Positive selection driving the evolution of a gene of male reproduction, Acp26Aa, of Drosophila: II. Divergence versus polymorphism

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.      

Gastric cancers of Western European and African patients show different patterns of genomic instability

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.

     

The OPALS Major Trauma Study: impact of advanced life-support on survival and morbidity

Background

To date, the benefit of prehospital advanced life-support programs on trauma-related mortality and morbidity has not been established

Methods

The Ontario Prehospital Advanced Life Support (OPALS) Major Trauma Study was a before–after systemwide controlled clinical trial conducted in 17 cities. We enrolled adult patients who had experienced major trauma in a basic life-support phase and a subsequent advanced life-support phase (during which paramedics were able to perform endotracheal intubation and administer fluids and drugs intravenously). The primary outcome was survival to hospital discharge.

Results

Among the 2867 patients enrolled in the basic life-support (n = 1373) and advanced life-support (n = 1494) phases, characteristics were similar, including mean age (44.8 v. 47.5 years), frequency of blunt injury (92.0% v. 91.4%), median injury severity score (24 v. 22) and percentage of patients with Glasgow Coma Scale score less than 9 (27.2% v. 22.1%). Survival did not differ overall (81.1% among patients in the advanced life-support phase v. 81.8% among those in the basic life-support phase; p = 0.65). Among patients with Glasgow Coma Scale score less than 9, survival was lower among those in the advanced life-support phase (50.9% v. 60.0%; p = 0.02). The adjusted odds of death for the advanced life-support v. basic life-support phases were nonsignificant (1.2, 95% confidence interval 0.9–1.7; p = 0.16).

Interpretation

The OPALS Major Trauma Study showed that systemwide implementation of full advanced life-support programs did not decrease mortality or morbidity for major trauma patients. We also found that during the advanced life-support phase, mortality was greater among patients with Glasgow Coma Scale scores less than 9. We believe that emergency medical services should carefully re-evaluate the indications for and application of prehospital advanced life-support measures for patients who have experienced major trauma.Each year in the United States, an estimated 500 000 adult patients are transported to hospital after experiencing major trauma.^1,2 Major trauma can be described as life-or limb-threatening injury due to blunt force, penetrating injury or burn injury. Considering both frequency and associated mortality, major trauma is the second most important condition for children and the fourth most important condition for adults treated by emergency medical service providers.² About 20% of these patients die, and many survivors are left with permanent disability.Throughout most urban areas of the United States and Canada, paramedics provide prehospital advanced life-support to many of these critically injured patients. Advanced life-support protocols include advanced airway management (endotracheal intubation) and intravenous fluid therapy. In contrast, basic life-support providers administer oxygen, ventilate with a bag valve mask, and provide immobilization and dressings. The relative effectiveness of community-based advanced life-support programs for major trauma patients has not been clearly established, and there have been calls for larger and more rigorously designed studies.^3–5Endotracheal intubation in the field has not been proven to reduce mortality and morbidity among severely injured patients, and there are concerns that performing this difficult task under trying conditions may cause harm.^6,7 The value of prehospital intravenous resuscitation has also been questioned.^8,9 In addition, there are concerns that the on-scene time spent providing advanced life-support measures may actually delay life-saving expeditious transfer to the hospital and the operating room.¹⁰ To date, no large controlled clinical trials have been conducted to evaluate the impact of prehospital advanced life-support programs on trauma-related mortality and morbidity.³As part of the Ontario Prehospital Advanced Life Support (OPALS) studies, we recently demonstrated that advanced life-support programs had no impact on the outcomes of patients who had experienced cardiac arrest, but they did lead to significant improvement in survival among patients with respiratory distress.^11,12 The primary objective of the current study, the OPALS Major Trauma Study, was to assess any change in survival that might result from the systemwide introduction of prehospital advanced life-support programs in multiple cities with existing basic life-support programs provided through emergency medical services. We also evaluated the impact of advanced life-support on morbidity and processes of care.     

膝关节挫伤的磁共振影像表现

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。     

Population structure of the Japanese eel, Anguilla japonica

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.      

Natural occurrence of aflatoxin B<Subscript>1</Subscript> in some Indonesian food and feed products in Yogyakarta in year 1998–1999

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.