Guy Lindberg

LAPAROSCOPIC RADIOFREQUENCY THERMAL ABLATION OF RENAL TISSUE WITH AND WITHOUT HILAR OCCLUSION

PURPOSE Few studies have evaluated the effect of radiofrequency thermal ablation on renal tissue, although it has been used clinically to treat small renal masses. We studied the size and histology of lesions created with radiofrequency thermal ablation administered via the laparoscopic approach with and without hilar occlusion in a porcine model. MATERIALS AND METHODS The lower pole of each kidney was exposed laparoscopically in 11 farm pigs. In each kidney a 7-electrode dry radiofrequency thermal ablation probe was inserted at an identical location and deployed to a diameter of 2 cm. Energy was applied for 8 minutes at an average temperature of 100C. The left renal hilum of each pig was clamped during radiofrequency thermal ablation. Two pigs were sacrificed immediately, and 3 each were sacrificed at 24 hours, 2 and 4 weeks. The size and shape of the lesions created were measured and examined histologically. RESULTS There were no intraoperative or postoperative complications. Laparoscopic ultrasound confirmed probe placement but did not monitor lesion progression. Acutely lesions were firm and white with a small adjacent hemorrhagic zone. Histological evaluation revealed preserved renal architecture but the loss of distinct cytoplasmic features. Nicotinamide adenine dinucleotide staining demonstrated no viable cells within the lesions. In surviving animals pelvicaliceal integrity was preserved. In the 2 and 4-week survival groups kidneys treated with hilar occlusion had larger lesions than nonoccluded kidneys but the differences were not significant at 4 weeks (3.2 x 2.7 x 2.5 cm. and 3.5 x 1.7 x 2.0, respectively, p >0.05). Histologically untreated parenchyma of hilar occluded kidneys demonstrated changes consistent with chronic pyelonephritis. In 1 kidney radiofrequency thermal ablation with hilar occlusion resulted in complete lower pole loss at 4 weeks. CONCLUSIONS In the porcine model renal radiofrequency thermal ablation creates rapid and completely devitalized lesions of consistent size and shape. Hilar occlusion may result in slightly larger lesions but risks damage to the whole renal unit.

Tumor necrosis factor inhibitor ameliorates murine intestinal graft-versus-host disease☆☆☆

BACKGROUND & AIMS Transfer of T helper cells from DBA/2 mice to irradiated allogeneic B6D2F1 mice leads to development of colonic graft-versus-host disease with pathological features of inflammatory bowel disease. To examine the role of tumor necrosis factor (TNF) in graft-versus-host disease enteropathy, an adenoviral vector encoding a TNF inhibitor protein was administered. METHODS Irradiated B6D2F1 mice were infused with DBA/2 bone marrow and spleen cells. Mice then received either a control beta-galactosidase-encoding adenovirus or an adenovirus encoding a TNF inhibitor, composed of the extracellular domain of the human 55-kilodalton TNF receptor linked to the murine immunoglobulin G1 heavy chain. Mucosal permeability to sucralose and colonic histology were assessed 14 and 25 days after transplantation. RESULTS Less diarrhea was observed in DBA/2 --> B6D2F1 mice expressing the TNF inhibitor, and colonic sections from these mice had significantly less inflammation and epithelial cell abnormalities. In TNF inhibitor recipients, mucosal permeability to sucralose was similar to that in nonirradiated control mice and significantly less than in recipients of the control adenovirus. CONCLUSIONS TNF inhibition decreases the severity of enteropathy in the DBA/2 --> B6D2F1 murine model of colonic graft-versus-host disease.

Loss of Dpc4 Expression in Colonic Adenocarcinomas Correlates with the Presence of Metastatic Disease

DPC4 is a candidate tumor suppressor gene on chromosome 18q21, a region that shows high frequencies of allelic losses in pancreatic and colorectal adenocarcinomas. Biallelic inactivation of DPC4 has been reported in half of pancreatic cancers, but are relatively infrequent in other tumor types. The role of DPC4 inactivation in colorectal neoplasms has not been fully characterized. An immunohistochemical assay for Dpc4 protein expression has been recently developed and shown to be a sensitive and specific surrogate for alterations in the DPC4 gene. In this study we examined the expression of Dpc4 protein in formalin-fixed archival tissue from 83 colorectal lesions, including 19 adenomas and 64 sporadic adenocarcinomas (11 stage I, 13 stage II, 17 stage III, and 23 stage IV cancers). None of the adenomas or stage I adenocarcinomas showed loss of Dpc4 expression, whereas one of 13 (8%) stage II, one of 17 (6%) stage III, and five of 23 (22%) of stage IV cancers showed loss of Dpc4 expression. There was a borderline significant difference in loss of Dpc4 reactivity in colorectal tumors with distant metastasis at presentation (22%) versus primary tumors without distant metastasis (5%) (Fishers exact test, P = 0.05; chi(2) = 0.04). Poorly differentiated histology or status of pericolonic lymph nodes did not affect Dpc4 expression. Alterations in DPC4 are involved in the progression of a subset of colorectal carcinomas, especially those that present with advanced disease. In the sequential pathogenesis of colorectal tumors, inactivation of DPC4 is likely to be a late event.

Regional and Systemic Cytokine Responses to Acute Inflammation of the Vermiform Appendix

ObjectiveTo measure local (peritoneal fluid) and systemic (plasma) cytokine profiles in patients with infection-inflammation of the vermiform appendix, a relatively mild, localized inflammatory process. Summary Background DataThe systemic host response to invading microorganisms, often termed the systemic inflammatory response syndrome (SIRS), includes changes in heart rate, respiratory rate, body temperature, and circulating white blood cell numbers. Although these changes can be induced experimentally by administering proinflammatory cytokines, the mediators that appear in the bloodstream during early, localized infection in humans have not been defined. MethodsThe authors studied 56 patients with pathologically proven appendicitis. Blood was obtained before the induction of anesthesia, when 82% of the patients met the criteria for SIRS. Peritoneal fluid (PF) was obtained by intraoperative lavage. Cytokines were measured by immunoassay. To assess the net impact of the mediators within plasma, the authors studied the ability of patient plasma to augment or suppress bacterial lipopolysaccharide (LPS) stimulation of monocytes in vitro. ResultsOf the proinflammatory cytokines, tumor necrosis factor-alpha was present in PF but not in plasma, interleukin (IL)-1&bgr; and interferon-&ggr; were found in low concentrations in both PF and plasma, and IL-12 (p70) was detectable in plasma but not PF. In contrast, IL-6 and IL-1 receptor antagonist (IL-1ra) were the most abundant cytokines in the PF and plasma, and the concentrations of IL-4 and IL-10 were also elevated in both compartments. Patients with more severe appendicitis had higher plasma levels of IL-6 and IL-10 and lower plasma levels of IL-12 and interferon-&ggr; than did those with uncomplicated disease. Patient plasma inhibited LPS-induced stimulation of a monocyte cell line, and this inhibition was accentuated by complicated disease. ConclusionsAs judged from the pattern of soluble cytokines in plasma and the effect of the plasma on monocyte activation by LPS, mild, localized infection can induce a systemic response that is predominantly anti-inflammatory.

Accuracy and effectiveness of laparoscopic vs open hepatic radiofrequency ablation

BackgroundThe purpose of this study was to compare the accuracy (in terms of ultrasound-guided probe placement) and the effectiveness (in terms of pathologic tumor-free margin) of laparoscopic vs open radiofrequency (RF) ablation.MethodsUsing a previously validated tissue-mimic model, 1-cm simulated hepatic tumors were ablated in 10 pigs randomized to open or laparoscopic techniques. Energy was applied until tissue temperature reached 100°C (warm-up) and thereafter for 8 min. A pathologist blinded to technique examined all specimens immediately after treatment. Analysis was by Fisher’s exact test and the Mann-Whitney U test; p<0.05 was considered significant.ResultsOff-center distance (3.5±1.6 vs 4.2±1.4 mm), size (24.7±3.1 vs 25.6±3.8 mm), symmetry (40% vs 73%), margin positivity (33% vs 9%), and margin distance (1.1±1.2 vs 2.2±1.6 mm) were not significantly different between laparoscopic (n=15) and open (n=11) ablations, respectively. The proportion of round/ovoid lesions (20% vs 64%) was lower (p=0.043), and warm-up time (20.2±14.0 vs 10.7±7.5) was longer (p=0.049) for the laparoscopic than for the open groups, respectively.ConclusionAccurate probe placement can be achieved using laparoscopic and open RF ablation techniques. The physiologic effects of laparoscopy may alter ablation shape and warm-up time. Additional studies are needed to establish effective ways of achieving complete tumor destruction.

Ureteral replacement using porcine small intestine submucosa in a porcine model

OBJECTIVES To investigate an alternative technique using an onlay patch of porcine small intestine submucosa (SIS) allograft to bridge a ureteral defect. For ureteral strictures that fail endourologic management, few options are available for minimally invasive repair or reconstruction. Although laparoscopic interposition of a tubularized allograft of porcine SIS has great promise, animal studies have yielded mixed results. METHODS In 9 anesthetized female pigs, cystoscopy and retrograde pyelography were performed, and a ureteral stent was placed. Transperitoneal laparoscopic access was obtained, and a segment of ureter 2 cm long and encompassing one half the ureteral circumference was excised. An oval-shaped patch of SIS was sutured to the native ureter to cover the defect. In one control survival animal, the ureter was excised and a stent placed, but no SIS onlay was performed. Two pigs were killed immediately. In the survival group (6 pigs), the stents were removed at 1 week (n = 2), 2 weeks (n = 2), or 4 weeks (n = 2) and the corresponding animals were killed at 3 weeks (n = 2), 6 weeks (n = 2), and 9 weeks (n = 2). Intravenous urography was performed to evaluate renal function, and retrograde pyelography was performed after harvest to identify ureteral stricture or obstruction. The ureteral grafts were measured and examined histologically. RESULTS All 6 kidneys from the survival group were grossly normal, appeared promptly on intravenous urography, and were patent on retrograde pyelography. The control animal demonstrated complete ureteral obstruction. By 9 weeks, the SIS graft was replaced with ureteral tissue, including the muscle layers. The epithelium was primarily transitional epithelium, with focal intestinal metaplasia. The submucosa and ureteral musculature appeared histologically normal. CONCLUSIONS In the porcine model, a patch graft technique using SIS appears to induce ureteral regrowth. Renal function remained intact, and no evidence of stricture was demonstrated on radiographic imaging. Before clinical application of this technique, evaluation in a stricture model is required.

The effect of hepatic inflow occlusion on laparoscopic radiofrequency ablation using simulated tumors.

BackgroundThe purpose of this study was to determine the effect of hepatic inflow occlusion (the Pringle maneuver) on laparoscopic radiofrequency (RF) ablation.MethodsUsing a previously validated agarose tissuemimic model, 1-cm simulated hepatic tumors (three per animal) were laparoscopically ablated in five pigs with normal perfusion and then in five pigs with hepatic artery and portal vein occlusion. Energy was applied until tissue temperature reached 100°C (warm-up) and there-after for eight min. Specimens were examined immediately after treatment.ResultsVascular occlusion was successful in all cases per color-flow Doppler ultrasound. Pringle time was 11.4±1.6 min. Warm-up time (2.7±1.4 vs 20.2±14.0 min) was significantly faster in the Pringle group. Ablation diameter (34.8±2.9 vs 24.7±3.1 mm), proportion of round/ovoid lesions (93% vs 20%), ablation symmetry (100% vs 40%), and margin distance (5.1±3.0 vs 1.1±1.2 mm) were significantly better for the Pringle group than the No Pringle group, respectively.ConclusionUsing a Pringle maneuver during laparoscopic RF ablation significantly enhances ablation geometry and results in larger margins.

Laparoscopic partial nephrectomy with a diode laser: porcine results.

PURPOSE To develop a safe and effective technique for laparoscopic partial nephrectomy without need for hilar occlusion. MATERIALS AND METHODS Laparoscopic transperitoneal lower-pole partial nephrectomy was performed in five 45- to 50-kg female farm pigs using a 980-nm diode laser. Standard transperitoneal access was obtained, and a four-port approach was used to perform a laparoscopic right partial nephrectomy using a diode laser (23 W) without hilar occlusion. The pigs were allowed to recover and 2 weeks later underwent a left laparoscopic partial nephrectomy. Postoperatively, renal function was monitored by serial serum creatinine measurements. Both kidneys and ureters were removed for ex-vivo retrograde pyelograms and histologic analysis. RESULTS The 980-nm diode laser resulted in successful lower-pole partial nephrectomy without hilar occlusion in all 10 of the kidneys. In three cases, laser hemostasis was insufficient, and adjunctive hemostatic clips were necessary to stop bleeding. The mean operative time was 126 minutes, and the mean laser time was 84 minutes. An average of 23% (range 13%-33%) of the kidney parenchyma was resected. The mean blood loss was 150 mL (range 50-300 mL). There was no evidence of urinary extravasation on ex-vivo retrograde pyelograms at 2 weeks in any of the kidneys. CONCLUSION Laparoscopic partial nephrectomy without hilar occlusion using the 980-nm diode laser is feasible in the porcine model. Because adjunctive hemostatic measures may be necessary in some cases, clinical trials in humans should be limited to small exophytic tumors.

The role of fine-needle aspiration biopsy in the primary diagnosis of mesenchymal lesions a community hospital-based experience

The objective of this study was to determine the utility of fine‐needle aspiration biopsy (FNAB) in the primary diagnosis of mesenchymal lesions. A total of 162 cases with a diagnosis of benign or malignant mesenchymal lesion (excluding lipoma) on FNAB were retrieved from the cytopathology archives for the years 1990–1997.

Development of an in vivo tumor-mimic model for learning radiofrequency ablation

Radiofrequency ablation requires accurate probe placement using ultrasound guidance. The purpose of this study was to develop an in vivo tumor-mimic model for learning open and laparoscopic radiofrequency ablation. Tumor-mimics were created in ex vivo porcine livers by injecting a mixture of 3% agarose, 3% cellulose, 7% glycerol, and 0.05% methylene blue, which formed 1 cm hyperechoic, discrete lesions on ultrasound. Open and laparoscopic (using a box-trainer) ablation techniques were practiced. In vivo experiments were then conducted in 10 pigs. Three tumor-mimics were created in each animal using a laparoscopic approach. Lesions were characterized sonographically, ablated using an open (n = 5) or laparoscopic (n = 5) approach, and examined pathologically. An ablation in normal liver tissue was performed as a control. Tissue impedance was recorded. Target creation took 81 minutes per animal and 96% of injections were successful. Tissue impedance (48.8 ±5.8 vs. 49.6 ±5.4) and ablation size (25.1 ±3.4 vs. 24.3 ±5.1) were not significantly different for controls (n = 8) and tumor-mimics (n = 26), respectively. One animal died of a pulmonary embolism following injection of agarose into a hepatic vein. The agarose-based tissue-mimic creates realistic sonographic targets for learning ultrasound-guided open and laparoscopic radiofrequency ablation in an in vivo model.