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Biomedical subjects

C W Chu

Publications and source records attributed to C W Chu.

At least 19 recordsLinked to original sources
PubMed2004

Changes in magnetocardiogram patterns of infarcted-reperfused myocardium after injection of superparamagnetic contrast media.

The changes in spatio-temporal patterns of magnetocardiograms were investigated following injection of superparamagnetic iron-oxide (SPIO) nanoparticles using a dog model of ischemia/reperfusion. Acute myocardial infarction was induced by ligation of the left anterior descending coronary in two anesthetized open-chest dogs. Following 60 min coronary occlusion and 30 min reperfusion, dogs were subjected to injections of SPIO at a dose of 0.56 mg Fe/kg using a catheter inserted into the left atrium. Magnetocardiograms were measured before coronary occlusion, 15 min after reperfusion and immediately after administration of the SPIO. Magnetic field maps of early reperfused myocardium showed spatio-temporal field distributions consistent with anterior myocardial infarction. Magnetic field distribution measured after injection of SPIO revealed additional spatio-temporal features most prominent during ventricular repolarization due to augmentation/fragmentation of the ST-segment detected at several sensor locations. No significant differences in MCG patterns were noted following contrast agent injections in a dog without coronary occlusion. In conclusion, preliminary experimental evidence appears to support the notion that superparamagnetic contrast agents increase the sensitivity of standard MCG and may have an important implication for magnetocardiography in the assessment of regional myocardial ischemia, infarction and perfusion.

Animals↗
PubMed2004

Field-induced reentrant novel phase and a ferroelectric-magnetic order coupling in HoMnO3.

A reentrant novel phase is observed in the hexagonal ferroelectric HoMnO3 in the presence of magnetic fields in the temperature range defined by a plateau of the dielectric constant anomaly. The plateau evolves with fields from a narrow dielectric peak at the Mn-spin rotation transition at 32.8 K in zero field. The anomaly appears both as a function of temperature and as a function of magnetic field without detectable hysteresis. This is attributed to the indirect coupling between the ferroelectric (FE) and antiferromagnetic (AFM) orders, arising from an FE-AFM domain wall effect.

Journal Article↗
PubMed2004

Unconventional superconductivity and electron correlations in the cobalt oxyhydrate Na0.35CoO2.yH2O from nuclear quadrupole resonance.

We report a careful 59Co nuclear quadrupolar resonance measurement on the recently discovered cobalt oxyhydrate Na0.35CoO2.yH(2)O superconductor from T=40 K down to 0.2 K. We find that in the normal state the spin-lattice relaxation rate 1/T(1) follows a Curie-Weiss type temperature (T) variation, 1/T(1)T=C/(T-theta), with theta=-42 K, suggesting two-dimensional antiferromagnetic spin correlations. Below T(c)=3.9 K, 1/T(1) decreases with no coherence peak and follows a T(n) dependence with n approximately 2.2 down to approximately 2.0 K but crosses over to a 1/T(1) proportional to T variation below T=1.4 K, which suggests non-s-wave superconductivity. The data in the superconducting state are most consistent with the existence of line nodes in the gap function.

Journal Article↗
PubMed2002

Adult-to-adult living donor liver transplantation at the Asan Medical Center, Korea.

Between February 1997 and December 2001, 311 adult-to-adult living donor liver transplants (A-A LDLTs) were performed at the Asan Medical Center for patients above 20 years of age. Indications for A-A LDLT were: chronic hepatitis B (203), chronic hepatitis C (5), hepatocellular carcinoma (64), alcoholic cirrhosis (9), cryptogenic cirrhosis (4), secondary biliary cirrhosis (5), primary biliary cirrhosis (1), Wilson' s disease (2), autoimmune hepatitis (1), hepatic tuberculosis (1), cholangiocarcinoma (1), fulminant hepatic failure (14) and primary non-function of cadaveric liver graft (1). Of 311 A-A LDLTs, 36 were of medical high urgency, 20 were for acute and subacute hepatic failure, 15 were for hepato-renal syndrome and 1 was for primary non-function. Recipient age ranged from 27 to 64 years. Donor age ranged from 16 to 62 years. There was no donor mortality. Implanted liver grafts were categorized into seven types: 175 modified right lobe (MRL), 70 left lobe, 32 right lobe, 20 dual grafts, 10 left lobe plus caudate lobe, three extended right lobe and one posterior segment. In MRL, the tributaries of the middle hepatic vein were reconstructed by interpositioning a vein graft. Indication for dual graft implantation was the same as single graft A-A LDLT, and four of 20 were emergency cases. Of 20 dual grafts, 14 received two left lobes, four received a left lobe and a lateral segment, one received a right lobe and a left lobe and one received a lateral segment and a posterior segment. Graft volume ranged from 28% to 83% of the standard liver volume of the recipients. There were 33 (10.6%) in-hospital mortalities (< 4 months) among the 310 patients after 311 A-A LDLTs. Of the 36 patients receiving emergency transplants, 31 survived. These encouraging results justify the expansion of A-A LDLT in coping with increasing demands, even in urgent situations. We have aimed to introduce the establishment of the efficacy of A-A LDLT in various end-stage chronic and acute liver diseases, as well as new technical advances to overcome small graft-size syndrome by using dual-graft implantation and MRL, both of which were first developed in our department.

Adult↗
PubMed2001

Clinical, virological, and pathological significance of hepatic bile duct injuries in Chinese patients with chronic hepatitis C.

PURPOSE: Hepatic bile duct injuries are characteristic histological findings in patients with chronic hepatitis C virus (HCV) infection. However, the pathogenesis and clinical significance of this phenomenon remain unclear. The aims of this study were to evaluate the prevalence and clinical significance of hepatic bile duct injuries in Chinese patients with chronic hepatitis C. METHODS: One hundred and seventeen Chinese patients with chronic hepatitis C were enrolled. Clinical, biochemical, immunological (serum autoantibodies and cryoglobulinemia), histological, and virological data (serum HCV RNA titer and HCV genotype) were compared between patients with and without hepatic bile duct injuries. RESULTS: Eighty-three (71%) of the 117 patients with chronic hepatitis C had hepatic bile duct injuries. Patients with hepatic bile duct injuries had a significantly higher frequency of HCV genotype 1b; a higher mean serum globulin level; significantly higher mean scores for histological periportal necro-inflammation, portal inflammation, and fibrosis; and more severe portal lymphoid aggregation/follicles when compared with patients without hepatic bile duct injuries (P < 0.05, all). No significant differences in the presence of serum autoantibodies, cryoglobulinemia, mean serum HCV RNA titer, or response to interferon treatment were noted between the two groups. Multivariate logistic regression analysis showed that HCV genotype 1b infection, portal inflammation, and lymphoid aggregation/follicles were significant independent predictors associated with hepatic bile duct injuries. CONCLUSIONS: The presence of hepatic bile duct injuries in Chinese patients with chronic hepatitis C was significantly correlated with HCV genotype 1b infection, and the patients with these injuries had more severe portal inflammation and formation of lymphoid aggregates/follicles.

Adult↗
PubMed2001

Economic decision analysis model of screening for lung cancer.

The objective of this study was to evaluate the potential clinical and economic implications of an annual lung cancer screening programme based on helical computed tomography (CT). A decision analysis model was created using combined data from the Surveillance, Epidemiology and End Results (SEER) registry public-use database and published results from the Early Lung Cancer Action Project (ELCAP). We found that under optimal conditions in a high risk cohort of patients between 60 and 74 years of age, annual lung cancer screening over a period of 5 years appears to be cost effective at approximately $19000 per life year saved. A sensitivity analysis of the model to account for a 1-year decrease in survival benefit and changes in assumptions for incidence rate and costs generated cost effectiveness estimates ranging from approximately $10800 to $62000 per life year saved. Based on the assumptions embedded in this model, annual screening of high risk elderly patients for lung cancer may be cost effective under optimal conditions, but longer term data are needed to confirm if this will be borne out in practice.

Aged↗
PubMed2001

Hepatic steatosis in chronic hepatitis C virus infection: prevalence and clinical correlation.

BACKGROUND AND AIMS: Hepatic steatosis is a histological characteristic in patients with chronic hepatitis C virus (HCV) infection. The aim of this study was to evaluate the prevalence of hepatic steatosis in Chinese patients with chronic hepatitis C, and to look for possible correlation with various histopathological changes and to look for possible correlation with various clinical and pathologic variables. METHODS: One hundred and six patients were enrolled, and patients with alcoholism or diabetes mellitus were excluded. Clinical, biochemical and virologic data, including HCV genotype and serum HCV-RNA titer and histological findings, were compared between patients with and without hepatic steatosis. RESULTS: Fifty-five (52%) of the 106 patients with chronic hepatitis C had hepatic steatosis. Patients with hepatic steatosis had significantly higher mean serum levels of triglyceride and gamma-glutamyl transpeptidase, higher body mass index, and a higher incidence of obesity compared with patients without hepatic steatosis. No significant differences in serum HCV-RNA titer and HCV genotype or the response to interferon therapy were noted between the two groups. Histological analysis showed patients with hepatic steatosis had a significantly higher mean fibrotic score than patients without hepatic steatosis (1.9 +/- 1.2 vs 1.3 +/- 1.0; P = 0.016). There were no significant differences in the severity of necroinflammation, the presence of lymphoid aggregation/follicle or bile duct damage between the two groups. Multivariate logistic regression analysis showed that independent predictors associated with hepatic steatosis were obesity or a histology fibrotic score of > or = 2. CONCLUSION: It was found that 52% of Chinese patients with chronic hepatitis C had hepatic steatosis. Patients with hepatic steatosis were more frequently obese and had more severe hepatic fibrosis.

Adult↗
PubMed2001

Comparison of clinical, virologic and pathologic features in patients with acute hepatitis B and C.

BACKGROUND AND AIMS: The clinical outcomes of adult-acquired acute infection of hepatitis C virus (HCV) and hepatitis B virus (HBV) are quite different. In order to compare the clinical, biochemical, virologic and pathologic pictures in these two groups of patients, we enrolled 22 adult patients with acute hepatitis C and 16 adult patients with acute hepatitis B, on whom liver biopsies were performed within 3 months of acute onset of the illness. RESULTS: The results showed that a significantly younger age, a higher ratio of the clinical symptoms of jaundice, nausea, vomiting, and poor appetite, a higher mean serum level of alanine transaminase, aspartate transaminase, and total bilirubin were present in patients with acute hepatitis B patients than in those with acute hepatitis C (P < 0.05). There was a significantly higher degree of periportal inflammation and total necro-inflammatory activity in the acute hepatitis B patients (P = 0.002 and 0.049, respectively). Fifteen (68.2%) of the 22 patients with acute hepatitis C had detectable serum HCV-RNA, but only two (14.3%) of the 14 tested patients with acute hepatitis B had detectable serum HBV-DNA, detected by using the branched DNA signal amplification assay. Eighteen (82%) of the 22 acute hepatitis C patients and none of the 16 acute hepatitis B patients progressed into a chronic hepatitis stage (P < 0.001). CONCLUSION: The manifestations of mild clinical symptoms, lower mean serum transaminases and bilirubin levels, a lesser degree of histological periportal necroinflammation, and more patients with a high circulatory viral load among the acute hepatitis C patients, may lead to more of that group developing chronicity than patients with acute hepatitis B.

Acute Disease↗
PubMed2001

Clinical, virologic, and pathologic significance of elevated serum alpha-fetoprotein levels in patients with chronic hepatitis C.

Elevated serum alpha-fetoprotein (AFP) in patients with chronic hepatitis C is not uncommonly seen, but the pathogenesis of this phenomenon remains unclear. The aims of this study were to assess the prevalence of elevated serum AFP in patients with chronic hepatitis C and to evaluate the clinical, virologic, and histopathologic significance of this phenomenon. One hundred and fifteen Chinese patients with a histologic diagnosis of chronic hepatitis C were enrolled. None had evidence of hepatocellular carcinoma by image study at enrollment and for at least 2 years' follow-up. Of the 115 patients, 33 (29%) had elevated serum AFP (more than 12 ng/mL). There was a significantly lower mean serum albumin (4.0 +/- 0.1 vs. 4.3 +/- 0.1 gm/dL, p <0.001) and higher mean scores for periportal necroinflammation (3.3 +/- 0.3 vs. 2.3 +/- 0.2, p = 0.007) and fibrosis (2.3 +/- 0.2 vs. 1.1 +/- 0.1, p < 0.001) in patients with elevated serum AFP when compared with patients without elevated serum AFP. Patients with elevated serum AFP had significantly more incidences of genotype 1b infection when compared with patients without elevated serum AFP (77% vs. 51%, p = 0.021). Mean serum hepatitis C virus (HCV) RNA titer showed no significant difference between the two groups. Multivariate logistic regression analysis showed that as serum albumin of less than 4.2 gm/dL, a histology fibrotic score of more than 3, and HCV genotype 1b infection were significantly independent predictors associated with elevated serum AFP. In conclusion, elevated serum AFP levels were significantly correlated with lower serum albumin levels, advanced fibrosis/cirrhosis, and genotype 1b infection in patients with chronic hepatitis C.

Hepatitis C, Chronic↗
PubMed2001

A new 3-D display method for 12-lead ECG.

A new three-dimensional (3-D) 12-lead electrocardiogram (ECG) display method is presented which employs a 3-D rectangular coordinate system to display the 12-lead cardiac electric signals in two 3-D graphs. The 3-D graph consists of a temporal axis representing the time domain of the cardiac signals, a spatial axis representing the lead positions, and an amplitude axis representing the voltages of the cardiac signals. The six horizontal plane leads and the other six frontal plane leads were displayed in two 3-D graphs, respectively. The voltages of the cardiac signals were represented in rainbow-like colors. Cubic interpolation was employed to insert interconnecting points between neighboring leads on each plane and to smooth the surface of the 3-D ECG graphs. The 3-D ECG graphs of a normal subject, a patient with myocardial infarction, and a patient with left bundle branch block were presented in this paper. This new display method could not only be used as a complementary display method to the 12-lead ECG, but also provide physicians with an overall integral view about the spatial distribution of the cardiac signals.

Color↗
PubMed2001

Deferoxamine-induced dysplasia of the knee: sonographic features and diagnostic performance compared with magnetic resonance imaging.

OBJECTIVE: To evaluate the features and diagnostic performance of sonography in the assessment of deferoxamine-induced dysplasia of the knee. METHODS: The left knees of 32 patients with thalassemia who were receiving regular blood transfusions and chelation therapy were studied with sonography for signs of deferoxamine-induced bone dysplasia. Abnormal physeal and metaphyseal changes detected on sonography included notching at the metaphyseal corner, a blurred or irregular peripheral juxtaphyseal metaphyseal contour, and widening of the peripheral juxtaphyseal metaphyseal echogenic interface. The accuracy of sonography in diagnosing dysplasia was evaluated by using magnetic resonance imaging as the standard of reference. RESULTS: There were 14 true-positive findings, 10 true-negative findings, 7 false-negative findings, and 1 false-positive sonographic diagnosis of dysplasia, giving 67% sensitivity, 91% specificity, a 93% positive predictive value, and a 59% negative predictive value. CONCLUSION: Sonography was specific but only moderately sensitive in the diagnosis of deferoxamine-induced dysplasia at the knee when compared with magnetic resonance imaging.

Adolescent↗
PubMed2001

Hepatitis C viral genotype influences the clinical outcome of patients with acute posttransfusion hepatitis C.

Most patients with an acute infection of hepatitis C virus (HCV) will develop chronic hepatitis, and only about 15-20% of the cases will resolve spontaneously. The mechanism for the different outcomes in patients with acute HCV infection remains unclear. HCV genotype has been recognized as an important factor affecting the clinical course and outcome of chronic hepatitis C patients. In order to evaluate the role of HCV genotype in the clinical course and outcome of acute posttransfusion hepatitis C, 67 patients with acute posttransfusion hepatitis C from a prospective study of posttransfusion non-A, non-B hepatitis were enrolled. Thirty-nine patients (58.2%) were HCV genotype 1b. Among the 67 patients with acute posttransfusion hepatitis C, 53 (79.1%) progressed to chronic hepatitis. Significantly more patients with genotype 1b than non-1b genotypes developed chronic hepatitis (89.7% vs. 64.3%; P = 0.019). There was no significant difference in gender, mean age, amount of transfused blood, hepatitis symptoms, jaundice, incubation period, peak serum alanine transaminase, or serum HCV RNA titer between patients with HCV genotype 1b and non-1b infections. Patients who developed chronic hepatitis had a significantly greater incidence of genotype 1b infection (66.0% vs. 28.6%; P = 0.013) and a longer incubation period (7.3 weeks vs. 5.4 weeks; P = 0.052) than patients whose infection was resolved. Patients with a genotype 1b infection that resolved itself spontaneously all had an incubation period of less than 6 weeks. Multivariate logistic regression analysis revealed that genotype 1b and an incubation period > or = 6 weeks were significant predictive factors for the development of chronic hepatitis. Therefore, the HCV genotype can influence the outcome of patients with acute HCV infection.

Acute Disease↗
PubMed2001

Degradation kinetics of reactive dye by UV/H2O2/US process under continuous mode operation.

Degradation of a dye, C. I . Reactive Red 120, in dyeing waatewater by the process o UV/H2O2/US was studied with a bench-scale reactor under the continuous mode of operation. The effects of dyeing wastewater flow rate and the feeding rate of an oxidant, H2O2, on the color removal efficiency of the process were investigated. The significance of ultrasonic (US) combined with UV irradiation was also investigated and the performances of the process on color removal were evaluated. The results showed that the decoloration process followed a pseudo first-order kinetic model and the UV light is the most significant factor on dye removal. Besides, at higher flow rates, incomplete color removal was observed due to relatively insufficient irradiation time (low degradation rate). In order to achieve a higher degradation rate, the feeding rate of H2O2 should be increased.

Coloring Agents↗
PubMed2000

Effects of pravastatin on left ventricular mass in patients with hyperlipidemia and essential hypertension.

Left ventricular (LV) mass is a powerful predictor for future cardiovascular events. Epidemiologic studies have shown that hyperlipidemia is associated with higher LV mass. The effects of statin therapy for hyperlipidemia on LV mass have not been studied. To determine the effects of statin therapy on LV mass, we prospectively studied 3 groups of age and body surface area-matched patients: group 1 (n = 20), patients with systemic hypertension and hyperlipidemia treated with pravastatin plus anti-hypertensive drugs; group 2 (n = 20), patients with hypertension and hyperlipidemia treated with hypertensive agents and diet control alone; and group 3 (n = 20), hypertensive patients with normolipidemia treated with antihypertensive agents. A group of controls without hypertension or hyperlipidemia was used for comparison. Echocardiograms were recorded at baseline and after 6-month therapy. All hypertensive groups showed significant decreases in LV mass index after treatment. Group 1 had the greatest decrease in LV mass and it was significantly higher than in groups 2 and 3. Multivariate analysis revealed that regression of LV mass was significantly correlated only with the use of statins and sex (p = 0.005 and 0.01, respectively, R(2) = 0.47). Linear regression analysis in group 1 showed a significant correlation between changes in arterial compliance and LV mass regression (r = 0.57, p = 0.01). Thus, the addition of a statin may have an additional effect on reducing LV mass, independent of lipid-lowering effects.

Echocardiography↗
PubMed2000

Seroprevalence of GB virus C/hepatitis G virus-RNA and anti-envelope antibody in high-risk populations in Taiwan.

BACKGROUND: GB Virus C (GBV-C)/hepatitis G virus (HGV) was identified in 1995-1996 as a transfusion-transmissible virus. The diagnosis of GBV-C/HGV infection is based on the detection of GBV-C/HGV-RNA by using polymerase chain reaction. Recently, an enzyme immunoassay detecting the antibodies to the viral protein, E2 envelope protein (anti-envelope) of GBV-C/HGV, has been developed. METHODS: Serum GBV-C/HGV-RNA and anti-envelope antibody were determined in 76 cases of intravenous drug users (IVDU), 76 patients with regular hemodialysis and in 80 prostitutes to evaluate the GBV-C/HGV infection rate among high-risk populations in Taiwan. Seventy-six healthy blood donors were randomly selected and were used as a control group. RESULTS: The prevalence of GBV-C/HGV-RNA in high-risk populations was 33% for IVDU, 16% for patients with hemodialysis and 13% for prostitutes, which was significantly higher than the 3% obtained in the control group (P < 0.05 for all groups). The prevalence of anti-envelope antibody was 13% for IVDU, 21% for patients with hemodialysis and 23% for prostitutes, which was not significantly different from the control group (11%). Among the 99 subjects who had positive GBV-C/HGV markers, 97 were tested for exclusive positivity for either GBV-C/HGV-RNA or anti-envelope antibody. CONCLUSIONS: The presence of serum anti-envelope antibody usually indicates the clearance of serum GBV-C/HGV-RNA in patients infected with GBV-C/HGV. GBVirus-C/HGV infection in high-risk populations, determined by the presence of serum GBV-C/HGV-RNA, may underestimate the true level of past and present infection.

Adult↗
PubMed2000

Chinese alcoholic patients with esophageal cancer are genetically different from alcoholics with acute pancreatitis and liver cirrhosis.

OBJECTIVE: It is a mystery why some alcoholic patients acquire certain organ-specific complications of alcoholism, whereas other alcoholic patients acquire different ones. The aim of this study was to investigate the differences among Chinese alcoholic patients with esophageal cancer, acute pancreatitis, and liver cirrhosis by studying the genetic polymorphisms of ADH2, ADH3, ALDH2, and P4502E1. METHODS: Liver alcohol dehydrogenase (ADH), aldehyde dehydrogenase (ALDH), and cytochrome P4502E1 (P4502E1) are polymorphic at the ADH2, ADH3, and ALDH2 loci and the 5'-flanking region of the P4502E1. Using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method, we determined the polymorphism of the above-mentioned alcohol metabolizing genes in 59 alcoholics with carcinoma of the esophagus (alcoholic esophageal Ca), 87 acute alcoholic pancreatitis patients, 116 alcoholics with liver cirrhosis (alcoholic cirrhosis), 19 alcoholics with both liver cirrhosis and acute pancreatitis (alcoholic P plus C), and 241 nonalcoholic patients. RESULTS: The results showed that the allele frequency of ALDH2*2 was significantly higher in the alcoholic esophageal Ca group than in the alcoholic pancreatitis and alcoholic cirrhosis groups. The allele frequency of ADH2*1 was significantly higher in the alcoholic esophageal Ca patients than in nonalcoholic control groups. The ALDH2*2 was significantly lower in alcoholic groups (except the alcoholic esophageal Ca group) than in nonalcoholic control groups. The allele frequencies of ADH2*1 and ALDH2*2 are higher in alcoholic patients with esophageal Ca than alcoholic patients without it. The genotype distribution of P4502E1, detected by RsaI and PstI, was not different among alcoholic patients with different organ diseases. CONCLUSIONS: The allele frequency of ADH2*1 and ALDH2*1 are different among subpopulations of alcoholics, suggesting that alcoholic patients with different specific types of organ damage are genetically different. The Chinese alcoholic patients with the ADH2*1 and ALDH2*2 allele are more susceptible to esophageal Ca.

Adult↗