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Biomedical subjects

Bing Zhao

Publications and source records attributed to Bing Zhao.

At least 55 records · Page 3Linked to original sources
PubMed2004

Ultraviolet-visible and surface-enhanced Raman scattering spectroscopy studies on self-assembled metalloporphyrin films on organic monolayer-modified ultra-thin silver substrates.

A self-assembled monolayer (SAM) film of 5,10,15,20-tetra-(para-chlorophenyl)-porphyrin terbium (or lutetium) hydroxy compound (TbOH/LuOH) fabricated on a silver substrate premodified with a SAM of 4-mercaptopyridine (PySH) was studied by ultraviolet-visible (UV-Vis) spectroscopy and surface-enhanced Raman scattering (SERS) spectroscopy. PySH can modify the substrate and deliver its pyridyl group pointing out from the silver surface. Thus, we can investigate the effects of the central metals of the metalloporphyrins in the formation of the composite films. For the TbOH-PySH composite film, a new absorption band arising from TbOH appears at 425 nm, and a band at 512 nm due to the PySH-modified silver substrate shifts to a longer wavelength (538 nm). The results suggest that TbOH is successfully assembled on the top of PySH-modified silver film and that there is an interaction between TbOH and PySH in the film. The frequency shifts and relative intensity changes of bands due to PySH in the SERS spectra imply the coordination of the pyridyl group on Tb in the SAM. As for the LuOH-PySH composite film, its SERS spectrum shows bands arising from both the LuOH and PySH moieties, indicating that LuOH is assembled on the PySH-modified silver film. Furthermore, a band at 1221 cm(-1) due to the in-plane C-H bending mode of PySH disappears, implying that the pyridyl moiety of PySH becomes more parallel to the silver surface upon the formation of the LuOH-PySH composite film. Additionally, an absorption band at 515 nm shifts to a longer wavelength (541 nm) and becomes broad upon the formation of the composite film, suggesting an interaction between LuOH and PySH in the film. By comparing the spectral changes between the two self-assembled composite films, we find that the central metal is crucial in the formation of the composite films. The structure and orientation of the composite films depend on the central metal of the metalloporphyrin compounds.

Journal Article↗
PubMed2004

Ultrasensitive detection of 1,4-Bis(4-vinylpyridyl)phenylene in a small volume of low refractive index liquid by surface-enhanced Raman scattering-active light waveguide.

This paper reports a novel surface-enhanced Raman scattering (SERS)-active light waveguide method for ultrasensitive detection of a sample dissolved in a small volume of low refractive index liquid. The SERS-active light waveguide demonstrated in this study was constructed via the light-guiding silica capillary. The surface of its inner wall was modified with SERS-active silver nanoparticles that can remarkably enhance Raman signals. The capillary with SERS-active modified layer was filled with the sample solution to form the SERS-active liquid core (LC) fiber. The incident laser beam travels through the waveguide in a totally reflective mode within the fiber wall and penetrates a small distance into the sample solution by the evanescent wave field. The Raman scattering of the analytes adsorbed onto the surface of the SERS-active modified layer can be excited by the laser beam and refracted into the fiber wall. Thus, a sample dissolved in low index liquid, e.g., methanol, can be quantitatively monitored by Raman spectroscopy and detection limit of its concentration is lower than 10(-9) mol/L.

Light↗
PubMed2004

[The effects of feeding methods on deciduous caries.].

PURPOSE: The goal of this study was to explore the relationship between feeding methods and deciduous caries. METHODS: An investigation on children's feeding methods, caries prevalence and dmft was made, using 260 cases which were provided with whole primary teeth. Chi-square test was used for statistical analysis on feeding methods and caries prevalence, and variance analysis was used on feeding methods and dmft. RESULTS: The results showed that the deciduous caries rate, mean dmft in breast feeding (BF) group were lower than those in mixed feeding (MF) group and artificial feeding (AF) group, there were significant differences between BF group and MF group,also between BF group and AF group. But there were no significant differences between MF group and AF group. CONCLUSION: It is concluded that proper breast feeding seems to be important for preventing deciduous caries.

Age Factors↗
PubMed2003

Immunoassay using probe-labelling immunogold nanoparticles with silver staining enhancement via surface-enhanced Raman scattering.

This paper reports a novel immunoassay based on surface-enhanced Raman scattering (SERS) and immunogold labelling with silver staining enhancement. Immunoreactions between immunogold colloids modified by a Raman-active probe molecule (e.g., 4-mercaptobenzoic acid) and antigens, which were captured by antibody-assembled chips such as silicon or quartz, were detected via SERS signals of Raman-active probe molecule. All the self-assembled steps were subjected to the measurements of ultraviolet-visible (UV-vis) spectra to monitor the formation of a sandwich structure onto a substrate. The immunoassay was performed by a sandwich structure consisting of three layers. The first layer was composed of immobilized antibody molecules of mouse polyclonal antibody against Hepatitis B virus surface antigen (PAb) on a silicon or quartz substrate. The second layer was the complementary Hepatitis B virus surface antigen (Antigen) molecules captured by PAb on the substrate. The third layer was composed of the probe-labelling immunogold nanoparticles, which were modified by mouse monoclonal antibody against Hepatitis B virus surface antigen (MAb) and 4-mercaptobenzoic acid (MBA) as the Raman-active probe on the surface of gold colloids. After silver staining enhancement, the antigen is identified by a SERS spectrum of MBA. A working curve of the intensity of a SERS signal at 1585 cm(-1) due to the [small nu](8a) aromatic ring vibration of MBA versus the concentration of analyte (Antigen) was obtained and the non-optimized detection limit for the Hepatitis B virus surface antigen was found to be as low as 0.5 [micro sign]g mL(-1).

Animals↗
PubMed2003

Effects of rare earth elements on the growth of Cistanche deserticola cells and the production of phenylethanoid glycosides.

The rare earth elements Nd, La, Ce at proper concentrations had positive effects on the cell growth of Cistanche deserticola and production of phenylethanoid glycosides (PeG). A mixture of rare earth elements (MRE, La(2)O(3):CeO(2):Pr(6)O(11):Sm(2)O(3)=255:175:3:1, mol/mol) showed the most remarkable effects. After 30 day's culture, 0.02 mmoll(-1) MRE gave the highest content (20.8%) and production (1.6 gl(-1)) of PeG, which were 104 and 167% higher than those obtained in control (without rare earth elements).

Cell Culture Techniques↗
PubMed2003

Comparison of molecular orientation and phase transition behaviors in the two kinds of ordered ultrathin films of reversed duckweed polymer ES-3 studied by infrared grazing reflection-absorption spectroscopy.

A multilayer LB film and a casting film of reversed duckweed polymer ES-3 on Au-evaporated glass slides were investigated by Fourier Transform infrared grazing reflection-absorption spectroscopy. It is found that the two kinds of ordered ultrathin films have different orientation of alkyl chains, nearly perpendicular to the substrate surface for the LB film while rather tilted for the casting film. The studies on their thermal transition behaviors indicate that both of the films have three phase transition processes, respectively, occurring near 65, 105 and 140 degrees C for the former while near 80, 105 and 140 degrees C for the latter, but show different transition behavior in the each corresponding transition process. It is referred that at room temperature there are island-like domain structures formed in the LB film, but no ones in the casting film; however, the latter can form the domain structures between the first two transition points due to the desorption of solvents. The formation of domain structure seems to play two important roles, one of which is to make alkyl chains more perpendicular to the substrate surface, and the other to make alkyl chains more packed closely. Thermal cyclic experiments reveal that neither of the films could return to its original state after thermal cyclic treatment up to the temperature, which is above the third transition point, although its alkyl chain becomes highly ordered again.

Polymers↗
PubMed2003

A novel MHCp binding prediction model.

Many statistical and molecular mechanics models have been developed and tested for major histocompatibility complex peptide (MHCp) binding predictions during the last decade. The statistical model prediction using pooled peptide sequence data and three-dimensional modeling prediction by molecular mechanics calculations have been assessed for efficiency and human leukocyte antigen diversity coverage. We describe a novel predictive model using information gleaned from 29 human MHCp crystal structures. The validation for the new model is performed using four different sets of data: (1) MHCp crystal structures, (2) peptides with known IC(50) binding values, (3) peptides tested positive by tetramer staining, (4) peptides with known binding information at the MHCBN database. The model produces high prediction efficiencies (average 60 %) with good sensitivity (approximately 50%-73%) and specificity (52%-58%) values. The average positive predictive value of the model is 89%, while the average negative predictive value is only 18%. The efficiency is very high in predicting binders and very low in predicting nonbinders. This model is superior to many existing methods because of its potential application to any given MHC allele whose sequence is clearly defined.

Amino Acid Sequence↗
PubMed2003

Compression of functional space in HLA-A sequence diversity.

The major histocompatibility complex (MHC) is highly polymorphic and more than 1500 human MHC alleles are known to date. These alleles do not bind to a given peptide with identical affinity. Although MHC alleles are functionally related, it is difficult to quantify the functional variation between them. Three-dimensional structures of known MHC-peptide (MHCp) complexes suggest that specific peptide residues bind selectively to functional pockets in the binding groove. From a set of known MHCp structures we identified 21 critical polymorphic functional residue positions (CPFRP) that significantly reduced functional pocket variability to just 189 among 212 HLA-A alleles. Interestingly 101 HLA-A alleles clustered into 29 clusters such that the six functional pockets formed by the CPFRPs are identical within the cluster.

Alleles↗
PubMed2003

Raman spectroscopic investigation of the single-monolayer Langmuir-Blodgett film of C16NaphOH and C10AzoNaphC4N-SDS.

Raman spectra were measured for Langmuir-Blodgett (LB) films of C(16)NaphOH and C(10)AzoNaphC(4)N-SDS on Calcium Fluorite substrate for the first time. In order to find out favorable excitation condition, Raman spectra of the single and multi-monolayer LB films excited at different lines at 244, 514, 633 and 778 nm are recorded and compared in the present study. Raman spectrum of the monolayer LB film of C(16)NaphOH excited by 244 nm demonstrate that excellent signal to noise is achieved even for one monolayer LB film with an extremely short integrating time as 60 s because of being resonantly enhanced, while no meaningful spectra were recorded under the same condition for the monolayer LB film of C(10)AzoNaphC(4)N-SDS because of burning. Using a HeNe 633 nm excitation the problem with strong substrate fluorescence was partially solved, since under these conditions this fluorescence is mainly outside the fingerprint region of the LB film molecules (1000-2000 cm(-1)). Therefore by using the HeNe laser excitation, Raman spectra with high signal to noise ratio of LB films of C(16)NaphOH were collected and shown in this paper. These findings stress again the necessity to define an appropriate Raman system for this special application of LB film diagnosis.

Alkanes↗
PubMed2003

Optimization of cryopreservation of Artemisia annua L. callus.

Cryopreservation of callus tissue of Artimisia annua L. was optimized. Two lines of calli were precultured on MS medium with 5% (v/v) dimethyl sulfoxide, and protected by a cryoprotectant containing 15% (v/v) ethylene glycol, 15% (v/v) dimethyl sulfoxide, 30% (v/v) glycerol and 13.6% (w/v) sucrose. The highest survival rate of callus A201 reached 87% after it was pretreated at 25 degrees C, cryopreserved by liquid nitrogen, recovered in water bath at 25 degrees C and reloaded at 25 degrees C with 34% (w/v) sucrose solution, and that of callus A202 reached 78% after it was treated as callus A201, except pretreated at 35 degrees C, recovered at 35 degrees C and reloaded with 47.8% (w/v) sucrose solution.

Artemisia annua↗
PubMed2003

Formation of phenylethanoid glycosides by Cistanche deserticola callus grown on solid media.

The optimal growth of Cistanche deserticola callus and formation of phenylethanoid glycosides (PeG) was at 25 degrees C with light irradiation intensity of 24 micromol m(-2) s(-1) on solidified B5 media supplemented with 0.5 mg 6-benzylaminopurine l(-1), 10 mg gibberellin l(-1), 800 mg casein hydrolysate l(-1) and 20 g sucrose l(-1). After 30 d culture, the biomass reached 15.5 g dry wt callus l(-1) medium and its PEG content was 10.7% (w/w). The PeG content was 42%-127% higher than those in explants.

Caseins↗
PubMed2003

Production of crocin using Crocus sativus callus by two-stage culture system.

Saffron callus was grown in a two-stage culture on B5 medium supplemented with casein hydrolysate (300 mg l(-1)) at 22 degrees C in dark with naphthalene acetic acid (2 mg l(-1)) and 6-benzyladenine (1 mg l(-1)) to give maximum biomass (16 g dry wt l(-1)), and with indole 3-acetic acid (2 mg l(-1)) and 6-benzyladenine (0.5 mg l(-1)) for crocin formation. The maximum crocin production (0.43 g l(-1)) was achieved by this two-stage culture method, which was three times that by a one-stage method.

Bioreactors↗
PubMed2003

Effect of caffeic acid phenethyl ester on proliferation and apoptosis of hepatic stellate cells in vitro.

AIM: To investigate the role of nuclear factor-kappaB (NF-kappaB) inhibitor caffeic acid phenethy1 ester (CAPE) in the proliferation, collagen synthesis and apoptosis of hepatic stellate cells (HSCs) of rats. METHODS: The HSCs from rats were isolated and cultured in Dulbecco's Modified Eagle's Medium (DMEM) and treated with CAPE. The proliferation and collagen synthesis of HSCs were determined by (3)H-TdR and (3)H-proline incorporation respectively, and the expression of type I, III procollagen genes was further explored by in situ hybridization. Apoptosis cell indices (AIs) were examined using terminal deoxynucleotidyl transferase- mediated DIG-dUTP nick end labeling (TUNEL). RESULTS: In activated HSC in culture, CAPE significantly inhibited (3)H-TdR and (3)H-proline incorporation by HSCs at concentrations of 5 micromol/L and 10 micromol/L respectively. CAPE also reduced the type I procollagen gene expression (P<0.05) at higher concentration. Apoptosis of HSC was induced by CAPE and the AIs were time-and dose-dependently increased from 2.82+/-0.73 % to 7.66+/-1.25 % at 12 h (P<0.01) and from 3.15+/-0.88 % to 10.61+/-2.88 % at 24 h (P<0.01). CONCLUSION: CAPE inhibits proliferation and collagen synthesis of HSC at lower concentration and induces HSC apoptosis at higher concentration.

Animals↗
PubMed2003

[DNA fingerprinting of Mycobacterium tuberculosis strains from Beijing, Guangdong and Ningxia].

OBJECTIVE: To explore the epidemic distribution of Mycobacterium tuberculosis isolates from Beijing, Guangdong and Ningxia, and to determine M. tuberculosis strains of the "Beijing Family". METHODS: Two hundred and six IS6110 DNA fingerprinting patterns of M. tuberculosis strains from three provinces (city) were transferred to digital data, compared with the world M. tuberculosis DNA fingerprinting database, and then clustered by Gel compare 4.1 software. The clustering values in different patients with tuberculosis were compared by chi(2) test. Risk factors for recent transmission were calculated using odd ratios. RESULTS: No M. tuberculosis strains were found the same as those of DNA fingerprint database. 56.8% (117/206) fingerprinting patterns of M. tuberculosis shared by least two-thirds of the IS6110 fragments and their Spoligotyping fingerprinting patterns were consistent with those of M.tuberculosis strains of the "Beijing Family". There were significant differences between female and male, different age groups (< 42 years old) and older (>or= 42 years old) (P < 0.05). Odd ratio was 5.06 in the group younger than 42 years old (95% CI: 1.00 - 34.34) and was 4.43 (95% CI: 0.94 - 28.76) in males. CONCLUSION: M. tuberculosis strains of "Beijing Family" were popular in Beijing, Guangdong and Ningxia. Men and younger age group (< 42) were shown to be infected by identical strains more often than women and older aged which might play an important role in the recent transmission of tuberculosis in these areas. IS6110 DNA fingerprinting of M. tuberculosis could be used to trace the source of tuberculosis infection.

Adult↗
PubMed2002

Thin films of Ag nanoparticles prepared from the reduction of AgI nanoparticles in self-assembled films.

A novel method for the preparation of thin films of Ag nanoparticles is reported. Using mercaptoacetic acid as the stabilizing agent, AgI nanoparticles were prepared in aqueous solution. And based on electrostatic interactions, the thiol-passivated AgI nanoparticles were assembled in a self-assembled film by alternative deposition with a cationic polyelectrolyte. Then the AgI nanoparticles in the composite film were reduced by NaBH(4), which resulted in the formation of a thin film of Ag nanoparticles. UV-visible spectra and X-ray photoelectron spectroscopy data confirmed the transformation from AgI to Ag. Atomic force microscopy (AFM) showed that the formed Ag nanoparticles distributed on the film homogeneously. Surface-enhanced Raman spectroscopy (SERS) measurement indicated that the prepared thin films could be used as effective SERS substrates. The reduction process was also carried out by UV light at selective surface regions, which resulted in the formation of patterned nanoparticle arrays.

Journal Article↗
PubMed2002

Sculpting the visual map: the distribution and function of serotonin-1A and serotonin-1B receptors in the optic tectum of the frog.

Agonists of serotonin (5-HT)-1 receptors modulate the synaptic strength of the connection between retinal ganglion cells and neurons of the frog optic tectum in brain slices (Brain Res. 1998;781:167-181). We have now used autoradiographic receptor binding techniques to determine the location of 5-HT1A and 5-HT1B binding sites in the laminated optic tectum. 5-HT1A binding sites, as labeled with [3H]8-hydroxy-dipropylaminotetralin (8-OH-DPAT), were highest in the superficial, retinorecipient layers of the tectum, intermediate in layers 6 and 7 and low in the remaining layers. Binding densities in all of these layers were unaffected by optic nerve lesion. 5-HT1B binding sites were visualized using [125I]iodocyanopindolol (ICYP). Binding densities were highest in the plexiform layers 5 and 7 and intermediate in layers 6 and 8. Binding sites were present at low levels in layer 9; however, optic nerve lesion resulted in a strong upregulation of these sites in this layer. Pharmacological manipulation of receptor activation resulted in changes in the activity-dependent visual map that is created at the tectum by retinal ganglion cell terminals. Chronic treatment of the tectum with SB-224289, a selective antagonist of 5-HT1B receptors, disrupted the topographic map. In contrast, exposure to WAY-100635, a selective antagonist of 5-HT1A receptors, refined it. We conclude that both 5-HT1A and 5-HT1B receptors are present in the adult frog tectum and that changes in their activation levels can produce changes in retinotectal transmission levels that drive visual plasticity in opposite directions.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed2002

Surface-enhanced Raman spectroscopy study on the structure changes of 4-mercaptopyridine adsorbed on silver substrates and silver colloids.

Surface-enhanced Raman scattering (SERS) of 4-mercaptopyridine (4-mpy) adsorbed on HNO3 etched silver foil, chemically deposited silver films (silver mirror) and silver colloids were measured. The SERS study has revealed that 4-mpy was adsorbed onto the three kinds of silver surfaces by a sulfur-silver bond with the plane of pyridine ring being normal to the silver substrates. The structure of 4-mpy adsorbed on the silver surfaces depends largely on the pH values of environment. When the pH values of the environment are changed, the structure of 4-mpy adsorbed on silver surfaces can easily be altered through a protonation or deprotonation reaction occurring on the N atom of the pyridine ring, and the modified structure shows unique characters on the SERS spectrum. Owing to the remarkable enhancement ability of SERS technique and characteristic spectrum of different species, a monolayer of 4-mpy assembled on a silver mirror holds potential as a H+ sensor for highly sensitive detection of the proton concentration in an aqueous solution.

Adsorption↗