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排序方式: 共有224条查询结果,搜索用时 15 毫秒
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2.
Danuta Rutkowska Jacek Pi tek Hiromi Tokura Krzysztof Linke Nana Takasu Naoki Inatsugi Teresa Torli ska 《Biological Rhythm Research》2006,37(3):241-246
Irritable bowel syndrome (IBS) is the most frequent functional disorder of the gastrointestinal tract, with great economical impact. The etiology and pathogenesis of the disease are unclear. Among patients seeking medical attention for IBS, 70 - 90% have psychiatric co-morbidity, most commonly major depression. In this study we test the influence of bright light on colon motility and subjectively felt symptoms. Eight IBS patients participated in the experiment. The passage rate was evaluated twice for every person: (1) after three days of exposure to bright light -3000 lux (from 8:00 to 18:00), (2) after three days exposure to dim light -100 lux (from 8:00 to 18:00). The comparison of colonic time in IBS patients point to differences in the elimination of markers, depending on experimental light conditions. After bright light conditions a tendency is observed to slower elimination of markers in the IBS-diarrhoea patients, and to a quicker elimination in the IBS-constipated patients. According to subjective feeling, all IBS patients reported an improvement in bowel function and relief of pain after bright but not after dim light application. Results of this preliminary study suggest that phototherapy might be a valuable addition to the conventional treatment of IBS. 相似文献
3.
Tadashi Hasegawa Jun Takashima Masako Takasu Yasuaki Hiwatari 《Molecular simulation》2013,39(3-6):365-381
Abstract Dynamical properties of condensed charged polymer melts are studied with a two-dimensional model and molecular dynamics simulation. Screened Coulombic interactions are assumed for the interactions between the monomer charges as well as the counterions which were introduced to neutralize the total monomer charges of polymer chains. Through molecular dynamics calculations, we have obtained the radial distribution function and velocity auto-correlation function, and their density dependences. As a structural characteristics in condensed charged polymer melts, we find that the monomers tend to form triangular structures locally. The radial distribution function for the center monomers implies that the polymer chains on our two-dimensional model are not entangled. The diffusion properties for both the counter-ions and innermost monomers are studied in detail. In this paper, we have also computed neutral polymer melts to study the effects of the presence of the long-range Coulombic interactions on the dynamical properties of polymer melts. We find that the Coulombic interactions significantly reduce the self diffusion. Snapshots analyses obtained from the molecular dynamics simulation suggest that the reptation model is not a proper model for two-dimensional polymer-chain melts, in which there are little entanglement effects in agreement with the result of the analyses for the radial distribution function. 相似文献
4.
Tatsuya Kawato Eiichi Mizohata Yohei Shimizu Tomohiro Meshizuka Tomohiro Yamamoto Noriaki Takasu 《Bioscience, biotechnology, and biochemistry》2013,77(4):640-642
The streptavidin/biotin interaction has been widely used as a useful tool in research fields. For application to a pre-targeting system, we previously developed a streptavidin mutant that binds to an iminobiotin analog while abolishing affinity for natural biocytin. Here, we design a bivalent iminobiotin analog that shows 1000-fold higher affinity than before, and determine its crystal structure complexed with the mutant protein. 相似文献
5.
The relationship between bacterial respiratory quinone (RQ) concentration and biomass was assessed for Lake Biwa bacterial assemblages to evaluate the utility of bacterial RQ concentration as an indicator of bacterial carbon. The biomass estimated from the RQ concentration correlated well with that from cell volume, indicating that RQ concentration is an appropriate indicator of bacterial biomass. The estimated carbon content per unit of RQ (carbon conversion factor) of bacteria was 0.67 mg C nmol RQ?1. Bacterial carbon biomass, which was estimated from the RQ concentration using the conversion factor, ranged between 0.008 and 0.054 mg C L?1 (average 0.025 mg C L?1) at 5 m depth and between 0.010 and 0.024 mg C L?1 (average 0.015 mg C L?1) at 70 m depth. Ubiquinone-8-containing bacteria dominated the epilimnion and hypolimnion. Compared to conventional image analysis, bacterial RQ analysis is a less laborious method of simultaneously determining bacterial biomass and community. 相似文献
6.
Yamanaka Yujiro Honma Ken-ichi Hashimoto Satoko Takasu Nana Miyazaki Toshihiko Honma Sato 《Sleep and biological rhythms》2006,4(3):199-206
Sleep and Biological Rhythms - Bright light is the principal zeitgeber for the biological clock in mammals, including humans. But there is a line of evidence that non-photic stimuli such as... 相似文献
7.
8.
Fugo Takasu 《Population Ecology》2009,51(3):399-409
Pine wilt disease is caused by the pinewood nematode Bursaphelenchus xylophilus, which is vectored by the Japanese pine sawyer beetle Monochamus alternatus. Due to their mutualistic relationship, according to which the nematode weakens and makes trees available for beetle reproduction
and the beetle in turn carries and transmits the nematode to healthy pine trees, this disease has resulted in severe damage
to pine trees in Japan in recent decades. Previous studies have worked on modeling of population dynamics of the vector beetle
and the pine tree to explore spatial expansion of the disease using an integro-difference equation with a dispersal kernel
that describes beetle mobility over space. In this paper, I revisit these previous models but retaining individuality: by
considering mechanistic interactions at the individual level it is shown that the Allee effect, an increasing per-capita growth
rate as population abundance increases, can arise in the beetle dynamics because of the necessity for beetles to contact pine
trees at least twice to reproduce successfully. The incubation period after which a tree contacted by a first beetle becomes
ready for beetle oviposition by later beetles is crucial for the emergence of this Allee effect. It is also shown, however,
that the strength of this Allee effect depends strongly on biological mechanistic properties, especially on beetle mobility.
Realistic individual-based modeling highlights the importance of how spatial scales are dealt with in mathematical models.
The link between mechanistic individual-based modeling and conventional analytical approaches is also discussed. 相似文献
9.
Masaki Fukuda Yu Komatsu Hironao Yamada Ryota Morikawa Takeshi Miyakawa Masako Takasu 《Molecular simulation》2014,40(6):498-503
Rational design of protein surface is important for creating higher order protein structures, but it is still challenging. In this study, we designed in silico the several binding interfaces on protein surfaces that allow a de novo protein–protein interaction to be formed. We used a computer simulation technique to find appropriate amino acid arrangements for the binding interface. The protein–protein interaction can be made by forming an intermolecular four-helix bundle structure, which is often found in naturally occurring protein subunit interfaces. As a model protein, we used a helical protein, YciF. Molecular dynamics simulation showed that a new protein–protein interaction is formed depending on the number of hydrophobic and charged amino acid residues present in the binding surfaces. However, too many hydrophobic amino acid residues present in the interface negatively affected on the binding. Finally, we found an appropriate arrangement of hydrophobic and charged amino acid residues that induces a protein–protein interaction through an intermolecular four-helix bundle formation. 相似文献
10.
M. Takata S. Hayashi C. E. Thomas S. Koyama T. Satoh H. Fugo 《Journal of evolutionary biology》2014,27(9):1830-1836
Life history theory predicts that natural selection favours parents who balance investment across offspring to maximize fitness. Theoretical studies have shown that the optimal level of parental investment from the offspring's perspective exceeds that of its parents, and the disparity between the two generates evolutionary conflict for the allocation of parental investment. In various species, the offspring hatch asynchronously. The age hierarchy of the offspring usually establishes competitive asymmetries within the brood and determines the allocation of parental investment among offspring. However, it is not clear whether the allocation of parental investment determined by hatching pattern is optimal for parent or offspring. Here, we manipulated the hatching pattern of the burying beetle Nicrophorus quadripunctatus to demonstrate the influence of hatching pattern on the allocation of parental investment. We found that the total weight of a brood was largest in the group that mimicked the natural hatching pattern, with the offspring skewed towards early hatchers. This increases parental fitness. However, hatching patterns with more later hatchers had heavier individual offspring weights, which increases offspring fitness, but this hatching pattern is not observed in the wild. Thus, our study suggests that the natural hatching pattern optimizes parental fitness, rather than offspring fitness. 相似文献