Mathematical precision in rotational corrective osteotomy of the femur.

We used a mathematical model to determine whether the approach to derotation of the malrotated femur can be improved for use in corrective osteotomy of the femur. Rotational corrective osteotomy of the femur (RCOF) is a procedure performed by orthopedic surgeons to correct congenital femoral torsion deformities and posttraumatic femoral shaft malunions. In the conventional technique, osteotomy is performed at the malrotation site, and correction is achieved by rotating the distal segment of the femur so that the patella and toes point upward, symmetric with the normal leg when the patient is in the supine position.

Interaction between Na+/phosphate-cotransporter and the adrenoceptors in myocardial depression.

The primary objective of this study was to test the hypothesis that an increase in the alpha1-adrenoceptor tone would potentiate the myocardial biphasic contractile response to inorganic phosphate [Pi, the substrate of Na/Pi-cotransporter (NP)]. A second aim was to determine whether activation of alpha1-adrenoceptor is necessary for the NP-mediated increase in myocardial contractility (+dP/dt). Earlier study from this laboratory showed that high concentration of Pi (10 mM) produces a biphasic contractile response: initial increase in +dP/dt was followed by decline.

Regulation of rat Na+/Pi cotransporter-1 gene expression: the roles of glucose and insulin.

Cytosolic inorganic phosphate (P(i)) is important for glucose metabolism. It plays a role in homeostatic regulation of glucose by insulin and glucagon. Recently, we isolated two cDNA clones for rat Na+/P(i) cotransporter-1 (rNaPi-1) and demonstrated that they are expressed primarily in the rat liver and kidney.

Role of Na+/phosphate-cotransporter in myocardial contractile responses to alpha 1-agonist.

The interaction of cardiac sodium/phosphate (Na+/Pi)-cotransporter and the phosphoinositide pathway (PIP) in influencing myocardial contraction was investigated. Specifically, the study was performed to determine if myocardial positive inotropic response (+dP/dt) to phenylephrine (PE, an activator of PIP) can be potentiated by inorganic phosphate (Pi, the substrate of Na+/Pi-cotransporter). Contractile responses of the isolated perfused rat heart were studied in conditions of controlled extracellular calcium activity and constant preload.

Role of sodium/phosphate-cotransporter in myocardial contractile responses to inorganic phosphate.

Na+/Pi-cotransporter utilizes the electrochemical gradient of sodium to transport inorganic phosphate (Pi) into the cells of various organs, including heart. Because changes in the activity of Na+/Pi-cotransporter may influence the concentrations of intracellular Na+, Ca2+ and other ions, the influence of Pi on myocardial contractility was investigated. Interaction between Pi and ouabain was also investigated.