Population pharmacokinetics of tacrolimus and CYP3A5, MDR1 and IL-10 polymorphisms in adult liver transplant patients

BACKGROUND AND OBJECTIVE

Tacrolimus, an immunosuppressant widely used after liver transplantation, is characterized by a large inter-individual variability in its pharmacokinetics. The aim of this study was to perform population pharmacokinetic analysis of oral tacrolimus in liver transplant recipients and clarify the potential role of CYP3A5, MDR1 and IL-10 genetic polymorphisms in the variability of population pharmacokinetic parameters.

METHODS

Tacrolimus blood concentration data (n = 1106) were collected from 104 full liver transplant patients and were analysed using a non-linear mixed-effects modelling program (nonmem). The CYP3A5*3, MDR1 G2677T/A and C3435T genetic polymorphisms were determined using polymerase chain reaction (PCR)-restriction fragment length polymorphism analysis. The IL-10 G-1082A variant was studied by allele-specific PCR method.

RESULTS AND DISCUSSION

The liver function in patients as indicated by the total bilirubin level (TBIL) and different CYP3A5*3 genotypes in donors (CYPD) and recipients (CYPR) were observed to influence tacrolimus pharmacokinetic parameter of apparent clearance (Cl/F). The final regression model can be expressed as Cl/F = 15.9 - 1.88 TBIL + 7.65 CYPD + 7.00 CYPR. The relative standard errors (%RSE) of the parameter estimation were lower than 30% and the residual variability of tacrolimus trough blood concentration was 2.81 ng/mL. No significant effect of MDR1 and IL-10 polymorphisms was observed on population pharmacokinetic parameter of tacrolimus within 175 days after liver transplantation.

CONCLUSION

The TBIL in patients and CYP3A5*3 genetic polymorphism in both donors and recipients contribute to the inter-individual variability of oral tacrolimus apparent clearance in Chinese adult liver transplant patients.

Well water contaminated by acidic mine water from the Dabaoshan Mine, south China: chemistry and toxicity

An investigation into well water quality was carried out in a rural area subject to irrigation with acidic mine water from the Guangdong Dabaoshan Mine, southern China. The results of water pH measurements from 112 wells in two different seasons suggest that the well water has been contaminated to varying degrees in the investigated Shangba floodplain (approximately 11km south of the Guangdong Dabaoshan Mine). There is a trend that well water pH increased southwards, suggesting that the impacts of acidic irrigation water on groundwater decreased with increasing distance to the entry point of acidic irrigation water. Water quality monitoring results of the selected wells show that Cu and Cd in the water exceeded the limits set in the Chinese National Standards for Drinking Water (GB 5749-85) for the wells close to the irrigation water source. If the World Health Organization (WHO) standard was considered, Cd in some wells was almost 10 times as high as the WHO guideline value (0.003mg l(-1)). Water collected from the location closest to the acidic irrigation water source was acutely toxic to the test organism (Daphnia carinata) even after 51 time dilution. It is likely that the extremely high mortality rate of the local population reported for the study area is at least partly related to the high levels of heavy metals, particularly Cd in the drinking well water.

Small-for-size syndrome secondary to outflow block of the segments V and VIII anastomoses--successful treatment with trans-splenic artery embolization: a case report

Despite the rapid expansion of living donor liver transplantation (LDLT) in the adult population over the last few years, small-for-size syndrome (SFSS) has emerged as an important clinical problem. We have herein reported a patient who developed clinical evidence of prolonged cholestasis and intractable ascites after a small-for-size right lobe LDLT. The SFSS was attributed to outflow block of segments V and VIII anastomoses with severe portal overperfusion injury. It was successfully treated by reduction of portal pressure and blood flow after trans-splenic arterial ligation. We recommend that trans-splenic artery embolization, a technically simple procedure, be applied to treat portal overperfusion injury in SFSS.

Photochemical cross-linking for collagen-based scaffolds: a study on optical properties, mechanical properties, stability, and hematocompatibility

Collagen presents an attractive biomaterial for tissue engineering because of its excellent biocompatibility and negligible immunogenicity. However, some intrinsic features related to the mechanical stability and thrombogenicity limit its applications in orthopedic and vascular tissue engineering. Photochemical cross-linking is an emerging technique able to stabilize tissue grafts and improve the physicochemical properties of collagen-based structures. However, other important properties of collagen-based structures and the effect of processing parameters on these properties have not been explored. In this study, we aim to investigate the dose dependence of tensile and swelling properties on two parameters, namely, laser energy fluence and rose Bengal photosensitizer concentration. We also study the compression properties using cyclic compression test, long-term stability using subcutaneous implantation, and hematocompatibility using platelets adhesion test, of cross-linked collagen structures. Moreover, because limited optical penetration in turbid media is the major obstacle for light-based techniques, we also characterize the optical properties, which partially determine the effective optical penetration depth in collagen gel samples, during photochemical cross-linking. Laser energy fluence and rose Bengal concentration are important parameters affecting the cross-linking efficiency, which was characterized as the mechanical and the swelling properties, in a dose-dependent manner. Under the experimental conditions in this study, the peak fluence was 12.5 J/cm2 and the minimal rose Bengal concentration for effective cross-linking was >0.00008% (0.786 micromol). Photochemical cross-linking also enhanced the compression strength and long-term stability of collagen structures without compromising the tissue compatibility. Furthermore, photochemical cross-linking reduced platelet adhesion and abolished fibrin mesh formation, thereby improving the hematocompatibility of collagen structures. These results suggest the feasibility of using the photochemically cross-linked collagen structures for orthopedic and vascular tissue engineering. Finally, the effective optical penetration depth in collagen gel samples is wavelength and rose Bengal concentration dependent, and was approximately 12 mm at 514 nm at 0.001% (9.825 micromol), the rose Bengal concentration mostly used in this study.

Randomized trial of acupuncture versus sham control for prevention of myelosuppression in patients with gynecologic malignancies

19524

Background: CIM is a significant toxicity that is treated with cytokine growth factors, dose reductions and/or delays. Preliminary uncontrolled Chinese studies suggest that acupuncture lessens CIM. Methods: Patients (pts) with newly diagnosed or recurrent gyn cancers receiving chemotherapy were eligible. Trial design was a double blinded, randomized trial of active acupuncture or sham for 5 weeks (administered 3x per week). Primary endpoints were first nadir WBC and ANC levels at chemo cycle 2; other endpoints were recovering counts following the cycle 2 nadir, QOL, G-CSF levels, and feasibility. Results: >460 patients were screened. 21 pts were randomized to either active acupuncture (n=11) or sham control (n=10). Median age of the pts was 55 yrs (range: 28–81). 15 pts have completed the acupuncture treatment to provide the baseline and nadir WBC and ANC. Toxicities related to either sham or active acupuncture were minimal. The active pts group showed higher baseline WBC (median: 3,600 vs. 2,600, NS) and ANC (median: 2,269 vs. 1,922, NS) values. The nadir WBC was higher in the pts receiving acupuncture (median 3,600 vs. 2,300) but the difference was not statistically significant after adjusting for the baseline difference (p=0.16). Nadir ANC was higher among the pts receiving acupuncture (median: 2,424 vs. 1,274) but the difference was not statistically significant after adjusting for the baseline difference (p=0.1107). Recovering WBC in the pts receiving acupuncture was higher (median: 8,600 vs. 4,400) after adjusting for the baseline difference (p=0.045). The recovering ANC in the pts receiving acupuncture was higher (median: 6,530 vs. 4,038) but this difference was not statistically significant after adjusting for the baseline difference (p=0.0919). QOL and G-CSF data will be presented at ASCO. Conclusions: Although a larger randomized trial is necessary to determine the effects of acupuncture on CIM, there were consistent trends, and recovering WBC counts were significantly higher in patients receiving acupuncture. Formal evaluation of CAM is vital to confirm potentially clinically meaningful benefits.

No significant financial relationships to disclose.