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Open Access Publications from the University of California

Scholarly Works (47 results)

  • Thesis
  • Peer Reviewed
UC Irvine Electronic Theses and Dissertations (2015)

ABSTRACT OF THE THESIS

Comparing Conventional and Valveless Trocar Insufflation During Laparoscopic Renal Surgery

By

Philip Bucur

Master of Science – Biomedical and Translational Science

University of California, Irvine, 2015

Professor Jaime Landman, Chair

We compared the variation in pneumoperitoneum, physiologic effects, and postoperative outcomes of patients undergoing laparoscopic renal surgery using a conventional insufflation system (CI) versus the valveless trocar insufflation (VI) system.

This is a prospective, randomized comparative study with fifty-six patients undergoing laparoscopic renal surgery with valveless trocar insufflation or conventional insufflation. Patients in the valveless insufflation arm (n=28) underwent surgery using the AirSeal valveless trocar insufflation system whereas patients in the conventional treatment arm (n=28) underwent surgery using standard laparoscopic trocars connected to a Storz insufflator with the insufflation pressure set to 15 mm Hg. We compared the groups with respect to stability of pneumoperitoneum, intraoperative and postoperative outcomes, and physiologic parameters.

The coefficient of variation in pressures was significantly lower in the valveless trocar group compared to the conventional treatment group (7.9% vs. 15.6%, p<0.001) with significantly less time spent above insufflation pressures of 20 mm Hg. Estimated blood loss was significantly higher in the valveless trocar group than conventional group (155 vs. 75 cc, p=0.03). End-tidal CO2 (ET CO2) was significantly lower at 10 minutes (34.3 vs. 36.6 mmHg, p=0.029) and 25 minutes (35.8 vs. 37.6 mmHg, p=0.047) in the valveless trocar group compared to the conventional treatment group. There were no other significant differences across physiologic parameters or outcomes.

In conclusion, compared with a conventional insufflation system, the valveless trocar insufflation system provides a significantly more stable pneumoperitoneum during laparoscopic renal surgery and lower end-tidal CO2 at 10 minutes, but with an increased risk of blood loss.

    Cover page: Comparing Conventional and Valveless Trocar Insufflation During Laparoscopic Renal Surgery
    • Article
    • Peer Reviewed
    UC Irvine Previously Published Works (2020)
    The loss of the von Hippel-Lindau (VHL) tumor-suppressor is a major driver of Clear Cell Renal Cell Carcinoma (CC-RCC) resulting in the stabilization and overactivation of hypoxia inducible factors (HIFs). ROCK1 is a well-known protein serine/threonine kinase which is recognized as having a role in cancer including alterations in cell motility, metastasis and angiogenesis. We recently investigated and identified a synthetic lethal interaction between VHL loss and ROCK1 inhibition in CC-RCC that is dependent on HIF overactivation. Increased expression and activity of both HIFs and ROCK1 occurs in many types of cancer supporting the potential therapeutic role of ROCK inhibitors beyond CC-RCC. We also discuss future research required to establish prognostic markers to predict tumor response to ROCK inhibitors.
      Cover page: Targeting the RhoGTPase/ROCK pathway for the treatment of VHL/HIF pathway-driven cancers.
      • Thesis
      • Peer Reviewed
      UC Irvine Electronic Theses and Dissertations (2020)

      In the past five decades, several landmark discoveries have demonstrated that nucleic acids are a multi-talented class of biomolecules. These discoveries include naturally occurring ribozymes (RNA enzymes), man-made ribozymes and deoxyribozymes (DNA enzymes), and DNA and RNA aptamers (nucleic acid-based molecular binders). These advancements have increased the popularity of nucleic acid molecules as potential biorecognition elements for analytical and biosensor applications. The studies presented here focuses on the in vitro selection of a rational deigned functional aptamer molecules capable of identifying bladder cancer urine samples by recognizing the urinary molecular compositions, or urine biomarkers, associated with bladder cancer. To achieve the aforementioned, I described the different in vitro selection strategies designed to identify aptamer molecules that recognize various target molecules with high specificity and affinity. This is followed by a more detailed focus on the in vitro selection of structure-switching aptamer scheme where I reported the designing and testing of a diverse DNA library. I provided three different selections that were performed utilizing the custom DNA library to demonstrate the feasibility of the library design and the structure-switching in vitro selection platform. Lastly, I performed a complex selection to isolate bladder cancer specific structure-switching aptamers. The complex selection yield specific-aptamers that can distinguish bladder cancer urine samples from hematuria, or blood in urine, urine samples.

        • Article
        • Peer Reviewed
        UC Irvine Previously Published Works (2013)

        Purpose

        To describe our initial experience with the second-generation Single Port Instrument Delivery Extended Reach (SPIDER) laparoendoscopic single-site surgical system in a porcine model.

        Materials and methods

        In four swine weighing approximately 32 to 35 kg, five nephrectomies, four adrenalectomies, three pyeloplasties, and three partial cystectomies and closures were performed by a single surgeon. The swine were placed in the lateral flank position under general anesthesia. The SPIDER surgical system was introduced through a single incision and the various urological procures were performed by use of flexible instrumentation.

        Results

        All five nephrectomies, four adrenalectomies, three pyeloplasties, and three partial cystectomies and closures were performed successfully without additional skin incisions. The mean time to set up the SPIDER platform was 3.5 minutes. The mean operative time for the right and left nephrectomies was 45.4 minutes and 47.8 minutes, respectively. The mean operative time for the right and left adrenalectomies was 37.6 minutes and 35.4 minutes, respectively. The mean operative time for the pyeloplasties for one right and two left ureters was 45.6 minutes and 47.3 minutes, respectively. The mean operative time for the partial cystectomies and closures was 18.6 minutes. There were no noticeable intraoperative complications except for minimal urine leakage in the first pyeloplasty.

        Conclusions

        In this initial pilot evaluation, the second-generation SPIDER surgical system offered intuitive instrument maneuverability and restored triangulation. However, retraction was challenging because of the lack of strength and the limited ability for precise manipulation of the tip. Future refinements of the technology and prospective studies are needed to optimize the application of this technology in urology.
          Cover page: Laparoendoscopic Single-Site Surgery With the Second-Generation Single Port Instrument Delivery Extended Reach Surgical System in a Porcine ModelCreative Commons 'BY' version 4.0 license
          • Article
          • Peer Reviewed
          UC Irvine Previously Published Works (2012)

          Background and objectives

          Cryoablation represents an alternative for treating small renal cortical neoplasms (RCN). Previously, we demonstrated that applying BioGlue during cryoablation diminished bleeding and incidentally noted that the iceballs seemed larger than those in controls. We examined the effects of BioGlue as a thermal insulator of cryoablated tissue to determine its effect on iceball size.

          Methods

          Laparoscopic cryoablation (LCA) was performed in 6 female pigs (24 ablations) by using a single 1.47-mm cryoablation probe. One pole of each kidney was randomly treated with BioGlue prior to ablation, while the contralateral pole was the untreated control. The size of the iceball was measured using laparoscopic ultrasound. The tissue ablation zone was measured grossly after the specimens were harvested. We also documented the amount of bleeding on a subjective scale.

          Results

          There were no differences in the diameters of the iceballs between the BioGlue and control groups when measured with laparoscopic ultrasound (P=.85). Similarly, the ablation zones on gross measurement were not significantly different (P=.47). No difference occurred in the amount of subjective bleeding.

          Conclusions

          In a porcine model, the application of BioGlue prior to LCA does not appear to increase the size of the iceball generated. No change was observed in the amount of subjective bleeding as a result of using BioGlue.
            Cover page: BioGlue Surgical Adhesive as a Thermal Reflector During Laparoscopic Cryoablation: Effect on Iceball Size and Ablation Zone DiameterCreative Commons 'BY' version 4.0 license
            • Article
            • Peer Reviewed
            UC Irvine Previously Published Works (2012)
            Urinary tract interventions can lead to multiple complications in the renal collecting system, including retained foreign bodies from endourologic or percutaneous procedures, such as stents, nephrostomy tubes, and others. We report a case of very delayed erosion of embolization coils migrating into the renal pelvis, acting as a nidus for stone formation, causing mild obstruction and finally leading to gross hematuria roughly 18 years post transarterial embolization. History is significant for a remote unsuccessful endopyelotomy attempt that required an urgent embolization.
              Cover page: Erosion of Embolization Coils into the Renal Collecting System Mimicking Stone
              • Article
              • Peer Reviewed
              UC Irvine Previously Published Works (2020)
              The loss of the von Hippel-Lindau (VHL) tumor-suppressor is a major driver of Clear Cell Renal Cell Carcinoma (CC-RCC) resulting in the stabilization and overactivation of hypoxia inducible factors (HIFs). ROCK1 is a well-known protein serine/threonine kinase which is recognized as having a role in cancer including alterations in cell motility, metastasis and angiogenesis. We recently investigated and identified a synthetic lethal interaction between VHL loss and ROCK1 inhibition in CC-RCC that is dependent on HIF overactivation. Increased expression and activity of both HIFs and ROCK1 occurs in many types of cancer supporting the potential therapeutic role of ROCK inhibitors beyond CC-RCC. We also discuss future research required to establish prognostic markers to predict tumor response to ROCK inhibitors.
                Cover page: Targeting the RhoGTPase/ROCK pathway for the treatment of VHL/HIF pathway-driven cancers.Creative Commons 'BY' version 4.0 license
                • Article
                • Peer Reviewed
                ICTS Publications (2013)
                AbstractBackground and Purpose

                Recent advances in distal sensor technologies have made distal sensor ureteroscopes both commercially and technically feasible. We evaluated performance characteristics and optics of a new generation distal sensor Flex-XC (XC) and a standard flexible fiberoptic ureteroscope Flex-X2 (X2), both from Karl Storz, Tuttlingen, Germany.

                Materials and Methods

                The ureteroscopes were compared for active deflection, irrigation flow, and optical characteristics. Each ureteroscope was evaluated with an empty working channel and with various accessories. Optical characteristics (resolution, grayscale imaging, and color representation) were measured using United States Air Force test targets. We digitally recorded a renal porcine ureteroscopy and laser ablation of a stone with the X2 and with the XC. Edited footage of the recorded procedure was shown to different expert surgeons (n=8) on a high-definition monitor for evaluation by questionnaire for image quality and performance.

                Results

                The XC had a higher resolution than the X2 at 20 and 10 mm 3.17 lines/mm vs 1.41 lines/mm, 10.1 vs 3.56, respectively (P=0.003, P=0.002). Color representation was better in the XC. There was no difference in contrast quality between the two ureteroscopes. For each individual ureteroscope, the upward deflection was greater than the downward deflection both with and without accessories. When compared with the X2, the XC manifested superior deflection and flow (P<0.0005, P<0.05) with and without accessory present in the working channel. Observers deemed the distal sensor ureteroscope superior in visualization in clear and bloody fields, as well as for illumination (P=0.0005, P=0.002, P=0.0125).

                Conclusions

                In this in vitro and porcine evaluation, the distal sensor ureteroscope provided significantly improved resolution, color representation, and visualization in the upper urinary tract compared with a standard fiberoptic ureteroscope. The overall deflection was also better in the XC, and deflection as well as flow rate was less impaired by the various accessories.

                  Cover page: In Vitro and In Vivo Comparison of Optics and Performance of a Distal Sensor Ureteroscope Versus a Standard Fiberoptic Ureteroscope
                  • Article
                  • Peer Reviewed
                  UC Irvine Previously Published Works (2013)

                  Background and purpose

                  Ureteroscope breakage is commonly related to laser fiber damage. Often, the damage is mechanical and not energy related. As such, we evaluated a novel laser fiber and sheath system in preventing mechanical ureteroscope damage during fiber insertion.

                  Materials and methods

                  We assessed 200-μm/272/3-μm laser fibers with the laser sheath in a flexible ureteroscope. Diminishment of active deflection and irrigation flow rates were compared with a standard laser fiber alone. Eight nonassembled working channel components were tested in a 0-degree/90-degree/210-degree deflection model. After insertion cycles, external and endolumenal damage to the working channel were classified. We also tested the sheath system in a 0-degree/90-degree/210-degree deflection model for fiber failure and laser damage.

                  Results

                  In all test trials with the sheath and for standard laser fibers in the 0-degree model, there were no channel perforations or damage. With standard laser fibers, in the 210-degree model, superficial scratches and demarcated abrasions were visible after 10 and 60 to 70 insertions for the 273-μm laser fiber and after 30 insertions (superficial scratches) for the 200-μm laser fiber. In the 90-degree model, superficial scratches occurred after 20 insertions for the 273-μm fibers and after 40 insertions for the 200-μm laser fibers. No demarcated abrasions were seen after 100 insertions. In the 210-degree model, there was one perforation with the 272-μm fiber, but none with 200-μm fiber. There were no fiber failures with sheath use; however, the sheath did not prevent laser energy damage. The laser sheath resulted in a 4.7-degree/3.8-degree (1.2%/1.5%) diminishment in deflection (up/down) for the 200 μm and a 3.5-degree/4.3-degree (1.8%/1.5%) diminishment for 272-μm laser fiber compared with standard 200/272-μm laser fiber. Irrigation flow was diminished with the sheath on both the 200-μm and 272-μm laser fiber by 28.7% and 32.6%, respectively.

                  Conclusion

                  The Scope Guardian Sheath prevented mechanical working channel damage with minimal diminishment of deflection and irrigation flow.
                    Cover page: In Vitro Evaluation of ScopeSafe Fibers and the Scope Guardian Sheath in Prevention of Ureteroscope Endolumenal Working DamageCreative Commons 'BY' version 4.0 license
                    • Article
                    • Peer Reviewed
                    UC Irvine Previously Published Works (2023)
                    Ureteral stent encrustation significantly limits indwelling time and can lead to downstream urological problems. However, no ideal polymeric biomaterials have been shown to completely resist encrustation in long-term urine exposure. Recently, 2-hydroxyethyl methacrylate (HEMA)-coated Pellethane was reported as a promising biomaterial resistant to encrustation. This study compared HEMA-coated Pellethane to commercially available stents under two different artificial urine environments. To evaluate the degree and composition of encrustation on HEMA-coated Pellethane, Boston Scientific Tria, Bard InLay Optima, Cook Universa Hydrogel, and Cook Black Silicone stents were used at various dwelling times in two different artificial urine environments. In a batch-flow model, samples of stents were suspended in an artificial urine solution (AUS) at 37 °C. Every 24 h for 11 weeks, 50% of the AUS would be replaced with fresh components using a programmable peristaltic pump system. The stent materials were removed at suitable time intervals and air-dried for 24 h under sterile conditions before follow-up analysis. SEM was used to assess the degree of encrustation, and inductively coupled plasma mass spectrometry (ICP-MS) was employed to quantify the encrusted compositions, specifically for calcium, magnesium, and phosphorus. We measured the weight gain over time due to encrusted deposits on the stents and quantified the amount of Ca, Mg, and P deposited on each encrusted stent. After the 11 week trial, HEMA-coated Pellethane showed the most average mass change. SEM showed that HEMA-coated Pellethane was fully encrusted in just 2 weeks in the AUS environments, and ICP-MS showed that Ca is the most abundant deposit. Among all the tested stents, Black Silicone performed the best. The two AUSs were formulated to encrust more rapidly than physiological conditions. HEMA-coated Pellethane is not an ideal stent material, while silicone is a promising material for advancing ureteral stents.
                      Cover page: Comparison of Ureteral Stent Biomaterials: Encrustation Profile in Lithogenic Artificial Urine Models.
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