Biomedical subjects

Yan Li

Publications and source records attributed to Yan Li.

At least 721 records · Page 40Linked to original sources

PubMed2002

[Studies on antitumor activity of rhEndostatin].

AIM: To investigate the inhibitory effect of recombinant human endostatin (rhEndostatin) on endothelia cell proliferation and tumor growth. METHODS: MTT assay was applied to examine the anti-proliferation of rhEndostatin on human embryo umbilical cord vascular endothelial cell ECV304 and human cancer cell HCT-8, BGC803 and EJ. Xenotrasplanted nude mice models with human cancer and experimental implanted tumor mice model were used to evaluate rhEndostatin's antitumor activity. RESULTS: rhEndostatin was shown to inhibit the proliferation of ECV304 cells and the IC50 is about 7 x 10(-6) g.L-1. No inhibition was observed in HCT-8, BGC803 and EJ cells at 1 x 10(-4) g.L-1 rhEndostatin. rhEndostatin was shown to inhibit human xenograft in nude mice with human gastric cancer BGC803 and breast cancer B37 when administered subcutaneously at 5, 10, 20 mg.kg-1.d-1 for 24 days in a dose-dependent manner. Mouse hepatoma H22 was also suppressed when given rhEndostatin subcutaneously 20 mg.kg-1.d-1 for 9 days, but it showed no inhibitory effect on Lewis lung carcinoma and B16 melanoma. CONCLUSION: These results indicate that rhEndostatin can inhibit the growth of xenotransplanted human tumors in nude mice and certain murine tumor. The action mechanisms may be that it can inhibit endothelial cell proliferation, thereby inhibiting the formation of new blood vessel in tumor, leading the tumor to stop grow.

Animals↗

PubMed2002

[The protective effect of bicyclol on ischemia-reperfusion induced kidney injury in rats].

AIM: To investigate the protective effect of bicyclol on kidney injury induced by ischemia-reperfusion in rats. METHODS: Bicyclol was orally administered to rats at doses of 50 and 200 mg.kg-1 before ischemia-reperfusion injury to evaluate the influence of bicyclol on the formation of MDA and BUN in serum, the content of GSH and the activity of GST in kidney, as well as kidney mitochondria membrane fluidity in ischaemia-reperfusion rats. RESULTS: Bicyclol given orally at doses of 50 and 200 mg.kg-1 was shown to significantly decrease the increment of MDA and BUN in serum and protect the GSH depletion in kidney. Bicyclol was also shown to induce kidney GST and ameliorate the decrease of mitochondria membrane fluidity. The protective effects of bicyclol on kidney injury induced by ischemia-reperfusion are dose-dependent. CONCLUSION: The protective action of bicyclol on kidney injury induced by ischemia-reperfusion may be attributed to its induction of kidney GSH and the GST, stabilization on mitochondria membrane and the inhibition on lipid peroxidation.

Animals↗

PubMed2002

[Microscopy identification of Phyllanthus simplex].

OBJECTIVE: To identify Phyllanthus simplex. METHODS: Morphological and histological identification. RESULTS: There are cluster crystals in cortex and mesophyll of the root and the stem from Phyllanthus simplex. Paracytic type stomata are visible. CONCLUSION: Above-mentioned characters can be used for the identification of Phyllanthus simplex.

Pharmacognosy↗

PubMed2002

[Transfection of the exogenous PTEN-induced growth inhibition of the highly metastatic mucoepidermoid carcinoma cell line M3SP2 in vitro].

OBJECTIVE: The purpose of this study was to evaluate the effects of the exogenous phosphatase and tensin homology deleted on chromosome 10 (PTEN) gene on in vitro growth of the highly metastatic mucoepidemoid carcinoma cell line M3SP2. METHODS: The growth of the exogenous PTEN transfected mucoepidemoid carcinoma cells M3SP2-PTEN gene was studied by analyzing cell growth curves, mitosis index and clone formation efficiency and compared with its parental cell line M3SP2 and the vector pBabepuro-transfected cell line M3SP2-pBp. RESULTS: The doubling time (h) of M3SP2, M3SP2-pBp and M3SP2-PTEN were 24.50, 24.76 and 31.74; the mitosis index (@1000) were 53.0 +/- 6.20, 49.0 +/- 5.24 and 16.2 +/- 3.2; the clone formation efficiency (%) were 37.37, 35.01 and 10.40, respectively. The M3SP2-PTEN cells also revealed 57.05%-71.46% inhibition of growth from day 3 to 7 and 65%-72% inhibition of clone formation compared with the parental cells. CONCLUSION: These data provide evidence that the exogenous wild-type PTEN have remarkably inhibitory effects on in vitro proliferation of the highly metastatic mucoepidermoid carcinoma cell line M3SP2.

Carcinoma, Mucoepidermoid↗

PubMed2002

A novel erythroid differentiation related gene EDRF1 upregulating globin gene expression in HEL cells.

OBJECTIVE: To further characterize the differentiation inducing properties of EDRF1 and demonstrate its functional pathway involved in regulation of globin gene expression. METHODS: By transfecting EDRF1 sense and antisense constructs into HEL cells, we identified the expression of globin and erythropoietin receptor genes by Northern blot analysis. RT-PCR and EMSA (electrophoresis mobility shift assay) were performed to monitor the expression and DNA-binding activity of erythroid specific transcription factors GATA-1 and NF-E2. RESULTS: It was shown that when EDRF1 was overexpressed, production of alpha-globin increased. In antisense EDRF1, overexpression of HEL cells, significant loss of alpha-, gamma-globin mRNA synthesis was observed. The transcription of endogenous GATA-1 and NF-E2 mRNA expression were maintained at the same levels compared with control experiments. However, the transcription activity of GATA-1 was severely impaired. Expression of erythropoietin receptor gene was not influenced by EDRF1 gene overexpression. CONCLUSION: The results suggested that EDRF1 regulated alpha- and gamma-globin gene synthesis by modulating DNA-binding activity of GATA-1 transcription factor.

Cell Differentiation↗

PubMed2002

[Comparison of machinability of two types of dental machinable ceramic].

OBJECTIVE: In terms of the problems of now available dental machinable ceramics, a new type of calcium-mica glass-ceramic, PMC-I ceramic, was developed, and its machinability was compared with that of Vita MKII quantitatively. Moreover, the relationship between the strength and the machinability of PMC-I ceramic was studied. METHODS: Samples of PMC-I ceramic were divided into four groups according to their nucleation procedures. 600-seconds drilling tests were conducted with high-speed steel tools (Phi = 2.3 mm) to measure the drilling depths of Vita MKII ceramic and PMC-I ceramic, while constant drilling speed of 600 rpm and constant axial load of 39.2 N were used. And the 3-point bending strength of the four groups of PMC-I ceramic were recorded. RESULTS: Drilling depth of Vita MKII was 0.71 mm, while the depths of the four groups of PMC-I ceramic were 0.88 mm, 1.40 mm, 0.40 mm and 0.90 mm, respectively. Group B of PMC-I ceramic showed the largest depth of 1.40 mm and was statistically different from other groups and Vita MKII. And the strength of the four groups of PMC-I ceramic were 137.7, 210.2, 118.0 and 106.0 MPa, respectively. CONCLUSION: The machinability of the new developed dental machinable ceramic of PMC-I could meet the need of the clinic.

Dental Porcelain↗

PubMed2002

[Gene expression profile of human hepatocellular carcinoma cell lines with different metastatic potentials].

OBJECTIVE: To compare gene expression profile of human hepatocellular carcinoma (HCC) cell lines with different metastatic potentials, so as to screen for metastasis-related genes. METHODS: Gene expression profile of MHCC97-L and HCCLM3, two HCC cell lines with similar genetic background but different in spontaneous metastatic potentials, were studied by cDNA microarray. RESULTS: From 1,626 screened genes, 25 differentially expressed genes were found, 18 showed decreased expression including the decreased expression of cell cycle control genes Rb2, mismatch repair gene hMSH2, and signal transduction gene protein kinase C beta 2 and 7 increased expression including signal transduction gene MAP kinase kinase 6, cell proliferation gene E25, immunity related gene SP40, 40, etc in HCCLM3. CONCLUSION: The genes, being closely associated with cancer metastasis, could be considered as potential markers to predict metastasis and targets for anti-metastasis intervention.

Blotting, Northern↗

PubMed2002

[The early pathological changes of KKAy mice with type 2 diabetes].

OBJECTIVE: To investigate the early pathological changes of KKAy mouse model of type 2 diabetes. METHODS: Five male KKAy mice and six C57BL mice each were studied at the age of 8, 16, 20 and 24 weeks. With each mouse a 24-hour urine collection was made for the tests of proteinuria. Plasma insulin, lipids, serum creatinine and urea were also measured. Renal tissues were observed to assess glomerular and tubulointerstial pathology. RESULTS: The KKAy mice developed hyperglycemia, hyperinsulinemia and obesity by 16 weeks of age (P < 0.01). The proteinuria increased with the increasing of age (P < 0.005), but there were no changes in control. The glomerular hypertrophy was observed in KKAy mice at the age of 16 weeks. Computer map analysis system (CMIAS) indicated the expansion of mesangial matrix in KKAy mice with ageing. There was significant tubular dilation, accompanied with focal tubular atrophy and interstitial fibrosis. On electron microscopy, GBM undergo progressive thickening (P < 0.01), accompanied with podocytes fusion and increasing of proteinuria. CONCLUSIONS: KKAy mice developed hyperglycemia, hyperinsulinemia and obesity after 16 weeks, with proteinuria, mesangial matrix accumulation, GBM thickening and tubular dilation. It was considered a good animal model for the early pathology changes of DN.

Animals↗

PubMed2002

[Reconstruction algorithms of computed tomography of remote sensing FTIR].

Reconstruction algorithms of computed tomography-remote sensing fourier transform infrared spectroscopy plays a key role in fast and cost-effective acquirement of gas concentration distribution. Ideally, a reconstruction algorithm can be used to obtain good reconstruction maps only by limited number of measurements and non-symmetric ray configurations, even in the presence of instrument noise, measurement error, poor beam geometry, and variations in the contaminant spatial distribution. Several conventional reconstruction algorithms used to reconstruct two-dimensional concentration maps of the vapor contaminants by remote sensing FTIR, such as ART, MART, SIRT and SBFM, have been reviewed in this paper. Comparing to ART, MART has the advantages of iterative speed and iterative precision, while SIRT overcomes the problem of illegibility and SBFM can reduce the noise sharply.

Air Pollutants↗

PubMed2002

[Calibration of EQUINOX55 remote sensing FTIR emission system].

In order to obtain the infrared spectral radiance distribution of the emission spectrum or the concentration of the gases, the calibration of FTIR emission system is necessary for obtaining an instrument response function of the system. This paper gives the effect of the temperature of the standard blackbody for calibration of EQUINOX55 remote sensing FTIR emission system on the instrument response function. The result illustrates that the values of the instrument response functions increase as the blackbody temperature increased, and tends to a limit.

Calibration↗

PubMed2002

[Determination of Zn, Cu, Mg and Mn in hair of cerebral infarction by AAS].

In order to study the relation between the contents of Zn, Cu, Mg and Mn in hair of 45 patients with cerebral infarction and 20 health people were determined by atomic absorption spectrometry (AAS). The results showed that the contents of Zn, Cu and Mg in the patients' hair (79.785 +/- 25.514, 8.241 +/- 1.405 and 24.831 +/- 9.986 respectively) were lower than that of the health people (168.031 +/- 29.467, 18.612 +/- 2.051 and 93.006 +/- 47.548 respectively) (p < 0.01), but the content of Mn of the patients (3.652 +/- 1.001) was higher than that of health people (1.751 +/- 0.597) (p < 0.01). These indicated that there must be some relation between the contents of Zn, Cu, Mg and Mn and the cerebral infarction. The lack of Zn, Cu and Mg as also as high level content of Mn subscribed to the formation of cerebral vascular deformation and sclerosis.

Aged↗

PubMed2002

[Spectroscopic determination of the dynamic electrical spark temperature of nonel tube igniter].

A set of transient real time two-line spectroscopy temperature measured system with quartz optical fiber was established. Two spectral lines are Cu I 510.5 and Cu I 521.8 nm respectively. Its maximum time resolution is up to 0.1 microsecond. The discharge spark temperature and spark discharge time of the nonel tube igniter under different voltage are 2,100-4,200 and 100-200 microseconds respectively. The spark discharge time increase with the rising of charge voltage. The discharge spark temperature variations versus the discharge time under different voltages, and the spark duration under different discharge conditions were studied with this instrument.

English Abstract↗

PubMed2002

[Comparison of four multivariate calibration methods in simultaneous determination of air toxic organic compounds with FTIR spectroscopy].

The concentration determination abilities of four multivariate calibration methods--classical least squares (CLS), partial least squares (PLS), kalman filter method (KFM) and artificial neural network (ANN) were compared in this paper. Five air toxic organic compounds--1,3-butadiene, benzene, o-xylen, chlorobenzene, and acrolein--whose FTIR spectra seriously overlap each other were selected to compose the analytical objects. The evaluation criterion was according to the mean prediction error (MPE) and mean relative error (MRE). Results showed that PLS was superior to other methods when treating multicomponent analysis problem, while there was no comparable difference between CLS, KFM and ANN.

Acrolein↗

PubMed2002

[Combustion temperature measurement of pyrotechnic composition using remote sensing Fourier transform infrared spectrometry].

In this paper, combustion characterization of pyrotechnic composition is investigated using a remote sensing Fourier transform infrared spectrometry. The emission spectra have been recorded between 4,700 and 740 cm-1 with a spectral resolution of 4 cm-1. The combustion temperature can be determined remotely from spectral line intensity distribution of the fine structure of the emission fundamental band of gaseous products such as HF. The relationship between combustion temperature and combustion time has been given. Results show that there is a violent mutative temperature field with bigger temperature gradient near combustion surface. It reveals that the method of temperature measurement using remote sensing FTIR for flame temperature of unstable, violent and short time combustion on real time is a rapid, accurate and sensitive technique without interference the flame temperature field. Potential prospects of temperature measurement, gas product concentration measurement and combustion mechanism are also revealed.

Fluorocarbons↗

PubMed2001

The Near Ultraviolet Band System of Singlet Methylene.

In a classic paper by G. Herzberg and J. W. C. Johns entitled "The Spectrum and Structure of Singlet CH(2)" (Proc. Roy. Soc. A 295, 107-128 (1966)) the analysis of the &btilde;(1)B(1)<--ã(1)A(1) red absorption band system of CH(2) is discussed in detail for the first time. In addition to that band system the observation of a fragment of a weak near ultraviolet absorption band system is reported. The three observed bands of the system could not be vibrationally assigned or rotationally analyzed but it was pointed out that they probably involve absorption into the second excited singlet state, &ctilde;(1)A(1). We show this supposition to be true here by simulation. In order to simulate the spectrum we have calculated ab initio the &ctilde;-ã and &ctilde;-&btilde; transition moment surfaces and used the MORBID and RENNER program systems with previously determined potential energy surfaces for the ã, &btilde;, and &ctilde; states in a calculation of the energy levels and wavefunctions. We find that the three bands seen by Herzberg and Johns are part of the &ctilde;<--(ã/&btilde;) system but that all of the bands of the system above about 31 000 cm(-1) are missing as a result of &ctilde; state predissociation. We vibrationally assign the bands but the weakness of the spectrum, and the presence of perturbations, make it impossible for us to analyze the rotational structure fully. Further experimental and theoretical studies are suggested. Copyright 2001 Academic Press.

Journal Article↗

PubMed2000

Induction of Apoptosis in Tumor Cells by a Recombinant Adenovirus with bak Gene.

Apoptosis, a genetically encoded process of cellular suicide, comprises an intrinsic cellular defence against tumorigenesis. bak(for bcl-2 homologous antagonist/killer) is a new apoptosis-inducing gene found recently, which is identified in all tissues examined. Initial work of Farrow, Chittenden and Klefer indicated that bak plays an important role in apoptosis. Successive work of others suggests inactivity of Bak always accompanies the development of tumor cells. In this work, a shuttle vector harboring bak gene, pCA13-bak, was constructed and used to cotransfect into the cell line 293 together with a recombinant plasmid, pBHG11, containing most of adenovirus genome. A mutant adenovirus(delete E1, E3 region)carring bak, Ad-bak, was obtained, and purified. Dot blot identified the construction of recombinant virus was successful. HeLa cells were infected by this virus. Some manners were used to identify the changes of HeLa cells including Annexin V-FITC staining which made the reversed PS observed directly, microscope observation and others. The characteristic morphology of apoptotic cells was due to Ad-bak. The experiment suggests that bak is a strong apoptosis-inducing gene, and a potential gene which could be used in gene therapy on tumor.

Journal Article↗

PubMed2000

[The Comparison between the Killing Effects of Two Anti-T Immunotoxins on Target Cells]

The key to killing target cells by immunotoxin depends on the specific recognition of antibody to target cell and the cytotoxic effect of toxin. The comparative study of the killing effects of two anti-T immunotoxins, CD5:Ricin and CD5:rRA, on target cells was performed. The elimination rate of immunotoxins was analysed by flow cytometry and MLR. The effect of immunotoxins on the proliferation of hematopoiesis was evaluted by CFU-GM. The results showed that (1) CD5(+) T cells were eliminated and CD25(+) CD3(+) activated T cells were concentration-dependently inhibited by the two immunotoxins in the range of 10(-9) - 10(-11) mol/L; (2) both immunotoxins significantly inhibited the mixed lymphocyte reaction, and the inhibiting effect of CD5:rRA to T cell proliferation was markedly lower than that of CD5:Ricin in the range of 10(-10) - 10(-11) mol/L; (3) the combination of CD5:rRA with 10 mmol/L NH(4)Cl increased the T cell elimination rate; and (4) the two immunotoxins and the combination of NH(4)Cl and CD5:rRA did not suppressed proliferation of granulocyte-macrophage progenitors in the range of concentrations with killing effect. It was concluded that T cell and activated T cell could be eliminated effectively by immunotoxins, the proliferation of granulocyte-macrophage progenitor was not inhibited significantly.

Journal Article↗

PubMed2000

[Recovery of Early and Mature T Lymphocyte Subsets after Allogeneic Hematopoietic Stem Cell Transplantation]

To study the reconstituion of the T-cell populations after allogeneic hematopoietic stem cell transplantation, the peripheral blood samples obtained at different time points post-transplantation in 21 patients were analyzed using CD5-PE and CD3-FITC with flow cytometry. During the first 3 months after transplantation, CD3(-) CD5(+) T cell subsets, representing early thymocytes, remained below normal level, whereas CD3(+) CD5(+) T cell subsets, representing mature T cells, regenerated to normal level. In 9 patients who developed acute graft-versus-host disease (GVHD), the percentage of CD3(+) CD5(+) T cell subsets was significantly higher than that in patients who did not develop acute GVHD (P < 0.05). These results demonstrated that the early recovery of T cells is mainly due to the expansion of mature T cell populations, and the over-expansion of mature T (CD3(+) CD5(+)) cells is responsible for the development of acute GVHD.

Journal Article↗