function load_regioes(filtro, combo) {

		//faz requisição xmlhttp
		var http = getHTTPObject();
		var url = "/xmlhttp/xml_regioes.php?idCidade=" + filtro;
		http.open("GET", url, false);
		http.send(null);
		var httpResponse = http.responseXML;


		//limpa combo
		combo.value="0";
		j=0;
		
		for (var i=combo.childNodes.length-1; i>1; i--) {
			aux = combo.childNodes.item(i);

			if ((aux.nodeName=="OPTION") && (aux.innerText!=null)) {
				combo.removeChild(aux);
				j++;
			}
			
			aux = null;
		}

		
		//exibe novos items para combo
		var options = httpResponse.documentElement.getElementsByTagName("regiao"); 

		for (i=0; i<options.length; i++) {
			optValue = options[i].getAttribute('idRegiao');
			optTitle = options[i].getAttribute('nome');
					
			aux = new Option(optTitle, optValue);
			aux.innerText = optTitle;

			combo.appendChild(aux);
		}
	}