Mikio Yasumura

Experimental model to estimate intestinal viability using charge-coupled device microscopy

Intraoperative assessment of intestinal viability following release of strangulation remains difficult. The aim of this study was to establish clinical standards for the evaluation of intestinal viability by charge‐coupled device (CCD) microscopy.

Experimental Studies to Estimate the Intestinal Viability in a Rat Strangulated Ileus Model Using a Dielectric Parameter

This study aimed at establishment of adequate evaluation of intestinal viability before release of the strangulated intestine by measuring electrical properties. In rats a 20-cm segment of the distal ileum and mesentery was strangulated. The intestine was strangulated for 0, 2, 15, 45, 90, and 120 min. The conductance and capacitance obtained by impedance analyzer were used to calculate tanδm in the strangulated intestine. ATP was measured as well. In another experiment, after various periods of strangulation, tanδm was measured just before release of the strangulation. Rats were divided into Group A (survived for 7 days) and Group D (died within 7 days). There was a positive correlation between tanδm and ATP levels (P < 0.01). And tanδm was significantly greater in Group A than in Group D (P < 0.05). There were no deaths at a tanδm value of 2.36 or more and no survivors at a tanδm of less than 2.20 except for one rat. These results suggested that tanδm may be a useful index of the viability of the strangulated intestine before reperfusion.

Dielectric spectrogram for evaluating ischemic microstructural changes of the liver in simple cold preservation.

Abstract.Purpose: Monitoring ischemic liver injury is important in liver transplantation. We previously reported that dielectric properties were correlated with tissue adenosine triphosphate during liver preservation; however, it is unknown what the changes in dielectric properties are based on. Using rats, we studied the relationship between dielectric parameters and microstructural changes in liver tissues during preservation. Methods: We serially measured the percent decrease in conductivity and the percent increase in relative permittivity in rat livers, and determined the areas of cellular and extracellular components using a charge-coupled device microscope and an NIH image. Thereafter, we evaluated the relationship between dielectric parameters and microstructural changes in the liver tissues. Results: A positive linear and exponential correlation was found between the percent decrease in conductivity and the percent decrease in extracellular components (P < 0.01). A positive linear and exponential correlation was also found between the percent increase in relative permittivity and the percent increase in cellular components (P < 0.01). Conclusions: Our results suggest that the serial changes in tissue conductivity and the relative permittivity reflect changes in liver tissue microstructures during cold preservation.

Simultaneous operations for abdominal aortic aneurysm and liver cancer complicated by severe ischemic heart disease: report of a case.

We performed successful simultaneous operations for an abdominal aortic aneurysm (AAA) and liver cancer in a patient complicated by severe ischemic heart disease. A 59-year-old man with a history of liver dysfunction presented with acute epigastric pain. Abdominal computed tomography findings of ascites and a liver tumor indicated a diagnosis of ruptured hepatocellular carcinoma. He had a concomitant 65-mm AAA and a 48-mm right common iliac aneurysm. Elective surgery was scheduled because of his good general condition. Although triple-vessel disease was detected preoperatively, there were no graftable coronary arteries. The aneurysms were repaired first to utilize intra-aortic balloon pumping (IABP) during resection of the liver cancer, followed by left lateral segmentectomy. Perioperative hemodynamics were maintained by administering catecholamines and vasodilators, without the need for IABP. The patient was discharged on the 21st postoperative day without any complications, and no recurrence of liver cancer has been found in the 5 months since his operation.

Protective effects of 5,6,7,8-tetrahydroneopterin against X-ray radiation injury in mice.

The protective effects of 5,6,7,8-tetrahydroneopterin (NH4) against radiation injury in mice were studied. (C57BL/6xA/J)F1 (B6A) mice received a single whole-body irradiation dose of 200, 400, 700 or 800 cGy of X-rays. NH4 (30 mg/kg body weight) or phosphate-buffered saline (PBS) was injected intraperitoneally into irradiated mice 10 min before and after the irradiation and again after 6 h. All mice which received the 800 cGy radiation+PBS died between 8 and 11 days after the treatment. In contrast, those which also received NH4 demonstrated a significantly prolonged survival time and 40% lived more than 5 months. Total numbers of thymocytes and spleen cells on day 5 post-irradiation were dramatically reduced in line with the radiation dose. The survival was significantly enhanced by NH4 in treated mice. The proliferation of spleen cells in mice stimulated by concanavalin A (Con A) or lipopolysaccharide (LPS) was also greater in NH4 treated mice. The immune response of survivors 5 months after 800 cGy+NH4 treatments, against Con A, LPS, allogenic mouse, and sheep red blood cells had essentially recovered to the levels of normal mice. These results indicate that NH4 had an important role in modifying radiation injury.

5,6,7,8-tetrahydroneopterin (NH4) Acts like an Endogenous Superoxide Dismutase

Summary The protective effect of 5,6,7,8-tetrahydroneopterin (NH.) against radiation injury in mice was studied. (C57BL/6x A/J)F1 mice received whole body irradiation with a single fatal dose of 8.0 Gy X-ray. NH4 was injected intraperitoneally into irradiated mice at various protocols. NH. was significantly effective to prolong the survival of the irradiated mice. The most effective protocol of NH4 administration was 3 times injections (10 minutes before and after irradiation and additional one 12 hours after that.) with a dose of 30 mg/kg body weight for each. Some mice that received such treatment survived more than 30 days after irradiation. In conclusion, these results indicate that NH4 has an inhibitory potential on radiation injury as an endogenous superoxide dismutase like substance.