Expression of HIF-1alpha, HIF-2alpha (EPAS1), and their target genes in paraganglioma and pheochromocytoma with VHL and SDH mutations

Soft tissue tumors of the urinary bladder, Part I: myofibroblastic proliferations, benign neoplasms, and tumors of uncertain malignant potential

Most bladder tumors arise from the urothelium. However, there are several uncommon but significant bladder lesions that must be differentiated from urothelial carcinomas. These include both benign and malignant spindle cell lesions. The first half of this 2-part review will describe benign myofibroblastic proliferations including inflammatory myofibroblastic tumor and postoperative spindle cell nodule; benign neoplasms including leiomyoma, hemangioma, neurofibroma, and schwannoma; and tumors of uncertain malignant potential including paraganglioma, granular cell tumor, and perivascular epithelioid cell tumor. Common clinical presentations, morphological characteristics, and immunohistochemical features are described to aid the practicing pathologist in the identification of these entities. This review also describes current theories as to the pathogenesis of inflammatory myofibroblastic tumor and postoperative spindle cell nodule and details the current molecular markers identifying several of these lesions.

Interrelationships Among Hypoxia-Inducible Factor Biology and Acid-Base Equilibrium

In this article, we try to summarize the most important novel biological information on the complex interrelationships between acid-base alterations and hypoxia-inducible factor (HIF) signaling. Extracellular and intracellular acid-base alterations affect HIF signaling in part independently of hypoxia, and involve, among others, effects on cytoprotection and apoptosis. Conversely, HIF signaling may affect systemic and local acid production rates and has been implicated in the mechanism of the acute hyperventilatory response (ie, respiratory alkalosis) in response to hypoxia as well as for hypoxia-induced pulmonary artery hypertension (PAH), although the latter data are quite preliminary and can be explained by alternative mechanisms. Thus, this review calls attention to these relationships for renal physiologists and nephrologists to stimulate focused clinical observations and specific investigative efforts as proposed in this overview.