How to find out when next() reaches the end, then go to the first item

I am displaying a series of elements using the next() function. Once I reach the end though, I want to go to the first element. Any ideas?

Here's the code:

//Prev / Next Click
$('.nextSingle').click( function() {
    //Get the height of the next element
    var thisHeight = $(this).parent().parent().parent().next('.newsSingle').attr('rel');
    //Hide the current element
    $(this).parent().parent().parent()
        .animate({
            paddingBottom:'0px',
            top:'48px',
            height: '491px'
        }, 300) 
        //Get the next element and slide it in      
        .next('.newsSingle')
        .animate({
            top:'539px',
            height: thisHeight,
            paddingBottom:'100px'
        }, 300);
});

Basically I need an "if" statement that says "if there are no remaining 'next' elements, then find the first one.

Thanks!