Maternal rumen and milk microbiota shape the establishment of early-life rumen microbiota in grazing yak calves.

Early-life gut microbial colonization and development exert a profound impact on the health and metabolism of the host throughout the life span. The transmission of microbes from the mother to the offspring affects the succession and establishment of the early-life rumen microbiome in newborns, but the contributions of different maternal sites to the rumen microbial establishment remain unclear. In the present study, samples from different dam sites (namely, oral, rumen fluid, milk, and teat skin) and rumen fluid of yak calves were collected at 6 time points between d 7 and 180 postpartum to determine the contributions of the different maternal sites to the establishment of the bacterial and archaeal communities in the rumen during early life. Our analysis demonstrated that the dam's microbial communities clustered according to the sites, and the calves' rumen microbiota resembled that of the dam consistently regardless of fluctuations at d 7 and 14. The dam's rumen microbiota was the major source of the calves' rumen bacteria (7.9%) and archaea (49.7%) compared with the other sites, whereas the potential sources of the calf rumen microbiota from other sites varied according to the age. The contribution of dam's rumen bacteria increased with age from 0.36% at d 7 to 14.8% at d 180, whereas the contribution of the milk microbiota showed the opposite trend, with its contribution reduced from 2.7% at d 7 to 0.2% at d 180. Maternal oral archaea were the main sources of the calves' rumen archaea at d 14 (50.4%), but maternal rumen archaea became the main source gradually and reached 66.2% at d 180. These findings demonstrated the potential microbial transfer from the dam to the offspring that could influence the rumen microbiota colonization and establishment in yak calves raised under grazing regimens, providing the basis for future microbiota manipulation strategies during their early life.

Remifentanil-sevoflurane interaction models of circulatory response to laryngoscopy and circulatory depression.

BACKGROUND: Sevoflurane and remifentanil are commonly combined to produce the hypnotic and analgesic effects required for clinical anaesthesia. Previous studies have characterized interactions between several i.v. drugs and inhalation agents. Aiming to extend this effort, we developed two new mathematical models to characterize the interactions manner and strength between sevoflurane and remifentanil. METHODS: Sixty-five adult Chinese patients undergoing elective operations received a target-controlled infusion of remifentanil (0-10 ng ml(-1)) and inhaled sevoflurane (0.3-3.4 vol.%) at various randomly selected target concentration pairs. After reaching pseudo-steady-state drug levels, the circulatory response to laryngoscopy and any circulatory depression (a side-effect) were observed for each pair of target concentrations. The pharmacodynamic interactions between sevoflurane and remifentanil were investigated by response surface methodology. NONMEM software was used to estimate the model parameters. RESULTS: The response surface models revealed significant synergy between sevoflurane and remifentanil. When the target remifentanil concentration was increased from 0 to 10 ng ml(-1), the C50, sevo decreased from 2.6 to 0.38 vol.% for the prevention of circulatory response to laryngoscopy and from 3.53 to 1.46 vol.% for the induction of circulatory depression. CONCLUSIONS: The new models can be used to characterize the interactions between these two drugs both qualitatively and quantitatively. Remifentanil significantly decreased the amount of sevoflurane required to eliminate patient response to clinical stimuli, thus reducing the likelihood of side-effects, specifically circulatory depression.