By CHRISTOPHER RUGABER
AP Economics Writer
WASHINGTON (AP) — U.S. wholesale prices increases accelerated in August, a sign that inflation remains stubbornly persistent despite a series of sharp interest rate hikes by the Federal Reserve. The Labor Department said Thursday that its producer price index — which measures inflation before it hits consumers — increased 1.6% last month from a year earlier. That is up from a small 0.8% yearly increase in July and just 0.1% in June. Sharply higher gas prices drove much of the increase.