Hirofumi Tagami

Activated protein C reduces the ischemia/reperfusion-induced spinal cord injury in rats by inhibiting neutrophil activation

ObjectiveTo examine whether activated protein C (APC) reduces spinal cord injury in rats by inhibiting neutrophil activation after the transient ischemia. Summary Background DataIschemic spinal cord injury is an important pathologic mechanism leading to the paraplegia observed after surgery to repair aortic aneurysms. Activated neutrophils play a pivotal role in the development of ischemia/reperfusion-induced tissue injury. Recently, the authors have reported that APC, a physiologic anticoagulant, prevents lipopolysaccharide-induced pulmonary vascular injury by inhibiting neutrophil activation. These observations strongly suggest that APC reduces ischemia/reperfusion-induced spinal cord injury by inhibiting neutrophil activation. MethodsIn rats, spinal cord ischemia was induced by using a balloon catheter placed into the aorta. After the transient ischemia, survival and motor function were evaluated, and histologic examination of the spinal cord was performed by using both hematoxylin-and-eosin staining and 2,3,5,-triphenyltetrazolium chloride (TTC) staining 24 hours after the ischemia. Tissue levels of myeloperoxidase and cytokines, including tumor necrosis factor-&agr; (TNF-&agr;) and rat interleukin-8, were measured in six experimental groups: sham-operated, control, APC (100 &mgr;g/kg, intravenous), dansyl glutamyl-glycyl-arginyl chloromethyl ketone-treated activated factor X (DEGR-F.Xa), a selective inhibitor of thrombin generation (1 mg/kg, intravenous), nitrogen mustard-induced leukocytopenia, and diisopropyl fluorophosphate-treated APC (DIP-APC), active site-blocked APC (100 &mgr;g/kg, intravenous). APC, DEGR-F.Xa, and DIP-APC were administered intravenously 30 minutes before aortic occlusion. Control and leukocytopenic rats received saline instead of other drugs. ResultsPretreatment with APC significantly reduced motor disturbances compared with those in control animals. In contrast, neither DEGR-F.Xa nor DIP-APC had any effect. Microinfarctions, evidenced by the absence of TTC staining and histologic change, were markedly reduced in animals given APC. The increases in the tissue levels of TNF-&agr;, rat interleukin-8, and myeloperoxidase in the ischemic part of the spinal cord were significantly reduced in animals that received APC. These levels were not reduced in rats given DEGR-F.Xa or DIP-APC. Leukocytopenia produced effects similar to those of APC. ConclusionsAPC reduced the ischemia/reperfusion-induced spinal cord injury by inhibiting neutrophil activation. The therapeutic mechanisms of APC might depend on its inhibitory effect on the production of TNF-&agr;, which is a potent activator of neutrophils. Although the anticoagulant effects of APC might not be related to its ability to inhibit TNF-&agr; production, its serine protease activity appears to be essential in the therapeutic mechanism. APC appears to have potential as a therapeutic agent for prevention of spinal cord injury in patients undergoing aortic aneurysm repair.

Antigenicity of cryopreserved arterial allografts: Comparison with fresh and glutaraldehyde treated grafts

The use of cryopreserved aortic allografts in cardiovascular surgery is widespread and has resulted in excellent outcomes. However, it is controversial whether cryopreservation suppresses the antigenicity of tissue. We designed experimental models to study whether the cryopreservation process alters antigenicity in comparison with that found in fresh and glutaraldehyde treated tissues. Fresh, cryopreserved, and glutaraldehyde treated thoracic aorta from Brown Norway rats were subcutaneously implanted into Lewis rats. Inflammatory cells infiltrating around the grafts were measured on days 7, 14, 28, and 56 after implantation. The glutaraldehyde treated grafts showed significantly less infiltration than the fresh or cryopreserved grafts (p < 0.005). No significant difference was detected between the fresh and cryopreserved grafts. Another study examined the effect of modifications of the aortic allograft on subsequent allogeneic skin graft antigenicity. Subcutaneous implantation of fresh, cryopreserved, and glutaraldehyde treated aortic grafts from Brown Norway into Lewis rats resulted in subsequent skin graft rejection at 4.4 ± 0.7, 5.1 ± 0.8, and 6.6 ± 2.1 days, respectively. There was no significant difference between the fresh and cryopreserved groups; whereas skin grafts in the glutaraldehyde group survived longer than those in the cryopreserved group. These results indicate that cryopreservation had no significant influence on antigenic suppression of arterial allografts.

Altered plasma antigen levels of tissue factor pathway inhibitor during open-heart surgery

r = 0.96, P < 0.0001) which increased significantly after heparin injection (P < 0.0001), and increased further during the bypass period (P < 0.005). The increased free TFPI antigen level during CPB correlated with the duration of bypass (r = 0.65, P = 0.02). When heparin was neutralized by protamine, the free TFPI antigen level decreased immediately, but remained higher than the preoperative level (P < 0.005). These results suggest that plasma TFPI antigen levels increase during CPB.

Small solid pseudopapillary tumor of the pancreas in a 32-year-old man: Report of a case

A solid pseudopapillary tumor (SPT) of the pancreas is a rare neoplasm that mainly occurs in young women. We herein report the case of a small SPT arising from the head of the pancreas in an asymptomatic 32-year-old man, plus a literature review of this tumor. A 32-year-old man was admitted to our department at Kumamoto University Hospital for the evaluation of a pancreatic mass. The tumor had central necrosis, which was poorly perfused on contrast-enhanced computed tomography (CT) and which had a high intensity on T2-weighted magnetic resonance imaging (MRI). Histology revealed the lesion to be a solid pseudopapillary tumor of the pancreas, with the characteristic pseudopapilla formation and central degeneration. However, no capsule formation was observed. The tumor was positive for CD56, CD10, α1-antitrypsin, α1-antichymotrypsin, β-catenin, and progesterone receptor. However, the tumor was negative for pancreatic hormones, chromogranin-A, carcinoembryonic antigen, and carbohydrate antigen 19–9. We diagnosed the patient to have an SPT based on these histological findings. Small-sized solid pseudopapillary tumors of the pancreas are being increasingly recognized because of the recent advances in CT and MRI. We should also consider SPT even if it occurs in a male when the tumor contains necrosis-suspected areas which are poorly perfused on contrast-enhanced CT with a high intensity on T2-weighted MRI.