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排序方式: 共有127条查询结果,搜索用时 15 毫秒
1.
2.
Sampling properties of DNA sequence data in phylogenetic analysis 总被引:26,自引:6,他引:20
We inferred phylogenetic trees from individual genes and random samples of
nucleotides from the mitochondrial genomes of 10 vertebrates and compared
the results to those obtained by analyzing the whole genomes. Individual
genes are poor samples in that they infrequently lead to the whole-genome
tree. A large number of nucleotide sites is needed to exactly determine the
whole-genome tree. A relatively small number of sites, however, often
results in a tree close to the whole-genome tree. We found that blocks of
contiguous sites were less likely to lead to the whole-genome tree than
samples composed of sites drawn individually from throughout the genome.
Samples of contiguous sites are not representative of the entire genome, a
condition that violates a basic assumption of the bootstrap method as it is
applied in phylogenetic studies.
相似文献
3.
The behavior of mammalian phosphofructokinase on immobilized adenine nucleotides was investigated. Three different insolubilized ligands were compared using a pure rabbit muscle phosphofructokinase. N6-[(6-aminohexyl)-carbamoyl-methyl]-ATP-Sepharose bound at least 90 times more enzyme than either N6-(6-aminohexyl)-AMP-agarose or ATP-adipic acid hydrazide-Sepharose. The elution of phosphofructokinase from the ATP-Sepharose with various metabolites and combinations of metabolites was investigated. The enzyme is eluted specifically from N6-[(6-aminohexyl)-carbamoyl]-ATP-Sepharose with a mixture of 25 μm each of fructose 6-phosphate and ADP (±Mg2+). The enzyme is not eluted either with ATP (25 μm), fructose 1,6-diphosphate (1 mm), ADP (25 μm), fructose 6-phosphate (1 mm) alone, or with a mixture of fructose 1,6-diphosphate (25 μm) and ATP (25 μm). The recovery of bound enzyme was usually greater than 90%. A mixture of glucose 6-phosphate and ADP or a mixture of IDP and fructose 6-phosphate also elutes the enzyme, but the recovery with these eluants was only about 40%. It was concluded that the “dead-end” complex is the most effective in the elution. Using this method, phosphofructokinase has been prepared in an essentially homogeneous form from muscle and brain of rabbit and rat. The overall isolation procedure involves a high speed centrifugation of crude extracts which sediments phosphofructokinase as a pellet, followed with adsorption on N6-[(6-aminohexyl)-carbamoyl-methyl]-ATP-Sepharose and specific elution with the mixture of fructose 6-phosphate and ADP. 相似文献
4.
Respiratory Viruses Associated Hospitalization among Children Aged <5 Years in Bangladesh: 2010-2014
Nusrat Homaira Stephen P. Luby Kamal Hossain Kariul Islam Makhdum Ahmed Mustafizur Rahman Ziaur Rahman Repon C. Paul Mejbah Uddin Bhuiyan W. Abdullah Brooks Badrul Munir Sohel Kajal Chandra Banik Marc-Alain Widdowson Melisa Willby Mahmudur Rahman Joseph Bresee Katharine-Sturm Ramirez Eduardo Azziz-Baumgartner 《PloS one》2016,11(2)
Background
We combined hospital-based surveillance and health utilization survey data to estimate the incidence of respiratory viral infections associated hospitalization among children aged < 5 years in Bangladesh.Methods
Surveillance physicians collected respiratory specimens from children aged <5 years hospitalized with respiratory illness and residing in the primary hospital catchment areas. We tested respiratory specimens for respiratory syncytial virus, parainfluenza viruses, human metapneumovirus, influenza, adenovirus and rhinoviruses using rRT-PCR. During 2013, we conducted a health utilization survey in the primary catchment areas of the hospitals to determine the proportion of all hospitalizations for respiratory illness among children aged <5 years at the surveillance hospitals during the preceding 12 months. We estimated the respiratory virus-specific incidence of hospitalization by dividing the estimated number of hospitalized children with a laboratory confirmed infection with a respiratory virus by the population aged <5 years of the catchment areas and adjusted for the proportion of children who were hospitalized at the surveillance hospitals.Results
We estimated that the annual incidence per 1000 children (95% CI) of all cause associated respiratory hospitalization was 11.5 (10–12). The incidences per 1000 children (95% CI) per year for respiratory syncytial virus, parainfluenza, adenovirus, human metapneumovirus and influenza infections were 3(2–3), 0.5(0.4–0.8), 0.4 (0.3–0.6), 0.4 (0.3–0.6), and 0.4 (0.3–0.6) respectively. The incidences per 1000 children (95%CI) of rhinovirus-associated infections among hospitalized children were 5 (3–7), 2 (1–3), 1 (0.6–2), and 3 (2–4) in 2010, 2011, 2012 and 2013, respectively.Conclusion
Our data suggest that respiratory viruses are associated with a substantial burden of hospitalization in children aged <5 years in Bangladesh. 相似文献5.
John J. Openshaw Sonia Hegde Hossain M. S. Sazzad Salah Uddin Khan M. Jahangir Hossain Jonathan H. Epstein Peter Daszak Emily S. Gurley Stephen P. Luby 《EcoHealth》2016,13(1):39-48
We used data on feeding practices and domestic animal health gathered from 207 Bangladeshi villages to identify any association between grazing dropped fruit found on the ground or owners directly feeding bat- or bird-bitten fruit and animal health. We compared mortality and morbidity in domestic animals using a mixed effects model controlling for village clustering, herd size, and proxy measures of household wealth. Thirty percent of household heads reported that their animals grazed on dropped fruit and 20% reported that they actively fed bitten fruit to their domestic herds. Household heads allowing their cattle to graze on dropped fruit were more likely to report an illness within their herd (adjusted prevalence ratio 1.17, 95% CI 1.02–1.31). Household heads directly feeding goats bitten fruit were more likely to report illness (adjusted prevalence ratio 1.35, 95% CI 1.16–1.57) and deaths (adjusted prevalence ratio 1.64, 95% CI 1.13–2.4). Reporting of illnesses and deaths among goats rose as the frequency of feeding bitten fruit increased. One possible explanation for this finding is the transmission of bat pathogens to domestic animals via bitten fruit consumption. 相似文献
6.
BACKGROUND: Morbidity management is a core component of the global programme for the elimination of lymphatic filariasis. In a double-blind clinical trial, the tolerability and efficacy of Daflon (500 mg) + DEC (25 mg) or DEC (25 mg) alone, twice daily for 90 days, was studied in 26 patients with bancroftian filarial lymphoedema. RESULTS: None of the patients in either drug group reported any adverse reaction throughout the treatment period (90 days). Haematological and biochemical parameters were within normal limits and there was no significant difference between the pre-treatment (day 0) and post-treatment (day 90) values. The group receiving Daflon showed significant reduction in oedema volume from day 90 (140.6 PlusMinus; 18.8 ml) to day 360 (71.8 PlusMinus; 20.7 ml) compared to the pre-treatment (day 0, 198.4 PlusMinus; 16.5 ml) value. This accounted for a 63.8% reduction in oedema volume by day 360 (considering the pre-treatment (day 0) as 100%). In the DEC group, the changes in oedema volume (between day 1 and day 360) were not significant when compared to the pre-treatment (day 0) value. The percentage reduction at day 360 was only 9%, which was not significant (P > 0.05). CONCLUSION: This study has shown that Daflon (500 mg, twice a day for 90 days) is both safe and efficacious in reducing oedema volume in bancroftian filarial lymphoedema. Further clinical trials are essential for strengthening the evidence base on the role of this drug in the morbidity management of lymphatic filariasis. 相似文献
7.
8.
Background
Standard public health interventions to improve hand hygiene in communities with high levels of child mortality encourage community residents to wash their hands with soap at five separate key times, a recommendation that would require mothers living in impoverished households to typically wash hands with soap more than ten times per day. We analyzed data from households that received no intervention in a large prospective project evaluation to assess the relationship between observed handwashing behavior and subsequent diarrhea.Methods and Findings
Fieldworkers conducted a 5-hour structured observation and a cross-sectional survey in 347 households from 50 villages across rural Bangladesh in 2007. For the subsequent 2 years, a trained community resident visited each of the enrolled households every month and collected information on the occurrence of diarrhea in the preceding 48 hours among household residents under the age of 5 years. Compared with children living in households where persons prepared food without washing their hands, children living in households where the food preparer washed at least one hand with water only (odds ratio [OR] = 0.78; 95% confidence interval [CI] = 0.57–1.05), washed both hands with water only (OR = 0.67; 95% CI = 0.51–0.89), or washed at least one hand with soap (OR = 0.30; 95% CI = 0.19–0.47) had less diarrhea. In households where residents washed at least one hand with soap after defecation, children had less diarrhea (OR = 0.45; 95% CI = 0.26–0.77). There was no significant association between handwashing with or without soap before feeding a child, before eating, or after cleaning a child''s anus who defecated and subsequent child diarrhea.Conclusions
These observations suggest that handwashing before preparing food is a particularly important opportunity to prevent childhood diarrhea, and that handwashing with water alone can significantly reduce childhood diarrhea. Please see later in the article for the Editors'' Summary 相似文献9.
Background
Drinking raw date palm sap is a risk factor for human Nipah virus (NiV) infection. Fruit bats, the natural reservoir of NiV, commonly contaminate raw sap with saliva by licking date palm’s sap producing surface. We evaluated four types of physical barriers that may prevent bats from contacting sap.Methods
During 2009, we used a crossover design and randomly selected 20 date palm sap producing trees and observed each tree for 2 nights: one night with a bamboo skirt intervention applied and one night without the intervention. During 2010, we selected 120 trees and randomly assigned four types of interventions to 15 trees each: bamboo, dhoincha (local plant), jute stick and polythene skirts covering the shaved part, sap stream, tap and collection pot. We enrolled the remaining 60 trees as controls. We used motion sensor activated infrared cameras to examine bat contact with sap.Results
During 2009 bats contacted date palm sap in 85% of observation nights when no intervention was used compared with 35% of nights when the intervention was used [p<0.001]. Bats were able to contact the sap when the skirt did not entirely cover the sap producing surface. Therefore, in 2010 we requested the sap harvesters to use larger skirts. During 2010 bats contacted date palm sap [2% vs. 83%, p<0.001] less frequently in trees protected with skirts compared to control trees. No bats contacted sap in trees with bamboo (p<0.001 compared to control), dhoincha skirt (p<0.001) or polythene covering (p<0.001), but bats did contact sap during one night (7%) with the jute stick skirt (p<0.001).Conclusion
Bamboo, dhoincha, jute stick and polythene skirts covering the sap producing areas of a tree effectively prevented bat-sap contact. Community interventions should promote applying these skirts to prevent occasional Nipah spillovers to human. 相似文献10.
Nusrat Homaira Stephen P. Luby William A. Petri Raija Vainionpaa Mustafizur Rahman Kamal Hossain Cynthia B. Snider Mahmudur Rahman A. S. M. Alamgir Farzina Zesmin Masud Alam Emily S. Gurley Rashid Uz Zaman Tasnim Azim Dean D. Erdman Alicia M. Fry Joseph Bresee Marc-Alain Widdowson Rashidul Haque Eduardo Azziz-Baumgartner 《PloS one》2012,7(2)