Changes in various metabolic parameters in blood and milk during experimental Escherichia coli mastitis for primiparous Holstein dairy cows during early lactation

Background： The objective of this study was to characterize the changes in various metabolic parameters in blood and milk during IMI challenge with Escherichia coli （E. coh. for dairy cows during early lactation. Thirty, healthy primiparous Holstein cows were infused （h = 0） with -20-40 cfu of live E. coil into one front mammary quarter at -4-6 wk in lactation. Daily feed intake and milk yield were recorded. At -12, 0, 3, 6, 12, 18, 24, 36, 48, 60, 72, 96, 108, 120, 132, 144, 156, 168, 180 and 192 h relative to challenge rectal temperatures were recorded and quarter foremilk was collected for analysis of shedding of E. coil Composite milk samples were collected at -180, -132, -84, -36, -12, 12, 24, 36, 48, 60, 72, 84, 96, 132 and 180 h relative to challenge （h=0） and analyzed for lactate dehydrogenase （LDH）, somatic cell count, fat, protein, lactose, citrate, beta-hydroxybutyrate （BHBA）, free glucose （fglu）, and glucose-6-phosphate （G6P）. Blood was collected at -12, 0, 3, 6, 12, 18, 24, 36, 60, 72, 84, 132 and 180 h relative to challenge and analyzed for plasma non-esterified fatty acids （NEFA）, BHBA and glucose concentration. A generalized linear mixed model was used to determine the effect of IMI challenge on metabolic responses of cows during early lactation. Results： By 12 h, E. coli was recovered from challenged quarters and shedding continued through 72 h. Rectal temperature peaked by 12 h post-challenge and returned to pre-challenge values by 36 h post-IMI challenge. Daily feed intake and milk yield decreased （P 〈0.05） by 1 and 2 d, respectively, after mastitis challenge. Plasma BHBA decreased （12 h, P 〈0.05） from 0.96± 1.1 at 0 h to 0.57±0.64 mmol/L by ]8 h whereas concentration of plasma NEFA （78 h） and glucose （24 h） were significantly greater, 11 and 27%, respectively, after challenge. In milk fglu, lactose, citrate, fat and protein yield were lower whereas yield of BHBA and G6P were higher after challenge when compared to pre-challenge values. Conclusions： Changes in metabolites in blood and milk were most likely associated with drops in feed intake and milk yield. However, the early rise in plasma NEFA may also signify enhanced adipose tissue lipolysis. Lower concentrations of plasma BHBA may be attributed to an increase transfer into milk after IMI. Decreases in both milk lactose yield and % after challenge may be partly attributed to reduced conversion of fglu to lactose. Rises in G6P yield and concentration in milk after challenge （24 h） may signify increased conversion of fglu to G6P. Results identify changes in various metabolic parameters in blood and milk after IMI challenge with E. coli in dairy cows that may partly explain the partitioning of nutrients and changes in milk components after IMI for cows during early lactation.

Early lactate clearance as a reliable predictor of initial poor graft function after orthotopic liver transplantation

BACKGROUND:Initial poor graft function (IPGF) following orthotopic liver transplantation is a major determinant of postoperative survival and morbidity.Lactate clearance is a good marker of liver function.In this study,we investigated the clinical utility of early lactate clearance as an early and accurate predictor for IPGF following liver transplantation.METHODS:This was a prospective observational study of 222 patients referred to the surgical intensive care unit (SICU) after orthotopic liver transplantation.The IPGF group consisted of patients with alanine aminotransferase (ALT) and/or aspartate aminotransferase (AST) >1500 IU/L within 72 hours after orthotopic liver transplantation.Early lactate clearance was defined as lactate at SICU presentation (hour 0) minus lactate at hour 6,divided by lactate at SICU presentation.The model for end-stage liver disease (MELD) score,Child-Pugh score and laboratory data including AST,ALT,total bilirubin (TB) and prothrombin time (PT) were recorded at SICU presentation and compared between the non-IPGF and IPGF groups Receiver operating characteristic (ROC) curves were plotted to measure the performance of early lactate clearance,MELD score,Child-Pugh score,TB and PT.RESULTS:IPGF occurred in 45 of the 222 patients (20.3%).The early lactate clearance in the non-IPGF group was markedly higher than that in the IPGF group (43.2±13.8% vs 13.4±13.7% P<0.001).The optimum cut-off value for early lactate clearance predicting IPGF was 24.8% (sensitivity 95.5%,specificity 88.9%).The area under the curve of the ROC was 0.961,which was significantly superior to MELD score,Child-Pugh score TB and PT.Patients with early lactate clearance ≤24.8% had a higher IPGF rate (OR=169) and a higher risk of in-hospital mortality (OR=3.625).CONCLUSIONS:Early lactate clearance can serve as a prompt and accurate bedside predictor of IPGF.Patients with early lactate clearance less than 24.8% are associated with a higher incidence of IPGF.