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Biomedical subjects

Ping Xie

Publications and source records attributed to Ping Xie.

At least 37 records · Page 2Linked to original sources
PubMed2006

[Determining the relationship between coronary artery and coronary sinus and its tributaries using multislice computed tomography].

OBJECTIVE: To obtain the coronary artery and coronary sinus (CS) and its tributaries imaging with multislice computed tomography (MSCT), measure the distance between coronary artery and CS and its tributaries and analyze their spatial relationships. METHODS: The MSCT scans of 117 patients (67 men, 50 women, age 56 +/- 10 years) were obtained, 3D image reconstructed and the vessels courses evaluated. The concomitant distances and spatial relationships of the vessels were determined. RESULTS: Right coronary artery domination was found in 107 cases (91.4%), left coronary artery domination in 7 cases (6.0%), and co-domination in 3 cases (2.6%). Left circumflex artery (LCX) was concomitant with CS or the great cardiac vein (GCV) in 81 cases (69.2%), intersected with left posterior vein in 62 cases (53.0%) and with middle cardiac vein (MCV) in 5 cases (4.3%), respectively. The dominant coronary artery branched out into the posterior descending artery (PDA) and the left posterior artery (LPA) in 112 cases (95.7%). PDA was concomitant with MCV in 93 cases (79.5%) and intersected with MCV in 44 cases (37.6%). LPA was intersected with MCV in 106 cases (90.6%), and concomitant with CS in 50 cases (42.7%). CONCLUSIONS: MSCT is a reliable tool to visualize the relationship between coronary artery and CS and its tributaries. Owing to the multiple possibilities inherent to this technique, MSCT has broad potential for more clinical use.

Adult↗
PubMed2006

[Relation between glucosylceramide synthase and multidrug resistance in leukemia cells].

This study was purposed to explore the expression of glucosylceramide synthase (GCS) in human leukemia cells and its relationship with multidrug resistance. RT-PCR was used to analyze peripheral blood samples from 53 leukemia patients with multidrug resistance/non-resistance, and to detect the expression level of GCS gene in HL-60 cells and HL-60/ADR cells, the expression level was compared with the level of mdr-1. The expressions of GCS protein and P-gp protein in HL-60 cells and HL-60/ADR cells were assayed by Western blot analysis. The results showed that the relative optical density ratio of GCS gene amplified bands in samples of leukemia patients with drug-resistance was significantly higher than that in samples of leukemia patients with drug non-resistance group (P < 0.05), meanwhile the significant enhancement of optical density value of GCS gene amplified bands accompanied by high expression of mdr-1 gene. Their correlation showed positive (P < 0.01, r = 0.6). The GCS mRNA and protein were overexpressed in HL-60/ADR cells, and their expression levels were obviously higher than that in HL-60 cells, meanwhile the expression of mdr-1 mRNA and P-gp also significantly increased in HL-60/ADR cells. It is concluded that the high level of GCS in leukemia patients possibly is associated with multidrug resistance of leukemia cells.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2005

Model for kinetics of myosin-V molecular motors.

A hand-over-hand model is presented for the processive movement of myosin-V based on previous biochemical experimental results and structural observations of nucleotide-dependent conformational changes of single-headed myosins. The model shows that the ADP-release rate of the trailing head is much higher than that of the leading head, thus giving a 1:1 mechanochemical coupling for the processive movement of the motor. It explains well the previous finding that some 36-nm steps consist of two substeps, while other 36-nm steps consist of no substeps. Using the model, the calculated kinetic behaviors of myosin-V such as the main and intermediate dwell time distributions, the load dependence of the average main and intermediate dwell time and the load dependence of occurrence frequency of the intermediate state under various nucleotide conditions show good quantitative agreement with previous experimental results.

Kinetics↗
PubMed2005

Model for kinetics of wild-type and mutant kinesins.

A hand-over-hand model is presented for the processive movement of two-headed kinesin based on previous structural and biochemical studies. In the model, the ATPase activities of the two heads are regulated by forces, both from internal elasticity and external load, exerted on their neck linkers. The results from the model show that the two heads may be partially coordinated in their ATPase cycles: in the case of backward load or low forward load, the ATPase cycles of its two heads are well coordinated, whereas in the case of high forward load, they are no longer well coordinated. The model gives results that show good quantitative agreement with both previous biochemical and mechanical experimental results such as the limping of homodimers and the dependences of mean velocity on [ATP] and on loads (both positive and negative). Furthermore, using the model we study the kinetics of a number of mutant kinesin homodimers and heterodimers, showing that the two heads' ATPase activities of some of these molecules are not well coordinated and they move processively with low mechanochemical coupling efficiencies even under no load. The theoretical results of ATPase rate per head, moving velocity, and stall force of the motors show good quantitative agreement with the experimental ones. The puzzling dynamic behaviours of mutant homodimeric and heterodimeric kinesins become understandable.

Adenosine Triphosphatases↗
PubMed2005

Modulation of renal-specific oxidoreductase/myo-inositol oxygenase by high-glucose ambience.

Biological properties of renal-specific oxidoreductase (RSOR), characteristics of its promoter, and underlying mechanisms regulating its expression in diabetes were analyzed. RSOR expression, normally confined to the renal cortex, was markedly increased and extended into the outer medullary tubules in db/db mice, a model of type 2 diabetes. Exposure of LLCPK cells to d-glucose resulted in a dose-dependent increase in RSOR expression and its enzymatic activity. The latter was related to one of the glycolytic enzymes, myo-inositol oxygenase. The increase in activity was in proportion to serum glucose concentration. The RSOR expression also increased in cells treated with various organic osmolytes, e.g., sorbitol, myoinositol, and glycerolphosphoryl-choline and H(2)O(2). Basal promoter activity was confined to -1,252 bp upstream of ATG, and it increased with the treatment of high glucose and osmolytes. EMSAs indicated an increased binding activity with osmotic-, carbohydrate-, and oxidant-response elements in cells treated with high glucose and was abolished by competitors. Supershifts, detected by anti-nuclear factor of activated T cells, and carbohydrate-response-element-binding protein established the binding specificity. Nuclear factor of activated T cells tonicity-enhancer-binding protein and carbohydrate-response-element-binding protein had increased nuclear expression in cells treated with high glucose. The activity of osmotic-response element exhibited a unique alternate binding pattern, as yet unreported in osmoregulatory genes. Data indicate that RSOR activity is modulated by diverse mechanisms, and it is endowed with dual properties to channel glucose intermediaries, characteristic of hepatic aldehyde reductases, and to maintain osmoregulation, a function of renal medullary genes, e.g., aldose reductase, in diabetes.

Animals↗
PubMed2005

Inhibition of progesterone receptor activity in recombinant yeast by soot from fossil fuel combustion emissions and air particulate materials.

Numerous environmental pollutants have been detected for estrogenic activity by interacting with the estrogen receptor, but little information is available about their interactions with the progesterone receptor. In this study, emission samples generated by fossil fuel combustion (FFC) and air particulate material (APM) collected from an urban location near a traffic line in a big city of China were evaluated to interact with the human progesterone receptor (hPR) signaling pathway by examining their ability to interact with the activity of hPR expressed in yeast. The results showed that the soot of a petroleum-fired vehicle possessed the most potent anti-progesteronic activity, that of coal-fired stove and diesel fired agrimotor emissions took the second place, and soot samples of coal-fired heating work and electric power station had lesser progesterone inhibition activity. The anti-progesteronic activity of APM was between that of soot from petroleum-fired vehicle and soot from coal-fired establishments and diesel fired agrimotor. Since there was no other large pollution source near the APM sampling sites, the endocrine disrupters were most likely from vehicle emissions, tire attrition and house heating sources. The correlation analysis showed that a strong relationship existed between estrogenic activity and anti-progesteronic activity in emissions of fossil fuel combustion. The discoveries that some environmental pollutants with estrogenic activity can also inhibit hPR activity indicate that further studies are required to investigate potential mechanisms for the reported estrogenic activities of these pollutants.

Air Pollutants↗
PubMed2005

Nondegenerate two-beam coupling in Kerr nonlinear photonic crystals.

We show that the energy-transfer efficiency by nondegenerate two-beam coupling in a one-dimensional Kerr-nonlinear superlattice can be enhanced by several orders of magnitude as compared with that in a homogeneous medium of the same nonlinearity and length. This significant enhancement utilizes the strong localized field at the band-edge state, two-frequency localized state, or defect state. Due to the intensity-induced index modulation, the bistability is observed, and because of the energy transfer between different wavelength components, the tristability behavior is induced.

Journal Article↗
PubMed2005

Cell biology of diabetic kidney disease.

In large part cellular dysfunctions induced by chronic hyperglycemia are similar in type-1 and -2 diabetes. In both instances chronic hyperglycemia induces injury to a multitude of organs by affecting various target cells. The cells affected may include those derived from of epithelial or mesenchymal progenitors; and at times hyperglycemia may induce phenotypic changes with epithelial-mesenchymal transformation. In the majority of target cells the high-glucose ambience activates various intracellular pathways that are similar except for minor exceptions that are related to the selective expression of various molecules in a given cell type. Keeping in perspective a common paradigm applicable to most of the cells, a brief discussion of different hyperglycemia-induced cellular events pertaining to various pathways is described in this review. They include fluxes of glucose intermediaries in various cellular metabolic pathways, generation of advanced glycation end products (AGEs) and their extra- and intracellular effects, the role of protein kinase C, transforming growth factor-beta, guanosine triphosphate-binding proteins and reactive oxygen species (ROS) in various cellular signaling events. The latter, i.e., ROS, may be central to several intracellular pathways and modulate various events in a reciprocal manner. The information compiled under various subtitles of this synopsis is derived from an enormous amount of literature data summarized in several recent excellent reviews, and thus further reading of them is suggested to gather detailed comprehensive information on each of the subjects.

Animals↗
PubMed2005

LMP1 protein from the Epstein-Barr virus is a structural CD40 decoy in B lymphocytes for binding to TRAF3.

Epstein-Barr virus is a human herpesvirus that causes infectious mononucleosis and lymphoproliferative malignancies. LMP1 (latent membrane protein-1), which is encoded by this virus and which is essential for transformation of B lymphocytes, acts as a constitutively active mimic of the tumor necrosis factor receptor (TNFR) CD40. LMP1 is an integral membrane protein containing six transmembrane segments and a cytoplasmic domain at the C terminus that binds to intracellular TNFR-associated factors (TRAFs). TRAFs are intracellular co-inducers of downstream signaling from CD40 and other TNFRs, and TRAF3 is required for activation of B lymphocytes by LMP1. Cytoplasmic C-terminal activation region 1 of LMP1 bears a motif (PQQAT) that conforms to the TRAF recognition motif PVQET in CD40. In this study, we report the crystal structure of this portion of LMP1 C-terminal activation region-1 (204PQQATDD210) bound in complex with TRAF3. The PQQAT motif is bound in the same binding crevice on TRAF3 where CD40 is bound, providing a molecular mechanism for LMP1 to act as a CD40 decoy for TRAF3. The LMP1 motif is presented in the TRAF3 crevice as a close structural mimic of the PVQET motif in CD40, and the intermolecular contacts are similar. However, the viral protein makes a unique contact: a hydrogen bond network formed between Asp210 in LMP1 and Tyr395 and Arg393 in TRAF3. This intermolecular contact is not made in the CD40-TRAF3 complex. The additional hydrogen bonds may stabilize the complex and strengthen the binding to permit LMP1 to compete with CD40 for binding to the TRAF3 crevice, influencing downstream signaling to B lymphocytes and contributing to dysregulated signaling by LMP1.

Alanine↗
PubMed2005

Use of PFU protozoan community structural and functional characteristics in assessment of water quality in a large, highly polluted freshwater lake in China.

Structural and functional parameters of protozoan communities colonizing on PFU (polyurethane foam unit) artificial substrate were assessed as indicators of water quality in the Chaohu Lake, a large, shallow and highly polluted freshwater lake in China. Protozoan communities were sampled 1, 3, 6, 9 and 14 days after exposure of PFU artificial substrate in the lake during October 2003. Four study stations with the different water quality gradient changes along the lake were distinguishable in terms of differences in the community's structural (species richness, individual abundance, etc.) and functional parameters (protozoan colonization rates on PFU). The concentrations of TP, TN, COD and BOD as the main chemical indicators of pollution at the four sampling sites were also obtained each year during 2002-2003 for comparison with biological parameters. The results showed that the species richness and PFU colonization rate decreased as pollution intensity increased and that the Margalef diversity index values calculated at four sampling sites also related to water quality. The three functional parameters based on the PFU colonization process, that is, S(eq), G and T90%, were strongly related to the pollution status of the water. The number of protozoan species colonizing on PFU after exposure of 1 to 3 days was found to give a clear comparative indication of the water quality at the four sampling stations. The research provides further evidence that the protozoan community may be utilized effectively in the assessment of water quality and that the PFU method furnishes rapid, cost-effective and reliable information that may be useful for measuring responses to pollution stress in aquatic ecosystems.

Animals↗
PubMed2005

Adult islets cultured in collagen gel transdifferentiate into duct-like cells.

AIM: To establish a model of islet-ductal cell transdifferentiation to identify the transdifferentiated cells. METHODS: Collagen was extracted from rat tail at first. Purified rat islets were divided into three groups, embedded in collagen gel and incubated respectively in DMEM/F12 alone (control group), DMEM/F12 plus epidermal growth factor (EGF), DMEM/F12 plus EGF and cholera toxin (CT). Transdifferentiation was proved by microscopy, RT-PCR, immunohistochemistry and RIA. RESULTS: Islets embedded in collagen gel plus EGF and CT were cystically transformed and could express new gene cytokeratin 19 while still maintaining the expression of insulin and Pdx-1 genes. Immunohistochemistry demonstrated that the protein of cytokeratin 19 was only expressed in the third group. The insulin content secreted by islets in the third group decreased significantly during the transdifferentiation. CONCLUSION: CT is a crucial factor for the islet-ductal cell transdifferentiation.

Age Factors↗
PubMed2005

Hyperglycemia: its imminent effects on mammalian nephrogenesis.

A sustained exposure of the mammalian embryo to very high glucose ambience is associated with a multitude of congenital birth defects, including those of the cardiovascular, CNS, skeletal and urogenital systems during the first 6-8 weeks of gestation in humans. These urogenital abnormalities may be associated with "caudal regression syndrome" or may occur alone in the form of partial or total renal agenesis. Similarly, an increase in the incidence of morphogenetic defects is observed in the offspring of streptozotocin-induced diabetic rats and mice, and also in non-obese diabetic mice. In certain cases, failure during the growth of the lower parts of embryos or newborn mice involving the genitourinary system has been observed in animals with severe diabetes. Investigators have utilized whole organ culture systems to delineate the mechanisms relevant to dysmorphogenesis of the embryonic metanephros. A marked dysmorphogenesis of the metanephros is observed upon treatment with a high concentration of D: -glucose. Associated with it are changes that include branching dysmorphogenesis of the ureteric bud iterations, reduced population of nascent nephrons, decreased expression of basement membrane proteoglycans, depletion of ATP stores, and fulminant apoptosis of the cells at the interface of mesenchyme and ureteric bud epithelium. The latter findings suggest that disruption of epithelial:mesenchymal interactions may be the major event responsible for the metanephric dysmorphogenesis induced by high glucose ambience.

Animals↗
PubMed2005

Evaluation of soot particles of biomass fuels with endocrine-modulating activity in yeast-based bioassay.

Exposure to indoor air pollution (IAP) from the combustion of biomass fuels is an important cause of morbidity and mortality in developing countries. In the work discussed in this paper we evaluated the endocrine activity of soot particles from biomass fuels by using yeast bioassay. These pollutants could have beta-galactosidase activity with a relative potency (RP) about 10(-7)-10(-9) that of estradiol. Soot particles from wood and straw combustion only partially induced beta-galactosidase activity whereas others produced fully inductive activity in the yeast assay system. These pollutants did not have estrogen antagonist and progesterone agonist activity within the defined concentration range. However, these pollutants require 2-4 orders of magnitude higher IC50 to inhibit the activity of progesterone in a similar dose-response manner to mifepristone. We therefore propose that the endocrine activity of some environmental pollutants may be because of inhibition of the progesterone receptor (hPR). GC-MS results showed that substituted polycyclic aromatic hydrocarbon (PAH) compounds, substituted phenolic compounds and derivatives, aromatic carbonyl compounds, and phytosteroids in these soot particles may be mimicking endogenous hormones.

Air Pollutants↗
PubMed2005

Large enhancement of third-harmonic generation induced by coupled gap solitons in chi(3) nonlinear photonic crystals.

It is shown that, in a chi((3)) nonlinear photonic crystal, the third-harmonic conversion efficiency can be enhanced by about three orders of magnitude via the formation of self-organized localized states inside the gaps as compared with that in a bulk medium of the same length with a perfect phase-matching condition. These localized states contain both the fundamental and third-harmonic frequencies located in different gaps. Their existence is a result of both the Kerr effect and the large energy transfer between fundamental and third-harmonic waves.

Journal Article↗
PubMed2005

Organ distribution and bioaccumulation of microcystins in freshwater fish at different trophic levels from the eutrophic Lake Chaohu, China.

This article reports the organ distribution and bioaccumulation of hepatotoxic microcystins (MCs) in freshwater fishes at different trophic levels from the large, shallow, eutrophic Lake Chaohu in September 2003, when there were heavy surface blooms of toxic cyanobacteria. Among all fish, intestines and blood had the highest average content of MC-RR + MC-LR (22.0 and 14.5 microg g(-1) DW, respectively), followed by liver, bile, and kidney (7.77, 6.32, and 5.81 microg g(-1) DW, respectively), whereas muscle had the least (1.81 microg g(-1) DW). MC content in muscle was highest in carnivorous fish (Culter ilishaeformis, 2.22 microg g(-1) DW) and omnivorous fish (Carassius auratus, 1.96 microg g(-1) DW) and was lowest in phytoplanktivorous fish (Hypophthalmichthys molitrix, 1.65 microg g(-1) DW) and herbivorous fish (Parabramis pekinensis 0.660 microg g(-1) DW). However, the amount of MC in the gut of H. molitrix (137 microg g(-1) DW) was more than 20 times that in the other fish (<6.50 microg g(-1) DW). The MCs showed a tendency to accumulate up the food chain, and piscivorous fish at the top of the food chain were at high risk of exposure to MCs in Lake Chaohu. Our study is the first to report MC concentrations in the bile and blood of wild fish. One hundred grams of fish muscle would contain 2.64-49.7 microg of MC-LR equivalent, or about 1.3-25 times the recommended tolerable daily intake of MC-LR by humans, indicating that fish are already severely contaminated by MCs and that the local authorities should warn the public of the risk of poisoning by eating the contaminated fish.

Animals↗
PubMed2005

Seasonal dynamics of the hepatotoxic microcystins in various organs of four freshwater bivalves from the large eutrophic lake Taihu of subtropical China and the risk to human consumption.

So far, little is known on the distribution of hepatotoxic microcystin (MC) in various organs of bivalves, and there is no study on MC accumulation in bivalves from Chinese waters. Distribution pattern and seasonal dynamics of MC-LR, -YR and -RR in various organs (hepatopancreas, intestine, visceral mass, gill, foot, and rest) of four edible freshwater mussels (Anodonta woodiana, Hyriopsis cumingii, Cristaria plicata, and Lamprotula leai) were studied monthly during Oct. 2003-Sep. 2004 in Lake Taihu with toxic cyanobacterial blooms in the summer. Qualitative and quantitative determinations of MCs in the organs were done by LC-MS and HPLC. The major toxins were present in the hepatopancreas (45.5-55.4%), followed by visceral mass with substantial amount of gonad (27.6-35.5%), whereas gill and foot were the least (1.8-5.1%). The maximum MC contents in the hepatopancreas, intestine, visceral mass, gill, foot, and rest were 38.48, 20.65, 1.70, 0.64, 0.58, and 0.61 microg/g DW, respectively. There were rather good positive correlation in MC contents between intestines and hepatopancreas of the four bivalves (r=0.75-0.97, p<0.05). There appeared to be positive correlations between the maximum MC content in the hepatopancreas and the delta13C (r=0.919) or delta15N (r=0.878) of the foot, indicating that the different MC content in the hepatopancreas might be due to different food ingestion. A glutathione (GSH) conjugate of MC-LR was also detected in the foot sample of C. plicata. Among the foot samples analyzed, 54% were above the provisional WHO tolerable daily intake (TDI) level, and the mean daily intakes from the four bivalves were 8-23.5 times the TDI value when the bivalves are eaten as a whole, suggesting the high risk of consuming bivalves in Lake Taihu.

Animals↗
PubMed2005

Tissue distributions and seasonal dynamics of the hepatotoxic microcystins-LR and -RR in a freshwater snail (Bellamya aeruginosa) from a large shallow, eutrophic lake of the subtropical China.

Tissue distributions and seasonal dynamics of the hepatotoxic microcystins-LR and -RR in a freshwater snail (Bellamya aeruginosa) were studied monthly in a large shallow, eutrophic lake of the subtropical China during June-November, 2003. Microcystins (MCs) were quantitatively determined by High-Performance Liquid Chromatography (HPLC) with a qualitative analysis by a Finnigan LC-MS system. On the average of the study period, hepatopancreas was the highest in MC contents (mean 4.14 and range 1.06-7.42 microg g(-1)DW), followed by digestive tracts (mean 1.69 and range 0.8-4.54 microg g(-1)DW) and gonad (mean 0.715 and range 0-2.62 microg g(-1)DW), whereas foot was the least (mean 0.01 and range 0-0.06 microg g(-1)DW). There was a positive correlation in MC contents between digestive tracts and hepatopancreas. A constantly higher MC content in hepatopancreas than in digestive tracts indicates a substantial bioaccumulation of MCs in the hepatopancreas of the snail. The average ratio of MC-LR/MC-RR showed a steady increase from digestive tracts (0.44) to hepatopancreas (0.63) and to gonad (0.96), suggesting that MC-LR was more resistant to degradation in the snail. Since most MCs were present in the hepatopancreas, digestive tracts and gonad with only a very small amount in the edible foot, the risk to human health may not be significant if these toxic parts are removed prior to snail consumption. However, the possible transference of toxins along food chains should not be a negligible concern.

Animals↗