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Bin Chen

Publications and source records attributed to Bin Chen.

At least 145 records · Page 8Linked to original sources
PubMed2004

Wide dispersal of aphid-pathogenic Entomophthorales among aphids relies upon migratory alates.

Entomophthoralean mycoses are of general importance in the natural control of aphids, but mechanisms involved in their dissemination are poorly understood. Despite several possible means of fungal survival, the dispersal of the mycoses in aphids has never been related to the flight of their migratory alates that are able to locate suitable host plants. In this study, aphid-pathogenic fungi proved to be widely disseminated among various aphids by their alates through migratory flight based on the following findings. First, up to 36.6% of the 7139 migratory alates (including nine species of vegetable or cereal aphids) trapped from air > 30 m above the ground in three provinces of China were found bearing eight species of fungal pathogens. Of those, six were aphid-specific Entomophthorales dominated in individual cases by Pandora neoaphidis, which occurs globally but has no resting spores discovered to date. Secondly, infected alates were confirmed to be able to fly for hours, to initiate colonies on plants after flight and to transmit fungal infection to their offspring in a laboratory experiment, in which 238 Sitobion avenae alates were individually flown in a computer-monitoring flight mill system after exposure to a spore shower of P. neoaphidis and then allowed to colonize host plants.

Animal Migration↗
PubMed2004

An electrodiffusion-filtration model for effects of endothelial surface glycocalyx on microvessel permeability to macromolecules.

Endothelial surface glycocalyx plays an important role in the regulation of microvessel permeability by possibly changing its charge and configuration. To investigate the mechanisms by which surface properties of the endothelial cells control the changes in microvessel permeability, we extended the electrodiffusion model developed by Fu et al. [Am. J. Physiol. 284, H1240-1250 (2003)], which is for the interendothelial cleft with a negatively charged surface glycocalyx layer, to include the filtration due to hydrostatic and oncotic pressures across the microvessel wall as well as the electrical potential across the glycocalyx layer On the basis of the hypotheses proposed by Curry [Microcirculation 1(1): 11-26 (1994)], the predictions from this electrodiffusion-filtration model provide a good agreement with experimental data for permeability of negatively charged a-lactalbumin summarized in Curry [Microcirculation 1(1), 11-26 (1994)] under various conditions. In addition, we applied this new model to describe the transport of negatively charged macromolecules, bovine serum albumin (BSA), across venular microvessels in frog mesentery. According to the model, the convective component of the albumin transport is greatly diminished by the presence of a negatively charged glycocalyx under both normal and increased permeability conditions.

Animals↗
PubMed2004

Glutamate-induced glutamine synthetase expression in retinal Muller cells after short-term ocular hypertension in the rat.

PURPOSE: To determine the effect of intraocular pressure (IOP) elevation on glutamate-induced expression of glutamine synthetase (GS) in retinal Müller cells of rat eyes. METHODS: Six groups of three rats each were studied. Group I was a normal control group. In Group II, one eye received an intravitreal glutamate injection (75 nmoles) while the contralateral eye served as control. In Groups III and IV, IOP was raised in one eye by episcleral vein cauterization. Moderately elevated IOP was maintained for 1 day in Group III or 1 week in Group IV (35 +/- 1.9-45 +/- 5.2 mm Hg). An additional two groups of rats received bilateral intravitreal glutamate injections (75 nmoles) immediately (Group V), or 6 days (Group VI), after induction of IOP elevation in one eye. One day after glutamate injection the rats in all groups were killed, and the eyes enucleated and fixed. Retinas from left and right eyes of each animal were embedded together in LR White resin (Ted Pella, Redding, CA). Sections were processed for GS immunolabeling with antibodies to GS by two-stage immunogold labeling with silver enhancement. Images of labeled retinas from the two eyes were captured under identical light microscopic conditions and the GS immunoreactivity in Müller cells was compared between the left and right retinas in the same section by image analysis. An additional five rats were included in Group II and the retinas were analyzed by Western blot analysis to confirm immunohistochemical findings. RESULTS: Similar to the finding in the control group (Group I), the GS immunoreactivity of the left and right eyes of Group III and IV remained unchanged even though the right eyes in the two groups had elevation of IOP lasting for 24 hours and 1 week, respectively. However, GS levels were significantly increased by 40 +/- 5.7% in normotensive eyes 24 hours after intravitreal injection of glutamate (Group II). The rise in GS immunoreactivity was abolished in eyes with acute IOP elevation (Group V). In contrast, when the eyes were exposed to high IOP for 1 week (Group VI), the glutamate-induced increase in GS immunoreactivity was restored. CONCLUSIONS: Elevated levels of vitreal glutamate can increase the expression of GS in retinal Müller cells. This increase was blocked if IOP was acutely elevated for 24 hours but was restored if IOP remained elevated for 1 week. This finding suggests that moderate elevation of IOP causes only short-term functional changes of glutamate metabolism (amidation) by retinal Müller cells. However, it is not known to what extent endogenous extracellular glutamate can regulate GS expression in normal eyes or in eyes with glaucoma.

Animals↗
PubMed2004

Fluorescence imaging in vivo: raster scanned point-source imaging provides more accurate quantification than broad beam geometries.

Two fluorescence imaging systems were compared for their ability to quantify mean fluorescence intensity from surface-weighted imaging of tissue. A broad beam CCD camera system was compared to a point sampling system that raster scans to create the image. The effects of absorption and scattering in the background tissue volume were shown to be similar in their effect upon the signal, but the effect of the three-dimensional shape of the tissue was shown to be a significant distortion upon the signal. Spherical phantoms with Intralipid and blood for absorber and scatterer were used with a fixed concentration of aluminum phthalocyanine fluorophore to illustrate that the mean intensity observed with the broad beam system increased with size, while the mean intensity observed with the raster scanned system was not as significantly affected. Similar results were observed in vivo with mice injected with the fluorophore and imaged multiple times to observe the pharmacokinetics of the drug. The fluorescence in the tumor observed with the broad beam system was higher than that observed with the raster scanned system. Based upon the phantom and animal observations in this study, it should be concluded that using broad beam fluorescence imaging systems to quantify fluorescence in vivo may be problematic when comparing tissues with different three dimensional characteristics. In particular, the ratio of fluorescence from tumor to normal tissue can yield inaccurate results when the tumor is large. However, similar measurements with a narrow beam system that is raster scanned to create the images are not as significantly affected by the three dimensional shape of the tissue. Raster scanned imaging appears to provide a more uniform and accurate way to quantify fluorescence signals from distributed tissues in vivo.

Animals↗
PubMed2004

Analysis of effective molecular diffusion rates for verteporfin in subcutaneous versus orthotopic Dunning prostate tumors.

Photosensitizer biodistribution change inside tissue is one of the dominant factors in photodynamic therapy efficacy. In this study, the pharmacokinetics of a benzoporphyrin derivative (BPD), delivered in verteporfin for injection formulation, have been quantified in the rat Dunning prostate tumor MAT-LyLu model, using both subcutaneous and orthotopic sites. Blood plasma sampling indicated that BPD had a bi-exponential metabolic lifetime in vivo, with the two lifetimes being 9.6 min and 8.3 h. The spatial distributions in the tumor were quantified as a function of distance from the perfused blood vessels, using fluorescence histologic images of the tumor. A fluorescent vascular marker was used to obtain locations and shapes of perfused capillaries at a wavelength of emission different from that of BPD and to allow colocalized images to be acquired of vessel and BPD locations. Using the BPD fluorescence images obtained 15 min after intravenous administration, a forward finite-element solution to the diffusion equation was used to predict the drug distribution by matching the fluorescence intensity images observed microscopically. An inverse solver was used to minimize the root mean square error between the image of simulated diffusion and the experimental image, resulting in estimation of the diffusion coefficient of BPD in the tumor models. Effective diffusion coefficients were 0.88 and 1.59 microm2/s for the subcutaneous and orthotopically grown tumors, respectively, indicating that orthotopic tumors have significantly higher vascular extravasation rates as compared with subcutaneous tumors. This analysis supports the hypothesis that leakage rates of the photosensitizer vary considerably. Thus, although varying the time between injection and optical irradiation may be used to vary the targeting between vascular and less vascular areas, the precise time of treatment will depend on the nature of the permeability of the vasculature in the tissue being treated.

Animals↗
PubMed2004

[Determination of three formulations of pilocarpine in rabbit ocular aqueous by RP-HPLC].

OBJECTIVE: To develop an RP-HPLC method for assay of pilocarpine in rabbit ocular aqueous humor. METHODS: The RP-HPLC method was performed on a column of ODS-C(18) with the mobile phase consisting of 0.5% of triethylamine (TEA) of phosphate solutions (10 mmol/L, pH 2.5) and acetonitrile (98/2,v/v). The detection wavelength was 215 nm and flow rate was 1.0 ml/min. Ninety albino rabbits were divided into 3 groups (30 in each):group 1 received 50 microl of eye drops containing 1% generic pilocarpine, group 21% mixture pilocarpine solution consisting of aqueous sample and liposome and group 31% liposome pilocarpine, respectively. The aqueous humor was withdrawn at 5, 10, 30, 40, 60, 90, 120, 180, 240 and 360 min. Pilocarpine was extracted from aqueous humor with dichloromethane. RESULT: The linear calibration curve was obtained in the concentration range of 0.1 - 20 microg/ml. The average recovery was (68.1+/-2.7)% (n=9). Inter-day and intra-day RSD were 4.33% and 2.87%, respectively. In three formations 1% liposome pilocarpine was the best for the areas under curve and measurable amounts. CONCLUSION: The RP-HPLC method is simple and reliable for pilocarpine measurement in ocular aqueous. Liposome formulation can significantly increase the bioavailability of pilocarpine in ocular aqueous.

Animals↗
PubMed2004

Perfusion homogeneity of hepatic parenchyma in magnetic resonance imaging during splenoportography.

OBJECTIVE: To evaluate the homogeneity of hepatic parenchyma enhancement in magnetic resonance imaging during splenoportography (MRSP) in the portal phase. METHODS: MRSP was performed in 16 patients suspected of space-occupying lesions in the livers. The signal intensity of non-lesion abnormal perfusion areas and that of peripheral parenchyma were measured in all the scanning phases including unenhanced phase, portographic phase, equilibrium phase, and delayed phase. RESULTS: Perfusion abnormalities were observed in 8 non-lesion foci in the portal phase in 4 cases of hepatic cirrhosis, most frequently appearing in triangle or fan-like shapes (7/8) with unpredictable locations. Hepatic cirrhosis patients had more non-lesion perfusion abnormalities than non-cirrhosis patients. CONCLUSIONS: The presence of non-lesion perfusion abnormalities in MRSP does not affect the diagnosis of the disease, and more homogeneous enhancement of the hepatic parenchyma in the portal phase can be achieved in MRSP than in CT during arterial portography and magnetic resonance imaging during arterial portography.

Adult↗
PubMed2004

[Analysis on the occurrence of violence among the injury surveillance program in the Emergency Department].

OBJECTIVE: To explore the characteristics of violence events occurred at the Emergency Department in the hospital and to provide evidence for prevention and control of the problem. METHODS: Surveillance on injuries was performed on those patients who first visited the Emergency Department in a general hospital in Shantou from January 1st 2000 to December 31th 2002. RESULTS: A total number of 11 472 injured patients registered in a 3-year surveillance program at the Emergency Department. Among the patients under surveillance, 29.0% of them were injured by violence events. The ratio of male to female was 3.8:1. The high risk age groups of violence patients were 15 - 44 years (77.1%) with workers as the majority. Home was the most common place for suicide/self-hurt (occupied 42.2%), and highway seemed to be the most common place for homicide/be injured (occupied 44.7%) to occur. Pre-hospital care for the injured patients was mostly taken care by other people (80.1%). Opening trauma appeared to be the most common injury caused by the violence. CONCLUSION: Our study on violence surveillance program at the Emergency Department provided information for identifying the main problems and population at high risk. Violence surveillance in the emergency department of different areas needs to be carried out in order to take preventive measures accordingly.

Age Factors↗
PubMed2004

[Culture and identification of human and rabbit corpus cavernosum smooth muscle cells].

OBJECTIVE: To investigate an effective method to produce large numbers of pure corporal smooth muscle cells in vitro according to the requirement of study. METHODS: In this study, we used the primary tissue culture technique to isolate and culture the corpus cavernosum smooth muscle cells (CCSM) from human males with normal erectile function and New Zealand white rabbits. The cells were identified in regard to morphological and growing characteristics via immunohistochemical methods (including alpha-smooth muscle actin, desmin, myocin and factor VIII related antigen), special dye techniques (including Masson and Van Gieson) and transmission electron microscope. RESULTS: CCSM were isolated and cultured successfully with high purity. Morphologically, the cells were spindle shaped and grow on top of each other, resembling a "hill and valley" in appearance. When characterized in immunohistochemistry, the cells were stained with alpha-smooth muscle actin, desmin and myocin, but not with anti-factor VIII, an endothelial marker. CONCLUSION: The CCSM, which can be isolated and cultured successfully, may be used for further studying their biological function. The CCSM cultured in vitro was proved to be useful to evaluate and investigate the effect of some new medicine for penile erection. There is also a clinical and theoretical significance in further studying the experimental mechanisms of erectile dysfunction.

Animals↗
PubMed2004

[Correlation between age and average apparent diffusion coefficient in normal-appearing cerebral white matter].

OBJECTIVE: To quantitatively study the effect of ages on the average apparent diffusion coefficient (ADCav) of normal-appearing white matter. METHODS: Fifty patients with normal-appearing white matter were divided into four age groups, namely 16-30 years, (n=13), 31-45 years (n=12), 46-60 years (n=14) and >60 years (n=11). All the subjects were examined with conventional and trace-weighted diffusion imaging in three orthogonal directions. The ADCav of the white matter was measured and compared between various age groups. RESULTS: In the white matter, the ADCav of all the patients was (0.71+/-0.08) x 10(-3) mm2/s; the ADCav of the white matter in the first to fourth age groups were (0.69+/-0.06) x 10(-3) mm2/s, (0.71+/-0.07) x 10(-3) mm2/s, (0.71+/-0.09) x 10(-3) mm2/s, and (0.73+/-0.10) x 10(-3) mm2/s respectively. ADCav of patients between 16-30 years was significantly different from that of patients over 60 years of age (P=0.014). Patients older than 60 years had an ADCav of the white matter significantly higher than the value of (0.70+/-0.07) x 10(-3) mm2)/s in the total patients younger than 60 years (P=0.026). CONCLUSION: Water diffusibility shows a slight increase in human white matter with aging, possibly due to mild ultrastructural changes associated with aging.

Adolescent↗
PubMed2004

[The research on the karyotypes of six species in the genus Eremias from China].

Based on the Giemsa-dyeing karyotypes and silver-staining bands of 15 populations from different localities in China belonging to 6 species of the genus Eremias , We found all species studied have 19 pairs of chromosomes, the size of chromosomes reduces gradually and there are no marked differences between the arranged pairs of macrochromosomes except the last pair of microchromosome. There are the same karyotype formula as 2n=38=36I+2m with NF=38 in E. argus, E. multiocellata, E. velox, E. arguta and E. grammica; but the karyotype formula of E. vermiculata is different as 2n=38=12V+2sI+22I+2m with NF=50. The NOR are all located on one small pair in female of E. velox, and E. arguta , in male of E. grammica and E. vermiculata ,and in both male and female of E. multiocellata. We have not found two or more than two pairs of NOR. Having one pair of NOR may be common in Genus Eremias and also the trait of Eremias. We speculate that the derivation of the karyotype of E. vermiculata had two possible way: one experienced the stage of triploid, and later the Robertsonian transposal of chromosomes; the other way was through the inversions between the arms on the chromosome and the phenomenon of inversions might occur during or subsequently after the upheaval of the Tibet and Qinghai plateau and the founding of the Tianshan . With regard to the trend of the evolution of chromosomes in the lizards ([1]), the karyotype of E. vermiculata is more advanced. Making specialties of E. vermiculata will help in building the phylogenic tree of Eremias. In both male and female of the species studied, the heteromorphic sex-chromosomes were not found.

Animals↗
PubMed2003

Fluorescence losses from Yb:YAG slab lasers.

We report on the distribution of fluorescence that can be emitted through the surfaces of a ytterbium-doped yttrium aluminum garnet (Yb:YAG) slab-shaped high-power solid-state laser. Slab shapes considered include parallel or antiparallel Brewster endfaced slabs and rectangular parallelepiped slabs. We treat cases in which all the faces of these slabs are in air, or with water or another coating on the largest faces. The fraction of the fluorescence emitted through each face, its distribution over that face, and the directions in which it travels are shown to be important to the design of high-power slab lasers.

Journal Article↗
PubMed2003

Hydrogen bonding in water.

Computer simulations using density functional theory based ab initio path integral molecular dynamics have been carried out to investigate hydrogen bonding in water under ambient conditions. Structural predictions for both H2O and D2O, which include the effects of zero-point energy, thermal motion, and many body polarization effects, are contrasted with classical simulations that ignore nuclear quantum effects. The calculated effect of H/D isotope substitution on the water structure is much smaller than the difference between the classical and quantum path integral results, and is in excellent agreement with the measured H/D difference data from both neutron and x-ray scattering.

Journal Article↗
PubMed2003

Paradoxical action of fulvestrant in estradiol-induced regression of tamoxifen-stimulated breast cancer.

BACKGROUND: Long-term tamoxifen treatment of breast cancer can result in tamoxifen-stimulated breast cancer, in which estrogen inhibits tumor growth after tamoxifen withdrawal. We investigated the molecular mechanism(s) of estradiol-induced tumor regression by using an in vivo model of tamoxifen-stimulated human breast cancer. METHODS: Growth of parental estradiol-stimulated MCF-7E2 and long-term tamoxifen-stimulated MCF-7TAMLT xenografts in athymic mice was measured during treatment with vehicle, estradiol, estradiol plus tamoxifen, tamoxifen alone, estradiol plus fulvestrant, or fulvestrant alone. Apoptosis was detected by the terminal deoxynucleotidyltransferase-mediated deoxyuridine triphosphate nick-end labeling (TUNEL) assay. Protein expression was assessed by western blot analysis. mRNA expression was assessed by real-time reverse transcription-polymerase chain reaction. All statistical tests were two-sided. RESULTS: MCF-7E2 tumor growth was stimulated by estradiol (cross-sectional area at week 13 = 1.06 cm2, 95% confidence interval [CI] = 0.82 to 1.30 cm2; P<.001) compared with control (0.06 cm2, 95%CI = -0.02 to 0.14 cm2), but tumor growth was inhibited by tamoxifen or fulvestrant. MCF-7TAMLT tumor growth was stimulated by tamoxifen) cross-sectional area at week 10 = 0.60 cm2, 95% CI = 0.50 to 0.70 cm2; P<.001) compared with control (0.02 cm2, 95% CI = 0.00 to 0.04 cm2). For MCF-7TAMLT tumors that were initially 0.35 cm2, estradiol-induced regression to 0.18 cm2 (95% CI = 0.15 to 0.21 cm2; P<.001), and tamoxifen or estradiol plus fulvestrant enhanced tumor growth to 1.00 cm2 (95% CI = 0.88 to 1.22 cm2). Estradiol increased the number of apoptotic cells in tumors by 23% (95% CI = 20% to 26%; P<.001) compared with all other treatments, decreased estrogen receptor alpha(ERalpha) protein expression, increased the expression of Fas mRNA and protein, decreased the expression of HER2/neu mRNA and protein and nuclear factor kappaB (NF-kappaB) protein but did not affect Fas ligand protein expression compared with control. Paradoxically, fulvestrant reversed this effect and stimulated MCF-7TAMLT tumor growth apparently through ERalpha-mediated regulation of Fas, HER2/neu, and NF-kappaB. CONCLUSION: Physiologic levels of estradiol induced regression of tamoxifen-stimulated breast cancer tumors, apparently by inducing the death receptor Fas and suppressing the antiapoptotic/prosurvival factors NF-kappaB and HER2/neu.

Animals↗
PubMed2003

Apoptotic action of 17beta-estradiol in raloxifene-resistant MCF-7 cells in vitro and in vivo.

BACKGROUND: Resistance to tamoxifen, a selective estrogen receptor modulator (SERM), involves changes that prevent apoptosis and enhance cell proliferation and survival. Paradoxically, estrogen treatment inhibits the growth of long-term tamoxifen-treated breast tumors. Because of the increasing use of raloxifene, another SERM, to prevent osteoporosis and potentially reduce breast cancer risk, some women will develop raloxifene-resistant breast cancer. We developed a raloxifene-resistant MCF-7 cell model (MCF-7/Ral) and investigated the nature of raloxifene-resistant breast cancer and its response to estradiol. METHODS: Raloxifene resistance and hormone responsiveness were assessed by proliferation assays and cell cycle analysis in parental MCF-7 and MCF-7/Ral cells. Nuclear factor kappaB (NF-kappaB) activity was investigated with a transient transfection assay. Apoptosis was investigated by annexin V staining, mRNA was measured by real-time polymerase chain reaction, and protein was measured by western blotting. Tumorigenesis was studied by injecting MCF-7 or MCF-7/Ral cells into ovariectomized athymic mice (10 per group) and monitoring tumor size weekly. All statistical tests were two-sided. RESULTS: Basal NF-kappaB activity was higher in MCF-7/Ral cells (1.6 U, 95% confidence interval [CI] = 1.2 to 2.0 U) than in MCF-7 cells (0.8 U, 95% CI = 0.4 to 1.1 U; P =.004). When cultured with 1 microM raloxifene, MCF-7/Ral cells grew statistically significantly (P<.001) faster than MCF-7 cells. Estradiol treatment of MCF-7/Ral cells arrested cells in G(2)/M phase of the cell cycle, decreased NF-kappaB activity (0.2 U, 95% CI = 0.2 to 0.3 U; P<.001), increased expression of Fas protein and mRNA (4.5-fold, 95% CI = 2.8- to 6.3-fold versus 0.5-fold, 95% CI = 0.3- to 0.8-fold for control treatment; P<.001), and induced apoptosis. Treatment with either raloxifene or tamoxifen stimulated MCF-7/Ral tumor growth, suggesting that such tumors were resistant to both drugs. When a 9-week raloxifene or tamoxifen treatment was followed by a 5-week estradiol treatment, estradiol statistically significantly reduced the size of tumors stimulated by raloxifene or tamoxifen (at week 14, P =.004 for raloxifene and P<.001 for tamoxifen). CONCLUSIONS: Growth of raloxifene-resistant MCF-7/Ral cells in vitro and in vivo is repressed by estradiol treatment by a mechanism involving G2/M-phase arrest, decreased NF-kappaB activity, and increased Fas expression to induce apoptosis.

Animals↗
PubMed2003

[The application of intravascular ultrasound imaging in identifying the visceral artery in aortic dissection].

OBJECTIVE: To study the role of intravascular ultrasound (IVUS) imaging in identifying the visceral artery in aortic dissection. METHODS: Twenty-two patients with aortic dissection were studied by IVUS via a femoral approach. The relationship between the visceral artery origin and the true and false lumens were differentiated by IVUS. The detection rate of visceral artery by IVUS was compared with those of CT and digital subtraction angiography (DSA). The cause of visceral ischemia was determined by the relationship between the intimal flap and the visceral artery origin in IVUS findings, and compared with routine examinations. RESULTS: The outer wall of the true lumen had a three layer structure while that of the false lumen had only one layer structure in IVUS imaging. There was an acute angle between the outer wall of the false lumen and the intimal flap at the true and false lumen junction. The thrombosis in the false lumen could be detected by IVUS. These features can assist in the differentiation of the true and false lumen. The relationship between the visceral artery origin and the true and false lumen could be determined in 81 out of 84 arteries, among which 54 were originated from the true lumen, and 27 from the false lumen. The detecting rate of visceral arteries by IVUS was 96.4%, higher than CT (70.2%) and DSA (84.5%), chi(2) = 20.74 and 6.91, P < 0.01. Static narrowing in 6 arteries and dynamic narrowing in 1 artery were visualized by IVUS, while only 2 static narrowings could be detected by CT. CONCLUSIONS: IVUS has an advantage over routine examinations at detecting visceral artery origin and clarifying the mechanism of visceral ischemia.

Adult↗