Auditory cortical plasticity induced by intracortical microstimulation under pharmacological blockage of inhibitory synapses

Electrical stimulation that can reorganize our neural system has a potential for promising neurorehabilitation. We previously demonstrated that temporally controlled intracortical microstimulation (ICMS) could induce the spike time-dependant plasticity and modify tuning properties of cortical neurons as desired. A 'pairing' ICMS following tone-induced excitatory post-synaptic potentials (EPSPs) produced potentiation in response to the paired tones, while an 'anti-pairing' ICMS preceding the tone-induced EPSPs resulted in depression. However, the conventional ICMS affected both excitatory and inhibitory synapses, and thereby could not quantify net excitatory synaptic effects. In the present work, we evaluated the ICMS effects under a pharmacological blockage of inhibitory inputs. The pharmacological blockage enhanced the ICMS effects, suggesting that inhibitory inputs determine a plastic degree of the neural system. Alternatively, the conventional ICMS had an inadequate timing to control excitatory synaptic inputs, because inhibitory synapse determined the latency of total neural inputs.

Pharmacokinetics and enhanced PKR response in patients with chronic hepatitis C treated with pegylated interferon alpha-2b and ribavirin

This study investigated the molecular and pharmacokinetic mechanisms of the enhanced antiviral efficacy associated with pegylated interferon (PEG-IFN) alpha-2b and ribavirin. The study involved comparing the expression of serial double-stranded RNA-activated protein kinase (PKR) before and during treatment in 26 PEG-IFN alpha-2b and 26 conventional IFN alpha-2b recipients matched for age, body weight and dose of ribavirin. The pharmacokinetics of PEG-IFN alpha-2b and ribavirin was analysed in 15 of the 26 PEG-IFN recipients. There was a rapid increase in PKR expression in both treatment groups, although expression from day 2 onwards was maintained at a significantly higher level in the PEG-IFN recipients (P < 0.05). C(max) of PEG-IFN occurred 12-48 h after the initial administration, with t(1/2) and C(min) being 49 h and 190 pg/mL, respectively. In contrast to ribavirin, accumulation of PEG-IFN was minimal. There was no association between serum PEG-IFN and ribavirin levels and virological response. Although baseline expression of PKR before treatment was marginally higher in nonresponders (NRs), from day 2 onwards, sequential PKR expression in response to PEG-IFN was higher in sustained viral responders compared with the NRs (P < 0.05). Significant correlations were found between kinetics of PKR expression and viral decline rates in each phase of hepatitis C virus dynamics (first phase, r = 0.67, P = 0.0006; second phase, r = 0.67, P = 0.001). In conclusion, improvement in pharmacokinetics following pegylation led to higher intracellular PKR expression, which was associated with enhanced virological efficacy of PEG-IFN-based combination therapy. The concentrations of both ribavirin and PEG-IFN alpha-2b were not associated with viral response and PKR expression.

A potent antiviral effect on hepatitis C viral dynamics in serum and peripheral blood mononuclear cells during combination therapy with high-dose daily interferon alfa plus ribavirin and intravenous twice-daily treatment with interferon beta

Hepatitis C virus (HCV) is known to infect and replicate within peripheral blood mononuclear cells (PBMC), thereby enabling the direct evaluation of antiviral mechanisms by analyzing HCV dynamics in PBMC. To address potential molecular differences associated with distinct antiviral regimens, we studied HCV dynamics in both serum and PBMC in 44 patients with HCV genotype 1b and high viral load who were randomly assigned to the following 4 different treatment groups: 1) combination therapy with 6 MU daily of interferon alfa 2b (IFN-alpha2b) plus 800 mg of ribavirin; 2) monotherapy with 6 MU daily of IFN-alpha2b; 3) monotherapy with twice-daily intravenous administration with 3MU of IFN-beta; and 4) monotherapy with daily intravenous administration with 6 MU of IFN-beta. HCV-RNA levels were measured serially using highly sensitive real-time detection polymerase chain reaction (PCR). HCV dynamics in both the serum and PBMC showed a "biphasic" pattern. The exponential decay slopes of the second phase were significantly higher in the combination or twice-daily dosing regimen groups compared with groups 2 or 4 (0.10 +/- 0.08 vs. 0.02 +/- 0.09 or 0.16 +/- 0.09 vs. 0.02 +/- 0.04 day(-1); P <.05 or P <.0005, respectively). Moreover, the viral half-lives in the second phase were significantly shorter in these groups (73.2 +/- 42.5 vs. 240.1 +/- 120.7 or 56.0 +/- 44.6 vs. 361.6 +/- 293.5 hours; P <.05 or P <.05, respectively). Additionally, the slope of HCV decline in PBMC tended to be higher in the combination regimens, as compared with monotherapy. Taken together, our data on HCV dynamics provide molecular insight into utilization of combination or twice-daily dosing regimens to increase rates of sustained viral eradication of HCV.

Risk factors for distant recurrence of hepatocellular carcinoma in the liver after complete coagulation by microwave or radiofrequency ablation

BACKGROUND

In patients with hepatocellular carcinoma (HCC), recurrences in the distant liver often are observed after curative treatment. Microwave coagulation therapy (MCT) and radiofrequency ablation (RFA) have been developed as less invasive alternatives than surgical resection for small HCCs. In the current study, risk factors for distant recurrence of HCC were analyzed in patients in whom complete coagulation was achieved.

METHODS

Ninety-two patients with HCCs < 3 cm in greatest dimension were treated by MCT or RFA percutaneously or laparoscopically. Eighty-four patients in whom complete coagulation was achieved without recurrence in the same subsegment as the primary nodule were included in this study. Distant recurrences were observed in 22 patients. Fifteen possible risk factors for a distant recurrence were analyzed.

RESULTS

When comparing the patients with a recurrence of HCC nodules in the remnant liver to those without recurrence, the authors observed a statistically significant difference only in serum alpha-fetoprotein. The distant recurrence-free survival was analyzed by the Kaplan-Meier method. A statistically significant difference was observed in hepatitis C virus (HCV) infection as an etiopathic agent of underlying liver diseases (P < 0.005) and in the number of the primary HCC nodules (P < 0.05, log-rank test). A multivariate stepwise Cox hazard model revealed that HCV infection and the number of primary HCC nodules were statistically independent risk factors.

CONCLUSIONS

Patients who had more than two HCC nodules accompanied by HCV infection had a high incidence of recurrence of HCC in the remnant liver, even when coagulation by microwave or ablation by radiofrequency was complete.

Interferon therapy for chronic hepatitis C in hemodialysis patients: increased serum levels of interferon

BACKGROUND/AIMS

The efficacy and side effects of interferon (IFN) therapy have not been well clarified in hemodialysis patients with chronic hepatitis C.

METHODS

In 6 of 9 hemodialysis patients with chronic hepatitis C, 3 million units (MU) or 6 MU of recombinant IFN-alpha2b or natural IFN-alpha were administered intramuscularly daily for the first 2 weeks, followed by three times a week for 22 weeks. In the remaining 3 patients, 3 MU of IFN-alpha2b were given three times a week for 24 weeks. Serum concentrations of IFN-alpha2b were measured sequentially after the injection of interferon. Responders were defined as the patients with normal serum aminotransferase and negative serum HCV RNA 6 months after the cessation of IFN therapy.

RESULTS

Three of the 6 patients who were administered IFN daily in the first 2 weeks were responders, while the other 3 withdrew from the therapy due to serious adverse events such as depression, loss of consciousness and persistence of high-grade fever. Serious adverse events were not observed in the 3 patients without daily administration. Half-lives of IFN-alpha2b in hemodialysis patients were significantly longer than those in nonuremic patients (10.0 vs. 6.0 h, p < 0.05). Moreover, the areas under the serum concentration curve of the hemodialysis patients were significantly larger than those of nonuremic patients (756 +/- 223 vs. 324 +/- 223 IU.h/ml, p < 0.05), despite the fact that the dose of IFN-alpha administered to hemodialysis patients was half that administered to nonuremic patients.

CONCLUSIONS

In hemodialysis patients with chronic hepatitis C, pharmacokinetic parameters of IFN may be different from those in nonuremic patients, and daily or high-dose administration of IFN may lead to serious adverse events in those patients.

Hemolysis, elevated liver enzymes, and low platelets syndrome associated with primary anti-phospholipid antibody syndrome

A 28-year-old woman with a history of a spontaneous abortion developed thrombocytopenia, Coombs-negative hemolytic anemia, and liver dysfunction at the sixteenth week of pregnancy. These findings were compatible with hemolysis, elevated liver enzymes, and low platelets (HELLP) syndrome (hemolysis, elevated liver enzymes, and low platelet counts). Moreover, serum anti-phospholipid antibodies were positive, suggesting the association of anti-phospholipid antibody syndrome. An artificial abortion, anti-coagulation therapy, and plasma exchange were performed concomitantly with corticosteroid therapy. She responded to the therapy, a remission was obtained. Anti-phospholipid antibodies may play a role in the pathogenesis of HELLP syndrome.

Hepatic iron contents and response to interferon-alpha in patients with chronic hepatitis C. Relationship to genotypes of hepatitis C virus

Recent reports have shown that response to interferon treatment is influenced by hepatic iron contents in patients with chronic hepatitis C. In those reports, however, hepatitis C virus (HCV) genotypes and serum HCV-RNA levels were not examined. The aim of the present study was to investigate whether hepatic iron contents influence the response to interferon in patients with chronic hepatitis C and whether HCV genotypes and serum HCV-RNA levels play a role in this relationship. Among 65 patients with chronic hepatitis C, hepatic iron contents were significantly high in patients with a history of excess drinking of alcohol (more than 80 g/day) compared to those without, and significantly low in female patients before menopause. Having excluded these patients, hepatic iron contents were significantly higher in patients with genotype 1b infection than those with genotype 2a and 2b infection. There was no significant correlation between hepatic iron contents and plasma HCV-RNA levels. Among the patients with genotype 1b infection, hepatic iron contents were significantly lower in the responders to interferon than those in the nonresponders (429 +/- 100 vs 875 +/- 110 micrograms/g liver, P < 0.05). From these results, it is concluded that response to interferon is mainly influenced by HCV genotypes, while hepatic iron contents may play an important role in response to interferon in patients with genotype 1b infection.

Characteristics of anti-HCV antibody-positive patients with hepatocellular carcinoma on chronic hemodialysis: recommendation of periodic ultrasonography for early detection

We analyzed 10 patients (male:female 9:1, mean age 64.2 years) who developed hepatocellular carcinoma during the observation period of 2 years among 2,164 chronic hemodialysis patients in 23 dialysis centers. Among them, 409 patients were positive for serum anti-HCV antibodies (19%). They were all positive for serum anti-HCV antibodies but negative for HBs antigen. None of the anti-HCV antibody-negative patients developed hepatocellular carcinoma during this period. Although liver function tests of the patients were almost normal, pathological examination of the liver revealed chronic active hepatitis or cirrhosis. Periodic ultrasonographic examination is necessary for early detection of hepatocellular carcinoma in chronic hemodialysis patients with positive anti-HCV antibodies even if liver function tests are within normal ranges.

Beta(+)-thalassemia with hemochromatosis

A 64-year-old man was admitted due to ascites. Laboratory data showed hemoglobin 6.7 g/dl, mean corpuscular volume 82 fl, and ferritin 2,360 ng/ml. Liver biopsy showed hemochromatosis. The diagnosis of beta-thalassemia was suggested by a decreased ratio of beta/alpha-globin synthesis in vitro (0.26). Cloning of the beta-globin gene showed A-to-G mutation in the first base of the ATA box. He was confirmed to be homozygous for this specific allele by beta-gene complex analysis and analysis of Southern blot hybridization of the alpha- and beta-globin genes. His two sons were confirmed to be heterozygous for this allele.

Clinical significance of elevated plasma endothelin concentration in patients with cirrhosis

Endothelin is a newly discovered potent vasoconstrictor peptide. To explain the clinical significance of endothelin in patients with chronic liver diseases, we measured the plasma concentration of endothelin in patients with chronic hepatitis (n = 15), cirrhosis with ascites (n = 8) and cirrhosis without ascites (n = 12), and we compared the findings with the plasma concentration of endothelin in normal controls (n = 14). The plasma endothelin concentration was significantly higher in patients with cirrhosis with ascites than in normal controls (8.3 +/- 2.3 pg/ml vs. 3.3 +/- 1.4 pg/ml, mean +/- S.D., p less than 0.001), whereas no significant difference was observed between normal controls and the other groups of patients (cirrhosis without ascites = 5.0 +/- 1.3 pg/ml; chronic hepatitis = 3.8 +/- 1.2 pg/ml). In patients with cirrhosis, the plasma endothelin concentration showed a significant negative correlation with creatinine clearance (r = -0.73, p less than 0.01), but no significant correlation was observed between plasma endothelin concentration and fractional excretion of filtered sodium. Furthermore, plasma endothelin levels were significantly higher in patients with endotoxemia than in those without (10.1 +/- 2.1 pg/ml vs. 4.9 +/- 1.2 pg/ml, p less than 0.001). From these results, elevated plasma endothelin, which has a close relation to endotoxemia, may play a contributory role in kidney dysfunction in patients with cirrhosis.

V1-receptor mediated GSH efflux by vasopressin from rat hepatocytes

Vasopression increases sinusoidal efflux of GSH in the perfused rat liver. The mechanism of this effect was studied in the perfused rat liver and in isolated rat hepatocytes. Vasopressin stimulated GSH efflux in both systems and a V1-receptor antagonist (OPC-21268) significantly inhibited the effect of vasopressin suggesting that vasopressin stimulates GSH efflux from rat hepatocytes via V1-receptor.

Inhibition of acetaminophen activation by ethanol and acetaldehyde in liver microsomes

Mechanisms of the inhibitory effect of ethanol on acetaminophen hepatotoxicity are controversial. We studied the effects of ethanol and acetaldehyde, an oxidative metabolite of ethanol, on NADPH-dependent acetaminophen-glutathione conjugate production in liver microsomes. Ethanol at concentrations as low as 2mM prevented the conjugate production noncompetitively. Acetaldehyde also inhibited acetaminophen-glutathione conjugate production at concentrations as low as 0.1mM that is comparable with those observed in vivo after social drinking. Acetaldehyde may be involved in ethanol-induced inhibition of acetaminophen hepatotoxicity.

In vitro effect of corticosteroid on immunoregulatory functions in primary biliary cirrhosis

Primary biliary (PBC) has many features, suggesting immunopathogenic mechanisms involved in its etiology. However, none of the therapeutic modalities that are beneficial in many autoimmune diseases have been demonstrated to halt histologic progression of the disease or to induce a complete clinical, biochemical, and histologic remission on this disease. To investigate whether corticosteroids improve the abnormal immunoregulatory functions in PBC, the in vitro effect of corticosteroid on the activity of suppressor T cells and interleukin 2, an inducer of immunoregulatory cells, was evaluated in eight patients with PBC. Defective suppressor T cell activity was found in PBC; however, no clear improvement of T cell activity was observed after in vitro treatment of lymphocytes with corticosteroid. In PBC, interleukin 2 activity was normal, and the same decrease of activity as occurring in healthy controls was observed after corticosteroid treatment. These results suggest that a defect in the responsiveness of suppressor T cell activity to corticosteroid may play, at least in part, a role in the pathogenesis of corticosteroid ineffectiveness in PBC.