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Biomedical subjects

Y B Yan

Publications and source records attributed to Y B Yan.

11 recordsLinked to original sources
PubMed2001

Two-phase unfolding pathway of ribonuclease A during denaturation induced by dithiothreitol.

The dynamics of the unfolding process of bovine pancreatic ribonuclease A (RNase A) unfolded by dithiothreitol (DTT) at a low concentration of 1:30 were investigated in alkaline phosphate-buffered saline solutions at 303K and 313K by using proton nuclear magnetic resonance ((1)H NMR) spectra. Three NMR spectral parameters including Shannon entropy, mutual information, and correlation coefficient were introduced into the analysis. The results show that the unfolding process of RNase A was slowed to the order of many hours, and the kinetics of the unfolding pathway described by the three parameters is best fit by a model of two consecutive first-order reactions. Temperature greatly influences the rate constants of the unfolding kinetics with different temperature effects observed for the fast and the slow processes. The consistencies and the differences between the three sets of parameters show that they reflect the same relative denaturation pathway but different spectra windows of the unfolding process of RNase A. The results suggest that the unfolding process of RNase A induced by low concentrations of DTT is a two-phase pathway containing fast and slow first-order reactions.

Animals↗
PubMed2001

[Detection of Cre recombinase activity in Mx-Cre transgenic mice induced by INF in vitro].

The Cre recombinase and its activity in C57-TgN(Mx-Cre) transgenic mice is studied by polymerase chain reaction (PCR), Western blot, immunohistochemistry, immunogold electron microscopy and Southern blot. C57-TgN(Mx-Cre) transgenic mice harbouring cre gene in genomic DNA is demonstrated by PCR, and these mice which are induced by INF-alpha 1b could express Cre recombinase, which is confirmed by Western blot. With immunohistochemistry, we find that the Cre recombinase expresses in hepatocyte cytoplasm and nuclear of C57-TgN(Mx-Cre) transgenic mice. Cre recombinase expressed in hepatocyte cytoplasm and nuclear is further confirmed by immunogold electon microscopy. And it is supported that the Cre recombinase which is created from C57-TgN(Mx-Cre) transgenic mice induced by INF-alpha 1b can direct DNA recombination reaction in vitro. All evidence leads us supporting the view that the Cre recombinase expressed in C57-TgN(Mx-Cre) transgenic mice has activity. Thus we find a method to detect the activity of Cre recombinase in vitro.

Animals↗
PubMed2001

[Estimating cardiovascular age of civil flying personnel by means of heart rate and blood pressure variability analysis].

Objective. To estimate the cardiovascular age of civil flying personnel by means of heart rate and blood pressure variability analysis and to evaluate its significance in aviation medicine. Method. First, heart rate variability (HRV), blood pressure variability (BPV) and spontaneous baroreflex sensitivity (BRS) were analyzed among 89 healthy civil flying personnel by using conventional AR spectral analysis and sequence method respectively. Then, principal component analysis was conducted over original and derived variables of HRV and BPV spectral and BRS data. Finally, by the use of multiple regression in which the chronological age acted as the dependent variable and the components significantly related to age were used as the regressors, the equation for estimating the cardiovascular age was established. Result. Only seven principal components can exactly reflect the same information of autonomic regulatory function which was embodied in the 17 variables of HRV and BPV spectral and BRS parameters. Among the seven principal components, the PC2orig, PC4orig and PC2deri were negatively correlated with chronological age (P<0.05), whereas the PC3orig was positively correlated with the chronological age (P<0.01). The cardiovascular age derived from the equation was significantly correlated with the chronological age of the civil flying personnel (r= 0.73, P<0.01). Conclusion. The cardiovascular age estimated by means of a multi-variate analysis of HRV, BPV and BRS can be treated as a comprehensive indicator reflecting the age dependency of autonomic regulatory function of cardiovascular system in healthy civil flying personnel, and its interpretation and significance in application are surely worthy of further and fully dedicated efforts.

Adult↗
PubMed2000

Dynamic accumulation and degradation of poly(3-hydroxyalkanoate)s in living cells of Azotobacter vinelandii UWD characterized by (13)C NMR.

The synthesis and degradation of poly(3-hydroxybutyrate) (PHB) and poly(3-hydroxybutyrate-co-hydroxyvalerate) (P(HB-co-HV)) by Azotobacter vinelandii UWD were investigated using natural abundance solution (13)C nuclear magnetic resonance (NMR) in vivo in shake flask culture and in fermenter culture. The synthesis and the degradation of poly(3-hydroxyalkanoate)s (PHA) monomers hydroxybutyrate (HB) and hydroxyvalerate (HV) had different rates. The amount of HB and HV increased dramatically in the initial degradation stage. The results suggest that the intracellular PHA of strain UWD was the subject of dynamic metabolic processing. (13)C NMR in vivo analysis provided a rapid, easy, accurate, non-destructive method to obtain valuable information on the metabolism of PHA.

Azotobacter vinelandii↗
PubMed1994

[Molecular recognition between GlcNAc and Plasmodium falciparum merozoites].

In this study p-aminophenyl-2-acetamido-2-deoxy-beta-D-glucopyranoside was bound covalently to bovine serum albumin (BSA) to form neoglycoprotein (GlcNAc-BSA). The antigenicity of BSA and the pyranose structure of the sugar was preserved. By using the neoglycoprotein antibody against BSA and staphylococcal protein A-gold (SPA-gold), Plasmodium falciparum FCC-1/HN merozoites were immunolabeled. The labelled sample was observed under transmission electron microscope (TEM). The TEM pictures showed that colloidal gold pellets were distributed all over the merozoite surface. This is the first report on the direct experimental evidence of molecular recognition between GlcNAc-BSA (or GlcNAc) and Plasmodium falciparum merozoites. But free GlcNAc or even GlcN can inhibit the immunolabeleation. The results support the hypothesis that, besides N-acetylneuraminic acid, GlcNAc is involved as another recognized site on GPA for Plasmodium falciparum. Thus we further confirmed that N-acetyl of GlcNAc is not necessary for the recognition.

Acetylglucosamine↗
PubMed1992

[Characterization of a surface antigen of Plasmodium falciparum merozoite with monoclonal antibody].

The monoclonal antibody (McAb) designated as C6 against erythrocytic stage of Plasmodium falciparum Fcc7801/HN showed significant growth inhibition of P. falciparum in vitro, having cross immunofluorescence reaction with P. falciparum Fcc-1/HN, Fcc7802/HN, Fcc8703/JS and P. berghei, P. cynomolgi. McAb C6 bound to the antigen distributed evenly over the entire surface of merozoites of P. falciparum, as demonstrated by immunoelectron microscopy. The McAb C6 also recognized a single protein of 71 kDa of P. falciparum by Western blotting. This antigen might be a candidate of malaria vaccine.

Animals↗
PubMed1991

[Molecular recognition between glycophorin A and Plasmodium falciparum merozoites].

By using purified human erythrocyte membrane glycophorin A (GPA) and glycopeptide of GPA, antibodies against GPA and against GPA-glycopeptide, and SPA-colloidal gold, Plasmodium falciparum FCC-1/HN merozoites were immunolabeled. The labeled samples were observed under transmission electron microscope (TEM). The TEM pictures showed that colloidal gold pellets were distributed over all of the merozoite surface. This is the first report on the direct experimental evidence of molecular recognition and combination between GPA (or glycopeptide of GPA) and Plasmodium falciparum merozoites. The results strongly support the hypothesis that GPA is involved as a recognized receptor on erythrocytes for Plasmodium falciparum and the glycopeptide domain of GPA is the receptor site for Plasmodium falciparum.

Animals↗