Biomedical subjects

K Mimatsu

Publications and source records attributed to K Mimatsu.

At least 19 recordsLinked to original sources

PubMed2000

Laminectomy performed using a micro bone saw.

In 154 clinical cases requiring laminectomy at any part of the spinal column, the laminae were removed using a micro bone saw. Immediately after the laminectomy two surgeons using a microscope examined the field for any damage to the dura, the spinal cord, the nerve roots and the epidural vessels. No injury to the spinal cord or the nerve roots was observed. In 5 patients the dura were lacerated for a length of up to 10 mm, and in all the patients adhesions were present due to previous operations. Epidural vessels were severed in 18 cases. The method is useful and less time-consuming than conventional laminectomy.

Adolescent↗

PubMed1998

[Immunohistochemical study of p53, p27 and PCNA expression in esophageal cancer].

We evaluated the clinical significance of p53, p27 and PCNA expressions in esophageal squamous cell carcinomas. Operative specimens obtained from 70 patients with esophageal squamous cell carcinomas were investigated by staining with antibodies against p53, p27 and PCNA. The correlations among p53, p27 and PCNA expression, clinicopathologic factors and prognosis were studied. The expression of p53 was observed in 55.7%, and it did not correlate to histologic classification, growth pattern, and lymphatic invasion. The expression of p27 was observed in 48.6%, and it correlated to lymph node metastasis. The PCNA positive index (PCNA-PI) was high in the p27 negative cases. The p53 positive and p27 negative group revealed the worst survival rate among groups. Therefore, the p27 positive case, often associated with well differentiated carcinoma, tends to have a slower tumor-growth rate and better prognosis. It is suggested that immunohistochemical assessment on the p53 and p27 expressions would be useful to the recognize the malignant potential and differentiation of squamous cell carcinoma of the esophagus.

Aged↗

PubMed1997

Natural course of experimental scoliosis in pinealectomized chickens.

STUDY DESIGN: Pinealectomy induces experimental scoliosis in chickens. This study analyzed the natural course and characteristics of the scoliosis that developed after pinealectomy. OBJECTIVES: To investigate the natural course of experimental scoliosis after pinealectomy in chickens and determine its similarity to idiopathic scoliosis in humans. SUMMARY OF BACKGROUND DATA. Pinealectomy affects the systemic hormonal balance and consistently induces progressive scoliosis in chickens. METHODS: Thirty five chickens were divided into two groups, a pinealectomy group (n = 25) and a control group (n = 10). At the age of 3 days, all chickens in the pinealectomy group underwent surgery. Spinal radiographs of all chickens were taken at 2-week intervals until the age of 16 weeks. RESULTS: There was no alteration of spinal alignment in the control group. Seventeen chickens in the pinealectomy group had scoliosis (17 degrees-85 degrees) that featured a three-dimensional spinal deformity consisting of both lateral curvature and vertebral rotation with rib humps. The scoliosis progressed to become slight, moderate, or severe as the chickens grew older. Pinealectomized chickens showed several other differences from chickens of the normal control group, such as poor weight gain, underdeveloped cockscombs, and late onset of egg laying. CONCLUSIONS: The scoliosis developing in chickens after pinealectomy was similar to human idiopathic scoliosis, and thus seems to be a useful model of idiopathic scoliosis.

Age Factors↗

PubMed1997

Histologic changes in the intervertebral disc after intradiscal injections of methylprednisolone acetate in rabbits.

STUDY DESIGN: Histologic changes in the intervertebral disc were evaluated by light and electron microscopy after an intradiscal injection of methylprednisolone acetate. OBJECTIVE: To evaluate the histologic changes that occur in the disc after an intradiscal injection of cortico steroids. SUMMARY OF BACKGROUND DATA: Several orthopedic surgeons have managed lumbar disc herniation with intradiscal steroid injection. Few studies have addressed the histologic changes after this treatment. METHODS: Thirty rabbits were surgically treated. Rabbits were divided into two groups. Group A: 25 rabbits underwent intradiscal steroid injections. Methylprednisolone acetate was injected into the L3-L4 disc, whereas methylprednisolone sodium succinate was injected into the L4-L5 disc. Physiologic saline was injected into the L5-L6 disc as a control. Groups of five rabbits were killed 1 day, 1, 4, 12, and 24 weeks after the injection and subjected to microscopic evaluation. Group B: Another five rabbits underwent an injection of polyethylene glycol 4000, a vehicle for methylprednisolone acetate, into the L3-L4 and L4-L5 discs. All five rabbits were killed 24 weeks after the injection and subjected to microscopic evaluation. RESULTS: Group A: Light microscopic evaluation showed tissue in the nucleus pulposus, and the inner layer of the anulus fibrosus had degenerated in the methylprednisolone acetate group killed 24 weeks after the injection. Matrix vesicles, an indication of primary tissue calcification, were observed by electron microscopy. In the methylprednisolone sodium succinate group and saline group, however, no histologic changes were observed. Group B: Degeneration of the nucleus pulposus and primary tissue calcification were observed in the discs of all rabbits. CONCLUSIONS: Methylprednisolone acetate and its vehicle polyethylene glycol cause degeneration and primary calcification in discs.

Animals↗

PubMed1997

Experimental chronic compression on the spinal cord of the rabbit by ectopic bone formation in the ligamentum flavum with bone morphogenetic protein.

This study was conducted to induce chronic spinal cord compression myelopathy in rabbits. The L5 lumbar lamina was cut partially in 70 rabbits, and bone morphogenetic protein (BMP) was implanted on the ligamentum flavum in 35 of them. In the BMP group, new bone formed on the dorsal side of the spinal canal and flattened the spinal cord in an anteroposterior direction. No pathological changes were detected in the intramedullary tissues by light microscopic examination. In rabbits it is possible to induce compression of the cord by using BMP, although sufficient cord compression to induce myelopathy was not achieved.

Animals↗

PubMed1997

New laminoplasty after thoracic and lumbar laminectomy.

We report the development of a new laminoplasty for the thoracic and lumbar spine. In this method, after two or three laminae are subjected to en bloc laminectomy using a surgical air drill, median longitudinal incisions are made in the laminae from the ventral side with a microsurgical saw and then the resected laminae are put back in place, like pitching a tent. Because fixation is accomplished with silk thread, magnetic resonance imaging is unaffected. In 39 cases in which this method was used, the spinal canal was adequately enlarged and bony union was also satisfactory starting after a mean of 4.3 months. This method is useful as a form of anatomical repair after laminectomy. Because it preserves the posterior element, it helps to prevent shrinkage of the laminectomy membrane mass and postoperative spinal column deformity.

Adolescent↗

PubMed1997

[Delayed exacerbation of cervical myelopathy in a case of juvenile muscular atrophy of unilateral distal upper extremity].

We reported a case in which cervical myelopathy exacerbated 20 years after the stabilization of juvenile muscular atrophy of unilateral distal upper extremity. The patient presented progressive weakness in the right proximal upper extremity and spastic paraparesis in addition to the long-lasting muscular atrophy of right distal upper extremity. Plain x-ray showed severe cervical spondylosis with kyphosis of the cervical spine. Dynamic study on MRI disclosed cervical spinal cord atrophy and compression enhanced in both flexion and extension position of the neck. Malalignment (kyphosis) and severe spondylotic change of the cervical spine seemed to affect the spinal cord with little functional reservoir, manifesting the delayed exacerbation of myelopathy. We conclude that malalignment and subsequent spondylotic change of the cervical spine would be significant factors to determine the long term prognosis of patients with juvenile muscular atrophy of unilateral distal upper extremity.

Arm↗

PubMed1996

Morphometric study of myelinated fibers in human cervical spinal cord white matter.

STUDY DESIGN: Using human autopsy spinal cord specimens, morphologic measurements of myelinated nerve fibers were performed, focusing on the regions that include the main white matter conduction paths. The hemilateral spinal cord morphology was also measured, and its relation with the component myelinated nerve fibers determined. OBJECTIVES: To determine the relation between spinal cord transverse area in the normal lower cervical spine, the site most vulnerable to chronic compressive myelopathy, and myelinated nerve fibers. SUMMARY OF BACKGROUND DATA: Considerable interindividual variation normally is observed in the morphology of the spinal cord transverse area. The influence of this variation on the composition of the white matter myelinated nerve fibers is obscure. METHODS: The C7 segments from seven cadavers were resected, and from magnified photographs of paraffin-embedded specimens, the hemilateral spinal cord area and funicular area were measured. Nerve fiber morphology was measured using Epon-embedded specimens. Three regions that included the main conduction paths were sampled, and magnified photographs obtained. The nerve fiber transverse morphology was measured using the ellipse conversion method, and the myelinated nerve density and fiber area were determined. RESULTS: Marked interindividual variations were found in both the hemilateral spinal cord transverse area and funicular area. A positive correlation was noted between the two, with the spinal cord transverse area large in the cases with a large funicular area. For fiber density and area, histograms were constructed that showed characteristic distribution patterns in each region. By dividing each region into two components (i.e., small- and large-diameter fibers), it was found that the interindividual variation in large-diameter fiber density was small, clarifying that the absolute number of large-diameter fibers compared to fiber density is more strongly dependent on the funicular area. CONCLUSIONS: The absolute number of large-diameter myelinated fibers is smaller in cross-sections of thin as compared to those of thick spinal cord. When elucidating the pathophysiology of compressive myelopathy, it is necessary to study not only the circumstances surrounding the spinal cord, but this kind of factor intrinsic to the spinal cord itself.

Adult↗

PubMed1996

Experimental chemonucleolysis with chondroitinase ABC in monkeys.

STUDY DESIGN: Experimental chemonucleolysis with chondroitinase ABC as compared with chymopapain was investigated in monkeys. The effects of these two enzymes were analyzed morphologically and biochemically. OBJECTIVES: The results of the present study facilitate the clinical application of chondroitinase ABC. SUMMARY OF BACKGROUND DATA: Many experimental studies on chemonucleolysis with chondroitinase ABC have been reported mostly in rabbits. Further examination in animals that are more similar to humans is necessary for its clinical application. METHODS: Ten mature rhesus monkeys were used. Lumbar intervertebral discs from six monkeys were injected with either chondroitinase ABC, chymopapain, or physiologic saline. The animals were killed not more than 6 weeks after injection, and their discs were examined morphologically and biochemically. The remaining four monkeys were used for a longer follow-up study to determine the changes in chondroitinase ABC-injected discs. RESULTS: Degenerative changes of discs were more severe with the injection of chymopapain, although the content of hyaluronic acid, chondroitin sulfate, and dermatan sulfate decreased more with the injection of chondroitinase ABC. In a longer follow-up study, chondroitinase ABC-injected discs recovered somewhat morphologically and biochemically. CONCLUSIONS: The results confirm that selective degradation is achieved with chondroitinase ABC in vivo in monkeys and that chondroitinase ABC is less toxic to discs than chymopapain is. From these considerations, chondroitinase ABC is believed to have a high potential for clinical application.

Animals↗

PubMed1996

Idiopathic spinal cord herniation.

Idiopathic spinal cord herniation is a rare disease, few cases having been reported. We encountered a case of idiopathic spinal cord herniation presenting with severe spasticity in the right leg and urinary dysfunction. The spinal cord was herniated into a cavity created by duplication of the dura mater and resection of the inner layer improved the neurological deficits. MRI, myelography, and CT myelography were useful for diagnosing this disease. Four radiological signs of spinal cord herniation are described.

Dura Mater↗

PubMed1996

Successful treatment of chylothorax by bleomycin for Gorham's disease.

A patient with idiopathic osteolysis in the thoracolumbar spine who developed severe chylothorax after a spinal operation is described. Irradiation and pleural adhesion therapies with minocycline and bleomycin were undertaken to control the chylothorax. Pleural adhesion therapy with bleomycin proved effective in treating this patient. Magnetic resonance imaging was performed to detect the lesion. T1 weighted imaging was particularly useful in diagnosing the lesion and evaluating the degree of fusion in the spine.

Adult↗

PubMed1996

Massive tongue swelling as a complication after spinal surgery.

We report four cases of massive tongue swelling after spinal surgery. Swelling resulted from the position of the spine during surgery (flexed thoracic-cervical position), fixation of the endotracheal tube, additional surgical gauzes packed around the endotracheal tube, and compression of the base of the tongue. Swelling, which causes obstruction of the airway, is a severe complication after spinal surgery that sometimes requires a tracheotomy. This complication can be avoided by careful positioning of the patient and by fixation of the endotracheal tube before surgery. Once swelling of the tongue occurs, administration of a corticosteroid is effective in preventing construction of the airway.

Adrenal Cortex Hormones↗

PubMed1995

Intramedullary spinal cord germinoma.

STUDY DESIGN: A very rare case of intramedullary spinal cord germinoma is described. OBJECTIVE: To increase knowledge about the pathogenesis and treatment of intramedullary spinal cord germinoma. SUMMARY OF BACKGROUND DATA: Primary intramedullary spinal cord germinoma is very rare and only two cases have been previously reported. METHODS: A case of intramedullary spinal cord germinoma with complete paraplegia is presented. The diagnosis was determined by biopsy. RESULTS: After local irradiation of 46 Gy, the tumor disappeared completely. CONCLUSION: Irradiation therapy effectively treated this tumor, as shown radiologically, although the patient remained paraplegic.

Adult↗

PubMed1995

Spinal cord expansion after decompression in cervical myelopathy. Investigation by computed tomography myelography and ultrasonography.

STUDY DESIGN: This study analyzed anatomic characteristics of 44 patients with cervical myelopathy. OBJECTIVES: This study was conducted to clarify the patterns of spinal cord expansion after decompression, their relationship to clinical recovery, and the capacity of the compressed spinal cord for restoration. SUMMARY OF BACKGROUND DATA: No previous studies have clearly assessed the relationship between morphological changes of the spinal cord and clinical improvement after posterior decompression in patients with cervical myelopathy using computerized tomography myelography and intraoperative spinal sonography. METHODS: Forty-four patients with cervical myelopathy underwent posterior decompression. The diagnosis was cervical spondylosis in 26 patients and ossification of the posterior longitudinal ligament in 18 patients. The cross-sectional area, sagittal diameter, and frontal diameter of the spinal cord at the level of maximum compression were determined by computerized tomography myelography (performed before and 1 month after decompression) and by intraoperative spinal sonography. RESULTS: Expansion of the spinal cord was defined as immediate or gradual. Of the 44 patients, 20 demonstrated gradual expansion, and their clinical recovery rate was 68.4%. In contrast, the clinical recovery rate of patients without gradual expansion was only 32.6%. Good clinical recovery was significantly related to gradual expansion. The patients were divided into four groups (A-D) based on the clinical recovery rate and compression ratio. Group A (severe compression and poor clinical recovery) showed a significantly smaller cross-sectional area of the spinal cord than Group D (severe compression, but good clinical recovery). CONCLUSIONS: Preservation of the cross-sectional area of the spinal cord, even when it is severely compressed and deformed, is an important factor in a good surgical outcome.

Adult↗

PubMed1995

Scoliosis and congenital heart disease.

STUDY DESIGN: This study analyzed clinical characteristics of scoliosis associated with congenital heart disease. Chest roentgenograms were reviewed to determine frequency, type, onset, and progression of scoliosis associated with congenital heart disease. OBJECTIVES: To determine which patients with scoliosis and congenital heart disease should be followed-up carefully. SUMMARY OF BACKGROUND DATA: Although several studies have been reported on scoliosis and congenital heart disease, the etiology of scoliosis in patients with congenital heart disease is still unknown. Furthermore, it has been difficult to determine the progression of scoliosis. METHODS: Chest roentgenograms of 680 patients who underwent cardiac operations because of congenital heart disease were evaluated. RESULTS: Seventy-four (10.9%) of these patients had scoliosis of more than 10 degrees, although most of them had mild curves. Scoliosis in patients under 10 years old undergoing cardiac operations was more severe than in those older than 10 years who underwent surgery. Scoliosis associated with congenital heart disease showed no particular features. Patients with patent ductus arteriosus showed left convex, high thoracic scoliosis after surgery. CONCLUSIONS: The mechanisms of onset of scoliosis in patients with congenital heart disease were not simple and were affected by several factors, including age at operation, side of approach, and type of congenital heart disease.

Adolescent↗

PubMed1995

Serial changes on MRI in lumbar disc herniations treated conservatively.

Using serial MRI, we studied 32 patients with herniated lumbar discs, treated conservatively, to clarify the natural history of this condition. MRI was performed in the acute stage, then 6 months and 1 year later. On axial images, the proportion of the cross-sectional area of the spinal canal occupied by the herniated disc was 31.9% on the average on the initial scan, 28.7% 6 months and 25.3% 1 year later. The size of the herniation decreased by more than 20% in 11 patients (34%), by 10-20% in 8 (28%) and was unchanged in 12 (38%). The height of the disc slightly decreased with time, but there was no significant change in the angle of lordosis in the affected segment. The initial MRI revealed degeneration of all affected discs, and progressive degeneration was observed in 9 patients. The more degenerate the disc and the larger the initial herniation the more the size of the herniated fragment decreased.

Adolescent↗

PubMed1995

Reinnervation of peripheral nerve segments implanted into the hemisected spinal cord estimated by transgenic mice.

We investigated how far Schwann cells, which are the peripheral nerve elements supporting axonal regrowth, penetrate into the hemisected recipient spinal cord. C57BL/6 mice, which carry carcinoembryonic antigen as transgene, were used for transplantation study. These CEA transgenic mice were syngenic to C57BL/6 mice except for the expression of human CEA DNA. In the syngenic transplantation study, C57BL/6 mice were transplanted with the sciatic nerve of CEA-transgenic mice to the hemisected spinal cord. Schwann cell migration into the recipient spinal cord was detected by the PCR method. Transplanted Schwann cells migrated into the recipient spinal cord both rostrally and caudally at a distance of 2 mm from the graft-host interface until 21 days after transplantation. At 28 days after transplantation, the Schwann cells migrated rostrally at a distance of 2 mm and caudally at a distance of 4 mm. C57BL/6-CEA sciatic nerve was transplanted to BALB/C mice as the allogenic transplant. CEA DNA was detected until 14 days after transplantation, but disappeared at 21 days. In addition, C57BL/6-CEA sciatic nerves were transplanted into Wistar rats to study xenogenic transplantation. The CEA band disappeared at 10 days after transplantation. In conclusion, by using CEA transgenic mice and the PCR method, we could evaluate the mobility of Schwann cells which are thought to play an important role in axonal regeneration.

Animals↗

PubMed1995

Experimental scoliosis induced by rib resection in chickens.

Factors which affected the severity of scoliosis induced by rib resection were examined. Seventy chickens were divided into a rib transection group and a rib resection group with seven subgroups, according to the number of ribs treated and the age at surgery, and examined radiographically until 20 weeks postoperatively. Rib transection group chickens showed fusion at the transected site and no marked scoliosis. In the rib resection group, the more ribs resected and the younger the age at operation, the more severely the scoliosis developed. Bone regeneration at the resection site made the progression of scoliosis milder. These findings indicate that the age at rib resection, the number of ribs that are operated on, and nonunion of the resected sites play important roles in the progression of scoliosis induced by rib resection.

Age Factors↗