Imaging and management of thumb carpometacarpal joint osteoarthritis.

Primary osteoarthritis (OA) involving the thumb carpometacarpal (CMC) joint is a common and frequently debilitating disease. Clinical examination and radiographs are usually sufficient for diagnosis; however, familiarity with the cross-sectional anatomy is useful for diagnosis of this condition. The most widely used classification system for the radiographic staging of thumb carpometacarpal joint OA was first presented by Eaton and Littler, ranging from mild (stages I and II) to severe (stage IV) disease. If conservative treatment fails, surgical treatment is considered. A variety of surgical techniques have been developed and implemented for the management of this pervasive and disabling condition. The purpose of this article is to review the anatomy of the basal joints of the thumb, pathophysiology, preoperative imaging, and various surgical techniques that are utilized in the treatment of OA of the basal joints of the thumb with emphasis on normal postoperative radiographic findings and possible postoperative complications.

Tumor cells upregulate normoxic HIF-1α in response to doxorubicin.

Hypoxia-inducible factor 1 (HIF-1) is a master transcription factor that controls cellular homeostasis. Although its activation benefits normal tissue, HIF-1 activation in tumors is a major risk factor for angiogenesis, therapeutic resistance, and poor prognosis. HIF-1 activity is usually suppressed under normoxic conditions because of rapid oxygen-dependent degradation of HIF-1α. Here, we show that, under normoxic conditions, HIF-1α is upregulated in tumor cells in response to doxorubicin, a chemotherapeutic agent used to treat many cancers. In addition, doxorubicin enhanced VEGF secretion by normoxic tumor cells and stimulated tumor angiogenesis. Doxorubicin-induced accumulation of HIF-1α in normoxic cells was caused by increased expression and activation of STAT1, the activation of which stimulated expression of iNOS and its synthesis of nitric oxide (NO) in tumor cells. Mechanistic investigations established that blocking NO synthesis or STAT1 activation was sufficient to attenuate the HIF-1α accumulation induced by doxorubicin in normoxic cancer cells. To our knowledge, this is the first report that a chemotherapeutic drug can induce HIF-1α accumulation in normoxic cells, an efficacy-limiting activity. Our results argue that HIF-1α-targeting strategies may enhance doxorubicin efficacy. More generally, they suggest a broader perspective on the design of combination chemotherapy approaches with immediate clinical impact.