Hydrodynamic description of granular convection.
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Journal Article↗
Biomedical subjects
S Yue
Publications and source records attributed to S Yue.
Dyes providing increased sensitivity in flow-cytometric dye-efflux assays for multidrug resistance.
In an effort to improve detection of P-glycoprotein-mediated multidrug resistance (mdr), several dyes were compared to rhodamine 123 (R123) in efflux assays. Two dyes (SY-38 and SY-3150) were found that provided better sensitivity. These dyes were effluxed by a cell line known to be mdr-positive (P388/R84) but not by an mdr-negative cell line (P388). Efflux was blocked by both verapamil and cyclosporine A. Efflux from KG1a cells was less than from P388/R84, just as has been seen with R123 and daunomycin. In further experiments, a model system was used to demonstrate two-color immunofluorescence plus efflux measurements. This was done using a sequential staining method. A procedure was devised that, at least for this model system, allowed single-step staining with both dye and antibody. The sensitivity of the efflux measurement was slightly compromised by using this one-step staining method.
ATP Binding Cassette Transporter, Subfamily B, Mem↗
Deterministic chaos in failure dynamics: Dynamics of peeling of adhesive tape.
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Journal Article↗
A method of stimulating an immune response with a hapten immobilized on a nitrocellulose membrane.
Hapten refers to a chemical compound of small molar mass (typically less than 1000 daltons) that can bind with an antibody, but cannot initiate an immune response by itself unless it is conjugated to a protein carrier of larger molar mass. A novel method to prepare a hapten to generate anti-hapten immunity without covalent conjugation to a carrier was developed. Coating both water-soluble and -insoluble haptens onto a nitrocellulose membrane effectively presented haptens to the system and caused the generation of specific anti-hapten B lymphocytes and antibodies by immunization both in vitro and in vivo. This method has a potential to substitute for conventional hapten carrier conjugation to generate anti-hapten immunity.
Adsorption↗
Granular relaxation under tapping and the traffic problem.
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Journal Article↗
[Pathological study of enamel caries produced by oral bacteria in vitro].
The authors used the bacterial culture method to study early enamel caries-like lesions in vitro. Pathologic changes in the lesions were observed under polarized light microscope and scanning electron microscope. The results showed that this method could simulate the destructive procedures in carious development. The destructive way and pathologic changes of the caries-like lesions were very similar to those of natural caries. Under microscope, the ultrastructures of the relatively intact layer of the enamel surfaces were already changed. The prisms in the enamel surfaces were destroyed, and dissolved to form small pores. The pores could be an important path of the carious development.
Actinomyces viscosus↗
A fluorometric microplate-based assay of submicrogram monomeric actin by inhibition of deoxyribonuclease I.
Inhibition of bovine pancreatic deoxyribonuclease I (DNase I) has been a standard method for specific quantitation of monomeric (G-) actin. The aim of this work is to substantially enhance the sensitivity of this type of G-actin assay by using a fluorescent dye, thiazole orange (TO), which has a high optical absorption, moderate DNA affinity, and large fluorescence enhancement upon binding to DNA. The high fluorescence output and moderate affinity of TO's DNA complex produce a large fluorescence decrease when the complex is disrupted by DNase I, thus permitting a highly sensitive detection of G-actin by its inhibition on the fluorescence decrease. The results show that the dynamic responsiveness of a fluorometric G-actin assay can be improved by lowering the concentration of DNA and affinity of the labeling dye, as long as the fluorescence signal of the dye-DNA complex is sufficient for instrumental detection. With a DNA concentration of 6.0 micrograms/ml and TO dye labeling, as little as 20 ng of G-actin can be reliably detected in a fluorescence microplate scanner. This sensitivity also appears to be the utmost detection limit of any G-actin assay that is based on DNase I inhibition.
Actins↗
Picogram detection of stable dye-DNA intercalation complexes with two-color laser-excited confocal fluorescence gel scanner.
The stable complexes between highly fluorescent, polyfunctional intercalators and dsDNA can be used to detect dsDNA in agarose gels at picogram levels and for multicolor detection of multiplexed dsDNA fragments. Development of additional DNA-binding fluorophores with appropriate spectroscopic properties will expand the range of applications. In principle, the DNA-dye intercalation complexes represent a more sensitive alternative to an established approach to fluorescent labeling and detection of restriction fragments by ligation to single-stranded short oligonucleotides labeled with different fluorochromes, followed by separation on denaturing polyacrylamide gels. The latter technique gives near single-base resolution up to 400 bases and the ability to quantitate fragment size up to 2000 bases, and has been successfully applied to cosmid mapping. Detection of DNA fragments as intercalation complexes requires that the separations be performed on agarose gels under nondenaturing conditions. Such conditions have been used for extensive mapping of yeast cosmids with postelectrophoresis staining with ethidium bromide. For the patterns on agarose gels, the magnitude of the "error window," which specifies how similar two fragments must be before the corresponding fragments in different digests are paired, was reported to be strongly size dependent. The error window was expanded by a factor of 1.3 for fragments from 400 to 600 bp, 1.2 for fragments from 600 to 800 bp, and 1.1 for fragments from 800 to 1000 bp. Moreover, it was necessary to introduce corrections for systematic differences between size estimates taken from two different gels. For the multiplexing procedure described here, the size estimates for fragments from 600 bp to over 23 kbp were in close agreement with actual sizes as determined from DNA sequence (Table I), and certainly within the error windows given above. The multiplexing procedure should also minimize errors introduced by gel-to-gel variations in mobility, because the standard and unknowns are always run in the same lanes. Kohara et al. established a physical map of almost the entire Escherichia coli chromosome by analysis of a large genomic library. In this case, partial restriction digests were used to generate patterns of fragments and the mapping was performed by agarose gel electrophoresis. The disadvantage of this approach is that fewer fragments are generated. However, this is compensated for by the fact that partial digests reveal the order of the fragments produced and thus greatly increase the amount of information relevant to the question of overlap between different DNA fragments.(ABSTRACT TRUNCATED AT 400 WORDS)
Benzothiazoles↗
Bacterial plaque and enamel caries.
A series of five experiments were done to investigate the relationship between bacterial plaque and enamel caries: 1) Topographic examination of the distribution of plaque and initial enamel caies demonstrated a close relationship between these two. 2) By using a method of caries-like lesion production in vitro, it was shown that plaques collected from caries-active, caries-free and periodontal diseased persons could produce caries-like lesions, but the lesions produced by periodontal plaque were shallower than others. 3) In testing the cariogenicity of different phases of plaque, it was found that the liquid phase is the active phase in the carious process. 4) Examination of the proteolytic action of plaque fluid showed no reaction between plaque fluid and proteinous substances in enamel. This result does not support Gottleib's proteolysis theory, especially as it applies to enamel cares. 5) An in vitro model of multibacterial artificial plaque was established. Caries-like lesions were produced in this model, and the structure of the plaque was found to be very similar to that produced naturally.
Adult↗
Stable fluorescent complexes of double-stranded DNA with bis-intercalating asymmetric cyanine dyes: properties and applications.
The synthesis, proof of structure, and the absorption and fluorescence properties of two new unsymmetrical cyanine dyes, thiazole orange dimer (TOTO; 1,1'-(4,4,7,7-tetramethyl-4,7- diazaundecamethylene)-bis-4-[3-methyl-2,3-dihydro-(benzo-1,3-thiaz ole)-2- methylidene]-quinolinium tetraiodide) and oxazole yellow dimer (YOYO; an analogue of TOTO with a benzo-1,3-oxazole in place of the benzo-1,3-thiazole) are reported. TOTO and YOYO are virtually non-fluorescent in solution, but form highly fluorescent complexes with double-stranded DNA (dsDNA), up to a maximum dye to DNA bp ratio of 1:4, with greater than 1000-fold fluorescence enhancement. The dsDNA-TOTO (lambda max 513 nm; lambda maxF 532 nm) and dsDNA-YOYO (lambda max 489 nm; lambda maxF 509 nm) complexes are completely stable to electrophoresis on agarose and acrylamide gels. Mixtures of restriction fragments pre-labeled with ethidium dimer (EthD; lambda maxF 616 nm) and those pre-labeled with either TOTO or YOYO were separated by electrophoresis. Laser excitation at 488 nm and simultaneous confocal fluorescence detection at 620-750 nm (dsDNA-EthD emission) and 500-565 nm (dsDNA-TOTO or dsDNA-YOYO emission) allowed sensitive detection, quantitation, and accurate sizing of restriction fragments ranging from 600 to 24,000 bp. The limit of detection of dsDNA-TOTO and YOYO complexes with a laser-excited confocal fluorescence gel scanner for a band 5-mm wide on a 1-mm thick agarose gel was 4 picograms, about 500-fold lower than attainable by conventional staining with ethidium bromide.
Benzoxazoles↗
[Histological study of the structure of artificial plaque].
Five cariogenic bacteria were used to produce a plaque, called artificial plaque, by sequential culture in vitro. The results showed that the artificial plaque is very similar to the natural one in morphology and structure. Artificial plaque may be taken as an excellent model in vitro for the studies on cariogenicity of dental plaque.
Dental Caries↗
[Study of enamel caries-lesion produced by artificial plaque].
The authors used the cariogenic bacteria isolated from human dental plaque to produce an artificial plaque which can produce carious lesion in vitro. Lesions on human enamel slabs produced by artificial plaque and single bacterium were observed under polarized light microscope and scanning electron microscope. The results showed that the characters of artificial carious lesions are very similar to natural enamel caries. It is very difficult to differentiate them under the microscopes. Compared with the lesions produced by single strain, the destructive fashion observed in lesions produced by artificial plaque is more similar to the changes produced by natural dental plaque.
Dental Caries↗
[The effect of plaque fluid on demineralization of enamel powder].
The aim of this study was to explore any substance in dental plaque which might affect the demineralization of enamel. Plaque fluid was prepared by centrifugation of pooled plaque from 56 young adults without periodontal diseases. Enamel was separated from healthy teeth of adolescents and crushed into powder. The enamel powder was treated separately by plaque fluid and synthetic plaque fluid (as a control, with similar calcium, fluoride content and pH as the natural). After this, the enamel powder was washed with PBS. Both the plaque fluid-treated and synthetic plaque fluid-treated enamel powder were demineralized by mixed organic acid (pH 4.5). The calcium content in both plaque fluids, PBS and organic acid after treatment with enamel powder was analysed by atomic absorption spectrophotometer. The results showed that there was no promoting effect in plaque fluid on demineralization of enamel, but, on the other hand, some protecting action was observed which might contribute to the presence of proteins in plaque fluid.
Adult↗
[An analysis of chemical oxygen demand, carbohydrate, IgG and IgA in extracellular fluid of bacterial plaque].
The chemical oxygen demand (COD) of extracellular plaque fluid was measured by potassium dichromate method. Micro-anthrone method and high performance liquid chromatography were used for measuring the carbohydrate content in the fluid. Immunochemistry system was used for measuring IgG and IgA contents in it. The results showed: (1) a high value of COD was found in the extracellular fluid, and it further increased with sugar-intake; (2) during resting stage, the content of carbohydrate measured by microanthrone method or high performance chromatography was very low, and there was no free glucose, fructose or sucrose; (3) no difference of IgG and IgA contents in plaque fluid between caries active (CA) and caries free (CF) subjects was found.
Adolescent↗
[The influence of Chinese Agkistrodon acutus enzyme (CAAE) on the functions of washed human platelets].
The effects of the activation and influence of CAAE on washed human platelets were investigated. Our findings were: (1) CAAE could induce aggregation and alpha-granule release reaction in the washed human platelet suspension; thus it could activate the platelets; (2) the aggregation effect of CAAE was inhibited by albumin and affected by Ca2+, Mg2+ concentration; (3) heparin and/or AT III did not inhibit the aggregation activation of CAAE, but alpha 2MG markedly inhibited it; (4) the aggregation activity of CAAE was associated with the serine protease activity. The mechanism of CAAE-induced aggregation mainly follows the prostaglandins-endoperoxides thromboxane A2 pathway.
Animals↗
[The effect of several acids and proteolytic enzymes on the production of artificial caries].
Human tooth slabs were used to observe the effect of several kinds of organic acids and proteolytic enzymes on the production of artificial caries of enamel. Acidic gels were made by formic, acetic and lactic acids separately or in mixed form. The experiments were done in a period of 10 days. After this the specimens were prepared in ground sections and observed under optic microscope. The depth of the artificial lesions was measured by a micrometric scale in the eye lens of the microscope. The enzymes used for investigation were papain, trypsin and collagenase. The surfaces of the tooth were treated with fresh enzyme solutions every day and then with mixed acid gels. This was done alternately every day in a period of ten days. The results showed that lesions produced by formic acid gel were deeper than those produced by other acids or mixed acid gels. No effect was observed on the depth of the lesion by enzymatic treatments.
Acids↗
[Scanning electron microscope observation on proximal enamel surfaces of normal teeth].
This observation was made on the proximal surfaces of normal permanent molars. Observations were concentrated mainly on those teeth with abraded contact areas on the mesial surface and the unabrasive distal surfaces if the partially or wholly embedded third molars. The results showed that the surfaces of the abraded contact areas were plain than those outside the contact. There were lots of pitted holes or fissures on the surfaces outside the contact areas. In the holes accumulations of bacteria could be seen. These holes and fissures could also be seen on the unexposed distal surfaces of the third molars, but no clear-defined traces of bacteria were observed in the holes.
Dental Enamel↗
[Effects of proteolytic enzymes on demineralization of enamel].
Papain, trypsin and collagenase were used in the experiment for the study of their effects on the demineralization of enamel surface by organic acids in vivo. No effect of any of the enzymes was observed. The use of papain and trypsin in treating tooth surfaces in vitro, no matter whether sodium bisulfite was used, showed no effect on the demineralization of the enamel by mixed organic acids. But, by the analysis of amino acids in the enzyme solutions before and after treating tooth surface, it was shown that some proteinous substances were destroyed. Accordingly, it can be suggested that the enzyme takes no part in the destruction of the inorganic tooth substance.
Dental Enamel↗