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Y Sun

Publications and source records attributed to Y Sun.

At least 1,009 records · Page 56Linked to original sources
PubMed1989

Computation of diagnostic data from coronary sinus pressure: a comparison between two possible models.

We have evaluated two mathematical models to describe the increase in coronary sinus pressure (CSP) following pressure controlled intermittent coronary sinus occlusion (PICSO). The models are evaluated and compared on the basis of human and canine data. Both models were fitted by non-linear least squares algorithms. Next, derived quantities, such as plateau, rise-time and mean integral of the coronary sinus pressure were calculated from the model parameters. Corresponding quantities for the two models were compared with regard to mean values, rate of successful calculation and specific features characterizing the human or canine case. One model was found to be superior for investigational purposes. The other model was found to be more stable in critical situations and is therefore suggested for usage in closed loop regulation of PICSO. Physiologically, the differences in mean values of the derived quantities between the two models were found to be negligible. The formal statistical significance of the differences is but a consequence of the large number of PICSO cycles analysed.

Algorithms↗
PubMed1989

The inhibition of catalase by glutathione.

Reduced glutathione (GSH) inhibited catalase activity in a dose-dependent manner. DL-dithiothreitol (DL-DTT) and dithioerythritol (DTE) also inhibited catalase activity. The inhibition of catalase by GSH and DL-DTT could be reduced by NADPH. Polyacrylamide gel electrophoresis demonstrated the inhibition was partially reversible. The inhibition of catalase by GSH appeared to be partly due to superoxide radicals, since it was inhibited by active manganese superoxide dismutase, but not by heat-inactivated enzyme. Other chemical species also appear to take part in the inhibition, but they could not be identified.

Animals↗
PubMed1989

A prospective, controlled, double-blind, cross-over study of tripterygium wilfodii hook F in treatment of rheumatoid arthritis.

A polyglycosides of Tripterygium wilfodii hook F (TWH) preparation with a code name of T2 is used in the present double-blind, controlled, cross-over study on the treatment of 70 cases of rheumatoid arthritis (RA). An impressive curative effect of T2 is confirmed much more convincingly by the present study than that by the previously reported clinical open trials. The adverse reactions and the probable pharmacological mechanism of T2 are also discussed.

Adult↗
PubMed1989

Viral etiology of cervical carcinoma. Human papilloma virus and herpes simplex virus type 2.

The possible role of human papilloma virus (HPV) and herpes simplex virus type 2 (HSV-2) in the viral etiology of cervical carcinoma was investigated a series of cervical lesions were studied for the presence of HPV and HSV-2 DNA sequences as well as HPV and HSV-2 antigens by DNA dot blot hybridization technique and high-specificity PAP staining method. The results obtained were correlated with the histologic diagnosis. HPV 16 DNA sequences detected in cervical carcinoma biopsies were 43%, whereas HSV-2 DNA sequences were only 8%. HPV antigens detected in cervical dysplasia were 31%, whereas those detected in cervical carcinoma and cervicitis were the least. HSV-2 antigens were detected in chronic cervicitis, dysplasia and cervical carcinoma. The difference in positive rate between the cervical carcinoma and cervicitis groups was statistically significant, (chi-square test, P less than 0.01). No HPV DNA and HSV-2 DNA sequences were found in the same specimen, although both HPV DNA sequences and HSV-2 antigens were found in the same sample in some cases. The results indicate that the viral etiology of cervical carcinoma may be multifactorial. Both HSV-2 and HPV may be associated with cervical carcinoma, but the mechanisms involved are different. HSV-2 and HPV may act synergistically in the development of cervical carcinoma.

Antigens, Viral, Tumor↗
PubMed1989

[Immune restoration of local xenogeneic graft-versus-host reaction in cancer patients in vitro and reversal of cyclophosphamide-induced immune suppression in the rat in vivo by fractionated Astragalus membranaceus].

Through the process of fractionation, purification by gel filtration chromatography and thereafter the screening with an in vitro local xenogeneic graft-versus-host reaction (XGVHR) model, a fraction was identified as a potent immunorestorative agent and was designated "Fraction 3" (F3). Using the XGVHR in vitro as a model assay for T cell function again, F3 was studied on mononuclear cells (MNC) from 13 cancer patients and exhibited significant immunorestorative activity, with an increase in local XGVHR (compared to untreated cells) of 151.34 +/- 46.02 mm3 vs 57.80 +/- 16.44 mm3, P less than 0.001. The in vitro augmented immune reactions induced by F3 in cancer patients also significantly exceeded the local XGVHR observed in the untreated MNC derived from 9 normal donor controls (94.15 +/- 9.16 mm3, P less than 0.005). In a newly developed in vivo XGVHR animal model, pretreatment of rats with F3 resulted in a significant abrogation of the local XGVHR with a reversal of the immunosuppressive effect of cyclophosphamide from 99.42 +/- 9.2 mm3 (positive control) to 39.78 +/- 8.3 mm3 (P less than 0.001). This reversal was complete as the volume of the abrogated local XGVHR was comparable to that of the negative control (no cyclophosphamide-priming, saline injection only) 34.79 +/- 5.69 mm3 (P greater than 0.1). These results suggest that F3 retained the immunopotentiating activity of the original crude extract and form the rational basis for the use of Astragalus in immunotherapy.

Adjuvants, Immunologic↗
PubMed1988

Alternate pathways of DNA replication in Escherichia coli.

We have described the pcbA1 mutation which enables E. coli cells to replicate DNA in the absence of a functional dnaE gene product if DNA polymerase I (the polA gene product) is present. The pcbA1 mutation phenotypically suppresses multiple dnaEts and dnaEam alleles. The pcbA1/PolI replication pathway differs from normal in sensitivity to certain DNA-damaging agents such as methylmethane sulfonate (MMS) and a lack of damage-directed mutagenesis. We report here cloning of the pcbA1 gene in a multicopy plasmid. The pcbA1 mutation is detected only in cis; therefore, cloning necessitated gene eviction. The pcbA1 gene lies closely- linked to gyrB. We have demonstrated the physical presence of DNA polymerase I in the replicating holoenzyme complex by immunoblotting using dnaEam strains. We conclude that E. coli has two alternate replisome structures: REP-A, in which DNA polymerase I is the functional synthetic subunit; and REP-E, in which the alpha-subunit, product of the dnaE gene, is functional. To investigate further the role of individual DNA polymerases in replication, we have isolated the polB gene on multicopy plasmids.

Alleles↗
PubMed1988

Identification of disulfide-containing peptides by performic acid oxidation and mass spectrometry.

In addition to reducing the analysis time, the direct examination of proteolytic digests by fast atom bombardment mass spectrometry (FABMS) greatly extends the information that is available from peptide mapping experiments. Mass spectral data are particularly useful for identifying post-translationally modified peptides. For example, the molecular weight of a disulfide-containing peptide may be used to locate the disulfide bond in the protein from which the peptide was derived. This paper describes a new procedure, which is useful for identifying disulfide-bonded peptides. Peptides are treated with performic acid to modify certain residues and thereby cause a characteristic change in the peptide molecular weight. This change in molecular weight is determined by FABMS and used to help identify peptides. Results for a series of small peptides demonstrate that Cys, Met, and Trp are the only residues that undergo a change in molecular weight under the conditions used here. Furthermore, these changes in molecular weight are diagnostic for each of the residues. Cysteinyl-containing peptides are of particular interest, because their identification is essential for locating disulfide bonds. The molecular weight of a peptide increases by 48 mu for each cysteinyl residue present. This approach is used to identify peptides that contain both cysteinyl and cystinyl residues in the peptic digest of bovine insulin. The method is extended to the analysis of a tryptic digest of cyanogen bromide-treated ribonuclease A. A computer-assisted analysis procedure is used to demonstrate the specificity with which peptide molecular weight is related to specific segments of the protein.(ABSTRACT TRUNCATED AT 250 WORDS)

Chromatography, High Pressure Liquid↗
PubMed1988

Induction of beta-glucuronidase activity during dimethylhydrazine carcinogenesis and additive effects of cholic acid and indole.

The kinetic change of beta-glucuronidase (beta-G) activity was measured in mouse large intestinal mucosa during dimethylhydrazine (DMH) carcinogenesis with addition of cholic acid and/or indole. The experiment lasted 21 weeks. The enzyme activity began to increase significantly at 5th week after treatment of DMH with cholic acid and/or indole, and at 7th week with DMH alone. Then, increased activity remained the rest of the time. Mouse intestinal cancer induced by DMH injection are also shown to have an increased beta-G activity. The induction of beta-G activity in the early stage of DMH colon carcinogenesis and additive effects of cholic acid and/or indole may imply one mechanism of action of DMH as a carcinogen and cholic acid as a promoter in large intestinal cancer.

Adenocarcinoma↗
PubMed1988

Induction of ornithine decarboxylase and histidine decarboxylase activities in rat colon mucosa after application of 12-o-tetradecanoylphorbol-13-acetate (TPA), sodium deoxycholate and indole.

Ornithine decarboxylase (ODC) and histidine decarboxylase (HDC) activities of rat colon mucosa were induced after intrarectal instillation of 12-o-tetradecanoylphorbol-13-acetate (TPA) and sodium deoxycholate. After instillation of sodium deoxycholate, ODC and HDC activities increased rapidly and reached a peak at 4 h, then decreased quickly towards control levels. Both enzymes activities also increased significantly 4 h after instillation in animals treated with TPA and sodium deoxycholate plus indole. However, there were no changes in ODC and HDC activities from 0-8 h after indole administration. These data are the first to show the induction of HDC activity in colon mucosa by TPA and sodium deoxycholate and suggest that the induction of activities in these two enzymes might be one mechanism of their action as cancer promoters.

Animals↗
PubMed1988

Estimation of intramyocardial pressure and coronary blood flow distribution.

To characterize the intramyocardial pressure (IMP) and coronary blood flow distribution in a stenosed coronary circulation, we compared four analog circuits for modeling coronary impedance. The resistor (R)-diode (D) model simulates vascular collapse, and the capacitor (C) simulates compliance effect. Identification of the best model and magnitudes of the endocardial and epicardial IMPs (IMPendo and IMPepi) was done retrospectively using data from studies in 28 anesthetized swine. Performance evaluation was based on comparison of model predicted vs. observed coronary distal pressure (DP) waveforms and endocardial-to-epicardial (endo-epi) flow ratios as determined by radiolabeled microspheres. The R-D-C model gave the best performance at IMPendo = 1.1 times left ventricular pressure (LVP), and IMPepi = 0.1.LVP + 15 mmHg; with good fit to DP (r = 0.98, slope of regression line = 1.0) and estimates of endo-epi flow ratio (r = 0.78, slope = 1.01, P less than 0.02, SEE = 0.21, n = 139). The R-D model gave comparable results even though capacitance was omitted. Although R-C and R models predicted distal coronary pressure well, they failed to predict endo-epi flow ratios (r less than 0.50). The R-D-C and R-D models were applied in seven prospective studies. Both models generated reasonable estimates of endo-epi flow distribution (r = 0.78, n = 50). Thus the R-D-C or R-D models of the stenosed coronary circulation can be used to provide reliable estimates of transmural blood flow distribution.

Animals↗
PubMed1988

Superoxide dismutase activity during dimethylhydrazine colon carcinogenesis and the effects of cholic acid and indole.

Copper, zinc superoxide dismutase (Cu,ZnSOD) and manganese superoxide dismutase (MnSOD) activities were measured in mouse large intestinal mucosa during dimethylhydrazine (DMH) carcinogenesis. Mice were divided into five groups. Group A was subcutaneously injected with DMH (20 mg/kg) weekly and fed with a diet containing 0.2% cholic acid (C) and 0.8% indole (I). Group B was injected with DMH and given indole feeding. Group C was treated with DMH injection and cholic acid feeding. Group D was given DMH injection alone. Group E was an age-matched control group given 0.9% NaCl injection. The experiment last 21 weeks. The Cu, ZnSOD activity of intestinal mucosa in group A animals began to increase significantly at the 7th week of the experiment. In groups B, C and D, however, this enzyme was not elevated statistically until the 16th week, and then each of these groups kept an increased Cu,ZnSOD level the rest of the experimental period. MnSOD activity was elevated statistically in group C animals at the 7th week. The enzyme activity in group A and D animals increased at the 9th week, but the enzyme activity did not increase statistically until the 11th week in group B. After the 16th week of the experiment the increased activity of MnSOD in all experimental groups returned to the level of the control group. Large intestinal cancer tissues had increased Cu,ZnSOD activity and decreased MnSOD activity.

Adenocarcinoma↗
PubMed1988

A simultaneous visualization of the antioxidant enzymes glutathione peroxidase and catalase on polyacrylamide gels.

A simple and sensitive method for the simultaneous visualization of glutathione peroxidase and catalase on polyacrylamide gels is described. The procedure included: (1) running samples on a 7.5% polyacrylamide gel, (2) soaking the gel in a certain concentration of reduced glutathione (0.25-2.0 mM), (3) soaking the gel in GSH plus H2O2 or cumene hydroperoxide, (4) finally staining with a 1% ferric chloride 1% potassium ferricyanide solution. The best concentration of glutathione for simultaneous visualization of glutathione peroxidase in mouse liver homogenates and also it is specific for glutathione peroxidase since other peroxidases such as lactoperoxidase, horseradish peroxidase and glutathione S-transferase cannot be visualized. Using this method, it was found that unlike catalase, glutathione peroxidase is heat resistant (68 degrees C, 1 min), but sensitive to 10 mM sodium iodoacetate.

Animals↗