PubMed Health⌕ Search

Biomedical subjects

K Kamada

Publications and source records attributed to K Kamada.

At least 55 records · Page 3Linked to original sources
PubMed1998

Motor, somatosensory and auditory cortex localization by fMRI and MEG.

Functional magnetic resonance imaging (fMRI) and magnetoencephalography (MEG) were performed in six subjects during self-paced finger movement performance, tactile somatosensory stimulation and binaural auditory stimulation using identical stimulation paradigms. Both functional imaging modalities localized brain activity in adjacent areas of anatomically correct cortex. The mean distances measured between fMRI activity and the corresponding MEG dipoles were 10.1 mm (motor), 10.7 mm (somatosensory), 13.5 mm (auditory right hemisphere) and 14.3 mm (auditory left hemisphere). The distances found may reflect the correlation between electrophysiological and hemodynamic responses due to the different underlying substrates of neurophysiology measured by fMRI and MEG: BOLD contrast vs neuronal biomagnetic activity.

Adult↗
PubMed1998

Localization analysis of neuronal activities in benign rolandic epilepsy using magnetoencephalography.

Benign epilepsy of childhood with rolandic spikes (BECRS) is an electroclinical syndrome characterized by partial sensorimotor seizures with centrotemporal spikes. We report a detailed localization analysis of spontaneous magnetic brain activities in seven BECRS patients using magnetoencephalography (MEG). All patients had BECRS diagnosis with typical seizures and electroencephalographic findings and five patients had minor psychomotor deficits. MEG was recorded over both parieto-temporal regions using a 2x37-channel biomagnetic system. The collected data were digitally bandpass-filtered (2-6, 14-30, or 1-70 Hz) to analyze slow- and fast-wave magnetic activities and rolandic spikes. Slow-wave activity was increased in four hemispheres of three patients. Increased fast-wave activity was found in all five patients with minor neuropsychological deficits. The presence of increased fast-wave magnetic brain activity appeared to cause functional anomalies in the higher brain function processes. In the spike analysis, the dipoles of rolandic spikes which constantly manifested anterior positivity in direction were concentrated in the superior rolandic region in four cases and the inferior rolandic region in three cases. The localizations of increased slow- and fast-wave activities were identical with those of the spikes. The seizure profiles were frequently characterized by the spike locations. Source localizations of the focal brain activities and rolandic spikes by MEG will contribute to the different diagnosis and pathophysiological elucidation of BECRS.

Adolescent↗
PubMed1998

[Surgical stabilization of multiple rib fractures successfully achieved with the use of long metalic plates].

Surgical stabilization of multiple rib fractures in 5 male patients was successfully achieved with the use of orthopedic A-O metalic plates, which are called reconstruction plates. In each patient, we prevented deformity of the rib cage and flail chest which frequently occurs after multiple rib fractures. Three of these patients received emergency operations because of severe hemopneumothorax and flail chest due to crushing injuries to the chest. They were treated by the standard thoracotomy, hemostasis of intrapleural bleeding, and stabilization of fractured ribs with reconstruction plates, in addition two of the patients underwent a single lobectomy to control the pulmonary hemorrhage. Another two patients were treated with mechanical ventilation and closed-tube thoracotomy following the chest trauma because their thoracic bleeding from drainage tubes was tolerable. But flail chest and respiratory insufficiency did not improve, in spite of positive controlled ventilation as a mode of internal pneumatic stabilization. Then surgical stabilization of the fractured ribs with these plates was carried out ten to twelve days after the accidents in each case. All patients tolerated the surgical procedures well and were successfully removed from the respirator, demonstrating complete stability of the chest wall. The long metal reconstruction plates with many perforations were very useful for the external fixation of segmentary fractured ribs as an external brace. This was because they were long enough to cover the whole length of the fractured ribs and moderately soft enough to be appropriately bent or twisted by hand at the time of operation. Moreover a number of holes in it allowed the suture to pass through the plate and rib, avoiding displacement of the prosthesis. This is the first report which describes the usefulness of orthopedic reconstruction plates for the stabilization of multiple rib fractures.

Adult↗
PubMed1998

Effect of ceramic surface treatments on the bond of four resin luting agents to a ceramic material.

PURPOSE: This study evaluated the effect of various ceramic surface treatments on the shear bond strengths of four resin luting agents to Cerec 2 ceramic material. MATERIAL AND METHODS: Four ceramic surface treatments were performed. All groups were subjected to the control treatment, which was abrasion with No. 600 silicon carbide paper. The other three group treatments were etching with phosphoric acid gel, application of bonding agent containing silane coupler, and application of silane coupling agent after etching with phosphoric acid gel. Cerec 2 ceramic specimens were treated with one of the four methods and then cemented together with each of the four resin luting agents (Super-Bond C&B, Panavia 21, Clapearl, and Vita Cerec Duo Cement). Half of the specimens were stored in water and the other half were thermal cycled before shear bond strength testing. RESULTS: Treatment with the silane coupler improved the shear bond strength compared only with the abrasion with carbide paper (control). When the ceramic material was treated with the silane coupler or the silane coupling agent after etching with phosphoric acid gel, no significant differences in bond strength were noted between water storage and 20,000 thermal cycles for any of the four resin luting agents. After 20,000 thermal cycles, all specimens treated with the silane coupling agent with phosphoric acid gel except those cemented with Super-Bond C&B resin luting agent after etching showed cohesive failures within the ceramic. CONCLUSION: Combined surface treatment of etching with phosphoric acid and application of silane coupling agent provides the highest bond strengths of resin luting agents to Cerec 2 ceramic material after thermal cycling.

Acid Etching, Dental↗
PubMed1998

Metal chloride primers for bonding dentine with tri-n-butylborane-initiated luting agents.

OBJECTIVES: The bonding of resin to dentine is dependent largely on surface modifications. The purpose of the present study was to test the hypothesis that a role of the metal chlorides used as primers is to initiate polymerization of resin at the resin-dentine interface, thereby affecting bond strength. METHODS: Nine primers were evaluated, comprising aqueous 2-hydroxyethyl methacrylate (HEMA) solutions containing AICl3, CeCl3, CoCl2, CuCl2, FeCl3, NiCl2, MgCl2, SnCl2 or ZnCl2, respectively. One of the two luting agents (Super-Bond resin) consisted of methyl methacrylate (MMA), 4-methacryloyloxyethyl trimellitate anhydride (4-META) and tri-n-butylborane (TBB) initiator. The other luting agent (MMA-TBB resin) consisted of MMA and TBB without 4-META. Extracted bovine teeth were ground to expose the dentine, etched with an aqueous solution of 10% phosphoric acid, primed, and then bonded with stainless-steel rods; tensile bond strengths were determined after 1-day immersion in water. Data were analysed by ANOVA and Duncan's new multiple range test (P < 0.05). RESULTS: Four of the metal chlorides (CuCl2, FeCl3, MgCl2 and ZnCl2) enhanced the bond strengths of MMA-TBB resin to dentine. With Super-Bond resin, maximum bond strengths of 15.6 MPa and 19.0 MPa were recorded with primer containing 2.0 x 10(-5) mol g(-1) FeCl3 and 2.0 x 10(-6) mol g(-1) CuCl2, respectively. CONCLUSIONS: Bonding techniques, combining the use of either cupric primer or ferric primer with 10% phosphoric acid etchant may be suitable for application in seating resin-bonded prostheses with TBB-initiated luting materials.

Acid Etching, Dental↗
PubMed1998

Responses to silent Kanji reading of the native Japanese and German in task subtraction magnetoencephalography.

The neuromagnetic activities evoked by semantic processing were localized by magnetoencephalography (MEG). We observed distinct time courses of the activities in native speaking Japanese subjects (Japanese speaker) and German subjects (German speaker) during silent reading of Japanese letters; Kanji and meaningless figures made by deforming the Arabian letters. There were significant differences in amplitude of the activities between Kanji and meaningless figure stimuli. The responses with meaningless figure stimuli were subtracted from those with Kanji stimuli to demonstrate the semantic responses. Earlier responses peaked at about 273.3+/-50. 8 and 245.0+/-23.8 ms (mean+/-S.D.) and were mainly located in the right fusiform gyrus (FuG) in the Japanese and German speakers, respectively. All the Japanese speakers constantly showed additional later responses in the left superior temporal gyrus (STG) and the supramarginal gyrus (SmG) at approximately 616.1+/-105.5 ms, whereas no further activity was observed in the German speakers who did not know the meaning of each Kanji. Because the later responses in the STG and SmG in the Japanese speakers were only observed in their dominant hemisphere, we believe the source of these responses to be part of the neural basis of Kanji semantic processing. The task subtraction MEG analysis could be a powerful method to discriminate distinct responses and visualize the neural networks involved in semantic processing.

Adult↗
PubMed1998

Application of RT-PCR designed from the sequence of the local SRSV strain to the screening in viral gastroenteritis outbreaks.

The Yuri strain of small round structured virus (SRSV) was cloned from a fecal specimen in which virus particles were observed by electron microscopy. The most common RT-PCR protocol in Japan, however, using 35/36 and NV81/NV82/SM82 nested primer pairs, could not detect the SRSV genome in this specimen. Nucleotide and amino acid sequence analysis revealed that the Yuri strain is genetically close to the genotype II of SRSV. A novel procedure using primer sets designed from the nucleotide sequence of the Yuri strain was applied to the screening of 119 stool samples obtained from subjects with sporadic diarrhea and 46 samples obtained during seven foodborne gastroenteritis outbreaks. Using this novel procedure, PCR bands were detected in 44% and 52% of the samples, respectively. These detection rates were approximately twice those obtained with the 35/36 and NV81/NV82/SM82 nested primers. In particular, more than 40% of positive samples could be detected by using only the Yuri primer sets. Furthermore, three improvements were made in the RNA preparation, cDNA synthesis, and amplification steps to save materials and time. The background, or extra bands, in the amplification reaction resulting from DNA in the fecal specimens was completely removed by DNase I treatment just before cDNA synthesis. Random nonamers were used as universal primers in the reverse transcription. No difference in sensitivity or specificity was noted in the final results when either random nonamers or specific primers were used. The use of a preamplification step under low stringent conditions before standard amplification under highly stringent conditions compensated for any mismatched bases in the primers with respect to the target sequences. Thus our novel procedure using Yuri primer sets may be useful for the screening of SRSV in the recent SRSV outbreaks in Japan.

Amino Acid Sequence↗
PubMed1998

[Correlation of pathological features of surgically excised choroidal neovascular membranes with age-related macular degeneration and indocyanine green videoangiographic findings].

We surgically excised subfoveal neovascular membranes from eight patients with age-related macular degeneration. The correlation of the histopathological features of choroidal neovascularization and preoperative indocyanine green (ICG) videoangiographic findings were studied. Neovascular membranes which demonstrated hyperfluorescence at an early phase of ICG videoangiography had many vascular channels and a large lumen without enclosure of retinal pigment epithelium (RPE). Fibrovascular tissues contained small vessels with fibrotic stroma that showed hyperfluorescence only at a late phase of ICG videoangiography. In contrast, the membrane which showed hypofluorescence of ICG videoangiography was composed of paucivascular fibrotic tissue covered extensively with RPE. Moreover, newly formed vessels with proliferative endothelium could be observed in the neovascular membranes that showed weak fluorescence or hypofluorescence. These results could provide a morphological basis for the interpretation of ICG videoangiographic features of choroidal neovascularization. It also may be useful in planning the treatment for subfoveal neovascular membranes.

Aged↗
PubMed1998

[A case of retroperitoneal malignant lymphoma successfully treated by chemotherapy].

A 71-year-old woman was admitted to our hospital with the complaint of lower abdominal pain. CT scan revealed a huge retroperitoneal mass. On laparotomy the tumor was found to have extensively invaded the retroperitoneum, and an incisional biopsy was performed. Histopathological diagnosis of the biopsied specimen demonstrated diffuse malignant lymphoma of the pleomorphic type. Six cycles of CHOP chemotherapy were very effective for complete remission. Our review of 18 cases in the Japanese literature showed that chemotherapy and radiotherapy were effective for retroperitoneal malignant lymphoma, so due care must be taken in opting for surgery.

Aged↗
PubMed1997

Functional and metabolic analysis of cerebral ischemia using magnetoencephalography and proton magnetic resonance spectroscopy.

The details of the relationship between brain function and metabolism in brain infarcts have not been studied. Using magnetoencephalography (MEG) and proton magnetic resonance spectroscopic imaging (1H MRSI), we localized sources of abnormal magnetic activities in ischemic brain regions and biochemical changes in suspected lesions showing pathological characteristics. Twelve patients with ischemic stroke were examined and the results of MEG and 1H MRSI were superimposed onto the corresponding MR images. The signal intensities of N-acetyl (NA) and lactate (Lac) were measured in the lesions with highly concentrated dipoles of slow wave activity. Eleven of 12 cases had increased slow wave activity in the cortical areas adjacent to the infarcts; 1 case was excluded because the infarct was too small (<1 cm in diameter). The signal intensity of NA in the regions with the highest slow wave activity was significantly reduced and was well correlated with the dipole density of slow waves. Though Lac was mildly accumulated in the lesions, the Lac level had no correlation with slow wave magnetic activity. The remaining and metabolically active cortical tissue showing NA signal produced the abnormal slow wave activity under lactic acidosis (mild accumulation of Lac).

Adult↗
PubMed1997

Metabolic and neurological patterns in chronic cerebral infarction: a single-voxel 1H-MR spectroscopy study.

The details of brain metabolism in chronic cerebral infarcts have not been clarified. Using proton MR spectroscopy (1H-MRS) at 1.5 T, we measured biochemical changes in 16 patients with large infarcts involving the motor cortex in the chronic phase (median 293.9 days) and related the findings to clinical data. Localised spectra were obtained using point-resolved spectroscopy, with an echo time of 270 ms. Regions of interest were placed on the frontal lobe, including the precentral gyrus and central sulcus. Motor function was assessed by the manual muscle power test at the time of the 1H-MRS study. Only three patients with severe paresis had no signal in the lesions and a lactate signal was obtained in 13 cases. N-acetyl aspartate (NAA) was observed in 4 cases with recanalisation of an occluded vessel. Motor function correlated strongly with the NAA/choline-containing compounds (Cho) ratio (P < 0.01) and lactate/Cho ratio (P < 0.01). We found various metabolic patterns, reflecting residual neurological function.

Adult↗
PubMed1997

Differentiation of cerebral radiation necrosis from tumor recurrence by proton magnetic resonance spectroscopy.

Proton magnetic resonance spectroscopy (1H MRS) was evaluated for distinguishing between radiation necrosis and recurrent glioma in 11 patients after high-dose radiotherapy. Six patients had a histological diagnosis of recurrent glioma. Four patients had a histological diagnosis of radiation necrosis and one had a clinical course consistent with the diagnosis of radiation necrosis. 1H MRS showed cases of radiation necrosis had two characteristic 1H MRS patterns: markedly increased lactate/creatine and phosphocreatine (Cr) ratio and decreased choline-containing compounds/Cr ratio compared to that of recurrent glioma; or all the major metabolites were completely diminished. The N-acetyl aspartate signal was not helpful for differential diagnosis. 1H MRS is a potentially useful method for differentiating tumor recurrence from radiation necrosis in patients treated for malignant glioma.

Adult↗
PubMed1997

Intraorbital subperiosteal hematoma due to paranasal mucocele--case report.

A 68-year-old female was admitted with a rare intraorbital subperiosteal hematoma manifesting as sudden orbital pain, progressive blepharoptosis, and diplopia. Computed tomography showed a biconvex high density mass in the superomedial part of the left orbit, which was recognized to be a subperiosteal hematoma intraoperatively. The eroded orbital roof between the frontal sinus and orbit was a result of mechanical compression by the mucocele. Infection extending into the orbit was important in causing the hemorrhage.

Aged↗
PubMed1997

[Ruptured traumatic aneurysms of the peripheral anterior cerebral artery: study of delayed hemorrhage after closed head injury].

We report three cases of ruptured traumatic aneurysms of the peripheral anterior cerebral artery after closed head injury. These cases were all young men with closed head injury due to traffic accidents. Consciousness level on admission was coma in all three cases. Case 1 was a 19-year-old man with interhemispheric hematoma on initial CT, then 7 days later his consciousness cleared. However, 14 days later he suddenly lapsed into a deep coma with a severe frontal hemorrhage. Case 2 was a 13-year-old boy. Plain skull films demonstrated a frontal depressed fracture, but CT scan showed no bleeding. Four days later his consciousness cleared but 11 days after trauma, he lapsed into a deep coma with a frontal hemorrhage. Case 3 was a 22-year-old man. Initial CT showed a slight ventricular hemorrhage. Fourteen days later, his consciousness had almost cleared, but then he lapsed into a deep coma with a large frontal hemorrhage 11 weeks after the trauma. These patients all died within a few days after intracranial bleeding. All patients underwent cerebral angiography but none of them showed filling defect. Autopsy was performed and ruptured aneurysms were found on the distal anterior cerebral artery that had no relation to the branch of bifurcation. Histological examination demonstrated a lack of elastic lamina and media in all of these three cases, so each of them was a victim of so-called false aneurysm. Twenty reported cases of ruptured traumatic aneurysms of the peripheral cerebral artery with delayed hemorrhage after closed head injury were reviewed. Factors in the traumatic aneurysm showed no relation to the duration of disturbed consciousness. Within one month, delayed hemorrhage due to ruptured traumatic aneurysm occurred. None of the delayed hemorrhages involved subarachnoid hemorrhage. Subdural hematoma was seen in the distal middle cerebral artery and frontal hemorrhage was found in the distal anterior cerebral artery. We consider that frontal hemorrhage is a predictive finding for the type of delayed hemorrhage due to traumatic aneurysm in the distal anterior cerebral artery.

Accidents, Traffic↗
PubMed1997

[Transfusion of autologous deposited blood in support of surgery for cerebral aneurysm evaluated by screening for occult intracranial disease].

Preoperatively donated autologous blood was transfused during surgery of an unruptured cerebral aneurysm in a 63-year-old banker to avoid allogeneic blood exposure. The aneurysm in this case was evaluated by noninvasive screening for occult intracranial disease. The transfusion was based on the Red Cross Blood Transfusion Service autologous donor programme for regional hospitals. Preoperative autologous blood donation has continued to grow to reduce risks such as infectious disease transmission and post-transfusion graft-versus-host disease. It is an alternative transfusion practice that should become a standard of care for elective neurosurgery especially in preventive medicine.

Blood Transfusion, Autologous↗
PubMed1997

[Wide resection and reconstruction of chest wall: usefulness of A-O metal plate].

A 53-year-old male was admitted to our department with a chest tumor due to infiltration of lung cancer. Right upper lobectomy and a wide en bloc excision of the right upper chest wall were performed, including the 2nd, 3rd, 4th, and 5th ribs with upper lobectomy of right lung. The defect was replaced with three A-O metal plates, which joined both stumps of the ribs, from the third to the fifth rib. These metal plates were very useful because it was easy to bent and twist them to fit the defect in operation. And curved metal plates preserved a cone from of chest cage. Postoperative course was favourable without mechanical ventilation and wound infection.

Carcinoma, Squamous Cell↗