Search PubMed⌕ Search

Biomedical subjects

L F Wang

Publications and source records attributed to L F Wang.

At least 37 records · Page 2Linked to original sources
PubMed2001

Extracellular domain of YWK-II, a human sperm transmembrane protein, interacts with rat Müllerian-inhibiting substance.

The YWK-II protein in human spermatozoa is structurally related to the betaA4-amyloid precursor protein of Alzheimer disease and has high similarity with amyloid precusor homologues. Antibodies to the YWK-II protein agglutinate human spermatozoa and may be a potential cause of infertility. In the present study, a yeast two-hybrid system (MATCHMAKER Two-Hybrid System 2; Clontech, Palo Alto, CA) was used to screen a rat ovary cDNA library for potential ligands capable of interacting with the YWK-II component. Müllerian-inhibiting substance was found to interact with the extracellular domain of YWK-II protein. The interaction was confirmed by a binding experiment in vitro and surface plasmon resonance assays. The recombinant Müllerian-inhibiting substance can significantly increase the viability and longevity of human spermatozoa after 5 and 22 h of incubation, presumably through binding the YWK-II component on the sperm membrane. The results of this study indicate that the YWK-II sperm membrane protein may function as a receptor for Müllerian-inhibiting substance.

Amino Acid Sequence↗
PubMed2001

Emerging viral diseases of Southeast Asia and the Western Pacific.

Over the past 6 years, a number of zoonotic and vectorborne viral diseases have emerged in Southeast Asia and the Western Pacific. Vectorborne disease agents discussed in this article include Japanese encephalitis, Barmah Forest, Ross River, and Chikungunya viruses. However, most emerging viruses have been zoonotic, with fruit bats, including flying fox species as the probable wildlife hosts, and these will be discussed as well. The first of these disease agents to emerge was Hendra virus, formerly called equine morbillivirus. This was followed by outbreaks caused by a rabies-related virus, Australian bat lyssavirus, and a virus associated with porcine stillbirths and malformations, Menangle virus. Nipah virus caused an outbreak of fatal pneumonia in pigs and encephalitis in humans in the Malay Peninsula. Most recently, Tioman virus has been isolated from flying foxes, but it has not yet been associated with animal or human disease. Of nonzoonotic viruses, the most important regionally have been enterovirus 71 and HIV.

Animals↗
PubMed2001

Inhibitory effect and mechanism of acarbose combined with gymnemic acid on maltose absorption in rat intestine.

AIM: To compare the combinative and individual effect of acarbose and gymnemic acid (GA) on maltose absorption and hydrolysis in small intestine to determine whether nutrient control in diabetic care can be improved by combination of them. METHODS: The absorption and hydrolysis of maltose were studied by cyclic perfusion of intestinal loops in situ and motility of the intestine was recorded with the intestinal ring in vitro using Wistar rats. RESULTS: The total inhibitory rate of maltose absorption was improved by the combination of GA (0.1g/L-1.0 g/L) and acarbose (0.1 mmol/L-2.0 mmol/L) throughout their effective duration (P <0.05, U test of Mann-Whitney), although the improvement only could be seen at a low dosage during the first hour. With the combination, inhibitory duration of acarbose on maltose absorption was prolonged to 3h and the inhibitory effect onset of GA was fastened to 15 min. GA suppressed the intestinal mobility with a good correlation (r = 0.98) to the inhibitory effect of GA on maltose absorption and the inhibitory effect of 2 mmol/L (high dose) acarbose on maltose hydrolysis was dual modulated by 1g/L GA in vivo indicating that the combined effects involved the functional alteration of intestinal barriers. CONCLUSION: There are augmented effects of acarbose and GA,which involve pre-cellular and paracellular barriers. Diabetic care can be improved by employing the combination.

Acarbose↗
PubMed2001

Experimental infections of pigs with Japanese encephalitis virus and closely related Australian flaviviruses.

The flavivirus Japanese encephalitis (JE) virus has recently emerged in the Australasian region. To investigate the involvement of infections with related enzootic flaviviruses, namely Murray Valley encephalitis (MVE) virus and Kunjin (KUN) virus, on immunity of pigs to JE virus and to provide a basis for interpretation of serologic data, experimental infections were conducted with combinations of these viruses. Antibody responses to primary and secondary infections were evaluated using panels of monoclonal antibody-based blocking enzyme-linked immunosorbent assays and microtiter serum neutralization tests (mSNTs). Identification of the primary infecting virus was possible only using the mSNTs. Following challenge, unequivocal diagnosis was impossible due to variation in immune responses between animals and broadened and/or anamnestic responses. Viremia for JE virus was readily detected in pigs following primary infection, but was not detected following prior exposure to MVE or KUN viruses. Boosted levels of existing cross-neutralizing antibodies to JE virus suggested a role for this response in suppressing JE viremia.

Animals↗
PubMed2001

[Experimental pharmacodynamic study on the anti-convulsion effect of shenpu decoction].

OBJECTIVE: To observe the anti-convulsion effect of Shenpu Decoction (SPD). METHODS: Experiments were conducted in three acute convulsion models (cardiazol seizure, strychnine convulsion and maximal electrical shock). Models were divided into the control group (A, treated by normal saline), the high, middle and low dose SPD groups (B, C and D, treated with SPD 9 g/kg, 6 g/kg and 4 g/kg respectively), and the nitrazepam treated group (E). The anti-convulsion effect of SPD was evaluated by 50% convulsion dose (CD50) detected in each group. RESULTS: In cardiazol convulsion model, the CD50 detected in group A-E were 63.3 +/- 3.4 mg/kg, 116.2 +/- 3.4 mg/kg, 105.6 +/- 3.7 mg/kg, 74.0 +/- 3.7 mg/kg and 197.2 +/- 3.3 mg/kg respectively, while they were 0.71 +/- 0.04 mg/kg, 1.21 +/- 0.04 mg/kg, 1.19 +/- 0.04 mg/kg, 0.94 +/- 0.04 mg/kg and 1.16 +/- 0.04 mg/kg respectively in the strychnine convulsion model, and 67.1 +/- 2.6 V, > 140 V, 109.4 +/- 3.5 V, 84.4 +/- 3.1 V and 128.4 +/- 3.9 V in the maximal electrical shock model respectively. CONCLUSION: SPD has a good anticonvulsion effect.

Animals↗
PubMed2001

[Determination of the binding site of testis-specific nucleoporin BS-63 to transportin (karopherin beta 2) and the proof of their combination in vitro].

OBJECTIVE: To locate the binding site of testis-specific nucleoporin BS-63 to transportin (karopherin beta 2) and confirm their combination in vitro. METHODS: Constructed different fragments of C terminal BS-63 was employed to localize the binding site of the testis-specific nucleoporin BS-63 to transportin by yeast two-hybrid system technique pull-down test was used to identify the interaction between the purified expressed fragments of BS-63 0.6 K and transportin in vitro. RESULTS: BS-63 binding site to transportin was shortened from 1.6 kb to 0.6 kb which included a Ran binding domain (RanBD). SDS-PAGE and Western blot tests confirmed the recombinant purified protein coded by 0.6 kb fragment of BS-63 cDNA could interact with transportin in vitro. CONCLUSIONS: In germ cells, the function of the testis-specific nucleoporin BS-63 localized at cytoplasmic side of NPC importing cargoes into nuclear may be accomplished by transportin cooperation.

Binding Sites↗
PubMed2000

Synthesis, characterization, and antibacterial activity of novel Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) complexes with vitamin K3-thiosemicarbazone.

Vitamin K3-thiosemicarbazone (C12H11N3NaO4S2 x 5H2O, abbreviated as VT), a new Schiff base derivative, has been synthesized. Its crystal structure, determined by X-ray diffraction, is triclinic, space group P1. We have also prepared five novel complexes of VT with transition metals: [M(VT)(2)2H2O] x nH2O, (n = 1 and 2 for M = Cu(II) and Zn(II), respectively) and [M'(HVT)2Cl2] x mH2O, (m = 4, 5, and 7 for M' = Co(II), Mn(II), and Ni(II), respectively). These compounds were characterized by IR and UV-Vis spectroscopy, molar conductivity, thermal analyses, complexometric titration, and elemental analysis. In all the complexes, the VT ligand coordinates through sulfur and oxygen atoms, and the geometry around metal atom is best described as octahedral. In vitro tests of antibacterial activity showed that VT and its complexes with Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) all had strong inhibitory actions against G(+) Staphylococcus aureus, G(+) Hay bacillus, and G(-) Escherichia coli.

Anti-Bacterial Agents↗
PubMed2000

The presence of cross-reactive antibodies to rabbit haemorrhagic disease virus in Australian wild rabbits prior to the escape of virus from quarantine.

Sera collected from Australian wild rabbits prior to the escape of rabbit haemorrhagic disease virus (RHDV) from Wardang Island were examined for RHDV antibodies using purified recombinant capsid protein VP60 expressed from baculovirus. A VP60-based indirect ELISA showed that 196 of 392 wild rabbit sera reacted (OD(450) >0.15) with VP60. Twenty sera (OD(450) ranging from 0.15-2.47), randomly chosen from the 196 positive sera, recognized the 64 kDa VP60 in Western blot analysis, indicating that the reactivity detected in ELISA is indeed specific to the VP60 antigen. In a separate study, sera of 23 rabbits from an RHD-free area after the escape of RHDV were tested by ELISA and 21 of the 23 rabbits were found to be positive. When these rabbits were challenged with a lethal dose of RHDV, 11 out of the 23 rabbits survived. The presence of RHDV-protective antibodies in some of these rabbits suggested that they had been exposed to a pre-existing non-virulent rabbit calicivirus closely related to RHDV. These results highlight the need to study the prevalence of, and to characterize, this viral agent in order to effectively control rabbit populations in Australia and New Zealand.

Animals↗
PubMed2000

Effects of heat processing and storage on flavanols and sensory qualities of green tea beverage.

This research was conducted to understand the effects of heat processing and storage on flavanols and sensory qualities of green tea extract. Fresh tea leaves were processed into steamed and roasted green teas by commercial methods and then extracted with hot water (80 degrees C) at 1:160 ratio (tea leaves/water by weight). Green tea extracts were heat processed at 121 degrees C for 1 min and then stored at 50 degrees C to accelerate chemical reactions. Changes in flavanol composition and sensory qualities of green tea extracts during processing and storage were measured. Eight major flavanols (catechin, epicatechin, gallocatechin, epigallocatechin, epicatechin gallate, catechin gallate, epigallocatechin gallate, and gallocatechin gallate) were identified in the processed tea extract. Among them, epigallocatechin gallate and epigallocatechin appeared to play the key role in the changes of sensory qualities of processed green tea beverage. The steamed tea leaves produced a more desirable quality of processed green tea beverage than the roasted ones.

Flavonoids↗
PubMed2000

Comparison of serum specific IgE antibodies to staphylococcal enterotoxins between atopic children with and without atopic dermatitis.

BACKGROUND: The skin of patients with atopic dermatitis (AD) exhibits a striking susceptibility to colonization and infection by Staphylococcus aureus. The exotoxins secreted by S. aureus can act as superantigens and classic allergens, inducing the production of functionally relevant specific IgE antibodies. The aim of this study was to compare the levels and positive rates of serum staphylococcal enterotoxin A (SEA)- and staphylococcal enterotoxin B (SEB)-specific IgE between atopic children with and without AD. METHODS: Sixty children with AD, 55 children with respiratory allergy without AD, and 24 nonatopic healthy children were studied. The levels and positive rates of serum SEA- and SEB-specific IgE were compared among three groups. The correlation between the levels or positive rates of serum SEA/SEB-specific IgE and the severity of AD or the presence of previous skin infections was studied. RESULTS: The children with AD had significantly higher levels and positive rates of serum SEA- and SEB-specific IgE than the atopic children without AD (P < 0.001) and the nonatopic children (P < 0.001). There was no significant difference in the levels and positive rates of serum SEA- and SEB-specific IgE between the atopic children without AD and the nonatopic children. With or without adjustment for the potential confounding effect of total serum IgE levels, the levels and positive rates of serum SEA- and SEB-specific IgE were significantly correlated with severity of AD (P <0.005), but they were not significantly different between AD children with and without previous skin infections. CONCLUSIONS: SEA and SEB may contribute to chronic inflammation and exacerbation of AD through the IgE-mediated immune response.

Adolescent↗
PubMed2000

High levels of interleukin-8, soluble CD4 and soluble CD8 in bullous pemphigoid blister fluid. The relationship between local cytokine production and lesional T-cell activities.

BACKGROUND: Bullous pemphigoid (BP) is an inflammatory subepidermal blistering disease associated with autoantibodies that recognize hemidesmosomal proteins. In addition to autoantibodies, the cell-mediated immune reaction is considered to play an important part in blister formation. Objectives To investigate some T-cell activation markers and inflammatory cytokines in the blister fluid and sera of patients with BP. METHODS: We measured soluble CD4 (sCD4) and soluble CD8 (sCD8), which have been, respectively, associated with CD4 and CD8 T-cell activation. Enzyme-linked immunosorbent assays were also used to quantify the production of the leucocyte chemoattractant interleukin (IL) -8 and of the cytokines IL-1alpha, IL-1beta, IL-6, IL-10 and tumour necrosis factor-alpha in the blister fluid and sera of 11 patients with BP. RESULTS: The mean +/- SD level of sCD4 in patients' blisters (42.4 +/- 25.0 units mL-1) was significantly elevated (P < 0.005) compared with that in their sera (11.2 +/- 8.9) and that in the suction blisters of 10 healthy people (11.4 +/- 5.4; P < 0.005). Mean +/- SD IL-8 concentrations in BP blisters (4683.6 +/- 3878.1 pg mL-1) were much higher than those in their sera (17.1 +/- 18.9; P < 0.001), and were very significantly elevated (P < 0.005) in comparison with those in suction blisters of healthy persons (512 +/- 292). sCD4 levels in BP blisters were inversely related to IL-10 levels (P = 0. 03, r2 = 0.85), IL-8 levels were positively related to sCD8 levels (P = 0.01, r2 = 0.54), and IL-1beta levels were positively related to sCD8 concentrations (P < 0.005, r2 = 0.65). CONCLUSIONS: The correlations suggest that there is a delicately orchestrated network of cytokines and cell-mediated immunity operating in BP blisters.

Aged↗
PubMed2000

Uneven distribution of hepatitis C virus quasispecies in tissues from subjects with end-stage liver disease: confounding effect of viral adsorption and mounting evidence for the presence of low-level extrahepatic replication.

We have found differences among the populations of hepatitis C virus sequences in serum, peripheral blood mononuclear cells (PBMCs), and various tissues in patients with chronic hepatitis C. These results are compatible with the existence of independent viral compartments in the infected host. Our results also suggest that PBMCs, and probably various tissues, can selectively adsorb viral subpopulations differing in the E2 region.

5' Untranslated Regions↗
PubMed2000

The exceptionally large genome of Hendra virus: support for creation of a new genus within the family Paramyxoviridae.

An outbreak of acute respiratory disease in Hendra, a suburb of Brisbane, Australia, in September 1994 resulted in the deaths of 14 racing horses and a horse trainer. The causative agent was a new member of the family Paramyxoviridae. The virus was originally called Equine morbillivirus but was renamed Hendra virus (HeV) when molecular characterization highlighted differences between it and members of the genus Morbillivirus. Less than 5 years later, the closely related Nipah virus (NiV) emerged in Malaysia, spread rapidly through the pig population, and caused the deaths of over 100 people. We report the characterization of the HeV L gene and protein, the genome termini, and gene boundary sequences, thus completing the HeV genome sequence. In the highly conserved region of the L protein, the HeV sequence GDNE differs from the GDNQ found in almost all other nonsegmented negative-strand (NNS) RNA viruses. HeV has an absolutely conserved intergenic trinucleotide sequence, 3'-GAA-5', and highly conserved transcription initiation and termination sequences similar to those of respiroviruses and morbilliviruses. The large genome size (18,234 nucleotides), the unique complementary genome terminal sequences of HeV, and the limited homology with other members of the Paramyxoviridae suggest that HeV, together with NiV, should be classified in a new genus in this family. The large genome of HeV also fills a gap in the spectrum of genome sizes observed with NNS RNA virus genomes. As such, it provides a further piece in the puzzle of NNS RNA virus evolution.

Amino Acid Sequence↗
PubMed2000

Niacin protects the isolated heart from ischemia-reperfusion injury.

Nicotinic acid (niacin) has been shown to decrease myocyte injury. Because interventions that lower the cytosolic NADH/NAD(+) ratio improve glycolysis and limit infarct size, we hypothesized that 1) niacin, as a precursor of NAD(+), would lower the NADH/NAD(+) ratio, increase glycolysis, and limit ischemic injury and 2) these cardioprotective benefits of niacin would be limited in conditions that block lactate removal. Isolated rat hearts were perfused without (Ctl) or with 1 microM niacin (Nia) and subjected to 30 min of low-flow ischemia (10% of baseline flow, LF) and reperfusion. To examine the effects of limiting lactate efflux, experiments were performed with 1) Ctl and Nia groups subjected to zero-flow ischemia and 2) the Nia group treated with the lactate-H(+) cotransport inhibitor alpha-cyano-4-hydroxycinnamate under LF conditions. Measured variables included ATP, pH, cardiac function, tissue lactate-to-pyruvate ratio (reflecting NADH/NAD(+)), lactate efflux rate, and creatine kinase release. The lactate-to-pyruvate ratio was reduced by more than twofold in Nia-LF hearts during baseline and ischemic conditions (P < 0.001 and P < 0.01, respectively), with concurrent lower creatine kinase release than Ctl hearts (P < 0.05). Nia-LF hearts had significantly greater lactate release during ischemia (P < 0.05 vs. Ctl hearts) as well as higher functional recovery and a relative preservation of high-energy phosphates. Inhibiting lactate efflux with alpha-cyano-4-hydroxycinnamate and blocking lactate washout with zero flow negated some of the beneficial effects of niacin. During LF, niacin lowered the cytosolic redox state and increased lactate efflux, consistent with redox regulation of glycolysis. Niacin significantly improved functional and metabolic parameters under these conditions, providing additional rationale for use of niacin as a therapeutic agent in patients with ischemic heart disease.

Animals↗
PubMed2000

Hepatitis C epitopes from phage-displayed cDNA libraries and improved diagnosis with a chimeric antigen.

A novel method for cloning DNase I fragments into bacteriophage display vector fUSE2 was used to create libraries expressing hepatitis C virus (HCV) protein fragments on the phage surface. Selection by panning with a mixture of sera from five HCV-seropositive individuals enabled identification of antigenic determinants in NS3 (amino acids 1,383-1,415), NS4 (amino acids 1, 930-1,938), and NS5 (amino acids 2,088-2,104). The NS3 result is the most accurate location to date of a major conformational determinant that cannot be mimicked by short peptides. Any expressed sequence from the phage library can be excised with Bgl II and cloned directly into the Bgl II site of an appropriate plasmid for bacterial expression. This enables production of chimeric proteins containing multiple antigenic determinants, illustrated by co-expression of the NS4P (amino acids 1,930-1,938) epitope with an NS4N fragment (amino acids 1,644-1,812) containing at least three linear HCV epitopes. When used to screen 35 individual HCV-positive sera by enzyme-linked immunosorbent assay (ELISA), the chimeric antigen detected eight more positives than NS4N alone and gave increased immunoreactivity with others. This approach of identifying antigenic regions by phage display and then co-expressing them as chimeric proteins may be generally applicable to the production of improved diagnostic antigens and recombinant vaccines.

Amino Acid Sequence↗
PubMed1999

Analysis of hepatitis G virus/GB virus C quasispecies and replication sites in human subjects.

Although the hepatitis G virus is unlikely to be a primary hepatotropic virus, its replication sites remain unclear. Using highly strand-specific Tth-based reverse transcriptase PCR we searched for the presence of the viral RNA negative strand in various autopsy tissues in two patients who died of end-stage liver disease. In addition, amplified viral sequences were compared in the 5' untranslated and the putative capsid regions by the single-strand conformation polymorphism (SSCP). Negative strand HGV RNA was detected in bone marrow and spleen from both patients and in lymph node tissue from one. All amplified sequences from a given patient were identical when compared by SSCP and direct sequencing. This lack of difference in the composition of quasispecies recovered from various tissues suggests the presence of a single, common viral compartment in the infected host.

5' Untranslated Regions↗