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Biomedical subjects

J Sun

Publications and source records attributed to J Sun.

At least 415 records · Page 23Linked to original sources
PubMed1998

[Exfoliative cancer cells in the surgical field of breast cancer].

OBJECTIVE: To study the relationship between exfoliative cancer cells in the surgical field and pathological stages of breast cancer and provide a theoretical basis for killing or removing of the exfoliative cancer cells in the surgical field. METHOD: Cytological examination of surgical field washings was performed in 104 patients with breast cancer. The results and pathological stages were compared and analysed. RESULT: Exfoliative cancer cells were found in the surgical field washings in 36 of 104 (34.6%). Stage I, II and III showed a positive rate of 3.8%, 29.8% and 85.7%. The positive rate of T(1), T(2) and beyond T(3) were 10.8%, 33.3% and 77.3%, respectively. When the number of axillary metastatic lymph nodes was over four, the positive rate of exfoliative cancer cell was 76.0% and only 13.5% if no axillary lymph node metastasis. CONCLUSION: Killing or removing of the exfoliative cancer cells in the surgical field of breast cancer is necessary.

Biopsy↗
PubMed1998

[Bile salt induces apoptosis of hepatocytes: the mechanism of hepatic function injury during obstructive jaundice].

OBJECTIVE: To determine if the bile salt induces hepatocyte apoptosis in vitro. METHOD: Hepatocytes were isolated by in situ collagenase perfusion and plated in 6 well flat bottom with DMEM/F12, 0.5 micro/ml insulin. Two hours later, glycochenodeoxcholate (GCDC) 25, 50, 100, 200, 300 micromol was added and cells evaluated by DNA-PI staining FACS and terminal-deoxynucleotidyl transferase mediated nick end labeling (TUNEL) 3, 6, 9, 12, 18, 20, 24 hours later. Agarose gel electrophoresis of DNA extracted from hepatocytes after incubation with GCDC using various experimental conditions. RESULT: The hepatocytes treated with GCDC have a high apoptotic rate as compared with the controls. 100 micromol GCDC treated 24 hours, nearly 61.81% of hepatocytes were apoptotic by FACS evaluation. The TUNEL showed that apoptotic hepatocytes had less cell volume and stained with brown by Biotin-11-dUTP. DNA ladder of bile-salt treated hepatocytes were shown in agarose gel electrophoresis. CONCLUSION: The mechanism of hepatic injury during obstructive jaundice is related to bile salt caused hepatocyte apoptosis.

Animals↗
PubMed1998

[Cloning, sequencing and expression of hepatitis E virus structural gene in E. coli and application of the recombinant products for diagnosis].

The prokaryotic expression vector PEGX-3X was used to express hepatitis E virus (HEV) open reading frame 2(ORF2 402-660). The recombinant protein was soluble in PBS buffer and was purified by the glutathione Sepharose 4B affinity column. When the purified recombinant protein was applied to detect HEV antibodies in sera of clinical patients, the results were quite consistent with the HEV diagnostic kit from Diagnostic Biotechnology Ltd(DBL), Singapore. The recombinant protein was more reactive with HEV antibodies than DBL reagent.

Antigens, Viral↗
PubMed1998

[A new genus of oral bacteria in human].

A strain, No. 90-1, is isolated from the oral cavity of a patient with periodontophthy. This strain is a Gram-positive, non-endospore-forming, facultative anaerobe with spherical cells, 0.9-1.5 microns in diameter, occuring in pairs and seldom in short chains of four cells, and motile by one flagellum per cell. The optimum growing temperature is 35-37 degrees C; appreciable growth is not found below 10 degrees C, but growth at 53 degrees and tolerance to 60 degrees C for 30 min. This strain is microhalophilous and grows best, well and poorly in the medium containing 2%, 10%-15% and 25% NaCl respectively. Catalase and urease are positive and nitrate is reduced. Acid is produced from many carbohydrates, but no gas. Gelatin can be hydrolyzed, but starch, cellulose and dextrin do not. G + C content in DNA is 41.34 mol%(Tm). The strain(90-1) is considered to be a new species belonging to a new genus because its some characteristics are different from those of the known coccus genuera and designated as Stomatostreptococcus microhalophilus Ping, Zhou, Sun et Fan gen. nov. sp. nov. according to its source and microhalophilic trait.

Humans↗
PubMed1998

[Strain of screening high toxin--producing from Corynebacterium diphtheria PW8-weissensee].

Corynebacterium diphtheria PW8-weissensee was grown on different media for screening high toxin produce. Through six times of screening (selecting butyrous brilliant smooth small colonies and testing their toxin production capacity) from original strain producing toxin 160 Lf/ml, a high toxin--producing descendand culture was obtained, which produced 79% more toxin than the original strain did.

Corynebacterium diphtheriae↗
PubMed1998

[Crackle detection and classification based on matched wavelet transform].

In this paper, we present a method for crackle detection which is based on 'matched' wavelet transform. We first modeled crackles as a mathematical function. Then we designed a matched mother wavelet based on this model. Applying a soft-threshold to the results of the continuous wavelet transform to suppress noise further, we obtained the optimal scale Crackles were detected based on the envelope of the signal at optimal scale, and could be classified based on energy distribution with scale. The theory, methods and experimental results are given in detail.

Algorithms↗
PubMed1998

[The thin film and absorption spectra of CsCu2I3].

This paper introduces a method of manufacturing CsCu2I3 thin films through hot evaporation. According to the absorption spectra at low temperature, the excitonic coefficient of CsCu2I3 was calculated. The spectral analysis shows that the localization of electron and exciton excitations in the twofold Chain created by CuI4(3-) causes the complicated character of the optical spectra of CsCu2I3.

English Abstract↗
PubMed1998

[Determination of trace lead in copper by enhancing effect FAAS-using derivative technique].

A new method for the determination of trace lead in copper is proposed by enhancing effect-flame atomic absorption spectrometry using derivative technique. Enhancing effect of matrix Cu on lead was investigated. The sensitivity for lead was enhanced 17 times than that of conventional flame atomic absorption spectrometry by combining derivative technique with matrix Cu enhancing effect. Determination result is satisfactory by this method with 0.007 microg/mL detection limit and 0.7% RSD.

English Abstract↗
PubMed1998

Positive biochemical effects of a bioartificial liver support system (BALSS) in a porcine fulminant hepatic failure (FHF) model.

This study describes biochemical changes in the plasma and blood of pigs with devascularised livers treated in a bioartificial liver support system (BALSS). Porcine hepatic cells were incubated with collagen-coated dextran microspheres (CDM) for 3 hours and the medium tested to determine cellular metabolic activity. Incubation continued for a further 18 hours during which the hepatic cells attach to the CDM. The CDM-attached cells were inoculated into a hollow fibre bioreactor which was part of an extracorporeal support system. Hepatic cell content of the bioreactor was 6 x 10(9) cells. The system was tested in a controlled trial in pigs prepared in a surgical model of fulminant hepatic failure (FHF). When plasma from FHF pigs was circulated through the device containing hepatic cells, there was significantly less increase in the accumulation of ammonia and most amino acids, together with a decrease in plasma lactate and of one amino acid, compared to control experiments when hepatic cells were excluded. We conclude that primary porcine hepatocytes can contribute beneficial metabolic function in a BALSS.

Adenosine Triphosphate↗
PubMed1998

Differential display detects altered gene expression between cataractous and normal human lenses.

PURPOSE: To identify and analyze differentially genes expressed between lens epithelia dissected from age-related cataractous and noncataractous human lenses. METHODS: RNAs from 50 pooled cataractous and 25 pooled noncataractous epithelia were compared by reverse transcription-polymerase chain reaction differential display (RT-PCR-DD). Two differentially displayed bands were chosen for further study. These were reamplified, cloned, and sequenced. Expression of these genes was further evaluated in pooled and individual epithelia by RT-PCR with gene-specific primers. RESULTS: Significant differences in gene expression were detected between the cataractous and the noncataractous epithelia. Three mRNAs displayed higher levels and 12 mRNAs displayed lower levels of expression in the cataractous samples compared with that in the noncataractous samples. Of the mRNAs expressed at higher levels, one was identified as metallothionein IIa (METII). Of the mRNAs with decreased expression, one was identified as protein phosphatase 2A regulatory subunit (P2A-RS). Overexpression of METII and underexpression of P2A-RS were confirmed in pooled and individual epithelia. CONCLUSIONS: These results provide evidence that age-related cataract is associated with alterations in the expression of multiple epithelial genes including METII and P2A-RS. METII is a detoxification protein induced by oxidative stress, and P2A-RS is a mitotic suppressor involved in cell-cycle control. These results implicate these proteins and their associated functions in the maintenance of lens transparency.

Adult↗
PubMed1998

Spinal cord protection by papaverine and intrathecal cooling during aortic crossclamping.

AIM: To extend the safe period of aortic crossclamping in the porcine model by intrathecally dilating the spinal arteries, with cooling of the spinal cord, or using selfoteL METHODS: Experimental design and setting: prospective domestic laboratory pig study. INTERVENTIONS: fifteen animals were assigned to a control group (C, N=5), intrathecal papaverine plus spinal cord cooling group (IP+C, N=5), or selfotel group (S, N=5). In the IP+C group, a lumbar laminectomy was performed and an intrathecal catheter placed for intrathecal injection of papaverine and perfusion with cold Ringer's solution (4 degrees C) prior to aortic crossclamping. In the selfotel group, 20 mg/kg of selfotel was administered 30 minutes before aortic crossclamping. In all 15 animals, the aorta was crossclamped for 60 minutes at normothermia. MEASURES: immediately after the operation and 24 hours later, lower limb function was evaluated. RESULTS: All five control animals were paralyzed; all 5 IP+C animals could stand or walk (p=0.004 versus control); and in the selfotel group, one had paraparesis, three had paraplegia and one died before evaluation (p=n.s.) CONCLUSIONS: The combination of intrathecal papaverine to dilate spinal arteries and prevent spasm from the cold solution plus intrathecally cooling the spinal cord appears to extend the period of safe aortic crossclamping. Selfotel, in this model of extended, severe, spinal cord ischemia, was ineffective.

Administration, Topical↗
PubMed1997

Comparison of the roles of CD8 alpha alpha and CD8 alpha beta in interaction with MHC class I.

The CD8 molecule is expressed either as an alpha/alpha homodimer or an alpha/beta heterodimer on thymocytes and cytotoxic T cells, and functions as a coreceptor in concert with TCR for binding the MHC class I/peptide complex. Although CD8alpha/beta heterodimers have been shown to be more effective coreceptors, the precise role of the beta-chain in TCR-mediated thymic maturation and T cell activation is not understood. To understand the role of CD8beta in mediating CD8/MHC class I interaction, we examined whether cell surface CD8alpha/beta heterodimer promotes better cell-cell adhesion with MHC class I than the CD8alpha/alpha homodimer. The abilities of different forms of CD8 to adhere to MHC class I were measured with a cell-cell binding assay. Using a wild-type CD8beta and -alpha, we found that CD8alphabeta heterodimers did not mediate greater cell-cell adhesion than CD8alphaalpha homodimers. Furthermore, we found that chimeric CD8beta-alpha homodimers afforded no detectable binding. These results do not support the idea that CD8alphabeta binding to MHC class I is greater than that of CD8alphaalpha. Rather, they point to an alternative explanation in which CD8beta may play an role in promoting CD8/TCR interaction and/or in signaling/regulatory pathways.

Animals↗
PubMed1997

Topology of allosteric regulation of lactose permease.

Sugar transport by some permeases in Escherichia coli is allosterically regulated by the phosphorylation state of the intracellular regulatory protein, enzyme IIAglc of the phosphoenolpyruvate:sugar phosphotransferase system. A sensitive radiochemical assay for the interaction of enzyme IIAglc with membrane-associated lactose permease was used to characterize the binding reaction. The binding is stimulated by transportable substrates such as lactose, melibiose, and raffinose, but not by sugars that are not transported (maltose and sucrose). Treatment of lactose permease with N-ethylmaleimide, which blocks ligand binding and transport by alkylating Cys-148, also blocks enzyme IIAglc binding. Preincubation with the substrate analog beta-D-galactopyranosyl 1-thio-beta-D-galactopyranoside protects both lactose transport and enzyme IIAglc binding against inhibition by N-ethylmaleimide. A collection of lactose permease replacement mutants at Cys-148 showed, with the exception of C148V, a good correlation of relative transport activity and enzyme IIAglc binding. The nature of the interaction of enzyme IIAglc with the cytoplasmic face of lactose permease was explored. The N- and C-termini, as well as five hydrophilic loops in the permease, are exposed on the cytoplasmic surface of the membrane and it has been proposed that the central cytoplasmic loop of lactose permease is the major determinant for interaction with enzyme IIAglc. Lactose permease mutants with polyhistidine insertions in cytoplasmic loops IV/V and VI/VII and periplasmic loop VII/VIII retain transport activity and therefore substrate binding, but do not bind enzyme IIAglc, indicating that these regions of lactose permease may be involved in recognition of enzyme IIAglc. Taken together, these results suggest that interaction of lactose permease with substrate promotes a conformational change that brings several cytoplasmic loops into an arrangement optimal for interaction with the regulatory protein, enzyme IIAglc. A topological map of the proposed interaction is presented.

Allosteric Regulation↗
PubMed1997

Differential expression of isoforms of PSD-95 binding protein (GKAP/SAPAP1) during rat brain development.

PSD-95/SAP90, which binds to the C-terminus of NMDA receptor and Shaker-type potassium channel, is one of the major postsynaptic density proteins. Recently, novel classes of proteins interacting with the guanylate kinase domain of PSD-95 have been identified, guanylate kinase-associated protein (GKAP) and SAP90/PSD-95-associated proteins (SAPAPs). Here we report the isolation of new isoforms of PSD-95 binding protein (GKAP/SAPAP1) using the yeast two-hybrid system. The isolated protein directly interacts with the guanylate kinase domain of PSD-95. Northern blot analyses revealed that the expression of these isoforms containing distinct N-terminal sequences is differentially regulated during brain development. The present findings suggest that each isoform of the PSD-95 binding protein is differentially expressed in a development-dependent manner and may be involved in the complex formation of PSD-95 and channel/receptors at the postsynaptic density.

Amino Acid Sequence↗
PubMed1997

Does retrograde warm blood cardioplegia provide equal protection to both ventricles? A magnetic resonance spectroscopy study in pigs.

BACKGROUND: The degree of protection provided to the right ventricle during retrograde continuous normothermic blood cardioplegia (RCNBC) remains controversial. The purpose of this study was to determine whether RCNBC is able to provide "adequate" nutritive flow to both ventricles to prevent ischemic metabolism in normal swine hearts. Localized 31P magnetic resonance spectroscopy (MRS) was used to monitor the changes in energy metabolism and intracellular pH (pHi) in each ventricle separately. METHODS AND RESULTS: Isolated normal swine hearts received 20 minutes of antegrade continuous normothermic blood cardioplegia (ACNBC) for collection of control (baseline) data, followed by 20 minutes of RCNBC. This protocol was repeated four times in five hearts and twice in two hearts. Perfusion pressure was maintained between 70 to 85 and 38 to 43 mm Hg during ACNBC and RCNBC, respectively. pHi, creatine phosphate (PCr), inorganic phosphate (Pi), and ATP were measured continuously in each ventricle during ACNBC and RCNBC, using localized 31P MRS with two surface coils. RCNBC resulted in a significant increase in Pi (LV 222% and RV 244% of the baseline levels, respectively) and a decrease in PCr (left ventricle [LV] to 68% and right ventricle [RV] to 31% of the baseline levels, respectively) in both ventricles relative to ACNBC. The PCr level was significantly lower in the RV than in the LV (31% versus 68%, P<.001) during RCNBC. In one series of experiments (n=5) where ACNBC and RCNBC were alternated every 20 minutes (ACNBC, RCNBC, ACNBC, RCNBC, ACNBC) for a total of 100 minutes, Pi and PCr recovered completely. A continuous and significant decrease in ATP was observed in the RV, and no recovery of ATP was found when switching from RCNBC to ACNBC. No significant decrease in ATP was observed in the LV. pHi remained unchanged in both ventricles during alternate ACNBC and RCNBC. CONCLUSIONS: Energy metabolism in the RV is less well preserved than in the LV during RCNBC. A combination of ACNBC and RCNBC seems to provide good cardiac protection as measured by the recovery of cardiac energetics and pHi.

Adenosine Triphosphate↗
PubMed1997

Limits to the differential avidity model of T cell selection in the thymus.

It has been postulated that the critical feature that determines the developmental fate of an immature thymocyte is the avidity of interaction between thymocyte TCR and peptide/MHC molecules on thymic stromal cells. However, it is possible that certain innate properties of peptides predispose them to triggering only positive or negative selection irrespective of their density on thymic stromal cells. To distinguish between these hypotheses, we examined the ability of several different peptides to induce the positive and negative selection of TCR transgenic (P14) antilymphocytic choriomeningitis virus (LCMV) CTLs in fetal thymus organ cultures (FTOC) from TAP1+ and TAP1- mice. We found that only relatively weak agonist peptides could induce the positive selection of anti-LCMV CTLs. A nonagonist peptide could induce positive selection but not negative selection; however, a weak agonist peptide could induce the positive selection of anti-LCMV CTLs in P14 TAP1- FTOC and negative selection in P14 TAP1+ FTOC. These data imply that there are upper and lower limits for the affinity of a peptide in triggering positive or negative selection, but that for peptides of intermediate affinity the overall avidity of interaction with the P14 TCR is the critical parameter in determining the developmental fate of thymocytes. Our observations also suggest a prominent role for low affinity self peptides in selecting a function repertoire of CD8+ T cells.

Animals↗
PubMed1997

The geranylgeranyltransferase-I inhibitor GGTI-298 arrests human tumor cells in G0/G1 and induces p21(WAF1/CIP1/SDI1) in a p53-independent manner.

Recently we have shown that in fibroblasts (NIH 3T3 and Rat-1 cells) inhibition of protein geranylgeranylation leads to a G0/G1 arrest, whereas inhibition of protein farnesylation does not affect cell cycle distribution. Here we demonstrate that in human tumor cells the geranylgeranyltransferase-I (GGTase-I) inhibitor GGTI-298 blocked cells in G0/G1, whereas the farnesyltransferase (FTase) inhibitor FTI-277 showed a differential effect depending on the cell line. FTI-277 accumulated Calu-1 and A-549 lung carcinoma and Colo 357 pancreatic carcinoma cells in G2/M, T-24 bladder carcinoma, and HT-1080 fibrosarcoma cells in G0/G1, but had no effect on cell cycle distribution of pancreatic (Panc-1), breast (SKBr 3 and MDAMB-231), and head and neck (A-253) carcinoma cells. Furthermore, treatment of Calu-1, Panc-1, Colo 357, T-24, A-253, SKBr 3, and MDAMB-231 cells with GGTI-298, but not FTI-277, induced the protein expression levels of the cyclin-dependent kinase inhibitor p21WAF. HT-1080 and A-549 cells had a high basal level of p21WAF, and GGTI-298 did not further increase these levels. Furthermore, GGTI-298 also induces the accumulation of large amounts of p21WAF mRNA in Calu-1 cells, a cell line that lacks the tumor suppressor gene p53. There was little effect of GGTI-298 on the cellular levels of another cyclin- dependent kinase inhibitor p27KIP as well as cyclin E and cyclin D1. These results demonstrate that GGTase-I inhibitors arrest cells in G0/G1 and induce accumulation of p21WAF in a p53-independent manner and that FTase inhibitors can interfere with cell cycle events by a mechanism that involves neither p21WAF nor p27KIP. The results also point to the potential of GGTase-I inhibitors as agents capable of restoring growth arrest in cells lacking functional p53.

Alkyl and Aryl Transferases↗