index.php:

$smarty = new Smarty;
$smarty->assign("articleTitle", "Two Soviet Ships Collide - One Dies. Enraged Cow Injures Farmer with Axe.");
$smarty->display("index.tpl");

index.tpl:

{$articleTitle}
{$articleTitle|count_sentences}

OUTPUT:

Two Soviet Ships Collide - One Dies. Enraged Cow Injures Farmer with Axe.
2