No abstract

Since ebselen is known to have glutathione peroxidase-like activity and inhibitory effects on lipoxygenase and cyclo-oxygenase, we investigated its protective effects against cerebral ischemia in the rat using microdialysis. Ebselen was given through a gastric tube 30 min before occlusion in the experimental groups. Ischemia was induced using 4-vessel occlusion either transiently (20-min occlusion of the arteries followed by reperfusion), or over a prolonged period (120-min occlusion). Extracellular lactate, pyruvate and purine catabolites were sampled using microdialysis and measured by high performance liquid chromatography. During ischemia, the level of lactate, adenosine, inosine and hypoxanthine in the control group increased markedly. The lactate: pyruvate ratio increased during ischemia and decreased after reperfusion. Although the level of lactate and adenosine decreased immediately after reperfusion, those of inosine and hypoxanthine showed delayed decrease. Ebselen reduced the maximum values of lactate and purine catabolites significantly and markedly in transient ischemia. Although it reduced the values significantly in prolonged ischemia, the decrements were less marked than those in transient ischemia. Based on these results we consider ebselen to protect against ischemic metabolic changes and to accelerate the recovery during reperfusion.

Summary:The hemodynamic changes occurring during obliteration procedures for arteriovenous malformations (AVM) have not been fully elucidated, Therefore, we un dertook a simulation study using a compartmental flow model to investigate the role of altered autoregulatory conditions in the development of hyperperfusion during obliteration of large high-flow A VM. Induced hypoten sion was also simulated to evaluate its usefulness in re ducing the incidence and severity of the event. As the A VM flow was decreased during the obliteration proce dures, feeder pressure increased and drainer pressure de creased, with a concomitant increase in the perfusion pressure in the brain tissue surrounding the A VM. Cere bral blood flow (CBF) remained constant at 50 miiOO g-l min -1 in the presence of autoregulation and increased to Microsurgery and intravascular surgery have re cently contributed considerably to progress in the management of formerly inoperable large arteriove nous malformations (A VM) of the brain (Andrews and Wilson, 1987;Drake, 1979;Stein and Solomon, 1990;Vinuela et al., 1991). Reduction of AVM flow volume induced by these therapeutic modalities is known to increase feeder pressure and decrease drainer pressure, both of which elevate the pressure gradient across the nidus as well as the perfusion pressure in the surrounding brain.Under physiological conditions, an autoregula tory mechanism maintains constant cerebral blood Received December 2, 1994; final revision received May 15, 1995; accepted May 15, 1995. Address correspondence and reprint requests to Dr. Shiro Nagasawa at Department of Neurosurgery, Osaka Medical Col lege, Daigaku-cho 2-7, Takatsuki-City, Osaka 569, Japan.Abbreviations used: A VM, arteriovenous malformation; CBF, cerebral blood flow; LAR, lower limit of autoregulatory range; NPPB, normal perfusion pressure breakthrough. 16267 ml 100 g -1 min -1 in its absence. When the lower limit of the autoregulatory pressure range (LAR) was shifted from 60 to 50 or 40 mm Hg, the flow volume increased markedly from 67 to 77 ml 100 g -1 min -I or to 92 ml 100 g -1 min -I after complete obliteration. Decrease in LAR would be a cause of the hyperperfusion. Induced sys temic hypotension was found to be effective in reducing the magnitude of these hemodynamic changes, when in duction was appropriately performed in a stepwise fash ion. A simulation study is useful in clarifying the various hemodynamic changes that develop during the treatment of A VM. Key Words: Arteriovenous malformation Autoregulation-Cerebral hemodynamics-Compart mental flow model-Regional cerebral blood flow Simulation.flow (CBF). However, the brain tissue surrounding a large high-flow A VM is considered to be chroni cally exposed to hypoperfusion, which may result in the impairment of autoregulatory mechanisms. These increased hemodynamic loads are likely to result in an abnormal increase in CBF, with cere bral edema and hemorrhage, in some large high flow AVM. This phenomenon is referred to as nor mal perfusion pressure breakthroug...

Real-time ultrasound was successfully applied to predict bovine fetal sex in early pregnancy. Ultrasound examinations were conducted in 68 cows through 117 trials between days 35 to 93 of pregnancy (day O = day of last artificial insemination). Regardless of fetal sex, the genital tubercle was readily recognized as a hyper-echogenic bilobar structure, and each lobe was elongated and oval shaped. The tubercle was first identified between the hind limbs on day 45 and then moved towards the umbilical cord in the male, while it moved towards the tail in the female. Thus sex of the fetus was diagnosed by ultrasonography in 90 cases. The diagnosis of sex was not possible in 27 cases: 18 cases with small fetuses before day 52, 2 cases with twin pregnancy, 2 cases with metroptosis after day 80, and 5 cases with maternal obesity. Accuracy of the ultrasonic diagnosis of fetal sex was 93.5% (43/46) for males and 90.9% (40/44) for females. The average umbilical-genital distance in frontal planes was significantly different between male and female fetuses by day 56. In conclusion, ultrasonic examination of the relative location of the genital tubercle was a reliable technique for determining bovine fetal sex between days 56 to 80 of pregnancy.

A case of a giant noninflammatory and nonatherosclerotic coronary arterial aneurysm in the left main trunk of a 69-year-old female is reported. Preoperative intravascular ultrasound (IVUS) images were helpful for visualizing the morphologic and histologic features of the coronary aneurysm. They were also useful for determining the etiologic background and surgical procedure.