Efficacy of a blood substitute (Fluosol-DA, 20%) on cerebral ischemia

Fluosol-DA, 20%, was intravenously infused in 28 patients suffering from cerebrovascular disease, and was found to be effective in 60% of the cases with vasospasm and in 80% of the cases with stenosis and/or occlusion of the artery. Administration of the solution increases r-CBF by 10.1 to 37.9% when measured by either intra-arterial injection or inhalation of 133Xe. However, an increase of arterial oxygen tension appears to have little effect on r-CBF after administration of the solution. The increase of r-CBF caused by Fluosol-DA, 20%, may be due not only to the lowering viscosity of the mixed blood but also to its direct effect on dilating cerebral vessels.     

New small-caliber antithrombotic vascular prosthesis: experimental study

Vascular prostheses with the inner diameter smaller than 1 mm were implanted to the common carotid artery of rats, and their patency was examined. Four types of tubes were prepared for this purpose in Experiment 1: polyethylene (PE), poly-(acrylic acid)-grafted polyethylene (PE-AA), polyacrylamide-grafted polyethylene (PE-AAm), and poly(vinyl alcohol) (PVA) tubes. Comparative studies made using nonsuture anastomosis revealed that the PE-AAm and PVA tubes were antithrombotic, although disconnection was noted at the anastomotic sites within 1 week and 1 month, respectively. Thereafter in Experiment 2, the PVA tubes were implanted to the common carotid artery of 20 rats using conventional anastomosis. Neither anticoagulants nor fibrinolytic agents were used in both series of experiments. Patency of the PVA tubes was 80% after 1 week and 70% after 1 month. In patent cases after 1 month, the luminal surfaces of the prostheses and the host arteries were examined using scanning electron microscopy. The lumen of the arteries and anastomotic sites was covered with endothelial cells, while the lumen of the PVA tubes was free from thrombi and there was no neointima formation. So far, there has been reported no manmade material that has completely antithrombotic property in vivo. However, our studies disclosed that PVA is antithrombotic and one of the most promising materials for the inner surface of small vascular prostheses.     

Melanotic astrocytoma

A case of pigmented pilocytic astrocytoma (WHO grade I) incidentally found in a right temporopolar lobectomy specimen is reported. The patient, a 41-year-old woman, underwent surgery because of long-standing complex partial epilepsy of presumed post-traumatic origin. Using immunohistochemistry and electron microscopy, the tumor was shown to be composed of astrocytes without evidence of neurosecretory or melanocytic differentiation. The cytoplasmic pigment was identified as neuromelanin by its histochemical staining properties and ultrastructure. Although rare cases of ependymoma, subependymoma, choroid plexus papilloma and ganglioglioma with melanogenesis are on record, no melanotic astrocytoma has been described so far. Received: 6 September 1995 / Revised, accepted: 6 November 1995     

Development of tolerance of phenobarbital after administration over several days (author's transl)

In mice daily testing by maximal electroshock (MES) and pentylenetetrazole infusion (PTZ) 2 h after an i.p. injection of 25 mg/kg penobarbital (PB) was performed on days 1, 2, 4 through 8. The first twitch was delayed as compared to NaCl controls (50.4 +/- 4.8 s; 36.6 +/- 3.6 s; n = 53) on day 2, 4, 6 through 8. There was no tolerance of the PTZ induced tonic extension with Pb-treatment. In contrast, MES-tested mice developed tolerance, at day 5 the number of protected animals fell to about 50%. In view of the constant phenobarbital levels in plasma, a functional tolerance was assumed. The development of tolerance seemed to be connected with the spread of the discharge but not with discharge of the neurones themselves since it was observed only with MES but not wih PTZ-testing.     

Arteriovenous malformations of the cervical spinal cord--with special reference to CT study

Arteriovenous malformation (AVM) of the cervical spinal cord has been known to constitute 5-13% of all spinal AVMs. In contrast to the AVMs located in thoracic or thoraco-lumbar regions, cervical AVM has several characteristic features such as preponderance in younger generation, high incidence of subarachnoid hemorrhage, intramedullary location of the nidus usually fed by the anterior spinal arterial system. We reported three cases of cervical AVMs, which located intramedullary at the levels of C4-C6, C1-C4 and C1-C2, respectively. Although selective angiography (vertebral artery, thyrocervical artery, costocervical artery) was essential for the diagnosis of these lesions, computerized tomographic (CT) study with both intrathecal injection of metrizamide and intravenous infusion of contrast material (dynamic and static study) was found to be extremely advantageous in detecting the topography of AVMs in the concerned horizontal planes of the spinal cord. Removal of AVM was given up in one case because of its possible involvement of the anterior spinal artery and central artery shown by CT scan. Removal of AVMs were performed in other two cases. A lateral approach was tried in one case with the AVM located in C1-C2 level, in which CT scan revealed not only an intramedullary but the associated extramedullary AVM in ventrolateral surface of the spinal cord. This operative approach was found to involve less bone removal and markedly reduce spinal cord manipulation necessary to deal with ventrally situated high cervical lesions, compared with a posterior approach with laminectomy.     

Disposition of mephenytoin and its metabolite, nirvanol, in epileptic patients

We investigated the conversion of mephenytoin to nirvanol in five patients with uncontrolled complex partial seizures. After a 50-mg single oral dose, mean peak mephenytoin level was 0.48 microgram/ml and nirvanol 0.37 microgram/ml. After 400 mg, peak mephenytoin level was 3.9 micrograms/ml and nirvanol 2.5 micrograms/ml. On 400 mg daily, mephenytoin reached a mean steady-state level of 1.5 micrograms/ml. Nirvanol mean steady-state level was 18 micrograms/ml. Mean plasma half-life was 17 hours for mephenytoin and 114 hours for nirvanol. Two patients had reduced seizures during mephenytoin therapy and one a transient increase during drug withdrawal. No toxicity was seen, but mephenytoin was not more effective than phenytoin.