Profile of Gut Microbiota Associated With the Presence of Hepatocellular Cancer in Patients With Liver Cirrhosis.

BACKGROUND: Changes within the gut microbiota contribute to the progression of chronic liver diseases. According to the results of several studies performed in animal models, gut dysbiosis plays an important role in hepatocarcinogenesis. The aim of this study was to explore the characteristics of gut microbiota associated with the presence of hepatocellular cancer (HCC) in patients with cirrhosis of the liver undergoing liver transplantation. METHODS: A total of 15 patients with HCC and 15 non-HCC patients matched according to etiology of cirrhosis and Model for End-Stage Liver Disease (MELD) scores who underwent liver transplantations between 2012 and 2014 were included. Analysis of their gut microbial profile was based on prospectively collected stool samples from the pretransplant period. RESULTS: Patients with and without HCC were similar with respect to age (P = .506), sex (P = .700), hepatitis C virus (P > .999) and hepatitis B virus (P = .715) infection status, alcoholic liver disease (P > .999), and MELD score (P = .337). Notably, the presence of HCC was associated with significantly increased fecal counts of Escherichia coli (P = .025). Prediction of HCC presence based on E coli counts was associated with the area under the receiver-operating curve of 0.742 (95% confidence interval, 0.564-0.920), with the optimal cutoff on the level of 17.728 (natural logarithm of colony-forming units per 1 g of feces). Sensitivity and specificity rates for the established cutoff were 66.7% and 73.3%, respectively. CONCLUSIONS: The profile of gut microbiota associated with the presence of HCC in cirrhotic patients is characterized by increased fecal counts of E coli. Therefore, intestinal overgrowth of E coli may contribute to the process of hepatocarcinogenesis.

The relevance of intestinal dysbiosis in liver transplant candidates.

BACKGROUND: The gut microbial ecosystem plays an important role in the pathogenesis of liver diseases. However, the association of microbial community structure with the severity of liver dysfunction is not completely understood. METHODS: Fecal microflora was assessed in 40 patients with liver cirrhosis listed for primary liver transplantation (LT). Independent associations between fecal microbial counts and serum bilirubin, serum creatinine, international normalized ratio (INR), and the Model for End-stage Liver Disease (MELD) score were established in multiple linear regression models. RESULTS: Bifidobacterium (standardized regression coefficient [sß] = -0.549; P < 0.001), Enterococcus (sß = 0.369; P = 0.004), and yeast (sß = 0.315; P = 0.018) numbers were independently associated with serum bilirubin, while Escherichia coli counts (sß = 0.318; P = 0.046) correlated with INR, and Bifidobacterium counts (sß = 0.410; P = 0.009) with serum creatinine. Only Bifidobacterium (sß = -0.468; P = 0.003) and Enterococcus (sß = 0.331; P = 0.029) counts were independent predictors of the MELD score. Bifidobacterium/Enterococcus ratio, proposed as a measure of pre-LT gut dysbiosis, was significantly related to the MELD score following the adjustment for the absolute Bifidobacterium (sß = -0.333; P = 0.029) and Enterococcus (sß = -0.966; P = 0.003) numbers. This pre-transplant dysbiosis ratio (PTDR) was significantly correlated with Enterococcus (R = -0.897; P < 0.001) but not with Bifidobacterium (R = 0.098; P = 0.546) counts. Among the other components of gut microflora, only hydrogen peroxide (H2 O2 )-producing Lactobacillus strains significantly influenced Enterococcus counts (sß = 0.349; P = 0.028) and PTDR (sß = -0.318; P = 0.046). CONCLUSION: While the abundance of both Bifidobacterium and Enterococcus is related to liver dysfunction, the size of the Enterococcus population seems to be the most important determinant of pre-LT gut dysbiosis in cirrhotic patients. The H2 O2 -producing Lactobacillus strains potentially ameliorate this dysbiotic state.

Rectification in synthetic conical nanopores: a one-dimensional Poisson-Nernst-Planck model.

Ion transport in biological and synthetic nanochannels is characterized by phenomena such as ion current fluctuations and rectification. Recently, it has been demonstrated that nanofabricated synthetic pores can mimic transport properties of biological ion channels [P. Yu. Apel, Nucl. Instrum Methods Phys. Res. B 184, 337 (2001); Z. Siwy, Europhys. Lett. 60, 349 (2002)]. Here, the ion current rectification is studied within a reduced one-dimensional (1D) Poisson-Nernst-Planck (PNP) model of synthetic nanopores. A conical channel of a few nm to a few hundred nm in diameter, and of a few mum long is considered in the limit where the channel length considerably exceeds the Debye screening length. The rigid channel wall is assumed to be weakly charged. A one-dimensional reduction of the three-dimensional problem in terms of corresponding entropic effects is put forward. The ion transport is described by the nonequilibrium steady-state solution of the 1D Poisson-Nernst-Planck system within a singular perturbation treatment. An analytic formula for the approximate rectification current in the lowest order perturbation theory is derived. A detailed comparison between numerical results and the singular perturbation theory is presented. The crucial importance of the asymmetry in the potential jumps at the pore ends on the rectification effect is demonstrated. This so constructed 1D theory is shown to describe well the experimental data in the regime of small-to-moderate electric currents.

How the asymmetry of internal potential influences the shape of I-V characteristic of nanochannels.

Ion transport in biological and synthetic nanochannels is characterized by such phenomena as ion current fluctuations, rectification, and pumping. Recently, it has been shown that the nanofabricated synthetic pores could be considered as analogous to biological channels with respect to their transport characteristics [P. Yu. Apel et al., Nucl. Instrum. Methods Phys. Res. B 184, 337 (2001); Z. Siwy et al., Europhys. Lett. 60, 349 (2002)]. The ion current rectification is analyzed. Ion transport through cylindrical nanopores is described by the Smoluchowski equation. The model is considering the symmetric nanopore with asymmetric charge distribution. In this model, the current rectification in asymmetrically charged nanochannels shows a diodelike shape of I-V characteristic. It is shown that this feature may be induced by the coupling between the degree of asymmetry and the depth of internal electric potential well. The role of concentration gradient is discussed.

Asymmetric nanodiffusion.

The asymmetric diffusion through conical nanopores is described by the diffusional model. Diffusion is several times faster; when the concentration gradient points from the wide towards the narrow opening of the cone than in the opposite direction. The asymmetric diffusion appears either when the diffusion coefficient depends on the concentration or when the diffusing substances interact with the channel (i.e., ions moving through channels with charged walls). These results suggest that asymmetric nanopores can act as molecular (ionic) filters which could be used for retrieving the molecules of a given component from solutions in which its concentration fluctuates strongly, and only occasionally attains high values.

Asymmetric diffusion through synthetic nanopores.

We show that diffusion currents for a membrane containing a single conical nanopore with a fixed surface charge and small enough opening diameter depend on the concentration gradient direction. We interpret the results based on the effect of salt concentration on the thickness of the electrical double layer within the nanopore associated with the nanopore's surface charge and the distribution of electric fields inside the pore. The experimental observations are described by a diffusional model based on the Smoluchowski-Nernst-Planck equation.

Effects of caffeine on NMDA-evoked 45Ca2+ release in the rate dentate gyrus in vivo.

Caffeine in 10(-2) M concentration per se activates ryanodine receptors (RyR) in vitro, thereby increasing the intracellular concentration of Ca2+ ([Ca2+]i). In general opinion, caffeine applied in vivo in much lower doses does not affect [Ca2+]i in neurones. However, it was recently demonstrated that caffeine in low concentrations in vitro potentiates evoked Ca2+ release in neurones via RyR. Microdialysis of the rat dentate gyrus (DG), combined with measurement of 45Ca2+ efflux, has been used in our laboratory to study in vivo NMDA-evoked calcium induced calcium release (CICR) via RyR. The aim of the present microdialysis study was to investigate in vivo effects of caffeine, applied systemically in a pharmacologically-relevant dose, and locally in the dialysis medium in very high concentration, on the NMDA-evoked CICR in DG neurones. To ensure steady brain concentration of caffeine, its systemic (i.p.) administration in a dose of 40 mg/kg was followed by a continuous i.p. infusion of 80 micrograms/kg/min and application of 0.4 mM caffeine in the dialysis medium. The results demonstrated that in the rat DG, local administration of 50 mM caffeine significantly stimulates a spontaneous 45Ca2+ efflux and its release induced by 5 mM NMDA. However, systemic administration of caffeine had no effect on spontaneous and NMDA-induced 45Ca2+ release in the rat DG, which supports the view that caffeine, applied in vivo, even in high doses, does not influence CICR in brain neurones.

Insulin impairs the anticonvulsive activity of carbamazepine against maximal electroshock-induced seizures in mice.

In view of the data indicating that insulin can modify penetration of some drugs across cell membranes and tissue barriers, particularly the blood-brain barrier, the aim of the present study was to evaluate the effect of insulin on both the anticonvulsant activity and the brain concentration of carbamazepine in mice suffering from seizures induced by maximal electroshock. The antiepileptic drug was administered per os in single doses either alone or in combination with insulin given as single intraperitoneal injections. To assess the anticonvulsant activity of carbamazepine the ED50 values were calculated. The results indicate that insulin given in doses up to 2 units/kg did not affect the convulsive threshold, whereas insulin applied at 2 units/kg led to a significant reduction in the anticonvulsant activity of carbamazepine, as judged by an increase in the ED50 value from 16.2 to 41.3 mg/kg. This effect was accompanied by the marked reduction in both the brain and blood concentrations of the drug. It is likely, therefore, that the inhibitory activity of insulin on the anticonvulsive function of carbamazepine is related not only to the effect of the former on the blood-brain transport of the latter, but also to insulin-induced modulation of the serum concentration of the drug.