bluuebunny/crossref_metadata_2025_split huggingface dataset:
Antimicrobial resistance in livestock
Authors: Catry B. , Laevens H. , Devriese L.A. , Opsomer G. , de Kruif A. 
Published: December 2004

Antimicrobial resistance may become a major problem in veterinary medicine as a consequence of the intensive use and misuse of antimicrobial drugs. Related problems are now arising in human medicine, such as the appearance of multi‐resistant food‐borne pathogens. Product characteristics, dose, treatment interval and duration of treatment influence the selection pressure for antimicrobial drug resistance. There are theoretical, experimental and clinical indications that the emergence of de novo resistance in a pathogenic population can be prevented by minimizing the time that suboptimal drug levels are present in the infected tissue compartment.Until recently, attention has been focused on target pathogens. However, it should be kept in mind that when antimicrobial drugs are used in an individual, resistance selection mainly affects the normal body flora. In the long term, this is at least equally important as resistance selection in the target pathogens, as the horizontal transfer of resistance genes converts almost all pathogenic bacteria into potential recipients for antimicrobial resistance. Other factors contributing to the epidemiology of antimicrobial resistance are the localization and size of the microbial population, and the age, immunity and contact intensity of the host. In livestock, dynamic herd‐related resistance patterns have been observed in different animal species.
Aetiology and prognostic factors in acute liver failure in India
Authors: Khuroo M. S. , Kamili S. 
Published: December 2004

Summary.  The early prognostic indicators for acute liver failure in endemic zones for hepatitis E virus have not been determined. All consecutive patients with acute liver failure from a geographically defined region endemic for hepatitis E virus were studied over the period April 1989–April 1996. Demographic, clinical and biochemical parameters were recorded at presentation and serum samples were analysed for known viral hepatitis (A–E) markers. Multiple parameters were compared in survivors and non‐survivors in a univariate analysis. All significant factors on univariate analysis were entered into a stepwise logistic regression analysis to identify independent variables of prognosis. The sensitivity and specificity of significant prognostic factors was then assessed.A total of 180 [69 males and 111 females: age (mean ± SD) 31.1 ± 14.7 years] with acute liver failure were studied. Of these, 131 (72.8%) patients died. Hepatitis E virus was the aetiological cause in 79 (43.9%) patients, while hepatitis A virus, hepatitis B virus, hepatitis C virus and non‐A, non‐E agent/'s could be incriminated in four (2.1%), 25 (13.9%), 13 (7.2%) and 56 (31.1%) patients respectively. Of 83 women in childbearing age, 49 (59.0%) were pregnant, 33 (67.3%) of these were in the third trimester. Forty‐seven (95.8%) pregnant women had HEV infection. Nine variables differed significantly between survivors and non‐survivors on univariate analysis. Of these, four variables which predicted the adverse outcome on multivariate analysis were non‐hepatitis‐E aetiology, prothrombin time >30 s, grade of coma >2 and age >40 years in that order of significance. Pregnancy per se or duration of gestation did not adversely affect the prognosis. In endemic areas, hepatitis E virus is the commonest cause of acute liver failure. Acute liver failure occurs in a high proportion of pregnant women, mostly in third trimester. Early predictors of a poor outcome are non‐E aetiology, prothrombin time >30 s, grade of coma >2 and age >40 years.
Clinical relevance of total HCV Core antigen testing for hepatitis C monitoring and for predicting patients’ response to therapy
Authors: Maynard M. , Pradat P. , Berthillon P. , Picchio G. , Voirin N. , Martinot M. , Marcellin P. , Trepo C. 
Published: December 2004

Summary. To study the correlation between total Hepatitis C virus (HCV) Core antigen (Ag) and HCV‐RNA, and to assess the proficiency of HCV Core Ag testing in monitoring and predicting virologic response during and after pegylated interferon (PEG‐IFN) and ribavirin combination therapy.A total of 307 samples from treated and untreated patients were used to assess the correlation between the total HCV Core Ag test and quantitative HCV‐RNA assays (Superquant, and Quantiplex branched DNA 2.0 assay). Twenty‐four patients received combination therapy for 48 weeks. Blood samples were collected at day 0, and week 2, 4, 12, 24, 48 and 72 for virologic evaluation.A linear relation exists between total HCV Core Ag and HCV‐RNA levels. At 3 months the positive predictive value (PPV) of response to therapy was 100% with either HCV Core Ag or HCV‐RNA. For HCV Core Ag the negative predictive value (NPV) was 100% whereas for HCV‐RNA the NPV was 80% (P > 0.05). At month 1, the PPV was 95% and 100% when determined by HCV Core Ag and HCV‐RNA, respectively. The NPV value was 100% for HCV Core Ag and 33% for HCV‐RNA (P = 0.005).HCV Core Ag quantification could be useful in clinical practice to predict a sustained virological response early during therapy (4 weeks), reaching an optimal performance at month 3. The determination of total HCV Core Ag levels in serum, constitutes an accurate and reliable alternative to HCV‐RNA for monitoring and predicting treatment outcome in patients receiving PEG‐IFN/Ribavirin combination therapy.
Liver p53 expression in patients with HCV‐related chronic hepatitis
Authors: Loguercio C. , Cuomo A. , Tuccillo C. , Gazzerro P. , Cioffi M. , Molinari A. M. , Del Vecchio Blanco C. 
Published: December 2004

Summary. Mutated p53 acts as a dominant oncogene and alterations in the p53 gene are described in a large number of patients with hepatocellular carcinoma (HCC). It has been demonstrated that hepatitis C virus (HCV)‐core protein regulates transcriptionally cellular genes, as well as cell growth and apoptosis. This study was undertaken to evaluate whether p53 may be expressed also in a precocious stage of HCV‐related liver damage.We studied p53 expression by immunoluminometric assay on liver samples from 40 patients (M/F 18/ 22, median age 44 years, range 13–64 years) with biopsy‐proven HCV‐related chronic hepatitis. We considered the following factors: degree of liver damage, liver iron content and HCV‐RNA titre. We also evaluated as possible co‐factors alcohol and food intake in the last 3 years.p53 was over‐expressed in seven of 40 (17.5%) patients. Liver histology documented the presence of unexpected cirrhosis in two patients among the p53 positive subjects. The p53 positive group had a daily ethanol intake significantly higher in respect to that of the p53 negative group (P < 0.05). Alimentary history documented that patients with a p53 over‐expression had a lower intake of total calories, monounsaturated fatty acids, vitamin C and riboflavin.Data indicate that p53 over‐expression can occur even in initial stages of HCV‐related liver disease.
The status of foxes Vulpes vulpes on the Isle of Man in 1999
Authors: REYNOLDS JONATHAN C. , SHORT MIKE J. 
Published: December 2004

ABSTRACT 1. Foxes Vulpes vulpes probably did not occur naturally on the Isle of Man, but were present in small numbers in the mid 19th century. They were introduced again in the 1980s, and in 1990 the population was estimated at 120–300 individuals (20–50 per 100 km2) on the basis of field signs. We used a nocturnal spotlight transect survey technique to assess the status of foxes on the Isle of Man in September 1999. This method had previously been used effectively to estimate fox densities in populations as sparse as 16 per 100 km2. We surveyed a total of 852 km over a period of eight consecutive nights, during weather conditions which allowed excellent visibility. No foxes were seen. 2. By comparison with equivalent survey efforts in reference areas of mainland Britain, we conclude that post‐breeding fox density on the Isle of Man was certainly below 2.5 per 100 km2, implying a maximum of 15 foxes on the entire island. We estimate a probability of only 15–25% that a fox population of 1 per 100 km2 was present but not detected; this would be equivalent to only five or six individuals on the whole island. Foxes may even be entirely absent, although unsubstantiated sightings continue to be reported. 3. This finding is significant in understanding the ecology of the Isle of Man, and in planning the conservation of a number of ground‐nesting bird species there, as well as for farming interests, and for contingency planning against an accidental introduction of rabies.
The importance of cytotaxonomy in understanding the biogeography of African rodents: Lake Chad murids as an example
Authors: GRANJON LAURENT , DOBIGNY GAUTHIER 
Published: December 2004

ABSTRACT1. Due to the existence of numerous morphologically sibling species among African rodent genera, cytogenetical analyses are essential for correct taxonomic identifications. As an illustration, karyotypes of rodents captured in the Lake Chad area were systematically conducted, to determine them unambiguously.2. Thirteen species were found, giving a list of at least 18 species in total for the whole Lake Chad region when previously published data were critically re‐examined. Gerbilline rodents dominate in this Sahelian region, with five species ofGerbillus, four ofTaterillus, two ofTateraandDesmodilliscus braueri, and six species of murine rodents were also counted. Moreover, two species ofTaterillusappeared characterized by unique and hitherto unknown karyotypes, and undoubtedly represent new species.3. The Lake Chad area, although poorly studied from a biogeographical point of view, occupies a central position in the northern half of Africa which makes its zoogeographical affinities interesting to evaluate. Analysis of the biogeographical characteristics of the rodent species recorded here leads to the conclusion that the murid rodent community of the Lake Chad region is of mixed origin, with a dominant West African component. However, the presence of two species considered as endemics (Mastomys verheyeniandTaterillus lacustris), combined with our discovery of two new chromosomal species ofTaterillus, suggest that this region may have acted as a centre of differentiation in relatively recent times, perhaps reflecting the extensive variations of the Lake Chad basin associated with Plio‐Pleistocene cycles of transgression–regression.4. Without chromosomal data, most of these findings would have remained weakly supported, or even undiscovered, as between five and eight species could have been overlooked.
The evolution of conspecific sperm precedence in Drosophila
Authors: Dixon Sheri M. , Coyne Jerry A. , Noor Mohamed A. F. 
Published: December 2004

AbstractConspecific sperm precedence takes place when females inseminated by both conspecific and heterospecific sperm preferentially produce conspecific rather than hybrid offspring. Although many studies have documented conspecific sperm precedence, most have only identified it between taxa that are already considered to be good species. Here, we test for sperm precedence between two Drosophila pseudoobscura subspecies and between two Drosophila melanogaster races to evaluate how early in evolutionary divergence sperm precedence evolves. We found evidence of weak conspecific sperm precedence between the Drosophila subspecies but none between the Drosophila races. These pairs of taxa are already separated by mating discrimination and/or hybrid sterility, so our observation suggests that conspecific sperm precedence does not always evolve before other barriers to gene exchange.
Subdivision and haplotype structure in natural populations of Arabidopsis lyrata
Authors: Wright Stephen I. , Lauga Beatrice , Charlesworth Deborah 
Published: December 2004

AbstractHigh levels of inbreeding are expected to cause a strong reduction in levels of genetic variability, effective recombination rates and in adaptation compared with related outcrossing populations. We examined patterns of DNA polymorphism at five nuclear loci and one chloroplast locus within and between four populations of the outcrossing plant Arabidopsis lyrata, a close relative of the highly self‐fertilizing model species A. thaliana. The observed patterns are compared with species‐wide polymorphism at orthologous loci, as well as within‐ and between‐population patterns at other studied loci in A. thaliana. In addition to evidence for much higher average within‐population diversity, species‐wide levels of silent polymorphism are generally higher in A. lyrata than in A. thaliana, unlike the results from a previous study of the ADH locus. However, polymorphism is also low in the North American A. lyrata subspecies lyrata compared with the European subspecies petraea, suggesting either a population bottleneck in North American populations or recent admixture involving diverged European populations. Differentiation between the two subspecies is strong, although there are few fixed differences, suggesting that their isolation is recent. Estimates of intralocus recombination rates and analysis of haplotype structure in European A. lyrata populations indicate lower recombination than predicted based on the variability together with physical recombination rates estimated from A. thaliana. This may be due to strong population subdivision, or to recent departures from demographic equilibrium such as a bottleneck or population admixture. Alternatively, there may be consistently lower recombination rates in the outcrossing species. In contrast, estimates of recombination rates from species‐wide samples of A. thaliana are close to the values expected assuming a high rate of self‐fertilization. Complex population histories in both A. thaliana and A. lyrata complicate theoretical predictions and empirical tests of the effects of inbreeding on polymorphism and molecular evolution.
Ancestral polymorphisms in genetic markers obscure detection of evolutionarily distinct populations in the endangered Florida grasshopper sparrow (Ammodramus savannarum floridanus)
Authors: Bulgin Natalie L. , Gibbs H. Lisle , Vickery Peter , Baker Allan J. 
Published: December 2004

AbstractGenetic analyses of bird subspecies designated as conservation units can address whether they represent units with independent evolutionary histories and provide insights into the evolutionary processes that determine the degree to which they are genetically distinct. Here we use mitochondrial DNA control region sequence and six microsatellite DNA loci to examine phylogeographical structure and genetic differentiation among five North American grasshopper sparrow (Ammodramus savannarum) populations representing three subspecies, including a population of the endangered Florida subspecies (A. s. floridanus). This federally listed taxon is of particular interest because it differs phenotypically from other subspecies in plumage and behaviour and has also undergone a drastic decline in population size over the past century. Despite this designation, we observed no phylogeographical structure among populations in either marker: mtDNA haplotypes and microsatellite genotypes from floridanus samples did not form clades that were phylogenetically distinct from variants found in other subspecies. However, there was low but significant differentiation between Florida and all other populations combined in both mtDNA (FST = 0.069) and in one measure of microsatellite differentiation (θ = 0.016), while the non‐Florida populations were not different from each other. Based on analyses of mtDNA variation using a coalescent‐based model, the effective sizes of these populations are large (∼80 000 females) and they have only recently diverged from each other (< 26 000 ybp). These populations are probably far from genetic equilibrium and therefore the lack of phylogenetic distinctiveness of the floridanus subspecies and minimal genetic differentiation is due most probably to retained ancestral polymorphism. Finally, levels of variation in Florida were similar to other populations supporting the idea that the drastic reduction in population size which has occurred within the last 100 years has not yet had an impact on levels of variation in floridanus. We argue that despite the lack of phylogenetic distinctiveness of floridanus genotypes the observed genetic differentiation and previously documented phenotypic differences justify continued designation of this subspecies as a protected population segment.
Genetic variation in the endangered wild apple (Malus sylvestris (L.) Mill.) in Belgium as revealed by amplified fragment length polymorphism and microsatellite markers
Authors: Coart Els , Vekemans Xavier , Smulders Marinus J. M. , Wagner Iris , Van Huylenbroeck Johan , Van Bockstaele Erik , Roldán‐Ruiz Isabel 
Published: December 2004

AbstractThe genetic variation within and between wild apple samples (Malus sylvestris) and cultivated apple trees was investigated with amplified fragment length polymorphisms (AFLP) and microsatellite markers to develop a conservation genetics programme for the endangered wild apple in Belgium. In total, 76 putative wild apples (originating from Belgium and Germany), six presumed hybrids and 39 cultivars were typed at 12 simple sequence repeats (SSR) and 139 amplified fragment length polymorphism (AFLP) loci. Principal co‐ordinate analysis and a model‐based clustering method classified the apples into three major gene pools: wild Malus sylvestris genotypes, edible cultivars and ornamental cultivars. All presumed hybrids and two individuals (one Belgian, one German) sampled as M. sylvestris were assigned completely to the edible cultivar gene pool, revealing that cultivated genotypes are present in the wild. However, gene flow between wild and cultivated gene pools is shown to be almost absent, with only three genotypes that showed evidence of admixture between the wild and edible cultivar gene pools. Wild apples sampled in Belgium and Germany constitute gene pools that are clearly differentiated from cultivars and although some geographical pattern of genetic differentiation among wild apple populations exists, most variation is concentrated within samples. Concordant conclusions were obtained from AFLP and SSR markers, which showed highly significant correlations in both among‐genotypes and among‐samples genetic distances.
Two centuries of the Scandinavian wolf population: patterns of genetic variability and migration during an era of dramatic decline
Authors: Flagstad Ø. , Walker C. W. , Vilà C. , Sundqvist A.‐K. , Fernholm B. , Hufthammer A. K. , Wiig Ø. , Koyola I. , Ellegren H. 
Published: December 2004

AbstractThe grey wolf (Canis lupus) was numerous on the Scandinavian peninsula in the early 19th century. However, as a result of intense persecution, the population declined dramatically and was virtually extinct from the peninsula by the 1960s. We examined historical patterns of genetic variability throughout the period of decline, from 1829 to 1979. Contemporary Finnish wolves, considered to be representative of a large eastern wolf population, were used for comparison. Mitochondrial DNA (mtDNA) variability among historical Scandinavian wolves was significantly lower than in Finland while Y chromosome variability was comparable between the two populations. This may suggest that long‐distance migration from the east has been male‐biased. Importantly though, as the historical population was significantly differentiated from contemporary Finnish wolves, the overall immigration rate to the Scandinavian peninsula appears to have been low. Levels of variability at autosomal microsatellite loci were high by the early 1800s but declined considerably towards the mid‐20th century. At this time, approximately 40% of the allelic diversity and 30% of the heterozygosity had been lost. After 1940, however, there is evidence of several immigration events, coinciding with episodes of marked population increase in Russian Karelia and subsequent westwards migration.
QTL architecture of resistance and tolerance traits in Arabidopsis thaliana in natural environments
Authors: Weinig Cynthia , Stinchcombe John R. , Schmitt Johanna 
Published: December 2004

AbstractQuantitative‐genetic approaches have offered significant insights into phenotypic evolution. However, quantitative‐genetic analyses fail to provide information about the evolutionary relevance of specific loci. One complex and ecologically relevant trait for plants is their resistance to herbivory because natural enemies can impose significant damage. To illustrate the insights of combined molecular and ecological research, we present the results of a field study mapping quantitative trait loci (QTL) for resistance and tolerance to natural rabbit herbivory in the genetic model, Arabidopsis thaliana. Replicates of the Ler × Col recombinant inbred lines were planted into field sites simulating natural autumn and spring seasonal germination cohorts. Shortly after flowering, herbivores removed the main flowering inflorescence (apical meristem). We found several main‐effect QTL for resistance within each seasonal cohort and significant QTL–season interactions, demonstrating that the loci underlying resistance to a single herbivore differ across seasonal environments. The presence of QTL × environment also shows that variation at specific loci is only available to selection in some environments. Despite significant among‐line variance components, no QTL for tolerance were detected. The combined results of the quantitative‐genetic and QTL analyses demonstrate that many loci of small effect underlie tolerance to damage by rabbits, and counter the hypothesis of locus‐specific tradeoffs between resistance and tolerance. The results also provide insights as to the locus‐specific nature of evolutionary constraints, i.e. some loci influence flowering time and resistance in both seasonal cohorts. Our results show how linking molecular‐genetic tools with field studies in ecologically relevant settings can clarify the role of specific loci in the evolution of quantitative traits.
Analysis of molecular data of Arabidopsis thaliana (L.) Heynh. (Brassicaceae) with Geographical Information Systems (GIS)
Authors: Hoffmann Matthias H. , GLAß Anne S. , Tomiuk Jürgen , Schmuths Heike , Fritsch Reinhard M. , Bachmann Konrad 
Published: December 2004

AbstractA Geographical Information System (GIS) is used to analyse allelic information of 13 sequenced loci of natural populations of Arabidopsis thaliana and to identify geographical structures. GIS provides tools for visualization and analysis of geographical population structures using molecular data. The geographical distribution of the number of variable positions in the alignments, the distribution of recombinant sequence blocks, and the distribution of a newly defined measure, the differentiation index, are studied. The differentiation index is introduced to measure the sequence divergence among individual plants sampled from various geographical localities. The numbers of variable positions and the differentiation index are also used for a metadata analysis covering about 26 kb of the genome. This analysis reveals, for the first time, differences in DNA sequence structures of geographically different populations of A. thaliana. The broadly defined west Mediterranean region consists of accessions with the highest numbers of polymorphic positions followed by the west European region. The GIS technology Kriging is used to define Arabidopsis specific diversity zones in Europe. The highest genetic variability is observed along the Atlantic coast from the western Iberian Peninsula to southern Great Britain, while lowest variability is found in central Europe.