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1.  Comparison between Bilateral C2 Pedicle Screwing and Unilateral C2 Pedicle Screwing, Combined with Contralateral C2 Laminar Screwing, for Atlantoaxial Posterior Fixation 
Asian Spine Journal  2014;8(6):777-785.
Study Design
A retrospective study.
Purpose
To compare clinical and radiological outcomes between bilateral C2 pedicle screwing (C2PS) and unilateral C2PS, combined with contralateral C2 laminar screwing (LS), for posterior atlantoaxial fixation.
Overview of Literature
Posterior fixation with C1 lateral mass screwing (C1LMS) and C2PS (C1LMS-C2PS method) is an accepted procedure for rigid atlantoaxial stabilization. However, conventional bilateral C2PS is not always allowed in this method due to anatomical variations of C2 pedicles and/or asymmetry of the vertebral artery. Although unilateral C2PS plus contralateral LS (C2PS+LS) is an alternative in such cases, the efficacy of this procedure has not been evaluated in controlled studies (i.e., with bilateral C2PS as a control).
Methods
Clinical and radiological records of patients who underwent the C1LMS-C2PS method, using unilateral C2PS+LS (n=9), and those treated using conventional bilateral C2PS (n=10) were compared, with a minimum two years follow-up.
Results
Postoperative complications related to the unilateral C2PS+LS technique included one case of spontaneous spinous process fracture of C2. A C1 anterior arch fracture occurred after a fall in one patient, who underwent bilateral C2PS and C1 laminectomy. No significant differences were seen between the groups in reduction of neck pain after surgery or improvement of neurological status, as evaluated using the Japanese Orthopaedic Association score. A delayed union occurred in one patient each of the groups, with the final fusion rate being 100% in both groups.
Conclusions
Clinical and radiological outcomes of unilateral C2PS+LS were comparable with those of the bilateral C2PS fixation technique for the C1LMS-C2PS method.
doi:10.4184/asj.2014.8.6.777
PMCID: PMC4278983  PMID: 25558320
Cervical spine; Atlantoaxial instability; Laminar screw; Pedicle screw
2.  Gossypiboma 19 years after laminectomy mimicking a malignant spinal tumour: a case report 
Introduction
Gossypiboma is rare and mostly asymptomatic in chronic cases. It can be confused with other soft tissue masses.
Case presentation
Our patient was an 87-year-old Japanese man with a history of surgery for a lumbar lesion causing lumbar canal stenosis 19 years earlier. Computed tomography showed a soft tissue mass with osteolysis and periosteal thickening of the vertebral lamina. On magnetic resonance imaging, the mass showed heterogeneous signal intensity on T2-weighted imaging, suggesting a malignancy. At the time of biopsy, small pieces of retained surgical sponge were collected. Surgical treatment was performed to excise the soft tissue tumour.
Conclusions
Gossypiboma should be included in the differential diagnosis of soft tissue masses in the paraspinal region in patients with a history of previous spinal surgery.
doi:10.1186/1752-1947-8-311
PMCID: PMC4177374  PMID: 25236490
Foreign body; Gossypiboma; Laminectomy; Malignant spinal tumour; Retained surgical sponge; Spinal surgery
3.  Restoration of Mismatch Repair Functions in Human Cell Line Nalm-6, Which Has High Efficiency for Gene Targeting 
PLoS ONE  2013;8(4):e61189.
Gene targeting is a powerful approach in reverse genetics. The approach has been hampered in most of human cell lines, however, by the poor targeting efficiency. Nalm-6, a human pre-B acute lymphoblastic leukemia cell line, exhibits exceptionally high gene targeting efficiency and is used in DNA repair and the related research fields. Nonetheless, usage of the cell line is still limited partly because it lacks expression of MSH2, a component of mismatch repair complex, which leads to increased genome instability. Here, we report successful restoration of MSH2 expression in Nalm-6 cells and demonstrate that the recovery does not affect the high targeting efficiency. We recovered the expression by introduction of cDNA sequences corresponding to exons 9 to 16 at downstream of exon 8 of the MSH2 gene. Endogenous exons 9 to 16 were deleted in the cell line. The MSH2 expression substantially reduced spontaneous HPRT mutation frequency. Moreover, gene targeting efficiency in the MSH2-expressing cells was similar to that in the MSH2-lacking cells. In fact, we generated heterozygously REV3L knockout and the catalytically dead mutants in the MSH2-proficient Nalm-6 cells with efficiency of 20–30%. The established cell line, Nalm-6-MSH+, is useful for reverse genetics in human cells.
doi:10.1371/journal.pone.0061189
PMCID: PMC3626652  PMID: 23596518
4.  Patient-specific finite element analysis of viscoelastic masticatory mucosa 
Journal of Dental Biomechanics  2013;4:1758736013483298.
The purpose of this study was to analyze the stress and strain inside of the oral mucosa in partially-edentulous patients. The patient-specific finite element models of the mucosa and the bone were constructed using the CT images and in-vivo surface measurement during a continuous load. The mean initial shear modulus of 8.3 × 10–5 (GPa) and the mean relaxation time of 503 (s) were determined as the viscoelastic properties of the mucosa. The increase of the highest maximum compressive strain during the continuous loading was observed in all the patients, however; the intensity of strain was not in accordance with the thickness of the mucosa. It is suggested that the variations of the morphology and the initial modulus of the mucosa should be considered in the mathematical approaches to detect the mechanical responses of the oral mucosa.
doi:10.1177/1758736013483298
PMCID: PMC3619231  PMID: 23580171
Mucosa; viscoelastic; edentulous; denture; finite element; pain
5.  Symptomatic cervical disc herniation in teenagers: two case reports 
Introduction
The development of a symptomatic herniated cervical disc before the age of 20 is extremely rare. Sporadically reported cases of patients with cervical disc herniation under the age of 20 usually have had underlying disease.
Case presentation
Case 1: A 19-year-old Asian man visited our clinic and presented with progressive pain in his upper left scapula and weakness of the left deltoid and biceps brachii muscles. C5 radiculopathy by soft disc herniation at C4-C5 without calcification was diagnosed. Microsurgical posterior foraminotomy was performed and he recovered completely eight weeks after the surgery.
Case 2: A 15-year-old Asian man presented with difficulty in lifting his arm and neck pain on the right side. Neurological examination showed weakness of the right deltoid and biceps brachii muscles. A magnetic resonance imaging scan demonstrated a herniated intervertebral disc in the right C4-C5 foramen. The patient was treated conservatively and put under observation only, and had completely recovered eight weeks after admission.
Conclusion
Although extremely rare, symptomatic cervical disc herniations may occur even in the younger population under the age of 20 without any trauma or underlying disease. Favorable outcomes can be achieved by conventional treatments for cervical disc herniation.
doi:10.1186/1752-1947-7-42
PMCID: PMC3599747  PMID: 23402661
6.  Anterior Decompression and Shortening Reconstruction with a Titanium Mesh Cage through a Posterior Approach Alone for the Treatment of Lumbar Burst Fractures 
Asian Spine Journal  2012;6(2):123-130.
Study Design
A retrospective study.
Purpose
To examine the efficacy and safety for a posterior-approach circumferential decompression and shortening reconstruction with a titanium mesh cage for lumbar burst fractures.
Overview of Literature
Surgical decompression and reconstruction for severely unstable lumbar burst fractures requires an anterior or combined anteroposterior approach. Furthermore, anterior instrumentation for the lower lumbar is restricted through the presence of major vessels.
Methods
Three patients with an L1 burst fracture, one with an L3 and three with an L4 (5 men, 2 women; mean age, 65.0 years) who underwent circumferential decompression and shortening reconstruction with a titanium mesh cage through a posterior approach alone and a 4-year follow-up were evaluated regarding the clinical and radiological course.
Results
Mean operative time was 277 minutes. Mean blood loss was 471 ml. In 6 patients, the Frankel score improved more than one grade after surgery, and the remaining patient was at Frankel E both before and after surgery. Mean preoperative visual analogue scale was 7.0, improving to 0.7 postoperatively. Local kyphosis improved from 15.7° before surgery to -11.0° after surgery. In 3 cases regarding the mid to lower lumbar patients, local kyphosis increased more than 10° by 3 months following surgery, due to subsidence of the cages. One patient developed severe tilting and subsidence of the cage, requiring additional surgery.
Conclusions
The results concerning this small series suggest the feasibility, efficacy, and safety of this treatment for unstable lumbar burst fractures. This technique from a posterior approach alone offers several advantages over traditional anterior or combined anteroposterior approaches.
doi:10.4184/asj.2012.6.2.123
PMCID: PMC3372547  PMID: 22708016
Lumbar spine; Burst fracture; Posterior approach
7.  Template properties of mutagenic cytosine analogues in reverse transcription 
Nucleic Acids Research  2006;34(22):6438-6449.
We have studied the mutagenic properties of ribonucleotide analogues by reverse transcription to understand their potential as antiretroviral agents by mutagenesis of the viral genome. The templating properties of nucleotide analogues including 6-(β-D-ribofuranosyl)-3,4-dihydro-8H-pyrimido[4,5-c](1,2)oxazin-7-one, N4-hydroxycytidine, N4-methoxycytidine, N4-methylcytidine and 4-semicarbazidocytidine, which have been reported to exhibit ambiguous base pairing properties, were examined. We have synthesized RNA templates using T3 RNA polymerase, and investigated the specificity of the incorporation of deoxyribonucleoside triphosphates opposite these cytidine analogues in RNA by HIV and AMV reverse transcriptases. Except for N4-methylcytidine, both enzymes incorporated both dAMP and dGMP opposite these analogues in RNA. This indicates that they would be highly mutagenic if present in viral RNA. To study the basis of the differences among the analogues in the incorporation ratios of dAMP to dGMP, we have carried out kinetic analysis of incorporation opposite the analogues at a defined position in RNA templates. In addition, we examined whether the triphosphates of these analogues were incorporated competitively into RNA by human RNA polymerase II. Our present data supports the view that these cytidine analogues are mutagenic when incorporated into RNA, and that they may therefore be considered as candidates for antiviral agents by causing mutations to the retroviral genome.
doi:10.1093/nar/gkl761
PMCID: PMC1702492  PMID: 17130163

Results 1-7 (7)