Magnetic Resonance Imaging Findings and Clinical Outcomes in the Early Postoperative Period after Full Endoscopic Diskectomy for Lumbar Disk Herniation.

INTRODUCTION: This prospective case-control study aimed to establish the normal spectrum of early magnetic resonance imaging (MRI) findings in patients whose symptoms resolve after full endoscopic diskectomy (FED). We examined the changes in postoperative MRI findings and their relation to early clinical symptoms. METHODS: In total, 33 patients underwent FED under local anesthesia. Clinical assessments and MRI examinations were performed preoperatively and immediately (within 1 week) and late (at 3 and 12 months) postoperatively. Residual disk bulging after surgery was classified into four grades compared with preoperative MRI findings: none (grade A), <25% (grade B), 25-75% (grade C), and >75% (grade D). RESULTS: MRI at postoperative week 1 showed grade B residual disk bulging in 9 patients, grade C residual disk bulging in 8 patients, and grade D residual disk bulging in 16 patients. Improvement was seen at postoperative month 3 (grade A in 18 patients, grade B in 10 patients, and grade C in 5 patients) and at postoperative month 12 (grade A in 29 patients, grade B in 3 patients, and grade C in 1 patient). Visual analog scale scores and the Japanese Orthopaedic Association scores showed significant differences at 1 week, 3 months, and 12 months after surgery. CONCLUSION: Postoperative MRI findings within 1 week of FED showed grade C or D residual disk material in 24 of 33 patients (73%). Clinical symptoms improved in the early postoperative period, even though residual disk bulging was present. Persisting residual bulging in the early stage following surgery may not correlate with clinical symptoms.

One-Stage Reconstruction for Re-rupture of Achilles Tendon with Soft Tissue Infection: Using an Anterolateral Thigh Flap Incorporating a Vascularized Muscle Flap and a Strip of Iliotibial Tract.

Reconstruction is challenging in a patient with loss of a segment of Achilles tendon and infection in the overlying soft tissue. Here the authors describe one-stage tendon reconstruction, using an anterolateral thigh free flap incorporating a vascularized muscle flap and a strip of iliotibial tract in a patient with re-rupture of an Achilles tendon and soft tissue infection. Postoperative immobilization of the affected ankle using an external fixator enabled us to observe the flap directly and reduce pressure on the flap. The patient had a successful outcome, with no difficulty in walking, running, or climbing stairs and no limitation of range of motion at the ankle joint postoperatively. This is a promising technique for reconstruction of the Achilles tendon and treatment of infection as a one-step procedure.

Role of Epiligament in Ligamentum Flavum Hypertrophy in Patients with Lumbar Spinal Canal Stenosis:a Pilot Study.

Ligamentum flavum (LF) hypertrophy is one of the main factors of lumbar spinal canal stenosis (LSCS). The primary object of this study is to clarify the existence of epiligament in the LF and its role in hypertrophy, and to develop an LF hypertrophy animal model. A cadaveric spine from a 30-year-old man was used to investigate the existence of epiligament in LF. Five LF samples from LSCS patients were obtained to evaluate hypertrophied LF. To create a rat model, we destabilized the lumbar spine. Each LF was sagittally cut for histological evaluation. The epiligament was clearly evident in normal LF specimens, which stained pink on Elastica van Gieson and green on Masson Trichrome. One layer was observed on the dural side and another on the dorsal side of the LF. LSCS patients had an enlarged dorsal epiligament, at around 30 times that of the regular thin epiligament on the dural side. The destabilized rat model showed an enlarged dorsal epiligament, with a mean thickness 8-fold that of the control. LF hypertrophy may be due to enlargement of the dorsal epiligament. Mechanical loading of the LF is an important factor for inducing hypertrophy in the rat model. J. Med. Invest. 65:85-89, February, 2018.

Morphometric Changes of the Lumbar Intervertebral Foramen after Percutaneous Endoscopic Foraminoplasty under Local Anesthesia.

BACKGROUND: Percutaneous endoscopic diskectomy (PED) for the lumbar spine is a relatively new technique that is becoming more common due to its relatively less invasive nature. However, one possible serious complication is an exiting nerve injury when the cannula of the endoscope is inserted into the neural canal through the intervertebral foramen. A technique to enlarge the intervertebral foramen, called foraminoplasty, was recently established to insert the cannula safely into an appropriate position in the neural canal. METHODS: In this study we performed foraminoplasty during PED under local anesthesia on 15 patients. Using computed tomography scans before and after surgery, the morphometric changes of the intervertebral foramen were evaluated. Surgery-related complications were reviewed. RESULTS: There were 13 men and 2 women, 21 to 86 years of age (mean: 47.1 years). Disk levels were 13 cases at L4-L5, one case at L3-L4, and one case at L5-S1. In 50% of the cases, the mean foraminal area significantly increased from 58.6 mm2 before surgery to 88.4 mm2 after surgery (p < 0.05 by paired t test). The diameter of the foramen was increased at all three points: the lower end plate of the superior vertebrae, the disk, and the upper end plate of the inferior vertebrae. The area increased ∼ 1.5 times, especially at the upper end plate of the inferior vertebrae. In all cases, no exiting nerve injury was encountered during PED. CONCLUSION: Foraminoplasty was an effective method for avoiding exiting nerve root injury during transforaminal PED.

A new concept of transforaminal ventral facetectomy including simultaneous decompression of foraminal and lateral recess stenosis: Technical considerations in a fresh cadaver model and a literature review.

Percutaneous endoscopic surgery for the lumbar spine, which was established in the last decade, requires only an 8-mm skin incision and causes minimal damage to the paravertebral muscles; thus, it is considered to be a minimally invasive technique for spinal surgery. It has been used to perform percutaneous endoscopic discectomy via two main approaches: the TF approach is a posterolateral one through the intervertebral foramen and can be done under local anesthesia; the IL approach is a more traditional one through the interlaminar space and is difficult to perform under local anesthesia. Recently, these techniques have been applied for lumbar spinal stenosis (LSS), the TF method for foraminal stenosis under local anesthesia, and the IL method for central and lateral recess stenosis under general anesthesia. In this study, using a fresh human cadaver model, we performed simultaneous decompression of the lateral recess and foraminal stenosis at L4-5 using the TF approach. Computed tomography confirmed enlargement of the lateral recess and intervertebral foramen. This technique, which can be performed under local anesthesia, should benefit elderly patients with LSS and poor general condition due to multiple comorbidities. Finally, we introduce the concept of percutaneous transforaminal ventral facetectomy using a spinal percutaneous endoscope. J. Med. Invest. 64: 1-6, February, 2017.

Pediatric isthmic spondylolisthesis showing radiologic evidence of slippage after physis injury.

The pathogenesis of slippage in pediatric spondylolisthesis is still unclear, although epiphyseal injury may account for many cases based on preclinical studies. However, no reports have described a pediatric case of isthmic spondylolisthesis showing radiologic evidence of epiphyseal injury. We report such evidence in a 13-year-old boy with low-back pain. Radiography revealed rounding of the S1 surface, a fracture line below the S1 endplate surface, and a bone marrow lesion in addition to slippage. Slippage and the rounding deformity were partially reversed (from 20 to 14% and from 42 to 27%, respectively) with conservative treatment and natural bone remodeling.

Percutaneous endoscopic lumbar discectomy utilizing ventral epiduroscopic observation technique and foraminoplasty for transligamentous extruded nucleus pulposus: technical note.

Percutaneous endoscopic discectomy (PED) is a minimally invasive disc surgery that can be performed under local anesthesia and requires only an 8-mm skin incision. For transligamentous extruded nucleus pulposus with foraminal stenosis, it is very hard to remove the migrated mass with a simple transforaminal approach. For such difficult cases, foraminoplasty and an epiduroscopic technique is useful. A 29-year-old man visited the authors' hospital, complaining of low-back and right leg pain. MRI revealed a massive herniated nucleus pulposus with foraminal stenosis. A transforaminal PED was planned to remove the herniated mass. Through the inside-out technique, the base of the herniated mass was removed. Following the foraminoplasty, the cannula was moved into the epidural space. With epidural observation just beneath the nerve root, the extruded transligamentous fragment was confirmed and removed en bloc. Immediately after the surgery, the patient's symptoms resolved. The combination of foraminoplasty and epiduroscopic observation during the transforaminal approach for PED is a useful and reliable technique to remove extruded transligamentous disc fragments.

Open dislocation of the proximal interphalangeal joint of the little finger subsequent to chronic radial collateral ligament injury: a case report of primary ligament reconstruction with a half-slip of the flexor digitorum superficialis: Case Report.

Open dislocation of the proximal interphalangeal (PIP) joint is relatively rare. We report a case of a 32-year-old man who had open dislocation of the PIP joint of the little finger while playing American football. He had a history of chronic radial collateral ligament injury. We reconstructed the radial collateral ligament with a half-slip of the flexor digitorum superficialis tendon.

Effectiveness of three types of lumbar orthosis for restricting extension motion.

Spinal orthoses are implemented to restrict lumbar motion. Several studies have compared the effectiveness of various types of lumbar orthoses on restricting motion, but none have compared the effect of different back supports on restricting extension. This study sought to evaluate the effectiveness of three types of lumbar orthosis in regard to their ability to restrict motion during extension. Range of motion was quantified using the Spinal Mouse system to measure flexion and extension, and the load distribution of the back support was measured using a pressure sensor. Ten subjects (8 men, 2 women) were assessed under the following five experimental conditions: custom-made stay (CMS), aluminum stay (AS), plastic stay (PS), corset only, and no brace. None of the stays changed the flexion angle, and none of the supports prevented flexion bending. The mean extension angle after immobilization with the CMS, AS, PS, corset only, and no brace was 27.5° ± 8.5°, 33.4° ± 11.0°, 34.3° ± 9.4°, 37.8° ± 10.7°, and 42.6° ± 10.5°, respectively. The load in the CMS was concentrated at the vertical ends of the stay, with a mean load of 11.5 ± 2.4 N at the top and 8.9 ± 2.4 N at the bottom. The loads at the top and bottom of the support were 7.2 ± 4.3 and 5.3 ± 3.1 N with the AS and 5.8 ± 2.3 and 4.4 ± 1.7 N with the PS, respectively. All supports allowed similar flexion motion. Although the CMS, AS, and PS all restricted extension compared with no brace, the CMS was the most effective for restricting trunk extension motion.

Relationship between limb length discrepancy and load distribution across the sacroiliac joint--a finite element study.

We assessed the relationship between leg length discrepancy (LLD) and the load distribution across the sacro-iliac joint (SIJ). A finite element model of the spine-pelvis was developed with different amounts of LLD by increasing the length of the right femur in the model. Peak stresses and contact loads across the SIJ were computed for different amounts of LLD (1, 2, and 3 cm). The load and the peak stresses across the SIJ articular surfaces progressively increased with the increase in the LLD. Trying to offset the LLD surgically by lengthening of the short side, shortening or stunting the growth (epiphysiodesis) of the long side, or by shoe lifts should decrease the load across the SIJ and should theoretically decrease SIJ pain.

Biomechanical rationale of sacral rounding deformity in pediatric spondylolisthesis: a clinical and biomechanical study.

AIM: Rounding surface of the sacral dome and wedging deformity of the vertebral body are commonly observed in patients with isthmic spondylolisthesis. Recently, an animal study showed that the deformity can be caused by the growth plate involvement in the immature pediatric vertebral body after biomechanical alteration due to the pars defects. However, the pathomechanism and biomechanics of these deformities have yet to be clarified. To demonstrate that the sacral rounding deformity observed in pediatric patients with spondylolisthesis can be reversed, and to understand the pathomechanism of the deformity from the biomechanical standpoint by analyzing changes of stress around the growth plate of the vertebral body due to spondylolysis. METHOD: Three-dimensional finite element pediatric lumbar models of the L3-L5 segment were utilized. Unlike the adult model, this pediatric model had growth plates and apophyseal rings. We analyzed stress distribution in response to 351°N axial compression and 10 N m moment in flexion, extension, lateral bending, and axial rotation. Bilateral spondylolysis was created in the model at the L4 level. The stress in the bilateral defect model was compared to the intact model predictions and the results obtained in the pediatric patients with sacral rounding deformity. RESULTS: Two patients presented rounding deformity of the anterior upper corner at S1 at the initial visit. They were asked to stop sports activities and use a soft trunk brace. Twelve months later, no rounding deformity was observed on the radiographs indicating that this deformity was reversible in pediatric cases. The biomechanical study indicated that in the pediatric spondylolytic spine, mechanical stress increased at the anterior upper corner during lumbar motion. CONCLUSION: In the presence of spondylolysis, mechanical stress increases in the growth plate at the anterior upper corner. Repetitive increases of mechanical stress may cause rounding deformity of the sacral dome mediated by growth plate involvement. When mechanical stress at the growth plate is reduced by wearing a brace, the proper functioning of the growth plate can help to remodel the sacral dome to its normal shape.

Operated and adjacent segment motions for fusion versus cervical arthroplasty: a pilot study.

BACKGROUND: Anterior cervical discectomy and fusion (ACDF) represent the standard treatment for cervical spondylolytic radiculopathy and myelopathy. To achieve solid fusion, appropriate compressive loading of the graft and stability are essential. Fusion may lead to adjacent segment degeneration. Artificial discs have been introduced as motion-preserving devices to reduce the risk of fusion-related complications. QUESTIONS/PURPOSES: We therefore asked: (1) Does the use of a plate reduce motion at the operated level and bone graft compression compared to fusion with bone graft alone; and (2) is adjacent-segment motion higher after fusion with a plate? METHODS: Motions and compressive loads in the graft were quantified for intact, C4-C5 ACDF without and with a plate, and total disc arthroplasty in human cadaver spines. RESULTS: At the surgery level all motions decreased for ACDF with a plate. The motions were similar to intact motions after total disc arthroplasty. The motions across the adjacent segment increased after fusion in all loading modes except lateral bending and were closer to the intact for the total disc arthroplasty case. The plate maintained a compressive load on the graft with a maximum increase in extension. CONCLUSIONS: Unlike fusion, the arthroplasty can restore motion to normal at the surgery and adjacent segments, compared to fusion cases. A cervical plate with a precompression of the graft provides enhanced stability and fusion due to improved compression. CLINICAL RELEVANCE: Our findings support the clinical observations that fusion may lead to the degeneration of the adjacent segments. Disc arthroplasty may be able to circumvent the adjacent segment degeneration.

Cross-sectional magnetic resonance imaging study of lumbar disc degeneration in 200 healthy individuals.

OBJECT: The current cross-sectional observational MR imaging study aimed to investigate the prevalence and risk factors of lumbar disc degeneration in a healthy population and to establish the baseline data for a prospective longitudinal study. METHODS: Two hundred healthy volunteers participated in this study after providing informed consent. The status of lumbar disc degeneration was assessed by 3 independent observers, who used sagittal T2-weighted MR imaging. Demographic data collected included age, sex, body mass index, episode(s) of low-back pain, smoking status, hours of standing and sitting, and Roland-Morris Disability Questionnaire scores. There were 68 men and 132 women whose mean age was 39.7 years (range 30-55 years). Eighty-two individuals (41%) were smokers, and the Roland-Morris Disability Questionnaire scores were averaged to 0.6/24. RESULTS: The prevalence of disc degeneration was 7.0% in L1-2, 12.0% in L2-3, 15.5% in L3-4, 49.5% in L4-5, and 53.0% in L5-S1. A herniated disc was observed at the corresponding levels in 0.5, 3.5, 6.5, 25.0, and 35.0% of cases respectively. Spondylolisthesis was observed in < 3% of this population. Multiple logistic regression analysis demonstrated that age and hours sitting were significantly related to L4-5 disc herniation. Episode of low-back pain, smoking status, body mass index, and hours standing did not affect the prevalence of disc degeneration. CONCLUSIONS: The current study established the baseline data of lumbar disc degeneration in a 30- to 55-year-old healthy population for a prospective longitudinal study. Hours spent sitting significantly increased the prevalence of disc herniation, but episode of low-back pain, smoking status, obesity, and standing hours were not significant risk factors.

Cervical spondylolysis in a judo player: a case report and biomechanical analysis.

STUDY DESIGN: A case report and a biomechanical study using a finite element method. OBJECTIVES: To report a case with the cervical spondylolysis and to understand the biomechanics of the cervical spine with spondylolysis at C6. Cervical spondylolysis, although not a common spinal disorder, can occur in athletes. Presently, the exact pathology, natural history and biomechanics are not known. Thus, treatment strategies for this disorder in athletes are in controversy. To treat and/or advise patients with cervical spondylolysis, the cervical spine biomechanics regarding this disorder should be understood. METHODS: A case of a 12-year-old male judo player is presented. The patient presented with occipital and upper neck pain. Plain radiographs, reconstructed CT scan and MRIs of this patient were reviewed. Biomechanically, stress distributions were analyzed in response to 73.6 N axial compression and 1.5-Nm moment in flexion, extension, lateral bending, and axial rotation using a FE model of the intact ligamentous C3 to C7 segment. Bilateral spondylolysis was created in the model at C6. The stress results from the bilateral defect model were compared to the intact model predictions. RESULTS: Plain radiographs showed bilateral C6 spondylolysis, and grade I spondylolisthesis. MRI showed mild disc degeneration at C6/7. With conservative treatment, the symptoms disappeared. In the spondylolysis model, the maximum Von Mises Stresses at C6/7 increased in all cervical spine motions, as compared to the intact case. Specifically, in axial rotation, the stress increase was 3.7-fold as compared to the intact model. The range of motion at C6/7 increased in the spondylolysis model as well. Again, during axial rotation, the increase in motion was 2.3-fold when compared to the intact model. CONCLUSIONS: Cervical spondylolysis can cause biomechanical alterations, especially in axial rotation, leading to increased disc stresses and range of motion. The increased stresses in the disc and the hypermobility would be a dangerous condition for athletes participating in contact sports such as judo. Thus, we recommended that judo players with cervical spondylolysis should change to non-contact sports, such as jogging.

Three dimensional finite element analysis of the pediatric lumbar spine. Part II: biomechanical change as the initiating factor for pediatric isthmic spondylolisthesis at the growth plate.

A non-linear 3-dimensional finite element pediatric lumbar spine model with vertebral growth plate and apophyseal bony ring was developed. Lumbar spondylolysis was simulated in the model. The Von Mises stresses in the structures surrounding the vertebral growth plate, including apophyseal bony ring and osseous endplate were calculated in various loading modes. Instantaneous axis of rotation (IAR) path from flexion to extension was also analyzed. The results were compared with those of the intact model and the literature. The IAR path was at the posterior disc-endplate space of the lower vertebra in the intact spine, and moved cranially towards the upper-posterior disc space in the lytic spine. This was in agreement with in vivo radiological data by Sakamaki et al. [19]. During various loading modes, stresses in the spondylolytic pediatric model were higher than that of the intact model; ranging from 1.1 to 6.0 times, with the highest value in extension at the growth plate. In conclusion, FE models indicate that stress concentrations in the lytic model increase at the growth plate which may lead to physis stress fracture leading to spondylolisthesis.

Three-dimensional finite element analysis of the pediatric lumbar spine. Part I: pathomechanism of apophyseal bony ring fracture.

The purpose of this study was to (1) develop a three-dimensional, nonlinear pediatric lumbar spine finite element model (FEM), and (2) identify the mechanical reasons for the posterior apophyseal bony ring fracture in the pediatric patients. The pediatric spine FE model was created from an experimentally validated three-dimensional adult lumbar spine FEM. The size of the FEM was reduced to 96% taking into account of the ratio of the sitting height of an average 14-years-old children to that of an adult. The pediatric spine was created with anatomically specific features like the growth plate and the apophyseal bony ring. For the stress analyses, a 10-N m moment was applied in all the six directions of motion for the lumbar spine. A preload of 351 N was applied which corresponds to the mean body weight of the 14-years-old group. The stresses at the apophyseal bony ring, growth plate and endplate were calculated. The results indicate that the structures surrounding the growth plate including apophyseal bony ring and osseous endplate were highly stressed, as compared to other structures. Furthermore, posterior structures in extension were in compression whereas in flexion they were in tension, with magnitude of stresses higher in extension than in flexion. Over time, the higher compression stresses along with tension stresses in flexion may contribute to the apophyseal ring fracture (fatigue phenomena).

JRAB/MICAL-L2 is a junctional Rab13-binding protein mediating the endocytic recycling of occludin.

The dynamic turnover of tight junctions (TJs) is essential for epithelial-mesenchymal transitions and/or mesenchymal-epithelial transitions during epithelial morphogenesis. We previously demonstrated that Rab13 specifically mediates the endocytic recycling of occludin. Here, we identified MICAL-L2 (molecule interacting with CasL-like 2) as a novel Rab13-binding protein. Immunoprecipitation and immunofluorescence microscopy showed that MICAL-L2 specifically bound to the GTP-bound form of Rab13 via its C terminus, which contained a coiled-coil domain, and localized at TJs in epithelial MTD-1A cells. Recycling assay demonstrated that a MICAL-L2 mutant lacking the Rab13-binding domain (MICAL-L2-N) specifically inhibited the endocytic recycling of occludin but not transferrin receptor. Ca2+ switch assay further revealed that MICAL-L2-N as well as Rab13 Q67L inhibited the recruitment of occludin to the plasma membrane, the development of transepithelial electrical resistance, and the formation of a paracellular diffusion barrier. MICAL-L2 was displaced from TJs upon actin depolymerization and was distributed along radiating actin cables and stress fibers in Ca2+-depleted MTD-1A and fibroblastic NIH3T3 cells, respectively. These results suggest that MICAL-L2 mediates the endocytic recycling of occludin and the formation of functional TJs by linking Rab13 to actin cytoskeleton. We rename MICAL-L2 as JRAB (junctional Rab13-binding protein).

MRI signal changes of the pedicle as an indicator for early diagnosis of spondylolysis in children and adolescents: a clinical and biomechanical study.

STUDY DESIGN: Clinical review of pediatric patients with lumbar spondylolysis and biomechanical analysis using finite-element lumbar spine model. OBJECTIVES: To evaluate the usefulness of the signal changes observed on MR images of the pedicle for the early diagnosis of spondylolysis, and to investigate the pathomechanism of the signal changes based on the stresses in pedicles, as predicted using finite-element analyses. Furthermore, to evaluate the usefulness of the signal change to predict the bony healing following conservative treatment. SUMMARY OF BACKGROUND DATA: Since early-stage spondylolysis can achieve osseous healing conservatively, it is important to diagnose this disorder as early as possible. Presently, there is no well-established, noninvasive, and reliable diagnostic tool for the early diagnosis. METHODS: Thirty-seven pediatric patients with spondylolysis were included. Sixty-eight defects were examined and their stages as revealed on CT scans were recorded. High signal changes (HSC) of the pedicles on axial T2-weighted MRI were compared with the CT-based stages of the defect. Among them, 16 patients, including 15 boys and 1 girl, were treated conservatively for at least a 3-month period. Bony healing of the fracture site was evaluated on CT, and the results were compared between two groups with or without HSC at the initial consultation. Using a three-dimensional nonlinear finite-element model of the L3-L5 segment, stress distributions in the pars and pedicle regions were analyzed in response to 400 N compression and 10.6 Nm moment. RESULTS: Based on CTs, 68 pars defects were classified as follows: 8 very early, 24 late-early, 16 progressive, and 20 terminal stages. All defects in very early and late-early stages (100%) showed HSC on T2-weighted MRI at the ipsilateral pedicle. Among 16 progressive stages, eight (50%) showed HSC, while no defects of the terminal stage (0%) were found to have HSC. In total, 29 pars defects were treated conservatively out of 16 patients. In 19 of the HSC positive defects, 15 (79%) showed bony healing after the conservative treatment, whereas none of the 10 HSC negative defects (0%) showed any healing. The results were statistically significant at P < 0.05 (chi). Stress results from the finite-element model indicated that pars interarticularis showed the highest value in all loading modes, and the pedicle showed the second highest. CONCLUSIONS: The correlation between the high stresses in the pedicle and the corresponding HSC suggest that signal changes in MRI could be used as an indicator for early diagnosis of spondylolysis. The HSC of the pedicle provided useful information to diagnose early stage spondylolysis. Furthermore, the HSC may be a good indicator as to whether a bony union will result from conservative treatment.

Rab13 mediates the continuous endocytic recycling of occludin to the cell surface.

During epithelial morphogenesis, adherens junctions (AJs) and tight junctions (TJs) undergo dynamic reorganization, whereas epithelial polarity is transiently lost and reestablished. Although ARF6-mediated endocytic recycling of E-cadherin has been characterized and implicated in the rapid remodeling of AJs, the molecular basis for the dynamic rearrangement of TJs remains elusive. Occludin and claudins are integral membrane proteins comprising TJ strands and are thought to be responsible for establishing and maintaining epithelial polarity. Here we investigated the intracellular transport of occludin and claudins to and from the cell surface. Using cell surface biotinylation and immunofluorescence, we found that a pool of occludin was continuously endocytosed and recycled back to the cell surface in both fibroblastic baby hamster kidney cells and epithelial MTD-1A cells. Biochemical endocytosis and recycling assays revealed that a Rab13 dominant active mutant (Rab13 Q67L) inhibited the postendocytic recycling of occludin, but not that of transferrin receptor and polymeric immunoglobulin receptor in MTD-1A cells. Double immunolabelings showed that a fraction of endocytosed occludin was colocalized with Rab13 in MTD-1A cells. These results suggest that Rab13 specifically mediates the continuous endocytic recycling of occludin to the cell surface in both fibroblastic and epithelial cells.

Fractures of the distal end of radius in elderly patients: a comparative study of anatomical and functional results.

The functional and anatomical results of distal end of radius fractures with severe displacement in 22 elderly patients are reviewed in this retrospective study. The mean age of the patients was 69.4 years (range, 60-88 years) and the mean follow-up period was 24 months (range, 12-53 months). According to the sum of demerit points (Saito, 1983), the latest follow-up functional end results were excellent in 64% of fractures and good in 36%. As for the anatomical results at follow-up, the average radial tilt was 20.7 degrees, ulnar variance was 4.0 mm, and palmar tilt was -2.7 degrees respectively. Though most of the patients had satisfactory outcome and the functional results did not correlate with the radiographic evidence of minor deformities, the functional results of the patients with radial shortening of 6 mm or over were poor. Furthermore, the grip power was the most significant factor related to subjective evaluation and did not improve significantly in patients with the non-dominant hand injured.