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Peng Chen

Publications and source records attributed to Peng Chen.

72 records · Page 4Linked to original sources
PubMed2003

The C-terminal portion of the nucleocapsid protein demonstrates SARS-CoV antigenicity.

In order to develop clinical diagnostic tools for rapid detection of the SARS-CoV (severe acute respiratory syndrome-associated coronavirus) and to identify candidate proteins for vaccine development, the C-terminal portion of the nucleocapsid (NC) gene was amplified using RT-PCR from the SARS-CoV genome, cloned into a yeast expression vector (pEGH), and expressed as a glutathione S-transferase (GST) and Hisx6 double-tagged fusion protein under the control of an inducible promoter. Western analysis on the purified protein confirmed the expression and purification of the NC fusion proteins from yeast. To determine its antigenicity, the fusion protein was challenged with serum samples from SARS patients and normal controls. The NC fusion protein demonstrated high antigenicity with high specificity, and therefore, it should have great potential in designing clinical diagnostic tools and provide useful information for vaccine development.

Antigens, Viral↗
PubMed2003

3,4-Methylenedioxymethamphetamine (MDMA) abuse may cause oxidative stress and potential free radical damage.

OBJECTIVE: To investigate whether 3,4-methylenedioxymethamphetamine abuse (MDMA abuse) may cause oxidative stress and potential free radical damage in the bodies of MDMA abusers (MA), and to explore the mechanisms by which MDMA abuse may be causing oxidative stress. METHODS: One hundred and twenty MA and 120 healthy volunteers (HV) were enrolled in a random control study design, in which the level of lipoperoxide (LPO) in erythrocytes, and the levels of Vitamin C (VC), Vitamin E (VE) and beta-carotene (beta-CAR) in plasma as well as the activities of superoxide dismutase (SOD) and catalase (CAT) in erythrocytes were determined by spectrophotometric methods. RESULTS: Compared with the average values of the above biochemical parameters in the HV group, the average value of LPO in erythrocytes in the MA group was significantly increased (P < 0.0001), while the average values of VC, VE and beta-CAR in plasma as well as those of SOD and CAT in erythrocytes in the MA group were significantly decreased (P < 0.0001). The analysis of bivariate correlations suggested that with the increase of the MDMA abuse dose and the MDMA abuse duration, the level of LPO in erythrocytes in the MA was increased (P < 0.0001), while the levels of VC, VE and beta-CAR in plasma as well as the activities of SOD and CAT in erythrocytes in the MA were decreased (P < 0.0001). CONCLUSION: The findings in this study suggest that MDMA abuse may cause oxidative stress and potential free radical damage to MA.

Adolescent↗
PubMed2003

[Effect of PP60c-Src on angiotensin II-induced signal transduction in rat vascular smooth muscle cells].

OBJECTIVE: To further clarify the mechanism of Ang II-induced intracellular signal transduction in vascular smooth muscle cells(VSMCs) proliferation by observing the effect of c-Src on Ang II-mediated MAPK activation and c-fos protein expressions in rat VSMCs. METHODS: Aortic VSMCs from SD rats were cultured primarily and subcultured, which were transfected with anti-sense c-Src oligodeoxynucleotides(ODNs) wrapped with lipofectin to inhibit c-Src activity and protein production. Untransfected VSMCs were used as control, to observe the role of Ang II stimulation in MAPK activation and c-fos protein expression in VSMC. Protein immunoprecipitation and kinase phosphorylation were employed to measure c-Src kinase activity; MAPK kinase activity was assessed by the phosphorylation rate of the substrate MBP(Myelin Basic Protein); Western blot was used to assess the protein expression of c-Src and c-fos. RESULTS: c-Src protein expressions in VSMC, which were transfected with different concentrations of anti-sense c-Src ODNs, were significantly decreased in a negative dose-effect manner (0.2 microm, 0.5 microm, 1.0 microm and 2.0 microm were 68.2%, 34.7%, 30.3% and 15.8% respectively compared with control). c-Src kinase activity was also obviously inhibited. Following stimulation of Ang II on VSMC transfected with anti-sense c-Src ODNs, the increase of c-Src activity was only 8.7% of control,the activity of MAPK only 1.6% compared with control, and the increase in c-fos protein expression 30.3% as control. CONCLUSION: Ang II can induce c-Src activation and intracellular signal transduction in VSMC which depend on c-Src activation, indicating that c-Src is a pivotal signal factor in VSMC proliferation.

Angiotensin II↗
PubMed2003

[Spatial heterogeneity of vegetation and soil characteristics in oasis-desert ecotone].

The spatial distribution of bio- and abiotic factors in ecosystem has the features of spatial heterogeneity in general, and spatial heterogeneity is important in the function and process of ecosystem at a variety of scales. In this paper, semivariance theory and methods were used to study the degree, composition, scale and pattern of spatial heterogeneity of vegetation coverage and soil environment factors, and their relationships in the Fukang oasis-desert ecotone of Xinjiang. With block kriging in the studied area of sampling, the spatial pattern of each factor was expressed in three dimensions as well. The results indicated that except the little spatial autocorrelation of salt salinity, there existed a spatial autocorrelation above mean of the other factors, and the spatial variation was mainly limited to smaller scales. The vegetation coverage, for which auto-correlated spatial heterogeneity was a main component, had a high degree of spatial heterogeneity with obvious spatial pattern at the scale of 3 km. From the perspective of spatial distributions, there existed a remarkable difference between soil holard and soil pH value in the studied area. Besides this, the higher value areas interleaved with the lower ones, significant positive correlations were observed between herbage coverage and soil factors (surface SH and SPH), and shrub coverage depended on the deep SH. The difference of spatial heterogeneity and pattern between SC and HC indicated the different ecological function and process in the ecosystem.

Desert Climate↗
PubMed2003

[Meta-analysis on the association of AGT M235T polymorphism and essential hypertension in Chinese population].

OBJECTIVE: To study on the association of M235T polymorphism of the angiotensinogen gene extron 2 (AGT/M235T) and essential hypertension (EH) in Chinese population by means of Meta-analysis. METHODS: Odds ratios (OR) of AGT M235T genotype distributions in EH patients against healthy controls were analyzed. All the relevant studies were identified, poor-qualified studies eliminated, and the risk of publication bias excluded. The Meta-analysis software, REVMAN4.1, was applied for investigating heterogeneity among individual studies and summarizing the effects across studies. RESULTS: A total of 853 cases and 835 controls from 10 studies were included. No heterogeneity among the studies was noticed. The frequencies of the AGT TT, MT and MM genotypes were 65%, 30%, and 4.9% in cases and 50.6%, 41.8% and 7.5% in controls respectively. The frequencies of the AGT T allele were 80% in cases and 72% in controls. The pooled OR (with 95% CI) of TT vs MT + MM was 1.76 (1.44 - 2.16) (P < 0.000 01) with T vs M 1.54 (1.31 - 1.81). The pooled OR of MM vs MT + TT was 0.67 (0.45 - 1.00) (P = 0.05). CONCLUSION: In Chinese population (mainly the Hans), TT genotype might be associated with the increased risk of EH while MM genotype be associated with low risk of EH.

Alleles↗
PubMed2002

A highly Ca2+-sensitive pool of vesicles is regulated by protein kinase C in adrenal chromaffin cells.

We have used flash photolysis of caged Ca2+ and membrane capacitance measurements to probe exocytosis in chromaffin cells at low concentrations of intracellular Ca2+ ([Ca2+]i) (<10 microM). We observed a small pool of granules that is more sensitive to [Ca2+]i than the previously described "readily releasable pool." Upon activation of PKC, this "highly Ca2+-sensitive pool" is enhanced in size to a greater extent than the readily releasable pool but is eliminated upon expression of a C-terminal deletion mutant (Delta9) of synaptosome-associated protein of 25 kDa (SNAP-25). Thus, in chromaffin cells, PKC enhances exocytosis both by increasing the number of readily releasable vesicles and by shifting vesicles to a highly Ca2+-sensitive state, enabling exocytosis at sites relatively distant from Ca2+ channels.

Animals↗
PubMed2002

Spectroscopic and electronic structure studies of the mu(4)-sulfide bridged tetranuclear Cu(Z) cluster in N(2)O reductase: molecular insight into the catalytic mechanism.

Spectroscopic methods combined with density functional calculations are used to develop a detailed bonding description of the mu(4)-sulfide bridged tetranuclear Cu(Z) cluster in N(2)O reductase. The ground state of Cu(Z) has the 1Cu(II)/3Cu(I) configuration. The single electron hole dominantly resides on one Cu atom (Cu(I)) and partially delocalizes onto a second Cu atom (Cu(II)) via a Cu(I)-S-Cu(II) sigma/sigma superexchange pathway which is manifested by a Cu(II) --> Cu(I) intervalence transfer transition in absorption. The observed excited-state spectral features of Cu(Z) are dominated by the S --> Cu(I) charge-transfer transitions and Cu(I) based d-d transitions. The intensity pattern of individual S --> Cu(I) charge-transfer transitions reflects different bonding interactions of the sulfur valence orbitals with the four Cu's in the Cu(Z) cluster, which are consistent with the individual Cu-S force constants obtained from a normal coordinate analysis of the Cu(Z) resonance Raman frequencies and profiles. The Cu(I) d orbital splitting pattern correlates with its distorted T-shaped ligand field geometry and accounts for the observed low g( parallel ) value of Cu(Z) in EPR. The dominantly localized electronic structure description of the Cu(Z) site results from interactions of Cu(II) with the two additional Cu's of the cluster (Cu(III)/Cu(IV)), where the Cu-Cu electrostatic interactions lead to hole localization with no metal-metal bonding. The substrate binding edge of Cu(Z) has a dominantly oxidized Cu(I) and a dominantly reduced Cu(IV). The electronic structure description of Cu(Z) provides a strategy to overcome the reaction barrier of N(2)O reduction at this Cu(I)/Cu(IV) edge by simultaneous two-electron transfer to N(2)O in a bridged binding mode. One electron can be donated directly from Cu(IV) and the other from Cu(II) through the Cu(II)-S-Cu(I) sigma/sigma superexchange pathway. A frontier orbital scheme provides molecular insight into the catalytic mechanism of N(2)O reduction by the Cu(Z) cluster.

Catalysis↗
PubMed2002

Inosine induces axonal rewiring and improves behavioral outcome after stroke.

Cerebral infarct (stroke) often causes devastating and irreversible losses of function, in part because of the brain's limited capacity for anatomical reorganization. The purine nucleoside inosine has previously been shown to induce neurons to express a set of growth-associated proteins and to extend axons in culture and in vivo. We show here that in adult rats with unilateral cortical infarcts, inosine stimulated neurons on the undamaged side of the brain to extend new projections to denervated areas of the midbrain and spinal cord. This growth was paralleled by improved performance on several behavioral measures.

Animals↗
PubMed2002

A cytosolic tRNA with an unmodified adenosine in the wobble position reads a codon ending with the non-complementary nucleoside cytidine.

Out of more than 500 sequenced cytosolic tRNAs, there is only one with an unmodified adenosine in the wobble position (position 34). The reason for this rare occurrence of A34 is that it is mostly deaminated to inosine-34 (I34). I34 is a common constituent in the wobble position of tRNAs and has a decoding capacity different from that of A34. We have isolated a mutant (proL207) of Salmonella typhimurium, in which the wobble nucleoside G34 has been replaced by an unmodified A in tRNA(Pro)(GGG), which is the only tRNA that normally reads the CCC codon. Thus, this mutant apparently has no tRNA that is considered cognate for the codon CCC. Despite this, the mutant grows normally. As expected, Pro-tRNA selection at the CCC codon in the A-site in a mutant deleted for the proL gene, which encodes the tRNA(Pro)(GGG), was severely reduced. However, in comparison this rate of selection was only slightly reduced in the proL207 mutant with its A34 containing tRNA(Pro)(AGG) suggesting that this tRNA reads CCC. Moreover, measurements of the interference by a tRNA residing in the P-site on the apparent termination efficiency at the A-site indicated that indeed the A34 containing tRNA reads the CCC codon. We conclude that A34 in a cytosolic tRNA is not detrimental to the cell and that the mutant tRNA(Pro)(AGG) is able to read the CCC codon like its wild-type counterpart tRNA(Pro)(GGG). We suggest that the decoding of the CCC codon by a 5'-AGG-3' anticodon occurs by a wobble base-pair between a protonated A34 and a C in the mRNA.

Adenosine↗
PubMed2002

Electronic structure description of the mu(4)-sulfide bridged tetranuclear Cu(Z) center in N(2)O reductase.

Spectroscopy coupled with density functional calculations has been used to define the spin state, oxidation states, spin distribution, and ground state wave function of the mu4-sulfide bridged tetranuclear CuZ cluster of nitrous oxide reductase. Initial insight into the electronic contribution to N2O reduction is developed, which involves a sigma superexchange pathway through the bridging sulfide.

Circular Dichroism↗
PubMed2002

Frontier molecular orbital analysis of Cu(n)-O(2) reactivity.

Frontier molecular orbital (FMO) theory coupled with density functional calculations has been applied to investigate the chemical reactivity of three key bioinorganic Cu(n)-O(2) complexes, the mononuclear end-on hydroperoxo-Cu(II), the side-on bridged mu-eta(2):eta(2)-O(2)(2-) Cu(II)(2) dimer and the bis-mu-oxo Cu(III)(2) dimer. Two acceptor orbitals (sigma* and pi*) of each complex and two types of donating substrates (sigma-substrate, phosphine; pi-substrate, alkylbenzene) are considered in the electrophilic attack mechanism. The angular dependences of different reaction pathways are determined using FMO theory and the angular overlap model. Including steric effects, the sigma*/sigma and pi*/pi pathways are found more reactive than the corresponding cross sigma*/pi and pi*/sigma pathways which have poor donor-acceptor orbital overlaps in the sterically constrained substrate access region.

Copper↗
PubMed2002

Sequential or simultaneous cyclophotocoagulation and glaucoma drainage implant for refractory glaucoma.

PURPOSE: To describe the outcomes of combining cyclophotocoagulation and tube-shunt glaucoma drainage implants, either sequentially or simultaneously, for the control of refractory glaucomas. PATIENTS AND METHODS: A retrospective review was conducted of all patients that had been treated at our institute with both cyclophotocoagulation and a tube-shunt glaucoma drainage implant in the same eye between January 1996 and June 2000. Preoperative and postoperative intraocular pressure, number of glaucoma medications, vision, and complications data were collected for each eye. RESULTS: A total of 10 eyes of 9 patients met the study criteria. The minimum follow-up period after the last surgery was 15 months. Intraocular pressures were reduced from 28.5 +/- 7.2 mm Hg preoperatively to 13.9 +/- 5.4 mm Hg postoperatively at 15 months (P < 0.000, n = 9). Medications were reduced from 2.7 +/- 1.2 preoperatively to 0.3 +/- 0.5 postoperatively at 15 months (P < 0.000, n = 9). Of the eight eyes with measurable Snellen acuity, postoperative vision decreased two or more lines in five eyes (63%). Complications included transient hypotony (one eye), transient serous choroidal detachment (two eyes), cystoid macular edema (two eyes), corneal edema (three eyes), and panuveitis with chronic hypotony and traction retinal detachment (one eye). CONCLUSIONS: Combining cyclophotocoagulation with tube-shunt glaucoma drainage implants can effectively reduce intraocular pressure and number of glaucoma medications needed to achieve target intraocular pressure goals. Further study is needed to determine the safety of this combined approach compared with other available options to manage refractory glaucomas.

Adolescent↗
PubMed2002

[Correlation of autoantibodies against oxidized low density lipoprotein and its immune complex with coronary artery disease]

OBJECTIVE: To evaluate the relationship between autoantibodies against oxidized low density lipoprotein(ox- LDL), immune complex and coronary artery disease(CAD). METHODS: The levels of autoantibodies against ox-LDL and immune complex were assayed by ELISA, the content of ox-LDL and lipid levels were also measured. The serum samples were taken from 61 patients with CAD, 116 patients with essential hypertension(EH) and 123 healthy individuals as control. RESULTS: The patients with CAD had significantly higher levels of anti-ox-LDL IgG[21.48(17.58 approximate, equals 29.01)U/L], anti-ox-LDL IgM4.71[3.88 approximate, equals 7.06)U/L] and ox-LDL[0.87(0.44 approximate, equals 1.08) mg/L] than EH group[15.93(11.12 approximate, equals 22.26) U/L 2.54(1.17 approximate, equals 5.05) U/L 0.32(0.16 approximate, equals 0.61) mg/L]and healthy control group[11.12(4.70 approximate, equals 16.57)U/L 1.61(0.60 approximate, equals 3.03)U/L 0.23(0.12 approximate, equals 0.36)mg/L], P<0.001. However, the serum ox-LDL immune complex[2.63(1.69 approximate, equals 5.90)U/L] was significantly lower in CAD than that in EH group[15.71(6.25 approximate, equals 28.74)U/L] and that in healthy control group[12.54(8.28 approximate, equals 23.90)U/L], P<0.001. There were discrepancies in the association between ox-LDL and autoantibodies against ox-LDL among different groups. CONCLUSION: The changes of autoantibodies against ox-LDL and immune complex in patients with CAD may be related to the role of ox-LDL and autoantibodies against ox-LDL in the process of coronary atherosclerosis.

Journal Article↗
PubMed2002

Dynamics of cAMP/cGMP in patients under a stress state.

OBJECTIVE: To investigate the dynamics of plasma cAMP/cGMP in patients during cardiac surgery, and its relationship to traumatic stress. METHODS: Sixteen patients, aged 19.31 years+/-10.4 years, who underwent an open heart operation with cardiopulmonary bypass (CPB) and hypothermia were served as subjects. The arterial plasma concentrations of cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) were measured by radioimmunoassay 2 hours before operation, after heparinization, 20 minutes following CPB, at the end of the operation, and 24 and 72 hours postoperatively, respectively. The patients' preoperative blood samples were heparinized and the venous blood samples of 30 healthy blood donors were taken to measure the levels of cAMP and cGMP as heparin and normal controls separately. RESULTS: There were no statistical difference among the heparin control, preoperative level and normal control. The peak values of cAMP and cGMP occurred during CPB and plasma cAMP levels changed synchronously with intensities of operative stimulus to human body. However cGMP level was mainly related to the operative stimulus to the heart and CPB. The cAMP value was positively correlated with the cGMP value (r=0.6313, P<0.001). CONCLUSIONS: Dynamic variation of plasma cyclic ribonucleotide can be considered as a reference parameter for intensity of traumatic stress.

Adolescent↗
PubMed2002

Oxidative stress in patients with acute coxsackie virus myocarditis.

OBJECTIVE: To study the state of oxidative stress in patients with acute coxsackie virus myocarditis (ACM), and to investigate the pathological chain reactions of a series of free radicals and oxidative and lipoperoxidative damages in their bodies. METHODS: Eighty ACM patients and 80 healthy adult volunteers (HAV) were enrolled in a case-control study, in which concentrations of nitric oxide (NO) in plasma, lipoperoxides (LPO) in plasma and LPO in erythrocytes (RBC), vitamin C (VC), vitamin E (VE) and beta-carotene (beta-CAR) in plasma as well as activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) in RBC were determined by using spectrophotometric assays. RESULTS: Compared with the average values (AV) of the above biochemical parameters (BP) in the HAV group, the AV of NO in plasma, and LPO in plasma and RBC in the ACM group were significantly increased (P = 0.0001), while the AV of VC, VE, beta-CAR, SOD, CAT and GSH-Px in the ACM group were significantly decreased (P = 0.0001). The values of the above BP were used to estimate the relative risk ratio (RR) between the ACM group and the HAV group; the RR and its 95% confidence interval were 12.467 (5.745-27.051), 4.333 (2.126-8.834), 6.517 (3.225-13.618), 3.310 (1.598-6.858), 31.000 (12.611-76.201), 4.663 (2.228-9.759), 11.769 (5.440-25.462), 3.043 (1.486-6.229) and 6.594 (3.045-14.281) respectively, and their P levels ranged from 0.002 to 0.0001. The results were as follows: D = 22.143 - 0.017SOD + 0.008NO + 0.244LPO in RBC, Eigenvalue = 13.659, Canonical correlation = 0.965, Wilks' lambda = 0.068, chi 2 = 420.212, P = 0.0001. The correct rate of discrimination to the ACM group and to the HAV group was 87.5% and 95.0%, respectively, and 91.3% of originally grouped cases was correctly classified. CONCLUSION: The findings in this study suggested that the oxidative stress in bodies of ACM patients was severely aggravated, and marked high oxidative constituents and low antioxidants and antioxidases in the human body might increase the relative risk of inducing acute coxsackie virus myocarditis, and measuring the values of NO in plasma, SOD and LPO in RBC might increase the correct rates of discriminatory analysis of the ACM.

Adolescent↗
PubMed2001

Oxygen Binding, Activation, and Reduction to Water by Copper Proteins.

Copper active sites play a major role in biological and abiological dioxygen activation. Oxygen intermediates have been studied in detail for the proteins and enzymes involved in reversible O(2) binding (hemocyanin), activation (tyrosinase), and four-electron reduction to water (multicopper oxidases). These oxygen intermediates exhibit unique spectroscopic features indicative of new geometric and electronic structures involved in oxygen activation. The spectroscopic and quantum-mechanical study of these intermediates has defined geometric- and electronic-structure/function correlations, and developed detailed reaction coordinates for the reversible binding of O(2), hydroxylation, and H-atom abstraction from different substrates, and the reductive cleavage of the O-O bond in the formation water.

Journal Article↗
PubMed2000

[Study on Methylation of p15(INK4B) Gene in Acute Myeloid Leukemia and Chronic Myeloid Leukemia]

In order to explore the role of p15(INK4B) gene with highly methylated CpG island in the pathogenesis of leukemia, the expression levels of p15(INK4B) gene was detected in patients with AML and CML. Methylation-specific PCR (MSP) assay was employed in the experiments. The methylation incidence was 83.9% (26/31) in AML and 0% (0/28) in CML. The results showed that methylation of p15(INK4B) gene was the one of the major ways for inactivation of the gene, and the methylation could be appeared in clinical development of the disease and patients condition worsened. Methylation of p15(INK4B) did not occur and its function probably is normal in CML.

Journal Article↗