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Biomedical subjects

H Liu

Publications and source records attributed to H Liu.

At least 667 records · Page 37Linked to original sources
PubMed1999

[Effects of human thorax tissues on conduction of electrocardiogram and body surface potential].

In this paper, the forward problem of electrocardiogram(ECG) has been calculated by means of numerical simulating techniques. Firstly, It is focused on the effects of organs and tissues within the thorax on the body surface potentials under a 2-D cross section of thorax in terms of finite element method (FEM). To check the effect of skeletal muscle layers on ECG, the simulating computation of ECG, by a method combining FEM with boundary element method (BEM), has been carried out in terms of a 3-D thorax model.

Algorithms↗
PubMed1999

[Perspectives of effect on new electrode technology with implantable motor prostheses for stimulating peripheral nerves].

This paper explores approaches to electrode technology and stimulating techniques that selectively activate specific portions of a peripheral nerve trunk with much less implanted hardware than is required with present motor prosthesis systems. The first section reviews the vulnerability of nerves to both mechanical and electrical factors and suggests ideas on how these findings might be utilized in future electrodes. The second section presents results on longitudinally oriented intrafascicular electrodes for nerve stimulation recording. The third section reviews results on longitudinal intrafascicular electrodes for nerve stimulation and recording.

Animals↗
PubMed1999

[Determination of the azetidine-2-carboxylic acid from lily of the valley].

This paper reports the separation and determination of the azetidine-2-carboxylic acid in lily of the valley by high performance liquid chromatography (HPLC) with post-column derivatization and fluorescence detection. The operating conditions were cation exchange resin column (30 cm x 0.4 cm i.d.) with buffer solution A [1.96% (mass fraction) sodium citrate solution pH 3.10 +/- 0.02] and B [2.1% (mass fraction) sodium nitrate solution pH 9.60 +/- 0.02] as mobile phase at flow-rate of 0.4 mL/min, gradient elution, column temperature 65 degrees C, detection wavelength lambda ex = 338 nm and lambda em = 425 nm. The retention time of azetidine-2-carboxylic acid was 5.86 minutes. The recovery was 96.4% and coefficient of variation was 0.94%. This method is simple, rapid and sensitive.

Azetidinecarboxylic Acid↗
PubMed1999

[Characterization and phylogenetic analysis of the new species of the Leucobacter tropicalis sp. nov].

A new aerobic, gram-positive, non-sporulating, rod-shaped organism is described. Strain F-8 was isolated from tropical soil, and has the following characteritics: the menaquinone contains a side chain with 11 isoprenyl units(MK-11); 2,4-diaminobutyric acid, glutamic acid, alanine, glycine and a small amount of gamma-aminobutyric acid present in the cell wall at a molar ratio of 0.77:1.0:1.66:0.95. The major cellular sugar were rhamnose, galactose and glucose. The G + C content of DNA is 68 mol%. The 16S rRNA gene was amplified, cloned and sequenced, a phylogenetic tree was constructed on the 16S rRNA gene sequences. The tree clearly indicated that strain F-8 forming the same lineage with leucobacter komagatae, the level of binary sequence similarity between strain F-8 and L. komagatae is 96%. Based on the characteristics, allow the placement of strain F-8 into the genus Leucobacter, but F-8 showed some differences in biochemical and physical characters from the reported species L. komagae. A new species name, Leucobacter tropicalis sp. nov. was proposed for this isolate. The type strain is designated F-8.

Base Sequence↗
PubMed1999

[Effects of combined treatment with flouride and 1,25-dihydroxyvitamin D3 on the histomorphometry and biomechanical properties of bone in ovariectomized rats].

OBJECTIVE: To evaluate the potential use of a combination of bone formation-promoting agents and a differentiation agent of osteoblast as a treatment for postmenopausal osteoporosis. METHODS: The effects of combined and separate administration of flouride-Ca (0.45 ng F- + 13.56 mg Ca2+)/(kg.d) and 1,25-dihydroxyvitamin D (135 pmol/d s.c.) on the histomorphometric parameters in the secondary spongiosa of proximal tibia and biomechanical properties of femoral midshaft in ovariectomized (OVX) rats were examined. RESULTS: Compared with OVX group, OVX + fluoride-Ca group (O + F) and OVX + Fluoride-Ca + 1,25-dihydroxyvitamin D(O + F + D) two kinds of treatment caused 42%, 91% more in %Tb Ar, 14%, 38% more in Tb Wi, 24%, 46% more in Tb N, 26%, 43% less in Tb Sp, 45%, 42% less in % E Pm, 30%, 60% more in Ob Pm respectively. W Wi in O + F treatment had no significant difference from OVX group but 15.2% in O + F + D treatment compared with sham group, MLT increased 16% in O + F group, had no difference from O + F + D. No significant alteration of mechanical strength at femoral midshaft in both O + F and O + F + D was found. There were significant difference in above changes of parameters except % Ob Pm. CONCLUSIONS: Above two treatments could prevent the loss of cancellous bone, reduced the resorption caused by OVX, protected trabecular microarchitecture, and stimulated bone formation significantly. The combined treatment avoided potential mineralization defect caused by F-Ca treatment alone, and two treatments maintained mechanical strength at femoral midshaft.

Animals↗
PubMed1999

[Evaluation of the risk of vertebral fracture predictable with quantitative tibial ultrasound velocity test in postmenopausal women].

OBJECTIVE: To investigate predicting value of increased risk of vertebral fracture associated with reduction of tibial ultrasound velocity (SOS) test in postmenopausal women. METHODS: 193 menopausal women aged(54.4 +/- 7.3) years were included in our study. Post menopausal period of these subjects were (16.0 +/- 7.8) years. These participants received tibial ultrasound speed (SOS) test, DEXA for lumbar 2-4, femoral neck wards triangle and trochant, as well as SPA for 1/3 and 1/10 of distal forearm. Vertebral fracture was determined by radiograph of lateral lumbar and thoracic spine. RESULTS: 54 subjects were found at least one vertebral deformation, and no vertebral deformation was found in other 139 subjects. Tibial SOS was significantly lower in subjects with than without vertebral fracture [(3,651.9 +/- 188.3) vs (3,731.3 +/- 140.8), P < 0.01], The similar results were also found in BMD. The analysis of logistic regression showed: odds ratio (OR) of SOS to vertebral fracture was 1.86(P < 0.01) when 1 standard deviation of SOS changed. It was lower than OR of BMD by DEXA(2.25-3.28, all P < 0.001), and similar with OR of BMD by SPA (1.50-1.96). CONCLUSIONS: Low SOS was associated with presence of vertebral fracture in postmenopausal women. SOS could predict the risk of vertebral fracture, 86% of the risk of vertebral fracture increased when 1 standard deviation of SOS reduced.

Aged↗
PubMed1999

[The role of ICAM-1 in leukocyte adherence to endothelial cells induced by hypoxia/reoxygenation].

OBJECTIVE: To determine whether intercellular adhesion molecule-1 (ICAM-1) mediats the polymorphonuclear leukocyte (PMN) adherence to endothelial cells elicited by hypoxia/reoxygenation (H/R). METHODS: Human umbilical vein endothelial cells (HUVEC) monolayers was exposed to hypoxia for 30 min or 120 min then reoxygenated. Count the number of PMN in adhesion assays. Expression of ICAM-1 and ICAM-1 mRNA was detected by immunohistochemical analysis and in situ hybridization. RESULTS: PMN adhesion to HUVEC exposed to H/R was significantly increased (1 fold) as compared with that of control (P < 0.01). H/R induced hyperadherence was significantly diminished by monoclonal antibodies directed at ICAM-1 or CD11a/CD18. The results showed an increased expression of ICAM-1 and ICAM-1 mRNA on HUVEC exposed to H/R. Hypoxic HUVEC might be responsible for PMN adesion. CONCLUSIONS: ICAM-1 mediated the adhesive interaction between PMN and VEC induced by hypoxia/reoxygenation.

Cell Adhesion↗
PubMed1999

[Studies on the anti-enteropathogenic bacteria action of Herba Pogostemonis extracts].

The results of antimicrobial test in vitro of water-extracts and volatile oil of the Herba Pogostemonis shown that the water-extracts posses some inhibitory activity on all the tested bacteria, including Salmonella, Escherichia coli, Shigella flexneri and Staphylococcus aureus, while inhibition to S. aureus is more stronger than to Enterobacteriaceae (P < 0.01). In addition, the activity of anti-enteropathogens of water-extracts of the herb collected from Gaoyao county is more stronger than of the herb collected from Wuchuan county (P < 0.01).

Anti-Bacterial Agents↗
PubMed1999

[Electron microscope observation on effect of kudingcha inspissation tea on small intestine villus in the adiposity rats].

OBJECTIVE: Experimental study on pharmacological action of Guang Dong kudingcha inspissation tea on small intestine villus in the adiposity rats (nutrition obesity). METHODS: By using electron microscope method, check on small intestine villus of 60 experiment rats of just wean and count and analyse and conclude. RESULTS: Under the scan electron imcroscope, the surface configuration on small intestine villus of model group and various kudingcha dosage groups is similar to the blank (P > 0.05), but fenfluramine group appear constriction on top end of small intestine villus. CONCLUSION: Compring with fenfluramine, Guang Dong kudingcha inspissation tea has not effect on configuration of small intestine of adiposity rats (nutrition obesity), but has more strong modulation function on fat tissue lipocyte hypertrophy and quantitative.

Adipocytes↗
PubMed1999

The study of influencing factors on the growth characters of Sprague-Dawley rat retinal neurons in vitro.

PURPOSE: To investigate the influencing factors in culturing Sprague-Dawley (S-D) rats retinal neurons in order to lay foundation for further experimental research. MATERIALS AND METHODS: Retinal cells were plated on plastic plates and coverslips coated with poly-l-lysine or ethylene imine polymer for primary culture. The cultured cells were divided into following groups: 1. Culture medium changed every 2 to 3 days vs changed only once; 2. Cytosine arabinoside (Ara-C) added to the culture medium vs not added. The cells were observed and pictured under inverted phase contrast microscope. The cells were identified through immunocytochemistry. RESULTS: The immunofluorescence showed that most of the cultured cells were neurons, among them were a few retinal ganglion cells. In the cultured group of which substrata coated with poly-l-lysine and culture medium added with Ara-c, the neurons intended to aggregate into clusters with relatively straight neurites. In the group of which substrata coated with ethylene imine polymer and medium added with Ara-c, the neurons grew dispersively with bent neurites. Both of them survived for 2 to 3 weeks. The cells which plated in the medium not added with Ara-c did not aggregate into clusters and survived longer than 4 weeks. In the group of which medium changed several times, the survival time of neurons was shorter than that in the medium changed only once. CONCLUSIONS: The retinal neurons plated on the substrata coated with ethylene imine polymer are easy to observe because of its dispersive growth. It is not favorable for the growth of the neurons by changing culture medium many times. Ara-c may possibly have side effect on the growth of retinal neurons.

Animals↗
PubMed1999

[Effect of N-methyl-D-aspartate and dexamethasone on apoptosis of rat cultured retinal ganglion cells].

PURPOSE: To investigate the effect of N-methyl-D-aspartate(NMDA) and Dexamethasone on cultured rat retinal ganglion cells (RGCS). METHODS: RGCs were obtained from 1-3 days old SD rats. In two groups, exposure of cocultured ganglion cells to N-methyl-D-aspartate (20-500 mumol/L) lasted for 24 hours. Apoptotic cells were identified by Hochest 33258 in one group; In another group, 0.4% Trypan blue dye was added. Cells excluding the dye were counted, and the survival rate of cells was determined by the ratio of the excluding cells in the experiment over in the control; Cocultured RGCs and purified RGCs were exposed to Dexamethasone(1 x 10(-4), 1 x 10(-5) and 1 x 10(-6) mol/L). After 24 hours, apoptotic cells were identified by Hochest33258. RESULT: Cocultured RGCs showed distinct morphological appearance of apoptotic cells when they were exposed to NMDA. The survival rate of cells was dose-related to the concentration of NMDA. Cocultured RGCs didn't show typical apoptotic appearance at 24 hours after exposure to Dexamethasone. But purified RGCs did so, even in the control group. CONCLUSION: NMDA has the effect of inducing cocultured RGCs apoptosis. Dexamethasone had no this effect on RGCs. Without additional neurotrophic factors, purified RGCs may become apoptotic cells when cultured in vitro for 24 hours.

Animals↗
PubMed1999

[Removal of YY1 binding sites in HPV 16 LCR increases viral transforming activities on mouse fibroblasts].

OBJECTIVE: To study the effect of removal of YY1 binding sites within the LCR region of HPV 16 on viral transforming activity. METHODS: Previously we had generated new plasmids carrying HPV 16 whole genome, which contained naturally occurred mutated LCR sequences. The viral transforming abilities on mouse fibroblasts were evaluated in anchorage-independent assays, while the expression and activity of YY1 protein in fibroblasts were tested with EMSA and luciferase assays. RESULTS: YY1 protein was expressed in mouse fibroblasts C127, with ability for DNA binding and repression on P97 activity. Both HPV 16 wild-type DNA and mutated DNAs were transfected into C127 cells and spread to the soft-agarose mediums after selecting with G 418. The growth numbers of the cells transfected with mutated HPV 16 DNAs were 2-10 fold more than that with wild-type HPV 16 DNA. CONCLUSION: Like in epithelial cells or cell lines, transcription regulator YY1 is widely expressed in rodent fibroblasts. Removal of YY1 binding motifs can elevate in the context of the whole genome, the anchorage independent growth ability and the transforming capacity of HPV 16 on the mouse fibroblasts.

Animals↗
PubMed1999

[Detection of IgM-antibody to hepatitis G virus and its clinical significance].

OBJECTIVE: To provide a rapid and early serodiagnostic technique for the patients with hepatitis G virus(HGV). METHODS: A capture ELISA was developed to detect anti-HGV IgM in sera using synthetic peptides of HGV NS3 NS5 gene regions conjugated with horseradish peroxidase. RESULTS: This assay was not disturbed by competition of specific IgG or interfered by RF and did not cross-react with HAV, HBV, HCV, HEV, CMV and EBV. Among 46 sera of non-A-E hepatitis, 14 were positive for anti-HGVIgM, the positive rate was 30.43%, 6 was positive for HGV RNA the positive rate was 42.86%. 12 paired sera from acute stage of HGV patients were all positive by capture-ELISA. CONCLUSION: This method is sensitive, specific, rapid and stable for detecting anti-HGV IgM, and is useful in the early diagnosis of HGV infection.

Enzyme-Linked Immunosorbent Assay↗
PubMed1999

[No switch region is found in the regulatory sequence of HPV 16 for promoter P97].

OBJECTIVE: Cellular transcriptional regulatory factor YY1 represses the activity of the early promoter P97 of HPV 16, but the regulatory activity to early promoter P105 of HPV 18 depends on a switch region which locates at the upstream sequences of YY1 binding sites. This study is to find out whether within the HPV 16 LCR there is such motif. METHODS: DNA sequences of the whole HPV 16 LCR region were analyzed. Two similar switch structures were found. Different CAT reporter plasmids, one containing HPV 16 reference and the other mutated LCRs, both starting at the end of L1 and from the beginning of the enhancer, were generated and transfected in HeLa cells transiently. RESULTS: CAT assays showed there is no change of regulation pattern of YY1 on P97, when the two switch-similar structures were deleted. Sequences analysis also showed that no switch region like motif could be demonstrated in enhancer region, in promoter proximal segment, and even in E6/E7 area. CONCLUSION: It suggests that there is no such switch region within HPV 16 transcriptional regulatory region.

DNA, Viral↗
PubMed1999

[Morphological study on chronic hypertrophic rhinitis treated with cryosurgery].

OBJECTIVE: To approach the effect of cryosurgery on the mucous membrane of patients with chronic hypertrophic rhinitis. METHODS: Thirty cases of chronic hypertrophic rhinitis treated with cryosurgery were observed by light, transmission and scanning electron microscopy. RESULTS: Before cryosurgery, the mucous epithelia were squamous metaplastic. After the first cryosurgery, the epithelia degenerated and fell off. After the second cryosurgery, the epithelia regenerated and cilia formed. CONCLUSION: The results showed that cryosurgery could diminish the pathological changes and improve the nasal function.

Chronic Disease↗