Biomedical subjects

Yong Chen

Publications and source records attributed to Yong Chen.

At least 91 records · Page 5Linked to original sources

PubMed2006

[Transbronchial needle aspiration in the diagnosis of bronchogenic carcinoma with enlarged mediastinal and /or hilar lymph nodes].

OBJECTIVE: To evaluate the role of transbronchial needle aspiraion (TBNA) in the diagnosis of bronchogenic carcinoma with enlarged mediastinal and/or hilar lymph node. METHODS: Patients with mediastinal and/or hilar lymphoadenopathy proven by CT scan were eligible for TBNA as reported by WANG. All specimen was directly and instantly smeared for cytological examination. RESULTS: From June 2004 to May 2006, 77 such patients were examined: including 38 lung cancers, 35 lung benign diseases and 4 without definite diagnosis. All TBNA procedures were successfully carried out in 222/225 ( 98.7%). Positive TBNA rate was 81.6% (31/38) in patients who had been proven to suffer from bronchogenic carcinoma. The diagnosis of lung cancer was confirmed via TBNA only in 9 patients. A total of 63 lymph nodes in the 38 lung cancer patients were aspirated by TBNA with a positive rate of 65.1% (41/63). The sensitivity of TBNA was significantly correlated with pathology type, lymph node size and experience of the cytologist. Severe complications were rare except small amount of bleeding at the TBNA site (52/77, 67.5%). CONCLUSION: TBNA is quite safe and helpful in diagnosis and staging of bronchogenic carcinoma, yet it is not helpful in diagnosis of benign lung diseases.

Adolescent↗

PubMed2006

[Identification of hydroxylate metabolites of daidzein and its sulfate conjugates in rat urine by LC-ESI/MS(n)].

AIM: To identify the hydroxylate metabolites and its sulfate conjugates of daidzein in rat urine. METHODS: Urine samples from 0 - 24 h were collected after single ig dose of 500 mg x kg(-1) daidzein to each of six rats. The urine samples were purified by SPE column (SPE C18) and analyzed with liquid chromatographic-tandem electrospray ionization ion trap mass spectrometry (LC-ESI/MS(n)) for potential metabolites. RESULTS: Several new hydroxylate metabolites and its sulfate conjugates were found and identified in rat urine. CONCLUSION: LC-ESI/MS(n) is proved to be a simple, rapid, sensitive and specific technique for identification of the hydroxylate metabolites and its sulfate conjugates of daidzein in rat urine.

Animals↗

PubMed2006

[Determination on contents of matrix metalloproteinase 3 and interleukin 1 in tissues of lumbar disc herniation and their roles in pathogenesis].

OBJECTIVE: To determine the contents of matrix metalloproteinase 3 (MMP-3) and interleukin 1 (IL-1) in the tissues of the lumbar disc herniation and to investigate their roles in the pathogenesis. METHODS: The tissues of the herniated lumbar disc were obtained from 30 patients undergoing surgery for persistent radiculopathy from June 2003 to December 2004 and at the same time these samples were divided into the following three experimental groups: the bulge group (n =11), the protrusion group (n = 9), and the prolapsus group (n = 10), 14 males, 16 females, aged 33-64 years. As the control group, 9 lumbar disc specimens were harvested from 9 patients (4 males, 5 females, aged 21-58 years) suffering from bursting fracture of the lumbar spine. The specimens were analyzed by the ELISA method for the contents of MMP-3 and IL-1. RESULTS: The contents of MMP-3(14.25+/-1. 32, 19.89+/-2.97, 20.69+/-2.18 ng/ml in the bulge group, protrusion group and prolapsus group, separately) and IL-1 (8.52+/-0.22, 11.88+/-0.52, 11.90+/-0.73 pg/ml in the bulge group, protrusion group and prolapsus group, separately) in the experimental groups were significantly higher than those in the control group. The contents of MMP-3 and IL-1 in the protrusion group were not significantly higher than those in the prolapsus group, but they were significantly higher than those in the bulge group(P<0.01). The contents of MMP-3 had a significant relationship with the contents of IL-1 in the three experimental groups and the control group(P<0. 01). CONCLUSION: The result demonstrates that the tissues of the lumbar disc herniation can produce both MMP-3 and IL-1, which may have an unknown but important relationship with each other.

Adult↗

PubMed2005

Surface modification and laser pulse length effects on internal energy transfer in DIOS.

Benzyl-substituted benzylpyridinium (BP) chloride salts were used as a source of thermometer ions to probe the internal energy (IE) transfer in desorption/ionization on porous silicon (DIOS). To modify their wetting properties and the interaction energies with the thermometer ions, the DIOS surfaces were silylated to produce trimethylsilyl- (TMS), amine- (NH2), perfluoroalkyl- (PFA), and perfluorophenyl-derivatized (PFP) surfaces. Two laser sources--a nitrogen laser with pulse length of 4 ns and a mode locked 3 x omega Nd:YAG laser with a pulse length of 22 ps--were utilized to induce desorption/ionization and fragmentation at various laser fluence levels. The corresponding survival yields were determined as indicators of the IE transfer and the IE distributions were extracted. In most cases, with increasing the laser fluence in a broad range (approximately 20 mJ/cm2), no change in IE transfer was observed. For ns excitation, this was in remarkable contrast with MALDI, where increasing the laser fluence resulted in sharply (within approximately 5 mJ/cm2) declining survival yields. Derivatization of the porous silicon surface did not affect the survival yields significantly but had a discernible effect on the threshold fluence for ion production. The IE distributions determined for DIOS and MALDI from alpha-cyano-4-hydroxycinnamic acid reveal that the mean IE value is always lower for the latter. Using the ps laser, the IE distribution is always narrower for DIOS, whereas for ns laser excitation the width depends on surface modification. Most of the differences between MALDI and DIOS described here are compatible with the different dimensionality of the plume expansion and the differences in the activation energy of desorption due to surface modifications.

Journal Article↗

PubMed2005

Membrane deformation of unfixed erythrocytes in air with time lapse investigated by tapping mode atomic force microscopy.

Estimation of the time of death is one of the most important problems for forensic medicine and law. Physical and chemical postmortem changes are evaluated together while estimating the time of death. The pattern analysis of antemortem and postmortem bloodstains is one of the important parameters for forensic science, and cellular changes of blood cells can be useful for the quantitative assessment of the time of death. In this study, by successively investigating erythrocytes exposed in air on mica for 5 days using tapping mode atomic force microscopy (TM-AFM), we observed deformation of whole cell and membrane surface of unfixed erythrocytes with time lapse. We found that the time-dependent cellular changes occurred after exposure of erythrocytes in air for several days. At 0.5 days of exposure, fissures and cell shrinkage were observed. At 2.5 days of exposure, the emergence of nanometer-scale protuberances were observed and these protuberances increased in number with increasing time. The changes of cell shape and cell membrane surface ultrastructure can be used to estimate the time of death. Futhermore, smear-induced abnormal erythrocytes and immunostained erythrocytes were observed here. The need for more precise research is indicated, such as the correlation of membrane changes to intervals of less than 0.5 day of air exposure, and use of various substrates in addition to mica, including glass, metals, fabrics, among others, on which the bloodstains appear in crime scenes. The results of this research demonstrate the efficacy of AFM as a potentially powerful analytical tool in forensic science.

Air↗

PubMed2005

Spectrophotometric study of fluorescence sensing and selective binding of biochemical substrates by 2,2'-bridged bis(beta-cyclodextrin) and its water-soluble fullerene conjugate.

A bis(beta-cyclodextrin)-fullerene conjugate (3) linked at the secondary hydroxyl side was prepared in a good yield from its precursor N,N'-bis(2-(2-aminoethylamino)ethyl)malonamide-bridged bis(beta-cyclodextrin) (2). Spectrophotomeric studies on the conformation and the inclusion complexation behavior of 3 with a variety of organic and biochemical substrates by means of UV-vis, FT-IR, NMR, fluorescence, and circular dichroism spectroscopy showed that the bis(beta-cyclodextrin)-fullerene conjugate displayed an intramolecular capsule-type conformation in aqueous solution. Because of the multiple binding of bis(beta-cyclodextrin) with substrates, 2 can act as an efficient fluorescence sensor for biochemical substrates, while its fullerene conjugate 3 displays a capability of cleaving DNA under visible-light irradiation.

Benzyl Compounds↗

PubMed2005

Microwave-assisted protein preparation and enzymatic digestion in proteomics.

The combinations of gel electrophoresis or LC and mass spectrometry are two popular approaches for large scale protein identification. However, the throughput of both approaches is limited by the speed of the protein digestion process. Present research into fast protein enzymatic digestion has been focused mainly on known proteins, and it is unclear whether these results can be extrapolated to complex protein mixtures. In this study microwave technology was used to develop a fast protein preparation and enzymatic digestion method for protein mixtures. The protein mixtures in solution or in gel were prepared and digested by microwave-assisted protein enzymatic digestion, which rapidly produces peptide fragments. The peptide fragments were further analyzed by capillary LC and ESI-ion trap-MS or MALDI-TOF-MS. The technique was optimized using bovine serum albumin and then applied to human urinary proteins and yeast lysate. The method enabled preparation and digestion of protein mixtures in solution (human urinary proteins) or in gel (yeast lysate) in 6 or 25 min, respectively. Equivalent (in-solution) or better (in-gel) digestion efficiency was obtained using microwave-assisted protein enzymatic digestion compared with the standard overnight digestion method. This new application of microwave technology to protein mixture preparation and enzymatic digestion will hasten the application of proteomic techniques to biological and clinical research.

Chromatography, Liquid↗

PubMed2005

Mechanisms underlying enhanced P2X receptor-mediated responses in the neuropathic pain state.

P2X3 and P2X2/3 receptors in dorsal root ganglia (DRG) appear to participate in producing nociceptive responses after nerve injury. However, the mechanisms underlying the receptor-mediated nociception in the neuropathic state remain unclear. Using spared nerve injury (SNI) rats, we found that allodynic and nocifensive (flinch) behavioral responses developed after injury can be reversed by P2X receptor antagonists, indicating an involvement of P2X receptors. Immunocytochemical studies revealed that P2X3 receptors are expressed in small and medium but rarely in large DRG neurons of both normal and SNI rats. Thus, contrary to the conventional view that only large A beta cells mediate allodynia, small and medium cells are intimately involved in P2X3 receptor-mediated allodynia. Measuring ATP levels in the subcutaneous space of the rat paw, we showed that ATP release does not change after SNI. On the other hand, the P2X receptor agonist, alpha beta-methylene ATP produces 3.5-fold larger flinch responses at a 8.0-fold lower dose. Thus, sensitization of P2X3 receptors rather than a change in ATP release is responsible for the neuropathic pain behaviors. We further demonstrated that sensitization of P2X3 receptors arises from an increase in receptor function. ATP-induced P2X3 receptor-mediated currents in DRG neurons is 2.5-fold larger after SNI. The expression of P2X3 receptors on the cell membrane is significantly enhanced while the total expression of P2X3 receptors remained unchanged. Thus, the enhancement of trafficking of P2X3 receptors is likely an important mechanism contributing to the increase in receptor function after nerve injury.

Animals↗

PubMed2005

Time-weighted average water sampling with a solid-phase microextraction device.

A fiber-in-needle SPME device was developed and investigated for time-weighted average water sampling. The device was designed so that the overall mass-transfer resistance is contained within the static water inside the needle, which ensures that mass uptake could be predicted with Fick's first law of diffusion and the sampling rate is less affected by water turbulence. The device possesses all of the advantages of commercialized devices, in addition to needle filling and replacement ease. Laboratory calibration with deployment of the device to a flow-through system demonstrated that there was a linear mass uptake for up to 12 days, and the linear range could be longer. PDMS coating is assumed to be a perfect zero sink for most polycyclic aromatic hydrocarbons, except naphthalene. The effect of water temperature was also investigated. Under normal field conditions, the change of mass uptake rate with temperature was negligible. To facilitate the convenience for long-term water sampling, a new standard aqueous generator was introduced. This study extended the application of SPME technology for long-term water sampling.

Journal Article↗

PubMed2005

Hepatitis E virus chimeric DNA vaccine elicits immunologic response in mice.

AIM: To construct the plasmid pcHEV23 containing fragments of HEV ORF2 and ORF3 chimeric gene and to assess its ability to elicit specific immunologic response in mice. METHODS: The gene encoding the structural protein of HEV ORF2 fragment and full-length ORF3 was amplified by PCR. The PCR products were cloned into an eucaryotic expression plasmid pcDNA3. The resulting plasmid pcHEV23 was used as a DNA vaccine to inoculate BALB/c mice intramuscularly thrice at a dose of 100 or 200 microg. Mice injected with empty pcDNA3 DNA or saline served as control and then specific immune responses in the mice were detected. RESULTS: After 2-3 times of inoculation, all mice injected with pcHEV23 had anti-HEV IgG seroconversion and specific T lymphocyte proliferation. The lymphocyte stimulation index in the group immunized with pcHEV23 (3.1+/-0.49) was higher than that in the control group (0.787+/-0.12, P<0.01). None in the control group had a detectable level of anti-HEV IgG. CONCLUSION: DNA vaccine containing HEV ORF2 and ORF3 chimeric gene can successfully induce specific humoral and cellular immune response in mice.

Animals↗

PubMed2005

Nano neodymium oxide induces massive vacuolization and autophagic cell death in non-small cell lung cancer NCI-H460 cells.

Neodymium, a rare earth element, was known to exhibit cytotoxic effects and induce apoptosis in certain cancer cells. Here we show that nano-sized neodymium oxide (Nano Nd2O3) induced massive vacuolization and cell death in non-small cell lung cancer NCI-H460 cells at micromolar equivalent concentration range. Cell death elicited by Nano Nd2O3 was not due to apoptosis and caspases were not involved. Electron microscopy and acridine orange staining revealed extensive autophagy in the cytoplasm of the cells treated by Nano Nd2O3. Autophagy induced by Nano Nd2O3 was accompanied by S-phase cell cycle arrest, mild disruption of mitochondrial membrane potential, and inhibition of proteasome activity. Bafilomycin A1, but not 3-MA, induced apoptosis while inhibiting autophagy. Our results revealed a novel biological function for Nano Nd2O3 and may have implications for the therapy of non-small cell lung cancer.

Antineoplastic Agents↗

PubMed2005

Atomic force microscope tracking observation of Chinese hamster ovary cell mitosis.

CHO cells possess easily identifiable karyotypes, and CHO cell chromosomes are large and few in number, making these cells ideal for mutational and drug toxicity studies and suitable for investigations of animal chromosome structure. Here, we used atomic force microscopy (AFM) in the tapping mode for detailed visualizations of Chinese hamster ovary (CHO) cell chromosomes during various mitotic phases, including typical prophase, prometaphase, metaphase, anaphase and telophase. Based on our detailed observations, we were able to divide metaphase and anaphase into sub-phases: metaphase I, II and III, and anaphase I and II. Furthermore, we used the AFM error-signal mode to visualize chromosomal ultrastructures and cytokinesis. While these visualizations were all successful, we found that the image quality was affected by cellular debris, contamination. Collectively, our results show that the AFM technique has great potential for the detailed study of chromosomes and chromosomal ultrastructures during all phases of the cell cycle, but that careful standards of sample preparation must be maintained.

Anaphase↗

PubMed2005

New neoclerodane diterpenoids isolated from the leaves of Salvia divinorum and their binding affinities for human kappa opioid receptors.

Bioactivity-guided fractionation of the leaves of Salvia divinorum has resulted in the isolation of three new neoclerodane diterpenoids: divinatorin D (1), divinatorin E (2), and salvinorin G (3), together with 10 known terpenoids, divinatorin C (4), hardwickiic acid (5), salvinorin-A (6), -B (7), -C (8), -D (9), -E (10), and -F (11), presqualene alcohol (12), and (E)-phytol (13). The structures of these three new compounds were characterized by spectroscopic methods. All these compounds were evaluated for their binding affinities to the human kappa opioid receptors. In comparison with divinatorin D (1), divinatorin E (2), and salvinorin G (3), salvinorin A (6) is still the most potent kappa agonist.

Binding, Competitive↗

PubMed2005

Synthesis and in vitro pharmacological studies of C(4) modified salvinorin A analogues.

Salvinorin A is the most potent naturally occurring opioid agonist with a high selectivity and affinity for kappa-opioid receptor. To explore its structure-activity relationships, modifications at the C(4) position have been studied and a series of salvinorin A derivatives were prepared. These C(4)-modified salvinorin A analogues were screened for binding and functional activities at the human kappa-opioid receptor and several potent new agonists have been identified.

Analgesics, Opioid↗

PubMed2005

Liquid chromatography-tandem mass spectrometry analysis of anisodamine and its phase I and II metabolites in rat urine.

A sensitive and specific method for the analysis of anisodamine and its metabolites in rat urine by liquid chromatography-electrospray ionization tandem mass spectrometry (LC-MS/MS) was developed. Various extraction techniques (free fraction, acid hydrolyses and enzyme hydrolyses) and their comparison were carried out for investigation of the metabolism of anisodamine. After extraction procedure the pretreated samples were injected on a reversed-phase C18 column with mobile phase (0.2 ml/min) of methanol/0.01% triethylamine solution (adjusted to pH 3.5 with formic acid) (60:40, v/v) and detected by MS/MS. Identification and structural elucidation of the metabolites were performed by comparing their changes in molecular masses (DeltaM), retention-times and full scan MS(n) spectra with those of the parent drug. At least 11 metabolites (N-demethyl-6beta-hydroxytropine, 6beta-hydroxytropine, tropic acid, N-demethylanisodamine, hydroxyanisodamine, anisodamine N-oxide, hydroxyanisodamine N-oxide, glucuronide conjugated N-demethylanisodamine, sulfate conjugated and glucuronide conjugated anisodamine, sulfate conjugated hydroxyanisodamine) and the parent drug were found in rat urine after the administration of a single oral dose 25mg/kg of anisodamine. Hydroxyanisodamine, anisodamine N-oxide and the parent drug were detected in rat urine for up 95 h after ingestion of anisodamine.

Animals↗

PubMed2005

A human beta-cell line for transplantation therapy to control type 1 diabetes.

A human pancreatic beta-cell line that is functionally equivalent to primary beta-cells has not been available. We established a reversibly immortalized human beta-cell clone (NAKT-15) by transfection of primary human beta-cells with a retroviral vector containing simian virus 40 large T-antigen (SV40T) and human telomerase reverse transcriptase (hTERT) cDNAs flanked by paired loxP recombination targets, which allow deletion of SV40T and TERT by Cre recombinase. Reverted NAKT-15 cells expressed beta-cell transcription factors (Isl-1, Pax 6, Nkx 6.1, Pdx-1), prohormone convertases 1/3 and 2, and secretory granule proteins, and secreted insulin in response to glucose, similar to normal human islets. Transplantation of NAKT-15 cells into streptozotocin-induced diabetic severe combined immunodeficiency mice resulted in perfect control of blood glucose within 2 weeks; mice remained normoglycemic for longer than 30 weeks. The establishment of this cell line is one step toward a potential cure of diabetes by transplantation.

Animals↗

PubMed2005

Flow-through system for the generation of standard aqueous solution of polycyclic aromatic hydrocarbons.

Standard aqueous solution of organic pollutants is used for the development of analysis methods and novel water sampling devices. The use of solid-phase microextraction (SPME) and other novel technologies for research in water sampling and analysis requires systems for the reliable generation of standard aqueous solution. In this communication, a new flow-through system based on permeation is introduced for the generation of standard aqueous solution of polycyclic aromatic hydrocarbons (PAHs). The main difference between the new developed system and typical system is that the syringe pump was changed with a permeation generator. The generator-based permeation offers many advantages, including convenient, inexpensive, solvent-free, long lifetime and production of high concentrations of the target analytes. The observed change in the concentration of the six PAH compounds was less than 20% over 3 months.

Dialysis↗

PubMed2005

The extracellular matrix guides the orientation of the cell division axis.

The cell division axis determines the future positions of daughter cells and is therefore critical for cell fate. The positioning of the division axis has been mostly studied in systems such as embryos or yeasts, in which cell shape is well defined. In these cases, cell shape anisotropy and cell polarity affect spindle orientation. It remains unclear whether cell geometry or cortical cues are determinants for spindle orientation in mammalian cultured cells. The cell environment is composed of an extracellular matrix (ECM), which is connected to the intracellular actin cytoskeleton via transmembrane proteins. We used micro-contact printing to control the spatial distribution of the ECM on the substrate and demonstrated that it has a role in determining the orientation of the division axis of HeLa cells. On the basis of our analysis of the average distributions of actin-binding proteins in interphase and mitosis, we propose that the ECM controls the location of actin dynamics at the membrane, and thus the segregation of cortical components in interphase. This segregation is further maintained on the cortex of mitotic cells and used for spindle orientation.

Actins↗