Actin filaments-stabilizing and -bundling activities of cofilin-phosphatase Slingshot-1

Slingshot-1 (SSH1) is known to regulate actin filament dynamics by dephosphorylating and activating cofilin, an actin-depolymerizing factor. SSH1 binds to filamentous (F-) actin through its multiple F-actin-binding sites and its cofilin-phosphatase activity is enhanced by binding to F-actin. In this study, we demonstrate that SSH1 has F-actin-stabilizing and -bundling activities. In vitro actin depolymerization assays revealed that SSH1 suppressed spontaneous and cofilin-induced actin depolymerization in a dose-dependent manner. SSH1 inhibited F-actin binding and severing activities of cofilin. Low-speed centrifugation assays combined with fluorescence and electron microscopic analysis revealed that SSH1 has F-actin-bundling activity, independently of its cofilin-phosphatase activity. Deletion of N- or C-terminal regions of SSH1 significantly reduced its F-actin-stabilizing and -bundling activities, indicating that both regions are critical for these functions. As SSH1 does not form a homodimer, it probably bundles F-actin through its multiple F-actin-binding sites. Knockdown of SSH1 expression by RNA interference significantly suppressed stress fiber formation in C2C12 myoblast cells, indicating a role for SSH1 in stress fiber formation or stabilization in cells. SSH1 thus has the potential to regulate actin filament dynamics and organization in cells via F-actin-stabilizing and -bundling activities, in addition to its ability to dephosphorylate cofilin.     

Intraoral extraction of an ectopic mandibular third molar detected in the subcondylar region without a pathological cause: A case report and literature review

Purpose: To present a case report on the presence of an ectopic mandibular third molar (EMTM), the surgical treatment, and outcome.

Case report: A 63-year-old woman presented with right preauricular facial swelling, limited jaw function, and pain. Radiographic assessment demonstrated an EMTM positioned in the superoposterior aspect of the ramus. Radiographically, there was a bony tunnel extending from the third molar to distal of the second molar. The patient was treated by an intraoral approach on the medial aspect of the ramus for removal of the ectopic third molar, as well as the tissue in the bony tunnel.

Results: The patient healed uneventfully. The soft tissue in the bony canal was granulation tissue, and nerve function was preserved. A literature search of EMTMs was conducted identifying 17 reported cases.

Conclusion: Three-dimensional imaging in the management of EMTM can be beneficial in identifying position of the tooth, associated pathology, and identifying the position of neurovascular structures to aid in removal of the ectopic tooth.     

ASXL2 mutations are frequently found in pediatric AML patients with t(8;21)/ RUNX1‐RUNX1T1 and associated with a better prognosis

ASXL2 is an epigenetic regulator involved in polycomb repressive complex regulation or recruitment. Clinical features of pediatric acute myeloid leukemia (AML) patients with ASXL2 mutations remain unclear. Thus, we investigated frequencies of ASXL1 and ASXL2 mutations, clinical features of patients with these mutations, correlations of these mutations with other genetic alterations including BCOR/BCORL1 and cohesin complex component genes, and prognostic impact of these mutations in 369 pediatric patients with de novo AML (0–17 years). We identified 9 (2.4%) ASXL1 and 17 (4.6%) ASXL2 mutations in 25 patients. These mutations were more common in patients with t(8;21)(q22;q22)/RUNX1‐RUNX1T1 (ASXL1, 6/9, 67%, P = 0.02; ASXL2, 10/17, 59%, P = 0.01). Among these 25 patients, 4 (27%) of 15 patients with t(8;21) and 6 (60%) of 10 patients without t(8;21) relapsed. However, most patients with relapse were rescued using stem cell transplantation irrespective of t(8;21). The overall survival (OS) and event‐free survival (EFS) rates showed no differences among pediatric AML patients with t(8;21) and ASXL1 or ASXL2 mutations and ASXL wild‐type (5‐year OS, 75% vs. 100% vs. 91% and 5‐year EFS, 67% vs. 80% vs. 67%). In 106 patients with t(8;21) AML, the coexistence of mutations in tyrosine kinase pathways and chromatin modifiers and/or cohesin complex component genes had no effect on prognosis. These results suggest that ASXL1 and ASXL2 mutations play key roles as cooperating mutations that induce leukemogenesis, particularly in pediatric AML patients with t(8;21), and these mutations might be associated with a better prognosis than that reported previously.     

Clinical observation of tongue coating of perioperative patients: factors related to the number of bacteria on the tongue before and after surgery

Background

Increased amount of tongue coating has been reported to be associated with increased bacteria count in the saliva and aspiration pneumonia in elderly people. However, the implications of tongue coating for prevention of postoperative complications in patients undergoing major oncologic or cardiac surgery has not been well documented. The purpose of this study is to investigate the number of bacteria on the tongue before and after surgery and factors affecting it.

Methods

Fifty-four patients who underwent oncologic or cardiac surgery under general anesthesia at Nagasaki University Hospital were enrolled in the study. Various demographic, tumor-related, treatment-related factors, and the number of bacteria on the tongue and in the saliva were examined, and the relationship among them was analyzed by Mann-Whitney U test, Spearman rank correlation coefficient, or multiple regression.

Results

Before surgery, no significant factors were correlated with the number of bacteria on the tongue, and there were no relationship between bacteria count on the tongue and that in the saliva. On the next day after surgery, bacteria on the tongue increased, and sex, periodontal pocket depth, feeding condition, dental plaque, blood loss, and bacteria in the saliva were correlated with bacteria on the tongue by a univariate analysis. A multivariate analysis showed that feeding condition, and amount of dental plaque were correlated with the number of bacteria.

Conclusions

Increased number of bacteria on the tongue was associated with feeding condition and amount of dental plaque. Further studies are necessary to clarify the clinical significance of dental coating in perioperative oral management of patients undergoing oncologic or cardiac surgery.

     

The tumour shape of lung adenocarcinoma is related to the postoperative prognosis

We evaluated the tumour shape as a potential prognostic indicator in lung adenocarcinoma patients. Among 994 patients who underwent curative surgery, 78 cases of adenocarcinoma (N0M0) with tumours ≥ 31 mm in diameter were reviewed. The patients were divided into two groups based on the ratio between the longest and the smallest axis length. The patients who had tumours whose ratios were > 0.5 were defined as the globular shape group (GL) and the others, whose ratio was 0.5 or less, were defined as the ellipse shape group (EL). The 78 patients were divided into two subgroups (57 in the GL and 21 in the EL). The tumour shape was related to the prognosis, and the 5-year overall survival (OS) rate in the GL was 51.5%, and that in the EL was 85.5% (P = 0.018). The 5-year disease-free survival rate of the GL was 46.6% and that of the EL patients was 85.0% (P = 0.04). The multivariate analysis showed that the shape of the tumour and the presence of pleural invasion were the independent and significant factors predicting the OS (P = 0.04 and P < 0.01, respectively). In adenocarcinoma patients, the shape of the tumour is related to the postoperative survival.     

Disease-associated CIAS1 mutations induce monocyte death, revealing low-level mosaicism in mutation-negative cryopyrin-associated periodic syndrome patients

Cryopyrin-associated periodic syndrome (CAPS) is a spectrum of systemic autoinflammatory disorders in which the majority of patients have mutations in the cold-induced autoinflammatory syndrome (CIAS)1 gene. Despite having indistinguishable clinical features, some patients lack CIAS1 mutations by conventional nucleotide sequencing. We recently reported a CAPS patient with mosaicism of mutant CIAS1, and raised the possibility that CIAS1 mutations were overlooked in "mutation-negative" patients, due to a low frequency of mosaicism. To determine whether there were latent mutant cells in "mutation-negative" patients, we sought to identify mutation-associated biologic phenotypes of patients' monocytes. We found that lipopolysaccharide selectively induced necrosis-like cell death in monocytes bearing CIAS1 mutations. Monocyte death correlated with CIAS1 up-regulation, was dependent on cathepsin B, and was independent of caspase-1. Cell death was intrinsic to CIAS1-mutated monocytes, was not mediated by the inflammatory milieu, and was independent of disease severity or anti-IL-1 therapy. By collecting dying monocytes after lipopolysaccharide treatment, we succeeded in enriching CIAS1-mutant monocytes and identifying low-level CIAS1-mosaicism in 3 of 4 "mutation-negative" CAPS patients. Our findings reveal a novel effect of CIAS1 mutations in promoting necrosis-like cell death, and demonstrate that CIAS1 mosaicism plays an important role in mutation-negative CAPS patients.