[Zope] How to get Query string in bold

Hi, I was wondering if anyone could help me with this. I let people search in all the Objects in a folder (with newsitems) I then would like to display the results and show the first 300 chars of the news message. This far everything works fine. What I would like to do now is if the first 300 chars of the message conain their search string to show this in bold. Does anybody have a tip for me on this subject? Greetz, James