Development of emission factors and emission inventories for motorcycles and light duty vehicles in the urban region in Vietnam.

This paper reports on a 2-year emissions monitoring program launched by the Centre for Environmental Monitoring of the Vietnam Environment Administration which aimed at determining emission factors and emission inventories for two typical types of vehicle in Hanoi, Vietnam. The program involves four major activities. A database for motorcycles and light duty vehicles (LDV) in Hanoi was first compiled through a questionnaire survey. Then, two typical driving cycles were developed for the first time for motorcycles and LDVs in Hanoi. Based on this database and the developed driving cycles for Hanoi, a sample of 12 representative test vehicles were selected to determine vehicle specific fuel consumption and emission factors (CO, HC, NOx and CO(2)). This set of emission factors were developed for the first time in Hanoi with due considerations of local driving characteristics. In particular, it was found that the emission factors derived from Economic Commission for Europe (ECE) driving cycles and adopted in some previous studies were generally overestimated. Eventually, emission inventories for motorcycles and LDVs were derived by combining the vehicle population data, the developed vehicle specific emission factors and vehicle kilometre travelled (VKT) information from the survey. The inventory suggested that motorcycles contributed most to CO, HC and NOx emissions while LDVs appeared to be more fuel consuming.

Long-term effect of interferon alpha-2b plus ribavirin therapy on incidence of hepatocellular carcinoma in patients with hepatitis C virus-related cirrhosis.

We assessed the efficacy of interferon (IFN) alpha-2b plus ribavirin therapy in patients with hepatitis C virus (HCV)-related cirrhosis, and elucidated the risk factors for the development of hepatocellular carcinoma (HCC) to determine whether these therapies might reduce the incidence of HCC. One hundred and thirty-two HCV-cirrhotic patients receiving IFN alpha-2b (3 or 5 MU thrice weekly) and oral ribavirin (1,000-1,200 mg/day) for 24 or 48 weeks were analysed. Cumulative incidence of HCC was estimated by the Kaplan-Meier method. The prognostic relevance of clinical variables and HCC occurrence was evaluated by univariate analysis with the log-rank test and by multivariate Cox's regression analysis. A total of 116 patients completed the treatment and 73 (55%) achieved a sustained virological response (SVR). Stepwise logistic regression analysis showed that nongenotype 1b (P < 0.001) and low viral load (P = 0.018) were independent variables of SVR. During a median follow-up period of 37 (12-63) months, HCC developed in 11 patients with non-SVR and five with SVR (P = 0.0178), whereas there was no difference between those with transient biochemical response and nonresponse (P = 0.5970). The Kaplan-Meier method also showed that old age (>or=60 years) (P = 0.0034) and genotype 1b (P = 0.0104) were associated with HCC occurrence. Using Cox's regression analysis, non-SVR (odds ratio = 3.521, P = 0.036), male (odds ratio = 6.269, P = 0.011) and old age (odds ratio = 3.076, P = 0.049) were independent significant risk factors contributing to HCC development. Our results suggest that achieving SVR by IFN alpha-2b plus ribavirin therapy may decrease the incidence of HCC in patients with HCV-related cirrhosis.

Is it possible to diagnose acute hepatitis C virus (HCV) infection by a rising anti-HCV titre rather than by seroconversion?

The diagnosis of acute hepatitis C virus (HCV) infection relies on documented positive-seroconversion of HCV antibody (anti-HCV). Because of the detection of seroconversion at an earlier stage by second or third generation anti-HCV enzyme immunoassays (EIA), the diagnosis of acute hepatitis C (AHC) may be underestimated. The aim of this study was to evaluate whether rising anti-HCV titre could be used to diagnose AHC or not. Eighteen patients with a clinical diagnosis of acute hepatitis C were enrolled, including eight cases with documented seroconversion to anti-HCV and 10 cases with clinically suspected acute hepatitis C. Four chronic hepatitis C patients with acute exacerbation were selected as a control group. Serial sera were assayed with a third generation anti-HCV (AxSYM, version 3.0; Abbott, Chicago, IL, USA) and recombinant immunoblot assays (RIBA; Chiron HCV 3.0 Strip; Immunoblot, Emeryville, CA, USA) and the titre of anti-HCV expressed as signal/cutoff (S/CO) ratio and the RIBA patterns were correlated. Seven of eight documented AHC (one lacking the initial serum) and five of 10 clinically suspected AHC showed a rising pattern of S/CO values. The initial S/CO values on the first visit were less than 40 in 14 of 18 cases. The RIBA pattern shifted from negative/indeterminate to positive in five of seven documented AHC and 4 of 10 clinically suspected AHC cases. Fifteen of 18 cases had seroconversions of at least one antibody, whilst 85.7% showed a rising S/CO ratio. On the contrary, the S/CO ratio and RIBA pattern remained unaltered in chronic hepatitis C with acute exacerbation. The rise in S/CO was usually accompanied with an increase in the number of RIBA reactive bands and their intensity in acute hepatitis C patients. The rise in S/CO ratios using a third generation anti-HCV assay and the RIBA pattern might be used as a supplemental diagnostic criterion for acute HCV infection.

Mutations in the NS5A and E2-PePHD region of hepatitis C virus type 1b and correlation with the response to combination therapy with interferon and ribavirin.

Nonstructural 5A (NS5A) and the second envelope (E2) proteins of hepatitis C virus (HCV) have the potential to block interferon (IFN)-induced RNA-dependent protein kinase (PKR) and may therefore interfere with the response to IFN therapy, but controversy still exists regarding the relevance of this. This study aimed to assess whether mutations in these regions correlated with the response to combination therapy, IFN and ribavirin. Pretreatment parameters were analysed in 57 HCV-1b patients who had received IFN-alpha2b (3 or 5 MU three times weekly) and ribavirin (800-1200 mg per day) for 24 weeks. The amino acid sequences of the NS5A and PKR-eIF2alpha phosphorylation homology domain (E2-PePHD) were deduced from the corresponding coding sequence, which were determinated by direct sequencing of the HCV genome amplified by the polymerase chain reaction. Twenty (36%) patients achieved a sustained virological response (SVR). The mean number of amino acid substitutions in the NS5A-PKR binding domain (2209-2274), interferon sensitivity-determining region (ISDR) (2209-2248), and E2-PePHD sequence (659-670) in patients with and without SVR were 4.53 +/- 3.31 vs 2.83 +/- 1.78 (P = 0.094), 2.45 +/- 2.74 vs 1.03 +/- 1.32 (P = 0.042) and 0.25 +/- 0.70 vs 0.03 +/- 0.17 (P = 0.109), respectively. Patients with a mutant-type (>/= 4) NS5A-ISDR had a higher rate of SVR (six of nine, 67%) than those with wild-type (five of 22, 23%) (P = 0.038). Stepwise multiple logistic regression analysis of the factors (age, gender, viral load, cirrhosis rate, IFN dosage and amino acid substitutions) revealed that the mutation in NS5A-ISDR (>/= 4 vs < 4) was the only independent variable of treatment outcome. Our study showed that NS5A-ISDR mutations were correlated with the SVR to combination therapy in chronic HCV-1b patients in Taiwan.

Prevalence and clinical implications of hepatitis B virus genotypes in southern Taiwan.

BACKGROUND: Hepatitis B virus (HBV) infection is a major health problem. HBV genotypes may be associated with progression of liver disease. The distribution and clinical implications of HBV genotypes in southern Taiwan are evaluated. METHODS: We used a polymerase chain reaction-restriction fragment length polymorphism genotyping method to determine HBV genotypes. RESULTS: The genotype distribution for 265 patients with chronic HBV infection was as follows: A, 3 (1%); B, 158 (60%); C, 90 (34%); D, 7 (2.5%); E, 0: F, 0; and unclassified, 7 (2.5%). Compared with genotype B patients, genotype C patients had a higher hepatitis B e antigen positive rate and higher fibrosis score. There was no significant difference in the mean age between genotype B and genotype C patients with hepatocellular carcinoma (HCC). However, when patients were stratified by age, the prevalence of genotype C was significantly higher in young HCC patients (<50 years of age) than in age-matched asymptomatic carriers (40% versus 10%, P < 0.001). Using multivariate analysis, the significant risk factors for advanced liver disease (cirrhosis or HCC) for patients with chronic HBV infection were old age, male gender and genotype C. CONCLUSIONS: These results suggest that genotype C is associated with more severe liver diseases than the B variant.

Antiviral treatment responses in patients with chronic hepatitis C virus infection evaluated by a third generation anti-hepatitis C virus assay.

Antibodies to hepatitis C virus (HCV) may decrease or disappear after viral clearance in treated or spontaneously resolved infection. We evaluated the usefulness of serial antibody assays in predicting the antiviral treatment responses. One hundred and four chronic hepatitis C patients who received 24 weeks of interferon and ribavirin combination therapy were assayed with a third generation enzyme immunoassay anti-HCV. The mean titre of anti-HCV decreased by more than 50% (from 89.5 +/- 10.8 to 43.6 +/- 17.5) at 48 weeks post-treatment in patients with a sustained virological response, while in nonsustained virological responders and nonresponders, the titres remained over 85% of the pretreatment level at 48 weeks post-treatment. There was a divergence of anti-HCV titres between sustained and nonsustained virological responders during 6-9 months. By using the ratio of 9-month to 6-month titres as an index and receiver operator characteristic curve analysis with the cut-off point set at 90%, we could differentiate sustained virological responders from nonsustained virological responders with a sensitivity and specificity of 91.7% and 90.9%, respectively, 3 months after treatment. The titre of this third generation anti-HCV decreased progressively in sustained virological responders and this assay may be used to monitor and predict antiviral treatment responses.

Sonographic features of hepatic adenomas with pathologic correlation.

BACKGROUND: We compared the sonographic characteristics of hepatic adenomas with pathologic findings. METHODS: Information over 10 years was collected on 12 patients (six men, six women; mean age = 47 years) with surgically proven hepatic adenomas. Clinical data, sonographic features, and histopathologic findings were reviewed. RESULTS: The tumors in males were smaller and simpler than those in women (p < 0.05, Fisher's exact test). Four of the six larger tumors (>5 cm) showed mixed-echoic patterns corresponding with pathologically intratumoral hemorrhage and necrosis. Four homogeneously hypoechoic tumors had less change in tumor composition. Three homogeneously hyperechoic tumors had evident fatty changes inside. One isoechoic tumor had a hypoechoic rim, that correlated mostly to the tumor itself and compressed liver parenchyma. Seven of the 12 tumors had thin fibrous capsules that were not seen on sonography. CONCLUSION: Hepatic adenomas have variable sonographic appearances depending on changes in the tumor. Hypoechoic, hyperechoic, and mixed-echoic patterns represent simple adenoma, adenoma with fatty metamorphosis, and hemorrhagic necrosis, respectively, in tumors.

Flash echo gray scale imaging with subtraction in assessment of small hepatocellular carcinoma treated with percutaneous ethanol injection: preliminary report.

OBJECTIVE: To assess the therapeutic effect of percutaneous ethanol injection on small hepatocellular carcinoma by using a flash echo imaging system, a newly developed technique for detecting echoes from microbubble contrast agents more efficiently. METHODS: Six patients with 7 small nodular hepatocellular carcinomas, proved by fine-needle aspiration cytologic or pathologic examination, were included. Percutaneous ethanol injection was performed until there was no intratumoral color signal on conventional color and power Doppler ultrasonography. A bubble contrast agent was then injected, and flash echo imaging in the subtraction mode was performed for assessment of the therapeutic effect. Dynamic computed tomography, magnetic resonance imaging, and hepatic angiography were also used for evaluation of the therapeutic effect. RESULTS: Five tumors had perfusion defects that were equal in size to or larger than the tumors. No tumor stain was shown on hepatic angiography. Two tumors had partial perfusion defects. Viable tumors were confirmed by tumor resection in 1 case and cytologic examination in the other. CONCLUSIONS: Our preliminary results show that flash echo imaging with subtraction has potential value in evaluation of the therapeutic effect of percutaneous ethanol injection on small hepatocellular carcinoma.