Masakazu Takemitsu

Dystrophin-related protein in the fetal and denervated skeletal muscles of normal and mdx mice

The amino acid sequence of the polyclonal antibodies we developed against the carboxyl terminus of the dystrophin-related protein, the putative gene product of B3 cDNA, had no homologous sequence to the dystrophin molecule except for two amino acids located at its ends for immunization. By immunohistochemical examination in C57B1/10ScSn and C57B1/10ScSn-mdx mice we found that the DRP was expressed on the surface membrane of fetal muscle fibers, was assembled at the neuromuscular junctions of the mature muscle fibers, and reappeared on the surface membrane of muscle fibers after denervation. Its localization was similar to that of the acetylcholine receptor, suggesting that DRP is one of the cytoskeletons which organize and stabilize the cytoplasmic domain of the acetylcholine receptor.

A prospective study of de novo scoliosis in a community based cohort.

Study Design. A 12-year prospective study of de novo scoliosis in a community based cohort. Objective. To investigate factors associated with development of de novo scoliosis. Summary of Background Data. De novo scoliosis is becoming one of the most prevalent findings in the aging spine, and this condition is associated not only with severe back or leg symptoms but also with complicated surgical outcomes. Cross-sectional studies were limited in distinguishing de novo scoliosis from preexisting deformities, and there had been controversies over the etiology of degenerative scoliosis. Methods. Community based volunteers were recruited, then examined by orthopedic physicians. Radiologic measurements using entire spine radiographs included the angle of scoliosis and sagittal spinal curvatures, sagittal spinal balance, grade of bone atrophy, number of degenerated discs, and vertebral fractures. We defined radiologic parameters, the disc index, and lateral osteophyte difference to evaluate the asymmetrical spinal degeneration. Results. A total of 60 subjects aged 50–84 years and without scoliosis at baseline were selected and followed for a mean of 12.0 years. De novo scoliosis ≥10° developed in 22 subjects, and logistic regression analysis revealed that the baseline disc index and lateral osteophyte difference values were independent predictors (P < 0.05). Conclusions. Incidence of de novo scoliosis was predictable by assessing asymmetric disc degeneration in frontal radiograph. More than 20% decrease in unilateral disc height or more than 5 mm longer osteophyte on one side led to increased incidence of de novo scoliosis, which might also influence long-term results of spinal surgery.

Recovery of the missing tumorigenicity in mitochondrial DNA-less HeLA cells by introduction of mitochondrial DNA from normal human cells

The role of mitochondrial DNA (mtDNA) in the expression of the transformed phenotype was examined using mtDNA-less HeLa cells. Complete depletion of mtDNA and its products in the mtDNA-less HeLa cell line, EB8, was confirmed by Southern blot analysis and by [35S]methionine labeling of mitochondrially synthesized polypeptides. The tumorigenicity of the EB8 cells was assayed by inoculation of 1×107 cells subcutaneously into the backs of nude mice. The results showed that the tumorigenicity of HeLa cells was lost in good correspondence with the loss of mtDNA. However, the growth of EB8 cells in culture was very poor compared with that of HeLa cells, indicating that the apparent loss of tumorigenicity in EB8 cells could possibly be due to poor growth of the cells. Introduction of mtDNA from normal human fibroblasts into EB8 cells restored both the missing tumorigenicity and growth of the EB8 cells. These observations could be interpreted to show that mtDNA is required for expression of tumorigenicity, but that mutational changes of the mtDNA are not required for modulation of the phenotype in our experiments.

Does the intraoperative tranexamic acid decrease operative blood loss during posterior spinal fusion for treatment of adolescent idiopathic scoliosis

Study Design. Retrospective, observational study. Objective. To assess the efficacy and safety of tranexamic acid (TXA) in decreasing operative blood loss and the need for transfusion during posterior spinal fusion for the treatment of idiopathic scoliosis in adolescents. Summary of Background Data. Blood loss associated with spinal surgery is a common potential cause of morbidity and often requires a blood transfusion, which subjects patients to the known risks of blood transfusion including transmission of diseases. Since the 1990s, intraoperative administration of antifibrinolytics has gained popularity. This study assesses the efficacy and safety of TXA in controlling blood loss during posterior spinal fusion for the treatment of idiopathic scoliosis in adolescents at 1 institution. Methods. A retrospective comparative analysis of 106 consecutive adolescents undergoing posterior spinal fusion procedures at 1 institution was performed. Patients were analyzed according to treatment group: controls (63) and TXA (43). There were no significant differences in demographic (age, sex, and comorbidities) or surgical traits (surgical time, number of fused vertebrae, preoperative hematocrit and hemoglobin) between the 2 groups. Results. TXA group had significantly less intraoperative blood loss (613 ± 195 mL) than the control group (1079 ± 421 mL; P < 0.001) as well as postoperative blood loss (155 ± 86 mL and 263 ± 105 mL, respectively; P < 0.001). TXA group received significantly less blood during the surgical procedure than the control group (258 ± 246 mL and 377 ± 200 mL, respectively; P < 0.001). There were no major intraoperative complications for any of the treatment groups. Conclusion. TXA treatment group lost significantly less blood and received significantly fewer blood transfusions than the control group without significant differences in intra- and postoperative complications. A multicenter randomized prospective analysis would provide additional information of the efficacy and safety of TXA.

Reoperation rate and risk factors of elective spinal surgery for degenerative spondylolisthesis: minimum 5-year follow-up

BACKGROUND CONTEXT The favorable outcome of surgical treatment for degenerative lumbar spondylolisthesis (DS) is widely recognized, but some patients require reoperation because of complications, such as pseudoarthrosis, persistent pain, infection, and progressive degenerative changes. Among these changes, adjacent segmental disease (ASD) and same segmental disease (SSD) are common reasons for reoperation. However, the relative risks of the various factors and their interactions are unclear. PURPOSE The purpose of this study was to determine the longitudinal reoperation rate after surgery for DS and to assess the incidence and independent risk factors for ASD and SSD. STUDY DESIGN This study is a retrospective consecutive case series of patients with DS who were surgically treated. PATIENT SAMPLE We assessed 163 consecutive patients who were surgically treated for DS between 2003 and 2008. Individual patients were followed for at least 5 years after the initial surgery. OUTCOME MEASURES The primary end point was any type of second lumbar surgery. Radiographic measurements and demographic data were reviewed. We compared patients who underwent reoperation with those who did not. Logistic regression analysis was used to determine the relative risk of ASD and SSD in patients surgically treated for DS. METHODS Radiographic measurements and demographic data were reviewed. We identified the incidence and risk factors for reoperation, and we performed univariate and multivariate analyses to determine the independent risk factors for revision surgery for SSD and for ASD as the two distinct reasons for the reoperation. Age, gender, etiology, body mass index (BMI), and other radiographic data were analyzed to determine the risk factors for developing SSD and ASD. RESULTS The average patient age was 65.8 (50-81 years; 73 women and 90 men; mean follow-up, 5.9±1.6 years). Eighty-nine patients had posterior lumbar interbody fusion and 74 had laminotomies. Twenty-two patients had L3-L4 involvement and 141 had L4-L5 involvement. The cumulative reoperation rate was 6.1% at 1 year, 8.5% at 2 years, 15.2% at 3 years, 17.7% at 5 years, and 23.3% (38/163 patients) at the final follow-up. A significantly higher reoperation rate was observed for patients undergoing laminotomy than for patients undergoing posterior lumbar interbody fusion (33.8% vs. 14.4%, p=.01). Eighteen patients (11.0%) had SSD, and 13 patients (8.9%) developed ASD. Higher BMI (obesity) and greater disc height (greater than 10 mm) predicted the occurrence of SSD in the multivariate model (BMI=odds ratio 4.11 [95% confidence interval 1.29-13.11], p=.016; disc height=3.18 [1.03-9.82], p=.044), and gender (male) and facet degeneration (Fujiwara grade greater than 3) predicted the development of ASD in the multivariate model (gender=4.74 [1.09-20.45], p=.037; facet degeneration=6.31 [1.09-36.52], p=.039). CONCLUSIONS The incidence of reoperation in patients surgically treated for DS was 23.2% at a mean time of 5.9 years. A significantly higher incidence of reoperation was observed in patients treated with decompression alone compared with those treated with decompression and fusion. Body mass index and disc height were identified as independent risk factors for SSD, whereas male gender and facet degeneration were identified as independent risk factors for ASD. The results of this comprehensive review will guide spine surgeons in their preoperative planning and in the surgical management of patients with DS, thereby reducing the reoperation rate.

Low back pain in pediatric athletes with unilateral tracer uptake at the pars interarticularis on single photon emission computed tomography

Study Design. Retrospective clinical study with radiographic and medical chart review. Objective. To study the clinical characteristics and outcome of pediatric athletes with low back pain and unilateral tracer uptake on single photon emission computed tomography (SPECT) at the pars interarticularis but no defect on radiographs. Summary of Background Data. Some pediatric athletes with low back pain have no findings on plain radiographs but a unilateral SPECT uptake at the pars interarticularis. However, little is known about these patients. Methods. Twenty-two pediatric athletes who had low back pain with increased tracer uptake on SPECT unilaterally at the pars interarticularis but no defect on plain radiograph were evaluated. The following criteria were used for evaluation: age, male-to-female ratio, duration of symptoms, vertebral level, and presence of spina bifida occulta or scoliosis. Results. The average age was 12.3 ± 2.5 years. The male-to-female ratio was 1.2:1. The average duration of symptoms was 21 ± 23 weeks. Nineteen (86%) had increased uptake at L5. Six (27%) had spina bifida occulta and 8 (36%) had scoliosis. Eighteen (82%) patients showed an excellent outcome. The patients who presented with a longer history of symptoms or a concomitant spina bifida occulta had an increased risk of having occasional aching with vigorous activity when compared with the patients who did not (P < 0.05). Conclusions. Athletes who have low back pain and increased tracer uptake unilaterally at the pars interarticularis on SPECT are younger than those previously reported patients with spondylolysis proven by a defect on radiographs. Some of these lesions do progress to “frank” spondylolysis seen on radiographs, but favorable clinical outcomes from nonoperative treatment can be expected. Patients with a longer pain history or concomitant spina bifida occulta may need careful follow-up because they are at increased risk of having occasional low back pain.

Dystrophin-related protein in skeletal muscles in neuromuscular disorders: immunohistochemical study

SummaryThirty-four biopsied muscles of Duchenne, Becker and congenital muscular dystrophy, congenital myotonic dystrophy and amyotrophic lateral sclerosis were exmined by an immunocytochemical method with an anti-dystrophin-related protein (DRP) antibody. Strongly positive immunoreaction to DRP at the neuromuscular junctions in all biopsied specimens and faint reaction on the surface membrane of atrophic fibers in amyotrophic lateral sclerosis suggest that DRP is an anchor protein of the acetylcholine receptor. Additionally, the surface membrane of muscle fibers of Duchenne muscular dystrophy was positively stained. DRP is, therefore, thought to be expressed to compensate for dystrophin deficiency in these muscle fibers.

Presence of emerinopathy in cases of rigid spine syndrome

Rigid spine syndrome (RSS) shows clinical similarities to Emery-Dreifuss muscular dystrophy (EDMD). Differential diagnosis between EDMD and RSS is essential because EDMD is often associated with life-threatening cardiomyopathy that can be cured by an implantation of a cardiac pacemaker. To determine if any of the patients with RSS had mutations of the emerin gene (responsible gene for X-linked EDMD or emerinopathy), we screened the patients for mutations. We found seven patients with a clinical picture consistent with RSS in the 6500 diagnostic muscle biopsies in our National Center over the last 19 years. We identified a novel mutation in the gene (1-bp frame-shift deletion in the exon 1) in one of the seven patients with RSS. This mutation created a premature termination at codon 12 and was expected to produce a severely truncated emerin. Emerin was not detected in the skeletal muscle. The unaffected mother of the patient was a heterozygous carrier for the mutation. The remaining six patients with RSS had no mutation in the gene and showed normal expression of emerin in the skeletal muscle. Our results emphasize the presence of clinical overlap between possible RSS and EDMD, and reinforce the necessity of molecular genetic diagnosis of emerin to exclude emerinopathy in a patient population that has a clinical diagnosis of RSS.

Immunoblot analysis of dystrophin-related protein (DRP)

Polyclonal antibodies against the carboxy-terminal portion of dystrophin-related protein (DRP), the putative autosomal gene product which shares sequence homology with dystrophin, show the clear expression of DRP in mouse fetal muscle and in cultured human muscle cells, but not in mature mouse or human muscle. DRP has the same molecular mass as X-linked dystrophin and is recovered from the membrane fraction, but is associated with membranes more loosely than dystrophin.

Selective defect in dystrophin-associated glycoproteins 50DAG (A2) and 35DAG (A4) in the dystrophic hamster: an animal model for severe childhood autosomal recessive muscular dystrophy (SCARMD).

To determine if dystrophin and dystrophin-associated glycoproteins (DAGs) are involved in muscle fiber necrosis in the dystrophic hamster, we examined NSJ-my/my (homozygous dystrophic) hamsters introduced from the BIO14.6 strain, by immunohistochemical and immunoblotting methods. Antibodies against dystrophin, utrophin and DAGs including 50DAG (A2), 43DAG (A3a) and 35DAG (A4) were employed for the examination. Dystrophin was stained strongly and utrophin stained very faintly along the sarcolemma of the dystrophic hamster, similar to the control. On the other hand, in the dystrophic hamster 50DAG (A2) and 35DAG (A4) were selectively defective, and 43DAG (A3a) was also decreased, although to a lesser degree. Since these results were almost identical to those seen in severe childhood autosomal recessive muscular dystrophy (SCARMD), the dystrophic hamster appears to be an animal model of SCARMD in which defects in DAGs may result in muscle fiber necrosis despite normal dystrophin expression.