Impact of beta-tricalcium phosphate on preventing tooth extraction-triggered bisphosphonate-related osteonecrosis of the jaw in rats.

Antiresorptive or antiangiogenic drugs can cause medication-related osteonecrosis of the jaw that is refractory. Bisphosphonate-related osteonecrosis of the jaw (BRONJ) may be caused by procedures such as tooth extraction damage the alveolar bone, release bisphosphonates (BPs) and impede healing. This study investigated strategies for BRONJ prevention and molecular mechanisms of its onset. We assessed the effectiveness of filling extraction sockets with beta-tricalcium phosphate (ß-TCP). Rats were administered zoledronic acid (ZA) 1.2 mg/kg once per week for 2 weeks, and a molar was extracted. They were randomly assigned to the ß-TCP group (bone defects filled with 0.01 g of ß-TCP) or control group. Tissue content measurements indicated 2.2 ng of ZA per socket in the ß-TCP group and 4.9 ng in the control group, confirming BP distribution and BP adsorption by ß-TCP in vivo. At 4 weeks after extraction, the ß-TCP group had normal mucosal coverage without inflammation. Moreover, at 8 weeks after extraction, enhanced bone healing, socket coverage, and new bone formation were observed in the ß-TCP group. Connective tissue in the extraction sockets suggested that local increases in BP concentrations may suppress the local autophagy mechanisms involved in BRONJ. Filling extraction sockets with ß-TCP may prevent BRONJ.

Extracellular Leakage Protein Patterns in Two Types of Cancer Cell Death: Necrosis and Apoptosis.

Dead cells release fragments of DNA, RNA, and proteins (including peptides) into the extracellular space. Two major forms of cell death during cancer development have been identified: necrosis and apoptosis. Our group investigated the mechanisms that regulate cell death during the treatment of mouse tumor FM3A cells with the anticancer drug floxuridine (FUdR). In the original strain F28-7, FUdR induced necrosis, whereas in the variant F28-7-A, it induced apoptosis. Here, we report that the extracellular leakage proteome (i.e., the secretome) is involved in these cell death phenomena. The secretome profile, which was analyzed via shotgun proteomic analysis, revealed that altered protein leakage was involved in signal transduction, transcription, RNA processing, translation, and cell death. Notably, the characteristic secretory proteins high mobility group box 1 and 2 were detected in the culture medium of both necrotic and apoptotic cells. Overall, these results indicate that unique cellular events mediated by secretory proteins may be involved in necrosis and apoptosis.

Effect of smoking status and programmed death-ligand 1 expression on the microenvironment and malignant transformation of oral leukoplakia: A retrospective cohort study.

Tobacco smoking is associated with an increased risk of oral leukoplakia and head and neck cancer. Although it has recently been reported that the establishment of an immunosuppressive microenvironment in oral potentially malignant disorders may lead to malignant transformation, it is unclear whether the microenvironments of oral potentially malignant disorders differ according to smoking status. We examined differences in programmed death-ligand 1 (PD-L1) expression and subepithelial CD163+ TAM and CD8+ cell/lymphocyte counts in the microenvironment of oral leukoplakia of smoking and non-smoking patients and investigated their associations with malignant transformation. Pathology reports and original biopsy request forms from 1995-2015 were retrospectively reviewed. Lesions clinically characterized as white plaques/lesions of the oral mucosa and pathologically diagnosed as oral epithelial dysplasia were included. Immunohistochemistry was performed to evaluate PD-L1 expression and subepithelial CD163+/CD8+ cell counts. The significance of prognostic factors in predicting malignant transformation was determined using Cox regression analysis. Statistical significance was defined as P<0.05. In total, 200 patients with oral leukoplakia were selected. The mean age at diagnosis was higher in non-smoking patients (n = 141; 66.9 years) than in smoking patients (n = 59; 60.5 years). The 5-year cumulative malignant transformation rate was higher in non-smoking patients than in smoking patients (9.3% vs. 3.0%, respectively). Oral leukoplakia was associated with significantly higher PD-L1 expression and increased numbers of subepithelial CD163+ cells in the non-smoking group compared with the smoking group. Non-smoking-related oral leukoplakia with positive PD-L1 expression was associated with a 6.97-fold (95% confidence interval: 2.14-22.7) increased risk of malignant transformation. The microenvironment of oral leukoplakia differed according to smoking status. A combination of smoking status and PD-L1 expression may predict malignant transformation in oral leukoplakia patients. This study highlights the importance of understanding the interaction between smoking and the microenvironment in oral leukoplakia.

Risk factors for post-extraction bleeding in patients with haemophilia: a retrospective cohort study.

Many guidelines and studies describe haemostatic management protocols for patients with haemophilia, but few have evaluated the risk factors for post-extraction bleeding. This retrospective cohort study was performed to investigate these risks among this group of patients. We used medical records to identify patients with haemophilia who underwent tooth extraction(s) between April 2006 and April 2019 in the Department of Oral and Maxillofacial Surgery at Nara Medical University Hospital, Nara, Japan, and conducted logistic regression analyses to identify risk or protective factors for post-extraction bleeding in procedures involving factor replacement therapy. Post-extraction bleeding was defined as bleeding that could not be stopped by biting down on gauze, and that required medical treatment between 30min and 14 days after the extraction. A total of 151 extractions (84 interventions) in 55 patients fulfilled the inclusion criteria (130 extractions (72 interventions) in 48 patients with haemophilia A, and 21 extractions (12 interventions) in seven patients with haemophilia B). Post-extraction bleeding was observed in nine patients (16.3%), 10 interventions (11.9%), and 12 extractions (7.9%). On average, it occurred six days after the intervention, and on the fifth postoperative day after extractions. Use of mouth splints significantly reduced the risk (odds ratio: 0.13; p=0.01) in patients on factor replacement therapy. We will conduct a prospective study to investigate the optimal type of splint and optimal splint-wearing period.

Intracellular microRNA expression patterns influence cell death fates for both necrosis and apoptosis.

MicroRNAs (miRNAs) are small noncoding RNA molecules that interact with target mRNAs at specific sites to induce cleavage of the mRNA or inhibit translation. Such miRNAs play a vital role in gene expression and in several other biological processes, including cell death. We have studied the mechanisms regulating cell death (necrosis in original F28-7 cells and apoptosis in their variant F28-7-A cells) in the mouse mammary tumor cell line FM3A using the anticancer agent floxuridine (FUdR). We previously reported that inhibition of heat-shock protein 90 by the specific inhibitor geldanamycin (GA) in F28-7 cells causes a shift from necrosis to apoptosis. In this study, we investigated the intracellular miRNA expression profiles of FUdR-treated F28-7 cells (necrotic condition), GA plus FUdR-treated F28-7 cells (apoptotic condition), and FUdR-treated F28-7-A cells (apoptotic condition) through miRNA microarray analysis. In addition, we knocked down Dicer, a key molecule for the expression of mature miRNAs, in F28-7 cells to examine whether it modulates FUdR-induced cell death. Our analysis revealed that the miRNA expression patterns differ significantly between these cell death conditions. Furthermore, we identified miRNA candidates that regulate cell death. Knockdown of Dicer in FUdR-treated necrosis-fated cells caused a partial shift from necrosis to apoptosis. These findings suggest that modulation of miRNA expression patterns influences the decision of cell death fate toward necrosis or apoptosis. Our findings may serve as a basis for further study of the functions of miRNAs in cell death mechanisms.

[Acute coronary syndrome due to coronary thrombus formed by severe coronary spasm: a case report].

A 47-year-old man was admitted to our hospital complaining of chest pain at rest in the early morning. Electrocardiography showed ST segment elevation in leads II, III and aVF. Emergency coronary angiography revealed total occlusion of the right coronary artery at the proximal portion. Intracoronary administration of isosorbide dinitrate successfully recanalized the right coronary artery. However, there was a thrombus image at the culprit lesion. Intracoronary administration of urokinase caused the residual thrombus to disappear completely. Follow-up coronary angiography at 1 week and 3 months revealed no organic stenotic lesion. Intravascular ultrasound showed only a little plaque without signs of ruptured plaque in the right coronary artery. Provocation coronary angiography revealed remarkable spasm causing total occlusion at the proximal portion of the right coronary artery. This case suggests that only severe coronary spasm without plaque rupture could form a thrombus causing acute coronary syndrome.

Cervical and intracranial atherosclerosis and silent brain infarction in Japanese patients with coronary artery disease.

PURPOSE: To investigate the prevalence of cervical and intracranial atherosclerosis and silent brain infarction in patients with coronary artery disease (CAD). METHODS: Cervical and intracranial atherosclerotic lesions on magnetic resonance angiography (MRA) and silent brain infarctions on magnetic resonance imaging (MRI) were investigated in comparison with the findings of coronary angiography in 133 consecutive patients with CAD. RESULTS: The mean severity scores of cervical and intracranial MRA lesions were significantly higher in the three-vessel CAD (0.40 and 0.53, respectively) than in the zero-vessel CAD group (0.04 and 0.11). The mean scores of the maximal size and multiplicity of MRI lesion were also significantly greater in the two-vessel (1.00 and 1.44) and three-vessel CAD (0.94 and 1.26) than in the zero-vessel CAD group (0.27 and 0.50). The incidence of MRA lesion was markedly higher in patients with brain MRI lesion than in those without (51.1 vs. 6.5%). CONCLUSIONS: Serious coronary artery lesions were commonly accompanied by latent atherosclerotic lesions in the cervical and intracranial arteries besides silent brain infarction in patients with CAD.