A Study of the Effects of Systemic Heparin and Intrathecal Urokinase on Experimental Cerebral Vasospasm

The author has investigated the protective effects of systemic Heparin and intrathecal Urokinase in the multi-hemorrhage canine model of severe chronic cerebral vasospasm. Each of 20 adult mongrel dogs was assigned to one of three experimental groups. All animals received a total of 12ml of fresh unheparinized autologous blood via three cisternal injections. Selective vertebral angiograms were obtained before and 8 days after the initial subarachnoid blood injection. Seven animals were treated by systemic Heparin for 7 days, the other seven were treated by intracisternal Urokinase for 3 days, and the remaining were not treated. Comparisons were based on the percentage of reduction in basilar artery diameter(% RBAD). The ultrastructural changes were studied by transmission electron microscopy(TEM). There was a mean reduction(+/-standard deviation) of 65+/-7% in control dogs, 53+/-5% in dogs with systemic Heparin(difference significant t-test, p<0.01), 37+/-6% in dogs with intrathecal Urokinase(difference signignificant, t-test, p<0.01). The preventive effects of intrathecal Urokinase was superior to systemic Heparin. There was a stroung trend toward reduction of medial necrosis in the basilar artery in dogs with intrathecal Urokinase(p<0.01), and with systemic Heparin(0.05

Experimential Brain Stem Compression

Patterns of brain-stem compression and secondary brain-stem evoked postentials were investigated to correlate with expanding mass volume and location in mass-induced supratentorial brain compression in cats in which the subjects were divided into four experimental group i.e., frontal, temporal, parietal, and occipital brain-compressed groups. Postmortem insepection of the brain-stem showed either unilateral or bilateral dorsal herniation of the brain in frontal and temporal brain-compressed groups and dorsolateral herniation in parietal and occipital brain-compressed groups, respectively. Microscopic examination revealed that the secondary brain-stem hemorrhages were mostly caused by venous bleeding secondary to venous congestion, the bleeding being more severe in occipital brain-compressed group. As the intracranial pressure was raised by expansion of a supratentorial balloon, the late components of the BSEP were suppressed first, followed by the suppression of the early components. In BSEP recording a significant change was observed in Vth wave with prolongation of latency and decrease in amplitude. This finding suggests that the midbrain is the most vulnerable to compression ischemia. In parietal group, the Vth wave started to be prolonged at 0.4ml of balloon expansion and totally disappeared at 1.8ml of expansion.

A Study of the Effect of Naloxone on the Lipid Peroxidation and the Fine Structure of the Myelin Sheath in the Injured Spinal Cord

Spinal Cord contusions in cats were produced experimentally by impact injuries to the surgically exposed cord at the second lumbar vertebral level. As a step in the investigation of the possible effect of spinal cord trauma on biochemical and ultrastructural changes in the injured cord, activities of lipid peroxidation were measured in the frozen-dried sample of the spinal cord and the fine structure of the myelinated nerve fiber in the white matter were observed before and after the cord injury. An increase of lipid peroxidation level was found as early as 30 minutes after the injury and the highest concentration was reached at 4 hours of injury. Fine structures of the myelinated nerve fibers were changed progressively with the lapse of time after the injury. By 1 hour after the contusion the myelinated nerve fibers showed moderately enlarged periaxonal space, attenuation and disarray of the myelin sheaths. By 4 hour after the contusion, there appeared disarray of the myelin sheaths, greatly enlarged periaxonal space and irregulary contoured axons. The effect of naloxone of the lipid peroxidation and fine ultrastructure of the myelinated nerve fibers were studied, and the results of this study suggested that naloxone have a beneficial effect on the change in lipid peroxidation and the preservation of the myelinated nerve fibers after injury.