Estimating the Rates of Acquisition and loss of Resistance of to Antimicrobial Drugs in Pre-Weaned Dairy Calves.

The objective of this study was to investigate the effect of the antimicrobial drugs (AMD) on the shedding of resistant Enterobacteriaceae in feces of pre-weaned dairy calves. The AMD considered were ceftiofur, administered parenterally, and neomycin sulfate added in milk replacer and fed to calves during the first 20 days of life. Fifty-five calves, aged one to three days, were enrolled and followed to 64 days.

Effect of Antimicrobial Treatment on the Dynamics of Ceftiofur Resistance in Enterobacteriaceae from Adult California Dairy Cows.

Dairy farm use of antimicrobial drugs (AMD) is a risk for the selection of antimicrobial resistance (AMR); however, these resistance dynamics are not fully understood. A cohort study on two dairy farms enrolled 96 cows with their fecal samples collected three times weekly, for the first 60 days in milk. Enterobacteriaceae were enumerated by spiral plating samples onto MacConkey agar impregnated with 0, 1, 8, 16 and 30 µg/mL ceftiofur.

Gestational exposure to excessive levels of dexamethasone impairs maternal care and impacts on the offspring's survival in rats.

Administration of dexamethasone (DEX) during late gestation is a model to study growth restriction in rodents, but the pup's mortality index can be high, depending on DEX dosage, and little is known about the effects of DEX on maternal care (MC). Considering that an inadequate MC can also contribute to pup's mortality in this model, we evaluated the effects of DEX on dams' behavior and its consequences on offspring survival. We also investigated whether the cross-fostering of pups from dams treated or not with DEX could improve pup's survival.

Ingestive and locomotor behaviours induced by pharmacological manipulation of -adrenoceptors into the median raphe nucleus.

The present study evaluated the involvement of α-adrenoceptors of the median raphe nucleus (MRN) in satiated rats, in food and water intake and motor behaviour. Control groups were treated with saline (SAL) or adrenaline (ADR), injected into the MRN seven minutes after injection of the vehicle used to solubilize the antagonists, propylene glycol (PLG) or SAL. Experimental groups were treated with an α-adrenoceptor antagonist, prazosin (α1, 20 or 40 nmol) or yohimbine (α2, 20 or 40 nmol) or phentolamine (non-selective α, 20 or 40 nmol), followed (later) by injection of ADR or SAL.

Blockade of median raphe nucleus α1-adrenoceptor subtypes increases food intake in rats.

Previous studies have shown that the blockade of α1-adrenoceptors in the median raphe nucleus (MnR) of free-feeding animals increases food intake. Since there is evidence for the presence of α1A-, α1B- and α1D-adrenoceptors in the MnR of rats, this study investigated the involvement of MnR α1-adrenoceptor subtypes in the control of feeding behavior, looking for possible differences on the role of each α1-adrenoceptor in feeding. Male adult rats weighing 280-300 g with guide cannulae chronically implanted above the MnR were injected with antagonists of α1A- (RS100329, 0, 2, 4 or 20 nmol), α1B- (Rec 15/2615, 0, 2, 4 or 20 nmol) or α1D-adrenoceptor (BMY 7378, 0, 2, 4 or 20 nmol).