Biomedical subjects

Tsuneo Takebayashi

Publications and source records attributed to Tsuneo Takebayashi.

13 recordsLinked to original sources

PubMed2007

Electrophysiologic changes in dorsal root ganglion neurons and behavioral changes in a lumbar radiculopathy model.

STUDY DESIGN: The DRG neuron was electrophysiologically investigated using a rat model with constriction of the proximal site of the DRG. OBJECTIVES: To investigate the pathomechanisms of lumbar radiculopathy, we established a rat model with constriction of the proximal site of the DRG. And to characterize the DRG neurons in the rat model of lumbar radiculopathy, the physiologic properties regarding action potential, Na, and K current of the DRG neurons were analyzed through the use of patch clamp recordings. SUMMARY OF BACKGROUND DATA: In lumbar root constriction models, properties of secondary afferent neurons in the dorsal horn have been investigated. However, the electrical properties of DRG neuron have not been well investigated. METHODS: To compare the excitability of DRG neurons between root constriction models and sham, we examined the threshold current, action potential (AP) threshold, resting membrane potential (RMP), afterhyperpolarization (AHP), action potential duration 50 (APD50), action potential amplitude, maximum rise time of AP, and pattern of discharges evoked by depolarizing current. We also examined the peak Na current and steady-state Na and K currents with the voltage clamp technique. RESULTS: The rats in the root constriction group demonstrated mechanical allodynia and thermal hyperalgesia. In measurement of the action potential, lower threshold current, more depolarized RMP, larger AHP, and prolonged APD50 were measured in the root constriction neurons compared with the sham group. The incidence of sustained burst was significantly higher in root constriction neurons. The Na current in root constriction neurons was markedly larger. There were no significant differences in K current density and voltage dependency. CONCLUSIONS: The constriction of lumbar root increased excitability and Na current amplitude of DRG neurons. These findings indicate that lumbar radicular pain may be associated with increased excitability of involved DRG neurons.

Action Potentials↗

PubMed2007

Plasma neuropeptides in patients undergoing lumbar discectomy.

STUDY DESIGN: A prospective analysis of patients with lumbar disc herniation (LDH). OBJECTIVES: To determine the role of neuropeptides as a biochemical signature of pain states in patients with LDH. SUMMARY OF BACKGROUND DATA: Increases in the plasma level of neuropeptides have been reported in patients suffering from a variety of painful conditions. However, there is no such report on patients with LDH. METHODS: From a total of 27 patients with a single-level LDH, blood samples were collected before and 3 weeks after lumbar discectomy. Plasma levels of alpha calcitonin gene-related peptide (CGRP), galanin, neuropeptide Y, and substance P were determined by using enzyme-linked immunosorbent assay. The association or correlation between preoperative concentration of plasma neuropeptides and gender, patients' age, and VAS were analyzed statistically. Also, the concentration of plasma neuropeptides was compared before and after lumbar discectomy. RESULTS: Preoperative plasma levels of CGRP were correlated significantly with the extent of sciatica as determined by VAS. In addition, plasma levels of CGRP and galanin significantly decreased after lumbar discectomy in line with the disappearance of pain symptoms. CONCLUSIONS: These findings indicate the role of plasma CGRP and possibly galanin as a systemic neurochemical signature of pain states in patients with LDH.

Adolescent↗

PubMed2007

Quantitative analysis of sensory functions after lumbar discectomy using current perception threshold testing.

A Neurometer device is an electrical nerve stimulator used to determine the current perception threshold (CPT) evoked by stimulating A-beta fibers at 2,000 Hz, A-delta fibers at 250 Hz and C fibers at 5 Hz. CPT evaluation is used for analyzing peripheral nerve dysfunction. In this study, the sensory disturbance of the lower-extremity was quantitatively analyzed using CPT testing before and after lumbar discectomy. In 33 patients (L4/5: 16 and L5/S: 17), as subjective evaluations, tactile sensation and leg pain were assessed before and 2 weeks after surgery. In the subjectively improved group (n = 22), significant decreases in CPT at 2,000 and 250 Hz were noted postoperatively, whereas in the unchanged group (n = 11), no significant changes in CPT at any frequencies was noted. The leg pain improved in all patients. Likewise, CPT at 5 Hz, which stimulated C fiber, decreased significantly for both improved and unchanged groups. CPT measured by a Neurometer is very useful in assessing lower-extremity sensory functions before and after surgery for lumbar disc herniation.

Adult↗

PubMed2006

Effects of interleukin-1 beta, interleukin-6, and tumor necrosis factor on sensitivity of dorsal root ganglion and peripheral receptive fields in rats.

This study was designed to characterize the effects of low doses (0.5-5 ng) of pro-inflammatory cytokines, interleukin-1 beta (IL-1beta), interleukin-6 (IL-6), and tumor necrosis factor (TNF), on the neural activity of dorsal root ganglion (DRG) in rats. The purpose of this study was to examine the effects of cytokines (IL-1beta, IL-6, and TNF) on the somatosensory neural response of DRG. The release of inflammatory cytokines by an injured disc may play a critical role in pain production at nerve endings, axons, and nerve cell bodies. Herniated disc tissue has been shown to release IL-1beta, IL-6, TNF, and other algesic chemicals. Their effects on nerve endings in disc and adjacent tissue may lead to low back pain and their effects on dorsal root axons and ganglia may lead to sciatica. Exposed lumbar DRGs were investigated by electrophysiologic techniques. Sham (mineral oil), control (carrier solution), or IL-1beta, IL-6, or TNF at doses of 0.5, 1, and 5 ng were applied over the DRG. Baseline discharge rates as well as mechanosensitivity of the DRG and peripheral receptive fields were evaluated over 30 min. Applications of IL-1beta at 1 ng resulted in an increase in the discharge rate, 5 ng resulted in an increased mechanosensitivity of the DRG in group II units. Similarly, after 1 ng TNF applications, group II units also showed an increase in mechanosensitivity of DRG and peripheral receptive fields. At low doses IL-1beta and TNF sensitization of receptive fields were observed. The responses observed in the group II units indicate that a sub-population of afferent units might have long-term effects modifying the sensory input to the central nervous system. This study provides added evidence to the role of cytokines in modulating afferent activity following inflammation.

Animals↗

PubMed2006

Scoliosis in cat cry syndrome.

BACKGROUND: Cat cry syndrome is an autosomal disease accompanying abnormal deletion of chromosome 5 and occurs in only 1 of 50,000 neonates. Scoliosis has been reported as a skeletal complication in cat cry syndrome. The characteristics and causes of scoliosis in this rare syndrome are unknown. The purpose of this study was to present the characteristics of scoliosis in cat cry syndrome and to speculate on its causative mechanisms. METHODS: We report on 11 cases (5 boys and 6 girls) of cat cry syndrome. Detailed investigations of scoliosis, as well as physical and imaging examinations, were performed to characterize scoliosis and its causes. Average age at initial diagnosis of scoliosis was 4.3 years, and average age at final examination was 11.8 years. RESULTS: The incidence of scoliosis was as high as 73% (8/11). Most cases show a single right thoracic curve. Of the 8 patients with scoliosis, 3 patients who had increased muscular tone showed marked progression of scoliosis with growth. CONCLUSIONS: Muscular hypertonia may play a key role in the progression of scoliosis in cat cry syndrome.

Child↗

PubMed2005

Adjacent segment stenosis after lumbar fusion requiring second operation.

BACKGROUND: Whereas degeneration of the segment adjacent to lumbar fusion has been often seen on radiographs, a small number of patients with such degenerative changes undergo reoperation. Most follow-up studies have focused on adjacent segment disease based on analysis of radiographs. The present study was conducted to understand the pathology of reoperation cases of adjacent segment disease and factors associated with this condition. Operative indication was consistently restricted to patients with neurological involvement. METHODS: The subjects were 117 patients who had undergone posterior lumbar fusion and were followed for a minimum of 2 years (mean 7 years). Among them, nine patients (7.7%) required a second operation owing to symptomatic adjacent segment disease (stenosis). The reoperation rate was assessed in relation to sex, age, initial pathologic condition, and initial spinal fusion and decompression methods. Data were analyzed in a 2 x 2 cross contingency table using Fisher's exact probability test. A probability of <0.05 was defined as statistically significant. RESULTS: Of the variables examined, only multilevel fusion was associated with a high rate of reoperation with statistical significance (P < 0.04). Two patients (100%) suffering from loss of coronal balance (degenerative scoliosis) also required a second operation. CONCLUSIONS: The reoperation rate of 7.7% for adjacent segment disease in this study was consistent with the prevalence of adjacent segment stenosis in the literature. Given the risk of later occurrence of adjacent segment stenosis following multisegment posterolateral fusion, correction of coronal and sagittal balance, preventive decompression of the adjacent segment, or selective decompression without fusion may have to be considered as an additional or alternative procedure.

Adult↗

PubMed2004

The effects of epidural application of allografted nucleus pulposus in rats on cytokine expression, limb withdrawal and nerve root discharge.

This study investigated cytokine expression, behavioral and neurophysiologic changes in Lewis rats whose lumbar nerve roots were exposed to nucleus pulposus (NP). Allografted NP or fat was implanted over the left L5 nerve root. Sham rats had no NP or fat implantation. Control rats had no surgery. Rats were allowed to survive for 7 days and were tested daily for hind-paw mechanical and thermal withdrawal response (TWR). Granulation tissue was processed by immunohistochemistry for cytokines--interleukin 1 beta (IL-1beta), interleukin 6 (IL-6) and tumor necrosis factor (TNF). Neurophysiological response from the L5 nerve roots was also characterized after 7 days. Significant staining density for IL-1beta, IL-6 and TNF was observed in NP granulation tissue compared with fat and sham (p<0.05). However, there were no significant thermal and mechanical behavioral changes. TWR data computed as percentage-difference scores indicated no significant changes in withdrawal response between the four groups, although NP-treated group showed a trend of decreasing withdrawal latency. Comparison of combined percentage-difference scores revealed increased sensitivity in the NP group on days 4, 5 and 6, 7 when compared with control rats only, with no significant changes in the percentage-difference scores of fat and sham rats when compared to control. Neurophysiologically, the percentage increase in discharge rate in NP-treated rats was higher than control (p<0.05) but not higher than fat and sham rats. These results support the inflammatory nature of NP but offer limited support to NP-mediated thermal behavioral changes.

Animals↗

PubMed2004

Effects of nucleus pulposus on nerve root neural activity, mechanosensitivity, axonal morphology, and sodium channel expression.

STUDY DESIGN: This study analyzed the effects of autografted nucleus pulposus on nerve root axon morphology, neurophysiologic function, and sodium channel expression. OBJECTIVES: To investigate the chronic effects of the epidural implantation of nucleus pulposus on nerve root morphology, neural activity, ectopic discharge, mechanosensitivity, and sodium channel expression. SUMMARY OF BACKGROUND DATA: It has been reported that ectopic discharges were recorded antidromically from sural nerve on compressing nucleus pulposus exposed spinal nerves. However, it is not clear what the effects of nucleus pulposus are on ectopic discharges recorded directly from the spinal nerve roots. It is also not clear what the effects of nucleus pulposus are on the threshold pressure to provoke ectopic discharges in the spinal nerves. Sodium channel content increases in remodeling axons after nerve injury, but it is not clear what the effects of nucleus pulposus are on sodium channel expression in spinal nerve. METHODS: Forty-six male Sprague-Dawley rats were used, 20 in a nucleus pulposus-implanted group, 18 in a fat-implanted group, and 8 in a normal group. Fresh autografted nucleus pulposus or fat tissue was implanted into the dorsal epidural space at the L4-L5 disc level. On the 7th, 21st, or 42nd day, neurophysiologic recordings were made to determine nerve root response to compression. Nerve roots were then harvested to determine sodium channel protein concentration and histologic changes in the nerve root. The correlations between sodium channel density and neural activity and mechanosensitivity of dorsal root were analyzed statistically. RESULTS: Ectopic discharge rate was higher in nucleus pulposus 7-day group. Threshold pressure to evoke ectopic discharges was lower in the nucleus pulposus 7-day group, and higher in the nucleus pulposus 42-day group compared to the normal group. Sodium channel protein density increased in the nucleus pulposus 7-day and nucleus pulposus 21-day group compared to normal nerve. Sodium channel density changes were not correlated to threshold pressure. Ectopic discharge rate increased with increase of sodium channel density in the nerve roots. The number of axons with neuropathy increased in the nucleus pulposus 7-day and 21-day groups. CONCLUSIONS: Acute exposure of nerve root to nucleus pulposus resulted in increased number of axons with neuropathy, higher intensity of ectopic discharges on compression, and nerve mechanosensitization. Chronic exposure resulted in mechanical desensitization. Changes of sodium channel density were correlated to ectopic discharge rate.

Animals↗

PubMed2003

Vertebral body ischemia in the posterior spinal artery syndrome: case report and review of the literature.

STUDY DESIGN: A case of posterior spinal cord syndrome in which magnetic resonance images showed predominant T2 hyperintense signal in the adjacent vertebral body is reported. OBJECTIVES: To present the case for abnormal bone marrow magnetic resonance signal in the radiologic diagnosis of posterior spinal cord syndrome and to review its significance. SUMMARY OF BACKGROUND DATA: Infarction in the region of posterior spinal arteries has been rarely described. This is attributable not only to the infrequent occurrence of infarction of posterior spinal arteries, but also to a lack of well-established diagnostic procedures. It is of clinical value to define diagnostic images of posterior spinal cord syndrome, especially early in the course of the disease. METHODS: The subject was a 52-year-old man who was presented with acute nontraumatic myelopathy. Magnetic resonance imaging, performed serially after onset of the disorder from 5 hours to 11 months, was evaluated in comparison with neurologic findings. The literature was reviewed to discuss the magnetic resonance images of spinal cord infarction. RESULTS: The neurologic findings were consistent with posterior spinal cord syndrome. A magnetic resonance image taken at 5 hours after onset of the syndrome showed T2 hyperintense signal in the T12 vertebral body. At 3 days after onset, T2 hyperintense signal became obvious in the posterior portion of the spinal cord at T9-T12 vertebral levels. Follow-up magnetic resonance imaging at 41 days, 8 months, and 11 months showed a decrease in the size and intensity of the T2 signal change in the spinal cord and T12 vertebral body. In the literature, T2 hyperintense bone marrow signal was defined in one case of posterior spinal cord syndrome and seven cases of anterior spinal cord syndrome. CONCLUSIONS: Associated bone marrow abnormalities likely reflect the underlying pathology of the blood supply to the vertebral body, and may be an additional key sign for radiologic diagnosis of posterior spinal cord syndrome.

Acute Disease↗

PubMed2003

Osteoporosis in 5 elderly women with pubic osteolysis.

5 elderly women developed pubic osteolysis after spontaneous fracture of the pubic bone. Radiographs showed gradual progression of the osteolysis, followed by callus formation, and bone union after 4-5 months. Bone mineral density was low in all patients. White blood cell count, erythrocyte sedimentation rate, and C-reactive protein were normal. Urine deoxypyridinoline was high, but serum osteocalcin normal. Elderly women with spontaneous fractures and osteolysis of the pubic bone should be considered for evaluation of osteoporosis and treatment.

Aged↗

PubMed2002

The effect of varying impact energy on diffuse axonal injury in the rat brain: a preliminary study.

Diffuse axonal injury (DAI) is seen as widespread damage in the white matter of brain characterized by morphological changes to axons throughout the brain and brain stem. The current study attempted to investigate the effect of increasing impact energy on the presence and severity of DAI in corpus callosum (CC). DAI was induced in adult male Sprague-Dawley rats using an injury model adapted from Marmarou et al. in 1994. A 450-g cylindrical brass weight was dropped from three different heights (2.0 m, 1.5 m and 1.0 m) on to a metal helmet affixed to the skull of the rats. In the sham group, rats underwent a surgical procedure with no impact. After a 24-h survival period the animals were transcardially perfused. The brain was removed and the cerebral hemispheres were sectioned with a vibrotome and stained by silver impregnation technique. The CC of all the impacted rats showed DAI in the form of beaded axons, retraction balls and vacuole-like enlargements. The axonal injury was most severe in the 2-m group, while mildest in the 1-m group. In the sham group, axons appeared to be normal. This study demonstrates evidence of graded DAI depending on the impact energy. Such data is useful for mathematical modeling of axonal injury in rat brain using the same impact parameters and potential determination of injury thresholds for neural trauma.

Animals↗

PubMed2002

A quantitative analysis of sensory function in lumbar radiculopathy using current perception threshold testing.

STUDY DESIGN: Peripheral sensory functions in patients with radiculopathy resulting from lumbar disc herniation and in control individuals were analyzed using current perception threshold testing. OBJECTIVE: To evaluate the severity of sensory disturbance quantitatively in patients with lumbar radiculopathy. SUMMARY OF BACKGROUND DATA: Subjective evaluation of the severity of sensory disturbance associated with spinal disorders using conventional methods often is difficult. Current perception threshold evaluation is a recently proposed method for studying peripheral nerve dysfunction. This is a quantitative sensory test for analyzing functions of A-beta, A-delta, and C fibers. METHODS: In this study, 48 patients with lumbar radiculopathy resulting from lumbar disc herniation were examined. The mean age of the patients was 37.9 years. All the patients had pain distribution from the compression of one lumbar nerve root (L5 or S1), and unequivocal unilateral disc herniation of the corresponding level was shown by magnetic resonance imaging. Eleven healthy volunteers were used as control subjects. Their mean age was 38.2 years. Current perception threshold evaluation using a Neurometer device was performed at three frequencies: 2000, 250, and 5 Hz. The stimulus sites were located on the dorsal side of the first metatarsus (the L5 dermatome) and the dorsal side of the fifth metatarsus (the S1 dermatome). These sites were investigated on both legs in all the patients and control subjects. The intensity of pain was scored using a visual analog scale. RESULTS: In the control group, there were no significant differences in current perception threshold values at any frequency between the left and right legs. In the patient group, the current perception threshold values in the affected legs were significantly higher than those in the contralateral legs at all frequencies. The current perception threshold values in the affected legs in the patient group were significantly higher than those in the control subjects at 2000 and 250 Hz, whereas there were no significant differences at 5 Hz. The current perception threshold values in the affected legs were significantly higher in patients with hypesthesia than in those without hypesthesia at 2000 and 250 Hz, and in patients with severe pain than in those with less pain at 5 Hz. CONCLUSIONS: Current perception threshold testing showed that the functions of A-beta, A-delta, and C fibers deteriorated in patients with lumbar radiculopathy. This technique may be useful for quantifying sensory nerve dysfunction in patients with radiculopathy.

Adolescent↗

PubMedDate not supplied

Biomechanical characteristics of the lateral ligament of the ankle joint.

The purpose of this study was to investigate the biomechanical properties of the lateral ankle ligaments and to correlate these properties with the distribution of mechanoreceptors in the ligaments reported previously. Biomechanical tensile tests were performed by using a video dimension analyzer to monitor the distortion of the lateral ligament at the pole and center in the animals. The mean upward slope of the load-elongation curves of the pole group was 38.1+/-14.2, and that of the center group was 79.1+/-6.5. The pole of the ligaments tended to be elongated more than the center. These biomechanical results suggest that mechanoreceptors in the pole of the ligaments, compared with those in the center, may receive more mechanical stress and be effective in monitoring of tension applied to the ligament.

Animals↗