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Y J Duan

Publications and source records attributed to Y J Duan.

9 recordsLinked to original sources
PubMed1997

Stimulatory effect of fatty acid treatment on glucose utilization in human erythrocytes.

We previously reported that treatment of human erythrocytes with bee venom phospholipase A2 increased the rate of lactate production from glucose. This increase was suggested to be mediated through liberation of free fatty acids from membrane phospholipids. So, in the present study we examined the mechanism of stimulation of glycolysis by fatty acids. Treatment of intact erythrocytes with most of the 15 fatty acids tested resulted in stimulation of lactate production from glucose. Among the fatty acids tested, myristoleic acid showed the highest stimulatory activity. The ratio of moles of lactate produced to those of glucose utilized was about 1.9 in both myristoleic acid-treated and untreated cells. Treatment of erythrocytes with myristoleic acid did not affect the amount of 2,3-bisphosphoglycerate. Lactate production from D-glyceraldehyde, which is thought to be phosphorylated to D-glyceraldehyde 3-phosphate and then metabolized in the glycolytic pathway, was not at all affected by treatment of cells with myristoleic acid. The cross-over plot of glycolytic intermediates suggested that the enhancement of glycolysis was induced by activation of the 6-phosphofructokinase (PFK) step. Fatty acids incorporated into erythrocytes were found to be present predominantly in the cytoplasm rather than in the plasma membrane. The PFK activity, but not the hexokinase activity, in hemolysates was clearly increased by a set of fatty acids, and myristoleic acid was again the most potent. However, partially purified human erythrocyte PFK was not activated by the acid. We conclude that fatty acids stimulate glycolysis through activation of PFK in cooperation with some other component(s) in erythrocytes.

Enzyme Activation↗
PubMed1995

[Investigation of mortality among HIV-infected intravenous drug users in Ruili region of Yunnan province].

The investigation of death condition of HIV infected intravenous drug users (IVDU) was conducted with a retrospective cohort study in Ruili city of Yunnan province from 1989-Oct to 1993-Oct, the deaths among 395 HIV+ IVDUs add up to 61 and the mortality is 15.4%, which has significant difference compared to the death level of control cohort composed by 192 HIV- IVDUs (add up to 18). The relative risk of death is 1.6 (95% confidence interval 1.0-2.5). After classified by the cause of death, it was found that both maintain high accidence mortality caused mainly by narcotism, violence and suicide. But in death group caused by diseases, the mortality of HIV+ IVDU (8.4%) is much higher than HIV- IVDU (3.1%) (95% confidence interval 1.2-6.1). We also compared non-AIDS mortality between HIV+ and HIV- IVDU according to data of HIV/AIDS surveillance which showed 2 patients died of AIDS in HIV+ IVDU. The difference is also significant (13.8% in HIV+, but 7.9% in HIV- IVDU) and the relative risk is 1.7 (95% confidence interval 1.0-2.8). The results indicated that the lever of reported AIDS cases were probably lower than that of actual AIDS cases existing.

Adult↗
PubMed1993

Stimulatory effect of phospholipase A2 treatment on glucose utilization in human erythrocytes.

We examined whether modification of membrane phospholipids of human erythrocytes by hydrolysis with phospholipase A2 (PLA2 from bee venom) would affect glucose utilization, chosen as a typical model of intracellular metabolism, and, if so, intended to clarify the mechanism of the alteration of glycolysis. Treatment of erythrocytes with PLA2 induced a marked shape change (i.e., crenation) and significantly increased the rate of lactate production from glucose. Available evidence indicated that there is no relevance of this cell-shape change to the alteration of glycolysis. The lack of a detectable effect of papain treatment on glycolysis in PLA2-treated cells suggested that the increase in glycolysis by PLA2 treatment might not be caused by the conformational change of band-3 protein through modulation of membrane phospholipids. The result of the measurement of lactate production in the presence and absence of ouabain did not support the idea that hydrolysis of phospholipids by PLA2 treatment makes plasma membranes leaky to Na+ and consequently enhances glycolysis through activation of Na+/K(+)-ATPase. The action of PLA2 on glycolysis was abolished by extraction of free fatty acids in the cell membrane with bovine serum albumin. Loading erythrocytes with free fatty acid (oleic acid, linoleic acid, or arachidonic acid) caused a significant increase in glycolysis. Analysis of glycolytic intermediates suggested that the enhancement of glycolysis was induced by activation of 6-phosphofructokinase. The data, thus, indicate that treatment of human erythrocytes with PLA2 significantly accelerates glucose utilization and suggest that the stimulation of glycolysis is caused by activation of 6-phosphofructokinase through liberation of free fatty acids of membrane phospholipids by PLA2.

Adult↗
PubMed1992

Anomeric preference of glucose utilization in rat erythrocytes.

The beta-anomer of glucose relative to the alpha-anomer was more rapidly metabolized into lactate by rat erythrocytes at 37 degrees C (beta/alpha ratio = ca. 1.3): the amounts of alpha- and beta-D-glucose metabolized into lactate during 3 min were 0.21 and 0.27 mumol/gHb, respectively. Also, the transport of beta-D-glucose into erythrocytes was more rapid than that of alpha-D-glucose: the amounts of alpha- and beta-D-glucose transported into erythrocytes during 3 min were approximately 3.5 and 5.0 mumol/gHb, respectively. Glucose phosphorylation by rat erythrocyte hexokinase (i.e., a possible rate-limiting step in glycolysis) occurred at higher velocities with the beta-anomer than with the alpha-anomer (beta/alpha ratio = 1.28). The Km value of hexokinase for either anomer of glucose was 53 microM. The glucose concentrations in erythrocytes incubated with alpha- and beta-D-glucose reached about 1 mM in 1 min, indicating that hexokinase is almost completely saturated with glucose within less than 1 min. The results suggest that glucose phosphorylation and glucose transport are major and minor determinants, respectively, for the anomeric preference of glucose utilization in rat erythrocytes.

Animals↗
PubMed1990

Presenile (early ageing) changes in tissues of Kaschin-Beck disease and its pathogenetic significance.

The selenium level and activity of glutathione peroxidase in blood of children living in Kaschin-Beck disease (KBD) endemic areas were lower than that in nonendemic areas. KBD children were deficient in selenium, their lipid components, structure and function of the red cell membrane and cartilage tissue were abnormal. That is, the phospholipid (PL) content in the tissues of the patient was less than that of the controls in endemic and non-endemic areas. Especially as the phosphatidylcholine (PC) content decreased significantly, but sphingomyelin (SM) increased, the molar ratio of SM/PC and cholesterol (Ch)/PL increased. Increase of acanthocyte content was seen under the electron microscope and the fragility of erythrocytes was also increased. It indicated that there were membrane defects and membrane damage in KBD. At the same time, the sulfation extent of mucopolysaccharides in cartilage of patients was lower, and the collagen content was higher than that of controls. The presenile changes in lipid composition, structure and function of biomembranes and cartilage metabolism of KBD are very significant in studies on the aetiological pathogenesis of KBD and other ageing diseases.

Aging↗
PubMed1988

Purification and characterization of a novel monomeric glutathione peroxidase from rat liver.

A novel glutathione peroxidase, which is active toward hydroperoxides of phospholipid in the presence of a detergent, has been purified to homogeneity from a rat liver postmicrosomal supernatant fraction by ammonium sulfate fractionation and three different column chromatographies. From a DE52 column, glutathione peroxidase active toward phosphatidylcholine dilinoleoyl hydroperoxides was eluted in one major and two minor peaks. The enzyme in the major peak was found to be separated from the "classic" glutathione peroxidase and glutathione S-transferases and further purified by Sephacryl S-200 and Mono Q column chromatographies. The purified enzyme was found to be homogeneous on polyacrylamide gel electrophoresis under nondenaturing conditions as well as that in the presence of sodium dodecyl sulfate. The molecular weight of the enzyme as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis was 22,000, and that by gel filtration was comparable, indicating that the enzyme protein is a single polypeptide. The purified enzyme was found to catalyze the reduction of phosphatidylcholine dilinoleoyl hydroperoxides to the corresponding hydroxy derivatives. The isoelectric point of the enzyme was found at pH 6.2, and the optimum pH for the enzyme activity was 8.0. The enzyme was active toward cumene hydroperoxide, H2O2, and 1-monolinolein hydroperoxides in the absence of a detergent. The enzyme activity toward phospholipid hydroperoxides was minute in the absence of a detergent but was remarkably enhanced by the addition of a detergent. From these results, the presently purified enzyme is obviously different from the classic glutathione peroxidase and also from phospholipid hydroperoxide glutathione peroxidase purified from pig heart (Ursini, F., Maiorino, M., and Gregolin, C. (1985) Biochim. Biophys. Acta 839, 62-70), though considerably similar to the latter.

Animals↗
PubMedDate not supplied

Serotyping of chlamydial clinical isolates from birds with monoclonal antibodies.

Forty-nine avian chlamydial strains, isolated mainly from various regions in France and from different species of birds, were analyzed and tested with a panel of nine monoclonal antibodies (MAbs) by the indirect microimmunofluorescence test (MIF). The MAbs included five serovar-specific MAbs, three MAbs raised against Chlamydia psittaci and Chlamydia pecorum ovine strains, and one genus-specific MAb. Of the 49 isolates, 41 came from parrots or budgerigars; the rest were from pigeons, a canary, a duck, and a dove. Two additional strains were from unknown hosts. Most of these avian strains were successfully serotyped according to their reactions with five serovar-specific MAbs by the MIF test. The serovars of 44 strains were determined: 39 were of serovar A, 3 of serovar B, and 2 of serovar E. The remaining five isolates were unclassified because they did not react with any of five serovar-specific MAbs but did react with genus MAb or the MAbs produced with ovine strains. The five unclassified isolates (two from budgerigars, two from Gabon gray parrots, and one from a duck) indicate that one or more additional serovars of C. psittaci exist in birds. The heterogeneity within each subgroup was evident because the 49 avian isolates gave 10 subgroups when the results of the five serovar-specific MAbs were combined with results from the three MAbs produced with ovine strains. This heterogeneity of the serovar isolates, as shown by the combination of MAbs, could provide strain markers very useful for epidemiologic studies.

Animals↗