Biomedical subjects

Y J Wang

Publications and source records attributed to Y J Wang.

At least 19 recordsLinked to original sources

PubMed1999

Long-term follow-up of hepatitis A vaccination in children.

We conducted this follow-up study to evaluate the long-term immunogenicity of an inactivated hepatitis A vaccine in children. Ninety-six children who had seroconversion to antibody to HAV (anti-HAV) after receiving a three-dose schedule of inactivated hepatitis A vaccine were enrolled into this study. Sixty months after the initial vaccination, all vaccinees who received annual follow-up still had protective levels of anti-HAV. The geometric mean titer (GMT) of anti-HAV, peaking at month 7 (4133 mIU/mL), kept declining throughout the follow-up period. The GMTs in months 12, 24, 36, 48 and 60 were 1722, 896, 896, 645 and 403 mIU/mL, respectively. Nine of the vaccinees were hepatitis B virus carriers. Their anti-HAV titers tended to be lower than those of the remaining vaccinees at all time-points, but the difference was not significant (p > 0.05). Natural booster was noted in one vaccinee during the follow-up period. In conclusion, inactivated hepatitis A vaccine is safe and immunogenic in children, the duration of protection against HAV infection is longer than five years.

Child↗

PubMed1999

Biological actions of synthetic locust ion transport peptide (ITP).

Locust Ion Transport Peptide (ITP) a member of the arthropod neuropeptide family which includes hyperglycemic, vitellogenesis-inhibiting, and moult-inhibiting hormones (CHH, VIH, MIH, respectively) was synthesized as proposed by Meredith et al. (1996) with terminal amidation of amino acid residue 72 and with 3 disulphide bridges. This is the first member of this family to be synthesized. Biological activities of synthetic ITP (synITP) were very similar to those previously reported for ITP purified from Schistocerca corpora cardiaca (ScgITP) and partially sequenced by Audsley et al. (1992a, b). Dose-response curves for both synITP and ScgITP on ileal transport of Cl- (measured as increased short-circuit current, delta Isc), were similar with a EC50 of 1-2 nM. The Isc time course and maximum delta Isc across ileal epithelia at different dosages of synITP and ScgITP had similar patterns as did changes in transepithelial open-circuit potential (Vt) and resistance (Rt), reflecting changes in salt transport which drives fluid absorption. Disulphide bridges were shown to be required for biological activity of synITP, which caused the same 4-fold increase in ileal fluid transport rate (Jv) as previously reported for ScgITP. Both synITP and ScgITP caused only partial stimulation of rectal Isc and had no significant effect on rectal Jv. These results indicate that the structure of ITP predicted earlier from cDNA is correct.

Animals↗

PubMed1998

Ligation of CD31/PECAM-1 modulates the function of lymphocytes, monocytes and neutrophils.

CD31 or platelet/endothelial cell adhesion molecule (PECAM-1) is a 130-kDa glycoprotein expressed on endothelial cells, granulocytes, a subset of lymphocytes and platelets. In this study, we examined the ability of four monoclonal antibodies (mAb) against different domains of CD31 to modulate the function of T lymphocytes, monocytes and neutrophils. Engagement of CD31 on T lymphocytes results in co-stimulation of T lymphocyte proliferation to suboptimal doses of anti-CD31 mAb. This proliferation is accompanied by secretion of numerous cytokines and chemokines, up-regulation of CD25 and an increase in cell size. Purification of T lymphocytes into CD45RO and CD45RA subsets showed that only naive CD45RA T lymphocytes are co-stimulated by anti-CD31 mAb. Further studies on neutrophils show that engagement of CD31 results in down-regulation of CD62L and up-regulation of CD11b/CD18 as well as oxidative burst, as assessed by superoxide release. In addition, ligation of CD31 on monocytes results in TNF-alpha secretion, and studies with various cell signaling inhibitors indicate that tyrosine kinases and cAMP-dependent kinases are involved in monocyte activation via CD31. Of the four mAb used in this study, only two activated human leukocytes. These mAb were PECAM-1.3 and hec7, which bind to domains 1 and 2 of CD31. We conclude that engagement of domains 1 and 2 of CD31 results in outside-in signaling in leukocytes.

Antibodies, Monoclonal↗

PubMed1998

The impact of traveling to endemic areas on the spread of hepatitis E virus infection: epidemiological and molecular analyses.

Traveling to endemic areas carries a risk of hepatitis E virus (HEV) infection, but no molecular analysis to document sources of infection is available. Eighteen (38%) of 47 patients with acute non-A, non-B, non-C hepatitis were positive for antibody to HEV (anti-HEV), and 9 (50%) of these were also positive for serum HEV RNA by polymerase chain reaction following reverse transcription. Only 1 (5%) of the 21 patients with acute hepatitis A was positive for HEV RNA. Travel to endemic areas (mostly to China; odds ratio, 22.2; 95% confidence interval, 4.7-105.8) and deeper jaundice (odds ratio, 5.2; 95% confidence interval, 1.01-27.2) were the only factors associated with HEV infection in multivariate analysis. The two HEV isolates from two patients who had traveled to China and the HEV isolate from a patient whose travel history was obscure formed a monophyletic group with the isolates from Guangzhou. The HEV isolates from our patients show a homology of 72% to 78% in nucleotide sequence with the Burma, Beijing, India, Pakistan, and Xiangjiang strains; a homology of 81% to 91% with the Guangzhou strains; and a homology of 76% with the Mexico strain. The close relationship between the Taiwan isolates and the Guangzhou strains was further supported by the short Kimura's two-parameter distances among them. In summary, HEV infection does occur in this area. Epidemiological and molecular analyses strongly indicate that most cases of HEV infection originated from travel to HEV-endemic areas.

Adult↗

PubMed1998

Ethanol induces subtype-specific up-regulation of muscarinic acetylcholine receptor mRNA in neurohybrid cell lines.

Effects of sub-chronic ethanol treatment on the mRNA levels of muscarinc acetylcholine receptor (mAChR) subtypes were studied in two neurohybrid cell lines, NG108-15 and NCB-20. The former expresses only m4-mAChRs, while the latter expresses m1- and m4-mAChRs. Exposure to 200 mM ethanol for 1 to 3 days induced a time-dependent increase in the levels of m4-mAChR mRNA in NG108-15 and NCB-20 cells. In contrast, the levels of ml-mAChR mRNA and mAChR-mediated phosphoinositide hydrolysis in NCB-20 cells were unchanged. The ethanol-induced up-regulation of m4-mAChR mRNA was associated with a parallel increase in the levels of mAChR binding sites assessed by using [3H]quinuclidinyl benzilate. The mRNA up-regulation was closely correlated with a decrease in intracellular cyclic AMP concentration and the ethanol up-regulation was blocked by 8-bromo-cyclic AMP and forskolin, suggesting that m4-mAChR mRNA is under negative regulation by cyclic AMP. Thus, neurally-related cell lines are useful models for studying molecular mechanisms underlying ethanol-induced alteration of mAChR expression and function in the nervous system.

Animals↗

PubMed1998

Stereo capture: local rematching driven by binocularly attended 3-D configuration rather than retinal images.

Previous explanations for stereo capture were mainly based on the low-level perceptual processing of binocular stereopsis which usually shows that one pair of retinal images corresponds to only one 3-D perceptual configuration. Stereo capture, however, may encounter multiple perceptual configurations due to the matching ambiguity of wallpaper elements that may not be solved merely by bottom-up processing of the retinal stimuli. The present study suggests that binocular attention plays an important role in stereo capture by way of selecting and enhancing a perceptual configuration that is often ambiguous without attention involved. Stereo capture results from wallpaper's local rematching driven by binocularly attended 3-D configuration rather than retinal images.

Attention↗

PubMed1998

Surgical treatment of Boerhaave's syndrome: when, how and why?

Ten cases of Boerhaave's syndrome have been treated in this hospital from 1983-1998. Nine patients underwent surgery resulting in complete recovery in seven cases and two postoperative deaths. One was treated with a satisfactory outcome. Vomiting was considered to be the determinative factor for the illness in eight cases. The relationship between the rupture of the esophagus and vomiting and the mechanism of its occurrence based on anatomy and pathophysiology is discussed. It is believed that the most beneficial time to perform surgery is based on the general condition of the patient. The surgical procedure should consist of closure of the lacerated esophagus, a complete clearance of the fibrinous coating on the surface of the pleura, mobilization of a pedicled omentum pad and a gastrostomy. The chest should be entered from the side where the esophagus was lacerated or the X-ray examination showed hydrothorax or hydropneumothorax. The most important factor to guarantee a successful outcome for surgery is a complete clear off of the empyema and early expansion of the lung in addition to effective nutritional support.

Adult↗

PubMed1998

Two novel antifibrotics, HOE 077 and Safironil, modulate stellate cell activation in rat liver injury: differential effects in males and females.

The perisinusoidal stellate cells of the liver in an injury milieu undergo activation, acquiring a myofibroblast-like phenotype. In this state, they are the principal source of collagen and related proteins in fibrosis. The present studies evaluate the mechanism of action of two novel antifibrotic compounds, HOE 077 and Safironil, which were designed as competitive inhibitors of collagen protein synthesis. Fibrosis was induced in rats by administration of carbon tetrachloride, and activation was monitored as the level of collagen I mRNA or smooth muscle alpha-actin. Both male and female rats were studied. Stellate cell activation, rather than collagen synthesis, proved to be the target of both HOE 077 and Safironil in the intact liver. In culture, the drugs not only prevented the activation of stellate cells but also accelerated their deactivation. They were no more effective in co-cultures containing hepatocytes than in pure stellate cell cultures, indicating that metabolic conversion of HOE 077 was not required. Interestingly, the response of cells from females was greater than that of male cells, leading to the conclusion that stellate activation is sexually dimorphic. This finding may be relevant to the observation that fibrosis in chronic viral hepatitis progresses less rapidly and that hepatocellular carcinoma is less frequent in females than in males.

Animals↗

PubMed1998

[Studies on late replication bands of giant panda (Ailuropoda melanoleuca) chromosomes].

Using the cultured giant panda (Ailuropoda melanoleuca) lymphocytes as experimental material, we carried out the terminal marking on the chromosomes which were in replication by adding BrdU (a final concentration: 10 micrograms/ml) about four hours before harvesting the cells. The chromosomes marked by BrdU were proceeded by staining with acridine orange solution (0.05%), irradiated by ultraviolet and counter-stained by Giemsa, we obtained clear chromosomes replication patterns. According to the different replication bands, every chromosome's characteristics in late replication behavior could be identified. In the two X chromosomes of female individual, one X chromosome is obviously much later than the other one. Especially in the large area near centromere on the long arm of late replicating X chromosome. In the male individual, there is also a large area on the long arm of chromosome Y which replicates very late, but the end of long arm of chromosome Y replicates much earlier.

Animals↗

PubMed1998

Functional pancreatic islet cell tumors with liver metastasis: the role of cytoreductive surgery and transcatheter arterial chemoembolization: a report of five cases.

Malignant pancreatic islet tumors are slow-growing tumors. Their relatively benign behavior makes aggressive treatment worthwhile. From January, 1987, to January, 1998, five cases of malignant pancreatic islet tumors with liver metastasis were diagnosed at the Veterans General Hospital-Taipei. Of these, three were gastrinomas and the others were vasoactive intestinal peptide (VIPoma, 1 case) and insulinoma (1 case). Four patients (3 with gastrinomas and 1 with insulinoma) had undergone cytoreductive surgery when the diagnosis of metastasis was made. All five patients underwent transcatheter arterial chemoembolization (TACE). All patients had improved symptoms after cytoreductive surgery and TACE. The survival of patients who underwent combined surgery and TACE was 38 and 17 months in the two gastrinoma cases, more than eight months in one gastrinoma case and more than 20 months in the insulinoma case (these 2 patients are still alive). One VIPoma patient who underwent TACE survived for 12 months. In conclusion, treatment for metastatic pancreatic islet cell tumors require a multidisciplinary approach. Metastasis of the tumor is not a contraindication for aggressive therapy. Combined cytoreductive surgery and TACE can relieve symptoms and are of benefit for patients with pancreatic islet cell tumors with liver metastases.

Adenoma, Islet Cell↗

PubMed1997

Effects of cholecystokinin-B receptor antagonist on dopamine system in tenascin mutant mice.

The aim of this study was to investigate the effect of cholecystokinin (CCK) receptor antagonist on the abnormal behavior and dopamine (DA) transmission of tenascin (TN)-gene knockout mice. Recently, we demonstrated that TN-gene deficient mice show hyperlocomotion that is related to reduced DA transmission and tyrosine hydroxylase (TH) activities in the brain. In this report, we show that the intraperitoneal administration of a CCK-B receptor antagonist, PD135158 (0.1 mg/kg), but not a CCK-A receptor antagonist, lorglumide, inhibited hyperlocomotion. Moreover, PD135158 reversed the low levels of DA turnover rate and TH activities in the striatum of TN-gene knockout mouse brain. These results suggest that CCK-B receptor is involved in the behavior of TN-gene knockout mouse through striatal DA transmission.

3,4-Dihydroxyphenylacetic Acid↗

PubMed1997

Paradoxical behavioral response to apomorphine in tenascin-gene knockout mouse.

Tenascin is a large extracellular matrix glycoprotein which is highly expressed in the developing nervous system. To examine the role of tenascin in vivo, we have produced mice in which the tenascin-gene is inactivated. These animals did not easily habituate to unfamiliar circumstances and displayed hyperlocomotion. A dopamine receptor agonist, apomorphine, reduced this hyperlocomotion dose dependently, but this phenomenon was not due to the appearance of apomorphine-induced stereotypic behavior, suggesting that tenascin-gene mutant mice have a paradoxical behavioral response to apomorphine compared to wild-type mice.

Animals↗

PubMed1997

Induction of glutathione depletion, p53 protein accumulation and cellular transformation by tetrachlorohydroquinone, a toxic metabolite of pentachlorophenol.

Glutathione (GSH) conjugate formation with tetrachlorohydroquione (TCHQ) and the GSH content in vivo were measured by capillary zone electrophoresis. A more than 60% depletion of GSH content was found in liver tissue of mice treated with TCHQ. In addition, p53 protein accumulation and DNA fragmentation was induced by TCHQ. A two-stage model of chemical transformation of mouse embryonic fibroblasts was used to elucidate the transformation activity of TCHQ in vitro, and a 33% foci formation efficiency was found at the concentration of 5 microM. GSH depletion caused by TCHQ could abolish the protective ability of the cell against reactive oxygen species provided by GSH. When DNA was damaged, p53 protein accumulated in the nucleus and, in the case of severe damage, initiated apoptosis. TCHQ's ability to cause GSH depletion and DNA damage may play a role in the cytotoxic and genotoxic properties of its metabolic precursor, PCP.

3T3 Cells↗

PubMed1997

Tyrosine hydroxylase activity and its mRNA level in dopaminergic neurons of tenascin gene knockout mouse.

We have recently demonstrated that some tenascin (TN) gene-knockout mice display abnormal behaviors, and that these abnormal behaviors stem from a low level of dopamine transmission in the brain. In the present study, we elucidated that tyrosine hydroxylase (TH) activity in the frontal cortex, striatum, and hippocampus of TN-knockout mice which showed abnormal behavior was significantly decreased. Also, the TH mRNA level of the midbrain was decreased by 43% in these animals compared with values for wild-type mice. These results suggest that the low dopamine turnover rate in some areas of the brain of TN-knockout mice accompanied by motor defects is due, at least in part, to the reduction in TH activity caused by diminished TH mRNA expression, and that TN-knockout mice exhibit abnormal behaviors in the presence of low levels of TH-gene expression.

Animals↗

PubMed1997

Safety and immunogenicity of inactivated hepatitis A vaccine in patients with chronic liver disease.

The safety and immunogenicity of inactivated hepatitis A vaccine was evaluated in patients with chronic liver disease. Sixty hepatitis A virus antibody (anti-HAV) seronegative patients with chronic liver disease (56 chronic hepatitis B and four chronic hepatitis C) and from 17 to 47 years of age received a dose of 1440 ELISA units of the inactivated hepatitis A vaccine at month 0, and a booster at month 6. Anti-HAV seroconversion (> or = 33 mIU/mL) was 57.6% (34/59) on day 15, and reached 93.2% (55/59) 1 month after primary vaccination. At month 6, the seropositivity of anti-HAV decreased before the booster to 69.0% (40/58). All vaccinees had measurable titers of anti-HAV 1 month after booster vaccination, and were still seropositive at month 12. After initial vaccination, the geometric mean titers of anti-HAV among vaccine responders were 158, 264, 74, 1309, and 409 mIU/ml at day 15 and months 1, 6, 7, and 12. Overall, 59.7% (71/119) of the vaccine doses administered were followed by mostly minor reactions. The majority of symptoms reported were local, all of which resolved within 3 days after vaccination. No significant changes in serum liver enzyme levels were detected after vaccination. Thus, an inactivated hepatitis A vaccine was safe in patients with chronic liver disease while the immune response was inferior to that observed in healthy subjects reported in a previous study.

Adolescent↗

PubMed1997

The role of hepatitis G virus infection in patients with acute posttransfusion hepatitis in Taiwan.

BACKGROUND & AIMS: Hepatitis G virus (HGV) has been recently identified as a new transfusion-transmissible agent. This study was performed to evaluate the role of HGV infection in patients with acute posttransfusion hepatitis in Taiwan. METHODS: Sera from 63 patients with acute posttransfusion hepatitis and 61 patients with normal serum aminotransferase levels after transfusion were tested for HGV RNA by reverse-transcription polymerase chain reaction. RESULTS: Six of the 63 patients (9.5%) with acute posttransfusion hepatitis were positive for HGV RNA in pretransfusion sera; 4 were superinfected with hepatitis C virus (HCV) after transfusion and 3 developed chronic hepatitis. Seven (12.3%) of the remaining 57 patients had acute posttransfusion HGV infection; 5 were coinfected with HCV and 2 infected with HGV alone. None with acute HGV infection alone developed chronic hepatitis, whereas 4 of 5 patients (80%) with acute HGV and HCV coinfection developed chronic hepatitis. The clinical course of acute HGV and HCV coinfection was similar to that of acute HCV infection alone. Four of 61 subjects (6.6%) with normal serum aminotransferase levels after transfusion were subclinically infected with HGV. CONCLUSIONS: HGV infection accounted for 12.3% of acute posttransfusion hepatitis in Taiwan before anti-HCV screening of blood donors. The clinical course of acute posttransfusion HGV infection alone was relatively benign.

Acute Disease↗

PubMed1997

Effect of PVA-AA on dentine bonding of HEMA.

PVA-AA, an esterification product of poly(vinyl alcohol) and acryloyl chloride, was synthesized and tested for its dentine bonding ability as an additive to 2-hydroxyethyl methacrylate (HEMA). The dentine bonding strength increased significantly by increasing the concentration of PVA-AA in HEMA. The dentine tensile bonding strength attained by the mixture of 10 wt% PVA-AA in HEMA is about 38% higher than that of HEMA or Gluma bonding agent. The dentine shear bonding strength also increased by increasing the acrylate content of the PVA-AA up to about 30%. Test results of cell culturing indicate that no toxic substance is released from PVA-AA to inhibit the cell growth.

Acrylates↗

PubMed1997

MALDI-MS as a monitor of the purification and folding of synthetic eclosion hormone.

Analogues of the small protein Manduca sexta eclosion hormone (62 amino acids) were synthesized by Fmoc solid-phase methodology. Matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS) was used to analyze the products of the syntheses and this information was used to design an efficient purification scheme. MALDI-MS was used to monitor the target products through purification and it was also used to monitor folding of the purified materials. The folded EH analogues were shown to be biologically active proteins with an in vivo bioassay using pharate adult moths, Heliothis virescens.

Amino Acid Sequence↗