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Biomedical subjects

Liang Chen

Publications and source records attributed to Liang Chen.

At least 109 records · Page 6Linked to original sources
PubMed2004

Electrophysiologic study of influence on C7 innervated muscles after transection of different C7 fascicles.

An experimental study was conducted to observe the electrophysiologic changes in C7 innervated muscles following transection of different fascicles of C7 nerve root in the brachial plexus with already transected C5 and C6. Twenty-four Sprague-Dawley rats were randomized into groups A, B, and C. C5 and C6 transection, C5, C6, and partial C7 (anteriolateral fascicles of the anterior division) transection, and C5, C6, and C7 transection were done in group A, B, and C, respectively. One month postoperatively, compound muscle action potentials of the latissimus dorsi, triceps, and extensor digitorum communis were recorded. Decreased amplitude and a prolonged latent period were seen in all three muscles of group C. No obvious changes, however, were found in groups A and B. This suggests that when the upper trunk of the brachial plexus is injured, partial transection of C7 does not obviously impair C7 innervated muscle function. Selective ipsilateral C7 transfer is safe for the treatment of upper-trunk avulsion.

Action Potentials↗
PubMed2004

Isocyanate vapor-induced antigenicity of human albumin.

BACKGROUND: The bioreactivity of isocyanate, a leading cause of occupational asthma, has led to uncertainty regarding the chemical's antigenicity and mechanisms that elicit immunopathology. OBJECTIVE: To understand better the biologically relevant antigenic forms of hexamethylene diisocyanate (HDI), commonly used in the auto body industry. METHODS: Human albumin was exposed to HDI vapors through a novel approach designed to model the air-liquid interface of the human airway. Vapor HDI-exposed albumin was characterized by electrophoresis, chemical substitution analysis, mass spectrometry, and serology studies on auto body shop workers (N=203) and HDI asthmatics (N=11). RESULTS: HDI vapors caused significant changes in the shape and/or charge of human albumin, which differed from albumin exposed to liquid phase HDI, with lower isocyanate substitution ratios and distinct electrophoretic mobility. Specific sites of vapor HDI conjugation to albumin were identified at His(247) and Lys(414). Vapor HDI-exposed albumin was specifically recognized by the humoral arm of the human immune system, with a strong dependence on albumin as the carrier. Vapor HDI-exposed albumin-specific IgG titers were significantly associated with HDI exposure (P=.001), and specific IgE was detectable in 55% (6/11) of isocyanate asthmatics versus 1.5% (3/203) of exposed healthy workers. Parallel studies using HDI-exposed albumin conjugates produced by previously published methods showed less significant associations of HDI-specific IgG and IgE with exposure and disease, respectively. CONCLUSION: HDI-albumin conjugates produced by novel vapor phase exposure methods may be more physiologically relevant than those produced by previously published methods and of greater utility in characterizing the immune responses associated with HDI exposure and asthma.

Albumins↗
PubMed2004

[Effects of estradiol on deltamethrin-induced neurotoxicity in rat cerebro-cortical synaptosomes].

OBJECTIVE: To investigate the neuroprotective effect of estradiol on the release of excitatory amino acid (EAAs) mediator, and the activity of ATPase in cerebro-cortical synaptosome membrane of rats exposed to deltamethrin. METHODS: Using HPLC to detect EAAs release, and colorimeter method to measure the activities of Na(+)-K(+)-ATPase, Mg(2+)-ATPase, Ca(2+)-ATPase, Ca(2+)-Mg(2+)-ATPase in the cerebro-cortical synaptosomes of ovariectomized rats exposed to deltamethrin (2 x 10(-5)mol/L), and treated with different doses of 17beta estradiol (10(-5), 10(-8), 10(-11) mol/L). Meanwhile, the estrogen receptor (ER) antagonist, tamoxifen, was used to investigate the effect on estradiol. RESULTS: The release of Asp and Glu from the cerebro-cortical synaptosomes was significantly increased by 2 x 10(-5)mol/L deltamethrin exposure at the depolarizing state evoked by 50 mmol/L KCl, while 10(-8), 10(-11) mol/L 17beta estradiol could partly inhibit the effect of deltamethrin on the release of Asp (28.42%, 24.36%, respectively), Glu (21.52%, 14.57%, respectively). The activities of 4 kinds of ATPase were inhibited by 2 x 10(-4) mol/L deltamethrin, and these effects could be blocked by 10(-5) mol/L estradiol, while the activity of Ca(2+)-ATPase was increased by 10(-8), 10(-11) mol/L of estradiol. However, no obvious antagonistic effect of tamoxifen on the function of estradial on EAAs release or the activities of ATPase was found. CONCLUSION: Estradiol showed certain neuroprotective effect on the release of EAAs and the inhibition on ATPase induced by deltamethrin. The effect of estradiol on synaptosomes may indicate the nongenetic mechanism of estradiol.

Animals↗
PubMed2004

[The polymorphism distributions of MICA and MICB microsatellite in Guangdong Han population].

OBJECTIVE: To investigate the genetic polymorphism of microsatellite in the exon 5 of MICA gene and the intron 1 of MICB gene in Guangdong Han population. METHODS: One hundred and six samples of Guangdong Han population were genotyped by polymerase chain reaction and fluorescent technique (6-FAM). Gene frequency, power of discrimination, expected heterozygosity, polymorphism information content and probability of paternity exclusion were calculated. RESULTS: The genotype distributions of MICA and MICB microsatellite met Hardy-Weinberg equilibrium. MICA A5 was the most common allele (0.2877), whereas A4 was the least popular one (0.1321). The genotype distribution frequencies of A5-5.1 (14.15%) and A5-5 (10.38%) are high. MICB CA14 was the most common allele (0.3255), and CA19,28 was the least popular one (0.0047). CA27 was not observed. The genotype distribution frequency of CA14-CA14(14.15%) is high. CONCLUSION: The microsatellite of the exon 5 of MICA gene and the intron 1 of MICB gene could be used as the genetic markers of Chinese population in the studies of anthropology, linkage analysis of genetic disease genes, individual identification and paternity test in forensic medicine.

China↗
PubMed2004

Clinical application of axonal repair technique for treatment of peripheral nerve injury.

OBJECTIVE: To evaluate the efficacy of axonal repair technique for treatment of peripheral nerve injury clinically. METHODS: In 1998, the authors applied axonal repair technique to treat peripheral nerve injuries in 12 patients with 13 nerves. It consists of four steps, ie, stumps of the nerve being soaked in a modified Collins fluid, freezed, trimmed, and coapted with glue, making the injured nerve repaired at the axonal level. RESULTS: The patients were followed up for an average of 13 months. Results showed that in 4 cases of first-stage contralateral C7 transfer, regenerating axons reached to the sternoclavicular joint or axilla at 4 to 7 months, offering the timing for performing the second-stage contralateral C7 transfer. In 5 cases of accessory nerve transferred to the suprascapular nerve, the abduction of the shoulder was 40 degree on average. In the other 3 patients with four different nerves repaired, results were also satisfactory. CONCLUSIONS: This technique is promising in the treatment of peripheral nerve injury.

Adult↗
PubMed2004

[Occupational exposure profiles of polycyclic aromatic hydrocarbons in coke oven workers].

OBJECTIVE: To study the characteristics of occupational exposure of polycyclic aromatic hydrocarbons (PAHs) in coke oven workers. METHODS: Samples were collected individually and PAHs concentration in the ambient air were assayed by high performance liquid chromatography (HPLC) and toxic equivalency factors (TEFs) were introduced to assess the carcinogenic potency. RESULTS: The levels of PAHs occupational exposure in oven workers at topside was higher than at side oven and bottom oven (P < 0.05). Non-carcinogenic PAHs were more than 70% of total PAHs and benzo[a]pyrene accounted for 65.5% approximately 72.4% of total benzo[a]pyrene equivalents. Total occupational exposure level of PAHs in coke oven workers was positively related to the content of benzo[a]pyrene and pyrene, respectively (r(2) = 0.84, r(2) = 0.94, P < 0.05). CONCLUSION: Coke oven workers were exposed to a high level of PAHs which possessed some extent of carcinogenic potency, and benzo[a]pyrene is the chief carcinogenic substance.

Benzo(a)pyrene↗
PubMed2004

[Effects of pyrethroids on dopamine and its metabolites in nigrostriatum of male rats].

OBJECTIVE: To investigate the effects of pyrethroids on nigrostriatal dopaminergic pathways in male rats and its mechanism. METHODS: Different doses of permethrin (PM, 200, 400 mg/kg) and deltamethrin (DM, 6.25, 12.50 mg/kg) in corn oil were administered to rats by gavage once daily for ten days, then the contents of dopamine (DA) and its metabolites, 3, 4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) in the substantial nigra and striatum were analyzed by HPLC-fluorescence detection. RESULTS: The contents of DA in striatum in four administered groups were decreased to a certain extent. DA in 6.25 mg/kg DM group [(6.14 +/- 0.57) microg/g wet weight] was lower than that in control group [(9.46 +/- 1.95) microg/g wet weight], P < 0.05. The turnover rate of DA in 200, 400 mg/kg PM and 6.25, 12.5 mg/kg DM groups increased by 133.33%, 166.67%, 166.67%, 266.67% respectively (P < 0.05 or P < 0.01), however there was no significant difference in DA and DOPAC in substantial nigra between control and administered groups. CONCLUSION: DM may inhibit tyrosine hydroxylase and decrease the level of DA in striatum, and both pyrethroid pesticides may increase the metabolism of dopamine in striatum.

3,4-Dihydroxyphenylacetic Acid↗
PubMed2004

[Effects of deltamethrin on the apoptosis and the expression of caspase-3 in rat neural cells].

OBJECTIVE: To study the effect of deltamethrin on the apoptotic rate and the expression of caspase-3 in rat neural cells. METHODS: Male Wistar rats were randomly divided into 5 groups: control, 5 h, 24 h, 48 h and 5 d exposed groups. Apoptotic rate and the expression of caspase-3 were measured by FACS420 Flow Cytometer; Ac-DEVD-pNa was used as a substrate to detect the activity of caspase-3. RESULTS: Apoptotic rates in 24 h, 48 h and 5 d exposed groups in hippocampus and cerebral cortex [hippocampus: (8.45 +/- 1.02)%, (9.44 +/- 1.14)%, (7.58 +/- 0.75)%; cerebral cortex: (7.90 +/- 0.49)%, (8.01 +/- 0.87)%, (7.97 +/- 0.41)% respectively] were higher than those in the control [hippocampus: (2.97 +/- 0.36)%; cerebral cortex: (3.50 +/- 0.48)%] (P < 0.01); the activity of caspase-3 in 5 h, 24 h and 48 h exposed groups (A(405) nm in hippocampus: 0.389 +/- 0.038, 0.472 +/- 0.041, 0.295 +/- 0.049; A(405) nm in cerebral cortex: 0.321 +/- 0.068, 0.429 +/- 0.077, 0.344 +/- 0.047) and 5 d group of hippocampus (0.246 +/- 0.065) were all higher than those of the control (hippocampus: 0.184 +/- 0.054; cerebral cortex: 0.198 +/- 0.049) (P < 0.05, P < 0.01); the expression of caspase-3 in 5 h, 24 h and 48 h exposed groups increased apparently while 5 d group did not. CONCLUSION: Exposure to high dose of deltamethrin would affect the apoptosis, the activity and expression of caspase-3 in rat neural cells. The increase in caspase-3 activity and expression occurred before the rising of neuronal apoptotic rate may be the upstream event of apoptosis.

Animals↗
PubMed2004

[Two-dimensional electrophoretic separation of subproteomes in adult rat hippocampal subregions after membrane protein enrichment with sequential extraction].

OBJECTIVE: To establish a method for analysis of the subproteomes following membrane protein enrichment, so as to investigate the differences in cytosolic and membrane protein/peptide contents among different hippocampal subregions (CA1, CA3 and dentate gyrus) of rats. METHODS: The hippocampal subregions were isolated by microdissection, and after membrane protein enrichment with protein solubility-based sequential sample extraction, subproteome profiling was accomplished using modified two-dimensional electrophoresis and silver staining method compatible with high-performance mass spectrometry, which displayed cytosolic or membrane proteins/peptides separately. The efficacy of the electrophoresis was evaluated by image analyzing software. RESULTS: The membrane proteins were enriched by 8 folds, and around 30% more spots were shown on the integrated dentate gyrus map than on the conventional map obtained by one-step protein extraction. Such improvement could also be seen in protein mapping of CA1 and CA3 regions. CONCLUSION: When analyzing hippocampal subregions sequential extraction and two-dimensional electrophoresis more effectively separate and display enriched membrane protein/peptides, which may play important roles in such cellular events as signal transduction.

Animals↗
PubMed2004

[The study on the haplotype of MICA and MICB microsatellite locus in Guangzhou Han population].

This study is to investigate genetic polymorphisms and haplotypes of microsatellite locus in the exon 5 of the MICA gene and intron 1 of the MICB gene based on 106 samples of Guangzhou Han Population by polymerase chain reaction and fluorescent technique (6-FAM). The corresponding haplotype frequencies, linkage disequilibria values and relative linkage disequilibria values were estimated based on population data. The results show that the genotype distributions of MICA and MICB microsatellite meet Hardy-Weinberg equilibrium in Guangdong Han population. In total, 5 alleles of MICA microsatellite locus and 14 alleles of MICB microsatellite locus were observed. MICA A5 was the most common allele (0.2877), whereas A4 was the least popular one (0.1321). MICB CA14 was the most common allele (0.3255), and CA19 and CA28 were the least popular ones (0.0047). CA27 was not observed. Twenty-one kinds of MICA-MICB haplotypes occurred at frequencies of more than 1% (linkage disequilibria value>0). The common MICA-MICB haplotypes were A5-CA14 (16.73%) , A5.1- CA18 (8.75%), A4- CA26(3.76%),A9-CA15(3.66%) and A6-CA21(2.61%) (chi(2)>3.84, P<0.05) , and they were strong linkage disequilibria. The polymorphisms and haplotypes distributions of MICA and MICB microsatellite locus in Guangzhou Han population have their own genetic characteristics. The microsatellite locus of the exon5 of the MICA gene and intron 1 of the MICB gene could be used as the genetic markers in the studies of anthropology, linkage analysis of genetic disease genes, individual identification and paternity test in forensic medicine.

Asian People↗
PubMed2004

[Expression of truncated 56 kDa antigen gene of Orientia tsutsugamushi in different vectors].

OBJECTIVE: To construct recombinant plasmids containing the truncated gene of the major surface antigen sta56 of Orientia tsutsugamushi (Ot.) Karp strain for expression antigen in E. coli so as to compare the expression efficiency in different systems. METHODS: From the recombinant plasmid TOPO-sta56 containing sta56 of Orientia tsutsugamushi Karp strain, several truncated genes of sta56 with different length were amplified and subcloned into the expression vectors pPROEX HTb and pET30a. These genes were expressed in E. coli DH5alpha and BL21(DE3) respectively when induced by IPTG. The expressed recombinant proteins were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blot. RESULTS: Six recombinant plasmids containing truncated sta56 genes of different length were constructed as follow: pHTbOt957, pHTbOt498, pHTbOt342 and pETOt957, pETOt498, pETOt342. The recombinant sta56 proteins were highly expressed as 6 x His fusion proteins in E. coli DH5alpha and BL21(DE3) respectively. The fusion proteins showed as different bands of different molecular weight respectively when analyzed with SDS-PAGE. Western blot demonstrated that the recombinant proteins were recognized by the positive serum of Ot. patients. CONCLUSION: The sta56 gene of Orientia tsutsugamushi Karp strain could be highly expressed in E. coli and its expression showed better efficiency in pET30a than in pPROEX HTb. The recombinant sta56 antigen with immunoreactivity could be used as diagnostic reagent for Ot. infection.

Animals↗
PubMed2003

Brillouin scattering spectrum in photonic crystal fiber with a partially germanium-doped core.

The Brillouin scattering spectrum in a photonic crystal fiber (PCF) with a partially Ge-doped core is measured with a pump-probe technique at a wavelength of 1320 nm. One main peak and four subpeaks are observed. The main peak has a Lorentzian shape with the bandwidth deltanuB = 66 MHz. Its intensity is six times higher than that from a standard single-mode fiber measured under the same conditions, which is consistent with the ratio of (1/Aeff(PCF))/(1/Aeff(SMF)), where Aeff is the effective area of the fibers. The temperature coefficient for the main peak is 0.96 MHz/degrees C. We believe that the subpeaks are caused by an interaction between light-wave and guided modes of longitudinal acoustic waves in the graded-Ge-doped region, the silica region, and the microstructured cladding. An analysis of the guiding and antiguiding properties of the PCF for acoustic waves is presented.

Journal Article↗
PubMed2003

Effect of the finite extinction ratio of an electro-optic modulator on the performance of distributed probe-pump Brillouin sensor systems.

The effect of the finite extinction ratio of an electro-optic modulator (EOM) on the Brillouin frequency measurement of a distributed Brillouin-based fiber optic sensor is studied. An EOM with a finite extinction ratio limits the application of Brillouin optical time domain analysis in a distributed Brillouin-based fiber optic sensor. This results in confusion in specifying the location of the strained region and in error in detecting the Brillouin frequency and hence in strain and temperature measurement.

Journal Article↗
PubMed2003

Protein-DNA interaction mapping using genomic tiling path microarrays in Drosophila.

We demonstrate the use of a chromosomal walk (or "tiling path") printed as DNA microarrays for mapping protein-DNA interactions across large regions of contiguous genomic DNA in Drosophila melanogaster. Microarrays were constructed with genomic DNA fragments 430-920 bp in length, covering 2.9 million base pairs of the Adh-cactus region of chromosome 2 and 85,000 base pairs of the 82F region of chromosome 3. We performed DNA localization mapping for the heterochromatin protein HP1 and for the sequence-specific GAGA transcription factor, producing a comprehensive, high-resolution map of in vivo protein-DNA interactions throughout these regions of the Drosophila genome.

Amino Acid Motifs↗
PubMed2003

Adsorption of CF4 on the internal and external surfaces of opened single-walled carbon nanotubes: a vibrational spectroscopy study.

Infrared spectroscopy has been used to make the first experimental discrimination between molecules bound by physisorption on the exterior surface of carbon single-walled nanotubes (SWNTs) and molecules bound in the interior. In addition, the selective displacement of the internally bound molecules has been observed as a second adsorbate is added. SWNTs were opened by oxidative treatment with O(3) at room temperature, followed by heating in a vacuum to 873 K. It was found that, at 133 K and 0.033 Torr, CF(4) adsorbs on closed SWNTs, exhibiting its nu(3) asymmetric stretching mode at 1267 cm(-1) (red shift relative to the gas phase, 15 cm(-1)). Adsorption on the nanotube exterior is accompanied by adsorption in the interior in the case of opened SWNTs. Internally bound CF(4) exhibits its nu(3) mode at 1247 cm(-1) (red shift relative to the gas phase, 35 cm(-1)). It was shown that, at 133 K, Xe preferentially displaces internally bound CF(4) species, and this counterintuitive observation was confirmed by molecular simulations. The confinement of CF(4) inside (10,10) single-walled carbon nanotubes does not result in the production of lattice modes that are observed in large 3D ensembles of CF(4).

Journal Article↗
PubMed2003

Study on the complex site of L-tyrosine with rare-earth element Eu3+.

Amino acids are the primary units of proteins and play an important role in human life. The coordinate of L-tyrosine with rare-earth element Eu(3+) was investigated in solution by ultraviolet and was proved the molar ratio is 1:2. Then the solid complex was prepared by coprecipitation method. The complex was characterized by several analytical techniques, including Fourier Transform Infrared Spectroscopy, Differential Scanning Calorimetry, Scanning Electron Microscopy, 1H-NMR and 13C-NMR. Based on these data, we found that pentatomic ring was formed by binding with N atom in group of amino (-NH(2)) and O atom in group of carboxyl (-COOH).

Binding Sites↗