Pharmacokinetics of once daily prolonged-release formulation of tacrolimus in children with primary nephrotic syndrome

OBJECTIVE

Tacrolimus prolonged-release(PR) formulation is a new once-daily formulation of the calcineurin inhibitor tacrolimus, which is currently used in adult liver or kidney transplant patients,and is also gradually widely used in children with nephrotic syndrome.The present study was undertaken to preliminarily investigate the pharmacokinetic characteristics of tacrolimus PR in pediatric nephrotic syndrome recipients.

METHODS

This single-center open-label prospective study was performed in pediatric nephrotic syndrome recipients. Pharmacokinetic samples were collected from eight pediatric subjects with nephrotic syndrome from Department of Pediatric Nephrology in Peking University First Hospital between June and August 2011. They followed administration of single oral doses of tacrolimus PR formulation at 0.02 mg/kg (n=2), 0.05 mg/kg (n=2) and 0.10 mg/kg (n=4). Blood samples were taken before the dose and 1, 2, 4, 6, 8, 10, 12 and 24 h after drug intake. No other medicines or interacting food or drinks were taken during the study period. Blood concentrations were measured using an enzyme multiplied immunoassay technique. Pharmacokinetic analysis was performed using WinNolin Phoenix software Version 6.0(Pharsight, Cary, NC,USA).

RESULTS

The pharmacokinetic data were best described by a non-compartment model. Pharmacokinetic parameters of tacrolimus PR formulation in the 3 ascending doses groups (0.02 mg/kg,0.05 mg/kg and 0.10 mg/kg) were as follows: the maximum drug concentrations (C_max/D) were (1.7±1.0) μg/L, (3.1±1.9) μg/L, (8.0±3.5) μg/L, respectively; Areas under the drug concentration-time curve(AUC_0-∞/D) were (47.2±47.1) h×μg/L, (84.0±13.1) h×μg/L, (175.6±107.1) h×μg/L, respectively; Oral clearance rates were (0.8±0.9) L/(h×kg), (0.4±0.1) L/(h×kg), (1.9±1.3) L/(h×kg), respectively; Body weight normalized distribution volumes were (7.0±3.4) L/kg, (12.4±8.4) L/kg and (73.6±68.6) L/kg, respectively. Both mean C_max normalized level for the administered dose(C_max/D) and mean AUC_0-∞ normalized level for the administered dose (AUC_0-∞/D) were higher in the 0.05 mg/kg dosage group than in the 0.02 and 0.10 mg/kg dosage group. There were two peaks in the drug concentrations in every dose group;a primary peak appeared at the end of about 2 h followed by a small secondary peak at h 12, which was more noticeable in the 0.10 mg/kg dose group than in the two lower dosages.

CONCLUSION

The pharmacokinetic characteristics of tacrolimus PR formulation were initially explored in pediatric patients with nephritic syndrome. The data presented form a basis for subsequent larger scale studies on pharmacokinetics of tacrolimus PR formulation in nephritic syndrome children.

TNF-α was involved in calcium hydroxide-promoted osteogenic differentiation of human DPSCs through NF-κB/p38MAPK/Wnt pathway

It has been reported that calcium hydroxide can induce proliferation, migration, and mineralization in dental pulp stem cells (DPSCs), but the underlying molecular mechanisms are still unclear. In this study, we sought to explore the role of calcium hydroxide in the cell proliferation and directional differentiation of DPSCs and to study the regulatory effect of NF-κB, p38MAPK, and Wnt signaling on differentiation of DPSCs. CCK8 cell assay, Wound Healing Assay, and Alkaline Phosphatase Staining Assay were respectively used to determine the proliferation rate, migration and ALP expression of DPSCs. Alizarin Red Staining Assay was used to observe the mineralization of DPSCs. RT-PCR analysis and Western Blot Analysis displayed the expression of related fators at mRNA and protein level, respectively. In the present study, we found that NF-κB, p38MAPK, and Wnt signaling could abolish calcium hydroxide-induced proliferation of DPSCs. The inhibition of NF-κB, p38MAPK, and Wnt signaling suppressed the migration, ALP expression, and mineralization of DPSCs. NF-κB, p38MAPK, and Wnt signaling involved in directional differentiation of DPSCs. Moverover, calcium hydroxide could activate NF-κB, p38MAPK, and Wnt pathway by regulating TNF-α. Our study showed that NF-κB, p38MAPK, and Wnt signaling pathway were involved in calcium hydroxide-induced proliferation, migration, mineralization, and osteogenic differentiation in DPSCs. Calcium hydroxide affected NF-κB, p38MAPK, and Wnt pathway by regulating TNF-α.

Hsp90 modulates the stability of MLKL and is required for TNF-induced necroptosis

The pseudokinase mixed lineage kinase domain-like protein (MLKL) is a key component of tumor necrosis factor (TNF)-induced necroptosis and plays a crucial role in necroptosis execution. However, the mechanisms that control MLKL activity are not completely understood. Here, we identify the molecular chaperone Hsp90 as a novel MLKL-interacting protein. We show that Hsp90 associates with MLKL and is required for MLKL stability. Moreover, we find that Hsp90 also regulates the stability of the upstream RIP3 kinase. Interference with Hsp90 function with the 17AAG inhibitor destabilizes MLKL and RIP3, resulting in their degradation by the proteasome pathway. Furthermore, we find that Hsp90 is required for TNF-stimulated necrosome assembly. Disruption of Hsp90 function prevents necrosome formation and strongly reduces MLKL phosphorylation and inhibits TNF-induced necroptosis. Consistent with a positive role of Hsp90 in necroptosis, coexpression of Hsp90 increases MLKL oligomerization and plasma membrane translocation and enhances MLKL-mediated necroptosis. Our findings demonstrate that an efficient necrotic response requires a functional Hsp90.

Protective effect of ginsenoside against acute renal failure via reduction of renal oxidative stress and enhanced expression of ChAT in the proximal convoluted tubule and ERK1/2 in the paraventricular nuclei

Generation of reactive oxygen species significantly contributes to the pathogenesis of acute renal failure (ARF) induced by myoglobin release. Ginsenosides (GS), the principal active ingredients of ginseng, is considered as an extremely good antioxidative composition of Chinese traditional and herbal drugs. The purpose of the present study was to investigate the protective effect of ginsenoside in rats with ARF on the changes of cholinergic nervous system in the kidney as well as on the involvement of mitogen-activated protein kinases (MAPK) in the hypothalamic paraventricular nuclei (PVN). In our assay, glycerol-induced acute renal failure in rats was employed to study the protective effects of ginsenoside. Our results indicated that the treatment of ARF rats with ginsenosides for 48 h significantly reduced lipid peroxidation, restored the superoxide dismutase (SOD) level. Meanwhile, the obvious increase of choline acetyltransferase-immunoreactivity (ChAT-IR) in the proximal convoluted tubular cells (PCT) was observed by immunohistochemistry in ARF+GS group. The same effect was also observed in the changes of p-ERK1/2-IR in the hypothalamic paraventricular nuclei. Our results suggest that ginsenoside administered orally may have a strong renal protective effect against glycerol-induced ARF, reduce the renal oxidative stress, and ginsenoside can also activate the cholinergic system in PCT, simultaneously MAPK signal pathway in the PVN was also activated.

Changes in and shortcomings of drug stockpiling, vaccine development and related policies during outbreaks of avian influenza A H5N1, H1N1, and H7N9 among humans

The purpose of this paper is to provide a reference for the future stockpiling of drugs and developing vaccines for treatment of emerging infectious diseases by summarizing the status of drug stockpiling, vaccine development, and related policies during three major outbreaks of avian influenza among humans (H5N1 in 2003, H1N1 in 2009, and H7N9 in 2013). Documents regarding drug stockpiling and vaccine development during three influenza outbreaks have been reviewed. Results indicated that the response to pandemic influenza outbreaks has improved markedly in terms of stockpiles of antivirals and vaccine development. These improvements also suggest advances in related policy planning. These trends also foreshadow better prospects for prevention and control of emerging infectious diseases. However, the rationality of drug stockpiling and international cooperation still needs to be enhanced.

Identification of cellular proteins interacting with influenza A virus PB1-F2 protein

The influenza A virus (IAV) protein PB1-F2, which is encoded by an alternative ORF of the PB1 polymerase gene, has been implicated as an important virulence factor and apoptosis inducer. However, the molecular mechanism of PB1-F2 function remains elusive. In this study, eight cellular proteins were identified as potential PB1-F2 interacting partners using the yeast two-hybrid system. Two positive candidate proteins, guanine nucleotide binding protein (G protein) beta polypeptide 2 (Gβ2) and macrophage migration inhibitory factor (MIF), were selected to be further characterized. The interaction of MIF and Gβ2 with PB1-F2 was confirmed by both GST pull-down and co-immunoprecipitation assays. Confocal laser microscopy showed that the interaction between PB1-F2 and the two cellular proteins occurred in the cytoplasm. The novel interactions between PB1-F2 and host proteins provide further pieces of evidence in the investigation of the pathogenic mechanism of IAV.

KEYWORDS

influenza A virus; PB1-F2; yeast two-hybrid; protein-protein interaction.