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Biomedical subjects

Kent T Perry

Publications and source records attributed to Kent T Perry.

15 recordsLinked to original sources
PubMed2006

Fat poor renal angiomyolipoma: patient, computerized tomography and histological findings.

PURPOSE: We reviewed our experience with fat poor cases of angiomyolipoma. MATERIALS AND METHODS: The records of patients with angiomyolipoma, as determined by pathological study, from 1998 to 2004 were reviewed by recording patient demographics and outcomes. Fat poor cases were defined as the failure of imaging to demonstrate fat in a lesion. Computerized tomography and histological characteristics were assessed. RESULTS: Histologically confirmed angiomyolipoma was found in 15 patients. Multiple lesions were found in 3 of 15 cases (20%). Of these 15 patients who underwent surgery 11 (73%) had unsuspected angiomyolipoma due to absent fat on computerized tomography and they underwent intervention for presumed renal cell carcinoma. Mean age +/- SD in this group was 54 +/- 15 years and 8 of 11 patients (73%) were female, of whom 4 (50%) had uterine fibroids. These lesions were found incidentally in 7 of 11 cases (64%). Operative complications developed in 2 of 11 patients (18%). Average maximal diameter on pathological evaluation was 3.2 +/- 1.3 cm (range 1.5 to 6). Nonenhanced computerized tomography was available in 7 of 11 cases, of which 3 of 7 (42%) showed hyperdense lesions and 4 of 7 (57%) showed isodense lesions. The percent of fat identified per high power field was less than 25% in 12 of 13 fat poor angiomyolipoma lesions (92%) compared to 2 of 4 classic lesions (50%) known to be angiomyolipoma before surgery (p = 0.04). CONCLUSIONS: We suggest that a general definition of fat poor angiomyolipoma should be the failure of imaging to reveal fat within a lesion, thus, making it unsuspected at surgery. A pathological definition should be less than 25% fat per high power field, which to our knowledge is a formerly undefined quantity. Not all cases are hyperdense on nonenhanced computerized tomography. These lesions cannot be reliably identified by imaging and they should be managed like all enhancing renal masses.

Adipose Tissue↗
PubMed2006

Urothelial-cell carcinoma and solitary kidney: outcomes with renal-sparing management.

PURPOSE: To review our experience with renal-sparing approaches for upper-tract transitional-cell carcinoma (UT-TCC) associated with solitary kidneys. PATIENTS AND METHODS: Ten patients with UT-TCC associated with solitary kidneys who were managed with renal-sparing approaches from 2000 to 2004 were identified. Patient data were gathered retrospectively, and a patient interview was conducted. A literature review was performed, and our results were compared with those from selected other authors. The mean follow-up was 33 months. RESULTS: Eight patients (80%) developed recurrence after initial treatment necessitating further intervention. The average number of procedures was nine per patient, and an average of two cycles of topical therapy was given. At the end of the follow-up period, 6 patients (60%) were disease free. Of these 6 patients, 2 (33%) required interval nephroureterectomy because of disease progression in one and renal insufficiency leading to dialysis in the other. Metastatic disease occurred in four patients during the surveillance interval, including one patient with a nephrostomy-site recurrence. Three patients died from their disease during the follow-up period, and one patient remained alive after chemotherapy. The overall survival rate was 70% at 33 months. Of the living patients, 6 (86%) could be reached for comment, and all were very satisfied with their renal-sparing management. CONCLUSIONS: Renal-sparing approaches remain an option in motivated patients with solitary kidneys and UT-TCC. Patients should realize that management tends to involve multiple procedures that are associated with potential morbidity, entails lifetime follow-up, and often requires long-term nephrostomy access for topical treatment or relief of obstruction. Long-term patient quality-of-life and cancer-specific outcomes for renal- sparing management compared with quality-of-life and survival on dialysis are unknown.

Aged↗
PubMed2006

Mixed epithelial and stromal tumor of the kidney and cystic nephroma share overlapping features: reappraisal of 15 lesions.

CONTEXT: Cystic nephroma is a rare cystic tumor, which only recently has been recognized as an exclusively adult lesion. Mixed epithelial and stromal tumor of the kidney is also a rare, recently recognized, biphasic tumor composed of tubular and cystic elements embedded in grossly recognizable spindle cell stroma. The histogenesis of both lesions is unclear. OBJECTIVES: To compare clinical phenotype, morphology, and immunohistochemistry in mixed epithelial and stromal tumor of the kidney and cystic nephroma in order to explore the relationship between these 2 lesions. DESIGN: Fifteen biphasic lesions (8 mixed epithelial and stromal tumors of the kidney and 7 cystic nephromas) were studied. All cases were reviewed and subjected to detailed pathologic studies, and the results were correlated with clinical findings. RESULTS: Mixed epithelial and stromal tumor of the kidney occurred exclusively in women aged 36 to 80 years (mean, 49.7 years), all of whom had a history of estrogen therapy and/or obesity. Cystic nephroma occurred in both sexes; patients were aged 22 to 71 years (mean, 50.4 years), and a history of hormonal therapy was present on occasion. All 15 lesions were benign. Lesions varied by size, the proportion of cystic component, and the amount and cellularity of stroma. However, in all lesions tested, the stroma was diffusely positive for smooth muscle actin, and smooth muscle differentiation was confirmed by electron microscopy. In mixed epithelial and stromal tumors of the kidney, the stroma was positive for estrogen and progesterone receptors in 4 of 5 lesions tested. In cystic nephroma, focal positivity for hormone receptors was seen in 2 of 7 tumors tested; both positive lesions were from women. The epithelial lining in both mixed epithelial and stromal tumor of the kidney and cystic nephroma lesions was variable with regard to shape, cytoplasmic appearance, and immunophenotype (with focal positivity for CD10, cytokeratin 7, high-molecular-weight keratin, and Ulex europaeus detectable in both lesions). This pattern suggests variable differentiation, which was confirmed by electron microscopic studies (performed in 1 case). CONCLUSIONS: While mixed epithelial and stromal tumor of the kidney has a strong association with the female sex and hormonal milieu, cystic nephroma can affect both sexes and, on occasion, may also have hormonal associations. Morphologically, there is considerable overlap between both lesions, which suggests that they may represent opposite ends of the spectrum of the same process. Our studies also suggest that the tubules may be entrapped rather than comprising an intrinsic component of the tumor. However, further studies, including molecular studies, are needed to support this hypothesis.

Adult↗
PubMed2005

Assessment of novel ureteral occlusion device and comparison with stone cone in prevention of stone fragment migration during lithotripsy.

PURPOSE: To present the initial ex-vivo results of a new ureteral-occlusion device (Cook Urological, Spencer, IN) for preventing the retrograde migration of particles during ureteroscopy and its comparison with the Stone Cone (Microvasive-Boston Scientific Corp., Spencer, IN). MATERIALS AND METHODS: We designed an ex-vivo model using a porcine kidney with an intact ureter. Standardized plastic beads were placed in the proximal ureter. Each device was deployed proximal to the beads during ureteroscopy, and the number of beads impeded by each device was recorded. RESULTS: The new device was successful at preventing retrograde migration of beads > or = 1.5 mm. Furthermore, 1.0-mm beads were impeded by the center of the device, although they passed through the periphery. The Stone Cone blocked the retrograde migration of beads > or = 2.5 mm. CONCLUSION: The new occlusion device was efficacious in an ex-vivo model. It appears to prevent the migration of smaller particles than are blocked by the Stone Cone.

Animals↗
PubMed2005

Endoscopic injection of fibrin glue for the treatment of urinary-tract pathology.

BACKGROUND AND PURPOSE: Urinary-tract fistulas present unique clinical challenges that often necessitate open surgical excision with interposition of healthy tissue. Advances in retrograde instrumentation have enabled endourologists to employ more minimally invasive approaches to urologic disease, including fistulas. We reviewed our experience with endoscopic injection of fibrin glue for the treatment of urinary-tract pathology. PATIENTS AND METHODS: We performed a retrospective review of the eight patients at our institution who have undergone retrograde endoscopic injection of fibrin glue for the treatment of urinary-tract pathology. The data collected included age, presentation, treatment technique, method/duration of follow-up, complications, and success, which was defined as subjective and objective resolution of the treated pathology. RESULTS: One of these patients was treated for a caliceal diverticulum refractory to percutaneous ablation. The other seven patients were treated for fistulas, including one colovesical fistula, two vesicovaginal fistulas, one ileal conduit-cutaneous fistula, one ureterocutaneous fistula, one urethrocutaneous fistula, and one ureterorectal fistula. All lesions except the urethrocutaneous fistula and the ureterorectal fistula were treated with a single injection of fibrin glue. At a mean follow-up of 11.75 months, this technique was successful in six cases (75%). Two (33%) of the successfully treated patients required two injections. There were no complications. Failures were apparent at initial follow-up. CONCLUSION: Retrograde endoscopic injection of fibrin glue offers a novel approach to ablation of caliceal diverticula. Additionally, although open surgical excision of urinary-tract fistulae remains the gold standard treatment, endoscopic injection of fibrin glue offers a safe, minimally invasive approach that may avoid the morbidity of open surgery in such challenging patients.

Adult↗
PubMed2005

Feasibility of nerve-sparing prostate cryosurgery: applications and limitations in a canine model.

BACKGROUND AND PURPOSE: In a canine model, we evaluated the feasibility of nerve-sparing cryosurgery by active warming of the neurovascular bundle (NVB). Furthermore, our aim was to determine if NVB warming increases the risk of acinar gland and stromal-tissue preservation in adjacent areas of the prostate. The effects of a single versus double freeze-thaw cycle on prostate tissue were also assessed. MATERIALS AND METHODS: Ten prostate lobes from five dogs were evaluated. Nine lobes from five dogs were treated with cryoablation using 17-gauge gas-driven cryoneedles. Seven lobes wre treated with active warming of the NVB using helium gas, and two lobes were treated without active warming. A single or double freeze-thaw cycle was utilized. Prostate tissue ablation and NVB preservation were evaluated in histologic sections. RESULTS: All seven prostate lobes treated with active warming demonstrated complete or partial NVB preservation. Four of these lobes had adjacent gland preservation. All lobes treated with a double freeze-thaw cycle showed complete and uniform ablation of prostate tissue. One of the three lobes treated with a single freeze-thaw cycle demonstrated incomplete ablation of the tissue. CONCLUSIONS: This is the first study investigating the feasibility of NVB preservation under controlled experimental conditions. In our canine model, NVB preservation with active warming was possible but not consistently reproducible. In some cases, NVB preservation with active warming may result in incomplete peripheral tissue ablation. A double, but not a single, freeze-thaw cycle induces complete and effective necrosis of prostatic tissue. These results have significant clinical applications when attempting nerve-sparing cryosurgical ablation of the prostate.

Animals↗
PubMed2005

Load-release points of two novel ureteral stone-trapping devices.

PURPOSE: We compared the load-release points of the Stone Cone and the new Cook Urological NTrap devices using an in vitro model of the ureter. MATERIALS AND METHODS: A strictured-ureter model was created using urethane tubing with a wire tie around it. A plastic bead was lodged above this narrowing. The Stone Cone, then the NTrap, was deployed in turn above this bead. The force required for each device to undeploy was measured over five trials. RESULTS: Each device released the bead in every trial. The Stone Cone released at a mean of 0.190 lb, while the NTrap yielded at 0.861 lb. CONCLUSIONS: Both of the devices released the plastic bead reliably and at low loads, although the NTrap did require statistically significantly more force than the Stone Cone. However, the loads for both devices were <1 lb, so the devices are unlikely to result in ureteral trauma. Whether a slight increase in load-release force or differences in design result in better stone-clearing ability of one device should be assessed in clinical trials.

Equipment Design↗
PubMed2005

The effects of intentional cryoablation and radio frequency ablation of renal tissue involving the collecting system in a porcine model.

PURPOSE: Ablative techniques for the treatment of urological malignancy are gaining acceptance and they are likely to become more widely used in clinical practice. Indications and limitations of the technologies are still evolving. In a porcine model we evaluated the safety and efficacy of cryotherapy and radio frequency ablation (RFA) of cortical and deep renal tissue. MATERIALS AND METHODS: In 11 swine argon gas based cryoablation or RFA of renal tissue adjacent to the collecting system was performed using a laparoscopic or percutaneous approach. Lesions created in renal units 30 days or 2 hours prior to harvest were termed chronic or acute. Using single or multiple 17 gauge cryoneedles or 3.0 mm cryoprobes and 2 freeze-thaw cycles (10-minute freeze and 5-minute thaw) 13 acute and 10 chronic cryolesions were made. Using a single 16 gauge umbrella-shaped RFA probe and 2 heating cycles to maximum impedance 13 acute and 4 chronic RFA lesions were made. Gross and microscopic tissue analysis was performed to assess lesion size and renal parenchymal, collecting system and arterial effects. Acute cryolesion size estimation by laparoscopic or transcutaneous ultrasound (US) was compared with pathological lesion size. RESULTS: Acute cryolesions on hematoxylin and eosin staining demonstrated uniform coagulative necrosis of renal parenchyma and chronic cryolesions demonstrated uniform necrosis with fibrous scar formation. Interlobar artery (adjacent to renal pyramid) preservation occurred in 7 of 13 acute and 5 of 9 chronic cryolesions. Urothelial architecture was preserved in 8 of 13 acute and 7 of 9 chronic cryolesions. Acute and chronic RFA lesions demonstrated indeterminate necrosis on hematoxylin and eosin staining, although triphenyl tetrazolium chloride staining of gross specimens confirmed necrosis most definitively in renal cortex. Interlobar artery preservation occurred in 6 of 13 acute and 3 of 4 chronic RFA lesions. Urothelial architecture was preserved in 1 of 13 acute and 2 of 4 chronic RFA lesions. Acute cryolesion dimensions measured by laparoscopic US equaled or underestimated lesion size measured grossly in all 6 cases. Lesion dimensions measured by transcutaneous US equaled or underestimated true lesion size in 3 of 6 cases. In 3 of 6 lesions transcutaneous US overestimated true lesion size by 20%, 76% and 260%, respectively. CONCLUSIONS: Renal cortical tissue can be effectively destroyed by cryoablation or RFA. However, treatment of deep parenchymal lesions with either modality may result in incomplete ablation. Cryosurgery but not RFA spares the collecting system in an acute setting. However, healing or regrowth of the urothelium may occur with time after RFA. Laparoscopic US is more accurate for cryolesion monitoring than transcutaneous US.

Animals↗
PubMed2005

Renal neoplasms in younger adults: analysis of 112 tumors from a single institution according to the new 2004 World Health Organization classification and 2002 American Joint Committee on Cancer Staging System.

CONTEXT: Adult renal neoplasms have a predilection for older patients and are clinically and morphologically distinct from renal neoplasms found in pediatric age groups. Relatively rare tumors occur in younger adults (18-45 years of age). Whether these renal tumors are morphologically and clinically distinct from those of older adults has been the subject of controversy. Recent modification of the World Health Organization histologic classification and the American Joint Committee on Cancer staging system of adult renal tumors further highlighted the need for case analysis in this age group. OBJECTIVE: To analyze renal tumors in younger adults based on a large surgical series from a single institution. DESIGN: Of 780 renal mass nephrectomy (partial, total, or radical) specimens that were available for evaluation and had been obtained between 1986 and 2004 at Loyola University Medical Center, 112 specimens were from patients between 18 and 45 years of age. The tumors were reevaluated according to the 2004 World Health Organization classification and the 2002 American Joint Committee on Cancer staging system. RESULTS: The likelihood of clear cell renal cell carcinoma was significantly reduced from 65% in older adults to 53% in younger adults (18-45 years, P = .04). The reduction trend was more significant when comparing an even younger age group. The majority (64%) of clear cell renal cell carcinoma in younger adults was low stage, T1a. Seventeen percent of these tumors had multilocular cystic features involving more than 50% of the tumor volume (55%-85%). The number of oncocytomas was also significantly lower in younger adults than in older adults (2% vs 11%, P < .001), and this presumably age-related benign neoplasm was not identified in patients younger than 40 years in this study. In contrast, the miscellaneous tumor category showed a remarkable increase, from 4% in older adults to 26% in younger adults (P < .001). The youngest patient group (18-35 years) had a higher incidence of miscellaneous tumors, 37%. Younger female adults tended to have more benign miscellaneous neoplasms than did their male counterparts (64% vs 36%, P < .001). Clear cell and chromophobe renal cell carcinoma occurred more frequently in younger male adults than in female adults (2:1 and 8:1, respectively). CONCLUSIONS: Renal neoplasms are more heterogeneous in younger adults and have a different distribution pattern compared with that in older adults. Malignant and benign renal neoplasms tend to have a contrasting sex distribution in younger adults.

Adult↗
PubMed2004

Improved functional deflection with a dual-deflection flexible ureteroscope.

PURPOSE: To compare the maximal active deflection capabilities of a newly designed dual-deflection ureteroscope with those of a standard flexible ureteroscope. MATERIALS AND METHODS: The dual-deflection ureteroscope is similar in design to single-deflection ureteroscopes with the addition of a second, more proximal unidirectional deflection point, which is controlled with the index finger on the contralateral side of the instrument. We evaluated the maximal deflection angles achieved with this ureteroscope with no inserted devices as well as with 200-, 365-, and 550-microm laser fibers and a 3F Nitinol wire basket in the working port. We compared these angles with those obtained with the Dur-8 single-deflection ureteroscope. RESULTS: The dual-deflection ureteroscope allowed a superior maximum active deflection angle of 234.3 degrees with an empty working channel compared with only 143 degrees for the standard single-deflection ureteroscope. Instruments in the working channel dampened the active deflection of both ureteroscopes. The average maximum upward angles achievable with the single-deflection ureteroscope with the 200-, 365-, and 550-microm laser fibers and the 3F basket were 115.3 degrees, 92 degrees, 46.6 degrees, and 123.3 degrees, respectively. The average deflection angles with the dual-deflection endoscope deflected at the distal point were similar to those obtained with the single-deflection ureteroscope. In contrast, the average maximum deflection angles obtained with the dual-deflection endoscope deflected at both points with a 200-, 365-, and 550-microm laser fiber and a 3F basket in the working channel were 211 degrees, 183.3 degrees, 109 degrees, and 224 degrees, respectively. The degree of dampening by larger instruments was greater in the single-deflection than the dual-deflection ureteroscope. CONCLUSIONS: The double-deflection ureteroscope can achieve superior active deflection compared with a standard ureteroscope. The second active angle allows the use of larger instruments in the working port with a smaller impact on overall deflection. The double-deflection ureteroscope should be beneficial in the management of difficult-to-treat lower-pole renal calculi and may allow some patients who would have required percutaneous nephrolithotomy to undergo ureteroscopic management of their stone disease.

Humans↗
PubMed2003

Laparoscopic partial nephrectomy and minimally invasive nephron-sparing surgery.

Surgical extirpation remains the most effective therapy for renal cell carcinoma. The surgical management of renal masses has evolved away from radical nephrectomy and now includes nephron-sparing surgery for small tumors. Nephron-sparing surgery has similar cure rates and does not appear to compromise cancer control. As the detection of small renal masses by widespread abdominal imaging continues to increase, so will the demand for minimally invasive nephron-sparing procedures. Despite progress in surgical techniques, laparoscopic partial nephrectomy remains a technically challenging procedure. In this review, we discuss the challenges and recent advances in laparoscopic partial nephrectomy and other minimally invasive approaches to renal masses.

Carcinoma, Renal Cell↗
PubMed2003

Quality of life, pain and return to normal activities following laparoscopic donor nephrectomy versus open mini-incision donor nephrectomy.

PURPOSE: We evaluated pain, convalescence and health related quality of life in patients undergoing laparoscopic and open mini-incision donor nephrectomy. MATERIALS AND METHODS: We compared the records of consecutive patients who underwent laparoscopic and mini-incision open donor nephrectomy from our donor nephrectomy data base in retrospective fashion using 2 questionnaires. The first questionnaire evaluated postoperative pain, return to functioning time and satisfaction. The second questionnaire was the RAND 36-Item Health Survey, version 2, a standardized and validated health survey quality of life assessment tool. Mean patient sex, age and followup were similar for the 2 groups. All data were analyzed using the 2-tailed t test for independent variables with commercially available statistical analysis software. RESULTS: Pain in the laparoscopic group was significantly less than in the mini-incision group at all followup time points (p <0.05). Statistically significant differences demonstrated that laparoscopy led to more rapid recovery time in certain categories, including walking, discontinuation of prescribed oral pain relievers, return to driving, and resumption of normal work and home daily activities. More subjective questions in the survey showed high levels of acceptance for the 2 procedures. Using the RAND 36-Item Health Survey, version 2 health related quality of life was significantly higher in the laparoscopy group in 3 domains that measure bodily pain, physical functioning and emotional role functioning. However, each group scored at or above age matched American averages in all domains. CONCLUSIONS: The laparoscopy group had significantly less postoperative pain and required less time to return to normal functional activities than the mini-incision group. In addition, the laparoscopic group showed significantly higher quality of life scores than the mini-incision group in 3 domains.

Activities of Daily Living↗
PubMed2002

Use of heparin and protamine sulfate during laparoscopic donor nephrectomy.

BACKGROUND: Our aim was to evaluate the necessity of heparin and protamine administration during laparoscopic donor nephrectomy. METHODS: Data from 52 consecutive living-related laparoscopic donor nephrectomies performed at University of California Los Angeles between August 1999 and August 2001 were used for this analysis. For the purpose of this analysis, the patients were divided into three cohorts: group A received both heparin and protamine; group B received heparin only; and group C received neither. Intraoperative blood loss, length of admission, recipient creatinine at follow-up, and intraoperative and postoperative complications were compared between the groups. Statistical analysis was performed using a two-tailed test. RESULTS: There were no significant differences between the groups with regard to patient age and gender. Intraoperative blood loss did not differ between group B (99+/-73 mL) and group C (82+/-54 mL) ( =0.4). None of the patients required blood transfusion. No graft loss occurred in any group. Length of hospital stay, excluding any preoperative days, was similar (2.8+/-0.7, 2.9+/-1.6, and 2.5+/-0.8 days, for groups A, B, and C, respectively, ( >0.05). No systemic thromboembolic complications were noted in any of the groups. One patient in group B was converted to an open procedure because of a difficult dissection unrelated to heparin administration. The mean recipient creatinine levels at follow-up in the recipients of kidneys from groups A, B, and C were not significantly different (1.1, 1.3, and 1.3; >0.05) through the extended follow-up period of 691, 286, and 97 days, respectively. CONCLUSIONS: According to our experience, there is no apparent benefit in the administration of heparin alone or in the administration of protamine sulfate to reverse heparin anticoagulation during laparoscopic donor nephrectomy if heparin is given. This is not only in terms of bleeding complications but is also true in regard to recipient renal function through the follow-up period. It is important to note that our warm ischemic times were less than 2 minutes, because longer warm ischemic times may make the use of heparin a more important consideration. This is the first time that these questions have been studied in the laparoscopic donor nephrectomy population.

Adult↗