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Y Imasato

Publications and source records attributed to Y Imasato.

16 recordsLinked to original sources
PubMed1992

Tea catechins decrease micellar solubility and intestinal absorption of cholesterol in rats.

A(-)-epicatechin (EC) and (-)-epigallocatechin (EGC) mixture and a mixture of their gallates (ECG and EGCG, respectively) markedly lowered lymphatic cholesterol absorption in rats with a cannulated thoracic duct. A mixture of ECG and EGCG was more effective in reducing cholesterol absorption than the EC and EGC mixture. These catechins also tended to decrease lymphatic absorption of triacylglycerols, although not so pronounced as in cholesterol absorption. An in vitro study on micellar solubility of cholesterol showed that these catechin mixtures precipitated cholesterol solubilized in mixed bile salt micelles in a dose-dependent manner. A mixture of ECG and EGCG more effectively precipitated micellar cholesterol than a mixture of EC and EGC. When purified EC, EGC, ECG and EGCG were used, EGCG was more effective in precipitating micellar cholesterol than ECG. The effect of EC and EGC was comparable and weaker than their gallate esters. The bile acid concentration in the micelles was not affected by these catechins. A positive correlation was observed between the amount of coprecipitated EGCG and cholesterol. These results clearly show that tea catechins, in particular their gallate esters, effectively reduce cholesterol absorption from the intestine by reducing solubility of cholesterol in mixed micelles. The observation accounts for the hypocholesterolemic effect of tea catechins.

Animals↗
PubMed1991

Prolongation of antipyretic action and reduction of gastric ulcerogenicity in the rat by controlled-release granules of bermoprofen, a new nonsteroidal anti-inflammatory drug.

While bermoprofen [(+-)-10,11-dihydro-alpha,8-dimethyl-11- oxodibenz[b,f]oxepin-2-acetic acid], a new nonsteroidal antiinflammatory drug (NSAID), has potent antipyretic and analgesic activities with a short biological half-life, it shows ulcerogenic activity as a side-effect like other nonsteroidal anti-inflammatory drugs. A bermoprofen preparation was specially designed to prolong its duration of action and to reduce its side effect. Immediate-release granules (IRGs) were prepared by coating particles of Nonpareil 103 with bermoprofen. The IRGs were also coated by spraying a film solution composed of ethylcellulose and hydroxypropylmethylcellulose (3:2), and, thereby, three kinds of retard-release granules (RRGs) were obtained with the coating amounts of 1.5, 2.5, and 4%. Peak plasma bermoprofen levels were seen 0.5, 1, 2, and 3 h after single oral administrations of IRG, RRG(1.5%), RRG (2.5%), and RRG(4%), respectively, in rats. The potency order in ulcerogenic activity was RRG(1.5%) greater than IRG greater than RRG(2.5%) greater than RRG(4%) after a single oral dosage in rats. Then, IRG and RRG(4%) were mixed (in the ratio 3:7, which was calculated from their simulated plasma bermoprofen profiles) in order to get fast onset and long duration of antipyretic action. These mixed granules [i.e., the sustained-release granules (SRGs)] exhibited a falt plasma bermoprofen profile, and longer lasting antipyretic and lower ulcerogenic activities in rats in comparison with IRG or bermoprofen. From these results, it is suggested that a bermoprofen SRG preparation has more durable therapeutic activity and lower side-effects as a NSAID.

Animals↗
PubMed1991

Bioavailability of cyclandelate from capsules in beagle dogs and dissolution rate: correlations with bioavailability in humans.

The bioavailability in beagle dogs and the dissolution rates of cyclandelate from five capsule preparations commercially available in Japan were measured. One of the capsules that showed an extremely low bioavailability in humans also showed the lowest bioavailability in beagle dogs, although the difference in bioavailability with the highest preparation was smaller than in humans. A significant correlation was obtained between the results of the studies in humans and beagles. However, the power of the test using beagles was extremely low in comparison with that in the human study. Food enhanced the bioavailability of cyclandelate from the capsules having the highest and lowest bioavailability in the fasted state in beagles as observed in the human study previously. The bioinequivalence of the cyclandelate capsules detected in the fasted state disappeared in the fed state in the beagle dog study, while the bioinequivalence still remained in the non-fasted state in human subjects. Thus bioequivalence testing in the fed state led to different results in both species. The most poorly bioavailable capsule in both species in the fasted state showed a slow dissolution rate by several dissolution methods with moderate stirring. In order to obtain a good correlation with in vivo bioavailability, a large volume of test solution and addition of Tween 80 were required. Extensive growth of whiskers (needle-like crystals) was observed in the entire capsule mass having the lowest bioavailability.

Animals↗
PubMed1989

Characteristics of the gastrointestinal absorption of morphine in rats.

The absorption characteristics of morphine were investigated by using rat gastrointestine. Absorption and transport experiments were carried out by the in situ loop and the in vitro everted sac methods, respectively. Brush border membrane vesicles (BBMVs) were used for uptake experiments. Morphine and its metabolites, morphine-3-glucuronide (M-3-G), and morphine-6-glucuronide (M-6-G), in biological samples were simultaneously determined by high-performance liquid chromatography (HPLC) with ultraviolet (UV) detection and electrochemical detection. In the in situ loop method, morphine was well absorbed in the order of jejunal site greater than duodenal site greater than ileal site greater than middle intestinal site greater than rectal site, but it was poorly absorbed from the stomach. In each of the everted duodenal and jejunal sacs, 2,4-dinitrophenol, a metabolic inhibitor, inhibited the transport of morphine from the mucosal side to the serosal side. Further, HgCl2 pretreatment reduced the absorption of morphine from the duodenal and the jejunal loops. The initial uptake of morphine by BBMVs was stimulated in the presence of an H+ gradient (inner pH 7.5 and outer pH 5.0) and an overshoot phenomenon was observed. The initial uptake showed concentration dependence, i.e., it was saturable. Results obtained in this study indicate that carrier-mediated transport stimulated by the H+ gradient is partly involved in the duodeno-jejunal absorption of morphine, although morphine is passively absorbed from other sites.

Animals↗
PubMed1989

Influence of specific gravity and food on movement of granules in the gastrointestinal tract of rats.

The suitability of rats as an animal model for estimating the bioavailability of controlled-release granules in humans was investigated. Non-disintegrating granules (diameter of 0.8 mm; specific gravity of 0.9-1.85) were used as a model preparation. Twenty granules were administered to fed rats, fasted rats and rats given soft food, and the number of granules remaining in the gastrointestinal tract was counted at suitable intervals. Granules with a specific gravity of 1.25 administered to fasted rats were rapidly emptied from the stomach with a 50% gastric emptying time of 1 h as compared with granules with a specific gravity of less than 1.0 or with a high specific gravity such as 1.85. The presence of food in the stomach reduced the emptying rate of granules. The mean transit time of granules through the small intestinal tract was not influenced by the specific gravity or the presence of food. The mean transit time was about 3 h. It was found that the transit profile of granules through the gastrointestinal tract in rats was similar to that of granules in humans. Accordingly, it is possible to use rats at the preformulation stage for estimating the bioavailability of controlled-release granules in humans.

Animals↗
PubMedDate not supplied

Fundamental study of automatic cyto-screening for uterine cancer. III. New system of automated apparatus (CYBEST) utilizing the pattern recognition method.

An investigation was carried out, both from the point of view of combining features which are considered as being of the highest reliability based on pattern analysis of the nuclear structure and cytoplasm of cells, and the complexity of the apparatus. Several features such as "ambiguity" function were extracted by mathematical and statistical processing, and these were then made the parameters of a diagnostic logic. Also, a method in which a "differential histogram" and a "threshold value" are combined was developed for segmentation of cells. It became possible to operate an automatic scanning machine at a speed of about six minutes per slide using two-stage coarse and fine scanning of a flying spot scanner. The advantage of this system is flexibility of diagnostic program logic and speed of algorithms for a determined number of cellular features. An automatic focusing system was also developed and it functions satisfactorily at high speed on a fully extended regular object slide.

Cell Nucleus↗
PubMedDate not supplied

Fundamental study of automatic cytoscreening for uterine cancer. IV. Sample requirements for CYBEST and simulation test of cell dispersion.

The preparation of samples with good cell dispersion and without cell overlapping is a particularly important problem, whether for image processing systems or for flow systems. Simulation tests were carried out to estimate a cell density with good cell dispersion and a minimum number of overlapping cells. A little less than 50 cells per mm2 was disclosed to show a condition of sufficient cell dispersion. By microscopical observation and counting of the malignant cells using ten cases of uterine cervical carcinoma, it was found that in most instances over 50 malignant cells were contained in 20,000 to 40,000 cells on the smears. When the cell density is approximately 50 per mm2, the scanning area of the CYBEST of 40 X 20 mm may contain up to 40,000 cells. The probability that such a number of cells contains malignant cells is extremely high, in fact, nearly 100 per cent. By field tests, it was experimentally confirmed that these cell densities are very adequate for the function of the CYBEST.

Autoanalysis↗
PubMedDate not supplied

Fundamental study of automatic cytoscreening for uterine cancer. V. Data analysis for imporvement of CYBEST.

The particles selected by CYBEST as "abnormal cells" at the stage of coarse scanning were examined by direct microscopy to determine whether they were actural cells or not. Approximately 20 to 30 per cent of these were cell clusters and/or clumped leukocytes and red cell or specks of dust. Such incidents interfered considerably with a precise cytologic assessment. To eliminate this problem by means of a software algorithm, experiments were carried out setting thresholds for cell feature values. When the values obtained by machine measurement exceeded the theshold values the particles concerned were automatically disregarded, as interfering indidents, at the state of the coarse scanning. The approach was found to have substantial value in the operation of CYBEST as a pescreening device.

Autoanalysis↗
PubMedDate not supplied

Fundamental study of automatic cyto-screening for uterine cancer. I. Feature evaluation for the pattern recognition system.

A basic study was carried out to determine the parameters of a pattern recognition system for the automatic assessment of cytologic cell samples. Various cell features were extracted, whose combinations were evaluationed by an "ambiguity function". It was shown that the highest reliability can be obtained with a combination of the features of nuclear staining, nuclear area, area of cytoplasm, nuclear/cytoplasmic ratio, nuclear shape and chromatin pattern. However, recognition of the nuclear edge and chromatin patterns is complicated and makes automation difficult. Even if these two features are omitted, false positives do not exceed 20 per cent. Consequently screening of abnormal cells can be carried out by image recognition procedures by the use of a computer.

Cell Nucleus↗
PubMedDate not supplied

Fundamental study of automatic cyto-screening for uterine cancer. II. Segmentation of cells and computer simulation.

In images of Papanicolaou stained cells 64 gray levels have been differentiated by scanning densitomery. One of the two peaks in a differential histogram indicates the threshold of the cytoplasm, the other that of the nucleus. The two modes indicate where in the digitized image of good segmentation of the cell from its background and the nucleus from the cytoplasm can be accomplished.

Cell Nucleus↗