The Fifth Circuit has upheld a Texas bankruptcy court's order recharacterizing the ostensible debt of a non-insider as equity.
Matter of Lothian Oil Incorporated, No. 10-50683 (5th Cir. 8/9/11). Unlike other circuits to consider the issue, the Fifth Circuit relied on Sec. 502(b) and Texas state law rather than the Court's equitable powers under Sec. 105. You can find the opinion
here.