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Biomedical subjects

Ryan F Paterson

Publications and source records attributed to Ryan F Paterson.

At least 19 recordsLinked to original sources
PubMed2006

Acute effects of percutaneous tract dilation on renal function and structure.

BACKGROUND: Percutaneous nephrolithotomy (PCNL) is performed on a routine basis for the rapid and efficient removal of large caliceal stones. After percutaneous puncture, rigid dilators or an inflatable balloon are used to dilate the nephrostomy tract to allow access to the collecting system for stone removal. Little is known of the acute impact of tract dilation procedures on renal function. MATERIALS AND METHODS: We compared renal hemodynamic and excretory function in female pigs immediately before and up to 5 hours after percutaneous nephrostomy (PCN) using sequential Amplatz dilators (N = 8) or Nephromax balloon inflation (N = 7) and control pigs with no PCN access (N = 8). We also examined renal function in patients undergoing PCNL. RESULTS: The two PCN procedures produced a renal lesion of comparable size and morphology, as well as similar changes in renal function. Glomerular filtration rate (GFR), renal plasma flow (RPF), and urinary sodium excretion (U(Na)V) were significantly reduced in Amplatz- and Nephromax-treated kidneys throughout the 5-hour observation period, by about 50%, 60%, and 80%, respectively. In control pigs, GFR and RPF remained stable and U(Na)V declined progressively to about 50% of baseline over the course of the experiment. The contralateral kidney showed changes in renal function similar to those in the PCN-treated or control kidney in all three groups. A retrospective analysis of 196 adults with normal renal function who underwent unilateral PCNL using the Nephromax balloon dilator revealed a significant increase in serum creatinine of 0.14 mg/dL at 1 day. CONCLUSION: Both animal and human studies show that PCN is associated with an acute decline in renal function.

Animals↗
PubMed2005

High-powered holmium-laser ablation: comparison of setting effectiveness using tissue-surrogate model.

BACKGROUND AND PURPOSE: The 100-W holmium laser, in conjunction with a sidefiring 550-microm fiber, can ablate prostate glands as large as 40 g to relieve lower urinary-tract symptoms. We evaluated the effect of various setting combinations on ablation efficiency using beef kidney as a tissue-surrogate model. MATERIALS AND METHODS: Beef kidney specimens (mean weight 44.8 +/- 3.1 g) were secured in a cylinder, which was submerged in a water-filled tank through which a 27F resectoscope and 550-microm sidefiring fiber were positioned. Four energy/frequency combinations were tested, with each used to treat 10 kidney specimens. The difference between the mean pretreatment and post-treatment weights of each treatment group were compared statistically with Student's t-test. RESULTS: The largest mean weight difference after treatment (8.94 +/- 2.38 g) was achieved using 3.2 J and 25 Hz. This mass reduction was significantly greater than that of all other combinations except 2.5 J and 40 Hz. CONCLUSIONS: Use of the 3.2 J and 25 Hz setting combination resulted in the greatest amount of ablation in this tissue-surrogate model, suggesting that maximal energy settings may provide an advantage in tissue vaporization using the 100-W holmium laser. Clinical assessment must be performed to substantiate these findings.

Animals↗
PubMed2005

Using and choosing a nephrostomy tube after percutaneous nephrolithotomy for large or complex stone disease: a treatment strategy.

BACKGROUND AND PURPOSE: Percutaneous nephrolithotomy (PCNL) is a well-accepted technique for removal of large or complex renal calculi. However, little attention has been paid to strategies for nephrostomy tube (NT) selection. We reviewed the reasons for selecting three types of NT after PCNL for large or complex stone disease. PATIENTS AND METHODS: A series of 106 consecutive renal units undergoing PCNL for stone burdens >2 cm by a single surgeon (JEL) were reviewed. Noncontrast CT (NCCT) was carried out on postoperative day 1, and secondary procedures were performed if fragments remained. The NTs studied were 8.5F and 10F Cope loops (CP), 20F reentry Malecot catheters (REM), and 20F circle loops (CL). Patient demographics, access site and number, complications, and stone type were examined. "Stone free" was defined as a negative NCCT or negative second-look PCNL. RESULTS: A total of 134 accesses were created in 106 renal units: 35 upper, 7 mid, and 92 lower; however, only 111 NTs were placed: 85 CP (76.6%), 19 REM (17.1%), and 7 CL (6.3%). Sixteen accesses were performed tubeless; all but two were in the upper pole. All 16 of these renal units had a concomitant NT placed in the lower pole. Multiple sites were accessed in 21 patients; 7 of these patients had CL placed. Five of ten patients with spinal-cord injury had REM/CL placed. Nineteen REM were placed: 10 for drainage of infection, and 9 for difficult anatomy. All renal units were rendered stone free: 31.1% with a single procedure and 95.6% with one or two procedures. There were no difficulties with drainage or access for secondary PCNL regardless of the NT employed. Complications included two hydrothoraces, one arteriovenous fistula, and one ureteral perforation. Three of four renal units in patients requiring transfusions underwent bilateral PCNL, and at least one renal unit required multiple accesses. Of kidneys with infection stones, 57.1% required REM or CL; only 12.0% of nonstruvite stones necessitated REM or CL. CONCLUSIONS: All patients having PCNL done for complex stone disease should have an NT placed; however, small (8.5F-10F) CP suffice in most cases and can provide greater patient comfort. To minimize pleural morbidity, tubeless upper-pole access should be considered if the kidney is judged to be stone free at the conclusion of PCNL. Circle loops are useful when multiple accesses are necessary, whereas REM are appropriate if access is difficult, gross residual stone remains, or pain is not an issue (i.e., spinal-cord injury).

Adult↗
PubMed2005

Change in serum prostate specific antigen concentration after holmium laser enucleation of the prostate: a marker for completeness of adenoma resection?

BACKGROUND AND PURPOSE: Holmium laser enucleation of the prostate (HoLEP) is a well-established technique for the treatment of benign prostatic hyperplasia (BPH). To date, changes in serum prostate specific antigen (PSA) after HoLEP have not been published. We hypothesized that HoLEP produces a diminution in PSA similar to that produced by the gold-standard therapies for BPH. To test this hypothesis, we have examined PSA data before and after HoLEP from two institutions performing high volumes of this procedure. PATIENTS AND METHODS: Between August 1998 and September 2004, 509 HoLEPs were performed at two institutions for which complete PSA data were available. Preoperative demographic and transrectal ultrasonography (TRUS) volume measurements were recorded; postoperative pathology and TRUS volume were obtained. Change in PSA as a function of the weight of prostate resected and the relation of preoperative TRUS volume to PSA was determined. RESULTS: The average weight of adenoma resected was 49.8 g (range 5-300 g) in the McGill group and 90.4 g (range 7.9-312 g) in the Methodist Hospital group. The mean decrease in PSA was 81.7% in the McGill group (range 6.0-1.1 ng/mL; P < 0.0001) and 86.0% in the Methodist Hospital group (range 8.6-1.2 ng/mL; P < 0.0001). Log transformed preoperative PSA correlated well with TRUS volume (r = 0.45), as did the weight of adenoma resected with absolute change in PSA (r = 0.38). The TRUS volume decreased significantly, from 111.9 cc to 26.5 cc, in the Methodist Hospital group (P < 0.0001). CONCLUSION: The HoLEP procedure produces a significant diminution in PSA that correlates well with the weight of adenoma resected. Measurement of PSA may be a useful tool for the objective assessment of ablative therapies for BPH, as the reduction in PSA corresponds well with the amount of adenoma removed.

Adenoma↗
PubMed2005

Shock wave lithotripsy of stones implanted in the proximal ureter of the pig.

PURPOSE: Ureteral stones can be difficult to treat with shock wave (SW) lithotripsy. A strategy for lithotripsy of proximal ureteral stones is to push them back into the renal pelvis prior to administering SWs. However, push-back is invasive and not always possible. Since there are few clues to suggest how best to treat ureteral stones with SWs in situ, we developed an animal model for research on lithotripsy for ureteral stones. MATERIALS AND METHODS: Gypsum model stones were implanted bilaterally in the proximal ureter and renal calix of the pig via percutaneous access. Lithotripsy was performed using a HM3 lithotripter (Dornier Medical Systems, Marietta, Georgia) and stones at each location were treated with the same dose (400 SWs, 20 kV and 30 SWs per minute). Fragments were collected and the percent increase in projected surface area of the particles was determined. RESULTS: The breakage (mean percent area increase) of stones implanted in the proximal ureter was significantly less than that of stones located in the renal calix treated with the same dose of shock waves (134% vs 327%, p <0.001). Also, stones that were fully confined by the ureter did not break as well as stones located at the ureteropelvic junction. This indicates that the physical environment surrounding a stone can have a significant effect on the efficiency of SW action. CONCLUSIONS: The observation that stones implanted in the ureter showed decreased breakage compared with stones in the kidney is consistent with clinical experience. This finding is a valuable and even essential prerequisite for any experimental animal model system intended for the study of SW action in the breakage of ureteral stones.

Animals↗
PubMed2005

Stone formation is proportional to papillary surface coverage by Randall's plaque.

PURPOSE: Randall's plaques are common in calcium oxalate (CaOx) stone formers (SF). Plaque coverage correlates directly with urine calcium excretion and inversely with urine volume. We hypothesize that plaque coverage should increase proportionally with increasing stone number. We measured plaque areas in idiopathic CaOx stone formers and nonstone formers (NSF), and identified significant relationships with quantified stone histories. MATERIALS AND METHODS: A total of 13 SFs and 4 control NSFs underwent nephroscopic papillary mapping with representative still images and MPEG (Moving Pictures Experts Group) movies used to identify plaque and papillary borders. Stone histories were obtained through patient interviews, and from medical records and radiographs. The relationship of plaque coverage to clinical stone events was assessed by general multivariate linear modeling. Log transformation normalized the distribution of percent plaque coverage and stone number. RESULTS: Plaque surface area in SFs differed significantly from that in NSFs (p <0.0001). The duration of stone disease and the log transformed percent plaque coverage correlated significantly with the number of stones (0.677 and 0.620, p = 0.003 and 0.008, respectively). On multivariate analysis and correcting for the duration of stone disease total percent plaque coverage correlated significantly with the number of stones (R = 0.496, p = 0.05). Disease duration and plaque coverage did not correlate significantly (p = 0.257). CONCLUSIONS: Percent plaque coverage directly correlates with the number of stones formed even when corrected for the duration of stone disease. However, plaque coverage does not correlate with the duration of stone disease. These results support the hypothesis that the pathogenesis of CaOx stones begins with Randall's plaques.

Biopsy↗
PubMed2004

Helical computed tomography accurately reports urinary stone composition using attenuation values: in vitro verification using high-resolution micro-computed tomography calibrated to fourier transform infrared microspectroscopy.

OBJECTIVES: To assess the ability of helical computed tomography (CT) to differentiate regions of known mineral composition in typical, heterogeneous urinary stones. Interest is substantial in the urologic community in using radiologic imaging to determine accurately the composition of urinary calculi. Recent advances in CT make this a viable prospect, but the heterogeneity of most stones is a complicating factor. METHODS: The ability of micro-CT (a high-resolution laboratory instrument) to identify the mineral composition of stones was confirmed by calibrating micro-CT attenuation values to pure mineral regions of sliced stones using infrared microspectroscopy. Intact human urinary stones were then analyzed by micro-CT, and regions-of-interest of pure mineral were correlated with identical regions-of-interest from quad slice multi-detector row helical CT images. With helical CT, narrow slice widths were used to decrease volume-averaging errors, and bone windows were used so that internal stone structure was visible. RESULTS: When stones were imaged using helical CT at narrow slice widths, mineral-specific regions-of-interest yielded nonoverlapping attenuation values for uric acid (566 to 632 Hounsfield units [HU]), struvite (862 to 944 HU), calcium oxalate (1416 to 1938 HU), and hydroxyapatite (2150 to 2461 HU). CONCLUSIONS: High resolution helical CT yields unique attenuation values for common types of stone mineral, but proper windowing is required to localize regions of homogeneity. The results of this in vitro study suggest that high-resolution helical CT may be able to identify stone composition at patient diagnosis.

Calcium Oxalate↗
PubMed2004

In vitro assessment of lithoclast ultra intracorporeal lithotripter.

PURPOSE: The Lithoclast Ultra (Boston Scientific Corporation, Natick, MA) enables the simultaneous application of ultrasonic and pneumatic modalities for the fragmentation and removal of stones during percutaneous nephrolithotomy (PCNL). We evaluated the effectiveness of this unit using a hands-free in vitro testing system. MATERIALS AND METHODS: An in vitro test system was used to assess the efficiency of stone penetration when the Lithoclast Ultra was operated at different settings of ultrasonic power and pneumatic frequency. The pneumatic and ultrasonic handpieces were assembled, the probes were inserted into an irrigation sheath (Cook Urological, Spencer, IN), and the complete unit was mounted upright (probe tip up). A gypsum artificial stone (mean length 12.8 +/- 0.6 mm; mean diameter 7.6 +/- 0.1 mm) was centered on the probe tip. A weight (63.4 g) was placed atop the stone to provide a constant force. Pneumatic frequency settings of 12, 8, 4, and 1 Hz were tested in conjunction with ultrasonic power settings of 100%, 70%, and 40%. The times required for complete stone penetration were assessed for each combination of settings. Differences in mean stone penetration times were compared using ANOVA. RESULTS: The combination of 12 Hz and 100% produced the fastest mean stone penetration time (8.9 +/- 1.1 seconds). Stone penetration times decreased significantly with increases in pneumatic frequency (P< 0.001) as well as with increases in ultrasonic power (P= 0.001). When analyzing the effect of each modality on the total improvement in penetration time, increasing the pneumatic frequency accounted for approximately 80% of the performance improvement. The stone penetration times were better than those of the most efficient ultrasonic device previously evaluated using this test system. CONCLUSIONS: The Lithoclast Ultra exhibited excellent stone penetration efficiency when evaluated with a hands-free in vitro test system. Increases in either pneumatic frequency or ultrasonic power significantly improve penetration times, with the pneumatic modality contributing the majority of the effect.

Humans↗
PubMed2004

Simultaneous holmium laser enucleation of prostate and upper-tract endourologic stone procedures.

BACKGROUND AND PURPOSE: The holmium laser is a versatile urologic tool. Its unique cutting and coagulating properties allow multiple procedures, such as stone fragmentation and laser enucleation of the prostate (HoLEP), to be performed with a single set-up. This paper reviews our experience with simultaneous HoLEP and endourologic upper-tract stone procedures. PATIENTS AND METHODS: We retrospectively reviewed all 11 patients (12 renal units) treated with the combined approach of HoLEP and an upper-tract endourologic procedure for stone disease. All patients initially underwent HoLEP, followed immediately by percutaneous nephrolithotomy (PCNL)(N=2), ureteroscopy (URS)(N=8), or both (N=1). The mean stone diameter was 34.7 mm for PCNL and 6.7 mm for URS. Outcome data and complications were recorded. RESULTS: The mean preoperative and postoperative American Urological Association Symptom Scores were 21.8 and 6.3, respectively. The mean prostatic specimen weight was 118 g (range 21-376 g), and the mean hospital stay was 1.4 days. For 10 patients with available prostatic specific antigen (PSA) data, the mean preoperative and postoperative values were 6.2 and 0.9 ng/mL, respectively. All patients were catheter free at discharge. All three PCNL patients were rendered stone free; all four URS patients who had radiographic follow-up were stone free. There were no short- or long-term complications, and no transfusions were necessary. CONCLUSIONS: Simultaneous HoLEP and laser lithotripsy are feasible, emphasizing the unique capabilities of the holmium laser. The hemostasis offered by HoLEP allows safe removal of prostatic tissue and urinary calculi, obviating multiple procedures.

Aged↗
PubMed2004

Prostatic intraepithelial neoplasia: an update.

High-grade prostatic intraepithelial neoplasia (HGPIN) is commonly encountered on prostate needle biopsies and, based on epidemiologic, molecular, and animal models, has proven to be the most significant risk factor for prostate cancer and likely represents the premalignant phase of prostatic adenocarcinoma. This lesion is characterized by cellular proliferations within pre-existing ducts and glands, with nuclear and nucleolar enlargement similar to prostate cancer. However, unlike cancer, HGPIN retains a basal cell layer identifiable by immunohistochemistry with the basal cell-specific antibody cytokeratin 34bE12. The incidence of HGPIN identified in needle biopsies is as high as 25%, increases with age, and coexists with prostate cancer in approximately 85% of cases. There appears to be no causal relationship between HGPIN and serum prostate-specific antigen (total, percent free, or density) or radiographic characteristics on transrectal ultrasound. In a large series, the identification of HGPIN on initial needle biopsy is associated with about a 35% risk of prostate cancer on subsequent biopsies. Thus, the finding of HGPIN on prostate needle biopsy necessitates a second biopsy in a patient eligible for curative treatment. As a precursor lesion, HGPIN is currently a target for chemopreventive strategies, including antiandrogens and nutritional supplementation.

Biopsy↗
PubMed2003

Molecular genetic alterations in the laser-capture-microdissected stroma adjacent to bladder carcinoma.

BACKGROUND: Urothelial carcinoma commonly manifested loss of heterozygosity (LOH) at different regions of chromosomes 17p, 3p, and 9q. Recent studies suggested that bladder stromal cells may be implicated in the growth and progression of urothelial carcinoma. To better understand the genetic alterations in the stromal cells in patients with bladder carcinoma, the authors evaluated the prevalence of allelic loss at three microsatellite polymorphic markers on chromosomes 17p13 (TP53), 3p25-26 (D3S3050), and 9q32-33 (D9S177). In addition, the pattern of X-chromosome inactivation of the stromal cells was evaluated by analyzing the DNA methylation pattern at a polymorphic site on the androgen receptor gene. METHODS: The authors studied 18 female patients who underwent either transurethral resection (n = 2) or radical cystectomy (n = 16) for high-grade muscle-invasive urothelial carcinoma of the urinary bladder. Genomic DNA samples from the stromal cells immediately adjacent to the tumor and the tumor itself were prepared from formalin-fixed, paraffin-processed tissues using laser-assisted microdissection and LOH was determined. RESULTS: The stromal cells showed a high frequency of LOH on chromosomes 17p13 (29%), 3p25-26 (61%), and 9q32-33 (47%) with no clear concordance with the adjacent tumor cells. Fourteen specimens (78%) showed LOH in the stroma in at least 1 of 3 markers examined. Nonrandom X-chromosome inactivation was frequent in the stromal cells (50% of informative specimens). CONCLUSIONS: The current study revealed that some of the genetic changes that commonly occur with invasive urothelial carcinoma were frequently found in the adjacent stroma and suggested that the stroma of urothelial carcinoma may play an important role in bladder carcinogenesis.

Carcinoma, Transitional Cell↗
PubMed2003

Holmium Laser Enucleation of the Prostate (HoLEP): A Technical Update.

INTRODUCTION: Holmium laser enucleation of the prostate (HoLEP) combined with mechanical morcellation represents the latest refinement of holmium:YAG surgical treatment for benign prostatic hyperplasia (BPH). Utilizing this technique, even the largest of glands can be effectively treated with minimal morbidity. The learning curve remains an obstacle, preventing more widespread adoption of this procedure. This paper provides an outline of the HoLEP technique as is currently used at two centers in hopes of easing the initial learning curve. TECHNICAL CONSIDERATIONS: Detailed descriptions of the major steps of the HoLEP procedure are provided with attention to critical steps such as identification of the surgical capsule, median and lateral lobe enucleation, and morcellation of enucleated tissue. CONCLUSIONS: HoLEP is a promising alternative for the surgical treatment of BPH which allows complete removal of intact lobes of the prostate. Obstruction is relieved immediately with superior hemostasis, no risk of TUR syndrome, and a minimal hospital stay.

Journal Article↗
PubMed2003

Laparoscopic partial kidney ablation with high intensity focused ultrasound.

PURPOSE: High intensity focused ultrasound has been performed for transrectal and extracorporeal thermal ablation of tissues. We developed and tested a laparoscopic probe that allows real-time ultrasound imaging during partial renal ablation using high intensity focused ultrasound. METHODS: A Sonablate 200 (Focus Surgery, Indianapolis, Indiana) high intensity focused ultrasound system with a modified 18 mm. laparoscopic probe was used in all experiments. In 13 Yucatan mini-pigs a 5Fr ureteral catheter was inserted into the renal pelvis and 10 cc air were instilled into the collecting system. The kidney was laparoscopically dissected, the high intensity focused ultrasound probe was inserted through a 33 mm. laparoscopic port and the targeted renal pole was treated. RESULTS: Renal lesions were created in 12 of 13 treated kidneys under real-time ultrasound visualization. Median operative time was 180 minutes, average high intensity focused ultrasound activation time was 18.3 minutes and lesion size was 23 x 17 x 11 mm. At 4 and 14 days 4 (acute group) and 6 (subacute group) animals were available for renal functional and anatomical evaluation, respectively. No difference in renal function was seen in treated and untreated kidneys. Pathological examination at 14 days revealed homogenous and complete tissue necrosis throughout the whole volume of the lesion with sharp demarcation from adjacent normal tissue. CONCLUSIONS: We were able to refine a probe for laparoscopic high intensity focused ultrasound delivery capable of simultaneous ultrasound imaging. Partial renal ablation using this probe is feasible and safe, and resulted in homogenous, complete and reproducible lesions.

Animals↗
PubMed2003

Holmium laser enucleation of the prostate: morbidity in a series of 206 patients.

OBJECTIVES: To review the complications associated with 206 holmium laser enucleation of the prostate (HoLEP) procedures. HoLEP is a minimally invasive surgical treatment for benign prostatic hyperplasia. METHODS: A retrospective review was conducted of HoLEPs performed from April 1, 1999 to October 1, 2001. Patients with previous diagnoses of prostate carcinoma or who had undergone HoLEP after admission for unrelated problems were excluded. Demographic, intraoperative, and immediate postoperative data were recorded to determine the incidence of complications. Patients were also contacted by telephone or mailed surveys for documentation of longer term complications. RESULTS: The mean age and procedure time was 70.5 years (range 45 to 91) and 133.6 minutes (range 25 to 473), respectively. The mean specimen weight was 68.2 g (range 3 to 376), with 20 (9.7%) of 206 patients diagnosed with adenocarcinoma. The mean hospital stay was 1.1 days, with 86.9% of patients discharged after an overnight stay without a catheter. Two patients required postoperative transfusions (1.0%). No deaths, major complications (myocardial infarction or pulmonary embolism), or transurethral resection syndrome episodes occurred. Intraoperative complications consisted of three capsular perforations (1.5%), one bladder neck false passage (0.5%), four incomplete morcellations (1.9%), and four minor bladder mucosal morcellation injuries (1.9%). Of 206 patients, 173 (84.0%) provided follow-up data (mean 19.0 +/- 8.4 months), allowing documentation of longer term complications, including five clot retention episodes (2.4%), five urethral strictures (2.4%), eight bladder neck contractures (3.9%), and 16 patients requiring re-catheterization (7.8%). CONCLUSIONS: HoLEP can be performed with minimal complication risks and blood loss. Patients can expect an overnight hospital stay and discharge without an indwelling catheter.

Adenocarcinoma↗
PubMed2003

Variability of renal stone fragility in shock wave lithotripsy.

OBJECTIVES: To measure, in an in vitro study, the number of shock waves to complete comminution for 195 human stones, representing six major stone types. Not all renal calculi are easily broken with shock wave lithotripsy. Different types of stones are thought to have characteristic fragilities, and suggestions have been made in published reports of variation in the fragility within some types of stones, but few quantitative data are available. METHODS: Kidney stones classified by their dominant mineral content were broken in an unmodified Dornier HM3 lithotripter or in a research lithotripter modeled after the HM3, and the number of shock waves was counted for each stone until all fragments passed through a sieve (3-mm-round or 2-mm-square holes). RESULTS: The mean +/- SD number of shock waves to complete comminution was 400 +/- 333 per gram (n = 39) for uric acid; 965 +/- 900 per gram (n = 75) for calcium oxalate monohydrate; 1134 +/- 770 per gram (n = 21) for hydroxyapatite; 1138 +/- 746 per gram (n = 13) for struvite; 1681 +/- 1363 per gram (n = 23) for brushite; and 5937 +/- 6190 per gram (n = 24) for cystine. The variation for these natural stones (83% +/- 15% coefficient of variation) was greater than that for artificial (eg, gypsum-based) stones (17% +/- 8%). CONCLUSIONS: The variability in stone fragility to shock waves is large, even within groups defined by mineral composition. Thus, knowing the major composition of a stone may not allow adequate prediction of its fragility in lithotripsy treatment. The variation in stone structure could underlie the variation in stone fragility within type, but testing of this hypothesis remains to be done.

Humans↗
PubMed2003

Urine calcium and volume predict coverage of renal papilla by Randall's plaque.

BACKGROUND: Renal papillary plaques are common in calcium stone formers. We hypothesized that plaque should increase directly with urine calcium excretion, and inversely with urine volume. To test this, we measured papillary plaque areas in both idiopathic calcium oxalate stone formers and nonstone formers and examined 24-hour urine data to identify significant correlations. METHODS: Fourteen stone formers and four nonstone forming controls underwent papillary mapping with flexible nephroscopy. For each papillum, representative still images and moving pictures expert group (MPEG) movies were used to identify plaque extent and papillary borders. The mean fractional plaque coverage for each polar region (upper, inter, lower) and per papillum was calculated. The relationship of the plaque coverage data to urine measurements was assessed with general multivariate linear modeling. RESULTS: Mean polar fractional plaque coverage was higher in the calcium oxalate stone formers (7.4% vs. 0.5%, P= 0.012) as was mean fractional plaque per papillum (7.6% vs. 0.6%, P= 0.011). When correlating mean polar plaque coverage to urine data, urine volume and calcium excretion were the only measurements with independent relationships to plaque (P= 0.002, adjusted multiple R2= 0.521), with higher calcium and lower volume increasing coverage. The same relationships hold for mean plaque per papillum, except that urine pH also becomes an independent factor (P= 0.001, adjusted multiple R2= 0.606). CONCLUSION: Utilizing advanced digital video and endoscopic equipment, we have achieved the most accurate estimation of papillary plaque coverage to date. Our findings support the idea that urine volume and calcium are the main correlates of plaque coverage.

Calcium↗
PubMed2003

Laparoscopic ileocytoplasty and continent ileovesicostomy in a porcine model.

BACKGROUND AND PURPOSE: Bladder augmentation with autologous bowel is commonly accompanied by a continent ileovesicostomy (the Monti procedure). Herein, we describe our initial experience with laparoscopy-assisted ileocystoplasty and continent ileovesicostomy in a porcine model. MATERIALS AND METHODS: Thirteen Yucatan minipigs with an average weight 49 lb underwent a laparoscopy-assisted ileocystoplasty and ileovesicostomy (Monti procedure) using a four-port technique. After catheter removal at 3 weeks, the animals underwent twice-daily catheterization of the ileovesicostomy until complete occlusion of the ileovesicostomy occurred. RESULTS: All animals survived the initial surgery, with 10 animals being available for catheterization at 3 weeks. The average Monti anastomotic time, average ileal patch-bladder anastomotic time, and average total surgery times were 47 minutes, 89 minutes, and 307 minutes, respectively. Eight of ten animals developed stomal stenosis after catheter removal (average time to complete occlusion of 6 days; range 1-13 days), with two animals also demonstrating partial obstruction at the Monti-bladder anastomosis and four partial obstruction at the fascial level of the Monti tube. Pathologic review of select bladder augmentation and Monti tube specimens revealed moderate to severe acute and chronic inflammation with severe scarring at the Monti-skin stoma site in the majority of specimens. CONCLUSIONS: We have demonstrated the feasibility of laparoscopic ileocystoplasty and continent ileovesicostomy in a porcine model. The development of stomal stenosis may be related to the intrinsic properties of the pig skin, but additional investigation is required prior to human studies of this novel surgical technique.

Anastomosis, Surgical↗