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Biomedical subjects

Ming Chen

Publications and source records attributed to Ming Chen.

At least 127 records · Page 7Linked to original sources
PubMed2004

[Effects of nitric oxide on root growth and its oxidative damage in wheat seedling under salt stress].

Effects of nitric oxide (NO), a substance newly found to have protective functions in plants, on root growth of wheat (Triticum aestivum L. Yangmai 158) seedlings under salt stress were studied. Sodium nitroprusside (SNP), an NO donor, markedly alleviated the inhibitory effect of salt on root elongation at salt concentrations around 150 mmol/L, but was ineffective when NaCl concentration was at 300 mmol/L or higher. It was most effective at 0.05-0.1 mmol/L, and had harmful effect at 0.30-5 mmol/L. Furthermore, when wheat seedling roots were treated with 150 mmol/L NaCl in combination with 0.05 mmol/L SNP and NO scavenger (hemoglobin, Hb), NO(-)(2)/NO(-)(3) and K(3)Fe(CN)(6) as controls, both of which were the two other major products besides NO when SNP dissolved in water, respectively, activities of superoxide dismutase (SOD), peroxidase (POD) and ascorbate peroxidase (APX) were enhanced to some extent. While, the generation of O(-.)(2) and the accumulation of MDA and H(2)O(2) were alleviated. DNA laddering was observed when wheat seedling roots exposed to 150 mmol/L NaCl for 6 d, also suggesting that salt stress might induce oxidative damage in root-tips. In combination with hemoglobin, NO(-)(2)/NO(-)(3) and K(3)Fe(CN)(6) as controls, the results showed that NO could block DNA ladders. Above results suggest that it is NO rather than any substances which is protecting root-tip cells of wheat seedlings from oxidative damage caused by salt stress.

Apoptosis↗
PubMed2004

[Study on expression of matrix metalloproteinases and their inhibitors in parotid gland tumors].

OBJECTIVE: To explore the correlation of MMP and TIMP and clinical data in benign and malignant parotid tumors. METHOD: The expression of matrix metalloproteinase-2, -9 (MMP-2, MMP-9), tissue inhibitor-1, 2 of matrix metalloproteinase (TIMP-1,TIMP-2) were determined in 60 patients with benign and malignant parotid gland tumors by ABC immunohistochemical methods, their correlation of clinical data was analysed. RESULT: (1) Down-regulation of TIMP-2 was accompanied by lymph node metastasis and distant metastasis in malignant parotid tumor (P<0.01). (2) The expression of MMP-2 was higher in patients more than 60 years old in benign parotid tumor (P<0.01). (3) There was a close positive relationship between the expression of MMP-2 and MMP-9, MMP-9 and TIMP-1, MMP-2 and TIMP-2 (P<0.05). CONCLUSION: The imbalance of MMP-2 and TIMP-2 may be more important in malignant parotid gland tumor, down-expression of TIMP-2 may be an early biomarker of metastasis and invasion of tumor.

Adult↗
PubMed2004

[Combined gene therapy enhances collateral vascularization in coronary artery occlusion swine model].

OBJECTIVE: To investigate the efficacy of combined gene transfer of vascular endothelial growth factor (VEGF) and angiotensin-1 (Ang-1) in swine coronary artery occlusion. METHODS: Swine underwent left thoracotomy followed by ligation of left anterior descending coronary artery. Constructed PCD(2)/VEGF and/or PCD(2)/Ang-1 eukaryotic expression plasmid was directly injected into the swine myocardium. RT-PCR, immunohistochemistry, capillary density and arteriole density were used to detect gene expression and biological effect. Coronary angiography was done to evaluate collateral circulation of the occluded artery. RESULTS: High levels of VEGF and Ang-1 mRNA and protein expression were detected. There was a significant increase in the number of capillaries and arterioles as compared with a control group (P < 0.05). Capillary density and arteriole density of the combination therapy group were higher than those of the swing receiving either therapy alone. Coronary angiography showed better collateral circulation in the combination therapy group. CONCLUSIONS: Direct injection of PCD(2)/VEGF and PCD(2)/Ang-1 can transfect the myocardium and express VEGF and Ang-1 protein. Combined gene transfer of VEGF and Ang-1 can increase capillary and arteriole number and enhance collateral circulation of the occluded coronary artery more effectively.

Angiotensin I↗
PubMed2003

Natural occurrence and synthesis of two new postspinel polymorphs of chromite.

A high-pressure polymorph of chromite, the first natural sample with the calcium ferrite structure, has been discovered in the shock veins of the Suizhou meteorite. Synchrotron x-ray diffraction analyses reveal an orthorhombic CaFe2O4-type (CF) structure. The unit-cell parameters are a = 8.954(7) A, b = 2.986(2) A, c = 9.891(7) A, V = 264.5(4) A3 (Z = 4) with space group Pnma. The new phase has a density of 5.62 g/cm3, which is 9.4% denser than chromite-spinel. We performed laser-heated diamond anvil cell experiments to establish that chromite-spinel transforms to CF at 12.5 GPa and then to the recently discovered CaTi2O4-type (CT) structure above 20 GPa. With the ubiquitous presence of chromite, the CF and CT phases may be among the important index minerals for natural transition sequence and pressure and temperature conditions in mantle rocks, shock-metamorphosed terrestrial rocks, and meteorites.

Biophysical Phenomena↗
PubMed2003

Correlation of echo-Doppler aortic valve regurgitation index with angiographic aortic regurgitation severity.

We assessed aortic regurgitation (AR) severity by utilizing multiple echo-Doppler variables in comparison with AR severity by aortic root angiography. Patients were divided into 3 groups: mild, moderate, and severe. An AR index (ARI) was developed, comprising 5 echocardiographic parameters: ratio of color AR jet height to left ventricular outlet flow diameter, AR signal density from continuous-wave Doppler, pressure half-time, left ventricular end-diastolic diameter, and aortic root diameter. There was a strong correlation between AR severity by angiography and the calculated echo-Doppler ARI (r = 0.84, p = 0.0001). As validated by aortic angiography, the ARI is an accurate reflection of AR severity.

Adult↗
PubMed2003

Lead transformation and distribution in the soils of shooting ranges in Florida, USA.

The use of lead bullets and shot at shooting ranges is under increasing scrutiny as a potentially significant source of Pb pollution. This study assessed Pb contamination in the soils of two shooting ranges (TRR and MPR) in Florida. Soil samples were collected from the two ranges and analyzed for total Pb to determine Pb contamination. Selected spent bullets and berm soil samples were mineralogically characterized to identify Pb transformation. Total Pb in the range soils was significantly elevated with the highest (up to 4.84% by weight) in the berm soils. Most soils failed the synthetic precipitation leaching procedure (SPLP) test. Also, at the MPR shooting range, a substantial amount of Pb migrated down in the subsurface soil, possibly due to the enhanced solubilization of organic Pb complexes at alkaline pH, whereas high cation exchange capacity of the profile soil may be responsible for Pb retention in the subsoil. The weathering products on the surface of the spent bullets were predominantly hydrocerussite [Pb(3)(CO(3))(2)(OH)(2)] and cerussite (PbCO(3)). Hydrocerussite was mainly found in the MPR range soils, whereas Pb was transformed into hydroxypyromorphite [Pb(5)(PO(4))(3)OH] in the TRR range soils because of the presence of more P. Sequential extraction and lead activity ratio modeling showed that the soil Pb solubility was controlled by Pb carbonate minerals in the MPR shooting range, and by less soluble Pb phosphate minerals in the TRR shooting range. This research suggests that it is important to develop and implement efficient management practices to minimize adverse impacts of Pb at shooting ranges. Phosphate-induced Pb immobilization may be an effective alternative for reducing Pb mobility in the shooting range soils.

Journal Article↗
PubMed2003

Field assessment of lead immobilization in a contaminated soil after phosphate application.

A pilot-scale field demonstration was conducted at a Pb-contaminated site to assess the effectiveness of Pb immobilization using P amendments. The test site was contaminated by past battery recycling activities, with average soil Pb concentration of 1.16%. Phosphate amendments were applied at a 4.0 molar ratio of P/Pb with three treatments: T1, 100% P from H(3)PO(4); T2, 50% from H(3)PO(4)+50% from Ca(H(2)PO(4))(2); and T3, 50% from H(3)PO(4)+5% phosphate rock. Soil samples were collected and characterized 220 days after P application. Surface soil pH was reduced from 6.45 to 5.05 in T1, to 5.22 in T2, and to 5.71 in T3. Phosphate treatments effectively transformed up to 60% of total soil Pb from the non-residual fraction (sum of water soluble and exchangeable, carbonate, Fe-Mn oxide, and organic fractions) to the residual fraction relative to the control. In addition, P treatments reduced Toxicity Characteristic Leaching Procedure (TCLP) Pb from 82 mg l(-1) to below EPA's regulatory level of 5 mg l(-1) in the surface soil. Scanning electron microscopy-energy dispersive X-ray elemental analysis and X-ray diffraction analysis indicated formation of insoluble chloropyromorphite [Pb(5)(PO(4))(3)Cl] mineral in the P-treated soils. Although H(3)PO(4) is necessary to dissolve meta-stable Pb in soil for further lead immobilization, it should be used with caution due to its potential secondary contamination. A mixture of H(3)PO(4) and Ca(H(2)PO(4))(2) or phosphate rock was effective in immobilizing Pb with minimum adverse impacts associated with pH reduction.

Adsorption↗
PubMed2003

Uropathogenic Escherichia coli toxins induce caspase-independent apoptosis in renal proximal tubular cells via ERK signaling.

BACKGROUND: Pyelonephritis is a risk factor for renal tubular epithelial cell damage. Recent studies have shown that Escherichia coli and/or its toxins may stimulate apoptotic cell death in renal tubular cells, but the underlying molecular mechanisms remain to be elucidated. METHODS: Confluent LLC-PK(1) cells were exposed to E. coli toxins from overnight cultures of the uropathogenic O6K13H1 (O6) and the nonpathogenic W3110. The cell death was studied with morphological and biological assay. RESULTS: E. coli soluble toxins from uropathogenic O6:K13:H1(O6) strain were found to induce apoptosis in a dose- and time-dependent manner in LLC-PK1 cells. The expression of FasR and the phosphorylation of ERK1/2 were significantly upregulated by O6 soluble toxins in a time-dependent manner. Cell death was completely inhibited by two specific ERK1/2 inhibitors, but not by a broad caspase inhibitor, zVAD-fmk, implicating a caspase-independent pathway via ERK. Moreover, we found that lysophosphatidic acid could trigger a survival signal through G-proteins and PI3K. CONCLUSION: We demonstrate that apoptosis induced by uropathogenic E. coli toxins is dependent on ERK1/2. Caspases, although being activated, are not necessary for cell death, and they act after the ERK signaling at which point cells become committed to cell death or can be rescued.

Analysis of Variance↗
PubMed2003

Contributions of the visual ventral pathway to long-range apparent motion.

Objects displaced intermittently across the visual field will nonetheless give an illusion of continuous motion [called apparent motion (AM)] under many common conditions. It is believed that form perception is of minor importance in determining AM, and that AM is mediated by motion-sensitive areas in the "where" pathway of the cortex. However, form and motion typically interact in specific ways when natural objects move through the environment. We used functional magnetic resonance imaging to measure cortical activation to long-range AM, compared to short-range AM and flicker, while we varied stability of structural differences between forms. Long-range AM activated the anterior-temporal lobe in the visual ventral pathway, and the response varied according to the form stability. The results suggest that long-range AM is associated with neural systems for form perception.

Brain Mapping↗
PubMed2003

Vitamin E succinate inhibits human prostate cancer cell growth via modulating cell cycle regulatory machinery.

Several epidemiological studies have demonstrated that vitamin E is a chemopreventative agent for prostate cancer. alpha-Tocopheryl succinate (VES), a derivative of vitamin E, effectively modulates prostate cancer cell growth. However, little is known about the mechanisms regarding this action. Here we show that VES causes human prostate cancer cell LNCaP arrest at G1 phase. This effect is accomplished through VES significantly decreasing expression of the cell cycle regulatory proteins cyclin D1, D3, and E, cdk2 and 4, but not cdk6. Furthermore, VES reduces cdk4 kinase activity, Rb phosphorylation, and cyclin E mRNA expression. Recently there is increasing interest in the protective effect of the VES and selenium combination on prostate cancer. Here we show that VES and selenium work through different mechanisms to exert their inhibitory effects on prostate cancer cells. Taken together, our studies suggest that VES-mediated prostate cancer cell G1/S arrest is a consequence of the regulation of multiple molecules of the cell cycle regulatory machinery.

Anticarcinogenic Agents↗
PubMed2003

Genetic organization of genes encoding phenol hydroxylase, benzoate 1,2-dioxygenase alpha subunit and its regulatory proteins in Acinetobacter calcoaceticus PHEA-2.

Acinetobacter calcoaceticus PHEA-2 is a phenol-degrading bacterium isolated from the wastewater from an oil refinery. A 10-kb XhoI fragment consisting of nine complete Open Reading Frames (ORFs) and one partial ORF was screened from a lambda library of PHEA-2 by Southern hybridization. The sequence analyses revealed that ORF2-ORF7, designated mphKLMNOP, are homologous to dmpKLMNOP of Pseudomonas sp. CF600 and mopKLMNOP of Acinetobacter calcoaceticus NCIB8250, sharing 38%-72% and 58.5%-93.5% respectively. The products encoded by dmp and mop genes convert phenol to catechol. The mph-operon and downstream ORFs, ORF9 and ORF10, sharing high identities to benM and benA, which encode ben-operon regulatory protein and benzoate 1,2-dioxygenase alpha subunit respectively, are separated by ORF8, whose function is unknown. The organization of the mph and ben operons is different from that described previously.

Acinetobacter calcoaceticus↗
PubMed2003

Phosphate-induced metal immobilization in a contaminated site.

To assess the efficiency of P-induced metal immobilization in soils, a pilot-scale field experiment was conducted at a metal contaminated site located in central Florida. Phosphate was applied at a P/Pb molar ratio of 4.0 with three treatments: 100% of P from H3PO4, 50% of P from H3PO4+ 50% of P from Ca(H2PO4)2, and 50% of P from H3PO4+5% phosphate rock in the soil. Approximately 1 year after P application, soil and plant samples were collected to determine mobility and bioavailability of selected metals (Pb, Zn, and Cu) using sequential extraction procedure and mineralogical characterization using X-ray diffraction (XRD) and scanning electron microscope-energy dispersive X-ray (SEM-EDX) analysis. Phosphorus distribution and soil pH effects were also evaluated. Phosphate was more effective in transforming soil Pb (to 53%) from the non-residual to the residual phase than soil Zn (to 15%) and soil Cu (to 13%). This was because Pb was immobilized by P via formation of an insoluble pyromorphite-like mineral in the surface and subsurface of the soil, whereas no phosphate mineral Zn or Cu was identified. While P amendment enhanced metal uptake in the roots of St. Augustine grass (Stenotaphrum secundatum), it significantly reduced metal translocation from root to shoot, especially Pb via formation of a pyromorphite-like mineral on the membrane surface of the root. A mixture of H3PO4 and phosphate rock was effective in metal immobilization, with less soil pH reduction and less soluble P. Although H3PO4 was effective in immobilizing Pb, its use should be limited to minimize soil pH reduction and potential eutrophication risk.

Biological Availability↗
PubMed2003

Synergism of aspirin and heparin with a low-frequency non-invasive ultrasound system for augmentation of in-vitro clot lysis.

BACKGROUND: Aspirin, glycoprotein IIb/IIIa inhibitors and heparin are routinely used in acute coronary syndromes. Previously we showed that there is synergism between ultrasound and heparin and tirofiban in augmenting blood clot disruption. However, there is a little data on a possible synergism of low-frequency ultrasound with aspirin for in-vitro clot dissolution, and especially on the combination of aspirin with heparin and/or glycoprotein IIb/IIIa inhibitors. MATERIALS AND METHODS: Human blood clots (n = 320) were incubated for 10 or 20 minutes in saline containing aspirin alone or combined with heparin and/or tirofiban and/or eptifibatide. Clots were randomly treated with low-frequency ultrasound (27.3 kHz) or incubation only. The percent clot weight loss and the incremental effect of ultrasound were calculated. RESULTS: The most significant incremental effect of ultrasound on clot weight reduction was detected with aspirin alone (5.2 +/- 2.3% and 5.2 +/- 2.6% after 10' and 20', p = 0.04 and p = 0.06, respectively) and in combination with heparin (8.8 +/- 2.5% and 11.5 +/- 2.7% after 10' and 20', p = 0.01 and p = 0.0001, respectively). The greatest absolute magnitude of clot weight reduction was observed with ultrasound combined with aspirin and heparin (48.5 +/- 9.5% after 20'). The addition of tirofiban or eptifibatide to aspirin, heparin and ultrasound did not increase clot lysis. However, eptifibatide had significantly better synergism than tirofiban (p = 0.025 and p = 0.015, after 10 and 20 minutes, respectively). CONCLUSIONS: Aspirin alone or in combination with heparin results in significant augmentation of clot lysis and is synergistic with application of low-frequency ultrasound for 10 and 20 minutes only. These results may have important implications for a possible use of low-frequency ultrasound in treatment algorithms of acute coronary syndromes.

Adult↗
PubMed2003

Alterations in the intrauterine environment by glucocorticoids modifies the developmental programme of the auditory system.

Prenatal exposure to excessive glucocorticoids alters the programming of the metabolic and endocrine balance of various organs, including the nervous system. In the present study, prenatal glucocorticoid treatment was shown to increase the susceptibility of the inner ear to acoustic noise trauma in adult life. Acute auditory brainstem response thresholds were not different between the age-matched groups. However, when measured at 48 h and 4 weeks postexposure, the dexamethasone (DEX)-treated rats showed little or no recovery from the trauma. In contrast, normal rats showed a significant amount of recovery by 48 h postexposure and continued to show further recovery over 4 weeks. In addition, acoustic trauma resulted in a massive outer hair cell loss in the DEX rats compared to minor loss in the normal rats. To determine whether oxidative stress plays a role in the recovery phase of acoustic trauma, the free radical scavenger PBN (100 mg/kg) was administered before, during and several times after noise exposure. PBN treatment significantly reduced the physiological and morphological cochlear differences which were observed between DEX and control rats after acoustic trauma. These data support the hypothesis that alterations in the intrauterine environment may modify the developmental programme of the cochlea, inducing dysfunction later in adult life. Excessive prenatal exposure to dexamethasone decreased the potential for recovery of the cochlea to oxidative stress induced by acoustic trauma; this decreased recovery potential can be counteracted by treatment with antioxidants.

Animals↗
PubMed2003

[Ropivacaine or its combination with fentanyl for postoperative patient-controlled epidural analgesia].

OBJECTIVE: To investigate the pain-relieving effects of ropivacaine or its combination with fentanyl in postoperative patient-controlled epidural analgesia. METHODS: Sixty patients (ASA class I to II) scheduled for elective upper abdominal surgery were randomly divided into 4 groups (15 in each group) to receive 2.0 mg/ml ropivacaine (group R), 1.25 mg/ml ropivacaine plus 1.0 microg/ml fentanyl (group RF1), 1.0 mg/ml ropivacaine plus 2.0 microg/ml fentanyl (group RF2), and 1.0 mg/ml ropivacaine plus 4.0 microg/ml fentanyl (group RF4) respectively for patient-controlled analgesia. The bolus injection was set at 3.0 ml, lockout interval at 20 min, and background epidural infusion at 5.0 ml/h. Before and at 0, 6, 12, 24 and 48 h after the surgeries, the data including mean arterial pressure (MAP), heart rate (HR), cumulative consumption volume (CCV) of analgesic solution and visual analog scale (VAS) scores were recorded, observed and the adverse effects such as vomiting, nausea, pruritus, as well as the time of first excretion of intestinal gas. RESULTS: Compared with group R, significantly smaller CCV occurred in groups RF2, RF4 (P<0.01), and RF1 (P<0.05) at each time points postoperatively. No significant differences were noted between the groups in VAS scores. CONCLUSION: The 4 preparations are comparable in terms of analgesic efficacy and adverse effects, but in groups RF2 and RF4, the smaller doses have sufficed the needs.

Abdomen↗
PubMed2003

[The effect of magnitopuncture stimulation on HRV during simulated driving under vibration conditions].

The purpose of this study was to assess the effect of magnitopuncture stimuli for reducing driver mental stress and fatigue using power spectral analysis of the heart rate variability (HRV) and subjective evaluation. The experiments were divided into A-group and B-group. In both groups the subjects performed the simulator for 90 minutes under a vibration conditions with an erect sitting posture in a silent environment, and magnitopuncture was put on the acupoints when performing the task for one hour in A-group. In this study HRV exhibited a significant difference between the two groups after the simulating task (P < 0.05). A conclusion that magnitopuncture stimuli can reduce the driver mental stress and fatigue effectively was drawn.

Acupuncture Points↗