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C Zheng

Publications and source records attributed to C Zheng.

At least 55 records · Page 3Linked to original sources
PubMed2001

[Auto-detection of contour in echocardiographic images based on active contour model].

Contour detection is one of the most difficult problems in the multi-dimensional reconstruction of echocardiographic images. A method based on active contour model is presented in the present paper to solve this problem. First, according to the characteristic of the ultrasonic medical images, an adaptive weighted median filter is used to suppress speckle noise and an adaptive threshold value is selected to get binary image. Then, mathematical morphological treatment is utilized to get the initial contour. At last, active contour model is employed to revise the initial contour and get the accurate final contour. Experiments with real and interpolated ultrasonic images are presented. The results show the effectiveness of this method. This method has practical use in the multi-dimensional reconstruction of ultrasonic medical images.

Algorithms↗
PubMed2001

Metabolites of the L-arginine-NO pathway in patients with left-to-right shunt.

OBJECTIVES: The endogenous production of metabolites of the L-arginine-NO pathway has been found to be altered in patients with left-to-right shunt and pulmonary hypertension. The objective of this study was to analyze the influence of age and of the magnitude of the left-to-right shunt on plasma levels of L-arginine, cyclic guanosine monophosphate (cGMP), nitrite and nitrate in children and young adults presenting with left-to-right shunt. METHODS: Twenty-nine patients with ventricular septal defect (n=18), atrial septal defect (n=6) and atrioventricular canal (n=5) were assigned to group I when the ratio of pulmonary to systemic blood flow (Qp/Qs) was less than 1.5 (n=10) and to group II when Qp/Qs > or = 1.5 (n=19). At cardiac catheterization blood samples were taken from the pulmonary vein or left ventricle. In 33 controls peripheral venous blood was obtained. cGMP levels were determined by radioimmunoassay, L-arginine, nitrite and nitrate by high performance liquid chromatography (HPLC). RESULTS: L-arginine plasma levels were lower in group II than in controls (51.7 [23.3-82.2] versus 60.5 [32.4-85.9] pmol/l; p < 0.05 by KRUSKAL-WALLIS). Age did not influence the L-arginine plasma levels (p = 0.30). cGMP levels depended on age (p<0.01) and mean pulmonary artery pressure (p <0.01) but not on high pulmonary blood flow (p=0.85; ANOVA). Plasma nitrite and nitrate were not different in both groups and when compared with controls (nitrite: 26.0 [23.5-31.0] micromol/l; nitrate: 26.8 [24.0-32.0] micromol/l). CONCLUSIONS: Age and pulmonary artery pressure exert important effects on plasma cGMP. Measurement of nitrite and nitrate in plasma alone may not reflect the endogenous NO production. Future studies should evaluate the role of plasma levels of L-arginine in patients with high pulmonary blood flow undergoing repair of their defect.

Adolescent↗
PubMed2001

[Study on preparation and properties of moisture permeable polyurethane membrane used for dressings].

A new hydrophilic polyurethane(PU) performed-polymer has been developed with polyethylene glycol(PEG) instead of general polyether. The solution of performed-polymer is poured casting a permeable membrane used for the outer layer of the bilayer dressings. The effects of molecular weigh (Mn) of PEG, the usage of cross-link agents, solvents and water in the solution on the moisture permeation of PU membrane have been studied. It has been shown that the membrane prepared is a porous moisture permeable membrane. The optimum conditions of preparing membrane are: Mn of PEG is 2,000-4,000, the mixture of acetone and N,N-dimethylformamide (DMF) is used as solvents, and the temperature of performance membrane is 50 degrees C-80 degrees C. The moisture permeability of the PU membrane is 49-60 g/m2.h at 35 degrees C, which can meet the requirement of the wound dressings. In addition, the mechanism of the moisture permeation of PU membrane has been discussed.

Bandages↗
PubMed2001

[Detection of spikes in epileptic EEG based on Multiresolution Tsallis' entropy].

In this paper, the detection of the spikes in the epileptic EEG signal was studied based on Multiresolution Tsallis' entropy (MRET). First, EEG signals were decomposed into wavelet series, and then, at every scale, the abnormal spikes were distinguished from normal background EEG activities by using MRET. The analysis of 6 patients' EEG data showed that the abnormal epileptiform spikes in EEG can be accurately detected with this method, which opens up the perspectives of building up automatic detection devices for spikes in EEG. Compared with the Shannon entropy, the MRET provides one with more detailed information.

Electroencephalography↗
PubMed2001

[Effect of organic acids on soil chemical behavior of lead and cadmium and their toxicity to plants].

The interaction between organic acids (citric and oxalic acids) and heavy metals was examined in this paper. Equilibrium dialysis showed that the extent organic acids bound metals depended on the metal involved, and their binding properties affected the adsorption of Pb and Cd by soil, which was increased in the presence of oxalic acid, and decreased in the presence of citric acid. The effect of citric acid on the behavior and toxicity of Pb and Cd to plants was also studied. The presence of citric acid could reduce the toxicity of Pb, and inhibit the uptake of Cd in shoots and roots. However, there was no significant effect on the apparent toxicity of Cd. The interaction between Pb and Cd was found to be complicated. The Pb content in rice was higher in the presence of Cd, while the content of Cd is lower in the presence of Pb.

Aconitic Acid↗
PubMed2001

[The CPBC types used for clinical choice and observation on their microstructure].

UNLABELLED: According to the primary properties of calcium phosphate bone cement (CPBCs), we have chosen certain types of them for use in cranioplasty and have observed the microstructure of their set bodies by means of SEM. Five kinds of CPBCs powder have been prepared, including: octacalcium phosphate precipitated hydroxyapatite (OCP-PHA) type, octacalcium phosphate hydroxyapatite (OCP-HA) type, octacalcium phosphate (OCP) type, calcium deficient hydroxyapatite (CDHA) type and hydroxyapatite (HA) type. The mixing liquids were deionized water and 0.25 M Na2HPO4/NaH2PO4 buffer solution. The setting time was measured by Gillmore method. The compressive strengths were measured using the TS-14 automatically measured instrument-II of single granule's compressive strength. The CPBC types used for clinical cranioplasty were defined according to Ginebra's Criteria of the CPBCs, and the ultrastructure of the set-bodies of the defined CPBC type was observed by SEM before and after its immersion in Ringer's Solution. RESULT: Two out of five CPBCs, OCP-PHA-CPBC and CDHA-CPBC were selected for clinical cranioplasty. Before and after they were immersed in Ringer's Sol., the SEM found their set-bodies to be structurally porous and to dissolve with the increase of immension time. These data indicate that OCP-PHA-CPBC and CDHA-CPBC are sufficient for the reconstruction of non-stress-bearing bone, and the porous structure of their set-bodies is advantageous to fibroplasty or fibrovasculization in their set bodies.

Bone Cements↗
PubMed2001

[The preliminary report of cervical cancer treated with californium-252 neutron after loading intracavitary radiotherapy].

OBJECTIVE: To observe the therapeutic effectiveness and complications of californium-252 (252Cf) brachytherapy in cervical cancer. METHODS: Fifty one cases of cervical cancer were diagnosed according to the standard of the International Federation of Gynecology and Obstetrics (FIGO), II a:8 cases, II b:31 cases, III a:8 cases, III b:4 cases. Treatment schedule: 252Cf after loading brachytherapy, 10-12 Gy/fraction/week, the total dose of reference point A was 36-40 Gy in three to four implant sessions. In the second day after 252Cf therapy, the whole pelvis was treated with 6 MV X-ray external beam radiotherapy, 200 cGy per fraction, 4 times per week. The total dose of external beam radiotherapy was 40 to 50 Gy (the middle of pelvis was blocked at width of 4 cm after 20-30 Gy), then the total dose of reference point B was 50-55 Gy;the total treatment time was 5-6 weeks. RESULTS: The average time of complete tumor regression was 25 days, the local control rate of 2 year was 100%, the total 2 year survival rate was 92%, i.e., II a: 8/8 cases, II b: 30/31 cases (97%), III a: 6/8 cases, III b: 3/4 cases; the late radiation complications of bladder and rectum was 2% respectively during these 2 years. CONCLUSIONS: It is concluded that combined 252 Cf brachytherapy and high energy X-ray external beam radiotherapy may be safe and effective in the management of cervical cancer. 252Cf has advantages of high local control rate; rapidly regression of bulky tumors and low-grade radiation complications.

Brachytherapy↗
PubMed2000

Frequent amplification of the telomerase reverse transcriptase gene in human tumors.

Activation of telomerase is a crucial step during cellular immortalization and malignant transformation of human cells and requires the induction of the catalytic component, human telomerase reverse transcriptase (hTERT), encoded by the hTERT gene. It is poorly understood how the hTERT gene is activated in human cancer cells. In the present study, we examined the hTERT gene copy number in human cancer cell lines and in primary tumor tissues. Amplification of the hTERT gene was observed in 8 of 26 (31%) tumor cell lines and 17 of 58 (30%) primary tumors examined (8 of 21 lung tumors, 3 of 10 cervical tumors, 5 of 19 breast carcinomas, and 1 of 8 neuroblastomas). In addition, 13 of 26 (50%) cell lines and 13 of 58 (22%) primary tumors displayed gain of hTERT gene copies with 3-4 copies/cell. The present findings imply that the hTERT locus may be a frequent target for amplification during tumorigenesis and that this genetic event probably contributes to the dysregulation of telomerase activity occurring in human tumors.

Catalytic Domain↗
PubMed2000

Two-dimensional molecular layers: interplay of H-bonding and van der waals interactions in the self-assembly of N,N'-dialkylsulfamides

N,N'-Dialkylsulfamide molecules assemble into solid-state structures consisting of 2D layers. The 2D layers are based on a hydrogen-bonded network of the sulfamide groups and the close-packing of alkyl groups on both sides of the 2D H-bonded network. The thickness of a 2D layer is proportional to the size of the alkyl substituents. The interplay of H-bonding and van der Waals interactions leads to stable 2D layers that pack into 3D structures.

Journal Article↗
PubMed2000

Adenoviral vector cytotoxicity depends in part on the transgene encoded.

First-generation adenoviral vectors induce G(2)/M arrest and cell death at high multiplicities of infection (m.o.i.'s) in vitro. It is unclear whether this cytotoxicity is entirely adenoviral gene related or influenced in part by the encoded transgene. We examined this question in epithelial cells using seven vectors at relatively low (50) or higher (200) m.o.i.'s. The vectors contained no transgene (+/-promoter), transgenes encoding a cytoplasmic reporter protein (two luciferase constructs; beta-galactosidase), or transgenes encoding a secretory protein (alpha1-antitrypsin; growth hormone). After 24 h with a m.o.i. of 50, vectors encoding cytoplasmic reporter proteins led to greatest cytotoxicity (approximately 35-40% cells in G(2)/M). Vectors without a transgene resulted in lower cytotoxicity (approximately 15%, minus, or 23%, plus promoter, cells in G(2)/M). Vectors encoding secretory proteins led to approximately 22-25% cells in G(2)/M. A similar pattern resulted when cell number was measured. Results were unrelated to the steady-state levels of transgene product. At the higher m.o.i., all vectors caused substantial growth retardation. This is the first demonstration that adenoviral vector-induced cytotoxic effects are in part related to the transgene encoded.

Adenoviridae↗
PubMed2000

Mutation analysis of replicative genes encoding the large subunits of DNA polymerase alpha and replication factors A and C in human sporadic colorectal cancers.

We examined cDNAs of the catalytic subunit of DNA polymerase alpha (185 kDa), the 70 kDa subunit of replication protein A (single-stranded DNA-binding protein) and the 140 kDa subunit of replication factor C for mutations. Surgical specimens from 12 patients with sporadic colon cancer and normal mucosae from the same patients were investigated. In addition, we analyzed 3 human colon cancer cell lines that exhibited defects in mismatch repair (DLD-1, HCT116, SW48) and 3 colon cancer cell lines without such a defect (HT29, SW480 and SW620). For detection of mutations, we used reverse transcription of mRNA, amplification of cDNAs by PCR, analysis of single-strand conformation polymorphism and DNA sequencing. Eleven colon cancers and 6 colon cancer cell lines were analyzed for DNA polymerase alpha. Only 2 silent point mutations were detected, in 1 colon carcinoma and in cell line HCT116. Two sequence alterations of the 70 kDa subunit of replication factor A were identified in 15 specimens (9 colon carcinomas and 6 cell lines). Colon carcinomas from 2 patients (CC5MA and CC25HN) exhibited an ACA-->GCA transition in codon 351, which caused a Thr-->Ala exchange. In carcinomas CC5MA and CC8MA, a TCC-->TCT (Ser-->Ser) transition in codon 352 was observed. The deviations in codons 351 and 352 occurred in both cancer tissues and normal mucosae, suggesting a genetic polymorphism. No mutation was found in the 140 kDa subunit of replication factor C from 16 specimens (10 tumors and 6 cell lines). Point mutations were identified in the p53 tumor-suppressor gene in 4 of the 6 colon cancer cell lines and 3 of the 8 carcinoma specimens. We did not find tumor-associated DNA sequence alterations that resulted in amino acid changes in the DNA replication genes analyzed. We infer that the scarcity of mutations found is due to stringent selection, eliminating functionally impaired replication proteins.

Colorectal Neoplasms↗
PubMed2000

Suppression of Pyk2 kinase and cellular activities by FIP200.

Proline-rich tyrosine kinase 2 (Pyk2) is a cytoplasmic tyrosine kinase implicated to play a role in several intracellular signaling pathways. We report the identification of a novel Pyk2-interacting protein designated FIP200 (FAK family kinase-interacting protein of 200 kD) by using a yeast two-hybrid screen. In vitro binding assays and coimmunoprecipitation confirmed association of FIP200 with Pyk2, and similar assays also showed FIP200 binding to FAK. However, immunofluorescent staining indicated that FIP200 was predominantly localized in the cytoplasm. FIP200 bound to the kinase domain of Pyk2 and inhibited its kinase activity in in vitro kinase assays. FIP200 also inhibited the kinase activity of the Pyk2 isolated from SYF cells (deficient in Src, Yes, and Fyn expression) and the Pyk2 mutant lacking binding site for Src, suggesting that it regulated Pyk2 kinase directly rather than affecting the associated Src family kinases. Consistent with its inhibitory effect in vitro, FIP200 inhibited activation of Pyk2 and Pyk2-induced apoptosis in intact cells, which correlated with its binding to Pyk2. Finally, activation of Pyk2 by several biological stimuli correlated with the dissociation of endogenous FIP200-Pyk2 complex, which provided further support for inhibition of Pyk2 by FIP200 in intact cells. Together, these results suggest that FIP200 functions as an inhibitor of Pyk2 via binding to its kinase domain.

3T3 Cells↗
PubMed2000

Molecular systematics of pikas (genus Ochotona) inferred from mitochondrial DNA sequences.

The phylogenetic relationships among worldwide species of genus Ochotona were investigated by sequencing mitochondrial cytochrome b and ND4 genes. Parsimony and neighbor-joining analyses of the sequence data yielded congruent results that strongly indicated three major clusters: the shrub-steppe group, the northern group, and the mountain group. The subgeneric classification of Ochotona species needs to be revised because each of the two subgenera in the present classification contains species from the mountain group. To solve this taxonomic problem so that each taxon is monophyletic, i.e. , represents a natural clade, Ochotona could be divided into three subgenera, one for the shrub-steppe species, a second for the northern species, and a third for the mountain species. The inferred tree suggests that the differentiation of this genus in the Palearctic Region was closely related to the gradual uplifting of the Tibet (Qinghai-Xizang) Plateau, as hypothesized previously, and that vicariance might have played a major role in the differentiation of this genus on the Plateau. On the other hand, the North American species, O. princeps, is most likely a dispersal event, which might have happened during the Pliocene through the opening of the Bering Strait. The phylogenetic relationships within the shrub-steppe group are worth noting in that instead of a monophyletic shrub-dwelling group, shrub dwellers and steppe dwellers are intermingled with each other. Moreover, the sequence divergence within the sister taxa of one steppe dweller and one shrub dweller is very low. These findings support the hypothesis that pikas have entered the steppe environment several times and that morphological similarities within steppe dwellers were due to convergent evolution.

Animals↗
PubMed2000

Generation of dendritic cells from peripheral blood of patients at different stages of chronic myeloid leukemia.

We report a method to generate dendritic cells (DC) from frozen leukapheresis products of patients with chronic myeloid leukemia (CML), using sterile culture bags and serum-free culture medium, ie conditions feasible for re-infusion into the patient as part of immunotherapeutic protocols. Leukapheresis products were stored from harvests performed either at diagnosis (13 patients) or after chemotherapy with subsequent granulocyte colony stimulating factor (G-CSF) administration (9 patients), for Peripheral Blood Stem Cell (PBSC) collections. In the presence of optimal concentrations of GM-CSF (50 ng/ml) and IL-4 (40 ng/ml) CML progenitors differentiated on day 7 and 14 of culture to DC, expressing CD1a,HLA-DR and CD86 surface antigens. Mature DCs exhibited on average 12-fold higher allo-stimulatory capacity for CD4+ and CD8+ cells compared to non-cultured PBMC in mixed lymphocyte reaction (MLR). Only DCs obtained from CML patients at diagnosis exhibited bcr/abl fusion gene when tested by fluorescent in situ hybridization (FISH). CD34-selection on leukapheresis products from diagnosis (7 patients) resulted in later maturation of DCs (after 14-15 d), compared to the nonselected PBMC. CD34-selection significantly increased the DC growth, and improved the allo-stimulatory capacity in MLR (on average on day 14, 3.5- and 2.3-fold, respectively). Large differences were observed between individual patients and different leukapheresis products from the same patient. Our report demonstrates the possibility to generate ex vivo autologous functionally active DC in CML in a way that allows their clinical application as immunotherapeutic agents.

Antigens, CD34↗
PubMed2000

Peripheral olfactory projections are differentially affected in mice deficient in a cyclic nucleotide-gated channel subunit.

Axons of olfactory sensory neurons expressing a given odorant receptor converge to a few glomeruli in the olfactory bulb. We have generated mice with unresponsive olfactory sensory neurons by targeted mutagenesis of a cyclic nucleotide-gated channel subunit gene, OCNC1. When these anosmic mice were crossed with mice in which neurons expressing a given odorant receptor can be visualized by coexpression of an axonal marker, the pattern of convergence was affected for one but not another receptor. In a novel paradigm, termed monoallelic deprivation, axons from channel positive or negative neurons that express the same odorant receptor segregate into distinct glomeruli within the same bulb. Thus, the peripheral olfactory projections are in part influenced by mechanisms that depend on neuronal activity.

Animals↗
PubMed2000

Genomic integration and gene expression by a modified adenoviral vector.

A replication-deficient recombinant adenovirus encoding luciferase was constructed using 5' and 3' long terminal repeat (LTR) sequences of the Moloney murine leukemia virus. Gene expression was observed in cultured cells in vitro and in submandibular gland, cortex, and caudate nucleus for as long as three months in vivo. The vector integrated randomly into the genome of both dividing and nondividing cells as determined by fluorescence in situ hybridization (FISH) (10-15% of cells in vitro and 5% in rat spleen in vivo), gene walking, Southern hybridization, and polymerase chain reaction (PCR), in the absence of transcomplementing reverse transcriptase or integrase activity. The new vector combines the high titer and versatility of adenoviral vectors with the long-term gene expression and integration of retroviral vectors.

Adenoviridae↗
PubMed2000

Adenoviral transfer of xenogeneic MHC class I gene results in loss of tumorigenicity and inhibition of tumor growth.

The immune system confers protection against a variety of pathogens and contributes to the destruction of neoplastic cells. Foreign major histocompatibility complex (MHC) protein serves as a potent stimulus to the immune system. In this report, a mouse H-2Kb gene was introduced into two poorly immunogenic tumor cell lines, a mouse colonic carcinoma cell line, MCA-26 (H-2Kd), and a rat mammalian carcinoma cell line, LN-4, in an effort to stimulate tumor rejection. Our results showed that the expression of xenogeneic MHC class I antigen completely abolished the LN-4 tumorigenicity in rats, whereas the expression of allogeneic MHC class I antigen only partially reduced the MCA-26 tumorigenicity in mice. Rats with tumor regression of LN-4/H-2Kb developed a T helper type 1-dominant response, whereas rats with LN-4 tumor growth developed a T helper type 2-dominant response. The immunized rats that experienced LN-4/H-2Kb tumor regression further developed protective immunity against a subsequent challenge of LN-4 cells. This protective immunity was mediated by the LN-4 tumor-specific cellular immune response against both the transduced and the parental LN-4 cells. Recombinant adenoviral vectors are highly efficient at in vitro and in vivo gene delivery. The LN4 cells transfected with the recombinant adenovirus AdV-H-2Kb in vitro expressed the cell surface H-2Kb molecule by fluorescence-activated cell sorter analysis. Adenovirus-mediated H-2Kb gene transfer in vivo can further significantly inhibit pre-established LN-4 tumors. Those rats with complete tumor regression further developed protective immunity against the subsequent challenge of a parental LN-4 tumor. Therefore, our study indicates that the adenovirus-mediated transfer of xenogeneic MHC class I gene may be an effective alternative to the current protocol of cancer gene therapy in which the allogeneic MHC class I gene is used.

Adenoviridae↗