Idiopathic thrombocytopenic purpura (ITP) is a blood disease in which the platelet count falls below 100,000/μl. When pregnancy is complicated by ITP, the reduced number of platelets increases the risk of bleeding during delivery. Here we report a successful tooth extraction procedure performed for a pregnant ITP patient.The patient was a 34-year-old woman. The initial dental examination was in June 20XX at this clinic, where she was referred for treatment of tooth mobility.Her medical history included the ITP diagnosis at age 33. Radiographic findings were a fracture line in the root of the left maxillary second premolar with root resorption and alveolar bone resorption. From these findings, conservation was judged to be difficult and extraction was indicated. The patient had maintained a platelet count of 60,000/μl, and the absence of a coagulation disorder was confirmed, so the extraction proceeded. The left maxillary second premolar was extracted. An absorbable hemostat was placed in the socket, which was then sutured. By the next day, bleeding had stopped, and the patient made a satisfactory recovery.
Oral streptococci, including cariogenic bacterium Streptococcus mutans, comprise a large percentage of human supragingival plaque, which contacts both tooth surfaces and gingiva. Eukaryotic cells are able to take up macromolecules and particles, including bacteria, by endocytosis. Increasing evidence indicates endocytosis may be used as an entry process by bacteria. We hypothesized that some endocytosed bacteria might survive and obtain nutrients, such as amino acids, until they are killed. To verify this hypothesis, we focused on bacterial utilization of branched-chain amino acids (BCAAs; isoleucine, leucine and valine) in host cells. A branched-chain aminotransferase, IlvE (EC 2.6.1.42), has been suggested to play an important role in internal synthesis of BCAAs in S. mutans UA159. Therefore, we constructed an ilvE-deficient S. mutans 109c strain and confirmed that it had similar growth behavior as reported previously. 14C radioactive leucine uptake assays showed that ilvE-deficient S. mutans took up more leucine both inside and outside of host cells. We further clarified that a relative decrease of BCAAs in host cells caused enhanced endocytic and autophagic activity. In conclusion, S. mutans is endocytosed by host cells and may survive and obtain nutrients, such as BCAAs, inside the cells, which might affect cellular functions of host cells.
Food allergy is a life-threatening response to specific foods, and microbiota imbalance (dysbiosis) in gut is considered a cause of this disease. Meanwhile, the host immune response also plays an important role in the disease. Notably, interleukin 33 (IL-33) released from damaged or necrotic intestinal epithelial cells facilitates IL-2-producing CD4 helper T (Th2) responses. However, causal relationships between the gut and oral dysbiosis and food allergy remain unknown. In this study, we analyzed effects of gut and oral dysbiosis on development of food allergy. A murine model of food allergy was established via ovalbumin (OVA) injection in BALB/c mice. Viable fecal bacteria were identified using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). il33 expression in colon-26 mouse colon cells stimulated by isolated fecal bacteria was quantified by real-time PCR. Intestinal T cells from the mice were analyzed by flow cytometry. Salivary IgA levels were quantified by enzyme-linked immunosorbent assay (ELISA), and IgA-bound oral bacteria were detected by flow cytometry. Among fecal bacteria, the abundance of Citrobacter sp. increased in the feces of allergic mice and induced il33 expression in colon-26 cells. Orally administered Citrobacter koseri JCM1658 exacerbated systemic allergic symptoms and reduced intestinal Th17 cells. Salivary IgA and IgA-bound oral bacteria increased in the allergic mice. Based on the results described above, food allergy induced both gut and oral dysbiosis. Citrobacter sp. aggravated allergy symptoms by inducing IL-33 release from intestinal epithelial cells.
Myelodysplastic syndrome （MDS）, an acquired hematopoietic disorder that is commonly referred to as preleukemia, often manifests as refractory anemia. Patients with this condition undergoing dental procedures may exhibit a bleeding tendency because of pancytopenia, infection, etc., necessitating a cautious approach. A man in his 70s presenting with upper left buccal swelling was referred to our department for detailed examination and treatment.Based on X-ray and CT findings （diagnostic imaging）, the patient was diagnosed as having left upper phlegmon, caused by a periapical lesion of the maximally left second molar. Further, the results of several laboratory examinations led to the suspicion of a systemic disease, and so the patient was referred to the hematology department; a bone marrow puncture was performed and the patient was diagnosed as having MDS. Thirteen teeth extractions and two pulp extractions were performed under local anesthesia, under cover of platelet transfusions during hospitalization.The patient, who was diagnosed with MDS due to an odontogenic infection, received successful dental treatment in cooperation with the hematology department, and good results were obtained.
The global outbreak of coronavirus disease 2019 (COVID-19) has raised concerns about the risk of airborne infection during dental treatment. Aerosol-generating dental procedures (AGDP) produce droplets and aerosols, but the details of the risks of COVID-19 transmission in AGDP are not well-understood. By discriminating between droplets and aerosols, we devised a method to measure particle size using laser diffraction analysis and evaluated aerosols generated from dental devices for providing a basis for proper infection control procedures. The droplets and aerosols generated from dental devices were characterized by multimodal properties and a wide range of droplet sizes, with the majority of droplets larger than 50 μm. AGDP emitted few aerosols smaller than 5 μm, which are of concern for pulmonary infections due to airborne transmission. In addition, the use of extraoral suction was found to prevent the spread of aerosols from high-speed dental engines. This study suggests that the risk of aerosol infections is considerably limited in regular dental practice and that current standard precautions, such as mainly focusing on protection against droplet and contact infections, are sufficient. While several cases of airborne transmission of COVID-19 in general clinics and emergency hospitals have been reported, cluster outbreaks in dental clinics have not yet been reported, which may indicate that AGDP does not pose a significant threat in contributing to the spread of SARS-CoV-2.
Melatonin, a sleep hormone derived from the pineal gland, has an anti-inflammatory effect on the immune system in addition to modulating the brain nervous system. Previous studies have shown that melatonin suppresses signaling pathways downstream of multiple pattern recognition receptors on the innate immune cells during pathogen infection, but the specific mechanism of suppression has not been well understood. Using an encephalomyocarditis virus (EMCV) infection model in macrophages, we investigated the effects of melatonin on the antiviral response in innate immunity and found that melatonin attenuated the uptake of viral particles into macrophages. Furthermore, melatonin suppressed cytoskeletal regulation by decreasing ATP production by mitochondria. Finally, in an in vivo infection experiment, we also found that melatonin administration partially exacerbated the infection in the mouse brain. These results suggest that melatonin may have an inhibitory effect on excessive inflammation by suppressing cytoskeletal regulation in the innate immune system, but also suggest that suppression of inflammation may lead to insufficient protection against EMCV infection in vivo.
Streptococcus oralis is a commensal oral bacterium that acts as an opportunistic pathogen, causing systemic diseases, such as infective endocarditis and aspiration pneumonia. However, the specific molecular mechanisms underlying its transition from commensal to pathogenic state remain unclear. In this study, to further elucidate the mechanisms underlying virulence expression, we identified and characterized the cell surface-associated ecto-5'-nucleotidase (Nt5e) in S. oralis. Biochemical analysis revealed Nt5e as a metal-dependent enzyme dephosphorylating ATP and producing adenosine, an immunosuppressive molecule that inhibits macrophage activation. Additionally, Nt5e was a critical regulator of innate immunity, particularly inflammasome activation, via environmental ATP metabolism. Analysis of an isogenic nt5e deletion mutant and its complemented strain revealed that cell surface-associated Nt5e played a crucial role in degrading extracellular ATP. The Nt5e-orchestrated mechanism possibly maintained the host-bacteria homeostasis under normal conditions, whereas its dysregulation facilitated pathogenicity in specific circumstances. Our study provides new insights into the mechanisms by which oral commensals modulate host immune responses and highlights Nt5e as a potential therapeutic target for S. oralis-associated systemic diseases.
Melatonin, a sleep hormone derived from the pineal gland, has an anti-inflammatory effect on the immune system in addition to modulating the brain nervous system. Previous studies have shown that melatonin suppresses signaling pathways downstream of multiple pattern recognition receptors on the innate immune cells during pathogen infection, but the specific mechanism of suppression has not been well understood. Using an encephalomyocarditis virus (EMCV) infection model in macrophages, we investigated the effects of melatonin on the antiviral response in innate immunity and found that melatonin attenuated the uptake of viral particles into macrophages. Furthermore, melatonin suppressed cytoskeletal regulation by decreasing ATP production by mitochondria. Finally, in an in vivo infection experiment, we also found that melatonin administration partially exacerbated the infection in the mouse brain. These results suggest that melatonin may have an inhibitory effect on excessive inflammation by suppressing cytoskeletal regulation in the innate immune system, but also suggest that suppression of inflammation may lead to insufficient protection against infection in vivo.
Distance recognition is the skill to estimate the distance to the target object. Such a distance recognition skill is one of the most important skills in everyday life. In various situations, such as walking, driving a car, communicating with people and so on, humans perceive the distance between the targets, and do the adequate action. Generally, the precision of distance recognition is different according to difference of the ambient surroundings, the objects, and especially the individual's ability. The distance recognition is achieved by capturing the target object visually and processing its visual information in their brains. Therefore, it is important to investigate how the difference of distance recognition skills affects the brain activity. In the paper, we measure the cerebral blood flow as a brain activity by using NIRS (Near-Infrared Spectroscopy) in the distance recognition.
