$str=~s/(iteration)(.*)/<B> \U$1\E$2 <\/B>/g;

##</code><code>##

$str=~s/(iteration)(.*)/"<B> ".uc($1).$2." <\/B>"/ge;

##</code><code>##

$str=~s/(iteration)(.*)/<B> @{[uc($1)]}$2 <\/B>/g;