PubMed Health⌕ Search

Biomedical subjects

Hisatoshi Baba

Publications and source records attributed to Hisatoshi Baba.

26 records · Page 2Linked to original sources
PubMed2004

Relation between vertical orientation and stability of acetabular component in the dysplastic hip simulated by nonlinear three-dimensional finite element method.

In acetabular dysplasia, more vertical orientation of the acetabular component is often used to minimize the superolateral bone grafting. This study was designed to determine the effects of vertical orientation of the cup on the stability and polyethylene wear of the acetabular component in uncemented total hip arthroplasty (THA). Three-dimensional finite element models of the hemipelvis with dysplastic acetabulum were developed. Metal-backed hemispherical cups were placed in the true acetabulum with abduction angles of 35, 45, 55, and 65 degrees. It was found that more vertical orientation of the cup was associated with larger relative motion of the metal shell between the acetabulum and metal shell. Furthermore, tilting and torsional shear stresses in the model of the cup abduction angle of 65 degrees were found to be 1.7 times larger than that in the model with 35 degrees at the bone-metal shell interface. More vertically oriented cups caused larger contact stresses at the articulating surfaces of the polyethylene liners. The results suggest that the abduction angle of the acetabular component significantly influences cup loosening and polyethylene wear in THA.

Acetabulum↗
PubMed2004

Metabolic neuroimaging of the cervical spinal cord in patients with compressive myelopathy: a high-resolution positron emission tomography study.

OBJECT: The authors conducted a study to examine whether high-resolution [18F]fluorodeoxyglucose (FDG)-positron emission tomography (PET) could be used to visualize deterioration of cervical spinal cord function associated with various degrees of compression and to determine its potential usefulness during assessment of compressive myelopathy. METHODS: In 23 patients requiring decompressive surgery for myelopathy FDG-PET was performed. The preoperative findings of high-resolution FDG-PET were compared with the neurological scores and magnetic resonance (MR) imaging findings. The preoperative standardized uptake value (SUV) of FDG utilization rate of the cervical cord correlated with the pre- (r = 0.497, p = 0.016) and postoperative neurological scores (r = 0.595, p = 0.003), as well as with the rate of neurological improvement postoperatively (r = 0.538, p = 0.008). The FDG utilization rate did not correlate with the high signal intensity on T2-weighted MR images. CONCLUSIONS: Analysis of these results indicates that high-resolution FDG-PET imaging provides useful qualitative and quantitative estimates of impaired metabolic activity of the compromised cervical cord that correlate closely with the severity of neurological dysfunction.

Adult↗
PubMed2003

Increased expression of neurotrophins and their receptors in the mechanically compressed spinal cord of the spinal hyperostotic mouse (twy/twy).

The purpose of the present study was to identify any compensatory changes at the site of chronic compression of the spinal cord and neighboring segments. For this purpose, serial immunohistochemical and immunoblot analyses were performed for the expression levels of endogenous brain-derived neurotrophic factor (BDNF), neurotrophin (NT)-3, and their receptors, trkB and trkC in 24 tip-toe walking Yoshimura mice (twy/twy) aged 12-24 weeks. The twy mouse exhibits spontaneous calcified deposits posteriorly at the C1-C2 level, compressing the spinal cord. Immunoreactivities for BDNF, NT-3, trkB and trkC were preferentially localized in the gray matter, particularly in the anterior horn cells. In 24-week-old twy mice with severe compression, expression levels of these neurotrophins at the site of maximal compression were significantly lower than at the less- or non-compressed sites. In contrast, the expression levels of BDNF, NT-3, trkB and trkC were significantly higher at the rostral and caudal sites immediately adjacent to the maximal compression site. No such changes were noted in 12-week-old twy mice or in control Institute of Cancer Research mice. Our results suggest that overexpression of BDNF, NT-3, trkB and trkC in motoneuron areas neighboring the site of mechanical compression may represent compensatory changes in response to the compromised neuronal function at the level of compression, and that these proteins possibly contribute to neuronal survival and plasticity.

Age Factors↗
PubMed2003

Lumbar epidural abscess causing septic shock: case report.

This case report describes a lumbar epidural abscess that caused septic shock. A 48-year-old woman who developed a high temperature was diagnosed as having a respiratory tract infection. She became unconscious the next day and was transferred to the intensive care unit for monitoring and treatment. She complained of increasing lower back pain as consciousness improved. Magnetic resonance images of the lumbar spine showed an abscess shadow between the vertebral body and dura mater at the level of L3-S1. Surgical drainage of the epidural abscess was performed as an emergency procedure, and the patient recovered immediately. The primary source of the epidural abscess was probably the respiratory tract infection, which spread to the epidural space through hematogenous dissemination. The initial treatment of the epidural abscess was rest and antibiotics, but surgical treatment was needed to save the patient because of septic shock.

Bronchitis↗
PubMed2002

Progressive changes in neurofilament proteins and growth-associated protein-43 immunoreactivities at the site of cervical spinal cord compression in spinal hyperostotic mice.

STUDY DESIGN: Immunohistochemical examination of the expression and localization of neurofilament (NF) proteins and growth-associated protein (GAP)-43 in spinal hyperostotic (twy/twy) mice with progressive compression of the cervical spinal cord. OBJECTIVE: To determine the biologic functions of NF proteins and GAP-43 in the mouse cervical spinal cord during chronic mechanical compression. SUMMARY OF BACKGROUND DATA: The pathologic and repair process in the chronically compressed spinal cord are understood poorly. The present authors hypothesized that there existed an increased expression of NF proteins and GAP-43 in twy/twy mice during the lengthy period of spinal cord compression, which resembles compressive myelopathy. METHODS: The cervical spinal cords of 54 twy mice (aged 8 weeks [n = 18], 14 weeks [n = 18], and 20 weeks [n = 18]) and 18 control animals were examined histologically. Using appropriate antibodies, sections were also stained immunohistochemically for NF proteins and GAP-43. RESULTS: Separation of the myelin sheath from the axon and axonal swelling with deformation were detected in the anterior and lateral funiculi of the spinalcords of 20-week-old twy/twy mice. No such changes were noted in 8-week-old twy mice. In twy/twy mice aged 8 and 14 weeks with mild-to-moderate compression, weak immunoreactivities (mainly in the white matter) for NF proteins and GAP-43 were noted; however, in 20-week-old twy/twy mice, these axons stained strongly positive and immunoreactive swollen axons were present. The relative area of GAP-43 immunoreactive axons gradually increased between 8 and 20 weeks in each column, particularly in the anterior and lateral funiculi in the contralateral side of compression. CONCLUSIONS: The results showed that the expression of NF proteins and GAP-43 in the white matter increased proportionally with the magnitude of spinal cord compression, and indicated the possible involvement of GAP-43 in both axonal degeneration and repair processes in the chronically compressed spinal cord.

Aging↗
PubMed2002

Mechanism of destructive pathologic changes in the spinal cord under chronic mechanical compression.

STUDY DESIGN: A histologic and histochemical study was performed both in the autopsy of a human patient with cervical spinal cord compression caused by ossification of the posterior longitudinal ligament and in a tiptoe-walking Yoshimura mouse model of progressive cervical cord compression. OBJECTIVES: To clarify the mechanism of destructive pathologic changes in the spinal cord under chronic mechanical compression. SUMMARY OF BACKGROUND DATA: Under chronic compression, the spinal cord exhibits destructive changes considered to be causes of profound and irreversible motor paresis. Recently, some investigators have found that apoptosis in acute spinal cord injury induces both secondary degeneration at the site of injury and chronic demyelination of tracts away from the site of injury. However, the mechanism responsible for these destructive spinal cord changes under chronic compression remains unclear. METHODS: The spinal cord was examined histologically, and an attempt was made to detect apoptotic cells using terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling in both the autopsy of a human patient and tiptoe-walking mice exhibiting spinal cord compression. RESULTS: Apoptotic cells were observed in the chronically compressed spinal cord in both the autopsy of a human patient and model mice. In tiptoe-walking mice exhibiting spinal cord compression, descending degeneration in the anterior and lateral columns and ascending degeneration in the posterior column were observed. The distribution of oligodendrocytes with positive results from terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling was similar to that for degeneration of the long tracts. CONCLUSIONS: Spinal cord cell apoptosis may produce destructive changes in the spinal cord under chronic compression, with a resulting irreversible neurologic deficit.

Aged↗
PubMed2002

Joint proprioception before and after total knee arthroplasty.

To investigate the effects of total knee arthroplasty on joint proprioception, the absolute angular error of the knee in 38 consecutive patients before and after total knee arthroplasty for osteoarthritis and in 23 age-matched control subjects were examined. Varus and valgus laxity of the knee and muscle strengths of the thigh were measured using appropriate instruments. There were no significant differences in absolute angular error before and after total knee arthroplasty, independent of retaining or substituting the posterior cruciate ligament. The absolute angular error of the knee with a normal appearing anterior cruciate ligament was larger than that with a missing anterior cruciate ligament before total knee arthroplasty and decreased significantly after surgery. The absolute angular error correlated with the varus and valgus laxity of the knee, but did not correlate with the strength of thigh muscles after total knee arthroplasty. These results suggest that deficiency of the anterior cruciate ligament may not adversely affect proprioception in severe knee osteoarthritis. In addition, proper ligament balance may partly contribute to better proprioception after total knee arthroplasty.

Aged↗