Biomedical subjects

Bin Chen

Publications and source records attributed to Bin Chen.

At least 181 records · Page 10Linked to original sources

PubMed2003

[The regulatory effect of human bone morphogenetic protein 7 gene transfer on the proliferation and differentiation of rabbit bone marrow mesenchymal stem cells].

OBJECTIVE: To detect the proliferation and differentiation of rabbit bone marrow mesenchymal stem cells (BMSc) transferred by retroviral vector carrying human bone morphogenetic protein 7 (hBMP-7) gene. METHODS: hBMP-7-expressing replication-deficient retroviral vector(PT-PLNCX2-hBMP7) was reconstructed using clone technique and recombinant DNA technique. BMSc were infected with the virus granules. The protein of BMP-7 gene in transferred cells were determined by immunohistochemistry. The proliferativity of the transferred cell were assayed by methabenzthiazuron (MTT) method and flow cytometer. Alkaline phosphatase (ALP) were also detected using enzyme kinetics. RESULTS: Cells transferred by PT-PLNCX2-hBMP7 expressed abundant hBMP7 protein in the cytoplasm. Positive findings were not found in those cells that were not transferred. After infected with virus there were not significant difference of cell proliferation and cell cycle between the cells transferred by hBMP-7 or not (P > 0.05). ALP activity in transferred cells were increased significantly (P < 0.01). CONCLUSIONS: hBMP-7 can be transferred and stably expressed in the cultured rabbit bone marrow stem cells. Proliferation and cell cycle of the transferred cell were not affected. hBMP7 gene transfer can be used to induce differentiation of BMSc into osteoblast-like cells.

Alkaline Phosphatase↗

PubMed2003

[The method of accelerating osteanagenesis and revascularization of tissue engineered bone in big animal in vivo].

OBJECTIVE: To study whether tissue engineered bone can repair the large segment bone defect of large animal or not. To observe what character the fascia flap played during the osteanagenesis and revascularization process of tissue engineered bone. METHODS: 9 Chinese goats were made 2 cm left tibia diaphyseal defect. The repairing effect of the defects was evaluated by ECT, X-ray and histology. 27 goats were divided into three groups: group of CHAP, the defect was filled with coral hydroxyapatite (CHAP); group of tissue engineered bone, the defect was filled with CHAP + bone marrow stroma cells (BMSc); group of fascia flap, the defect was filled with CHAP + BMSc + fascia flap. After finished culturing and inducing the BMSc, CHAP of group of tissue engineered bone and of fascia flap was combined with it. Making fascia flap, different materials as described above were then implanted separately into the defects. Radionuclide bone imaging was used to monitor the revascularization of the implants at 2, 4, 8 weeks after operation. X-ray examination, optical density index of X-ray film, V-G staining of tissue slice of the implants were used at 4, 8, 12 weeks after operation, and the biomechanical character of the specimens were tested at 12 weeks post operation. RESULTS: In the first study, the defect showed no bone regeneration phenomenon. 2 cm tibia defect was an ideal animal model. In the second study, group of CHAP manifested a little trace of bone regeneration, as to group of tissue engineered bone, the defect was almost repaired totally. In group of fascia flap, with the assistance of fascia flap which gave more chance to making implants to get more nutrient, the repair was quite complete. CONCLUSIONS: The model of 2 cm caprine tibia diaphyseal defect cannot be repaired by goat itself and can satisfy the tissue engineering's demands. Tissue engineered bone had good ability to repair large segment tibia defect of goat. Fascia flap can accelerate the revascularization process of tissue engineered bone. And by this way, it augment the ability of tissue engineered bone to repair the large bone defect of goat.

Animals↗

PubMed2003

[The application of intravascular ultrasound imaging in the diagnosis of aortic dissection].

OBJECTIVE: To evaluate the role of intravascular ultrasound (IVUS) imaging in the diagnosis of aortic dissection. METHODS: Eighty-two patients with aortic dissection were admitted. The role of IVUS was evaluated and compared with CT, MRI, transthoracic echocardiography (TTE), transesophageal echocardiography (TEE), Duplex scanning and digital subtraction angiography (DSA). RESULTS: The different laminar appearance of the outer wall of the true and false lumen, characteristic alterations in the true and false lumen junction and the thrombosis in the false lumen detected by IVUS were useful to differentiate the true from the false lumen. Static and dynamic narrowing, causing visceral ischemia could be detected by IVUS imaging. The detection rate of entry site by IVUS was 100%, higher than CT (28%), MRI (22%), TTE (2%) and TEE (61%), P < 0.01, having no statistic difference with DSA (88%). The detection rate of the distal end of the dissection by IVUS was 100%, higher than Duplex (21%), P < 0.01, but had no statistic difference as compared with CT (89%) and MRI (86%). The detection rate of visceral arteries by IVUS was 98%, higher than CT (56%), MRI (57%), Duplex (17%) and DSA (66%), P < 0.01. The aortic diameter measured by IVUS was correlated well with CT measurement (r = 0.94, P < 0.01). CONCLUSIONS: A full picture of aortic dissection can be obtained using IVUS imaging. It has an advantage over routine examinations in detecting visceral artery origin and clarifying visceral ischemia causes.

Adult↗

PubMed2003

[Textual research of wuguteng].

OBJECTIVE: To make clear the origin of the traditional Chinese medicine, Wuguteng. METHODS: The correlation literature was consulted and arranged. RESULTS: There are a few plants using as Wuguteng, such as Fissistigma glaucescens (Hance) Merr. and Marsdenia tenacissima (Roxb.) Wight et Arn. in the records of principle literature. Wuguteng used as a drug was first recorded in "Dian Nan Ben Cao". The views of various persons in past dynasties on the efficacy of Wuguteng are unanimous. CONCLUSION: The paper has proved that Wuguteng comes from Marsdenia tenacissima of Asclepiadaceae.

Annonaceae↗

PubMed2003

[Protective effect of natural dietary antioxidants on space radiation-induced damages].

This paper described the radiation-induced damage on human body in space and summarized the studies of antioxidants such as Vit C, Vit E, Vit A, beta-carotene, flavonoids, polysaccharide, green-tea and Spirulina protection against radiation-induced damage. Application prospects of natural antioxidants in space food were also put forward in this article.

Antioxidants↗

PubMed2003

[Special space food: microecological health food].

Intestinal microflora and its balance have a specific effect on human health. This paper described the changes in astronauts' intestinal microflora and its adverse effects on human health, as well as the application of microecological health food in the area of manned spaceflight.

Adaptation, Physiological↗

PubMed2003

[Evaluation of interactive efficacy of two mycoinsecticides and low application rate imidacloprid in controlling greenhouse whitefly Trialeurodes vaporariorum (Homoptera: Aleyrodidae)].

The interactive effects of pure emulsifiable formulations (10(10) conidia.ml-1) of Beauveria bassiana and Paecilomyces fumosoroseus conidia and 1% and 3% of imidacloprid 10% WP were tested for controlling greenhouse whitefly, Trialeurodes vaporariorum, on lettuce grown in four polyethylene film-covered greenhouses (5 m x 100 m) in Kunming, Yunnan. Six fungal treatments, two imidacloprid ones, and one water-spray control were included in the experiment, with each being replicated in three plots (7 m x 5 m.plot-1). For each of the treatments, 1000-fold aqueous dilution (10(7) conidia.ml-1) was sprayed twice at a 15-d interval, with the first spray given on day 11 after lettuce transplantation. Counts of live and dead whiteflies from each treatment were made on the initial day, and then, once every five days. During a 30-d period of observation from August 20, the two applications of the fungal formulations alone or those containing low rates of imidacloprid 10% WP effectively protected the lettuce from damage by T. vaporariorum, and generated relative efficacies. Whitefly density decreased > 95%, which was significantly higher than that attributed to the low application rates of imidacloprid 10% WP. Based on the estimations of relative efficacy and percent density decrease, P. fumosoroseus treatments controlled the whiteflies better than B. bassiana ones, and the effects of both fungi on the pest population were apparently enhanced with the quantity of imidacloprid added. The differences among the fungal treatments in the two estimations were larger during the first 10 days, but decreased thereafter, becoming insignificant on day 10 after the second spray. The results indicated that the fungal formulations tested in this study are of great potential for practical use in whitefly control, and their efficacy could be enhanced with low rates of imidacloprid.

Animals↗

PubMed2002

Cross-polarization/magic angle spinning NMR to study glucose mobility in a model intermediate-moisture food system.

Theories for the chemical stability of foods cite the role of moisture content or water activity in reactant mobility, though mobility has been variously defined. One theory, based on plasticization by moisture, is limited by a lack of research directly linking the mobility of a matrix to the mobility and reactivity of small solute molecules in foods. A cross-polarization/magic angle spinning technique was developed to study glucose rotational mobility in the solid state over a range of water activities and in matrixes with different glass transition temperatures. Data analysis stressed the significance of separating molecular mobility from relaxation time. Results showed that, in a caseinate matrix, compared to a control, adding glycerol yielded the highest glucose mobility and lowest glass transition temperature (T(g)), while adding sorbitol also increased mobility and lowered T(g). Consequently, plasticization by either moisture or these humectants increases the mobility of small solute molecules such as glucose.

Chemical Phenomena↗

PubMed2002

An electrodiffusion model for effects of surface glycocalyx layer on microvessel permeability.

To investigate the charge effect of the endothelial surface glycocalyx on microvessel permeability, we extended the three-dimensional model developed by Fu et al. (J Biomech Eng 116: 502-513, 1994) for the interendothelial cleft to include a negatively charged glycocalyx layer at the entrance of the cleft. Both electrostatic and steric exclusions on charged solutes were considered within the glycocalyx layer and at the interfaces. Four charge-density profiles were assumed for the glycocalyx layer. Our model indicates that the overall solute permeability across the microvessel wall including the surface glycocalyx layer and the cleft region is independent of the charge-density profiles as long as they have the same maximum value and the same total charge. On the basis of experimental data, this model predicts that the charge density would be 25-35 meq/l in the glycolcalyx of frog mesenteric capillaries. An intriguing prediction of this model is that when the concentrations of cations and anions are unequal in the lumen due to the presence of negatively charged proteins, the negatively charged glycocalyx would provide more resistance to positively charged solutes than to negatively charged ones.

Capillary Permeability↗

PubMed2002

Vapor-liquid interfacial properties of mutually saturated water/1-butanol solutions.

Adsorption and ordering at the vapor-liquid interfaces of mutually saturated water/1-butanol solutions at a temperature of 298.15 K were investigated using configurational-bias Monte Carlo simulations in the Gibbs ensemble and compared to the surface properties of neat water and 1-butanol liquids. A dense 1-butanol monolayer is observed at the surface of the water-rich phase, which results in a substantial decrease of its surface tension. In contrast, there is no enrichment of water molecules at the surface of the butanol-rich phase, and its surface tension is not significantly changed. Analysis of the interfacial structures reveals that these systems exhibit orientational ordering and composition heterogeneity. Analysis of the hydrogen-bonding distributions suggests that the formation of the 1-butanol monolayer is driven by an excellent match between water and the primary alcohol; that is, additional hydrogen bonds are formed between the excess free hydrogens of surface water and the excess hydrogen-bond acceptor sites of 1-butanol.

1-Butanol↗

PubMed2002

Non-invasive determination of intraocular pressure in the rat eye. Comparison of an electronic tonometer (TonoPen), and a rebound (impact probe) tonometer.

BACKGROUND: The reproducibility and accuracy of the induction/impact (I/I) probe device (rebound tonometer) and the TonoPen XL electronic tonometer were compared through the measurement of intraocular pressure (IOP) differences between contralateral rat eyes. METHODS: IOP was measured in 18 female Wistar rats with variable, modest elevations of IOP in one eye. Mean IOP from five measurements on each of the 36 eyes was determined using the rebound tonometer, followed by the TonoPen XL. Following cannulation, true (manometrically determined) IOP was recorded with a calibrated pressure transducer. Differences between the operated and normal eye of each animal for each tonometric method of measurement were correlated with the true difference in IOP. RESULTS: IOP differences between the operated and contralateral normal eye ranged from +5.9 to -1.7 mmHg (mean +1.7 mmHg) when measured by cannulation and from +7.2 to -1.4 mmHg (mean +2.4 mmHg) and +9.8 to -3.2 mmHg (mean +3.6 mmHg) when measured with the rebound tonometer and TonoPen XL respectively. Differences between eyes recorded by rebound tonometer ( y) correlated with those determined by cannulation ( x) in a linear fashion ( y=0.8243 x+1.0721; R(2)=0.6603). Correlation for the TonoPen XL was much weaker ( y=0.8675 x+2.1672; R(2)=0.2077). IOP measurements using the rebound tonometer did not differ significantly from true IOP, whereas TonoPen XL increasingly underestimated IOP with increasing IOP (9-20 mmHg). CONCLUSION: The rebound tonometer displayed greater accuracy and less variability than TonoPen XL in measuring the IOP of the rat eye (range 9-20 mmHg).

Animals↗

PubMed2002

Gene expression profiles with activation of the estrogen receptor alpha-selective estrogen receptor modulator complex in breast cancer cells expressing wild-type estrogen receptor.

Selective Estrogen Receptor Modulators (SERMs) are a new class of drugsthat bind to estrogen receptor (ER) and elicit agonistic or antagonistic responses, depending on the target tissue. We have developed an in vitro system in which some SERMs (4-hydroxytamoxifen and resveratrol) demonstrate estrogenic response through wild-type (wt) ER, whereas others (raloxifene and GW7604) remain antiestrogenic. This system mimics the tamoxifen-resistant phenotype in clinic, when resistant tumors contain wtER. We used Atlas cDNA arrays to study gene expression profiles after ER activation by different SERMs in MDA-MB-231 human breast cancer cells stably transfected with wtER. Cells were treated with estradiol, four different SERMs, and the pure antiestrogen ICI 182,780. The obtained expression data were analyzed using GeneSpring software. Real-time reverse transcription-PCR was used to verify the array data. Our results showed that treatment with various compounds altered the expression of a diverse group of genes, revealing sets of overlapping genes that may represent a complex network of genes of interrelated signal transduction pathways. Sets of "agonistic" and "antagonistic" genes were identified on the basis of the known response to different SERMs. Further analysis of selected sets of genes revealed functionally related group of genes in each set, encoding proteins that were related to cell proliferation, survival, and apoptosis. Flow cytometry data indicated an antiapoptotic activity in cells treated with agonists versus apoptotic activity in cells treated with antagonists. A model for estradiol-like (survival) and antiestrogen-like (apoptosis) activities of SERMs on the basis of their gene expression profiles is suggested.

Breast Neoplasms↗

PubMed2002

First-principles study of aqueous hydroxide solutions.

Car-Parrinello molecular dynamics simulations have been carried out for aqueous NaOH and KOH solutions under ambient conditions over a wide range of concentrations. From these simulations, we have observed a continuous change of the water structure with added hydroxide, characterized by a significant shift of the second peak of the OO radial distribution functions to shorter distances. At the highest concentration investigated, the normal tetrahedral coordination of pure water is completely missing, a result that is consistent with a recent neutron diffraction experiment. The added hydroxide also gives rise to some unique spectroscopic features, including a "free" O-H stretch, a broadening of the normal water OH stretching band, and a large blue shift of both the librational band and the low-frequency translation. These results are in good agreement with the experimental data. Finally, it was demonstrated that the structural and dynamical behavior is inextricably linked to the formation of compact hydroxide-water complexes.

Journal Article↗

PubMed2002

De novo design of biomimetic antimicrobial polymers.

The design of polymers and oligomers that mimic the complex structures and remarkable biological properties of proteins is an important endeavor with both fundamental and practical implications. Recently, a number of nonnatural peptides with designed sequences have been elaborated to provide biologically active structures; in particular, facially amphiphilic peptides built from beta-amino acids have been shown to mimic both the structures as well as the biological function of natural antimicrobial peptides such as magainins and cecropins. However, these natural peptides as well as their beta-peptide analogues are expensive to prepare and difficult to produce on a large scale, limiting their potential use to certain pharmaceutical applications. We therefore have designed a series of facially amphiphilic arylamide polymers that capture the physical and biological properties of this class of antimicrobial peptides, but are easy to prepare from inexpensive monomers. The design process was aided by molecular calculations with density functional theory-computed torsional potentials. This new class of amphiphilic polymers may be applied in situations where inexpensive antimicrobial agents are required.

Anti-Bacterial Agents↗

PubMed2002

Photodynamic therapy with hypericin induces vascular damage and apoptosis in the RIF-1 mouse tumor model.

Hypericin, a polycyclic quinone obtained from plants of the genus Hypericum, has been proven to be a potent photosensitizer. The mechanism of tumor eradication and mode of cell death induced by in vivo photodynamic therapy (PDT) with hypericin were investigated in the present study using 2 therapeutic protocols. RIF-1 tumors were exposed to laser light at either 0.5 hr or 6 hr after hypericin administration (5 mg/kg, i.v.). A significant reduction in tumor perfusion, as determined by the retention of fluorescein in the tumor tissue, was detected immediately after both PDT treatments. Further decrease in tumor perfusion was observed in the hours after treatment. The re-establishment of tumor perfusion, however, occurred 24 hr after 6 hr-interval PDT, but not after 0.5 hr-interval PDT. The kinetics of tumor cell survival estimated by the in vivo/in vitro clonogenic assay revealed no or limited cell death when tumors were explanted immediately after irradiation, whereas a delayed but progressive cell death was detected when tumors remained in situ after both PDT treatments. The detection of nucleosomal DNA fragmentation by agarose gel electrophoresis or TUNEL assay and the assessment of cell morphology by light microscopy indicated that apoptosis was the most prominent tumor response to hypericin-mediated PDT. Furthermore, immunohistochemical analysis of the tumor tissue showed an increased expression of both Fas and Fas ligand after irradiation, suggesting that this cell death pathway might contribute to the overall PDT-induced apoptotic response. In conclusion, our results demonstrate that apoptosis, likely occurring as a result of vascular damage, is responsible for the tumor eradication by PDT with hypericin in this tumor model.

Animals↗

PubMed2002

Investigation of the mechanism of n-butane oxidation on vanadium phosphorus oxide catalysts: evidence from isotopic labeling studies.

The selective oxidation of n-butane to maleic acid catalyzed by vanadium phosphates (VPO) is one of the most complex partial oxidation reactions used in industry today. Numerous reaction mechanisms have been proposed in the literature, many of which have butenes, butadiene, and furan as reaction intermediates. We have developed an experimental protocol to study the mechanism of this reaction in which (13)C-isotopically labeled n-butane is flowed over a catalyst bed and the reaction products are analyzed using (13)C NMR spectroscopy. This protocol approximates the conditions found in an industrial reactor without requiring an exorbitant amount of isotopically labeled material. When [1,4-(13)C]n-butane reacted on VPO catalysts to produce maleic acid and butadiene, the isotopic labels were observed in both the 1,4 and 2,3 positions of butadiene and maleic acid. The ratio of label scrambling was typically 1:20 for the 2,3:1,4 positions in maleic acid. For butadiene, the ratio of label scrambling was consistently much higher, at 2:3 for the 2,3:1,4 positions. Because of the discrepancy in the amount of label scrambling between maleic acid and butadiene, butadiene is unlikely to be the primary reaction intermediate for the conversion of n-butane to maleic anhydride under typical industrial conditions. Ethylene was always observed as a side product for n-butane oxidation on VPO catalysts. Fully (13)C-labeled butane produced about 5-13 times as much isotopically labeled ethylene as did [1,4-(13)C]butane, indicating that ethylene was produced mainly from the two methylene carbons of n-butane. When the reaction was run under conditions which minimize total oxidation products such as CO and CO(2), the amounts of ethylene and carbon oxides produced from fully (13)C-labeled butane were almost equal. This strongly suggests that the total oxidation of n-butane on VPO catalysts involves the oxidation and abstraction of the two methyl groups of n-butane, and the two methylene groups of n-butane form ethylene. An organometallic mechanism is proposed to explain these results.

Journal Article↗

PubMed2002

Enhancing the antitumoral effect of hypericin-mediated photodynamic therapy by hyperthermia.

BACKGROUND AND OBJECTIVES: In the previous study, we have found a synergistic effect on the RIF-1 tumor cell killing when hypericin-mediated photodynamic therapy (PDT) was combined with hyperthermia. The purpose of the present study was to investigate the antitumoral effect of hypericin-PDT in combination with hyperthermia in the RIF-1 mouse tumor model. STUDY DESIGN/MATERIALS AND METHODS: Tumor response to PDT in combination with hyperthermia was compared to the response to PDT or hyperthermia alone. To explore the possible mechanism involved in the interaction of PDT and hyperthermia, we determined the tumor cell survival by in vivo/in vitro cell survival assay and analyzed the functional blood vessels by Hoechst 33342 staining. The mode of cell death was examined by TUNEL assay. RESULTS: Enhanced tumor response was obtained by PDT immediately followed by hyperthermia. Tumor cell survival assay revealed that indirect vascular effect contributed greatly to the overall tumor cell death induced by PDT with hypericin, whereas direct tumor cytotoxicity played a major role in hyperthermia-induced tumor cell killing. Combining PDT with hyperthermia brought about a synergistic interaction on direct tumor cell killing. Even though PDT or hyperthermia alone induced severe blood vessel shutdown and the combined treatments led to significant potentiation of the vascular damage as examined by Hoechst staining, the gain in tumor cell death as a result of this secondary vascular effect was limited after the combined treatments. Following the cellular damage by PDT in combination with hyperthermia, tumor cells were triggered to undergo apoptosis. CONCLUSIONS: Our study demonstrated the possibility of using hyperthermia to potentiate the antitumoral effect of hypericin-mediated PDT.

Animals↗

PubMed2002

Defining normal upper airway motion in asymptomatic children during sleep by means of cine MR techniques.

PURPOSE: To define normal upper airway motion in asymptomatic children during sleep by means of dynamic cine magnetic resonance (MR) techniques. MATERIALS AND METHODS: In children referred for MR of the brain who required sedation, a sagittal midline cine MR sequence was performed. Motion of the nasopharynx, oropharynx, and hypopharynx was characterized as static patent, dynamic patent, intermittent collapse, or static collapsed; maximal diameter and greatest change in size were calculated in millimeters. Mouth position (open or closed) was determined. Parameters were compared with age (t test) and mouth position (Fisher exact test). RESULTS: In the 148 subjects (mean age, 3.4 years), the nasopharynx showed dynamic motion in 53 (36%). The oropharynx was most commonly collapsed in 98 (66%) of the patients. The hypopharynx showed dynamic motion in 72 (49%) of the patients and was never collapsed. Vertical motion was present in 77 (52%) of the patients. The mouth was open in 96 (65%) of the patients. There was a statistically significant correlation between mouth position and dynamic motion in the oropharynx (P =.006) and in the nasopharynx (P <.006) but not in the hypopharynx (P =.655). CONCLUSION: Dynamic changes in diameter were often seen in the nasopharynx and in the hypopharynx of asymptomatic sleeping children. However, collapse of the hypopharynx was not normally encountered.

Adolescent↗