Immediate soft-tissue reconstruction using a rectus abdominis myocutaneous flap following wide resection of malignant bone tumours of the pelvis

Resection of malignant bony tumours of the pelvis creates large bone and soft-tissue defects, and is frequently associated with complications such as wound dehiscence and deep infection. We present the results of six patients in whom a rectus abdominis myocutaneous (RAM) flap was used following resection of a malignant tumour of the pelvis. Bony reconstruction was performed using a constrained hip tumour prosthesis in three patients, vascularised fibular graft in two and frozen autograft in one. At a mean follow-up of 63 months (16 to 115), no patients had a problem with the wound.

Immediate reconstruction using a RAM flap may be used after resection of a malignant tumour of the pelvis to provide an adequate volume of tissue to eliminate the dead space, cover the exposed bone or implants with well-vascularised soft tissue and to reduce the risk of complications.

Cite this article: Bone Joint J 2014;96-B:270–3.

SS18-SSX fusion protein-induced Wnt/β-catenin signaling is a therapeutic target in synovial sarcoma

Synovial sarcoma is a high-grade soft tissue malignancy characterized by a specific reciprocal translocation t(X;18), which leads to the fusion of the SS18 (SYT) gene to one of three SSX genes (SSX1, SSX2 or SSX4). The resulting chimeric SS18-SSX protein is suggested to act as an oncogenic transcriptional regulator. Despite multimodal therapeutic approaches, metastatic disease is often lethal and the development of novel targeted therapeutic strategies is required. Several expression-profiling studies identified distinct gene expression signatures, implying a consistent role of Wnt/β-catenin signaling in synovial sarcoma tumorigenesis. Here we investigate the functional and therapeutic relevance of Wnt/β-catenin pathway activation in vitro and in vivo. Immunohistochemical analyses of nuclear β-catenin and Wnt downstream targets revealed activation of canonical Wnt signaling in a significant subset of 30 primary synovial sarcoma specimens. Functional aspects of Wnt signaling including dependence of Tcf/β-catenin complex activity on the SS18-SSX fusion proteins were analyzed. Efficient SS18-SSX-dependent activation of the Tcf/β-catenin transcriptional complex was confirmed by TOPflash reporter luciferase assays and immunoblotting. In five human synovial sarcoma cell lines, inhibition of the Tcf/β-catenin protein-protein interaction significantly blocked the canonical Wnt/β-catenin signaling cascade, accompanied by the effective downregulation of Wnt targets (AXIN2, CDC25A, c-MYC, DKK1, CyclinD1 and Survivin) and the specific suppression of cell viability associated with the induction of apoptosis. In SYO-1 synovial sarcoma xenografts, administration of small molecule Tcf/β-catenin complex inhibitors significantly reduced tumor growth, associated with diminished AXIN2 protein levels. In summary, SS18-SSX-induced Wnt/β-catenin signaling appears to be of crucial biological importance in synovial sarcoma tumorigenesis and progression, representing a potential molecular target for the development of novel therapeutic strategies.

Endogenous estrogen may prevent bone loss in postmenopausal hemodialysis patients throughout life

SUMMARY

Postmenopausal hemodialysis patients are at risk of complications related to renal mineral and bone disorder, and postmenopausal osteoporosis. In 112 postmenopausal hemodialysis patients, free estrogen index was positively correlated with bone mineral density (BMD) Z-score and the annual percent change of BMD in multiple regression analysis. Endogenous estrogen may prevent bone loss in postmenopausal hemodialysis patients throughout life.

INTRODUCTION

Women on dialysis are not only at risk of developing mineral and bone disorder, but also suffer from postmenopausal osteoporosis. We assessed the effect of sex hormones on bone metabolism in postmenopausal hemodialysis patients.

METHODS

We enrolled 112 postmenopausal hemodialysis patients with a mean age of 68.4 ± 10.4 years. We measured the serum levels of estradiol, testosterone, sex hormone-binding globulin (SHBG), and intact parathyroid hormone (intact-PTH), as well as bone metabolism parameters and radial bone mineral density (BMD). The free estrogen index (FEI) was calculated from the estradiol and SHBG values. After conventional dialysis was performed for 12 months, BMD was measured again and the annual percent change was calculated. Estradiol and SHBG were also measured in 25 postmenopausal women without chronic kidney disease.

RESULTS

Estradiol levels were higher in the hemodialysis patients than in the postmenopausal women without chronic kidney disease. In patients with relatively normal bone turnover (intact-PTH: from 150 to 300 pg/ml), the FEI showed a positive correlation with the BMD Z-score. The annual percent change of BMD showed a positive correlation with the FEI according to multiple regression analysis.

CONCLUSIONS

Endogenous estrogen may prevent bone loss in postmenopausal hemodialysis patients throughout life.

Correction of severe open bite using miniscrew anchorage

This report describes the treatment of a case of severe open bite with posterior crossbite. While treating open bite, the outcome may not always be successful with orthodontic therapy alone. In such cases, surgical therapy is often chosen to gain a stable occlusion. Skeletal anchorage systems such as miniscrews are now frequently used for correcting severe malocclusion. In this report, we treated an open bite by intruding the molars with miniscrews placed bilaterally in the interdental space between both the upper and lower posterior teeth. The active treatment period was 36 months and the patient's teeth continued to be stable after a retention period of 36 months.

Construct validity of the Enneking score for measuring function in patients with malignant or aggressive benign tumours of the upper limb

We evaluated the construct validity of the Musculoskeletal Tumour Society rating scale (Enneking score) as a functional measure for patients with sarcoma involving the upper limb. We compared the Enneking score by examining the correlation between two patient-derived outcome measures, the Disability of the Arm, Shoulder, and Hand (DASH) questionnaire and the Medical Outcomes Study Short Form-36 (SF-36) as indicators of functional status in 40 patients with malignant or aggressive benign bone and soft-tissue tumours of the upper limb who had undergone surgical treatment. The frequency distributions were similar among the three scoring systems. As for the validity, Spearman's rank correlation coefficient of the Enneking score to the DASH questionnaire was -0.79 and that of the Enneking to the SF-36 subscales ranged from 0.38 to 0.60. Despite being a measure from the surgeon's perspective, the Enneking score was shown to be a valid indicator of physical disability in patients with malignant or aggressive benign tumours of the upper limb and reflected their opinion.

Different origins of bird and reptile sex chromosomes inferred from comparative mapping of chicken Z-linked genes

Recent progress of chicken genome projects has revealed that bird ZW and mammalian XY sex chromosomes were derived from different autosomal pairs of the common ancestor; however, the evolutionary relationship between bird and reptilian sex chromosomes is still unclear. The Chinese soft-shelled turtle (Pelodiscus sinensis) exhibits genetic sex determination, but no distinguishable (heteromorphic) sex chromosomes have been identified. In order to investigate this further, we performed molecular cytogenetic analyses of this species, and thereby identified ZZ/ZW-type micro-sex chromosomes. In addition, we cloned reptile homologues of chicken Z-linked genes from three reptilian species, the Chinese soft-shelled turtle and the Japanese four-striped rat snake (Elaphe quadrivirgata), which have heteromorphic sex chromosomes, and the Siam crocodile (Crocodylus siamensis), which exhibits temperature-dependent sex determination and lacks sex chromosomes. We then mapped them to chromosomes of each species using FISH. The linkage of the genes has been highly conserved in all species: the chicken Z chromosome corresponded to the turtle chromosome 6q, snake chromosome 2p and crocodile chromosome 3. The order of the genes was identical among the three species. The absence of homology between the bird Z chromosome and the snake and turtle Z sex chromosomes suggests that the origin of the sex chromosomes and the causative genes of sex determination are different between birds and reptiles.

Functional similarities of a thermostable protein-disulfide oxidoreductase identified in the archaeon Pyrococcus horikoshii to bacterial DsbA enzymes

We have isolated and characterized a gene for a putative protein-disulfide oxidoreductase (phdsb) in the archaeon Pyrococcus horikoshii. The open reading frame of phdsb encodes a protein of 170 amino acids with an NH(2)-terminal extension similar to the bacterial signal peptides. The putative mature region of PhDsb includes a sequence motif, Cys-Pro-His-Cys (CPHC), that is conserved in members of the bacterial DsbA family, but otherwise the archaeal and bacterial sequences do not show substantial similarity. A recombinant protein corresponding to the predicted mature form of PhDsb behaved as a monomer and manifested oxidoreductase activities in vitro similar to those of DsbA of Escherichia coli. The catalytic activity of PhDsb was thermostable and was shown by mutation analysis to depend on the NH(2)-terminal cysteine residue of the CPHC motif. Thus, in spite of their low overall sequence similarities, DsbA-like proteins of archaea and bacteria appear to be highly similar in terms of function.

Clear cell sarcoma of tendons and aponeuroses: An analysis of 75 cases

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Background: Clear cell sarcoma (CCS) of tendons and aponeuroses is a rare malignant tumor that occurs most commonly in the extremities of young adults. Because of the rarity of the disease (1% of all soft tissue sarcomas), most reports about CCS have dealt with a few cases during a long time period. We conducted a multi-institutional study of CCS to clarify the clinical findings and prognostic factors of CCS treated during the era of modern multidisciplinary treatment. Methods: The records of 75 consecutive patients with histologically confirmed CCS treated at the JMOG affiliated institutions between 1980 and 2004 (follow-up; average 44 months) were reviewed. There were 41 men and 34 women with an average age of 36 years (range, 10–71 years). 65 tumors were in the extremities (foot 22, hand 13, thigh 9, others 21) and 10 were in the trunk. The tumor size ranged from 1 to 11 cm (mean, 4 cm). 52 patients presented with localized disease (M0) and 23 with metastatic disease (M1). Results: Surgical excision of the primary tumor was performed in 71 patients (limb-sparing surgery; 56, amputation; 15). Microscopic surgical margin was negative in 60 and positive in 11. 56 patients received chemotherapy (30 with measurable disease) and 17 had radiotherapy. Local recurrence occurred in 16 patients and 48 patients developed metastasis. The 5-year overall survival rate was 47% (M0; 55%, M1; 20%). On univariate analysis, sex (p=0.02), size (p=0.001), depth (p=0.002), TNM stage (p=0.001), IRS group (p=0.001) and surgical margin (p=0.04) were prognostic factors. On multivariate analysis, size (p=0.02) remained to be a significant prognostic factor. Objective response to chemotherapy was observed in 8 (27%) patients. In the group of M0 patients, those who received adjuvant chemotherapy had better prognosis (5-year survival, 65%) than those without chemotherapy (5-year survival, 23%)(p=0.03). Conclusions: The results support the contention that early diagnosis and initial excision with negative surgical margin are essential for favorable outcome of CCS. The role of chemotherapy for CCS should be further investigated.

No significant financial relationships to disclose.

Immobilization of diverse foreign proteins in viral polyhedra and potential application for protein microarrays

Cypoviruses are insect viruses that produce a cytoplasmic crystalline particle called the polyhedron in which progeny virions are occluded. The virion structural protein, VP3, is implicated in the occlusion of viral particles into polyhedra. In this study, we determined the amino acid sequence of VP3 required for occlusion of viral particles into polyhedra and proposed that this sequence could be used as an immobilization signal to direct the stable incorporation of foreign proteins into polyhedra. A large-scale survey revealed that the immobilization signal could, in fact, direct the incorporation of a variety of human proteins into polyhedra. Immune reactivity and protein-protein interactions were detected on the surface of polyhedra containing immobilized foreign proteins, and these particles were shown to be highly stabilized against dehydration. We showed that these particles could be arrayed onto a glass slide by standard spotting and laser manipulation methods. Thus, this approach is well suited for protein expression, purification, and the development of protein microarrays.

A practical approach to the clinical diagnosis of Ewing's sarcoma/primitive neuroectodermal tumour and other small round cell tumours sharing EWS rearrangement using new fluorescence in situ hybridisation probes for EWSR1 on formalin fixed, paraffin wax embedded tissue

BACKGROUND

Over 90% of Ewing's sarcoma/primitive neuroectodermal tumour (ES/PNET) cases have the t(11;22) chromosomal rearrangement, which is also found in other small round cell tumours, including desmoplastic small round cell tumour (DSRCT) and clear cell sarcoma (CCS). Although this rearrangement can be analysed by fluorescence in situ hybridisation (FISH) using routinely formalin fixed, paraffin wax embedded (FFPE) tissues when fresh or frozen tissues are not available, a sensitive and convenient detection method is needed for routine clinical diagnosis.

AIMS

To investigate the usefulness of newly developed probes for detecting EWS rearrangement resulting from chromosomal translocations using FISH and FFPE tissue in the clinical diagnosis of ES/PNET, DSRCT, and CCS.

METHODS

Sixteen ES/PNETs, six DSRCTs, and six CCSs were studied. Three poorly differentiated synovial sarcomas, three alveolar rhabdomyosarcomas, and three neuroblastomas served as negative controls. Interphase FISH analysis was performed on FFPE tissue sections with a commercially available EWSR1 (22q12) dual colour, breakapart rearrangement probe.

RESULTS

One fused signal and one split signal of orange and green, demonstrating rearrangement of the EWS gene, was detected in 14 of 16 ES/PNETs, all six DRSCTs, and five of six CCSs, but not in the negative controls.

CONCLUSIONS

Interphase FISH using this newly developed probe is sensitive and specific for detecting the EWS gene on FFPE tissues and is of value in the routine clinical diagnosis of ES/PNET, DSRCT, and CCS.

Nanoscale hydrophobic interaction and nanobubble nucleation

We report large-scale atomistic simulation of midrange nanoscale hydrophobic interaction, manifested by the nucleation of nanobubble between nanometer-sized hydrophobes at constrained equilibrium. When the length scale of the hydrophobes is greater than 2 nm, the nanobubble formation shows hysteresis behavior resembling the first-order transition. Calculation of the potential of mean force versus interhydrophobe distance provides a quantitative measure of the strength of the nanoscale hydrophobic interaction.