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Biomedical subjects

J Zheng

Publications and source records attributed to J Zheng.

At least 181 records · Page 10Linked to original sources
PubMed2000

Bifunctional effect of human IFN-gamma on cultured human fibroblasts from Tenon's capsule.

PURPOSE: To study the effect of human IFN-gamma on in vitro cultured human fibroblasts from Tenon's capsule. MATERIALS AND METHODS: The effect of different concentrations of human IFN-gamma and mitomycin-C (MMC), 5-fluorouracil (5-Fu) on cultured human Tenon's capsule fibroblasts (HTCF) was measured using a MTT [3-(4, 5-dimethylthiazo-2-yl)]-2, 5-diphenyltetrazolium bromide; Thiazolyl blue) colorimetric assay. The results were analyzed using ANOVA of the statistical package for social sciences (SPSS) 9.0 version. The difference was considered to be significant if P < 0.05. RESULTS: The effects of MMC and 5-Fu on the growth of HTCF were negative, while the effects of IFN-gamma on the growth of HTCF were both negative (10(2)-10(4) units/ml in two experiments) and positive (10(6), 10(5), 10 units/ml in two experiments). The inhibition rate of MMC ranged from 5.73% to 46.9%, which was similar to the inhibition rate of 5-Fu ranged from 12.49% to 38.92% (P = 0.351). The inhibition rate of IFN-gamma in two experiments was smaller than MMC and 5-Fu (P < 0.05). CONCLUSION: IFN-gamma has bifunctional effect (both enhancement and inhibition) on proliferation of cultured HTCF. The antiproliferative effect of IFN-gamma was weaker than MMC and 5-Fu. Further study has to be carried out to document the inhibition of scar formation of filtration bleb by IFN-gamma and the molecular mechanisms of its bifunctional effect on HTCF proliferation.

Cell Division↗
PubMed2000

[The cultivation, freezing-state preservation and resuscitation of human iris pigment epithelial cells in vitro].

PURPOSE: To establish the culture of human iris pigment epithelial cells in vitro and study the freezing-state preservation and resusciation. METHODS: The iris pigment epithelial specimens from human eyes were cultured in vitro. Based on the cell-frozen principle, the cultured cells were collected, then frozen in liquid nitrogen and resuscitation. RESULTS: Cultured iris pigment epithelial cells were obtained. Under the inverted light microscope, primary cells appeared multigonal and arranged in monolayer, there were abundant pigment granules in the cytoplasm and the nuclei each of which contained 1 or 2 nuceoli wre relatively transparent. Under the transmission electron microscope, there were plenty of microvilli at the cell membrane and desmosomes present in the intercellular space. 6 groups of cells were frozen. The resuscitation exeriment was carried out for 4 times, every times being successful. All of the resuscitated rates were more than 90%. CONCLUSION: The human iris pigment epithelial cells were cultured in vitro successfully, they can also be frozen and resuscitated, which will be useful in studies of pathogenesis for some eye disease.

Cells, Cultured↗
PubMed2000

[Culture and identification of human vascular endothelial cells].

PURPOSE: To investigate the culture technigue of human vascular endothelial cells in vitro and improve the success rate of culture. METHODS: Human vascular endothelial cells were isolated from umbilical cords by "Irrigative digestion" technique with 0.2% collagenase III and were digested by 0.0625% tripsin when the cells confluent. The cells were identified by morphologic and immunohistochemical assays. RESULTS: The cultured human umbilical vein endothelial cells attached completely after 24 hours in vitro, reached confluence in 3-5 days with the typical appearance of "stone of pave road" and were passaged on time; Immunohistochemically these cells were stained positively by CD34 monoclonal antibody. CONCLUSION: "Irrigative digestion" technique was a reliable method to obtain human umbilical vascular endothelial cells with high success rate. It can be widely used to the culture and researches of human vascular endothelial cells.

Antibodies, Monoclonal↗
PubMed2000

[The culture and cryopreservation of human conjunctival epithelium in vitro].

PURPOSES: To detect the best method of culture and preservation of human conjunctival epithelia. METHODS: Human conjunctival epithelia were cultured by tissue inoculation, mechanical separation or enzyme digestion with 0.25% trypsin. The cultured cells were identified through their morphology, growing features and immunohistochemical staining. The third and fourth passage confluent cells were frozen in liquid nitrogen, and resuscitated 30 days later. RESULTS: Cells from tissue digested with 0.25% Trypsin grew much better than those from tissue inoculation. No cell outgrew in mechanical separating group. The cultured cells spread along the flask in polygonal shape and positive in pan-Keratin staining. Ninty percent of the cryopreserved cells were successfully resuscitated. CONCLUSION: Tissue digestion with trypsin is the best approach to culture human conjunctival epithelium, and the cultured cells can be cryopreserved in liquid nitrogen.

Cell Culture Techniques↗
PubMed2000

[Central low frequency hearing loss].

OBJECTIVE: To study the pathogenesis of the bilateral central low frequency hearing loss. METHODS: Audiologic findings [auditory brainstem response(ABR), evoked otoacoustic emission (EOAE), et al] of 101 cases with bilateral central low frequency hearing loss were studied. RESULTS: The typical clinical manifestations of bilateral central low frequency hearing loss were normal EOAE which cannot be suppressed by contralateral white noise, abnormal ABR, no acoustic reflex and--SP/AP > 0.44. CONCLUSIONS: The results suggest that cochlear outer hair cells are normal in function with dysfunction of the cochlear nuclei. The main lesion of the disease are neural pathways related to Acoustic reflex and medial olivo-cochlear efferent nervous system. The cochlear afferent nerve may also be involved.

Adolescent↗
PubMed2000

[Studies on c-myc gene expression and p16 gene inactivation in nasopharyngeal carcinoma].

OBJECTIVE: The alterations of c-myc and p16 genes and their relationship with the development and progression of nasopharyngeal carcinoma were studied. METHODS: Sixty-nine biopsies of nasopharyngeal carcinoma were examined for the homozygous deletion methylation and reduced expression of p16, and the overexpression of myc family oncogenes using multiple PCR, restriction endonuclease coupled PCR, reverse transcriptase PCR and immunohistochemistry. RESULTS: The homozygous deletion and methylation of p16 gene were found in 7 and 11 cases respectively. The total inactivation rate was 26.1% (18/69). The negative expression of p16, as shown by immunohistochemical examination was found in 42 out of 69 cases (60.9%). The overexpression of myc family oncogenes was found in 51 cases (73.9%). CONCLUSION: It suggests that the inactivation of anti-oncogene p16 and the activation of myc family oncogene may play an important role in the development of nasopharyngeal carcinoma.

Adult↗
PubMed2000

[Arsenic trioxide induces human tumor cell apoptosis and G2 + M arrest whereas causes HPV16 DNA immortalized cervical epithelial cells G1 block].

OBJECTIVE: To investigate whether As2O3 induces tumor cell apoptosis and cell cycle arrest. METHODS: DNA agarose gel electrophoresis, flowcytometry analysis, RT-PCR, and Western blot. RESULTS: As2O3 induced G2 + M arrest of tumor cells such as GLC-82, MGC-803, SGC-7901, Eca109 and HeLa cells before inducing apoptosis and decreased c-myc gene expression, whereas caused G1 block of HPV16 DNA immortalized cervical epithelial HCE16/3 cells and did not affect c-myc expression. CONCLUSIONS: As2O3 caused apoptosis was related with cell cycle arrest. However, the phase of arrest of tumor cells was different from the pre-tumor cell HCE16/3 cells, which could be related to the change of c-myc gene expression.

Apoptosis↗
PubMed2000

The effect of basic fibroblast growth factor slow-release microcapsules on angiogenesis in infarcted rabbit myocardium.

OBJECTIVES: To observe the effect of basic fibroblast growth factor (bFGF) slow-release microcapsules on angiogenesis in infarcted myocardial regions. METHODS: Myocardial infarction was induced in 24 New Zealand rabbits by ligating the root of left anterior descending coronary artery. Group I (n = 8) served as control, group II (n = 8) as a blank microcapsule group, group III (n = 8, each microcapsule contains 1 microg bFGF) as microcapsule group. In group II and III, 5 blank microcapsules or bFGF slow-release microcapsules were implanted into myocardium underneath the epicardium between the left anterior descending coronary artery and left circumflex artery. Infarct size was evaluated by infarcted weight/left ventricle weight ratio and angiogenesis was evaluated by immunohistochemical examinations 5 weeks later. RESULTS: As compared with group I and II, rabbits treated with bFGF slow-release microcapsules showed higher microvessel counts (group I 37.75 +/- 4.50, group II 38.37 +/- 4.98, vs x group III 135.50 +/- 4.81, P < 0.001) and less infarcted weight/left ventricle weight (group I 16.8% +/- 0.4%, group II 16.7% +/- 0.5%, vs x group III 7.0% +/- 0.2%, P < 0.001). CONCLUSIONS: Subepicardial administration of bFGF slow-release microcapsule in the infarcted rabbit model results in effective angiogenesis and reduction in infarct size.

Animals↗
PubMed2000

[Two-dimensional surface Raman imaging of a roughened iron electrode in saline solution].

By using a confocal microprobe Raman system and proper surface roughening procedure for iron, the pit corrosion behavior of bare iron electrode in 3.4% NaCl (saline solution) solution has been investigated. The surface-enhanced Raman scattering (SERS) spectra of the corrosion products due to the pit corrosion at positive potential was obtained with high ratio of signal to noise. The application of SERS technique has been extended successfully to the study of iron corrosion. The two-dimensional surface Raman imaging acquired at 660 cm-1 was obtained also with the utility of surface Raman image technique. Results show that different iron oxides should coexist in the pit corrosion region and the distribution of the corrosion products was not uniform.

Chemical Phenomena↗
PubMed2000

[Self-assembly of nano-structured silver particle and its surface-enhanced Raman spectroscopic application].

Planar arrays of nano-structured silver particle were self-assembled on poly-lysine modified glass surfaces. SEM characterization indicates that silver particles were assembled as a sub-monolayer. A comparison of the UV/Vis spectra of silver colloid and the arrays demonstrates that the poly-lysine layer showed size selectivity for the self-assembling silver particles. Surface-enhanced FT-Raman spectrum of methylviolegen on the array reveals that Raman scattering in near IR region was mainly enhanced via a chemical enhancement mechanism.

Colloids↗
PubMed2000

[Resonance Raman and surface-enhanced Raman spectroscopic study of microperoxidase-11].

The electron transfer and structure of microperoxidase-11 (MP-11) in solution and at electrode/solution interface were studied by electrochemical, resonance Raman and surface-enhanced Raman spectroscopic techniques. Results show that the central iron in heme group was six-coordinated in solution, whereas it was converted to five-coordinated state as MP-11 was adsorbed on the surface of a roughened silver electrode, due to the reorientation of MP-11 molecules. The electrochemical properties of MP-11 were directly affected by the coordination state of heme iron.

Electrochemistry↗
PubMed1999

Miniaturized ultrathin slab gel electrophoresis with thermal lens microscope detection and its application to fast genetic diagnosis.

A miniaturized ultrathin slab gel electrophoresis (MUSGE) apparatus was developed, and fast separation of DNA fragments was obtained using it. To obtain sufficient separation efficiency in a limited space, a discontinuous buffer system was used. In general, it is difficult to cast a discontinuous ultrathin slab gel of adequate quality. However, the miniaturized resolving gel could be cast by taking advantage of the "capillary phenomenon" of the ultrathin channel. A gradient plate was used to control the height of the resolving gel and to form a clear interface between the concentrating gel and the resolving gel. This method was used to cast multiple gels simultaneously and reproducibly. The gradient plate also facilitated sample introduction, which was carried out by using a micropipet. A 25-mm-long and 80-micron thick-resolving gel was used to separate the 100-base pair ladder DNA within 10 min. Bandwidth was reduced to 100-200 microns, thus improving the number of theoretical plates to 22,000, which was comparable to that in conventional slab gel electrophoresis even though the migration distance was reduced to 1/10. Satisfactory lane-to-lane reproducibility (RSD < 1.0%, n = 6) and gel-to-gel reproducibility (RSD < 2.7%, n = 4) were obtained. Finally, the MUSGE apparatus was successfully applied to get a rapid genetic diagnosis.

Apolipoproteins B↗
PubMed1999

Involvement of peripheral NMDA and non-NMDA receptors in development of persistent firing of spinal wide-dynamic-range neurons induced by subcutaneous bee venom injection in the cat.

To study the roles of peripheral excitatory amino acids receptor subtypes N-methyl-D-aspartate (NMDA) and non-NMDA receptors in persistent nociception, extracellular single unit recording technique was used to assess the effects of a single dose NMDA and non-NMDA receptor antagonists, AP(5) (5-aminophosphonovaleric acid) and CNQX (6-cyano-7-nitroquinoxaline-2,3-dione) or DNQX (6,7-dinitroquinoxaline-2,3-dione), on s.c. bee venom-induced increase in firing of wide-dynamic-range (WDR) neurons in the spinal dorsal horn of the urethane-chloralose anesthetized cats. Subcutaneous bee venom injection into the cutaneous receptive field resulted in a single phase of increased firing of WDR neurons over the background activity for more than 1 h. Local pre-administration of AP(5) (200 microg/100 microl) or CNQX (8.3 microg/100 microl) into the bee venom injection site produced 94% (1.01+/-0.96 spikes/s, n=5) or 76% (2.97+/-0.58 spikes/s, n=4) suppression of the increased neuronal firing when compared with local saline (16.32+/-4.55 spikes/s, n=10) or dimethyl sulfoxide (DMSO) (12.37+/-6.36 spikes/s, n=4) pre-treated group, respectively. Local post-administration of the same dose of AP(5) produced a similar result to the pre-treatment group with a 67% inhibition of the mean firing rate, however, the same treatment with CNQX and even a higher dose of DNQX (100 microg/100 microl) did not produce any inhibition of the neuronal firing induced by s.c. bee venom injection (DNQX vs. DMSO: 23.91+/-0. 25 vs. 22.14+/-0.04 spikes/s, P=0.0298, n=5). In the control experiments, local pre-administration of the same dose of AP(5) or CNQX into a region on the contralateral hindpaw symmetrical to the bee venom injection site produced no significant influence on the increased firing of the WDR neurons [contralateral AP(5) vs. saline: 14.17+/-6.27 spikes/s (n=5) vs. 16.32+/-4.55 spikes/s (n=10), P0.05; contralateral CNQX vs. DMSO: 12.85+/-6.38 spikes/s (n=4) vs. 12. 37+/-6.36 spikes/s (n=4), P0.05], implicating that the suppressive action of local AP(5) or CNQX was not the result of systemic effects. The present results suggest that activation of the peripheral NMDA receptors is involved in both induction and maintenance, while activation of non-NMDA receptors is only involved in induction, but not in the maintenance of persistent firing of the dorsal horn WDR neurons induced by s.c. bee venom injection.

2-Amino-5-phosphonovalerate↗
PubMed1999

Intracellular CXCR4 signaling, neuronal apoptosis and neuropathogenic mechanisms of HIV-1-associated dementia.

The mechanism(s) by which HIV-1 affects neural injury in HIV-1-associated dementia (HAD) remains unknown. To ascertain the role that cellular and viral macrophage products play in HAD neurotoxicity, we explored one potential route for neuronal demise, CXCR4. CXCR4, expressed on lymphocytes and neurons, is both a part of neural development and a co-receptor for HIV-1. Its ligand, stromal cell-derived factor-1alpha (SDF-1alpha), affects neuronal viability. GTP binding protein (G-protein) linked signaling after neuronal exposure to SDF-1alpha, virus-infected monocyte-derived macrophage (MDM) secretory products, and virus was determined. In both human and rat neurons, CXCR4 was expressed at high levels. SDF-1alpha/beta was detected predominantly in astrocytes and at low levels in MDM. SDF-1beta/beta was expressed in HAD brain tissue and upregulated in astrocytes exposed to virus infected and/or immune activated MDM conditioned media (fluids). HIV-1-infected MDM secretions, virus and SDF-1beta induced a G inhibitory (Gi) protein-linked decrease in cyclic AMP (cAMP) and increase inositol 1,4, 5-trisphosphate (IP3) and intracellular calcium. Such effects were partially blocked by antibodies to CXCR4 or removal of virus from MDM fluids. Changes in G-protein-coupled signaling correlated, but were not directly linked, to increased neuronal synaptic transmission, Caspase 3 activation and apoptosis. These data, taken together, suggest that CXCR4-mediated signal transduction may be a potential mechanism for neuronal dysfunction during HAD.

AIDS Dementia Complex↗
PubMed1999

Potent urea and carbamate inhibitors of soluble epoxide hydrolases.

The soluble epoxide hydrolase (sEH) plays a significant role in the biosynthesis of inflammation mediators as well as xenobiotic transformations. Herein, we report the discovery of substituted ureas and carbamates as potent inhibitors of sEH. Some of these selective, competitive tight-binding inhibitors with nanomolar K(i) values interacted stoichiometrically with the homogenous recombinant murine and human sEHs. These inhibitors enhance cytotoxicity of trans-stilbene oxide, which is active as the epoxide, but reduce cytotoxicity of leukotoxin, which is activated by epoxide hydrolase to its toxic diol. They also reduce toxicity of leukotoxin in vivo in mice and prevent symptoms suggestive of acute respiratory distress syndrome. These potent inhibitors may be valuable tools for testing hypotheses of involvement of diol and epoxide lipids in chemical mediation in vitro or in vivo systems.

Animals↗
PubMed1999

Piceatannol, a stilbene phytochemical, inhibits mitochondrial F0F1-ATPase activity by targeting the F1 complex.

Piceatannol is a stilbene phytochemical from the seeds of Euphorbia lagascae, previously identified as an antileukemic principle. Piceatannol is considered an inhibitor of several tyrosine kinases. We recently reported that resveratrol, another stilbene phytoalexin from grape seeds, was an inhibitor of ATP synthase. Here, we demonstrated that piceatannol potently inhibited the rat brain mitochondrial F0F1-ATPase activity in both solubilized and submitochondrial preparations (IC50 of 8-9 microM), while having relatively small effect on the Na(+), K(+)-ATPase activity of porcine cerebral cortex (no effect up to 7 microM). Piceatannol inhibited the ATPase activity of the purified rat liver F1 with IC50 of about 4 microM, while resveratrol was slightly less active (IC50 of about 14 microM). Our results indicate that piceatannol and resveratrol inhibit the F-type ATPase by targeting the F1 sector, which is located to the inner membrane of mitochondria and plasma membrane of normal endothelial cells and several cancer cell lines. This mechanism could potentially contribute to the multiple effects of these chemopreventive phytochemicals.

Animals↗
PubMed1999

Arsenic trioxide induces apoptosis of HPV16 DNA-immortalized human cervical epithelial cells and selectively inhibits viral gene expression.

Arsenic trioxide (As2O3), a major ingredient of arsenic compounds in traditional Chinese medicine, exhibits anti-acute promyelocytic leukemic activity. Considering that over 80% of human malignant tumors derive from epithelial cells, we studied the effect of As2O3 on HPV 16 DNA-immortalized human cervical epithelial cells (HCE16/3 cells) in vitro. As2O3 reduced HCE16/3 cell survival, induced apoptosis at a low concentration and selectively inhibited expression of viral early genes. This effect was evidenced by a reduction of cell viability in the MTT assay, G1 arrest and significant apoptosis upon flow-cytometric analysis, presence of apoptotic bodies, formation of DNA ladders upon gel electrophoresis and inhibition of viral early gene expression by RT-PCR and Western blot. There was a good correlation between cell apoptosis and viral early gene inhibition after As2O3 treatment, suggesting that induction of apoptosis of HCE16/3 cells by As2O3 treatment might be associated with down-regulation of viral oncogene expression. In conclusion, our findings indicate that As2O3 induces apoptosis of HCE16/3 cells, which may provide a new approach for treating HPV-associated tumors.

Antineoplastic Agents↗