| Summary: | 碩士 === 台北醫學院 === 醫學研究所 === 86 === The infection of Helicobacter pylori is related with cell apoptosis,
but the mechanism of the phenomenon had not been well established. The
activation of Sphingomyelinase (SMase) has been implicated as the cause
of elevation of ceramide level and consequently of apoptosis. We
demonstrate for the presence of two isoform SMase in H. pylori.
One is a membrane-bound Mg2+dependent SMase with optimal activity
3 nmole/hr/mg at pH 7; the other is a cytosolic Mg2+ independent
SMase with optimal activity 0.6 nmole/hr/mg at pH 5. EDTA possessed
significantly inhibitory effect in the neutral Mg2+dependent SMase.
Both of the enzyme was inhibited by bisalumin, which was a bismuth
salt, usually used to cure the infection of H. pylori. By Western
blot analysis, the SMase of H. pylori and Bacillus cereus were showen
to be antigenically related and to have a similar denature molecular
weight of 28kDa.
We use the extracted surface protein and H. pylori to mimic the
situation of H. pylori infecting GI tract. The cell membrane blebing
was similar to the ceramide induced after administration of the
0.17mg/ml surface protein and 3.2x108 H. pylori infected. The
Hoechest staining assay showed that dose of 0.17mg/ml surface protein
and 3.2x108H. pylori intact cause AGS cell apoptosis are similar to
induced by ceramide .After treatment for 24 hours of extracted
0.17mg/ml surface protein and 3.2x108H. pylori, the AGS cell
viability was decreased 60%. Then change the fresh medium, the cell
viability was decreased to 0% after continued 24 hours culture.
Based on our results, we conclude that the apoptosis of H. pylori
infected involved the ceramide hydrolyzed by SMase.
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