Biomedical subjects
T Yoshimine
Publications and source records attributed to T Yoshimine.
[A case of ruptured aneurysm in a patient over 90 years of age, successfully treated by clipping with the use of a one-way ball valve for cisternal drainage].
The authors report a case of ruptured aneurysm in a patient in her 90's who was treated by clipping and returned to her independent life after discharge. A 91-year-old woman with a diagnosis of SAH of Hunt & Kosnik Grade III was treated using a conventional clipping operation with cisternal drainage. The cisternal drainage was assembled as a closed system using a newly developed one-way ball valve to regulate the CSF outflow. With this system the patient was able to take any posture and do any movement she wished, not being obligned to stay in bed. Early postoperative rehabilitation was able to be started to prevent pneumonia and muscular atrophy. The drainage was stopped on the 27th postoperative day when the CSF became clear. During the period of drainage, neither valve obstruction nor meningitis was noted. This valve system allows patients under cisternal drainage to move freely. It would be useful, especially when dealing with the elderly, to prevent unwanted complications often caused by postoperative restraint imposed by confinement to bed.
BDNF atelocollagen mini-pellet accelerates facial nerve regeneration.
We investigated the effect of BDNF mini-pellet on the GAP-43 mRNA expression and functional status of facial nerve in a rat model of facial nerve transection and immediate repair. The facial function started to recover at 17 days in the placebo group and 14 days in the BDNF group. BDNF group had shorter period of increased GAP-43 mRNA expression than the placebo group. Topically applied BDNF may accelerate the facial nerve regeneration.
Kainic acid-induced seizure upregulates Na(+)/myo-inositol cotransporter mRNA in rat brain.
A major organic osmolyte, myo-inositol protects cells from perturbing effects of high intracellular concentrations of electrolytes. Myo-inositol is accumulated into cells through Na(+)/myo-inositol cotransporter (SMIT). In order to investigate the regulation of SMIT in generalized seizure, we employed Northern blot analysis and in situ hybridization to study the changes in SMIT mRNA expression in kainic acid-injected rats. Northern blot analysis demonstrated that SMIT mRNA began to increase in the brain 2 h after onset of seizure, and peaked at 12 h. In situ hybridization revealed rapid increase of SMIT mRNA (2 h of seizure) in the CA3 hippocampal pyramidal cells and in the dentate granular cells. Then, at 4-6 h SMIT mRNA expression was observed in the other limbic structure such as amygdala and piriform cortex. Finally, in neocortex and in CA1 pyramidal cells, SMIT mRNA was slowly increased and peaked at 12 h. Microautoradiogram demonstrated that cells expressed SMIT mRNA were mainly neurons. These results suggest that SMIT mRNA is upregulated by kainic acid-induced seizure primarily in structures involved in seizure activity.
Medial prefrontal cortex generates frontal midline theta rhythm.
Frontal midline theta rhythm (Fm theta) is a distinct theta activity of EEG in the frontal midline area that appears during concentrated performance of mental tasks in normal subjects and reflects focused attentional processing. To tomographically visualize the source current density distributions of Fm theta, we recorded Fm theta by using a 64-channel whole-head MEG system from four healthy subjects, and applied a new analysis method, synthetic aperture magnetometry (SAM), an adaptive beam forming method. Fm theta was observed in the MEG signals over the bilateral frontal regions. SAM analysis showed bilateral medial prefrontal cortices, including anterior cingulate cortex, as the source of Fm theta. This result suggests that focused attention is mainly related to medial prefrontal cortex.
Isolation and expression analysis of a novel human homologue of the Drosophila glial cells missing (gcm) gene.
A novel human homologue (GCMB) of the Drosophila glial cells missing gene (dGCM) was isolated using RACE. GCMB contained a gcm motif sequence and a nuclear targeting sequence similar to that of dGCM and mouse GCMb. Homology searches indicated that GCMB was located within chromosome 6p24.2. Transcripts of GCMB were detected by means of RT-PCR in fetal brain, normal adult kidney, 3/3 medulloblastomas, 1/3 gliomas and 4/8 non-neuroepithelial tumor cell lines. Our data suggest that humans have two homologues of gcm like mice and that human gcm genes form a novel family which may function not only during fetal development but also in the postnatal or pathological stage.
Chromosomal aberrations detected by comparative genomic hybridization (CGH) in human astrocytic tumors.
We investigated chromosomal aberrations in 16 patients with astrocytic tumors of various histologic malignancies by comparative genomic hybridization (CGH). The degree of chromosomal loss was shown to be negatively correlated with histologic malignancy. Losses of portions of chromosomes 1p, 19q and 22q were the three chromosomal aberrations observed most frequently. Alterations in multiple chromosomes were observed more frequently in glioblastomas than in astrocytomas or anaplastic astrocytomas (P < 0.001). Primary glioblastomas showed a high frequency of genomic DNA gains (5/7), whereas recurrent glioblastomas from anaplastic astrocytomas did not (0/3). We found CGH to be a powerful tool for surveying DNA alterations in tumors and characterizing the biology of tumors of astrocytic lineage.
Hemangioblastoma of the third ventricle.
A third ventricle tumor, in addition to a recurrent cerebellar hemangioblastoma, was found in a 47-year-old woman on follow-up magnetic resonance imaging (MRI) 5 years after operation of the cerebellar tumor. On MRI, the tumor was hypo- to isointense on T1-weighted images and hyperintense on T2-weighted images compared with the normal gray matter, and was strongly enhanced with gadolinium. The tumor was first treated with fractionated conventional external-beam radiation (5120 cGy in 16 fractions over a 4-week period), resulting in a slight decrease in size of the tumor. For a definite diagnosis and mass reduction, surgery was performed using an interhemispheric translamina terminalis approach, resulting in a partial removal of the tumor due to profuse bleeding. Histological diagnosis was hemangioblastoma. Hemangioblastomas of the third ventricle are extremely rare and have not been specifically discussed. We describe the detailed clinicopathological features of the present case together with the possible explanation for the development of this tumor in this rare location.
Differential regulation of adenine nucleotide translocators by hypertonicity in the brain.
To determine the gene(s) induced by hypertonicity in the brain, we performed a differential display analysis using RNA isolated from isotonic and hypertonic rat astrocytes. One cDNA rapidly up-regulated by hypertonicity was isolated, and the DNA sequence revealed that it was identical to adenine nucleotide translocator (ANT)2. ANT2 protein exchanges intramitochondrial ATP for cytoplasmic ADP. Among three ANT isoforms, only ANT2 mRNA was up-regulated markedly from 1 to 4 h after exposure to hypertonicity. Induction of the mRNA did not require de novo protein synthesis. Furthermore, ADP translocase activity in mitochondria of astrocytes was increased significantly by hypertonicity. To see the localization and regulation of ANT2 mRNA in the brain, we performed in situ hybridization of rat brain after intraperitoneal injection of a high concentration of NaCl. Although there were only weak signals in the control, intense hybridization signals were seen in hypertonic rat whole brain. Microscopic examination showed that ANT2 signals were present in the neurons, as well as glial cells. These results suggest that ANT2 may play a role in brain cells to adapt to the hypertonic environment.
Neuroprotective role of Na+/myo-inositol cotransporter against veratridine cytotoxicity.
Na+/myo-inositol cotransporter has been shown to protect cells from the perturbing effects of hypertonic stress by the accumulation of myo-inositol. Here we report a regulatory mechanism for the cotransporter. Induction of myo-inositol cotransporter mRNA was observed after exposure to veratridine, a voltage-gated sodium channel opener. The veratridine-elicited induction was inhibited when Na+ was eliminated from the bath, although calcium chelation failed to modify the gene expression. Veratridine evoked an accumulation of Na+ in the cells, which paralleled the abundance of the mRNA. These results strongly suggested that an increase in Na+ influx due to sodium channel opening affected transcription of the cotransporter gene. Activity of the myo-inositol cotransporter was also up-regulated after veratridine exposure. To clarify the possible roles of myoinositol accumulation under veratridine exposure, we next examined the neurotoxic effects of veratridine when myo-inositol uptake was blocked. Neither 30 microM veratridine nor 500 microM 2-O,C-methylene myo-inositol, a competitive inhibitor of myo-inositol, elicited apparent cytotoxicity. However, a combination of these agents markedly increased cytotoxicity in culture, suggesting that an adequate amount of myo-inositol was necessary when the cells were stimulated with veratridine.
Combined transfrontal and endonasal endoscopic surgery of epidural abscess following frontal sinusitis. A case report.
A large epidural abscess secondary to frontal sinusitis in a previously healthy 19-year-old man was successfully treated with a small eyebrow incision using combined transfrontal and endonasal endoscopic technique. The abscess was resolved with concomitant pneumatization of the paranasal sinuses. The present case illustrates the promising use of endoscopy in the merging fields of neurosurgery and otorhinolaryngology.
Immunohistochemical study of insulin-like growth factor II (IGF-II) and insulin-like growth factor binding protein-2 (IGFBP-2) in choroid plexus papilloma.
Insulin-like growth factor-II (IGF-II), a mitogen for various kinds of cells, has been shown to be secreted from the choroid plexus in animals. Insulin-like growth factor binding protein-2 (IGFBP-2), one of the six carrier proteins for IGFs, is also thought to be released from the choroid plexus, bind to IGF-II in the cerebrospinal fluid (CSF) and modulate the action of this growth factor. Little is known about the expression and localization of these substances in human choroid plexus and choroid plexus papillomas. The present immunohistochemical study demonstrated all six choroid plexus papillomas were positive for IGF-II, whereas normal choroid plexuses were negative for IGF-II. On the other hand, IGFBP-2 was positive in the endothelium and vascular media in the normal choroid plexus, while it was weakly positive in four and negative in two out of six choroid plexus papillomas. These results suggest that the alterations in the IGF-II/IGFBP-2 axis might be involved in the tumorigenesis of choroid plexus papilloma.
Decrease in N-acetylaspartate without commensurate accumulation of acetate in focal cerebral ischemia in rat.
N-acetylaspartate (NAA) is a plausible marker of neuronal viability which decreases in a variety of neurodestructive conditions. To elucidate the mechanism that leads to NAA decline in two different types of cerebral ischemia in rats, we simultaneously determined cortical concentrations of NAA and its hydrolytic metabolites, aspartate, and acetate by high-resolution 1H-NMR spectroscopy. NAA decreased almost linearly up to 24 h in both decapitation induced global cerebral ischemia, and in ischemic cortices of focal ischemia. Acetate was increased continuously for up to 24 h of global ischemia, while in focal cerebral ischemia it was increased transiently at 6 h. Aspartate did not show any change in global ischemia, while it was decreased in focal ischemia. Although NAA decreased similarly in the brain with global and focal ischemia, temporal changes of two NAA hydrolytic metabolites were different in each type of ischemia. The present results suggest hydrolytic degradation of NAA may be modified alternatively under each pathophysiologic condition.
Visualization of epileptogenic phenomena using cross-correlation analysis: localization of epileptic foci and propagation of epileptiform discharges.
The main objectives of the preoperative evaluation of a patient with medically intractable epileptic seizures are localization of the foci and propagation of the epileptiform discharges. Electrocorticographic (ECoG) data of intractable focal epilepsy were analyzed using an AR model, wavelet analysis, and cross-correlation analysis. In order to derive the time-shifts, the cross correlations of the epileptiform discharges were calculated between electrodes for every unit of time. Further analyses were made by means of a set of contour maps of the time-shifts and sequential two- and three-dimensional visualizations of the time-shift maps in order to localize the epileptic foci and study their propagation process. Two types of foci and propagation were revealed in the results. In the first type, epileptiform discharges were generated at localized focal sites and spread quickly to other sites. In the second type, the foci of epileptiform discharges, which appeared soon after the former bursts, were localized at more than one site, and the discharges tended to spread more slowly. The findings suggest that epileptic phenomena can be caused by at least two kinds of mechanisms in one patient: in the former, the propagation might be mediated through synaptic projections, while in the latter, the extracellular diffusion of an excitatory factor might play an important role. In addition, our newly developed visualization technique for the localization of epileptic foci and the propagation of epileptiform discharges should prove useful in the study of epileptogenesis etiology.
Rapid infusion of high-dose methotrexate resulting in enhanced penetration into cerebrospinal fluid and intensified tumor response in primary central nervous system lymphomas.
OBJECT: Twenty-nine nonimmunocompromised patients with primary central nervous system (CNS) lymphoma were treated with high-dose methotrexate (MTX) therapy followed by irradiation. The authors investigated the correlation of infusion schedules with MTX penetration into cerebrospinal fluid (CSF), tumor response, and survival to develop a regimen that would lead to better clinical results. METHODS: In this study, 100 mg/kg MTX was administered on either a rapid (3-hour) or regular (6-hour) infusion schedule for two or three cycles. Of 28 assessable patients, a complete or partial response was achieved in 15 (93.8%) of 16 who received rapid and in seven (58.3%) of 12 who received regular infusion therapy (p = 0.034). Rapid infusion significantly increased levels of MTX in the CSF (p < 0.001) and resulted in significant tumor volume reduction (p < 0.001). The mean tumor volume after the first, second, and third cycle of rapid infusion therapy was reduced to 34%, 14%, and 9%, respectively, of the initial volume, whereas the corresponding values were 54%, 42%, and 37% for regular infusion. The reduction between the second and third cycle was small and not significant for either schedule. Despite the longer median survival time in patients who underwent rapid MTX infusion and irradiation (> 60 compared with 20 months), the difference in survival was not significant (p = 0.147) because of the small number of patients enrolled. The median survival time was 39.3 months for all assessable patients who received high-dose MTX and radiation therapy, and the median relapse-free survival time was 35.2 months. CONCLUSIONS: Rapid infusion enhanced both MTX penetration into the CSF and tumor response and may improve patient survival. Administration of three or more cycles of therapy should be carefully weighed in terms of cytoreductive benefits.
Application of a rigid endoscope to the microsurgical management of 54 cerebral aneurysms: results in 48 patients.
OBJECT: To enhance visual confirmation of regional anatomy, endoscopy was introduced during microsurgery for cerebral aneurysms. The risks and benefits are analyzed in the present study. METHODS: The endoscopic technique was used during microsurgery for 54 aneurysms in 48 patients. Forty-three aneurysms were located in the anterior circulation and 11 were in the posterior circulation. Thirty-eight aneurysms (70.4%) had not ruptured. All ruptured aneurysms in the present series produced Hunt and Hess Grade I or II subarachnoid hemorrhage. After initial exposure achieved with the aid of a microscope, the rigid endoscope was introduced to confirm the regional anatomy, including the aneurysm neck and adjacent structures. The necks of 43 aneurysms were clipped using microscopic control or simultaneous microscopic/endoscopic control. After clipping, the positions of the clip and nearby structures were inspected using the endoscope. Use of the neuroendoscope provided useful information that further clarified the regional anatomy in 44 cases (81.5%) either before or after neck clipping. In nine cases (16.7%), these details were available only with the use of the endoscope. In five cases (9.3%), the surgeons reapplied the clip on the basis of endoscopic information obtained after the initial clipping. There were two cases in which surgical complications were possibly related to the endoscopic procedures (one patient with asymptomatic cerebral contusion and another with transient oculomotor palsy). CONCLUSIONS: It is the authors' impression that the use of the endoscope in the microsurgical management of cerebral aneurysms enhanced the safety and reliability of the surgery. However, there is a prerequisite for the surgeon to be familiar with this instrumentation and fully prepared for the risks and inconveniences of endoscopic procedures.
[Follow-up of children with early neonatal surgery of fetal hydrocephalus].
This is a retrospective study of patients with surgically treated antenatal diagnosed hydrocephalus. We conducted the study to elucidate the outcomes of the patients, as well as potential pitfalls in their care. A series of 51 patients underwent surgical intervention between 1987 and 1997. All lesions were diagnosed by antenatal ultrasound sonography. After the estimation of their lung maturation, they were delivered in early pregnancy stage and the operation had performed for hydrocephalus. 43 children could be followed-up. To estimate the morphological improvement from radiological examinations objectively, we compared cerebroventricular index (CVI) of pre-operation with that of post-operation. The result was that excellent improvement group was 18 cases, good improvement group was 13 cases, fair improvement group was 8 cases and poor improvement group was 4 cases. In 43 cases, 20 children also had myelomeningocele and in them the improvement of hydrocephalus was that excellent improvement group was 10 cases, good improvement group was 5 cases and fair improvement group was 5 cases. About motor function of 20 children with myelomeningocele, only 5 children were ambulatory with brace. Attending to the rest 23 children without myelomeningocele, 6 children in 8 excellent improvement cases and 6 children in 8 good improvement cases were ambulatory by themselves. But all 7 children belonging to fair and poor improvement groups were unambulatory. We concluded that it was necessary to improve dilated ventricle on the radiological examinations with surgical procedure in order to get better motor function, even semilobar and lobar holoprosencephaly.
[Use of Ommaya CSF reservoir for refractory chronic subdural hematoma].
Ten patients with refractory chronic subdural hematoma were the subjects of this paper. All patients had severe diseases influencing the clinical course of chronic subdural hematoma, such as cerebral infarction, liver cirrhosis, thrombocytopenia, severe parkinsonism, severe heart disease, and spino-cerebellar degeneration. They were first treated in a usual manner; irrigation and drainage of the hematoma cavity. After recurrence of the hematoma, an Ommaya CSF reservoir was put into place and whenever the volume of the hematoma increased the reservoir was punctured. Postoperatively, 7 patients returned to the same conditions as they had before the onset. However, one patient died of myocardial infarction and 2 patients with parkinsonism could not maintain the condition they had before the onset of their disease, resulting in their partially dependent state. Complications were minor bleeding in one patient and an occlusion of the reservoir in another patient. By using this method reoperation was unnecessary, and the patients were able to move early in the post-operative period. This method was suitable for refractory chronic subdural hematoma with severe disease influencing its clinical course.