Yoon J. Park

Bio: Yoon J. Park is an academic researcher from National Institutes of Health. The author has contributed to research in topics: Ribavirin & Hepatitis C virus. The author has an hindex of 3, co-authored 4 publications receiving 165 citations.

The natural history of acute hepatitis C: clinical presentation, laboratory findings and treatment outcomes

Abstract: Aliment Pharmacol Ther 2011; 33: 559–565 Summary Background Acute hepatitis C has variable modes of presentation and frequently results in chronic infection. Its optimal management has yet to be defined. Aim To establish natural history and complications of treatment of acute hepatitis C. Methods Data from all patients presenting with acute hepatitis C to the National Institutes of Health between 1994 and 2007 were reviewed. Results Twenty-five patients were identified. Symptoms were reported by 80% and jaundice by 40%. Aminotransferase levels and hepatitis C virus (HCV) RNA levels fluctuated greatly; 18% of patients were intermittently negative for HCV RNA. Five patients recovered spontaneously whereas 20 developed chronicity or received interferon-based therapy during the acute phase. Among 15 patients treated during the acute phase with peginterferon with or without ribavirin for 24 weeks, all became HCV RNA negative within 4–8 weeks, and all except two (HIV-positive) achieved a sustained virological response. Side effects (particularly psychiatric) were common and limited treatment in 30%. Conclusions Among 25 patients with acute HCV infection, fluctuating illness was common and spontaneous recovery occurred in only 20%. Anti-viral treatment with a 24-week course of peginterferon and ribavirin was highly effective, but marked by frequent and severe side effects.

Effect of ribavirin on viral kinetics and liver gene expression in chronic hepatitis C

Abstract: Objective Ribavirin improves treatment response to pegylated-interferon (PEG-IFN) in chronic hepatitis C but the mechanism remains controversial. We studied correlates of response and mechanism of action of ribavirin in treatment of hepatitis C. Design 70 treatment-naive patients were randomised to 4 weeks of ribavirin (1000–1200 mg/d) or none, followed by PEG-IFNα-2a and ribavirin at standard doses and durations. Patients were also randomised to a liver biopsy 24 h before or 6 h after starting PEG-IFN. Hepatic gene expression was assessed by microarray and interferon-stimulated gene (ISG) expression quantified by nCounter platform. Temporal changes in ISG expression were assessed by qPCR in peripheral-blood mononuclear cells (PBMC) and by serum levels of IP-10. Results After 4 weeks of ribavirin monotherapy, hepatitis C virus (HCV) levels decreased by 0.5±0.5 log 10 (p=0.009 vs controls) and ALT by 33% (p Conclusions Ribavirin is a weak antiviral but its clinical effect seems to be mediated by a separate, indirect mechanism, which may act to reset IFN-responsiveness in HCV-infected liver.

A rapid immunochromatographic assay for hepatitis B virus screening.

Abstract: Simple, rapid and accurate assays for hepatitis B surface antigen (HBsAg) and hepatitis B e antigen (HBeAg) are helpful for clinical diagnosis and field epidemiological surveys. A commercially developed, rapid immunochromatographic test for simultaneous detection of HBsAg and HBeAg was evaluated using a total of 2463 selected samples (827 frozen sera, 1011 fresh sera, and 625 whole blood samples). Results of the rapid test were compared with standard enzyme immunoassay (EIA) methods for HBsAg and HBeAg detection. The accuracy of the rapid test was excellent and was similar for frozen sera, fresh sera and whole blood. The overall sensitivity and specificity for the detection of HBsAg were 95 and 100%, and the corresponding positive and negative predictive values were 100 and 99.7%, respectively. The sensitivity and specificity for the detection of HBeAg were slightly less than that for HBsAg, and were 80 and 98%, with positive and negative predictive values of 91 and 94%, respectively. Thus, compared with the EIA method, the rapid test was highly sensitive and accurate for the detection of HBsAg although somewhat less sensitive and specific for detection of HBeAg. Because of its speed, simplicity and flexibility, the rapid test is ideally suited for HBsAg and HBeAg screening in population-based epidemiological studies and in low risk populations, particularly in regions of the world where hepatitis B is endemic.

Natural history of acute and chronic hepatitis C.

Abstract: Hepatitis C virus (HCV) infection remains a major global health burden. Hepatitis C causes significant liver-related morbidity and mortality due to hepatic decompensation and development of hepatocellular carcinoma. In addition, extra-hepatic manifestations of hepatitis C are frequent. There is a very large interindividual variability in the natural history of both acute and chronic hepatitis C which can be explained in part by a combination of various host, viral and environmental factors. Successful antiviral treatment can prevent short- and long-term complications of HCV infection in many patients. Still, the relative contribution of distinct risk factors for disease progression in different phases of HCV infection needs to be better defined. Personalized treatment approaches for HCV infection should consider individual risk profiles to avoid both under- and over-treatment - which will remain important also in upcoming era of interferon-free treatment of hepatitis C.

Recent advances in nanoparticle-based lateral flow immunoassay as a point-of-care diagnostic tool for infectious agents and diseases

Abstract: Lateral flow immunoassay (LFIA) technology is a paper-based, point-of-care strip biosensor designed to detect a specific analyte in a given sample. This type of assay is now of great interest to researchers for its cost-effectiveness, simplicity, portability and rapidness of detection of analytes, including but not limited to areas such as agriculture, food, biomedicine and pathogen detection. Various nanoparticles (such as metal nanoparticles, carbon-based nanoparticles, quantum dots, lanthanides and up-converting phosphor) functionalized by an antibody to detect an analyte protein or molecular marker present in the surface of an infectious pathogen are used for in LFIAs. Herein, we review the principle of the assay and recent advancements made in terms of the different approaches and designs of the assay towards the detection of infectious agents and diseases.