Biomedical subjects

Hideki Toyoda

Publications and source records attributed to Hideki Toyoda.

11 recordsLinked to original sources

PubMed2006

Features of early gastric cancer and gastric adenoma by enhanced-magnification endoscopy.

BACKGROUND: Changes to the mucosal surface of early gastric carcinomas and gastric adenomas as viewed by enhanced-magnification endoscopy with acetic acid have not been investigated thoroughly. Using this technology, we investigated the appearance of the gastric surface patterns of neoplastic and surrounding nonneoplastic mucosa. METHODS: Forty-seven consecutive patients with early gastric carcinomas or gastric adenomas underwent enhanced-magnification endoscopy following 1.5% acetic acid instillation. All biopsy specimens were taken from the area at which the enhanced-magnified endoscopic image was obtained. RESULTS: Surface patterns of gastric tumors and the surrounding mucosa were classified into five types: type I, small round pits of uniform size and shape; type II, slit-like pits; type III, gyrus and villous patterns; type IV, irregular arrangements and sizes of pattern types I, II and III; type V, destructive patterns of types I, II and III. The predominant pattern of the surrounding mucosa was type III, and most type III mucosa had characteristics of intestinal metaplasia. Although all elevated adenomas showed type II or type III surface patterns, both depressed adenomas showed type IV. Elevated carcinomas showed type III (42.9%) or type IV (57.1%) surface patterns, while depressed carcinomas showed type IV (70%) or type V (30%). Although differentiated tubular adenocarcinomas showed type III (10.3%), type IV (86.2%), or type V (3.5%) surface patterns, all of the signet-ring cell carcinomas and poorly differentiated tubular adenocarcinomas showed type V. CONCLUSIONS: Enhanced-magnification endoscopy may be useful for identifying gastric tumors and determining the extent of horizontal spread, especially in tumors of the depressed type.

Adenoma↗

PubMed2006

[The ranking model which estimates the factor scores of residual variables].

In this research, a new directions for utilizing the residual variable score in structural equation modeling was proposed. The residual variable score is created by removing the influence of the comprehensive index, which is strongly related to brand cognition from each trait factor. By using it as a new index, we tried to detect low cognition and high evaluation Brands which are not ranked high in the comprehensive index. It was shown that the ranking by the residual variable score on the same trait has very high correlation between years and same trait, and low correlation with the comprehensive index. Thus, the discriminant validity and stability of the new index were identified. Concerning the interpretation of the new index, it became clear that the brand which shows an increasing trend with the new index has the uniformly low degree of cognition as compared with the descending brand. It indicates that the new index has the capability of detecting brands with low cognition and high evaluation Brand.

Cognition↗

PubMed2005

[Comparison of several expressions of two-way ANOVA for a latent factor: analysis of the relation between music and mood].

The purpose of this research is to provide a two-way analysis of variance (ANOVA) model for a latent factor. Typical psychological studies measure mental states with questionnaires and analyze the variance of the measures into the portions attributable to various sources. This type of research, when conducted under regular ANOVA designs, uses total score as the dependent measures. However, this method is based on the unrealistic presumption that every item on the questionnaire has the same factor loading on the attribute being measured. In this research, we incorporated factor analysis model, and used a latent factor instead of total score as the dependent measure, thereby applying ANOVA under a more realistic assumption. Structural Equation Modeling (SEM) was used to express statistical models. This paper also examined a relation between music and mood, which is a quite popular area of research in psychology of music. To study the possible effects of tonality and key-signature on mood, music was chosen to represent tonality and key-signature conditions.

Adult↗

PubMed2004

Detection of intestinal metaplasia in distal esophagus and esophagogastric junction by enhanced-magnification endoscopy.

BACKGROUND: Standard videoendoscopy identifies columnar-lined esophagus but cannot distinguish intestinal metaplasia from other types of epithelium. Enhanced-magnification endoscopy identifies different mucosal pit patterns. A preliminary study suggested that a type 3 pattern is associated with the presence of intestinal metaplasia. This study assesses the value of enhanced-magnification endoscopy for the detection of intestinal metaplasia in the distal esophagus and esophagogastric junction in patients undergoing diagnostic EGD. METHODS: Patients undergoing diagnostic endoscopy for upper-GI symptoms underwent enhanced-magnification endoscopy after instillation of 1.5% acetic acid. The enhanced-magnification endoscopy mucosal pattern was classified into 3 types: 1, normal pits; 2, slit-reticular pattern; and 3, gyrus-villous pattern. Preliminary studies indicated that the type 3 pattern was related to intestinal metaplasia. One to 6 biopsies were targeted to areas having a type 3 pattern in columnar-appearing mucosa in the distal esophagus or esophagogastric junction. In the absence of type 3 pattern, one to 8 biopsies were targeted to areas with a type 2 pattern in columnar-appearing mucosa in the distal esophagus or esophagogastric junction. RESULTS: The overall frequency of intestinal metaplasia in the esophagus and esophagogastric junction was 38.8% (26/67 patients). There was a good correlation between the type 3 pattern and intestinal metaplasia in targeted biopsy specimens (sensitivity 88.5%, specificity 90.2%, positive predictive value 85.2%, negative predictive value 92.5%, overall accuracy 90.0%). CONCLUSIONS: Enhanced-magnification endoscopy is useful for detection of intestinal metaplasia in distal esophagus and esophagogastric junction.

Acetic Acid↗

PubMed2004

[Reliability of students' evaluations of university teaching: an analysis of four-facet data by a generalized model and structural equation modeling].

In our study, we examined the reliability of students' evaluation of university teaching. First, we analyzed four-facet data (teacher x rater x viewpoint x order) by the generalizability theory approach, and estimated the variance components for the facets as a G study. Then, we evaluated the reliability from the point of view of the generalizability coefficient (a reliability-like coefficient that is used when a decision concerns the relative ordering of individuals) and the index of dependability (an index that is used when a decision focuses on the absolute level of an individual's performance independent of others' performance), and examined how those indices change as the number of raters and viewpoints are changed. With these analyses we found conditions needed to maintain sufficient reliability of the evaluation for various situations. We also introduced a new method to evaluate the reliability at each level of facet by using structural equation modeling. By this method, one can examine the reliability of students' evaluation of university teaching more specifically.

Adult↗

PubMed2004

[Paired comparison analysis by using structural equation modeling: Scheffe's method and its improvements].

The purpose of this study is to propose a way to express and implement paired comparison analysis in a framework of structural equation modeling (SEM). By this method, one can perform paired comparison using widely available SEM programs and can develop a variety of models for specific purposes. Here, three models are shown. One is a model for performing basic paired comparison by using SEM. Another is an expanded model which makes it possible to apply analysis of variance (ANOVA) or regression analysis to the result of paired comparison. A third model is for paired comparison of latent factors. All models are illustrated with actual numerical examples.

Adult↗

PubMed2004

[Analysis of paired comparison data based on experimental design: expression using structural equation modeling].

Paired comparison is a useful method for assessing ranks among several objects, and it enables us to obtain more reliable data than assessing objects one by one. But paired comparison principally provides information only about the ranks of the objects. On the other hand, experimental design provides a framework for elucidating causal associations. If we could analyze paired comparison data by the experimental design framework, it would be a very effective method. But experimental design, in its original form, is not readily applicable to paired comparison data. However, if we adopt the perspective of structural equation modeling (SEM), we can deal with paired comparison and experimental design in a unified way, because they are both submodels of SEM. The purpose of this study is to provide a new method to analyze causal connection of paired comparison data by using SEM. Here, two actual numerical examples are shown, one of which is obtained by within-subject design and the other is obtained by between-subject design.

Humans↗

PubMed2004

[Structural equation modeling using ability parameters: analysis of the situation where item parameters have been estimated by item response theory].

One of the problems with structural equation modeling (SEM) is that the estimation of measurement equation is not separated from the estimation of structural equation. The main aim of this study was to propose a new method to overcome that problem by using ability parameters estimated by item response theory (IRT) as data. According to IRT, the error variance of measurement equation can be easily computed as the reciprocal of the information function. By using the estimates of the error variance, we can fix all parameters in measurement equation and can separate the estimation of structural equation from that of measurement equation. This method also allows us to estimate relations among factor scores with improved precision, because the errors of estimating factor scores are taken into account. The article concludes with a simulation result for verifying the efficacy of this method and an actual numerical.

Adult↗

PubMed2004

[Construction of a stress reaction scale based on an item response model and examination of the developmental process of psychological stress reactions by using test characteristic curves].

In this study, a stress reaction scale was constructed based on an Item Response Model, and the developmental process of psychological stress reactions was investigated by using test characteristic curves. Subjects consisted of 286 private college students and 234 national college students. The Job Stress Scale (JSS) was revised for college students, and used to assess psychological stress reaction. Graded response model of Item Response Theory (IRT) was used to estimate parameters. After estimating item and subject parameters, we assessed the precision of measurement and the fit of the model, and found both precision and fit to be satisfactory. Then we examined the test characteristic curves of each subscale to investigate the developmental process of psychological stress reactions of college students in comparison with company employees.

Adult↗

PubMed2002

[Estimation of Cronbach's alpha coefficient in the context of item response theory].

Cronbach's alpha coefficient is an index of reliability for the total score of a set of measurements. The alpha takes a value of 1.0 when the total score variance is perfectly attributable to the common factors running through the test items. In this research, a method of estimating Cronbach's coefficient alpha is proposed for the case where the parameters of dichotomous item response model are known and the ability distribution of subjects is given. In addition, the case of polytomous response model where the item parameters are estimated by graded response model (Samejima, 1969) is also considered, and a method of estimating the alpha coefficient is proposed for that case.

Adult↗

PubMed2002

[Parameter estimation for Rasch type items that have never been used].

This study proposes a new conjoint model with orthogonal array using the notation of the structural equation modeling. It is shown that commonly available computer programs such as LISREL (Jöreskog & Sörbom, 1993) and LISCOMP (Muthen, 1984) can be used to estimate the worth values of conjoint measure and item response curves of the Rasch type and graded response type. One remarkable feature of this method is that the response curves of items that have never been used, can be constructed. The constructed distribution functions were compared with the empirical distribution functions of cross validation data. The proposed method seemed to work well, because these functions were very similar to each other.

Models, Psychological↗