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排序方式: 共有78条查询结果,搜索用时 15 毫秒
1.
Kim J. Brolin Ribacke Alex J. van Duinen Helena Nordenstedt Jonas H?ijer Ragnhild Molnes Torunn Wigum Froseth AP Koroma Elisabeth Darj H?kon Angel Bolkan AnnaMia Ekstr?m 《PloS one》2016,11(2)
Background
As Sierra Leone celebrates the end of the Ebola Virus Disease (EVD) outbreak, we can begin to fully grasp its impact on already weak health systems. The EVD outbreak in West Africa forced many hospitals to close down or reduce their activity, either to prevent nosocomial transmission or because of staff shortages. The aim of this study is to assess the potential impact of EVD on nationwide access to obstetric care in Sierra Leone.Methods and Findings
Community health officers collected weekly data between January 2014—May 2015 on in-hospital deliveries and caesarean sections (C-sections) from all open facilities (public, private for-profit and private non-profit sectors) offering emergency obstetrics in Sierra Leone. This was compared to official data of EVD cases per district. Logistic and Poisson regression analyses were used to compute risk and rate estimates. Nationwide, the number of in-hospital deliveries and C-sections decreased by over 20% during the EVD outbreak. The decline occurred early on in the EVD outbreak and was mainly attributable to the closing of private not-for-profit hospitals rather than government facilities. Due to difficulties in collecting data in the midst of an epidemic, limitations of this study include some missing data points.Conclusions
Both the number of in-hospital deliveries and C-sections substantially declined shortly after the onset of the EVD outbreak. Since access to emergency obstetric care, like C-sections, is associated with decreased maternal mortality, many women are likely to have died due to the reduced access to appropriate care during childbirth. Future research on indirect health effects of health system breakdown should ideally be nationwide and continue also into the recovery phase. It is also important to understand the mechanisms behind the deterioration so that important health services can be reestablished. 相似文献2.
There is marked heterogeneity of nucleotide composition in mitochondrial
DNA across divergent animals. Differences in nucleotide composition
presumably reflect differences in directional nucleotide substitution for
A+T or G+C nucleotides. In mitochondrial DNA, there is A+T directional
nucleotide substitution in most (if not all) animals surveyed, and the
magnitude of directional A+T nucleotide substitution differs greatly within
and among groups. Differences in directional nucleotide substitution among
lineages of mammals can be explained by changes in metabolic physiology.
This relationship is thought to be mediated by the effect of oxygen
radicals because these toxic compounds are by-products of aerobic
metabolism and are known mutagens. Association between metabolism and
nucleotide composition provides additional evidence in favor of the
hypothesis that rates and patterns of nucleotide substitution in
mitochondrial DNA can be influenced by factors that impinge on rates of
endogenous DNA damage.
相似文献
3.
Mitochondrial DNA sequence evolution in sharks: rates, patterns, and phylogenetic inferences 总被引:8,自引:0,他引:8
Abundant representation of sharks in the fossil record makes this group a
superb system in which to investigate rates and patterns of molecular
evolution and to explore the strengths and weaknesses of phylogenetic
inferences from molecular data. In this report, the molecular evolution of
the cytochrome b gene in sharks is described and the information related to
results from phylogenetic analysis of the data evaluated in the light of a
phylogeny derived independently of the molecular data. Across divergent
lineages of sharks there is evidence for significant substitution rate
variation, departure from compositional equilibrium, and substantial
homoplasy; nevertheless, the signal of evolutionary history is evident in
patterns of shared transversions and amino acid replacements.
相似文献
4.
Zhaohui Liu Jason D. Zurn Gayan Kariyawasam Justin D. Faris Gongjun Shi Jana Hansen Jack B. Rasmussen Maricelis Acevedo 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2017,130(6):1267-1276
Key message
Tan spot susceptibility is conferred by multiple interactions of necrotrophic effector and host sensitivity genes.Abstract
Tan spot of wheat, caused by Pyrenophora tritici-repentis, is an important disease in almost all wheat-growing areas of the world. The disease system is known to involve at least three fungal-produced necrotrophic effectors (NEs) that interact with the corresponding host sensitivity (S) genes in an inverse gene-for-gene manner to induce disease. However, it is unknown if the effects of these NE–S gene interactions contribute additively to the development of tan spot. In this work, we conducted disease evaluations using different races and quantitative trait loci (QTL) analysis in a wheat recombinant inbred line (RIL) population derived from a cross between two susceptible genotypes, LMPG-6 and PI 626573. The two parental lines each harbored a single known NE sensitivity gene with LMPG-6 having the Ptr ToxC sensitivity gene Tsc1 and PI 626573 having the Ptr ToxA sensitivity gene Tsn1. Transgressive segregation was observed in the population for all races. QTL mapping revealed that both loci (Tsn1 and Tsc1) were significantly associated with susceptibility to race 1 isolates, which produce both Ptr ToxA and Ptr ToxC, and the two genes contributed additively to tan spot susceptibility. For isolates of races 2 and 3, which produce only Ptr ToxA and Ptr ToxC, only Tsn1 and Tsc1 were associated with tan spot susceptibility, respectively. This work clearly demonstrates that tan spot susceptibility in this population is due primarily to two NE–S interactions. Breeders should remove both sensitivity genes from wheat lines to obtain high levels of tan spot resistance.5.
6.
The genome sequence of avian pathogenic Escherichia coli strain O1:K1:H7 shares strong similarities with human extraintestinal pathogenic E. coli genomes 下载免费PDF全文
Johnson TJ Kariyawasam S Wannemuehler Y Mangiamele P Johnson SJ Doetkott C Skyberg JA Lynne AM Johnson JR Nolan LK 《Journal of bacteriology》2007,189(8):3228-3236
Escherichia coli strains that cause disease outside the intestine are known as extraintestinal pathogenic E. coli (ExPEC) and include human uropathogenic E. coli (UPEC) and avian pathogenic E. coli (APEC). Regardless of host of origin, ExPEC strains share many traits. It has been suggested that these commonalities may enable APEC to cause disease in humans. Here, we begin to test the hypothesis that certain APEC strains possess potential to cause human urinary tract infection through virulence genotyping of 1,000 APEC and UPEC strains, generation of the first complete genomic sequence of an APEC (APEC O1:K1:H7) strain, and comparison of this genome to all available human ExPEC genomic sequences. The genomes of APEC O1 and three human UPEC strains were found to be remarkably similar, with only 4.5% of APEC O1's genome not found in other sequenced ExPEC genomes. Also, use of multilocus sequence typing showed that some of the sequenced human ExPEC strains were more like APEC O1 than other human ExPEC strains. This work provides evidence that at least some human and avian ExPEC strains are highly similar to one another, and it supports the possibility that a food-borne link between some APEC and UPEC strains exists. Future studies are necessary to assess the ability of APEC to overcome the hurdles necessary for such a food-borne transmission, and epidemiological studies are required to confirm that such a phenomenon actually occurs. 相似文献
7.
8.
The relationship between dental morphology, sex, body length and age of small cetaceans can be used to determine ontogeny, sexual dimorphism and geographical variation. The objective of this study was to determine the relationship between dental morphology, sex, body size and age. A total of 91 specimens of P. blainvillei and 80 specimens of S. fluviatilis accidentally captured in fisheries or stranded in northern Rio de Janeiro (21 masculine37'-22 masculine25'S), from September 1988 to November 1996 were analysed. The teeth root diameter in P. blainvillei was significantly different between the sex; the values for females were larger than males. In neither species aid we observed significant in variations dimension and number of teeth, thickness of dentine and cemental layers and in the maximum width of cement as a function of body size. Age was related to increases in tooth length, root and cingulum diameters, and maximum width of cement in individuals of P. blainvillei, and tooth and crown lengths and maximum width of cement in individuals of S. fluviatilis. The observation of a linear growth between maximum width of cement and age in both species indicates that the equations obtained can be used to estimate relative age in P. blainvillei and S. fluviatilis in northern of Rio de Janeiro. 相似文献
9.
Characterization of apelin, the ligand for the APJ receptor 总被引:36,自引:0,他引:36
Lee DK Cheng R Nguyen T Fan T Kariyawasam AP Liu Y Osmond DH George SR O'Dowd BF 《Journal of neurochemistry》2000,74(1):34-41
The apelin peptide was recently discovered and demonstrated to be the endogenous ligand for the G protein-coupled receptor, APJ. A search of the GenBank databases retrieved a rat expressed sequence tag partially encoding the preproapelin sequence. The GenBank search also revealed a human sequence on chromosome Xq25-26.1, containing the gene encoding preproapelin. We have used the rat sequence to screen a rat brain cDNA library to obtain a cDNA encoding the full-length open reading frame of rat preproapelin. This cDNA encoded a protein of 77 amino acids, sharing an identity of 82% with human preproapelin. Northern and in situ hybridization analyses revealed both human and rat apelin and APJ to be expressed in the brain and periphery. Both sequence and mRNA expression distribution analyses revealed similarities between apelin and angiotensin II, suggesting they that share related physiological roles. A synthetic apelin peptide was injected intravenously into male Wistar rats, resulting in immediate lowering of both systolic and diastolic blood pressure, which persisted for several minutes. Intraperitoneal apelin injections induced an increase in drinking behavior within the first 30 min after injection, with a return to baseline within 1 h. 相似文献
10.
Substitution rates of organelle and nuclear genes in sharks: implicating metabolic rate (again) 总被引:7,自引:4,他引:3
Rates of nucleotide substitution for nuclear genes are thought to be
governed primarily by the number of germ line replication events (the
so-called "generation time" hypothesis). In contrast, rates of
mitochondrial DNA evolution appear to be set primarily by DNA damage
pathways of mutation mediated by mutagenic by-products of oxidative
phosphorylation (the so-called "metabolic-rate" hypothesis). Comparison of
synonymous substitution rates estimated for the mitochondrial cytochrome b
gene and nuclear-encoded dlx, hsp70, and RAG-1 genes in mammals and sharks
shows that rates of molecular evolution for sharks are approximately an
order of magnitude slower than those for mammals for both nuclear and
mitochondrial genes. In addition, there is significant positive covariation
of substitution rate for mitochondrial and nuclear genes within sharks.
These results, interpreted in light of the pervasiveness of DNA damage by
mutagenic by-products of oxygen metabolism to both nuclear and
mitochondrial genes and coupled with increasing evidence for cross-genome
activity of DNA repair enzymes, suggest that molecular clocks for
mitochondrial and nuclear genes may be set primarily by common mutational
mechanisms.
相似文献