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Biomedical subjects

Y Xu

Publications and source records attributed to Y Xu.

At least 829 records · Page 46Linked to original sources
PubMed1997

[Dynamic analysis of 24 h blood pressure in pilots and hypertensive patients].

Blood pressure of 63 healthy male pilots and 20 primary hypertensive patients was measured with the "Smart LINK Ambulatory Monitoring System". The BP readings were taken every 30 min in daytime and 60 min at night for 24 h. The results showed that two peaks appeared at 7:00-9:00 A.M. and 16:00-19:00 P.M. and two valleys at 12:00-14:00 P.M. and 24:00-5:00 A.M. in healthy pilots, but the hypertensive subjects showed higher systolic or/and diastolic blood pressure continuously.

Aerospace Medicine↗
PubMed1997

[The effects of gossypol on rat luteal cells, human decidual cells and cytotrophoblasts].

The direct effects of gossypol on the serum-free primary cultures of rat luteal cells and cytotrophoblasts were observed. The results indicate that: (1) Gossypol affected the viability of the cultured rat luteal cells, LD50: 1.6 (0.4-2.9) micrograms.ml-1. (2) The basal secretions of progesterone were significantly inhibited at low and high concentrations. The activities of 3 beta-HSD, adenyl cyclase and hCG-stimulated progesterone production were inhibited by higher concentrations of gossypol. (3) Gossypol damaged cultured human decidual cells and cytotrophoblasts, the LD50 were 3.5(0.4-6.6) micrograms.ml-1 and 4.1(0.6-7.6) micrograms.ml-1, respectively. These results suggest that the luteolytic effect is the main mechanism of action for the termination of early pregnancy by gossypol, while the direct damaging effects on decidual cells and cytotrophoblasts may also play a role in the termination of early pregnancy.

Animals↗
PubMed1997

[High performance liquid chromatographic method for the determination of ipriflavone in serum and its pharmacokinetic study in healthy volunteers].

A sensitive and rapid high performance liquid chromatographic method has been developed for the determination of ipriflavone in human serum. The average recovery of ipriflavone was 85% with relative standard deviation of 3.8%-5.4%. The calibration curve was linear in the range from 8 ng.ml-1 to 400 ng.ml-1 with gamma = 0.9981. The detection limit of the method was 3 ng.ml-1 (S/N > or = 3). The serum drug concentration-time curve exhibited a 2-compartment model and the mean T1/2 beta was 12.00 +/- 1.89 h (for ipriflavone made in Japan) and 9.05 +/- 0.80 h (for ipriflavone made in China). The AUC0-->infinity of the two kinds of ipriflavone were 804.99 ng.h.ml-1 and 807.40 ng.h.ml-1, respectively. The relative bioavailability of ipriflavone made in China vs that made in Japan was 1.003.

Adult↗
PubMed1997

[Accumulative trends of ephedrine and pesudoephedrine in Ephedra sinica].

In Yi Kezhao Alliance, the content of ephedrine and pseudoephedrine in Ephedra sinica is in a ratio of four to six. The total content of ephedine and pseudoephedrine form cultivated Ephedra sinica is higher than that of wild one, and in direct ratio with the years of plant. For the content enhance of total alkaloids, decreasing irrigation and applying middlingly fertilizer is more effective measure.

Alkaloids↗
PubMed1997

[Coxsackievirus B3-induction of tumor necrosis factor and IL-6 of murine monocyte-macrophages].

This study is to observe the infection of coxsackievirus B3 (Cox B3) to murine monocyte-macrophages (Mo/Mpsi), and its induction of tumor necrosis factor (TNF) and IL-6. Cox B3 was capable of infecting murine macrophages as revealed by immunofluorescence and releasing infectious virus particles. Virus infection with < or = 100 TCID50 did not reduce macrophages viability. Cox B3 stimulated the release of monokines from Mo/Mpsi in vitro and in vivo, markedly increasing the concentration of TNF and IL-6. These were found in the plasma and homogenized heart tissue during the acute phase of murine myocarditis induced by Cox B3, and in the culture supernatant of Mo/Mpsi infected by Cox B3.

Animals↗
PubMed1997

[Quantitative study of calcitonin gene methylation in myelodysplastic syndromes].

OBJECTIVE: To investigate the role of calcitonin gene hypermethylation in the transformation from myelodysplastic syndromes (MDS) to acute myeloid leukemias (AML). METHODS: The methylation rate of calcitonin gene (CTMR) in the genomic DNA extracted from bone marrow cell of 27 MDS patients and 6 AML patients with antecedent MDS were studied by PCR amplification of Hpa I digested DNA, with external reference of undigested and Msp I digested DNA and internal reference of 112bp fragment containing N-ras-61. Intensity of silver-stained PCR products was measured by densitometer and analysed using the computer program. RESULTS: The CTMR was significantly higher in MDS (33.65% +/- 23.37%) than in control group (P<0.001), in 9 RAEB(T) (58.35% +/- 17.44%) than in the control and RA groups. Five RA patients who have survived three to ten years without leukemia, have a normal CTMR. Seven of 8 RAEB(T) patients who had a high CTMR of more than 30% evolved into AML in two months. CONCLUSION: CTMR might be a useful marker for predicting the evolution of MDS into AML.

Adolescent↗
PubMed1997

[Comparative study of two fusion retinoic acid receptor alpha in acute promyelocytic leukemia].

OBJECTIVE: To make a comparison of biological properties between PML-RARalpha and PLZF-RARalpha fusion proteins. METHODS: Receptor radioligand binding assay, receptor DNA binding assay and immunofluorescence methods were used. RESULTS AND CONCLUSION: PML-RARalpha and PLZF-RARalpha had similar ligand-binding affinities. Both could bind in vitro to retinoic acid response elements (RAREs) forming homodimers and to retinoic acid X receptor. However ,they differed in the relative binding affinities to different RAREs,the behavior of forming complex with RXR and the subcellular localization. More importantly, PML-RARalpha and PLZF-RARalpha could block different regulatory pathways mediated by PML or PLZF, through heterocomplex formation with wild-type PML or PLZF. The differences between PML-RARalpha and PLZF-RARalpha may in part explain the apparent resistance of APL with t(11;17) to differentiating effect of all-trans retinoic acid (ATRA).

DNA↗
PubMed1997

[Effects of cytokines on multidrug-resistance in K562/A02 cells].

OBJECTIVE: To explore the effects of cytokines on human leukemic cell line K562/S and its multidrug-resistant counterpart K562/A02. METHODS: The toxicities of cytokines and the IC50 (the concentration causing 50% inhibition of cell growth) of DNR were assayed by MTT method; intracellular drug concentration was measured by fluorometry; p-glycoprotein (p-gp) expression was detected by APAAP and mdr-1 mRNA was assayed by RT-PCR. RESULTS: The IC50 of DNR for K562/A02 and K562/S cells were 45.08 microg/ml and 0.607 microg/ml, respectively. Pretreating K562/A02 cells with rhu IFN (500 U/ml) or rhu IL-2 (250 U/ml) for 24 hours partially restored the sensitivity of K562/A02 cells to DNR (IC50 were 16.39 and 11.96 microg/ml, respectively) but had not effect on K562/S cells, and it elevated the intracellular DNR accumulation in K562/A02 from 2151 ng/mg x protein to 2570 and 2503ng/mg x protein, respectively. p-gp and mdr-1 mRNA were not down regulated. By contrast, rhu G-CSF and rhu GM-CSF had no effect on either K562/A02 or K562/S. CONCLUSION: rhu IFN or rhu IL-2 could partially restore the sensitivity of K562/A02 to DNR and elevate the intracellular DNR accumulation via a mechanism independent of p-gp or mdr-1 mRNA down-regulation.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1997

[Effects of antisense oligodeoxynucleotides targeting multidrug resistance gene on resistant cell line K562/ AO2].

OBJECTIVE: To investigate the reversal effect of antisense oligodeoxynucleotide on human multidrug-resistant leukemic cell line K562/AO2. METHODS: Antisense oligodeoxynucleotides (AOD) targeting-6 approximately 9 sites of exon 2 in human multidrug resistance gene(mdr-1), one of which is sequence-strict-complied and linked with polyethyleneglycol (PEG) at 5' end (AP, 15 mer), the other lacks nucleotide complied site-1 (AP', 14mer), were synthesized. AP, AP' and verapamil were simultaneously added to human mdr-1-mRNA positive leukemia cell line K562/AO2 and, mdr-1-mRNA and p170 were detected. AS' and AP'were labelled by FITC and designated as ASF' and APF', respectively. In addition, the intracellular concentration of them was detected by FACS. RESULTS: AP' significantly enhanced the sensitivity of K562/AO2 to DOX, down-regulated the expression of mdr-1 and MRP-mRNA and p170, elevated the intracellular concentration of the two AOD, while AP had no effect. The uptake of APF' was significantly higher than that of ASF' in K562/AO2, and the fluorescence was observed in the plasma and nuclear of K562/AO2 cells. CONCLUSION: (AOD targeting mdr-1 promoted the drug sensitivity of drug-resistant tumor cells. 2 AOD had no cytotoxicity to tumor cells. 5 Low molecule PEG enhanced significantly the uptake of AOD by tumor cells.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1997

[Study on the interaction of metal ion in active center of superoxide dismutase with cobalt chloride by visible spectroscopy].

The direct interaction of metal ion in active center of copper-zinc superoxide dismutase (Cu2Zn2SOD) with inorganic cobalt chloride (CoCl2) in buffer has been first studied by visible spectroscopy. The effects of increasing amounts of CoCl2, changing pH,different acid salt and equilibrium time on the interaction have been discussed. It was found that the Co(II) of CoCl2 makes an exchanging interaction with Zn(II) in Cu2Zn2SOD and thus the partial Cu2Co2SOD is formed.

Buffers↗
PubMed1997

[Molfig, a software for displaying the structure and vibration of molecule].

A Molfig software has been developed for displaying the structure and vibrational mode of molecule in our lab. Various functions and a friendly interface are equipped in the software. The testing results showed that the software may enhance our understanding of the relationship between the vibrational behavior and the structure of molecules.

English Abstract↗
PubMed1997

[Curvefit, an overlapping bands resolving software for IR spectra].

A Curvefit software has been developed for resolving the overlapping band of the vibartional spectra in our lab . Various functions and a friendly interface are equipped in the software. The testing results showed that both the speed of the calculation and the reliability of the final results are satisfactory.

English Abstract↗
PubMed1997

The plasma concentrations of lidocaine after slow versus rapid administration of an initial dose of epidural anesthesia.

We measured venous blood concentrations of lidocaine in 15 patients undergoing lower abdominal or extremity surgery after epidural injection of lidocaine. Patients were divided into either an infusion group (Group I, n = 6) or a bolus injection group (Group II, n = 9). We administered 15 ml of 2% lidocaine into the epidural space at 1 mL/min in Group I and at 1 mL/3 in Group II. Venous blood was drawn at 3, 6, 9, 12, 15, 18, 21, 30, 60, and 90 min after injection for measurement of plasma lidocaine concentrations. The peak plasma concentration (Cmax) of lidocaine in Group I was significantly less than that in Group II (P < 0.0005). We conclude that slow epidural infusion can produce a lower Cmax of lidocaine compared with that of a bolus administration and thereby decrease the potential for systemic toxicity of the local anesthetic.

Anesthesia, Epidural↗
PubMed1997

Transurethral bladder tumor resection alters fibronectin expression in transitional carcinoma cell lines.

PURPOSE: To examine the effect of TGF beta 1 and post-transurethral resection of bladder tumor (TURBT) urine on fibronectin (FN) expression by transitional carcinoma (TCC) cell lines. MATERIALS AND METHODS: Northern analysis and rtPCR for mRNA transcripts, in combination with ELISA and immunohistochemistry for protein, were used to quantify the effect of TGF beta 1 and post-TURBT urine on cellular expression of FN in two TCC lines, 253J and 647V. The TGF beta 1-dependent nature of the response seen in post-TURBT urine was confirmed using exogenous TGF beta 1 or blocking antibodies to TGF beta 1. Active and latent levels of TGFb1 were measured in post-TURBT urine and urine "spiked" cell culture media. RESULTS: Baseline FN expression was low in the poorly differentiated, metastatic 253J line and high in the moderately differentiated 647V line. TGF beta 1 and post-TURBT urine increased FN expression at both the mRNA and protein levels in the 253J line. Anti-TGF beta 1 antibodies inhibited the effect of post-TURBT urine on FN expression in 253J cells. High levels of TGF beta 1 decreased FN expression in 647V cells. Only latent TGF beta 1 was present in samples of urine and media. CONCLUSIONS: FN production in low expressing TCC lines can be augmented by exogenous TGF beta 1. TURBT increases latent urinary TGF beta 1 which in turn affects TCC FN expression. Altered tumor expression of FN following TURBT may influence the effectiveness of intravesical BCG.

Carcinoma, Transitional Cell↗
PubMed1997

Down-regulation of apurinic/apyrimidinic endonuclease expression is associated with the induction of apoptosis in differentiating myeloid leukemia cells.

The human DNA repair enzyme apurinic/apyrimidinic endonuclease (APE/ref-1) is a multifunctional protein in the DNA base excision repair (BER) pathway that is responsible for repair of apurinic/apyrimidinic (AP) sites in DNA. DNA repair and programmed cell death both function using different mechanisms to protect the organism from the consequences of extensive cellular damage; however, little is known about the relationship of the DNA BER repair pathway to apoptosis. We have determined the relationship of a BER DNA repair enzyme, APE, to apoptosis using the myeloid leukemia cell line HL-60, which can be induced to differentiate down the granulocytic or monocytic/ macrophage pathway. Treatment of HL-60 cells with retinoic acid/DMSO (granulocytic) or phorbol 12-myristate 13-acetate (monocytic) results in apoptosis and in down-regulation of APE expression at both the RNA and protein levels. Moreover, double-labeling experiments using APE immunohistochemistry and the terminal deoxyribonucleotidyl transferase-mediated dUTP-fluorescein nick end labeling assay for apoptosis demonstrate that individual cells undergoing apoptosis lose expression of APE regardless of their state of differentiation. Blocking apoptosis by overexpression of the bcl-2 proto-oncogene in HL-60 cells or by a bcr-abl-related mechanism in K562 cells and subsequent differentiation results in morphological differentiation but no loss of APE expression. These studies establish that down-regulation of APE expression is associated with programmed cell death in cells of the myeloid lineage.

Apoptosis↗
PubMed1997

NMR studies on the flexibility of nucleoside diphosphate kinase.

Human NDP kinase B, product of the nm23-H2 gene, binds DNA. It has been suggested that a helix hairpin on the protein surface, part of the nucleotide substrate binding site, could accommodate DNA binding by swinging away. The presence of flexible regions was therefore investigated by 1H NMR dynamic filtering. Although TOCSY peaks could be assigned to five residues at the N terminus of Dictyostelium NDP kinase, no flexible region was detected in the human enzyme. These data favor the idea that the protein offers different binding sites to mono- and polynucleotides.

Amino Acid Sequence↗