High-gain 1.3 µm GaInNAs semiconductor optical amplifier with enhanced temperature stability for all-optical signal processing at 10 Gb/s.

We report on the complete experimental evaluation of a GaInNAs/GaAs (dilute nitride) semiconductor optical amplifier that operates at 1.3 µm and exhibits 28 dB gain and a gain recovery time of 100 ps. Successful wavelength conversion operation is demonstrated using pseudorandom bit sequence 27-1 non-return-to-zero bit streams at 5 and 10 Gb/s, yielding error-free performance and showing feasibility for implementation in various signal processing functionalities. The operational credentials of the device are analyzed in various operational regimes, while its nonlinear performance is examined in terms of four-wave mixing. Moreover, characterization results reveal enhanced temperature stability with almost no gain variation around the 1320 nm region for a temperature range from 20°C to 50°C. The operational characteristics of the device, along with the cost and energy benefits of dilute nitride technology, make it very attractive for application in optical access networks and dense photonic integrated circuits.

Genotype 4 HCV infection is difficult to cure with pegylated interferon and ribavirin. Results from a Greek Nationwide Cohort Study.

BACKGROUND AND AIM: Patients with genotype 4 (G4) chronic hepatitis C (CHC) are considered a difficult to treat population, although current data on G4 treatment responsiveness and duration are controversial. Greece represents a country with an intermediate prevalence of G4 infections, offering an opportunity to compare treatment outcomes by genotype and to identify potential prognostic factors for sustained virologic response (SVR). METHODS: All CHC patients from the HepNet.Greece, an ongoing nationwide cohort study on viral hepatitis, with known hepatitis C virus (HCV) genotype who received treatment with Peg-IFNa and ribavirin were analyzed. RESULTS: From 4443 patients, 951 (61.7% males, 78.4% Greeks, median age 40.6 years, 10% cirrhosis) fulfilled the inclusion criteria. G4 was found in 125 (13.1%) patients. Genotype distribution was not significantly different between Greeks and immigrants. Patients with G4 had similar odds of SVR compared to G1 but significantly lower compared to G2/G3. Age, treatment discontinuation, presence of cirrhosis and previous history of HCV-treatment were associated with lower probabilities of SVR. Ethnicity did not affect SVR for all genotypes while response to treatment was similar between Greek and Egyptian patients groups (35.7% vs 40.9%, p=0.660%) with G4 infection. The relation between SVR and genotype did not substantially change after adjustment for age, gender, cirrhosis, treatment interruption and history of HCV-treatment. CONCLUSIONS: The findings of this large cohort of CHC patients with a well balanced genotype distribution further supports the idea of considering G4 as a difficult to treat genotype. Further investigation is needed to identify genotype specific prognostic factors.

0.48Tb/s (12x40Gb/s) WDM transmission and high-quality thermo-optic switching in dielectric loaded plasmonics.

We demonstrate Wavelength Division Multiplexed (WDM)-enabled transmission of 480Gb/s aggregate data traffic (12x40Gb/s) as well as high-quality 1x2 thermo-optic tuning in Dielectric-Loaded Surface Plasmon Polariton Waveguides (DLSPPWs). The WDM transmission characteristics have been verified through BER measurements by exploiting the heterointegration of a 60 µm-long straight DLSPPW on a Silicon-on-Insulator waveguide platform, showing error-free performance for six out of the twelve channels. High-quality thermo-optic tuning has been achieved by utilizing Cycloaliphatic-Acrylate-Polymer as an efficient thermo-optic polymer loading employed in a dual-resonator DLSPPW switching structure, yielding a 9 nm wavelength shift and extinction ratio values higher than 10 dB at both output ports when heated to 90°C.

Multi-format all-optical processing based on a large-scale, hybridly integrated photonic circuit.

We investigate through numerical studies and experiments the performance of a large scale, silica-on-silicon photonic integrated circuit for multi-format regeneration and wavelength-conversion. The circuit encompasses a monolithically integrated array of four SOAs inside two parallel Mach-Zehnder structures, four delay interferometers and a large number of silica waveguides and couplers. Exploiting phase-incoherent techniques, the circuit is capable of processing OOK signals at variable bit rates, DPSK signals at 22 or 44 Gb/s and DQPSK signals at 44 Gbaud. Simulation studies reveal the wavelength-conversion potential of the circuit with enhanced regenerative capabilities for OOK and DPSK modulation formats and acceptable quality degradation for DQPSK format. Regeneration of 22 Gb/s OOK signals with amplified spontaneous emission (ASE) noise and DPSK data signals degraded with amplitude, phase and ASE noise is experimentally validated demonstrating a power penalty improvement up to 1.5 dB.

Significant epidemiological changes in chronic hepatitis C infection: results of the nationwide HEPNET-GREECE cohort study.

BACKGROUND AND AIMS: Hepatitis C virus (HCV) infection is an important health problem worldwide. The aim of the study is to describe the baseline characteristics and possible epidemiological changes of the patients with chronic HCV infection included in a nationwide Greek study. PATIENTS AND METHODS: two thousand eight hundred seventeen (2817) patients, followed-up at 20 hepatology centres throughout Greece between the years 1997 and 2006 were enrolled in the study. RESULTS: Intravenous drug use (IDU) and history of blood transfusion prior to 1992 was reported in 30.7% and 22.6% of our patients, respectively. In 1865 (66.2%) patients with known genotypes, the distribution for genotype 1, 2, 3 and 4 was 45.1%, 7%, 34% and 13.9% respectively. Genotype 1 was more common in older people, in women (55.9% p<0.001) and patients with transfusion-related hepatitis (61.6% p<0.001). Genotype 3 was more common in younger patients, in men (43% p<0.001) and in IDUs (63.3% p<0.001). A significant reduction of transfusion-related hepatitis C incidence (p<0.001) in conjunction with the proportion of genotype 1 (p<0.001) was observed during the last three decades while an increase in IDU infected patients and genotype 3 was detected. CONCLUSIONS: Our study showed a significant change in HCV genotype distribution and source of HCV infection during the last three decades and under that scope, urgent actions are needed in order to control the spread of HCV infection.

A randomized trial to assess the efficacy of interferon alpha in combination with ribavirin in the treatment of interferon alpha nonresponders with chronic hepatitis C: superior efficacy of high daily dosage of interferon alpha in genotype 1.

A randomized trial was conducted to assess the efficacy of daily (QD) or thrice weekly (TIW) administration of interferon-alpha (IFN) in high doses in combination with ribavirin (1.0-1.2 g/day) in patients with chronic hepatitis C (CHC) who were nonresponders to previous IFN monotherapy. Interferon was administered as 10 MU IFN (QD or TIW) for 4 weeks, followed by 5 MU IFN (QD or TIW) for 20 weeks, and then by 3 MU IFN (QD or TIW) for 24 weeks. Sustained virological response (SVR) was evaluated in 142 patients who received at least one dose of medication. One-fourth of the patients achieved SVR, 26% of those treated with IFN QD and 25% of those treated with IFN TIW (P = 0.85). For genotype 1 patients, SVR rates were 32.4 and 15.8% for IFN QD and IFN TIW, respectively, whereas for genotype non-1 patients the corresponding SVR rates were 20.6 and 36.4%, respectively (test of homogeneity: P = 0.031). This finding was further confirmed by multivariate logistic regression analysis where a statistically significant interaction (P = 0.012) was found between treatment and HCV genotype indicating that the IFN QD regimen was superior to IFN TIW among genotype 1 patients whereas, among genotype non-1 patients, the two treatments were similar (odds ratio of SVR in IFN QD vs IFN TIW: 3.33 among genotype 1 patients, 95% CI: 1.00-11.14). In conclusion, re-treatment of patients not responding to previous IFN monotherapy with a combination of high daily dose of IFN with ribavirin may be beneficial for genotype 1 infected patients.

Treatment of hepatocellular carcinoma with combined suppression and inhibition of sex hormones: a randomized, controlled trial.

We tested the hypothesis that a combination of sex hormone suppression and inhibition of their target receptors might improve survival for patients with hepatocellular carcinoma (HCC). Eighty-five consequent, previously untreated HCC patients with inoperable disease, were randomized to receive the luteinizing hormone-releasing hormone (LR-RH)-analogue triptorelin and the antiestrogen tamoxifen (33 patients) or triptorelin plus the antiandrogen flutamide (23 patients), or only placebo (29 patients) in a double blind fashion. All groups were comparable as to age, sex, tumor extension, underlying cirrhosis and biochemical parameters. The tamoxifen (TMX) group had a significantly longer survival (282 days) compared with flutamide (112 days) and with placebo (127 days) groups (P = .0238, log rank test). The upper quartile of patients in the TMX group lived 384 days or longer, and most of them (57.1%) were women (P < .0005), in contrast to the upper quartile of the placebo (170 days, 16.7% women) and the flutamide group (134 days, 33.3% women). The calculated tumor volume doubling time (TVDT) was significantly higher in the TMX group (296 days) than in the other two groups (99 and 101 days for placebo and flutamide groups, respectively, P = .023). In a Cox proportional hazards model, the TMX treatment, along with the baseline Okuda's HCC stage, the hepatitis B surface antigen, the portal vein diameter, the carcino embryonic antigen (CEA) and a self-assessment score of quality of life, were covariates predicting survival. Although the degree of serum sex hormone suppression was not a significant predictor of survival, the interaction of female sex and TMX treatment, it was (P = .0052).(ABSTRACT TRUNCATED AT 250 WORDS)

Hepatitis C virus infection in Greece and its role in chronic liver disease and hepatocellular carcinoma.

The aim of this study was to evaluate the prevalence of hepatitis C virus infection (HCV) in Greece, to estimate its frequency in chronic liver disease and to explore the role of HCV infection in the aetiology of hepatocellular carcinoma. A series of 1034 patients with chronic liver disease of various aetioloigies and 299 patients with hepatocellular carcinoma allocated to two case-control studies was tested for anti-HCV. Twelve recent reports on HCV infection in Greece were reviewed and analyzed. The results of the present study indicate the existence of a large pool of HCV infection in Greece and an impressive spread of the virus in high-risk groups. Chronic HCV infection was found to account for 83.6% of patients with chronic non-A, non-B hepatitis parenterally transmitted, 56.5% of cases of sporadic community-acquired disease and for almost 1/4 of all patients with chronic liver disease. The relative risks for development of hepatocellular carcinoma of patients with chronic HCV infection was 6.3 in the first and 13.7 in the second case-control study, increasing to 20.0 and 18.7, respectively, when hepatitis B surface antigen (HBsAg) was positive. Serum HBV-DNA was positive and/or anti-HBc IgM levels were high in 12 of 15 (80%) patients with hepatocellular carcinoma positive only for HBsAg, and in 7 of 15 (47%) positive both for HBsAg and antibodies to HCV. The present data support the view that hepatitis B and C virus have an interacting role in the origin of hepatocellular carcinoma.