Fumiaki Isaka

Ectopic expression of the bHLH gene Math1 disturbs neural development

The basic helix–loop–helix gene Math1, a positive regulator of neuronal differentiation, is specifically expressed in the dorsal part of the developing nervous system. To determine the effects of ectopic expression of Math1, we generated two transgenic mouse lines; One carried the Cre recombinase gene under the control of the nestin promoter and enhancer, which direct expression in neural precursor cells, and the other carried the Math1 gene, the expression of which was regulated by the cytomegalovirus (CMV) promoter but interrupted by the stop cassette flanked by loxP sites. In F1 embryos that carried the two transgenes, the stop cassette was removed by Cre recombinase in the developing nervous system, and Math1 expression was ectopically directed from the CMV promoter. We found that these embryos exhibited abnormal morphology of the brain and extensive cell death in the nervous system. These results suggest that ectopic expression of Math1 is toxic to neurons and leads to apoptosis.

Endovascular treatment of aneurysms on the feeding arteries of intracranial arteriovenous malformations

Abstract The association between intracranial aneurysms and arteriovenous malformations (AVMs) is well documented. Recent advances in the understanding of the haemodynamics of this association encourage an aggressive approach to these aneurysms. However, the pathophysiology of these aneurysms is not fully understood and a strategy for their management has not been established. We describe seven patients, with eight aneurysms, on the feeding arteries of AVMs. The aneurysms could be divided into those located 1. proximally on the superficial feeding artery (type I; 4 aneurysms); 2. distally on the superficial feeding artery (type II; 3 aneurysms); and 3. on the deep feeding artery (type III; 1 aneurysm). All aneurysms were treated by the endovascular procedure prior to, or simultaneously with, treatment of the AVM, using detachable coils or liquid embolic material. All aneurysms were obliterated successfully, with no adverse events. Each patient further received treatment of the AVM. None of the patients suffered intracranial haemorrhage after treatment for the aneurysms. Based on our experiences, we discuss the indications for this approach for each type of aneurysm. We believe endovascular treatment could be an important alternative for treatment of aneurysms associated with AVMs, thus reducing the risk of haemorrhage.

An Infected Aneurysm of the Vertebral Artery Treated with a Stent-graft: A Case Report

In a 75-year-old man, a growing vertebral artery aneurysm at the C3/4 intervertebral level was found at postoperative evaluation of cervical abscess, which was diagnosed as a complication of sepsis subsequent to cholangitis. Even after a successful antibiotic treatment and a surgical drainage, the aneurysm grew enough to cause compression of esophagus and trachea. The aneurysm was judged to be infection-related, based on the clinical course and the anatomical vicinity to the abscess. Following a dual antiplatelet treatment (clopidogrel 75 mg and aspirin 100 mg per day) for a week, the patient underwent endovascular treatment of the aneurysm with a stent-graft. Postoperative angiography showed complete obliteration of the aneurysm with preserving patency of the vertebral artery. A dual antiplatelet treatment was continued for 6 months and was changed to a single antiplatelet treatment (clopidogrel 75 mg per day) thereafter. Neither recurrence of the aneurysm nor stent-graft infection was observed for 4 years of follow-up. This case illustrates the potential use of a stent-graft in the treatment of an infected aneurysm.

Modification of immediately electrically detachable coil.

An immediately electrically detachable coil (IEDC) that we previously developed was modified to enhance the reliability in its detachment system. IEDC is detached by applying a monopolar high-frequency electrical current that heat and disrupt a junction between a platinum coil and a delivery wire. The original IEDC immediately detaches only when the junction is just outside the catheter tip and precise positioning of the junction is required. In the modified IEDC Its delivery wire was insulated with polytetra fluoroethylene (PTFE) to concentrate electrical current to the junction. The modified IEDC was tested in vitro and in animal experiments. Modified IEDC always detached instantaneously even when the junction was far beyond the catheter tip. Insulated delivery wire enabled the electrical current to be concentrated at the PVA junction and produce appropriate heat to disrupt the junction.

Initial experiences of carotid stenting with palmaz stent.

Results of cervical carotid stenting are reported. Twenty-nine lesions in 25 cases were treated by percutaneous transluminal balloon angioplasty combined with stent placement. All the lesions were successfully dilated. There was one embolic complication during the operation that caused deterioration of preoperative symptoms. Stent deformation causing more than 30% luminal narrowing occurred in one case. Instent restenosis with more than 50% luminal narrowing was seen in bilateral lesions in one case. These were satisfactory results as an initial experience, but further improvement in this technique is considered essential especially to avoid embolic complications.

Intra-aneurysmal Occlusion of Cerebral Aneurysms Using Detachable Coils. Correlation of Aneurysm Neck Size and Treatment Results.

The aneurysmal neck size seems to be an import ant factor in the endovascular treatment outcome4,5. The purpose of the present study was to measure aneurysm neck size on angiographic films, and compare the measured value with the extent of intra-aneurysmal occlusion performed with detachable coils. The subjects were 22 patients with intracranial aneurysms treated using detachable coils. The cases were divided into two groups according to the aneurysmal neck size, 4 mm being the discriminating value for small neck. The neck of the aneurysm was successfully occluded in 19 of 22 patients. Ten aneurysms had a small neck and 9 aneurysms had a wide neck. Complete aneurysm occlusion was observed in 70% of small neck aneurysms and 25% of wide neck aneurysms. The results support that the size of the aneurysm neck correlates well with the effectiveness of endovascular treatment.