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Biomedical subjects

T Sakou

Publications and source records attributed to T Sakou.

At least 55 records · Page 3Linked to original sources
PubMed1997

Bone morphogenetic protein receptors and activin receptors are highly expressed in ossified ligament tissues of patients with ossification of the posterior longitudinal ligament.

Ossification of the posterior longitudinal ligament (OPLL) is a pathological ossification in the spinal ligament, with formation of ectopic bone mainly through endochondral ossification. Bone morphogenetic proteins (BMPs) and activins are multifunctional proteins that belong to the transforming growth factor-beta superfamily and that have been implicated in the formation of new bone and cartilage. BMPs and activins signal via type I and type II receptors for BMPs (BMPRs) and activins (ActRs), respectively. OP-1/BMP-7 binds to BMPR-II and ActR-II and forms complexes with BMPR-IA and -IB and ActR-I. We studied the expression of BMPR-IA, -IB, and -II, ActR-I, ActR-II, and OP-1/BMP-7 by immunohistochemistry in ossified ligament tissues of patients with OPLL and control ligament tissues from patients with cervical disc herniation. The expression of BMPRs and ActRs was elevated in OPLL compared with controls. Expressions of BMPR-IA, -IB, and -II were observed not only in chondrocytes at the fibrocartilage tissue around the calcified zone but also in fibroblast-like spindle cells at the nonossified ligament. ActR-I and -II were found co-localized in the hypertrophic chondrocytes near the calcified zone and in the ossified tissue. OP-1/BMP-7 was expressed in chondrocytes near the calcified zone. In the control cases, the BMPRs and ActRs were only weakly expressed in the fibrocartilage tissue at the site of ligament attachments to bone and OP-1/BMP-7 was not detected. Enhanced expression of BMPRs at the nonossified ligament in OPLL patients suggests that these cells have a greater potential to differentiate into osteogenic cells than ligament cells from non-OPLL patients. The high expression of BMPRs and ActRs in the ectopic ossified ligament suggests that BMPs and activin may be tightly involved in the pathological ossification process of OPLL.

Activin Receptors↗
PubMed1997

[Three cases of primary lung cancer unexpectedly discovered during the operation of pneumothorax].

It is well known that emphysematous bulla is thought to be often associated with lung cancer. However, it is very rare that lung cancer predisposing to pneumothorax as initial manifestation. We performed surgical operations of four hundred and one cases of spontaneous pneumothorax, and discovered three cases of lung cancer during the operation. However, these three cases occupied the 30% of the patients with pneumothorax who were older than 65 years. The two of them were adenocarcinomas which were situated in the wall of bullae, but did not perforated the bullous wall. The other one was squamous cell carcinoma which was apart from the bullous lesion. This shows that we should always be careful of the associated lung cancer when we care elderly patients with pneumothorax.

Adenocarcinoma↗
PubMed1996

Restriction fragment length polymorphism of genes of the alpha 2(XI) collagen, bone morphogenetic protein-2, alkaline phosphatase, and tumor necrosis factor-alpha among patients with ossification of posterior longitudinal ligament and controls from the Japanese population.

STUDY DESIGN: The present study analyzed the restriction fragment length polymorphism patterns of alpha 2(XI) collagen, bone morphogenetic protein-2, alkaline phosphatase, and tumor necrosis factor-alpha genes in patients with ossification of the posterior longitudinal ligament. This study investigates the genetic polymorphism of bone-induced factors in patients with ossification of the posterior longitudinal ligament and compares it with healthy control subjects. OBJECTIVES: To clarify the genetic markers linked to ossification of the posterior longitudinal ligament. SUMMARY OF BACKGROUND DATA: Ossification of the posterior longitudinal ligament is a genetic disease associated with abnormal calcium metabolism involving the posterior longitudinal ligament. Previous genetic studies have not identified the pathologic mechanism of ossification of the posterior longitudinal ligament. Histopathologic studies of ossification of the posterior longitudinal ligament and the animal model, the spinal hyperostotic mouse, have revealed an increase in Type XI collagen and bone morphogenetic protein-2 expression. METHODS: Eighteen Japanese patients with ossification of the posterior longitudinal ligament and 51 healthy, unrelated control subjects were investigated for the restriction fragment length polymorphism patterns of COL11A2, bone morphogenetic protein-2, alkaline phosphatase, and tumor necrosis factor-alpha, genes with various restriction endonucleases. RESULTS: The gene frequencies of COL11A2 obtained with BamHl (10.0 kb fragment) and HindIII (19.0 kb fragment) observed in patients with ossification of the posterior longitudinal ligament were higher compared with control subjects (0.43 and 0.14, respectively). These differences were statistically significant (BamHl P = 0.018; Hindlll P = 0.046). Two new restriction fragment length polymorphism patterns were detected of the bone morphogenetic protein-2 gene with Mspl and Taql and one already known restriction fragment length polymorphism pattern of the tumor necrosis factor-alpha gene with Ncol. However, they were not significantly different from the control subjects. CONCLUSIONS: Seven restriction fragment length polymorphisms of COL11A2 gene were identified. Two of them (BamHl, 10.0/10.0 kb genotype; HindIII, 19.0/19.0 kb genotype) were significantly different in patients with ossification of the posterior longitudinal ligament.

Alkaline Phosphatase↗
PubMed1996

Effects of strain distribution in the intervertebral discs on the progression of ossification of the posterior longitudinal ligaments.

STUDY DESIGN: Strain distribution in the intervertebral discs was evaluated biomechanically using an engineering true strain calculation formula. OBJECTIVES: This study was performed to clarify the involvement of dynamic factors in the progression of ossification of the posterior longitudinal ligament. SUMMARY OF BACKGROUND DATA: In patients with ossification of the posterior longitudinal ligament of the cervical spine, ossification frequently progresses after laminectomy. This suggests the involvement of dynamic factors in the progression of ossification. However, these factors have not yet been clarified. METHODS: The analysis was performed on 101 patients with ossification of the posterior longitudinal ligament by employing dynamic lateral x-ray films of the cervical spine. The x-ray films were digitized and used as computer data for calculating the strain distribution. X-ray films were obtained again 5 years later, and the strain distribution and the presence or absence of progression of ossification were evaluated. RESULTS: The progression of ossification of the posterior longitudinal ligament was highly correlated with abnormal strain distribution in the intervertebral discs. Progression of ossification was frequently observed in areas having disc distortion in tension and extension on the posterior longitudinal ligament. CONCLUSIONS: In this study, the area of progression of ossification corresponded to the area showing uneven strain distribution and resultant concentration of dynamic stress. These results suggest an important role for dynamic factors in the progression of ossification of the posterior longitudinal ligament.

Adult↗
PubMed1996

Indication of fusion for lumbar spinal stenosis in elderly patients and its significance.

STUDY DESIGN: Selection of surgical therapy for lumbar canal stenosis in elderly patients is discussed. Decompression alone and decompression with fusion were evaluated. OBJECTIVES: To determine the indication of decompression with fusion for lumbar spinal stenosis in elderly patients. SUMMARY OF BACKGROUND DATA: Although there is no objection to posterior decompression, which is regarded as the first choice of surgical therapy for lumbar spinal stenosis in the elderly, it is debatable whether or not fusion should be used with decompression. METHODS: The presence or absence of instability was defined by Posner's method from preoperative plain radiographic lateral findings. Thirty-four elderly patients with lumbar canal stenosis were studied. Seventeen of the 34 patients were found to have instability. Ten of the 17 patients with spinal instability underwent decompression and instrumented fusion. The seven remaining patients with spinal instability underwent decompression alone. The 17 patients without spinal instability were treated by decompression alone. Preoperative symptoms, postoperative results, and changes in radiographic findings were compared among the three groups. RESULTS: The group treated by decompression and fusion showed the best results. The group treated by decompression in the presence of instability showed the worst results by the Japanese Orthopaedic Association back scores. Good results can be obtained by decompression alone only if the patients do not have instability as defined by Posner. CONCLUSIONS: The definition of instability by Posner's method proved useful for selecting elderly patients with instability for fusion treatment. Fusion with instrumentation should be performed on elderly patients with instability after decompression.

Aged↗
PubMed1996

Myeloscopic observation of adhesive arachnoiditis in patients with lumbar spinal canal stenosis.

In this study a myeloscope was used to assess the influence of adhesive arachnoiditis on the surgical outcome of patients with lumbar spinal canal stenosis (LSS). The presence or absence and the degree of the complication of adhesive arachnoiditis were preoperatively determined by myeloscopy in 36 patients with LSS, and these findings were compared with the postoperative results. Various degrees of adhesive changes in the cauda equina were observed in all 36 patients. Patients with marked adhesions, which may indicate a blocked cauda equina, had distinctly worse operative results than did patients with slight or moderate adhesions. Adhesive arachnoiditis was considered to be one of the causes for the poor operative results for LSS. Myeloscopy is useful in diagnosing the morbid condition of the cauda equina in LSS, and for predicting the operative results.

Adult↗
PubMed1995

Enhanced expression of type I receptors for bone morphogenetic proteins during bone formation.

Type I receptors for bone morphogenetic proteins (BMPs), i.e., BMPR-IA and BMPR-IB, are transmembrane serine/threonine kinases, that bind osteogenic protein-1 (OP-1, also termed BMP-7) and BMP-4. Using antibodies specific to BMPR-IA and -IB, we have studied the expression of BMP type I receptors in the bone formation process during embryonic development and fracture healing. In the mouse embryo, both BMPR-IA and -IB were expressed in condensing mesenchymal cells at 13.5 days post coitum (p.c.). At 15.5 days p.c., expression of BMPR-IB, but not of BMPR-IA, was observed in the cells in perichondrium of developing cartilage. At 17.5 and 19.5 days p.c., expression of both receptors was observed in chondrocytes and in osteoblasts. In normal rat adult bone, expression of BMPR-IA, but not of BMPR-IB, was observed in osteoblasts in the periosteum. Three days after the femoral fracture, expression of BMPR-IA and -IB was up-regulated in cells at the proliferating osteogenic layer of the periosteum. On day 7, both receptors were found in fibroblast-like spindle cells and chondrocytes in the endochondral ossification sites, and osteoblasts in the newly formed trabecular bone. Expression of BMPR-IA was higher than that BMPR-IB in osteogenic layer on day 3 and in osteoblasts in the trabecular bone on day 7. On day 14, expression of BMP type I receptors was observed at similar sites, albeit with lower expression levels than were observed on day 7. The present data suggest that expression of BMP type I receptors is up-regulated during bone formation, and that they may play important roles in bone morphogenesis.

Animals↗
PubMed1995

MRI findings in patients with a cervical spinal cord injury who do not show radiographic evidence of a fracture or dislocation.

We investigated the usefulness of magnetic resonance imaging (MRI) in assessing cervical spinal cord injury in patients where there was no evidence of bone injury on radiographs, and examined the relationship between the MRI findings and the clinical prognosis of this injury. MRI allowed us to confirm directly the cause and severity of spinal cord compression in 30 of 31 cases. The patients with severe spinal cord compression demonstrated by MRI showed poor neurological improvement. In regard to the signal changes in the spinal cord, the patients who showed no signal change on T1- and T2-weighted images had a better prognosis. MRI is a very useful non-invasive adjunctive imaging modality for diagnosis of this injury and for the evaluation of the compressed spinal cord. It also demonstrates potential in predicting neurological recovery.

Adult↗
PubMed1995

Transpedicular fixation of the lumbar and lumbosacral spine with screws. Application of the Diapason system.

Forty-six patients with the Diapason transpedicular screw system for lumbar and lumbosacral fusions were analysed clinically. No implant breakage was observed, but one rod migrated. Additional sacral screws different in the length of the threaded portion are necessary in this system. Metallosis was noted in a few cases, but posed no significant clinical problems. This system, which is simple in structure, easy to use, and applicable to magnetic resonance scanning after surgery, is considered to be a useful instrumentation.

Adolescent↗
PubMed1995

Role of N-methyl-D-aspartate receptor in acute spinal cord injury.

To clarify the role of N-methyl-D-aspartate (NMDA) receptors in acute spinal cord injury, changes in the intraspinal microcirculation after acute spinal cord injury in rabbits were examined. Systemic administration of MK-801, an NMDA receptor antagonist, at a dose of 5 mg/kg, significantly improved motor recovery after injury and significantly reduced edema formation at the injured site without altering spinal cord blood flow or vascular permeability at the injured site. These findings indicate that excitatory amino acids contribute to secondary spinal cord damage, especially edema formation, mediated by NMDA receptors in the early stage after injury.

Acute Disease↗
PubMed1994

The natural course of myelopathy caused by ossification of the posterior longitudinal ligament in the cervical spine.

The natural course of ossification of the posterior longitudinal ligament, particularly the relationship between the onset of myelopathy and factors associated with its aggravation, was studied in 207 patients during an average period of 10 years 3 months. Myelopathic signs were already present in 37 (18%) patients at the time of the initial examination. Fourteen of these 37 patients showed aggravation of symptoms during the observation period. Myelopathy appeared during the observation period in 33 (16%) of the 207 patients. One hundred thirty-seven (66%) patients were free of myelopathy. Some patients had no myelopathic signs, despite severe spinal stenosis, because of the ossification. In these patients, the range of motion of the cervical spine was severely limited, indicating that dynamic factors are important in the development of myelopathy. In treating this disease, it is necessary to take into consideration the natural course of the disease and to identify the involvement not only of static factors, such as compression caused by ossification, but also of dynamic factors.

Adult↗
PubMed1993

Dissociated motor loss in the upper extremities. Clinical features and pathophysiology.

Dissociated motor loss occurring in the upper extremities with and without lower extremity myelopathy was evaluated in patients with cervical spondylosis. The presence of dissociated motor loss without attendant myelopathy was correlated with selected compression of the anterior nerve root in the lateral spinal canal, close to the intervertebral foramen. The clinical and radiologic feature differentiating these two dissociative syndromes were reviewed.

Arm↗
PubMed1993

Magnetic resonance imaging study of experimental acute spinal cord injury.

Magnetic resonance imaging (MRI) has been used widely in the diagnosis of acute spinal cord injuries. The association between MRI findings and histologic changes, however, remains unclear. Using a rabbit spinal cord injury model, the authors compared the MRI and histologic abnormalities as they evolved over the first post-trauma month. Bleeding in the gray matter, visualized as a low-intensity area on T1-weighted views and high-intensity area on T2-weighted views, observed immediately after injury, disappeared within the first week. Edema, appearing 6 hours after the initial injury and seen as a high-intensity T2-weighted MRI image, became maximal 1 week later and gradually decreased thereafter. Also appearing 1 week later, were necrotic changes in the gray matter, corresponding to low signals on T1-weighted studies but high signals on T2-weighted studies. MRI therefore helped differentiate hemorrhage and necrosis, presumably irreversible lesions, from the more reversible findings related to edema.

Animals↗
PubMed1993

Anabolic responses of an adult cancellous bone site to prostaglandin E2 in the rat.

The objects of this study were to determine: (1) the response of a non-growing cancellous bone site to daily prostaglandin E2 (PGE2) administration; and (2) the differences in the effects of daily PGE2 administration in growing (proximal tibial metaphysis, PTM) and non-growing cancellous bone sites (distal tibial metaphysis, DTM). Seven-month-old male Sprague-Dawley rats were given daily subcutaneous injections of 0, 1, 3 and 6 mg PGE2/kg per day for 60, 120 and 180 days. The static and dynamic histomorphometric analyses were performed on double-fluorescent labeled undecalcified distal tibial metaphyses (DTM). No age-related changes were found in static and dynamic histomorphometry of DTM cancellous bone between 7 and 13 months of age. The DTM of 7-month-old (basal controls) rats consisted of a 24.5 +/- 7.6%-metaphyseal cancellous bone mass, and a thick trabeculae (92 +/- 12 micron). It also had a very low tissue-base bone formation rate (3.0 +/- 7.3%/year). Exogenous PGE2 administration produced the following transient changes in a dose-response manner between zero and 60 days: (1) increased trabecular bone mass and improved architecture (increased trabecular bone area, width and number, and decreased trabecular separation); (2) increased trabecular interconnections; (3) increased bone formation parameters; and (4) decreased eroded perimeter. A new steady state with more cancellous bone mass and higher bone turnover was observed from day 60 onward. The elevated bone mass induced by the first 60 days of PGE2 treatment was maintained by another 60 and 120 days with continuous daily PGE2 treatment. When these findings were compared to those previously reported for the PTM, we found that the DTM was much more responsive to PGE2 treatment than the PTM. Percent trabecular bone area and tissue-based bone formation rate increased significantly more in DTM as compared to PTM after the 60 days of 6 mg PGE2 treatment. These observations indicate that a non-growing cancellous bone site is more responsive than growing bone site to long-term daily administration of PGE2.

Aging↗
PubMed1993

Percutaneous discectomy in athletes.

Percutaneous discectomy has been widely used for the lumbar disc herniation in recent years because it is a simple and safe procedure. This report evaluates the postoperative return to the original level of activity among athletes who compete in their sports on a national level. It has been thought that the recovery rate was poor in the conventional surgery but there have been few studies. The postoperative results using percutaneous discectomy were rated as excellent in 4 athletes, good in 5, poor in 4. The patients generally returned to full sports activity 2 months after surgery. The authors conclude that percutaneous discectomy may be considered if conservative treatments fail to relieve pain in athletes.

Adolescent↗
PubMed1993

Comparison of operative results of lumbar disc herniation in manual laborers and athletes.

The results of various surgical treatments for lumbar disc herniation in laborers and athletes were compared on the basis of the relative success of return to work and athletic activity. The rate of successful return to manual labor was the highest at 89% after spinal fusion, but no difference was observed between simple disc excision and percutaneous discectomy. Return to competitive sports was achieved at rate of 81% after percutaneous discectomy, and the time until return to sports activity was significantly shorter than after other procedures. In individuals whose lumbar region is expected to be subjected to great mechanical stress, it is important to take work needs and the special needs of athletes into consideration when selecting the surgical procedure.

Adult↗
PubMed1993

Percutaneous diskectomy for lumbar disk herniation. A preliminary report.

Percutaneous diskectomy is a new method for reducing lumbar disk herniation. This procedure is simple, safe, and only semiinvasive since it causes no direct damage to the dura or nerve roots. This technique employs a nucleotome (blunt-tipped, suction-cutting probe) with a rotating electric shaver (3 mm in diameter) that was specially developed for this procedure. It was applied to 117 patients with lumbar disk herniation whose sciatica had not been relieved by conservative treatments. The results of the technique were considered effective in 94 patients (80.3%). The improvements were even more marked in patients with protrusion or prolapse type herniation. Reviewed with postoperative examinations using magnetic resonance imaging (MRI), excision of the herniated disk, resulting in decompression of the nerve root, may be correlated with the relief of symptoms.

Adolescent↗