Biomedical subjects

Hong Zheng

Publications and source records attributed to Hong Zheng.

At least 55 records · Page 3Linked to original sources

PubMed2005

Determination of nucleic acids based on shifting the association equilibrium between tetracarboxy aluminum phthalocyanine and poly-lysine.

A new method based on near-infrared (near-IR) fluorescence recovery was presented for the determination of nucleic acids. This method employed a two-reagent system composed of anionic tetracarboxy aluminum phthalocyanine (AlC4Pc) and polycationic poly-lysine. The fluorescence of AlC4Pc, with the maximum excitation and emission wavelengths at 620 and 701 nm, respectively, was quenched by poly-lysine with a proper concentration, but recovered by adding nucleic acids. Under optimal conditions, the recovered fluorescence was in proportional to the concentration of nucleic acids. The linear ranges of the calibration curves were 5-200 ng mL(-1) for both calf thymus DNA (ctDNA) and fish sperm DNA (fsDNA) with the detection limit of 2.6 ng mL(-1) for ctDNA and 2.1 ng mL(-1) for fsDNA. The relative standard deviation (n = 6) was 1.9 and 1.3% for 50 ng mL(-1) ctDNA and fsDNA, respectively. The proposed method was applied to the determination of nucleic acids in synthetic samples with satisfactory results.

Animals↗

PubMed2005

Family characteristics and smoking among urban and rural adolescents living in China.

BACKGROUND: Adolescent smoking is a public health concern in China. Although the family is an important social influence in China, few associations among family characteristics and adolescent smoking have been examined using Chinese samples. METHODS: Survey data on psychosocial variables and smoking were collected from a sample of 3629 7th grade adolescents (46% female; 54% male; mean age 12.7 years) in Wuhan, China. For adolescents, past 30-day smoking, family relationships, parents' negative sanctioning of smoking, parents' agreement with smoking, and parents' smoking behaviors are assessed. To account for the clustered data structure, hierarchical logistic regression analyses controlling for demographics (urbanization, age) examined the independent and multivariate effects of family characteristics for each gender. RESULTS: Girls are less likely than boys to report smoking and are more likely to report positive family relationships, and having parents with negative attitudes toward them smoking. Positive family relationships and age were strongly associated with smoking for both genders. No significant differences exist by gender. CONCLUSION: These findings suggest that the quality of family relationships are important for adolescent female and male smoking in China.

Adolescent↗

PubMed2005

Identification, cloning, expression, and characterization of the gene for Plasmodium knowlesi surface protein containing an altered thrombospondin repeat domain.

Proteins present on the surface of malaria parasites that participate in the process of invasion and adhesion to host cells are considered attractive vaccine targets. Aided by the availability of the partially completed genome sequence of the simian malaria parasite Plasmodium knowlesi, we have identified a 786-bp DNA sequence that encodes a 262-amino-acid-long protein, containing an altered version of the thrombospondin type I repeat domain (SPATR). Thrombospondin type 1 repeat domains participate in biologically diverse functions, such as cell attachment, mobility, proliferation, and extracellular protease activities. The SPATR from P. knowlesi (PkSPATR) shares 61% and 58% sequence identity with its Plasmodium falciparum and Plasmodium yoelii orthologs, respectively. By immunofluorescence analysis, we determined that PkSPATR is a multistage antigen that is expressed on the surface of P. knowlesi sporozoite and erythrocytic stage parasites. Recombinant PkSPATR produced in Escherichia coli binds to a human hepatoma cell line, HepG2, suggesting that PkSPATR is a parasite ligand that could be involved in sporozoite invasion of liver cells. Furthermore, recombinant PkSPATR reacted with pooled sera from P. knowlesi-infected rhesus monkeys, indicating that native PkSPATR is immunogenic during infection. Further efficacy evaluation studies in the P. knowlesi-rhesus monkey sporozoite challenge model will help to decide whether the SPATR molecule should be developed as a vaccine against human malarias.

Amino Acid Sequence↗

PubMed2005

[The influence of leukocyte depletion filter-LD-1 on leukocytes, IL-6, MPO and the pathologic changes of myocardic tissues during cardiopulmonary bypass].

OBJECTIVE: To elucidate the influence of the leukocyte depletion filter (LD-1) on leukocytes, IL-6, myeloperoxidase enzyme (MPO) and the pathological changes of myocardic tissues during cardiopulmonary bypass(CPB). METHODS: Twelve dogs were used in this study. The LD-1, designed and made by ourselves, was fixed on the venous line in the trial group (n=6). It was used during the first 5 min after 2 min of CPB. LD-1 was not installed in the control group (n=6). Circulating leukocytes were counted before CPB, at 10 min, 40 min, 75 min during CPB, at the end of CPB, and 2 h after CPB. Plasma levels of IL-6 and MPO were also determined at the same time. The pathologic changes of left ventricular biopsies were observed before CPB, 5 min after protamine was given, and 2 h after CPB. RESULTS: The CPB 10 min WBC Count fell to 36% of that Before CPB in LD-1 group, which was lower than the WBC count in the control group synchronously (P < 0.01). But after CPB 2 h, both of them were close to the levels Before CPB in the two groups. In LD-1 group, IL-6 increased at CPB 40 min and reached to the top. But after wards it dropped continuously. The changes were of no significance in MPO and in the pathological examination of myocardic tissues (P > 0.05). CONCLUSION: The LD-1 on venous line was capable of decreasing WBC count effectively. As a result, the inflammation factors that leukocytes released were lower, so the program chain of inflammation by CPB was shorter. But LD-1 was not superior in myocardial preservation.

Animals↗

PubMed2005

[Effects of leukocyte depletion filter on canine kidney during cardiopulmonary bypass].

OBJECTIVE: To explore the effect of a reforming leukocyte depletion filter (LDF-1) on the functional and pathologic changes of canine kidney during cardiopulmonary bypass (CPB). METHODS: Twelve Mongolian dogs were randomly allocated into a control group (no LDF-1, n = 6) or a leukocyte-depleted filter group (LDF-1 placed in venous line, n = 6). CPB of the dogs anestheitized with sodium pentobarbitone at 25 mg/kg was set up. After 10 min of CPB, aorta was clamped and St. Thomas cardioplegic solution at 20 mg/kg was immediately injected into the root of aorta. The aortic cross-clamp was released and CPB was closed at 70 min. Dogs were observed for 2 h after weaning from CPB. LDF-1 was opened at 2 min and stoped at 7 min during initially running CPB in the LDF-1 group. Circulating leukocytes, plasma L-selectin, and plasma IL-8 were respectively counted before CPB, at 10 minutes, 40 min, and 75 min during CPB, the end of CPB, and 2 h after CPB. The urine analysis and renal pathology, which were obtained before CPB and 2 h after CPB, were observed. RESULTS: The number of leukocytes significantly decreased by 55% - 68% in the LDF-1 group compared with the baseline during CPB. The value at 10 min of CPB in the LDF-1 group was lower than that in the control group (P < 0.05). Plasma levels of L-selectin and IL-8 obviously increased in the 2 groups compared with the baseline during CPB, but both levels at 2 h after CPB in the LDF-1 group were lower than those in the control group (P <0. 05). No statistic difference was found in plasma levels of urea and creatinine, but hematuria was observed in the 2 groups at 2 hours after CPB. The pathologic changes of kidney, which was mainly renal tubule swelling accompanied partly with vacuolar degeneration, were similar under the light microscope in the 2 groups at 2 h after CPB. Obvious glomerular damage was not found. CONCLUSION: LDF-1 can effectively decrease leukocyte counts and the inflammatory reaction, but it can not bring about excellent protective effect on kidney during CPB when used alone. Attention to should be paid the renal protection in the postoperative CPB.

Acute Kidney Injury↗

PubMed2005

[The purification of HBV full-length PreS protein in Pichia pastoris].

The Pichia pastoris strain GS115-PreS could produce a high expression level of full-length PreS protein that secreted to the supernatant after methanol induction in the fermentation. The Western blot analysis showed a single band with expected molecular mass of 48kD and that the major component of the particles was the full-length PreS protein (PreS1 + PreS2 + S) and small envelope protein (S) of 48 and 28 kD, respectively. Electron microscopy image showed PreS particles with 30 nm in diameter. The supernatants of the fermentation were desalted and concentrated. Purified PreS protein was obtained by DEAE-SFF anion exchange column chromatography and the PreS particles were obtained by ultracentrifugation and sucrose density gradient. The ELISA assay results proved that both full-length PreS protein and particles showed high immunogenicity and specificity. P/N ratio further demonstrated that the immunogenicity of the particles is higher than the full-length PreS protein.

Hepatitis B Surface Antigens↗

PubMed2005

[Surgical treatment of peripheral facial nerve paralysis: analysis of 51 cases].

OBJECTIVE: To investigate the surgical treatment of peripheral facial nerve paralysis as well as the factors which affect the operation effect. METHOD: Fifty-one cases of peripheral facial nerve paracusis were analyzed retrospectively. RESULT: Forty-two cases were followed up. Among them, twenty-two cases who received facial nerve decompression reached House I-II degree (22/36), 2 cases facial nerve anastomosis reached House I-II degree (2/4), and the function recovery of 2 cases who received facial nerve grafting > III degree both. CONCLUSION: Intensive and timely surgery is an efficient way in treating of peripheral facial nerve paralysis.

Adolescent↗

PubMed2005

[Expression of estrogen and progesterone receptor subtypes in human endometrial carcinoma tissues].

OBJECTIVE: To investigate the expressions of estrogen receptor (ER) and progesterone receptor (PR) subtypes in human endometrial carcinoma tissues. METHODS: Thirty samples of normal endometrial tissue and 66 endometrial carcinomas were investigated using western blot assays and reverse-transcription polymerase chain reaction. RESULTS: (1) Both ERalpha and ERbeta mRNA were significantly increased in endometrial carcinoma compared with that in normal endometrium tissues. The relative value of ERalpha and ERbeta mRNA in endometrial carcinoma was 8.00 +/- 7.77, 3.84 +/- 2.57 and that in normal endometrium tissues was 4.15 +/- 3.55, 0.41 +/- 0.29, respectively. (2) Decreased levels of PR, PRA, PRB protein and PR mRNA were associated with endometrium carcinogenesis (P < 0.05), while PRB mRNA expression and the ratio of PRA/PRB was not. (3) Expression of PRB mRNA was associated with ERbeta mRNA (r = 0.43, P < 0.01). CONCLUSION: Overexpression of ER subtypes and down-regulation of PR may be involved in the pathogenesis of endometrial carcinoma, and expression of PRB mRNA is associated with ERbeta but not ERalpha mRNA.

Adult↗

PubMed2004

Cutting edge: cross-presentation of cell-associated antigens to MHC class I molecule is regulated by a major transcription factor for heat shock proteins.

The ability for the professional APC to cross-present Ag to MHC class I from parenchymal cells is essential for priming as well as tolerance of CD8+ T cells against intracellular Ags. Since cross-presentations of non-cell-associated free Ags are inefficient, the roles of molecular chaperones or heat shock proteins (HSPs) in chaperoning Ags to APCs have been postulated. We herein genetically addressed this hypothesis using mice that were defective of heat shock factor 1 (Hsf1), a major transcription factor for HSPs. Hsf1(-/-) mice have a decreased expression of several HSPs including HSP90 and HSP70. Using multiple Ag systems, we demonstrated that cross-priming of Ag-specific CD8+ T cells was inefficient when Ag expression was restricted to Hsf1(-/-) non-APCs. Our study provides the first genetic evidence for the roles of Hsf1 in regulating cross-presentation of MHC class I-associated Ags.

Adoptive Transfer↗

PubMed2004

Fluorescence enhancement method for measuring anionic surfactants with a hydrophobic cyanine dye.

A novel fluorimetric method based on use of a hydrophobic cationic cyanine dye has been developed for determination of the anionic surfactant sodium dodecylbenzenesulfonate (DBS). The method is based on the enhancement effect of DBS on the fluorescence of the hydrophobic cyanine dye 2-[-4'-chloro-7'-(1"-ethyl-3",3"-dimethylindolin-2"-ylidene)-3',5'-(propane-1"',3"'-diyl)-1',3',5'-heptatrien-1'-yl]-1-ethyl-3,3-dimethyl-3 H-indolium iodide. Under the optimum conditions the extent of fluorescence enhancement is proportional to the concentration of DBS in the range 0.05-5.0 mg L(-1); the detection limit is 0.014 mg L(-1). The relative standard deviation for 0.35 mg L(-1) DBS was 1.1% (n=10). The proposed method, which avoided use of toxic solvents and tedious solvent-extraction, and was applied to the determination of DBS in natural water with recoveries between 99.9 and 107%. Preliminary research shows that the fluorescence enhancement is due to the formation of a dye aggregate facilitated by DBS.

Anions↗

PubMed2004

Conversion of cell movement responses to Semaphorin-1 and Plexin-1 from attraction to repulsion by lowered levels of specific RAC GTPases in C. elegans.

Plexins are functional receptors for Semaphorin axon guidance cues. Previous studies have established that some Plexins directly bind RAC(GTP) and RHO. Recent work in C. elegans showed that semaphorin 1 (smp-1 and smp-2) and plexin 1 (plx-1) are required to prevent anterior displacement of the ray 1 cells in the male tail (Fujii et al., 2002; Ginzburg et al., 2002). We show genetically that plx-1 is part of the same functional pathway as smp-1 and smp-2 for male ray positioning. RAC GTPase genes mig-2 and ced-10 probably function redundantly, whereas unc-73, which encodes a GEF for both of these GTPases, is required cell autonomously for preventing anterior displacement of ray 1 cells. RNAi analysis indicates that rho-1-encoded RHO GTPase, plus let-502 and K08B12.5-encoded RHO-kinases, are also required to prevent anterior displacement of ray 1 cells, suggesting that different kinds of RHO-family GTPases act similarly in ray 1 positioning. At low doses of wild-type mig-2 and ced-10, the Semaphorin 1 proteins no longer act through PLX-1 to prevent anterior displacements of ray 1, but have the opposite effect, acting through PLX-1 to mediate anterior displacements of ray 1. These results suggest that Plexin 1 senses levels of distinct RHO and RAC GTPases. At normal levels of RHO and RAC, Semaphorin 1 proteins and PLX-1 prevent a forward displacement of ray 1 cells, whereas at low levels of cycling RAC, Semaphorin 1 proteins and PLX-1 actively mediate their anterior displacement. Endogenously and ectopically expressed SMP-1 and SMP-2 suggest that the hook, a major source of Semaphorin 1 proteins in the male tail, normally attracts PLX-1-expressing ray 1 cells.

Amino Acid Sequence↗

PubMed2004

Long-term exposure to tamoxifen induces hypersensitivity to estradiol.

In women with hormone-dependent breast cancer, tamoxifen (TAM) frequently induces tumor regression, but regrowth occurs with continuation of antiestrogen therapy. Studies of breast xenografts in nude mice suggest that this secondary resistance to TAM may reflect the development of enhanced sensitivity to the estrogenic properties of TAM. In the current study, we examined the hypothesis that TAM could also induce a state of hypersensitivity to estradiol (E(2)) itself. Oophorectomized nude mice with MCF-7 cell xenografts received 25-mg implants of TAM [long-term TAM treated (LTTT) mice] or cholesterol (C-MCF-7) over a 5-month period (phase 1). The LTTT group regressed to a lesser extent than did C-MCF-7 tumors. After 4 months of TAM exposure, the LTTT tumors begin to regrow, as did the C-MCF-7, as assessed by slope analysis. At 5 months, TAM or vehicle implants were removed, and the LTTT and C-MCF-7 subgroups were given vehicle or two doses of E(2) to test estrogen sensitivity (phase 2). We used our "E(2) clamp" technique to maintain levels of plasma E(2) at either 1.25 or 20 pg/ml. Neither group responded to the very low concentrations of E(2) (1.25 pg/ml) or vehicle. The LTTT tumors but not C-MCF-7 tumors exhibited a growth response on exposure to 20 pg/ml E(2) during 7 weeks, as demonstrated with mixed models analysis. These studies provide evidence that long-term TAM exposure enhances sensitivity to the estrogenic effects of TAM and also to E(2) itself.

Animals↗

PubMed2004

Fluorescence enhancement method for the determination of nucleic acids using cationic cyanine as a fluorescence probe.

A fluorescence enhancement method with a cationic cyanine as a probe was developed for the determination of nucleic acids. Under the experimental conditions, the fluorescence enhancement of cyanine (lambda(ex)/lambda(em)= 524/591.5 nm) was observed in the presence of DNA. The calibration graphs were linear over the range of 0.01-15 microg mL(-1) for both calf thymus DNA (CT DNA) and fish sperm DNA (FS DNA). The limits of detection were 0.005 and 0.007 microg mL(-1) for CT DNA and FS DNA, respectively. The method was applied to the determination of DNA in synthetic and real samples and satisfactory results were obtained. A possible fluorescence enhancement mechanism was also studied.

Carbocyanines↗

PubMed2004

Project EX--a teen smoking cessation initial study in Wuhan, China.

The increasing smoking prevalence in China indicates a need for effective smoking cessation programs, yet, to our knowledge, no studies have evaluated the effects of smoking cessation programs among Chinese adolescents. A group of 46 10th-grade-level cigarette smokers from two schools in Wuhan, China, were provided with Project EX, an eight-session school-based clinic smoking cessation program developed in the United States. Efforts of translation of the Project EX curriculum, verification of translation, curriculum modification, and cultural adaptation were made to adapt the curriculum to the local culture. The 46 smokers represented 71% of all the self-reported 30-day smokers among 622 10th graders at these two schools. Only one student dropped out from the clinic program. Four-month follow-up data indicated a 10.5% 30-day quit rate and a 14.3% 7-day quit rate. The students who did not quit smoking reported a 16% reduction in daily cigarette consumption at posttest and a 33% reduction at 4-month follow-up. Use of a 2 1/2-week prebaseline-to-baseline clinic assessment indicated a clinic cohort nonassisted quit rate of 3%. These data provided evidence that Project EX can be adapted in another country, such as China; can be very well received; and can lead to promising results on cessation.

Adolescent↗

PubMed2004

Fluorescence spectroscopic determination of dipyridamole binding on pancreas-1 tumor cell membrane.

BACKGROUND: The traditional method to determine the binding sites of inhibitors bound to nucleoside transporters on cell membrane is the radioactive assay. This method suffers from radiolabel instability and the need to dispose of reactive materials. Fluorescence spectroscopy has been increasingly applied to biochemical analysis due to its high sensitivity and selectivity. We describe fluorescence spectroscopy for the determination of the binding sites of dipyridamole bound to nucleoside transporters on pancreas-1 tumor cell membrane. METHODS: Pancreas-1 tumor cell was cultured in Dulbecco's modified Eagle medium under appropriate conditions. The cell plasma membrane was separated from the ultrasonically dissolved cell mixture by gradient centrifugation. After dipyridamole was bound to the cell membrane, the test sample was obtained by ultrasonically dissolving the labeled membrane in 10 mmol/l tris-HCl membrane lysis solution. Under selected experimental conditions, the fluorescence intensity of dipyridamole was determined. RESULTS: At lambda em of 295 nm and lambda em of 485 nm, dipyridamole was proportional to its concentration ranging from 1.0 x 10(-12) to 5.0 x 10(-11) mol/l with a detection limit of 2.8 x 10(-13) mol/l (0.14 pg/ml) at 3sigma. The value of affinity constant of the cell membrane to dipyridamole was 4.7(+/-0.5) x 10(10) l/mol and the average total number of binding sites of a pancreas-1 tumor cell was 1.9(+/-0.2) x 10(6). CONCLUSIONS: The proposed method can be used in the study of binding characters of dipyridamole on the cell membrane.

Binding Sites↗

PubMed2004

SU5416 is a potent inhibitor of hepatocyte growth factor receptor (c-Met) and blocks HGF-induced invasiveness of human HepG2 hepatoma cells.

BACKGROUND/AIMS: SU5416 is a potent inhibitor of receptor tyrosine kinases, including those of the vascular endothelial growth factor receptor, stem cell factor receptor, and platelet-derived growth factor receptor. Because of the overwhelming evidence favoring the role of aberrant hepatocyte growth factor (HGF)/Met signaling in the pathogenesis of various human cancers, various inhibitor strategies have been employed to therapeutically target this receptor. METHODS: Cell proliferation was determined by incorporation of [(3)H] thymidine. Invasiveness was assayed in Boyden Chambers with 8 microm Matrigel coated filters. Phosphorylation of ERK1/2, Akt by HGF stimulation was detected by Western blotting. RESULTS: We found that SU5416 inhibited motility scattering and the invasive activity of a hepatocellular carcinoma cell line HepG2 in vitro and growth in primary cultured hepatocytes induced by HGF. Consequently, tyrosine autophosphorylation of the c-met induced by HGF was inhibited in these cells by SU5416 in a dose-dependent manner. Furthermore, ERK1/2 and Akt phosphorylation, the signaling events down-stream of c-met activation were reduced. Moreover, SU5416 caused reversion in NIH3T3 fibroblasts transformed by the oncogenic form of the receptor, Tpr-Met. CONCLUSIONS: Inhibition of various solid tumors growth and metastasis by SU5416 may be partially attributed to blocking activation of the hepatocyte growth factor receptor.

3T3 Cells↗

PubMed2004

Fluorescence quenching method for the determination of sodium dodecyl sulphate with near-infrared hydrophobic dye in the presence of Triton X-100.

A fluorophotometric method for the determination of anionic surfactant sodium dodecyl sulphate (SDS) was proposed. The method is based on the quenching effect of SDS on the fluorescence of near-infrared (NIR) hydrophobic dye, 2-[4'chloro-7'(3''hexadecyl-2''benzothiazolinylidene)-3',5'-(1''',3'''-propanediyl)-1',3',5'-heptatriene-1'-yl]-3-ethylbenzothiazolium iodide (dye I) in the presence of Triton X-100. The calibration graph is linear in the concentration range from 0 to 2 x 10(-6) mol L(-1) of SDS with a detection limit (LOD) of 8.3 x 10(-8) mol L(-1). The relative standard deviation for the determination of 7 x 10(-7) mol L(-1) SDS was 4.1%. Recoveries of 95.3-110.3% were found for the addition to 1.0 x 10(-6) mol L(-1) SDS in the analysis of environmental water samples. Preliminary research shows that the fluorescence quenching is due to the formation of dye aggregate facilitated by SDS.

Fluorescence↗

PubMed2004

Integration of semaphorin-2A/MAB-20, ephrin-4, and UNC-129 TGF-beta signaling pathways regulates sorting of distinct sensory rays in C. elegans.

Semaphorins and ephrins are axon guidance cues. In C. elegans, semaphorin-2a/mab-20 and ephrin-4/efn-4/mab-26 also regulate cell sorting to form distinct rays in the male tail. Several erf (enhancer of ray fusion) mutations were identified in a mab-20 enhancer screen. Mutants of plexin-2 (plx-2) and unc-129, which encodes an axon guiding TGF-beta, were also found to be erfs. Genetic analyses show that plx-2 and mab-20 function in the same pathway, as expected if PLX-2 is a receptor for MAB-20. Surprisingly, MAB-20 also signals in a parallel pathway that requires efn-4. This signal utilizes a non-plexin receptor. The expression of plx-2, efn-4, and unc-129 in subsets of 3-cell sensory ray clusters likely mediates the ray-specific cell sorting functions of the ubiquitously expressed mab-20. We present a model for the integrated control of TGF-beta, semaphorin, and ephrin signaling in the sorting of cell clusters into distinct rays in the developing male tail.

Animals↗