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排序方式: 共有268条查询结果,搜索用时 15 毫秒
1.
Hiroyuki Kozu Isao Kobayashi Mitsutoshi Nakajima Kunihiko Uemura Seigo Sato Sosaku Ichikawa 《Food biophysics》2010,5(4):330-336
This paper uses computational fluid dynamics to simulate and analyze intragastric fluid motions induced by human peristalsis.
We created a two-dimensional computational domain of the distal stomach where peristalsis occurs. The motion of the gastric
walls induced by an antral contraction wave (ACW) on the wall of the computational domain was well simulated using a function
defined in this study. Retropulsive flow caused by ACW was observed near the occluded region, reaching its highest velocity
of approximately 12 mm/s in the narrowest region. The viscosity of the model gastric contents applied in this study hardly
affected the highest velocity, but greatly affected the velocity profile in the computational domain. The shear rate due to
gastric fluid motion was calculated using the numerical output data. The shear rate reached relatively high values of approximately
20 s−1 in the most occluded region. The shear rate profile was almost independent of the fluid viscosity. We also simulated mass
transfer of a gastric digestive enzyme (pepsin) in model gastric content when peristalsis occurs on the gastric walls. The
visualized simulation results suggest that gastric peristalsis is capable of efficiently mixing pepsin secreted from the gastric
walls with an intragastric fluid. 相似文献
2.
A new process for the simultaneous enzymic synthesis and purification of N-(benzyloxycarbonyl)-
-aspartyl-
-phenylalanine methyl ester (ZAPM), a precursor of aspartame, has been developed. The enzymic reaction between N-(benzyloxycarbonyl)-
-aspartic acid (ZA) and
-phenylalanine methyl ester (PM) was carried out in a biphasic hollow-fibre rector with an aqueous phase an a butyl acetate phase. The reaction took place in the aqueous phase and by maintaining the pH at 5, the product (ZAPM) was extracted into the organic phase. Product purity was greater than 90% and reasonable productivity could be achieved with this system. 相似文献
3.
Tatsuo Kawarasaki Tetsuya Kohsaka Masaru Sone Mitsutoshi Yoshida Kimio Bamba 《Molecular reproduction and development》1995,40(4):455-459
This study was carried out to determine whether Y-bearing porcine spermatozoa could be detected by in situ hybridization using a digoxigenin (Dig)-labelled DNA probe specific to the Y chromosome produced by polymerase chain reaction (PCR). A conventional PCR (with Dig-dUTP) was performed using a set of oligonucleotide primers (5′-AAGTGGTCAGCGTGTCCATA-3′ and 5′-TTTCTCCTGTATCCTCCTGC-3′) for 236 bp fragment of porcine male-specific DNA sequence and 1.25 × 104 template white blood cells obtained from a boar. When fluorescence in situ hybridization with the Dig-labelled DNA probe was applied to the metaphase chromosome spreads prepared from both boar and gilts, the fluorescein signal was only detected on the long arm of the Y chromosome. In addition, immunocytochemical detection with the Dig-labelled DNA probe and alkaline phosphatase-labeled anti-Dig was applied to both sperm nuclei pretreated with dithiothreitol and white blood cells; 51% of sperm nuclei and 96% of white blood cells obtained from boar were labelled, whereas none of white blood cells obtained from gilts were labelled with the Dig-labelled DNA probe. The results indicated that in situ hybridization with porcine male-specific DNA probe produced by PCR made possible the direct visualization of Y-bearing porcine spermatozoa by in situ hybridization. © 1995 Wiley-Liss, Inc. 相似文献
4.
Nobuakira Takeda Akira Tanamura Takaaki Iwai Mitsutoshi Kato Kenji Noma Makoto Nagano 《Molecular and cellular biochemistry》1993,129(2):139-143
The effects of captopril, an angiotensin-converting enzyme inhibitor, on congestive heart failure (CHF) were investigated in animal and clinical studies. Congestive heart failure was induced in rats by a combination of pressure and volume overload. Cardiac pressure overload was induced by constricting one renal artery (Goldblatt rat) and volume overload was induced by aorto-caval fistula. Captopril (100 mg/kg/day) was then administered for 14 weeks. Isometric contraction was assessed using isolated left ventricular papillary muscles. The maximum developed tension and the maximum rate of increase in tension (dT/dtmax) were decreased in untreated rats with CHF and improved in captopriltreated rats. The left ventricular myosin isoenzyme pattern was shifted towards V3 in untreated rats with CHF, and was shifted back towards V1 in the captopril-treated rats. In the clinical study, captopril (37.5–75 mg/day) was administered to patients with cardiomyopathy for 12 months. There was no effect on left ventricular mass in hypertrophic cardiomyopathy, although systolic anterior motion of the mitral valve disappeared in one patient. In dilated cardiomyopathy, however, left ventricular mass tended to decrease. These results indicate that captopril has a beneficial effect in congestive heart failure. 相似文献
5.
Mitsutoshi Kato Jie Yang Takaaki Iwai Akira Tanamura Toru Arino Osamu Kawashima Nobuakira Takeda 《Molecular and cellular biochemistry》1993,119(1-2):89-94
ADP/ATP carrier protein (AAC) is located in the mitochondrial inner membrane and has an important function in mitochondrial energy supply. This protein transports ATP to the cytoplasm and counter transports ADP into the mitochondria. J-2-N cardiomyopathic hamsters were investigated to determine the AAC content in cardiac mitochondria. After recording an electrocardiogram and collecting blood, the cardiac mitochondria were isolated. The mitochondrial membranes were labelled with eosin-5-maleimide (EMA) and separated on SDS polyacrylamide gels. The position of the AAC component was identified by exposing the gel under UV light, and the AAC content was determined by densitometry after staining with Coomassie blue. The AAC content ratio was significantly decreased in both 10-week-old and 1-year survived J-2-N hamsters when compared to control Golden hamster. Among 10-week-old J-2-N hamsters, the decrease in the AAC content ratio was more marked for the animals with more severe myocardial damage. The H+-ATPase activities of mitochondrial membrane were higher in 10-week-old J-2-N hamsters than in control hamsters. These results suggest that the decrease of AAC in J-2-N hamster plays an important role in the pathogenesis of cardiomyopathy in J-2-N hamsters. 相似文献
6.
Yuichi Takeuchi Reiko Fukumoto Hirokazu Kasahara Takeshi Sakaki Mitsutoshi Kitao 《Plant cell reports》1995,14(9):566-570
Cotyledons excised from dark-grown seedlings of cucumber (Cucumis sativus L.) were cultured in vitro under UV radiation at different wavelengths, obtained by passage of light through cut-off filters with different transmittance properties. Growth and the synthesis of chlorophyll (Chl) in cotyledons were inhibited and malondialdehyde was accumulated upon irradiation at wavelengths below 320 nm. Exogenous application of scavengers of free radicals reversed the growth inhibition induced by UV-B. Measurement of the fluorescence of Chl a suggested that electron transfer in photosystems was affected by UV-B irradiation. On the basis of these results, the involvement is postulated of active species of oxygen in damages to thylakoid membranes and the growth inhibition that are induced by UV-B irradiation.Abbreviations Chl
chlorophyll
- Fm
maximal fluorescence (dark)
- Fm
maximal fluorescence (light)
- Fv
variable fluorescence (dark)
- Fv
variable fluorescence (light)
- MDA
malondialdehyde
- O2
Superoxide radical
- PS
photosystem
- qN
non-photochemical quenching of fluorescence
- qP
photochemical quenching of fluorescence
- UV-BBE
biologically effective UV-B radiation
- WL(T = 0.5)
wavelength at which 50% transmittance occurs 相似文献
7.
Transforming growth factor-ß1 (TGF-β1) is a multifunctional cytokine that is involved in various pathophysiological processes, including cancer progression and fibrotic disorders. Here, we show that treatment with TGF-β1 (5 ng/mL) induced downregulation of cyclooxygenase-2 (COX-2), leading to reduced synthesis of prostaglandin E2 (PGE2), in human lung cancer A549 cells. Treatment of cells with specific inhibitors of COX-2 or PGE2 receptor resulted in growth inhibition, indicating that the COX-2/PGE2 pathway contributes to proliferation in an autocrine manner. TGF-β1 treatment induced growth inhibition, which was attenuated by exogenous PGE2. TGF-β1 is also a potent inducer of epithelial mesenchymal transition (EMT), a phenotype change in which epithelial cells differentiate into fibroblastoid cells. Supplementation with PGE2 or PGE2 receptor EP4 agonist PGE1-alcohol, as compared with EP1/3 agonist sulprostone, inhibited TGF-β1-induced expression of fibronectin and collagen I (extracellular matrix components). Exogenous PGE2 or PGE2 receptor agonists also suppressed actin remodeling induced by TGF-β1. These results suggest that PGE2 has an anti-fibrotic effect. We conclude that TGF-β1-induced downregulation of COX-2/PGE2 signaling is involved in facilitation of fibrotic EMT response in A549 cells. 相似文献
8.
Refeeding with a standard diet after a 48-h fast elicits an inflammatory response in the mouse liver
Motoko Oarada Takashi Miki Shohei Kohno Kanae Sakai Takeshi Nikawa Mitsutoshi Yoneyama Tohru Gonoi 《The Journal of nutritional biochemistry》2013,24(7):1314-1323
Unhealthy eating behaviors increase the risk of metabolic diseases, but the underlying mechanisms are not fully elucidated. Because inflammation contributes to the pathogenesis of metabolic diseases, it is important to understand the effects of unhealthy eating on the inflammatory state. The objective of our present study was to address the effects of a fasting–refeeding regime, a model of irregular eating, on the hepatic inflammatory responses in mouse. The animals were fasted for 48 h and then refed either a standard or low-carbohydrate/high-fat diet. Inflammatory gene expression in the liver was then sequentially measured for the first 17 h after initiation of refeeding. To assess the roles of dietary carbohydrates and toll-like receptor 2 (TLR2) in the refeeding-induced inflammatory changes, gene expression levels in mice refed only carbohydrates (α-corn starch and sucrose) at different doses and in TLR2-deficient mice refed a standard diet were also analyzed. Refeeding with a standard diet increased the liver expression of Tlr2, proinflammatory mediators (Cxcl10, Cxcl1, Cxcl2, Icam-1) and negative regulators of TLR-signaling (A20 and Atf3). These increases were attenuated in mice refed a low-carbohydrate/high-fat diet. Refeeding only α-corn starch and sucrose also increased the expression of these inflammatory pathway genes depending on the doses. TLR2 deficiency significantly attenuated the refeeding-induced increase in the liver expression of Cxcl10, Cxcl1, Icam-1 and A20. These findings suggest that an irregular eating behavior can elicit a liver inflammatory response, which is at least partly mediated by TLR2, and that dietary carbohydrates play critical roles in this process. 相似文献
9.
Mitsutoshi Nakamura Kenjiroo Matsumoto Yuta Iwamoto Takeshi Muguruma Naotaka Nakazawa Ryo Hatori Kiichiro Taniguchi Reo Maeda Kenji Matsuno 《Mechanisms of development》2013,130(2-3):169-180
Animals often show left–right (LR) asymmetry in their body structures. In some vertebrates, the mechanisms underlying LR symmetry breaking and the subsequent signals responsible for LR asymmetric development are well understood. However, in invertebrates, the molecular bases of these processes are largely unknown. Therefore, we have been studying the genetic pathway of LR asymmetric development in Drosophila. The embryonic gut is the first organ that shows directional LR asymmetry during Drosophila development. We performed a genetic screen to identify mutations affecting LR asymmetric development of the embryonic gut. From this screen, we isolated pebble (pbl), which encodes a homolog of a mammalian RhoGEF, Ect2. The laterality of the hindgut was randomized in embryos homozygous for a null mutant of pbl. Pbl is a multi-functional protein required for cytokinesis and the epithelial-to-mesenchymal transition in Drosophila. Consistent with Pbl’s role in cytokinesis, we found reduced numbers of cells in the hindgut epithelium in pbl homozygous embryos. The specific expression of pbl in the hindgut epithelium, but not in other tissues, rescued the LR defects and reduced cell number in embryonic pbl homozygotes. Embryos homozygous for string (stg), a mutant that reduces cell number through a different mechanism, also showed LR defects of the hindgut. However, the reduction in cell number in the pbl mutants was not accompanied by defects in the specification of hindgut epithelial tissues or their integrity. Based on these results, we speculate that the reduction in cell number may be one reason for the LR asymmetry defect of the pbl hindgut, although we cannot exclude contributions from other functions of Pbl, including regulation of the actin cytoskeleton through its RhoGEF activity. 相似文献
10.
Ayako Kitano Takeo Shimasaki Yuri Chikano Mitsutoshi Nakada Mayumi Hirose Tomomi Higashi Yasuhito Ishigaki Yoshio Endo Takahisa Takino Hiroshi Sato Yoshimichi Sai Ken-ichi Miyamoto Yoshiharu Motoo Kazuyuki Kawakami Toshinari Minamoto 《PloS one》2013,8(2)