) were eliminated. Febantel paste (10 mg/kg) alone was ineffective against cestodes (14.2% elimination of Dipylidium caninum) and praziquantel paste (1 mg/kg) alone was ineffective (0% to 2.4% elimination) against nematodes.
Efficacy of a combined paste formulation of praziquantel/febantel against immature Echinococcus granulosus and immature Echinococcus multilocularis.
A combined paste formulation of praziquantel (1 mg/kg of body wt)/febantel (10 mg/kg) given for 3 consecutive days gave 100% clearance of immature Echinococcus granulosus and E multilocularis in experimentally infected dogs. The formulation was extremely convenient to administer. Adverse reactions were not noted in the treated animals.
Anthelmintic effect of febantel/praziquantel paste in dogs and cats.
A paste formulation of 3.4% febantel and 0.34% praziquantel was given in soft food at a rate of 0.29 g/kg of body weight, once daily for 3 days to dogs and cats. Eleven of 12 dogs were naturally infected with Ancylostoma caninum, 10 with Trichuris vulpis, 2 with Toxocara canis, 5 with Taenia sp, and 3 with Dirofilaria immitis. Ten of 11 cats were naturally infected with Toxocara cati, 2 with Ancylostoma tubaeforme, 3 with Taenia sp, 5 with Capillaria aerophila, and 1 with Paragonimus kellicotti. Efficacy was 100% for the removal of A caninum, T canis, and Taenia sp and 99.9% in clearance of T vulpis in dogs, and 100% in removal of A tubaeforme, T cati, and Taenia sp in cats. In dogs, Dirofilaria appeared unaffected, and in cats, there was no apparent effect on Capillaria or on Paragonimus. The paste formulation given in soft food was well tolerated and without observable adverse effects.
Effect of febantel against Ancylostoma caninum and Trichuris vulpis infections in dogs.
Febantel was administered as a 3.4% paste to 45 dogs infected with 1 or more nematode species, which included Ancylostoma caninum and Trichuris vulpis. Dosage levels of 5, 10, or 15 mg/kg of body weight daily for 3 consecutive days for a total of 15, 30, or 45 mg/kg were administered. At 15 mg/kg, all dogs were completely cleared of all nematode and cestode infections, including A caninum, T vulpis, Uncinaria stenocephala, Toxocara canis, Toxascaris leonina, Taenia sp, and Dipylidium caninum, except for 1 Physaloptera sp adult. The 2 other dosage levels produced somewhat lower efficacy, with the 5 mg/kg being the least effective. The paste appeared palatable to the dogs and there were no apparent adverse effects.
Effectiveness of a topical antifungal agent (clotrimazole) in dogs.
An infection of Trichophyton mentagrophytes was induced in 13 dogs, and of Microsporum canis, in 9 dogs. After the lesions became established, they were assigned to a group for clotrimazole treatment, miconazole treatment, or no treatment. Treatments were applied one daily for 28 days, using a double blind method. The lesions were evaluated by daily scoring of severity and by semiweekly culturing throughout the treatment period. Compared with untreated controls, the response to clotrimazole was significantly better from day 11 until the end of the study. The response to clotrimazole equaled or occasionally exceeded that to miconazole.
Summary of safety evaluations for praziquantel in dogs.
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Recovery of quenched radioactivity from thin-layer chromatographic plates. An improved assay for cGMP phosphodiesterase in Myxococcus xanthus.
Ammonium bicarbonate was found useful in extracting a variety of radiolabeled compounds from thin-layer chromatographic plates. The technique significantly increased the sensitivity of the assay for cyclic nucleotide phosphodiesterases. This method was used to show unequivocally, the presence of cGMP phosphodiesterase in vegetative cells of Myxococcus xanthus.
The function of fimbriae in Myxococcus xanthus. I. Purification and properties of M. xanthus fimbriae.
Myxococcus xanthus fimbriae have been purified and characterized as part of a study of the function of fimbriae in this prokaryote. Myxococcus xanthus produced two types of fimbriae, termed flaccid (F) and rigid (R) on the basis of electron microscopy. F and R fimbriae differed slightly in their response to pH and freeze-thaw regimes but were similar in their resistance to hydrolytic enzymes, amino acid composition, molecular weight, carbohydrate content, and antigenic determinants. Although the precise relationship between F and R fimbriae is unknown, the possibility is considered that F fimbriae might represent a "contracted" form of the R type. Studies designed to determine fimbriae function in M. xanthus are described in an accompanying report.
Demonstration of positive chemotaxis to cyclic GMP and 5'-AMP in Myxococcus xanthus by means of a simple apparatus for generating practically stable concentration gradients.
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The function of fimbriae in Myxococcus xanthus. II. The role of fimbriae in cell-cell interactions.
Anti-fimbriae antiserum specifically inhibited swarming but no gliding motility per se in Myxococcus xanthus. However, formation of motile aggregates on agar and clumps in liquid media correlated with the presence of fimbriae. Ethylenediaminetetraacetic acid which inhibited swarming also inhibited fimbriae formation. Direct electron-microscopic observations revealed that fimbriae establish contact with apposing cell surfaces. Intact but not depolymerized fimbriae exhibited hemagglutination activity against guinea pig erythrocytes. This activity was inhibited by mannose, N-acetyl-D-galactosamine, and to a lesser degree by fructose, raffinose, melibiose, and alpha-methyl-D-mannoside. It is concluded that fimbriae are organelles which function to establish and maintain intercellular contacts, perhaps by a lectin-like function, during the coordinated movement of cell aggregates' (swarming) in myxobacteria. This hypothesis is supported by the observations of other workers that genes determining movement of cells in groups also control fimbriation in M. xanthus.
Cyclic nucleotides, cyclic nucleotide phosphodiesterase, and development in Myxococcus xanthus.
Exogenous cyclic nucleotide phosphodiesterase (PD) accelerated fruiting body (FB) formation and increased territory size of aggregates in Myxococcus xanthus. Both guanosine 3'5'-monophosphate (cGMP) and guanosine 5'-monophosphate (GMP) were antagonistic to the PD effect. Adenosine 3'5'-monophosphate (cAMP) increases FB numbers twofold in the absence but not in the presence of PD. PD induction is not affected by methionine or isoleucine, which inhibit, or by threonine, which stimulates, FB formation. There is an increase and subsequent decrease in cAMP levels during early glycerol-induced microcyst development but 10 mM theophylline or caffeine not only inhibited microcyst development but induced germination in the presence of glycerol. On the basis of these results and the reports of other investigators a tentative model is proposed based on a dual role for cyclic nucleotides in the development in M. xanthus.
Fimbriation in gliding bacteria.
Of twenty-two strains of gliding prokaryotes examined, all but three were found to possess polar fimbriae. Fimbriae were not observed on two gliders, while Chloroflexus aurantiacus bore abundant peritrichous fimbriae. In some gliding bacteria, fimbriae were associated with 'holes' surrounded by an electron-transparent collar bearing 12 spike-like projections.
The diguanosine nucleotides: do they exist in aquatic fungi?
The aquatic fungi Achlya ambisexualis and Blastocladiella emersonii were grown in the presence of 32Pi and the 32P-labeled acid-soluble nucleotide fractions were analyzed by ion-exchange chromatography on DEAE-cellulose. Selected column fractions containing diguanosine tri- and tetra-phosphates (Gp3G and Gp4G) added as chromatographic markers were analyzed further for 32P by chromatography and (or) enzyme hydrolysis. The results of these experiments clearly indicate that neither Gp4G nor Gp3G is synthesized during vegetative growth of these organisms and cast doubt on the hypothesis that diguanosine nucleotides are important metabolic regulators in fungi.
Controlled critical anthelmintic evaluation of mebendazole powder in the dog.
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Critical and clinical trials of mebendazole and trichlorfon in the horse.
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The isolation and characterization of gliding motility mutants of Myxococcus xanthus.
Nonmotile and motility-altered mutants of Myxococcus xanthus have been obtained by the use of chemical mutagens, ultraviolet irradiation, and a procedure for selective spontaneous mutants. As judged by their behaviour on a variety of growth media, in both plate and slide culture, the mutants were divided into four groups. One group contains mutants which are truly nonmotile. Myxococcus xanthus NM, previously described as a nonmotile mutant, may be similar to type 3 mutants (described in text).
Evaluation of mebendazole in paste formulation in the horse.
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