Biomedical subjects

Ping Shi

Publications and source records attributed to Ping Shi.

At least 19 recordsLinked to original sources

PubMed2007

Simultaneous in situ reflectance and probe beam deflection measurements at solid electrode-aqueous electrolyte interfaces.

A method is herein described for performing simultaneous in situ normal incidence reflectance spectroscopy (DeltaR/R, lambda = 633 nm) and probe beam deflection (PBD) measurements at solid electrodes in aqueous electrolytes, while scanning the potential linearly between two prescribed limits. Results obtained for Au in 0.1 M HClO4 and for Pt in both 0.1 M HClO4 and 0.1 M NaOH were found to be in excellent agreement with those reported in the literature for each individual spectroelectrochemical technique under otherwise similar conditions. Data collected for Pt electrodes in CO-saturated 0.1 M HClO4 revealed rather sudden changes in both DeltaR/R and PBD signals in the voltammetric region where the characteristic sharp peak associated with the oxidation of adsorbed CO occurs. This behavior was ascribed, respectively, to oxide formation (DeltaR/R) and to changes in the electrolyte composition in region neighboring the electrode, involving predominantly the acid concentration (PBD). In contrast, CO oxidation on Pt in 0.1 M NaOH yielded a PBD response consistent with formation of solution-phase carbonate via the reaction of the product, CO2, with hydroxyl ion. The exquisite sensitivity of DeltaR/R and PBD to interfacial phenomena was further illustrated using a monolayer of hemin irreversibly adsorbed on glassy carbon surfaces in 0.1 M Na2B4O7 (pH approximately 9.2). For this system, DeltaR/R was found to be proportional to the relative fractions of hemin and its reduced counterpart, while the PBD signal could be correlated with corresponding variations in the electrolyte concentration induced by the surface-bound redox process.

Journal Article↗

PubMed2006

In situ, time-resolved reflectance spectroscopy in the microsecond domain: oxidation of adsorbed carbon monoxide on polycrystalline pt microelectrodes in aqueous solutions.

The dynamics of the electrooxidation of adsorbed CO, COads, on polycrystalline Pt microelectrodes has been examined in CO-saturated 0.5 M H2SO4 and 0.5 M HClO4 aqueous solutions, using in situ, time-resolved, normalized differential reflectance spectroscopy lambda = 633 nm). Attention was focused on the unique dependence of COads oxidation on the potential at which the adsorbed full CO monolayer is assembled (i.e., hydrogen adsorption/desorption vs the double-layer region) using both fast linear scan voltammetry and potential step techniques. As evidenced from the data collected, COads oxidation at a fixed potential proceeds at slower rates when the monolayer is formed in the double- layer region compared to when it is formed in the hydrogen adsorption/desorption region. Possible explanations for this effect are discussed.

Adsorption↗

PubMed2006

Gender and risk factor dependence of cerebral blood flow velocity in Chinese adults.

BACKGROUND AND PURPOSE: The objective of this study is to determine if and how cerebral blood flow velocity and stroke risk factors are related in a stroke free population. METHODS: This cross-sectional study recruited 1323 stroke-free subjects, aged 42-73 years, from a county region in China. Systolic blood flow velocities in cerebral arteries were detected with trans-cranial Doppler. Key factors, such as anthropometry, life-style, medication use, blood pressure and blood biochemical analysis were investigated at the same time. RESULTS: In women, even controlled for major cardiovascular risk factors, cerebral blood flow velocities of common carotid artery, internal carotid artery, middle cerebral artery, anterior cerebral artery and posterior cerebral arteries decreased significantly with age (from 43.8 to 39.3, 48.0 to 42.6, 97.7 to 82.8, 79.2 to 69.4 and 44.1 to 39.7 cm/s in the range of 42-73 years old, p < 0.01 for each). In men, however, this inverse trend only existed in common carotid artery (from 45.6 to 41.7 cm/s, p < 0.01). Multivariate regression showed that most established cardiovascular risk factors (e.g. hypertension, hypercholesterolemia, diabetes mellitus and overweight/obesity) were associated with decreased blood flow velocity in the extra-cranial arteries. However, this association was not present (e.g. diabetes and overweight/obesity) or was inversed (e.g. hypertension and hypercholesterolemia) in the intra-cranial arteries. CONCLUSION: Extra-cranial blood flow velocity is significantly and inversely related to age and cardiovascular risk factors. The relationship between intra-cranial blood flow and risk factors changes and may depend on gender. These finding may have importance in the determination of mechanisms of stroke.

Adult↗

PubMed2006

Influence of lanthanum on the accumulation of trace elements in chloroplasts of cucumber seedling leaves.

Influence of La3+ on the accumulation of trace elements (75Se, 56 Co, 83 Rb, 48 V, 95 mTc, and 67Ga) in chloroplasts of cucumber seedling leaves was studied by a radioactive multi-tracer technique. At the same time, chloroplast contents of different concentrations of La3+ treatment were calculated. It was observed that chloroplast contents peaked at 0.02 mM La3+ treatment and that the uptake and distribution of these trace elements in chloroplasts of cucumber seedling leaves are different under different La3+ treatments. With the increase of lanthanum concentrations from 0.002 to 2 mM, the uptake percentages of 75Se, 56 Co, and 83 Rb presented an obvious increase and then sharply decreased in contrast to the non-lanthanum treatment, whereas there appeared a sharp decrease and then restored control level in the uptake of 48 V. The other two trace elements, namely 95 mTc and 67Ga, were accumulated only in the presence of 0.02 mM La3+. The results indicate that lanthanum treatments to growing the cucumber lead to the change of trace element uptake in the chloroplasts of leaves, which suggest that lanthanum might influence the accumulation of trace elements in chloroplasts of cucumber seedling leaves by regulation of various ion transport mechanisms, thus affecting the photosystem of leaves.

Chloroplasts↗

PubMed2006

Effects of azadirachtin on six inorganic cation distributions in Ostrinia furnacalis (G.).

Azadirachtin (Az), as a botanical insecticide, is relatively safe and biodegradable. It affects a wide variety of biological processes, including the reduction of feeding, suspension of molting, death of larvae and pupae, and sterility of emerged adults in a dose-dependent manner. However,the mode of action of this toxin remains obscure. By using ion chromatography, we analyzed changes in six inorganic cation (Li+, Na+, NH4+, K+, Mg2+, and Ca2+) distributions of the whole body and hemolymph in Ostrinia furnacalis (G.) after exposure to sublethal doses of Az. The results showed that Az dramatically interfered with Na+, NH4 +, K+, Mg2+, and Ca2+ distributions in hemolymph of O. furnacalis (G.) and concentrations of these five cations dramatically increased. However, in the whole body, the levels of K+, Mg2+, and Ca2+ significantly, decreased after exposure to Az, except that Na+ and NH4 + remained constant. Li+ was undetected in both the control and treated groups in the whole body and hemolymph. It is suggested that Az exerts its insecticidal effects on O. furnacalis (G.) by interfering with the inorganic cation distributions related to ion channels.

Ammonia↗

PubMed2005

Optical determination of differential coverage-potential relations of redox-active species immobilized on electrode surfaces.

Single-wavelength (HeNe laser, lambda = 633 nm), normal incidence UV-visible reflectance spectroscopy was used to monitor the optical properties of the glassy carbon (GC)|0.2 M NaOH(aq) interface as a function of the applied potential, E. Whereas the electroreflectance coefficient for bare GC was found to be small and potential independent, surface functionalization by an irreversibly adsorbed layer of tetrasulfonated cobalt phthalocyanine (CoTSPc) yielded a clearly defined sigmoidally shaped normalized reflectance change (DeltaR/R) vs E curve over the potential region in which the adsorbate displayed redox peaks. Assuming DeltaR/R is proportional to the extent of redox conversion, as has been reported for macrocycles adsorbed on other types of carbon (e.g., Kim, S.; Xu, X.; Bae, I. T.; Wang, Z.; Scherson, D. A. Anal. Chem. 1990, 62, 2647-2650), differential coverage-potential relations were determined based purely on the optical data collected. A similar optical behavior was found for irreversible adsorbed CoPc and tetraamino CoPc (CoTAPc) adsorbed on GC, for which the voltammetric peaks were ill-defined, too small for coulometric analyses to be reliably performed, or both. No detectable changes in the DeltaR/R vs E profiles of either bare or macrocyclic-functionalized surfaces were observed upon addition of hydrazine to the neat 0.2 M NaOH solution at potentials at which these surfaces display electrocatalytic properties for its oxidation. Possible factors responsible for this behavior are discussed.

Journal Article↗

PubMed2005

Effects of ATRA on expression of mRNA binding protein p62 in human gastric cancer cells.

The distribution of the cancer-associated protein p62 in human gastric carcinoma (BGC-823) cells was examined by confocal laser scanning microscopy and electron microscope immunocytochemistry. In control cells p62 was cytoplasmic in location and concentrated in the cytoplasmic matrix, but when cell growth was inhibited by treatment with 50 microM all-trans-retinoic acid (ATRA) for 5 days, p62 expression decreased and the protein was translocated from cytoplasm to nucleus. Ultrastructural localization using gold particles showed that p62 was bond mainly to a linear structure in nucleus. The speculation that p62 binds Insulin-like growth factor (IGF)-II mRNA indicates its probable involvement in the posttranscriptional IGF-II mRNA processing and p62 could play a role in tumorgenesis by regulating the expression of IGF-II. Further studies will be needed to confirm this view.

Carcinoma↗

PubMed2005

In situ, time-resolved normal incidence reflectance spectroscopy of polycrystalline platinum microelectrodes in aqueous electrolytes.

In situ normal incidence reflectance spectra of polycrystalline Pt microelectrodes have been monitored as a function of the applied potential in aqueous 0.5 M H(2)SO(4) using a He-Ne laser source (633 nm) and a beam splitter/microscope objective arrangement. Data recorded during voltammetric cycles in Ar-purged solutions revealed a linear correlation between the normalized change in reflectance, DeltaR/R = (R(s) - R(ref))/R(ref) (where R(s) and R(ref) are the light intensities measured by the detector at the sampling, s, and reference potentials, ref, respectively), and the extent of oxidation of the Pt surface over a wide coverage range. Reflectance spectra were also collected in CO-saturated 0.5 M H(2)SO(4) during chronocoulometric measurements involving judiciously selected limits for both the potential step and duty cycle parameters. Analysis of these results made it possible to extract contributions to the current derived from oxide formation during oxidation of adsorbed and bulk CO, based strictly on the optical response.

Adsorption↗

PubMed2005

Proteomic detection of changes in protein synthesis induced by lanthanum in BGC-823 human gastric cancer cells.

There is increasing interest in the use of rare earth elements in medicine. However, the biological mechanism of action of this metal ion remains unclear. In the present study, changes in protein synthesis induced by lanthanum in BGC-823 human gastric cancer cells were investigated. The proteins were separated using two-dimensional polyacrylamide gel electrophoresis and four proteins were significantly affected by lanthanum treatment when compared to an untreated control. Among them, one was down-regulated and three were up-regulated. Of these, three were successfully identified as RHOJ, CSP6 and MPI2 with peptide mass fingerprinting using matrix-assisted laser desorption/ionization time of flight mass spectrometer (MALDI-TOF-MS) after in-gel trypsin digestion. Among them, RHOJ was down-regulated and CSP6 and MPI2 were up-regulated. The three proteins are involved in various cellular functions, which are correlated with the regulation of cell morphology, gene transcription and cell cycle, respectively. It is suggested that the possible involvement of rare earth elements in the growth arrest of tumor cells is significantly associated with the differential protein expression induced by rare earth ions.

Carcinoma↗

PubMed2005

The diversity expression of p62 in digestive system cancers.

The expression of p62 autoantigen and the frequency of p62 autoantibody have been reported in hepatocellular carcinoma (HCC) and many types of malignant tumors, respectively, but information regarding to the expression of p62 in other cancer tissues and the association of autoantibody to p62 with tumor behaviors is not available. In the current study, the expression of p62 in tissues and the appearance of p62 autoantibody in sera were detected by immunohistochemical staining and ELISA in four clinical types of digestive system cancers including gastric cancer, esophageal cancer, large intestine cancer and HCC, respectively. Interestingly, the immunohistochemistry staining of p62 has been shown in all of digestive canal tissues (stomach, esophagus, large intestine) including tissues with cancers, beside cancers and from non-malignant patients, whereas the frequencies were 62.5% and 0% in tissues with cancer and beside cancer in patients with HCC, respectively. Importantly, we found that the p62 expression and the frequency of autoantibody to p62 were associated to cell differentiation and tumor metastasis, respectively. These results suggest that the expression of p62 in tissues and the appearance of autoantibody to p62 in sera might be related to cell malignant manifestations. Moreover, p62 autoantibody is a significant marker for the prognosis of cancers and the evaluation of clinical treatments.

Adult↗

PubMed2005

Baseline pulmonary function and quality of life 9 years later in a middle-aged Chinese population.

STUDY OBJECTIVE: This research examined the association of baseline pulmonary function with future quality of life (QOL). METHODS: We collected baseline pulmonary function data in 1993 and 1994, and assessed QOL using the Chinese 35-Item Quality of Life Instrument in 2002 in a cohort of 1,356 participants. We used Pearson correlation analysis, multivariate analysis of variance, and multivariate linear regression analysis to assess the relationship between pulmonary function and QOL. RESULTS: The baseline percentage of age- and height-predicted FEV1 (FEV1%) was significantly correlated with the resurvey total QOL score (r = 0.126, p < 0.001) and with QOL scores for the general (r = 0.074, p = 0.006), physical (r = 0.085, p = 0.002), independence (r = 0.178, p < 0.001), and psychological (r = 0.064, p = 0.018) domains but not with the social and environmental domains after adjusting for age and sex. These associations were weaker for the percentage of age- and height-predicted FVC. Multiple linear regression showed that the above associations were independent of baseline and resurvey smoking status. Inclusion of respiratory symptoms in the model reduced the regression coefficients from 0.82 to 0.41 for the total QOL score and from 1.43 to 0.94 for the independence domain score, for a 10% change in FEV1%. The age- and sex-adjusted mean total QOL scores were 78, 76, 76, and 69, respectively (p < 0.001), for the groups of normal, symptomatic only, impaired pulmonary function only, and both symptomatic and impaired pulmonary function. This trend was also significant for the general, physical, independence, and psychological domain scores. CONCLUSION: Impaired baseline pulmonary function has a significant negative impact on QOL in later life that is independent of age, sex, height, and smoking status and is largely mediated through the development of chronic respiratory symptoms.

China↗

PubMed2005

[The development and Assessment on the general quality of life intrument for Chinese people].

OBJECTIVE: To develop a general quality of life (QOL) instrument for Chinese in accordance with the Chinese culture and to assess its reliability, validity and sensitivity. METHODS: A 35-item QOL questionnaire(QOL-35) was developed with reference to the World Health Organization QOL questionnaire(WHO-100) and the 36-item medical outcomes study on short-form health status(SF-36). Thirty five items were divided into six domains (general, physical, independent, psychological, social, environment) and one item on QOL transition. The reliability of QOL-35 was assessed by a test-retest survey among 127 adults with an interval of 24-72 hours. The internal consistency and validity were evaluated by a survey on 135 adults from outpatients or general population, using QOL-35, WHO-100 and SF-36. The adaptability was assessed by application to 1356 community-based samples in Beijing. RESULTS: (1)Test-retest reliability of QOL-35: weighted Kappa indexes for items were from 0.86 to 1.00. Intraclass correlation coefficients were from 0.68 to 0.94 for domains, and 0.94 for total score. (2) On internal consistency: Cronbach's Alphas were 0.93, 0.97 and 0.89 for QO1-35, WHO-100 and SF-36. (3)On construct validity. The accumulated proportions of variances of the preceding seven factors were 66.5%, 50.3% and 65.3% for QOL-35, WHO-100 and SF-36. (4) On criterion validity. Spearman correlation coefficients of total QOL score of QOL-35 with those of WHO-100 and SF-36 were 0.805 and 0.745. (5)The rates of chronic diseases were 53.1%, 33.1%, 26.4% and 25.1% from first to fourth quantile of the total QOL scores of QOL-35(P<0.05). (6)Cronbach's Alpha was from 0.68 to 0.93 in 135 subjects, and from 0.71 to 0.91 in 1356 individuals of natural population. CONCLUSION: The QOL-35 instrument satisfied test-retest reliability and was highly correlated with WHO-100 and SF-36, having fewer items but better construction validity, better internal consistency, and better discrimination ability. We suggested that QOL-35 be used as a replicable tool to assess quality of life in the Chinese general population.

Adult↗

PubMed2004

Diffusion boundary layer of a rotating disk electrode as a thin-layer spectroelectrochemical cell.

A UV-visible rapid scan spectrophotometer (RSS) was coupled to a Au rotating disk electrode (RDE) for monitoring at near-normal incidence the reflection-absorption spectrum of the diffusion boundary layer in [Fe(CN)(6)](4)(-) aqueous solutions over a potential region in which [Fe(CN)(6)](4-) oxidizes, generating highly absorbing [Fe(CN)(6)](3-) (lambda(max) = 420 nm). Measurements were performed under steady-state conditions at rotation rates, omega, in the range 300 <or= omega <or= 2500 rpm, yielding well-defined spectra displaying characteristic features of [Fe(CN)(6)](3-). In agreement with theoretical predictions, the absorbance A at lambda(max), using as a reference A(lambda(max)) for the spectrum recorded at a potential negative to the onset of [Fe(CN)(6)](4-) oxidation, was found to be proportional both to the current and also to omega(1/2) under conditions in which E was positive enough for the reaction to proceed under diffusion-limited control.

Journal Article↗

PubMed2004

Hypertension and subclinical carotid atherosclerosis in a suburban general population in China.

OBJECTIVE: To explore the association of hypertension and carotid atherosclerosis in a general population in China. METHODS: A population-based cardiovascular epidemiology survey was performed in a total of 1198 residents in suburban Beijing, 426 men and 776 women aged 43-73 years. Carotid plaque and the intima-media thickness were measured using duplex ultrasound. RESULTS: The intima-media thickness, the prevalence of plaque and the number of plaques were found significantly positively related to hypertension categories (optimal, normal, high-normal, stage 1, 2 and 3 hypertension, according to The Chinese Hypertension Guidelines) as well as to the duration of hypertension, with a dose-response pattern in both genders (trend test, P < 0.01). After adjustment for age, total cholesterol, high-density lipoprotein-cholesterol, fasting glucose, smoking, antihypertensive treatment, stroke, myocardial infarction and angina, the relationship still existed, particularly in women. The associations of carotid atherosclerosis with duration of hypertension were weakened by further adjustment for systolic blood pressure, diastolic blood pressure or hypertension categories. CONCLUSION: Hypertension was associated with subclinical carotid atherosclerosis. A prolonged course of the disease may aggravate the carotid atherosclerosis, independently of the level of blood pressure.

Adult↗

PubMed2004

[Hypertension and subclinical carotid atherosclerosis in a general population of a rural areas in China].

OBJECTIVE: To explore the association of hypertension and carotid atherosclerosis in a general population in China. METHODS: A population-based epidemiological survey on cardiovascular diseases was performed in autumn, 2002. A total of 1198 rural residents with 426 men and 776 women aged 43 - 73 years, underwent carotid duplex examination. Hypertension was classified into 6 groups of optimal, normal, high-normal, stage 1, 2 and 3. RESULTS: (1) A significant positive dose-response relation was found between hypertension categories, duration of hypertension and intima-media thickness (IMT) in both genders (trend test P < 0.01). After adjustment of age, body mass index, total cholesterol, high density lipoprotein cholesterol, glucose and smoking, the relation did not change. The associations between duration of hypertension and IMT disappeared after further adjustment with blood pressure. (2) The occurrence of plaque was positively associated with blood pressure groups and duration of hypertension, as well as in the age-adjusted models. The associations between duration of hypertension and plaque weakened or disappeared after further adjustment with systolic blood pressure, diastolic blood pressure or hypertension categories. CONCLUSION: Hypertension was associated with subclinical carotid atherosclerosis. Prolonged course of disease might aggravate the carotid atherosclerosis.

Adult↗

PubMed2003

Use of partition coefficients to predict mixture toxicity.

By using the C(18)-Empore disks/water partition coefficient (K(MD)) to describe the toxicity of 50 mixed halogenated benzenes to Photobacterium phosphoreum, an approach is proposed in this study. Application of the approach to the 15 other related mixtures prove the predictive capability of this K(MD)-based approach, due to the consistency between the predicted toxicity and the observed ones with r(2)=0.929, SE=0.104, F=169.513 at P<0.001. Further analysis of this approach finds that, for the mixtures, although the toxicity is highly correlated with their hydrophobicity, this correlation is free from the range difference of the hydrophobicity, the ratio or the number of the individual chemicals. These analysis results suggest that this K(MD)-based approach is able to predict the toxicity of mixture pollutants in wastewater.

Benzene Derivatives↗

PubMed2003

Development of QSARs for predicting the joint effects between cyanogenic toxicants and aldehydes.

Quantitative structure-activity relationship (QSAR) approaches are proposed in this study to predict the joint effects of mixture toxicity. The initial investigation studies the joint effects between cyanogenic toxicants and aldehydes to Photobacterium phosphoreum. Joint effects are found to result from the formation of a carbanion intermediate produced through the chemical interactions between cyanogenic toxicants and aldehydes. Further research indicates that the formation of carbanion intermediate is highly correlated with not only the charge of the carbon atom in the -CHO of aldehydes but also the charge of the carbon atom (C) in the carbochain of cyanogenic toxicants. The charge of the carbon atom in the -CHO of aldehydes is quantified by using the Hammett constant (sigma(p)), and then, sigma(p)-based QSAR models are proposed to describe the relationships between the joint effects and the chemical structures of the aldehydes. By using the charge of carbon atom (C) in the carbochain of cyanogenic toxicants, another QSAR model is proposed to describe the relationship between the joint effects and the chemical structures of cyanogenic toxicants.

Aldehydes↗

PubMed2003

Application of remote sensing techniques for monitoring the thermal pollution of cooling-water discharge from nuclear power plant.

This article introduces a practical method to investigate thermal pollution in coastal water from satellite data. The intensity and distribution areas of thermal pollution by the heated effluent discharge from the nuclear power plant on Daya Bay, southern China were investigated by using Landsat-5 Thematic Mapper (TM) thermal band data from 1994 to 2001. A local algorithm was developed, based on sea-truth data of water surface temperature measured when the satellite passed over the study area. The local algorithm was then applied to estimate water temperature from TM data. It shows that the remote sensing technique provides an effective means to quantitatively monitor the intensity of thermal pollution and to retrieve a very detailed distribution pattern of thermal pollution in coastal waters. The remotely-sensed results of the thermal pollution can be used for environmental management of coastal waters.

Algorithms↗