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941.
Ali C Akyildiz Lambert Speelman Harald van Brummelen Miguel A Gutiérrez Renu Virmani Aad van der Lugt Anton FW van der Steen Jolanda J Wentzel Frank JH Gijsen 《Biomedical engineering online》2011,10(1):25
Background
Rupture of the cap of a vulnerable plaque present in a coronary vessel may cause myocardial infarction and death. Cap rupture occurs when the peak cap stress exceeds the cap strength. The mechanical stress within a cap depends on the plaque morphology and the material characteristics of the plaque components. A parametric study was conducted to assess the effect of intima stiffness and plaque morphology on peak cap stress. 相似文献942.
Phytoplankton and nutrient dynamics of shallow coastal stations at Bay of Bengal,Eastern Indian coast 总被引:2,自引:0,他引:2
Phytoplankton dynamics of Eastern Indian coast was studied from surface water for a period of 24 months (April 2005–March
2007) in relation to environmental variables like, temperature, pH, dissolved oxygen, biochemical oxygen demand (BOD), salinity
and nutrient contents—including nitrate, phosphate and silicate. Total 43 taxa were recorded during the study period. Phytoplankton
density ranged from approximately 350–3,000 cells/ml and showed complete dominance of diatom genera namely, Asterionella japonica in winter and Odontella rhombus in summer. Other frequently occurring diatoms were Coscinodiscus perforatus, Actinocyclus normanii f. subsala, Thalassiothrix fraunfeldii, Ditylum brightwelli, Stephanodiscus hantzschoides, Cyclotella meneghiniana, Thalassionema nitzschoides etc. Seasonal changes in abundance and diversity of phytoplankton significantly differed showing maximum diversity in autumn
with high diversity index (2.76-Oct, 05) and minimum in winter (0.326-January, 06). The species evenness varied from 0.137
(January 06) to 0.991 (August 06), which signifies minimum variation in percentage contribution of individual species to total
phytoplankton population in monsoon and maximum in winter. Correlation studies of total cell count to physicochemical variables
indicated significant positive relation with dissolved oxygen, salinity and pH but negative relation with nitrate, silicate
and BOD of the water body. Multivariate procedures like ordination by principal component analysis and multi dimensional scaling
of phytoplankton population based on their occurrence data and magnitude of abundance indicated that some genera (Biddulphia heteroceros, B. dubia, Odontella aurita, Gyrosigma acuminatum, Coscinodiscus granii, Paralia sulcata, etc.) have specific preference for water temperature and salinity and flourished maximally in particular season(s). While
other genera (A. japonica, C. meneghiniana, C. perforatus, D. brightwelli, S. hantzschoides, etc.) appeared in wide range of temperature and salinity gradient. 相似文献
943.
Linda S. M. Ooi Wing-Shan Ho Karry L. K. Ngai Li Tian Paul K. S. Chan Samuel S. M. Sun Vincent E. C. Ooi 《Journal of biosciences》2010,35(1):95-103
A mannose-binding lectin (Narcissus tazetta lectin [NTL]) with potent antiviral activity was isolated and purified from the bulbs of the Chinese daffodil Narcissus tazetta var. chinensis, using ion exchange chromatography on diethylaminoethyl (DEAE)-cellulose, affinity chromatography on mannose-agarose and
fast protein liquid chromatography (FPLC)-gel filtration on Superose 12. The purified lectin was shown to have an apparent
molecular mass of 26 kDa by gel filtration and 13 kDa by SDS-PAGE, indicating that it is probably a dimer with two identical
subunits. The cDNA-derived amino acid sequence of NTL as determined by molecular cloning also reveals that NTL protein contains
a mature polypeptide consisting of 105 amino acids and a C-terminal peptide extension. Three-dimensional modelling study demonstrated
that the NTL primary polypeptide contains three subdomains, each with a conserved mannose-binding site. It shows a high homology
of about 60%–80% similarity with the existing monocot mannose-binding lectins. NTL could significantly inhibit plaque formation
by the human respiratory syncytial virus (RSV) with an IC50 of 2.30 μg/ml and exhibit strong antiviral properties against influenza A (H1N1, H3N2, H5N1) and influenza B viruses with
IC50 values ranging from 0.20 μg/ml to 1.33 μg/ml in a dose-dependent manner. It is worth noting that the modes of antiviral action
of NTL against RSV and influenza A virus are significantly different. NTL is effective in the inhibition of RSV during the
whole viral infection cycle, but the antiviral activity of NTL is mainly expressed at the early stage of the viral cycle of
influenza A (H1N1) virus. NTL with a high selective index (SI=CC50/IC50≥141) resulting from its potent antiviral activity and low cytotoxicity demonstrates a potential for biotechnological development
as an antiviral agent. 相似文献
944.
Commentary: Carbon Metabolism of the Terrestrial Biosphere: A Multitechnique Approach for Improved Understanding 总被引:2,自引:0,他引:2
J. G. Canadell H. A. Mooney D. D. Baldocchi J. A. Berry J. R. Ehleringer C. B. Field S. T. Gower D. Y. Hollinger J. E. Hunt R. B. Jackson S. W. Running G. R. Shaver W. Steffen S. E. Trumbore R. Valentini B. Y. Bond 《Ecosystems》2000,3(2):115-130
Understanding terrestrial carbon metabolism is critical because terrestrial ecosystems play a major role in the global carbon
cycle. Furthermore, humans have severely disrupted the carbon cycle in ways that will alter the climate system and directly
affect terrestrial metabolism. Changes in terrestrial metabolism may well be as important an indicator of global change as
the changing temperature signal. Improving our understanding of the carbon cycle at various spatial and temporal scales will
require the integration of multiple, complementary and independent methods that are used by different research communities.
Tools such as air sampling networks, inverse numerical methods, and satellite data (top-down approaches) allow us to study
the strength and location of the global- and continental-scale carbon sources and sinks. Bottom-up studies provide estimates
of carbon fluxes at finer spatial scales and examine the mechanisms that control fluxes at the ecosystem, landscape, and regional
scales. Bottom-up approaches include comparative and process studies (for example, ecosystem manipulative experiments) that
provide the necessary mechanistic information to develop and validate terrestrial biospheric models. An iteration and reiteration
of top-down and bottom-up approaches will be necessary to help constrain measurements at various scales. We propose a major
international effort to coordinate and lead research programs of global scope of the carbon cycle.
Received 7 May 1999; accepted 28 September 1999. 相似文献
945.
Recovery of transgenic plants by pollen-mediated transformation in <Emphasis Type="Italic">Brassica juncea</Emphasis> 总被引:1,自引:0,他引:1
The aroA-M1 encoding the mutant of 5-enolpyruvyl-shikimate-3-phosphate synthase (EPSPS) was introduced into the Brassica juncea genome by sonication-assisted, pollen-mediated transformation. The plasmid DNA and collected pollen grains were mixed in
0.3 mol/L sucrose solution and treated with mild ultrasonication. The treated pollen was then pollinated onto the oilseed
stigmas after the stamens were removed artificially. Putative transgenic plants were obtained by screening germinating seeds
on a medium containing glyphosate. Southern blot analysis of glyphosate-resistant plants indicated that the aroA-M1 gene had been integrated into the oilseed genome. Western blot analysis further confirmed that the EPSPS coded by aroA-M1 gene was expressed in transgenic plants. The transgenic plants exhibited increased resistance to glyphosate compared to untransformed
plants. Some of those transgenic plants had considerably high resistance to glyphosate. The genetic analysis of T1 progeny further confirmed that the inheritance of the introduced genes followed the Mendelian rules. The results indicated
that foreign genes can be transferred by pollen-mediated transformation combined with mild ultrasonication. 相似文献
946.
Chunbo Hao Hongxun Zhang Richard Haas Zhihui Bai Baoguo Zhang 《World journal of microbiology & biotechnology》2007,23(1):15-21
A sediment sample (pH 2.5) was collected at an acid mine drainage site in Anhui, China. The present acidophilic microbial
community in the sediment was studied with a 16S rRNA gene clone library. Small-subunit rRNA genes were PCR amplified, cloned
and screened by amplified rDNA restriction analysis (ARDRA). Subsequently, 10 different clones were identified and they were
affiliated with Acidobacteria, β/γ-Proteobacteria, δ-Proteobacteria, Nitrospira, Candidate division TM7, and Low G + C Gram-positives. Phylogenetic analysis of 16S rRNA gene sequences revealed a diversity
of acidophiles in the sediment that were mostly novel. Unexpectedly, 16S rRNA gene sequences affiliated with δ-Proteobacteria were found to constitute more than 60% of clone library. To our knowledge, this is the first occasion that bacteria of δ-Proteobacteria have been found dominant in the acidic habitat. Anaerobic sulfate- or metal reduction is the predominant physiological trait
of bacteria of this subdivision. The high sulfate, ferric iron and the presence of bioavailable carbon in the anaerobic microenvironment
may result in the dominance of bacteria of δ-Proteobacteria. 相似文献
947.
A thermophilic bacterial strain GXN151 which could degrade Avicel efficiently was isolated and identified as Bacillus licheniformis. A genomic library of GXN151 was constructed and two novel endoglucanase genes designated cel9A and cel12A were isolated by screening the library on carboxylmethyl cellulase indicator plates. The analysis of amino acid sequences deduced from the genes indicated that Cel9A consisted of a catalytic domain belonging to glycosyl hydrolase family 9, a linker domain, and a carbohydrate binding module family 3 from N-terminal to C-terminal; Cel12A had only one catalytic domain belonging to glycosyl hydrolase family 12. The combinations of Cel9A and Cel12A produced by the recombinant E. coli exhibited synergistic action against substrates of carboxylmethyl cellulose as well as Avicel. 相似文献
948.
Sediment quality criteria in use around the world 总被引:20,自引:0,他引:20
There have been numerous sediment quality guidelines (SQGs) developed during the past 20 years to assist regulators in dealing
with contaminated sediments. Unfortunately, most of these have been developed in North America. Traditionally, sediment contamination
was determined by assessing the bulk chemical concentrations of individual compounds and often comparing them with background
or reference values. Since the 1980s, SQGs have attempted to incorporate biological effects in their derivation approach.
These approaches can be categorized as empirical, frequency-based approaches to establish the relationship between sediment
contamination and toxic response, and theoretically based approaches that attempt to account for differences in bioavailability
through equilibrium partitioning (EqP) (i.e., using organic carbon or acid volatile sulfides). Some of these guidelines have
been adopted by various regulatory agencies in several countries and are being used as cleanup goals in remediation activities
and to identify priority polluted sites. The original SQGs, which compared bulk chemical concentrations to a reference or
to background, provided little insight into the ecosystem impact of sediment contaminants. Therefore, SQGs for individual
chemicals were developed that relied on field sediment chemistry paired with field or laboratory-based biological effects
data. Although some SQGs have been found to be relatively good predictors of significant site contamination, they also have
several limitations. False positive and false negative predictions are frequently in the 20% to 30% range for many chemicals
and higher for others. The guidelines are chemical specific and do not establish causality where chemical mixtures occur.
Equilibrium-based guidelines do not consider sediment ingestion as an exposure route. The guidelines do not consider spatial
and temporal variability, and they may not apply in dynamic or larger-grained sediments. Finally, sediment chemistry and bioavailability
are easily altered by sampling and subsequent manipulation processes, and therefore, measured SQGs may not reflect in situ
conditions. All the assessment tools provide useful information, but some (such as SQGs, laboratory toxicity and bioaccumulation,
and benthic indices) are prone to misinterpretation without the availability of specific in situ exposure and effects data.
SQGs should be used only in a “screening” manner or in a “weight-of-evidence” approach. Aquatic ecosystems (including sediments)
must be assessed in a “holistic” manner in which multiple components are assessed (e.g., habitat, hydrodynamics, resident
biota, toxicity, and physicochemistry, including SQGs) by using integrated approaches.
Received: December 26, 2000 / Accepted: December 28, 2001 相似文献
949.
Suk Hee Lee Suk Oh Young Il Kim Sang Cheol Jun Sang Sup So Hwan Gyu Kim 《Biotechnology and Bioprocess Engineering》2007,12(2):100-105
Phellinus linteus is a fungus which is found primarily in tropical regions of the Americas, Africa, and Asia.P. linteus has been used in traditional medical practice for the treatment of arthritis, liver damage and cancer. Angiogenesis is a
process that involves migration, proliferation and cell differentiation, as well as the formation of new capillary structures.
The anti-angiogenic activities evidenced by natural compounds may actually be a critical effect for the inhibition of angiogenesis-dependent
disease by these agents via the blockage of vascular development. This study assessed the effects of water extracts fromP. linteus (Phellinus extracts) on primary cultured porcine coronary artery endothelial cells (PCAECs).Phellinus extracts induced no changes in DNA synthesis or cell numbers, but inhibited the migration of PCAECs.Phellinus extracts also induced a reduction in the secretion of matrix metalloproteinase-2 (MMP-2) and MMP-9. Our results show that,
in endothelial cells,Phellinus extracts may inhibit angiogenesis by reducing levels of MMP-2 and MMP-9 secretion. 相似文献
950.
Eutrophication assessment and bioremediation strategy in a marine fish cage culture area in Nansha Bay,China 总被引:3,自引:0,他引:3
On the basis of field data measured during four cruises from January to November 2007, variations in the characteristics of
dissolved inorganic nitrogen and phosphate were analyzed in Nansha marine fish cage culture area, Ningbo City, China. Dissolved
inorganic nitrogen (DIN) was selected as the parameter to balance seaweed absorption and fish DIN production. The contents
of DIN and phosphate varied with different seasons, and eutrophication index (E) value ranged from 2.41 to 15.99, indicating serious eutrophication conditions; the annual average value of N/P of 32.95
indicates a nitrogen surplus in this system. The eutrophication condition in Nansha Bay was mainly caused by the fish cage
culture activities. Based on their biological characteristics, Laminaria and Gracilaria were selected as the bioremediation species in winter and spring and summer and autumn, respectively. The optimal co-cultivation
proportion of fish cage to Laminaria and Gracilaria in this bay was 1 cage, 450 m2 and one cage, 690 m2, respectively. 相似文献