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Biomedical subjects

S J Jeng

Publications and source records attributed to S J Jeng.

9 recordsLinked to original sources
PubMed1997

Dietary fat affects lipids and anti-cardiolipin antibody levels in autoimmune-prone NZB/W F1 mice.

Studies in autoimmune-prone NZB/W F1 mice have demonstrated that the amount of dietary fat can affect autoantibody production and the disease course of autoimmune diseases. Anti-cardiolipin antibodies have been found to play a major role in thrombus formation and the increase of abortion rate in both human lupus patients and murine lupus. The present study investigated further the effect of dietary fat on lipid and anti-cardiolipin antibody production in autoimmune-prone mice. Two groups of NZB/W F1 mice were fed on diets containing 200 g dietary fat/kg and 50 g dietary fat/kg respectively, the fat being composed of equal amounts of lard and soyabean oil. Serum levels of lipids, immunoglobulin (Ig) anti-single stranded DNA and anti-cardiolipin antibodies were followed regularly every month and mice were killed for in vitro experiments after 5 months on the experimental diets. The results showed that serum triacylglycerol concentration was lower in mice fed on the high-fat diet than in those fed on 50 g fat/kg. There was no significant difference in hepatic lipid contents; however, the fatty acid contents were different between these two groups. Hepatic linoleic acid (18:2n-6) and arachidonic acid (20:4n-6) concentrations were higher in mice fed on the high-fat diet. There were no significant differences in serum IgM concentrations or IgM anti-cardiolipin antibody levels between these two groups. However, IgG anti-cardiolipin antibody levels were higher in mice fed on the high-fat diet at the age of 3-4 months. Total serum IgG concentration was noted to be higher, but in contrast, serum IgA was lower, in the high-dietary-fat group. These findings suggest that high dietary fat may affect lipid metabolism and autoantibody levels in autoimmune diseases.

Animals↗
PubMed1996

Dietary fat influences Ia antigen expression, cytokines and prostaglandin E2 production of immune cells in autoimmune-prone NZB x NZW F1 mice.

To elucidate further the influences of dietary fat on autoimmune diseases, two groups of NZB/W F1 mice were fed with diets containing 200 g dietary fat/kg and 50 g dietary fat/kg (control) respectively. The difference in energy intake between these two groups was compensated with carbohydrate. Mice were bled regularly every month and some of them were killed for in vitro experiments after 5 months experimental diets. Higher immunoglobulin (Ig)M and IgG anti-double stranded DNA antibody levels, shortened life span and worsened proteinuria were noted in mice fed on the high-fat diet compared with those fed on 50 g dietary fat/kg. Phenotypic analyses of spleen cells and peritoneal exudate cells showed that the percentage of CD5+ B cells and the mean fluorescent intensity of major histocompatibility molecules on the surface of both types of cells were higher in mice fed on the high-fat diet. In general, higher type 2 T-helper cell activity was noted in mice fed on the high-fat diet. In addition, cytokines such as interleukin-6, tumour necrosis factor-alpha and prostaglandin E2 (PGE2) produced by lipopolysaccharide-stimulated peritoneal exudate cells were also higher in the high-dietary-fat group. These studies suggest that high dietary fat and its related PGE2 level might have a critical effect on the frequency of CD5+ B cells, cytokine production, macrophage function and subsequent autoimmune regulation in autoimmune mice.

Animals↗
PubMed1985

Interaction of [3H]arylazido aminopropionyl ATP ([3H]ANAPP3) with P2-purinergic receptors in the smooth muscle of the isolated guinea-pig vas deferens.

Following its photolysis in the presence of the isolated guinea-pig vas deferens, the ATP photoaffinity label ANAPP3 produces a specific antagonism of adenine nucleotide-induced contractile responses which are mediated by P2-purinergic receptors. To characterize the site of covalent photoincorporation of ANAPP3, intact vasa deferentia were treated with [3H]ANAPP3 and samples of homogenate, cytosol and a crude membrane fraction were analyzed using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Photolysis of [3H]ANAPP3 (10(-5) M; 3.0 mu Ci/ml) resulted in the incorporation of radioactivity into cellular components with apparent molecular weights of 54-66 and 43-57 kilodaltons. The photoincorporation of [3H]ANAPP3 was associated with the crude membrane fraction and not the cytosol, was reduced in the presence of ATP in an ATP-concentration-dependent manner, was lessened following pretreatment of the tissues with photolyzed nonradiolabeled ANAPP3, and was unaffected by the nucleoside transport inhibitor, dipyridamole. In tension studies on the same tissues the presence of ATP resulted in a concentration-dependent reduction in the initial contractile response to [3H]ANAPP3 the response to 3H was antagonized in tissues which had been pretreated with nonradiolabeled ANAPP3, and dipyridamole had no effect on the contractile response to [3H]ANAPP3. According to several criteria these findings indicate that the antagonism by photolyzed ANAPP3 of adenine nucleotide-induced responses is a direct result of the covalent insertion at or near the recognition site of cell-surface P2-purinergic receptors.

Adenosine Triphosphate↗
PubMed1983

Photoaffinity labeling: theory and practice.

The potential for generating a reactive reagent in situ by photoexcitation and for labeling sites not containing reactive nucleophilic residues provides photoaffinity labeling with a special advantage in the study of ligand-binding sites. There are, however, problems in the application of the photoaffinity technique. A number of concerns about this approach are examined by using as a background studies with arylazido-beta-alanyl nucleotide probes developed in this laboratory. It is concluded that photoaffinity labeling is likely to emerge as one of the major techniques for elucidating structure-function relationships within biological membranes. In the future the design of photoprobes with shorter activation half-lives may make it possible to investigate time-dependent (i.e., conformational) changes occurring at the active site of enzymes and within complex ligand-binding sites.

Adenosine Triphosphate↗
PubMed1975

The use of aryl azido ATP analogs as photoaffinity labels for myosin ATPase.

The synthesis of ATP analogs containing a photoactive aryl azido grouping coupled to the 3' hydroxyl of ATP is described. The potential effectiveness of these analogs in the investigation of nucleotide-binding regions is outlined and this effectiveness demonstrated by their photodependent inhibition of subfragment 1 ATPase. The use of 14C-labeled azido ATP demonstrates an almost stoichiometric covalent binding of the analog. Because of their potential application to other systems, a number of reactions describing the reactivity of the 3' hydroxyl of the nucleotide ribose are outlined in an Appendix.

Adenosine Triphosphatases↗