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S Sauleda

Publications and source records attributed to S Sauleda.

27 records · Page 2Linked to original sources
PubMed1999

High-throughput real-time reverse transcription-PCR quantitation of hepatitis C virus RNA.

We describe a rapid and reproducible method for assessment of the hepatitis C virus (HCV) load in serum samples. The method combines Taqman technology (Roche) and the ABI Prism 7700 (Perkin Elmer) real-time sequence detection system. We have optimized a single-tube reverse transcription-PCR (RT-PCR) that contains a dual-labeled fluorogenic probe to quantify the 5' noncoding region (5' NCR) of HCV. The probe contains a fluorescent reporter at the 5' end and a fluorescent quencher at the 3' end. The use of such a probe combined with the 5'-3' nuclease activity of Taq polymerase allows direct quantitation of the PCR product by the detection of a fluorescent reporter released in the course of the exponential phase of the PCR. For accurate quantitation of the number of copies of HCV in samples containing unknown quantities, we have used serial dilutions of a synthetic 5' NCR RNA standard of HCV that was previously quantified with an isotopic tracer. The method has a 5-log dynamic range (10(3) to 10(7)). The coefficient of regression of the standard curve was, on average, 0.98. The intra-assay and the interassay coefficients of variation of the threshold cycle were 1% and 6.2%, respectively. Seventy-nine RNA samples from the sera of infected patients were quantified by this method. Comparison of the results with those obtained by other quantitation methods (the Quantiplex 2.0 branched-DNA assay and the Superquant assay from the National Genetics Institute) revealed a significant correlation with all of the results. The mean values were also statistically comparable. In conclusion, the high sensitivity, simplicity, and reproducibility of the real-time HCV RNA quantitation which allows the screening of large numbers of samples, combined with its wide dynamic range, make this method especially suitable for monitoring of the viral load during therapy and tailoring of treatment schedules.

Adult↗
PubMed1999

Profiles of GBV-C/hepatitis G virus markers in patients coinfected with hepatitis C virus.

GBV-C/Hepatitis G virus (GBV-C/HGV) is a newly discovered viral agent, found widely among healthy blood donors and among individuals at risk of parenterally transmitted infections. GBV-C/HGV is found frequently in coinfection with HCV. A population of 109 HCV positive patients was examined for the presence of GBV-C/HGV RNA and antibodies to E2. Of the 109 patients, 23 (21%) had serum GBV-C/HGV RNA in serum, 39 (36%) had only antibodies to E2 and 8 (7%) were positive for both markers, with an overall prevalence of 64%. Different serologic and virological patterns were observed in GBV-C/HGV exposed patients according to their infection status. Active infection was characterized by positive RT/PCR signal with primers for both the 5'UTR and NS5 genomic regions, viremia levels above 10(4) copies/mL by real time quantitative RT/PCR and absence of detectable anti-E2. In the transition phase between active infection and recovery, GBV-C/HGV RNA was only detectable by RT/PCR using primers from the 5' untranslated region and viremia levels were below 10(4) copies/ml by quantitative PCR, with or without simultaneous presence of anti-E2 antibodies. Resolved infection was characterized by absence of detectable viremia and, in most patients, by the presence of anti-E2.

5' Untranslated Regions↗
PubMed1997

Humoral immune response to the E2 protein of hepatitis G virus is associated with long-term recovery from infection and reveals a high frequency of hepatitis G virus exposure among healthy blood donors.

The second envelope protein (E2) of the hepatitis G virus (HGV) was expressed in Chinese hamster ovary (CHO) cells and showed a molecular weight of approximately 60 to 70 kd, with 15 to 25 kd of the size contributed by N-linked glycosylation. An enzyme-linked immunosorbent assay (ELISA) using HGV-E2 was developed to test for antibodies to this protein (anti-E2) in human sera. High sensitivity was achieved by developing monoclonal antibodies (mAbs) to HGV-E2, which were used as capture antibodies in the ELISA. Our studies revealed that 16% of healthy Spanish blood donors were exposed to HGV, indicating that additional routes of viral transmission besides parenteral exposure might exist. An even higher prevalence of exposure to HGV (52%-73%) was found in several groups at risk of parenteral exposure to infectious agents, i.e., intravenous drug users, transfusion history, hemophiliacs, and hepatitis C virus (HCV)-positive patients. Most anti-E2-positive patients were HGV-RNA-negative and vice versa, indicating an inverse correlation of these two viral markers. A panel of 16 posttransfusion patients followed for up to 16 years revealed that patients who develop an anti-E2 response become HGV-RNA-negative, while patients who do not develop anti-E2 are persistently infected. Immunity to HGV seems to be long-lasting, because circulating antibody to E2 could still be detected 14 years after seroconversion. Sequence comparisons showed that E2 is highly conserved among isolates collected worldwide, indicating that immune escape variants are not common in HGV infections. This reflects on a molecular level why HGV infections usually are cleared spontaneously by the host. However, possible mechanisms of HGV persistence, as found in some patients, remain to be elucidated.

Amino Acid Sequence↗
PubMed1995

[Hepatocarcinoma and killer cell activity].

BACKGROUND: Alterations in natural killer (NK) cell activity have been described in patients with different neoplasms including hepatocellular carcinoma (HCC). Nonetheless, the relationship between this activity and the clinical situation of the patients with HCC is not well established. METHODS: A group of 33 patients with hepatic cirrhosis and non treated HCC, a group of 22 patients with only hepatic cirrhosis, and a control group of 31 healthy blood donors were studied. In all the subjects the NK cell activity was determined against the K562 cell line marked with 51Cr by the short duration cytotoxicity test, and the number of NK cells/microliters in peripheral blood was determined by flow cytometry (FACScan) using the anti-CD3, CD16 and CD56 monoclonal antibodies. RESULTS: No statistically significant differences were observed in the NK cell activity or in the number of NK cells/microliters among the three groups studied. In the patients with HCC the NK cell activity was not related to the degree of hepatic function, however the patients with tumors greater than 5 cm in diameter or multinodular tumors showed a significant decrease in NK cell activity without a decrease in the number of NK cells/microliters. CONCLUSIONS: The natural killer cell activity in patients with hepatocellular cancer is not related to subjacent hepatic cirrhosis but is related to tumor size.

Aged↗
PubMed1995

Hepatitis C virus infection in renal transplant recipients: epidemiology, clinical impact, serological confirmation and viral replication.

The presence and significance of hepatitis C virus infection was evaluated in 241 renal transplant recipients from our hospital. Hepatitis C virus antibodies were tested by second-generation enzyme immunoassay, followed by second- and third-generation immunoblot assays (RIBA-2 and RIBA-3); hepatitis C virus RNA was measured by nested polymerase chain reaction. Hepatitis C virus antibodies, which were detected in 46.5% of patients, were mainly present before transplantation and independently associated with the total amount of transfused blood, time in hemodialysis and duration of posttransplant follow up. Liver dysfunction (alanine aminotransferase elevation) was observed in 50% of antibody-positive recipients, and 92.5% of patients with chronic liver disease without hepatitis B infection were infected with hepatitis C virus. Most antibody-positive patients (78.4%) tested positive by RIBA-2, but 21.6% were indeterminate; RIBA-3 was positive in 90% of these indeterminates. Hepatitis C virus RNA detection was positive in 96% of antibody-positive cases tested, in 20% of patients who were already anti-HCV negative before transplantation and also demonstrated persistence of HCV infection in all cases who, being antibody positive prior to transplantation, lost these antibodies during follow up (9% of transplanted patients). In conclusion, hepatitis C virus infection is extremely prevalent in renal transplant recipients from Spain and is the main cause of chronic liver disease in these patients. Confirmation by supplemental assays of anti-HCV antibodies is not necessary, but hepatitis C virus RNA testing is indispensable to detect those cases who lose or do not develop hepatitis C virus antibodies.

Adult↗
PubMed1991

Immunological abnormalities in pediatric AIDS.

HIV infection of a fetus from an infected mother has severe immunological implications because it destroys still immature immune system. The abnormalities observed are precocious in the infants. When the infection occurs in perinatal period, clinical and immunological manifestations can present themselves at the age of 2-5 years. Two patterns of HIV infection can be distinguished. Humoral immunodeficiency is present in a high proportion of patients and leads to repeated bacterial infections and progression of the disease. Immunoglobulin substitution therapy improves clinical manifestations and can help to avoid viral replication.

Acquired Immunodeficiency Syndrome↗