How to put the text and symbols “Italic” quickly?

The following is my original texts.

\textbf{The Interior Dirichlet Problem:} Given $f\in C(S)$, find
$u\in C(\overline{\Omega})$ such that $u$ is harmonic on $\Omega$
and $u=f$ on $S$.


Instead of using \emph{} word by word and symbol by symbol, how can I quickly get everything Italic quickly?

I have tried the \newtheorem command. But the font would be different from the desired one. What's more, I am not able to get rid of the period automatically added by the macro.

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You could apply one of the techniques proposed here tex.stackexchange.com/q/16996/1998 – pmav99 Jun 25 '11 at 23:26

\newenvironment{problem}[1]
\textbf{#1:}\em\ \ignorespaces}

...

\begin{problem}{The Interior Dirichlet Problem}
Given $f\in C(S)$, find $u\in C(\overline{\Omega})$ such
that $u$ is harmonic on $\Omega$ and $u=f$ on $S$.
\end{problem}


However, you can also put everything after the colon as argument to \emph or say {\em Given $f\in C(S)$, ... on $S$.}

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I thought use of \em et al was discouraged? – You Jun 25 '11 at 21:19
@You: not at all. But it's preferable to use it only in the definition of environments. For a "one shot" application it's handier than a very long argument to \emph. – egreg Jun 25 '11 at 21:24
@You -- \em isn't the best command to use here, although it works. \itshape is the preferred latex equivalent. – barbara beeton Jun 26 '11 at 13:48