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Biomedical subjects

H Chen

Publications and source records attributed to H Chen.

At least 559 records · Page 31Linked to original sources
PubMed2000

[Detection of cucumber mosaic virus subgroup II isolate from tobacco plants in Yunnan province].

One of the spherical virus(designated as CMV-YNb) was isolated form the tobacco plants in Yunnan province. SDS-PAGE showed that this virus contained one polypeptide with molecular weights of 55 kD. The polypeptide was submitted to automated Edman degradation, and found the 10 amino acid sequence of the N-terminus of 55 kD protein shares 100% identity with amino acid sequence of coat protein of CMV-Q, which is belong to CMV Subgroup II. Western blot analysis also showed that this 55 kD protein was serological related to CMV-Q. A 0.9 kb cDNA fragment was amplified by RT-PCR from the RNA template of CMV-YNb with the QCf/QCr primer pair, which was designed according to the CP gene sequence of CMV-Q. The cDNA fragment was then cloned and sequenced. The fragment comprises 865 bp (EMBL accession number: AJ242585), including a 197 bp of 5' intergenic region, 657 bp of CP gene encoding 158 amino acids and a 11 bp of 3' partial non-coding region. Comparison of the nucleotide and amino acid sequences of CMV-YNb CP gene with that of CMV strains belonging to Subgroup II, and that of CMV strains belonging to subgroup I showed 97%-98% and 96%-99%, 75%-76% and 78%-79% identities, respectively. With these data, we made a conclusion that the CMV-YNb is an isolate of CMV Subgroup II.

Amino Acid Sequence↗
PubMed2000

[Effect of lysophosphatidylcholine on endothelial cell surface expression of adhesion molecules].

Extensive monocyte recruitment is an early phenomenon associated with the development of atherosclerotic lesion, in which adhesion molecules expressed by endothelial cell play an active role. In this study we examined the effects of Lysophosphatidylcholine(Lyso-PC), a major phospholipid component of atherogenic lipoproteins, on the expression of adhesion molecules for monocytes, such as intercellular adhesion molecule-1(I-CAM-1), endothelial-leukocyte adhesion molecule-1(E-selectin) and vascular cell adhesion molecule-1(VCAM-1), in cultured human umbilical vein endothelial cells(HUVECs). After treating HUVECs with different concentration Lyso-PC at different times, the expression of adhesion molecules on the surface of HUVECs induced by Lyso-PC were analyzed using flow cytometry. The results showed that compared with control group, the surface expression of ICAM-1 and VCAM-1 was increased on HUVECs treated with Lyso-PC. ICAM-1 and VCAM-1 expression was maximally induced 1 h after stimulated with 50 micrograms/mg Lyso-PC, compared to basal values. At the 3 h after stimulation, ICAM-1 dropped to basal level while VCAM-1 dropped below to basal level. The effects of Lyso-PC on E-selection expression were negligible with in 3 h. However, at the 3 h of treatment with 50 micrograms/ml, the E-selectin expression on HUVECs began to be up-regulated significantly. We conclude that in addition to its monocyte chemoatractant activity, Lyso-PC can selectively induce ICAM-1 and VCAM-1 expression on the surface of HUVECs. Lyso-PC may play an important role in monocyte recruitment into athersclerotic lesions.

Cells, Cultured↗
PubMed2000

[Microwave treatment of ethmoidal nerve under nasal endoscopy in the patients with allergic rhinitis].

OBJECTIVE: To study the effect of microwave treatment of ethmoidal nerve on allergic rhinitis. METHOD: 106 cases of allergic rhinitis patients were treated with ethmoidal nerve microwave under nasal endoscope. RESULT: It showed marked effect in 89 cases(84.0%), immprovement in 12 cases(11.3%) and failed in 5 cases (4.7%) in one year follow-up. The overall effective rate was 95.3%. CONCLUSION: This result indicated that the microwave tissue coagulation in treating allergic rhinitis unde nasal endoscope is a good method for clinical treatment.

Adolescent↗
PubMed2000

The preliminary study of interferon-gamma gene transfection to human Tenon's capsule fibroblasts in vitro.

PURPOSE: To investigate the results of the interferon-gamma (IFN-gamma) gene transfer and transient expression in human Tenon's capsule fibroblast in vitro in order to find a way to gene therapy in vivo. METHOD: Using LipofectAMINE, IFN-gamma gene was transferred in human Tenon's capsule fibroblasts with plasmid pcDNA3 IFN-gamma. Its mRNA transcription and protein expression were determined by RT-PCR and flow cytometry assay respectively. RESULT: The human Tenon's capsule fibroblasts transferred the IFN-gamma gene can express the IFN-gamma in transcription and protein level transiently. CONCLUSION: IFN-gamma gene can be transferred successfully and expressed expressed efficiently in human tenon's capsule fibroblast in vitro.

Conjunctiva↗
PubMed2000

[The clinical analysis of 260 combined surgery of glaucoma and cataract].

PURPOSE: To evaluate the efficacy of the combined surgery of glaucoma and cataract. METHODS: We reviewed 260 consecutive cases (279 eyes) who underwent the combined procedure of glaucoma and cataract. The patients were divided into three groups: group 1: extracapsular cataract extraction combined with trabeculectomy; group 2: extracapsular cataract extraction and intraocular lens implantation combined with trabeculectomy; group 3: cataract phacoemulsification and intraocular lens implantation combined with trabeculectomy; We analyzed and compared the postoperative visual acuity (VA), intraocular pressure(IOP) and complications among three groups. RESULTS: 16.2%, 32.4% and 43.5% of patients in three groups achieved 0.3 or better VA. The VA improved rate were 46.6%, 70.4% and 78.3% respectively. The mean postoperative IOP of three groups were 12.72 +/- 6.66 mmHg(1 mmHg = 0.133 kPa), 13.01 +/- 5.26 mmHg, 12.63 +/- 4.66 mmHg(compared with preoperative IOP, P < 0.01). The complications of group 3 were much less than those of the other two groups. CONCLUSION: The combined surgery can control the IOP effectively; The triple procedure can improve the VA rapidly and the phacoemulsification technique can decrease the complications.

Adult↗
PubMed2000

[Three-dimensional reconstruction of internal auditory meatus and anatomical study of the inner structures].

OBJECTIVE: To provide anatomical basis for surgical operation in internal auditory meatus (IAM). METHODS: Structures of cerebellopontine angle (CPA) and IAM in 25 temporal bone specimens (50 sides) fixed in formalin were measured. Three-dimensional reconstruction (3DR) of IAM in 13 normal adults (26 sides) was conducted using spiral CT scanning. RESULTS: IAM took a conic shape with larger inside and smaller outside. The average width of IAM was (4.16 +/- 1.23) mm(2.87-6.83 mm) in horizontal dimension, the average height was (3.14 +/- 1.01) mm(2.23-4.45 mm) in vertical dimension, the average length was (8.67 +/- 2.31) mm (6.77-11.22 mm), the average volume was (98.23 +/- 16.56) mm3(67.44-133.21 mm3). There were 1-4 internal auditory arteries branched from the anterior-inferior cerebellar artery, which formed a vascular ansa near the opening of IAM. The average length of the facial nerve in IAM was (0.98 +/- 0.03) mm (0.89-1.07 mm), the average diameter of vestibulocochlear nerve was (1.67 +/- 0.05) mm (1.42-1.97 mm), the average diameter of the intermediate nerve (0.23 +/- 0.02) mm (0.19-0.26 mm). CONCLUSION: It is necessary to pay attention to types of vascular ansa and relative nerve location in IAM during operation.

Adult↗
PubMed2000

[Effect of low dose gossypol treatment on male sperm nuclear basic protein].

OBJECTIVE: Study on human sperm nuclear basic proteins after low dose of gossypol treatment. METHODS: Twenty-three men with normal fertility were divided into two groups. The experimental group included 15 men which were treated daily with gossypol (15 mg/d for 12 weeks and treated with 10 mg/d for 32 weeks continuously), 8 men were used in the control group. Semen was collected at 1, 4, 8, 12, 16, 24, 36 and 44 weeks after gossypol treatment and 10 weeks after stopping treatment. Total nuclear basic protein (TNBP) was extracted and TH/TP, HP1/(HP2+HP3) ratios were determined by scanning microdensitometry following electrophoresis of TNBP in polyacrylamide gels. RESULTS: The TH/TP ratio of control and the gossypol treated group were 0.17 +/- 0.07 and 0.63 +/- 0.79(P < 0.05); The HP1/(HP2+HP3) ratio of control and gossypol treated group were 1.05 +/- 0.21 and 1.47 +/- 0.18 (P < 0.01). These two parameters were returned to normal after 10 weeks of stopping gossypol treatment. CONCLUSIONS: The interruption of histone-to-protamine replacement reaction (HPRR) and alteration of nuclear basic proteins induced by low dose gossypol treatment might lead to infertility. Changes of HPRR and nuclear basic protein were reversible after stopping gossypol treatment.

Adult↗
PubMed2000

[Detection of proteolytic activity of hepatitis C virus NS3-4A protease using enzymelinked immunosorbent assay].

OBJECTIVE: To establish an ELISA method for detecting proteolytic activity of HCV serine protease for screening inhibitors against HCV. METHODS: HCV recombinant plasmid pMAL-c2/NS3-4A was transformed into the E. coli strain K12 TB1. Maltose-binding-protein (MBP)-NS3/NS3-4A fusion protein expression were induced by adding isopropyl-beta-D-thiogalacto-pyranoside (IPTG) and purified by affinity chromatography. The immunological activities of the fusion protein were analyzed by Western blot. A peptide substrate was used to analyze the biological activity of the fusion protein. The hydrolyzed product was treated with sodium iodacetate and labeled with digoxigenin, then adding immunological anti-digoxigenin-alkaline phosphatase conjugate to detect the protease activity by colorimeteric reaction. RESULTS: The purified MBP-NS3 and MBP-NS3-4A proteases were identified as 112,000 u and 116,000 u protein by Western blot. HCV NS3/NS3-4A protease showed substrate cleavage activities by ELISA. Coefficients of variation (CV) of ELISA in a lot and among the lots were 4.16% and 7.52% respectively, the P/N was 3.63 under the best experimental conditions determined by L9 (3(4)) factorial design. The method confirmed that 8.36 mumol/L 1,4-naphthoquinone had 50% inhibitive activity on HCV serine protease. CONCLUSIONS: We have established a simple and rapid ELISA method with stable repeatability for detecting proteolytic activities of HCV NS3-4A protease, which might be used for screening and studying of specific inhibitors of HCV serine protease NS3-4A.

Enzyme-Linked Immunosorbent Assay↗
PubMed2000

The bi-directional regulation of filamin on the ATPase activity of smooth muscle myosin.

OBJECTIVE: The aim of this study is to investigate the functional relationship between filamin, a known actin binding protein, and myosin and the effects of filamin on the interaction between myosin and actin. METHODS: Ultra-centrifugation method was used to investigate the binding of filamin to both phosphorylated and unphosphorylated myosins. Mg-ATPase activities of both phosphorylated and unphosphorylated myosins in the presence and absence of actin were measured to observe the effects resulted from filamin-actin and filamin-myosin interactions. RESULTS: It was found that filamin is also a myosin binding protein. Filamin inhibited the actin activated Mg-ATPase activity of phosphorylated myosin and stimulated Mg-ATPase of phosphorylated myosin in the absence of actin; in addition, filamin stimulated Mg-ATPase activity of unphosphorylated myosin in both the presence or absence of actin. CONCLUSION: The result suggest that the effects of filamin on the myosin Mg-ATPase activities are bi-directional, i.e., stimulatory via binding to myosin and inhibitory via binding to actin.

Actins↗
PubMed2000

[Matrix effects in inductively coupled plasma mass spectrometry by use of organic solvents].

Matrix effects arising from ethanol, propanol, glycerol, acetic acid, ethylenediamine and triethanolamine in inductively coupled plasma mass spectrometry have been studied. Addition of ethanol, propanol, glycerol, acetic acid, ethylenediamine and triethanolamine into solution has an enhancement effect on the signal intensity of analyte with ionization potential between 9 and 11 eV. The ethylenediamine and triethanolamine have higher enhancement effect on the signal intensity of Hg than that of ethanol, propanol, glycerol and acetic acid. Addition of ethylenediamine and triethanolamine into solution has a suppression effect on the signal intensity of Pb and Sr. The mechanism of the enhancement or suppression was investigated. The signal enhancement of Hg in the presence of ethylenediamine and triethanolamine is not caused by improved degree of ionization of Hg and nebulization efficiency. The suppression effects of Pb and Sr in the presence of ethylenediamine and triethanolamine are due to decrease of atomization efficiency of these elements. A method for the determination of Hg in the biological standard samples by ICP-MS was developed.

1-Propanol↗
PubMed2000

[Comparison between two spectral lines for the determination of Pb].

This article introduces the comparison between two sensitive spectral lines for the determination of Pb. The result proved that the sensitivity of 217.0 nm spectral line was increased by at least one time and the other indices also approached those of 283.3 nm spectral line. We concluded that it could be used to hygienic detection.

Environmental Pollution↗
PubMed2000

[The noise-filtering of chemiluminescence spectra with wavelet multiresolution analysis].

In this paper, the wavelet multiresolution signal decomposition was successfully applied to the filtering of high-frequency noise in chemiluminescence spectra. The spectra signal-to-noise ratio was greatly improved while the noise was suppressed effectively. The effect of wavelet basis and time of decomposition are also discussed. It is shown that the wavelet analyses have many advantages in processing of discrete signals.

Algorithms↗
PubMed2000

[Determination of ultra-trace rare-earth elements in human plasma by inductively coupled plasma mass spectrometry].

Inductively coupled plasma mass spectrometry (ICP-MS), highly sensitive inorgnic analytic technique, fits to determine ultra-trace rare-earth elements in human plasma. Under the optimized conditions detection limits for 15 rare-earth elements are in the range of 0.7 (for Eu)-5.4 (for Gd) ng.L-1. Indium as an internal standard element is used to compensate for matrix suppression effect and sensitivity drift. Three kinds of preparation methods, diluted with 1% HNO3, digested with HNO3-H2O2 and with HNO3-HClO4, are checked and compared, and the former is the simplest way to be measured. The samples diluted with 1% HNO3, stored in 4 degrees C, are very steady for 16 days. With the method, 11 healthy plasma samples in Changchun area of China are analysed.

Europium↗
PubMed2000

[Modern spectral estimation of ICP-AES].

The inductively coupled plasma atomic emission spectrometry (ICP-AES) and its signal characteristics were discussed using modern spectral estimation technique. The power spectra density (PSD) was calculated using the auto-regression (AR) model of modern spectra estimation. The Levinson-Durbin recursion method was used to estimate the model parameters which were used for the PSD computation. The results obtained with actual ICP-AES spectra and measurements showed that the spectral estimation technique was helpful for the better understanding about spectral composition and signal characteristics.

Regression Analysis↗
PubMed1999

Cysteine mutagenesis and homology modeling of the ligand-binding site of a kainate-binding protein.

Glutamate receptors comprise the most abundant group of neurotransmitter receptors in the vertebrate central nervous system. Cysteine mutagenesis in combination with homology modeling has been used to study the determinants of kainate binding in a glutamate receptor subtype, a low molecular weight goldfish kainate-binding protein, GFKARbeta. A construct of GFKARbeta with no cysteines in the extracellular domain was produced, and single cysteine residues were introduced at selected positions. N-Ethylmaleimide or derivatized methanethiosulfonate reagents (neutral or charged) were used to modify the introduced cysteines covalently, and the effect on [(3)H]kainate binding was determined. In addition, cysteine mutants of GFKARbeta transiently expressed in HEK293 cells were labeled with a membrane-impermeable biotinylating reagent followed by precipitation with streptavidin beads and specific detection of GFKARbeta by Western blot analysis. The results are consistent with the proposal that the energy driving kainate binding is contributed both from residues within the binding site and from interactions between two regions (i.e. two lobes) of the protein that are brought into contact upon ligand binding in a manner analogous to that seen in bacterial amino acid-binding proteins.

Binding Sites↗
PubMed1999

Long-term suppression of Leydig cell steroidogenesis prevents Leydig cell aging.

Male aging is accompanied by reduced testosterone production by the Leydig cells, the testosterone-producing cells of the testis. The mechanism by which this occurs is unknown. Based on the observations that reactive oxygen is capable of damaging components of the steroidogenic pathway and that reactive oxygen is produced during steroidogenesis itself, we hypothesized that long-term suppression of steroidogenesis might inhibit or prevent age-related deficits in Leydig cell testosterone production. To test this, we administered contraceptive doses of testosterone to groups of young (3 months old) and middle-aged (13 months old) Brown Norway rats via Silastic implants to suppress endogenous Leydig cell testosterone production. After 8 months, the implants were removed, which rapidly (days) restores the ability of the previously suppressed Leydig cells to produce testosterone. Two months after removing the implants, when the rats of the two groups were 13 and 23 months of age, respectively, the Leydig cells in both cases were found to produce testosterone at the high levels of young Leydig cells, whereas significantly lower levels were produced by the 23-month-old controls. Thus, by placing the Leydig cells in a state of steroidogenic "hibernation," the reductions in Leydig cell testosterone production that invariably accompany aging did not occur. If hormonal contraception in the human functions the same way, the adverse consequences of reduced testosterone in later life (osteoporosis, reduced muscle mass, reduced libido, mood swings, etc. ) might be delayed or prevented.

17-Hydroxysteroid Dehydrogenases↗
PubMed1999

Pharmacokinetics of (-)-beta-D-dioxolane guanine and prodrug (-)-beta-D-2,6-diaminopurine dioxolane in rats and monkeys.

(-)-beta-D-Dioxolane guanine (DXG) is a nucleoside analog possessing potent activity against human immunodeficiency virus type 1 (HIV-1) and type 2 (HIV-2), and hepatitis B virus (HBV) in vitro. Owing to the limited aqueous solubility of DXG, (-)-beta-D-2,6-diaminopurine dioxolane (DAPD), a more water-soluble prodrug of DXG, is being developed for clinical use. The purpose of this study was to characterize the pharmacokinetics of DXG after administration of DXG and DAPD to rats and monkeys. After intravenous administration of DXG, plasma concentrations of the nucleoside declined in a biexponential manner, with a terminal-phase half-life of 0.44 +/- 0.14 hr (mean +/- SD) in rats and 2.3 hr in monkeys. Total clearance of DXG was 4.28 +/- 0.99 liters/hr/kg in rats and 0.72 liters/hr/kg in monkeys. Renal excretion of unchanged DXG accounted for approximately 50% of total clearance in both species. Steady state volume of distribution of DXG was 2.30 liters/kg in rats and 1.19 liters/kg in monkeys. After intravenous administration of DAPD to rats, prodrug concentrations declined with a half-life of 0.37 +/- 0.11 hr. DXG was rapidly generated from DAPD, with approximately 61% of the dose of DAPD being converted to DXG. After administration of DAPD to monkeys, only concentrations of metabolite DXG could be determined owing to rapid conversion of DAPD to DXG during sample collection. The half-lives of DAPD and DXG after intravenous administration determined from urinary excretion data were 0.8 +/- 0.4 and 1.6 +/- 0.2 hr, respectively. Oral bioavailability of DAPD was estimated to be approximately 30%.

Administration, Oral↗