Biomedical subjects

B Wang

Publications and source records attributed to B Wang.

At least 343 records · Page 19Linked to original sources

PubMed2000

[The structure identification of Julibroside J6 from Albizia julibrissin Durazz].

OBJECTIVE: To study the saponin from Albizia julibrissin. METHODS: A saponin was separated by using chromatography and its structure was elucidated on the basis of spectral data. RESULTS: A saponin was obtained and it's structure was identified as 3-O-[beta-D-xylopyranosyl-(1-->2)-alpha-L-arabinopyranosyl-(1-->6)-beta- D-2-deoxy-2-acetamidoglucopyranosyl]-21-O-(6S-2-trans-2-hydroxymethyl- 6-methyl-6-O-[4-O-(6S-2-trans-2-hydroxymethyl-6-methyl-6-hydroxy-2, 7-octadienoyl)-beta-D-quinovopyranosyl]-2, 7-octadienoyl)-acacic acid-28-O-beta-D-glucopyranosyl(1-->3)-[alpha-L-arabinofuranosyl- (1-->4)]-alpha-L-rhamnopyranosyl-(1-->2)-beta-D-glucopyranosyl ester. CONCLUSION: The saponin is a new compound named Julibroside J6.

Molecular Structure↗

PubMed2000

[Comparison of mechanical properties of laser-welded wrought and cast titanium].

OBJECTIVE: This study was aimed to compare the mechanical properties of laser-welded wrought and cast titanium. METHODS: According to relevant reports and clinical demands, the specimens of TA2 were machine milled or cast into certain sizes using LZ centrifuge-vacuum-pressure titanium casting machine. This experiment involved four groups including the laser-welded wrought titanium group, the laser-welded cast titanium group, the wrought titanium group and the cast titanium group. There were 6 complete specimens in each group and the specimens were ultrasonically cleaned with ethyl and distilled water before they were welded with home-made Nd:YAG apparatus, and comparisons of mechanical properties were made among these groups. All tensile specimens were mounted on the Instron universal testing machine to test tensile loads, yield loads and absolute elongations were measured. The cross section of fractured surface was observed under S-2700 Hitachi SEM and Vickers' microhardness values in different areas were detected with AKASHI microhardness tester. RESULTS: It was showed that the tensile load of laser-welded wrought titanium made no difference from that of the original wrought titanium, but the yield load of laser-welded wrought titanium was bigger than that of the original wrought titanium. The tensile load and yield load of cast titanium were slightly bigger than those of wrought titanium. The tensile load and yield load of laser-welded wrought titanium made no statistic difference from those of laser-welded cast titanium. The absolute elongations of cast or welded titanium were lower than those of wrought or non-welded titanium. The fractured surface of cast titanium under SEM appeared lath-like structure and that of welded cast titanium honeycomb-like structure. The honeycomb-like structure of wrought titanium was more obvious than that of laser-welded wrought titanium. The microhardness value of laser-welded cast titanium was slightly bigger than that of laser-welded wrought titanium. CONCLUSION: The mechanical property of laser-welded wrought titanium might be not apparently different from that of laser-welded cast titanium.

Dental Soldering↗

PubMed2000

[The neutralizing effect of histidine-rich-polypeptides on LPS from suspected periodontal pathogens].

OBJECTIVE: Human parotid histidine-rich-polypeptides (HRPs) are a family of lowmolecular-weight, cationic polypeptides. HRP-1, HRP-3 and HRP-5 comprise 85%-90% of the total HRPs and are called major HRPs. There were many researches indicating the antimicrobial activities of HRPs. Recently, HRPs were reported to have an inhibitory action on the lipopolysaccharide (LPS) of E. coli, with HRP-5 being the most effective one among the three major HRPs. Since the LPS of oral gram-negative bacteria is thought to be one of the important etiological factors during the development of periodontal diseases, our experiment was aimed to investigate the neutralizing effect of human parotid HRP-5 on the LPS of anaerobic suspected periodontal pathogens, which have different chemical structures and biological activities compared with LPS of aerobic E. coli. METHODS: By using of preparative acid urea polyacrylamide gel electrophoresis (AU-PAGE), HRP-5 was purified from parotid saliva collected from healthy adults. Two stains of suspected periodontal pathogens, Porphyromonas gingivalis (P.g, 47-A) and Fusobacterium nuceatum (F. n, separated from subgingival plaque of a patient with adult periodontitis) were mass cultured. After harvested in the midlogarithmic phase, they were washed and lyophilized. The LPS of dried bacteria were extracted by the modified Westphal hot phenol-water procedures and purified by the enzyme digestion plus ultracentrifugation. Limulus test was applied to test the neutralizing effect of HRP-5 on the LPS-induced gelation of Limulus amoebocyte lysate. In brief, the standard LPS of E. coli, or extracted LPS of P. g or F. n, was preincubated with HRP-5 in a tube separately in room temperature for 10 minutes. Then the reagent of Limulus amoebocyte lysate was added in all the tubes, continued the incubation in 37 degrees C for one hour. After that, the gelation level of every tube was observed. RESULTS: LPS extracted from P. g and F. n both showed good purity and strong activities to induce gelation of Limulus amoebocyte lysate. The gelation induced by LPS (1 ng/ml) of these two anaerobic suspected periodontal pathogens were weakly inhibited by HRP-5 (10 micrograms/ml), similar to that observed with standard LPS of E. coli. To get a complete neutralizing effect on LPS, it may be important to increase the concentration of HRP-5. CONCLUSION: It appeared that HRPs could neutralize the endotoxic properties of LPS of suspected periodontal pathogens, therefore may contribute to periodontal health. The present investigation further confirmed that HRPs are important components of the host non-immune defense system.

Escherichia coli↗

PubMed2000

[Enhancement of BCG-induced hBD-1 mRNA expression in human pulmonary gland epithelial cells].

Using reverse-transcription PCR (RT-PCR) and Northern blot analysis, the present authors found an enhanced expression of the human beta-defensin 1 (hBD-1) gene in the SPC-A-1 cells challenged with heat-killed M. Bovis Bacille Calmette-Guerin (BCG). The enhanced expression of hBD-1 mRNA was dose- and time-dependent. This result indicated a significant progress in the work of developing a new antimicrobial strategy that enhances mucosa antibiotic peptide expression for the prevention and treatment of mucosal infections.

BCG Vaccine↗

PubMed2000

[A noninvasive method for radial pulse-wave velocity and the determinants of pulse-wave velocity].

An effective experimental method has been proposed and used to determine the pulse-wave velocity (PWV) of 257 radial pulse signals. Experimental results show that, compared with the normal pulse, the wiry pulse has an increased PWV(P < 0.01 or P < 0.05), the thready pulse has a decreased PWV(P < 0.05), but the PWV of the smooth pulse is not significantly different from the normal's (P > 0.05). PWV highly correlates with the artery blood pressure. The possible determinants of PWV are analyzed and discussed in reference to clinical diagnosis.

Blood Pressure↗

PubMed2000

[The effect of artesunate in preventing the populations from Schistosoma japonicum infection during flood-control].

OBJECTIVE: To evaluate the prophylactic effect of artesunate in high-risk populations who had contacted the infested water. METHODS: From the 7th day post-exposure to infested water, a total of 17,031 people who had contacted the infested water for more than 20 days had been treated with artesunate at a dose of 300 mg once a week for three successive weeks. On day 17 after the last medication, they were examined for schistosomiasis and followed-up 60 days later. RESULTS: No acute schistosomiasis case was found. ELISA-positive was found in 204(1.20%) and COPT > 3% was found in 195 cases (1.14%). The side-effects were slight. CONCLUSION: Artesunate is highly effective and safe for the prevention of schistosomiasis.

Adolescent↗

PubMed2000

[The clinical observation of microsurgery treatment in early glottic carcinomas].

OBJECTIVE: To improve the life quality of the patients with T1 glottic carcinomas, and obtain good vocal effect. METHODS: Twenty-two patients under shoring laryngoscope and microscope were operated by surgery and laser. The phonetic parameters and vocal cord states of preoperative and postoperative patients were evaluated and analyzed objectively. RESULTS: The three-year relapse rate was 9.0% (2/22), and the survival rate of three-year, four-year, five-year were 100%, 94.7%, 93.3% respectively. The postoperative phonetic quality was improved. CONCLUSION: Patients with early glottis carcinomas could be treated by microsurgery. The damage of normal tissue might be reduced, and the patient's life quality has been improved. This method should be used widely in clinic.

Adult↗

PubMed2000

[Clinical and experimental studies on condyloma acuminata].

Condyloma acuminata(CA) is one of sexually transmitted diseases(STD) caused by human papillomavirus(HPV). We have done systemic study on the CA in recent years. Analyzing the morbidity of CA in our STD clinics showed that CA was in the first or second place of STD. Tissue specimens from CA were detected HPV DNA by dot blot hybridization and PCR. The result showed PCR was more sensitive than dot blot hybridization. HPV DNA were detected by PCR in tissue specimens of cervical squamous carcinoma, as well as cervical and vulvar CA. The result confirmed that HPV 16 was main type in cervical squamous carcinoma, and HPV 6 and 11 were main types in cervical and vulvar CA. To differentiate pseudocodyloma of vulva from CA, electron microscopy and HPV DNA detection were done. Certain ultrastructural changes were helpful, and detection of HPV DNA was better method in differentiating CA from pseudocondyloma. High purification of podophyllintoxin was studied and the effectiveness of podophyllintoxin was observed, compared to imported podophyllintoxin to treat CA, both cure rates were more than 80% after 3 week's therapy. Intralesional injection of different interferons for CA was effective.

Condylomata Acuminata↗

PubMed2000

[The spectroscopic study of topaz].

In this paper, the natural gem material--Topaz (colorless transparent samples and reactor irradiation induced blue color samples) was studied on the spectroscopic analysis of Fourier transformation infrared spectrum (FTIR) and FT-Raman spectrum. The structure of topaz consists of OH groups and SiO4 groups. Si-O vibration spectrum was characterized with the group theoretical analysis. OH stretching modes of vibration showed many changes among the different color samples, the reason of the changes was explained. The color origin was preliminary investigated by ultra-violet and visible absorption spectrum.

Resin Cements↗

PubMed1999

The selection of M3-restricted T cells is dependent on M3 expression and presentation of N-formylated peptides in the thymus.

The major histocompatibility complex (MHC) class Ib molecule H2-M3 binds N-formylated peptides from mitochondria and bacteria. To explore the role of M3 expression and peptide supply in positive and negative selection, we generated transgenic mice expressing an M3-restricted TCR-alpha/beta from a CD8(+) T cell hybridoma (D7) specific for a listerial peptide (LemA). Development of M3-restricted transgenic T cells is impaired in both beta2-microglobulin-deficient and transporter associated with antigen processing (TAP)-deficient mice, but is not diminished by changes in the H-2 haplotype. Maturation of M3/LemA-specific CD8(+) single positive cells in fetal thymic organ culture was sensitive to M3 expression levels as determined by antibody blocking and use of the castaneus mutant allele of M3. Positive selection was rescued in TAP(-/-) lobes by nonagonist mitochondrial and bacterial peptides, whereas LemA and a partial agonist variant caused negative selection. Thus, M3-restricted CD8(+) T cells are positively and negatively selected by M3, with no contribution from the more abundant class Ia molecules. These results demonstrate that class Ib molecules can function in thymic education like class Ia molecules, despite limited ligand diversity and low levels of expression.

Animals↗

PubMed1999

An Eph receptor regulates integrin activity through R-Ras.

The ability of integrins to mediate cell attachment to extracellular matrices and to blood proteins is regulated from inside the cell. Increased ligand-binding activity of integrins is critical for platelet aggregation upon blood clotting and for leukocyte extravasation to inflamed tissues. Decreased adhesion is thought to promote tumor cell invasion. R-Ras, a small intracellular GTPase, regulates the binding of integrins to their ligands outside the cell. Here we show that the Eph receptor tyrosine kinase, EphB2, can control integrin activity through R-Ras. Cells in which EphB2 is activated become poorly adherent to substrates coated with integrin ligands, and a tyrosine residue in the R-Ras effector domain is phosphorylated. The R-Ras phosphorylation and loss of cell adhesion are causally related, because forced expression of an R-Ras variant resistant to phosphorylation at the critical site made cells unresponsive to the anti-adhesive effect of EphB2. This is an unusual regulatory pathway among the small GTPases. Reduced adhesiveness induced through the Eph/R-Ras pathway may explain the repulsive effect of the Eph receptors in axonal pathfinding and may facilitate tumor cell invasion and angiogenesis.

3T3 Cells↗

PubMed1999

Human ferrochelatase: crystallization, characterization of the [2Fe-2S] cluster and determination that the enzyme is a homodimer.

Ferrochelatase (protoheme ferrolyase, EC 4.99.1.1) catalyzes the terminal step in the heme biosynthetic pathway, the insertion of ferrous iron into protoporphyrin IX to form protoheme IX. Previously we have demonstrated that the mammalian enzyme is associated with the inner surface of the inner mitochondrial membrane and contains a nitric oxide sensitive [2Fe-2S] cluster that is coordinated by four Cys residues whose spacing in the primary sequence is unique to animal ferrochelatase. We report here the characterization and crystallization of recombinant human ferrochelatase with an intact [2Fe-2S] cluster. Gel filtration chromatography and dynamic light scattering measurements revealed that the purified recombinant human ferrochelatase in detergent solution is a homodimer. EPR redox titrations of the enzyme yield a midpoint potential of -453+/-10 mV for the [2Fe-2S] cluster. The form of the protein that was crystallized has a single Arg to Leu substitution. This mutation has no detectable effect on enzyme activity but is critical for crystallization. The crystals belong to the space group P2(1)2(1)2(1) and have unit cell constants of a=93.5 A, b=87.7 A, and c=110.2 A. There are two molecules in the asymmetric unit and the crystals diffract to better than 2.0 A resolution. The Fe to Fe distance of the [2Fe-2S] cluster is calculated to be 2.7 A based upon the Bijvoet difference Patterson map.

Chromatography, Gel↗

PubMed1999

NK cell-deficient mice develop a Th1-like response but fail to mount an efficient antigen-specific IgG2a antibody response.

NK cells have been shown to play a role in the modulation of B cell differentiation and Ab production. Using a novel murine model of NK cell deficiency, we analyzed the in vivo role of NK cells in the regulation of Ag-specific Ab production. After immunization with OVA or keyhole limpet hemocyanin in CFA, NK cell-deficient (NK-T+) mice developed an efficient Th1 response and produced significant levels of IFN-gamma but displayed markedly reduced or absent Ag-specific IgG2a production. There were no differences in the levels of Ag-specific IgG, IgG1, and IgG2b between NK-T+ and NK+T+ mice. Furthermore, NK cell-reconstituted, NK+T+ (tgepsilon26Y) mice produced significant amounts of Ag-specific IgG2a after immunization with OVA. These results indicate that NK cells are involved in the induction of Ag-specific IgG2a production in vivo. Moreover, they also demonstrate that the lack of Ag-specific IgG2a Ab production in NK-T+ mice is not associated with the impaired Th1 response and IFN-gamma production.

Animals↗

PubMed1999

Protein kinase A antagonizes Hedgehog signaling by regulating both the activator and repressor forms of Cubitus interruptus.

The Hedgehog (Hh) family of secreted proteins controls many aspects of animal development. In Drosophila, Hh transduces its signal via Cubitus interruptus (Ci), a transcription factor present in two forms: a full-length activator and a carboxy-terminally truncated repressor that is derived from the full-length form by proteolytic processing. The proteolytic processing of Ci is promoted by the activities of protein kinase A (PKA) and Slimb, whereas it is inhibited by Hh. Here we show that PKA inhibits the activity of the full-length Ci in addition to its role in regulating Ci proteolysis. Whereas Ci processing is blocked in both PKA and slimb mutant cells, the accumulated full-length Ci becomes activated only in PKA but not in slimb mutant cells. Moreover, PKA inhibits an uncleavable activator form of Ci. These observations suggest that PKA regulates the activity of the full-length Ci independent of its proteolytic processing. We also provide evidence that PKA regulates both the proteolytic processing and transcriptional activity of Ci by directly phosphorylating Ci. We propose that phosphorylation of Ci by PKA has two separable roles: (1) It blocks the transcription activity of the full-length activator form of Ci, and (2) it targets Ci for Slimb-mediated proteolytic processing to generate the truncated form that functions as a repressor.

Animals↗

PubMed1999

Local L-arginine delivery after balloon angioplasty reduces monocyte binding and induces apoptosis.

BACKGROUND: Local administration of L-arginine after balloon angioplasty has been shown to enhance NO generation and inhibit lesion formation. In this study, we assessed the mechanisms by which local delivery of L-arginine inhibits lesion formation. METHODS AND RESULTS: New Zealand White rabbits (n=56) were fed a 1% cholesterol diet. After 1 week, both iliac arteries were balloon-denuded, and a local drug delivery catheter was introduced into both iliac arteries to deliver either L-arginine (800 mg/5 mL with and without 100 microCi L-[2,3-(3)H]-arginine) or saline. Monocyte-endothelial interaction was assessed by functional binding assay; NO activity was measured by chemiluminescence. Intramural administration of radioactively labeled L-arginine led to significantly higher counts in comparison to the contralateral segment for up to 1 week after delivery (676+/-223 versus 453+/-93 cpm/mg; P<0.02); this was associated with significantly higher NO levels in the L-arginine-treated segments (394.4+/-141.6 versus 86.3+/-34.3 nmol/mg; P<0.01). Even after 2 to 3 weeks, monocyte binding was significantly decreased by treatment with L-arginine as compared with saline infusion (P<0.01). After 4 weeks, there was a 9-fold greater number of apoptotic cells in the vessel wall of L-arginine as compared with the saline-treated segments (P<0.05). CONCLUSIONS: Intramural delivery of L-arginine immediately after angioplasty causes a sustained increase in tissue L-arginine levels associated with enhancement of local NO synthesis. The local increase in NO synthesis is associated with an attenuation of monocyte binding and increased apoptosis of resident macrophages. This treatment strategy could be valuable for the prevention and management of restenosis.

Angioplasty, Balloon↗

PubMed1999

Building fluorescent sensors by template polymerization: the preparation of a fluorescent sensor for D-fructose.

[formula: see text] The application of molecular imprinting in making fluorescent sensors has been hampered by the lack of suitable fluorescent tags, which would respond to the binding event with significant fluorescence intensity changes. We have designed and synthesized a fluorescent monomer which allows for the preparation of fluorescent sensors of cis diols using molecular imprinting methods. This monomer was used for the preparation of sensitive fluorescent sensors for D-fructose.

Fluorescent Dyes↗

PubMed1999

Sonic hedgehog protein signals not as a hydrolytic enzyme but as an apparent ligand for patched.

The amino-terminal signaling domain of the Sonic hedgehog secreted protein (Shh-N), which derives from the Shh precursor through an autoprocessing reaction mediated by the carboxyl-terminal domain, executes multiple functions in embryonic tissue patterning, including induction of ventral and suppression of dorsal cell types in the developing neural tube. An apparent catalytic site within Shh-N is suggested by structural homology to a bacterial carboxypeptidase. We demonstrate here that alteration of residues presumed to be critical for a hydrolytic activity does not cause a loss of inductive activity, thus ruling out catalysis by Shh-N as a requirement for signaling. We favor the alternative, that Shh-N functions primarily as a ligand for the putative receptor Patched (Ptc). This possibility is supported by new evidence for direct binding of Shh-N to Ptc and by a strong correlation between the affinity of Ptc-binding and the signaling potency of Shh-N protein variants carrying alterations of conserved residues in a particular region of the protein surface. These results together suggest that direct Shh-N binding to Ptc is a critical event in transduction of the Shh-N signal.

Amino Acid Sequence↗

PubMed1999

Isolation of high-affinity peptide antagonists of 14-3-3 proteins by phage display.

The 14-3-3 proteins interact with diverse cellular molecules involved in various signal transduction pathways controlling cell proliferation, transformation, and apoptosis. To aid our investigation of the biological function of 14-3-3 proteins, we have set out to identify high-affinity antagonists. By screening phage display libraries, we have identified a set of peptides which bind 14-3-3 proteins. One of these peptides, termed R18, exhibited a high affinity for different isoforms of 14-3-3 with estimated K(D) values of 7-9 x 10(-)(8) M. Recognition of multiple isoforms of 14-3-3 suggests the targeting of R18 to a structure that is common among 14-3-3 proteins, such as the conserved ligand-binding groove. Indeed, mutations that alter critical residues in the ligand-binding site of 14-3-3 drastically decreased the level of 14-3-3-R18 association. R18 efficiently blocked the binding of 14-3-3 to the kinase Raf-1, a physiological ligand of 14-3-3, and effectively abolished the protective role of 14-3-3 against phosphatase-induced inactivation of Raf-1. The cocrystal structure of R18 in complex with 14-3-3zeta revealed the occupancy of the general binding groove of 14-3-3zeta by R18, explaining the potent inhibitory effect of R18 on 14-3-3-ligand interactions. Such a well-defined peptide will be an effective tool for probing the role of 14-3-3 in various signaling pathways, and may lead to the development of 14-3-3 antagonists with pharmacological applications.

14-3-3 Proteins↗