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1.
The measurement of 13 items in the face and nose of 220 young adults (110 males and 110 females) of the Han nationality between the ages of 18 and 21 years has been done in the Henan Province of China. The means and standard deviations have been obtained, and the significant differences in many items between males and females have been proved. Some items influencing outer nasal shape have been analyzed. The correlations between nose height, nose length, and morphologic facial height and physiognomic facial height have been discussed. The ratio and amount of nasal breadth to facial breadth and nasal breadth to interocular breadth have been compared and analyzed, and the differences among the different races and between the sexes have been explained.  相似文献   

2.
Ribozyme和DNAzyme具有水解mRNA分子的功能,是阻断基因表达和抗病毒的重要工具。近年来,Ribozyme和DNAzyme在临床治疗研究中已经获得了长足进展,有许多成功的实例。比较了Ribozyme和DNAzyme的差异和特点,总结了它们在抗病毒、抗肿瘤、治疗遗传病、治疗神经系统疾病等方面的临床前研究、应用及进展。  相似文献   

3.
Polysaccharides containing galactofuranosyl and arabinofuranosyl residues are key components of many microorganisms. Recent investigations have provided a greater understanding of the biosynthetic pathways by which these glycans are assembled. Concomitant with these biochemical studies, an increasing number of chemical syntheses of oligofuranosides have been reported and new methods for their assembly have been developed.  相似文献   

4.
植物几丁质酶的结构与功能、分类及进化   总被引:7,自引:0,他引:7  
近年来对几丁质酶的研究越来越深入,资料也愈来愈多,有的植物几丁质酶除具有几丁质酶活性,还具有其它的活性,典型的几丁质酶由-N-端信号区,催化区和C-端延伸区组成,有的还有几丁质结合域,各项能域具有各自的功能,对植物几丁质酶的分类已经过多次改进,目前公认的分成4组9个亚组,有证据表明植物几丁质酶在进化过程中有遗传转座现象,但具有进化过程还有待进一步确证,对几丁质酶与其它一些蛋白的关系的了解有助于理解几丁质酶的起源和进化,由于几丁质酶具有独特的抗真菌特性,因而几丁质酶基因成为目前抗真菌基因工程研究的热之一。  相似文献   

5.
近年来对几丁质酶的研究越来越深入,资料也愈来愈多。有的植物几丁质酶除具有几丁质酶活性,还具有其它的活性。典型的几丁质酶由N_端信号区、催化区和C_端延伸区组成,有的还有几丁质结合域。各功能域具有各自的功能。对植物几丁质酶的分类已经过多次改进,目前公认的是分成4组9个亚组。有证据表明植物几丁质酶在进化过程中有遗传转座现象,但具体进化过程还有待进一步确证。对几丁质酶与其它一些蛋白的关系的了解有助于理解几丁质酶的起源和进化。由于几丁质酶具有独特的抗真菌特性,因而几丁质酶基因成为目前抗真菌基因工程研究的热点之一。  相似文献   

6.
Corticosteroids and leukotrienes play opposite roles in asthma. Corticosteroids, both endogenously secreted and exogenously administered, are antiinflammatory and are very effective in the treatment of asthma. They have also been evaluated chronotherapeutically and have been found to be very effective in reducing the enhanced airway inflammation and decrement in lung function associated with nocturnal worsening of asthma. Leukotrienes are potent proinflammatory and spasmogenic mediators that have been shown to be increased at night in patients with nocturnal asthma (NA). Leu-kotriene modifiers, a new class of medications to treat asthma, improve, but do not abolish, the symptoms and decrement in lung function associated with nocturnal asthma. However, they have not been evaluated chronotherapeutically. This article addresses the roles of corticosteroids and leukotrienes in nocturnal asthma and their position as therapeutic agents or targets for therapy.  相似文献   

7.
To determine the prevalence and distribution of rickettsial pathogens around the world, scientists have relied more and more upon molecular techniques in addition to serological and culture methods. The ease of use and sensitivity/specificity of molecular techniques such as quantitative real-time PCR assays and multilocus sequence typing have lead to an increase in reports of the detection and identification of new and old rickettsiae in previously known and in new endemic regions. These assays have been successfully used with clinical samples such as serum, blood, and tissue biopsies and with environmental samples such as arthropod vectors including ticks, fleas, lice, and mites, and blood and tissue specimens from small mammal collections and from wild and domestic large animals. These methods have lead to the detection of new and old rickettsial pathogens often in new locations leading investigators to suggest new regions of risk of these rickettsioses.  相似文献   

8.
The past eighteen months have provided much progress in the cyclic nucleotide phosphodiesterase (PDE) field. Six new phosphodiesterase genes have been discovered and characterized. In addition, several new highly specific PDE inhibitors have been developed and approved for clinical use. Finally, new strategies have been employed to determine PDE function in model systems including the use of antisense oligonucleotide and disruption techniques.  相似文献   

9.
An X-ray crystallographic study has confirmed that the potassium bisulfite adducts of D-glucose and D-mannose have open-chain structures with R and S configurations respectively at C-1. NMR studies have shown that each sugar gives rise to two bisulfite compounds, and solution-state structures and conformations of these isomers have been deduced from analysis of (1)H NMR spectra. (13)C NMR data for the four adducts are given. Furanose forms of the D-glucose and D-mannose have been detected in the equilibrium solutions.  相似文献   

10.
Corticosteroids and Leukotrienes: Chronobiology and Chronotherapy   总被引:2,自引:0,他引:2  
Corticosteroids and leukotrienes play opposite roles in asthma. Corticosteroids, both endogenously secreted and exogenously administered, are antiinflammatory and are very effective in the treatment of asthma. They have also been evaluated chronotherapeutically and have been found to be very effective in reducing the enhanced airway inflammation and decrement in lung function associated with nocturnal worsening of asthma. Leukotrienes are potent proinflammatory and spasmogenic mediators that have been shown to be increased at night in patients with nocturnal asthma (NA). Leu-kotriene modifiers, a new class of medications to treat asthma, improve, but do not abolish, the symptoms and decrement in lung function associated with nocturnal asthma. However, they have not been evaluated chronotherapeutically. This article addresses the roles of corticosteroids and leukotrienes in nocturnal asthma and their position as therapeutic agents or targets for therapy.  相似文献   

11.
Poloxamers and poloxamine nonionic surfactants have diverse applications in various biomedical fields ranging from drug delivery and medical imaging to management of vascular diseases and disorders. Although this is a progressive, rapidly advancing field in biotechnology, the future will depend on the recognition and rectification of a range of toxicity issues, which have to be addressed but have frequently been ignored until now.  相似文献   

12.
K. S. Antonets 《朊病毒》2017,11(5):300-312
Amyloids represent protein fibrils that have highly ordered structure with unique physical and chemical properties. Amyloids have long been considered lethal pathogens that cause dozens of incurable diseases in humans and animals. Recent data show that amyloids may not only possess pathogenic properties but are also implicated in the essential biological processes in a variety of prokaryotes and eukaryotes. Functional amyloids have been identified in archaea, bacteria, fungi, and animals, including humans. Plants are one of the most poorly studied groups of organisms in the field of amyloid biology. Although amyloid properties have not been shown under native conditions for any plant protein, studies demonstrating amyloid properties for a set of plant proteins in vitro or in heterologous systems in vivo have been published in recent years. In this review, we systematize the data on the amyloidogenic proteins of plants and their functions and discuss the perspectives of identifying novel amyloids using bioinformatic and proteomic approaches.  相似文献   

13.
Cyclooxygenase enzymes: catalysis and inhibition   总被引:4,自引:0,他引:4  
Scientists working in the field of cyclooxygenase enzymes have witnessed several major advances in the past two years. Crystal structures of fatty acid substrate and prostaglandin product complexes have been elucidated. Elegant site-directed mutagenesis studies have pinpointed the roles of key amino acids within the active site. Together, these results have provided key insights into the overall reaction mechanism. Detailed kinetics, spectroscopic and crystallographic studies have shed new light on the complex mechanism of inhibition of these fascinating enzymes. Finally, novel substrates of cyclooxygenase-2 have been identified.  相似文献   

14.
Plants are nutritious and hence herbivores and phytopathogens have specialized to attack and consume them. In turn, plants have evolved adaptations to detect and withstand these attacks. Such adaptations we call ‘defenses’ and they can operate either directly between the plant and the plant consumer or indirectly i.e. when taking effect via other organisms such as predators and parasitoids of herbivores. Plant defenses put selection pressure on plant-consumers and, as a result, herbivores and pathogens have evolved counter-adaptations to avoid, resist, or manipulate plant defenses. Here we review how plant consumers have adapted to cope with plant defenses and we will put special emphasis on the phenomenon of suppression of plant defenses.  相似文献   

15.
D N Propert 《Human heredity》1979,29(6):361-363
Pseudocholinesterase activity and the phenotypes controlled by the E1 locus have been determined in a sample of 307 Down's syndrome patients and 206 patients suffering from nonspecific mental retardation and compared to those in the healthy population. Both groups of patients have an elevated frequency of phenotypes possessing the rate E1f allele. The mentally retarded patients have a higher mean pseudocholinesterase activity than those with Down's syndrome who, in turn, have activity than the healthy controls.  相似文献   

16.
In considering the best possible solutions for answering phylogenetic questions from genomic sequences, we have chosen a strategy that we suggest is superior to others that have gone previously. We have ignored multigene families and instead have used single-gene families. This minimizes the inadvertent analysis of paralogs. We have employed strict data controls and have reasoned that if a protein is not capable of recovering the uncontroversial parts of a phylogenetic tree, then why should we use it for the more controversial parts? We have sliced and diced the data in as many ways as possible in order to uncover the signals in that data. Using this strategy, we have tested two controversial hypotheses concerning eukaryotic phylogenetic relationships: the placement of arthropoda and nematodes and the relationships of animals, plants, and fungi. We have constructed phylogenetic trees from 780 single-gene families from 10 completed genomes and amalgamated these into a single supertree. We have also carried out a total evidence analysis on the only universally distributed protein families that can accurately reconstruct the uncontroversial parts of the phylogenetic tree: a total of five families. In doing so, we ignore the majority of single-gene families that are universally distributed as they do not have the appropriate signals to recover the uncontroversial parts of the tree. We have also ignored every protein that has ever been used previously to address this issue, simply because none of them meet our strict criteria. Using these data controls, site stripping, and multiple analyses, 24 out of 26 analyses strongly support the grouping of vertebrates with arthropods (Coelomata hypothesis) and plants with animals. In the other two analyses, the data were ambivalent. The latter finding overturns an 11-year theory of Eukaryotic evolution; the first confirms what has already been said by others. In the light of this new tree, we re-analyze the evolution of intron gain and loss in the rpL14 gene and find that it is much more compatible with the hypothesis presented here than with the Opisthokonta hypothesis.  相似文献   

17.
靛蓝及其同类色素的微生物生产与转化   总被引:2,自引:0,他引:2  
靛蓝类色素广泛应用于印染、食品和医药工业, 其环境友好的合成或生产途径越来越受到人们的关注, 特别是微生物生物合成。已经鉴定和分离了能够合成靛蓝类色素的多种微生物, 并且明确了起催化作用的主要是单加氧酶和双加氧酶。已经克隆和利用了一些加氧酶的基因, 构建了工程菌, 优化了其发酵过程。同时, 微生物合成靛蓝的生物转化也已经起步。这些进展将带来环境友好的靛蓝类色素的合成与生产。  相似文献   

18.
Acidophilic and acid-tolerant fungi and yeasts   总被引:1,自引:1,他引:0  
Gross  Sabine  Robbins  Eleanora I. 《Hydrobiologia》2000,433(1-3):91-109
Fungi have not been systematically studied from mines and mine drainage waters, even though they are often encountered there. This paper provides a key from literature sources and lists morphological characteristics and habitat information for the 81 fungal species that have been collected or identified in pH <4 environments.  相似文献   

19.
This paper discusses the importance of geochemistry as a determining factor in the evolutionary development of plant assemblages. Three contrasting examples of geochemical systems are described and considered in relation to their effects on plant growth and development. Soils derived from serpentines may contain elevated and sometimes toxic concentrations of Cr and Ni depending on mineral composition and weathering processes. These conditions have so modified plant growth during the past few million years that specialized floras have evolved on particular sites. Extensive areas throughout the world contain high concentrations of Se but these have not always been accompanied by the development of specific floras. Geochemistry can help explain how Se-specific floras have developed in several Western States of America but are absent on Se-rich sites in the Republic of Ireland. Pronounced effects of As toxicity in plants have been recognized in recent years especially from areas polluted by smelter waste and fallout. As-tolerant genotypes have developed during the past 100 years and may still be evolving at the present time.  相似文献   

20.
E Argyle 《Origins of life》1977,8(4):287-298
Random chemical reactions in the Earth's primitive hydrosphere could have generated no more than 200 bits of information, whereas the first Darwinian organism must have encoded about a million bits, and therefore could not have arisen by chance. This information gap is bridged by separating reproduction from organism, and postulating a reproductive chemical community that would generate information by proto-Darwinian evolution. The information content of the initial community could have been as low as 160 bits, and its evolution might have led to the first Darwinian cell.  相似文献   

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