No abstract

BACKGROUND.In colorectal carcinoma, venous invasion has been related to patient

There is still controversy surrounding the indications for performing either a retrograde ureteral stent or percutaneous nephrostomy to manage malignant extrinsic ureteral obstruction (MEUO). We retrospectively analyzed 53 patients who underwent a decompression of MEUO using retrograde ureteral stent. Ureteral stent failure occurred in 18 of 53 patients (34%). Multivariate analysis showed that gastrointestinal cancer as the primary disease, poor preoperative performance status and severe preoperative hydronephrosis were independent predictors of stent failure. Based on the present data, we propose an algorithm for the management of MEUO.

We describe voltage- and calcium-dependent ionic currents in the photoreceptor inner segments similar to the Hodgkin and Huxley (Journal of Physiology, 117, 500-544, 1952) equations. The model is used to describe both rods and cones by adjusting parameters. To simulate the light response, the inner segment model was connected with the phototransduction model proposed by Torre et al. (Cold Spring Harbor Symposia on Quantitative Biology, 55, 563-573, 1990). The role of individual ionic currents in the inner segment in shaping the light response was analyzed through computer simulations. The results suggest that: (1) the transient hyperpolarization to a bright flash is generated by Ih; (2) the oscillation after prolonged hyperpolarization in rods results from the interaction among Ica, IK(Ca), and ICI(Ca). Since the present model describes the biophysical processes from phototransduction to voltage response, the model can be used for analyzing the light response properties of the photoreceptors quantitatively.