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Biomedical subjects

Bo Chen

Publications and source records attributed to Bo Chen.

At least 109 records · Page 6Linked to original sources
PubMed2004

Four new eudesmanes from Caragana intermedia and their biological activities.

Four new eudesmanes, namely, 4(15)-eudesmene-1beta,7alpha-diol (1), 4(15)-eudesmene-1beta,7beta-diol (2), 7-trinoreudesma-4(15),8-dien-1beta-ol-7-one (3), and eudesma-4(15),7-dien-1beta-ol (4), as well as three known compounds, 5-epi-eudesma-4(15)-ene-1beta,6beta-diol (5), 4(15)-eudesmene-1beta,6alpha-diol (6), and 4(15)-eudesmene-1beta,5alpha-diol (7), were isolated from the aerial part of Caragana intermedia. The structures were elucidated by spectroscopic and spectrometric analyses including 1D, 2D NMR, HRMS, and IR. The structures of compounds 1, 5, 6, and 7 were confirmed by X-ray crystallographic analysis. Compound 7 showed glucose consumption activity with an IC value of 10.7 microg/mL in a C2C12 muscle cell assay. The MIC value of this compound (100 mg/kg) in a db/db mice model is equivalent to that of metformin in vivo.

Anti-HIV Agents↗
PubMed2004

[Effect of PKC inhibitor on P-gp expression and drug-resistance in MGC803 cells].

BACKGROUND & OBJECTIVE: It is showed that there is close relationship between multidrug resistance (MDR) and protein kinase C signal transduction system, but the mechanism remains unclarified. The aim of this study was to investigate the correlation between protein kinase C (PKC) signal transduction system and mdr1 gene in human gastric cancer cell line through studying the effect of vincristine (VCR) and a selective inhibitor of PKC, myr-psiPKC on MGC803 cells. METHODS: Western blot analysis was used to analyze the expression of P-glycoprotein (P-gp), which was encoded by mdr1, in transient VCR induced MGC803 cells, which were treated with or without myr-psiPKC. Cell cycle analysis was performed using flow cytometry and MTT assay was used to investigate the drug susceptibility of MGC803 cells which were exposed to VCR with or without myr-psiPKC. RESULTS: High level of P-gp expression was detected in the MGC803 cells after transient exposure to VCR, and its expression was down-regulated when the same VCR induced MGC803 cell line was incubated with myr-psiPKC. FCM results indicated that more MGC803 cells showed significantly higher level of apoptotic phenotype when treated with VCR and myr-psiPKC (ratio 31.23%), than those treated with only VCR (ratio 18.42%). The IC(50) (284.0+/-13.2 ng/ml) to VCR of MGC803 cells pretreated with VCR exhibited 2.24-fold of negative control group (127.0+/-17.6 ng/ml) and 1.33-fold of the group (212.0+/-30.4 ng/ml) treated with myr-psiPKC. CONCLUSION: The expression of P-gp can be induced by transient exposure to VCR and this induction can be inhibited by myr-psiPKC, which blocks the activity of PKCalpha and beta. PKC signal transduction system may play certain roles in modulating mdr1 expression in gastric cancer.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2004

Myosin light-chain kinase contributes to short-term endothelial cell cytoskeletal alteration induced by serum from burned rats.

OBJECTIVES: To investigate the time-dependent effects of serum from burned rats on cytoskeletal filamentous actin (F-actin) reorganization by visualizing their distribution in human umbilical vein endothelial cell line ECV-304 and evaluate the role of myosin light-chain kinase (MLCK) in this process. METHODS: The serum-starved ECV-304 cells were incubated with the serum from burned rats for 30 min, 1, 2, 4, and 6 h, respectively, and 30 min before or after the incubation, the cells were treated with 5 micromol/L ML-7 for 30 min. F-actin was stained with rhodamine-phalloidin and observed under fluorescence microscope. RESULTS: Under normal condition, F-actin was distributed mainly in the cortical area of the endothelial cells. After stimulation with the burn serum, stress fiber formation could be clearly seen in the endothelial cells, exhibiting a time-dependent enhancement in a time course ranging from 30 min to 6 h. Such an effect could be significantly inhibited by a 30-min pretreatment of the cells with MLCK-specific inhibitor ML-7. Inhibition of MLCK also reversed actin reorganization in the endothelial cells pretreated with the burn serum. CONCLUSION: Serum from burned rats induces characteristic morphological changes in the endothelial cell actin cytoskeleton mainly due to the MLCK activation, an effect that can be reversed by the inhibition of MLCK.

Actins↗
PubMed2004

Effects of lipopolysaccharide on actin reorganization and actin pools in endothelial cells.

OBJECTIVE: To investigate the dose and time-dependent effects of lipopolysaccharide (LPS) on cytoskeletal F-acitn and G-actin reorganizations by visualizing their distribution and measuring their contents in human umbilical vein endothelial cell line ECV-304. METHODS: F-actin was labeled with rhodamine-phalloidin and G-actin with deoxyribonuclease I (DNase I)conjugated with fluorescein isothiocyanate (FITC). Contents of cytoskeletal proteins were obtained by flow cytometry. RESULTS: F-actin was mainly distributed peripherally in endothelial cells under normal conditions. LPS stimulation caused the formation of stress fibers and filopodia. G-actin was normally seen in perinuclear and nuclear areas in control ECV-304 cells. Under LPS stimulation, G-actin dots appeared in the cytoplasmic region. The actin disorganization was accompanied by the time- and dose- dependent decrease in F-actin pool and increase in G-actin pool. CONCLUSIONS: LPS can induce characteristic morphological alterations of actin cytoskeleton and formation of intercellular gap in endothelial cells, accompanied by changes in F-actin and G-actin pools.

Actins↗
PubMed2004

[Immediate loading of dental implants in partialful edentulous and edentulous jaws].

OBJECTIVE: To investigate the clinical feasibility and technical characteristics of immediate loading and to access the short-term clinical results of treatment. METHODS: This study included 3 completely edentulous patients and 24 patients who were partially edentulous from March 1999 to December 2003. 21 implants were immediately loaded and provided support for mandibular overdenture for 3 fully edentulous patients. 30 implants were placed in 21 partially edentulous patients and implants were immediate loaded in edentulous mandibular providing support for fixed provisional prosthesis within 6 months. Then, metal-ceramic crowns were completed. All patients were followed up by 1, 3, 6, 12 months and the patients were checked every 12 months. RESULTS: A total of 42 implants were loaded immediately. From March 1999 to December 2003, no implants were lost during follow-up (range 3 to 49 months, mean of 28 months). No infections, nerve or sinus damage or other sequelae occurred. No implants exhibited peri-implant radiolucencies. Moreover, immediate loading seems to increase the ossification of the alveolar bone around endosseous implants. Patients were satisfied with the treatment. CONCLUSIONS: The data and the experience described in this study indicate that immediate loading with restorations using appropriate surgical and restorative techniques can predicate the completely edentulous and partially edentulous mandible in some cases. Further study is needed to determine the long-term result of immediately loaded implants.

Adult↗
PubMed2004

[Pulmonary disease caused by nontuberculous mycobacteria after allogeneic hematopoietic stem cell transplantation--a case report and literature review].

OBJECTIVE: To report a case with pulmonary disease caused by nontuberculous mycobacteria (NTM) after allogeneic hematopoietic stem cell transplantation (allo-HSCT), with a literature review. METHODS: Case report and literature review. RESULTS: A patient with acute non-lymphocytic leukemia was treated by allo-HSCT. Her NTM lung disease developed after HSCT was successfully treated with a 3 antimicrobials combination of clarithromycin, levofloxacin and capreomycin for 10 months. CONCLUSION: NTM infections are infrequent in allo-HSCT recipients and have a good clinical prognosis if correctly treated.

Adult↗
PubMed2004

[Occupational exposure profiles of polycyclic aromatic hydrocarbons in coke oven workers].

OBJECTIVE: To study the characteristics of occupational exposure of polycyclic aromatic hydrocarbons (PAHs) in coke oven workers. METHODS: Samples were collected individually and PAHs concentration in the ambient air were assayed by high performance liquid chromatography (HPLC) and toxic equivalency factors (TEFs) were introduced to assess the carcinogenic potency. RESULTS: The levels of PAHs occupational exposure in oven workers at topside was higher than at side oven and bottom oven (P < 0.05). Non-carcinogenic PAHs were more than 70% of total PAHs and benzo[a]pyrene accounted for 65.5% approximately 72.4% of total benzo[a]pyrene equivalents. Total occupational exposure level of PAHs in coke oven workers was positively related to the content of benzo[a]pyrene and pyrene, respectively (r(2) = 0.84, r(2) = 0.94, P < 0.05). CONCLUSION: Coke oven workers were exposed to a high level of PAHs which possessed some extent of carcinogenic potency, and benzo[a]pyrene is the chief carcinogenic substance.

Benzo(a)pyrene↗
PubMed2004

[Gly374Arg mutation in Fgfr3 causes achondroplasia in mice].

OBJECTIVE: To establish the mouse model of Gly374Arg mutation in fibroblast growth factor receptor 3(Fgfr3) and to analyze the phenotype of the mutant mice. METHODS: The double PCR was used to introduce Gly374Arg point mutation into mouse Fgfr3. The electroporation of embryonic stem(ES) cells was carried out with targeting vector. The targeted ES cells were screened by Positive-Negative Selection of G418 and Ganciclovir, and Southern blot. The correct targeted ES cells were microinjected into blastula. Finally, mutant mice were obtained by crossing between EIIa-Cre transgenic mice and mice carrying recombined mutant Fgfr3 allele. The mice were genotyped by PCR, and phenotype was observed by skeleton staining, histology, etc. RESULTS: Fgfr3-Gly374Arg mutant mice exhibited small size, short tail, macrocephaly and had dome-shaped heads, the epiphyseal growth plates of mutant mice were narrower, and the hypertrophic chondrocyte zone was also obviously decreased. Meanwhile, the majority of female mice were infertile, and the uterus, ovary and mammal gland in mutant female mice were also smaller and underdeveloped. CONCLUSION: The model of Fgfr3-Gly374Arg mutation causing achondroplasia in mice has been established successfully.

Achondroplasia↗
PubMed2004

[Fluorescence fluctuation spectroscopy with strong background fluorescence--a Monte Carlo approach].

Fluorescence fluctuation spectroscopy is a method in which fluorescence fluctuations arising from a very small sample volume are analysed to obtain brightness, diffusion coefficient and concentration of particles. Using Monte Carlo simulation, the influences of background autofluorescence and noises on fluorescence fluctuation spectroscopy are studied. Results show that a two-component photon counting histogram can effectively remove the effects due to background autofluorescence from low brightness and high concentration components and uniform noise. The result will help to bring applications of fluorescence fluctuation spectroscopy to intracellular environment.

English Abstract↗
PubMed2004

[Method to measure spectrum intensity from laser plasma soft X-ray source].

This paper presents a method to detect and measure spectrum intensity from a laser plasma soft X-ray source. A Channel Electron Multiplier (CEM) and a calibrated silicon photodiode were used as detectors in this method, the former is a nonstandard detector and the latter is a standard one. Charge-sensitive preamplifiers were used for measuring total charges generated by detectors, and a monochromator with high resolution was employed as the spectrometer. The formulae to calculate spectrum intensity from laser plasma soft X-ray source was given, based on the known grating efficiency of the monochromator, CEM's gain and responsivity of the silicon photodiode to photons.

Equipment Design↗
PubMed2004

[The experiment study on the resolution of electro-optical imaging system at EUV wave band].

An imaging system based on a Microchannel Plate (MCP) detector was designed to image the Extreme Ultraviolet (EUV) light. The images of a 3 mm-width-slit were presented by this imaging system at the wavelengths of 13, 17.1, 19.5 and 30.4 nm respectively. Their corresponding spatial resolutions are 85, 120, 182 and 495 microm respectively. The best is 85 microm, corresponding to 13 nm. Moreover, the shorter the wavelength, the better the spatial resolution. So is the brightness of the image.

English Abstract↗
PubMed2003

Progesterone regulation of the mammalian ortholog of methylcitrate dehydratase (immune response gene 1) in the uterine epithelium during implantation through the protein kinase C pathway.

Implantation requires coordination between development of the blastocyst and the sex steroid hormone-regulated differentiation of the uterus. Under the influence of these hormones, the uterine luminal epithelium becomes receptive to attachment of the hatched blastocyst. In this study we sought to identify genes regulated by progesterone (P4) in the uterine epithelium. This resulted in the identification of one novel P4-regulated gene that had been previously found in lipopolysaccharide-stimulated macrophages and called immune response gene-1 (Irg1) and which is the mammalian ortholog of the bacterial gene encoding methylcitrate dehydratase. In adult mice Irg1 expression was limited to the uterine luminal epithelium where it is expressed only during pregnancy with a peak coinciding with implantation. Irg1 mRNA expression is regulated synergistically by P4 and estradiol (E2) but not by E2 alone. In macrophages Irg1 is induced by lipopolysaccharide through a protein kinase C (PKC)-regulated pathway. Now we demonstrate that the PKC pathway is induced in the uterine epithelium at implantation by the synergistic action of P4 and E2 and is responsible for the hormone induction of Irg1. These results suggest that the PKC pathway plays an important role in modulating steroid hormone responsiveness in the uterine luminal epithelium during the implantation window and that Irg1 will be an important marker of this window and may play an important role in implantation.

Animals↗
PubMed2003

Afterpulsing and its correction in fluorescence correlation spectroscopy experiments.

Afterpulsing arises from feedback in a photon detector. This means that each real signal pulse can be followed by an afterpulse at a later time. This effect is particularly troubling in photon correlation experiments. Few treatments of this effect have appeared in the literature, and few software programs to solve the problem have been written. We demonstrate the afterpulsing effect in fluorescence correlation spectroscopy by using different avalanche photodiodes. We prove theoretically that under simple and reasonable conditions afterpulsing in autocorrelation can be eliminated to the leading order; we have found it easy to program software for the correction. We compare our results with those from cross correlation. We also discuss some experimental parameters that may affect the afterpulsing.

Journal Article↗
PubMed2003

Cyclin D2 compensates for the loss of cyclin D1 in estrogen-induced mouse uterine epithelial cell proliferation.

The cell cycle-regulatory protein, cyclin D1, is the sensor that connects the intracellular cell cycle machinery to external signals. Given this central role in the control of cell proliferation, it was surprising that mice lacking the cyclin D1 gene were viable and fertile. Fertility requires 17beta-estradiol (E2)-induced uterine luminal epithelial cell proliferation. In these cells E2 causes the translocation of cyclin D1/cyclin-dependent kinase 4 (CDK4) from the cytoplasm into the nucleus with the consequent phosphorylation of the retinoblastoma protein. In cyclin D1 null mice, E2 also induces retinoblastoma protein phosphorylation and DNA synthesis in a normal manner. CDK4 activity was slightly reduced in the D1 null mice compared with wild-type mice. This CDK4 activity was due to complexes of cyclin D2/CDK4. Cyclin D2 was translocated into the nucleus in response to E2 in the cyclin D1-/- mice to a much greater degree than in wild-type mice. This cyclin D2/CDK4 complex was also able to bind p27kip1 in cyclin D1-/- uterine luminal epithelial cells, allowing for the activation of CDK2. Our data show that in vivo cyclin D2 can completely compensate for the loss of cyclin D1 and reinforces the conclusions that cyclin Ds are the central regulatory point in the proliferative responses of epithelial cells to estrogens.

Animals↗
PubMed2003

Simultaneous analysis of caffeic acid derivatives and alkamides in roots and extracts of Echinacea purpurea by high-performance liquid chromatography-photodiode array detection-electrospray mass spectrometry.

High-performance liquid chromatography (HPLC) coupled with UV photodiode-array detection and electrospray ionization mass spectrometry was developed for the simultaneous analysis of caffeic acid derivatives and alkamides in the roots and extracts of Echinacea purpurea. Caffeic acid derivatives and alkamides produced very abundant peaks in the total ion current chromatogram during negative and positive cone voltage switching. Cichoric acid and the isomer pair, dodeca-2E,4E,8Z,10E/Z-tetraenoic acid isobutylamide, were used as a standard for quantification of caffeic acid derivatives and alkamides in E. purpurea. This novel method surpasses previously published ones in product quality control and providing the HPLC chromatographic fingerprints of biological active components in E. purpurea.

Amides↗
PubMed2003

NIRS monitoring of pilots subjected to +Gz acceleration and G-induced loss of consciousness (G-LOC).

With the increasing maneuverability of modern aircraft, there is an increased frequency of pilots losing consciousness due to high +Gz acceleration. This phenomena is defined as "G-induced loss of consciousness" (G-LOC). We used an NIRS system of our design to monitor cerebral oxygenation changes of pilots subjected to high +Gz acceleration and G-LOC. During the +Gz pulse, delta HbO2, and delta TotalHb decreased, with lesser changes of delta Hb. The maximum decrease of delta HbO2 and delta TotalHb usually occurred at the onset of G-LOC. After G-LOC, delta HbO2 and delta TotalHb increased rapidly for the first few seconds, beginning the reactive hyperemic recovery phase. delta HbO2 and delta TotalHb peaked, and then began to decrease towards baseline. The subjects were unconscious for 3-10 seconds after the onset of G-LOC. Upon returning to consciousness, the subjects were disoriented for another 4-11 seconds. NIRS provides an additional means of studying physiological mechanisms leading to and recovery from G-LOC.

Acceleration↗