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 tan(delta)m in the strangulated intestine. ATP was measured as well. In another experiment, after various periods of strangulation, tan(delta)m 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 tan(delta)m and ATP levels (P < 0.01). And tan(delta)m was significantly greater in Group A than in Group D (P < 0.05). There were no deaths at a tan(delta)m value of 2.36 or more and no survivors at a tan(delta)m of less than 2.20 except for one rat. These results suggested that tan(delta)m may be a useful index of the viability of the strangulated intestine before reperfusion.
Our results suggest that the serial changes in tissue conductivity and the relative permittivity reflect changes in liver tissue microstructures during cold preservation.
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.
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