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Biomedical subjects

Peng Liu

Publications and source records attributed to Peng Liu.

At least 73 records · Page 4Linked to original sources
PubMed2005

Differential regulation of cadherin expression by osteotropic hormones and growth factors in vitro in human osteoprogenitor cells.

AIM: To examine if cadherins are expressed constitutively in human bone marrow stromal cells (hBMSC) and investigate the regulation of cadherin expression by various osteotropic hormones and local factors. METHODS: Cadherin expression was examined in first passaged (secondary) hBMSC as well as in the conditionally-immortalized human osteoprogenitor cell line (hOP-7). Using a monoclonal antibody (MoAb C-1821) to a cytoplasmic domain common to all known cadherins (pan-cadherin MoAb), cadherins were immunolocalized in first passaged hBMSC as well as in hOP-7 cells. In addition, intense immunostaining for cadherin expression was associated with alkaline phosphatase (ALP) in nodules formed in the high density cultures of hOP-7 cells. Human E-cadherin (HECD) was specifically detected by Western blotting in extracts of untreated hBMSC using an anti-HECD MoAb 004FD. RESULTS: Differential regulation of cadherin expression by various osteotropic hormones and local factors (parathyroid hormone, dexamethasone, estradiol, prostaglandin E2, basic fibroblast growth factor, and tumor necrosis factor-beta) was also observed. In addition, blocking cadherins with the MoAb C-1821 increased basal ALP activity and had an additive effect on 1, 25(OH) 2D3-induced ALP activity. CONCLUSION: Cadherins are expressed in human osteoprogenitor cells and are involved in the osteogenic differentiation. The differential modulation of cadherin expression by osteotropic agents indicates that these agents may regulate osteoprogenitor cells through different cadherins and these cadherins may play different roles.

Alkaline Phosphatase↗
PubMed2005

Surface-initiated ATRP of HEA from nanocrystal alpha-Fe2O3 under ultrasonic irradiation.

Core/shell poly(beta-hydroethyl acrylate) (PHEA) encapsulated nanocrystal alpha-Fe2O3 nanospheres (Fe2O3@PHEA) were successfully prepared by the surface-initiated atom transfer radical polymerization (SI-ATRP) of beta-hydroethyl acrylate (HEA), a functional monomer, from the surfaces of the nanocrystal Fe2O3 modified with bromo-acetamide groups with the catalysts of 1,10-phenanthroline and Cu(I)Br under ultrasonic irradiation at room temperature in water. The products, Fe2O3@PHEA, were characterized by elemental analysis (EA), FT-IR, XRD, XPS and TEM. The percentage of grafting (PG%) of 38.95% and the conversion of HEA (C%) of 14.29% at room temperature for 6 h with ultrasonic irradiation were higher than the 22.41% and 8.22%, respectively, found for samples prepared by electromagnetic stirring. This demonstrated that the ultrasonic irradiation improves the SI-ATRP of HEA.

Acrylates↗
PubMed2005

[Heteroplasmy: a common phenomenon of mitochondrial genome mutations in human tumor tissues].

To explore the status of heteroplasmy and homoplasmy of Mitochondrial DNA somatic mutations in different tumors. DNA from 149 tumors and corresponding normal tissues were extracted and entire mitochondrial genome was amplified using 32 pairs of overlapping primers. The somatic mutations were screened by temporal temperature gradient gel electrophoresis and their heteroplasmic statute were identified by sequencing. The results showed that the incidence rate of heteroplasmy of mitochondrial DNA somatic mutations varies in different tumors. There is a high rate of heteroplasmic mutation in oral cancer (65%) and esophageal cancer (64%), followed by breast cancer (45%). The frequency of four transfer types is Hm (homoplasmy)-->Hm (heteroplasmy) > Hm-->Ht > Ht-->Hm > Ht-->Ht. The main transfer forms of transition and transversion mutations are Hm-->Hm and Hm-->Ht respectively. Heteroplasmy is a common phenomenon in mitochondrial DNA somatic mutations of human tumors.

Breast Neoplasms↗
PubMed2005

[Study on the genotoxicity of exhausts of diesel engine with ethanol-diesel blending fuel].

OBJECTIVE: To study the genotoxicity of components of diesel engine exhausts with ethanol-diesel blending fuel. To provide scientific arguments to find more economical and less polluted fuels. METHODS: Ames test, comet assay and GC-MS technique were used to test the genotoxicity and 16 kinds of PAHs on diesel engine exhausts with different proportions of ethanol (E0, E5, E10, E20). RESULTS: Both Ames test and comet assay were positive. It shows that diesel engine exhausts can lead to mutation and DNA damage, especially in pure diesel oil. But the content of 16 kinds of PAHs and DNA damage level decreased in exhausts of E5. With the increase of ethanol proportion in diesel oil, the content of 16 kinds of PAHs and DNA damage level increased. CONCLUSION: Compared with pure diesel oil and high proportion of ethanol fuel, E5 can reduce the genotoxicity and the brake specific exhausts of PAHs.

Air Pollutants↗
PubMed2005

[Treatment effect of DICE regimen on patients with relapsed or refractory intermediate and high grade non-Hodgkin's lymphoma].

BACKGROUND & OBJECTIVE: So far, there is still no standard salvage regimen for relapsed or refractory non-Hodgkin's lymphoma (NHL). The response rates (RR) of NHL patients received common salvage regimens, such as DICE, ESHAP, MINE, and EPOCH, are only 30%-70%. This study was to evaluate the efficacy and safety of DICE regimen, as a salvage regimen, in treating patients with relapsed or refractory intermediate and high grade NHL. METHODS: Thirty-five patients with relapsed or refractory intermediate and high grade NHL, who had been pretreated with chemotherapy dominated by CHOP or CHOP-like regimen with a median of 6 cycles (ranged 2-12 cycles), were salvaged by DICE regimen from Jun. 1999 to Jan. 2004. Of the 35 patients, 14 were T-cell original, and 21 were B-cell original. RESULTS: The 35 patients received DICE regimen with a median of 4 cycles (ranged 2-7 cycles). All patients were assessable in the efficacy and adverse events. The total RR was 74.3% with complete response (CR) rate of 31.4%, median response time (MST) of 4 months (ranged 1-30 months), median time to failure (TTF) of 7 months (ranged 2-34 months),median survival time (MST) of 14 months (ranged 3-51 months), and 2-year survival rate of 33.3%. The RRs of T-cell and B-cell NHL were 85.7% and 66.7%. The CR rate was higher in T-cells NHL than in B-cell NHL (50.0% vs. 19.0%, P=0.073). Elevated serum lactate dehydrogenase (LDH) and bulky disease were high risk factors of the efficacy of DICE regimen (P < 0.05). The response to DICE reginmen was an independent prognostic factor of patients with relapsed or refractory NHL (P = 0.001). The major toxicity was myelosuppression. Incidences of neutropenia and thrombocytopenia of grade III-IV were 71.4% and 8.6%. CONCLUSIONS: DICE regimen is a safe and effective salvage regimen for the patients with relapsed or refractory intermediate and high grade advanced NHL. Elevated serum LDH and bulky disease are the adverse prognostic factors. The response to DICE regimen may directly influence survival time of patients with relapsed or refractory NHL.

Adolescent↗
PubMed2005

[Effects of aluminum stress on photosynthetic characters of soybean].

With three soybean (Glycine max) varieties Zhechun No. 2, Zhechun No. 3 and 9703 as test materials, this paper studied the effects of different aluminum (Al) concentration on their photosynthetic characters. The results showed that the leaf chlorophyll content decreased by 5%-35% when Al concentration increased. Al also affected various physiological functions, e. g., stomatal resistance increased by 10%-35%, stomatal conductance decreased by 10%-40%, photosynthetic and transpiration rate decreased by 5%-40% and 20%-50%, respectively, and water utilization efficiency decreased by 15%-50%. Al stress could inhibit the photosynthesis of soybean leaves, and the inhibition was more serious in vegetative than in reproductive growth period. In addition, three test soybean varieties had definite genetic difference in response to Al toxicity.

Aluminum↗
PubMed2005

[Effect of alcohol on brain mitochondria development of mouse embryos].

OBJECTIVE: To probe the effect of alcohol consumption on brain mitochondria development of mouse embryos. METHODS: Pregnant mice were given alcohol intragastrically from pregnant day (PD) 6 - 5. On PD 18, embryos were dissected out and the brain mitochondria were extracted. Then mitochondria membrane potential, activities of mitochondria respiratory chain complex I, IV and ATPase, and ATP content were measured in vitro. RESULTS: The ratio of fetal brain/body weight decreased as the maternal alcohol dosage increasing. An increased proportion of immature mitochondria, from 18 percent to 34 percent, was detected by flow cytometry. Reduced activities of respiratory chain complexes I and IV were found in 3.0 g/kg/day (91.7% and 87.9% respectively) and 6.0 g/kg/day alcohol exposure groups (72.4% and 69.7% respectively). Only 6.0 g/kg/day ethanol exposure group showed significantly reduced activity (80.3% of control) of ATPase. ATP contents in the fetal brain mitochondria of 3.0 g/kg/day and 6.0 g/kg/day maternal alcohol exposure groups were significantly less than that of control, implying an impaired mechanism of ATP synthesis and/ or uptake. CONCLUSION: Alcohol consumption during pregnancy can affect embryo brain mitochondria development, which may be related to the neural tube defects induced by alcohol.

Animals↗
PubMed2005

Pathological study of rabbits' femoral arteries subjected to gunshot wounds combining with seawater immersion.

OBJECTIVE: To investigate pathological characteristics of gunshot wounds concomitant seawater immersion in rabbits' femoral arteries. METHODS: Thirty rabbits were divided randomly into 3 groups: simple gunshot-wound group (Group I, n = 10), gunshot wound with seawater immersion for 30 mins (Group II, n = 10), and 60 mins group (Group III, n = 10). Femoral arteries were impacted by 0.38 g steel spheres fired with a 7.62 mm rifle. After being wounded, rabbits in Groups II and III were immersed in seawater for 30 or 60 mins, but those in Group I were not. At 2, 4, 6, 8, 12 hours following injury, a 40 mm segment of the artery on each side of the gunshot point were excised and observed by light and electron microscopy. RESULTS: The patterns of arterial injuries were mainly contusion and transection. Completely transected artery was classified as primary-wound-tract area, contused area and shocked area. Compared with those in Group I, the primary-wound-tract and contused areas in Group II manifested obvious swelling in the arterial wall especially at the outside 2/3 of the media. Vacuolar structures were often seen in smooth muscle cells of the media. Intercellular space among the smooth muscle cells were filled with homogeneous acidophilic substances. Deep rugae among endothelial cells flattened or rugal folds lost their longitudinal orientation, and marked fibrin and platelet deposition were noticed. No significant difference was detected between Group II and III. The pathological changes in the shocked area were similar in 3 groups. CONCLUSIONS: For gunshot wounds concomitant seawater immersion in rabbits' femoral arteries, there was a marked swelling of cells and intercellular space in primary-wound-tract area and contusion area. The influence of these pathological changes on surgical reparation deservers further study.

Animals↗
PubMed2005

[Effects of ginsenoside Rb1 on mouse embryonic development in vitro].

OBJECTIVE: To evaluate the developmental toxicity of ginsenoside Rb1 and the potential mechanism of it in vitro. METHODS: Whole embryo culture system was used in this research. Embryos were exposed to various concentrations of ginsenoside Rb1, and scored for growth and development at the end of the 48h culture period. RESULTS: With the concentration of Rb1 rising, the total morphological scores significantly decreased; Developments of forebrain, midbrain and optic system were relatively sensitive to Rb1 and were affected at the concentration of 30 microg/ml; hindbrain, Branchial arch and limb buds were affected at 50 microg/ml; Yolk sac was affected at the low concentration of 15 microg/ml and the indexes of embryonic growth and development decreased at the high concentration of 50 microg/ml. Moreover, the rate of embryo teratogenicity were obviously increased. CONCLUSION: Ginsenoside Rb1 displayed teratogenic action in mice. The damage on structure and function of yolk sac might be part of teratogenic mechanisms of it.

Abnormalities, Drug-Induced↗
PubMed2005

[Comparative analysis of genetic diversity revealed by genomic-sSR, EST-SSR and pedigree in wheat (Triticum asetivum L.)].

Two SSR molecular markers, genomic-SSR and EST (expressed sequence tagged)-SSR, were used to measure the genetic diversity among 18 accessions of common wheat with known pedigrees, which were collected from winter wheat production region in Northern China. In addtion, the genetic diversity revealed by pedigree, EST-SSR and genomic-SSR was also compared. The results showed that the average number of alleles per genomic-SSR locus is 3.34, which is higher than that of EST-SSR (2.31), indicating that genomic-SSR is more polymorphic than EST-SSR. Genomic-SSR and EST-SSR were used to calculate the genetic distance (GD) in different materials. The mean GD value of EST-SSR for the 18 wheat genotypes is 0.3996,which is lower than that of genomic-SSR (0.5458). At the locus level, the mean GD calculated using pedigree information is higher (0. 9716) than that of genomic-SSR and EST-SSR markers (0.5458 and 0.3996). Therefore, although polymorphism of EST-SSR is low as compared to genomic SSR,it provides a more accurate evaluation of genetic relationship, especially when accessions are very closely related in pedigree. The strategy for improving the genetic diversity of wheat was also discussed.

Alleles↗
PubMed2005

Surgical treatment for rabbits' femoral arteries subjected to gunshot wounds combining with seawater immersion.

OBJECTIVE: To investigate the surgical treatment methods and evaluate the outcome of gunshot wounds combining with seawater immersion in rabbits' femoral arteries. METHODS: One hundred healthy New Zealand white rabbits (either sex, 3.14 kg+/-0.61 kg in weight) were randomly divided into a seawater immersion group (n=50) and a simple injury group (n=50). The unilateral femoral arteries of all the rabbits were injured by 0.38 g steel spheres with velocity of 600-800 m/s fired by a 7.62 mm rifle. The rabbits in the seawater immersion group were immersed in seawater (saline content of 2.54%, pH 8.2-8.4, and at 21 degrees C) for 60 minutes but those in the simple injury group were not. After the injured segment (observed by naked eyes) of the femoral artery was excised, the blood flow restoration was reconstructed by direct end-to-end anastomosis, reversed autogenous venous grafting or cryopreserved arterial allografting, according to the length of the arterial defects. At 24 hours, and 7, 14 and 21 days after operation, the blood flow was examined. Operative exploration was performed for the animals with partly or fully obstructed blood flow. The tissues around the anastomosis sites and the grafts were harvested for pathological observation under a light microscope and an electron microscope. RESULTS: In the rabbits with completely transected injury, the unobstructed rates in the first 3 weeks after operation were 80.00% in the seawater immersion group and 86.67% in the single injury group, and no significant difference was found between the two groups (P>0.1). In the rabbits with arterial contusion injury, the unobstructed rates in the first 3 weeks after operation were 86.67% in the seawater immersion group and 82.35% in the single injury group, and no significant difference was found between the two groups (P>0.1). Most thrombosis occurred in the first operative week. Atypical endothelial cells were detected at the anastomosis sites at the first operative week, and the anastomosis sites were lined with endothelial cells in 3 weeks postoperatively. CONCLUSIONS: During the surgical treatment for gunshot wounds combining with seawater immersion, resection of the grossly-injured artery and routine artery reconstruction can obtain satisfactory outcome. Homologous artery is a kind of vascular graft with certain applied value.

Animals↗
PubMed2004

Crystallization and preliminary X-ray crystallographic analysis of agkicetin-C from Deinagkistrodon acutus venom.

The crystallization and preliminary crystallographic analysis of agkicetin-C, a well known platelet glycoprotein Ib (GPIb) antagonist from the venom of Deinagkistrodon acutus found in Anhui Province, China is reported. Crystals of agkicetin-C suitable for structure determination were obtained from 1.8 M ammonium sulfate, 40 mM MES pH 6.5 with 2%(v/v) PEG 400. Interestingly, low buffer concentrations of MES seem to be necessary for crystal growth. The crystals of agkicetin-C belong to space group C2, with unit-cell parameters a = 177.5, b = 97.7, c = 106.8 A, beta = 118.5 degrees, and diffract to 2.4 A resolution. Solution of the phase problem by the molecular-replacement method shows that there are four agkicetin-C molecules in the asymmetric unit, with a VM value of 3.4 A3 Da(-1), which corresponds to a high solvent content of approximately 64%. Self-rotation function calculations show a single well defined non-crystallographic twofold axis with features that may represent additional elements of non-crystallographic symmetry.

Agkistrodon↗
PubMed2004

Inhalation of nitric oxide in the treatment of severe acute respiratory syndrome: a rescue trial in Beijing.

Inhalation of nitric oxide (NO) improved arterial oxygenation and enabled the reduction of inspired oxygen therapy and airway pressure support in patients with severe acute respiratory syndrome (SARS). In addition, chest radiography showed decreased spread or density of lung infiltrates, and the physiological effects remained after termination of inhaled NO therapy. These findings suggest not only a pulmonary vasodilator effect of inhaled NO, but also an effect on SARS.

Administration, Inhalation↗
PubMed2004

Purification, characterization, crystallization and preliminary X-ray crystallographic analysis of two novel C-type lectin-like proteins: Aall-A and Aall-B from Deinagkistrodon acutus venom.

Aall-A and Aall-B, two novel heterodimeric snake-venom C-type lectin-like proteins (sv-CLPs), were purified from the venom of Deinagkistrodon acutus from Anhui, China. Strikingly, both these proteins can localize on and congregate human erythrocytes, instead of aiming at the common targets of sv-CLPs such as platelet glycoproteins, von Willebrand factors, coagulant factors etc. The crystals of Aall-A belong to space group P2, with unit-cell parameters a = 105.2, b = 56.2, c = 108.7 A, beta = 100.5 degrees , and diffract to 2.0 A resolution, while the crystals of Aall-B belong to space group P2(1)2(1)2(1), with unit-cell parameters a = 36.8, b = 56.5, c = 149.2 A, and diffract to 2.2 A resolution. To our knowledge, this is the first report of sv-CLPs with this unique function and of their preliminary crystallographic analysis.

Amino Acid Sequence↗
PubMed2004

Direct binding of visual arrestin to a rhodopsin carboxyl terminal synthetic phosphopeptide.

PURPOSE: The phosphorylated carboxyl terminus of rhodopsin is required for the stable binding of visual arrestin to the full length rhodopsin molecule. Phosphorylation of the carboxyl terminus has been shown to induce conformational changes in arrestin, which promote its binding to the cytoplasmic loops of rhodopsin. However, it has not been determined whether phosphorylation is also responsible for the direct binding of the rhodopsin carboxyl terminus to arrestin. To further investigate the role of rhodopsin phosphorylation on arrestin binding, surface plasmon resonance was used to measure the interaction between a synthetic phosphopeptide corresponding to the carboxyl terminus of rhodopsin and visual arrestin in real time. METHODS: Synthetic peptides were generated that correspond to the phosphorylated and nonphosphorylated carboxyl terminus of bovine rhodopsin. These peptides were immobilized on a biosensor chip and their interaction with purified visual arrestin was monitored by surface plasmon resonance on a BIAcore 2000 or 3000. RESULTS: A synthetic peptide phosphorylated on residues corresponding to Ser-338, Thr-340, Thr-342 and Ser-343 of bovine rhodopsin was sufficient for direct binding to visual arrestin. In contrast, a second phosphopeptide phosphorylated on Thr-340 and Thr-342 and a nonphosphorylated synthetic peptide were not able to bind arrestin. A peptide fully substituted at all serine and threonine residues with glutamic acid was unable to substitute for phosphorylation. CONCLUSIONS: Surface plasmon resonance is a sensitive method for detecting small differences in affinity. We were successful in using this technique to detect differences in the affinity of phosphorylated and nonphosphorylated rhodopsin peptides for visual arrestin. The data suggest that these are low-affinity interactions and indicate that phosphorylation is responsible for the direct binding of the rhodopsin carboxyl terminus to visual arrestin. Four phosphorylated residues are sufficient for this interaction. Because the affinity of the synthetic phosphopeptide for arrestin is substantially lower than the full length rhodopsin molecule, the cytoplasmic loops and rhodopsin carboxyl terminus appear to interact in a cooperative manner to stably bind arrestin.

Animals↗
PubMed2004

Highly diastereoselective epoxidation of allyl-substituted cycloalkenes catalyzed by metalloporphyrins.

Highly diastereoselective epoxidations of allyl-substituted cycloalkenes including allylic alcohols, esters, and amines using sterically bulky metalloporphyrins [Mn(TDCPP)Cl] (1) and [Ru(TDCPP)CO] (2) as catalysts have been achieved. The "1 + H(2)O(2)" and "2 + 2,6-Cl(2)pyNO" protocols afforded trans-epoxides selectively in good yields (up to 99%) with up to >99:1 trans-selectivity.

Journal Article↗
PubMed2004

Purification, partial characterization, crystallization and structural determination of AHP-LAAO, a novel L-amino-acid oxidase with cell apoptosis-inducing activity from Agkistrodon halys pallas venom.

A snake-venom protein named AHP-LAAO has been purified from Agkistrodon halys pallas venom using four-stage chromatography. AHP-LAAO is a novel member of the snake-venom L-amino-acid oxidase family. Its amino-acid sequence shows high homology to other members of this family. For L-leucine, the values of k(cat) and K(M) are 31.1 s(-1) and 0.25 mM, respectively. The molecular weight of AHP-LAAO is about 60.7 kDa as determined by MALDI-TOF mass spectrometry. AHP-LAAO can also induce apoptosis of cultured Hela cells. Two sets of diffraction data with similar resolution limits (about 2.5 A) were collected independently at MacCHESS (Cornell High Energy Synchrotron Source, USA) and IHEP (Institute of High Energy Physics, Beijing, China). The crystals belong to space group I2(1)3, with unit-cell parameter a = 169.31 A, corresponding to one molecule in the asymmetric unit and a volume-to-weight ratio of 3.33 A(3) Da(-1). The final structural model is similar to that of L-amino-acid oxidase from Calloselasma rhodostoma venom.

Amino Acid Oxidoreductases↗