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Biomedical subjects

K Yoshiura

Publications and source records attributed to K Yoshiura.

At least 19 recordsLinked to original sources
PubMed2006

Size and orientation of masticatory muscles in patients with mandibular laterognathism.

Size measurements of jaw muscles reflect their force capabilities and correlate with facial morphology. Using MRI, we examined the size and orientation of jaw muscles in patients with mandibular laterognathism in comparison with a control group. We hypothesized that the muscles of the deviated side would be smaller than those of the non-deviated side, and that the muscles of both sides would be smaller than in controls. In patients, a comparison of deviated and non-deviated sides showed, in orientation, differences for masseter and medial pterygoid muscles, but, in size, differences only for the masseter muscle. Nevertheless, muscle sizes in patients were much smaller than in controls. Lateral displacement of the mandible can explain the orientation differences, but not the smaller muscle size, in patients. It is possible that the laterodeviation initiates an adaptive process in the entire jaw system, resulting in extensive atrophy of the jaw muscles.

Adaptation, Physiological↗
PubMed2006

A novel missense mutation in Van der Woude syndrome: usefulness of fingernail DNA for genetic analysis.

Van der Woude syndrome (VWS) is an autosomal-dominant oral facial disorder. To find a gene mutation in a Japanese family using fingernail DNA samples, we performed this study. We hypothesized that a gene mutation in IRF6 might be involved in VWS, and that fingernail DNA samples may be valuable for detecting such mutations. Linkage and haplotype analyses of the family mapped the disease locus to the 1q32-q41 region. Mutation analysis with an improved extraction method for fingernail DNA detected a novel missense mutation (1046A>T, E349V) in exon 7 of IRF6 in all the affected members of the family. Since the E349V change may disturb the hydrophobic core and affect regulatory activity of IRF6, it is most likely that the mutation is causative for VWS in this family. Fingernail DNA is thus useful for linkage and mutation analyses, since the fingernail can be easily obtained non-invasively, sent through the mail, and stored for a long period. We emphasize here the usefulness of fingernail DNA for the genetic analysis of a disease.

Adenine↗
PubMed2006

CT analysis of the Stafne's bone defects of the mandible.

OBJECTIVE: To investigate the aetiology of Stafne's bone defects by analysing the CT findings of two types of defects, which appeared differently on panoramic radiographs. METHODS: 32 lesions with suspicion of the Stafne's bone defect on a panoramic radiograph were categorised into two groups: typical "Stafne type", which showed the connection to the base of the mandible, and non-typical "Cyst type", which showed no connection. Age, sex, the existence of hypertension and the following CT findings: location, size and inner content of the defect, existence of expansion of the buccal cortical bone, and location of submandibular glands, were analysed. RESULTS: There were 14 "Stafne type" and 17 "Cyst type" on the panoramic radiographs. One lesion in the "Cyst type" was a true cystic lesion and was excluded from further review. The "Stafne type" was seen primarily in the posterior and inferior locations, while the "Cyst type" was seen in the anterior and superior locations on the CT. The size of the defect was significantly larger in the "Stafne type". Buccal cortical expansion was observed only in three lesions in the "Stafne type". While the "Cyst type" contained mainly fatty tissue, the "Stafne type" contained other soft tissues. Though the submandibular glands on the defect side were located anteriorly in both types compared with those on the contralateral side and on the control patients, they spread mainly outwards in the "Stafne type". CONCLUSION: The Stafne's bone defects are thought to be caused by the dislocated submandibular gland. The differences between the two types might occur as a result of a different location of the submandibular gland.

Adipose Tissue↗
PubMed2005

In vivo cross-sectional area of human jaw muscles varies with section location and jaw position.

Muscle cross-sectional area (CSA) is used as a measure for maximum muscle force. This CSA is commonly determined at one location within the muscle and for one jaw position. The purpose of this study was to establish a method to standardize the analysis of the CSA of the masticatory muscles in vivo, and to compare the CSAs along their entire length for two different jaw positions (opened and closed). The CSAs in the planes perpendicular to the long axes of the masseter, medial, and lateral pterygoid muscles were measured in ten normal young adult subjects by magnetic resonance imaging. Our results showed large differences among the muscles and a non-uniform change in CSA after jaw-opening. The method enables the CSA measurement to be standardized in vivo, and allows for a correct comparison of CSAs in different skull morphologies.

Adult↗
PubMed2005

Correlation between diagnostic accuracy and perceptibility.

OBJECTIVES: To correlate diagnostic accuracy for proximal caries with perceptibility of low contrast image details using regression analysis. The other purpose was to determine the attenuation range required for proximal caries diagnosis. METHODS: The results of the two types of observer performance tests described above were retrieved from previous studies. Recording media included in those studies were the Compuray and the Dixel, direct digital radiographic systems, and Ektaspeed Plus film. The average numbers of perceptibility of image details from five observers were calculated for each step and for every combination of contiguous steps of the aluminium test phantom from the perceptibility test. The average diagnostic accuracy for proximal caries from the same five observers was correlated with the total number of perceptible details from the phantom using regression analysis. Finally, attenuation range required for proximal caries diagnosis was calculated from the attenuation range of the phantom where the maximum correlation coefficient was obtained. RESULTS: Maximum correlation (r=0.68) was obtained at the combination of five contiguous steps of the aluminium test phantom. Attenuation range required for proximal caries diagnosis corresponded to the 2 mm to 6 mm thickness of aluminium with acrylic block of 12 mm thickness. CONCLUSIONS: There is a correlation between perceptibility of low contrast image details and diagnostic accuracy for proximal caries. There may be a possibility to simplify observer performance tests for proximal caries diagnosis by using the standardized phantom simulating its attenuation range.

Adolescent↗
PubMed2005

The clinical and diagnostic imaging findings of osteosarcoma of the jaw.

OBJECTIVE: To clarify the valuable clinical features and diagnostic imaging findings regarding the diagnosis of osteosarcoma of the jaw (OSJ). MATERIALS AND METHODS: The initial symptoms and diagnostic imaging findings of 10 patients with OSJ were analysed. The points analysed on the diagnostic images were as follows: any widening of the periodontal ligament space of the teeth on the periphery of the OSJ; the presence of radial spicules and Codman's triangle; any signs of bone destruction; and the patterns of osteogenesis. RESULTS: All patients had pain and/or swelling of the affected site, and all OSJs, except for one edentulous case, showed a widening of the periodontal ligament space of the teeth on the periphery of the OSJ. Radial spicules or Codman's triangle were observed in only three cases (30%). Four out of five mandibular OSJs were osteolytic or osteolytic dominant with bone destruction, while, in contrast, four out of five maxillary OSJs were osteogenic or osteogenic dominant, and three out of the four maxillary OSJs did not show bone destruction. The osteogenic OSJ without bone destruction was similar to some benign cemento-osseous lesions of the jaw and thus was difficult to diagnose as OSJ based on the diagnostic imaging findings alone. CONCLUSION: Even though some OSJ showed features similar to the benign tumours of the jaw bone based on the diagnostic imaging findings, the pain and swelling of the affected site, and the widening of the periodontal ligament space of the teeth on the periphery of OSJ were considered to be common findings, which may help in making an accurate diagnosis of OSJ in this limited series.

Adolescent↗
PubMed2005

Effects of the automatic exposure compensation on the proximal caries diagnosis.

OBJECTIVE: To elucidate the effect of automatic exposure compensation (AEC) on the diagnostic accuracy of proximal caries by comparing several digital intraoral imaging systems with a film. MATERIALS AND METHODS: Twenty-seven extracted teeth served as proximal caries samples. Three digital radiographic systems; the Compuray, the Dixel, and the Sens-A-Ray without scintillator layer, and Kodak Ekta-speed Plus films were used as recording media. Radiographs of the teeth samples were obtained with each recording medium under seven to eight different exposures including the optimum level. Six oral radiologists evaluated the possibility of proximal caries with the five-grade-confidence-scale. On digital radiographs, image manipulations were allowed after the initial assessment. Receiver operating characteristic (ROC) curves were obtained at each exposure in each recording medium. The area under the ROC curve (Az) was used as the representative value of diagnostic accuracy. Diagnostic accuracy (DA) curves were obtained by plotting averaged Az values from all observers as a function of incident exposure in each system. RESULTS: The effect of exposure variation on the DA was slight in the film while it was significantly larger in the digital systems without AEC. Among digital systems, the effect of exposure variation was smaller in the system with AEC than those without AEC. There was no significant effect on the diagnostic accuracy even if digital image manipulation was employed. CONCLUSION: AEC minimizes the decrease of DA due to inadequate exposures. Since it compensates for the narrow exposure range in the digital intraoral sensor systems, the system with AEC may be preferable for the clinical diagnostic tasks.

Adolescent↗
PubMed2004

Perceptibility curve test for conventional and colour-coded radiographs.

OBJECTIVE: A colour scale has been developed as a complement to the grey scale in radiographs. The aim of the present study was to compare colour-coded with conventional black-and-white radiographs in terms of the perceptibility curve test. MATERIALS AND METHODS: Twelve digital radiographs were exposed on a test object from low to high exposures and recorded using the DIXI system (Planmeca Oy, Helsinki, Finland). An aluminium test object was used containing ten object details in the form of holes with depths ranging from 0.03 mm to 0.30 mm in steps of 0.03+/-0.01 mm. The new colour scale was used to transform the conventional black-and-white radiographs into colour radiographs by specially designed software. Ten observers were asked to analyse four sets of radiographs, i.e. colour-coded and black-and-white radiographs, and reversed colour-coded and reversed black-and-white radiographs. The object detail having the lowest perceptible contrast in each radiograph was registered for each observer. Perceptibility curves were plotted based on the mean value of observer data. RESULTS: Results from the perceptibility curve test showed that the information in colour-coded radiographs was at least as good as that in black-and-white radiographs. In fact, in the lower exposure range, colour-coded radiographs exhibited better perception than conventional black-and-white radiographs. CONCLUSION: Radiographs that are colour-coded with the applied colour scale may be used as an alternative to conventional black-and-white radiographs.

Absorptiometry, Photon↗
PubMed2004

Comparison of the psychophysical properties of various intraoral film and digital systems by means of the perceptibility curve test.

OBJECTIVES: To compare psychophysical properties of two intraoral films and three digital systems using the perceptibility curve (PC) test. MATERIALS AND METHODS: A test object was used to determine the exposures and exposure differences between the total thickness of the test object and details consisting of holes of increasing depth. The PCs for the two intraoral films, UltraSpeed and EktaSpeed Plus, were constructed employing exposure and exposure differences from dose response functions. Integrals of the PCs were calculated to obtain the psychophysical properties of the two films. Psychophysical properties of the two films were compared with those of the three digital systems published previously (CDR, Dixel and Digora). RESULTS: The PC for the EktaSpeed Plus showed a slightly higher peak than that for the UltraSpeed. Available exposure ranges were comparable. The PC for the EktaSpeed Plus was shifted to the left of the exposure axis indicating its higher sensitivity as compared with UltraSpeed. All three digital systems had narrower but higher peaks compared with the films. The integrals for the digital systems were considerably larger than those for the two film types. CONCLUSIONS: All the three digital systems have superior psychophysical properties compared with the two tested films.

Absorptiometry, Photon↗
PubMed2004

Psychophysical properties of a new F-speed intraoral film.

OBJECTIVES: To compare the psychophysical properties of the new Kodak InSight F-speed intraoral dental film with those for the E-speed Ektaspeed Plus film by means of the perceptibility curve (PC) test. METHODS: A specially designed test object was used. The test object was made of aluminium and was 10 mm thick. It contained ten holes, contrast details, with the same diameter of 1.5 mm but with different depths. The depths ranged from 0.03 mm to 0.30 mm in steps of 0.03 mm. The holes were placed randomly within a square area with a total of 16 possible positions. Radiographs of the test object were obtained over the full exposure ranges of the two films. A Combex DX-907 dental X-ray unit was used operating at 10 mA and two tube potentials, 70 kVp and 90 kVp. The focus-to-object distance was 50 cm. Ten observers evaluated the radiographs under uniform artificial lighting using a view box and stated the number of perceptible representations of contrast details. In order to construct perceptibility curves, absolute values of the reciprocal of the minimum perceptible logarithmic exposure differences, 1/(DeltalogE)min, were plotted as functions of the logarithm of exposures, logE, registered by the tested films. Comparisons between the two films were made separately for the two tube potentials, 70 kVp and 90 kVp. RESULTS: The results are presented graphically. PCs for the InSight film had higher peaks than those for the Ektaspeed Plus film. This indicates that the viewers were able to perceive smaller exposure differences in the former compared with the latter. PCs for the InSight film were shifted towards the left along the exposure axis relative to the PCs for the Ektaspeed Plus film indicating that the former film is more sensitive than the latter. The integrals of the PCs for InSight film were larger than those for Ektaspeed film indicating superior psychophysical properties of the InSight film. CONCLUSIONS: From the point of view of perception, the new InSight film has such psychophysical properties in comparison with Ektaspeed Plus film that it will be the more favourable of the two in clinical radiographic practice.

Absorptiometry, Photon↗
PubMed2003

Up-regulation of TFF expression by PPARgamma ligands in gastric epithelial cells.

BACKGROUND: Although trefoil factor family peptides (TFF peptides) are assumed to play important roles in gastric mucosal protection, the regulatory mechanism of gastric TFF expression has not been fully understood yet. Recent reports showed gastric expression of peroxisome proliferator-activated receptor gamma (PPARgamma), a nuclear receptor known to be involved in the regulation of cell growth and differentiation in other cell types, such as adipocytes. AIM: To determine whether PPARgamma affects the expression of TFF in gastric epithelial cells. METHODS: MKN45 gastric cells were used as a model of gastric epithelial cells. DNA synthesis of the cells was determined by the measurement of BrdU incorporation. The effects of PPARgamma ligands, 15-deoxy-Delta12,14-prostaglandin J2 (15d-PGJ2) and troglitazone (TGZ) on TFF expression were assessed by real-time quantitative reverse transcription-polymerase chain reaction (RT-PCR). RESULTS: MKN45 cells expressed a significant amount of PPARgamma. Both 15d-PGJ2 and TGZ suppressed DNA synthesis of the cells in a dose-dependent manner. In the control condition, MKN45 cells most abundantly expressed TFF1 and the relative expression level of TFF1, TFF2, and TFF3 mRNA was 1700:32:1. TFF1 and TFF2 mRNA levels were significantly up-regulated by the incubation of the cells with 15d-PGJ2 (10 micro m) or TGZ (30 micro m), whereas TFF3 mRNA level was not affected. CONCLUSION: The results of the present study suggest a possible role of PPARgamma in the regulation of TFF expression in gastric epithelial cells.

Blotting, Western↗
PubMed2003

Perceptibility curves for the Digora system.

OBJECTIVES: To construct perceptibility curves (PCs) for given calibration settings in order to define psychophysical properties of the Digora storage phosphor system and to evaluate the effects of automatic exposure correction (AEC) on the PCs. METHODS: The Digora system was calibrated at two exposures, 80 microC kg(-1) (high calibration) and 40 microC kg(-1) (low calibration). Since the grey levels displayed in the radiographs are adjusted by AEC, dose-response functions at high calibration were obtained using AEC on and off modes. The dose-response function at low calibration was obtained with AEC off. The PC at each experimental setting was calculated using known physical parameters of the system and the performance of the average observer used in a previous study. In addition, PCs were also constructed using transmitted radiation flux behind the test object calculated from the attenuation coefficient in order to study observer and system performance. PCs obtained under these conditions were compared. RESULTS: The PC using calculated transmitted radiation flux behind the test object showed a wide plateau at the peak owing to AEC, while the PC obtained by a modified approach showed a higher but narrower peak. There were no differences between the two PCs using AEC on and off modes when the PCs were constructed using a modified approach. There were no differences between the two PCs obtained at high and low calibration settings or between the three PCs obtained with AEC on except for the position along the exposure axis. CONCLUSIONS: Psychophysical properties of the Digora system may be determined if we employ registered exposures from a dose-response function with AEC off under a given calibration setting. Under these circumstances the shape and height of the PCs will be unchanged irrespective of the AEC mode.

Algorithms↗
PubMed2003

Perceptibility curve test for digital radiographs before and after correction for attenuation and correction for attenuation and visual response.

OBJECTIVE: Two digital image processing methods, correction for X-ray attenuation and correction for attenuation and visual response, have been developed. The aim of the present study was to compare digital radiographs before and after correction for attenuation and correction for attenuation and visual response by means of a perceptibility curve test. MATERIAL AND METHODS: Radiographs were exposed of an aluminium test object containing holes ranging from 0.03 mm to 0.30 mm with increments of 0.03 mm. Fourteen radiographs were exposed with the Dixi system (Planmeca Oy, Helsinki, Finland) and twelve radiographs were exposed with the F1 iOX system (Fimet Oy, Monninkylä, Finland) from low to high exposures covering the full exposure ranges of the systems. Radiographs obtained from the Dixi and F1 iOX systems were 12 bit and 8 bit images, respectively. Original radiographs were then processed for correction for attenuation and correction for attenuation and visual response. Thus, two series of radiographs were created. Ten viewers evaluated all the radiographs in the same random order under the same viewing conditions. The object detail having the lowest perceptible contrast was recorded for each observer. Perceptibility curves were plotted according to the mean of observer data. RESULTS: The perceptibility curves for processed radiographs obtained with the F1 iOX system are higher than those for originals in the exposure range up to the peak, where the curves are basically the same. For radiographs exposed with the Dixi system, perceptibility curves for processed radiographs are higher than those for originals for all exposures. Perceptibility curves show that for 8 bit radiographs obtained from the F1 iOX system, the contrast threshold was increased in processed radiographs up to the peak, while for 12 bit radiographs obtained with the Dixi system, the contrast threshold was increased in processed radiographs for all exposures. When comparisons were made between radiographs corrected for attenuation and corrected for attenuation and visual response, basically no differences were found. CONCLUSION: Radiographs processed for correction for attenuation and correction for attenuation and visual response may improve perception, especially for 12 bit originals.

Humans↗
PubMed2002

Visual linearization of the display of digital radiographs.

OBJECTIVES: To derive and test a method to linearize the visual response of the display of digital radiographs so that equal steps in gray levels will be perceived as equal steps in brightness. METHOD: A mathematical analysis was performed and expressions for visual linearization were derived. Twenty-four test images were computer generated to confirm that visual linearization may be achieved. Each image had three groups of square areas of different size placed in three rows. The left and right squares in each row were given different gray levels to simulate various contrast levels. The middle squares were initially given the same gray level value as one of the outer squares. The images were examined by ten observers who could change the gray levels of the middle squares so that the step in brightness between the middle square and the outer squares become subjectively equal. The test was performed three times employing two different monitors. RESULTS: The experimental test confirmed that visual linearization could be achieved. Linear regression analyses gave determination coefficients of 0.9926 amd 0.9942 for monitors with gamma-values of 1.93 and 2.50. respectively. The mean data from the ten observers perfectly fitted those theoretically calculated. CONCLUSION: Visual linearization of gray levels can be achieved but further clinical research is needed to determine if this improves diagnosis.

Algorithms↗