Annales de recherches veterinaires. Annals of veterinary research最新文献

Virulence factors and phenotypes of 61 strains CNF1+ were investigated. Eighty-nine percent of the strains produced an aerobactin and were resistant to the bactericidal activity of sheep serum, both of which are properties of septicemic strains of E coli. None of the strains reacted either with DNA probes corresponding to the enterotoxins STaP, STb, LT-I and LT-IIa, or to the verotoxins VT-I and VT-II. None produced the adhesins K99, Att25 (FY or F17) and Att111. The great majority (93.4%) of the CNF1+E coli possessed both properties. These properties allow CNF1+ to be distinguished from CNF-E coli.

Escherichia coli B41 (O101: K99: F41: ST+) adheres to HeLa 229 cells in a diffuse pattern. Heat-killed (100-105 degrees C) Lactobacillus acidophilus (Lactéol strain) was found to inhibit this adhesion in a dose-dependent manner. This inhibitory action was lost after lysis of the L acidophilus, suggesting steric hindrance of E coli adhesion sites rather than competition for a common binding site. A thermostable factor (100-105 degrees C) excreted by L acidophilus into the medium may be required for the adhesion of L acidophilus to HeLa cells, and for the inhibition of adhesion of E coli to these cells.

To implement a new macrofilaricide, treatment of heartworm infection or disease in dogs was checked in all the clinical situations ie from subclinical to severe disease. After preliminary toxicity and efficacy models on experimentally infected dogs, in addition, to the reference posology (2.5 mg of melarsomine (RM 340)/kg twice, 24 h apart by deep IM injection) a more practical program for vet practitioners was suggested (2.2 mg/kg twice, 3 h apart) using modelization of the pharmacokinetic data. The two treatments were equivalent as shown on models with experimental infection of dogs, critical tests on naturally infected dogs and clinical trials in veterinary practice. We advise using specific and well adapted therapeutic programs for each of the clinical classes (class 1: subclinical, class 2: moderate, class 3: severe). The safety margin is respectively x 3 or x 2.5 in contrast with thiacetarsamide which, being hepatotoxic, has no safety margin, and sometimes is nephrotoxic at the recommended dose. RM 340 is fully effective on D immitis adults (even on young ones of 7 months old) and L5 immatures (4 months old) when thiacetarsamide is poorly effective on 7 months or ineffective on 4-month-old parasites. Clinical trials in veterinary practice showed that the programs are well adapted to many clinical situations. The product is effective, relatively safe and easy to handle by IM injection. Preliminary results show its possible use as tactical treatment (2.2 mg/kg twice, 3 h apart) twice a year in mid August and December-January to prevent heartworm disease.

Lambing in small ruminants is a time of high lentivirus expression; infected mononuclear phagocytes are frequent in colostrum and milk. We have studied mammary secretions in 5 multiparous ewes and shown that infected macrophages in milk are accompanied by an augmentation of leucocyte number. The lymphocyte CD8 subpopulation increased in size simultaneously with the onset of infected cell excretion. The udder infection by coagulase negative staphylococci did not modulate milk lymphocyte content. Although infected cell excretion was restricted to one half of the udder, virus-specific lesions were found in both udder halves. Milk leukocytes changes are a marker of infected macrophage presence; they do not control lentivirus spread.

Estimation of serum creatine kinase isoenzyme activity was used as a selection criterion for stress sensitivity in pigs 8-12 weeks of age, classified for stress susceptibility as positive to halothane anaesthesia. Standardized stress was provoked by administration of adrenocorticotropic hormone or synstigmine. The experiments were performed under experimental conditions in permanently catheterized animals and in a field trial. It was shown that the stress inductors can be used as a selection criterion for stress sensitivity in catheterized animals by estimation of the CK-MM isoenzyme activity 20-24 h after administration of the inductor. In cases where the individual reaction to halothane anaesthesia is unclear and non classifiable, CK-MM isoenzyme assay performed before and 24 h after the halothane test, may also be useful under practical conditions as an additional indicator of stress sensitivity.

The morphological variations of rat thyroid follicles after treatment with either thyroxin or propylthiouracil were evaluated by histomorphometry. A silver impregnation technique allowed a precise visualization of thyroid follicles on histological sections. The histomorphometric values (cell height, follicular diameter, percentage of epithelial cells) were obtained using a semi-automatic image analyser. The statistical tests used were analysis of variance (Fisher's test) and the Newman-Keuls tests. The results obtained showed that thyroxin treatment did not lead to any modification in histomorphometric values. Propylthiouracil, on the contrary, caused profound alterations in the morphology of thyroid follicles and in particular an increase in the height of the follicular epithelium. These changes were induced by a deficiency in thyroid hormones leading to an increase in thyroid-stimulating hormone (TSH) release. This study shows that with rigorous methodology, histomorphometry is adaptable to the requirements of a simple and reproducible evaluation of substances capable of causing functional perturbations and their effects on the thyroid gland.

Nine weeks after weaning, 12 lambs were randomised to 2 groups, each consisting of 6 animals. One group received a diet containing 213.9 mg/kg of fluor (F) in the form of sodium fluoride (NaF) and the other group received a diet containing 212.3 mg/kg of fluor in the form of sepiolite. The 24 h time courses of plasma fluoride concentrations showed that after feeding the average peak plasma concentration of the NaF-fed group was 0.75 microgram F/ml; that of the sepiolite-fed group was 0.35 microgram F/ml. The 12-h area under the plasma concentration curve (AUC) values in the NaF-fed group were higher with statistical significance (P less than 0.001) at each time point. Compared with fluoride from NaF, the relative bioavailability of fluoride from sepiolite was found to be very weak.