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Biomedical subjects

F Imai

Publications and source records attributed to F Imai.

At least 19 recordsLinked to original sources
PubMed2001

Preservation of neurotrophin expression in microglia that migrate into the gerbil's brain across the blood-brain barrier.

Microglia isolated from a mixed glial culture drawn from neonatal Mongolian gerbils were demonstrated to produce high amounts of brain-derived neurotrophic factor (BDNF) and glial cell line-derived neurotrophic factor (GDNF). The gerbil microglia retained the capability to migrate into the brain parenchyma after intra-arterial injection. We found that exogenously migrated microglia retained their BDNF and GDNF productive ability and expressed large amounts of BDNF and GDNF in damaged brain areas which suggests microglia's role as a protectant of damaged neurons. Since peripherally injected microglia exhibit specific affinity for areas of neural damage within the brain, we suggest that microglia are possible tools for cell therapy of brain damage.

Animals↗
PubMed2001

Calmodulin binds to inv protein: implication for the regulation of inv function.

Establishment of the left-right asymmetry of internal organs is essential for the normal development of vertebrates. The inv mutant in mice shows a constant reversal of left-right asymmetry and although the inv gene has been cloned, its biochemical and cell biological functions have not been defined. Here, we show that calmodulin binds to mouse inv protein at two sites (IQ1 and IQ2). The binding of calmodulin to the IQ2 site occurs in the absence of Ca(2+) and is not observed in the presence of Ca(2+). Injection of mouse inv mRNA into the right blastomere of Xenopus embryos at the two-cell stage randomized the left-right asymmetry of the embryo and altered the patterns of Xnr-1 and Pitx2 expression. Importantly, inv mRNA that lacked the region encoding the IQ2 site was unable to randomize left-right asymmetry in Xenopus embryos, implying that the IQ2 site is essential for inv to randomize left-right asymmetry in Xenopus. These results suggest that calmodulin binding may regulate inv function. Based on our findings, we propose a model for the regulation of inv function by calcium-calmodulin and discuss its implications.

Amino Acid Sequence↗
PubMed2000

Neurosurgery at Fujita Health University, Japan.

Neurosurgery at the Fujita Health University began in 1972 with Dr. Tetsuo Kanno. In 1973, he was joined by Dr. Kazuhiro Katada and in the year 1976, an independent neurosurgery department was established with Dr. Kanno as the Chief of Neurosurgery. Under his guidance the department continued to grow and by 1978, a neurosurgical residency program recognised by the Japanese Board of Neurosurgery was established. Integration of laboratory research and clinical experience is the hallmark of this program. The current philosophy is directed towards subspecialization and academic training. This article provides a brief overview of the rapid development of a Neurosurgical Centre to reach international acclaim under the guidance of Prof. Tetsuo Kanno.

Hospitals, University↗
PubMed1999

Exogenous microglia enter the brain and migrate into ischaemic hippocampal lesions.

We compared migration of systemically injected microglia into normal brain vs. ischaemic brain using a model of ischaemic hippocampal lesion. Microglia were labeled by a fluorescent dye using our standard phagocytosis procedure of microscopic particles and then injected intra-arterially into Mongolian gerbils subjected to ischaemia reperfusion neuronal injury. Delayed death of pyramidal neurons was confirmed by conventional histological analysis and dUTP nick end labeling (TUNEL) method. Clusters of dye-tagged cells migrating into the hippocampal ischaemic lesions were confirmed histochemically to be microglia. Since peripherally injected microglia exhibit specific affinity for ischaemic brain lesions and does not exacerbate ischaemic neuronal injury in the present model, we suggest that microglia may have a potential to be used as a piggy-back ride to deliver therapeutic genes and/or drugs for CNS repair following transitory global ischaemic insult.

Animals↗
PubMed1998

Brain-specific gene expression by immortalized microglial cell-mediated gene transfer in the mammalian brain.

The intra-arterial injection of immortalized microglia transfected with the lacZ gene, resulted in the expression of beta-galactosidase in the rat brain at 48 h and the activity of -galactosidase was detected for up to 3 weeks post-injection. More than 30-fold higher activity of beta-galactosidase was detected in the brain than in the liver, lung or spleen at 48 h post-injection. This method allows us to easily deliver the gene of interest to the brain without influencing other organs. Our brain-targeting gene delivery system can facilitate gene therapy of several brain disorders, including brain tumor, metabolic disorders, and degenerative disorders, as well as investigation into the roles of particular genes in brain function and development.

Animals↗
PubMed1998

Successful resection of arteriovenous malformations in eloquent areas diagnosed by surface anatomy scanning and motor evoked potential.

Successful resection of cerebral arteriovenous malformations (AVMs) involving the sensorimotor cortex was achieved in 17 cases. The theoretical basis for performing resection of AVMs in eloquent areas is the fact that the brain in and around the nidus about 1 mm in thickness is considered not to be functioning. It is also considered that any center of important function, when an AVM is involved, shifts to the near-by cortex from the original site. Nevertheless, it is critically important to recognize the cortex functioning as sensorimotor centers before and during operation. For this purpose, we have used surface anatomy scanning (SAS) in combination with magnetic resonance angiography. SAS is found to be very useful for the recognition of the topographical relationship between the surface anatomy and AVM. During operation, the motor cortex is identified with motor evoked potential. We have found that, in some cases, the motor center has shifted to the accessory motor cortex. With these information, it is possible to start resection of the lesion from dissection of the main feeders and dissection of the nidus from a silent cortex toward the critical area. Apparent neurological improvements were achieved in 15 of 17 patients treated surgically (88%). With this result, we think that AVMs in eloquent areas can be treated successfully when the surgery is well-designed and well-oriented with the combined use of diagnostic imaging and monitoring. As for control of intraoperative bleeding, careful attention to small but important surgical techniques avoids troublesome bleeding during AVM surgery.

Arteriovenous Malformations↗
PubMed1997

Migration activity of microglia and macrophages into rat brain.

We examined the entry of intra-arterially injected microglia and macrophages into the brain using a rat muscle graft model to compare their respective abilities to invade the brain parenchyma. Isolated microglia without any activation treatment entered into the brain with or without the muscle graft, while macrophages activated by phorbol 12-myristate-13-acetate (PMA) entered the brain only in the presence of the muscle graft. These results suggest that microglia have a higher affinity for the brain than macrophages.

Animals↗
PubMed1997

Clinical efficacy of lactulose in cirrhotic patients with and without subclinical hepatic encephalopathy.

Seventy-five cirrhotic patients with hyperammonemia in the past or at the time of the study were randomly divided into two groups (treated with lactulose or nontreated) in 14 hospitals in Japan. Thirty-six cirrhotic patients were diagnosed as having subclinical hepatic encephalopathy (SHE), and 39 were diagnosed as non-SHE. SHE was diagnosed when the results of all three of the quantitative psychometric tests used (number connection test, and symbol digit and block design tests of the Wechsler adult intelligence scale [revised]) were abnormal as compared with age-matched normal values. The mean number of abnormal psychometric test results and the prevalence of SHE were used for a quantitative evaluation of the efficacy of the lactulose treatment. Twenty-two of the SHE patients were treated with lactulose (45 mL/d) for 8 weeks, and the other 14 SHE patients did not receive lactulose. In the SHE patients administered lactulose, the results of the quantitative psychometric evaluation were significantly improved at 4 and 8 weeks after the beginning of the lactulose administration. The SHE had disappeared in 10 (50%) of the 20 treated patients at week 8, but it persisted in 11 (85%) of the untreated 13 patients. We concluded that lactulose treatment in cirrhotic patients with SHE is effective with respect to psychometric tests.

Administration, Oral↗
PubMed1997

[Primary biliary cirrhosis (PBC)-CREST overlap syndrome complicated with Sjögren's syndrome].

We reported two sisters of primary biliary cirrhosis (PBC)-CREST overlap syndrome complicated with Sjögren's syndrome (SS). Both patients had Raynaud's phenomenon, sclerodactylia, telangiectasia, chronic sialoadenitis, chronic nonsuppurative destructive cholangitis by liver biopsy and were positive for anti-centromere antibodies. This is the first report of two sisters of PBC-CREST overlap syndrome complicated with SS.

Autoantibodies↗
PubMed1996

Synthesized surface anatomy scanning (SSAS) for surgical planning of brain metastasis at the sensorimotor region: initial experience with 5 patients.

Surface anatomy scanning (SAS) is a powerful technique that uses T2-weighted magnetic resonance images (MRI) to visualize brain surface structures, and to precisely localize subcortical lesions. To overcome technical limitations of this method, synthesized SAS (SSAS) superimposes MR angiography (MRA) data on the SAS images. We describe our initial experience with surgical planning for the resection of metastases at the sensorimotor region in 5 patients using SSAS. Neurological deficits were assessed before and after surgical resection. Although 4 of 5 patients had mild to severe neurological deficits before surgery, three became symptom-free and no patient had an increased deficit after surgery. Our results undoubtedly provide palliative surgery for sensorimotor metastases. As SSAS is non-invasive and requires a short scanning time, this method could become a useful technique for the routine pre-operative simulation for surgery on brain surface lesions such as sensorimotor metastases.

Adenocarcinoma↗
PubMed1996

Stereoscopic synthesized brain-surface imaging with MR angiography for localization of a peripheral mycotic aneurysm: case report.

A patient with subacute bacterial endocarditis and a peripheral mycotic aneurysm is presented. We used a combined multi-slice surface anatomy scanning (SAS) and contrast-enhanced MR angiography image to determine the exact location of the small lesion by applying a skin marker on the scalp and visualizing the relationship of the marker to the brain surface structures and to the lesion. This technique was useful for the removal of a small peripheral aneurysm using only a limited craniotomy.

Aged↗
PubMed1996

Surgical treatment of internal carotid siphon aneurysms.

Surgical treatment of internal carotid artery aneurysms around the carotid siphon is discussed. The surgical approach to the aneurysms in this region, is as follows: 1. A fronto-temporal approach with the patient in a 45 degrees semi-sitting position to decrease venous pressure. 2. A Dolenc approach cutting a part of the dura mater of the superior orbital fissure to facilitate removal of the anterior clinoid process and unroofing of the optic canal. 3. Opening the medial triangle followed by transection of the optic canal dural sheath. Carotid siphon aneurysms can be divided into three groups anatomically; aneurysms of the ophthalmic segment (C2), those of the clinoid segment (C3), and those of the horizontal segment (C4). We present 29 cases of aneurysms arising from the C2 or C2/3 segment, 14 cases arising from the C3 or C3/4 segment, and 11 cases arising from the C4 segment. Anatomic localization of the aneurysms was established preoperatively by angiography and three-dimensional CT imaging. Small aneurysms of the ophthalmic segment projecting infero-medially can be clipped using a contralateral approach via the prechiasmatic root. Aneurysms of the ophthalmic segment projecting superiorly can be clipped following resection of the anterior clinoid process. The clinoid process should be resected intradurally with direct visualization of the aneurysms. Straight side-angled clips are suitable for these aneurysms. Carotid cave aneurysms, which include aneurysms of the ophthalmic segment oriented infero-medially and of the clinoid segment projecting postero-medially, can be clipped using curved fenestrated clips via Dolenc's extradural approach. For accurate clipping, opening of the medial triangle and full mobilization of the IC at the clinoid segment and optic nerve by unroofing the optic canal are required. Aneurysms of the horizontal portion are clipped after full exposure of the artery in the cavernous sinus only when the aneurysms are large and symptomatic. We used the fronto-temporal and Dolenc approaches and applied fenestrated clips to aneurysms oriented or postero-medially and straight or oblique clips to aneurysms projecting antero-laterally. Out of 40 aneurysms which underwent surgical clipping, 37 resulted in good post-operative recovery. There were three deaths secondary to complications of vasospasm and three cases with post-operative visual loss. The classification of these aneurysms and the surgical techniques we employed are discussed in detail.

Carotid Artery Diseases↗
PubMed1995

Epidemiological and clinical features of Budd-Chiari syndrome in Japan.

The Japanese Ministry of Health and Welfare Research Committee on Aberrant Portal Blood Flow carried out an epidemiological survey and clinical study on Budd-Chiari syndrome in 1990. In the primary survey for determining the prevalence of the disease, a questionnaire was sent to all major hospitals throughout Japan and 160 cases seen in 1989 were compiled. More epidemiological details were obtained in 87 of these 160 cases. The number of patients with Budd-Chiari syndrome in this country was estimated to be about 300 (prevalence of 2.4/million) with about 20 new cases occurring every year. In the clinical study, 157 authentic cases of Budd-Chiari syndrome studied in 15 years (1975-89) were analyzed. There were 87 males (average age, 36.4 years) and 70 females (46.5 years), and the average period from the likely onset to the first medical consultation was 6.6 years, suggesting that these patients were mostly chronic cases. The main clinical features were hepatomegaly, leg edema, ascites and venous dilatation over the trunk. Abdominal pain was recorded in only four (2.5%). There were 16 (10.2%) with known identifiable etiologies. Of the patients 93% showed an obstructing lesion of various thickness in the hepatic portion of the inferior vena cava. Only nine (5.7%) had hepatic vein obstruction without caval lesions. Thus, the majority of Budd-Chiari syndrome patients in Japan are idiopathic, having an obstructing lesion in the inferior vena cava. The main causes of 33 deaths (21%) were liver failure, variceal bleeding and hepatocellular carcinoma. Hepatocellular carcinoma occurred in 10 (6.4%) in the 15-year period. However, the incidence of Budd-Chiari syndrome among all cases of hepatocellular carcinoma was less than 1% in the survey made by the Liver Cancer Study Group of Japan.

Adult↗
PubMed1995

Tolosa-Hunt syndrome with unusual clinical courses--two case reports.

Two cases of Tolosa-Hunt syndrome with unusual clinical courses are described. The clinical onset of the first patient was typical, but was unresponsive to steroid hormone treatment. The symptoms resolved spontaneously after 1 year. Computed tomography (CT) and magnetic resonance (MR) imaging revealed enlargement of the affected cavernous sinus, which did not change after the symptoms resolved. The clinical presentation in the second patient included marked pupillary dilatation, a sign which is absent in the classical criteria. CT showed no abnormal findings, but MR imaging revealed a mass located in the medial side of the cavernous sinus extending to the lateral wall, which might have caused the pupillary dilatation. After steroid therapy the symptoms disappeared and MR imaging showed remarkable reduction of the mass in the cavernous sinus. Tolosa-Hunt syndrome usually responds promptly to steroid therapy and rarely manifests marked pupillary dilatation. Such variation in presentation adds to the difficulties in diagnosis and treatment of this disease of unknown etiology.

Adult↗
PubMed1995

Intracerebral infiltration by monoclonal plasmacytoid cells in Waldenstrom's macroglobulinemia--case report.

A 68-year-old female presented with Waldenstrom's macroglobulinemia with infiltration into the cerebral parenchyma manifesting as increased confusion, memory loss, and disorientation. She had a past history of Waldenstrom's macroglobulinemia treated 3 years before. Magnetic resonance imaging showed a high intensity area on T2-weighted images in the left frontal lobe extending to the corpus callosum which was well enhanced by gadolinium-diethylenetriaminepenta-acetic acid. Direct infiltration of neoplastic cells was confirmed by biopsy. Immunohistochemical examination showed that mature plasmacytoid cells in the cerebral parenchyma were immunoglobulin M and lambda light chain antigen positive, but immature lymphocytes in Virchow-Robin space were negative. Monoclonal proliferation was confirmed by southern blot analysis. She became symptom free and the size of the lesion was dramatically reduced after 40 Gy irradiation. She showed no evidence of recurrence 3 years after irradiation. As no effective chemotherapy regimen for Bing-Neel syndrome has been established, irradiation is worth considering when neuroimaging suggests intracranial infiltration of neoplastic cells.

Aged↗