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Biomedical subjects

T Maehara

Publications and source records attributed to T Maehara.

At least 37 records · Page 2Linked to original sources
PubMed2001

Surgical outcome of corpus callosotomy in patients with drop attacks.

PURPOSE: We examined presurgical factors that independently influence surgical outcome after corpus callosotomy. For adequate measurement of the surgical outcome, we analyzed seizure outcome of drop attacks, postoperative overall daily function, and family satisfaction. METHODS: At least 2 years after callosotomy (mean, 40.0 months), we retrospectively investigated 52 patients with drop attacks. As presurgical factors, we analyzed the age at surgery, age at seizure onset, age at drop attack onset, sex, hemiparesis, severe mental retardation, EEG abnormality, MRI abnormality, and extent of callosal section (total or partial callosotomy). Stepwise logistic regression was used for analysis. RESULTS: Satisfactory outcome (seizure cessation or >90% seizure reduction) was achieved in 85% of patients with drop attacks, 32% of those with generalized tonic seizures, and 31% of those with generalized tonic-clonic seizures. The families assessed the overall daily function as improved in 62% of patients, unchanged in 23%, and impaired in 15%. Family satisfaction with callosotomy was achieved in 83% of patients (definitely satisfied, 39%, somewhat satisfied, 44%). Total callosotomy is independently predictive of satisfactory reduction of drop attacks (p = 0.013). A younger age is independently predictive of improvement of overall daily function (impaired and improved: p = 0.004) and family satisfaction (unsatisfied and somewhat satisfied, p = 0.018; unsatisfied and definitely satisfied, p = 0.0006). CONCLUSIONS: In the present study, we found that total callosotomy is more effective for treatment of drop attacks than partial callosotomy and that children receive more benefit than adults after callosotomy.

Adolescent↗
PubMed2001

Experimental evaluation of photocrosslinkable chitosan as a biologic adhesive with surgical applications.

BACKGROUND: In various surgical cases, effective tissue adhesives are required for both hemostasis (eg, intraoperative bleeding) and air sealing (eg, thoracic surgery). We have designed a chitosan molecule (Az-CH-LA) that can be photocrosslinked by ultraviolet (UV) light irradiation, thereby forming a hydrogel. The purpose of this work was to evaluate the effectiveness and safety of the photocrosslinkable chitosan hydrogel as an adhesive with surgical applications. METHODS: The sealing ability of the chitosan hydrogel, determined as a bursting pressure, was assessed with removed thoracic aorta, trachea, and lung of farm pigs and in a rabbit model. The carotid artery and lung of rabbits were punctured with a needle, and the chitosan hydrogel was applied to, respectively, stop the bleeding and the air leakage. In vivo chitosan degradability and biologic responses were histologically assessed in animal models. RESULTS: The bursting pressure of chitosan hydrogel (30 mg/mL) and fibrin glue, respectively, was 225 +/- 25 mm Hg (mean +/- SD) and 80 +/- 20 mm Hg in the thoracic aorta; 77 +/- 29 mm Hg and 48 +/- 21 mm Hg in the trachea; and in the lung, 51 +/- 11 mm Hg (chitosan hydrogel), 62 +/- 4 mm Hg (fibrin glue, rubbing method), and 12 +/- 2 mm Hg (fibrin glue, layer method). The sealing ability of the chitosan hydrogel was stronger than that of fibrin glue. All rabbits with a carotid artery (n = 8) or lung (n = 8) that was punctured with a needle and then sealed with chitosan hydrogel survived the 1-month observation period without any bleeding or air leakage from the puncture sites. Histologic examinations demonstrated that 30 days after application, a fraction of the chitosan hydrogel was phagocytosed by macrophages, had partially degraded, and had induced the formation of fibrous tissues around the hydrogel. CONCLUSIONS: A newly developed photocrosslinkable chitosan has demonstrated strong sealing ability and a great potential for use as an adhesive in surgical operations.

Animals↗
PubMed2001

Effect of multiple subpial transection on motor cortical excitability in cortical dysgenesis.

We report here a 12-year-old patient with unilateral cortical dysgenesis and intractable simple partial seizure in his left arm, who underwent multiple subpial transection (MST) in the right cerebral cortex including the primary motor cortex. We investigated motor cortical excitability using multimodal transcranial magnetic stimulation (TMS) before and 1 month after MST, in which surgical cortical incisions were made with strokes 5 mm apart and 4 mm deep. Preoperative TMS studies showed hyperexcitability in the affected motor cortex as abnormally prolonged muscle responses to TMS with a wide cortical motor map, which were markedly reduced following the operation. The preoperative motor evoked potentials were large and polyphasic, and consisted of early and late components. The late component was completely abolished after MST, suggesting that this component might be due to activation of the corticospinal tract neurones by long recurrent axon branches of dysplastic excitatory pyramidal neurones, which were cut by MST, or by delayed, polysynaptic intracortical conduction with marked temporal dispersion. Intracortical inhibition in the affected motor cortex was also disrupted preoperatively and improved after MST. Postoperative recruitment order of muscle responses to TMS was bilaterally symmetrical, indicating that MST did not interfere with the function of the corticospinal tract neurones. The patient showed fair motor recovery and good seizure control after the operation. These results of TMS studies demonstrated the remarkable effectiveness of MST not only on intractable seizure but also on abnormal motor cortical organization and hyperexcitability in cortical dysgenesis.

Cerebral Cortex↗
PubMed2001

DNA topology on an increase in positive writhing number of DNA: conformation changes in the time course of cis-diamminedichloroplatinum(II)-DNA adducts.

We show that the topological significance of the gel mobility of cis-diamminedichloroplatinum(II) (DDP)-closed circular DNA (ccDNA) adducts decreases with reaction time, until a point at which it joins relaxed DNA, and that the mobility of the adducts increases again. There is no relationship between the relative length of the adducts and the gel mobility. Although the significance of the decrease of gel mobility is due to the unwinding of cis-DDP-DNA (or trans-DDP-DNA) adducts, the conformational significance of the subsequent increase in mobility is unclear. To elucidate the conformational significance for unwinding of the adducts, we measured the writhing number (Wk) of the adducts using electron microscopy and analyzed the topological states of cis-DDP (or trans-DDP) adducts based on the White rule, Lk=Wk+Tk. Where, Lk and Tk represent the linking and twisting number in the ring, respectively. From the data, we found that the Wk of cis-DDP-ccDNA adducts in comparison with trans-DDP-ccDNA adducts increases from a negative to a positive number with time. This suggests that cis-DDP plays a role in the change of the topological state of ccDNA. In the abstraction of platinum from the adducts with CN- ion, the differences in both topological states may explain why Pt in trans-DDP is abstracted more easily than in cis-DDP. To explain the abstraction of Pt ion, we also discuss the findings based on the thermodynamic cycle in a intermolecular crosslink model Pt(NH3)2(guanine)2(2+)-->Pt(CN)4(2-) using the Pt parametrized PM3 method.

Algorithms↗
PubMed2001

Apoptosis of Neuro2a cells induced by lysosphingolipids with naturally occurring stereochemical configurations.

Lysosphingolipids, which lack the fatty acid moiety of sphingolipids, are known to be accumulated in some variants of sphingolipid storage diseases. Here, we report that lysosphingolipids with naturally occurring stereochemical configurations induce apoptosis in mouse neuroblastoma Neuro2a cells. The intracellular dehydrogenase activity and [3H]thymidine incorporation of Neuro2a cells were strongly suppressed by the addition of lysosphingolipids in a dose-dependent manner, whereas the parental sphingolipids had no effect. Intranucleosomal DNA fragmentation, chromatin condensation, and phosphatidylserine externalization, which are typical features of apoptosis, were observed when the cells were cultured with 40-80 microM of lysosphingolipids for 24-48 h in the presence of 5% fetal calf serum. Activation of caspase-3-like enzyme occurred after addition of lysosphingolipids followed by incubation at 37 degrees C for 24 h. The addition of an inhibitor of caspases, ZVAD-fmk, to the Neuro2a cell culture completely inhibited the elevation of caspase-3 activity but not the DNA fragmentation. These results may indicate that a caspase-3 independent signaling pathway is involved in the lysosphingolipid-induced apoptosis and suggest that accumulation of lysosphingolipids, but not parental sphingolipids, triggers the apoptotic cascade in neuronal cells of patients with sphingolipidoses.

Amidohydrolases↗
PubMed2000

Enhanced motor cortical excitability in the unaffected hemisphere after hemispherectomy.

We evaluated motor cortical excitability of the unaffected hemisphere in three patients with intractable epilepsy who underwent hemispherectomy, using transcranial magnetic stimulation (TMS) and PET. TMS of the unaffected hemisphere evoked motor responses not only in the contralateral muscles but also in the ipsilateral ones in all the patients. A PET study in one patient showed activation of the unaffected motor cortex by movement of either arm. All of these responses were enhanced after the hemispherectomy, probably due to motor cortical disinhibition by transection of the corpus callosum. The PET study also showed postoperative activation of the premotor area of the unaffected hemisphere. These phenomena indicate posthemispherectomy neuroplastic reorganization leading to preservation of the motor function after the operation.

Adult↗
PubMed2000

Suppression of gamma activity in the human medial temporal lobe by sevoflurane anesthesia.

We have reported the presence of continuous gamma (30-150 Hz) activity in the human medial temporal lobe (MTL). Since the MTL is involved in learning and memory, we speculated that MTL gamma activity is related to such higher brain functions. It is thus of interest to learn how this activity changes during different states of consciousness. In this study, we recorded electrocorticographic (ECoG) activity directly from the surface of the MTL after various doses of sevoflurane anesthesia. Five epileptic patients underwent electrode placement operations in which electrodes were attached to the surfaces of the MTL and the basal temporal lobe (BTL). Immediately following the operation ECoG was recorded from each patient under four concentrations of sevoflurane anesthesia (1.5, 2.0, 2.5 and 3.0%). Fast Fourier Transform (FFT) analysis was performed on the MTL ECoGs. Under the lowest sevoflurane concentration, MTL gamma activity was observed in all patients. However, gamma activity was progressively suppressed by increased concentrations of sevoflurane, in a dose-dependent manner. Sevoflurane has been known to reduce neuronal excitability in the rat hippocampus in vitro, probably by changing GABAergic inhibition. The reduction of MTL gamma in the present study may be the result of such a mechanism. Although memory function was not tested in this study, the amount of MTL gamma activity may be related to residual memory function during anesthesia.

Adolescent↗
PubMed2000

Multiple myeloma presenting high fever and high serum levels of lactic dehydrogenase, CRP, and interleukin-6.

Two myeloma patients presented high fever with no signs or data indicating infection at diagnosis or relapse. Both patients had plasmablastic myeloma, and serum levels of lactic dehydrogenase (LDH) and CRP were extremely high. Plasmablastic morphology, high LDH, and CRP were recognized as poor prognostic factors, indicating a fulminant phase of multiple myeloma. Interleukin-6 (IL-6) was only high in measured cytokines. We proposed that IL-6 caused high fever and induced the fulminant phase in these 2 cases.

C-Reactive Protein↗
PubMed2000

Usefulness of cerebral blood flow (CBF) measurements to predict the functional outcome for rehabilitation in patients with cerebrovascular disease (CVD).

PURPOSE: The objectives of this study were to (1) elucidate the relationship between the mean CBF in the whole brain (Av.mCBF) before rehabilitation of CVD patients and the BI score before and after rehabilitation, (2) determine whether the efficacy of rehabilitation can be predicted by measurement of the Av.mCBF, and (3) investigate what part of the brain was most important to improving the BI score. MATERIALS AND METHODS: The Av.mCBFs in 160 patients with CVD were calculated by Patlak plots with 99mTc-HMPAO before rehabilitation, and we determined the BI score before and after rehabilitation. Based on the BI scores before and after rehabilitation, patients were divided into four groups: Group A, BI = 100; Group B, 80 < or = BI < or = 99; Group C, 60 < or = BI < or = 79; Group D, 0 < or = BI < or = 59. We evaluated the relationship between the Av.mCBF and BI score before and after rehabilitation. RESULTS: The Av.mCBF before rehabilitation showed a tendency to be more correlated with the BI score after rehabilitation (r = 0.414, p < 0.0001) than before rehabilitation (r = 0.272, p = 0.0006). After rehabilitation, there was a tendency for the Av.mCBF value to increase in direct proportion to the BI score of the group: it was highest in Group A and lowest in Group D. The strongest correlation was found between the frontal lobe regional CBF before rehabilitation and the BI score after rehabilitation (r = 0.343, p < 0.0001). CONCLUSIONS: Measurement of the Av.mCBF before rehabilitation of CVD patients will permit prediction of the efficacy of rehabilitation. Also the regional CBF of the frontal lobe is most important for improving the BI score.

Adolescent↗
PubMed2000

Presence of human herpesvirus 6 and herpes simplex virus detected by polymerase chain reaction in surgical tissue from temporal lobe epileptic patients.

We investigated the presence of human herpesvirus 6 (HHV-6) and herpes simplex virus (HSV) in surgical tissue from temporal lobe epileptic patients. A total of 17 cases were studied, including eight males and nine females. The mean age was 24.9 +/- 11.1 years and the mean age of onset was 11.1 +/- 5.4 years. Five patients were diagnosed as encephalitis/meningitis and another three had a history of suspected encephalitis/meningitis, but no patient showed any obvious neurological symptom or mental handicap. Mesial and lateral temporal tissues were examined by polymerase chain reaction. Among six patients positive for HHV-6 (35%), the mesial temporal lobe was positive in four and the lateral temporal lobe was positive in three. Herpes simplex virus was positive in only one patient. Three of the six patients positive for HHV-6 did not show any apparent causes. Mild encephalitis/meningitis induced by HHV-6, a condition sometimes not recognized as encephalitis/meningitis, may be one of the most frequent causes of temporal lobe epilepsy.

Adult↗
PubMed2000

Vacuum assisted cardiopulmonary bypass in minimally invasive cardiac surgery: its feasibility and effects on hemolysis.

The present study describes a cardiopulmonary bypass (CPB) technique that incorporates vacuum assisted venous drainage and arterial return using a centrifugal pump in minimally invasive cardiac surgery (MICS). The technique was performed on 40 patients scheduled to undergo MICS. The proposed CPB technique enables a good operative field to be obtained even through a limited incision through the use of peripheral cannulation using small cannulae. Vacuum pressure was applied to the venous reservoir (-43 +/- 14 mm Hg) to maintain adequate CPB flow (>2.4 L x min-1 x M-2). The effects of CPB on hemolysis were subsequently compared between patients who underwent the proposed procedure (MICS group; n = 6) and a control group who underwent coronary arterial bypass grafting (CABG group; n = 6) with conventional CPB. Plasma free hemoglobin (FHb) increased and plasma haptoglobin (Hp) decreased during CPB in both groups, with no significant difference between the groups. By the next day, FHb had returned to pre-CPB levels whereas Hp remained lower in both groups. Again, these values did not differ significantly between groups. Thus, we conclude that the proposed CPB technique is useful in MICS with acceptable effects on hemolysis.

Analysis of Variance↗
PubMed2000

Adult Still's disease as a paraneoplastic manifestation of breast cancer.

We treated a patient who developed symptoms and findings indistinguishable from those of adult Still's disease as a manifestation of metastatic breast cancer 7 years after treatment for a stage 1 tumor. Although clinical features fulfilled diagnostic criteria for adult Still's disease, examination of a bone marrow biopsy specimen indicated that the apparent adult Still's disease was a paraneoplastic manifestation associated with diffuse marrow infiltration by breast cancer. The fever and polyarthralgia resolved with administration of prednisolone, and antiestrogen therapy with tamoxifen citrate was also started.

Breast Neoplasms↗
PubMed2000

Modification of peri-insular hemispherotomy and surgical results.

OBJECTIVE: We modified the peri-insular hemispherotomy technique devised by Villemure and Mascott. Our modified technique and the surgical results obtained with this method are presented. METHODS: The frontoparietal operculum is resected, and the resection cavity is connected with the lateral ventricle. Through this cavity, a transventricular corpus callosotomy and resection of the medial temporal structures are performed. RESULTS: This technique was used for 34 patients, with satisfactory surgical results. Cerebrospinal fluid shunt placement was necessary for five patients, and incomplete callosal sectioning was postoperatively detected in three cases. CONCLUSION: Our modification of the peri-insular hemispherotomy can be safely and effectively used to treat epilepsy caused by hemispheric lesions, even in cases without ventricular dilation.

Adolescent↗
PubMed2000

Cortical dysplasia with ossification.

We present the first case of cortical dysplasia with extensive intracerebral ossification. An eight-year-old epilepsy patient with a calcified lesion was successfully treated by surgical intervention. Pathological examination revealed a number of bizarre dysplastic cells in the whole lesion, which consisted of an epileptogenic cerebral cortex and a nonepileptogenic hamartomatous lesion with adipose tissue, vascular tissue, calcification, and ossification. The patient was diagnosed as having cortical dysplasia with ossification. Our findings support the notion that cortical dysplasia has a multipotentiality of cellular differentiation, including various hamartomatous tissues. We suggest that cortical dysplasia should be considered as a potential cause for epileptogenicity of a hamartomatous lesion even when magnetic resonance imaging (MRI) fails to disclose cortical dysplasia.

Brain Diseases↗
PubMed2000

Neuronal disconnection for the surgical treatment of pediatric epilepsy.

The surgical methods and results of disconnective surgery for pediatric epilepsy were retrospectively analyzed. The techniques of neuronal disconnection included multiple subpial resection (MST), corpus callosotomy. and functional hemispherectomy by disconnection. Of 158 total pediatric operations, disconnective techniques were employed in more than 60% of the cases. MST was applied when the epileptic focus was located in unresectable cortices such as speech or motor areas. MST was also instrumental when the epileptogenic zone was extensive and was widely disseminated, as is often observed in cases of neocortical epilepsy. Of 25 patients who underwent MST, surgical outcomes after > 1 year follow-up showed Engel Class I or II in 10 cases, Class III in 12, and Class IV in 3. No mortality or morbidity was encountered during surgery or postoperatively. Corpus callosotomy was applied to cases of disabling generalized seizures and showed a marked effect in alleviating potentially injurious drop attacks. Of 34 patients with drop attacks, 29 became free from this type of seizure, 4 had infrequent attacks, and only 1 showed no beneficial effect. Postoperative improvement of cognition and speech was recognized in 77% of the cases. We developed a new method of functional hemispherectomy by fiber disconnection and applied this less invasive technique to 23 cases of hemispheric lesions. Of the 17 cases with > 1 year follow-up, 13 were in Class I or II, and 3 in Class III, and 2 in Class IV. Development partially normalized in infants with good seizure outcomes.

Adolescent↗