No abstract

No abstract

In this work, we have shown that hepatitis C virus (HCV) and hepatitis B virus (HBV) can coexist in the same hepatocyte using double fluorescent in situ hybridization in liver biopsy samples from patients with chronic HCV infection with occult HBV infection. Digital image analysis of hybridization signals showed that the HBV DNA levels in coinfected hepatocytes were lower than those in cells infected only with HBV. This finding supports the hypothesis of inhibition of HBV replication by HCV. Furthermore, HCV RNA levels were lower in coinfected cells than in cells infected only with HCV, suggesting that HBV may also inhibit HCV replication.Hepatitis B virus (HBV) belongs to the Hepadnaviridae family of animal viruses, and its genome consists of a circular partially double-stranded DNA molecule of 3.2 kb in length which contains four overlapping reading frames that code for surface proteins (HBsAg), core proteins (HBc/HBeAg), the viral polymerase, and the transcriptional transactivator X protein (HBx) (9).Hepatitis C virus (HCV) is classified in the Hepacivirus genus of the Flaviviridae family, and its genome is a positive-stranded RNA of 9.6 kb in length that encodes a large polyprotein that undergoes proteolytic processing by cellular and viral proteinases to generate the individual viral proteins (17).As HBV and HCV share similar transmission routes, coinfection with the two viruses is not a rare event (3,6,7). Clinical data obtained from chronic HBV carriers superinfected with HCV suggest that HCV may inhibit HBV replication (13,15,20). This hypothesis is supported by the fact that patients with chronic HCV infection frequently have a special form of HBV infection, termed occult HBV infection (2,8,10,12). This is characterized by the presence of low levels of HBV DNA in serum and/or in liver in the absence of detectable HBsAg in serum. This inhibition may be mediated by the host immune response (via the induction of cytokines such as interferons) or by a direct effect of HCV proteins. In this regard, it has been shown that HCV core and NS2 proteins inhibit HBV replication and gene expression in vitro (4,5,19,21,22).Direct interference mediated by HCV proteins can occur in vivo only if both HBV and HCV coexist in the same hepatocyte. However, it has not been demonstrated whether HBV and HCV infect the same cell in the liver of patients coinfected with the two viruses. To address this issue, we have used double fluorescent in situ hybridization to determine the presence of HBV DNA and HCV RNA in liver biopsy samples from six patients with chronic hepatitis C (anti-HCV positive, serum HCV RNA positive) and occult HBV infection (HBsAg negative, serum HBV DNA positive).Patients underwent a liver biopsy for diagnostic purposes. After liver samples were obtained, they were divided into two portions. One fragment was processed for histological diagnosis and for in situ hybridization, and the other was embedded in RNAlater (QIAGEN, Hilden, Germany) in less than 30 seconds after being obtained and stored at Ϫ20°C. At th...

a b s t r a c tThe integration of wind power in power systems results in a reduction in greenhouse gas emissions. Thus, it has a positive environmental impact. However, the operation of these power systems becomes increasingly complex, owing mainly to random behaviour of the wind.In the case of island power systems, this problem is even more difficult. The traditional solution is to use diesel generators as an alternative power supply. For a wind-only power supply, an energy storage system is required. If the topography of the island makes possible the use of pumped storage hydropower plants, this is, nowadays, the most suitable energy storage system. This paper presents a novel method of Pelton turbine operation with no water flow, as a way to provide fast power injection in the case of an abrupt wind power decrease, or a wind-generator trip. This operation mode allows maximizing wind power penetration in a reliable and efficient way. This method has been validated by computer simulations, and will be tested during the commissioning of a combined wind-pumped storage power plant in an autonomous power system, on a small island.

No abstract