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Biomedical subjects

Y Mikawa

Publications and source records attributed to Y Mikawa.

At least 19 recordsLinked to original sources
PubMed2005

Pathology of experimental disuse muscular atrophy in rats.

The relationship between structural changes and hyaluronic acid (HA) content in muscular atrophy is unknown. The objective of our study was to conduct multifaceted evaluations of the change in muscle extensibility in muscular atrophy, in terms of morphological aspects as well as from a biochemical viewpoint, including changes in intercellular substances. Using a muscular atrophy model of the soleus muscle in the cast-fixed limbs of Wistar rats, we examined changes in HA accompanying muscular atrophy. Compared with controls, the cast-fixed limbs showed histological evidence of muscular atrophy and electron microscopy indicated destruction of the fasciae. Measurement of the HA level in muscle tissue from cast-fixed rats indicated a reduction in concentration per unit of weight. In contrast, serum HA concentrations increased in the cast-fixed group compared with the control group, suggesting that HA present in the fasciae was released into the blood stream during muscular atrophy.

Animals↗
PubMed2004

Vascularized nerve grafts for the treatment of large nerve gap after severe trauma to an upper extremity.

We reviewed the clinical outcomes of vascularized nerve grafts for the repair of large nerve gaps (longer than 20 cm) after severe trauma to an upper extremity. Six patients who underwent vascularized sural nerve grafting (five to the median nerve and one to the ulnar nerve) with a monitoring skin flap were evaluated. The length of the vascularized sural nerve grafts ranged from 20 to 30 cm, with a mean length of 23.3 cm. All but one of the monitoring skin flap grafts was successful. In those patients for whom the monitoring skin flap graft was successful, the mean static-2PD at the corresponding fingertip was 14.2 mm (range 10-20 mm). Evaluation of these patients with the Semmes-Weinstein test produced the following results: filament 6, two patients; filament 10, three patients. The results of this study show that vascularized sural nerve grafting should be considered as a clinical alternative for nerve reconstruction in patients with nerve defects longer than 20 cm.

Adult↗
PubMed2002

Ruptured abdominal aortic aneurysm associated with a psoas abscess.

A case of abdominal aortic aneurysm infected by Salmonella dublin is presented. Computed tomography (CT) revealed an abdominal aortic rupture associated with a psoas abscess. An axillo-femoral bypass was performed. The aneurysm and the psoas abscess were resected.

Aneurysm, Infected↗
PubMed2001

Traumatic T9 burst fracture in an 8-month-old infant: incomplete neurologic deficit and its recovery.

STUDY DESIGN: Case report of a rare burst fracture of the ninth thoracic vertebra in an 8-month-old male infant. OBJECTIVES: To describe a rare traumatic lesion in an infant. SUMMARY OF BACKGROUND DATA: There are two reported cases of fracture-dislocation in an infant in the literature, both of which were managed surgically. However, this is the first reported clinical case of burst fracture in an infant. METHODS: The patient was treated conservatively and observed for 40 months. His spine was examined by using roentgenography and magnetic resonance imaging. His neurologic condition was evaluated by clinical examination and somatosensory-evoked potential (SEP). RESULTS: The infant became ambulant with no need for support 2 years after injury. At that time, the burst vertebra was remodeling gradually and showed no spinal deformity. CONCLUSION: Fracture-dislocation of the spine with neurologic deficit requires surgical management. However, burst fracture can be managed conservatively, provided the neurologic condition improves.

Accidents, Traffic↗
PubMed2001

[Blood concentrations and side effects of tacrolimus in a living renal transplantation].

In a living renal transplantation, the recipients are administered an immunosuppressive agent preoperatively. The drug exhibits a high incidence of side effects of special note. We examined the side effects of tacrolimus to evaluate the postoperative management of living renal transplantation. Hypertension, hyperglycemia, tachycardia and chest pain were found as the side effects. The blood concentration should be measured frequently to maintain the effective blood concentration and to prevent the side effect.

Adult↗
PubMed2001

[Usefulness of epidural administration of ketamine for relief of postherpetic neuralgia].

Four patients with postherpetic neuralgia had their pain alleviated by epidural administration of ketamine. No oral non-steroidal anti-inflammatory drugs and anti-depressant drugs were effective in all cases. Lidocaine or bupivacaine was administered epidurally to all four patients. When these patients stated that they did not feel pain reduced, they received epidural infusion of ketamine at doses from 5 mg to 20 mg with lidocaine or bupivacaine and their postherpetic neuralgia was controlled. Therefore with these cases, we suspect that epidural administration of ketamine, an antagonist for N-methyl-D-aspartic acid receptor, could be an effective and useful alternative treatment in a patient with refractory postherpetic neuralgia.

Aged↗
PubMed2001

[Anesthetic management of a patient with von Recklinghausen disease complicated with spinal tumor and severe spinal deformity].

We had three occasions of giving anesthesia to a patient with von Recklinghausen disease complicated with spinal tumor and spinal deformity. A 49-year-old male patient who had suffered from von Recklinghausen disease since 35 years of age developed slight low respiratory function due to neurofibroma in the spinal canal and the paravertebral lesion and severe kyphoscoliosis in the lumbar spine which were checked by lumbar X-ray, abdominal ultrasonography and computed tomography during the preoperative period. Transurethral biopsy of the bladder tumor, internal urethrotomy for the urethral stricture and vesical lithotripsy for the bladder stone were performed under general anesthesia. Elevated position of his head and lower extremities and slight right lateral decubitus position were employed during anesthetic induction and semi-Trendelenburg's position during anesthetic maintenance. Convalescence after each operation was uneventful. He was comfortable and had a safe perioperative course. He showed no unward change in neurological symptoms during the post-operative period. This case suggests that we must take the complication such as spinal tumor and spinal deformity into consideration for anesthetic management of patients with von Recklinghausen disease and select the appropriate anesthetic method and patient's position.

Anesthesia, General↗
PubMed2000

The effect of age on inflammatory responses and nerve root injuries after lumbar disc herniation: an experimental study in a canine model.

STUDY DESIGN: An experimental investigation on the effect of age on pathologic events surrounding the herniated disc and at the adjacent nerve root. OBJECTIVES: To investigate the role of age on the inflammatory responses and nerve root damage surrounding a sequestered lumbar disc fragment using a dog model. SUMMARY OF BACKGROUND DATA: Lumbar disc herniation is manifested in patients by variable clinical findings, natural history, and resorption phenomena in which the variability is particularly noted among patients with different ages. There are no previous reports on the effect of age on pathologic events induced by the herniated disc. METHODS: Six beagle dogs, including two animals of each age group of 6, 12, and 24 months (human equivalent ages of 10, 15, and 24 years), were used in this study. The dogs underwent L4-L5, L5-L6, and L6-L7 laminotomy and discectomy under general anesthesia. An autologous intervertebral disc from the tail was divided into anulus fibrosus and nucleus pulposus fragments. The anulus fibrosus and nucleus pulposus fragments were placed in the anterolateral epidural space of L5-L6 and L6-L7, respectively. The L4-L5 discectomy site served as a control. Dogs were killed at 12 weeks after surgery. The lumbar spine was removed en bloc, and histologic sections were prepared consecutively and examined. RESULTS: In the nucleus pulposus group at L6-L7, neovascularity, and intensive infiltration of lymphocytes, macrophages, and fibroblasts were observed surrounding the nucleus pulposus fragment in the 24-month-old group only. Degenerative changes of the nerve root fibers were observed in the 24-month-old group only. In the control and anulus fibrosus groups at L4-L5 and L5-L6, there were no marked inflammatory reactions in all age groups. The nerve root fibers around the anulus fibrosus were normal in all age groups. CONCLUSIONS: There is an effect of age on the inflammatory response and nerve root injury caused by the herniated disc. The apparent neuroprotective mechanism in the young animal, and the apparent inflammatory and resorption changes of the nucleus pulposus fragment in the older animal are quite intriguing.

Aging↗
PubMed2000

Characterization of the recombinase activating gene-1 and 2 locus in the Japanese pufferfish, Fugu rubripes.

The recombinase activating genes (RAG1 and RAG2) encode nuclear proteins that directly mediate the mechanism V(D)J recombination process that occurs in T- and B-lymphocytes. The expression of RAG1 and RAG2 is required for the proper development of maturing lymphocytes. To identify evolutionary conserved regulatory regions adjacent to both genes we isolated and sequenced a cosmid clone containing 43kb of genomic DNA of the Japanese pufferfish, Fugu rubripes. Fugu has a haploid genome of 400Mb and contains the same number of genes as the genome of higher vertebrates. With low abundance of repetitive DNA, the genome of the pufferfish has shown to be ideal for comparative genomics. We found three complete genes, RAG1, RAG2 and ACS (a possible homologue of the plant 1-aminocyclopropane-carboxylate synthase gene). There is also the 5' exon of a prohormone convertase gene, possibly PACE4. The genetic structure of both RAG1 and RAG2 is identical to that found in other fish, but the size of the intergenic region is smaller in Fugu. Expression analysis by RT-PCR shows the presence of RAG transcripts in kidney of adult Fugu. The human ACS was identified in a cosmid assigned to chromosome 11p11, which is close to the location of the RAGs (11p12). This indicates conservation of linkage between human and pufferfish.

Animals↗
PubMed1999

Intraosseous epithelioid malignant peripheral nerve sheath tumor of the phalanx. Case report.

We report the first case of intraosseous epithelioid malignant peripheral nerve sheath tumor (MPNST) occurring in the phalanx. The patient was a 50-year-old Japanese man with an intramedullary lytic lesion of the proximal phalanx. Microscopically, the tumor was composed of epithelioid cells or polygonal cells, forming large cell nests with central necrosis. Most tumor cells were diffusely and strongly immunopositive for S-100 protein and vimentin, and negative for cytokeratin, epithelial membrane antigen, carcinoembryonic antigen, alpha-smooth muscle actin, and HMB-45. Laminin-positive material was discontinuously demonstrated between the individual tumor cells. Electron microscopy showed prominent external lamina. Our case indicated that laminin is useful for differentiating epithelioid MPNST from metastatic carcinoma and malignant melanoma.

Bone Neoplasms↗
PubMed1997

Cervical spinal cord compression in hereditary multiple exostoses. Report of a case and a review of the literature.

Spinal cord compression is an extremely serious complication of hereditary multiple exostoses (HME). A case of HME with compression of the cervical spinal cord is reported. Complete recovery following surgery was achieved. A review of the relevant literature revealed 51 previous cases of HME with cord/cauda equina compression. Most patients were under 30 years of age with more men affected than women. The family history was positive in 60%. The cervical and thoracic areas were predominantly affected, with the symptoms usually developing slowly. Recovery following surgery is to be expected in the majority of cases. In patients with HME and suffering from neurological symptoms, the possibility of spinal cord compression should be considered. Prompt diagnosis and surgical excision provide the best prognosis.

Adolescent↗
PubMed1997

Cervical myelo-radiculopathy in athetoid cerebral palsy.

Cervical myelopathy complicating athetoid cerebral palsy has not been adequately highlighted in the literature. We report two cases of patients with athetoid cerebral palsy and long histories of involuntary movements who developed cervical myelo-radiculopathy. Dystonic athetoid neck movements may cause excessive axial neck rotation as well as flexion and extension movements of the spine. These repetitive exaggerated movements may result in early degenerative changes of the vertebrae which may enhance the myelo-radiculopathy. The two patients were treated with combined anterior and posterior fusion with satisfactory results. They were bedridden preoperatively but have since started walking with or without a cane. We conclude that combined anterior and posterior fusion is the treatment of choice for severe myelopathy complicating athetoid cerebral palsy.

Adult↗
PubMed1997

Organization of the Fugu rubripes Hox clusters: evidence for continuing evolution of vertebrate Hox complexes.

The clustered organization of Hox genes provides a powerful opportunity to examine gene gain and loss in evolution because physical linkage is a key diagnostic feature which allows homology to be established unambiguously. Furthermore, Hox genes play a key role in determination of axial and appendicular skeletal morphology and may be a key component of the evolution of diverse metazoan body forms. Despite suggestions that changes in Hox gene number played a role in evolution of metazoan body plans, there has been a general lack of evidence for such variation amongst gnathostomes (or indeed any vertebrate) and it has therefore been widely assumed that differential regulation may be the key element in all vertebrate Hox evolution. We have studied the Hox gene clusters of a teleost fish, Fugu rubripes, to test the possibility that Hox organization may have varied since the origin of jawed vertebrates. We have identified four Hox complexes in Fugu and found an unprecedented degree of variation when compared with tetrapod clusters. Our data show that: Fugu clusters are widely variant with respect to length; at least nine genes have been lost; there is a new group-2 paralogue; and pseudo-gene remnants of group-1 and group-3 paralogues were found in the Hoxc complex, when compared with the present mammalian clusters. We show that gene loss after duplication of the prototypical vertebrate Hox clusters is a key feature of both tetrapod and fish evolution.

Amino Acid Sequence↗
PubMed1996

Morphometric analysis of the lumbosacral nerve roots and dorsal root ganglia by magnetic resonance imaging.

STUDY DESIGN: Lumbosacral nerve roots and dorsal root ganglia in relation to surrounding bony structures in normal subjects were investigated using magnetic resonance imaging. OBJECTIVES: This study determined the normal anatomic parameters of the lumbosacral nerve root and dorsal root ganglion, to which degenerative or pathologic changes may be compared. SUMMARY OF BACKGROUND DATA: In the previous literature, most authors have used various modalities in either cadavers or symptomatic patients to study the anatomic details of the lumbar nerve roots and dorsal root ganglia. The data in the literature are conflicting, mainly because of individual variations and different degrees of degenerative change in the spine. METHODS: Twenty male volunteers who had no back pain or radiculopathy underwent magnetic resonance imaging. Ages ranged from 22 to 38 years, with a mean of 30.4 years. T1-weighted coronal magnetic resonance images were taken from L1 to S1. Two hundred thirty-three nerve roots were examined, including 36 L1, 40 L2, 40 L3, 39 L4, 40 L5, and 38 S1. nerve roots Measurements were determined using a computer digitizer. RESULTS: The nerve root origin was at a more cephalad level for the caudad nerve roots, particularly the S1. The take-off angels acutely changed at L1 and S1. The length of the nerve roots increased progressively to a maximum at L5, and decreased at S1. The center of the dorsal root ganglion was positioned more cephalad at S1. The average dimension of the dorsal root ganglion gradually increased from L1 to S1. The most striking difference was in the S1 root, which takes off more cephalad, at a more vertical angle, and has the shortest length of any of the nerve roots. The S1 dorsal root ganglion was also unique in that it was the largest and more frequently located intraspinally. CONCLUSION: The anatomy of the lumbar nerve roots and dorsal root ganglia and their relations to bony structures have been better defined in this study. Because of its more medial location, S1 radiculopathy may involve both the nerve root and dorsal root ganglion as a result of either disc herniation or degenerative L5-S1 facet changes. The relatively larger dorsal root ganglia and the greater dorsal root ganglion/foramen height ratios in the lower lumbar region may explain the higher incidence of L5 or S1 radiculopathy, particularly given the propensity to disc degeneration and intervertebral foraminal narrowing in the lower lumbar region.

Adult↗
PubMed1996

Role of ICAM-1 and LFA-1 in endotoxin-induced uveitis in mice.

The effect of monoclonal antibodies against adhesion molecules on the development of endotoxin-induced uveitis (EIU) and interleukin-1 (IL-1)-enhanced EIU were studied. When endotoxin or IL-1 was injected into C3H/HeN mice, the expression of intercellular adhesion molecule-1 (ICAM-1) on the ciliary body was up-regulated as determined by immunohistochemical assay. However, these agents did not alter lymphocyte function-associated antigen-1 (LFA-1) expression on leukocytes when whole blood cells were analyzed with flow cytometry. Monoclonal anti-ICAM-1 antibody or anti-LFA-1 antibody was intraperitoneally administered to C3H/HeN mice simultaneously with endotoxin, and the effect on the development of EIU was studied. The cell number in aqueous humor and frequency of posterior synechiae were markedly decreased in EIU when either antibody was administered. However, protein concentration in the aqueous humor was not statistically reduced by the injection of these antibodies. In the model of IL-1 enhanced EIU, not only the cell number and frequency of posterior synechiae but also protein concentration were decreased. Moreover, there were no differences between these two antibodies in the effect on EIU, whereas anti-LFA-1 antibody was more effective than anti-ICAM-1 antibody in IL-1-enhanced EIU.

Animals↗
PubMed1994

Elastin in the human posterior longitudinal ligament and spinal dura. A histologic and biochemical study.

STUDY DESIGN: A histologic and biochemical study of elastin in the posterior longitudinal ligament and spinal dura was performed using autopsy cadavers. OBJECTIVE: To provide a rationale for resiliency of the PLL and the spinal dura. SUMMARY OF BACKGROUND DATA: Among the spinal ligaments, the nuchal ligament and the ligamentum flavum have a very high elastin content, and some biochemical and morphologic studies of these ligaments have been published. No reports on the elastin content in the posterior longitudinal ligament or spinal dura have been published. METHODS: Specimens of the posterior longitudinal ligament and the dura collected from three cadavers were studied histologically. For quantitative analysis of elastin and collagen, the posterior longitudinal ligament specimens were collected from 22 cadavers and the dura specimens from 20 cadavers. Elastin was extracted using the hot alkali method of Lansing et al. RESULTS: The elastic fibers in the posterior longitudinal ligament generally were arranged parallel in the cephalocaudal direction, whereas the fibers in the spinal dura had a more multidirectional arrangement. The elastin content of the posterior longitudinal ligament averaged 7.3% of the total dry weight and that of the spinal dura was 7.1% for the ventral aspect and 13.8% for the dorsal aspect. The elastin content of the spinal dura was about two times higher in all dorsal specimens than in the corresponding ventral specimens. The elastin content of the lower thoracic region was higher than that of any other region. The amino acid composition of the elastin in the posterior longitudinal ligament and spinal dura was similar to that previously determined in other spinal ligaments.

Aged↗
PubMed1994

Cerebellar hemorrhage complicating cervical durotomy and revision C1-C2 fusion.

STUDY DESIGN: A case of cerebellar hemorrhage complicating cervical durotomy and revision C1-C2 fusion is reported. There has been only one report on cerebellar hemorrhage after cervical durotomy. SUMMARY OF BACKGROUND DATA: The patient became comatose approximately 16 hours after surgery. According to a review of the recovery room records, the patient's cerebellar hemorrhage probably occurred some time within the first 10 hours after the procedure and not during the operation. METHODS: The authors reviewed reports on complicated cerebellar hemorrhage, and the causative factors were studied. CONCLUSION: Postoperative drainage of cerebrospinal fluid, especially when negative pressure is applied, may play a role in the occurrence of cerebellar hemorrhage.

Aged↗