Alpha-toxin induces programmed cell death of human T cells, B cells, and monocytes during USA300 infection

This investigation examines the influence of alpha-toxin (Hla) during USA300 infection of human leukocytes. Survival of an USA300 isogenic deletion mutant of hla (USA300Δhla) in human blood was comparable to the parental wild-type strain and polymorphonuclear leukocyte (PMN) plasma membrane permeability caused by USA300 did not require Hla. Flow cytometry analysis of peripheral blood mononuclear cells (PBMCs) following infection by USA300, USA300Δhla, and USA300Δhla transformed with a plasmid over-expressing Hla (USA300Δhla Comp) demonstrated this toxin plays a significant role inducing plasma membrane permeability of CD14(+), CD3(+), and CD19(+) PBMCs. Rapid plasma membrane permeability independent of Hla was observed for PMNs, CD14(+) and CD19(+) PBMCs following intoxication with USA300 supernatant while the majority of CD3(+) PBMC plasma membrane permeability induced by USA300 required Hla. Addition of recombinant Hla to USA300Δhla supernatant rescued CD3(+) and CD19(+) PBMC plasma membrane permeability generated by USA300 supernatant. An observed delay in plasma membrane permeability caused by Hla in conjunction with Annexin V binding and ApoBrdU Tunel assays examining PBMCs intoxicated with recombinant Hla or infected with USA300, USA300Δhla, USA300Δhla Comp, and USA300ΔsaeR/S suggest Hla induces programmed cell death of monocytes, B cells, and T cells that results in plasma membrane permeability. Together these findings underscore the importance of Hla during S. aureus infection of human tissue and specifically demonstrate Hla activity during USA300 infection triggers programmed cell death of human monocytes, T cells and B cells that leads to plasma membrane permeability.     

A regulatory interaction between pyrimidine and purine biosyntheses via ureidosuccinic acid

Summary l-Ureidosuccinic acid (USA), an intermediate metabolite of pyrimidine biosynthesis, inhibits cell growth. Mutants blocked in pyrimidine biosynthesis after dihydroorotate (DHO), are more resistant to USA than are the wild type and the mutants blocked in the synthesis of DHO. This difference in sensitivity correlates with the level of dihydroorotase activity. Purines revert USA inhibition. Mutants selected for their resistance to USA were resistant because of a) overproducing purines (adenine excretion), b) having a reduced USA uptake, or c) showing a USA resistance independant of the above phenotypes.     

Genetic Variation in Spatio-Temporal Confined USA300 Community-Associated MRSA Isolates: A Shift from Clonal Dispersion to Genetic Evolution?

Introduction

Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) are increasingly isolated, with USA300-0114 being the predominant clone in the USA. Comparative whole genome sequencing of USA300 isolates collected in 2002, 2003 and 2005 showed a limited number of single nucleotide polymorphisms and regions of difference. This suggests that USA300 has undergone rapid clonal expansion without great genomic diversification. However, whole genome comparison of CA-MRSA has been limited to isolates belonging to USA300. The aim of this study was to compare the genetic repertoire of different CA-MRSA clones with that of HA-MRSA from the USA and Europe through comparative genomic hybridization (CGH) to identify genetic clues that may explain the successful and rapid emergence of CA-MRSA.

Materials and Methods

Hierarchical clustering based on CGH of 48 MRSA isolates from the community and nosocomial infections from Europe and the USA revealed dispersed clustering of the 19 CA-MRSA isolates. This means that these 19 CA-MRSA isolates do not share a unique genetic make-up. Only the PVL genes were commonly present in all CA-MRSA isolates. However, 10 genes were variably present among 14 USA300 isolates. Most of these genes were present on mobile elements.

Conclusion

The genetic variation present among the 14 USA300 isolates is remarkable considering the fact that the isolates were recovered within one month and originated from a confined geographic area, suggesting continuous evolution of this clone.     

Assessment of clinical pathology and pathogen exposure in sea otters (Enhydra lutris) bordering the threatened population in Alaska

Northern sea otter (Enhydra lutris kenyoni) abundance has decreased dramatically over portions of southwest Alaska, USA, since the mid-1980s, and this stock is currently listed as threatened under the Endangered Species Act. In contrast, adjacent populations in south central Alaska, USA, and Russia have been stable to increasing during the same period. Sea otters bordering the area classified in the recent decline were live-captured during 2004-2006 at Bering Island, Russia, and the Kodiak Archipelago, Alaska, USA, to evaluate differences in general health and current exposure status to marine and terrestrial pathogens. Although body condition was lower in animals captured at Bering Island, Russia, than it was at Kodiak, USA, clinical pathology values did not reveal differences in general health between the two regions. Low prevalences of antibodies (<5%) were found in Kodiak, USA, and on Bering Island, Russia, to Toxoplasma gondii, Sarcocystis neurona, and Leptospira interrogans. Exposure to phocine herpesvirus-1 was found in both Kodiak, USA (15.2%), and Bering Island, Russia (2.3%). Antibodies to Brucella spp. were found in 28% of the otters tested on Bering Island, Russia, compared with only 2.7% of the samples from Kodiak, USA. Prevalence of exposure to Phocine distemper virus (PDV) was 41% in Kodiak, USA, but 0% on Bering Island, Russia. Archived sera from southwest and south-central Alaska dating back to 1989 were negative for PDV, indicating exposure occurred in sea otters in Kodiak, USA, in recent years. Because PDV can be highly pathogenic in na?ve and susceptible marine mammal populations, tissues should be examined to explore the contribution of this virus to otter deaths. Our results reveal an increase in exposure to pathogens in sea otters in Kodiak, Alaska, USA, since the 1990 s.     

Isolations from the redbay ambrosia beetle, Xyleborus glabratus, confirm that the laurel wilt pathogen, Raffaelea lauricola, originated in Asia

The laurel wilt pathogen Raffaelea lauricola was hypothesized to have been introduced to the southeastern USA in the mycangium of the redbay ambrosia beetle, Xyleborus glabratus, which is native to Asia. To test this hypothesis adult X. glabratus were trapped in Taiwan and on Kyushu Island, Japan, in 2009, and dead beetles were sent to USA for isolation of fungal symbionts. Individual X. glabratus were macerated in glass tissue grinders, and the slurry was serially diluted and plated onto malt agar medium amended with cycloheximide, a medium semiselective for Ophiostoma species and their anamorphs, including members of Raffaelea. R. lauricola was isolated from 56 of 85 beetles in Taiwan and 10 of 16 beetles in Japan at up to an estimated 10 000 CFUs per beetle. The next most commonly isolated species was R. ellipticospora, which also has been recovered from X. glabratus trapped in the USA, as were two other fungi isolated from beetles in Taiwan, R. fusca and R. subfusca. Three unidentified Raffaelea spp. and three unidentified Ophiostoma spp. were isolated rarely from X. glabratus collected in Taiwan. Isolations from beetles similarly trapped in Georgia, USA, yielded R. lauricola and R. ellipticospora in numbers similar to those from beetles trapped in Taiwan and Japan. The results support the hypothesis that R. lauricola was introduced into the USA in mycangia of X. glabratus shipped to USA in solid wood packing material from Asia. However differences in the mycangial mycoflora of X. glabratus in Taiwan, Japan and USA suggest that the X. glabratus population established in USA originated in another part of Asia.     

Invaded range of the blackberry pathogen Phragmidium violaceum in the Pacific Northwest of the USA and the search for its provenance

Field surveys in 2006 confirmed that the exotic rust fungus Phragmidium violaceum was widespread on Rubus armeniacus and Rubus laciniatus in the Pacific Northwest of the USA. The origin and dispersal pattern of this obligate biotrophic pathogen in the USA were investigated by comparing the genetic diversity and structure of 27 isolates each from the USA and Europe, and 20 isolates from Australia where an invasion occurred in 1984. Analysis of 11 microsatellite loci revealed 74 unique genotypes, with the European population having a significantly higher level of allelic diversity and number of private alleles compared to populations from the USA and Australia. Principal coordinate analysis (PCA), analysis of molecular variance and pairwise comparisons of Φ confirmed a strong level of differentiation among continental populations, with little divergence between isolates from the USA and Europe, but a high level of differentiation between these isolates and those from Australia. These results were broadly supported by the Bayesian cluster analysis, which indicated that at K = 3 the clustering of the isolates corresponds to their geographic origin. Bayesian clustering, PCA as well as insignificant migration estimates from Europe to the USA suggest that the USA population is not a direct descendant from the European P. violaceum population. There was a weak association between genetic and geographic distance among the USA isolates, suggesting invasion was initially localized prior to dispersal or that the population may have been present for some time prior to first detection in 2005.     

International migration,the economic crisis and the state: An analysis of Mediterranean migration to Western Europe

This article deals with the experience of German minorities in Britain and the USA during World War I. The introductory section points to the fact that serious racial persecutions have taken place during total war in the twentieth century. The subsequent sections detail the experience of Germans in the USA and Britain respectively, pointing to the development of ethnic groups before 1914 and moving on to demonstrate the persecution that they faced from governments and public opinion in both countries. The conclusion compares the wartime experience of Germans in Britain and the USA, and suggests that in terms of strength of hostility, British and US treatment of enemy aliens remains similar. The main difference concerns the much smaller number of Germans in Britain and the greater ethnic diversity of the USA. These two factors, especially the former, meant that the British government could deal with its German population more thoroughly than could the Wilson administration in the USA.     

近30年来中美生态系统服务研究热点对比分析——基于文献计量研究

近年来生态系统服务研究已经成为了生态学、地理学及环境科学领域的热点和核心议题。基于SCI-E和CNKI数据库,运用文献计量和文本分析法对比了中美两国生态系统服务研究现状和热点。结果表明:(1)近30年来中美两国生态系统服务领域的发文量分别是9327篇和9468篇,均呈现快速增长趋势。(2)就中美两国发文篇均被引频次和总被引频次而言,中国科学院生态环境研究中心和斯坦福大学分别位列第1。美国刊发生态系统服务研究文稿最多的期刊是Ecological Economics,PNAS刊发的文章引用率最高;生态学报刊发的中文文章最多且被引用率最高。研究成果影响力最大的中美两国学者分别是欧阳志云、傅伯杰、Kremen C和Polasky S等。(3)不同时期中美两国所关注的研究热点不同。美国作为生态系统服务研究的主要发源地,在理论研究和方法上都相对领先于中国。(4)美国的研究侧重于理论与模型构建,中国的基础应用研究成果丰富。近年来两国越来越关注人类福祉、生态安全等全球性问题,生态系统服务与人类福祉及科学决策正成为新的热点。在全球可持续发展的背景下,两国在生态系统服务研究方面具有良好的交流与合作前景。     

Characterization of Whitney's Clethrionomy gapperi virus isolates from Massachusetts.

Six strains of virus were recovered from the blood and/or liver of five Clethrionomys gapperi ochraceus trapped in southeastern Massachusetts during 1969. Biological, antigenic and physiochemical properties of these isolates are reported. USA M-2268a was selected as the reference strain. This strain was identical by complement-fixation and neutralization tests to Whitneys C. gapperie virus (USA 64-7855) from New York State and was related to, but distinct from, an unpublished agent (Johnson's Microtus montanus enterovirus USA M-1146) isolated in June, 1962 from voles trapped in Klamath County, Oregon. USA M-2268a was resistant to lipid solvents and acid pH and was stable at temperatures of 4 C, 22 C, and 37 C. Virus was detected over a 10-day observation period in four species of mosquitoes inoculated with USA M-2268a, although there was no evidence of infection or replication, and transmission attempts by bite failed. Neutralizing antibody was detected in C.g. gapperi and C. g. ochraceus in various habitats throughout the state.     

The role of parasite release in invasion of the USA by European slugs

Several species of European slugs are invasive in the USA, threatening native species and damaging agricultural and horticultural crops. One possible explanation for the success of these invaders is parasite release. To test this hypothesis we collected European slugs in part of their native range (United Kingdom) and in the USA and compared prevalence, distribution and species richness of their nematode parasites. All slugs were dissected and examined for the presence of nematodes. In the UK, nematodes were present at 93% of study sites and 16.4% of all slugs examined were associated with nematodes whereas in the USA the respective figures were 34% of sites and 5.4% of slugs. Nematode species richness was greater in the UK with 12 species being found, seven of which were thought to be truly parasitic as opposed to being phoretic or necromenic. Nine species of nematode were found in the USA, four of which were truly parasitic. Four of the ten European slug species examined in the USA, were entirely free of truly parasitic nematodes whereas all were infected by nematodes in some sites in the UK. There was a significant difference in the prevalence of truly parasitic nematodes in five of these species when comparing their home versus invasive range. A significant difference in parasite prevalence was observed when comparing native and introduced slug species in the USA, however, this was not significant in the UK. Our data support a role for parasite release during the invasion of the USA by European slugs.     

保存大豆种质遗传完整性的策略:Ⅰ细化表型分级标准精细整理大豆库存种质

以中国大豆种质资源在美国的种植调查数据为资料,并与中国的调查数据进行比较,旨在研究大豆种质的遗传完整性,为中国大豆资源的繁种保存策略提供参考。中国大豆种质资源2093份在美国利用不同的调查标准进行农艺性状重新鉴定评价,30%的中国大豆种质资源可进一步分为不同的纯系,使种质的数量增加到3062份。以纯化后种质份数增加到9份的资源ZDD4572为例,对其纯化过程进行了详细分析。研究表明,现有的大豆资源在纯合保存前提下,用更多的评价性状、每个性状划分更多的等级,将有助于大豆种质资源的纯化及其数量的增加,从而更方便繁种和实际利用。     

Deferoxamine mesylate enhances virulence of community-associated methicillin resistant Staphylococcus aureus

Staphylococcus aureus is a leading cause of bacterial infections. Strains of community-associated methicillin-resistant S. aureus (CA-MRSA), such as USA300, display enhanced virulence and fitness. Patients suffering from iron overload diseases often undergo iron chelation therapy with deferoxamine mesylate (DFO). Here, we show that USA300 uses this drug to acquire iron. We further demonstrate that mice administered DFO I.P., versus those not administered DFO, had significantly higher bacterial burden in livers and kidneys after I.V. challenge with USA300, associated with increased abscess formation and tissue destruction. The virulence of USA300 mutants defective for DFO uptake was not affected by DFO treatment.     

Return migration and economic turmoil: experiences of repatriated Chinese professionals in Shanghai, China

From 2007, the economic turmoil in the USA has had a dramatic impact on immigrant populations living within the nation’s borders. One such group is Chinese migrants who came to the USA as students in the 1980s and 1990s. This paper focuses on a segment of this population—medical professionals—who obtained graduate degrees in the USA and subsequently stayed on to work in pharmaceutical or health industries in Philadelphia’s metropolitan area. As a result of the economic crises in the USA and also the burgeoning market in China, pharmaceutical companies have begun to repatriate some of these Chinese professionals. This paper will examine reflections on the return experience to Shanghai, which has developed rapidly to become the most commercialized modern city in China as a result of the market reform initiated in 1979. I argue that neoliberal ideology in the USA not only forces these Chinese immigrants back to China, but also challenges their concepts of identity and citizenship, including cultural citizenship. This paper also examines the ways in which processes of change are affected by global capitalism and neoliberalism.     

Identification of a Novel Staphylococcus aureus Two-Component Leukotoxin Using Cell Surface Proteomics

Staphylococcus aureus is a prominent human pathogen and leading cause of bacterial infection in hospitals and the community. Community-associated methicillin-resistant S. aureus (CA-MRSA) strains such as USA300 are highly virulent and, unlike hospital strains, often cause disease in otherwise healthy individuals. The enhanced virulence of CA-MRSA is based in part on increased ability to produce high levels of secreted molecules that facilitate evasion of the innate immune response. Although progress has been made, the factors that contribute to CA-MRSA virulence are incompletely defined. We analyzed the cell surface proteome (surfome) of USA300 strain LAC to better understand extracellular factors that contribute to the enhanced virulence phenotype. A total of 113 identified proteins were associated with the surface of USA300 during the late-exponential phase of growth in vitro. Protein A was the most abundant surface molecule of USA300, as indicated by combined Mascot score following analysis of peptides by tandem mass spectrometry. Unexpectedly, we identified a previously uncharacterized two-component leukotoxin–herein named LukS-H and LukF-G (LukGH)-as two of the most abundant surface-associated proteins of USA300. Rabbit antibody specific for LukG indicated it was also freely secreted by USA300 into culture media. We used wild-type and isogenic lukGH deletion strains of USA300 in combination with human PMN pore formation and lysis assays to identify this molecule as a leukotoxin. Moreover, LukGH synergized with PVL to enhance lysis of human PMNs in vitro, and contributed to lysis of PMNs after phagocytosis. We conclude LukGH is a novel two-component leukotoxin with cytolytic activity toward neutrophils, and thus potentially contributes to S. aureus virulence.     

Palaeozoic oolitic ironstones on the North American Craton

More than 40 mostly minor Palaeozoic oolitic ironstones (OI) accumulated on low-latitude cratonic North America, almost entirely in USA. A few Middle Cambrian OI, among the oldest anywhere, were deposited on the western cratonic shelf of USA. Widely scattered Late Cambrian ones developed on the southwestern, southeastern and northeastern flanks of the Transcontinental Arch. Middle Ordovician OI were deposited on the cratonic interior and on the southern and southeastern cratonic margins. In latest Ordovician time Neda OI spread across north-central USA east of the Arch and south of the Laurentian upland. Minor ones developed in the southern part of the Taconian foreland basin after major orogeny. Early and Middle Silurian Clinton OI flourished throughout the foreland basin in eastern USA, producing the largest OI deposit on the North American craton. Minor early Late Silurian OI accumulated in the central part of the basin. Middle and Late Devonian OI in the Acadian foreland basin in northeastern cratonic USA developed progressively westward of the encroaching Catskill delta. An isolated Middle Devonian one accumulated in southwestern cratonic USA, and latest Devonian ones in north-central USA east of the Arch.

During this Palaeozoic episode sites of OI deposition shifted eastward across the craton. Most of the OI were deposited during a hiatus in normal sedimentation, accumulating in the upper part of shoaling-upward sequences. Some early Palaeozoic ones occur in glauconitic siliciclastic-carbonate facies and contain mostly spherical hematitic ooids. These suggest derivation from iron-rich soils developed on glauconitic deposits. OI in wholly siliciclastic facies, containing distorted chamositic ooids with cores of mud peloids, were common in later Palaeozoic time. These OI, like many other Phanerozoic ones, suggest a synsedimentary to early diagenetic origin.     

Diversity of Methicillin-Resistant Staphylococcus aureus (MRSA) Strains Isolated from Inpatients of 30 Hospitals in Orange County,California

There is a need for a regional assessment of the frequency and diversity of MRSA to determine major circulating clones and the extent to which community and healthcare MRSA reservoirs have mixed. We conducted a prospective cohort study of inpatients in Orange County, California, systematically collecting clinical MRSA isolates from 30 hospitals, to assess MRSA diversity and distribution. All isolates were characterized by spa typing, with selective PFGE and MLST to relate spa types with major MRSA clones. We collected 2,246 MRSA isolates from hospital inpatients. This translated to 91/10,000 inpatients with MRSA and an Orange County population estimate of MRSA inpatient clinical cultures of 86/100,000 people. spa type genetic diversity was heterogeneous between hospitals, and relatively high overall (72%). USA300 (t008/ST8), USA100 (t002/ST5) and a previously reported USA100 variant (t242/ST5) were the dominant clones across all Orange County hospitals, representing 83% of isolates. Fifteen hospitals isolated more t008 (USA300) isolates than t002/242 (USA100) isolates, and 12 hospitals isolated more t242 isolates than t002 isolates. The majority of isolates were imported into hospitals. Community-based infection control strategies may still be helpful in stemming the influx of traditionally community-associated strains, particularly USA300, into the healthcare setting.     

Comparative study of scientific publications in urology and nephrology journals originating from USA, china and Japan (2001-2010)

Background

In the past decade, scientific research has developed rapidly in China, but the growth seems to vary widely between different disciplines. In this study, we aimed to compare the quantity and quality of publications in urology and nephrology journals from USA, China and Japan.

Methods

Journals listed in the “Urology and Nephrology” category of Science Citation Index Expanded subject categories were included. Scientific papers in these journals written by researchers from USA, Japan and China were retrieved from the “PubMed” and “Web of Knowledge” online databases.

Results

The annual number of total scientific articles increased significantly from 2001 to 2010 in China, and has ranked second in the world since 2006. In the field of urology and nephrology, the annual number increased significantly from 2001 to 2010 in USA and China; but not in Japan. The share of articles increased significantly over time in China, decreased significantly in Japan, and remained unchanged in USA. In 2010, USA contributed 32.17% of the total world output in urology and nephrology field and ranked 1^st; Japan contributed 5.19% and ranked 5^th; China contributed 3.83% and ranked 9^th. Publications from USA had the highest accumulated IFs and the highest total citations of articles (USA>Japan>China, p<0.001). No significant difference was found in average IF among the three countries. USA published the most articles in the top 10 urology and nephrology journals (USA(35165)>Japan(6704)>China(2233), p<0.001). Researchers from USA published more clinical trials and randomized controlled trials than Japan and China (USA>Japan>China, p<0.001).

Conclusion

Although China has undergone significant increase in annual number and percentage of scientific publication in urology and nephrology journals in the past decade, it still lags far behind USA and Japan in the field of urology and nephrology in terms of quantity and quality.     

Evolution of host- and habitat association in the wood-feeding cockroach, Cryptocercus

Members of the cockroach genus Cryptocercus are subsocial insects that live in temperate forests and feed on decomposing logs. At present, seven species are recognized worldwide: four in the eastern USA, one in the western USA, and one each in Russia and China. Genetic variation within and among the Nearctic species has been characterized extensively in previous studies. However, whether there has been a corresponding divergence in the host and habitat association of Cryptocercus species is not known. Here, we report on differences in host and habitat association among six of the seven Cryptocercus species, estimated from field observations, elevation data, and land cover data. Our results indicated that the eastern and western USA species differ from one another in their distribution patterns, abundance, and habitat association. The eastern USA species are associated largely with deciduous forests, whereas the western USA and the Russian species are associated with evergreen forests. Thus, the eastern USA species, which are evolutionarily the most recent ones, have adapted to a different set of tree species relative to the basal species. There were also differences in the habitat association of the various species. Specifically, in the eastern USA, Cryptocercus darwini , evolutionarily the most recent species, occupied a habitat that is predominantly at low elevation [<400 m above sea level (ASL)] while all the other Nearctic species and the Russian species occupied a habitat that is at relatively higher elevations (>400 m ASL). Mapping of the above traits on a phylogenetic tree revealed that the evolutionary trend in Cryptocercus with regard to host and habitat association has been toward the utilization of low elevation habitats dominated by deciduous forests. © 2002 The Linnean Society of London, Biological Journal of the Linnean Society , 2002, 75 , 163–172.