Biomedical subjects

K Kaneda

Publications and source records attributed to K Kaneda.

At least 91 records · Page 5Linked to original sources

PubMed2000

Vascularised fibular grafts. An experience of 102 patients.

The results and complications of 104 vascularised fibular grafts in 102 patients are presented. Bony union was ultimately achieved in 97 patients, with primary union in 84 (84%). The mean time to union was 15.5 weeks (8 to 40). In 13 patients, primary union was achieved at one end of the fibula and secondary union at the other end. In these patients, the mean time to union was 31.1 weeks (24 to 40). Five patients failed to achieve union, with a resultant pseudarthrosis (3 patients) or amputation (2 patients). There were various complications. Immediate thrombosis occurred in 14 cases. In two of 23 patients with osteomyelitis, infection recurred at two and six months after surgery, respectively. Both patients had active osteomyelitis less than one month before the operation. Bony infection occurred in a patient with a synovial sarcoma of the forearm one year after surgery. In 15 patients, 19 fractures of the fibular graft occurred after bony union, all except one within one year after union. In patients in whom an external fixator had been used, fracture occurred soon after its removal. Union was difficult to achieve in cases of congenital pseudarthrosis of the tibia. Appropriate alignment of the fibular graft is an important factor in preventing stress fracture. The vascularised fibula should be protected during the first year after union. Postoperative complications at the donor site included transient palsy of the superficial peroneal nerve in three patients, contracture of flexor hallucis longus in two and valgus deformity of the ankle in three. Vascularised fibular grafts are useful in the reconstruction of massive bony defects. We believe that meticulous preoperative planning, including choosing which vessels to select in the recipient and the type of fixation devices to use, and care in the introduction of the vascularised fibula, can improve the results and prevent complications.

Adolescent↗

PubMed2000

Phenotypical and morphological analyses of intraepithelial and lamina propria lymphocytes in normal and regenerating gastric mucosa of rats in comparison with those in intestinal mucosa.

While the intestine has abundant intraepithelial lymphocytes (IELs) including extrathymically differentiated T-cell populations and natural killer (NK) cells, the stomach contains only a few IELs. To elucidate whether the gastric epithelium is capable of inducing predominant lymphocyte lodging and subsequent differentiation within, we counted the number of IELs and lamina propria lymphocytes (LPLs) and calculated the percentage of IELs to total lymphocytes for each alpha-beta T cell, gamma-delta T cell, CD4+ cell, CD8+ cell and NK cell in normal and regenerating gastric mucosa as well as the intestinal mucosa of the rat. In the normal rat pylorus, a few alpha-beta T cells but no gamma-delta T cells were found in the epithelium and lamina propria. In regenerating gastric mucosa, all subsets of LPLs increased in number to a degree comparable to those in intestinal mucosa, whereas every IEL subset, though slightly increased, was much smaller in number than in the intestinal mucosa, consequently giving lower percentages of IELs. Electron microscopic observations revealed that all IELs in regenerating gastric mucosa were agranular, while 55% of intestinal IELs were large granular lymphocytes positively stained for an NK-cell, alpha-beta-cell or gamma-delta T-cell marker. The present results indicate that, unlike the intestinal epithelium, the gastric epithelium does not induce the preferential localization of T cells/NK cells and T-cell differentiation into granular lymphocytes in the epithelium even under conditions of prominent LPL infiltration.

Animals↗

PubMed2000

Kupffer cell activation and hematopoiesis in the liver of autoimmune MRL-lpr/lpr mice.

Hematopoiesis can be induced in the adult murine liver by the administration of macrophage activators. The proliferation of macrophages and extrathymic T cells is spontaneously induced in the liver of autoimmune MRL-lpr/lpr mice, and deeply involved in the development of disease. To study the role of Kupffer cell activation in the induction of hematopoiesis and lymphocyte proliferation in the liver, we histologically analysed the kinetic and spatial relationship between Kupffer cells and hematopoietic cells or lymphocytes. At 5 weeks of age before the onset of disease, there were no appreciable histological changes in the liver. At 7 weeks, Kupffer cells had slightly increased in number, while hematopoietic islands were not yet detected. When disease had fully developed at 14 weeks, Kupffer cells were considerably increased in number and size, and exhibited numerous lysosomes. Hematopoietic cells of erythroid and myeloid series frequently appeared in the sinusoid, and lay in close apposition to Kupffer cells. Promyelocytes further migrated into the space of Disse to cluster there, being surrounded by the stellate cells (or fat-storing cells) and hepatocytes. After maturation, metamyelocytes and mature granulocytes were released into the sinusoidal circulation. Mitotic figures were detected in the cells of both erythroid and myeloid series. Lymphocytes proliferated in various sites such as in the sinusoid lumen, the space of Disse, and interlobular connective tissue, whether associated or not with Kupffer cells. The present results indicate that erythropoiesis, granulopoiesis, and lymphocyte proliferation are induced in the liver of MRL-lpr/lpr mice and are closely associated with Kupffer cell activation.

Age Factors↗

PubMed2000

Spontaneous intracranial hypotension associated with bilateral chronic subdural hematomas--case report.

A 34-year-old female presented with spontaneous intracranial hypotension (SIH) manifesting as severe postural headache and meningism. Magnetic resonance (MR) imaging with gadolinium showed diffuse pachymeningeal enhancement. She developed bilateral chronic subdural hematomas 4 weeks after the onset of the symptoms. MR imaging showed descent of the midline structures of the brain. The bilateral chronic subdural hematomas were surgically drained, with no remarkable pressure. Postoperative MR imaging showed complete resolution of the pachymeningeal enhancement and relevation of the midline structures of the brain. SIH is an uncommon and probably unrecognized condition because of the usually benign course. However, this case emphasizes that SIH is not entirely benign. SIH should be considered if there is no identifiable risk for intracranial hemorrhage, particularly in young patients. Neurosurgical intervention for the treatment of the underlying cerebrospinal fluid leak may be required if SIH persists.

Adult↗

PubMed2000

Indirect posterior reduction and fusion of the traumatic herniated disc by using a cervical pedicle screw system.

OBJECT: In this study the authors retrospectively review 16 patients with traumatic disc herniation secondary to middle and lower cervical spine injuries who underwent a single posterior reduction and fusion procedure in which a cervical pedicle screw system was used. The study was undertaken to evaluate whether the procedure effectively reduced the disc herniation and whether it can be safely conducted without performing anterior decompressive surgery. METHODS: A total of 73 patients with middle and lower cervical spine injuries were identified. In 50 patients, pre- and postoperative magnetic resonance (MR) images were obtained, and disc herniation was defined as the presence of an extruded disc that deformed the thecal sac or nerve roots. Traumatic disc herniation was revealed in 16 patients (32%) who underwent a single posterior reduction/fusion procedure in which a cervical pedicle screw system was used. The average follow-up period was 4.25 years (2-6.25 years). In all patients the average kyphotic deformity was 18 degrees, which was corrected to 0.7 degrees lordosis postoperatively. Anterior translation was reduced from 8 to 0.7 mm. The preoperative disc height ratio of 63% (normal 100%) was improved to 104%. Preoperative MR images revealed traumatic disc herniation in all 16 patients; postsurgery, reduction or reversal of disc herniation was observed in all patients. Thecal sac and/or spinal cord compression had disappeared after indirect decompression was achieved using a posterior procedure. No additional decompressive procedures were required to remove residual herniated disc material. Preoperatively, four patients presented with cervical radiculopathy, 10 with myelopathy (eight incomplete and two complete), and two without neurological symptoms. At final follow up, complete recovery was observed in all four patients with radiculopathy and improvement of at least one Frankel grade was shown in six patients (60%) with myelopathy. There were no cases of neurological deterioration immediately after surgery or during the course of the follow-up period. In all patients solid bone union was demonstrated, and there were no implant-related complications. CONCLUSIONS: Traumatic disc herniation may occur frequently in association with injury of the cervical spine. The incidence of traumatic disc herniation in our series was 32%. The cervical pedicle screw system allowed three-dimensional reduction of the injured cervical segment and reduction or reversal of a disc herniation. After surgery, compression of the thecal sac and/or spinal cord had disappeared. The cervical pedicle screw system provides effective and safe fixation of the cervical spine injury-related traumatic disc herniation, and the surgery can be performed safely in a single posterior-approach procedure without need of additional anterior decompressive interventions.

Adolescent↗

PubMed2000

In vitro biomechanical investigation of the stability and stress-shielding effect of lumbar interbody fusion devices.

OBJECT: Interbody fusion devices are rapidly gaining acceptance as a method of ensuring lumbar interbody arthrodesis. Although different types of devices have been developed, the comparative reconstruction stability remains controversial. It also remains unclear how different stress-shielded environments are created within the devices. Using a calf spine model, this study was designed to compare the construct stiffness afforded by 11 differently designed lumbar interbody fusion devices and to quantify their stress-shielding effects by measuring pressure within the devices. METHODS: Sixty-six lumbar specimens obtained from calves were subjected to anterior interbody reconstruction at L4-5 by using one of the following interbody fusion devices: four different threaded fusion cages (BAK device, BAK Proximity, Ray TFC, and Danek TIBFD), five different nonthreaded fusion devices (oval and circular Harms cages, Brantigan PLIF and ALIF cages, and InFix device); two different types of allograft (femoral ring and bone dowel) were used. Construct stiffness was evaluated in axial compression, torsion, flexion, and lateral bending. Prior to testing, a silicon elastomer was injected into the cages and intracage pressures were measured using pressure needle transducers. CONCLUSIONS: No statistical differences were observed in construct stiffness among the threaded cages and nonthreaded devices in most of the testing modalities. Threaded fusion cages demonstrated significantly lower intracage pressures compared with nonthreaded cages and structural allografts. Compared with nonthreaded cages and structural allografts, threaded fusion cages afforded equivalent reconstruction stiffness but provided more stress-shielded environment within the devices.

Animals↗

PubMed2000

Structure of lamina propria lymphoid follicles and associated epithelium in the gastric mucosa during Helicobacter pylori infection in ulcer-bearing Mongolian gerbils.

To develop a gerbil model of Helicobacter pylori-induced chronic active gastritis comparable in severity to human lesions, we made acetic acid-induced ulcer in the anterior antral wall and concurrently challenged 1 x 10(8) colony-forming units bacteria per os. At 30 and 60 days after inoculation, the number of viable bacteria colonizing on the surface epithelium of the gastric mucosa was larger in ulcer-bearing animals compared to non-bearing ones. Furthermore, in the former animals, neutrophil and mononuclear cell infiltration as well as lymphoid follicle formation in the lamina propria was more prominent. Electron microscopically, lymphoid follicle-associated epithelium displayed specialized structures. Namely, brush cells interposed between mucous epithelial cells and characterized by prominent microfilament bundles and many apical vesicles or caveola specifically embraced the cluster of intraepithelially invading lymphocytes and macrophage-like cells by the attenuated cytoplasm in an analogous manner to M cells in Peyer's patches. The present study has demonstrated that ulcer formation enhances both H. pylori colonization and lamina propria lymphoid follicle formation and suggested that follicle-associated epithelium might play roles in the delivery of intraluminal antigen.

Animals↗

PubMed1999

ROCK inhibitor Y-27632 attenuates stellate cell contraction and portal pressure increase induced by endothelin-1.

By using a selective ROCK inhibitor Y-27632, the role of Rho-ROCK signaling in the function of hepatic stellate cells in culture was studied. Stellate cells maintained the "star-like" configuration of the quiescent stage in the presence of Y-27632, while the expression of smooth muscle alpha-actin and PDGF receptor beta was not affected by the agent. Serum-stimulated migration of the cells was significantly suppressed by Y-27632. The contraction of stellate cells induced by 5 nM endothelin-1 was attenuated by the agent in a dose-dependent manner. Formation of F-actin stress fibers and phosphorylation of myosin light chain was apparently reduced by Y-27632 even under the stimulation with endothelin-1. On the other hand, ex vivo liver perfusion experiment revealed that endothelin-1 (2 nM)-induced increase of portal vein constriction was almost completely inhibited by 20 microM Y-27632 with a concomitant improvement of hepatocyte degeneration. These results suggest that ROCK is one of the key regulators of stellate cell motility and that the clinical application of ROCK inhibitors such as Y-27632 should be considered in the reduction of portal hypertension in liver fibrosis and cirrhosis.

Actins↗

PubMed1999

Correction of cervical kyphosis using pedicle screw fixation systems.

STUDY DESIGN: This retrospective study was conducted to analyze the clinical results in 30 patients with cervical kyphosis that had been treated using cervical pedicle screw fixation systems. OBJECTIVES: To evaluate the effectiveness of a pedicle screw fixation procedure in correction of cervical kyphosis. SUMMARY OF BACKGROUND DATA: Correction of cervical kyphosis is a challenging problem in the field of spinal surgery. There have been several reports regarding surgical correction of cervical kyphosis; however, there have been no detailed reports on correction of cervical kyphosis using a pedicle screw fixation procedure. METHODS: Thirty patients with cervical kyphosis underwent correction and fusion using cervical pedicle screw fixation. Seventeen of 30 patients with flexible kyphosis (Group I) were managed by a posterior procedure alone. The remaining 13 patients with rigid or fixed kyphosis (Group II) had a combined anterior and posterior procedure. RESULTS: The average preoperative cervical kyphosis of 29.4 degrees improved to 2.3 degrees after surgery and was 2.8 degrees at the final follow-up. In Group I patients, preoperative kyphosis of 28.4 degrees improved to 5.1 degrees at the final follow-up. In contrast, preoperative kyphosis of 30.8 degrees in Group II patients improved to 0.5 degree at the final follow-up. Solid fusion was achieved in all patients. There were two patients with transient nerve root complications related to pedicle screw instrumentation. CONCLUSION: Cervical kyphosis in 30 patients was effectively corrected using a pedicle screw fixation procedure with no serious complications. Flexible kyphosis with segmental motion can be satisfactorily corrected by a single posterior procedure using pedicle screw fixation. However, circumferential osteotomies combined with a posterior shortening procedure involving a pedicle screw system are required to achieve the best correction of fixed kyphosis by bony union. Cervical pedicle screw fixation is the most advantageous instrumentation in the correction of cervical kyphosis.

Bone Screws↗

PubMed1999

The stability of reconstruction methods after thoracolumbar total spondylectomy. An in vitro investigation.

STUDY DESIGN: After total spondylectomy, five types of spinal reconstruction techniques were compared biomechanically. OBJECTIVES: To evaluate the stability provided by five reconstruction methods after total spondylectomy. SUMMARY OF BACKGROUND DATA: Total spondylectomy presents a worst-case scenario for spinal reconstruction. However, few investigators have biomechanically investigated spinal reconstruction stability after total spondylectomy. METHODS: Eight human cadaveric spines (T11-L5) were used. After intact analysis, a total spondylectomy was performed at L2 and reconstructed using Harms titanium mesh (Depuy-Motech, Warsaw, IN) as an anterior strut. Anterior, posterior, or circumferential instrumentation techniques were then performed using the Kaneda SR and ISOLA pedicle screw systems (AcroMed Corp., Cleveland, OH) as follows: 1) anterior instrumentation at L1-L3 with multisegmental posterior instrumentation at T12-L4 (AMP), 2) anterior instrumentation at L1-L3 with short posterior instrumentation at L1-L3 (ASP), 3) anterior instrumentation at L1-L3 (A), 4) multilevel posterior instrumentation at T12-L4 (MP), and 5) short posterior instrumentation at L1-L3 (SP). Nondestructive biomechanical testing was performed under axial compression, flexion-extension, and lateral bending loading modes. RESULTS: Only circumferential instrumentation techniques (AMP, ASP) exhibited higher stiffness than the intact spine in all loading modes (P < 0.05). Short circumferential fixation provided more stability than did multilevel posterior instrumentation (P < 0.05). Multilevel posterior fixation provided more stiffness than did short posterior and anterior instrumentation alone (P < 0.05). CONCLUSIONS: Only circumferential fixation techniques provide more stability than the intact spine in all testing modes. Short circumferential instrumentation provides more stability than multilevel posterior instrumentation alone and requires fewer levels of spinal fusion.

Aged↗

PubMed1999

Biomechanical role of the intervertebral disc and costovertebral joint in stability of the thoracic spine. A canine model study.

STUDY DESIGN: Biomechanical evaluation was performed to investigate the stability of the thoracic spine. Unilateral resection of the intervertebral disc, the rib head joint, and the costotransverse joint were sequentially performed, and nondestructive cyclic loading tests were conducted at each injury stage to examine the roles of the intervertebral disc and the costovertebral joint of the thoracic spine. The effects of each resection were three-dimensionally analyzed as the main motion and the associated coupled motions. OBJECTIVE: To examine the role of the intervertebral disc and the costovertebral joint in stability of the thoracic spine. SUMMARY OF BACKGROUND DATA: The effects of unilateral resection of the intervertebral disc and the costovertebral joints in the thoracic spine with the rib cage have not been documented three-dimensionally in a biomechanical study. MATERIALS AND METHODS: Ten canine rib cage-thoracic spine complexes, consisting of the sixth to eighth ribs, the sternum and T5-T8 vertebrae, were used. Six pure moments along three axes, flexion-extension, lateral bending, and axial rotation, were applied to the specimen, and the angular deformation between T6-T7 was recorded by a stereophotogrammetric method. After the intact specimens were tested, staged resections were conducted in the following manner: partial resection of the T6-T7 intervertebral disc, performed as a resection of the anterior longitudinal ligament, the nucleus pulposus, and the annulus fibrosus on the approach side, leaving the posterior longitudinal ligament intact; resection of the right seventh rib head with the joint capsule; and resection of the right seventh costotransverse joint. At each stage, the main motion and associated coupled motions were determined three dimensionally. RESULTS: The ranges of motion (ROM) in flexion-extension, lateral bending, and axial rotation were significantly increased after partial discectomy (P < 0.01). Moreover, along with large increases in the ROM of the main motions in left axial rotation and right lateral bending, coupled motions, expressed by right lateral bending and left axial rotation, showed marked increases after resection of the rib head joint (P < 0.05). The neutral zones also increased in lateral bending, axial rotation, and flexion-extension after partial discectomy (P < 0.01). A further increase in the neutral zone was observed in lateral bending after resection of the right seventh rib head (P < 0.01). CONCLUSIONS: In this canine spine model, the intervertebral disc regulates the stability of the thoracic spine in flexion-extension, lateral bending, and axial rotation. Moreover, the articulation of the rib head with the vertebral bodies provides stability to the thoracic spine in lateral bending and axial rotation. Unilateral resection of the rib head joint after partial discectomy on the same side produces significant coupled motions in lateral bending and axial rotation, resulting in a significant decrease in thoracic spinal stability, and integrity.

Animals↗

PubMed1999

Posterior occipitocervical reconstruction using cervical pedicle screws and plate-rod systems.

STUDY DESIGN: This retrospective study was conducted to analyze the clinical results in 26 patients with lesions at the craniocervical junction that had been treated by occipitocervical reconstruction using pedicle screws in the cervical spine and occipitocervical rod systems. OBJECTIVES: To evaluate the effectiveness of pedicle screw fixation in occipitocervical reconstructive surgery and to introduce surgical techniques. SUMMARY OF BACKGROUND DATA: Many methods of occipitocervical reconstruction have been reported, but there have been no reports of occipitocervical reconstruction using pedicle screws and occipitocervical rod systems for reduction and fixation. METHODS: Twenty-six patients with lesions at the craniocervical junction underwent reconstructive surgery using pedicle screws in the cervical spine and occipitocervical rod systems. The occipitocervical lesions were atlantoaxial subluxation associated with basilar invagination, which was caused by rheumatoid arthritis in 19 patients and other disorders in 7. The lowest cervical vertebra of fusion in 16 patients was C2, and the remaining 10 patients underwent fusion downward from C3 to C7. Flexion deformity of the occipitoatlantoaxial complex was corrected by application of extensional force, and upward migration of the odontoid process was reduced by application of combined force of extension and distraction between the occiput and the cervical pedicle screws. RESULTS: Solid fusion was achieved in all patients except two with metastatic vertebral tumors who did not receive bone graft for fusion. Correction of malalignment at the craniocervical junction was adequate, and postoperative magnetic resonance imaging showed improvement of anterior compression of the medulla oblongata. There were no neurovascular complications of cervical pedicle screws. CONCLUSIONS: Occipitocervical reconstruction by the combination of cervical pedicle screws and occipitocervical rod systems provided the high fusion rate and sufficient correction of malalignment in the occipitoatlantoaxial region. Results of this study showed the effectiveness of cervical pedicle screw as a fixation anchor for occipitocervical reconstruction.

Adult↗

PubMed1999

Does spinal instrumentation influence the healing process of posterolateral spinal fusion? An in vivo animal model.

STUDY DESIGN: An in vivo sheep model was used to investigate the effect of spinal instrumentation on the healing process of posterolateral spinal fusion. OBJECTIVES: To examine the role of spinal instrumentation during the healing process of posterolateral fusion. SUMMARY OF BACKGROUND DATA: In long bone fractures, internal fixation improves the union rate but does not accelerate the healing process. Spinal instrumentation also improves the fusion rate in spinal arthrodesis. However, it remains unclear whether the use of spinal instrumentation expedites the healing process of spinal fusion. METHODS: Sixteen sheep underwent posterolateral spinal arthrodeses at L2-L3 and L4-L5 using equal amounts of autologous bone. One of those segments was selected randomly to be augmented with transpedicular screw fixation (Texas Scottish Rite Hospital spinal system). The animals were killed at 8 weeks or 16 weeks after surgery. Fusion status was evaluated by biomechanical testing, manual palpation, plain radiography, computed tomography, and histology. RESULTS: Instrumented fusion segments demonstrated significantly higher stiffness than did uninstrumented fusions at 8 weeks after surgery. Radiographic assessment and manual palpation showed that the use of spinal instrumentation improved the fusion rate at 8 weeks (47% versus 38% in radiographs, 86% versus 57% in manual palpation). Histologically, the instrumented fusions consisted of more woven bone than the uninstrumented fusions at 8 weeks after surgery. The 16-week-old fusion mass was diagnosed biomechanically, radiographically, and histologically as solid, regardless of pedicle screw augmentation. CONCLUSION: The current study's results demonstrated that spinal instrumentation creates a stable mechanical environment to enhance the early bone healing of spinal fusion.

Animals↗

PubMed1999

Biomechanical analysis of anterior versus circumferential spinal reconstruction for various anatomic stages of tumor lesions.

STUDY DESIGN: Spinal reconstruction procedures for metastasis evaluated biomechanically using human cadaver specimens. OBJECTIVE: To investigate the stiffness of anterior versus circumferential spinal reconstructions for different anatomic stages of tumor lesions. SUMMARY OF BACKGROUND DATA: Metastatic tumors predominantly involve the vertebral bodies. Although anterior instrumentation and strut grafts provide excellent stability, it remains unclear to what extent vertebral destruction requires anterior reconstructions alone versus combined anterior and posterior procedures. METHODS: Ten human cadaveric thoracolumbar spines were used. The L1 vertebral body and posterior elements were resected sequentially based on Weinstein's anatomic zone classification for tumor lesions. Anterior reconstruction was performed between T12 and L2 using an iliac strut graft and the Kaneda SR system (AcroMed, Cleveland, OH). For circumferential reconstruction, the Cotrel-Dubousset hook and rod system was combined with the anterior reconstruction procedure. Experimental groups included the intact condition and five reconstruction stages: anterior reconstructions for corpectomy, subtotal and total spondylectomies, and circumferential reconstructions for subtotal and total spondylectomies. Nondestructive biomechanical testing was performed under four different loading modes. RESULTS: All the reconstruction groups except anterior instrumentation alone for total spondylectomy returned stiffness to a level equivalent or higher to that of the intact spine. There were no statistical differences observed between anterior and circumferential reconstruction for subtotal spondylectomy. Anterior instrumentation alone for total spondylectomy did not restore stiffness to the intact level, and demonstrated significantly lower stiffness than that of circumferential reconstruction. CONCLUSIONS: For corpectomy or subtotal spondylectomy, anterior reconstruction alone can provide stiffness equivalent to circumferential reconstruction. However, total spondylectomy significantly reduces the anterior reconstruction stiffness, suggesting the need for combined anterior and posterior procedures.

Aged↗

PubMed1999

Dynamic motion analysis of normal and unstable cervical spines using cineradiography. An in vivo study.

STUDY DESIGN: Cervical motion patterns were analyzed in a normal population and in patients with cervical instability by using cineradiography. OBJECTIVES: To determine normal and pathologic motion patterns in the cervical spine through an in vivo continuous motion analysis. SUMMARY OF BACKGROUND DATA: Cineradiographic techniques have been used in a limited number of studies to quantify spinal motion. There is a paucity of information regarding dynamic motion patterns in normal and pathologic cervical spines. METHODS: Ten healthy subjects and 12 patients with unstable cervical spines (C1-C2 subluxation caused by rheumatoid arthritis, n = 10; instability below C2, n = 2) were studied. Cervical motion during flexion from the maximum extension position was recorded using cineradiography. Cervical segmental motions (C1-C2 to C5-C6) were continuously measured through quantifying cineradiographic images projected on a digitizer. RESULTS: Normal cervical spines showed a well-regulated stepwise motion pattern that initiated at C1-C2 and transmitted to the lower segments with time lags. Pathologic spines showed a different order of onset of segmental motion. In patients with rheumatoid arthritis who had atlantoaxial subluxation, C1-C2 motion initiated significantly earlier than C2-C3 motion. In patients with segmental instability below C2, motion in the unstable segments preceded that in the upper intact segments. CONCLUSIONS: Different motion patterns were observed between normal and pathologic cervical spines. Cineradiographic motion analysis is a valuable adjunctive technique, especially in diagnosis or evaluation of conditions that cannot be identified through conventional radiographic examination.

Adult↗

PubMed1999

Identification of macrophage migration inhibitory factor (MIF) in rat peripheral nerves: its possible involvement in nerve regeneration.

Macrophage migration inhibitory factor (MIF) is known as a pluripotent immunoregulatory cytokine involved in T-cell activation and inflammatory responses; however, no study on this protein in the peripheral nervous systems has been carried out. We here demonstrated for the first time expression of MIF mRNA and MIF protein in rat sciatic nerves by reverse transcription-polymerase chain reaction, Western blotting, and immunohistochemistry. Immunohistochemical analysis revealed positive staining of MIF, which was largely observed in Schwann cells. Furthermore, we examined MIF mRNA expression in the sciatic nerves by Northern blot analysis in the case of nerve transection. In both proximal and distal segments, the level of MIF mRNA started to increase 12 h after the nerve transection. The level remained high from 24 h up to day 7 after the injury. During the period from days 14 to 21, MIF mRNA sharply decreased to the pre-transection level. In immunohistochemistry, positive staining of MIF was largely observed in axons as well as non-neuronal cells in proximal segments at day 4 after transection. In the distal segments, contrastingly, endoneurial fibroblasts or Schwann cells migrating into neuronal fibers showed positive staining with Wallerian degeneration. Although the precise functions of MIF in the peripheral nerves remain to be elucidated, the present results could represent a major departure from the current state of knowledge, revealing a novel function in the degenerative-regenerative process.

Animals↗

PubMed1999

Apoptotic DNA fragmentation and upregulation of Bax induced by transient ischemia of the rat retina.

This study was performed to examine the involvement of apoptosis and the expression of bcl-2 family genes in ischemia-induced retinal injury. Retinal ischemia was induced in adult rats by raising the intraocular pressure to 130 mmHg for 45 min. Selective damage to the inner retina was observed 7 days after ischemia. No terminal deoxynucleotidyl-transferase (TdT)-mediated dUTP nick end-labeling (TUNEL) positive cells were observed in the normal retina, but there was a significant number of TUNEL positive cells 6-48 h after transient ischemia followed by a decrease at 96 and 168 h. The number of TUNEL positive cells reached a maximum at 24 h after ischemia. DNA laddering was observed on agarose gel electrophoresis with the retinas 24 and 48 h after ischemia but not in the normal retina. Semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) revealed that bax gene expression did not change immediately after cessation of ischemia, but gradually increased as early as 6 h, reached a peak at 24 h, then decreased to near baseline levels at 168 h. On the other hand, bcl-2 gene expression showed no obvious changes at any time after transient ischemia. Moreover, intense Bax protein immunoreactivity was detected in the retinal sections at 24 h after ischemia although little immunoreactivity was present in the normal sections. These results suggest that apoptosis associated with the expression of Bax is involved in retinal cell loss after ischemic insult.

Animals↗

PubMed1999

Selective occlusion of choroidal neovascularization by photodynamic therapy with a water-soluble photosensitizer, ATX-S10.

BACKGROUND AND OBJECTIVE: To determine the optimal treatment parameters for selective occlusion of choroidal neovascularization (CNV) by photodynamic therapy (PDT) by using the photosensitizer ATX-S10 and a diode laser (wavelength = 670 nm). MATERIALS AND METHODS: Experimental CNV was induced in rat fundi by argon laser photocoagulation. The distribution of ATX-S10 in the chorioretina was analyzed by fluorescence microscopy, and the optimal treatment parameters for selective occlusion of CNV were investigated by changing the dosage and timing of laser irradiation. CNV closure and resulting damage of the surrounding tissue were documented by fluorescein angiography and light and electron microscopies. RESULTS: Fluorescence of ATX-S10 was observed to be localized in the vascular lumen of the retina and choroid within 5 min after dye injection and increased in intensity in CNV up to 2-6 h and decreased rapidly in normal tissue. Laser irradiation with radiant exposures of 7.4 J/cm2 applied immediately after dye injection or with 22.0 J/cm2 at 2-4 h later effectively occluded the induced CNV without causing significant damage to normal retinal capillaries and large choroidal vessels. CONCLUSIONS: PDT using ATX-S10 can selectively occlude CNV. ATX-S10 is a potentially useful photosensitizer for the treatment of CNV.

Animals↗