PURPOSE: To clarify the function of ascorbate free radical (AFR) reductase in the antioxidation system of different vertebrate lenses. METHODS: The soluble and insoluble fractions were prepared from bullfrog, guinea pig, rat, rabbit, swine, and bovine lenses, and membrane-bound enzymes in the insoluble fraction were extracted by 0.3% Triton X-100. Ascorbate free radical reductase and diaphorase activities in each fraction were determined. RESULTS: Ascorbate free radical reductase activity in the lens soluble fraction was the highest in the bullfrog. That in the guinea pig and rabbit was at the next level. There was only a little activity in rat and swine lenses, and none was detected in the bovine lenses. However, a large species difference in AFR reductase activity was not observed in the 0.3% Triton X-100 extracts. Diaphorase activity was three to nine higher than AFR reductase activity in the soluble fractions of bullfrog, guinea pig, and rabbit. In the 0.3% Triton X-100 extracts of all animal species used, it was very high, 108 to 311 times the AFR reductase activity. CONCLUSION: These results indicate that the lens soluble and membrane-bound AFR reductase in the different animals may be individual enzyme molecules and have different antioxidative functions. Because the lenses of bullfrog, guinea pig, and rabbit are known to contain a near-ultraviolet (UV) light-absorbing compound, reduced pyridine nucleotide, at a high concentration, the soluble AFR reductase activity is expected to be high in the vertebrate lenses with a near-UV light filter, to enhance the antiphoto-oxidation capacity of ascorbate.

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Mouse CD4 and CD8 T-cell clones that recognize xeno-antigens directly on xeno-antigen presenting cells in xeno MHC-restricted ways.

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Dielectric spectrogram for instantaneous evaluation of ischemic injury of the liver.

Electrical properties of tissues sensitively reflect structural and physiologic changes. The authors examined the use of a dielectric spectrogram for instantaneous evaluation of ischemic injury of the liver. Wistar rats, which had enough collateral circulation for portal bypass with subcutaneous transposition of the spleen, were used. Four ischemic periods (15, 30, 60, and 120 min) were examined and followed by reflow. Permittivity and conductivity were measured at 39 frequency points in the 20 Hz-1 MHz range using an LCR meter system. They were then expressed in a loss tangent (LT) plot to clear their behavior. The maximum LT value (max-LT) and the minimum LT value (min-LT) of the normal liver were 3.98 +/- 0.28 and 2.98 +/- 0.22, and appeared in 15-20 kHz and 150-300 kHz, respectively. During the first 30 min after ischemia, max-LT decreased to 3.25 +/- 0.14 (p < 0.005) and its range shifted to 0.3-0.6 kHz, and min-LT decreased to 1.35 +/- 0.06 (p < 0.001) without shifting of range. Max-LT then decreased gradually and min-LT began to increase. After reflow, max-LT increased and higher max-LT was observed in the longer ischemic cases. Max-LT at 1 hr after reflow correlated negatively with recovery rate of bile flow at that time (y = -0.238x + 1.84, r2 = 0.82). Additionally, the difference between max-LT and min-LT at just before reflow (dif-LT) showed a significant correlation coefficient with recovery rate of bile flow at 1 hr after reflow (y = 2.22x -3.32, r2 = 0.92).

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Distinctive microcirculation of the brain during cerebral perfusion by observation with a CCD microscope.

Establishment of safer cerebral protection remains an important issue in reducing cerebral complications during aortic arch repair. Various cerebral perfusion techniques have been used. Recently, the usefulness of retrograde cerebral perfusion (RCP) combined with hypothermia was reported. The authors evaluated the cerebral microcirculation during RCP by direct observation with a charge-coupled device (CCD) microscope. In six craniotomied, anesthetized swine, cardiopulmonary bypass was established by arterial perfusion through the femoral artery and venous drainage from the right atrium. The authors observed cerebral arteriolae and venulae on the brain surface. Each swine was cooled to a brain temperature of 20 degrees C. Perfusion was stopped, RCP was initiated with oxygenated blood through the superior vena cava, and cerebral perfusion pressure (CPP) was gradually increased. During antegrade cerebral perfusion (ACP), homogeneous vascular flow was observed in all models. During RCP, retrograde vascular flow was generated in four of the six models, but homogeneous retrograde vascular flow was achieved in arteriolae and venulae in only two models at a CPP of greater than 20 mmHg. It is suggested that homogeneous and effective retrograde perfusion may not be achieved at a CPP of less than 20 mmHg, and that RCP causes uneven microcirculation of the brain with a disadvantageous effect on cerebral protection when compared with ACP.

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Monitoring and regulating latissimus dorsi muscle performance for circulatory assist.

The purposes of this study were monitoring and regulating latissimus dorsi muscle (LDM) performance with muscle internal pressure and thickness, and with burst stimulation parameters, respectively. The unconditioned LDM flap of a pig was connected to a measurement system to examine force and contraction length. Internal pressure was measured using a catheter pressure transducer with a fluid-filled balloon inserted into the muscle, and correlated linearly with force during both contraction and relaxation. During contraction, thickness change correlated linearly with contraction length and the area enclosed within an internal pressure-thickness curve, and the X-axis was correlated linearly with muscle work. Stroke work increased incrementally according to the pulse width up to 6.72 msec or burst rate up to 120 Hz, and then plateaued at 240 Hz. The authors conclude that muscle work during contraction could be monitored with internal pressure and thickness, and that stroke work could be regulated with pulse width or burst rate.

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