Exploring new technologies to facilitate laparoscopic surgery: creating intestinal anastomoses without sutures or staples, using a radio-frequency-energy-driven bipolar fusion device.

INTRODUCTION: Intestinal anastomotic healing requires apposition of the collagen containing submucosal layers of the opposing intestinal walls, which is traditionally achieved by staples or sutures. Recently, a feedback-controlled bipolar sealing system (LigaSure) has been successfully introduced to seal and transect vessels. Since this technology depends on fusion of collagen fibres which are abundantly present in the intestinal wall, the possibility to create intestinal anastomoses using this technology was investigated in the present study. MATERIALS AND METHODS: For this purpose a new-generation radiofrequency (RF) generator and a prototype of the Ligasure Anastomotic Device (LAD) have been developed. The generator incorporates a closed loop control system which monitors tissue fusion, compares it with a mathematical model of ideal fusion based on the density and compliance of intestinal tissue and adjusts energy output accordingly. In total 8 anastomoses were created in a porcine model (4 pigs, 2 anastomoses each) and healing was assessed by macroscopic and histological examination. RESULTS: All seals were macroscopic intact both immediate after creation and at sacrifice at the 7th postoperative day. Between operations, pigs appeared healthy and had normal intestinal passage. Histological examination of the anastomoses revealed undisturbed healing with granulation tissue, newly synthesised collagen in the submucosa and re-epithelialization at the borders of the seals. CONCLUSION: These results confirm the feasibility to create experimental intestinal anastomoses using LigaSure technology. This may be an important step towards the development of new laparoscopic equipment combining dissecting and reconstructive properties within one single instrument.

Assessment of the role of neutrophils on the antitumor effect of TNFalpha in an in vivo isolated limb perfusion model in sarcoma-bearing brown Norway rats.

INTRODUCTION: Isolated limb perfusion (ILP) with TNFalpha in combination with melphalan and IFNgamma has resulted in an immediate and dramatic tumor response in patients. Such an effect was also noted following ILP in a rat sarcoma model. This model enables us to investigate several factors responsible for the TNFalpha-induced tumor responses. We applied total body irradiation (TBI) to reduce white blood cell count, to investigate the contribution of leukocytes to the anti-tumor effect of TNFalpha. METHODS: Small fragments of the nonimmunogenic BN 175 sarcoma were implanted sc in the lower hind leg. A 5 Gy TBI was performed before ILP at a tumor diameter of approximately 15 mm. The hind limbs of 63 rats were perfused and were divided into 6 groups: group 1, sham perfusion, n = 9; group 2, TBI + sham perfusion, n = 6; group 3, TNFalpha 50 microgram, n = 9; group 4, melphalan 40 microgram, n = 9; group 5, TNFalpha 50 microgram + melphalan 40 microgram, n = 22; group 6, TBI + TNFalpha + melphalan ILP, n = 8. In addition, 10 rats were perfused for histological analysis at 24 h post-ILP. RESULTS: We observed in Group 1: 9/9 progressive disease (PD); Group 2: 6/6 PD; Group 3: 9/9 PD; Group 4: 9/9 no change (NC) of tumor diameter for at least 4 days; Group 5: 6/22 NC, 16/22 complete remission (CR), 12/16 of which showed skin necrosis at the tumor site; and Group 6: 7/8 NC and 1/8 CR (without skin necrosis). After TBI, WBC reduction of 80-95% was observed, while the number of platelets was not significantly reduced and platelet aggregation was maintained at 72 %. Histological analysis revealed decreased hemorrhagic necrosis associated with the absence of PMN infiltration at the tumor margins in the TBI rats. CONCLUSION: TBI and the associated reduction in WBC count decreased the tumor response by TNFalpha and melphalan significantly and abrogated the immediate response of skin necrosis at the tumor site, as found in rats treated with TNFalpha and melphalan without TBI. These data strongly suggest that leukocytes play an important role in the hemorrhagic effects of TNFalpha.

Synergistic effects of TNF-alpha and melphalan in an isolated limb perfusion model of rat sarcoma: a histopathological, immunohistochemical and electron microscopical study.

Isolated limb perfusion (ILP) with tumour necrosis factor alpha (TNF-alpha) and melphalan has shown impressive results in patients with irresectable soft tissue sarcomas and stage III melanoma of the extremities. The mechanisms of the reported in vivo synergistic anti-tumour effects of TNF-alpha and melphalan are not precisely understood. We have developed an ILP model in the rat using a non-immunogenic sarcoma in which similar in vivo synergy is observed. The aim of this present study was to analyse the morphological substrate for this synergistic response of TNF-alpha in combination with melphalan to shed more light on the pathomechanisms involved. Histology of the tumours from saline- (n = 14) and melphalan-treated (n = 11) rats revealed apparently vital tumour cells in over 80% of the cross-sections. Interstitial oedema and coagulation necrosis were observed in the remaining part of the tumour. Haemorrhage was virtually absent. TNF-alpha (n = 22) induced marked oedema, hyperaemia, vascular congestion, extravasation of erythrocytes and haemorrhagic necrosis (20-60% of the cross-sections). Oedema and haemorrhage suggested drastic alterations of permeability and integrity of the microvasculature. Using light and electron-microscopy, we observed that haemorrhage preceded generalised platelet aggregation. Therefore, we suggest that the observed platelet aggregation was the result of the microvascular damage rather than its initiator. Remarkably, these events hardly influenced tumour growth. However, perfusion with the combination of TNF-alpha and melphalan (n = 24) showed more extensive haemorrhagic necrosis (80-90% of the cross-sections) and revealed a prolonged remission (mean 11 days) in comparison with the other groups of rats. Electron microscopical analysis revealed similar findings as described after TNF-alpha alone, although the effects were more prominent at all time points after perfusion. In conclusion, our findings suggest that the enhanced anti-tumour effect after the combination of TNF-alpha with melphalan results from potentiation of the TNF-alpha-induced vascular changes accompanied by increased vascular permeability and platelet aggregation. This may result in additive cytotoxicity or inhibition of growth of residual tumour cells.

Isolated limb perfusion with TNF alpha and melphalan in a rat osteosarcoma model: a new anti-tumour approach.

Isolated limb perfusion (ILP) with TNF alpha, IFN gamma and melphalan causes impressive tumour reduction in patients with irresectable soft tissue sarcomas with a high limb salvage rate. Since this therapy could be of value in patients with progressive osteosarcoma, we performed a study in an osteosarcoma tumour model in the rat. The ROS-1 osteosarcoma was implanted s.c. in the hind leg of WAG rats. Rats were divided in four groups: rats that underwent ILP with perfusate alone, TNF alpha alone, melphalan alone or their combination. Almost all rats, treated with a sham ILP or a perfusion with 40 micrograms melphalan, showed progressive disease (PD) (6/6 and 5/6). After perfusion with 50 micrograms TNF alpha alone a varied response was observed: 2/6 PD, 2/6 no change (NC) and 2/6 a complete remission (CR). After combined perfusion: 3/6 rats had a partial remission and 3/6 a CR. The best and most consistent responses are obtained by combining TNF alpha and melphalan. The discrepancy with the in vitro sensitivity of ROS-1 indicates that indirect effects are important in this tumour model.

Synergistic antitumour effect of recombinant human tumour necrosis factor alpha with melphalan in isolated limb perfusion in the rat.

The efficacy of isolated limb perfusion (ILP) for 'intransit' metastases from malignant melanoma and irresectable soft tissue sarcoma has been improved considerably by the addition of tumour necrosis factor (TNF) alpha. A rat sarcoma tumour model was, therefore, developed to evaluate the effects of TNF-alpha, melphalan and the combination of these drugs in the treatment of sarcoma. In BN rats bearing the non-immunogenic BN 175 sarcoma ILPs were performed with perfusate only, TNF-alpha, melphalan alone, or in combination when tumours had grown to approximately 1.5 cm in diameter. All rats treated with sham perfusion or perfusion with 50 micrograms TNF-alpha showed progressive disease. After perfusion with 40 micrograms melphalan no change in tumour diameter was observed in any rats at 4 days. After a combined perfusion with 40 micrograms melphalan and 50 micrograms TNF-alpha complete remission was noted in 12 of 16 rats. This synergistic effect in vivo between relatively ineffective doses of TNF-alpha and melphalan was not observed in vitro.