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Biomedical subjects

L F Wang

Publications and source records attributed to L F Wang.

At least 55 records · Page 3Linked to original sources
PubMed1999

Hepatitis C virus in peripheral blood mononuclear cells from a chronically infected patient receiving liver graft from infected donor.

BACKGROUND: In hepatitis C virus (HCV)-positive patients receiving HCV-positive liver allografts either the donor or recipient strain overtakes the other strain. Whether these changes are reflected in peripheral blood mononuclear cell (PBMC)-associated virus is unknown. METHODS: We analyzed by single-strand conformation polymorphism and sequencing HCV RNA from serum and PBMCs from a liver transplant recipient whose indigenous strain was replaced by the donor strain. RESULTS: Only the recipient strain was detectable in serum and PBMCs 3 and 5 days after transplantation; at day 7 and 8, a mixture of both was present in the PBMCs, but only recipient strain was detectable in serum. This coincided with the peak presence of donor DNA in recipient PBMCs. From day 14 on, HCV sequences in serum and PBMCs were indistinguishable. CONCLUSIONS: Overtake phenomenon in the setting of liver transplantation from infected donors to infected recipients is manifested in PBMCs. Cells released from infected graft carry donor HCV strain.

Aged↗
PubMed1999

Repetitive acidosis protects the ischemic heart: implications for mechanisms in preconditioned hearts.

Repetitive brief ischemic episodes (ischemic preconditioning, PC) result in transient intracellular acidosis and protect the heart from subsequent ischemic injury, potentially through a protein kinase C (PKC)-dependent mechanism. We hypothesized that repetitive brief acidification of the heart without concomitant ischemia would also protect the heart from ischemic injury via a PKC-dependent mechanism. Isolated rat hearts underwent 30 min of global ischemia following control perfusion (CTL), or after PC or repetitive acidosis (RA), in the presence of absence of chelerythrine, a specific PKC inhibitor. Intracellular pH, PCr and ATP were measured using 31P NMR spectroscopy, while intracellular sodium [Na]i was measured using 23Na spectroscopy. Na,K-ATPase activity was measured prior to ischemia and on reperfusion. Both PC and RA resulted in transient acidification prior to ischemia. Ischemic injury, as assessed by creatinine kinase (CK) release on reperfusion, was reduced in both the PC and RA hearts [63+/-14 and 16+/-4 IU/g dry weight (dw) respectively, v 705+/-72 IU/gdw for control P<0.001], and was associated with improved functional recovery on reperfusion. PC and RA each significantly reduced Na,K-ATPase activity prior to ischemia (8.18+/-0.47 and 7.76+/-0.54 micromol ADP/h/mg protein) when compared to control (11.05+/-0.54 micromol ADP/h/mg protein P<0.05), limited the rate of ATP depletion during ischemia, and resulted in more rapid normalization of [Na]i on reperfusion. Chelerythrine resulted in intermediate CK release in PC and RA hearts (443+/-48 and 375+/-72 IU/gdw, P<0.001 v PC, P<0.01 v control), but did not alter the rate of ATP depletion or [Na]i kinetics in either PC or RA hearts. PC and RA each protect the ischemic heart, having in common ATP preservation during ischemia and more rapid normalization of [Na]i on reperfusion. These effects, not modulated by protein kinase C, are consistent with the hypothesis that ATP preservation during ischemia provides enhanced substrate for sodium efflux via the Na,K-ATPase on reperfusion.

Acidosis↗
PubMed1999

Virus-like particles of calicivirus as epitope carriers.

The VP60 of rabbit haemorrhagic disease virus (RHDV), when expressed in baculovirus, self-assembles into virus-like particles (VLP) which are antigenically and immunogenically indistinguishable from native virions. When the N-terminal 30 amino acid residues of VP60 were deleted and substituted by a well characterized six residue epitope from bluetongue virus capsid protein VP7 (Btag), the fusion protein retained its ability to self-assemble into VLPs. However, the size of these particles was only 27 nm, compared to 40 nm of VLPs derived from native VP60. The antigenicity of both VP60 and the Btag was retained as evident from ELISA and Western blot analyses. When Btag was fused at the C-terminus of VP60 without deletion, the fusion proteins formed VLPs of 40 nm in size and also retained their antigenicity, but the Btag antigenicity appeared weak at this fusion site.

Amino Acid Sequence↗
PubMed1999

Regulation of glycogen utilization in ischemic hearts after 24 hours of fasting.

INTRODUCTION: Fasting protects the ischemic heart from injury and infarction. Previous studies have shown that hearts from fasted animals have greater glycogen utilization and a lower cytosolic redox state (NADH/NAD+) during global ischemia. While the mechanisms of increased glycogen utilization in fasted animals have not been elucidated, animals that hibernate or are tolerant of anoxia are known to increase the tissue content of the active form of glycogen phosphorylase, phosphorylase a. Therefore, this study was designed to (a) determine whether hearts from fasted animals have increased activity of glycogen phosphorylase during ischemia and (b) define those mechanisms responsible for this increase. METHODS: Hearts isolated from either fed or fasted (24 h) rats were perfused and freeze-clamped at baseline, and after 1 and 10 min of ischemia, for measurement of phosphorylase activity, phosphorylase kinase activity, and glucose-6-phosphate concentrations. RESULTS: Fasting increased the phosphorylase a/b ratio under both baseline and ischemic conditions. This increase was not accompanied by an increase in the activity of phosphorylase kinase, either with maximal [Ca2+] or under physiologic [Ca2+]. Glucose 6-phosphate concentrations were lower in hearts from fasted animals under baseline, but not ischemic, conditions. CONCLUSIONS: Fasting enhances glycogen utilization during ischemia by increasing the active form of glycogen phosphorylase. This increase is not due to a change in phosphorylation by phosphorylase kinase nor end-product inhibition by G-6P. While the precise mechanism of increased glycogen phosphorylase activity in fasted animals is not clear, one likely explanation may be the lower cytosolic redox state demonstrated in the myocardium of fasted animals.

Analysis of Variance↗
PubMed1999

Outcome of liver transplantation in hepatitis C virus-infected patients who received hepatitis C virus-infected grafts.

BACKGROUND & AIMS: The present organ shortage has brought into question the suitability of hepatitis C virus (HCV)-positive grafts. This study reviewed the outcome of such transplantations in our institution. METHODS: Twenty-three HCV-positive patients who underwent orthotopic liver transplantation (OLT) for end-stage liver disease with HCV-positive grafts in 1992-1995 were studied. Only patients who survived more than 30 days were included in the analysis. Control group included 169 patients who underwent transplantation for HCV-related cirrhosis and received HCV-negative organs. RESULTS: Patients who received HCV-infected organs had a cumulative survival rate of 89% and 72% at 1 and 5 years, respectively, vs. 88% and 73% for the control group (NS). There was no difference in graft survival, incidence of cirrhosis, mean hepatitis activity index score, fibrosis, or mean activity of serum transaminases. There was a trend toward lower incidence of recurrent hepatitis C in the study group compared with control (21% vs. 23% at 1 year and 47% vs. 64% at 5 years; NS). Patients in whom the donor strain became predominant after transplantation had significantly longer disease-free survival than patients who retained their own HCV strain (P < 0.003). CONCLUSIONS: HCV-infected livers transplanted into HCV-infected recipients do not appear to convey a worse outcome in the initial years after OLT than HCV-negative grafts.

Adult↗
PubMed1999

Quantification of recombinant core-like particles of bluetongue virus using immunosorbent electron microscopy.

Immunosorbent electron microscopy was used to quantify recombinant baculovirus-generated bluetongue virus (BTV) core-like particles (CLP) in either purified preparations or lysates of recombinant baculovirus-infected cells. The capture antibody was an anti-BTV VP7 monoclonal antibody. The CLP concentration in purified preparations was determined to be 6.6 x 10(15) particles/l. CLP concentration in lysates of recombinant baculovirus-infected cells was determined at various times post-infection and shown to reach a value of 3 x 10(15) particles/l of culture medium at 96 h post-infection. The results indicated that immunosorbent electron microscopy, aided by an improved particle counting method, is a simple, rapid and accurate technique for the quantification of virus and virus-like particles produced in large scale in vitro systems.

Animals↗
PubMed1999

Fasting limits norepinephrine release with myocardial ischemia and reperfusion.

INTRODUCTION: Fasting for 24 hours improves functional recovery and reduces injury due to global ischemia and reperfusion. Since fasting affects catecholamine kinetics, and norepinephrine (NE) release has been implicated as a mediator of dysrhythmias and injury with myocardial ischemia, we hypothesized that fasting would limit NE release following ischemia and reperfusion as a mechanism of its beneficial effects. METHODS: Hearts were isolated and perfused from rats either fed normally or fasted for 24 hours. Following baseline perfusion, hearts were subjected to 20 minutes of ischemia followed by reperfusion. Hemodynamics (developed and end-diastolic pressure) and dysrhythmias were monitored, and creatine kinase release on reperfusion was measured as a marker of cellular injury. NE tissue content was assessed prior to ischemia and NE release was measured upon reperfusion with and without blockade of the uptake1 carrier using desipramine. RESULTS: The release of NE was reduced by fasting (0.52+/-0.14 vs. 1.47+/-0.15 nmol/gdw, p<0.001) associated with a reduction in dysrhythmias, lower creatine kinase release, and lower end-diastolic pressure on reperfusion. However, fasting did not reduce NE tissue stores prior to ischemia. Desipramine also reduced NE release on reperfusion and limited the frequency of dysrhythmias, but did not alter ischemic injury. CONCLUSIONS: Fasting limits NE release after ischemia and reperfusion, an effect not due to lower NE stores. Lower NE release, either by fasting or blockade of the uptake1, carrier, significantly reduces the frequency of dysrhythmias. However, the amount of NE release, per se, does not alter ischemic injury, suggesting that the infarct limiting effect of fasting is not mediated by lower NE release.

Adrenergic Uptake Inhibitors↗
PubMed1999

Epicutaneous administration of hapten through patch application augments TH2 responses which can downregulate the elicitation of murine contact hypersensitivity.

BACKGROUND AND OBJECTIVE: Allergic contact dermatitis and its animal model, contact hypersensitivity (CHS), have long been documented as type 1 T-cell-predominant immune responses. Although type 1/type 2 T-cell deviation has been repeatedly demonstrated to play an important role in many human diseases and their animal models, the potential of tilting type 1/type 2 T-cell differentiation of CHS by modulating the manner of administration and dosage of hapten remains unexplored. This study examined the effect of these two factors on type 1/type 2 balance of CHS. METHODS: ELISA methods for detection of isotypes of hapten-specific antibodies and cytokine profiles of in vitro reactivation culture as well as ear-swelling assay were used to indicate type 1 or type 2 T-cell immune responses. RESULTS: In this paper, it was demonstrated that dosage of hapten has no effect on the type 1/ type 2 T-cell balance of CHS, whereas epicutaneous administration of hapten through patch application could tilt the type 1/type 2 balance to decrease type 1 and to augment type 2 T-cell responses. Patch application-induced modulation is still effective in ever-sensitized mice and the augmented type 2 T-cell responses are persistent and increase progressively in strength after repeated immunizations. Moreover, it was demonstrated that the augmented type 2 T-cell response can downregulate the elicitation of CHS. The major mediating cells of the enhanced type 2 T-cell responses were determined to be CD4+ T cells (TH2 cells). CONCLUSIONS: These data show that epicutaneous administration of hapten through patch application augments TH2 response which can downregulate the elicitation of murine CHS. This exploration may contribute to the understanding of regulatory mechanisms involved in contact allergy.

Adoptive Transfer↗
PubMed1999

Differences between hepatitis C virus 5' untranslated region quasispecies in serum and liver.

It is unclear whether the sequence populations of hepatitis C virus (HCV) quasispecies in the liver and in serum are different, as a variety of studies on this subject provide conflicting results. In the current study, the populations of HCV 5' untranslated region (5' UTR) sequences in paired serum and liver samples from six patients with chronic hepatitis were analysed. Liver-derived, negative-strand viral RNA was amplified with a highly strand-specific Tth-based assay, and extensive measures, including accounting for template copy number, were undertaken to lower the risk of sporadic artefactual polymorphism. Amplified sequences were compared by single-strand conformation polymorphism analysis and by direct sequencing of identified differences. In four patients, liver samples were found to contain variants within the quasispecies which were not found in serum or negative-strand viral RNA, while in the remaining two patients, low virus titre prevented a reliable quasispecies analysis. These results suggest the presence in the same individual of HCV variants differing in the 5' UTR and possibly replicating with different kinetics.

5' Untranslated Regions↗
PubMed1999

A novel Bacillus subtilis gene, antE, temporally regulated and convergent to and overlapping dnaE.

A Bacillus subtilis promoter, Px, that functions in a convergent manner with the sigA operon promoter P3 has been found in the sigA operon. Promoter Px is turned on at the same time as promoter P3 during early sporulation. The transcript from promoter Px codes for a small protein with partial homology to the OmpR protein from Escherichia coli and also carries an untranslated sequence at its 3' end that is complementary to the 5' end of the P3 transcript, which codes for the ribosome binding site of dnaE. The gene controlled by Px has been called antE. The expression of antE does not require sigmaB, sigmaE, or sigmaH. Px was transcribed in vitro by the sigmaA holoenzyme and is the seventh promoter to be recognized in the sigmaA operon. A possible role for the antE gene during early sporulation is proposed.

Amino Acid Sequence↗
PubMed1999

Traumatic ossicular chain discontinuity--report of two cases.

In addition to hemotympanum and traumatic eardrum perforation, traumatic ossicular chain discontinuity should also be considered in the differential diagnosis of conductive hearing impairment resulting from head injury. The most common form of these ossicular chain lesions following head injury is incudostapedial joint (I-S joint) separation. We successfully managed two patients with I-S joint separation resulting from head injury through exploratory tympanotomy with ossiculoplasty within the recent 2 years. Both were young females who had sustained head injury resulting from traffic accident with the sequelae of persistent hearing impairment. They both gained significant hearing improvement postoperatively.

Adult↗
PubMed1998

The attachment protein of Hendra virus has high structural similarity but limited primary sequence homology compared with viruses in the genus Paramyxovirus.

The complete nucleotide sequence of the attachment protein gene of Hendra virus, a new member of the subfamily Paramyxovirinae, has been determined from cDNA clones derived from viral genomic RNA. The deduced mRNA is 2565 nucleotides long with one open reading frame encoding a protein of 604 amino acids, which is similar in size to the attachment protein of the members of the subfamily. However, the mRNA transcript is >600 nucleotides longer than others in the subfamily due to the presence of long untranslated regions at both the 5' and 3' ends. The protein is designated G because it lacks both hemagglutination and neuraminidase activities. It contains a hydrophobic transmembrane domain close to the N terminus, eight potential N-linked glycosylation sites, and 18 cysteine residues. Although the HeV G protein had low sequence homology with Paramyxovirinae members, the predicted folding pattern of its extracellular globular head was very similar to that of members of the genus Paramyxovirus, with the location of seven potential pairs of sulfide bonds absolutely conserved. On the other hand, among the seven residues known to be critical for neuraminidase activity, only one was conserved in the Hendra virus G protein compared with at least six in HN proteins of paramyxoviruses and rubulaviruses and four in H proteins of morbilliviruses. The biological significance of this finding is discussed.

Amino Acid Sequence↗
PubMed1998

Detection of hepatitis C virus replication in peripheral blood mononuclear cells after orthotopic liver transplantation.

BACKGROUND: The presence of hepatitis C virus (HCV) replication in peripheral blood mononuclear cells (PBMCs) remains controversial. We determined the presence of the negative HCV RNA strand in PBMCs from a group of HCV-positive patients before and after liver transplantation. METHODS: Nine patients receiving orthotopic liver transplantation for end-stage HCV-related liver disease were studied. PBMCs were collected on the day of transplantation and 1 month later. The negative HCV RNA strand was detected by highly strand-specific Tth-based reverse transcriptase polymerase chain reaction. RESULTS: All nine patients were positive for the presence of the HCV RNA-positive strand in serum and PBMCs both before and after transplantation. The presence of the negative HCV RNA strand was documented in three PBMC samples after transplantation but in none of the samples collected before transplantation. CONCLUSION: Our results suggest that under circumstances of impaired immunity associated with pharmacological immunosuppression, HCV may be lymphotropic in vivo.

Hepacivirus↗
PubMed1998

Hepatitis C virus quasispecies in patients infected with HIV-1: correlation with extrahepatic viral replication.

Hepatitis C virus (HCV) sequences recovered from serum, peripheral blood mononuclear cells (PBMCs), and various tissues from human immunodeficiency virus type 1 (HIV-1) positive patients were compared by single strand conformational polymorphism (SSCP) and sequencing. In five patients, paired serum and PBMCs samples were analyzed while in two other patients multiple autopsy tissues were studied. Sequences amplified from the NS5 and E2 regions were consistently identical in the same patient; however, three PBMCs samples and three different tissue samples (pancreas and adrenal gland in one patient and lymph node in the other patient) contained 5' untranslated region (5'UTR) sequences that were different from circulating sequences. The presence of 5' UTR sequences differing from circulating sequences correlated with the presence of HCV RNA negative strand, as the latter was detected by a Tth-based strand-specific assay in all but one of these samples. These two independent lines of evidence: viral sequence differences and the presence of RNA negative strand in the same tissues strongly argue for the genuine presence of extrahepatic HCV replication, at least in the setting of HIV-1 infection.

Base Sequence↗
PubMed1998

Nitro-polycyclic aromatic hydrocarbon contents of fumes from heated cooking oils and prevention of mutagenicity by catechin.

According to earlier studies, fumes from cooking oils were found to be mutagenic and several polycyclic aromatic hydrocarbons (PAHs), (benzo(a)pyrene (B(a)P), benz(a)antracene (B(a)A), and dibenz(a,h)anthracene (DB(ah)A)) were identified. Fume samples from three different commercial cooking oils frequently used in Taiwan were collected and nitro-polycyclic aromatic hydrocarbons (NPAHs) were extracted from the samples and identified by HPLC chromatography. Extracts from three cooking oil fumes contained 1-nitropyrene (1-NP) and 1,3-dinitropyrene (1,3-DNP). Concentrations of 1-NP and 1,3-DNP were 1.1 +/- 0.1 and 0.9 +/- 0.1 micrograms/m3 in fumes from lard oil, 2.9 +/- 0.3 and 3.4 +/- 0.2 micrograms/m3 in soybean oil, 1.5 +/- 0.1 and 0.4 +/- 0.1 micrograms/m3 in peanut oil, respectively. The preventive effect of three natural antioxidants (gamma-tocopherol (TOC), lecithin (LEC), and catechin (CAT)) for the reduction of mutagenicity and amounts of PAHs and NPAHs of fumes from cooking oils were evaluated. Mutagenicity of cooking oil fumes occurred, and the concentration of B(a)P were significantly reduced (p < 0.05), by adding CAT into cooking oils before heating. B(a)A, DB(ah)A, and two NPAHs were not detected when the concentration of CAT was 500 ppm in all three cooking oil fumes. These results indicate that fumes of cooking oils contained PAHs and NPAHs that may be a risk factor for lung cancer among cooks and the carcinogens could be reduced by adding the natural antioxidant, catechin.

Antimutagenic Agents↗
PubMed1998

Metabolism of the lipid peroxidation product, 4-hydroxy-trans-2-nonenal, in isolated perfused rat heart.

The metabolism of 4-hydroxy-trans-2-nonenal (HNE), an alpha, beta-unsaturated aldehyde generated during lipid peroxidation, was studied in isolated perfused rat hearts. High performance liquid chromatography separation of radioactive metabolites recovered from [3H]HNE-treated hearts revealed four major peaks. Based on the retention times of synthesized standards, peak I, which accounted for 20% radioactivity administered to the heart, was identified to be due to glutathione conjugates of HNE. Peaks II and III, containing 2 and 37% radioactivity, were assigned to 1, 4-dihydroxy-2-nonene (DHN) and 4-hydroxy-2-nonenoic acid, respectively. Peak IV was due to unmetabolized HNE. The electrospray ionization mass spectrum of peak I revealed two prominent metabolites with m/z values corresponding to [M + H]+ of HNE and DHN conjugates with glutathione. The presence of 4-hydroxy-2-nonenoic acid in peak III was substantiated using gas chromatography-chemical ionization mass spectroscopy. When exposed to sorbinil, an inhibitor of aldose reductase, no GS-DHN was recovered in the coronary effluent, and treatment with cyanamide, an inhibitor of aldehyde dehydrogenase, attenuated 4-hydroxy-2-nonenoic acid formation. These results show that the major metabolic transformations of HNE in rat heart involve conjugation with glutathione and oxidation to 4-hydroxy-2-nonenoic acid. Further metabolism of the GS-HNE conjugate involves aldose reductase-mediated reduction, a reaction catalyzed in vitro by homogenous cardiac aldose reductase.

Aldehydes↗