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61.
H. C. Lau Carolyn Horowitz Jocelyn Jumawan O. Koldovsky 《Cellular and molecular life sciences : CMLS》1978,34(5):566-567
Summary Triiodothyronine injected daily to pregnant rats for the last week of gestation (50 g/100 g b.wt) increased the specific activities of 5 acid glycosidases in the fetal forebrain and cerebellum. Cortisone (50 mg/100 g b.wt) administered in the same period had no effect on cerebellum acid hydrolases, but decreased their activity in the forebrain.Supported by grant No. HD 08536 from the National Institutes of Health, Bethesda, Maryland. 相似文献
62.
Pycnogenol enhances immune and haemopoietic functions in senescence-accelerated mice 总被引:1,自引:0,他引:1
F. J. Liu Y. X. Zhang B. H. S. Lau 《Cellular and molecular life sciences : CMLS》1998,54(10):1168-1172
Pycnogenol (procyanidin extracted from Pinus maritima) has been shown to be a potent free radical scavenger and an antioxidant phytochemical. The effects of pycnogenol on immune
and haemopoietic dysfunction in senescence-accelerated mice (SAM), as a murine model of accelerated ageing, were determined.
SAMP8, a strain of senile-prone mice, exhibit learning and memory deficits, immunodeficiency and dysfunction of the haemopoietic
system. Oral feeding with pycnogenol for 2 months significantly improved their T- and B-cell function. Pycnogenol also augmented
the proliferative capacity of haemopoietic progenitors of bone marrow in SAMP8. These data suggest that pycnogenol may be
useful for either retardation or restoration of parameters associated with ageing.
Received 3 July 1998; accepted 28 July 1998 相似文献
63.
The objective of this paper is to introduce three semi-automated approaches for ontology mapping using relatedness analysis techniques. In the architecture, engineering, and construction (AEC) industry, there exist a number of ontological standards to describe the semantics of building models. Although the standards share similar scopes of interest, the task of comparing and mapping concepts among standards is challenging due to their differences in terminologies and perspectives. Ontology mapping is therefore necessary to achieve information interoperability, which allows two or more information sources to exchange data and to re-use the data for further purposes. The attribute-based approach, corpus-based approach, and name-based approach presented in this paper adopt the statistical relatedness analysis techniques to discover related concepts from heterogeneous ontologies. A pilot study is conducted on IFC and CIS/2 ontologies to evaluate the approaches. Preliminary results show that the attribute-based approach outperforms the other two approaches in terms of precision and F-measure. 相似文献
64.
A cytosolic catalase is needed to extend adult lifespan in C. elegans daf-C and clk-1 mutants. 总被引:1,自引:0,他引:1
The dauer larva is an alternative larval stage in Caenorhabditis elegans which allows animals to survive through periods of low food availability. Well-fed worms live for about three weeks, but dauer larvae can live for at least two months without affecting post-dauer lifespan. Mutations in daf-2 and age-1, which produce a dauer constitutive (Daf-C) phenotype, and in clk-1, which are believed to slow metabolism, markedly increase adult lifespan. Here we show that a ctl-1 mutation reduces adult lifespan in otherwise wild-type animals and eliminates the daf-c and clk-1-mediated extension of adult lifespan. ctl-1 encodes an unusual cytosolic catalase; a second gene, ctl-2, encodes a peroxisomal catalase. ctl-1 messenger RNA is increased in dauer larvae and adults with the daf-c mutations. We suggest that the ctl-1 catalase is needed during periods of starvation, as in the dauer larva, and that its misexpression in daf-c and clk-1 adults extends lifespan. Cytosolic catalase may have evolved to protect nematodes from oxidative damage produced during prolonged dormancy before reproductive maturity, or it may represent a general mechanism for permitting organisms to cope with the metabolic changes that accompany starvation. 相似文献
65.
Meiyu He Jiaxi Xu Xiaoran He Tak Wah Dominic Chan Rebecca L. C. Lau 《科学通报(英文版)》2001,46(15):1281-1285
The mass spectra of five peptides with biological activities are reported. All mass spectra were recorded using a 4.7-T Fourier transform ion cyclotron resonance mass spectrometer equipped with an external electrospray source. The accurate molecular weights for the five peptides prepared by solid phase synthesis were measured as 1765.9013, 1063.5420, 1092.5254, 820.3804 and 1078.5193, respectively. All the data were obtained with the external calibration. Differences between observed and theoretical monoisotopic molecular weights were in the (0.2—1.0)×10-6 range. The complete primary sequence for the five polypeptides were determined using the method of in-source electrospray ionization/collision induced dissociation (ESI/CID). All the intact y series ions and b series ions were obtained from various peptides respectively, thus determining the sequences of the five polypeptides. We found that the measured accurate molecular mass of sample 4 was not in agreement with that expected from the planned synthetic peptide. The sequences of sample 4 were determined through analysis. The corresponding accurate masses of b series ions and y series ions were gained, which proved that it was correct to re-determine the sequences. 相似文献
66.
67.
The density distribution and internal structure of trabecular bone are modulated by local mechanical environment. In this study, an orthotropic adaptation algorithm was applied to the 3D femur model to simulate the variations of stiffness and orientation of trabecular bone under multi-loading conditions. This algorithm includes the determination of orthotropic axes and the stiffness modification of trabecular bone. Three methods were used to determine the orthotropic axes, i.e. the maximal cycle method, the stress maximum method, and the composite method. We found that the composite method was better than the other two. Firstly, the characteristics of density distribution obtained by using the composite method agreed better with those in real proximal femur. Secondly, the material orientation aligned with the known trabeculaer pattern. Finally, the ratios of the longitudinal modulus to the transverse modulus were also shown to be realistic in three local regions of the proximal femur. 相似文献
68.
69.
This study evaluates trends in quality of nanotechnology and nanoscience papers produced by authors from the People's Republic of China (PRC). The metric used to gauge quality is ratio of highly cited nanotechnology papers to total nanotechnology papers produced in sequential time frames. The USA is both the most prolific nanotechnology publishing country and most represented country on highly cited nanotechnology papers (both in absolute numbers of highly cited papers and highly cited papers relative to total publications) over the 1998-2003 time frame, based on the SCl/SSCl databases. Some of the smaller hi-tech countries have relatively high ratios (-2) of highly cited papers to total publications (e.g. Denmark, Netherlands, Switzerland). Countries that have exhibited rapid growth in SCl/SSCl nanotechnology paper production in recent years (e.g. PRC, South Korea) had ratios an order of magnitude less than that of the USA for 1998, but by 2003 had increased to about 20% that of the USA (-2.5). PRC and South Korea have climbed in the publications rankings from 6th and 9th in 1998, respectively, to 2nd and 6th in 2005, respectively. PRC's ratio monotonically increased from 0.16 to 0.45 over the 1998-2003 period, and South Korea's ratio increased from 0.11 to about 0.6 over that same period, indicating their papers are getting more and more citations proportionately. Thus, under rapid growth conditions, PRC and South Korea have been able to increase their share of participation in highly cited papers. As of 2003, PRC and South Korea have ratios comparable to nations like Japan, France, Italy, and Australia but not yet approaching those of the highly cited countries. None of the top ten publications producing institutions are from the USA, while all of the top ten highly cited publications producers are from the USA. Over the 1998-2003 time period, the top six total publications producing institutions (globally) remained the same, with Chinese Academy of Sciences (which consists 相似文献