Search PubMed⌕ Search

Biomedical subjects

S Yao

Publications and source records attributed to S Yao.

162 records · Page 9Linked to original sources
PubMed1994

Failure to detect Trichinella spiralis p43 in isolated host nuclei and in irradiated larvae of infected muscle cells which express the infected cell phenotype.

Infection by Trichinella spiralis induces host muscle cells to become repositioned within the cell cycle and to lose differentiated skeletal muscle characteristics. Antibodies to a 43-kDa excretory-secretory (ES) protein (p43) also bind to infected host cell nuclei. Neither the identity of these nuclear antigens nor their role in inducing the infected cell phenotype is known. To address these issues, infected cell nuclei were isolated and nuclear antigens analyzed with several antibody preparations to p43. Four antibody preparations to p43 recognized 43-, 45-, 50-, 67- and 71-kDa proteins in ES extracts. The prominent proteins recognized by these antibodies in host nuclear antigen extracts were 71, 79, 86 and 97 kDa. Less prominent proteins of approximately 43 and 45 kDa were detected in nuclear extracts. However, antibodies which specifically recognized p43 failed to bind detectably with in situ and isolated host nuclei and nuclear extracts. Expression of p43 was analyzed in host cells infected by newborn larvae irradiated with 60Co. This treatment prevented expression of detectable levels of p43 in resulting muscle larvae, while infected muscle cells displayed typical infected cell characteristics. However, anti-p43 antibodies which recognized multiple ES and nuclear proteins did stain nuclei of irradiated larva-infected cells, albeit at reduced levels. The results raise doubts that p43 is required for induction of the infected cell phenotype. Nevertheless, nuclear antigens recognized by anti-p53 antibodies remain as candidates for influencing this phenotype.

Animals↗
PubMed1994

[Chromosome abnormality and dominant lethality among the F1 generation of mice after gamma-ray irradiation].

This paper reports on the relationship between chromosome abnormality or dominant lethality and dosage of 0.15-1.56 Gy 60Co gamma-ray irradiation in the F1 generation of mice. The irradiated female mice were mated at 7-12 days after irradiation with unirradiated or irradiated at 22-28 days after irradiation. The fetuses aged 9.5-11 days were recovered from the uterus and lethality and chromosome aberrations were investigated. Results suggested that the rate of fetus with chromosome abnormality increased with dose, and so did dominant lethality rate, and both could fit linear relationship. Increase of translocation carriers in the F1 mice was observed at the dose level of over 1.0 Gy.

Animals↗
PubMed1993

DNA triple-helix specific intercalators as antigene enhancers: unfused aromatic cations.

Triple-helical structures involving the interaction of an oligonucleotide third strand with a duplex nucleic acid sequence have recently gained attention as a therapeutic strategy in the "antigene" approach [cf. Helene, C. (1991) Eur. J. Cancer 27, 1466-1471]. This method utilizes the triple helix formed from the cellular duplex and an added third strand to directly regulate the activity of a selected gene. The limited stability of nucleic acid triple-helical interactions, particularly if the third strand has backbone modifications such as methylphosphonate or phosphorothioate substitutions, is a limiting condition for the use of this approach. We have designed and synthesized compounds, on the basis of the following three criteria, that we feel should provide selective interactions and significant stabilization of triplexes: appropriate aromatic surface area for stacking with triplex bases in an intercalation complex, positive charge, and limited torsional freedom in the aromatic system to match the propeller twist of the triple-base interactions in the triplex. A series of quinoline derivatives with an alkylamine side chain at the 4-position and with different aryl substituents at the 2-position has been synthesized as our first compounds. A 2-naphthyl derivative provides significant and selective stabilization of the triplex. In a 0.2 M NaCl buffer, the naphthyl derivative increased the Tm for the triplex (triplex to duplex and third strand transition) by approximately 30 degrees C more than the Tm increase for the duplex (duplex to single strands transition). Spectral changes and energy-transfer results indicate that the naphthyl compound and related derivatives bind to the triplex by intercalation.(ABSTRACT TRUNCATED AT 250 WORDS)

DNA↗
PubMed1993

Flow-selective pulse sequences.

A series of pulse sequences is described which selectively excite signals only from flowing spins. The method is based on the binomial selective excitation sequences employed for solvent suppression in NMR spectroscopy, combined with 180 degrees refocusing of chemical shift and static field inhomogeneity effects and the application of bipolar gradients to distinguish stationary from flowing spins. The effectiveness of the method is demonstrated by experiments on a simple flow phantom.

Humans↗
PubMed1993

Immunological status and pathology of coxsackie B viral myocarditis and dilated cardiomyopathy.

The changes in 15 cases of viral myocarditis and 28 cases of dilated cardiomyopathy were reported and compared, which were the pathological changes of endomyocardial biopsy; NK cells activity; % of peripheral T lymphocytes and its subsets determined by using OKT3,4,8 (OKT3-peripheral total lymphocytes; OKT4-helper cells; OKT8-suppressive cells) monoclonal antibody; values of immunoglobulin IgG, IgA, IgM; titer of coxsackie B antibody neutralization test. And a discussion on their relationship was included.

Adolescent↗
PubMed1992

Laser photolysis of cytosine, cytidine and dCMP in aqueous solution.

Laser photolysis of cytosine and cytosine derivatives (cytidine and 2'-deoxycytidine-5'-monophosphate) using acetone as a sensitizer have been carried out in aqueous solution using a KrF laser. The absorption spectra of triplet states of cytosine and cytosine derivatives have been observed for the first time. From detailed kinetic analyses, the reaction mechanisms including triplet-triplet excitation transfer, and intramolecular excitation transfer within the exciplex arising from the interaction of triplet acetone with cytosine and cytosine derivatives, have been suggested. Accordingly, a series of kinetic parameters have also been obtained.

Cytidine↗
PubMed1992

Heterogeneity among heat-labile enterotoxins produced by porcine enterotoxigenic Escherichia coli.

The heat-labile enterotoxins (LT) produced by various porcine strains (LTp) of enterotoxigenic Escherichia coli were purified to homogeneity and their molecular properties were compared with each other. By double gel diffusion and rabbit skin permeability test, LTps from WT-1 (LTp-WT-1) and BO-149 (LTp-BO-149) strains were antigenically and biologically identical. By polyacrylamide gel electrophoresis with sodium dodecyl sulfate (SDS), the mobilities of A and B subunits of LTp (BO-149) were identical to those of LTp (WT-1). However, on polyacrylamide gel electrophoresis without SDS, LTp (BO-149) and LTp (WT-1) differed in mobility, suggesting their molecular differences. Though the pI value of the B subunit of LTp (BO-149) was identical to that of LTp (WT-1), the pI value of the A subunit of LTp (BO-149) was higher than that of LTp (WT-1). These data suggest that there is molecular heterogeneity among LTps produced by the two porcine enterotoxigenic Escherichia coli strains.

Animals↗
PubMed1992

A molecular mechanics investigation of RNA complexes. I. Ethidium intercalation in an HIV-1 TAR RNA sequence with an unpaired adenosine.

Nucleic acid complexes with ethidium intercalated into different sites in a segment of HIV-1 TAR RNA with an unpaired A base, along with corresponding complexes with a normal RNA sequence without an unpaired base were studied by molecular mechanics energy minimization methods. Different intercalation geometries as well as different orientations of the ethidium molecule in the intercalation sites were tested. A general binding affinity enhancement for the ethidium binding to the bulge sequence compared with the normal RNA segment was obtained. With the unpaired adenosine base stacked in the duplex, the binding site adjacent to the 3' side of the bulge was found to be the most energetically favorable binding site, and the intercalation site 5' to the bulge in the same sequence is much less favorable. Unique correlated backbone conformational changes on binding of ethidium to the intercalation site 3' to the bulge were found to relieve backbone strains caused by the stacking of the unpaired base into the helix. These backbone conformational changes present a plausible molecular basis for the experimentally observed ethidium binding preference in this bulge RNA segment (L.S. Ratmeyer, R. Vinayak, G. Zon and W.D. Wilson, J. Med. Chem. 35, 966, 1992).

Base Sequence↗
PubMed1991

Clinical and experimental observations on treatment of peptic ulcer with wei yang an (easing peptic-ulcer) capsule.

The therapeutic effects of peptic ulcer treated with cimetidine and Wei Yang An were compared clinically and experimentally by the double blind method. Results showed that the effects of the two are similar, but the long-term effect of Wei Yang An was better. Wei Yang An was also good for most cimetidine resistant ulcers, with few side effect. Animal experiment showed that Wei Yang An inhibited the ulcers.

Adult↗
PubMed1990

Evidence that combined thromboxane A2 and serotonin receptor blockade might prevent coronary artery thrombosis and the conversion from chronic to acute coronary heart disease syndromes.

Evidence that combined thromboxane A2 and serotonin blockade may prevent coronary artery thrombosis and the conversion from chronic to acute coronary heart disease syndromes is considered. Available data from clinical and experimental animal studies are consistent with the hypothesis that interference with thromboxane and serotonin's contributions to platelet aggregation and dynamic coronary artery constriction might prevent the conversion from chronic to acute disorders, including the development of unstable angina and myocardial infarction in some patients at risk. Substantial protection preventing the conversion from stable to unstable angina and myocardial infarction may very well require both thromboxane and serotonin receptor antagonists or the combination of a thromboxane synthesis inhibitor and receptor antagonist with a serotonin receptor antagonist. Future clinical studies should test this hypothesis directly.

Animals↗
PubMedDate not supplied

Bulk acoustic wave bacterial growth sensor applied to analysis of antimicrobial properties of tea.

A bulk acoustic wave (BAW) bacterial growth sensor has been proposed for study of inhibitory effects of tea by continuous monitoring of disturbances in Proteus growth in the aqueous extracts of various teas, e.g. green tea, Fuzhuan brick tea, Oolong tea, Kudin tea, and black tea. The kinetic parameters, e.g. asymptote (A), maximum specific growth rate (microm), lag time (lambda), and generation time (g), accurately estimated by using the growth response model, have been first used to characterize antimicrobial properties of tea. All of the parameters were changed via the inhibitory effects by tea. Green tea gives the weakest inhibitory action while others show stronger inhibitory actions. These inhibitory effects have also been examined by using the pour plate count technique. Both of the results show that, in addition to the antimicrobial properties of tea polyphenols and catechins, etc., the inhibitory effects may be attributed to the metabolites produced during the fermentation processing of these teas except green tea. The conventional disk diffusion test has been used to determine the minimum inhibitory concentration (MIC) against P. rettgeri. The MICs of green tea, Fuzhuan brick tea, Oolong tea, and black tea were found to be 1113, 818.0, 681.2, and 510.4 microg/mL, respectively. The BAW bacterial growth sensor has shown to have advantages over other techniques, including the disk diffusion test, photometry, and the impedance method.

Acoustics↗