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Biomedical subjects

Y Kaku

Publications and source records attributed to Y Kaku.

At least 19 recordsLinked to original sources
PubMed2006

The role of intraoperative monitoring of oculomotor and trochlear nuclei -safe entry zone to tegmental lesions.

OBJECTIVE: A safe entry zone to tegmental lesions was identified based on intraoperative electrophysiological findings, the compound muscle action potentials (CMAP) from the extraocular muscles, and anatomic considerations. This entry zone is bordered caudally by the intramesencephalic path of the trochlear, laterally by the spinothalamic tract, and rostrally by the caudal margin of the brachium of the superior colliculus. METHODS: Four intrinsic midbrain lesions were operated upon via the safe entry zone using the infratentorial paramedian supracerebellar approach. All lesions involved the tegmentum and included an anaplastic astrocytoma, a metastatic brain tumor, a radiation necrosis, and a cavernous angioma. CMAP were bilaterally monitored from the inferior recti (for oculomotor function) and superior oblique (for trochlear nerve function) muscles. RESULTS: In three of four cases, CMAP related to the oculomotor nerve were obtained upon stimulation at the cavity wall after removal of the tumor. Stimulation at the surface of the quadrigeminal plate, however, did not cause any CMAP response. Using this monitoring as an indicator, the lesions were totally removed. CONCLUSIONS: In the surgery of tegmental lesions, CMAP monitoring from extraocular muscles is particularly helpful to prevent damage to crucial neural structures during removal of intrinsic lesions, but less so to select the site of the medullary incision. The approach via the lateral part of the colliculi is considered to be a safe route to approach the tegmental lesions.

Action Potentials↗
PubMed2006

Carotid-compression technique for the insertion of guiding catheters.

Inserting a guiding catheter into a tortuous artery for neurointerventional procedures can be difficult. In our technique, the carotid artery is manually compressed to stabilize and/or straighten the inserted wire before advancing the guiding catheter. Although this technique is not risk-free and care must be taken to avoid vascular injury by excessive compression, it is useful for the insertion of a guiding catheter into the carotid artery.

Aged↗
PubMed2005

Genetic variation and geographic distribution of porcine reproductive and respiratory syndrome virus in Japan.

Porcine reproductive and respiratory syndrome virus (PRRSV) has two genotypes, the North American-type (NA-type) and the European-type (EU-type), and each genotype is also genetically diverged. We sequenced the ORF5 gene of 30 PRRSVs isolated from 23 prefectures of Japan during 1992 and 1993 and during 2000 and 2001. All of the isolates were of the NA-type. Phylogenetic analysis of the overall NA-type viruses isolated from around the world identified five major genetic clusters. The 1992-1993 Japanese samples belonged to only two genetic clusters, while the 2000-2001 samples included more diverged ORF5 genomes. One genetic cluster, which included 63% (20/32) of Japanese isolates, one Taiwanese isolate and one Chinese isolate, was mainly found in the eastern part of Japan. Another genetic cluster, which was found in various areas around the world, was distributed in the western part of Japan.

Animals↗
PubMed2005

Conventional microsurgical technique and endovascular method for the treatment of cerebral aneurysms: a comparative view.

Endovascular embolization using Guglielmi Detachable Coils (GDCs) for complicated intracranial aneurysms has become widely accepted as an alternative to direct surgery. There is now a choice of therapeutic options for the management of cerebral aneurysms. The decision for treatment of an individual patient should be based on objective selection of the safest and most effective treatment. In addition, less invasive and cost effective treatment should be chosen. It is self-evident that the primary consideration in the selection process must be the immediate and long-term welfare of the individual patient, rather than the physician's preference for any specific treatment modality. GDC embolization is a less invasive and safe treatment with low incidence of periprocedural morbidity, and has been successful in preventing acute subsequent bleeding, whereas follow-up results are less satisfactory in cases involving incompletely obliterated lesions. High incidence of recanalization was promoted in cases with neck remnant and/or body filling. In contrast, the most important advantage of direct surgery is long-term durability, while conditions of patients and aneurysmal geometry limit the indication of direct surgery. In addition, direct surgery could be applied to complicated aneurysms with wide-neck or branching from the neck in combination with vascular reconstruction technique, such as EC-IC bypass. With these limitations in mind, patients need to be very carefully chosen for GDC embolization or direct surgery.

Blood Vessel Prosthesis↗
PubMed2004

Considerations in the surgical treatment of superior-wall type aneurysm at the proximal (M1) segment of the middle cerebral artery.

OBJECTIVE: To present our experience and analyze the risks of neck clipping for superior-wall type aneurysms of the proximal segment of the middle cerebral artery (M1-Sup aneurysm). METHODS: Of 14 patients with M1-Sup aneurysms, 4 suffered postoperative infarctions in the territory of the lenticulostriate arteries (LSA) or fronto-orbital arteries. We re-examined our intraoperative findings and clinical records in an effort to identify possible causes. RESULTS: The patency of the LSA was confirmed at the end of surgery in all 14 cases. We posit that temporary occlusion of the LSA by a permanent clip resulted in delayed obstruction of the LSA in 3 patients. Other possibilities we considered were relatively long temporary occlusion of the M1, slipping of the clips and twisting of the clip blades after release of the brain retractors. CONCLUSION: M1-Sup aneurysms are some of the most complicated aneurysms; they carry the risk of perforator injury during neck clipping. Surgical considerations to avoid perforator injury are discussed.

Adult↗
PubMed2004

Nonsuppurative encephalitis in piglets after experimental inoculation of Japanese encephalitis flavivirus isolated from pigs.

Nonsuppurative encephalitis was experimentally induced in 3-week-old piglets by a single intravenous inoculation of either of two strains (IB 2001 or AS-6) of Japanese encephalitis flavivirus (JEV) isolated from field pigs. The lesions, which consisted of neuronal necrosis, neuronophagia, glial nodules, and perivas-cular cuffing, were distributed in the cerebrum, midbrain, pons, medulla oblongata, and cerebellum, particularly in the gray matter of the frontal and temporal lobes and thalamus. The gray matter of the spinal cord of piglets that were given the AS-6 strain also was affected. JEV antigen was immunohistochemically detected in the cytoplasm of the nerve cells in the cortex of the frontal and temporal lobes and in the gray matter of the thalamus and midbrain. Two JEV strains isolated from field pigs exhibited neurovirulence, inducing nonsup-purative encephalitis in piglets.

Animals↗
PubMed2002

Failure of stent-assisted endovascular treatment for ruptured dissecting aneurysms of the basilar artery.

We report two instructive cases of ruptured dissecting aneurysm of the basilar artery. Although stent-assisted endovascular treatment was successful, recurrent bleeding occurred 4 h after the procedure in one patient, and the other's basilar artery occluded 6 days after the procedure. These cases suggest that the high porosity of currently available stents may be insufficient to induce intraluminal thrombosis and merely stenting may fail to prevent bleeding, while postoperative anticoagulation alone may be inadequate to prevent occlusion of the stented vessel.

Adult↗
PubMed2002

Endovascular aneurysm treatment from the neurosurgeon's point of view.

Recent advancement in microneurosurgery and interventional neuroradiology has brought us a new aspect in the treatment of cerebral aneurysms. There is now a choice of several therapeutic alternatives for the management of cerebral aneurysms. The selection of interventional neuroradiologic techniques with GDC therefore requires consideration of neurosurgical techniques, just as the selection of neurosurgical treatment requires an analysis of endovascular alternatives. The decision for treatment of an individual patient should be based on objective selection of the safest and the most effective treatment. It is self-evident that the primary consideration in the selection process must be the immediate and long-term welfare of the individual patient, rather than the physician's preference for any specific treatment modality. Although GDC embolization has been successful in preventing acute subsequent bleeding of aneurysms, incomplete endovascular occlusion of aneurysm leaves the patient at risk for future expansion and future subarachnoid hemorrhage. With this limitation in mind, patients need to be very carefully chosen for GDC embolization. Endovascular treatment of intracranial aneurysms with GDCs has thus been limited to adjuvant or palliative indications for many patients.

Aneurysm, Ruptured↗
PubMed2001

The clinical utility of contrast-enhanced 3D MR angiography for cerebrovascular disease.

The purpose of this study was to evaluate the usefulness of contrast-enhanced 3D MR angiography (CE-MRA) with an automated bolus-detection algorithm (SmartPrep technique) and the specialized phased-array coils for the patients suspected cerebrovascular disease. Forty-three patients with brain attack were examined with CE-MRA. A tracker volume of SmartPrep technique was placed along the ascending aorta in the coronal image. After the bolus injection of gadolinium, an increase in signal that corresponded to the arrival of gadolinium was used to trigger centric re-ordered spoiled gradient echo arterial selective MRA with imaging time of 20-40 sec. We were able to achieve a 100% successful triggering rate of SmartPrep technique and selectively arterial-phase carotid and vertebral arteries with almost no venous contamination could be delineated. These techniques enabled high resolution imaging of entire craniocervical arteries from aortic arch to the circle of Willis. This CE-MRA was useful to evaluate both occlusion of arteries and the collateral pathways and to measure stenosis and residual flow of dissection accurately. CE-MRA was a reliable less-invasive alternative to investigate the patients of cerebrovascular disease.

Brain↗
PubMed2001

Supracerebellar transtentorial approach to posterior temporomedial structures.

The supracerebellar transtentorial (SCTT) approach, a modification of the infratentorial supracerebellar approach, facilitates simple and minimally invasive access to posterior temporomedial structures without requiring retraction of the temporal or occipital lobe. The SCTT approach was used in 16 patients over a 3-year period. Eleven patients harbored tumors confined to, or located mainly within, the posterior hippocampal formation, three patients harbored aneurysms (one ruptured posterior cerebral artery [PCA] aneurysm at the P2-P3 junction, one ruptured giant PCA [P2] aneurysm, and one giant basilar artery-superior cerebellar artery aneurysm), one patient had juvenile-type moyamoya disease, and one patient suffered from medically intractable epilepsy. In these patients, the SCTT approach enabled tumor removal, aneurysm clipping, and vascular bypass procedures. The authors' experience suggests that this approach can be used routinely in treating lesions in the posterior temporomedial region.

Adolescent↗
PubMed2001

[A case of a persistent primitive proatlantal intersegmental artery with a ruptured basilar bifurcation aneurysm].

A case of persistent primitive proatlantal intersegmental artery (PPPIA) associated with a ruptured basilar bifurcation aneurysm was reported. A 44-year-old male with sudden headache was admitted to our hospital. CT scan revealed subarachnoid hemorrhage. Cerebral angiography revealed anomalous anastomosis between the internal carotid artery and the vertebral artery at the proatlantal region. This anastomosis branched off from the left internal carotid artery at the C4 level and joined the horizontal portion of the left vertebral artery. It was thought to be PPPIA. Angiography also revealed an aneurysm of the basilar bifurcation which was responsible for the patient's subarachnoid hemorrhage. The aneurysm was successfully treated by endovascular embolization with Guglielmi detachable coils in an acute stage, and resulted in good outcome. PPPIA with basilar bifurcation aneurysm has not been presented or reported in the literature to date. To our knowledge, this is the first report of such an association of vascular anomalies. The frequency of PPPIA combined with the intracranial aneurysm is relatively high, whereas the occurrence of PPPIA is extremely rare. Therefore, it was suggested that some congenital and/or hemodynamic factors changed by PPPIA may affect the pathogenesis of intracranial aneurysms.

Adult↗
PubMed2000

Renal tubular acidosis associated with zonisamide therapy.

PURPOSE: We sought to report a previously undescribed adverse effect, renal tubular acidosis associated with zonisamide (ZNS) therapy. METHODS: Ammonium chloride, bicarbonate, and furosemide loading tests were performed in an epileptic patient with metabolic acidosis and episodic hypokalemia who was treated with ZNS. RESULTS: Distal renal tubular acidosis was diagnosed. On reexamination 7 weeks after ZNS had been replaced with phenytoin, the renal tubular acidosis disappeared. CONCLUSIONS: This case indicates, for the first time, that ZNS might be a potential cause of renal tubular acidosis. Blood gases and serum electrolytes should be measured in patients undergoing ZNS therapy.

Acidosis, Renal Tubular↗
PubMed2000

Complement component 9 deficiency is not a susceptibility factor for SLE.

Almost all complement component 9 (C9) deficiency in Japan shows Arg95 Stop mutation of C9 gene. Therefore, we studied the prevalence of Arg95Stop mutation of C9 gene among 78 patients with SLE to elucidate the association of SLE and C9 deficiency. The Arg95Stop carrier frequency showed no significant difference between SLE patients and controls. Thus, C9 deficiency is not implicated in SLE susceptibility.

Complement C9↗
PubMed2000

[Coil embolization for incidental aneurysms in patients with chronic renal failure: midterm clinical results of two cases].

In spite of recent advances in perioperative management, the risk of neurosurgical intervention for patients with chronic renal failure is still considered too high. In this study, coil embolization for incidental aneurysms in such patients is demonstrated in reference to midterm results. A 42-year-old woman with a history of hemodialisis for 7 years presented with subcortical hemorrhage in her right frontal lobe. The magnetic resonance angiography (MRA) demonstrated a distal anterior cerebral artery aneurysm, but it was considered to be unrelated to the hemorrhage. Two and a half months after the hemorrhage the aneurysm was embolized with interlocking detachable coils. Thirty months after embolization, the angiogram revealed the coil compaction and the recanalization of the aneurysm neck. However, 54 months after embolization, the figure of the embolized aneurysm and neck remnant was the same as the previous findings. A 69-year-old woman with a history of hemodialisis for 5 years suddenly experienced left hemiparesis. Computed tomography revealed cerebral infarction in the right frontoparietal white matter. In addition, a left middle cerebral artery aneurysm was unexpectedly found on the MRA. Five months after the onset of the attack, the aneurysm was embolized with a Guglielmi detachable coli. An angiogram obtained 24 months after the embolization showed the aneurysm to be almost completely obliterated. In considering the therapeutic risks and benefits for incidental aneurysms of patients with chronic renal failure, intra-vascular surgery could be recommended as a less invasive treatment.

Adult↗
PubMed1999

Sequence determination and phylogenetic analysis of RNA-dependent RNA polymerase (RdRp) of the porcine enterovirus 1 (PEV-1) Talfan strain.

The nucleotide sequence of the region including the RNA-dependent RNA polymerase (RdRp) of the porcine enterovirus 1 (PEV-1) Talfan strain was determined. Amino acid identities of Talfan RdRp with those of other picornaviruses were significantly lower than those seen among the viruses of the same genus of picornaviruses. The phylogenetic analysis of RdRp indicated that picornaviruses were divided into 8 clusters, in which Talfan was genetically distinct from other picornaviruses in contrast to the current taxonomy. In this study, we propose that PEV-1 Talfan be regarded as a new genus for the family Picorna- viridae.

Amino Acid Sequence↗
PubMed1999

Development of a dural arteriovenous fistula around the jugular valve after transvenous embolization of cavernous dural arteriovenous fistula.

BACKGROUND: Endovascular therapy for dural arteriovenous fistulas (DAVFs) is not without any risks, although it has been generally accepted to be a safe procedure. In this paper, we report a very rare complication: metachronous DAVF around a jugular valve 4 months after transvenous embolization. CASE DESCRIPTION: A 43-year-old woman presented with left proptosis, chemosis, and double vision. Cerebral angiography demonstrated a left cavernous DAVF. The patient's symptoms resolved almost completely after embolization with platinum coils via the superior ophthalmic vein. Four months later, angiography revealed a metachronous DAVF around a jugular valve. CONCLUSION: To our knowledge, only four such cases have been reported in the literature. Careful follow-up of patients treated with transvenous embolization and accumulation of such cases are needed to understand the pathogenesis of multiple DAVFs.

Adult↗