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Biomedical subjects

J Yang

Publications and source records attributed to J Yang.

At least 541 records · Page 30Linked to original sources
PubMed2000

[Studies on constituents in Uncaria macrophylla Wall].

OBJECTIVE: To study the chemical constituents of Uncaria macrophylla. METHOD: Compounds were isolated by Columu Chromatography, and the structures were identified by NMR spectral data and other methods. RESULT AND CONCLUSION: Six compounds were isolated and identified as ursolic acid, 3 beta-6 beta-23-trihydroxyurs-12-en-28-oic acid, 3 beta, 6 beta, 19 alpha-trihydroxyurs-12-en-28-oic acid, epicatechin, beta-sitosterol and daucosterin. All the compounds were isolated for the first time from the plant.

Catechin↗
PubMed2000

[Relationship between blood lead and free erythrocyte-protoporphyrin of female workers exposed to low concentration of lead operating environment].

The thesis focused in the research on whether low-lead operation would have effects on female workers. Based on investigation of 82 female workers under an operation environment with lead concentration of 0.0315 mg/m3, the following report indicated that differences did exist in terms of free erythrocyte-protoporphyrin(FEP), lead-blood(Pb-B) and lead-urine(Pb-U) values between the exposure and control groups. Pb-B, FEP and Pb-U were found closely interrelated and comparatively sensitive. Dose-response relationship was discovered in the process, positive percentage of Pb-B and FEP were 20.73% and 21.95% respectively, 13.4% above the maximal standard in both cases. In consequence, it was concluded that exposure to the 0.0315 mg/m3 lead concentration (0.03 mg/m3 being the normal) was still harmful to the female workers. Apart from that, the article suggested that the upper limit of lead in blood for common women (in Changchun city) was properly defined at 1.46 mumol/L. With FEP as the standard, the article made repective comparisons on the female workers' intelligence quotient (IQ) and the symptom occurrence of the neural system. People with IQ value between 60 to 79, 80 to 89, 90 to 109 or 110 to 119, the rates of showing positive report with FEP > or = 0.90 mumol/L were 27.6%, 22.6% and 15.0% respectively. The general occurrence rate on various level of FEP was obviously higher than that of the control group. The highest occurrence rate of 208.32% and 58.74% appeared when the FEP value was between 0.36 mumol/L to 0.54 mumol/L. When we made the comparison according to different symptoms as headache, dizziness, hypomnesis, somnipathy, palpitation and ephidrosis, the occurrence rate of headache was distinctively highger than that of the somnipathy.

Adult↗
PubMed2000

[Expression of eukaryotic expression plasmid pcDNA3/pacA and pcDNA3/pacP in mammalian cells].

OBJECTIVE: Prior to the use of pcDNA3/pacA and pcDNA3/pacP in vivo, the transcription and expression products of these two eukaryotic expression plasmids in mammalian cells were detected. METHODS: The eukaryotic expression plasmids pcDNA3/pacA and pcDNA3/pacP were transfected into COS-7 cells respectively with liposome according to the manufacturer's protocol. In order to generate stable transfectants, after a 48 h incubation period in regular Dulbecco's modified Eagle's medium (DMEM) supplemented with 10% heat inactivated fetal bovine serum, cells were treated with neomycin (1 mg.ml-1 of G418) and maintained under continuous selective pressure. G418-resistant colonies, which became visible after 2 weeks, were isolated and screened for expression of the vector-encoded protein. The control transfections were performed with the pcDNA3 vector and without recombinant as well as vector plasmid DNA. The mRNA transcriptions of the two insertional genes were detected by RT-PCR assay and their expression products were analysed by labelled-avidin-biotin enzymed-linked immunosorbent assay, flow cytometry and Western blotting. The cells transfected by pcDNA3 were used as the negative control. RESULTS: 1. The two eukaryotic expression plasmids could be correctly transcripted and translated under the control of the CMV immediate early promoter in mammalian cells. 2. The protein products could be detected in cell plasma, cell membrane and the culture supernatant. CONCLUSION: The two eukaryotic expression plasmids pcDNA3/pacA and pcDNA3/pacP can express protein products which were encoded by insertional gene pac-A and pac-P in mammalian cells.

Animals↗
PubMed2000

[Evaluation of cariogenic potential of Streptococcus mutans isolated from caries-free and -active persons: adherence properties to saliva-coated hydroxyapatite].

OBJECTIVE: In this study, authors used saliva-coated hydroxyapatite to simulate tooth surface in oral cavity to evaluate adherence of different Streptococcus mutans isolated from caries-free and -active persons to saliva-coated hydroxyapatite. METHODS: Streptococcus mutans isolated from people with different carious experiences were divided into two groups: the caried-free group (DMFS = 0) including 19 persons and the caries-active group (DMFS > or = 6) including 40 persons. Totally 105 genotype Streptococcus mutans strains were obtains, including 22 strains from the caries-free group, and 83 strains from the caries-active group. The adhering properties of Streptococcus mutans (serotype c) strains were investigated, and different adhering properties were compared between the caries-free group and the caries-active group in order to find the correlationship between carious experiences and adhering properties of Streptococcus mutans. Saliva-coated hydroxyapatite was used to simulated tooth surface in oral cavity. Streptococci mutans were cultured in TPY liquid medium containing 3H-TDR in the same radioactive concentration. After being cultured in an anaerobic incubator for 18 hours, Streptococci mutans were radiolabelled by 3H-TDR. Saliva-coated hydroxyapatite and bacterial liquid(BSA = 0.52) were mixed for 90 minutes. Samples were assayed by using liquid scintillation counter, and binding abilities of strains were evaluated by the count per minute(cpm). RESULTS: Binding abilities of strains were significantly different in two groups, Caries-active people harbored more Streptococci mutans with high binding abilities(cpm > 2000) than caries-free people did(P < 0.05). The binding abilities to saliva-coated hydroxyapatite were different between strains of differing genotypes isolated from the same person. Each person always harbored one or two strains with high binding abilities(cpm > 2000) in the caries-active group. CONCLUSION: 1. Different genotypes have different adhering properties. 2. In caries-active group, different genotype strains have synergic effects, and adhesion of high binding ability strains cause caries susceptibility. 3. The differences in binding properties of isolates might relate to differences in carious experiences.

Bacterial Adhesion↗
PubMed2000

[Evaluation of cariogenic potential of Streptococcus mutans isolated from caries-free and -active persons: abilities to synthesize water-soluble and -insoluble glucans].

OBJECTIVE: In this study, authors investigated abilities of Streptococcus mutans (serotype c) strains to synthesize water-soluble and water-insoluble glucans. METHODS: Streptococcus mutans strains were isolated from people with different carious experiences, which were divided into two groups: caries-free (DMFS = 0) group including 19 persons and caries-active group(DMFS > or = 6) including 40 persons. Totally 105 genotypes of Streptococcus mutans strains were obtained, including 22 strains from the caries-free group and 83 strains from the caries-active group. The differences of abilities to synthesize water-soluble and water-insoluble glucans between these two groups were compared in order to find the correlationship between the synthesis of glucans and caries experience. Then, Streptococcus mutans were cultured in TPY liquid medium containing 1% sucrose in an anaerobic incubator at 37 degrees C for 24 hours. Glucans synthesized by Streptococcus mutans was qualified by using infrared spectrophotometry. The amounts of water-soluble and water-insoluble glucans were measured by using the anthron method. RESULTS: According to the same absorption tops position analysed by infrared spectrophotometry, glucans samples were certified. The amounts of glucans synthesized by Streptococcus mutans strains were different between strains of different genotypes even isolated from the same person. Mostly, the amount of water-insoluble glucans was higher than that of water-soluble glucans between different genotype Streptococcus mutans strains. The oral environments of patients in the caries-active group harbored more Streptococcus mutans strains with higher water-soluble glucans producing ability than those of the caries-free group did (P < 0.05), and patients of the caries-active group also harbored more Streptococcus mutans strains with higher water-insoluble glucans producing ability than those of the caries-free group did(P < 0.01). CONCLUSION: 1. Glucosyltranferases of different genotype strains are different in glucans production, and different genotype strains relate to different cariogenic abilities. 2. Glucans was one of cariogenic factors, and water-insoluble glucans was more important than water-soluble glucans in cariogenic ability of Streptococcus mutans. 3. The differences in glucans production of isolated strains might relate to differences in carious experiences.

Dental Caries↗
PubMed2000

[Morphological observation and electrophysiological properties of isolated Deiters' cells from guinea pig cochlea].

OBJECTIVE: To dissociate viable isolated Deiters' cells from guinea pig cochlea and perform morphological measurements under inverted microscope; To study electrophysiological properties of Deiters' cells. METHOD: Deiters' cells were dissociated from guinea pig cochlea by papain digestion followed by trituration. Standard patch clamp methods were used to measure whole cell capacitance, zero current potential, reversal potential and potassium ion currents of Deiters' cells in normal external solution. Equations were used to compute the relative membrane permeability ratio of Deiters' cell to K+ and Na+ (PK/PNa) and the potassium equilibrium potential (EK). RESULT: Isolated Deiters' cell looks like a comma, which was divided into cell body, stem and Deiters' phalanx and the nucleus is at about center of its body. Cell length of Deiters' cell was (61.6 +/- 20) microM (mean +/- SEM, n = 45), whole cell capacitance was (27.5 +/- 9.2) pF (n = 28), zero current potential was (-20 +/- 1.8) mV(n = 28), reversal potential was (-64.3 +/- 2.9) mV (n = 24), PK/PNa = 25.4:1 and EK = -82.4 mV. Potassium currents of Deiters' cells were recorded in normal external solution. CONCLUSION: The situation of Deiters' cells in cochlea could be inferred according to length of them indirectly. The ion channel of Deiters' cells was mainly K+ selective. Voltage-dependent and outwardly rectifying potassium currents were prominent in Deiters' cells.

Animals↗
PubMed2000

[Study on the production of beta-mannanase by Bacillus M50].

Bacillus sp. M50 produced beta-mannanase efficiently in the medium composed of 4% konjac powder, 1.0% (NH4)2SO4 and 0.35% Na2CO3. Fermentation of beta-mannanase by Bacillus sp. M50 has been carried out in 100 L tank. The temperature, ventitation quantity and agitation speed were 30-32 degrees C, 1:0.75 vvm and 220 r/min respectively. the fermentation cycle was 28 h and the highest beta-mannanase activity was 330 u/mL. The optimal temperature and pH for beta-mannanase reaction were 50 degrees C and 6.0 respectively. It was stable at pH 4.0-7.0 and below 50 degrees C. The activity of the enzyme was strongly inhibited by Fe3+, Al3+, EDTA, Hg2+ and slightly stimulated by Ba2+, Mn2+. Treatment of ramie-fibers with crude enzyme preparations from Bacillus sp. M50 showed a good degradation for hemicellulose of ramie-fibers residues.

Bacillus↗
PubMed2000

[Pharmacognostical studies on the roots of Stellera chamaejasme and S. chamaejasme f. chrysantha].

Morphological and histological characters of the roots of Stellera chamaejasme L. and S. chamaejasme L. f. chrysantha S. C. Huang, used as the origins of the Chinese medicine Langdu, were described and illustrated with line drawings. TLC analyses of the above two drugs were also undertaken. These studies provide referencial informations for the quality control, development and identification of these two drugs.

Chromatography, Thin Layer↗
PubMed2000

[Pharmacognostical studies on the roots of Euphorbia stracheyi].

Morphological and histological characters of the roots of Euphorbia stracheyi Boiss., a traditional Chinese medicine, were described and illustrated with line drawings. TLC analysis of the above drug was also undertaken. These studies provide referencial information for clinics, quality control, development and identification of this crude drug.

Chromatography, Thin Layer↗
PubMed2000

[Protective effect of total paeony glycoside against cerebral ischemia-reperfusion injury in mice].

OBJECTIVE: To investigate actions of Total Paeony Glycoside (TPG) on cerebral ischemia-reperfusion model in mice. METHODS: The cerebral ischemia-reperfusion models induced by lagation of bilateral common carotid arteries incompletely were used. RESULTS: It was found that TPG could improve the learning and memory capacity of model mice in step down test. TPG significantly reduced the decrease of superoxide dismutase(SOD), inhibited the increase of nitric oxide(NO) and lessened the level of malondialdehyde(MDA) in model mice. 75 mg.kg-1 TPG also reduced the decrease of lactate dehydrogenase (LDH) in cerebrum remarkedly. CONCLUSION: It is suggested that TPG possess obvious protective effects against cerebral ischemia-reperfusion mice.

Animals↗
PubMed2000

[Pharmacognostical studies on the roots of Euphorbia fischeriana].

Morphological and histological characters of the roots of Euphorbia fischeriana Steud., used as one of the origins of traditional Chinese medicine Langdu, were described and illustrated with line drawings. TLC analysis of the above drug was also undertaken. These studies provide referencial informations for clinics, quality control, development and identification of this crude drug.

Chromatography, Thin Layer↗
PubMed2000

[Outward potassium currents in isolated Deiters' cells of guinea pig cochlea].

OBJECTIVE: To study potassium currents in isolated Deiters' cells of guinea pig cochlea. METHODS: Potassium currents in Deiters' cells in normal external solution, in external solutions with different K+ concentrations effecting on reversal potentials and outward potassium currents, 4-aminopyridine (4-AP) and tetraethylammonium (TEA) blocking components of outward potassium currents and kinetics of activation and inactivation of potassium ion channels were studied using the whole cell variant of the patch clamp technique. RESULTS: Isolated Deiters' cells could possess voltage dependent, outwardly rectifying ion channel which was K+ selective. Existence of two separate types of K+ channels or their closed and open states was suggested by effects of 4-AP and TEA. Activation and inactivation of ion channels were described by Boltzmman equation. Voltage dependent inward Ca2+ current could not be detected. CONCLUSION: Outwardly rectifying potassium in Deiters' cells could buffer extracellular K+ in the small space between Deiters' cells and outer hair cells or neural fibers and alter the stiffness of Deiters' cells, which as a result might influence cochlear mechanics.

4-Aminopyridine↗
PubMed2000

[Uptake of drug-containing nanoparticles in dog catotid and femoral arteries].

OBJECTIVE: To study the uptake of drug-containing nanoparticles in artery for local therapy of restenosis. METHODS: Polylactic polyglycolic acid copolymer (PLGA) nanoparticles containing an antiproliferative agent 2-amino-chromone were formulated with an oil-in-water sonication emulsion/solvent evaporation technique. Arterial uptake of nanoparticles was assessed both in vitro and in vivo models of dog and rat carotid and femoral arteries. Epoxide, cyanoacrylate, fibrinogen, fibronectin, didodecyldimethylammonium bromide (DMAB), L-alpha-phosphatidylethanolaine, and lipofectin were selected to modify the surface of nanoparticles to enhance arterial uptake of nanoparticles. RESULTS: The nanoparticle size ranged from 100 nm to 200 nm, the drug loading in nanoparticles was about 15%, the nanoparticle morphology was observed by scanning electron microscopy and showed spherical shape with smooth surface. Arterial uptake of nanoparticles was enhanced greatly by surface modified nanoparticle with positively charged active agent DMAB. Once nanoparticles located in artery, a high drug level could be maintained at local site for 2 days in vivo model. CONCLUSION: The primary results of animal experiments suggested that nanoparticle could be used as drug carrier of local drug delivery for treating cardiovascular diseases.

Animals↗
PubMed2000

[Optimum parameters of four-color high temperature measurement].

The ratio of the intensity of black body radiation at four wavelengths was calculated by the blackbody radiation law. The result shows that there is a good single-valued relationship between the ratio and the temperature of an emission body under some given conditions, and the impact of radiant emittance on the measurement of temperature was reduced to some extent. The optimum conditions, such as measured wavelengths, wavelength distance and integrating width at every measured point were deduced. The results were diagrammed and discussed.

English Abstract↗
PubMed1999

Targeted gene disruption demonstrates that P-selectin glycoprotein ligand 1 (PSGL-1) is required for P-selectin-mediated but not E-selectin-mediated neutrophil rolling and migration.

P-selectin glycoprotein ligand 1 (PSGL-1) is a mucin-like selectin counterreceptor that binds to P-selectin, E-selectin, and L-selectin. To determine its physiological role in cell adhesion as a mediator of leukocyte rolling and migration during inflammation, we prepared mice genetically deficient in PSGL-1 by targeted disruption of the PSGL-1 gene. The homozygous PSGL-1-deficient mouse was viable and fertile. The blood neutrophil count was modestly elevated. There was no evidence of spontaneous development of skin ulcerations or infections. Leukocyte infiltration in the chemical peritonitis model was significantly delayed. Leukocyte rolling in vivo, studied by intravital microscopy in postcapillary venules of the cremaster muscle, was markedly decreased 30 min after trauma in the PSGL-1-deficient mouse. In contrast, leukocyte rolling 2 h after tumor necrosis factor alpha stimulation was only modestly reduced, but blocking antibodies to E-selectin infused into the PSGL-1-deficient mouse almost completely eliminated leukocyte rolling. These results indicate that PSGL-1 is required for the early inflammatory responses but not for E-selectin-mediated responses. These kinetics are consistent with a model in which PSGL-1 is the predominant neutrophil P-selectin ligand but is not a required counterreceptor for E-selectin under in vivo physiological conditions.

Animals↗
PubMed1999

Mammalian chondrocytes expanded in the presence of fibroblast growth factor 2 maintain the ability to differentiate and regenerate three-dimensional cartilaginous tissue.

The differentiated phenotype of chondrocytes from hyaline cartilage is gradually lost during expansion in monolayers. Chondrocytes can reexpress their differentiated phenotype by transfer into an environment that prevents cell flattening, but serially passaged cells never completely recover their chondrogenic potential. We report that chondrocytes expanded (up to 2000-fold) in the presence of fibroblast growth factor 2 (FGF-2) dedifferentiated, but fully maintained their potential for redifferentiation in response to environmental changes. After seeding onto three-dimensional polymer scaffolds, chondrocytes expanded in the presence of FGF-2 formed cartilaginous tissue that was histologically and biochemically comparable to that obtained using primary chondrocytes, in contrast to chondrocytes expanded to the same degree but in the absence of FGF-2. The presence of FGF-2 inhibited the formation of thick F-actin structures, which otherwise formed during monolayer expansion, were maintained during tissue cultivation, and were associated with reduced ability of chondrocytes to reexpress their differentiated phenotype. This study provides evidence that FGF-2 maintains the chondrogenic potential during chondrocyte expansion in monolayers, possibly due to changes in the architecture of F-actin elements and allows more efficient utilization of harvested tissue for cartilage tissue engineering.

Actins↗