º, aka Masculine Ordinal Indicator, Breaking XML Node Creation in PHP

Here is some PHP code that creates XML nodes from a MySQL DB call. It works great except the masculine ordinal indicator º breaks the code. Any suggestions or tips would be much appreciated. Thanks in advance!

Code

$result = mysql_query("SELECT street FROM Addresses");
while ($row = @mysql_fetch_assoc($result)){
  $node = $dom->create_element("marker");
  $newnode = $parnode->append_child($node);
  $newnode->set_attribute("street", $row['street']);
}

The code breaks when $row['street'] has an entry that looks something like Nº111-E AVENIDA FOO.

Expected Result

<markers><marker street="Nº111-E AVENIDA FOO" /></markers>

Actual (Broken) Result

<markers><marker street="N

It breaks on the º. I've tried using utf8_encode($row['street']) and htmlentities($row['street']) but neither helped.

Manually Entering Character

The curious thing is that if the address is added manually, as follows, the code works well and in fact, the º automatically gets converted to its HTML encoding º.

$result = mysql_query("SELECT street FROM Addresses");
while ($row = @mysql_fetch_assoc($result)){
  $node = $dom->create_element("marker");
  $newnode = $parnode->append_child($node);
  $newnode->set_attribute("street", "Nº111-E AVENIDA FOO");
}

Result when manually entering º:

<markers><marker street="N&#xBA;111-E AVENIDA FOO" /></markers>