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Tineke E Buffart Melanie Louw Nicole CT van Grieken Marianne Tijssen Beatriz Carvalho Bauke Ylstra Heike Grabsch Chris JJ Mulder Cornelis JH van de Velde Schalk W van der Merwe Gerrit A Meijer 《BMC medical genomics》2011,4(1):7
Background
Infection with H. pylori is important in the etiology of gastric cancer. Gastric cancer is infrequent in Africa, despite high frequencies of H. pylori infection, referred to as the African enigma. Variation in environmental and host factors influencing gastric cancer risk between different populations have been reported but little is known about the biological differences between gastric cancers from different geographic locations. We aim to study genomic instability patterns of gastric cancers obtained from patients from United Kingdom (UK) and South Africa (SA), in an attempt to support the African enigma hypothesis at the biological level.Methods
DNA was isolated from 67 gastric adenocarcinomas, 33 UK patients, 9 Caucasian SA patients and 25 native SA patients. Microsatellite instability and chromosomal instability were analyzed by PCR and microarray comparative genomic hybridization, respectively. Data was analyzed by supervised univariate and multivariate analyses as well as unsupervised hierarchical cluster analysis.Results
Tumors from Caucasian and native SA patients showed significantly more microsatellite instable tumors (p < 0.05). For the microsatellite stable tumors, geographical origin of the patients correlated with cluster membership, derived from unsupervised hierarchical cluster analysis (p = 0.001). Several chromosomal alterations showed significantly different frequencies in tumors from UK patients and native SA patients, but not between UK and Caucasian SA patients and between native and Caucasian SA patients.Conclusions
Gastric cancers from SA and UK patients show differences in genetic instability patterns, indicating possible different biological mechanisms in patients from different geographical origin. This is of future clinical relevance for stratification of gastric cancer therapy.33.
Positive selection driving the evolution of a gene of male reproduction, Acp26Aa, of Drosophila: II. Divergence versus polymorphism 总被引:5,自引:1,他引:4
The evolution of the gene for a male ejaculatory protein, Acp26Aa, has been
shown to be driven by positive selection when nonsibling species in the
Drosophila melanogaster subgroup are compared. To know if selection has
been operating in the recent past and to understand the details of its
dynamics, we obtained DNA sequences of Acp26Aa and the nearby Acp26Ab gene
from 39 D. melanogaster chromosomes. Together with the 10 published
sequences, we analyzed 49 sequences from five populations in four
continents. The southern African population is somewhat differentiated from
all other populations, but its nucleotide diversity is lower at these two
loci. We find the following results for Acp26Aa: (1) The R: S (replacement
: silent changes) ratio is significantly higher in the between-species
comparisons than in the within-species data by the McDonald and Kreitman
test. Positive selection is probably responsible for the excess of amino
acid replacements between species. (2) However, within-species nucleotide
diversity is high. Neither the Tajima test nor the Fu and Li test indicates
a reduction in nucleotide diversity due to positive selection in the recent
past. (3) The newly derived nucleotides in D. melanogaster are at high
frequency significantly more often than predicted by the neutral
equilibrium. Since the nearby Acp26Ab gene does not show these patterns,
these observations cannot be attributed to the characteristics of this
chromosomal region. We suggest that positive selection is active, but may
be weak, for each amino acid change in the Acp26Aa gene.
相似文献
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Mitochondrial DNA (mtDNA) sequences that include (a) a part of the
cytochrome b gene, (b) two tRNA genes, and (c) a part of the noncoding
D-loop region of 31 Anguilla japonica (Japanese eel) and 1 A. marmorata
collected from Taiwan, Japan, and mainland China were determined to
evaluate the population structure of Japanese eel. Among 30 genotypes
identified from the 31 Japanese eel mtDNAs sequenced, there are 58 variable
sites, predominantly clustered at the D-loop region. The phylogenetic tree
constructed by the unweighted pair-group method with arithmetic mean shows
neither significant genealogical branches nor geographic clusters.
Furthermore, the sequence-statistics test reveals little, if any,
significant genetic differentiation. These results indicate that the 31
Japanese eels might come from a single population. Analysis of sequence
variation in mtDNA by using the relationship between the number of
segregating sites and the average number of nucleotide differences under
the neutral mutation hypothesis reveals that neutral mutation acts as a
major factor influencing the evolutionary divergence of the Japanese eel
mitochondrial genome sequenced, especially in the noncoding region.
相似文献
36.
膝关节挫伤的磁共振影像表现 总被引:1,自引:1,他引:0
目的 :探讨磁共振短时的反转恢复序列 (STIR)在膝关节骨挫伤中的临床应用。方法 :通过 32例膝关节外伤病例在常规SE序列、FSE序列和STIR序列中的影像表现 ,分析STIR序列的优越性。结果 :32例共 45个骨挫伤病灶 ,T1W发现 38个 (占 84% ) ,T2W发现 37个 (占 82 % ) ,STIR序列病灶全部显示( 1 0 0 % )。结论 :STIR序列对骨挫伤的敏感性较高 ,能显示微小的骨髓水肿 ,充血及骨小梁的微骨折及其周围的骨软骨、关节囊的细微变化 ,对膝关节外伤具有较高价值。 相似文献
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Vidya P. Nair Saumya Anang Chandru Subramani Abhilasha Madhvi Karishma Bakshi Akriti Srivastava Shalimar Baibaswata Nayak Ranjith Kumar CT Milan Surjit 《PLoS pathogens》2016,12(4)
Hepatitis E virus (HEV) causes acute hepatitis in many parts of the world including Asia, Africa and Latin America. Though self-limiting in normal individuals, it results in ~30% mortality in infected pregnant women. It has also been reported to cause acute and chronic hepatitis in organ transplant patients. Of the seven viral genotypes, genotype-1 virus infects humans and is a major public health concern in South Asian countries. Sporadic cases of genotype-3 and 4 infection in human and animals such as pigs, deer, mongeese have been reported primarily from industrialized countries. Genotype-5, 6 and 7 viruses are known to infect animals such as wild boar and camel, respectively. Genotype-3 and 4 viruses have been successfully propagated in the laboratory in mammalian cell culture. However, genotype-1 virus replicates poorly in mammalian cell culture and no other efficient model exists to study its life cycle. Here, we report that endoplasmic reticulum (ER) stress promotes genotype-1 HEV replication by inducing cap-independent, internal initiation mediated translation of a novel viral protein (named ORF4). Importantly, ORF4 expression and stimulatory effect of ER stress inducers on viral replication is specific to genotype-1. ORF4 protein sequence is mostly conserved among genotype-1 HEV isolates and ORF4 specific antibodies were detected in genotype-1 HEV patient serum. ORF4 interacted with multiple viral and host proteins and assembled a protein complex consisting of viral helicase, RNA dependent RNA polymerase (RdRp), X, host eEF1α1 (eukaryotic elongation factor 1 isoform-1) and tubulinβ. In association with eEF1α1, ORF4 stimulated viral RdRp activity. Furthermore, human hepatoma cells that stably express ORF4 or engineered proteasome resistant ORF4 mutant genome permitted enhanced viral replication. These findings reveal a positive role of ER stress in promoting genotype-1 HEV replication and pave the way towards development of an efficient model of the virus. 相似文献
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Noviandi CT Razzazi E Agus A Böhm J Hulan HW Wedhastri S Maryudhani YB Nuryono Sardjono Leibetseder J 《Mycotoxin Research》2001,17(2):174-177
A survey was conducted between 1998–1999 to evaluate the level of aflatoxin B1 (AfB1) contamination in some selected Indonesian food products, mainly peanuts and peanut products for sale in supermarkets or traditional markets in Yogyakarta, Indonesia. Quantitative analysis was carried out on 118 samples using the ELISA (Enzyme-Linked Immunosorbent Assay) technique. The results indicate that (61.1%) samples were contaminated with AfB1 at range 2.0 to 249.0 μg/kg. Approximately 50% of the baby food products analysed were contaminated with AfB1 and the maximum level found was 7.0 μg/kg. In corn products and fermented products, AfB1 was detected in 66.7 and 50.0% of samples, respectively. A level as high as 5.6 μg/kg of AfB1 was found in the corn and 6.0 μg/kg in fermented product. AfB1 was also detected in all rice products, feed products, and other processed products at levels of up to 7.0, 27.0, and 26.0 μg/kg, respectively. 相似文献