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Biomedical subjects

H B Wang

Publications and source records attributed to H B Wang.

At least 55 records · Page 3Linked to original sources
PubMed2000

[Design of the system for detecting impedance cardiography based on windows plantform].

In this paper is introduced systematically the design of the system for detecting impedance cardiography (ICG) based on Windows plantform. The three major ICG indexes of 30 students have been detected by the designed system in the clinical application, and conform with the results from the reference. On the other hand, compared with the system based on DOS plantform, the system has higher detection speed, and becomes more convenient, more flexible by the introduction of Mouse.

Adult↗
PubMed1999

The role of B-cells in experimental myasthenia gravis in mice.

Myasthenia gravis (MG) and experimental autoimmune myasthenia gravis (EAMG) are caused by auto-antibodies against the nicotinic acetylcholine receptor (AChR) at the postsynaptic membrane. To evaluate the extent to which the humoral immune response against AChR operates in the pathogenesis of EAMG, we immunized B-cell knockout (microMT) and wild type C57BL/6 mice with AChR in complete Freund's adjuvant. The ability of AChR-primed lymph node cells to proliferate and secrete IFN-gamma in response to AChR and its dominant peptide alpha 146-162 were intact in microMT as in wild type mice. Similar levels of mRNA for IFN-gamma, IL-4 and IL-10 in AChR-reactive lymph node cells were detected in microMT and wild type mice. However, microMT mice had no detectable anti-AChR antibodies and never developed clinical EAMG. We conclude that B-cells are critically required for the genesis of clinical EAMG, but not for AChR-specific T-cell priming.

Animals↗
PubMed1999

Regiochemical control of monolignol radical coupling: a new paradigm for lignin and lignan biosynthesis.

BACKGROUND: Although the lignins and lignans, both monolignol-derived coupling products, account for nearly 30% of the organic carbon circulating in the biosphere, the biosynthetic mechanism of their formation has been poorly understood. The prevailing view has been that lignins and lignans are produced by random free-radical polymerization and coupling, respectively. This view is challenged, mechanistically, by the recent discovery of dirigent proteins that precisely determine both the regiochemical and stereoselective outcome of monolignol radical coupling. RESULTS: To understand further the regulation and control of monolignol coupling, leading to both lignan and lignin formation, we sought to clone the first genes encoding dirigent proteins from several species. The encoding genes, described here, have no sequence homology with any other protein of known function. When expressed in a heterologous system, the recombinant protein was able to confer strict regiochemical and stereochemical control on monolignol free-radical coupling. The expression in plants of dirigent proteins and proposed dirigent protein arrays in developing xylem and in other lignified tissues indicates roles for these proteins in both lignan formation and lignification. CONCLUSIONS: The first understanding of regiochemical and stereochemical control of monolignol coupling in lignan biosynthesis has been established via the participation of a new class of dirigent proteins. Immunological studies have also implicated the involvement of potential corresponding arrays of dirigent protein sites in controlling lignin biopolymer assembly.

Amino Acid Sequence↗
PubMed1999

Biological effects of man-made mineral fibers (II)--their genetic damages examined by in vitro assay.

In order to study and compare genetic damage induced by 10 kinds of man-made mineral fibers (JFM fibers) in cells, human lung epithelial cells (A549) were exposed to JFM fibers and chrysotile for 1 h, then single-cell gel electrophoresis (SCGE) assay was used to detect DNA strand breaks, DNA-DNA interstrand crosslink and the ability of DNA to repair; The results showed that all 10 JFM fibers could induce DNA strand breaks, DNA-DNA interstrand crosslinks and inhibit the ability of DNA repair. When human embryo lung (HEL) cells were exposed to JFM fibers and chrysotile for 24 h respectively, the chromosomal aberration was analyzed and the results showed that chrysotile and most of JFM fibers at 5.0 micrograms/ml induced structural chromosomal aberration, but all of these effects were lower than that of chrysotile and were different among them, suggesting that 10 types of JFM fibers had genotoxicity with different degree in vitro, but all of them were lower than that of chrysotile.

Analysis of Variance↗
PubMed1999

Biological effects of man-made mineral fibers (I)--Reactive oxygen species production and calcium homeostasis in alveolar macrophages.

10 types of standard mineral fiber samples (JFM fibers) were tested for their cytotoxicity in alveolar macrophages (AM) in vitro experiments, in which UICC chrysotile B was used as a positive control. The cytotoxicity included the production of superoxide anion radical and hydrogen peroxide, depletion of glutathione (GSH) and increase of intracellular free calcium. The results showed that chrysotile and most of the 10 mineral fibers could increase the production of superoxide anion and hydrogen peroxide, deplete the concentration of GSH and increase the level of free intracellular Ca2+ in AM. But all the effects of JFM fibers were lower than that induced by UICC chrysotile B. Although the cytotoxicity of JFM fibers were lower than that of asbestos, these mineral fibers should be used with highly care for workers in industries.

Animals↗
PubMed1999

[Brainstem changes in death from head injury].

The cortex and brainstem changes in death from head injury were observed. There were hemorrhage, edema and neuron necrosis in brain injury group, and also in disputed group of brainstem injury.

Adolescent↗
PubMed1998

Esculentoside A inhibits tumor necrosis factor, interleukin-1, and interleukin-6 production induced by lipopolysaccharide in mice.

Esculentoside A, a kind of saponin isolated from the root of the Chinese herb Phytolaca esculenta, is reported to possess potent anti-inflammatory effects in acute and chronic experimental models. In the present study, we investigated the effects of esculentoside A on the production of tumor necrosis factor (TNF), interleukin-1 (IL-1) and interleukin-6 (IL-6) induced by lipopolysaccharide (LPS) in mice. In vitro experiments demonstrated that esculentoside A (0.1-10 mumol/l) significantly reduced the release of TNF from the peritoneal macrophages derived from mice pretreated with thioglycolate. IL-1 and IL-6 secretion was also obviously inhibited in a concentration-dependent manner by esculentoside A from 0.01 to 10 mumol/l. In vivo experiments demonstrated that detectable TNF was observed 0.25 h after injection, was maximal at 0.5 h, and returned to baseline at 4 h. Maximal production of IL-1 and IL-6 were observed to be 1 and 2 h, respectively, after injection of LPS. Pretreatment of mice with 5, 10, or 20 mg/kg esculentoside A once a day for 7 consecutive days dose-dependently decreased the TNF, IL-1 and IL-6 levels in the sera of mice following LPS challenge. TNF, IL-1, and IL-6 are important cytokines involved in the pathogenesis of inflammatory lesions. Inhibition of inflammatory cytokine production may contribute to the anti-inflammatory effects of esculentoside A.

Animals↗
PubMed1998

Doses to patients in routine X-ray examinations in Malaysia.

A collaborative national survey initiated by the University of Malaya and the Ministry of Health was conducted from 1993 to 1995 to establish baseline patient dose data for seven common types (12 projections) of X-ray examinations in Malaysia. A total of 12 randomly selected public hospitals and 867 patients were included in this survey. The entrance surface doses (ESD) received by the patients were measured using thermoluminescent dosemeters (TLDs) attached to the patient's skin. Histograms are presented showing wide, positively skewed distributions of measured entrance surface doses for each examination. Mean, median, first and third quartile values of ESD and median effective dose are reported. Survey results are generally comparable with those reported in the UK, USA and by the International Atomic Energy Agency (IAEA). The results also provide information on dose level for a lower weight population (mean weight 60 kg) compared with the international reference dose values based on a 70 kg standard. The findings support the importance of the on-going national quality assurance programme to ensure doses are kept to a level consistent with optimum image quality. The data will also be useful for the formulation of national guidance levels as recommended by the IAEA. Furthermore, this study provides patient dosimetry information on healthcare level II countries.

Adult↗
PubMed1998

Quantitative study of Stewart-Holmes test.

Stewart-Homes test (SHT) is an ordinary neurological test performed for the diagnosis for cerebellar disease. We developed a quantitative method based on SHT carried out on the upper limb. Nineteen cerebellar patients and fifteen volunteer healthy subjects were tested. During the test, acceleration of forearm and two associated surface EMGs over biceps and triceps brachialis were recorded and analyzed. (1) Acceleration curve showed an oscillating pattern with flexion and extension over the elbow in both groups, but in cerebellar patient group, the acceleration oscillation wave was more pronounced and latencies of peak acceleration were significantly longer. (2) Correspondingly, the EMGs timing parameters were also different between the two groups: in patient group, ceasing isometric biceps contraction was delayed; rebound EMGs bursts over both biceps and triceps were prolonged. (3) Modelization of the oscillation of acceleration curve with dampened oscillation model showed that in patient group the oscillating amplitude attenuated much more slowly than in control group. A standard curve was established for detecting the acceleration profile abnormalities of SHT in cerebellar patients.

Adult↗
PubMed1997

Stereoselective bimolecular phenoxy radical coupling by an auxiliary (dirigent) protein without an active center.

The regio- and stereospecificity of bimolecular phenoxy radical coupling reactions, of especial importance in lignin and lignan biosynthesis, are clearly controlled in some manner in vivo; yet in vitro coupling by oxidases, such as laccases, only produce racemic products. In other words, laccases, peroxidases, and comparable oxidases are unable to control regio- or stereospecificity by themselves and thus some other agent must exist. A 78-kilodalton protein has been isolated that, in the presence of an oxidase or one electron oxidant, effects stereoselective bimolecular phenoxy radical coupling in vitro. Itself lacking a catalytically active (oxidative) center, its mechanism of action is presumed to involve capture of E-coniferyl alcohol-derived free-radical intermediates, with consequent stereoselective coupling to give (+)-pinoresinol.

Dimerization↗
PubMed1997

Effects of Phytolacca acinosa polysaccharides I with different schedules on its antitumor efficiency in tumor bearing mice and production of IL-1, IL-2, IL-6, TNF, CSF activity in normal mice.

Effects of Phytolacca acinosa polysaccharides I (PAP-I), 5 approximately 40 mg/kg in timing of 7 times/wk, 3 times/wk and 1 time/wk on their antitumor efficiency in Sarcoma-180 bearing mice were comparatively investigated. The results confirmed that PAP-I (10 mg/kg, 3 times/wk) reached its optimal antitumor efficiency. Concanavalin A-, lipopolysaccharides-induced lymphocyte proliferation and the IL-2 production were tested in normal mice which were treated with PAP-I, 5 approximately 50 mg/kg in timing of 1 time/wk and 3 times/wk. The results showed that PAP-I could augment lymphocyte proliferation and IL-2 production in the group treated with PAP-I in timing of once a week. However, in the group 3 times/wk, PAP-I could significantly weaken lymphocyte proliferation and IL-2 production. Further studies on IL-1, TNF and IL-6 secreted from macrophages and the level of CSF activity in serum of normal mice with different schedules showed that PAP-I (10 mg/kg, 3 time/wk) was the best one in regulating the production of IL-1, TNF, IL-6 and CSF activity. M-CSF was confirmed in the serum by using monoclonal antibody of IL-3, GM-CSF and polyclonal antibody of M-CSF. These results suggested that the antitumor effect of PAP-I, may be mainly related to its augmenting effect on macrophages in mice.

Animals↗
PubMed1995

Effects of Phytolacca acinosa polysaccharides I combined with interleukin-2 on the cytotoxicity of murine splenocytes against tumor cells.

Phytolacca acinosa polysaccharides I (PAP-I), a kind of purified polysaccharides, isolated from Phytolacca acinosa Roxb was found to significantly augment the cytotoxicity of murine splenocytes and interleukin-2 (IL-2) activated splenocytes against P815 tumor cells in vitro. The optimal concentration of PAP-I was 1 microgram.ml-1 and the peak level of the cytotoxicity against P815 tumor cells was reached on d 3-5. The supernatants collected from splenocytes cultured with PAP-I alone or in combination with IL-2 showed no effect on the cytotoxicity against P815 tumor cells. Splenocytes from mice injected ip with PAP-I, 5, 10 and 50 mg.kg-1, thrice a week produced more cytotoxicity against P815 and L929 tumor cells compared with the control group. PAP-I ip was shown to significantly increase IL-2 activated killer cell activity (LAK) against P815 tumor cells. The higher the dosage of PAP-I, the more potent the LAK activity was observed. These results confirmed that PAP-I can augment the cytotoxicity of murine splenocyte against tumor cells and LAK activity and warranted further evaluation of its clinical usefulness.

Animals↗
PubMed1995

[Effects of osthol and total-coumarins from Cnidium monnieri on immunological function in kidney yang deficiency mice].

Mice were injected intraperitoneally with hydrocortisone acetate to replicate the animal model of Kidney Yang Deficiency (KYD). Osthol and total-coumarins (TCR) from the fruit of Cnidium monnieri were administered orally to model mice. The effects of osthol and TCR on the immunological function of the KYD mice were observed. The results showed that compare with those in normal mice, the percentage of phagocytosis and the index of macrophage phagocytosis, the level of serum hemolysin and the proliferation of lymphocytes lowered significantly (P < 0.01) in model mice. It was shown that administering osthol or TCR could notably (P < 0.01) prevent the above-mentioned lowering in model mice, revealing that osthol and TCR could improve the immunological function of KYD mice.

Adjuvants, Immunologic↗
PubMed1994

[Inhibitory effects of esculentoside A on mouse macrophages and antibody production].

Esculentoside A (EsA) is a kind of saponin isolated from Phytolacca esculenta Van Houtte. It was shown to significantly inhibit phagocytic activity, intracellular and extracellular production of interleukin-1 by thioglycollate primed murine peritoneal macrophages in vitro at the concentration 0.01-1.0 mumol.L-1. In vivo experiments showed that EsA 2.5-5 mg.kg-1 markedly decreased serum hemolysin concentration in sensitized mice challenged with sheep red blood cells. Inhibition of antibody production by B lymphocytes, phagocytosis and the production of inflammatory mediators by macrophages may partially explain the wide and strong anti-inflammatory effect of EsA.

Animals↗
PubMed1994

Leflunomide inhibits cytokine-induced DNA synthesis of rabbit synovial cells in culture.

The effects of interleukin-1 beta (IL-1 beta), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF alpha) and granulocyte-macrophage colony-stimulating factor (GM-CSF) on DNA synthesis of rabbit synovial cells were studied. IL-1 beta 1000-10,000 U.ml-1, IL-6 10-1000 U.ml-1, TNF alpha 0.5-50 U.ml-1 and GM-CSF 1-100 ng.ml-1 concentration-dependently stimulated DNA synthesis in rabbit synovial cells in culture. Leflunomide (LFM) and its metabolite A77 1726 elicited an inhibitory effect on such cytokine-induced DNA synthesis of synovial cells. These results suggested that IL-1 beta, IL-6, TNF alpha and GM-CSF play a key role in the pathogenesis of rheumatoid arthritis. Inhibition of cytokine-induced proliferation of synovial cells by LFM may partially explain its antirheumatic activity.

Aniline Compounds↗
PubMed1994

Inhibitory effects of triazolodiazepine on mouse splenocytes and peritoneal macrophages in vitro.

Effects of triazolodiazepine (Tri) on mouse splenocyte proliferation and macrophage phagocytosis were studied. Tri 0.1-10 mumol.L-1 significantly inhibited concanavalin A (Con A) 5 micrograms.ml-1 and lipopolysaccharides (LPS) 10 micrograms.ml-1-induced splenocyte proliferation and phagocytic activity of activated peritoneal macrophages. Tri 10 mumol.L-1 reduced Con A-induced colony stimulating factor release from mouse splenocytes and LPS-challenged intracellular and extracellular interleukin-1 production from peritoneal macrophages. These results partially explain the wide and strong anti-inflammatory effects of Tri.

Animals↗
PubMed1994

[Leflunomide inhibits PAF induced DNA synthesis in rabbit synovial cells and PAF production from rat peritoneal macrophages].

Leflunomide (LFM, HWA 486) is an isoxazol derivative with antiphogistic and novel immunomodulating properties. It has been shown to be very effective in preventing and curing arthritis. In this report we found that platelet-activating factor (PAF) at 0.1-10 micrograms.ml-1 significantly stimulated DNA synthesis in cultured rabbit synovial cells. While LFM and its metabolite A771726 elicited inhibitory effects on this action of PAF. These two agents were also shown to markedly inhibit A23187 induced PAF production from rat peritoneal macrophages. The inhibition was dose and time-dependent. The inhibitory effects of LFM and A771726 on DNA synthesis in synovial cells and PAF production from macrophages may play an important role in the antiinflammatory effects of LFM.

Aniline Compounds↗