Improved hepatic microcirculation by human soluble urinary thrombomodulin in the xeno-perfused porcine liver.

PURPOSE: Both the protein C/thrombomodulin system and the heparin/anti-thrombin III system are major physiological anticoagulant systems, which may also play a major role in preserving the hepatic microcirculation in xenogeneic liver transplantation. To compensate for the functional incompatibilities of the porcine thrombomodulin (TM)-cofactor activity beyond species for human thrombin, soluble human TM protein was tested in xenogeneic perfusion of the porcine liver. MATERIALS AND METHODS: The livers were harvested from adult female pigs and perfused through the portal vein (PV) and hepatic artery (HA) for 2 hr, with fresh human blood in group 1 (n=5), fresh porcine blood (10 units/ml) in group 2 (n=5), and fresh human blood with TM (50,000 units/1.5 l) in group 3 (n=5). The tissue PO2 level, tissue blood flow, PV and HA pressures were all continuously monitored. Circulating perfusate and liver tissue samples were periodically obtained for blood chemistry and histologic analyses. RESULTS: The activated protein C (aPC) level was significantly elevated in the TM-treated group 3 (47.5%+/-3.5% at preperfusion and 51%+/-2.8% after 120 min of perfusion) in comparison to group 1 (32.3%+/-7.2% and 35.3+/-12.0%). The hepatocyte enzyme release of aspartate aminotransferase (AST) was suppressed significantly more in group 3 (238.2+/-107 IU/l), than in group 1 (672.3+/-160 IU/l) at 2 hr after reperfusion. In group 3, the tissue PO2 levels and tissue blood flow also remained significantly higher throughout the perfusion. The platelet counts in the perfusate remained significantly higher in group 3 (37.1% to 74.3% of the preperfusion level) than in group 1 (4.4% to 14.7%), after 0 to 80 min of perfusion. According to the histologic findings, the degree of interlobular hemorrhaging and congestion decreased remarkably more in group 3 than in group 1. CONCLUSION: These findings thus indicated that soluble thrombomodulin protein extracted from human urine remarkably improved hepatic microcirculation in the xenoperfused porcine liver. The thrombomodulin/protein C system might, thus, play an important role in restoring the physiological anticoagulant system in the xenoperfused porcine liver.

Limitations of exogenous L-arginine in exerting a cytoprotective effect on hepatic ischemia/reperfusion injury.

To test whether or not the L-arginine/nitric oxide (NO) pathway induces a protective effect, we investigated the effect of exogenous L-arginine on hepatic ischemia/reperfusion (I/R) injury, using ex vivo perfusion of the isolated rat liver. The rat liver was removed and preserved in cold saline for 60 min, followed by 120 min of reperfusion with oxygenated perfusate at 37 degrees C. Either 600 mg/kg of L-arginine (groups 1 and 4), D-arginine (group 2), N(G)-nitro-L-arginine methyl ester (L-NAME) (group 3), or saline (group 5) were administered through the portal vein starting from 5 min before reperfusion to 5 min after reperfusion. In group 4, 600 mg/kg of L-NAME was preadministered at 10 min prior to the administration of L-arginine. The intrahepatic nitric oxide (NO) levels showed only a temporal elevation (227% +/- 70% of the pre-reperfusion levels at 5 min) after reperfusion in group 1. Pretreatment with L-NAME suppressed the elevation of the NO levels immediately after reperfusion in group 4. The lactate dehydrogenase release to the effluent perfusate significantly decreased and the histological findings showed that the sinusoidal damage observed after reperfusion was mitigated in group 1 more than in the other groups. These results thus suggest that exogenous L-arginine produced a relatively small amount of NO and therefore resulted in a slight decrease of hepatic I/R injury.

Radiation-associated rectal cancer: report of four cases.

BACKGROUND/AIMS: Radiation-associated rectal cancer is a remarkable clinical entity. We demonstrate 4 patients (mean age 68 years, range 63-74) who had undergone pelvic radiotherapy for cervical cancer. We indicate some characteristics of radiation-associated rectal cancer. RESULTS: Two patients had received intracavitary and external pelvic radiotherapy, while the remaining 2 had external pelvic radiotherapy following hysterectomy. The mean total radiation dose was 63 Gy, though radiation dose information was not available for 1 patient. Colorectal cancer developed at a mean time of 20.7 years (range 11-30) after radiation therapy. All patients presented with chronic radiation colitis, and 3 demonstrated abnormal tumor markers. Colonoscopy revealed an ulcerative, localized well-differentiated adenocarcinoma of the rectosigmoid colon in 1 patient, and diffusely infiltrating cancers of the lower rectum, one signet-ring cell carcinoma and two mucinous carcinomas in the remaining 3. One case was stage I, 2 were stage IIIa, and the remaining case was stage IV. Three patients underwent abdominoperineal resection. The remaining patient was felt to be inoperable. The colorectal wall demonstrated the changes of chronic radiation injury. Two patients died within a short time because of their advanced cancers. CONCLUSION: Radiation-associated rectal cancer has a tendency to be diagnosed in the advanced stage and to have a poor prognosis. A literature review and our case report suggest that since there are no reliable clinical or laboratory indicators of the presence of a curable colorectal cancer in the setting of chronic radiation proctocolitis, surveillance with a colonoscope should be done 10 years after irradiation in patients with previous pelvic radiotherapy.

Stable gene expression with VSV-G pseudotyped-retrovirus vector in the rat liver.

BACKGROUND: Pseudotyped-retrovirus-mediated gene transfer to the regenerating rat liver was investigated in vivo and the findings were compared with those for retrovirus-mediated gene transfer. MATERIALS AND METHODS: Four weeks prior to gene transfer, the spleen was transpositioned to the left subcutaneous position to develop a port-splenic shunt. Twenty-four hours after a partial hepatectomy (68%) was performed, the liver was perfused in situ and kept in contact with either a pseudotyped-retrovirus vector encoding LacZ (7 x 10(7) cfu/ml, Group 1) or a retrovirus vector encoding LacZ (1 x 10(4) cfu/ml, Group 2) for 30 min. The animals were sacrificed at various points after gene transfer, and X-gal staining, reversed polymerase chain reaction (RT-PCR), and ONPG assay were performed to detect the transferred LacZ cDNA. RESULTS: In X-gal staining, the transferred LacZ cDNA started to show a strong beta-galactosidase activity in 30 to 50% of the hepatocytes at 3 days after gene transfer. Positive staining continued to be recognized until 28 days with a slight decrease in its intensity thereafter. On the other hand, Group 2 animals showed weak staining, which was observed in about 10 to 15% of the hepatocytes from 3 days after gene transfer and then decreased thereafter. In RT-PCR, positive mRNA of LacZ was detected constitutively until 28 days after gene transfer in Group 1, whereas two-thirds of the samples showed a negative band in Groups 2 at 3 days after gene transfer. CONCLUSION: In conclusion, the pseudotyped-retrovirus vector was useful in establishing a stable and strong expression of the in vivo gene transfer, while targeting the regenerating liver.