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161.
Tabuchi M Ozaki M Tamura A Yamada N Ishida T Hosoda M Hosono A 《Bioscience, biotechnology, and biochemistry》2003,67(6):1421-1424
Neonatally streptozotocin-induced diabetic (n-STZ) rats were given food containing Lactobacillus GG cells (GG) or a control diet (control), from 9 to 18 weeks of age. The GG cells significantly lowered the blood hemoglobin A(1C) (HbA(1C)) level and improved glucose tolerance in n-STZ rats (p<0.05). In the GG group, the serum insulin level at 30 min after glucose loading was significantly higher than in the control group (p<0.05). 相似文献
162.
Spiders synthesize several kinds of silk fibers. In the primary structure of spider silk, one of the major ampullate (dragline, frame) silks, spidroin 1, and flagelliform silk (core fibers of adhesive spiral), there are common repeated X-Gly-Gly (X = Ala, Leu, Pro, Tyr, Glu, and Arg) sequences, which are considered to be related to the elastic character of these fibers. In this paper, two dimensional spin diffusion solid-state NMR under off magic angle spinning (OMAS), 13C chemical shift contour plots, and Rotational Echo DOuble Resonance (REDOR) were applied to determine the torsion angles of one Ala and two kinds of Gly residues in the Ala-Gly-Gly sequence of 13C=O isotope-labeled (Ala-Gly-Gly)10. The torsion angles were determined to be (, ) = (–90°, 150° ) within an experimental error of ±10° for each residue. This conformation is characterized as 31 helix which is in agreement with the structure proposed from the X-ray powder diffraction pattern of poly(Ala-Gly-Gly). The 31 helix of (Ala-Gly-Gly)10 does not change by formic acid treatment although (Ala-Gly)15 easily changes from the silk I conformation (the structure of Bombyx mori silk fibroin before spinning in the solid state) to silk II conformation (the structure of the silk fiber after spinning) by such treatment. Thus, the 31 helix conformation of (Ala-Gly-Gly)10 is considered very stable. Furthermore, the torsion angles of the 16th Leu residue of (Leu-Gly-Gly)10 were also determined as (, ) = (–90°, 150° ) and this peptide is also considered to take 31 helix conformation. 相似文献
163.
164.
Ismail AB Yoshinobu T Iwasaki H Sugihara H Yukimasa T Hirata I Iwata H 《Biosensors & bioelectronics》2003,18(12):1509-1514
This article reports an investigation on light-addressable potentiometric sensor (LAPS) to be used as a possible biological cell-semiconductor hybrid that will enable us to make an interface between the physical and biological system. To increase the surface potential sensitivity, we used a LAPS structure with single insulator (SiO2) coated with poly-L-ornithine and laminin (PLOL) on Si. Efficient culturing of PC-12 and nerve cells of Lymnaea stagnalis on PLOL-coated Si3N4 and SiO2 was achieved. The thickness of the PLOL layer was found to be about 4 nm by the atomic force microscope (AFM) measurement. Using the advantage of this thin layer of PLOL, we compared the performance of a novel structure to the previously reported "PLOL-coated Si3N4/SiO2/Si" structure. Due to high insulating capacitance, the photocurrent response of the novel LAPS was found to be very steep. As a result, higher sensitivity was achieved. This steepness did not degrade during 10 days when the sensor surface was kept in contact with the cell culture medium and environment. The thickness of PLOL layer, its ability to improve the biological cell adhesion, enhanced sensitivity, and experiment with simulated neural action potential (AP) applied to the novel LAPS show a good promise for LAPS to be a biological cell-semiconductor hybrid. 相似文献
165.
2',5'-isoDNA mimic chiral peptide nucleic acid (isoPNA) monomers derived from D- and L-aspartic acids were synthesized. These novel monomers were incorporated in aminoethylglycine peptide nucleic acid (aegPNA) thymine dodecamers, and the hybridization properties to RNA and DNA were demonstrated by UV thermal denaturation. 相似文献
166.
Isometric skeletal muscle fatigue is usually assumed to be a linear process based upon the monotonic decrease in spectral
frequency of the EMG. Since spectral analysis by fast Fourier transform (FFT) constitutes a linear transformation of the data,
the present study was designed to reevaluate the time-course of muscle fatigue with a nonlinear tool, recurrence quantification
analysis (RQA). Surface EMG recordings were obtained from the multifidus muscle of 17 human subjects during isometric posture-holding
of the upper torso. The process of muscle fatigue was found to be linear for 59% of the subjects by FFT criteria, but nonlinear
for 76% by RQA criteria. As a demonstrative control, both slow and fast transients occurring within a nonlinear mathematical
process could be accurately depicted by RQA, but not by FFT. It is concluded that assessment of EMG patterns by nonlinear
techniques can give insight into the time-course of fatiguing muscles attributed to the summation of several nonlinear and
competing processes.
Received: 12 November 1998 / Accepted in revised form: 29 November 1999 相似文献
167.
Denda M Tsuchiya T Elias PM Feingold KR 《American journal of physiology. Regulatory, integrative and comparative physiology》2000,278(2):R367-R372
Recent studies have shown that psychological stress can influence cutaneous barrier function, suggesting that this form of stress could trigger or aggravate skin disease. In the present study, we demonstrate that transfer of hairless mice to a different cage delays barrier recovery rates. Pretreatment with a phenothiazine sedative, chlorpromazine, before transfer of animals restored the kinetics of barrier recovery toward normal, suggesting that psychological stress is the basis for this alteration in barrier homeostasis. To determine the mechanism linking psychological stress to altered barrier recovery, we first demonstrated that plasma corticosterone levels increase markedly after transfer of animals to new cages and that pretreatment with chlorpromazine blocks this increase. Second, we demonstrated that the systemic administration of corticosterone delays barrier recovery. Finally, we demonstrated that pretreatment with the glucocorticoid receptor antagonist RU-486 blocks the delay in barrier recovery produced by systemic corticosterone, change of cage, or immobilization. These results suggest that psychological stress stimulates increased production of glucocorticoids, which, in turn, adversely affects permeability barrier homeostasis. 相似文献
168.
The effects of 100g melatonin injection at postnatal day 5 (PD 5) on the development of the central serotonergic systems in male and female rats were investigated. The contents of serotonin (5-HT) and 5-hydroxy-3-indolacetic acid (5-HIAA) were measured in several extra-hypothalamic regions at 3, 10 and 42 weeks of age. The neonatal melatonin administration increased both 5-HT and 5-HIAA levels in the striatum throughout the examined period. In the hippocampus, an increase in 5-HIAA contents by neonatal melatonin administration was found at 3 weeks but not 10 or 42 weeks of age. There were no significant differences in the effects of melatonin between male and female rats. These results indicated that exogenous melatonin administration during the early neonatal period influenced the development of the serotonergic systems in extrahypothalamic regions including the hippocampus and the striatum. 相似文献
169.
Rice is the only cereal in which germination and coleoptile elongation occur in hypoxia or anoxia. Little is known of the
molecular basis directly underlying coleoptile cell extension. In this paper, we describe the expression of α-expansin genes
in embryos during seed development and young seedlings grown under various oxygen concentrations. The genes Os-EXP2 and Os-EXP1 were predominantly expressed in the developing seeds, mainly in newly developed leaves, coleoptiles, and seminal roots. These
expansins expressed in the developing seeds may give cells the potential to expand after seed imbibition begins. In coleoptiles,
Os-EXP4 and Os-EXP2 mRNAs were greatly induced by submergence, while they were weakly detected in aerobic or anoxic conditions. Under submerged
soil conditions, the signals hybridized with probes Os-EXP4 and Os-EXP2 in coleoptiles were strongest when coleoptiles elongated in the water layer. These data show that expansin gene expression
is highly correlated with coleoptile elongation in response to oxygen concentrations. The Os-EXP4 gene was also expressed in leaves, mesocotyls, and coleorhizas of young seedlings. The growth of these tissues was also correlated
with the presence of expansins. Therefore, the evidence derived from this study clearly demonstrates that expansins are indispensable
for the growing tissues of rice seedlings.
Received: 23 December 1999 / Accepted: 24 February 2000 相似文献
170.
The photosynthetic purple bacteria such as Rb. sphaeroides possesses an intracytoplasmic membrane (ICM) and a variety of pigment-binding membrane proteins located in the ICM, acting
as photoreceptor. Such photosynthetic apparatus is concentrated in the ICM. It is composed of three multimeric membrane-bound
proteins; light-harvesting complexes (LH 1, LH 2), a reaction center (RC) and a cytochrome b/c1 complex. We have purified these membranes, which are called chromatophores, and characterized the structure and dynamics
of the photosynthetic membrane-bound proteins by means of multi-nuclear solid state NMR. First, the isotropic chemical shift
of carbonyl carbons in natural abundance and [1-13C] Phe labeled chromatophores indicates that the membrane-bound proteins take mainly the helical conformation. Second, the
chemical shifts of side-chain resonances of uniformly 15N-labeled chromatophores indicate the side-chain histidine residue is mainly hydrogen bonded, whereas structural heterogeneity
of arginine and lysine side-chains are probed by those wide distribution of 15N shifts. Thirdly, the [β-2H3]Ala and [ε-2H2]Tyr labeling of the chromatophores are performed and dynamics of the [β-2H]Ala and the [ε-2H2]Tyr labeled chromatophores are studied by means of 2H solid state NMR. The dynamics of [β-2H3]Ala is found to be a 108Hz three-site jump motion with 10° liberation along the Cα-Cβ bond axis. The 2H-NMR powder pattern spectrum of [ε-2H2] Tyr labeled chromatophores was interpreted with an averaged correlation time of 5×105 Hz with 180° two-fold flips, the result of the averaging of two kinds of split spectra in terms of motional time scale.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献