Search

Background The Precision ID Ancestry Panel with 165 SNP markers was unable to differentiate between mainland Japanese and Okinawa Japanese or to distinguish either of them from other East Asian populations. Aim An Okinawa panel was developed with the aim of further separating Okinawa Japanese individuals from mainland Japanese and other Asian groups. Seventy-five SNPs were selected using the most informative markers from the literature. Further, 22 SNPs were selected to separate Okinawa Japanese at minimum SNPs. Subjects and methods Samples were collected from 48 unrelated individuals from mainland Japan and 46 unrelated residents of the Okinawa prefecture. Data were evaluated by STRUCTURE, principal component, and GenoGeographer analyses. Results The 22 SNP set had similar levels of differentiation in STRUCTURE and PCA analyses as the 75 SNP set. GenoGeographer analysis showed that, out of the 46 Okinawa Japanese individuals, the 75 SNP and 22 SNP sets correctly assigned the Okinawan population as the most likely population of origin for 32 and 31 individuals, respectively. Conclusion Neither SNP set could completely differentiate between Okinawa Japanese and other Asian groups, however, these sets should be useful for crime investigation, when the sample, cost and time are limited.

Background The Precision ID Ancestry Panel with 165 SNP markers was unable to differentiate between mainland Japanese and Okinawa Japanese or to distinguish either of them from other East Asian populations. Aim An Okinawa panel was developed with the aim of further separating Okinawa Japanese individuals from mainland Japanese and other Asian groups. Seventy-five SNPs were selected using the most informative markers from the literature. Further, 22 SNPs were selected to separate Okinawa Japanese at minimum SNPs. Subjects and methods Samples were collected from 48 unrelated individuals from mainland Japan and 46 unrelated residents of the Okinawa prefecture. Data were evaluated by STRUCTURE, principal component, and GenoGeographer analyses. Results The 22 SNP set had similar levels of differentiation in STRUCTURE and PCA analyses as the 75 SNP set. GenoGeographer analysis showed that, out of the 46 Okinawa Japanese individuals, the 75 SNP and 22 SNP sets correctly assigned the Okinawan population as the most likely population of origin for 32 and 31 individuals, respectively. Conclusion Neither SNP set could completely differentiate between Okinawa Japanese and other Asian groups, however, these sets should be useful for crime investigation, when the sample, cost and time are limited.

The steady behaviour of a rarefied gas around a rotating sphere is studied numerically on the basis of the linearised ellipsoidal statistical model of the Boltzmann equation, also known as the ES model, and the Maxwell diffuse–specular boundary condition. It is demonstrated numerically that the normal derivative of the circumferential component of the flow velocity and that of the heat flux diverge on the boundary with a rate s⁻¹/² , where s is the normal distance from the boundary. Further, it is demonstrated that the diverging term is proportional to the magnitude of the jump discontinuity of the velocity distribution function on the boundary, which originates from the mismatch of the incoming and outgoing data on the boundary. The moment of force exerted on the sphere is also obtained for a wide range of the Knudsen number and for various values of the accommodation coefficient.

Adult Cebpb KO mice incisors present amelogenin-positive epithelium pearls, enamel and dentin allopathic hyperplasia, fewer Sox2-positive cells in labial cervical loop epitheliums, and reduced Sox2 expression in enamel epithelial stem cells. Thus, Cebpb acts upstream of Sox2 to regulate stemness. In this study, Cebpb KO mice demonstrated cementum-like hard tissue in dental pulp, loss of polarity by ameloblasts, enamel matrix in ameloblastic layer, and increased expression of epithelial-mesenchymal transition (EMT) markers in a Cebpb knockdown mouse enamel epithelial stem cell line. Runx2 knockdown in the cell line presented a similar expression pattern. Therefore, the EMT enabled disengaged odontogenic epithelial stem cells to develop supernumerary teeth. Cebpb and Runx2 knockdown in the cell line revealed higher Biglycan and Decorin expression, and Decorin-positive staining in the periapical region, indicating their involvement in supernumerary tooth formation. Cebpb and Runx2 acted synergistically and played an important role in the formation of supernumerary teeth in adult incisors.

Tundra fires are increasing in their frequencies and intensities due to global warming, which alter revegetation patterns through various pathways. To understand the effects of tundra fire and the resultant thermokarst on revegetation, vegetation and related environmental factors were compared between burned and unburned areas of Seward Peninsula, Alaska, using a total of 140 plots, 50 cm x 50 cm each. The area was burned in 2002 and surveyed in 2013. Seven vegetation types were classified by a cluster analysis and were categorized along a fire-severity gradient from none to severe fire intensity. The species richness and diversity were higher in intermediately disturbed plots. Severe fire allowed the immigration of fire-favored species (e.g., Epilobium angustifolium, Ceratodon purpureus) and decreased or did not change the species diversity, indicating that species replacement occurred within the severely burned site. Although thermokarsts (ground subsidence) broadly occurred on burned sites, due to thawing, the subsidence weakly influenced vegetation patterns. These results suggest that the fire directly altered the species composition at a landscape scale between the burned and unburned sites and it indirectly altered the plant cover and diversity through the differential modification, such as thermokarst, at a small scale within the burned site.

Tundra fires are increasing in their frequencies and intensities due to global warming, which alter revegetation patterns through various pathways. To understand the effects of tundra fire and the resultant thermokarst on revegetation, vegetation and related environmental factors were compared between burned and unburned areas of Seward Peninsula, Alaska, using a total of 140 plots, 50 cm x 50 cm each. The area was burned in 2002 and surveyed in 2013. Seven vegetation types were classified by a cluster analysis and were categorized along a fire-severity gradient from none to severe fire intensity. The species richness and diversity were higher in intermediately disturbed plots. Severe fire allowed the immigration of fire-favored species (e.g., Epilobium angustifolium, Ceratodon purpureus) and decreased or did not change the species diversity, indicating that species replacement occurred within the severely burned site. Although thermokarsts (ground subsidence) broadly occurred on burned sites, due to thawing, the subsidence weakly influenced vegetation patterns. These results suggest that the fire directly altered the species composition at a landscape scale between the burned and unburned sites and it indirectly altered the plant cover and diversity through the differential modification, such as thermokarst, at a small scale within the burned site.

Tundra fires are increasing in their frequencies and intensities due to global warming, which alter revegetation patterns through various pathways. To understand the effects of tundra fire and the resultant thermokarst on revegetation, vegetation and related environmental factors were compared between burned and unburned areas of Seward Peninsula, Alaska, using a total of 140 plots, 50 cm x 50 cm each. The area was burned in 2002 and surveyed in 2013. Seven vegetation types were classified by a cluster analysis and were categorized along a fire-severity gradient from none to severe fire intensity. The species richness and diversity were higher in intermediately disturbed plots. Severe fire allowed the immigration of fire-favored species (e.g., Epilobium angustifolium, Ceratodon purpureus) and decreased or did not change the species diversity, indicating that species replacement occurred within the severely burned site. Although thermokarsts (ground subsidence) broadly occurred on burned sites, due to thawing, the subsidence weakly influenced vegetation patterns. These results suggest that the fire directly altered the species composition at a landscape scale between the burned and unburned sites and it indirectly altered the plant cover and diversity through the differential modification, such as thermokarst, at a small scale within the burned site.

We typed 165 AIMs in 49 mainland Japanese and 47 Okinawa Japanese using the Precision ID Ancestry Panel (Thermo Fisher Scientific). None of the 165 SNPs showed significant deviation from Hardy-Weinberg equilibrium in the mainland Japanese. One SNP (rs3943253) showed significant deviation from Hardy-Weinberg equilibrium in Okinawa Japanese. Fisher’s exact tests showed that the genotype frequencies of 14 loci were significantly different (p < 0.05) between the two populations before correction for multiple testing. After Bonferroni correction, only rs671 remained statistically significant (p < 0.0003). This SNP is located in the ALDH2 gene. The mutant A allele is associated with increased side effects after alcohol intake. The frequency of the GG genotype (wild type) was higher in the Okinawa Japanese (78.7%) than in mainland Japanese (34.7%; Bonferroni corrected P < 0.001). For 31 (63.3%) of the mainland Japanese and 42 (89.4%) of Okinawa Japanese, the highest population likelihood was obtained with the Japanese reference population. However, only in a few individuals, the likelihoods were significantly different from those calculated using reference data from neighboring populations. The likelihoods for mainland Japanese and Okinawa Japanese were not significantly different from each other for any of the investigated individuals. STRUCTURE and PCA analyses showed that mainland Japanese, Okinawa Japanese, and East Asians could not be differentiated with the Precision ID Ancestry Panel.

Realistic projection of future climate-carbon (C) cycle feedbacks requires better understanding and an improved representation of the C cycle in permafrost regions in the current generation of Earth system models. Here we evaluated 10 terrestrial ecosystem models for their estimates of net primary productivity (NPP) and responses to historical climate change in permafrost regions in the Northern Hemisphere. In comparison with the satellite estimate from the Moderate Resolution Imaging Spectroradiometer (MODIS; 246 ± 6 g C m−2 yr−1), most models produced higher NPP (309 ± 12 g C m−2 yr−1) over the permafrost region during 2000–2009. By comparing the simulated gross primary productivity (GPP) with a flux tower-based database, we found that although mean GPP among the models was only overestimated by 10% over 1982–2009, there was a twofold discrepancy among models (380 to 800 g C m−2 yr−1), which mainly resulted from differences in simulated maximum monthly GPP (GPPmax). Most models overestimated C use efficiency (CUE) as compared to observations at both regional and site levels. Further analysis shows that model variability of GPP and CUE are nonlinearly correlated to variability in specific leaf area and the maximum rate of carboxylation by the enzyme Rubisco at 25°C (Vcmax_25), respectively. The models also varied in their sensitivities of NPP, GPP, and CUE to historical changes in climate and atmospheric CO2 concentration. These results indicate that model predictive ability of the C cycle in permafrost regions can be improved by better representation of the processes controlling CUE and GPPmax as well as their sensitivity to climate change.

The dominant mode of sea level pressure (SLP) variability during the winter months in the Northern Hemisphere (NH) is characterized by a dipole with one anomaly center covering the Arctic with the opposite sign anomaly stretched across the mid-latitudes. Associated with the SLP anomaly, is a surface temperature anomaly induced by the anomalous circulation. We will show that this anomaly pattern originates in the early fall, on a much more regional scale, in Siberia. As the season progresses this anomaly pattern propagates and amplifies to dominate much of the extratropical NH, making the Siberian high a dominant force in NH climate variability in winter. Also since the SLP and surface temperature anomalies originate in a region of maximum fall snow cover variability, we argue that snow cover partially forces the phase of winter variability and can potentially be used for the skillful prediction of winter climate., National Science Foundation (U.S.) (Grant ATM-9902433)

Our demonstration shows a system that estimates internal body structures from 3D surface models using deep convolutional neural networks trained on CT (computed tomography) images of the human body. To take pictures of structures inside the body, we need to use a CT scanner or an MRI (Magnetic Resonance Imaging) scanner. However, assuming that the mutual information between outer shape of the body and its inner structure is not zero, we can obtain an approximate internal structure from a 3D surface model based on MRI and CT image database. This suggests that we could know where and what kind of disease a person is likely to have in his/her body simply by 3D scanning surface of the body. As a first prototype, we developed a system for estimating internal body structures from surface models based on Visible Human Project DICOM CT Datasets from the University of Iowa Magnetic Resonance Research Facility., Comment: 2 pages, 3 figures

Supernumerary teeth and tooth agenesis are common morphological anomalies in humans. We previously obtained evidence that supernumerary maxillary incisors form as a result of the successive development of the rudimentary maxillary incisor tooth germ in Usag-1 null mice. The development of tooth germs is arrested in Runx2 null mice, and such mice also exhibit lingual epithelial buds associated with the upper molars and incisors. The aim of this study is to investigate the potential crosstalk between Usag-1 and Runx2 during tooth development. In the present study, three interesting phenomena were observed in double null Usag-1-/-/Runx2-/- mice: the prevalence of supernumerary teeth was lower than in Usag-1 null mice; tooth development progressed further compared than in Runx2 null mice; and the frequency of molar lingual buds was lower than in Runx2 null mice. Therefore, we suggest that RUNX2 and USAG-1 act in an antagonistic manner. The lingual bud was completely filled with odontogenic epithelial Sox2-positive cells in the Usag-1+/+/Runx2-/- mice, whereas almost no odontogenic epithelial Sox2-positive cells contributed to supernumerary tooth formation in the rudimentary maxillary incisors of the Usag-1-/-/Runx2+/+ mice. Our findings suggest that RUNX2 directly or indirectly prevents the differentiation and/or proliferation of odontogenic epithelial Sox2-positive cells. We hypothesize that RUNX2 inhibits the bone morphogenetic protein (BMP) and/or Wnt signaling pathways regulated by USAG-1, whereas RUNX2 expression is induced by BMP signaling independently of USAG-1.

[ackground]Wnt5a and Mrfzb1 genes are involved in the regulation of tooth size, and their expression levels are similar to that of Bmp7 during morphogenesis, including during the cap and early bell stages of tooth formation. We previously reported that Usag-1-deficient mice form supernumerary maxillary incisors. Thus, we hypothesized that BMP7 and USAG-1 signaling molecules may play important roles in tooth morphogenesis. In this study, we established double genetically modified mice to examine the in vivo inter-relationships between Bmp7 and Usag-1. [Results]We measured the volume and cross-sectional areas of the mandibular incisors using micro-computed tomography (micro-CT) in adult Bmp7- and Usag-1-LacZ knock-in mice and their F2 generation upon interbreeding. The mandibular incisors of adult Bmp7+/− mice were significantly larger than those of wild-type (WT) mice. The mandibular incisors of adult Usag-1−/− mice were the largest of all genotypes examined. In the F2 generation, the effects of these genes were additive; Bmp7+/− was most strongly associated with the increase in tooth size using generalized linear models, and the total area of mandibular supernumerary incisors of Usag-1−/−Bmp7+/− mice was significantly larger than that ofUsag-1−/−Bmp7 +/+ mice. At embryonic day 15 (E15), BrdU assays demonstrated that the labeling index of Bmp7+/− embryos was significantly higher than that of WT embryos in the cervical loop. Additionally, the labeling index of Usag-1−/− embryos was significantly the highest of all genotypes examined in dental papilla. [Conclusions]Bmp7 heterozygous mice exhibited significantly increased tooth sizes, suggesting that tooth size was controlled by specific gene expression. Our findings may be useful in applications of regenerative medicine and dentistry.

A significant portion of the large amount of carbon (C) currently stored in soils of the permafrost region in the Northern Hemisphere has the potential to be emitted as the greenhouse gases CO2 and CH4 under a warmer climate. In this study we evaluated the variability in the sensitivity of permafrost and C in recent decades among land surface model simulations over the permafrost region between 1960 and 2009. The 15 model simulations all predict a loss of near-surface permafrost (within 3m) area over the region, but there are large differences in the magnitude of the simulated rates of loss among the models (0.2 to 58.8x10(3)km(2)yr(-1)). Sensitivity simulations indicated that changes in air temperature largely explained changes in permafrost area, although interactions among changes in other environmental variables also played a role. All of the models indicate that both vegetation and soil C storage together have increased by 156 to 954TgCyr(-1) between 1960 and 2009 over the permafrost region even though model analyses indicate that warming alone would decrease soil C storage. Increases in gross primary production (GPP) largely explain the simulated increases in vegetation and soil C. The sensitivity of GPP to increases in atmospheric CO2 was the dominant cause of increases in GPP across the models, but comparison of simulated GPP trends across the 1982-2009 period with that of a global GPP data set indicates that all of the models overestimate the trend in GPP. Disturbance also appears to be an important factor affecting C storage, as models that consider disturbance had lower increases in C storage than models that did not consider disturbance. To improve the modeling of C in the permafrost region, there is the need for the modeling community to standardize structural representation of permafrost and carbon dynamics among models that are used to evaluate the permafrost C feedback and for the modeling and observational communities to jointly develop data sets an

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2000., Includes bibliographical references (p. 107-112)., Recently it has been shown that the Eurasian snow cover in the prior autumn (ESCSON) and the leading mode variability in the wintertime extratropical Northern Hemisphere (NH) atmospheric circulation have significant correlation. In this study, a linkage between the ESCSON and the following wintertime NH climate variability was investigated. Satellite data from the NOAA is used for snow cover, and NCEP/NCAR Reanalysis data are used for climate variables. The high latitudes sea-level pressure is quality-controlled by use of the IABP sea-level pressure dataset, which is derived from the buoy observations. Interannual variability of and association between ESCSON and winter climate variables were surveyed by use of linear statistical analysis techniques; Empirical Orthogonal Function (EOF) analysis, and correlation/regression analysis. The gravity current by the expansion of the cold, dense air over Siberia north- and westward remained one among the several possible mechanisms. The upper air mechanism may be active to connect the ESCSON and the leading mode of DJF surface pressure variability. It is also suggested that the DJF sea-level pressure variations associated with the ESCSON is considerably confined to the Atlantic side, and has only limited association with the linear trend and the Pacific side variations. Future work may include reexamination of the results using the possible, longer data of the observation. The mechanism connecting the ESCSON anomalies and the upper level circulation anomaly should be investigated further, for which one possible approach is analysis of the wave activity and energy propagation in the troposphere and stratosphere., by Kazuyuki Saito., S.M.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2000., Includes bibliographical references (p. 107-112)., Recently it has been shown that the Eurasian snow cover in the prior autumn (ESCSON) and the leading mode variability in the wintertime extratropical Northern Hemisphere (NH) atmospheric circulation have significant correlation. In this study, a linkage between the ESCSON and the following wintertime NH climate variability was investigated. Satellite data from the NOAA is used for snow cover, and NCEP/NCAR Reanalysis data are used for climate variables. The high latitudes sea-level pressure is quality-controlled by use of the IABP sea-level pressure dataset, which is derived from the buoy observations. Interannual variability of and association between ESCSON and winter climate variables were surveyed by use of linear statistical analysis techniques; Empirical Orthogonal Function (EOF) analysis, and correlation/regression analysis. The gravity current by the expansion of the cold, dense air over Siberia north- and westward remained one among the several possible mechanisms. The upper air mechanism may be active to connect the ESCSON and the leading mode of DJF surface pressure variability. It is also suggested that the DJF sea-level pressure variations associated with the ESCSON is considerably confined to the Atlantic side, and has only limited association with the linear trend and the Pacific side variations. Future work may include reexamination of the results using the possible, longer data of the observation. The mechanism connecting the ESCSON anomalies and the upper level circulation anomaly should be investigated further, for which one possible approach is analysis of the wave activity and energy propagation in the troposphere and stratosphere., by Kazuyuki Saito., S.M.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2000., Includes bibliographical references (p. 107-112)., Recently it has been shown that the Eurasian snow cover in the prior autumn (ESCSON) and the leading mode variability in the wintertime extratropical Northern Hemisphere (NH) atmospheric circulation have significant correlation. In this study, a linkage between the ESCSON and the following wintertime NH climate variability was investigated. Satellite data from the NOAA is used for snow cover, and NCEP/NCAR Reanalysis data are used for climate variables. The high latitudes sea-level pressure is quality-controlled by use of the IABP sea-level pressure dataset, which is derived from the buoy observations. Interannual variability of and association between ESCSON and winter climate variables were surveyed by use of linear statistical analysis techniques; Empirical Orthogonal Function (EOF) analysis, and correlation/regression analysis. The gravity current by the expansion of the cold, dense air over Siberia north- and westward remained one among the several possible mechanisms. The upper air mechanism may be active to connect the ESCSON and the leading mode of DJF surface pressure variability. It is also suggested that the DJF sea-level pressure variations associated with the ESCSON is considerably confined to the Atlantic side, and has only limited association with the linear trend and the Pacific side variations. Future work may include reexamination of the results using the possible, longer data of the observation. The mechanism connecting the ESCSON anomalies and the upper level circulation anomaly should be investigated further, for which one possible approach is analysis of the wave activity and energy propagation in the troposphere and stratosphere., by Kazuyuki Saito., S.M.

The purpose of this research was to clarify the meaning of easy swallowing, that is what kind of food texture can be swallowed safely by the elderly whose swallowing ability is decreasing with aging. The subjects of this experiment were 18 healthy individuals (10 males and 8 females, 19-35 years old of age) who understood the purpose of this research and gave their consent to participate in this study. Gelatin, agar, and starch were used as test-foods. After choosing at random the order of these 3 foods, We gave each food in six concentrations, in an order also chosen at random. Each sample of 5 ml was put on the center of the tongue and each subject was instructed to swallow it at once. The posture at the time of swallowing was adjusted so that FH plane should become horizontal, and the subject was instructed not to change the head position during swallowing. The subjective evaluation of swallowing was performed on the VAS scale from 0 to 100. In addition, swallowing was objectively evaluated by measuring its dynamic state from simultaneous recordings of the laryngeal movement and electromyogram. The laryngeal movement was measured with a newly improved device that measured pulse wave at fingertip level. Furthermore. simultaneous recordings of the laryngeal movement, electromyogram, and videofluorography were performed on another group of 3 subjects and the swallowing period found was divided in two: from the base of the tongue to the epiglottis (A) and from the epiglottis to the esophagus (B). Thereafter, the physical properties (hardness, adhesion) of all the foods used in the study were measured. For all foods, the VAS value decreased with the increase of the concentration. In all concentrations, gelatin showed a higher VAS value than the other foods. The duration of A increased with the food concentration, on the contrary, there was no difference in the duration of B for neither food nor concentration. The increase of the food concentration made swallowing subj, 本研究の目的は、食品の飲み込みやすさとは何か、すなわち、加齢に伴って嚥下機能が低下した高齢者にとって、どのような物性の食品が安全に嚥下できるのかを明らかにすることである｡被験者は事前に研究内容を十分説明して同意が得られた顎口腔機能に異常のない健常者18名(男10名、女8名、19～35歳)とした｡ゼラチン、寒天、デンプンを被験食品とし、3種類の食品と各食品において濃度の異なる6種類の試料をそれぞれ無作為に選択した｡試料5mlを被験者の舌背中央部に置き、一塊として嚥下するよう指示した｡嘆下時の姿勢はフランクフルト平面が床面と平行となるようにして、嚥下時には頭位の動きがないように指示した｡各被験食品の嚥下終了後に、主観的な飲み込みやすさをVisual Analogue Scale(VAS)を用いて0-100で評価した｡同時に、嚥下動態を喉頭運動と筋電図から客観的に評価した｡喉頭運動の測定は手指用脈波測定器を改良して新たに考案した測定装置を用いた｡また、別の3名を被験者として行った喉頭運動、筋電図と嚥下造影との同時測定結果から、嚥下時間、すなわち被験食品の咽頭通過時間を、舌背から喉頭蓋谷までの通過時間(A)と喉頭蓋谷から食道までの通過時間(B)に2分して測定した｡さらに、被験食品の物性(硬さ、付着性)を測定した｡飲み込みやすさの主観的評価では、すべての被験食品で濃度が高くなるに従ってVAS値が低下した｡ゼラチンは全ての濃度において、他の食品に比べて高いVAS値を示した｡舌背から喉頭蓋谷までの通過時間は被験食品の濃度が高くなると延長したのに対して、喉頭蓋谷から食道までの通過時間は被験食品の種類や濃度による変化は認められなかった｡被験食品で濃度が高くなると、主観的に嘆下し難いと評価され、舌背から喉頭蓋谷までの通過時間が延長したことから、舌背から喉頭蓋谷まで食品が移動する時間が飲み込みやすさの評価に影響していることが示唆された｡

The purpose of this research was to clarify the meaning of easy swallowing, that is what kind of food texture can be swallowed safely by the elderly whose swallowing ability is decreasing with aging. The subjects of this experiment were 18 healthy individuals (10 males and 8 females, 19-35 years old of age) who understood the purpose of this research and gave their consent to participate in this study. Gelatin, agar, and starch were used as test-foods. After choosing at random the order of these 3 foods, We gave each food in six concentrations, in an order also chosen at random. Each sample of 5 ml was put on the center of the tongue and each subject was instructed to swallow it at once. The posture at the time of swallowing was adjusted so that FH plane should become horizontal, and the subject was instructed not to change the head position during swallowing. The subjective evaluation of swallowing was performed on the VAS scale from 0 to 100. In addition, swallowing was objectively evaluated by measuring its dynamic state from simultaneous recordings of the laryngeal movement and electromyogram. The laryngeal movement was measured with a newly improved device that measured pulse wave at fingertip level. Furthermore. simultaneous recordings of the laryngeal movement, electromyogram, and videofluorography were performed on another group of 3 subjects and the swallowing period found was divided in two: from the base of the tongue to the epiglottis (A) and from the epiglottis to the esophagus (B). Thereafter, the physical properties (hardness, adhesion) of all the foods used in the study were measured. For all foods, the VAS value decreased with the increase of the concentration. In all concentrations, gelatin showed a higher VAS value than the other foods. The duration of A increased with the food concentration, on the contrary, there was no difference in the duration of B for neither food nor concentration. The increase of the food concentration made swallowing subj, 本研究の目的は、食品の飲み込みやすさとは何か、すなわち、加齢に伴って嚥下機能が低下した高齢者にとって、どのような物性の食品が安全に嚥下できるのかを明らかにすることである｡被験者は事前に研究内容を十分説明して同意が得られた顎口腔機能に異常のない健常者18名(男10名、女8名、19～35歳)とした｡ゼラチン、寒天、デンプンを被験食品とし、3種類の食品と各食品において濃度の異なる6種類の試料をそれぞれ無作為に選択した｡試料5mlを被験者の舌背中央部に置き、一塊として嚥下するよう指示した｡嘆下時の姿勢はフランクフルト平面が床面と平行となるようにして、嚥下時には頭位の動きがないように指示した｡各被験食品の嚥下終了後に、主観的な飲み込みやすさをVisual Analogue Scale(VAS)を用いて0-100で評価した｡同時に、嚥下動態を喉頭運動と筋電図から客観的に評価した｡喉頭運動の測定は手指用脈波測定器を改良して新たに考案した測定装置を用いた｡また、別の3名を被験者として行った喉頭運動、筋電図と嚥下造影との同時測定結果から、嚥下時間、すなわち被験食品の咽頭通過時間を、舌背から喉頭蓋谷までの通過時間(A)と喉頭蓋谷から食道までの通過時間(B)に2分して測定した｡さらに、被験食品の物性(硬さ、付着性)を測定した｡飲み込みやすさの主観的評価では、すべての被験食品で濃度が高くなるに従ってVAS値が低下した｡ゼラチンは全ての濃度において、他の食品に比べて高いVAS値を示した｡舌背から喉頭蓋谷までの通過時間は被験食品の濃度が高くなると延長したのに対して、喉頭蓋谷から食道までの通過時間は被験食品の種類や濃度による変化は認められなかった｡被験食品で濃度が高くなると、主観的に嘆下し難いと評価され、舌背から喉頭蓋谷までの通過時間が延長したことから、舌背から喉頭蓋谷まで食品が移動する時間が飲み込みやすさの評価に影響していることが示唆された｡