Biomedical subjects

T Ikata

Publications and source records attributed to T Ikata.

At least 55 records · Page 3Linked to original sources

PubMed1996

Experimental and clinical studies of eicosanoids in cerebrospinal fluid after spinal cord injury.

OBJECTIVE: In an attempt to elucidate a possible role for eicosanoids in the pathogenesis of spinal cord injury (SCI), we measured the concentration of leukotriene (LT) C4, thromboxane B2, and 6-keto-prostaglandin F1 alpha in cerebrospinal fluid in both a canine experimental model and 11 patients with SCIs. METHODS: The eicosanoid concentration in cerebrospinal fluid was measured by radioimmunoassay. Neurological severity was assessed according to the grading system of Frankel et al.. Control samples were obtained from 20 patients without SCIs. RESULTS: In the canine model, a significant increase in all eicosanoid levels was found on Days 1 to 7, which subsequently returned to the control levels. In the clinical study, the highest mean (+/- standard error of the mean) concentrations of LTC4, thromboxane B2, and 6-keto-prostaglandin F1 alpha in the acute stage of SCI were 95.9 +/- 10.7, 175.2 +/- 38.2, and 167.5 +/- 39.9 pg/ml, respectively. These concentrations were five to nine times higher than control levels. There was a good correlation between cerebrospinal fluid LTC4 levels and the neurological severity. The time-dependent change in LTC4 concentrations in seven patients with SCIs was similar to that observed in the canine model. In addition, the highest mean concentrations of the eicosanoids measured in patients with complete paralysis was also similar to those of the canine model. The eicosanoid concentrations in five patients with SCI were measured more than 6 months after the onset of injury. Although all eicosanoid levels had elevated in the acute stage of injury, they were not elevated and showed the same levels as the controls at the chronic stage. CONCLUSION: The findings suggest that enhanced arachidonate metabolism occurs in humans and support the evidence from animal experiments that emphasizes the importance of eicosanoids in the secondary processes mediating ischemia and edema.

6-Ketoprostaglandin F1 alpha↗

PubMed1996

Fibrosarcoma of the toe: a destructive lesion of the distal phalanx.

A rare case of well differentiated fibrosarcoma occurring in the left second toe is described in a 12-year-old boy who presented with a destructive lesion that had almost totally destroyed the distal phalanx, except for the epiphysis. Amputated specimens showed microscopic evidence of proliferation of uniform spindle cells arranged in both fascicles and a characteristic herringbone pattern with a small number of mitotic figures. This tumor did not show any specific immunoreactivity except for vimentin and had basic ultrastructural characteristics of fibroblasts and myofibroblasts. The tumor was treated by amputation at the middle phalanx level and had not recurred 3 years later. From the presenting radiographic features, some benign neoplasms and reactive lesions were considered in the differential diagnosis. Only results from the pathologic examination were useful in reaching a correct diagnosis.

Amputation, Surgical↗

PubMed1995

Intradural extramedullary ependymoma. A case report.

STUDY DESIGN: The present study illustrates a rare case of ependymoma of the spinal cord. OBJECTIVES: An encapsulated intradural extramedullary ependymoma of the cervicothoracic spinal cord in a 24-year old woman is reported. SUMMARY OF BACKGROUND DATA: Ependymoma is a glial tumor arising in the central nervous system. Intradural extramedullary ependymoma of the spinal cord is rare, and two cases were reported previously. METHODS: The woman presented with myelopathy below C6. Magnetic resonance imaging showed an intradural tumor from C4 to T3 and no other lesion in the central nervous system. At surgery, the extramedullary tumor apparently was not attracted to the spinal cord or dura mater. Gross total removal was easily achieved under the operating microscope. RESULTS: Histologic examination revealed the encapsulated tumor as an anaplastic ependymoma. Almost complete neurologic recovery was obtained. CONCLUSION: The encapsulated appearance, lack of an apparent attachment to the central nervous system, and absence of signs of the primary neoplastic process within the brain or spinal cord suggested that the tumor arose from ectopic ependymal cells.

Adult↗

PubMed1995

A nationwide epidemiological survey of spinal cord injuries in Japan from January 1990 to December 1992.

This survey of traumatic spinal cord injuries in Japan from January 1990 to December 1992 was carried out by a statistical method of the nationwide epidemiological study. The number of the registered patients during these 3 years was 9752 and the mean response rate of every of the 47 prefectures was 51.4%. The registered patients with neurological deficits (Frankel A-D) were 7471 and the annual spinal cord injury incidence was 40.2 per million. The ratio of cervical cord injuries to more caudal SCI was 3:1. The age distribution and the causes of spinal cord injuries are presented in detail. From the results of this study, the prevention campaign should be focused mainly on the following topics: sports and motorcycle accidents involving young people; traffic accidents involving adults; falling accidents involving aged people.

Accidents, Occupational↗

PubMed1995

Influence of minor trauma to the neck on the neurological outcome in patients with ossification of the posterior longitudinal ligament (OPLL) of the cervical spine.

The influence of minor trauma to the neck on the neurological outcome in patients with ossification of the posterior longitudinal ligament (OPLL) of the cervical spine was evaluated retrospectively. Out of 118 patients treated in our clinic for cervical OPLL between 1976 and 1992, 27 had sustained minor trauma to the cervical spine. Of these 27 patients, 13 developed myelopathy, seven showed deterioration of preexisting myelopathy, and no neurological change was observed in seven patients. Regarding the relationship between the diameter of the residual spinal canal and the neurological outcome in these 27 patients, 18 out of the 19 patients with a narrow residual spinal canal (< 10 mm) developed neurological deterioration, whereas that occurred in only two of the eight patients with a wider spinal canal (> or = 10 mm). Although the severity of myelopathy and the transverse area of the spinal cord measured from T1-weighted magnetic resonance images, in patients who had sustained minor trauma was not statistically different from patients without trauma, neurological recovery after surgical treatment was poorer in the former group than in the latter. These results indicate that even indirect minor trauma to the neck can cause irreversible changes in the spinal cord if there is marked stenosis of the cervical spinal canal; such patients who are at risk, must be educated, and should be told to avoid even minor injuries at any cost.

Adult↗

PubMed1995

Lesions of the lumbar posterior end plate in children and adolescents. An MRI study.

We have reviewed 37 patients under the age of 18 years with lesions of the lumbar posterior end plate. All but one were active in sport, and most were seen because of low back pain. An abnormality was commonly found at the inferior rim of the body of L4 and at the superior rim of the sacrum. All adjacent intervertebral discs showed a decrease of signal intensity on the T2-weighted MRI. In 12 patients there was no interposed tissue at the posterior end-plate lesions. When disc material had migrated posteriorly none protruded beyond the posterior margin of the end plate, the dissociated portion of which was the main element compressing neural tissue. The posterior end-plate lesion should be regarded as a vertebral non-articular osteochondrosis.

Adolescent↗

PubMed1995

Lumbar spondylolysis in children and adolescents.

We investigated 185 adolescents under the age of 19 years with spondylolysis. All but five were active in sport. The pars defect was classified into early, progressive and terminal stages. Of the 346 pars defects in 185 patients, 39.6% were early, 29.5% progressive and 30.9% in the terminal stages. Conservative management produced healing in 73.0% of the early, 38.5% of the progressive and none of the terminal defects. These results suggest that spondylolysis is caused by repetitive microtrauma during growth and can be successfully treated conservatively if treatment is started in the early stage. There was elongation of the pars interarticularis as the pars defect progressed, and this is likely to be a consequence of the defect rather than a contributing cause.

Adolescent↗

PubMed1995

Bone mineral density of the lumbar spine in patients with ossification of the posterior longitudinal ligament of the cervical spine.

Bone mineral density (BMD) of the lumbar spine in patients with ossification of the posterior longitudinal ligaments of the cervical spine (OPLL) was measured to elucidate the relation of spinal ossification with systemic hyperostotic condition. BMD in the lateral projection had a statistically significant correlation with that in the anteroposterior projection, and the former was considered to reflect the condition more accurately than was the latter, which may include the ossified spinal ligaments. BMD of patients with continuous and mixed types of OPLL was higher than that of those with the segmental type. Patients with OPLL and ossification of the other spinal ligaments had higher BMDs than did those without ossification. These results suggest that the BMD of the lumbar spine may reflect the systemic hyperostotic tendency and advancement of the ossification.

Absorptiometry, Photon↗

PubMed1994

Morphologic analysis of the cervical spinal cord, dural tube, and spinal canal by magnetic resonance imaging in normal adults and patients with cervical spondylotic myelopathy.

STUDY DESIGN: Transverse areas of the spinal canal, the dural tube and the spinal cord of the cervical spine of normal adults and patients with cervical spondylotic myelopathy (CSM) were analyzed by magnetic resonance imaging (MRI). OBJECTIVES: Correlations of the results of MRI to clarify the pathogenesis of CSM. SUMMARY OF BACKGROUND DATA: Relationships between the area of the spinal cord and that of the dural tube or the spinal canal have been reported, but there is no report to compare the relationships among the three in patients with CSM and normal adults. METHODS: T1-weighted MR images of the cervical spine of 96 normal adults and 74 patients with CSM were evaluated by measuring the transverse areas of the three structures mentioned above in the axial plane. RESULTS: In normal adults, the maximal transverse area of the spinal cord was 85.8 mm2 at C4/5 and the minimal transverse areas of the dural tube and the spinal canal were 186.0 mm2 at C5/6 and 236.1 mm2 at C4, respectively. At the unaffected level of C3, the ratio of the canal to the spinal cord was significantly higher in CSM patients than in age-matched normal adults. The transverse area of the spinal cord and the ratio at the maximal compression level showed significant correlations with the severity of neurological symptoms. CONCLUSION: These results suggest that the narrow area and high ratio of the spinal canal to the spinal cord are responsible for a static factor in CSM.

Adult↗

PubMed1994

Spinal cord injuries in Japan: a nationwide epidemiological survey in 1990.

To survey the situation of traumatic spinal cord injuries (SCI) in Japan, the SCI Prevention Committee of the Japanese Medical Society of Paraplegia sent out by mail study charts in the form of questionnaires to institutions nationwide. Using the statistical method of the nationwide epidemiological survey described by Hashimoto et al,1 the annual estimated incidence was obtained from the number of patients registered, and from the questionnaire reply rate at each prefecture. The number of registered patients in 1990 was 3465 and the mean reply rate was 56.6%. There were 2665 registered patients with a neurological deficit (Frankel A-D) and the annual SCI incidence was 39.4 per million. The male:female ratio was 4.3:1 and the ratio of cervical cord injures to those caudal to the cervical cord was 2.9:1. The mean age at the time of injury was 48.5 years. The cause most frequently seen was traffic accidents, the second most frequent being falls from a height. Besides those two, sports injuries and falls on level ground were the third most frequent causes of SCI in the young generation and in elderly people respectively.

Accidental Falls↗

PubMed1994

Increased production of eicosanoids, TXA2, PGI2 and LTC4 in experimental spinal cord injuries.

Arachidonate metabolites have many kinds of bioactivities. Thromboxane A2 (TXA2) stimulates platelet aggregation and vasoconstriction, whereas prostaglandin I2 (PGI2) antagonises its activities. Thromboxane B2 (TXB2) and 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha) are determined in biological materials. Production of TXB2, 6-keto-PGF1 alpha and leukotriene C4 (LTC4), which have potent vascular permeability, was measured by radioimmunoassay in experimental spinal cord injured animals. TXB2 level in the rat spinal cord reached a peak concentration of 133.6 +/- 3.8 pmol/g cord, and 6-keto-PGF1 alpha increased to 26.2 +/- 11.7 pmol/g cord 5 minutes after the injury. There was good correlation between TXB2 production and vascular damage as monitored by fluorescein uptake. When OKY-046 ((E)-3-[4-(1-imidazolylmethyl) phenyl]-2-propenoic acid), which selectively inhibits TXA2 synthetase activity, was administered 10 minutes before injury, the increase in TXB2 production was inhibited by more than 80%, but the degree of vascular damage was reduced by only 40%. In the guinea pig spinal cord, LTC4 levels reached a peak concentration of 2.2 +/- 0.4 pmol/g cord 10 minutes after compression, while that of TXB2 reached 146.8 +/- 6.2 pmol/g cord. The increased production of TXB2 was correlated with the degree of compression injury while that of LTC4 production did not. These findings suggest that vasoactive eicosanoids, TXA2, PGI2 and LTC4, play important roles in secondary damage following spinal cord injury, although their roles may be different among species of animals.

6-Ketoprostaglandin F1 alpha↗

PubMed1994

Effect of stimulation frequency on metabolism of skeletal muscles.

We studied the effects of stimulation frequency on the energy metabolism of rat skeletal muscles during electrical low-frequency stimulation, using in vivo phosphorus-31 magnetic resonance spectroscopy. The sciatic nerve of Wistar-Kyoto rats (n = 16) was stimulated electrically using low frequency stimulation (LFS) at 30 Hz and high frequency stimulation (HFS) at 100 Hz as tetanizing frequencies. The initial tension during LFS was significantly different from that during HFS, 200.49 +/- 19.47 vs. 516.67 +/- 5.38 dynes (mean +/- S.E.; n = 8) (p < 0.01). In the first 2 min of stimulation, the ratio of phosphocreatine (PCr) to inorganic phosphate (Pi) + sugar phosphate (SP) during LFS and HFS were 0.28 +/- 0.04 and 0.53 +/- 0.06 (mean +/- S.E.; n = 8), respectively. Subsequently, the ratio during LFS remained lower than that during HFS. The intracellular pH during LFS and HFS in the first 2 min of stimulation was 6.27 +/- 0.02 and 6.75 +/- 0.03 (mean +/- S.E.; n = 8), respectively. From 2 min to 12 min of stimulation, the intracellular pH during LFS remained lower than that during HFS. The results showed that lower levels of both energy and intracellular pH of skeletal muscles were maintained during LFS than during HFS, facilitating aerobic glycolysis to produce ATP during stimulation.

Animals↗

PubMed1993

Magnetic resonance imaging study on the results of surgery for cervical compression myelopathy.

The morphologic changes and signal intensity of the spinal cord on preoperative magnetic resonance images were correlated with postoperative outcomes in 74 patients undergoing decompressive cervical surgery for compressive myelopathy. The transverse area of the spinal cord on T1-weighted images at the level of maximum compression was closely correlated with the severity of myelopathy, duration of disease, and recovery rate as determined by the Japanese Orthopaedic Association score. In patients with ossification of the posterior longitudinal ligament or cervical spondylotic myelopathy, the increased intramedullary T2-weighted magnetic resonance imaging signal at the site of maximal cord compression and duration of disease significantly influenced the rate of recovery. A multiple regression equation was then developed with these three variables to predict surgical outcomes.

Cervical Vertebrae↗

PubMed1993

Mechanism of pain in osteoid osteomas: an immunohistochemical study.

Osteoid osteoma is a benign bone tumour characterized by pain which is relieved by non-steroidal anti-inflammatory drugs (NSAIDs), such as aspirin. To clarify the mechanism of the pain, five osteoid osteomas were studied immunohistochemically using polyclonal antibodies against prostaglandin E2 (PGE2), S-100 protein and protein gene product 9.5 (PGP 9.5). In all five cases, the pain had been relieved by NSAIDs. Nerve fibres positive for S-100 protein and PGP 9.5 were observed in the fibrous zone, especially close to the blood vessels, around the nidus in all the lesions and also within the nidus in three lesions. PGE2 immunoreactivity was variably positive in the nidus of three lesions. In one case a large number of actively proliferating osteoblasts reacted with this antibody. The other cases showed unevenly distributed PGE2 positivity which tended to be prominent in the plump osteoblasts. As control material we examined fibrous dysplasia (3 cases), osteosarcomas (3) and giant-cell tumours of bone (3). The plump osteoblastic tumour cells of three osteosarcomas and the bone-forming cells in two cases of fibrous dysplasia gave a positive reaction for PGE2. No S-100 or PGP 9.5 immunoreactive nerve fibres were seen in these lesions. It is concluded that the presence of nerve fibres alone might play a more important role in mediation of pain in osteoid osteomas than some effects of osteoblast-produced PGE2 on the nerves and proliferated blood vessels.

Adolescent↗

PubMed1993

Immunoaffinity purification of prostaglandin E2 and leukotriene C4 prior to radioimmunoassay: application to human synovial fluid.

When human synovial fluid as such was subjected to radioimmunoassays of prostaglandin E2 (PGE2) and leukotriene C4 (LTC4), there was no linear increase in PGE2 and LTC4 as the amount of synovial fluid was raised. For removal of substances thus disturbing the assay we developed a method of immunoaffinity purification of PGE2 and LTC4. A monoclonal antibody against PGE2 or LTC4 was coupled to BrCN-activated Sepharose 4B. When synovial fluid mixed with radiolabelled PGE2 or LTC4 was applied to the column of immobilized antibody, the ligand was adsorbed to the column and eluted with a mixture of methanol/water in a recovery of about 80%. The purified material showed a linearity between the amount of the sample and the value of radioimmunoassay. The one-step method was applied to synovial fluid from patients with rheumatoid arthritis, osteoarthritis and other joint diseases.

Animals↗

PubMed1993

Effect of active recovery on intracellular pH following muscle contraction, a 31P-MRS study.

The effect of active recovery after intense muscular exercise was examined by 31P-MRS. Seven healthy males participated in this study, and their right wrist flexor muscles were examined. Each subject flexed the right wrist at 60% of the maximum voluntary contraction (MVC) until the intracellular pH in the wrist flexor muscle decreased to approximately 6.4. This was followed either by active recovery (AR) which consisted of 5, 10, 20, 30 or 40% MVC exercise, and by passive recovery (PR) during a 10-min-recovery period. The intracellular pH (pHi) recovered faster during AR at each condition than during PR. Besides, from the 2nd to the 5th min of the recovery period, the pHi was significantly higher during AR than during PR. The quadratic regression curve of pHi recovery during the 10-min-recovery-period against the % MVC was obtained. The optimal contraction intensity determined from this curve was 8.7% MVC for a 10-min-recovery-period. The optimal levels were determined for another recovery duration within 10 min, and the level decreased with the prolonged recovery duration. These data suggest that mild exercise is an effective maneuver to promote the recovery from intracellular metabolic acidosis, and that the intensity of the recovery exercise should be determined according to the cooling down duration or the resting interval before the subsequent exercise performance.

Adult↗

PubMed1991

Magnetic resonance imaging study on spinal cord plasticity in patients with cervical compression myelopathy.

Spinal cord plasticity in 55 patients with cervical compression myelopathy was assessed with magnetic resonance imaging, by which the transverse area of the spinal cord was measured at the site of maximum compression before and after surgery and compared with the conventional modalities of computed tomographic myelography. A high correlation (r = 0.901, P less than 0.01) was observed between the preoperative measurements of magnetic resonance imaging and computed tomographic myelography. The preoperative transverse area was in good correlation with the preoperative Japanese Orthopaedic Association score (r = 0.466, P less than 0.01). In most patients with a spinal cord area of less than 0.45 cm2, the clinical results were poor despite considerable morphologic restoration of the spinal canal obtained after decompression surgery, reflecting an irreversible pathology developed in the spinal cord.

Adult↗

PubMed1991

Comparative study between magnetic resonance imaging and histopathologic findings in ossification or calcification of ligaments.

Magnetic resonance imaging findings were compared with histopathologic specimens of ossified or calcified ligaments, including the surrounding tissue, to evaluate the usefulness of magnetic resonance imaging as a means to predict the progression of ossification. In addition, factors influencing signal intensity were evaluated by histochemical and immunohistochemical analyses. The area of low signal intensity corresponded to the hyperplastic ligament around the ossification, and to the transitional area between the ligament and the ossification. A mineralization front and chondrocyte proliferation with strong metachromasia were recognized in these areas. The presence of a low-intensity signal area suggested the progression of ossification. The isointensity signal corresponded to proliferation of small vessels in the hyperplastic ligament, presumably representing the initiation of ossification. Histochemically, the metachromasia was intense at the transitional area between the ligament and the ossification, and the main constituent in these areas was chondroitin sulfate. Immunohistochemically, S-100 protein, transforming growth factor-beta 1, and Type II collagen showed an intense immunoreactivity in the chondrocytes, indicating increased production of the extracellular matrix. We postulate that the activation of chondrocytes and the alteration of the extracellular matrix may have affected the signal intensity.

Aged↗