Liver transplantation and bile analysis: a parallel evolution

Serum bile acid levels assist the prediction of biliary stricture and survival after liver transplantation in children

Biliary stricture is an important biliary complication after liver transplant in children. We aimed to investigate the utility of serum bile acid levels for prediction of biliary stricture in children after liver transplant. This study enrolled 60 children who underwent liver transplantation at a mean age of 2.04±0.30 years; serum bile acid levels were surveyed in a cross-sectional design. These patients were followed regularly at our institute, and the clinical data were collected prospectively. The major indication of liver transplant in this pediatric cohort was biliary atresia (78.33%). During the follow-up period (3.08±0.30 years), nine patients (15%) developed biliary stricture after the check of serum bile acid. A receiver operating characteristic curve analysis yielded a serum bile acid cutoff of >40 μM for the prediction of biliary stricture (P = 0.002). A serum bile acid level >40 is the most important predictor of a biliary stricture after liver transplant (odds ratio=65.65, P = 0.003) after adjusting for gender and GGT levels. The phenomenon remained on Cox's proportional hazard survival analysis (hazard ratio =15.42, P = 0.001). The mortality risk after liver transplant was significantly higher in subjects with serum bile acid levels >40 μM than in those with levels ≤40 μM (log-rank test, P = 0.004).Conclusion: Serum bile acid levels can be used for non-invasive screening and prediction of biliary stricture and mortality in children after liver transplantation. What is Known: • Biliary stricture is a major biliary complication after pediatric liver transplantation, and we showed the serum bile acid level significantly associates with biliary stricture. What is New: • In this study, we demonstrated the serum bile acid level may assist in the early detection of biliary stricture and mortality non-invasively.

Bile UPLC-MS fingerprinting and bile acid fluxes during human liver transplantation

Bile flow restoration is a crucial step in the recovery process post transplantation of the liver. Here, metabolic trajectories based on changes in bile secretion - a known marker of functionality - have been utilised as an approach for discovering bile fluxes during transplantation. A total of ten liver transplants were monitored and from these 68 bile samples from both donors and recipients were collected and analysed using ultra-performance LC-MS in combination with multivariate statistical analysis. Based on the principal component scores constructed from the total bile fingerprint, differentiation of the bile acid concentrations before and after transplantation was detected. A trend was also observed, by constructing metabolic trajectories, whereby the post-transplant profiles approached the position of pre-transplant profiles within 30-60 min of the restoration of bile secretion function. The ten major conjugated bile acid salts were measured and a significant increase in concentrations of taurocholic acid and taurochenodeoxycholic acid were seen after transplantation. In addition, the ratios of secondary bile acids detected in gall bladder and hepatic bile were measured before and after transplantation. This study suggests that bile acid ratios in the donor liver at the pre-transplant and post-transplant stage may be important and that profiling of secreted bile after transplantation may aid clinical assessment and progress post-transplantation.

Cyclosporine A versus tacrolimus monotherapy. Comparison on bile lipids in the first 3 months after liver transplant in humans

Biliary lipids output is reduced after liver transplantation and tends to normalize thereafter. Cyclosporine A (CyA) is reported to interfere with the normal bile-restoring process after liver grafting, but data are inconclusive, in particular regarding the comparison with the other widely used calcineurin inhibitor tacrolimus (TCR). Furthermore, previous researches were conducted in patients taking multiple immunosuppressive therapies and with a short follow up. In this study we readdressed this issue by comparing biliary lipids in the first 3 months after liver transplant, in 20 patients randomized to receive immunosuppression with CyA or TCR monotherapy. Bile samples, harvested through a T-tube at days 1, 3, 7, 15, 30, 60 and 90 were assessed for cholesterol, phospholipids, and total and individual concentrations of bile acids (BA). Liver and kidney function tests were evaluated as well. We found no differences between CyA and TCR in biochemical findings or in total biliary BAs, cholesterol, and phospholipids. However, CyA-treated patients showed lower levels of glycochenodeoxycholic acid at day 15, compared to those treated with TCR (P < 0.04). This difference normalized thereafter, without any biochemical or clinical effect at 3-month follow up.

Explaining phenotypic selection on plant attractive characters: male function, gender balance or ecological context?

It is widely agreed that the flowers of hermaphrodite plants evolve in response to selection acting simultaneously through male and female sexual functions, but we know very little about the pattern of gender-specific selection. We review three current hypotheses for gender-specific selection by viewing them within a single phenotypic selection framework. We compile data from phenotypic selection and manipulative studies and evaluate the fit between empirical data and the hypotheses. In this preliminary analysis, we find that neither the male-function hypothesis nor the gender-balance hypothesis is well supported. However, the context-dependence hypothesis is supported by the documented diversity of gender-specific selection and by evidence that selection through female fertility is significantly correlated with pollen limitation of seed production. Future studies contributing to our understanding of selection through male and female function in plants need to quantify and manipulate the ecological context for reproduction, as well as describe male and female fitness responses to fine-scale trait manipulation.

Bile acids analysis: a tool to assess graft function in human liver transplantation

The expanding use of "sub-optimal" grafts due to donor organ shortage increases the importance of accurate graft assessment before liver transplantation. Bile secretion is an early sign of recovering hepatic function post-transplant. The role of bile acid analysis in assessing graft function before and immediately after liver transplantation has been investigated. Two hundred and sixteen samples of hepatic bile were collected from 35 donors and 13 recipients. Clinical data, bile flow, total bile acid concentration, apparent choleretic activity and bile acid composition were assessed. Sub-optimal donor livers showed a low apparent choleretic activity and a different bile acid composition when compared to normal grafts. In recipients, the pattern of recovery of bile secretion immediately after reperfusion was a useful predictor of graft function. This study characterises bile acid secretion of liver grafts and remarks the potential value of bile acid analysis to assess donor liver quality and early post-transplant graft function.

Survival of rats undergoing continuous bile drainage depends on maintenance of circadian rhythm of bile secretion

It is very difficult to collect bile secretions from animals for extended periods of time. We compared the use of saline or water as drinking fluids to sustain the animals, which were being continuously drained of bile. Complete bile drainage was performed in 16 male Wistar rats by surgical intervention. After surgery, 8 rats were given tap water, and the other 8 were given normal saline for water. The rats that received water rapidly lost weight after bile drainage, and all died within 8 days after the operation. In contrast, all rats that drank saline maintained their body weight and survived 14 days or longer after surgery. Serum biochemistry of the rats with water intake on the third day after bile drainage revealed hyponatremia, hypochloremia, and acute renal failure resulting in hyperkalemia. In contrast, electrolyte balance and renal function were normal in the rats with saline intake, and bile was secreted continuously with a circadian rhythm. These results clearly demonstrate that saline as drinking water is essential to the replacement of lost fluids and loss of electrolytes due to bile drainage. Further, saline proved efficacious for sustaining experimental animals undergoing continuous bile collection.