Biomedical subjects

Bin Chen

Publications and source records attributed to Bin Chen.

At least 109 records · Page 6Linked to original sources

PubMed2005

The control of phthalocyanine properties through nitro-group electronic effect.

The UV-vis spectra of peripherally substituted tetranitrometallophthalocyanines (TNMPcs) 1a-1d and non-peripherally substituted TNMPcs 2a-2d were investigated. In comparison of 1a with 2a, there is the only difference in the substitution position of nitro-groups. The structural diversity of 1a and 2a resulted in different electronic effects of nitro-group on Pc rings, which caused them have two kinds of Q bands. The Q band in the UV-vis spectra of 1a-1d was split into two peaks, which were obviously influenced by temperature, while no split was observed in the Q band of 2a-2d. We can draw a conclusion that tuning nitro-group electronic effect is an important approach for controlling the properties of Pcs.

Electrochemistry↗

PubMed2005

Endovascular therapy for stanford type B aortic dissection in 102 cases.

OBJECTIVE: To share our experience of 102 cases of endovascular therapy for Stanford type B aortic dissection. METHODS: Multiple imaging diagnostic modalities were used preoperatively to obtain the anatomical parameters of the aortic dissection. Stent grafts were implanted using digital subtraction angiography and intravascular ultrasound guidance. Follow-up computed tomography angiography 1 week and 1 year postoperatively was used to evaluate treatment efficacy and reveal complications such as endoleak, migration and fracture of the stent graft. RESULTS: Clinical success was achieved in 101 cases (99.0%); one patient (1.0%) died within the perioperative period. Neither postoperative paraplegia nor conversion occurred. Endoleak occurred in 18 cases (17.6%). CONCLUSION: Endovascular therapy for Stanford type B aortic dissection is less invasive and leads to less severe complications and shorter hospital stay compared with traditional surgery. The short- and mid-term efficacy are persuasive, but further follow-up is required to determine long-term efficacy.

Adult↗

PubMed2005

Human embryonic stem cell lines derived from the Chinese population.

Six human embryonic stem cell lines were established from surplus blastocysts. The cell lines expressed alkaline phosphatase and molecules typical of primate embryonic stem cells, including Oct-4, Nanog, TDGF1, Sox2, EBAF, Thy-1, FGF4, Rex-1, SSEA-3, SSEA-4, TRA-1-60 and TRA-1-81. Five of the six lines formed embryoid bodies that expressed markers of a variety of cell types; four of them formed teratomas with tissue types representative of all three embryonic germ layers. These human embryonic stem cells are capable of producing clones of undifferentiated morphology, and one of them was propagated to become a subline. Human embryonic stem cell lines from the Chinese population should facilitate stem cell research and may be valuable in studies of population genetics and ecology.

Animals↗

PubMed2005

Characterization of two protein-binding sites in the second intron of the mouse K-ras gene.

A tandem repeat region in the second intron of the K-ras gene has been reported to be a possible regulatory site for transcription. In this study, a second protein-binding site was identified and characterized. It lies downstream (nucleotides 463 to 509) of the tandem repeat region. A T--> C base variation at nucleotide 494 was found in all K(S) strains (which have K-ras alleles identical to those of susceptible A/J strain) and all K(i) strains (which have K-ras alleles identical to those of the intermediate CBA/J strain). DNase I footprint analysis indicated a protein binding site within the downstream repeated region in the second intron of the K-ras gene. Gel mobility-shift studies showed differential protein-binding patterns between the K(r) strains (which have K-ras alleles identical to those of the resistant C3H/HeJ strain) and the K(s) or K(i) strains. Southwestern blot analysis of DNA-protein complexes indicated that the 2 repeated regions might bind the same regulatory complex.

Adenine↗

PubMed2005

Anthraquinones from Gladiolus gandavensis.

Five new anthraquinones have been obtained from the ethanolic extracts of the subterranean corms of Gladiolus gandavensis Van Houtt. Their structures were elucidated as 3,8-dihydroxy-6-methoxy-1-methyl-anthraquinone (gandavensin D, 1), methyl 3,8-dihydroxy-6,7-methylenedioxy-1-methyl-anthraquinone- 2-carboxylate (gandavensin E, 2), 2,3,8-trihydroxy-6-methoxy-1-methoxymethyl-anthraquinone (gandavensin F, 3), 8-hydroxy-3,6-dimethoxy-1-methyl-anthraquinone-2-carboxylic acid (gandavensin G, 4) and 1,7-dihydroxy-3,6-dimethoxy-anthraquinone (gandavensin H, 5) on the basis of spectral data. The known compounds isolated for the first time from this plant have been determined to be methyl 3,6,8-trihydroxy-7-methoxy-1-methyl-anthraquinone-2-carboxylate (6), methyl 3,6,8-trihydroxy-1-methyl-anthraquinone-2-carboxylate (7), 3,8-dihydroxy-6-methoxy-1-methyl-anthraquinone-2-carboxylic acid (8), 3,6,8-trihydroxy-1-methyl-anthraquinone-2-carboxylic acid (9), 6,8-dihydroxy-3-methoxy-1-methyl-anthraquinone-2-carboxylic acid (10), methyl 3,8-dihydroxy-6-methoxy-1-methyl-anthraquinone-2-carboxylate (11) and methyl 3,7,8-trihydroxy-1-methyl-anthraquinone-2-carboxylate (12).

Anthraquinones↗

PubMed2005

Sabian, a novel flavonoid from Sabiayunnanensis.

A novel flavonoid, [2-(3,4-dihydroxy-phenyl)-3,5,7-trihydroxy-4-oxo-4H-chromen-8-yl]-[8-hydroxy-7-(E-4-hydroxy-3-methyl-but-2-enyl)-2,2-dimethyl-chroman-5-yl]-acetic acid methyl ester (10), trivially named sabian, along with 11 known compounds, have been isolated from the stems and leaves of Sabiayunnanensis. Their structures were established on the basis of spectral analysis.

Flavonoids↗

PubMed2005

Developing a sustainable process to provide quality control materials for genetic testing.

PURPOSE: To provide a summary of the outcomes of two working conferences organized by the Centers for Disease Control and Prevention (CDC), to develop recommendations for practical, sustainable mechanisms to make quality control (QC) materials available to the genetic testing community. METHODS: Participants were selected to include experts in genetic testing and molecular diagnostics from professional organizations, government agencies, industry, laboratories, academic institutions, cell repositories, and proficiency testing (PT)/external Quality Assessment (EQA) programs. Current efforts to develop QC materials for genetic tests were reviewed; key issues and areas of need were identified; and workgroups were formed to address each area of need and to formulate recommendations and next steps. RESULTS: Recommendations were developed toward establishing a sustainable process to improve the availability of appropriate QC materials for genetic testing, with an emphasis on molecular genetic testing as an initial step. CONCLUSIONS: Improving the availability of appropriate QC materials is of critical importance for assuring the quality of genetic testing, enhancing performance evaluation and PT/EQA programs, and facilitating new test development. To meet the needs of the rapidly expanding capacity of genetic testing in clinical and public health settings, a comprehensive, coordinated program should be developed. A Genetic Testing Quality Control Materials Program has therefore been established by CDC in March 2005 to serve these needs.

Centers for Disease Control and Prevention, U.S.↗

PubMed2005

Using the frontal branch of the superficial temporal artery as a landmark for locating the course of the temporal branch of the facial nerve during rhytidectomy: an anatomical study.

BACKGROUND: Previous studies have proposed that the frontal branch of the superficial temporal artery could be used to determine the course of the temporal branch of the facial nerve; however, these studies have not documented this relationship. The objective of this study was to thoroughly examine the courses of the frontal branch and temporal branch in the temporal region and to describe their relationship in detail. The operating technique used to avoid damaging the temporal branch in the rhytidectomy also is discussed. METHODS: An anatomical study was performed on 30 temporoparietal regions from 10 fixed adult cadavers and five fresh cadavers. Twenty halves of head-vascular-cast specimens also were observed. RESULTS: Depending on whether the bifurcation point of the superficial temporal artery is superior or inferior to the horizontal line of the superior orbital rim, the frontal branch can be classified as having a high-location or low-location type. The temporal branch and its terminal twigs run deeper into the superficial temporal fascia and are inferior to the frontal branch in the high-location type. In the low-location type, one or more terminal twigs of the temporal branch interweave with the frontal branch above the horizontal plane of the upper orbital rim and terminate below the frontal eminence. The temporal branch locates within a triangular area formed by the lower aspect of the zygomatic arch, the frontal branch, and the vertical line where it crosses the highest point of the frontal eminence CONCLUSION: The frontal branch can be the anatomical landmark used to locate and protect the temporal branch during rhytidectomy.

Dissection↗

PubMed2005

Expression of mRNA for the t-complex polypeptide-1, a subunit of chaperonin CCT, is upregulated in association with increased cold hardiness in Delia antiqua.

Summer-diapause and winter-diapause pupae of the onion maggot, Delia antiqua (Diptera: Anthomyiidae), were significantly more cold hardy than nondiapause, prediapause, and postdiapause pupae. Moreover, cold acclimation of nondiapause pupae conferred strong cold hardiness comparable with that of diapause pupae. Differential display analysis revealed that the expression of a gene encoding TCP-1 (the t-complex polypeptide-1), a subunit of chaperonin CCT, in D antiqua (DaTCP-1) is upregulated in the pupae that express enhanced cold hardiness. Quantitative real-time polymerase chain reaction analyses showed that the levels of DaTCP-1 messenger RNA in pupal tissues, brain, and midgut in particular, are highly correlated with the cold hardiness of the pupae. These findings suggest that the upregulation of DaTCP-1 expression is related to enhanced cold hardiness in D antiqua. The upregulation of CCT in response to low temperature in an organism other than the yeast is newly reported.

Acclimatization↗

PubMed2005

Liposomal delivery of photosensitising agents.

Photodynamic therapy is a clinically approved treatment for cancer and noncancer diseases. This modality utilises light-activatable chemicals (photosensitising agents) to capture photons and use light energy for the production of cytotoxic reactive molecular species. Most photosensitisers that are in use clinically or in preclinical development are hydrophobic and tend to aggregate in the aqueous environment, which limits their delivery and photosensitising efficiency. Liposomal delivery of photosensitisers will often overcome or decrease these problems. In addition, as with chemotherapeutic agents, liposomal formulations of photo-sensitising agents may help to achieve better selectivity for tumour tissue compared with normal tissue. Over the past years, liposomal photosensitisers have emerged as therapeutic agents in many experimental studies, and have obtained approval for clinical applications. Recent progress in liposomal technology further opens up the possibility of generating more selectively targeted photosensitisers encapsulated in liposomes. This review will cover progress in the use of liposomal photosensitisers, summarise current liposomal formulations, and project future directions for the liposomal delivery of photosensitising agents.

Biological Availability↗

PubMed2005

The effect of hepatic blood inflow occlusion on hepatic cancer treated with diode-laser thermocoagulation.

OBJECTIVE: To assess the effect of temporary occlusion of hepatic blood inflow on hepatic cancer treated with diode-laser induced thermocogation (LITT). METHODS: The carcinoma Walker-256 was implanted in 40 SD rat livers. Twelve days later, the animals were randomly divided into 4 groups. Group A received LITT alone; group B received hepatic artery temporary occlusion during LITT; group C received portal vein temporary occlusion during LITT; group D received hepatic artery and portal vein temporary occlusion during LITT. Tumors were exposed to 810 nm diode-laser light at 0.95 watts for 10 min from a scanner tip applicator placed in the tumor. At the same time, the intrahepatic temperature distribution in rats with liver tumors was measured per 2 min during thermocoagulation. Tumor control was examined immediately 7 and 14 d after thermocoagulation. RESULTS: There was significant difference of intrahepatic temperature distribution in rats with liver tumors among the 4 groups (P<0.05) except when group C samples were compared with group D samples at each time point, and group B samples were compared with group C samples at 120 s (P>0.05). Light microscopic examination of the histologic section samples revealed three separate zones: regular hyperthermic coagulation necrosis zone, transition zone and reference zone. Compared with the samples in group A and group B, group C and group D samples had more clear margin among the three zones. CONCLUSION: The hepatic blood inflow occlusion, especially portal vein hepatic blood inflow occlusion, or all hepatic blood inflow occlusion considerably increased the efficacy of LITT in the treatment of liver cancer.

Animals↗

PubMed2005

Novel HDAC inhibitors with radiosensitizing properties.

The members of the histone deacetylase (HDAC) family play important roles in various cellular processes, including transcriptional regulation, cell proliferation, differentiation and apoptosis. Inhibitors of histone deacetylases are emerging as an important new class of chemotherapeutic agents. As such, identifying stable and potent chemical HDAC inhibitory compounds is an important focus for translational research. Here we report the results of a rational drug design of novel HDAC inhibitors with potential for sensitizing cancer cells to radiation therapy. Over 60 HDAC inhibitor analogues incorporating a urea backbone and the hydroxamic acid end moiety were designed and screened. Six were found to confer 50% inhibition of HDAC enzyme activity at nanomolar concentrations. These candidate HDAC inhibitors inhibited cell proliferation at the ranges of IC50 10-50 microM in various cancer cells, including prostate (PC-3), breast (MCF-7) and head and neck squamous carcinoma (SQ-20B). Furthermore, radiation clonogenic survival assays revealed that these compounds possess radiosensitizing properties that are cell type-specific. The data support the further investigation of these HDAC inhibitors for use as sensitizing agents with potential for clinical application.

Cell Line, Tumor↗

PubMed2005

[Optical, scanning electron and atomic force microscopic observation of the microstructure of human humeral bone].

OBJECTIVE: To observe the microstructure of human long bone with scanning electron and atomic force microscopes to understand the ultrastructural organization and the composition and the morphology of the bone collagen and minerals. METHOD: Fresh human cadaveric humeral bone were fixed and dehydrated to prepare the ground sections and thin slices, respectively, which were observed for bone microstructure using optical, scanning electron and atomic force microscopy, respectively. RESULTS: Under optical microscope, the bone lacunae were in circular permutation around the Haversian canal, and the canaliculi communicated the lacunae and Haversian canal or between the lacunae. Atomic force microscopy represented distinct morphology of the large clusters of collagen, and the collagen fibers thickened in the mineralized zone and appeared in the shape of overlapping discs, whereas the calcium-phosphorus crystal displayed ellipse cylinders. The size, shape and relation of the canaliculi and lacunae were observed clearly. The bone matrix was observed in circular arrangement along the Haversian canal and the calcium-phosphorus crystal was in regular alignment under scanning electron microscope. CONCLUSION: Atomic force microscopy can help analyze the three-dimensional configuration of calcium-phosphorus crystal and bone collagen as well as the canaliculi and lacuna. The canaliculi serve as the channels mediating alimentation and molecular signals into the lacuna.

Collagen↗

PubMed2005

[The molecular mechanisms of the effects of murine interferon-gamma transgenic expression on allergen-induced allergic model via adenoviral vector].

OBJECTIVE: To investigate adenoviral vector mediated murine interferon-gamma (mIFN-gamma) transgene expression and its effect on allergen-induced airway inflammation and multiple interleukin (IL) cytokines (IL-4, IL-5, IL-6, IL-10, IL-12, IL-13 and IL-18) expression in a murine allergic model. METHODS: Forty-eight mice were divided into 7 groups by random digits table: a negative control group (A), allergic model groups I, II, III (B, D, F), gene therapy groups I, II, III (C, E, G). Except for group A, mice of the other groups were peritoneally sensitized with ovalbumin (OVA, 15 microg/mouse) twice on day 0 and day 5, and challenged by inhalation of 0.5% OVA (20 ml per time) twice per day from day 12 to 14. On day 15, AdCMVmIFN-gamma (5 x 10(9) PFU/mouse) solution 50 microl was administrated by nasal drip in groups C, E and G. For groups A, B, D and F, 0.9% NaCl 50 microl was administrated by nasal drip. Groups A, B and C were sacrificed on day 18. Groups D and E were sacrificed on day 21. Groups F and G were sacrificed on day 25. The concentration of mIFN-gamma in bronchioalveolar lavage (BALF) was measured by enzyme-linked immunosorbant assay. Accumulation of inflammatory cells and eosinophils (EOS) were quantified by cell count and histopathological analysis. Multi-cytokine expression was tested by semi-quantitative reverse transcription polymerase chain reaction (RT-PCR). RESULTS: (1) mIFN-gamma was efficiently expressed after gene therapy. The concentration of mIFN-gamma in BALF was (729.0 +/- 104.7) pg/ml 3 days after gene therapy (group C); it was (984.5 +/- 119.1) pg/ml after 6 days (group E); and (310.6 +/- 59.7) pg/ml after 10 days (group G). (2) The total cell number in BALF of group B and C was (318 +/- 41) x 10(3)/ml and (137 +/- 12) x 10(3)/ml, respectively (P < 0.01); the constituent ratio of EOS in BALF was 0.715 +/- 0.054 and 0.452 +/- 0.016, respectively (P < 0.01). The total cell number in BALF of group D and E was (183 +/- 23) x 10(3)/ml and (92 +/- 6) x 10(3)/ml, respectively (P < 0.01); the constituent ratio of EOS was 0.393 +/- 0.065 and 0.083 +/- 0.038, respectively (P < 0.01). The total cell number in BALF of groups F and G was (196 +/- 7) x 10(3)/ml and (98 +/- 15) x 10(3)/ml, respectively (P < 0.01); the constituent ratio of EOS was 0.253 +/- 0.035 and 0.068 +/- 0.025, respectively (P < 0.01). (3) The histopathological results showed that in the gene therapy groups, the infiltration of inflammatory cells was markedly reduced and the damage of airway epithelium was alleviated. (4) For group D and E, the ratio of IL-10 mRNA abundance to that of home gene was 0.14 +/- 0.10 and 0.49 +/- 0.27, respectively (P < 0.01); that of IL-12 was 0.15 +/- 0.05 and 0.63 +/- 0.17, respectively (P < 0.01); that of IL-13 was 0.76 +/- 0.17 and 0.37 +/- 0.10, respectively (P < 0.01). For group F and G, the ratio of IL-10 mRNA abundance to that of home gene was 0.13 +/- 0.04 and 0.27 +/- 0.17, respectively (P = 0.019); that of IL-12 was 0.14 +/- 0.05 and 0.35 +/- 0.21, respectively (P = 0.006); that of IL-13 was 0.57 +/- 0.24 and 0.30 +/- 0.09, respectively (P = 0.003). However, there were no statistically significant changes in IL-4, IL-5, IL-6, and IL-18 in lung tissue between allergic model groups (B, D, F) and gene therapy groups (C, E, G, P > 0.05). CONCLUSIONS: (1) mIFN-gamma gene transferred via adenoviral vector could abrogate the infiltration of EOS in OVA-induced allergic model. (2) The molecular mechanisms for effect by AdCMVmIFN-gamma transgenic therapy on murine allergic model involve the indirect action by the upregulation of IL-10 and IL-12 expression and the downregulation of IL-13 expression locally in the lungs, in addition to the direct effects of locally overexpressed mIFN-gamma.

Adenoviridae↗

PubMed2005

Anthropogenic impacts on the biogeochemistry and cycling of antimony.

Antimony is a potentially toxic trace element with no known biological function. Antimony is commonly enriched in coals, and fossil fuel combustion appears to be the largest single source of anthropogenic Sb to the global atmosphere. Abundant in sulfide minerals, its emission to the atmosphere from anthropogenic activities is linked to the mining and metallurgy of non-ferrous metals, especially Pb, Cu, and Zn. In particular, the geochemical and mineralogical association of Sb with Pb minerals implies that, like Pb, Sb has been emitted to the environment for thousands of years because of Pb mining, smelting, and refining. In the US alone, there are more than 400 former secondary lead smelting operations and worldwide there are 133 Pb-Zn smelters in operation today. Antimony is used in creating and improving dozens of industrial and commercial materials including various alloys, ceramics, glasses, plastics, and synthetic fabrics, making waste incineration another important source of Sb to the environment. Enrichments of Sb in atmospheric aerosols, plants, soils, sediments, as well as alpine and polar snow and ice suggest that Sb contamination is extensive, but there are very few quantitative studies of the geographic extent, intensity, and chronology of this contamination. There is an urgent need to quantify the extent of human impacts and how these have changed with time. The decreasing inventories of anthropogenic Sb with time in peat cores from Switzerland and Scotland suggest that the atmospheric Sb flux may be declining, but there have been too few studies to make any general conclusions. In fact, some studies of sediments and biomonitors in central Europe show little decline in Sb concentrations during the past decades. There is an obvious need for reliable data from well dated archives such as polar snow and ice, peat bogs, and sediments. The air concentrations, extent of enrichment, particle size distribution, and rate of deposition of Sb in urban areas is cause for concern. The natural processes which controlled the Sb flux to the atmosphere in the pre-anthropogenic past are poorly understood. The cumulative amount of anthropogenic Sb in soils has not yet been quantified. The long-term fate of Sb in soils, including weathering and mobilization, has only started to be investigated. However, the limited data available suggests that, in some locations at least, anthropogenic Sb in soils may be more mobile than anthropogenic Pb. Further study of this problem is needed, as well as the chemical speciation of Sb in soil-water-plant-sediment systems, and the implications which this has for human and ecosystem health.

Air Pollutants↗

PubMed2005

Potential of endogenous estrogen receptor beta to influence the selective ER modulator ERbeta complex.

The ratio of estrogen receptor beta (ERbeta) to ERalpha can alter the estrogen-like properties of tamoxifen. Transient transfection of ERbeta cDNA into cells can decrease the estrogen-like properties of the ERalpha:tamoxifen complex, whereas an increase in the amount of ERbeta is associated with tamoxifen-resistant breast cancer. We have addressed each of these hypotheses by examining well characterized laboratory models. We determined whether changes in endogenous ERbeta are responsible for the estrogen-like or antiestrogenic properties of tamoxifen or raloxifene in MDA-MB-231 cells transfected with cDNAs for ERalpha or mutants D351G, D351Y. We found that the amount of ERbeta mRNA in separate, stable transfectants of mutant ERalpha cDNA was always < 2% of ERalpha. Since at least a 50:50 mixture of ERalpha:ERbeta is needed to silence the tamoxifen:ERalpha complex, we conclude that insufficient ERbeta mRNA is available for selective ER modulation in stable transfectants of D351G and D351Y ERalpha. Similarly, to test the hypothesis that ERbeta is up-regulated and plays an important role during the development of tamoxifen-stimulated tumor growth, we quantitatively analyzed ERbeta and ERalpha mRNA in tamoxifen-naïve (MCF-7:E2, ECC1:E2) and tamoxifen-stimulated tumors (MCF-7:TAM, EnCa 101:TAM). We found that ERbeta mRNA levels were not significantly elevated in tamoxifen-stimulated tumors and the ERalpha mRNA remained over 99% out of all ER species for all the tumors tested. The same results were also obtained when mRNA levels of ERbeta and ERalpha in a series of tamoxifen-naïve and tamoxifen-resistant breast cancer was analyzed. We conclude that endogenous ERbeta may not play a dominant role in the modulation of the tamoxifen ERalpha complex, or in the development of tamoxifen-stimulated resistant tumor growth.

Animals↗

PubMed2005

[Expression of Survivin and Bcl-2 in laryngeal squamous cell carcinoma and their significance].

OBJECTIVE: To research the expression of Survivin and Bcl-2 protein in laryngeal squamous cell carcinoma (LSCC) and the correlation between them. METHOD: Immunohistochemical (SP) method was used to detect the expression of Survivin and Bcl-2 in 64 cases of LSCC, 28 cases of normal laryngeal mucous membrane and 20 cases of laryngeal benign lesion. The relationship among them was studied by statistical analysis. RESULT: Survivin protein was expressed in 43 of 64 (67.2%) samples of LSCC, just 2 samples was expressed in laryngeal benign lesion (10%) and 1 sample expressed in normal laryngeal mucosa (3.6%). The over expression of Survivin was related to the tumor's location, clinical stage, histological grade, lymphatic metastasis. The expression of Survivin was correlated with the expression of Bcl-2. CONCLUSION: Survivin may play an important role in the pathway of carcinogenesis, progress and metastasis of LSCC,it is feasible for early diagnosis and precaution. Bcl-2 and Survivin may play synergetic roles in the pathogenesis of LSCC.

Adult↗

PubMed2005

[Update of PDE5 inhibitors as treatment of ED].

Erectile dysfunction is a common ailment in middle-aged and old men. The management of ED has entered a new stage since sildenafil was used to treat ED in 1998. Sildenafil became the first-line treatment for its efficacy and safety. In recent years, new PDE5 inhibitors--vardenafil and tadalafil came into market in succession, providing more options available for oral therapy. This review is about the development of preclinical and clinical medicine research on the three PDE5 inhibitors, and provide information for clinical choices.

Erectile Dysfunction↗