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Biomedical subjects

Z Sun

Publications and source records attributed to Z Sun.

At least 109 records · Page 6Linked to original sources
PubMed2000

Effects of N-acetylcysteine on pulmonary macrophage activity after intestinal ischemia and reperfusion in rats / with invited commentaries.

BACKGROUND/AIMS: Intestinal ischemia and reperfusion (I/R) is considered to be a critical and triggering event in the development of distal organ dysfunction after a variety of insults. It appears that activated leukocytes, especially polymorphonuclear granulocytes (PMNs), and reactive oxygen species are important mediators in the process. In the present study, the aim was to evaluate the behavior of pulmonary macrophages, acute lung injury and pulmonary endothelial permeability after intestinal I/R, together with potential alterations in pulmonary endothelial and epithelial ultrastructure and cellular membrane system integrity. METHODS: Intestinal ischemia for 40 min was followed by reperfusion for 12 h in the rat. Macrophage uptake of radiolabeled bacteria, levels of pulmonary blood content assessed by radiolabeled red blood cells and pulmonary endothelial permeability of radiolabeled albumin, as well as pulmonary endothelial and epithelial ultrastructure and cellular membrane system integrity by the use of scanning electron microscopy and a tracer was evaluated after 12 h reperfusion. Treatment with the free radical scavenger N-acetylcysteine (NAC) administered prior to reperfusion was evaluated. RESULTS: Overactivation of pulmonary macrophages was noted after intestinal I/R, as was a significant decrease in pulmonary blood content. No increase in pulmonary albumin leakage or increase in pulmonary water content was found after intestinal I/R as compared to controls. Treatment with NAC prevented against intestinal I/R-induced overactivation of pulmonary macrophages and a decrease in pulmonary blood content. CONCLUSION: Reactive oxygen species may be involved in the regulation of pulmonary macrophage function and pulmonary circulation after intestinal I/R.

Acetylcysteine↗
PubMed2000

Accumulation of synaptosomal-associated protein of 25 kDa (SNAP-25) and other proteins associated with the secretory pathway in GH4C1 cells upon treatment with estradiol, insulin, and epidermal growth factor.

Treatment of rat pituitary GH4C1 cells with estradiol, insulin, and epidermal growth factor induces secretory granule accumulation, PRL storage, and stabilization of ICA512, a membrane protein associated with secretory granules. In these investigations we found that the same treatment induced accumulation over 2-fold of other proteins in the secretory pathway, including synaptosomal-associated protein of 25 kDa (SNAP-25), synaptotagmin III, synaptobrevin, synaptophysin, and cyclophilin B, and did not affect accumulation of others, including synaptotagmin I, calnexin, and glucose-regulated protein 94. The induction of proteins was not a coordinate event, because epidermal growth factor alone maximally stimulated SNAP-25 accumulation, but not that of synaptotagmin III. Induction of SNAP-25 accumulation occurred without an increase in its synthesis, and induction of cyclophilin B occurred without an increase in its messenger RNA accumulation, suggesting that accumulation may be caused by stabilization of the proteins. SNAP-25 immunofluorescence was located in the cytoplasm and on the plasma membrane and sometimes was heavily concentrated in protrusions from the cell surface, especially in hormone-treated cells. Frequenin immunofluorescence was also sometimes concentrated in intense patches, but did not colocalize with SNAP-25. Growth hormone and prolactin immunofluorescence was not found in the protrusions and sometimes did not colocalize with each other when they were present in the same cell. Hormone treatment of GH4C1 cells therefore induces accumulation of specific proteins in all parts of the secretory pathway and causes morphological changes in addition to accumulating secretory granules.

Animals↗
PubMed2000

[Targeting studies of humanized scFv25 fusing to TNFalpha against hepatocellular carcinoma].

OBJECTIVE: To obtain humanized engineering bifunctional antibody, which has potentialities for clinical application. METHODS: Humanized anti-human hepatocellular carcinoma (HCC) single chain fragment (hscFv25) was linked with human TNF-alpha gene to form anti-HCC bifunctional antibody, then it was subcloned into prokaryotic GST fusion expression vector pGEX 4T-1 and expressed in the host E.coli. Indirect immunofluorescent staining was performed on HCC cell smearing slides in order to evaluate the activity of the purified aim protein, then MTT trial to evaluate the cytotoxicity of hscFv25-TNFalpha to SMMC-7721, finally primary tumor regression trial in nude mice bearing HCC to evaluate the targeting therapeutic value of hscFv25-TNFalpha. RESULTS: The hscFv25-TNFalpha had the similar specificity to parental antibody HAb25 for SMMC-7721 antigen. One hour predisposed MTT trial in control with parental antibody HAb25 affirmed that hscFv25-TNFalpha was cytotoxic to targeted cell SMMC-7721 with the IC(50) to be 7.1 microg/ml. The cytotoxicity can be inhibited by parental antibody HAb25. This indicated that the cytotoxicity of hscFv25-TNFalpha to targeted cell is antibody-mediated selective cytotoxicity. The tumor regression trial to the 3mm HCC xenografts in nude mice showed that hscFv25-TNFalpha had assured targeting cytotoxicity and the efficiency was nearly up to 3/3 (1/3 complete remission, 2/3 partial remission). The cytotoxicity of the hscFv25-TNFalpha was better than that of TNFalpha, whose efficiency was only 2/3 and without complete remission. CONCLUSION: hscFv25-TNFalpha is an anti-HCC bi-functional antibody which has potentialities for clinical application.

Animals↗
PubMed2000

[Establishment and its application of a reporter-based screening model for discovering new ligands of estrogen receptor alpha subtypes].

AIM: To establish a sensitive and efficient reporter gene based screening model and use it to screen compounds for discovering new ligands of estrogen receptor alpha subtype. METHODS: A recombinant Epstein-Barr virus episomal vector (pMT/ERE-CAT) was constructed by inserting a synthetic sequence composed of five estrogen response elements upstream of promoter and a chloramphenicol acetyltransferase (CAT) gene downstream of promoter. pMT/ERE-CAT was transfected into HepG2 cells expressing estrogen receptor alpha subtype (ER +HepG2). Hygromycin (200 micrograms.mL-1) was added 48 h after transfection for selection. One stably transfected clone was isolated and used to screen compounds for activity of stimulating CAT gene expression using colorimetric CAT assay. RESULTS: In the ER +HepG2 cells, the expression of CAT gene was induced by estradiol. A dose-dependent expression of CAT gene with half-maximal induction at 0.07 nmol.L-1 was observed. The ER +HepG2 cell was used to screen compounds for activity of stimulating CAT gene expression. Resveratrol was found to produce a maximal level of induction (1.75 times of estradiol). In vitro radiation survival experiment showed that the radioprotection activity of resveratrol (D0 = 3.18 Gy) is stronger than that of estradiol (D0 = 2.59 Gy). CONCLUSION: Vector pMT/ERE-CAT was used to generate stably transfected ER +HepG2 cell lines. The cell lines can be used to screen compounds for estrogen activity by testing extracts of cells grown in microtiter wells directly using colorimetric CAT assay. This system should provide an efficient method for screening and analyzing the activity of large numbers of ligands of estrogen receptor.

Chloramphenicol O-Acetyltransferase↗
PubMed2000

[Shear bond strength of glass ionomer cement for orthodontic bracket bonding].

OBJECTIVE: The purpose of this study was to investigate the shear bond strength of resin-modified glass ionomer used for orthodontic bracket bonding. METHODS: 30 extracted premolars were evenly divided into two groups. Edgewise brackets (Orsu) were bonded with resin-modified glass ionomer (Advance) in group one and with composite resin (DM) in group two. The shear bond strengths of two materials were tested by material testing machine after 24 hours. The adhesive remnant index was scored after debonding. RESULTS: The shear bong strengths of resin-modified glass ionomer and composite resin were (6.862 +/- 2.142) MPa and (7.183 +/- 3.205) MPa respectively. There were no statistically significant differences between two groups. CONCLUSIONS: In vitro bond strength of resin-modified glass ionomer had reached the same level of composite resin. It had the prospect of clinic use.

Composite Resins↗
PubMed2000

[The correlation analysis between frequency of micronucleated cells of exfoliated oral mucosa cells and oral mucosa cells in different grading of oral leukoplakia lesions].

OBJECTIVE: To provide evidence for using micronucleated cells of exfoliated oral mucosa cells in diagnosis and treatment of oral leukoplakias and chemopreventive studies of oral cancer. METHODS: Micronuclei of exfoliated oral mucosa cells and oral mucosa cells in 119 patients comprising 59 simple hyperplasia, 32 mild and moderate oral leukoplakia and 28 severe oral leukoplakia and oral squamous carcinoma by Feulgen stain method were examined, and micronuclei of exfoliated oral mucosa cells in 100 normal persons were also examined. RESULTS: Frequency of micronucleated cells of exfoliated oral mucosa cells in oral leukoplakia lesions was higher than that of normal persons. Frequency of micronucleated cells of exfoliated oral mucosa cells had a positive correlation with oral leukoplakia lesions(r = 0.9997, P < 0.001) and with frequency of micronucleated cells of oral mucosa cells (P < 0.001). CONCLUSIONS: Frequency of micronucleated cells of exfoliated oral mucosa cells are useful markers to the clinician to predict oral leukoplakia behaviour and prognosis and substitute for frequency of micronucleated cells of oral mucosa cells as intermediate endpoint in chemopreventive trials.

Adult↗
PubMed2000

[Cardiac protective effects of tetramethylpyrazine in patients performed open-heart operation with cardiopulmonary bypass].

OBJECTIVE: To study the cardiac protective effects of tetramethylpyrazine (TMP) on patients undergoing cardiac operation. METHODS: Twelve patients with rheumatic heart disease were randomly divided into the TMP group and the control group, 6 in each group. The changes of hemodynamics, serum creatine phosphokinase (CPK), creatine phosphokinase isoenzyme (CPK-MB) levels were observed before, during and 72 hours after operation. RESULTS: The hemodynamic indexes in the TMP group were better than those in the control group after operation, the serum CPK, CPK-MB levels measuring 12 h, 24 h and 48 h after operation in the TMP group were lower than those in the control group. CONCLUSION: TMP has good cardiac protective function in patients undergoing cardiac operation in improving cardial function and reducing the release of myocardial enzymes.

Adult↗
PubMed2000

[The age-related effect of basic fibroblast growth factor on the proliferation of lens epithelial cells].

OBJECTIVE: To detect the age-related effect of basic fibroblast growth factor (bFGF) on the proliferation of human lens epithelial cells (HLECs) in patients with cataract and discuss the mechanism. METHODS: Human lens anterior capsules with attached HLECs were cultured in vitro, treated with 10 microg/L bFGF for 48hr, and then the positive area ratio of proliferating cell nuclear antigen (PCNA) in immunohistochemistry was estimated. Immunohistochemical analysis of bFGF receptor was also carried out. RESULTS: The bFGF could enhance the HLEC proliferation in patients with cataract at various ages. The enhancement of the proliferation and the expression of bFGF receptor protein were negatively correlated to the age of the patients with cataract (P < 0.01). CONCLUSIONS: The basic fibroblast growth factor might play an important role in the formation of posterior capsular opacity (PCO) after cataract surgery. With the decrease in the patient's age, the enhancement of HLEC proliferation is increased, indicating that the fact is related to the high incidence of PCO in children.

Adolescent↗
PubMed2000

[Adherence of bovine lens epithelial cells to the surface of intraocular lens made of different materials].

OBJECTIVE: To compare the in vitro adherence of bovine lens epithelial cells (BLEC) onto the surface of intraocular lens (IOL) made of 4 different materials: polymethylmethacrylate (PMMA), silicone (SI), hydroxyethylmethacrylate (HEMA) and acrylic (Acrysof, ACRY). METHODS: BLEC were incubated with IOLs four 48 hours. Adherent cells were counted by flow cytometry technique. RESULTS: The amount of the adherent cells on IOLs of ACRY was the highest, that of HEMA the least, and there was no significant difference between the amount on PMMA and SI IOLs (P > 0.05). CONCLUSIONS: Adherence of lens epithelial cells to IOLs is influenced by the surface property of IOL materials, which may influence the occurrence of postoperative capsular opacification after IOL implantation.

Animals↗
PubMed2000

[Effect of oxidatively modified high density lipoprotein on transcriptional expression of proto c-fos and PDGF receptor genes in cultured human arterial smooth muscle cell].

The proliferation of arterial smooth muscle cell (SMC) plays an important role in the process of atherosclero-genesis. Using the establishment of primary culture and sub-culture method for human arterial SMC, we observed the effects of native HDL (N-HDL) and oxidized HDL of proto c-fos and PDGF receptor genes transcriptional expression in cultured SMC. The results showed that N-HDL had no effect on the expression of proto c-fos and PDGF receptor genes in the cultured human SMC, that OX-HDL had no effect on the expression of PDGF receptor gene in the cultured human SMC, and that OX-HDL promoted the expression of protoc-fos gene significantly (P < 0.01). These results suggest that the OX-HDL's atherogenic role is closely related to its stimulating effect on proto c-fos gene expression of SMC.

Aorta↗
PubMed2000

[In vitro antiviral activity of antisense oligonucleotides against influenza virus].

For developing of antisense oligonucleotides as potential antiviral therapeutic agents against influenza A virus, phosphorothioate oligodeoxynucleotides(PS-ODN) targeted to part to the 3' and 5' end sequences which are common to the eight RNAs of type A influenza virus were synthesized. The in vitro cytotoxicity of these PS-ODNs was assayed and then antiviral activity of these PS-ODNs was evaluated by using cultured MDCK cells infected by A/JingFang/86-1(H1N1). It was found that(1) No in vitro cytotoxicity was seen when concentration of PS-ODN was up to 50 mumol/L. (2) Oligonucleotides(IV4 #) complementary to 5' terminal conserved sequences and ODN(IV6 #, IV7 #)composed by 3'/5' terminal conserved sense sequences or antisense sequences all exhibited the most potent antiviral activity. IV4 # ODN exhibited significant antiviral activity with reduced hemegglutination titer about 50% at concentration of 1 mumol/L, and over 70% at 10 mumol/L. The antiviral activity of IV4 # was in a dose- and sequence-dependent manner. (3) IV4 # ODN showed significant antiviral activity not only against H1N1 subtype strains of influenza virus, but also against H3N2 subtype strains. (4) The multiplicity of infection(MOI) of influenza virus had effects on antiviral activity of IV4 # ODN. IV4 # ODN showed better dose-dependent antiviral activity when there was lower MOI. These results suggested the the 3'/5' terminal sequences of influenza A virus could be used as a target for designing antiviral oligonucleotides against influenza A virus.

Animals↗
PubMed2000

[Indirect determination of iodide by flame atomic absorption spectrometry].

A new method was developed for the indirect determination of iodide by flame atomic absorption spectrometry (FAAS). Precipitation of CuI, obtained with the reaction of Cu+ with I, was dissolved in Na2S2O3. Copper content in the solution was determined by FAAS and the iodide content was calculated using the content of copper. The linear range of the proposed method is 0-800 micrograms. mL-1 of I-, and the relative standard derivation at 0.4 mL of I level is 0.7%. The proposed method was applied to determination of iodine in iodized tablets salt, cydiodine tablets and laver with a recovery range of 99.9%-100.3%.

Humans↗
PubMed2000

[Study on the third-order nonlinear optical effect of fused-cyclic aromatic hydrocabon].

The third-order nonlinear optical susceptibility X(3), nonlinear refractive index n2 and time response property of 1,2,5,6,dibenzathracene (C22H14) and dibenzopentacene (C30H18) in fused-cyclic aromatic hydrocarbon were studied with forward degenerate four-wave mixing (DFWM). The mechanism for their larger nonlinear effect and faster time response was discussed.

English Abstract↗
PubMed2000

[Spectral interferences of rare earth elements with a high resolution sequential ICP-AES. IV. Spectral interferences of europium and gadolinium].

The spectral interferences of Eu and Gd(100 micrograms.mL-1, separately) as matrices on the other REEs(1 or 5 micrograms.mL-1) were studied with a high resolution sequential ICP-AES with a grating of 3,600 grooves/mm. Totally 66 prominent lines of 14 REEs were selected as the analytical lines for the spectral interference studies. The overlapping profiles of analytical lines and interference lines were obtained by scanning four solutions(blank, analyte, Eu matrix, and Gd matrix, individually) within the selected wavelength windows (0.2 nm for each analytical line). Some new emission lines of Eu and Gd were observed. The obtained information of spectral interferences would be very useful for the selection of the best analytical lines for the determination of REEs in the other REEs matrices.

Europium↗
PubMed2000

[Spectral interferences of rare earth elements observed with a high resolution inductively coupled plasma atomic emission spectrometer. V. Spectral interferences of lutetium, thulium, yttrium and ytterbium as matrices].

The spectral interferences of Lu, Tm, Y and Yb (100 microns.mL-1, separately) as matrices on the other REEs (1 or 5 microns.mL-1) were observed with a high resolution ICP-AES with a grating of 3,600 grooves.mm-1. Totally 66 analytical lines of 15 REEs were selected as the prominent lines for spectral interference studies. The "Q" values and "the true detection limit" were calculated for the selected prominent lines with the exist of the four matrix elements. The obtained information is useful in the selection of the best analytical lines for the determination of REEs in the other REEs' matrices.

Lutetium↗
PubMed1999

A simple and sensitive antigen retrieval method for free-floating and slide-mounted tissue sections.

The masking of antigens by aldehyde-containing fixatives or by paraffin embedding procedures is a problem for immunohistochemical studies. Enzymatic digestion, formic acid treatment, microwave heating and autoclave heating have been used to deal with this problem, with microwave heating-based antigen retrieval having become widely used as the method of choice. Microwave heating, however, has the shortcoming that it is difficult to precisely control the heating temperature and it is difficult to apply this method of heating to free-floating sections without damaging the sections. We describe here a simple, reliable and sensitive antigen retrieval method that uses water-bath heating. By this method, the temperature can be precisely controlled to yield effective antigen retrieval with minimal tissue damage in free-floating or paraffin-embedded slide-mounted sections. We found that the best results were obtained with a 30 min incubation in a 10-50 mM sodium citrate solution (pH 8.5-9.0) preheated to and maintained at 80 degrees C in a water-bath, followed by 30 min incubation in 0.3-3% nonfat dry milk to reduce nonspecfic staining. This method is highly effective for both 40 microm free floating sections, slide-mounted cryostat sections and paraffin-embedded slide-mounted sections, and it works well for tissue from diverse species (human, rat, mouse, pigeon, and zebra finch) and for diverse antigens (e.g. enkephalin, substance P, huntingtin, GluR1, GFAP, and ubiquitin). This method was also found to enhance immunolabeling in glutaraldehyde-fixed tissue that had been prepared for ultrastructural examination, without having a deleterious effect on the ultrastructure.

Animals↗
PubMed1999

A Comparative Study of Surface Acid-Base Characteristics of Natural Illites from Different Origins.

The acid-base characteristics of naturally occurring illites, collected from different locations, were investigated by potentiometric titrations. The experimental data were interpreted using the constant capacitance surface complexation model. Considerable release of Al and Si from illite samples and subsequent complexation or precipitation of hydroxyl aluminosilicates generated during the acidimetric forward titration and the alkalimetric back titration, respectively, were observed. Therefore, the acidimetric supernatant, rather than the neutral one, was regarded as the system blank for each illite suspension to yield the surface site concentrations. In order to describe the acid-base chemistry of aqueous illite surfaces, two surface proton-reaction models, introducing the corresponding reactions between the dissolved aluminum species and silicic acid, as well as a surface Al-Si complex on homogeneous illite surface sites, were proposed as follows: The K(f2) constant in Model II was obtained by simulating the complex formation between the dissolved aluminum species and silicic acid that occurred in acidimetric supernatant when the hydroxide was added. Additionally, the following cation exchange reaction was also considered for a special case, where a large amount of K(+) is released during the corresponding acidimetric titration, in which a high concentration of protons are consumed. Optimization results indicated that both models could provide a good description of the titration behavior for all aqueous illite systems in this study. The intrinsic acidity constants for the different illites were similar in Model I, showing some generalities in their acid-base properties. Model I may be considered as a simplification of Model II, evident in the similarities between the corresponding constants. In addition, the formation constant for surface Al-Si species (complexes or precipitates) is relatively stable in this study. Copyright 1999 Academic Press.

Journal Article↗