[A case of small intestinal stage IV gastrointestinal stromal tumor in which long-term disease control was maintained for more than 10 Years through a multidisciplinary team approach].

The prognosis of metastatic or recurrent gastrointestinal stromal tumors (GISTs) accompanied by multiple hepatic metastases and peritoneal dissemination is very poor. We encountered a case of stage IV small intestinal GIST with multiple hepatic metastases and peritoneal dissemination that were observed after resection of the primary lesion. Multidisciplinary treatments were performed over time, including hepatic resection, radiotherapy, imatinib therapy, sunitinib therapy, and transcatheter arterial chemoembolization, and the disease had been brought under control following resection of a primary lesion 14 years ago. The patient was a 49-year-old woman diagnosed with hemorrhagic stool in July 1998, when a computed tomography scan revealed an 8-cm-diameter tumor in her small bowel. Partial resection of her small bowel was performed and the pathological diagnosis was a high-risk GIST showing 15 mitoses per 50 high power fields. Several metastases developed in the S4 and S5 segments of the patient's liver 3 years after resection of the primary lesion, and a central two-segmental resection of the liver was performed. Furthermore, 1 year after this procedure, peritoneal dissemination developed near the pancreas, for which radiotherapy was performed. Four months later, the patient again developed multiple liver metastases and was started on treatment with 400 mg imatinib per day, achieving a partial response(PR). Five years and 6 months after imatinib initiation, resistance emerged in one of the liver metastases. The patient was switched to sunitinib(50 mg per day), but was diagnosed with progressive disease at the end of the second course and the procedure was discontinued. Treatment with 400 mg of imatinib per day was resumed, and transcatheter arterial chemoembolization was performed twice over a 17-month period for the resistant hepatic region and a PR was achieved each time. We were able to maintain a PR in this patient; other metastases indicated the effectiveness of imatinib therapy. Therefore, a multidisciplinary team approach can be effective in achieving long-term disease control in patients with metastatic or recurrent GIST.

Hemolysis resulting from surface roughness under shear flow conditions using a rotational shear stressor.

The degree of hemolysis as a function of surface roughness value and roughened area under shear flow conditions was investigated using a rotational shear stressor. The shearing portion of the stressor is cone shaped in its upper and lower positions, with a cylindrical central section. Surface roughness was applied to the cylindrical section. Bovine blood was sheared for 30 min over a set of roughened surfaces of between arithmetic mean roughness (Ra) 0.1 and 0.8 mm covering 10% of the surface area of the cylindrical section (equivalent to 1.8% of the whole blood contact area) at a shear rate of 3750/s. The threshold value thus obtained for rapid increase in hemolysis was between Ra 0.6 and 0.8 mm. When sheared with a roughened surface of Ra 0.8 mm applied to the cylindrical surface at areas between 0 and 100% (equivalent to between 0 and 18% of the whole blood-contacting area), the hemolysis level did not increase from 10 to 100%, but a significant difference was obtained between 0 and 10%. This suggests that red blood cells were destroyed not by fatigue failure caused by rolling on the roughened surface, but due to the high shear stress generated by surface roughness. Moreover, it appears that the shear stress was generated over the entire cylindrical section, regardless of the area of surface roughness.

Hemolysis caused by surface roughness under shear flow.

In this study, the relationship between the degree of roughness of blood contact surfaces under laminar shear flow conditions and the level of hemolysis resulting from this roughness was investigated using a rotational shear stressor. Unlike previous in vitro experiments that used a pumped circuit, the level of hemolysis was directly evaluated under a constant shear flow. In total, 1.8% of the blood contact area was roughened to an arithmetic mean roughness (Ra) value of between 0.4 and 9.2 microm by machine processing and a shear load was applied for 30 min at a shear flow rate of 3750 s(-1). As a result, the threshold Ra value for the induction of hemolysis was found to be between 0.4 and 0.8 microm. In addition, the results of this experiment suggested that the high shear stress resulting from surface roughness plays a major role in determining the level of hemolysis caused by surface roughness.