Percutaneous cryoablation for recurrent low grade renal cell carcinoma after failed nephron-sparing surgery.

INTRODUCTION: Partial nephrectomy has a 3%-4% incidence of local treatment failure. This study is to present a series of percutaneous cryoablation for locally recurrent renal cell carcinoma after partial nephrectomy. MATERIALS AND METHODS: Five consecutive patients were referred to our quarternary center's multidisciplinary Small Renal Mass (SRM) Center for assessment after failure of partial nephrectomy. Tumor size and location was noted. CT-guided cryoablation was performed using an argon/helium-based system (Healthtronics, Austin, Texas, USA). Patients were admitted overnight for observation. Patients were followed with serial imaging, laboratory tests and examination at our SRM Center. Tumor size, location, and nephrometry scores were documented for each patient. RESULTS: Four tumors were endophytic and one was exophytic. The median tumor size was 2.2 cm (1.8 cm-4.0 cm). Nephrometry scores were 8a, 7x, 4p, 6x, 7p, and 6p prior to cryoablation. Median follow up after cryoablation was 32 months (20-39 months). One patient with a 4.0 cm endophytic tumor developed a second recurrence measuring 2.9 cm 13 months following ablation, which was managed successfully with repeat cryoablation with no evidence of disease after an additional 19 months of follow up. Two patients developed self-limited hematuria which was conservatively managed. There were no other complications, and all patients remained at their pretreatment performance status. CONCLUSIONS: Percutaneous cryoablation appears to be a safe and effective nephron-sparing modality for control of locally recurrent disease following partial nephrectomy. Most recurrent tumors are endophytic. One patient suffered a second local recurrence, which was managed successfully with repeat cryoablation.

A novel soft sensor approach for estimating individual biomass in mixed cultures.

Due to many advantages associated with mixed cultures, their application in biotechnology has expanded rapidly in recent years. At the same time, many challenges remain for effective mixed culture applications. One obstacle is how to efficiently and accurately monitor the individual cell populations. Current approaches on individual cell mass quantification are suitable for off-line, infrequent characterization. In this study, we propose a fast and accurate "soft sensor" approach for estimating individual cell concentrations in mixed cultures. The proposed approach utilizes optical density scanning spectrum of a mixed culture sample measured by a spectrophotometer over a range of wavelengths. A multivariate linear regression method, partial least squares or PLS, is applied to correlate individual cell concentrations to the spectrum. Three experimental case studies are used to examine the performance of the proposed soft sensor approach. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:347-354, 2017.