Toshihiko Nakashima

Clinical analysis of a series of vertebral aneurysm cases.

We reviewed 38 cases of aneurysms of the vertebral artery treated over the last 10 years: 26 (68%) located at the junction of the vertebral and posterior inferior cerebellar arteries, 10 (26%) at the vertebral artery, and 2 (5%) at the vertebrobasilar union. There were three distinct forms of aneurysms: 20 saccular (53%), 10 fusiform (26%), and 8 dissecting (21%). Among these 38 aneurysms, 33 (87%) had ruptured: 18 of the saccular aneurysms (90%), all 10 of the fusiform aneurysms (100%), and 5 of the dissecting aneurysms (63%). Computed tomography of the 28 ruptured aneurysms revealed diffuse subarachnoid hemorrhage in the basal cistern combined with intraventricular hemorrhage in 24 cases (86%). Magnetic resonance imaging was useful for differentiating between fusiform and dissecting aneurysms. Abnormalities such as a double lumen of the vertebral artery were demonstrated in four of the dissecting aneurysms. The overall surgical results were good for 22 of the 27 surgically treated cases (81%). New bleeding was observed in 8 (24%) of the 33 ruptured aneurysms. The rate of new bleeding was high (60%) in the patients with dissecting aneurysms, and occurred mostly in the acute stage. The incidence of vasospasm was 27%, and only two patients suffered permanent neurological deficits. These findings indicate that the rate of new bleeding tends to be high in patients with saccular and dissecting aneurysms, and thus, they should be treated as early as possible. A preoperative balloon occlusion test should be conducted if proximal occlusion of the vertebral artery is necessary, since proximal occlusion is not always safe, despite angiographic evidence of sufficient contralateral arterial flow.

Postnatal development and enlargement of primary middle cranial fossa arachnoid cyst recognized on repeat CT scans

The etiology and mechanism of expansion of primary intracranial arachnoid cysts have been much debated. A rare case of an 8-month-old boy is reported, in which postnatal development and enlargement of a middle cranial fossa arachnoid cyst was detected on follow-up CT scans. Based on intraoperative and histological findings, the cyst was found to be intra-arachnoid. The wall was excised completely, and the lobe adjacent to the cyst appeared normal apart from signs of atrophy. Histological study of the excised cyst revealed a common arachnoid membrane with neither ependymal nor inflammatory cells; the cyst fluid was similar to CSF. The etiology of the lesion remains unclear, but it was considered that the expansion of the cyst might have occurred through a ball-valve mechanism of the membrane in communication with the general subarachnoid space.

Purification and characterization of a cytosolic phosphoinositide-phospholipase C (γ2-type) from human platelets

A human platelet cytosolic phosphoinositide-specific phospholipase C, one of four PLC activity peaks separated by column chromatographies, designated as cPLC-I, was purified to homogeneity. The cPLC-I exhibited an apparent Mr of 145 kDa by SDS-polyacrylamide gel electrophoresis and was immunologically identified to be PLC-gamma 2. It hydrolyzed PI and PIP2 at optimum pH of 5.5-6.0. Deoxycholate and cholate inhibited the enzyme activity to hydrolyze two substrates. Calcium was required to obtain the maximal activity for PI- and PIP2-hydrolysis at concentration of 10(-3) M and 10(-5) M, respectively. Hg2+ (1 microM) inhibited strongly the enzyme activity.

Germinoma in cerebral hemisphere associated with Down syndrome

Abstract A Down syndrome patient with germinoma developing in the cerebral hemisphere is reported. A review of the literature yielded only 14 cases of Down syndrome with brain tumors, including our case. This finding of brain tumors in patients with Down syndrome may reflect chance occurrence. However, it is of interest in this regard that in 6 of the 14 (43%) reported cases the lesions were intracranial germ cell tumors.

Activation of phosphoipase D by platelet-derived growth factor (PDGF) in rat C6 glioma cells: Possible role in mitogenic signal transduction

The effects of platelet-derived growth factor (PDGF) on phospholipase D (PLD) activity and deoxyribonucleic acid (DNA) synthesis in rat C6 glioma cells have been investigated. Pretreatment of serum-starved C6 cells with PDGF results in enhanced choline production and the phosphatidylethanol (PEt) formation in the presence of ethanol, indicating the activation of PLD acting on phosphatidylcholine (PC). The dose-response curve for choline generation and DNA synthesis were comparable. In addition, the effects of PDGF on both PEt formation and [3H]thymidine incorporation into acid-precipitable material was blocked by the potent protein kinase C (PKC) inhibitor 1-(5-isoquinolinesulphonyl)-2-methylpiperazine (H-7) but not by N-(2-guanidinoethyl)-5-isoquinolinesulphonamide (HA1004), a relatively weak inhibitor of PKC, suggesting that PDGF plays an important role as a positive regulator of glioma cell growth via a PLD-mediated mitogenic signal transduction cascades, which depends largely on the activation of PKC.

Phospholipase C Activity in Cerebrospinal Fluid Following Subarachnoid Hemorrhage Related to Brain Damage

Phosphoinositide-specific phospholipase C (PLC) activities were measured in CSF from patients after subarachnoid hemorrhage (SAH). Their PLC activities were significantly higher than those in control CSF. Moreover, there was an obvious correlation between the PLC activity in CSF collected on day 3 and the preoperative clinical grade. The PLC activity was also closely correlated with the level of neuron-specific enolase as a marker of brain damage. Furthermore, the PLC activities were partially purified from CSF of patients after SAH and were immunologically identified to be PLCβ, PLCγ, and PLCδ. These results suggest that PLCs are released into the CSF from brain tissue in conjunction with the initial hemorrhage and that their activity may reflect the extent of brain damage.

Purification of a factor from CSF in patient after SAH which induces the cytosolic free calcium elevation in vascular smooth muscle cells

Cerebrospinal fluid from patients with aneurysmal subarachnoid hemorrhage induces the elevation of cytosolic free calcium [Ca2+]i in cultured vascular smooth muscle cells. We have purified a [Ca2+]i elevating factor from cerebrospinal fluid of a patient with subarachnoid hemorrhage due to aneurysm rupture. The calcium-elevating protein factor was purified to homogeneity by ammonium sulfate precipitation and a combination of Mono Q, Superose 12, and Mono S columns using liquid chromatography. Fifteen microgram of the purified protein was obtained from 340 mg of cerebrospinal fluid proteins and the molecular mass of the protein was estimated to be 81 kDa by sodium dodecyl sulfate polyacrylamide gel electrophoresis. It was also shown that the purified protein was cross-reactive with anti-human transferrin antibody. These results suggested that transferrin may be involved with the cerebral vasospasm after subarachnoid hemorrhage.