tacrolimus and Pheochromocytoma

The aim of this paper was to report the case of type 2 diabetes and significant insulin resistance that improved dramatically after removal of a pheochromocytoma in a liver transplant recipient , and to provide a review of the relevant literature. We describe the clinical presentation, diagnostic results and management of the patient. In addition, we performed a PubMed search for related English language articles, to provide an overview of the pertinent literature. A 53 year old woman with a history of an orthotopic liver transplantation and insulin-requiring type 2 diabetes was admitted to the hospital with fever, diaphoresis, tachycardia and hypertension. A pheochromocytoma was diagnosed and removed. The patient subsequently developed hypoglycemia and required no further insulin therapy. Pheochromocytomas have been described to lead to hyperglycemia and diabetes, due to the suppression of insulin release and increased insulin resistance. Furthermore, a review of the literature revealed only 3 other reported cases of pheochromocytomas in organ transplant recipients. None of these pheochromocytomas were believed to have occurred de novo after transplantation. This is the first report of a pheochromocytoma in a liver transplant recipient and possibly the first case of a de novo pheochromocytoma in any organ transplant recipient. Moreover, this case showcases pheochromocytomas as a rare cause of diabetes mellitus.

Topics: Adrenal Gland Neoplasms; Adrenalectomy; Diabetes Mellitus, Type 2; Female; Glipizide; Glucocorticoids; Humans; Hypertension; Hypoglycemic Agents; Immunosuppressive Agents; Insulin; Insulin Resistance; Insulin Secretion; Liver Diseases, Alcoholic; Liver Transplantation; Middle Aged; Pheochromocytoma; Postoperative Complications; Remission Induction; Tachycardia; Tacrolimus

ortho-Substituted PCBs mobilize Ca2+ from isolated brain microsomes by interaction with FKBP12/RyR complexes. Investigation into the cellular importance of this mechanism was undertaken using PC12 cells by fluoroimaging the actions of specific PCB congeners on [Ca2+]i and pH. RyR and IP3R share a common intracellular Ca2+ store in PC12 cells. Perfusion of nM to low microM PCB95 caused a transient rise of [Ca2+]i that was not completely dependent on extracellular Ca2+. Pre-incubation of the cells with ryanodine or FK506 completely eliminated PCB95 responses, suggesting a primary action on the FKPP12/RyR-sensitive store. PCB95, but not PCB126, induced a gradual decrease in cytosolic pH that could be completely eliminated by FK506 pre-incubation of the cells. Direct respiration measurement using isolated brain mitochondria demonstrated that neither of the PCBs directly altered any stage of mitochondrial respiration. These results revealed that PCB95 disrupts intracellular Ca2+ signaling in PC12 cells by interaction with the FKBP12/RyR complex that in turn accelerated cellular metabolism, possibly affecting signaling between ER and mitochondria. Since ortho-substituted PCBs have been shown to be neurotoxic and may affect neurodevelopment, studies on the molecular mechanism by which they alter cellular signaling may provide valuable information on the physiological roles of FKPB12 and RyR on neuronal functions.

Topics: Acidosis; Animals; Bradykinin; Brain Chemistry; Calcium; Calcium Signaling; Cell Respiration; Enzyme Inhibitors; Estrogen Antagonists; Hydrogen-Ion Concentration; Immunophilins; Inositol Phosphates; Intracellular Fluid; Male; Mitochondria; PC12 Cells; Pheochromocytoma; Polychlorinated Biphenyls; Rats; Rats, Sprague-Dawley; Ryanodine; Structure-Activity Relationship; Tacrolimus