Biomedical subjects

Yong Chen

Publications and source records attributed to Yong Chen.

At least 145 records · Page 8Linked to original sources

PubMed2005

[In vitro inhibitory effect of dibenzoxanthene CY-B12 on proliferation of tumor cell lines and its possible mechanisms].

BACKGROUND & OBJECTIVE: CY-B12, a new dibenzon-xanthene, has been synthesized recently. This study was to investigate the in vitro antiproliferative activity of CY-B12 and its possible mechanisms. METHODS: The inhibitory effects of CY-B12 on proliferation of gastric carcinoma cell line MGC803, nasopharyngeal carcinoma cell line CNE-2, oral epithelial carcinoma cell line KB-3-1, and lung cancer cell line Glc82 were assessed by MTT assay. Cell cycle distribution and apoptosis were detected by flow cytometry (FCM). Apoptotic morphology of CNE-2 cells was observed under fluorescent microscope after Hoechst33258 staining. The expression of cell cycle-related proteins Cdc25C, Cdc2, and Cyclin B1 were measured by Western blot. DNA damage was detected by single cell gel electrophoresis (SCGE). RESULTS: CY-B12 obviously inhibited the proliferation of MGC803, CNE-2, KB-3-1, and Glc82 cells; the IC(50) values were 7.51, 9.58, 8.84, and 15.99 micromol/L, respectively. After treatment of CY-B12, CNE-2 cells were arrested at G(2)/M phase; chromatin condensation, apoptotic bodies, and sub-G1 peak were observed in CNE-2 cells. The protein expression of Cdc25C in CNE-2 cells was down-regulated by CY-B12 in a dose-dependent mannerû whereas Cyclin B1 and Cdc2 were up-regulated by low dose of CY-B12, and down-regulated by high dose of CY-B12. CY-B12 induced DNA damage in CNE-2 cells in a dose-dependent manner. CONCLUSION: CY-B12 has potent in vitro antiproliferative activity, which may be exerted through breaking DNA, down-regulating cell cycle-related protein Cdc25C, and inducing cell cycle arrest and apoptosis.

Antineoplastic Agents↗

PubMed2005

[Comparing studies on the differences of CCl4 liver injury and immunity liver injury mice models].

Comparison between CCl4 liver injury model and immunity liver injury model was studied through physiological, biochemical and gene expression profile methods, and the pathological mechanism of them were discussed. There are significant changes about the physiological, biochemical parameters including ALT,AST between two model groups and normal control group. Among the 14112 target genes, 379 and 293 differentially expressed genes were screened out from the both two model groups respectively in gene expression profile experiments, including 105 common, differentially expressed genes. The results indicate that the two models of CCl4 and immunity have some similarities. However, the differences between them are also obvious. It is useful for the further investigation on the liver-injury mechanism and pathological process of the two different liver-injury models.

Alanine Transaminase↗

PubMed2005

[Identification of triacylglycerols in coix oil by high performance liquid chromatography-atmospheric pressure chemical ionization-mass spectrometry].

OBJECTIVE: To identify triacylglycerols in coix oil. METHOD: High performance liquid chromatography-atmospheric pressure chemical ionization-mass spectrometry was used for identification. The experiment was operated under the conditions: spray voltage at 3 000 V, capillary temperature at 250 degrees C, APCI vaporizer temperature at 400 degrees C, and corona current of 4 microA. Sheath gas pressure (high purity liquid nitrogen) was 35 kPa. Mass spectra were obtained over the m/e range of 300 to 900 amu, scan duration of 1s and Q1 peak width at 0.7. The stationary phase was Zorbax Extend C18 column (4.6 mm x 250 mm, 5 microm). The mobile phase: dichloromethane-acetonitrile (35:65), flow rate: 1 mL x min(-1); column temperature: 25 degrees C. RESULT: 12 triacylglycerols were identified by HPLC-MS method. CONCLUSION: The result can be used to identify the components in a fingerprint chromatogram of coix oil and its related injection product.

Chromatography, High Pressure Liquid↗

PubMed2005

[Changes of gene expression profiles in CCl4 injured liver of mice].

AIM: To study the gene expression profiles between the CCl4 injured liver and normal liver in mice, and to screen the differentially expressed genes that relate to liver injury by CCl4 on a large scale using cDNA microarrays. METHODS: Male Kunming strain mice were divided into two groups: one was control group and another was CCl4 injured liver group that was given 0.1% CCI4 oil solution ip at dose of 10 mL x kg(-1) every three days, totally for ten times. Then mRNA in livers of the two groups of mice was extracted, separately, and reversely transcribed to cDNA with the incorporation of different fluorescent-labeled dUTP as the hybridization probes. The mixed probes were hybridized to the cDNA microarrays. The fluorescent signal values were acquired by scanner and analyzed with statistical software. RESULTS: Among the 14 100 target genes, 379 genes were differentially expressed, in which 163 genes were up-regulated and the other 216 genes were down-regulated. They are closely related to a range of biological functions. CONCLUSION: Using the cDNA microarray and experimental animal modeling technique, the differentially expressed genes of CCl4 injured liver in mice on a large scale could be studied. It is useful for further investigation of the injury mechanism of CCl4.

Alanine Transaminase↗

PubMed2005

[Retrospective analysis of 934 nasopharyngeal carcinoma patients treated with conventional external beam radiotherapy alone].

OBJECTIVE: To analyze the clinical outcome of 934 primary nasopharyngeal carcinoma treated with conventional external beam radiotherapy alone. METHODS: 34 patients were treated from Jan. 1, 1999 to Dec. 31, 1999. The radiation fields were delineated according to the CT/MRI imaging findings on disease extent. Two lateral opposing isocentric portals with customized blockings were used for the nasopharynx and upper neck. The dose delivered to tumor in the nasopharynx was 68-70 Gy/2 Gy fraction/7 weeks. The doses delivered to the neck was 60-70 Gy/6-7 weeks for patients with positive lymph nodes and 50 Gy/5 weeks for the patients with negative lymph node. RESULTS: The 1-, 2-, 3- and 4-year overall survival rate (OS) was 89.5%, 81.9%, 78.1% and 75.7%, and metastasis-free survival rate (MFS) was 84.0%, 77.2%, 74.4% and 72.0%, respectively. The 1-, 2-, 3- and 4-year disease-free survival rate (DFS) was 80.8%, 73.1%, 68.5% and 65.1%, and the relapse-free survival rate (RFS) was 95.5%, 92.7%, 90.3% and 87.3%, respectively. The overall failure rate was 30.9% (289/934). At the end of the radiotherapeutic course, the percentage of residual disease was 14.6%. The 4-year loco-regional recurrence and distant metastasis rates after radiotherapy were 7.2% and 9.2% with a median time of 19.3 months and 12.8 months. CONCLUSION: It may be helpful to improve radiotherapy curative effect when the target is individually designed through improving irradiation technique according to CT/MRI findings and by shortening the overall course time, enhancing irradiation dose and strictly implementing QA/QC measures.

Adolescent↗

PubMed2005

[Study on time-series analysis and forecast models on lung cancer incidence in Qidong, 1972 - 2001].

OBJECTIVE: To explore the lung cancer incidence rates from 1972 to 2001 and utilize varieties of models in forecasting trend up to 2010 in the city of Qidong, Jiangsu in order to provide baseline data for its control and prevention. METHODS: Using data from the cancer registry office in Qidong, we tried to reveal the trends of lung cancer incidence by analyzing the time-series on trends extrapolation, exponent smoothness, Box-Jenkins model etc. We also compared the prognostication precision, endow differ power, and established assembled forecast model. RESULTS: Data showed that there had been a rising trend of lung cancer from 1972 to 2001 and would still probably be on the increase in the future. The rate of male and female attained to 70 per 100 000 and 20 per 100 000, predicting that there would be a respective 33 percent and 10 percent increase in 2010. CONCLUSIONS: According to analysis of forecast models, it was right to prognosticate lung cancer incidence from time-series and improve forecast precision through developing combination models. The result of combination seemed close to ARIMA models which suggested that it could serve as a chief way to forecast the incidence of lung cancer.

China↗

PubMed2004

Atomic force microscopy imaging and 3-D reconstructions of serial thin sections of a single cell and its interior structures.

The thin sectioning has been widely applied in electron microscopy (EM), and successfully used for an in situ observation of inner ultrastructure of cells. This powerful technique has recently been extended to the research field of atomic force microscopy (AFM). However, there have been no reports describing AFM imaging of serial thin sections and three-dimensional (3-D) reconstruction of cells and their inner structures. In the present study, we used AFM to scan serial thin sections approximately 60 nm thick of a mouse embryonic stem (ES) cell, and to observe the in situ inner ultrastructure including cell membrane, cytoplasm, mitochondria, nucleus membrane, and linear chromatin. The high-magnification AFM imaging of single mitochondria clearly demonstrated the outer membrane, inner boundary membrane and cristal membrane of mitochondria in the cellular compartment. Importantly, AFM imaging on six serial thin sections of a single mouse ES cell showed that mitochondria underwent sequential changes in the number, morphology and distribution. These nanoscale images allowed us to perform 3-D surface reconstruction of interested interior structures in cells. Based on the serial in situ images, 3-D models of morphological characteristics, numbers and distributions of interior structures of the single ES cells were validated and reconstructed. Our results suggest that the combined AFM and serial-thin-section technique is useful for the nanoscale imaging and 3-D reconstruction of single cells and their inner structures. This technique may facilitate studies of proliferating and differentiating stages of stem cells or somatic cells at a nanoscale.

Animals↗

PubMed2004

Effect of perinatal asphyxia on tyrosine hydroxylase and D2 and D1 dopamine receptor mRNA levels expressed during early postnatal development in rat brain.

This study was designed to investigate the postnatal developmental plasticity of the mesostriatal and mesolimbic dopamine systems that occurs following perinatal asphyxia. The time course and patterning of the changes in levels of tyrosine hydroxylase (TH), and D1 and D2 dopamine receptor (R) mRNA in the cell body region, substantia nigra and ventral tegmental area (SN/VTA), and projection fields, striatum and limbic regions at the age of 6 and 24 h, and 1 week after asphyxia were studied with a quantitative reverse transcription polymerase chain reaction method with appropriate internal cRNA standard. In Caesarean-delivered control rats (Sprague-Dawley), TH, D2R and D1R mRNA levels showed regional and temporal specificity in both absolute levels and developmental kinetics during the first week of life. TH mRNA levels were >10-fold higher in SN/VTA than in striatum and limbic regions. Compared to Caesarean delivered controls, severe asphyxia (15-20 min) induced an increase of TH and D2R mRNA in SN/VTA 6 h and 1 week after birth. In addition, asphyxia induced an increase of TH mRNA in the projection fields, striatum and limbic regions, at 1 week. Perinatal asphyxia did not appear to exert any effect on D1R mRNA levels. No differences in any of the parameters were observed between spontaneous- and Caesarean-delivered animals. The present results indicate that perinatal asphyxia triggers coordinated changes in the expression of TH, and dopamine receptor mRNA in SN/VTA, striatum and limbic regions. These changes may affect differently dopamine D2R and D1R expression along development, contributing to long-term neurocircuitry imbalances.

Analysis of Variance↗

PubMed2004

Inclusion complexes of paclitaxel and oligo(ethylenediamino) bridged bis(beta-cyclodextrin)s: solubilization and antitumor activity.

The inclusion complexation behavior of paclitaxel with a series of oligo(ethylenediamino) bridged bis(beta-cyclodextrin)s possessing bridge chains in different length (1-4) has been investigated in order to improve the water solubility of paclitaxel. It is found that only the long-tethered bis(beta-cyclodextrin)s 1 and 2 can form the inclusion complexes with paclitaxel, which are characterized by NMR, SEM, XRD, FT-IR, TG-DTA, DSC, and microcalorimetry technology. The results obtained show that bis(beta-cyclodextrin)s 1 and 2 are able to solubilize paclitaxel to high levels up to 2 and 0.9 mg/mL, respectively. The high complex stability of bis(beta-cyclodextrin) 1 and paclitaxel is discussed from thermodynamic viewpoint. Furthermore, the cytotoxicity of these complexes assessed using a human erythroleukemia K562 cell line indicates that the IC(50) value of 1/paclitaxel complex is 6.0 x 10(-10) mol/dm(3) (calculated as paclitaxel molar concentration), which means that the antitumor activity of 1/paclitaxel complex is better than that of parent paclitaxel (IC(50) value 9.8 x 10(-10) mol/dm(3)). This high antitumor activity, along with the satisfactory water solubility and high thermal stability of the 1/paclitaxel complex, will be potentially useful for its clinical application as a highly effective antitumor drug.

Antineoplastic Agents↗

PubMed2004

Solid-phase microextraction field sampler.

To facilitate the use of solid-phase microextraction (SPME) for field sampling, a new field sampler was designed and tested. The sampler was versatile and user-friendly. The SPME fiber can be positioned precisely inside the needle for time-weighted average sampling or exposed completely outside the needle for grab sampling. The needle is protected within a shield at all times, hereby eliminating the risk of operator injury and fiber damage. A replaceable Teflon cap is used to seal the needle to preserve sample integrity. Factors that affect the preservation of sample integrity (sorbent efficiency, temperature, sealing materials) were studied. The use of a highly efficient sorbent for the fiber is recommended as the first choice for the preservation of sample integrity. Teflon was a good material for sealing the fiber needle, had little memory effect, and could be used repeatedly. To address adsorption of high boiling point compounds on fiber needles, several kinds of deactivated needles were evaluated. RSC-2 fiber needles were the more effective. A preliminary field sampling investigation demonstrated the validity of the new SPME device for field applications.

Adsorption↗

PubMed2004

Evidence of a first-order phase transition between Wigner-crystal and bubble phases of 2D electrons in higher Landau Levels.

For filling factors nu in the range between 4.16 and 4.28, we simultaneously detect two resonances in the real diagonal microwave conductivity of a two-dimensional electron system (2DES) at low temperature T approximately 35 mK. We attribute the resonance to Wigner-crystal and Bubble phases of the 2DES in higher Landau Levels. For nu below and above this range, only single resonances are observed. The coexistence of both phases is taken as evidence of a first-order phase transition. We estimate the transition point as nu=4.22.

Journal Article↗

PubMed2004

Kinetics and the on-site application of standards in a solid-phase microextraction fiber.

The kinetics of the desorption of analytes from a SPME fiber into an agitated sample matrix was studied, and a theoretical model was proposed to describe the dynamic desorption process, based on the steady-state diffusion of analytes in the extraction phase and in the boundary layer. It was found that the desorption of analytes from a SPME fiber into an agitated sampling matrix is isotropic to the absorption of the analytes onto the SPME fiber from the sample matrix under the same agitation conditions, and this allows for the calibration of absorption using desorption. The calibration was accomplished by exposing a SPME fiber, preloaded with a standard, to an agitated sample matrix, during which desorption of the standard and absorption of analytes occurred simultaneously. When the standard was the isotopically labeled analogue of the target analyte, the information from the desorption process, i.e., time constant a, could be directly used for estimating the concentration of the target analyte. When the standard varied from the target analyte, the mass-transfer coefficient of the analyte could be extrapolated from that of the standard. These predictions agree well with experimental results. This approach facilitates the full integration of sampling, sample preparation, and sample introduction, especially for on-site or in vivo investigations, where the addition of standards to the sample matrix, or control of the velocity of the sample matrix, is very difficult.

Journal Article↗

PubMed2004

Autocrine expression of hepatocyte growth factor and its cytoprotective effect on hepatocyte poisoning.

AIM: To construct pEGFP-hepatocyte growth factor (HGF) expression vector, the to detect its expression in transfected human hepatocytes, and to investigate the influence of autocrine HGF expression on the proliferative potential and cytoprotective effects in human hepatocytes. METHODS: Human HGF cDNA was ligated to the pEGFP vector. Recombinant plasmid was transfected into human hepatocyte line QZG with liposome. Expression of HGF protein was observed by fluorescence microscopy and immunohistochemistry. Hepatic cells were collected 24, 48, and 72 h after transfection to detect the number of ((3)H)-TdR uptake in DNA. DNA synthesis was observed by using PCNA stain immunohistochemistry. Acute liver cell damage was induced by carbon tetrachloride. Cytoprotective effect was observed by examining the survival rate of hepatocytes and leakage of intracellular alanine transaminase (ALT) and potassium ions. RESULTS: HGF identification of pEGFP-HGF by enzyme digestion showed that HGF fragment was cloned into BamH I and Sal I sites of pEGFP-N3. Expression of GFP in transfected hepatocytes was observed with fluorescence microscopy. The ((3)H)-TdR uptake became 7 times as many as in the control group 96 h after transfection. After HGF transfection, the survival rate of hepatocytes poisoned by CCl(4) significantly increased (83% vs 61%, P<0.05), and the leakage of intracellular alanine transaminase and potassium ions decreased (586 nkat/L vs 1 089 nkat/L, P<0.01; and 5.59 mmol/L vs 6.02 mmol/L, P<0.01 respectively). Culture of transfected hepatic cells promoted the proliferation of other non-transfected cells. CONCLUSION: Transfected HGF is expressed in hepatic cells and has the activity of promoting cell division and protecting hepatic cells against poisoning.

Cell Division↗

PubMed2004

Nek2A kinase regulates the localization of numatrin to centrosome in mitosis.

Chromosome segregation in mitosis is orchestrated by the kinetochore and spindle microtubules stemming from two centrosomes. Our recent studies demonstrated the importance of Nek2A in faithful chromosome segregation during mitosis. Here, we report that Nek2A regulates the function of numatrin in mitosis. The biochemical interaction between Nek2A and numatrin in mitotic cells was revealed by a set of reciprocal immunoprecipitation experiments using Nek2A and numatrin antibodies, respectively. The interaction is validated by a pull-down assay using recombinant Nek2A and numatrin proteins. Moreover, our immunofluorescence studies demonstrate that numatrin becomes centrosome-associated as the cell enters into mitosis and depart from the centrosome after sister chromatid separation in anaphase. The co-localization of numatrin and Nek2A to the centrosome suggests their interaction with and involvement in centrosome function. Indeed, elimination of Nek2A kinase by siRNA diminished its association with the centrosome. Furthermore, we show that numatrin is phosphorylated by wild type but not kinase-death Nek2A. Our studies suggest that the Nek2A kinase cascade is essential for the localization of numatrin to the centrosome.

Centrosome↗

PubMed2004

The effect of anesthesia and surgery on CYP3A activity in rats.

The purpose of this investigation was to examine the effects of surgery and anesthesia on in vivo CYP3A activity and portal venous blood flow. Midazolam, a CYP3A probe for both rats and humans, was administered orally (2.7 mg), intravenously (0.57 mg), or via the portal vein (0.57 mg) to rats 4 h after anesthesia with ketamine/xylazine and surgery for placement of indwelling vascular and duodenal catheters and 3 days after surgery (chronic). The systemic clearance of midazolam was 51 +/- 4 ml/min/kg in the chronic animals, and this was significantly decreased (29 +/- 1 ml/min/kg, P = 0.024) in acute rats studied 4 to 6 h after anesthesia and surgery. The hepatic availability (FH), directly determined from the aortic and hepatic venous concentration gradient, was significantly higher in the acute animals (0.57 +/- 0.05) compared with the chronic animals (0.33 +/- 0.07, P = 0.001). Hepatic availability was determined using a classical approach in which FH was calculated from the area under the plasma concentration versus time curve ratio after portal venous or intravenous administration. FH was higher in the acute rats (0.48) compared with the chronic animals (0.27 +/- 0.03). Portal venous blood flow was significantly lower in the acute animals (5.0 +/- 0.4 ml/min/100 g body weight) compared with the chronic animals (9.1 +/- 0.9 ml/min/100 g body weight, P = 0.015). The effect of surgery and anesthesia was confirmed using the indicator dye dilution method after infusion of [14C]polyethylene glycol 4000 into the superior mesenteric artery. Our data suggest that anesthesia and surgery decreases both hepatic CYP3A activity and hepatic blood flow in rats. Studies performed in rats within 3 days of surgery and anesthesia are conducted under nonphysiologic conditions and therefore provide inaccurate assessment of drug disposition, in particular, clearance and bioavailability.

Anesthetics↗

PubMed2004

An integrated AC electrokinetic pump in a microfluidic loop for fast and tunable flow control.

We have built a dedicated lab on a chip to study the performance of an integrated electrokinetic micropump, driven by a low voltage AC signal. This micropump consists of an array of interdigitated electrodes and is here integrated in a microfluidic loop. We demonstrate that this device can pump continuously and reproducibly electrolyte solutions of low to moderate ionic strength. The pumping speed reaches up to 500 [micro sign]m s(-1) in 20 [micro sign]m deep and 100 [micro sign]m wide channels with a driving signal in the 1-10 kHz range and an amplitude of only a few volts. In addition, we have observed an interesting reversal of the pumping direction at higher frequencies (50-100 kHz). Our device permits a systematic and automated exploration of the influence of the ionic strength thanks to an integrated micromixer.

Journal Article↗

PubMed2004

Biquinolino-modified beta-cyclodextrin dimers and their metal complexes as efficient fluorescent sensors for the molecular recognition of steroids.

A series of bridged beta-cyclodextrin (beta-CyD) dimers possessing functional tethers of various lengths was synthesized in moderate yield by the treatment of 2,2'-biquinoline- 4,4'-dicarboxylic dichloride with beta-CyD or mono[6-oligo(ethylenediamino)-6-deoxy]-beta-CyDs. The products were 2,2'-biquinoline-4,4'-dicarboxy-bridged bis(6-O-beta-CyD) (8), N,N'-bis(2-aminoethyl)-2,2'-biquinoline-4,4'-dicarboxamide-bridged bis(6-amino-6-deoxy-beta-CyD) (9), and N,N'-bis(5-amino-3-azapentyl)-2,2'-biquinoline-4,4'-dicarboxamide-bridged bis(6-amino-6-deoxy-beta-CyD) (10). The reaction of 8-10 with copper perchlorate give their copper(II) complexes 11-13 in satisfactory yields of over 77 %. All the bis(beta-CyD)s 8-13 act as efficient fluorescent sensors and display remarkable fluorescence enhancement upon addition of optically inert steroids. The inclusion complexation behaviors of 8-13 when treated with the representative steroids cholate (14), deoxycholate (15), and glycocholate (16) in aqueous solution at 25 degrees C were investigated by means of UV/Vis spectroscopy, conductivity and fluorescence measurements, circular dichroism spectroscopy, and 2D NMR spectroscopy. The tether length of bis(beta-CyD) 9 allows it to adopt a cooperative host-tether-guest binding mode in which the spacer and guest are co-included in the two CyD cavities. As a result of this cooperation, 9 has a stability constant (K(s)) about 2x10(2) times higher than that of monomodified beta-CyD 4 for inclusion complexation with cholate. Metallooligo(beta-CyD)s with four beta-CyD units have enhanced binding abilities compared with monomodified beta-CyDs. These metallo compounds have binding affinities for guest steroids that are up to 50-4.1x10(3) times higher than those of CyDs 2-4. The guest-induced fluorescence enhancement of bis(CyD)s opens a new channel for the design of sensor materials. The complex stability constants of these compounds are discussed from the viewpoint of induced-fit interaction and cooperative multiple binding between host and guest.

Circular Dichroism↗

PubMed2004

Gigantic cavernous hemangioma of the liver treated by intra-arterial embolization with pingyangmycin-lipiodol emulsion: a multi-center study.

PURPOSE: To evaluate the therapeutic effect and safety of pingyangmycin-lipiodol emulsion (PLE) intra-arterial embolization for treating gigantic cavernous hemangioma of the liver (CHL). METHODS: Three hospitals (Nanfang Hospital, Inner Mongolia Autonomous Region's Hospital and Huai He Hospital) participated in the study during 1997-2001. A total of 98 patients with CHL were embolized with PLE via the hepatic artery. The therapeutic effects including changes in tumor diameter, symptomatic improvement and occurrence of complications were evaluated for a period of 12 months after the procedure. RESULTS: The tumor diameters decreased significantly from 9.7 +/- 2.3 cm to 5.6 +/- 1.6 cm 6 months after the treatment ( P < 0.01), and then to 3.0 +/- 1.2 cm at 12 months ( P < 0.01). Transient impairment of liver function was found in 77 cases after embolization, 69 cases of which returned to normal in 2 weeks, and the other eight cases of which recovered 1 month later. The clinical symptoms were significantly relieved in all 53 symptomatic patients. Persistent pain in the hepatic region was found in two cases, and these two patients resorted to surgery eventually. CONCLUSION: Intra-arterial PLE embolization proves to be effective and safe in treating patients with CHL.

Adult↗