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Stephen Y Nakada

Publications and source records attributed to Stephen Y Nakada.

At least 19 recordsLinked to original sources
PubMed2006

Examination of laparoscopic retrieval bag washings for malignant cells after hand-assisted laparoscopic radical nephrectomy and intact specimen removal.

OBJECTIVES: Port site metastases after hand-assisted laparoscopic radical nephrectomy have been described in the literature. There is no uniform agreement among urologists regarding the use of a retrieval bag before intact specimen removal. The aim of this study was to determine whether LapSac renal extraction bag washings contain malignant cells. METHODS: We prospectively obtained washings from the LapSac retrieval bag after hand-assisted laparoscopic radical nephrectomy and intact specimen removal for renal cell carcinoma. In 30 consecutive cases, after removal of the kidney specimen from the LapSac, the LapSac was irrigated with 50 mL sterile Hank's balanced salt solution. These washings were sent for cytologic examination. Cytologic evaluation was performed with a Thin Prep and the Papanicolaou method. RESULTS: We performed 30 hand-assisted laparoscopic radical nephrectomies for suspected renal cell carcinoma with the above protocol. One specimen was benign and one showed transitional cell carcinoma; these were excluded from the study. Six specimens were stage T1a, 17 were T1b, 1 was T2, 2 were T3a, and 2 were T3b. Histopathology revealed 27 specimens with clear cell renal cell carcinomas with Fuhrman grades from 1 to 4; 1 specimen showed chromophobe renal cell carcinoma. Margins were negative in all cases, and there were no gross or microscopic tumor violations. The cytologic results from 27 cases were negative and in 1 case with T3b renal cell carcinoma the LapSac washings were positive for malignant cells. CONCLUSIONS: The preliminary findings from our study show that low-stage, low-grade tumors removed laparoscopically with minimal manipulation do not exfoliate cells into their LapSac retrieval bags.

Carcinoma, Renal Cell↗
PubMed2006

Magnetic resonance imaging findings after laparoscopic renal cryoablation.

OBJECTIVES: To assess the magnetic resonance imaging (MRI) appearance of renal masses after laparoscopic cryoablation. METHODS: Between October 2000 and June 2004, 33 patients underwent laparoscopic cryoablation of 34 renal masses, 24 of whom (25 renal masses, size range 1.5 to 3.7 cm, mean 2.4) were followed up with MRI postoperatively. Postoperative MRI was done at 1, 3, and 6 months after ablation and every 6 months thereafter using a 1.5-T MRI scanner. T1-weighted dual-phase, coronal T1-weighted fat-saturated, and T2-weighted coronal and axial MRI was done before contrast administration. Postenhancement images were obtained in the coronal and axial planes during the arterial, venous, and delayed phases. RESULTS: Patient follow-up data were available for at least 6 months and up to 48 months for 18 patients. On the first follow-up MRI study, six lesions had increased in size, five had decreased in size, and seven showed no change. Of the 18 patients, 7 had peripheral rim enhancement within 3 months of follow-up. Four resolved. One patient developed rim enhancement at 7 months postoperatively. Subsequent images revealed lesion enlargement with heterogeneous enhancement. Biopsy was positive for renal cell carcinoma. One patient developed nodular enhancement at 10 months with a decrease in lesion size. Watchful waiting was chosen because the patient had significant medical comorbidities. CONCLUSIONS: Peripheral rim enhancement is a common finding on MRI immediately after laparoscopic renal cryoablation. Rim enhancement with an increase in lesion size or nodular enhancement is of more concern than rim enhancement alone. More data are necessary to understand the progression of renal lesions after cryoablation.

Aged↗
PubMed2006

Evaluation of urothelial stretch-induced cyclooxygenase-2 expression in novel human cell culture and porcine in vivo ureteral obstruction models.

Obstruction and stretch induce cyclooxygenase (COX)-2 expression and prostanoid synthesis in urinary tissues, causing pain, inflammation, hypercontractility, and cell proliferation. Our objective was to characterize acute COX-2 induction during in vivo ureteral obstruction, establish a cell culture model of urothelial stretch-induced COX-2 expression, and evaluate whether mechanotransduction could alter transcriptional and post-transcriptional regulation of COX-2. We performed laparoscopic unilateral ureteral ligation in pigs and allowed progression for 1, 2, 6, 24, or 48 h. We evaluated COX-2 expression with reverse transcriptase (RT)-polymerase chain reaction (PCR) and immunoblotting. We cultured primary human urothelial cells on stretch plates, applied stretch for up to 48 h, and measured COX-2 expression by RT-PCR and immunoblotting, transcription with run-on assays, and mRNA stability with actinomycin mRNA decay assays. In vivo ureteral obstruction induced COX-2 expression 4-fold within 6 h, maintaining induction for 24 h. In cell culture, stretch induced COX-2 steady-state mRNA and protein within the first 3 h of stretch, maintaining this induction for over 6 h. Three hours of stretch doubled COX-2 transcription relative to unstretched controls and increased COX-2 mRNA half-life 3-fold. This is the first report to characterize in vivo temporal stretch-induced COX-2 expression in the urothelium and establish a primary urothelial cell culture model for the study of stretch-induced COX-2 mechanisms. This is also the first report to identify alterations in steady-state COX-2 mRNA having components of both transcriptional and post-transcriptional regulation of stretch-regulated COX-2. Future elucidation of COX-2 signaling may identify novel therapeutic targets for treating stretch and distension of urinary tissues.

Adult↗
PubMed2006

Maintaining urine production and early allograft function during laparoscopic donor nephrectomy.

OBJECTIVES: Intraoperative oliguria and its impact on early postoperative allograft function have been expressed as potential concerns of laparoscopic kidney donation. We evaluated our ability to maintain adequate diuresis during laparoscopic donor nephrectomy and its potential impact on early graft function compared with open donation. METHODS: We performed a retrospective review of 98 laparoscopic and 80 open donor nephrectomies from 1999 to 2002. All laparoscopic donors received infusions of mannitol (grams of mannitol equaled patient weight in kilograms) and dopamine (2 to 3.0 microg/kg/min) throughout the pneumoperitoneum. All open donors received a single dose of mannitol (12.5 g). Multiple donor variables were compared, including operative time, estimated blood loss, intraoperative fluid administration (in milliliters per kilogram per hour), intraoperative urine production (milliliters per kilogram per hour), and change in creatinine at discharge. The postoperative recipient data were compared, including initial 24-hour urine output, 1-week creatinine level, 1-month creatinine level, and need for postoperative hemodialysis. RESULTS: No significant differences were noted in the donor groups with respect to age, weight, intraoperative fluid administration, or change in creatinine at discharge. The mean operative urine production was greater in the laparoscopic group at 5.22 mL/kg/hr than in the open group at 2.43 mL/kg/hr (P = 0.0001). The mean estimated blood loss was significantly lower (P = 0.0001) for the laparoscopic donors (106.7 mL) than for the open donors (184.7 mL). No significant differences were seen among the recipient groups. CONCLUSIONS: The use of mannitol and dopamine infusions during laparoscopic donor nephrectomy provided superior intraoperative urine production in the donor and equivalent early graft function in the recipient compared with the open approach.

Adult↗
PubMed2006

Meta-analysis of the complications of laparoscopic renal surgery: comparison of procedures and techniques.

PURPOSE: We performed a meta-analysis of the literature to define the current expectations of complications during laparoscopic renal surgery. MATERIALS AND METHODS: References were searched in the MEDLINE database from 1995 to 2004 using the terms complications and laparoscopic nephrectomy. Inclusion criteria were any series with greater than 20 cases, patient age older than 16 years and any complications listed for certain procedures, including laparoscopic radical nephrectomy, HA laparoscopic radical nephrectomy, LPN, HALPN, laparoscopic donor nephrectomy, HA laparoscopic donor nephrectomy, laparoscopic simple nephrectomy, laparoscopic nephroureterectomy and retroperitoneal laparoscopic nephrectomy. A data extraction form was created to categorize major or minor complications. A 5 member panel adhered to the strict criteria and extracted data from articles that met inclusion criteria. Data were entered into a spreadsheet and a meta-analysis was performed. RESULTS: Initial review identified 73 of 405 references that were acceptable for retrieval and data extraction, of which 56 met inclusion criteria. The overall major and minor complication rates of laparoscopic renal surgery were 9.5% and 1.9%, respectively. There was a significant difference between the major complication rates of LPN and HALPN (21.0% vs 3.3%, p <0.05). CONCLUSIONS: Our results show that patients who undergo laparoscopic renal surgery may have an overall major complication rate of 9.5%. The highest major complication rate is associated with technically challenging LPN (21%). There appears to be a significantly higher wound complication rate associated with HA surgery in comparison to that of standard laparoscopy (1.9% vs 0.2%, p <0.05).

Humans↗
PubMed2006

Elastographic measurements of in-vivo radiofrequency ablation lesions of the kidney.

BACKGROUND AND PURPOSE: Elastography may prove useful for monitoring radiofrequency ablative (RFA) therapy because heat-ablated tissues are more elastic than untreated tissues. Herein, we report our initial evaluations of the reliability of elastography for delineating thermal-lesion boundaries at the time of RFA of porcine kidneys. MATERIALS AND METHODS: In-vivo RFA was performed on 20 kidneys from 10 40-kg female pigs. Elastography was performed at the time of surgery and after 48 hours. The imaging plane was perpendicular to the axis of the RF electrode so that the ablated region was around the center of the plane. Measurements of the sections representing the same image plane used for elastography were taken at pathologic examination and compared with the measurements obtained from the elastograms. RESULTS: We found a statistically significant correlation between elastography and pathology measurements with respect to the area and volume estimates (r = 0.9302 and r = 0.953, respectively). Overall, elastography slightly underestimated the lesion size, as judged by the digitalized pathologic images, a finding consistent with previous reports. CONCLUSION: We found a correlation between the area and volume estimates of thermal lesions that were based on elastographic images and the measurements from gross pathologic dimensions. A significant limitation of renal RFA is the inaccuracy of current imaging modalities to provide real-time monitoring, and elastography may prove to be reliable for delineating the resulting thermal lesions.

Animals↗
PubMed2006

Energy ablative techniques for treatment of small renal tumors.

PURPOSE OF REVIEW: The success of partial nephrectomy for the treatment of small renal cancers has led to the development of energy ablative technologies, which are less invasive alternatives for performing nephron-sparing surgery. Currently, cryoablation and radiofrequency ablation are the two most reported technologies. Both technologies use very different means to cause cellular injury. Additionally, three newer technologies, high-frequency ultrasound ablation, laser interstitial therapy, and microwave therapy are emerging in the literature. RECENT FINDINGS: Three- and 4-year data for cryoablation and radiofrequency ablation are now becoming available. On the basis of these studies, it is clear that ablative technologies can be effective treatments for select small renal tumors. It is also evident that both percutaneous and laparoscopic approaches offer minimal morbidity. SUMMARY: As long-term (5 years and greater) outcome data for ablative technologies accumulate, we are likely to see an increase in clinical reports, including more patients who may be candidates for extirpative surgery. Technology will advance, leading to smaller probes with larger treatment zones, making it possible to treat larger tumors and potentially even tumors in the advanced disease state.

Catheter Ablation↗
PubMed2005

Celecoxib inhibits ureteral contractility and prostanoid release.

OBJECTIVES: To evaluate the efficacy and potency of clinically available celecoxib for inhibition of ureteral contractility and prostanoid release. We have previously reported that the selective cyclooxygenase (COX)-2 inhibitor NS-398 inhibits ureteral contractility. METHODS: We evaluated the release of prostaglandin (PG) E2, F2alpha, D2, thromboxane B2 (a thromboxane2 metabolite), and 6-keto-PGF1alpha (a prostacyclin metabolite) by gas chromatography-mass spectrometry from porcine ureters in the presence and absence of tumor necrosis factor-alpha (TNF-alpha), a putative cyclooxygenase (COX)-2 inducer. PGE2 and PGF2alpha were the prostanoids released in greatest quantity in response to TNF-alpha. We subsequently measured spontaneous contractility and prostanoid release in porcine ureters treated with 0.1, 1.0, or 10 microM concentrations of indomethacin (nonselective COX inhibitor), NS-398, celecoxib, or 0.1% dimethyl sulfoxide (vehicle) for 2 hours. Ureteral contractility and prostanoid release were measured every 15 minutes after the addition of the various compounds. We also treated ureters with 10 ng/mL TNF-alpha and all three COX inhibitors or dimethyl sulfoxide for 2 and 4 hours and measured the PGE2 and PGF2alpha release. RESULTS: Celecoxib, indomethacin, and NS-398 inhibited ureteral contractility and prostanoid release with similar efficacy and potency. All three compounds also reduced TNF-alpha-induced prostanoid release to control levels at concentrations as low as 0.1 microM. CONCLUSIONS: Our data have indicated that celecoxib and indomethacin inhibit PG release by the ureter to a similar degree, even in the presence of COX-2 induction. Animal experiments and clinical trials evaluating the safety and efficacy of celecoxib for the treatment of symptomatic ureteral obstruction are warranted.

6-Ketoprostaglandin F1 alpha↗
PubMed2005

Survey from skills-based hands on learning courses demonstrates increased laparoscopic caseload and clinical laparoscopic suturing.

OBJECTIVES: To evaluate the impact of the American Urological Association Hands on Laparoscopy course on the participants' practices. Many urologists without fellowship training perform laparoscopy, but do not advance beyond hand-assisted, extirpative laparoscopy. The American Urological Association Hands on Laparoscopy course was designed to help these practitioners advance their skills. METHODS: A total of 68 urologists, aged 31 to 61 years (mean 46.6), participated in one of the four courses given between August 2002 and March 2004. The 2-day course included performing standardized tasks under videotape analysis and participating in porcine and pelvic trainer laboratory sessions. Surveys were sent by regular and electronic mail in September 2004 to assess the courses' impact. The mean follow-up was 15.2 months (range 7 to 25). RESULTS: Of the 68 surveys mailed, 54 were returned (79%). Most respondents were in private practice and had had prior experience with extirpative laparoscopy. Of the respondents, 41 (76%) reported that their laparoscopic practice had expanded after taking the course, with 34% performing at least 2 cases per month. Also, 33 respondents (61%) reported performing laparoscopic suturing after taking the course, with 35% having sutured a bleeding vessel. Of the respondents, 85% reported that the video mentoring during the course was helpful. Of those who purchased a pelvic trainer, 90% reported practicing on it regularly. CONCLUSIONS: The Hands on Laparoscopy course appeared to contribute to expansion of laparoscopic practices. Experience gained from skills-based lectures, videotape analysis of pelvic trainer performance, and a mentored porcine laboratory resulted in most (61%) participants expanding their practice to include clinical laparoscopic suturing.

Adult↗
PubMed2005

Shock wave lithotripsy success determined by skin-to-stone distance on computed tomography.

OBJECTIVES: To evaluate whether the skin-to-stone distance (SSD), body mass index (BMI), and Hounsfield unit (HU) density can be used as independent predictors of stone-free (SF) status after shock wave lithotripsy (SWL) of lower pole kidney stones. No studies have evaluated the SSD by non-contrast-enhanced computed tomography (NCCT) as a predictor of SWL success. Studies have suggested that the BMI and HU density of urinary calculi on NCCT may predict the SF rate after SWL. METHODS: The radiographs of 64 patients treated with SWL (DoliS lithotripter) from March 2000 to April 2004 with lower pole kidney stones measuring 0.5 to 1.5 cm on NCCT were reviewed. The average SSD was calculated by measuring three distances from the center of the stone to the skin (0 degrees, 45 degrees, and 90 degrees angles) on NCCT. The BMI and HU density were determined, and chemical analysis was performed on all stones. Radiographic assessment of the kidneys, ureter, and bladder at 6 weeks categorized patients into the SF or residual stone group. Logistic regression was fit, using SSD, BMI, and HU density as predictors, to assess the SF rates after SWL. RESULTS: Of 64 patients, 30 were SF and 34 had residual stones. The mean SSD was 8.12 +/- 1.74 cm for the SF group versus 11.53 +/- 1.89 cm for the residual stone group (P <0.01). Logistic regression analysis revealed only SSD to be a significant predictor of outcome (odds ratio 0.32, 95% confidence interval 0.29 to 0.35, P <0.01). An SSD greater than 10 cm predicted treatment failure. CONCLUSIONS: The SSD may predict the outcome after SWL of lower pole kidney stones. SWL in patients with an SSD greater than 10 cm is likely to fail. The use of the SSD may be transferable to the treatment of all urinary stones, regardless of location.

Female↗
PubMed2005

Third prize: Prostaglandin E(2)-3 receptor is involved in ureteral contractility in obstruction.

BACKGROUND AND PURPOSE: We previously found that prostaglandin (PG) E2 contracts acutely obstructed ureters while relaxing normal ureters. This study investigated the procontractile effects of the PG EP3 receptor in PGE(2)-mediated contractility in obstructed and normal porcine ureters. MATERIALS AND METHODS: We created unilateral ureteral obstruction laparoscopically using titanium clips in farm pigs; the contralateral ureters were dissected as sham controls. Ureters were harvested 48 hours post-obstruction, cut into 5-mm segments, and suspended in water-jacketed tissue baths in Krebs buffer. Tissues were equilibrated for 1 hour, and spontaneous contractile rates were recorded. After 2 hours of incubation in Krebs (controls) or pertussis toxin (G(alpha)i signaling-protein inhibitor [EP-3 blockade]) 500 ng/mL, a concentration- response curve (10(-9) M-10(-5) M) to PGE(2), PGF(2), sulprostone (EP 3 agonist), or 0.01% ethanol (vehicle) was created (N = 4). RESULTS: In the normal ureters, PGE(2) relaxed both pertussis toxin-treated and control tissues. In obstructed segments, PGE(2) increased contractions by 60%; this was reversed by pertussis toxin to a 67% reduction in contractile rate. In both obstructed and contralateral segments, sulprostone induced contractility in the controls; this was attenuated by pertussis toxin. The PGF(2) produced a contractile effect in both the controls and the pertussis toxin-treated segments, demonstrating the selectivity of pertussis toxin for EP3 receptors. CONCLUSION: Our data indicate that the EP3 receptor is involved in hypercontractility during ureteral obstruction. However, it may not be the sole factor behind the condition-dependent effect of PGE(2).

Animals↗
PubMed2005

Obstruction alters the effect of prostaglandin E2 on ureteral contractility.

BACKGROUND AND PURPOSE: Although our understanding of ureteral physiology during acute obstruction remains limited, we believe that prostanoids (prostaglandins [PGs], thromboxanes, prostacyclins) play a major role in modulation of ureteral contractility and that inhibition of prostanoid synthesis causes substantial reduction in in-vitro and in-vivo ureteral contractility rates. The purpose of this study was to determine the in-vitro effects of PGE2 on chronically obstructed human and acutely obstructed porcine ureters. MATERIALS AND METHODS: Female pigs underwent unilateral laparoscopic ureteral obstruction. Following 1, 2, 6, 24, and 48 hours of obstruction (n = 3 at all points), animals were euthanized, and obstructed, contralateral nonobstructed, and normal (from unobstructed pigs) ureters were harvested. Chronically obstructed human ureter was obtained from subjects who underwent nephrectomy to remove nonfunctioning kidneys. Normal human ureter was obtained from the discarded portion of excess distal ureter in patients undergoing elective donor nephrectomy. Rings 4 to 5 mm long were suspended in aerated Krebs buffer, and their spontaneous contractions and contraction in response to various concentrations of PGE2 were recorded. RESULTS: Prostaglandin E2 increased contractility in chronically obstructed human ureters. In acutely obstructed porcine ureteral segments, low concentrations of PGE2 inhibited ureteral contractility in a dose-dependent fashion, similar to controls. At higher concentrations of PGE2, contractility was increased. This increase was more pronounced with longer intervals of obstruction in a time-dependent manner. CONCLUSION: Prostaglandin E2 increased contractility in obstructed ureters while relaxing normal and nonobstructed ureters. The response to PGE2 was accentuated by a longer duration of obstruction. Prostaglandin E2 may be a unique target for pharmacologic modulation in the treatment of symptoms associated with acute urinary obstruction.

Animals↗
PubMed2005

Prospective, randomized trial comparing shock wave lithotripsy and ureteroscopy for lower pole caliceal calculi 1 cm or less.

PURPOSE: The optimal management of lower pole renal calculi is controversial. We compared shock wave lithotripsy (SWL) and ureteroscopy (URS) for the treatment of patients with small lower pole stones in a prospective, randomized, multicenter trial. MATERIALS AND METHODS: A total of 78 patients with 1 cm or less isolated lower pole stones were randomized to SWL or URS. The primary outcome measure was stone-free rate on noncontrast computerized tomography at 3 months. Secondary outcome parameters were length of stay, complication rates, need for secondary procedures and patient derived quality of life measures. RESULTS: A total of 67 patients randomized to SWL (32) or URS (35) completed treatment. The 2 groups were comparable with respect to age, sex, body mass index, side treated and stone surface area. Operative time was significantly shorter for SWL than URS (66 vs 90 minutes). At 3 months of followup 26 and 32 patients who underwent SWL and URS had radiographic followup that demonstrated a stone-free rate of 35% and 50%, respectively (p not significant). Intraoperative complications occurred in 1 SWL case (unable to target stone) and in 7 URS cases (failed access in 5 and perforation in 2), while postoperative complications occurred in 7 SWL and 7 URS cases. Patient derived quality of life measures favored SWL. CONCLUSIONS: This study failed to demonstrate a statistically significant difference in stone-free rates between SWL and URS for the treatment of small lower pole renal calculi. However, SWL was associated with greater patient acceptance and shorter convalescence.

Adult↗
PubMed2005

Urological intervention in patients with cystinuria is decreased with medical compliance.

PURPOSE: Theoretically patients with cystinuria compliant with medical treatment should undergo fewer surgical procedures than those noncompliant with treatment. We describe a single urologist's experience (SYN) with the effects of medical management on the number of surgical interventions required in patients with cystinuria treated at our metabolic stone clinic (MSC). MATERIALS AND METHODS: The records of 20 patients with cystine stones seen at our MSC (mean followup of 42.5 months) were evaluated. The number of surgical interventions (endourology or open surgery) during followup were recorded as surgical events. Patients were placed into a compliant or noncompliant category based on their attendance record at scheduled appointments at our MSC and whether they adhered to the prescribed medical regimen by report. Patients were classified in an active disease category if recent imaging revealed a clinically significant stone burden greater than 3 mm. Statistical analysis of the number of surgical events for stone-free patients compliant with treatment versus noncompliant was conducted (Student's t test). RESULTS: Of the 20 patients 11 were categorized as compliant and 9 as noncompliant. Of the compliant patients the average number of surgical events was 1.0 per patient versus 4.0 in the noncompliant group (p <0.05). Of the 11 compliant patients 8 (73%) were stone-free compared to 3 (33%) in the noncompliant group. CONCLUSIONS: The majority of our patients with cystinuria compliant with treatment underwent a significantly fewer number of surgical procedures per year than those noncompliant with treatment. Active medical management in patients with cystinuria compliant with treatment decreases the incidence of surgical interventions.

Adolescent↗