Prevalence and follow-up of occult HCV infection in an italian population free of clinically detectable infectious liver disease

Background

Occult hepatitis C virus infection (OCI) is a recently described phenomenon characterized by undetectable levels of HCV-RNA in serum/plasma by current laboratory assays, with identifiable levels in peripheral blood mononuclear cells (PBMCs) and/or liver tissue by molecular tests with enhanced sensitivity. Previous results from our group showed an OCI prevalence of 3.3% in a population unselected for hepatic disease. The present study aimed to evaluate OCI prevalence in a larger cohort of infectious liver disease-free (ILDF) subjects. Clinical follow-up of OCI subjects was performed to investigate the natural history of the infection.

Methods and Findings

439 subjects referred to a Turin Blood Bank for phlebotomy therapy were recruited. They included 314 ILDF subjects, 40 HCV-positive subjects and 85 HBV-positive subjects, of whom 7 were active HBV carriers. Six subjects (4/314 ILDF subjects [1.27%] and 2/7 active HBV carriers [28%]) were positive for HCV-RNA in PBMCs, but negative for serological and virological markers of HCV, indicating OCI. HCV genotypes were determined in the PBMCs of 3/6 OCI subjects two had type 1b; the other had type 2a/2c. OCI subjects were followed up for at least 2 years. After 12 months only one OCI persisted, showing a low HCV viral load (3.73×10¹ UI/ml). By the end of follow-up all OCI subjects were negative for HCV. No seroconversion, alteration of liver enzyme levels, or reduction of liver synthesis occurred during follow-up.

Conclusions

This study demonstrated the existence of OCI in ILDF subjects, and suggested a high OCI prevalence among active HBV carriers. Follow-up suggested that OCI could be transient, with a trend toward the decrease of HCV viral load to levels undetectable by conventional methods after 12–18 months. Confirmation studies with a longer follow-up period are needed for identification of the OCI clearance or recurrence rates, and to characterize the viruses involved.     

Mauthner cell-evoked synaptic actions on pacemaker medullary neurons of a weakly electric fish

The present study was designed to examine the synaptic events in neurons of the pacemaker nucleus of Gymnotus carapo during the increase in rate of the electric organ discharge following activation of Mauthner cells. Pacemaker and relay cells were investigated using intracellular recordings which were performed under two different conditions: (1) with the pacemaker nucleus spontaneously discharging and (2) after its activity was abolished by anesthesia. Mauthner axon activation induced an increase in the rate of pacemaker cell discharges. This response was accompanied by an increase in the slope of the pacemaker potential (up to 110%) and a depolarization of these cells. The discharges of relay cells followed one to one those of pacemaker cells. In contrast to that observed in pacemaker cells, only brief depolarizing antidromic effects could be evoked in relay cells after Mauthner axon activation. In quiescent pacemaker cells, Mauthner cell activation induced a prolonged (up to 500 ms) depolarizing potential with an average amplitude of 1.92 ± 0.82 mV; its latency was 4.43 ± 1.14 ms. Our data indicate that, within the pacemaker nucleus, the population of pacemaker cells is the only target for Mauthner cell-evoked, short-latency excitatory synaptic actions. Accepted: 1 March 1997     

Crystallographic studies on D-amino acid oxidase.

D-amino acid oxidase, a flavoprotein from hog kidneys, has been crystalized in two different forms. Orthorhombic prisms have been obtained from the enzyme.benzoate complex at pH 8.3; the space group is C2221 and the cell dimensions are a = 325A, b = 138.8 A, c = 200 A. At lower pH values, the enzyme crystallizes in trigonal prisms with a = b = 116.0 A, c = 399 A, space group P3112 or its enantiomorph. The two crystal forms have been obtained at 28 degrees C while at 4 degrees C only weak evidence of crystallization has been detected. In both crystalline modifications, the protein is highly associated.     

Immunochemical properties of D-amino-acid oxidase

Antiserum against homogeneous hog kidney D-amino-acid oxidase (D-amino-acid: oxygen oxidoreductase (deaminating), EC 1.4.3.3) was elicited in rabbits, and monospecific antibodies were prepared by affinity chromatography. The antibodies inhibited up to 90% of hog D-amino-acid oxidase activity, and 100% of the enzyme could be immunoprecipitated. The antibodies inhibited both holoenzyme and reconstituted apoprotein to a similar degree, indicating that they did not interfere with the FAD-binding site of the protein. The antibodies inhibited D-amino-acid oxidase activity from other mammalian species to a similar degree, while the enzyme activities from birds, amphibians, fishes and yeast were inhibited and immunoprecipitated to lower extents. In immunoblotting experiments, after SDS-polyacrylamide gel electrophoresis, the antibodies recognized a single band of about 40 kDa in all the species analyzed, and the entity of the signal was inversely related to the phylogenetic distance from mammals. The antibodies did not inhibit D-alanine dehydrogenase activity from Escherichia coli, but gave positive bands in immunoblotting.     

DNA polymerase switching: effects on spontaneous mutagenesis in Escherichia coli

Escherichia coli possesses five known DNA polymerases (pols). Pol III holoenzyme is the cell's main replicase, while pol I is responsible for the maturation of Okazaki fragments and filling gaps generated during nucleotide excision repair. Pols II, IV and V are significantly upregulated as part of the cell's global SOS response to DNA damage and under these conditions, may alter the fidelity of DNA replication by potentially interfering with the ability of pols I and III to complete their cellular functions. To test this hypothesis, we determined the spectrum of rpoB mutations arising in an isogenic set of mutL strains differentially expressing the chromosomally encoded pols. Interestingly, mutagenic hot spots in rpoB were identified that are susceptible to the actions of pols I–V. For example, in a recA730 lexA (Def) mutL background most transversions were dependent upon pols IV and V. In contrast, transitions were largely dependent upon pol I and to a lesser extent, pol III. Furthermore, the extent of pol I-dependent mutagenesis at one particular site was modulated by pols II and IV. Our observations suggest that there is considerable interplay among all five E. coli polymerases that either reduces or enhances the mutagenic load on the E. coli chromosome.     

Carvedilol protects against cisplatin-induced oxidative stress, redox state unbalance and apoptosis in rat kidney mitochondria

Cisplatin is a highly effective chemotherapeutic agent which causes severe nephrotoxicity. Studies have suggested that reactive oxygen species, mainly generated in mitochondria, play a central role in cisplatin-induced renal damage. A wide range of antioxidants have been evaluated as possible protective agents against cisplatin-induced nephrotoxicity; however a safe and efficacious compound has not yet been found. The present study is the first to evaluate the protective potential of carvedilol, a beta-blocker with strong antioxidant properties, against the mitochondrial oxidative stress and apoptosis in kidney of rats treated with cisplatin. The following cisplatin-induced toxic effects were prevented by carvedilol: increased plasmatic levels of creatinine and blood urea nitrogen (BUN); lipid peroxidation, oxidation of cardiolipin; oxidation of protein sulfhydryls; depletion of the non-enzymatic antioxidant defense and increased activity of caspase-3. Carvedilol per se did not present any effect on renal mitochondria. It was concluded that carvedilol prevents mitochondrial dysfunction and renal cell death through the protection against the oxidative stress and redox state unbalance induced by cisplatin. The association of carvedilol to cisplatin chemotherapy was suggested as a possible strategy to minimize the nephrotoxicity induced by this antitumor agent.