Irrigation with reduced sodium hypochlorite solution concentration using laser-induced cavitation is effective and safe in rat intraradicular biofilm model.

This study aimed to investigate the optimal sodium hypochlorite solution (NaOCl) concentration to effectively remove the root canal biofilm without stimulating periradicular inflammation using coronal laser-activated irrigation (CLAI). To compare the efficacy of different NaOCl concentrations combined with CLAI in removing the biofilm, an in vivo intraradicular biofilm rat model was used. Root canals were irrigated using an Er:YAG laser with either 5% or 0.5% NaOCl. Biofilm removal efficacy of CLAI was compared to that of conventional needle irrigation using scanning electron microscopy (SEM) and quantitative polymerase chain reaction (qPCR). Histological observation of CLAI-associated periradicular inflammation was also conducted. In both the 5% and 0.5% CLAI groups, SEM observation showed the opening of the dentin tubules and biofilm removal. qPCR analysis indicated that the residual bacteria counts after cleaning were significantly lower in the 5% and 0.5% CLAI groups than in the conventional needle irrigation and positive control groups (Tukey test, p < 0.05), and no significant difference was observed between the 5% and 0.5% CLAI groups (p > 0.05). Periapical inflammation in the 5% CLAI group revealed the most severe, including significant neutrophilic and lymphocytic infiltration with abscess formation, while only mild vasodilation was observed in the 0.5% CLAI group. CLAI can remove the biofilm independently of chemical action, which avoids the risks associated with high NaOCl concentrations. Therefore, this root canal irrigation technique ensures safety and effectiveness, promising to contribute to new treatment strategies intended to remove intraradicular biofilm.

Salivary leukocyte esterase activity by SillHa is a risk indicator of periodontal disease.

BACKGROUND: There is increasing evidence that diagnostic salivary tests measuring inflammatory biomarkers are being developed to assess inflammatory status for early detection, prevention, and progression of periodontal disease. Therefore, the aim of the present study was to investigate and identify the salivary biomarker that can predict the inflammatory status of periodontal disease. METHODS: A total of 36 patients (28 women and 8 men) with an average age of 57 years were investigated. Unstimulated saliva was collected from the recruited subjects and analyzed using SillHa, a saliva-testing device that measures bacteria count, saliva buffer capacity, acidity, leukocyte esterase, protein, and ammonia. Periodontal parameters were then obtained by clinical examination and initial periodontal therapy was performed. Data obtained with SillHa were compared with clinical periodontal parameters at baseline, re-examination (three months from baseline), and final examination (six months from re-examination). RESULTS: Leukocyte esterase activity in saliva measured by SillHa; BOP and PCR measured by clinical examination showed a significant difference between baseline and final examination and between re-examination and final examination. Patients in the lower median group (group 1) had a significant difference in leukocyte esterase activity between baseline and final examination and re-examination and final examination. In addition, patients in Group 1 had significantly lower BOP between baseline and final examination. While patients in the higher median group (group 2) showed a modest decrease in leukocyte esterase activity, which was significant only between baseline and final examination, no significant changes were observed concerning BOP. Furthermore, the associated systemic disease was observed in 30% and 81.2% of group 1 and 2 patients, respectively. CONCLUSION: The results suggest that leukocyte esterase activity in saliva measured by SillHa could serve as a reliable diagnostic marker for monitoring inflammatory status in periodontal disease.

A case series describing the risk of periodontal disease in Marfan syndrome patients harboring a possible aortic aneurysm or dissection.

BACKGROUND: Marfan syndrome (MFS) is a systemic disorder of connective tissues caused by insufficient elastic fiber formation that leads to structural weakness and results in various tissue disorders, including cardiovascular and periodontal disease. Notably however, the risk of periodontal disease in MFS patients affected by an aortic aneurysm or dissection has not yet been clarified. METHODS: We investigated the periodontal condition in the following three groups: MFS patients diagnosed with an aortic aneurysm or dissection with a planned aortic surgery (MFS surgery), MFS patients who had already undergone aortic surgery (MFS post-surgery) and healthy control patients (Healthy). The periodontal condition of all of these patients was evaluated at their first visit, reassessed again at two-month after the first visit, and evaluated again at a six-month follow-up after the reassessment. RESULTS: A total of 14 participants, 3 MFS surgery patients, 4 MFS post-surgery patients and 7 healthy control volunteers were examined. Saliva examinations revealed no significant differences between any of the groups at the first visit, reassessment, or follow-up. Interestingly, the MFS surgery cases showed a higher BOP and PISA at the first visit and follow-up compared with the other groups. In contrast, the MFS surgery patients showed an improvement in their LVDd and EF values, both markers of cardiac function, at the reassessment and follow-up compared with the first visit. CONCLUSIONS: MFS associated with an aortic aneurysm or dissection leads to a higher risk of periodontal disease, indicating the need for more frequent oral hygiene maintenance in these patients. In addition, MFS patients who undergo frequent professional cleaning of their teeth show a lower onset of cardiovascular disease, suggesting that professional oral hygiene in these cases contributes to a healthier condition.

Er:YAG laser-induced cavitation can activate irrigation for the removal of intraradicular biofilm.

We investigated the biofilm removal effects of laser activated irrigation (LAI) using a pig model, focusing on the impact of the fiber tip position, and used a high-speed camera to observe the occurrence and positioning of the cavitation associated with laser irradiation. A total of 16 roots of deciduous mandibular second premolars from 4 pigs were used. After a pulpectomy, the canals were left open for 2 weeks and sealed for 4 weeks to induce intraradicular biofilm. Root canal irrigation was then performed with Er:YAG laser activation. The fiber tip was inserted at two different positions, i.e., into the root canal in the intracanal LAI group and into the pulp chamber in the coronal LAI group. Intracanal needle irrigation with saline or 5% NaOCl was utilized in the positive control and conventional needle irrigation (CNI) groups. SEM and qPCR were carried out to evaluate treatment efficacy. Statistical analysis was performed using ANOVA and a Tukey-Kramer post-hoc test for qPCR and with a Steel-Dwass test to compare the SEM scores, with α = 0.05. A high-speed camera was used to observe the generation of cavitation bubbles and the movement of the induced bubbles after laser irradiation. The intracanal and coronal LAI groups showed significantly lower amounts of bacteria than either the positive control or CNI groups. There was no significant difference found between the intracanal and coronal LAI groups. SEM images revealed opened dentinal tubules with the destruction of biofilm in both LAI groups. High-speed camera images demonstrated cavitation bubble production inside the root canal after a single pulse irradiation pulse. The generated bubbles moved throughout the entire internal multi-rooted tooth space. Coronal LAI can generate cavitation in the root canal with a simply placed fiber inside the pulp chamber, leading to effective biofilm removal. This method could thus contribute to the future development of endodontic treatments for refractory apical periodontitis caused by intraradicular biofilm.

Correction of large jawbone defect in the mouse using immature osteoblast-like cells and a 3D polylactic acid scaffold.

Bone tissue engineering has been developed using a combination of mesenchymal stem cells (MSCs) and calcium phosphate-based scaffolds. However, these complexes cannot regenerate large jawbone defects. To overcome this limitation of MSCs and ceramic scaffolds, a novel bone regeneration technology must be developed using cells possessing high bone forming ability and a scaffold that provides space for vertical bone augmentation. To approach this problem in our study, we developed alveolar bone-derived immature osteoblast-like cells (HAOBs), which have the bone regenerative capacity to correct a large bone defect when used as a grafting material in combination with polylactic acid fibers that organize the 3D structure and increase the strength of the scaffold material (3DPL). HAOB-3DPL constructs could not regenerate bone via xenogeneic transplantation in a micromini pig alveolar bone defect model. However, the autogenic transplantation of mouse calvaria-derived immature osteoblast-like cells (MCOBs) isolated using the identical protocol for HAOBs and mixed with 3DPL scaffolds successfully regenerated the bone in a large jawbone defect mouse model, compared to the 3DPL scaffold alone. Nanoindentation analysis indicated that the regenerated bone had a similar micromechanical strength to native bone. In addition, this MCOB-3DPL regenerated bone possesses osseointegration ability wherein a direct structural connection is established with the titanium implant surface. Hence, a complex formed between a 3DPL scaffold and immature osteoblast-like cells such as MCOBs represents a novel bone tissue engineering approach that enables the formation of vertical bone with the micromechanical properties required to treat large bone defects.

Clinical Applications of Cell-Scaffold Constructs for Bone Regeneration Therapy.

Bone tissue engineering (BTE) is a process of combining live osteoblast progenitors with a biocompatible scaffold to produce a biological substitute that can integrate into host bone tissue and recover its function. Mesenchymal stem cells (MSCs) are the most researched post-natal stem cells because they have self-renewal properties and a multi-differentiation capacity that can give rise to various cell lineages, including osteoblasts. BTE technology utilizes a combination of MSCs and biodegradable scaffold material, which provides a suitable environment for functional bone recovery and has been developed as a therapeutic approach to bone regeneration. Although prior clinical trials of BTE approaches have shown promising results, the regeneration of large bone defects is still an unmet medical need in patients that have suffered a significant loss of bone function. In this present review, we discuss the osteogenic potential of MSCs in bone tissue engineering and propose the use of immature osteoblasts, which can differentiate into osteoblasts upon transplantation, as an alternative cell source for regeneration in large bone defects.

Corrigendum to "Generation of cardiomyocytes by atrioventricular node cells in long-term cultures" [Biochem. Biophys. Rep. 26 (2021) 101018].

[This corrects the article DOI: 10.1016/j.bbrep.2021.101018.].

Generation of cardiomyocytes by atrioventricular node cells in long-term cultures.

Turnover of cardiac pacemaker cells may occur during the lifetime of the body, and we recently raised the hypothesis that specialized cardiac cells have in common the potential to generate cardiomyocytes from fibroblasts. To examine this hypothesis, we analyzed the ability of atrioventricular node cells (AVNCs) to generate functional cardiomyocytes in long-term culture. AVNCs were isolated from adult guinea pig hearts and cultured for up to three weeks. Under phase-contrast microscopic observation over time, it was found that within a week, a number of fibroblasts gathered around the AVNCs and formed cell clusters, and thereafter the cell clusters started to beat spontaneously. The nascent cell clusters expanded their area gradually by three weeks in culture and expressed specific cardiac genes and proteins. Maturation of newly formed cardiomyocytes seems to be slow in cultures of AVNCs compared with those of sinoatrial node cells. Stimulation of muscarinic receptors with acetylcholine induced a beating rate decrease which was blocked by atropine, and activation of adenylate cyclase activity with forskolin increased the beat rate, while stimulation of beta adrenoceptors by isoproterenol had no effect. These results indicate that AVNCs form a cluster of cells with properties of functional cardiomyocytes and provide evidence to support the hypothesis.

Inhibition of the CXCL9-CXCR3 axis suppresses the progression of experimental apical periodontitis by blocking macrophage migration and activation.

Apical periodontitis (AP) is an acute or chronic inflammatory disease caused by complex interactions between infected root canal and host immune system. It results in the induction of inflammatory mediators such as chemokines and cytokines leading to periapical tissue destruction. To understand the molecular pathogenesis of AP, we have investigated inflammatory-related genes that regulate AP development. We found here that macrophage-derived CXCL9, which acts through CXCR3, is recruited by progressed AP. The inhibition of CXCL9 by a CXCR3 antagonist reduced the lesion size in a mouse AP model with decreasing IL-1ß, IL-6 and TNFα expression. The treatment of peritoneal macrophages with CXCL9 and LPS induced the transmigration and upregulation of osteoclastogenic cytokines such as IL-1ß, IL-6 and matrix metalloprotease 2, a marker of activated macrophages. This suggests that the CXCL9-CXCR3 axis plays a crucial role in the development of AP, mediated by the migration and activation of macrophages for periapical tissue destruction. Our data thus show that CXCL9 regulates the functions of macrophages which contribute to AP pathogenesis, and that blocking CXCL9 suppresses AP progression. Knowledge of the principal factors involved in the progression of AP, and the identification of related inflammatory markers, may help to establish new therapeutic strategies.

Cardiac Pacemaker Cells Generate Cardiomyocytes from Fibroblasts in Long-Term Cultures.

Because cardiomyocyte generation is limited, the turnover of cardiomyocytes in adult heart tissues is much debated. We report here that cardiac pacemaker cells can generate cardiomyocytes from fibroblasts in vitro. Sinoatrial node cells (SANCs) were isolated from adult guinea pig hearts and were cultured at relatively low cell densities. Within a week, a number of fibroblast-like cells were observed to gather around SANCs, and these formed spontaneously beating clusters with cardiomyocyte structures. The clusters expressed genes and proteins that are characteristic of atrial cardiomyocytes. Pharmacological blocking of pacemaker currents inhibited generation of action potentials, and the spontaneous beating were ceased by physically destroying a few central cells. Inhibition of beating during culture also hampered the cluster formation. Moreover, purified guinea pig cardiac fibroblasts (GCFs) expressed cardiac-specific proteins in co-culture with SANCs or in SANC-preconditioned culture medium under electrical stimulation. These results indicate that SANCs can generate cardiomyocytes from cardiac fibroblasts through the influence of humoral factor(s) and electrophysiological activities followed by intracellular Ca2+ oscillations. This potential of SANCs to generate cardiomyocytes indicates a novel mechanism by which cardiomyocytes turns over in the vicinity of pacemaker cells and could be exploited in the development of strategies for cardiac regenerative therapy in adult hearts.

The influence of dietary peptide inhibitors of angiotensin-converting enzyme on the hypotensive effects of enalapril.

BACKGROUND: Enalapril is an antihypertensive medicine that inhibits angiotensin I-converting enzyme (ACE). The present study investigated interactions between enalapril and a fermented milk product (FMP) containing the ACE-inhibitory peptides, Val-Pro-Pro (VPP) and Ile-Pro-Pro (IPP). METHODS: Single-dose and long-term (6-week) in vivo studies were used to investigate the effects of enalapril and FMP on blood pressure in spontaneously hypertensive rats. RESULTS: Single-dose oral administration of concomitant enalapril and FMP (VPP, IPP: 3.5 mg/kg) produced a lower antihypertensive effect than enalapril monotherapy. However, this effect was not observed in animals administered a lower dose of FMP (VPP, IPP: 1.75 mg/kg) along with enalapril. In rats administered enalapril concomitantly with a fish protein product (FPP) containing a different ACE inhibitory peptide (Leu-Lys-Pro-Asn-Met), significant attenuation of the antihypertensive effect was also observed 1 and 2 h after administration, as compared to enalapril monotherapy. During a 6-week oral administration study, the enalapril monotherapy group showed significant antihypertensive effects compared to those observed in the controls on day 28. Oral administration of enalapril and FMP, with a 1-h interval between doses, resulted in significant antihypertensive effects on day 35, indicating a delayed onset in comparison to enalapril monotherapy. In rats receiving enalapril monotherapy for 28 days, followed by 14 days of concomitant FMP, significant antihypertensive effects were observed after day 35, and these did not differ significantly from the effects observed during enalapril monotherapy. CONCLUSIONS: The present findings suggested that long-term concomitant intake of FMP and enalapril could influence the antihypertensive effects of this drug.

Enhancement or Suppression of ACE Inhibitory Activity by a Mixture of Tea and Foods for Specified Health Uses (FOSHU) That Are Marketed as "Support for Normal Blood Pressure".

The ACE inhibitory activities of mixtures of FOSHUs (Healthya, Goma-Mugicha, Lapis Support and Ameal) were examined in order to identify any antihypertensive interactions. Among combinations of Healthya with other samples that contain active peptides, only that with Ameal was found to have no inhibitory activity. Enhanced activity was observed in 2 other mixtures. The activity of a mixture of tea polyphenols and the whey component extracted from an Ameal solution was significantly decreased, thus demonstrating that whey protein lowered the ACE inhibitory activity of Healthya. Although oral administration of tea polyphenols alone significantly decreased SBP in SHR at 2 and 4 hr, combined administration with Ameal failed to decrease SBP at the same time points. In conclusion, the simultaneous intake of tea and FOSHUs that contain active peptides might affect daily self-antihypertensive management via enhancement or suppression of ACE inhibitory activity.

Captopril enhances cardiac vagal but not sympathetic neurotransmission in pithed rats.

The effect of captopril on neurally evoked bradycardia and tachycardia was investigated in pithed rats. Captopril enhanced the vagal nerve stimulation-evoked bradycardia. Angiotensin I reduced the vagal bradycardia, which was reversed by subsequent administration of captopril. Bradykinin did not affect the neurally evoked bradycardia. Captopril and angiotensin I affected neither the exogenous acetylcholine-evoked bradycardia nor the sympathetic nerve stimulation-evoked tachycardia. These results suggest that the interruption of angiotensin II formation by captopril causes less presynaptic inhibition of acetylcholine release via angiotensin II receptors without affecting cardiac sympathetic neurotransmission.