Biomedical subjects

H L Wu

Publications and source records attributed to H L Wu.

At least 91 records · Page 5Linked to original sources

PubMed1994

Intrafamilial transmission of hepatitis C virus: the important role of inapparent transmission.

To evaluate the intrafamilial transmission of hepatitis C virus (HCV) 104 index patients with type C chronic liver disease and their 307 family contacts were interviewed. After a questionnaire on the risk factors of parenteral exposure, blood samples were obtained and tested for liver biochemistry and anti-HCV antibody by enzyme-linked immunosorbent assay (Abbott II). Overall, 52 family contacts (17%) were positive for anti-HCV, indicating a higher anti-HCV prevalence among family contacts than among the general population in Taiwan. The anti-HCV prevalences in parents, spouses, children, and other contacts of the patients were 54% (14/26), 28% (25/91), 6.9% (10/143), and 6.4% (3/47), respectively. The contacts of index patients had increasingly greater risk of HCV infection when they became older and had lived longer with index patients. All family contacts were divided into two groups categorized by whether the index patients had or did not have a history of parenteral exposure. Among 126 family contacts of the 42 patients without parenteral exposure, blood transfusion and surgery were the factors significantly associated with HCV infection in these family contacts (odds ratio = 7.26, 95% confidence interval = 2.32-32.67; odds ratio = 3.95, 95% CI = 1.29-12.11, respectively). Risk factors were not significantly associated with HCV infection among 181 family contacts of the 62 index patients with parenteral exposure. It is concluded that the index patients without parenteral exposure appeared to have acquired the disease from HCV-infected family members with risk factors. Most of the index patients had a history of parenteral exposure and in turn served as the source of the disease for family members.

Adult↗

PubMed1994

Regional differences in prostaglandin production rates among porcine intrathoracic vessels.

To investigate the regional variability in intrathoracic vascular prostaglandin (PG) synthesis, we obtained vessel segments from porcine coronary artery (COA), thoracic aorta (AT), common carotid artery (CRA), pulmonary artery (PA), pulmonary vein (PV), and inferior vena cava (IVC). Vascular production rates of 6-keto-PGF1 alpha (an indicator for PGI2), PGF2 alpha, and PGE2 were measured both in unstimulated state and in arachidonic acid-stimulated state using immunosorbent assays. Our results indicated that PGI2 production rate in all vessel segments decayed with time after vessel dissection. In all vessel segments tested under unstimulated conditions, PGI2 production rates were about one order of magnitude higher than PGF2 alpha and PGE2 production rates of the same specimens. Results from unstimulated, 1.5 hr pre-incubated specimens indicated that i) PGI2 production rates in COA, AT, and PV were greater than those in CRA, PA, and IVC; ii) PGF2 alpha production rates from the same specimens were higher in PV than in AT, CRA, and IVC, while these in PA were higher than in IVC; and iii) PGE2 production rates from the same specimens were not significantly different from one another. Arachidonic acid added at about 1.5 hr after vessel harvest stimulated the PGI2 and PGF2 alpha synthesis rates by 3 to 15 folds. However, this arachidonic acid treatment caused 70 to 300-fold increases in PGE2 production rates, reaching levels comparable to PGI2. All three prostanoid production rates under stimulated conditions were also variable among different intrathoracic vessels. Although either physiological gas concentrations or local hemodynamic conditions alone can partially explain our results, which physiological parameter(s) actually causes these regional differences remains to be verified.

Animals↗

PubMed1994

Packaging of hepatitis delta virus RNA via the RNA-binding domain of hepatitis delta antigens: different roles for the small and large delta antigens.

Hepatitis delta virus (HDV) is composed of four specific components. The first component is envelope protein which contains hepatitis B surface antigens. The second and third components are nucleocapsid proteins, referred to as small and large hepatitis delta antigens (HDAgs). The final component is a single-stranded circular RNA molecule known as the viral genome. In order to study the mechanism of HDV RNA packaging, a four-plasmid cotransfection system in which each viral component was provided by a separate plasmid was employed. Virus-like particles released from Huh-7 cells receiving such a cotransfection were found to contain HDV RNA along with three proteins. Therefore, the four-plasmid cotransfection system could lead to successful HDV RNA packaging in vitro. The system was then used to show that the large HDAg alone was able to achieve a low level of HDV RNA packaging. Analysis of a variety of large HDAg mutants revealed that the RNA-binding domain was essential for viral RNA packaging. By increasing the incorporation of small HDAg into virus-like particles, we found a three- to fourfold enhancement of HDV RNA packaging. This effect was probably through a direct binding of HDV RNA, independent from that of large HDAg, with the small HDAg. The subsequent RNA-protein complex was packaged into particles. The results provided insight into the roles and functional domains of small and large HDAgs in HDV RNA packaging.

Antigens, Viral↗

PubMed1994

Effect of monounsaturated fatty acids under fixed P/S and n-6/n-3 ratios on lipid metabolism in rats.

The purpose of the present study was to investigate the effect of monounsaturated fatty acid (MUFA), in particular oleic acid, under fixed P/S and n-6/n-3 ratios on serum and liver lipid metabolism in rats. The male Sprague-Dawley rats aged 28 days were fed diets low in MUFA (LM) or high in MUFA (HM) with or without 1% cholesterol for 4 weeks. The experimental diets contained 10% (w/w) fat. The body weight gain, food efficiency, and liver weight were comparable among the groups except for an increase in liver weight by dietary cholesterol. When cholesterol-added diets were fed, the concentration of serum cholesterol in the HM group was higher than that of the corresponding LM group at second week and at the end of experiment. The concentration of serum triacylglycerol in rats fed a cholesterol-enriched HM diet was markedly lower than that of cholesterol-free counterpart. Both MUFA and cholesterol tended to increase serum low density lipoprotein-cholesterol concentration, but they had no interaction. Serum high density lipoprotein-cholesterol in cholesterol-enriched groups was lower than that in the cholesterol-free counterparts, but it was independent of the MUFA content. Dietary cholesterol markedly increased the concentration of liver cholesterol and triacylglycerol and the increase in liver cholesterol was more marked in the HM group than in the LM group, while the level of liver triacylglycerol was comparable. The fecal excretion of neutral and acidic steroids increased when 1% cholesterol was added to the diets, irrespective of the MUFA content in the diets. Thus, the results indicate that the proposed beneficial effect of MUFA on cholesterol can be modified when diet contains cholesterol.

Animals↗

PubMed1994

Carrier screening and prenatal diagnosis for alpha-thalassemia with biphasic polymerase chain reaction.

Alpha-thalassemia is the most common single gene disorder in Taiwan and Southeast China. The majority of alpha-thalassemic mutations in this area are alpha-thalassemia 1. Homozygous alpha-thalassemia 1 has been recognized as the most important cause of hydrops fetalis. To investigate the incidence of alpha-thalassemia 1 mutations and to characterize its molecular defects, cord blood electrophoresis was performed on 2,000 newborns, of which 99 (5%) cases were found to have hemoglobin (Hb) Bart's levels > 3.0%. A methodology using biphasic polymerase chain reaction (PCR) with nesting primers was developed to characterize the alpha-thalassemia 1 Southeast Asia type (SEA) deletion in the cases with detectable Hb Bart's levels. The SEA deletion was found in 92 (93%) of 99 cases. Prenatal screening was performed on couples with abnormal hematologic indices, and PCR was used to detect couples heterozygous for SEA deletion. Prenatal diagnosis was performed in 21 cases, and four cases were found to have a homozygous SEA deletion. This strategy can be applied to couples who need prenatal genetic counseling for alpha-thalassemia major in this area.

Asia, Southeastern↗

PubMed1994

Nonpeptide endothelin receptor antagonists. I. Effects on binding and signal transduction on human endothelinA and endothelinB receptors.

The effect of a series of endothelin (ET) receptor antagonists, including the novel nonpeptide receptor antagonist, SB 209670, on [125I]ET-1 binding to human ET receptors (ETA and ETB) cloned and stably expressed in Chinese hamster ovary cells was studied. SB 209670 was found to compete for [125I]ET-1 binding with apparent Ki values of 0.43 +/- 0.09 and 14.7 +/- 3.0 nM for ETA and ETB receptors, respectively. This inhibition was competitive because addition of SB 209670 in saturation binding experiments resulted in decreased affinity, with no change in maximum binding. In addition, SB 209670 inhibited ET-1-mediated accumulation of inositol phosphates and intracellular calcium release in a concentration-dependent manner. The racemic mixtures, (+/-)-SB 209670 and (-)-SB 209670, were approximately 1.5 and at least 200-fold less potent than SB 209670. The binding affinity of (+/-)-SB 209670 therefore resides in (+)-antipode. The peptide antagonists, BQ123 (ETA-selective) and RES 701 (ETB-selective), were 40- and 6-fold less potent than SB 209670 in inhibition of [125I] ET-1 binding to ETA and ETB receptors, respectively. The nonselective peptide antagonist, PD 142893, was 75- and 10-fold less potent than SB 209670, whereas the nonpeptide antagonist, bosentan, was approximately 80- and approximately 30-fold less potent than SB 209670 in inhibition of [125I]ET-1 binding to ETA and ETB receptors, respectively. Thus, the present studies indicate clearly that SB 209670 is the most potent nonpeptide ET receptor antagonist yet described.

Animals↗

PubMed1994

[Pharmacokinetics of harringtonine liposomes in rabbits].

After i.v. free harringtonine (FH) and harringtonine liposomes (HL) with high and low encapsulation percentage (En%) to rabbits, their blood concentrations were determined by reverse-phase HPLC. The blood concentration-time curves were shown to fit a two-compartments open model. FH: T1/2 alpha = 1.32 +/- 0.24, T1/2 beta = 32 +/- 6 min; Low En % HL: T1/2 alpha = 4.12 +/- 0.25, T1/2 beta = 106 +/- 5 min; High En % HL: T1/2 alpha = 9.4 +/- 1.2, T1/2 beta = 209 +/- 5 min.

Animals↗

PubMed1994

Trace analysis of acetaldehyde as fluorogenic derivative by high performance liquid chromatography.

A sensitive method is described for the determination of acetaldehyde as a fluorogenic derivative of decahydroacridin-1,8-dione by high performance liquid chromatography. The analytical derivatization is based on the reaction of acetaldehyde in an acidic aqueous system with 1,3-cyclohexanedione and ammonium acetate. The resulting derivative was separated by a reversed-phase C-18 column and monitored with a fluorescent detector (lambda ex, 375nm; lambda em, 512nm). Several parameters affecting the derivatization of acetaldehyde were studied. The linear range of the method for the quantitation of acetaldehyde was between 20 and 800 pmol in aqueous sample (0.5 mL). Application of the method to the analysis of acetaldehyde in plasma was performed.

Acetaldehyde↗

PubMed1993

Impaired fibrinolysis in patients with Blackfoot disease.

Blackfoot disease is a unique endemic and chronic progressive arteriosclerotic vascular disease in southwest area of Taiwan. In this study, we determined the plasma levels of tissue plasminogen activator (tPA), plasminogen activator inhibitor (PAI), urokinase plasminogen activator (uPA), and von Willebrand factor (vWF) antigen in Blackfoot disease patients, in comparison with normal controls from non-endemic areas and the endemic area, Putai. Blackfoot disease patients had mean tPA antigen level of 7.9 ng/ml (n = 27) which was significantly lower (p < 0.05) than both the normal controls with 11.0 ng/ml (n = 20) and the Putai normal controls with 9.7 ng/ml (n = 39). However, the mean PAI-1 antigen level in the patient group was 41.2 ng/ml (n = 28) which was significantly higher (p = 0.0001) than both the normal controls with 19.7 ng/ml (n = 23) and the Putai normal controls with 21.3 ng/ml (n = 40). Furthermore, in the patient group, a significantly lower (p < 0.005) mean uPA antigen level (2.3 ng/ml, n = 18) was noted as compared with that in the normal controls (3.2 ng/ml, n = 14). No significant difference was observed in vWF antigen level between patients and normal controls. This study suggests that a reduced capacity for fibrinolysis is associated with Blackfoot disease.

Adult↗

PubMed1993

Interaction of immobilized human plasminogen and plasmin with streptokinase.

The complex of immobilized human plasminogen (iHPlg) and streptokinase (SK) has a lower catalytic activity in hydrolysis of plasmin-specific substrate S-2251 with a kcat/Km of 0.005 microM-1 x s-1, compared to 0.031 microM-1 x s-1 of immobilized human plasmin (iHPlm) and 0.078 microM-1 x s-1 of HPlm. The SK in the complex could be removed by acid buffer solution, and the iHPlg will remain catalytically active. IHPlm.SK complex could activate bovine plasminogen (BPlg), whereas iHPlg.SK complex could not. IHPlg could be activated by interaction with a combination of SK and HPlg or urokinase. The activated iHPlg.SK complex had the ability to activate BPlg as iHPlm.SK. The reasonable explanation is that iHPlg was converted to iHPlm in reaction with the combination of HPlg and SK. However, iHPlg was converted to a virgin enzyme in reaction with SK alone and could not activate BPlg. A new modified mechanism for the interaction of HPlg or HPlm with SK was proposed.

Amidohydrolases↗

PubMed1993

Molecular characterization and regulation of the human endothelin receptors.

Endothelin receptors (ETRs) are distributed throughout a variety of tissues. Two human cDNAs were identified which encode distinct ETR proteins. One cDNA encoded a 427-amino acid protein that shared 91% identity to rat ETAR. The second cDNA encoded a 442-amino acid protein that was 88% identical to rat ETBR. Ligand binding studies of the cloned receptors expressed in COS cells confirmed that they were pharmacologically ETAR and ETBR subtypes; although the selective antagonist BQ123 showed a potency similar to ET-3 in displacing 125I-ET-1 binding to ETAR. This observation contrasts with rat ETAR pharmacology where BQ123 has a 100-fold higher affinity than ET3. Chinese hamster ovary cells expressing the human ETAR displayed equal potencies in displacing 125I-ET-1 binding, which indicates that rat and human ETAR are pharmacologically distinct. Electrophysiological studies of both ETRs expressed in Xenopus oocytes revealed that they are functional. Northern analysis indicated that the two ETRs are differentially expressed in many tissues. Marmosets maintained on a high fat/high cholesterol diet exhibited 3-fold increase in ETBR mRNA levels with little change in ETAR mRNA levels. Availability of cDNA clones for ETR subtypes can open avenues for future analysis of their role in pathophysiology of various diseases.

Amino Acid Sequence↗

PubMed1993

Hepatitis B and hepatitis C among institutionalized psychiatric patients in Taiwan.

To investigate the seroprevalence of hepatitis B surface antigen (HBsAg) and antibodies to hepatitis C virus (anti-HCV) in a psychiatric institution in Taiwan, where hepatitis B virus (HBV) is hyperendemic, a total of 780 patients with psychiatric disorders were studied. Enzyme-linked immunosorbent assays (ELISA) were used for testing HBsAg and anti-HCV. The prevalence of HBsAg was higher than that of anti-HCV among these patients (18.1% vs. 6.8%, P < 0.0001). The HBsAg carrier rate in these patients was consistent with that of the general population, with a trend for HBsAg carrier rate to be lower in the aged and in females. In contrast, the prevalence of anti-HCV was higher in these patients than in general population. Anti-HCV positivity was found more frequently in patients who had received blood transfusion previously (24% vs. 6.4%, P < 0.05). The majority (92%) of patients with positive anti-HCV did not have a history of apparent parenteral exposure. The prevalence of anti-HCV increased significantly with duration of the psychiatric disorder. The prevalence of anti-HCV also tended to increase with duration of hospitalization but without reaching statistical significance. These findings suggest that these institutionalized psychiatric patients contract hepatitis B, as does the general population in Taiwan, and they should be considered as a specific risk group for hepatitis C infection.

Adult↗

PubMed1993

Detection of hepatitis C virus RNA in peripheral blood mononuclear cells and in saliva.

The nested polymerase chain reaction (PCR) technique was applied to investigate hepatitis C virus (HCV) RNA in the peripheral blood mononuclear cells (PBMCs), saliva, and serum of patients with chronic type C hepatitis. The specificity of the amplified products was analyzed and confirmed by agarose gel electrophoresis, Southern blot hybridization, and restriction endonuclease pattern analysis. HCV RNA was detectable in the PBMCs of 24% (12/50) of the patients. The HCV RNA detected in PBMCs was not due to the contamination from plasma, since no viral sequences could be detected in the third washing of PBMCs. Of the 12 patients with HCV RNA in PBMCs, five were negative for HCV RNA sequences in the serum. Thus the presence of HCV RNA in PBMCs was not strictly correlated to the results for sera. Among 25 patients with HCV RNA in their saliva, 18 were negative for PBMCs. Among 25 patients without HCV RNA in their saliva, five had HCV RNA in PBMCs. In conclusion, PBMCs are an extrahepatic target for chronic HCV infection. However, we do not suggest that PBMCs act as a vehicle for carrying HCV to saliva, since the presence of HCV RNA in PBMCs and in saliva was not closely correlated.

Base Sequence↗

PubMed1993

Human plasmin induces a receptor-mediated arachidonate release coupled with G proteins in endothelial cells.

Treatment of cultured bovine carotid artery endothelial cells with 10(-7) M plasmin increased arachidonate release coupled with the increase in prostacyclin production. The stimulatory effect of plasmin on arachidonate release could be divided into the early and late phases according to its calcium dependency and pertussis toxin sensitivity. The early phase of plasmin-induced arachidonate release was a calcium-dependent and pertussis toxin-sensitive response, which was observed within 20 min after plasmin treatment. The late phase was a calcium-independent and pertussis toxin-insensitive response, which was induced gradually from 20 to 60 min. Induction of the early phase of plasmin's effect required both the lysine binding and catalytic sites in plasmin molecule because it was inhibited either by the binding antagonist tranexamic acid or by the serine protease inhibitor aprotinin. Guanosine 5'-O-(2-thiotriphosphate) potentiated the effect of plasmin in permeabilized or nonpermeabilized cells, indicating that the early phase effect was mediated by a pertussis toxin-sensitive guanosine 5'-triphosphate (GTP)-binding protein. The late phase of plasmin's effect was due to the catalytic activity because it was inhibited by aprotinin but not by tranexamic acid. Microplasmin structurally having the catalytic sites induced a similar late phase effect. Plasmin did not elicit the metabolism of phosphatidyl polyphosphoinositides. These studies demonstrate that the activation of phospholipase A2, which results in arachidonate release, in the early phase of plasmin's effect is a receptor-mediation via GTP-binding protein that is not coupled through phospholipase C activation.

Animals↗

PubMed1993

Determination of thiocyanate anion as an organic derivative by gas chromatography.

A simple and sensitive gas chromatographic method has been established for the determination of biologically active thiocyanate anion as pentafluorobenzyl thiocyanate. The method is based on the partition of an ion-pair from the thiocyanate anion and a complex crypstand to a benzene layer for derivatization with pentafluorobenzyl bromide. The resulting derivative was analyzed by gas chromatography with electron capture detection. The quantitation range for thiocyanate anion was over 0.086 and 3.45 nmol. The detection limit of thiocyanate in 0.2 ml sample is about 34 pmol. The effects of several parameters such as base or acid, reaction time and the amount of pentafluorobenzyl bromide were evaluated for the optimization of partition and derivatization of thiocyanate anion. Application of the method to the analysis of thiocyanate in waste water and human saliva proved to be feasible.

Calibration↗

PubMed1993

[Distribution of harringtonine positively and negatively charged liposome in rat tissues].

Distribution of harringtonine positively and negatively charged liposome (HL(+), HL(-)) and harringtonine free drug (FH) in rat tissues were measured by HPLC. Their LD50 in mice were compared. The results showed that distribution of HL(+), HL(-), In vivo may be changed, that the amount of HL(+), HL(-) was increased in the liver, lung, and spleen and in these tissues it was 2-30-fold higher than that of HF after iv 2 h. HL(+), HL(-) may aid to permeate through the blood-brain, blood-testicle barrier, and to reduce acute lethal toxicity. Areas under the time curve of HL(+), HL(-) in brain and testis within 2 h were 2-4.5 times as much as those of HF. There were significant differences in the fate between negatively and positively charged liposomes in vivo.

Animals↗

PubMed1992

The binding of plasminogen fragments to cultured human umbilical vein endothelial cells.

Glu-plasminogen, kringle 1-5, kringle 1-3, and miniplasminogen exhibited strong binding to human umbilical vein endothelial cells (HUVEC). On the other hand, no significant binding was obtained with microplasminogen and kringle 4. Kringle 1-5 and miniplasminogen, which both contained kringle 5, specifically inhibited the binding of plasminogen to HUVEC while kringle 1-3 did not. The results implied plasminogen molecule contained at least two binding sites, with which it interacted HUVEC. The stronger binding site was located in kringle 5 and the weaker one was in kringle 1-3. Kringle 4 and the active site domain exhibited no significant binding to HUVEC. The interaction of plasminogen with HUVEC is mainly through binding site on kringle 5.

Amino Acid Sequence↗

PubMed1992

Dexamethasone down-regulates the expression of endothelin receptors in vascular smooth muscle cells.

Steroid hormones have been shown to modulate a number of physiological processes in addition to their potent antiinflammatory effects. Endothelin (ET) is a newly discovered vasoconstrictor that is synthesized and released by endothelial cells and acts on adjacent vascular smooth muscle cells by interacting with specific cell surface receptors. Proinflammatory agents such as thrombin and transforming growth factor beta have been shown to up-regulate ET gene expression in vascular endothelial cells. We wondered whether the anti-inflammatory steroids might have any regulatory effect on the ET receptors present in the vascular smooth muscle cells. Rat vascular smooth muscle cells (A-10 cell line, ATCC.CRL 1476) were used as a model system to study the effects of glucocorticoids on ET receptor expression and function. These cells display high density and high affinity ET receptors that belong to the ETA subtype. Pretreatment of these cells with dexamethasone reduced the number of ET receptors by 50-60% without changing the affinity. Of the steroids tested, dexamethasone was most effective followed by prednisolone and hydrocortisone. Aldosterone, a mineralocorticoid, was 5000-fold less potent than dexamethasone. This effect of dexamethasone was dependent on the time of pretreatment and concentration of the steroid used. This down-regulation of ET receptors was also accompanied by an attenuated response to ET-1 in dexamethasone-pretreated cells. The inhibitory effect of dexamethasone was selective for ET receptors because the vasopressin-mediated response was unaffected. In addition, dexamethasone pretreatment of these cells resulted in 50-60% reduction in the steady-state level of ETA receptor mRNA as revealed by Northern analysis. These results suggest that glucocorticoid pretreatment of smooth muscle cells resulted in the down-regulation of the ETA receptor at the mRNA level.

Animals↗