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result(s) for
"Takahashi, Nobuhiro"
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Integrated hypothesis of dental caries and periodontal diseases
2020
This review considers an integrated hypothesis of dental caries and periodontal diseases that builds on theoretical ecological principles. The backbone of the hypothesis is based on the dynamic stability stage of the oral microbiota, at which intrinsic (mainly saliva and gingival crevicular fluid) and bacterial (mainly metabolic) resilience factors maintain ecological dynamic stability, compatible with clinical health. However, loss of intrinsic resilience factors and/or prolonged changes in the availability of microbial metabolic substrates may shift the ecological balance of the microbiota into either saccharolytic (acidogenic) or amino acid-degrading/proteolytic (alkalinogenic) stages, depending on the nature of the predominant substrates, leading to clinical diseases. Therefore, to maintain and restore the dynamic stability of the oral microbiota, it is necessary to control the drivers of disease, such as salivary flow and influx of bacterial nutrients into the oral cavity. Contrary to conventional wisdom, excessive intake of fermentable carbohydrates may contribute to inflammation in periodontal tissues resulting from hyperglycaemia. An integrated hypothesis emphasizes that both dental caries and periodontal diseases originate in the dynamic stability stage and emerge in response to nutritional imbalances in the microbiota. Periodontal diseases may belong to the sugar driven inflammatory diseases, similar to diabetes, obesity, and cardiovascular diseases.
Journal Article
Evaluation of the flagGraupelHail Product from Dual-Frequency Precipitation Radar Onboard the Global Precipitation Measurement Core Observatory Using Multi-Parameter Phased Array Weather Radar
2025
A major scientific challenge is understanding how precipitation systems will change under global warming. In particular, extreme precipitation events associated with hail and graupel are of significant concern. In this study, we evaluated the performance of the flagGraupelHail product from the Dual-Frequency Precipitation Radar (DPR) aboard the GPM Core Observatory using high-resolution dual-polarization observations from Multi-Parameter Phased Array Weather Radar (MP-PAWR). The analysis focused on a convective system that developed in a humid environment over the Tokyo region of Japan, providing a valuable assessment within a climatic regime that has been underrepresented in previous studies. A bias correction for MP-PAWR reflectivity, derived from XRAIN network comparisons, yielded good agreement with KuPR observations from the DPR. A new grid-matching method, suitable for comparing vertically varying hydrometeor particle types and available only for MP-PAWR, was also introduced. The comparison revealed that DPR flagGraupelHail detections generally corresponded to regions of graupel occurrence identified by the MP-PAWR GHratio, defined as the number of graupel/hail grids within a DPR observation volume, although DPR tended to detect fewer events. To improve detection performance, we introduced a new indicator, STH35-FH—the height difference between the 35 dBZ echo top and the 0 °C level—as a complementary parameter to the PTI value used to determine flagGraupelHail. Incorporating STH35-FH improved the consistency between DPR and MP-PAWR detections, reducing false positives and enhancing overall detection accuracy. These results demonstrate the value of combining ground-based and spaceborne radar observations to improve global precipitation retrievals, particularly in humid environments. This approach will contribute to more accurate global graupel/hail estimation by spaceborne precipitation radar and a better understanding of how global warming affects precipitation systems.
Journal Article
Metabolomic Studies of Oral Biofilm, Oral Cancer, and Beyond
2016
Oral diseases are known to be closely associated with oral biofilm metabolism, while cancer tissue is reported to possess specific metabolism such as the ‘Warburg effect’. Metabolomics might be a useful method for clarifying the whole metabolic systems that operate in oral biofilm and oral cancer, however, technical limitations have hampered such research. Fortunately, metabolomics techniques have developed rapidly in the past decade, which has helped to solve these difficulties. In vivo metabolomic analyses of the oral biofilm have produced various findings. Some of these findings agreed with the in vitro results obtained in conventional metabolic studies using representative oral bacteria, while others differed markedly from them. Metabolomic analyses of oral cancer tissue not only revealed differences between metabolomic profiles of cancer and normal tissue, but have also suggested a specific metabolic system operates in oral cancer tissue. Saliva contains a variety of metabolites, some of which might be associated with oral or systemic disease; therefore, metabolomics analysis of saliva could be useful for identifying disease-specific biomarkers. Metabolomic analyses of the oral biofilm, oral cancer, and saliva could contribute to the development of accurate diagnostic, techniques, safe and effective treatments, and preventive strategies for oral and systemic diseases.
Journal Article
Analysis of the Three-Dimensional Structure of the Misocyclones Generating Waterspouts Observed by Phased Array Weather Radar: Case Study on 15 May 2017 in Okinawa Prefecture, Japan
2022
Tornadoes are one of the most severe meteorological phenomena on the earth and their high winds cause serious damage to society. It is well known that vortices (mesocyclone or misocyclone, depending on their scale) in convective clouds contribute to tornadogenesis. High temporal resolution radar observations are necessary to elucidate the mechanism of tornadogenesis because convective clouds change drastically over time. This study focused on waterspouts that occurred on 15 May 2017 near Okinawa, Japan. Using Phased Array Weather Radar (PAWR) data, which provide three-dimensional data with high temporal resolution (every 30 s), radar reflectivity factors and Doppler velocity data were used to detect the three-dimensional structure of vortices. Using PAWR data, vorticities and diameters of these misocyclones were detected every 30 s and their potential vorticities, which are only possible because of the three-dimensional observation by PAWR, were calculated to understand the vortex generation and advection. The structures of two misocyclones (MC1 and MC2) were detected from Doppler velocity patterns. Combined with the radar reflectivity analysis, MC2 can be divided into two misocyclones (MC2a and MC2b). Potential vorticity of MC1 increased with time, probably because an outflow from the strong echo enhanced the lower horizontal shear. Potential vorticities in MC2a and MC2b were conserved in each period, with MC2b being nearly twice as large as MC2a.
Journal Article
Nitrite-producing oral microbiome in adults and children
by
Sato-Suzuki, Yuria
,
Wicaksono, Dimas Prasetianto
,
Takahashi, Nobuhiro
in
631/326
,
631/326/2565
,
631/326/41
2020
Recently, it was suggested that the nitrite (NO
2
−
) produced from NO
3
−
by oral bacteria might contribute to oral and general health. Therefore, we aimed to clarify the detailed information about the bacterial NO
2
-production in the oral biofilm. Dental plaque and tongue-coating samples were collected, then the NO
2
-producing activity was measured. Furthermore, the composition of the NO
2
−
-producing bacterial population were identified using the Griess reagent-containing agar overlay method and molecular biological method. NO
2
−
-producing activity per mg wet weight varied among individuals but was higher in dental plaque. Additionally, anaerobic bacteria exhibited higher numbers of NO
2
−
-producing bacteria, except in the adults’ dental plaque. The proportion of NO
2
−
-producing bacteria also varied among individuals, but a positive correlation was found between NO
2
−
-producing activity and the number of NO
2
−
-producing bacteria, especially in dental plaque. Overall, the major NO
2
−
-producing bacteria were identified as
Actinomyces, Schaalia, Veillonella
and
Neisseria
. Furthermore,
Rothia
was specifically detected in the tongue coatings of children. These results suggest that dental plaque has higher NO
2
−
-producing activity and that this activity depends not on the presence of specific bacteria or the bacterial compositions, but on the number of NO
2
−
-producing bacteria, although interindividual differences were detected.
Journal Article
Removing Interfering Signals in Spaceborne Radar Data for Precipitation Detection at Very High Altitudes
2023
This study investigated the effects of interfering signals on high-altitude precipitation extraction from spaceborne precipitation radar data. Data analyses were performed on the products of the Tropical Rainfall Measuring Mission Precipitation Radar (TRMM PR) and the Global Precipitation Measurement
Core Observatory
Dual-Frequency Precipitation Radar (GPM DPR) to clarify the effects of removing radio interferences and mirror images, particularly focusing on deep precipitation detection. The TRMM PR acquired precipitation data up to an altitude of approximately 20 km and occasionally captured interferences from artificial radio transmissions in specific areas. Artifacts could be distinguished as isolated profiles exhibiting almost constant radar reflectivity. The number of interferences affecting the TRMM PR gradually increased during the operation period of 1998–2013. A filter was introduced to separate the observed profiles into deep storms that reach the upper observation altitude and contamination caused by radio interference. The former frequently appeared over the Sahel area, where the observation upper limits are lowest. The removal of the latter, radio interference, improved the detection accuracy of the mean precipitation at high altitudes and considerably influenced specific low-precipitation areas such as the Middle East. This spatial feature–based filter allowed us to evaluate the results of screening based on noise limits that are implemented in standard algorithms. The GPM DPR Ku-band radar product contained other unwanted echoes due to the mirror images appearing as second-trip echoes contaminating the high-altitude statistics. Such second-trip echoes constitute a major portion of the echoes observed near the highest altitudes of deep storms.
Journal Article
Metabolic property of acetaldehyde production from ethanol and glucose by oral Streptococcus and Neisseria
2019
Acetaldehyde is known to be carcinogenic and produced by oral bacteria. Thus, bacterial acetaldehyde production might contribute to oral cancer. Therefore, we examined bacterial acetaldehyde production from ethanol and glucose under various conditions mimicking the oral cavity and clarified the metabolic pathways responsible for bacterial acetaldehyde production.
Streptococcus mitis
,
S
.
salivarius
,
S
.
mutans
,
Neisseria mucosa
and
N
.
sicca
were used. The bacterial metabolism was conducted at pH 5.0–8.0 under aerobic and anaerobic conditions. The production of acetaldehyde and organic acids was measured with gas chromatography and HPLC, respectively. Bacterial enzymes were also assessed. All of the bacteria except for
S
.
mutans
exhibited their greatest acetaldehyde production from ethanol at neutral to alkaline pH under aerobic conditions.
S
.
mutans
demonstrated the greatest acetaldehyde from glucose under anaerobic conditions, although the level was much lower than that from ethanol. Alcohol dehydrogenase and NADH oxidase were detected in all of the bacteria. This study revealed that oral indigenous bacteria,
Streptococcus
and
Neisseria
can produce acetaldehyde, and that such acetaldehyde production is affected by environmental conditions. It was suggested that alcohol dehydrogenase and NADH oxidase are involved in ethanol-derived acetaldehyde production and that the branched-pathway from pyruvate is involved in glucose-derived acetaldehyde production.
Journal Article
SAMMSON fosters cancer cell fitness by concertedly enhancing mitochondrial and cytosolic translation
by
Vendramin, Roberto
,
Lafontaine, Denis L J
,
Saraf, Kritika
in
Cancer
,
Complex formation
,
Cytosol
2018
Synchronization of mitochondrial and cytoplasmic translation rates is critical for the maintenance of cellular fitness, with cancer cells being especially vulnerable to translational uncoupling. Although alterations of cytosolic protein synthesis are common in human cancer, compensating mechanisms in mitochondrial translation remain elusive. Here we show that the malignant long non-coding RNA (lncRNA) SAMMSON promotes a balanced increase in ribosomal RNA (rRNA) maturation and protein synthesis in the cytosol and mitochondria by modulating the localization of CARF, an RNA-binding protein that sequesters the exo-ribonuclease XRN2 in the nucleoplasm, which under normal circumstances limits nucleolar rRNA maturation. SAMMSON interferes with XRN2 binding to CARF in the nucleus by favoring the formation of an aberrant cytoplasmic RNA–protein complex containing CARF and p32, a mitochondrial protein required for the processing of the mitochondrial rRNAs. These data highlight how a single oncogenic lncRNA can simultaneously modulate RNA–protein complex formation in two distinct cellular compartments to promote cell growth.
Journal Article
Distinct shed microvesicle and exosome microRNA signatures reveal diagnostic markers for colorectal cancer
by
Ishikawa, Hideaki
,
Greening, David W.
,
Suwakulsiri, Wittaya
in
Analysis
,
Biochemistry
,
Bioindicators
2019
Extracellular vesicle (EV) microRNAs are of major interest as potential diagnostic biomarkers in all cancer types. This study aims to identify miRNA profiles of shed microvesicles (sMVs) and exosomes (Exos) secreted from the isogenic colorectal cancer (CRC) cell lines SW480 and SW620 and evaluate their ability to predict CRC. Deep sequencing of miRNAs in parental cell lysates (CLs) and highly-purified sMVs and Exos was performed. We focused on miRNAs enriched in EVs and dysregulated miRNAs in metastatic cells (SW620) relative to primary cancer cells (SW480). We investigated the ability of EV miRNA signatures to predict CRC tumours using 594 tumours (representing different pathological stages) and 11 normal samples obtained from TCGA. In SW480 and SW620 cells we identified 345 miRNAs, of which 61 and 73 were upregulated and downregulated in SW620-CLs compared to SW480-CLs, respectively. Selective distribution of cellular miRNAs into EVs results in distinct miRNA signatures for sMVs and Exos in each cell line. Cross cell line comparisons of EV miRNA profiles reveal a subset of miRNAs critical in CRC progression from primary carcinoma to metastasis. Many miRNAs non-detectable (<5 TPM) in CLs were significantly enriched (>1000 TPM) in secreted EVs. Strikingly, miR-7641 which is non-detectable in SW480-CL but upregulated in SW620-CL is highly enriched in EVs secreted from both cell lines. Pearson correlation analysis demonstrated that EV miRNA profiles can be used to predict CRC tumours with ~96% accuracy. Our findings suggest that EV miRNA profiles from CRC cell lines may allow prediction of CRC tumours, and that miR-7641 may serve as an attractive candidate for the specific, non-invasive diagnosis and prognosis of CRC.
Journal Article
Hypoxically cultured cells of oral squamous cell carcinoma increased their glucose metabolic activity under normoxic conditions
2021
The oxygen concentration within cancer tissue is known to be low, but is expected to increase rapidly when oxygen is supplied by angiogenesis and hematogenous metastasis, suggesting that rapid increases in oxygen levels might influence cancer cell physiology. Therefore, we investigated the effects of oxygen concentration fluctuations on the glucose metabolism of cancer cells. The glucose metabolism of oral squamous cell carcinoma (HSC-2 and HSC-3) and normal epithelial (HaCaT) cells cultured under normoxic (21% oxygen) or hypoxic (1% oxygen) conditions was measured using a pH-stat system under normoxic or hypoxic conditions. The acidic end-products and reactive oxygen species (ROS) generated by glucose metabolism were also measured. Under normoxic conditions, the metabolic activity of hypoxically cultured cancer cells was significantly increased, and the production of acids other than lactate was upregulated, while the normal cells did not respond to rapid increases in oxygen levels. ROS production was higher in normoxic conditions in all cells, especially the hypoxically cultured HSC-3 cells. Rapid increases in oxygen levels might enhance the glucose metabolism of hypoxically cultured cancer cells by mainly activating the TCA cycle and electron transport system, which might activate cancer cells through the ATP and ROS generation.
Journal Article