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Biomedical subjects

Y Tian

Publications and source records attributed to Y Tian.

At least 109 records · Page 6Linked to original sources
PubMed1999

[Experiment and clinical application of targeting treatment with adriamycin magnetic albumin microspheres in human gastric carcinoma].

OBJECTIVE: To study the pharmacokinetics in experimental animals and observe the concurrent anticancer effects in human advanced gastric cancer as an adjuvant chemotherapy, when adriamycin magnetic albumin microspheres (ADM-MAM) were combined with external static magnetic fields. METHODS: The drug concentration of targeting tissues in the animals and the stability of ADM-MAM in human gastric juices were determined. Clinical and histopathological changes were observed in 55 cases of advanced gastric carcinomas after targeting treatment. RESULTS: The peak concentrations of the targeting tissue were highest after ADM-MAMs were administered for 2 hours and remained at the high level for a long time. ADM-MAM maintained its stability in human gastric juices. Targeting treatment improved the patients' symptoms, raised the rated of tumor resection, prolonged patients' lifetime, and enhanced histopathological effects (P < 0.01). CONCLUSIONS: The administration of ADM-MAM combined with the external static magnetic fields is effective for targeting location and is of clinical value as a preoperative adjuvant chemotherapy for human advanced gastric carcinoma.

Adolescent↗
PubMed1999

[Deletion analysis and functional studies of the promoter from commelina yellow mottle virus].

Commelina Yellow Mottle Virus(CoYMV) is a double-stranded, circular DNA virus and its promoter could direct GUS gene specifically expressing in phloem tissue of transgenic tobacco plants. To determine the optimal promoter sequence for pholem-specific gene expression, CoYMV promoter was deleted from its 5 end to form promoter fragments with 5 different lengths. Chimeric GUS genes were constructed using the promoter deletion based on the binary vector pBI121. Transgenic tobacco plants evidenced by PCR analysis were obtained with each kind of chimeric GUS gene structure by Agrobacterium mediated transformation. The results of GUS activity assay and histo-chemical staining showed that most of the chimeric GUS genes were expressed in transgenic plants. The GUS activity with the promoter deleted to -870 bp was about 78% higher than that of the full length promoter(1040 bp) and was a little higher than that of the promoter deleted to -585 bp, but the difference is not significant. The GUS activity reduced significantly when the promoter was deleted to -447 bp or -232 bp, whereas the property of phloem-specific expression pattern was still retained. When the promoter was deleted to -44 bp, just upstream adjacent to the TATA box, its tissue-specificity was lost and the activity was reduced to undetectable level. These results suggest that the region between -870 bp-232 bp and downstream of -232 bp of CoYMV promoter could be responsible for promoter activity and tissue specific expression, respectively. A negative regulation sequence might exist upstream of -870 bp of the CoYMV promoter. Therefore, we recommend that the optional CoYMV promoter sequence for phloem specific expression could be downstream from -870 bp or -585 bp. In comparison with CaMV 35S promoter, the GUS activity when driven by -870 bp CoYMV promoter was about 70% of that when driven by the 35S promoter. Considering the fact that 35S promoter-GUS gene is constitutively expressed, while the CoYMV promoter-GUS gene is expressed only in phloem tissues, the activity of the latter in phloem may be the same with or even higher than that of the 35S promoter.

Badnavirus↗
PubMed1999

[Effect of promoter-PTH4 on Streptomyces sporulation].

233 bp of promoter--PTH4 was subcloned into Streptomyces plasmid pIJ4083. pIJ4470 was obtained after recombinant plasmid was introduced into Streptomyces coelicolor J1501. Both Streptomyces coelicolor J1501/pIJ4083 and J1501/pIJ4470 were grown on minimal medium (MM) agar containing mannitol and 10 micrograms/mL thiostrepton for 6 days, and then ultrathin sections of colonies were prepared and stained with silver proteinate to observe glycogen biosynthesis in cell by the electron microscope. Result showed that the glycogen was produced by J1501/pIJ4083, whereas little glycogen was produced by J1501/pIJ4471. The dark color spores were not observed in J1501/pIJ4470 with lead stain in contrast with dark color spores which were produced by J1501/pIJ4083, indicating that promoter PTH4 may play an important role in physiological and morphological differentiation of Streptomyces.

Gene Expression Regulation, Bacterial↗
PubMed1999

[UV-Vis spectroscopic characterization of LB films of hydroxyl-substituted porphyrin derivatives].

The LB films forming properties of two hydroxyl-substituted porphyrins with double hexadecyl chains have been characterized. UV-Vis spectra show that the two porphyrins possess various aggregation behaviors in LB films. The porphyrin with symmetrically attached chains tend to form J-aggregate and the other asymmetric porphyrin can form hydrogen-bonded aggregate in LB films. The orientation of porphyrin rings was examined by polarized UV-Vis spectra. The results indicate that the situation of side-chain attached on porphyrin ring has no influence on porphyrin ring orientation, but has great influence on mean molecular areas or the distanses between porphyrin rings, and so as to affect the aggregation behaviors of porphyrin in LB films.

Molecular Structure↗
PubMed1999

[TXRF technique and quantitative analysis of mollusc teeth].

Total reflection X-ray fluorescence (TXRF) analysis technique and the instrument with a short path, high efficiency, low power and small volume are briefly presented. The detection limit of the system are at pg-level for Cu and Mo target excitation. Teeth of a marine mollusc were measured quantitatively and the spectrum and analysis results were given.

Animals↗
PubMed1998

Oxytocin is elevated in plasma of 10-day-old rats following gastric distension.

In adult rats, oxytocin (OT) has been shown to reduce the intake of both food and fluids, and oxytocinergic cells are activated by gastric distension and administration of the intestinal peptide cholecystokinin (CCK-8). These and other findings indicate that OT can play a role in inhibiting ingestion under some conditions. A previous study has shown, however, that oxytocinergic cells are unresponsive to CCK-8 in 2-day-old rats. We report here that OT is elevated in the plasma of 10-day-old rats after induction of gastric distension with both mother's milk and saline. These results indicate that the vagal-hypothalamic axis becomes mature between 2- and 10-days of age in infant rats.

Animals↗
PubMed1998

[Effects of taurine and extraction of cristata L on serum Zn, Cu and Ca in rats].

Forty rats fed with basic diets were randomly divided into 4 groups. NG group were fed with basic diets. The other three groups were fed with high fat diets. The rats in TA group and EC group were given TA 100 mg/kg or EC 100 mg/kg each day respectively in addition to high fat diet for 8 weeks. The results showed that taurine and extraction of cristata L not only increased the level of red cell SOD and the content of serum Zn (P < 0.05), but also decreased the contents of TC, MDA in the wall of artery and decreased the level of serum LDH significantly (P < 0.05 or P < 0.01). TA and EC increased significantly the content of serum Cu and decreased the ratio of serum Cu to Zn in the high fat diet rats (P < 0.01), and decreased the contents of serum Ca also. The results indicate that TA and EC may play some role in lipid metabolism and inhibit atherosclerosis by regulating the levels of Zn, Cu and Ca in rats.

Animals↗
PubMed1998

Separation and purification of 10-deacetylbaccatin III by high-speed counter-current chromatography.

High-speed counter-current chromatography (HSCCC) was used for the separation and purification of 10-deacetylbaccatin III from the needle extract of Chinese yew (Taxus chinensis). The crude needle extract (500 mg/5 ml) was first separated with a two-phase solvent system composed of n-hexane-ethyl acetate-ethanol-water (2:5:2:5, v/v) and the partially purified fraction was again purified with a different solvent system composed of n-hexane-chloroform-methanol-water (5:25:34:20, v/v). HPLC analysis of the final fraction showed that the purity of 10-deacetylbaccatin (20 mg) was over 98%. The chemical structure was confirmed by fast atom bombardment MS and 1H NMR.

Chromatography↗
PubMed1998

Increased CD40 ligand gene expression during human renal and murine islet allograft rejection.

BACKGROUND: The interaction between CD40 and its ligand CD40L is essential for the development and maintenance of vigorous immunity. We have sought to determine: (i) whether a heightened level of CD40L transcripts is evident during acute allograft rejection and (ii) the kinetics of CD40L gene expression during allograft rejection. METHODS: By using quantitative reverse transcriptase-assisted polymerase chain reaction techniques, we found that heightened CD40L gene expression is a correlate of acute human renal allograft rejection (P<0.01). RESULTS: In a murine model of MHC-mismatched islet allografts, our results showed that CD40L transcripts were rarely detected at day 2 after transplantation, but were remarkably heightened at day 5 after transplantation. The transcript levels then steadily increased and peaked at the time of rejection. CONCLUSION: These data suggest that therapy aimed at blocking the CD40 to CD40L interaction should be applied during the immediate posttransplant period.

Animals↗
PubMed1998

The Streptomyces coelicolor sporulation-specific sigma WhiG form of RNA polymerase transcribes a gene encoding a ProX-like protein that is dispensable for sporulation.

In the non-motile mycelial organism Streptomyces coelicolor A3(2), the sporulation gene whiG encodes a protein that closely resembles RNA polymerase sigma factors such as sigma D of Bacillus subtilis, which mainly control motility and chemotaxis genes. Here, we show that the whiG gene product, purified from an Escherichia coli strain carrying an expression construct, could activate E. coli core RNA polymerase in vitro to transcribe a sigma D-dependent motility-related promoter from B. subtilis. Such RNA polymerase holoenzyme preparations could also transcribe from an S. coelicolor promoter, PTH4, previously shown to require an intact whiG gene for in-vivo transcription. The in-vivo dependence on whiG was therefore shown to be direct. Unusually, the initiation of PTH4 transcription in vitro depended on the provision of appropriate dinucleotides. The whiG-dependent PTH4 transcription unit consisted of a single gene, orfTH4. Sequence comparisons suggested that the gene product was a member of a small group of proteins that include the B. subtilis and E. coli ProX proteins. Though none of these proteins shared more than about 30% of extended primary sequence identity, they had similar size and hydropathy profiles, and could be aligned end to end to reveal a mosaic of similarities. The ProX proteins of B. subtilis and E. coli are implicated in glycine betaine transport in response to hyperosmotic stress. However, disruption of orfTH4 did not cause any obvious phenotypic changes in growth or development on media of varying osmotic strengths.

Amino Acid Sequence↗
PubMed1998

Immunosuppression preventing concordant xenogeneic islet graft rejection is not sufficient to prevent recurrence of autoimmune diabetes in nonobese diabetic mice.

BACKGROUND: We and others have reported previously that the immunosuppressant, leflunomide (Lef), can prevent allogeneic and xenogeneic islet graft rejection in streptozocin (STZ)-induced diabetic animals. However, whether Lef required to prevent islet graft rejection is sufficient to prevent the recurrence of autoimmune diabetes has not been addressed. METHODS: The effect of Lef on concordant xenogeneic islet graft in STZ-induced diabetic mice and autoimmune nonobese diabetic (NOD) mice were studied. Then, whether Lef prevents the onset of spontaneous diabetes in young NOD mice and the recurrence of diabetes after major histocompatibility complex (MHC)-matched islet transplantation in diabetic NOD mice were investigated. RESULTS: In STZ-induced diabetic BALB/c mice, Lef treatment significantly prolonged rat islet graft survival. However, Lef could not significantly prolong rat islet graft survival in autoimmune diabetic NOD mice. For prevention studies, treatment with Lef at 30 mg/ kg/day from 4 weeks to 20 weeks of age significantly reduced the incidence of spontaneous diabetes in NOD mice. However, when the NOD mice were treated from 8 to 24 weeks of age, the incidence of spontaneous diabetes was not significantly reduced as compared to the incidence of diabetes in the untreated female NOD mice at 28 weeks of age. Finally, in the MHC-matched islet transplant model, Lef could not significantly prolong MHC-matched nonobese diabetes-resistant mice islet graft survival in NOD mice. CONCLUSIONS: Lef preventing concordant xenogeneic islet graft rejection is not sufficient to prevent the recurrence of autoimmune diabetes in NOD mice. We believe that controlling autoimmunity after islet transplantation will lead the way to promote successful clinical islet transplantation in the future.

Animals↗
PubMed1998

Regulation of estrogen receptor mRNA by 2,3,7,8-tetrachlorodibenzo-p-dioxin as measured by competitive RT-PCR.

Environmental contaminants, such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), cause alterations in gene expression. In this study, we measured the regulation of estrogen receptor (ER) mRNA in female CD-1 mice by competitive RT-PCR. Previous work suggests that ER protein levels are affected by TCDD, but how this is regulated is uncertain. These studies found no significant changes in ER mRNA levels, but the methods used (Northern blot analysis and RNase protection assays) lack sensitivity for measuring the low levels of RNA transcript, such as ER mRNA. The method described here offers an excellent alternative for quantifying the changes in mRNA levels. Internal competitors were created with gene-specific primers for ER and beta-actin by PCR reactions at low annealing temperatures. For each sample, the mRNA levels of ER and beta-actin were determined. Using competitive RT-PCR, the relative changes in ER mRNA from TCDD-treated and control animals were determined after normalization with the levels of beta-actin mRNA. The ER mRNA from female CD-1 mice treated with TCDD (single dose 5 micrograms/kg, i.p., 4 days) was found to be significantly suppressed as compared with the vehicle control in all tissues examined. TCDD decreased ER mRNA in the liver (30.1%) as expected. However, the greatest effect was in the reproductive tissues, with a 64.2% reduction in ER mRNA in the ovary. This is the first demonstration that TCDD causes tissue-specific downregulation of ER mRNA. These effects may contribute to the tissue-specific toxicity of TCDD.

Animals↗
PubMed1998

Bacterial expression and characterization of human recombinant apolipoprotein(a) kringle IV type 9.

Elevated plasma lipoprotein(a) [Lp(a)] is an independent risk factor for several vascular diseases. Lp(a) particles are generated through the formation of a disulfide bond between Cys4057 of kringle IV type 9, (KIVt9), of the multikringle apolipoprotein(a) [apo(a)] and a cysteine in apoB-100 low-density lipoprotein (LDL). To better understand this interaction, we have expressed and purified KIVt9 from Escherichia coli as a His-Tag fusionprotein. Dithiothreitol (DTT)-treated purified KIVt9 migrated as a single approximately 17. 3-kDa band on SDS-PAGE gels. Without DTT, an additional band twice the molecular weight of KIVt9 was observed. The double-size band presumably resulted from dimerization of individual kringles, through their unpaired cysteine residues, since a mutation Cys4057 --> Ser ([Ser4057]KIVt9) abolished dimer formation. Using a gel-shift assay, we showed that KIVt9 could couple to 14-amino-acid apoB-100 synthetic peptides (apoB3732-3745 and apoB4319-4332) containing Cys3734 or Cys4326. Both of these apoB-100 cysteines have been reported to associate with apo(a) to generate Lp(a). In the presence of either apoB-100 peptide, KIVt9 was shifted to a higher molecular weight that was consistent with the covalent addition of a 1.2-kDa apoB-100 peptide. Identical apoB-100 peptides in which the cysteine residues were replaced by alanine ([Ala3734]apoB3732-3745 and [Ala4326]apoB4319-4332) had no effect in the gel-shift assay. Furthermore, [Ser4057]KIVt9 did not covalently interact with apoB3732-3745 or apoB4319-4332. These results indicated that KIVt9 couples to the Cys-apoB-100 peptides through a disulfide linkage. This system may be suitable for further investigating the apo(a)/apoB-100 coupling reaction and the structure of KIVt9 through X-ray crystallographic studies.

Apolipoprotein B-100↗
PubMed1998

Inflammatory mediators in adults undergoing cardiopulmonary bypass: comparison of centrifugal and roller pumps.

BACKGROUND: The nonocclusive centrifugal pump is used for cardiopulmonary bypass (CPB) and mechanical cardiac assistance. This study examined its impact on proinflammatory cytokine release. METHODS: Forty-one patients undergoing elective coronary artery bypass grafting were randomized prospectively to either a standard roller pump group (n = 21) or a centrifugal vortex pump group (n = 20) for CPB. The two groups were well matched in age, sex, severity of disease, and duration of CPB and aortic cross-clamping. Plasma levels of the cytokines tumor necrosis factor-alpha, interleukin-1beta, interleukin-6, and interleukin-8, as well as terminal complement, neutrophil counts, and leukocyte elastase, were analyzed before, during, and after CPB. RESULTS: In both groups, traces of tumor necrosis factor-alpha were observed infrequently and interleukin-1beta was not detected. Plasma levels of interleukin-6 and interleukin-8 increased during and after CPB, reaching a peak at 2 hours after protamine administration in both groups before returning toward baseline at 24 hours. The release of interleukin-6 was significantly greater in the centrifugal group (p < 0.05), whereas the interleukin-8 concentration did not differ between the groups throughout the study period. Levels of terminal complement increased in both groups perioperatively, reaching a peak 30 minutes after protamine administration, whereas neutrophil counts and elastase peaked 2 hours after protamine administration. Plasma terminal complement, neutrophil counts, and elastase release were significantly higher in the centrifugal group (p < 0.05). Peak terminal complement correlated (r = 0.64, p < 0.01) with peak elastase in the centrifugal group only. CONCLUSIONS: This study confirms the proinflammatory nature of CPB in adults and demonstrates that use of the centrifugal pump induces a greater systemic inflammatory response than use of the standard roller pump.

Adult↗
PubMed1998

Stimulation of endothelial cell production of vasoconstrictive substances by hypertensive sera.

The endothelial cell regulates vessel tone by elaborating a number of vasoactive substances such as thromboxane and endothelin, both of which are highly vaosconstrictive, and prostacyclin and nitric oxide, both of which are vasodilatory. The current study examines the postulate that one of the mechanisms responsible for the increased vessel tone found in hypertension is the presence of substances in the sera of patients with this disorder that stimulates selectively the endothelial cell production of thromboxane and endothelin. Sera from ten patients with mild hypertension and from 11 age-matched controls were incubated with human umbilical arterial endothelial cells and the concentrations of endothelin, thromboxane, prostacyclin, and nitric oxide produced by the cells was measured in the supernatant. The results of the assays showed that the amounts of thromboxane and endothelin produced by endothelial cells in response to stimulation by hypertensive sera were significantly higher than the amounts produced in response to control sera; in comparison, the amounts of prostacyclin and nitric oxide produced by the cells in response to either hypertensive sera or control sera were not significantly different. The findings suggest that a mechanism that may be responsible for the increased vascular tone found in hypertension is the presence of substances in hypertensive sera that stimulate endothelial cells selectively to produce increased amounts of the vasoconstrictive hormones, endothelin and thromboxane.

6-Ketoprostaglandin F1 alpha↗