Length of carotid stenosis predicts peri-procedural stroke or death and restenosis in patients randomized to endovascular treatment or endarterectomy.

BACKGROUND: The anatomy of carotid stenosis may influence the outcome of endovascular treatment or carotid endarterectomy. Whether anatomy favors one treatment over the other in terms of safety or efficacy has not been investigated in randomized trials. METHODS: In 414 patients with mostly symptomatic carotid stenosis randomized to endovascular treatment (angioplasty or stenting; n = 213) or carotid endarterectomy (n = 211) in the Carotid and Vertebral Artery Transluminal Angioplasty Study (CAVATAS), the degree and length of stenosis and plaque surface irregularity were assessed on baseline intraarterial angiography. Outcome measures were stroke or death occurring between randomization and 30 days after treatment, and ipsilateral stroke and restenosis ≥50% during follow-up. RESULTS: Carotid stenosis longer than 0.65 times the common carotid artery diameter was associated with increased risk of peri-procedural stroke or death after both endovascular treatment [odds ratio 2.79 (1.17-6.65), P = 0.02] and carotid endarterectomy [2.43 (1.03-5.73), P = 0.04], and with increased long-term risk of restenosis in endovascular treatment [hazard ratio 1.68 (1.12-2.53), P = 0.01]. The excess in restenosis after endovascular treatment compared with carotid endarterectomy was significantly greater in patients with long stenosis than with short stenosis at baseline (interaction P = 0.003). Results remained significant after multivariate adjustment. No associations were found for degree of stenosis and plaque surface. CONCLUSIONS: Increasing stenosis length is an independent risk factor for peri-procedural stroke or death in endovascular treatment and carotid endarterectomy, without favoring one treatment over the other. However, the excess restenosis rate after endovascular treatment compared with carotid endarterectomy increases with longer stenosis at baseline. Stenosis length merits further investigation in carotid revascularisation trials

What can comparative genomics tell us about species concepts in the genus Aspergillus?

Understanding the nature of species” boundaries is a fundamental question in evolutionary biology. The availability of genomes from several species of the genus Aspergillus allows us for the first time to examine the demarcation of fungal species at the whole-genome level. Here, we examine four case studies, two of which involve intraspecific comparisons, whereas the other two deal with interspecific genomic comparisons between closely related species. These four comparisons reveal significant variation in the nature of species boundaries across Aspergillus. For example, comparisons between A. fumigatus and Neosartorya fischeri (the teleomorph of A. fischerianus) and between A. oryzae and A. flavus suggest that measures of sequence similarity and species-specific genes are significantly higher for the A. fumigatus - N. fischeri pair. Importantly, the values obtained from the comparison between A. oryzae and A. flavus are remarkably similar to those obtained from an intra-specific comparison of A. fumigatus strains, giving support to the proposal that A. oryzae represents a distinct ecotype of A. flavus and not a distinct species. We argue that genomic data can aid Aspergillus taxonomy by serving as a source of novel and unprecedented amounts of comparative data, as a resource for the development of additional diagnostic tools, and finally as a knowledge database about the biological differences between strains and species

Identification of resistanceassociated proteins in closelyrelated maize lines varying in aflatoxin accumulation

Aspergillus flavus infection of maize and subsequent contamination with carcinogenic aflatoxins poses serious health concerns, especially in developing countries. Maize lines resistant to A. flavus infection have been identified; however, the development of commercially-useful aflatoxin-resistant maize lines has been hindered due to a lack of breeding markers. To identify maize resistance-associated proteins (RAPs) as potential markers for breeding, 52 BC1S4 lines developed from crosses between five African maize inbreds and five temperate aflatoxin-resistant lines were screened using the kernel screening assay. Five pairs of closely-related lines that had 75–94% genetic similarity within each pair and which varied within each pair in aflatoxin accumulation were selected for proteomic investigation. Kernel embryo and endosperm protein profile differences within the pair and across pairs were compared using two-dimensional polyacrylamide gel electrophoresis. Differentially expressed (≥1.5-fold) RAPs were sequenced through tandem mass spectrometry and were identified as antifungal, stress-related, storage or regulatory proteins. Sequence homology analysis highlighted several proteins in maize that confer resistance to A. flavus infection and/or aflatoxin production

Using biotechnology to enhance host resistance to aflatoxin contaminiation of corn

Host resistance is the most widely explored strategy for eliminating aflatoxin contamination by Aspergillus flavus. Breeding strategies for developing resistant corn germplasm have been enhanced by the development of new screening tools for field inoculation and for laboratory screening. RFLP analysis of corn populations has highlighted the possibility that different resistance traits can be successfully pyramided into agronomically useful germplasm, while proteomics has impacted the identification of proteins associated with resistance (RAPs). The identification of RAPs has also been enhanced by the discovery of near-isogenic corn lines in progeny generated in a West African breeding program. The characterization of genes of the aflatoxin biosynthetic pathway has provided a foundation for a genomics investigation aimed at understanding the biochemical function and genetic regulation of aflatoxin biosynthesis. Successful inhibition of aflatoxin elaboration may require not only the action of antifungal compounds, but of compounds that block biosynthesis of toxins as well

Identifying aflatoxin resistance related proteins/genes through proteomics and RNAi gene silencing

Aflatoxins are carcinogenic secondary metab-olites produced mainly byAspergillus flavusLinkex. Fries, andA. prarasiticusSpeare duringinfection of susceptible crops, such as maize,cottonseed, peanuts and tree nuts. This paper willreview research efforts in identifying aflatoxinresistance-related proteins/genes in maize. Similarstrategies may be useful in peanut. For maize,although genotypes resistant toA. flavusinfectionor aflatoxin production have been identified, theincorporation of resistance into commercial lineshas been slow due to the lack of selectable markersand poor understanding of host resistance mech-anisms. Recently, resistance-associated proteins(RAPs) were identified through proteomic com-parison of constitutive protein profiles betweenresistant and susceptible maize genotypes. Theseproteins belong to three major groups based ontheir peptide sequence homologies: storage pro-teins, stress-related proteins, and antifungal pro-teins. Preliminary characterization of some ofthese RAPs suggest that they play a direct role inhost resistance, such as pathogenesis-relatedprotein 10 (PR10), or an indirect role, such asglyoxalase I (GLX I), through enhancing the hoststress tolerance. To verify whether these RAPsplay a role in host resistance, RNA interference(RNAi) gene silencing technique was used tosilence the expression of these genes in maize.RNAi vectors (glx IRNAi andpr10RNAi) wereconstructed using Gateway technology, and thentransformed into immature maize embryos usingboth bombardment andAgrobacteriuminfection.The extent of gene silencing in transgenic callustissues ranged from 20% to over 99%. The RNAisilenced transgenic maize seeds have also beenobtained from plants regenerated fromAgrobac-teriumtransformed callus lines. Kernel screenassay of the transgenic maize kernels demonstrat-ed a significant increase in susceptibility toA.flavuscolonization and aflatoxin production insome of the silenced transgenic lines comparedwith non-silenced control kernels, suggesting thedirect involvement of these two proteins inaflatoxin resistance in maize

Comparative proteomics of nearisogenic maize inbred lines to identify potential aflatoxinresistance markers

Several maize near-isogenic inbred lines were subjected to comparative proteomics to identify kernel proteins associated with resistance. These lines were developed in Nigeria through a joint project between ARS-SRRC and the International Institute of Tropical Agriculture. The goal of this project is to develop aflatoxin-resistant inbreds for use in Central and West African national programs and U.S. breeding programs to combat aflatoxincontamination of maize. Parental lines that produced these inbreds were U.S. aflatoxin-resistant lines crossed with Central and West African lines selected for moderate to high ear rot resistance. Lines were selfed and selected for foliar and ear rot resistances and for good agronomic characteristics until the S4 generation where selection began for aflatoxin accumulation using a laboratory-based kernel screening assay (KSA) and field trials. Recently, inbred lines developed through the above-protocol were re-examined with the KSA and near-isogenic lines varying significantly in aflatoxin accumulation were identified. These lines were subjected to comparative proteomics and differences in protein expression between these near-isogenics were identified and results are discussed

A USA Africa collaborative strategy for identifying, characterising and developing maize germplasm with resistance to aflatoxin contamination

Aflatoxin contamination of maize by Aspergillus flavus poses serious potential economic losses in the US and health hazards to humans, particularly in West Africa. The Southern Regional Research Center of the United States Department of Agriculture, Agricultural Research Service (USDA-ARS-SRRC) and the International Institute of Tropical Agriculture (IITA) initiated a collaborative breeding project to develop maize germplasm with resistance to aflatoxin accumulation. Resistant genotypes from the US and selected inbred lines from IITA were used to generate backcrosses with 75% US germplasm and F1 crosses with 50% IITA and 50% US germplasm. A total of 65 S4 lines were developed from the backcross populations and 144 S4 lines were derived from the F1 crosses. These lines were separated into groups and screened in SRRC laboratory using a kernel-screening assay. Significant differences in aflatoxin production were detected among the lines within each group. Several promising S4 lines with aflatoxin values significantly lower than their respective US resistant recurrent parent or their elite tropical inbred parent were selected for resistance-confirmation tests. We found pairs of S4 lines with 75–94% common genetic backgrounds differing significantly in aflatoxin accumulation. These pairs of lines are currently being used for proteome analysis to identify resistance-associated proteins and the corresponding genes underlying resistance to aflatoxin accumulation. Following confirmation tests in the laboratory, lines with consistently low aflatoxin levels will be inoculated with A. flavus in the field in Nigeria to identify lines resistant to strains specific to both US and West Africa. Maize inbred lines with desirable agronomic traits and low levels of aflatoxin in the field would be released as sources of genes for resistance to aflatoxin production