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Biomedical subjects

T Ikata

Publications and source records attributed to T Ikata.

At least 73 records · Page 4Linked to original sources
PubMed1991

[Alteration of leukotriene C4 levels in experimental spinal cord injury].

Leukotriene C4 (LTC4) production in the guinea pig spinal cord following compression injury was determined by radioimmunoassay, in the same way thromboxane B2 (TXB2), a stable metabolite of thromboxane A2 (TXA2), was also measured. When the spinal cords were compressed under a 20 gram weight for 10 minutes, LTC4 levels reached peak values (2.2 +/- 0.4 pmol/g cord) 10 minutes after release, then gradually decreased until being undetectable 60 minutes later. TXB2 levels reached peak values (146.8 +/- 6.2 pmol/g cord) 5 minutes after the release from compression, the TXB2 level then gradually decreased, but remained at about 1/2 of the peak level even 60 minutes after the release. When the spinal cords were compressed with various weights, TXB2 production depended on the degree of compression, while LTC4 production was not affected by the compression injury. The LTC4 production confirmed in the injured spinal cords is suggestive of its relation to secondary disorders after spinal cord injury, spinal edema, in particular.

Animals↗
PubMed1990

Influence of dietary vitamin E deficiency on compression injury of rat spinal cord.

The influences of vitamin E deficiency on compression injury of the rat spinal cord associated with ischemia were investigated. Growing rats were divided into two groups and given a diet containing either 2 IU/100 g or less than 0.1 IU/100 g of alpha-tocopherol acetate, respectively, for 6-8 weeks before experiments. Motor disturbances induced by spinal cord injury were found to be enhanced by vitamin E deficiency. The spinal cord blood flow (SCBF) was reduced by compression and subsequently increased transiently and then decreased gradually in both groups, but the level was lower in the vitamin E-deficient group than in the control group. After injury, the vitamin E-deficient group showed lower recoveries than the control group in the amplitude and latency of spinal cord evoked potentials and greater pathological changes of the spinal cord, such as bleeding and edema. The increase in the level of TBA-reactive substances in the spinal cord after injury increased with decrease in the dietary level of vitamin E. These results suggest that vitamin E may have a protective effects against ischemic spinal cord injury by its antioxidant effect.

Animals↗
PubMed1990

[Beneficial effect of a selective TXA2 synthetase inhibitor, OKY-046, both on thromboxane B2 production and vascular damage after spinal cord injury in rat spinal cord].

Thromboxane A2 (TXA2) is an eicosanoid with potent platelet aggregation and vasoconstricting activity, while prostaglandin I2 (PGI2) antagonizes its activity. But these eicosanoids are so labile that the stable degradation products, thromboxane B2 (TXB2) and 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha), are determined in biological materials. In a rat spinal cord compression injury model, a production of TXB2 reached a peak (133.6 +/- 13.8 pmol/g cord) 5 minutes after compression injury, while that of 6-keto-PGF1 alpha slightly increased (26.2 +/- 11.7 pmol/g cord). And the magnitude of the increase in TXB2 and the extent of post-traumatic vascular damage as determined by fluorescein uptake were both dependent on the degree of spinal cord compression injury. We also studied the effect of a selective TXA2 synthetase inhibitor, OKY-046 [E)-3-[4-(1-imidazolylmethyl)phenyl]-2-propenoic acid), both on TXB2 production in the injured spinal cord and post-traumatic vascular damage. When OKY-046 was administered intravenously 10 minutes prior to compression injury at a dose of 500 micrograms/kg body weight, the increased production of TXB2 was inhibited by about 80% and uptake of sodium fluorescein was reduced by a maximum of 40%. When the compression injury was induced before OKY-046 was administered, the inhibitory effect of OKY-046 on TXB2 production decreased depending on the duration before administration. In contrast, the 6-keto-PGF1 alpha level was not affected in the presence of OKY-046.

6-Ketoprostaglandin F1 alpha↗
PubMed1989

Protective effect of vitamin E on spinal cord injury by compression and concurrent lipid peroxidation.

Studies were made on the influence of vitamin E on the effects of compression injury of the spinal cord associated with ischemia in rats. The motor disturbance induced by spinal cord injury was greatly reduced by vitamin E supplementation. After injury, the spinal cord evoked potentials showed greater recovery of both amplitude and latency in the vitamin E-supplemented group than in the control group. Spinal cord blood flow was promptly restored and remained normal after injury in the vitamin E-supplemented group, but was significantly decreased from 3 h after injury in the control group. Thiobarbituric acid (TBA)--reactive substances in the spinal cord was immediately increased by compression injury in both groups, and after injury it persisted at a high value for 24 h in the control group, but decreased within 1 h in the vitamin E-supplemented group. Pathological examination of the spinal cord showed less damage, such as bleeding and edema, in the vitamin E-supplemented group than in the control group. Vitamin E may have protective effects on the spinal cord by inhibiting damage induced by lipid peroxidation and/or by sustaining the blood flow by maintaining the normal metabolism of arachidonic acid.

Animals↗
PubMed1989

Experimental studies on permeability of tracers into the spinal cord.

For investigation of the intramedullary penetration of metrizamide, the intramedullary movements of fluorescein, Evans Blue, Horseradish peroxidase (HRP) and ionic lanthanum in the normal cord and experimental syringomyelia of rats were studied. Syringomyelia was induced by injection of kaolin suspension into the cisterna magna. Subsequently HRP or ionic lanthanum was perfused into the subarachnoid space and its distribution was examined by electron microscopy. In normal rats, HRP mainly became localised in the basement membrane between the pia mater and glial cells and only a few vesicles migrated into the extracellular spaces (ECS) between glial cells. Ionic lanthanum, however, migrated deep into the ECS. In rats with experimental syringomyelia many vesicles of HRP migrated deep into the ECS of glial cells and the white matter. These findings indicated that the ECS of the marginal glia and the neuropil constitute part of a pathway through which metrizamide migrates into the intramedullary cavity.

Animals↗
PubMed1989

Malignant peripheral nerve sheath tumor (MPNST) showing perineurial cell differentiation.

We report a malignant peripheral nerve sheath tumor (MPNST) showing the unusual immunohistochemical feature of epithelial membrane antigen (EMA) immunoreactivity in a 52-year-old man. The tumor, located in the left paravertebral muscles, was composed of both cellular and myxoid areas. Spindle-shaped tumor cells were arranged in longitudinal cell cords, in a storiform pattern, and in whorled structures. Ultrastructurally, the tumor cells had many interdigitating cell processes, primitive cell junctions, and discontinuous external laminae. These histological and ultrastructural features were most consistent with those of an MPNST; but on immunohistochemistry, the tumor cells reacted for epithelial membrane antigen rather than for S-100 protein or Leu-7. Because EMA-immunoreactivity was recently demonstrated in perineurial cells, we concluded that the tumor was an MPNST mainly composed of tumor cells showing perineurial cell differentiation.

Cell Differentiation↗
PubMed1989

Clinical considerations and biochemical basis of prognosis of cervical spinal cord injury.

A total of 118 patients with cervical spinal cord injury were studied to determine the neurologic improvement achieved by either conservative or surgical treatment. Useful recovery was observed in 55% of the patients with incomplete cord injuries, but in none of those with complete cord injuries. There was no significant difference between the treatment groups regarding neurologic improvement. In experimental studies on rats, the increased levels of lipid peroxides and thromboxane after spinal cord injury were found to be proportional to the magnitude of injury. These evidences suggest that spinal cord injury is directly related with the magnitude of injury, and the prognosis is determined entirely at the time of injury.

6-Ketoprostaglandin F1 alpha↗
PubMed1988

Observation of fatigue unrelated to gross energy reserve of skeletal muscle during tetanic contraction--an application of 31P-MRS.

The mechanism of muscle fatigue was studied by 31P-MRS. During tetanic contraction for 2 minutes(min), the tension measured with a strain gauge and Phosphocreatine(PCr)/Inorganic phosphate(Pi)+ Phosphomonoester(PME) ratio decreased to 31.5 +/- 4.4% of the control value and 0.6 +/- 0.1, respectively. The intracellular pH(pH) also decreased to 6.62 +/- 0.04. Toward the end of the stimulation, the tension decreased to 25.3 +/- 1.9% of the control value. However, during 20min stimulation, the PCr/(Pi+PME) ratio increased to 2.5 +/- 0.5 and the pH to 6.91 +/- 0.04. These results show that muscular fatigue is ascribable not to a decreased level of high energy metabolites required for actomyosin ATPase, but to an increase in the threshold intensity of excitation in excitation-contraction coupling.

Animals↗
PubMed1988

Clinical and experimental studies on permeability of tracers in normal spinal cord and syringomyelia.

Delayed CT Myelography (CTM) demonstrated intramedullary cavities in 18 patients, most of which appeared on the 6-hour scan. The attenuation values of the normal spinal cord increased progressively with time, and recorded a peak at 6 hours. The CT numbers of the gray matter of metrizamide were significantly high, as compared with those of iotrol. In the tracer study reported, lanthanum penetrated through the marginal glia to the normal and pathologic spinal cord. Reaction products of horseradish peroxidase (HRP) were mainly in the extracellular space of the normal spinal cord. The pathologic spinal cord, however, allowed the passage of HRP into the parenchyma through the extracellular space of the marginal glia. Consequently, the extracellular space of the spinal cord surface constitutes a pathway for cerebrospinal fluid solutes. Either metrizamide or iotrol thus diffuses into the spinal cord from the subarachnoid space.

Animals↗
PubMed1988

[An experimental study on preventive effect of vitamin E in spinal cord injury].

The effects of vitamin E on compression injury of the spinal cord associated with ischemia were studied in rats. Growing rats were divided into two groups and given diet containing 2 IU/100 g (group C) or 50 IU/100 g (group E) of alpha-tocopherol acetate from 8-10 weeks before experiments. The motor disturbance induced by spinal cord injury was greatly reduced by vitamin E-supplementation. After injury, the value of TBA-reactive substances (TBARS) was immediately increased and the level of alpha-tocopherol was correspondingly decreased in the spinal cord. A higher level of TBARS was observed in the proximal region than in the injured region of the spinal cord. The high level persisted for 24 hrs in group C, but decreased within 1 hr in group E. Pathological examination of the spinal cord revealed less damage, such as bleeding and edema, in group E than in group C.

Animals↗
PubMed1983

A technique of dynamic reduction for displaced fractures of the thalamus of the calcaneum.

A new technique of reduction based on the anatomical structure of the calcaneum was first described in 1974. Two pins were inserted, one into the posterior surface and the other into the plantar surface of the bone. This allowed early mobilisation of the foot. The method can be used in all types of fractures including comminuted fractures of the tuberosity, the tongue type, the central depression type, the severe tongue type, the severe depression type and unclassified severe crush fractures. Complete anatomical reduction was obtained in 58 out of 72 fractures (77%) and 56 out of 64 patients (87.5%) were classified as "very good" by the Maxfield assessment. In this paper the authors discuss their method of management of displaced fractures of the thalamic part of the calcaneum.

Adult↗