Outer membrane vesicles of Porphyromonas gingivalis: Novel communication tool and strategy.

Extracellular vesicles (EVs) have been recognized as a universal method of cellular communications and are reportedly produced in bacteria, archaea, and eukaryotes. Bacterial EVs are often called "Outer Membrane Vesicles" (OMVs) as they were the result of a controlled blebbing of the outer membrane of gram-negative bacteria such as Porphyromonas gingivalis (P. gingivalis). Bacterial EVs are natural messengers, implicated in intra- and inter-species cell-to-cell communication among microorganism populations present in microbiota. Bacteria can incorporate their pathogens into OMVs; the content of OMVs differs, depending on the type of bacteria. The production of distinct types of OMVs can be mediated by different factors and routes. A recent study highlighted OMVs ability to carry crucial molecules implicated in immune modulation, and, nowadays, they are considered as a way to communicate and transfer messages from the bacteria to the host and vice versa. This review article focuses on the current understanding of OMVs produced from major oral bacteria, P. gingivalis: generation, characteristics, and contents as well as the involvement in signal transduction of host cells and systemic diseases. Our recent study regarding the action of P. gingivalis OMVs in the living body is also summarized.

What impact does postgraduate clinical training have on empathy among Japanese trainee dentists?

BACKGROUND: Enhancing empathy in healthcare education is a critical component in the development of a relationship between healthcare professionals and patients that would ensure better patient care; improved patient satisfaction, adherence to treatment, patients' medication self-efficacy, improved treatment outcomes, and reduced patient anxiety. Unfortunately, however, the decline of empathy among students has been frequently reported. It is especially common when the curriculum transitions to a clinical setting. However, some studies have questioned the significance and frequency of this decline. Thus, the purpose of this study was to determine the impact of postgraduate clinical training on dental trainees' empathy from cognitive, behavioral, and patients' perspective. METHODS: This study included 64 trainee dentists at Okayama University Hospital and 13 simulated patients (SPs). The trainee dentists carried out initial medical interviews with SPs twice, at the beginning and the end of their clinical training. The trainees completed the Japanese version of the Jefferson Scale of Empathy for health professionals just before each medical interview. The SPs evaluated the trainees' communication using an assessment questionnaire immediately after the medical interviews. The videotaped dialogue from the medical interviews was analyzed using the Roter Interaction Analysis System. RESULTS: No significant difference was found in the self-reported empathy score of trainees at the beginning and the end of the clinical training (107.73 [range, 85-134] vs. 108.34 [range, 69-138]; p = 0.643). Considering the results according to gender, male scored 104.06 (range, 88-118) vs. 101.06 (range, 71-122; p = 0.283) and female 109.17 (range, 85-134) vs. 111.20 (range, 69-138; p = 0.170). Similarly, there was no difference in the SPs' evaluation of trainees' communication (10.73 vs. 10.38, p = 0.434). Communication behavior in the emotional responsiveness category for trainees in the beginning was significantly higher than that at the end (2.47 vs. 1.14, p = 0.000). CONCLUSIONS: Overall, a one-year postgraduate dental training program neither reduced nor increased trainee dentists' empathy levels. Providing regular education support in this area may help trainees foster their empathy.

Outer membrane vesicles derived from Porphyromonas gingivalis induced cell death with disruption of tight junctions in human lung epithelial cells.

OBJECTIVE: Porphyromonas gingivalis (P. gingivalis) is a major bacterium responsible for the progression of periodontitis. P. gingivalis produces small vesicles called outer membrane vesicles (OMVs) containing virulence factors. Increasing evidence suggests a close relationship between periodontitis and respiratory system diseases, such as aspiration pneumonia. However, little is known about whether P. gingivalis OMVs give rise to the impediment of lung epithelial cells. We investigated the effect of the OMVs on cell viability and tight junctions of lung epithelial cells. DESIGN: Human lung epithelial A549 cells were treated with P. gingivalis OMVs. Cell viability was evaluated, and cell morphology was examined using scanning electron and phase contrast microscopies. To detect apoptosis induced by P. gingivalis OMVs, activation of caspase-3 and poly ADP-ribose polymerase (PARP) cleavage was examined by using Western blotting. Immunocytochemistry was performed to stain tight junction proteins. RESULTS: P. gingivalis OMVs decreased cell viability in A549 cells in a dose- and time-dependent manner. Microscopic analysis revealed that the OMVs induced morphological changes leading to irregular cell membrane structures. The OMVs caused cell shrinkage, membrane blebbing, and cytoplasmic expulsion in a dose-dependent manner. Western blot analysis showed the OMVs induced caspase-3 activation and PARP cleavage. Treatment with the OMVs disrupted the intact distributions of tight junction proteins. CONCLUSIONS: These results indicate that P. gingivalis OMVs induced cell death by destroying the barrier system in lung epithelial cells. Our present study raises the possibility that P. gingivalis OMVs is an important factor in the engagement of periodontitis with respiratory system diseases.

Relationship of trainee dentists' self-reported empathy and communication behaviors with simulated patients' assessment in medical interviews.

OBJECTIVES: We aimed to clarify the communication behaviors between trainee dentists and simulated patients (SPs), to examine how the level of trainee dentists' self-reported empathy influences assessment by SPs in medical interviews. MATERIALS AND METHODS: The study involved 100 trainee dentists at Okayama University Hospital and eight SPs. The trainee dentists conducted initial interviews with the SPs after completing the Japanese version of the Jefferson Scale of Empathy (JSE). All interviews were recorded and analyzed using the Roter Interaction Analysis System (RIAS). The SPs assessed the trainees' communication immediately after each interview. The trainee dentists were classified into two groups (more positive and less positive) according to SP assessment scores. RESULTS: Compared with less-positive trainees, the more-positive trainees scored higher in the RIAS category of emotional expression and lower in the medical data gathering category. There was no difference in dental data gathering between the two groups. SP ratings for more-positive trainees were higher for use of positive talk and emotional expression and lower for giving medical information and dental information. Trainees with more positive ratings from SPs had significantly higher JSE total scores. CONCLUSION: The results of this study suggest that responding to the emotions of patients is an important behavior in dentist-patient communication, according to SPs' positive assessment in medical interviews. Further, SPs' assessment of trainees' communication was related to trainees' self-reported empathy, which indicates that an empathic attitude among dentists is a significant determinant of patient satisfaction.

Morphological and Functional Analyses of the Tight Junction in the Palatal Epithelium of Mouse.

Tight junction (TJ) is one of the cell-cell junctions and known to have the barrier and fence functions between adjacent cells in both simple and stratified epithelia. We examined the distribution pattern, constitutive proteins, and permeability of TJ in the stratified squamous epithelium of the palatal mucosa of mice. Ultrastructural observations based on the ultrathin section and freeze-fracture methods revealed that poorly developed TJs are located at the upper layer of the stratum granulosum. The positive immunofluorescence of occludin (OCD), claudin (CLD)-1 and -4 were localized among the upper layer of the stratum granulosum showing a dot-like distribution pattern. And CLD-1 and -4 were localized among the stratum spinosum and the lower part of stratum granulosum additionally showed a positive reaction along the cell profiles. Western blotting of TJ constitutive proteins showed OCD, CLD-1, -2, -4, and -5 bands. The permeability test using biotin as a tracer revealed both the areas where biotin passed through beyond OCD positive points and the areas where biotin stopped at OCD positive points. These results show that poor TJs localize at the upper layer of the stratum granulosum of the palatal epithelium, and the TJs are leaky and include at least CLD-1 and -4.

Determination of cell fate in skeletal muscle following BMP gene transfer by in vivo electroporation.

We previously developed a novel method for gene transfer, which combined a non-viral gene expression vector with transcutaneous in vivo electroporation. We applied this method to transfer the bone morphogenetic protein (BMP) gene and induce ectopic bone formation in rat skeletal muscles. At present, it remains unclear which types of cells can differentiate into osteogenic cells after BMP gene transfer by in vivo electroporation. Two types of stem cells in skeletal muscle can differentiate into osteogenic cells: muscle-derived stem cells, and bone marrow-derived stem cells in the blood. In the present study, we transferred the BMP gene into rat skeletal muscles. We then stained tissues for several muscle-derived stem cell markers (e.g., Pax7, M-cadherin), muscle regeneration-related markers (e.g., Myod1, myogenin), and an inflammatory cell marker (CD68) to follow cell differentiation over time. Our results indicate that, in the absence of BMP, the cell population undergoes muscle regeneration, whereas in its presence, it can differentiate into osteogenic cells. Commitment towards either muscle regeneration or induction of ectopic bone formation appears to occur five to seven days after BMP gene transfer.