Yuichi Nakazawa

Clinicopathological analysis of liver allograft biopsies with late centrilobular necrosis: a comparative study in 54 patients

BACKGROUNDnCentrilobular necrosis (CLN) in liver allografts can be a difficult lesion to interpret histologically. Although long recognized in association with developing chronic rejection, recent studies have described the lesion in association with a number of other disease processes. To clarify the histologic features that could allow a specific diagnosis to be made and to determine the outcome in different diagnostic groups, we assessed biopsies from 54 patients with CLN.nnnMETHODSnBiopsies were classified as CLN with acute cellular rejection (ACR), CLN with hepatitis, CLN with developing chronic rejection (CR), and CLN of other etiology. Histologic features were assessed and then compared between groups, and clinical outcomes were noted.nnnRESULTSnDiscriminating features for the different groups were as follows: CLN and ACR showed bile duct injury, endothelialitis, and acinar congestion. CLN and CR showed severe bile duct injury, bile duct loss, or centrilobular swelling. CLN and hepatitis was often a diagnosis of exclusion, although interface hepatitis was more common in this group. Cases of autoimmune hepatitis usually demonstrated plasma cell predominance in the portal and acinar inflammatory infiltrate. Significantly, there was considerable overlap in the histologic features between the groups, accounting for the diagnostic difficulty. Patients in whom the CLN was associated with CR or vascular complications generally required retransplantation or died, but in the groups with ACR and hepatitis, the outcome was more favorable.nnnCONCLUSIONSnWith regard to most liver allograft biopsies showing late CLN, it is possible to make a specific diagnosis despite overlapping histologic features; this allows specific therapy to be instituted. Ultimately this is likely to contribute to improved graft survival.

RELATIONSHIP BETWEEN IN VIVO FK506 CLEARANCE AND IN VITRO 13-DEMETHYLATION ACTIVITY IN LIVING-RELATED LIVER TRANSPLANTATION

BACKGROUNDnAlthough it is important to maintain an appropriate blood concentration of FK506 after liver transplantation, significant interindividual variability in the actual FK506 dosage has been observed, presumably due to the wide variability of cytochrome P450 3A4 activity in liver microsomes.nnnMETHODSnA study was conducted in patients undergoing living-related liver transplantation and their donors to investigate the relationship between the in vitro FK506 demethylation activity in graft liver microsomes and the in vivo blood clearance of FK506. Liver biopsy tissue was obtained from 17 living donors to measure the in vitro formation rate of 13-demethyl derivative (M-I: the major metabolite of FK506). Erythromycin N-demethylation activity in vitro was also assessed in 11 cases. The FK506 blood clearance (CLss) was calculated from its constant infusion rate and steady-state blood concentration on day 4 after transplantation in 17 recipients.nnnRESULTSnThe FK506 infusion rate varied 4.6-fold from 8.3 to 38.4 ng/min/kg. The mean CLss of FK506 was 22.1+/-10.8 ml/min (10.1-45.2 ml/min). The M-I formation rate showed a wide variability, ranging from 0.098 to 0.571 nmol/min/mg protein. A significant correlation was observed between the in vitro estimated total metabolic ability of the graft for FK506 (M-I formation rate x graft weight) and the in vivo CLss of FK506 (r=0.770, P<0.001). Erythromycin N-demethylation (0.066-0.443 nmol/min/mg protein) showed a strong correlation with the M-I formation rate (r=0.891, P<0.01).nnnCONCLUSIONSnThe in vivo FK506 clearance can mainly reflect in vitro FK506 demethylation activity.

Optimal Initial Dose of Orally Administered Once-daily Extended-release Tacrolimus Following Intravenous Tacrolimus Therapy After Liver Transplantation

INTRODUCTIONnOnce-daily extended-release tacrolimus (Tac-OD) is expected to reduce non-adherence in recipients after liver transplantation (LT). The aim of this study was to determine the optimal initial dose of orally administered Tac-OD after intravenous tacrolimus (Tac-IV) therapy after LT.nnnPATIENTS AND METHODSnThis prospective study included 10 adult recipients who had undergone LT at our institute. The recipients were prescribed tacrolimus by continuous intravenous administration with a steroid as initial immunosuppression therapy. Tacrolimus was converted from intravenous administration to once-daily oral intake when gastrointestinal function returned. We evaluated tacrolimus concentrations in blood 9 times a day and area under the blood concentration-time curve (AUC) during conversion. The optimal initial dose of Tac-OD was determined based on simple regression analysis between the oral dose of Tac-OD and the total dose of Tac-IV during a 24-hour period.nnnRESULTSnThe AUC before and after conversion showed no differences. We found that the optimal initial dose of Tac-OD was 8 times the dose of Tac-IV. There was a relationship between the AUC and the trough level. No recipients experienced acute rejection or adverse effects such as renal failure, neurotoxicity, or cardiac failure during conversion.nnnCONCLUSIONSnWe successfully converted continuous Tac-IV to oral intake of Tac-OD by adjusting the dose using trough levels without acute rejection or adverse effects. The AUC of Tac-OD correlated with the trough level. The optimal initial dose ratio of Tac-OD after Tac-IV was 8:1.