The role of pasteurella spp and of Mycoplasma bovis in respiratory diseases in young cattle

Lors des essais terrains d’un traitement antibiotique chez des veaux d’éle vage atteints de maladies respiratoires, la flore trachéobronchique a été inven toriée à différentes périodes : à l’arrivée, avant traitement et après guérison. Le rôle de l’association synergique Mycoplasma bovis - Pasteurella haemoly- tica Al apparaît clairement. Les conditions d’élevage et la participation de certains virus (RSV) sont encore des éléments importants de la pathogénèse et du pronostic des bronchopneumonies infectieuses enzootiques.When we tried an antibiotic treatment on clinical trials on weaner calves with respiratory diseases, tracheobronchial flora was examined at different moments : on the day of the arrival, before treatment and after recovery. The role of the synergistic association of Mycoplasma bovis / Pasteurella haemo- lytica A1 in the development of troubles appears to be confirmed. Bad breeding conditions and the participation of a virus (RSV) are important components of pathogenesis and prognosis of bovine Endemic Infectious Broncho pneumonia

A longitudinal study of Besnoitia besnoiti infections and seasonal abundance of Stomoxys calcitrans in a dairy cattle farm of southwest France

Bovine besnoitiosis, caused by the cyst-forming apicomplexan Besnoitia besnoiti, is commonly reported in some restricted regions of South-Western Europe, and in larger regions of Africa and Asia. This infection is thought to be transmitted by blood feeding insects and is responsible for major economic losses in cattle production. A recent emergence in Europe, notified in the Centre of France, Spain and Germany, has attracted more attention to this disease. Clinical signs could appear in some animals; however, many infected cattle remain asymptomatic or show scleral-conjunctival cysts (SCC) only. Recent development of serological methods allows carrying out seroepidemiological field studies. In this respect, a long-term investigation was performed in a dairy cattle farm localized in an enzootic area of besnoitiosis of South-western France between March 2008 and May 2009. The objective was to estimate the seasonal pattern of B. besnoiti infections based on the presence of SCC and serology (ELISA and Western blot). In parallel, an entomological survey was conducted to describe population dynamics of Stomoxys calcitrans and Tabanidae species. The seroprevalence determined by Western blot in a cohort of 57 animals continuously present during the whole survey increased from 30% in March 2008 to 89.5% in May 2009 and was always higher than the prevalence based on clinically assessed SCC. New positive B. besnoitia seroconversions occurred throughout the year with the highest number in spring. In addition, many seroconversions were reported in the two months before turn-out and could be associated with a high indoors activity of S. calcitrans during this period

Structure-activity relationships of the N-methylcarbamate series in Salmonella typhimurium.

Aromatic hydrocarbons of low molecular weight, hydroxy and N-methylcarbamate derivatives were tested for mutagenicity by the reversion of histidine-dependent Salmonella typhimurium TA98 and TA1535 in the presence of a rat-liver 9000 × g supernatant fraction. The presence of 2 or 3 aromatic rings resulted in a weak increase in revertants. Hydroxylation and carbamylation of aromatic rings increased the mutagenic activity of these aromatic compounds. In order to evaluate the structure-activity relationship, the specific molecular connectivity indices were calculated. A significant inverse relationship exist between mutagenicity and zero- and second-order specific molecular connectivity indices. Only compounds with second-order specific molecular connectivity indices lower than 0.300 increased mutagenic activity