Escaping the trademark symbol with MySQL

[eluser]TWP Marketing[/eluser]
I'm stumped. I want to input the trademark symbol (&trade as part of a textarea input string:

Code:

"This is my trademark: TWP Marketing™ or TWP Marketing™."

however I can only write this to the db one time.

I'm using htmlentities () to encode to the db and html_entity_decode() on extraction from the db. This works on such HTML as the paragraph symbols and less-than/more than, etc. but fails for the trademark symbol.

On the first db operation (insert), the text is stored, correctly escaped (phpMyAdmin shows it to be so). When I read that record back into the same textarea input field, the actual trademark symbol is displayed:

"This is my trademark: TWP Marketing™ or TWP Marketing™."

The generated HTML still shows the properly escaped code for the symbol.

If I update that record, the text stored in the db is truncated just before the first trademark symbol:

"This is my trademark TWP Marketing

Can anyone suggest what is happening here?