Influence of enrichment and isolation media on the detection of Campylobacter spp. in naturally contaminated chicken samples.

Investigating Campylobacter epidemiology requires adequate technique and media to ensure optimal culturing and accurate detection and isolation of Campylobacter strains. In the present study, we investigated the performances of three enrichment durations in Bolton broth (0, 24 and 48h) and compared four isolation media (mCCDA, Karmali, Butzler no. 2 and CampyFood agar (CFA)) for the detection of Campylobacter positive samples and the identification of Campylobacter species, from naturally contaminated broiler chicken samples (caeca, neck skin from carcasses, and skin from thighs). We compared our local results to those we obtained with samples from a European survey (caeca and neck skin) and a national survey (neck skin, thigh skin, and breast). Direct plating favored the detection of positive samples highly contaminated by Campylobacter (caeca and neck skin from carcasses) whatever the media. A longer enrichment reduced the rates of Campylobacter recovery except when using Butzler no. 2, more particularly for neck skin which background microflora was less important than in caeca. As a matter of fact, enrichment allowed a higher detection rate of positive samples with low Campylobacter contamination levels (breast, thigh skin), this detection being enhanced when using Butzler no. 2. When comparing the 3 other selective media, CFA was the 2nd most efficient media prior to mCCDA and Karmali. Interestingly, enrichment promoted the growth of Campylobacter coli but this promotion was least with Butzler no. 2 agar. Our study has confirmed the need to adapt the method to the types of samples for improving the detection of Campylobacter and that the method may affect the prevalence of the species.

The development of the ovine fetal adrenal gland and its regulation.

In mammalian species, the fetal adrenal gland plays a key role during late gestation since fetal glucocorticoids are involved in the maturation of the fetus and in the adaptation of the neonate to extra-uterine life. Moreover, in domestic ruminants as well as in the pig, the onset of parturition is triggered by an increased level of fetal plasma glucocorticoids. This prepartum rise of fetal glucocorticoids, which conveys growth and differentiation of adrenocortical cells, is not only under pituitary control but also involves local regulations. We review the actual knowledge of the modalities of fetal adrenal development in the sheep and its regulation by the adrenocorticotropic hormone (ACTH) and other factors.

Effect of transforming growth factor beta-1 on the cholesterol side-chain cleavage system in the adrenal gland of sheep fetuses and newborns.

The present work examined the effect of transforming growth factor-beta1 (TGFbeta1) on the cholesterol side-chain cleavage system of sheep fetal and neonatal adrenal glands. Freshly isolated fetal adrenal cells produced 3-fold less pregnenolone from 22R- hydroxycholesterol than neonatal cells. Also, the relative amounts of immunoreactive cytochrome P450 side-chain cleavage (P450scc), adrenodoxin, and adrenodoxin reductase were 1.5- to 2-fold lower in mitochondria from fetal than neonatal cells. However, during culture under control conditions, the cholesterol side-chain cleavage activity and the amounts of P450scc, adrenodoxin, and adrenodoxin reductase of fetal cells increased after 48 h to reach neonatal values. A 5-day treatment with TGFbeta1 (1ng/ml) decreased significantly both the cholesterol side-chain cleavage activity and the amounts of immunoreactive P450scc, adrenodoxin, and adrenodoxin reductase in sheep fetal and neonatal adrenal cells in culture. Immunoreactive TGFbeta1- like material was present in freshly isolated adrenal cells from both fetuses and newborn lambs. After 2 days of culture, the amount of TGFbeta1-like protein was 2-fold lower than in freshly isolated fetal cells. No change was observed for neonatal cells. Finally, TGFbeta1 encoding messenger RNAs and TGFbeta-like immunoreactive protein were much higher in adrenal cortices from fetuses than from neonates. Taken together, these results have made TGFbeta1 a potentially attractive candidate for being an auto/paracrine negative regulator of the cholesterol side-chain cleavage system in the sheep fetal adrenal gland.

Ontogenesis of cholesterol side-chain cleavage activity in the ovine adrenal during late gestation.

The present study examined the activity of the cholesterol side-chain cleavage system, and the amount of cytochrome P450scc in adrenal glands of sheep fetuses and newborn lambs as well as the in vitro regulation of these parameters. Freshly isolated fetal adrenal cells incubated in the presence of 1 mM 8Br-cAMP or 25 microM 22R-OH cholesterol, produced 4- to 5-fold less pregnenolone than neonatal cells under similar conditions. Likewise, pregnenolone production by isolated fetal adrenal mitochondria was lower than that of neonatal mitochondria when endogenous cholesterol was used as a substrate or when 22R-OH cholesterol was added to the incubation medium. Also, the amount of P450scc, determined by immunoblot, was lower in fetal mitochondria than in neonatal mitochondria. In culture, ACTH, despite enhancing both the production of pregnenolone and the incorporation of [14C]acetate in cholesterol and its end-products by fetal adrenal cells, neither increased the amount of pregnenolone formed from 22R-OH cholesterol nor the amount of immunoreactive P450scc. By contrast, during the first 48 h of culture under standard conditions, there was a "spontaneous" increase in the activity of P450scc which reached values observed in neonatal adrenal cells. Such a development was inhibited when 5% ovine fetal serum was added to the culture medium. These results reinforce the view that in the ovine fetal adrenal gland, the development of P450scc is not ACTH-dependent but involves most probably a decrease in inhibitory factors present in fetal blood.