bluuebunny/crossref_metadata_2025 huggingface dataset:
Genes in the accessory sec locus of Streptococcus gordonii have three functionally distinct effects on the expression of the platelet‐binding protein GspB
Authors: Takamatsu Daisuke , Bensing Barbara A. , Sullam Paul M.
Published: December 2004

Platelet binding by Streptococcus gordonii strain M99 is strongly correlated with the expression of the large surface glycoprotein GspB. A 14 kb chromosomal region downstream of gspB was previously shown to be required for the expression of this protein. The region encodes SecA2 and SecY2, which are components of an accessory secretion system dedicated specifically to the export of GspB. The region also includes three genes (gly, nss and gtf) that encode proteins likely to function in carbohydrate metabolism, and four genes (orf1–4) that encode proteins of unknown function. In this report, we have investigated the role of these genes in GspB expression. We found that disruption of orf1, orf2 or orf3 resulted in a loss of GspB export and the intracellular accumulation of GspB. As they are apparently essential components of the accessory secretion system, these genes were renamed asp1–3 (for accessory secretory protein). In gtf and orf4 mutants, gspB was transcribed, but no GspB was detected. These results suggest that Gtf and Orf4 are required for the translation or for the stability of GspB. In contrast, gly and nss mutants were able to express and export GspB. However, disruption of these genes appeared to affect the carbohydrate composition of this glycoprotein. As asp1–3, gtf and orf4, but not gly and nss, are conserved in the accessory sec loci of several staphylococcal and streptococcal species, these genes may also have crucial roles in the expression and export of GspB homologues in the other Gram‐positive bacteria.
Transcription activation by remodelling of a nucleoprotein assembly: the role of NarL at the FNR‐dependent Escherichia coli nir promoter
Authors: Browning Douglas F. , Cole Jeffrey A. , Busby Stephen J. W.
Published: December 2004

Expression from the Escherichia coli nir promoter is co‐dependent on both the FNR protein (an anaerobically triggered transcription activator) and NarL or NarP proteins (transcription activators triggered by nitrite and nitrate). We found previously that FNR binds to a site centred at position − 41.5 at the nir promoter, but that FNR‐dependent activation is repressed by IHF binding to a site centred at position −88 (IHF I) and Fis binding to sites centred at positions −142 (Fis I) and +23 (Fis II). Here, we have studied the binding of purified IHF, Fis and FNR to the nir promoter in vitro. Our results show that the nir promoter contains a second IHF site at position −115 (IHF II) and a third Fis site at position −97 (Fis III), and that IHF, Fis and FNR can bind together to form multiprotein complexes. Surprisingly, IHF binding at the IHF II site increases FNR‐dependent activation by decreasing the repression mediated by IHF and Fis binding at the other sites. In previous work, we found that NarL or NarP activates the nir promoter by binding to a site centred at position −69.5 and counteracting the repressive effects of IHF and Fis. We now show that NarL can displace IHF bound at the IHF I site, but IHF is unable to displace bound NarL. We suggest that NarL interferes with IHF binding at the nir promoter by distorting the minor groove at its target site, and we argue that the resulting activation by NarL results from remodelling of the local nucleoprotein structure to facilitate FNR‐dependent transcription.
Sortases and pilin elements involved in pilus assembly of Corynebacterium diphtheriae
Authors: Ton‐That Hung , Marraffini Luciano A. , Schneewind Olaf
Published: December 2004

Corynebacterium diphtheriae SpaA pili are composed of three pilin subunits, SpaA, SpaB and SpaC. SpaA, the major pilin protein, is distributed uniformly along the pilus shaft, whereas SpaB is observed at regular intervals, and SpaC seems to be positioned at the pilus tip. Pilus assembly in C. diphtheriae requires the pilin motif and the C‐terminal sorting signal of SpaA, and is proposed to occur by a mechanism of ordered cross‐linking, whereby pilin‐specific sortase enzymes cleave precursor proteins at sorting signals and involve the side‐chain amino groups of pilin motif sequences to generate covalent linkages between pilin subunits. We show here that two elements of SpaA pilin precursor, the pilin motif and the sorting signal, are together sufficient to promote the polymerization of an otherwise secreted protein by a process requiring the function of the sortase A gene (srtA). Five other sortase genes are dispensable for SpaA pilus assembly. Further, the incorporation of SpaB into SpaA pili requires a glutamic acid residue within the E box motif of SpaA, a feature that is found to be conserved in other Gram‐positive pathogens that encode sortase and pilin subunit genes with sorting signals and pilin motifs. When the main fimbrial subunit of Actinomyces naeslundii type I fimbriae, FimA, is expressed in corynebacteria, C. diphtheriae strain NCTC13129 polymerized FimA to form short fibres. Although C. diphtheriae does not depend on other actinomycetal genes for FimA polymerization, this process involves the pilin motif and the sorting signal of FimA as well as corynebacterial sortase D (SrtD). Thus, pilus assembly in Gram‐positive bacteria seems to occur by a universal mechanism of ordered cross‐linking of precursor proteins, the multiple conserved features of which are recognized by designated sortase enzymes.
Differentiate to thrive: lessons from the Legionella pneumophila life cycle
Authors: Molofsky Ari B. , Swanson Michele S.
Published: December 2004

When confronted by disparate environments, microbes routinely alter their physiology to tolerate or exploit local conditions. But some circumstances require more drastic remodelling of the bacterial cell, as sporulation by the Bacillus and Streptomyces species of soil bacteria vividly illustrates. Cellular differentiation is also crucial for pathogens, the challenge for which is to colonize one host, then be transmitted to the next. Using the Gram‐negative Legionella pneumophila as a model intracellular pathogen, we describe how biogenesis of the replication vacuole is determined by the developmental state of the bacterium. Subsequently, when replicating bacteria have exhausted the nutrient supply, the pathogens couple their conversion to stationary phase physiology with expression of traits that promote transmission to a new host. The cellular differentiation of L. pneumophila is co‐ordinated by a regulatory circuit that integrates several elements that are broadly conserved in the microbial world. The alarmone (p)ppGpp promotes transcription directed by the alternative sigma factors RpoS, FliA and, probably, RpoN, and also post‐transcriptional control mediated by a two‐component regulatory system, LetA/S (GacA/S), and an mRNA‐binding protein, CsrA (RsmA). By applying knowledge of microbial differentiation in combination with tools to screen the complete genomes of pathogens, experiments can be designed to identify two distinct classes of virulence traits: factors that promote replication and those dedicated to transmission.
A hyperstructure approach to mitochondria
Authors: Trinei Mirella , Vannier Jean‐Pierre , Beurton‐Aimar Marie , Norris Vic
Published: December 2004

Several questions in our understanding of mitochondria are unanswered. These include how the ratio of mitochondrial (mt)DNA to mitochondria is maintained, how the accumulation of defective, rapidly replicating mitochondrial DNA is avoided, how the ratio of mitochondria to cells is adjusted to fit cellular needs, and why any proteins are synthesized in mitochondria rather than simply imported. In bacteria, large hyperstructures or assemblies of proteins, mRNA, lipids and ions have been proposed to constitute a level of organization intermediate between macromolecules and whole cells. Here, we suggest how the concept of hyperstructures together with other concepts developed for bacteria such as transcriptional sensing and spontaneous segregation may provide answers to mitochondrial problems. In doing this, we show how the problem of the very existence of mtDNA brings its own solution.
Subtilisin‐like proteases of the malaria parasite
Authors: Withers‐Martinez Chrislaine , Jean Létitia , Blackman Michael J.
Published: December 2004

Proteases play critical roles in the life cycle of the malaria parasite, Plasmodium spp. Within the asexual erythrocytic cycle, responsible for the clinical manifestations of malaria, substantial interest has focused on the role of parasite serine proteases as a result of indications that they are involved in red blood cell invasion. Over the past 6 years, three Plasmodium genes encoding serine proteases of the subtilisin‐like clan, or subtilases, have been identified. All are expressed in the asexual blood stages and, in at least two cases, the gene products localize to secretory organelles of the invasive merozoite. They may have potential as novel drug targets. Here, we review progress in our understanding of the maturation, specificity, structure and function of these Plasmodium subtilases.
Magnetic resonance imaging as a tool to examine the neuropathology of multiple sclerosis
Authors: Bö L. , Geurts J. J. G. , Ravid R. , Barkhof F.
Published: December 2004

Magnetic resonance imaging (MRI) has significantly extended the understanding of multiple sclerosis (MS), owing to its ability to sensitively depict the dynamics of the disease process in vivo. The subject of this review is the use of MRI in the post‐mortem setting, with emphasis on how it may be used to improve the specimen selection process at autopsy. Lesions with active demyelination are highly interesting in the study of MS pathogenesis, but are rare in a typical autopsy material of chronic MS. The yield of MS lesions in autopsy specimen selection can be increased by the use of MRI‐guided tissue sampling, as a significant proportion of abnormalities detected by post‐mortem MRI are not macroscopically visible/palpable. The majority of these MRI abnormalities have been found to represent either discrete areas of microglial activation with no demyelination (so‐called (p)reactive lesions), or active demyelinating MS lesions by further histopathological examination. The presence and extent of MS pathology outside of the focal demyelinated lesions is more readily appreciated by MRI‐guided specimen sampling, as has been shown in the study of extensive areas of partial myelin loss in the spinal cord. A further advantage of MRI‐guided specimen sampling is the ability to use three‐dimensional and quantitative measures. The potential of correlating these with histopathological data may be further exploited in the future. The technical procedure for MRI‐guided tissue sampling at autopsy is presented, and the limitations of the technique are discussed.
Immunohistochemical localization of vascular endothelial growth factor receptors‐1, ‐2 and ‐3 in human spinal cord: altered expression in amyotrophic lateral sclerosis
Authors: Spliet W. G. M. , Aronica E. , Ramkema M. , Witmer A. N. , Schlingemann R. O. , De Jong J. M. B. V. , Troost D.
Published: December 2004

Vascular endothelial growth factor (VEGF) has recently been implicated in several neurological disorders. Apart from its prominent role in angiogenesis, VEGF has been shown to have direct effects on neuronal and glial cells through activation of different VEGF receptor (VEGFR) types. In the present study the expression patterns of VEGFR‐1, ‐2 and ‐3 were investigated in the spinal cord of control and both sporadic and familial amyotrophic lateral sclerosis (ALS) patients. Immunocytochemical analysis of control human spinal cord demonstrated that VEGFR‐1, but not VEGFR‐2 or ‐3 was found to be present in blood vessels of both white and grey matter. All three VGEFRs were not detectable in resting glial cells of control tissue. Diffuse neuropil staining was observed in the control spinal cord grey matter for VEGFR‐3. Regional differences in VEGFRs immunoreactivity (IR) were apparent in ALS compared to controls. In particular, VEGFR‐1 expression was increased in reactive astroglial cells in both grey (ventral horn) and white matter of ALS spinal cord. In addition to the astroglial labelling, increased expression of VEGFR‐1 and, to a less extent also of VEGFR‐2, was observed in blood vessels of the ALS spinal cord. No changes in VEGFR‐3 IR were detected in blood vessels or reactive astroglial cells, whereas VEGFR‐3 neuropil expression was reduced and paralleled the distribution of neuronal loss in the ventral horn of ALS spinal cord. These findings indicate that VEGFRs have specific distribution patterns, suggesting different physiological functions in human spinal cord. Moreover, the altered expression observed in ALS supports a role for these receptors in the complex reactive processes that are associated with the progression of spinal cord damage.
Differential gene expression in human brain pericytes induced by amyloid‐β protein
Authors: Rensink A. A. M. , Otte‐Höller I. , Donkelaar H. J. ten , De Waal R. M. W. , Kremer B. , Verbeek M. M.
Published: December 2004

Cerebral amyloid angiopathy is one of the characteristics of Alzheimer's disease (AD) and this accumulation of fibrillar amyloid‐β (Αβ) in the vascular wall is accompanied by marked vascular damage. In vitro, Aβ1−40 carrying the ‘Dutch’ mutation (DAβ1−40) induces degeneration of cultured human brain pericytes (HBP). To identify possible intracellular mediators of Aβ‐induced cell death, a comparative cDNA expression array was performed to detect differential gene expression of Aβ‐treated vs. untreated HBP. Messenger RNA expression of cyclin D1, integrin β4, defender against cell death‐1, neuroleukin, thymosin β10, and integrin α5 were increased in DAβ1−40‐treated HBP, whereas insulin‐like growth factor binding protein‐2 mRNA expression was decreased. Corresponding protein expression was investigated in AD and control brains to explore a potential role for these proteins in pathological lesions of the AD brain. Cyclin D1 expression was increased in cerebral amyloid angiopathy and cells in a perivascular position, suggesting that the cell cycle may be disturbed during Aβ‐mediated degeneration of cerebrovascular cells. Moreover, cyclin D1 expression, but also that of integrin β4, defender against cell death‐1, neuroleukin and thymosin β10 was found in a subset of senile plaques, suggesting a role for these proteins in the pathogenesis of senile plaques.
Comparison of the pathology of cerebral white matter with post‐mortem magnetic resonance imaging (MRI) in the elderly brain
Authors: Fernando M. S. , O'Brien J. T. , Perry R. H. , English P. , Forster G. , McMeekin W. , Slade J. Y. , Golkhar A. , Matthews F. E. , Barber R. , Kalaria R. N. , Ince P. G. ,   Neuropathology Group of MRC CFAS
Published: December 2004

White matter lesions (WML) on magnetic resonance imaging (MRI) brain scans are associated with ageing. They are unrelated to specific disorders, and their impact on cognitive and other brain functions is poorly characterized. Pathological studies often omit systematic survey of WML because of the need to study multiple full coronal tissue blocks, and uncertainty over the significance of lesions identified in periventricular and deep subcortical regions. Post‐mortem MRI provides a means of mapping WML but the sensitivity and specificity of the method are unresolved. In this study post‐mortem MRI of WML in fixed brain slices was compared with pathology in 33 brains donated to the Medical Research Council Cognitive Function and Ageing Study (MRC CFAS). This study shows that MRI detection of WML was less sensitive than pathology: periventricaular lesions (PVL) sensitivity = 95% (87–99%), specificity = 71% (44–90%); deep subcortical lesions (DSCL) sensitivity = 86% (79–93%), specificity = 80% (72–88%). False negative MRI was associated with milder pathology, but lesions detected by myelin attenuation alone showed both microglial and endothelial activation. Therefore post‐mortem MRI of formalin‐fixed brain slices is a reliable method to obtain systematic data on the severity and distribution of cerebral white matter disease, and appears to detect those WML most likely to have clinical impact.
Protein misfolding in neurodegenerative diseases
Authors: Agorogiannis E. I. , Agorogiannis G. I. , Papadimitriou A. , Hadjigeorgiou G. M.
Published: December 2004

A common pathogenic mechanism shared by diverse neurodegenerative disorders, like Alzheimer's disease, Parkinson's disease, Huntington's disease and transmissible spongiform encephalopathies, may be altered protein homeostasis leading to protein misfolding and aggregation of a wide variety of different proteins in the form of insoluble fibrils. Mutations in the genes encoding protein constituents of these aggregates have been linked to the corresponding diseases, thus a reasonable scenario of pathogenesis was based on misfolding of a neurone‐specific protein that forms insoluble fibrils that subsequently kill neuronal cells. However, during the past 5 years accumulating evidence has revealed the neurotoxic role of prefibrillar intermediate forms (soluble oligomers and protofibrils) produced during fibril formation. Many think these may be the predominant neurotoxic species, whereas microscopically visible fibrillar aggregates may not be toxic. Large protein aggregates may rather be simply inactive, or even represent a protective state that sequesters and inactivates toxic oligomers and protofibrils. Further understanding of the biochemical mechanisms involved in protein misfolding and fibrillization may optimize the planning of common therapeutic approaches for neurodegenerative diseases, directed towards reversal of protein misfolding, blockade of protein oligomerization and interference with the action of toxic proteins.
The evolution of phenotypic plasticity in spatially structured environments: implications of intraspecific competition, plasticity costs and environmental characteristics
Authors: Ernande B. , Dieckmann U.
Published: December 2004

We model the evolution of reaction norms focusing on three aspects: frequency-dependent selection arising from resource competition, maintenance and production costs of phenotypic plasticity, and three characteristics of environmental heterogeneity (frequency of environments, their intrinsic carrying capacity and the sensitivity to phenotypic maladaptation in these environments). We show that (i) reaction norms evolve so as to trade adaptation for acquiring resources against cost avoidance; (ii) maintenance costs cause reaction norms to better adapt to frequent rather than to infrequent environments, whereas production costs do not; and (iii) evolved reaction norms confer better adaptation to environments with low rather than with high intrinsic carrying capacity. The two previous findings contradict earlier theoretical results and originate from two previously unexplored features that are included in our model. First, production costs of phenotypic plasticity are only incurred when a given phenotype is actually produced. Therefore, they are proportional to the frequency of environments, and these frequencies thus affect the selection pressure to avoid costs just as much as the selection pressure to improve adaptation. This prevents the frequency of environments from affecting the evolving reaction norm. Secondly, our model describes the evolution of plasticity for a phenotype determining an individual's capability to acquire resources, and thus its realized carrying capacity. When individuals are distributed randomly across environments, they cannot avoid experiencing environments with intrinsically low carrying capacity. As selection pressures arising from the need to improve adaptation are stronger under such extreme conditions than under mild ones, better adaptation to environments with low rather than with high intrinsic carrying capacity results.
Uneven segregation of sporophytic self-incompatibility alleles inArabidopsis lyrata
Authors: Bechsgaard J. , Bataillon T. , Schierup M. H.
Published: December 2004

Self-incompatibility in Arabidopsis lyrata is sporophytically controlled by the multi-allelic S-locus. Self-incompatibility alleles (S-alleles) are under strong negative frequency dependent selection because pollen carrying common S-alleles have fewer mating opportunities. Population genetics theory predicts that deleterious alleles can accumulate if linked to the S-locus. This was tested by studying segregation of S-alleles in 11 large full sib families in A. lyrata. Significant segregation distortion leading to an up to fourfold difference in transmission rates was found in six families. Differences in transmission rates were not significantly different in reciprocal crosses and the distortions observed were compatible with selection acting at the gametic stage alone. The S-allele with the largest segregation advantage is also the most recessive, and is very common in natural populations concordant with its apparent segregation advantage. These results imply that frequencies of S-alleles in populations of A. lyrata cannot be predicted based on simple models of frequency-dependent selection alone.
Epistasis affecting litter size in mice
Authors: Peripato A. C. , De Brito R. A. , Matioli S. R. , Pletscher L. S. , Vaughn T. T. , Cheverud J. M.
Published: December 2004

Litter size is an important reproductive trait as it makes a major contribution to fitness. Generally, traits closely related to fitness show low heritability perhaps because of the corrosive effects of directional natural selection on the additive genetic variance. Nonetheless, low heritability does not imply, necessarily, a complete absence of genetic variation because genetic interactions (epistasis and dominance) contribute to variation in traits displaying strong heterosis in crosses, such as litter size. In our study, we investigated the genetic architecture of litter size in 166 females from an F2 intercross of the SM/J and LG/J inbred mouse strains. Litter size had a low heritability (h2 = 12%) and a low repeatability (r = 33%). Using interval-mapping methods, we located two quantitative trait loci (QTL) affecting litter size at locations D7Mit21 + 0 cM and D12Mit6 + 8 cM, on chromosomes 7 and 12 respectively. These QTL accounted for 12.6% of the variance in litter size. In a two-way genome-wide epistasis scan we found eight QTL interacting epistatically involving chromosomes 2, 4, 5, 11, 14, 15 and 18. Taken together, the QTL and their interactions explain nearly 49% (39.5% adjusted multiple r2) of the phenotypic variation for litter size in this cross, an increase of 36% over the direct effects of the QTL. This indicates the importance of epistasis as a component of the genetic architecture of litter size and fitness in our intercross population.
Human birthweight evolution across contrasting environments
Authors: Thomas F. , Teriokhin A. T. , Budilova E. V. , Brown S. P. , Renaud F. , Guegan J. F.
Published: December 2004

We explore from both theoretical and empirical perspectives the hypothesis that a significant part of the worldwide variability in human birthweight results from adaptive responses to local selective pressures. We first developed an agent-based model to simulate the process of evolutionary selection on life history strategy, and then we performed a comparative analysis across 89 countries worldwide. The model illustrates that optimal birthweight depends on which fitness-reducing risk locally predominates (somatic diseases, parasitic diseases or adverse environmental conditions). When fitness variations between individuals mainly result from somatic diseases (e.g. industrialized countries), or conversely from infectious and parasitic diseases (e.g. developing countries), selection is expected to favour individuals producing larger children. Conversely, when environmental risks increase in relative importance, selective pressures for producing children with high birthweight are reduced. The comparative analysis supports these theoretical expectations, in particular the finding that birthweight is higher than predicted in highly parasitized countries.
An analysis of genetic differentiation among assortatively mating Drosophila melanogaster in Zimbabwe
Authors: Kauer M. O. , Schlötterer C.
Published: December 2004

African Drosophila melanogaster populations, and those from Zimbabwe in particular, have attracted much interest recently. African flies differ genetically from ‘cosmopolitan‘ populations and were found to exhibit discriminative mating behaviour against individuals from ‘cosmopolitan’ populations. It has therefore been proposed that Zimbabwean and some other African populations are in an ‘incipient stage of speciation’. However, whether the mating behaviour is an effective barrier against gene flow from other populations, and whether intra-population genetic differentiation has already evolved in sympatry is not known. Here, we took a population-based approach to test whether the well-characterized mating type differences have resulted in a genome-wide differentiation at the population level. Using 122 polymorphic microsatellite loci mapping to the third chromosome, we demonstrate a significant genetic differentiation between Zimbabwean flies differing in their mating behaviour. We also provide evidence to suggest that this difference is unlikely to be attributable to population structure within Zimbabwe. However, the analysis of individual microsatellite loci did not indicate more loci differentiating these two groups than expected by chance. Our data suggest that the ‘Z’-‘M’ mating behaviour is strong enough to result in a small but significant genetic differentiation. Thus, future studies based on a larger population sample of flies characterized for their mating behaviour and using more markers are expected to provide more information on the genetic basis of the mating traits in the Zimbabwe flies.
Levels of inbreeding depression over seven generations of selfing in the androdioecious clam shrimp, Eulimnadia texana
Authors: Weeks S. C.
Published: December 2004

Androdioecy (mixtures of males and hermaphrodites) is a rare mating system in both plants and animals. Theory suggests that high levels of inbreeding depression can maintain males in androdioecious populations if hermaphrodites commonly self-fertilize. However, if inbreeding depression (δ) can be ‘purged’ from selfing populations, maintaining males is more difficult. In the androdioecious clam shrimp, Eulimnadia texana, δ is estimated to be as high as 0.7. Previous work suggests that this high level is maintained in the face of high levels of inbreeding due to an associative overdominance of fitness-related loci with the sex-determining locus. Such associative overdominance would make purging of inbreeding depression difficult to impossible. The current experiment was designed to determine if δ can be purged in these shrimp by tracking fitness across seven generations in selfing and outcrossing treatments. Evidence of purging was found in one of four populations, but the remaining populations demonstrated a consistent pattern of δ across generations. Although the experimental design allowed ample opportunity for purging, the majority of populations were unable to purge their genetic load. Therefore, δ in this species is likely due to associative overdominance caused by deleterious recessive alleles linked to the sex determining locus.
Glycopeptide resistant Staphylococcus
Authors: Witte W.
Published: December 2004

Insensitivity of Staphylococcus aureus to glycopeptides became known at the end of the 1990s. To distinguish intermediate (VISA and GISA) and full resistance (vancomycin‐resistant Staphylococcus aureus, VRSA) is of both epidemiological and clinical importance. The VISA (GISA) phenotype is obviously selected by glycopeptide usage in individual patients and can be disseminated by clonal spread of particularly affected staphylococcal isolates, preferentially methicillin‐resistant S. aureus (MRSA). In the meantime emergence of VISA became known worldwide. VRSA evolve by acquisition of the vanA gene from enterococci, which are of significance as reservoir of resistance genes among gram‐positive bacterial pathogens. Until now three independent single cases of emergence of VRSA became known from the USA, in two of them an association with vanA containing Enterococcus spp. at the same site of the affected patients could be established. The frequency of VISA (GISA) among MRSA in Central Europe is still low (<0.1%); no VRSA have been detected until now.
Monitoring of Antimicrobial Resistance Among Food Animals: Principles and Limitations
Authors: Aarestrup F. M.
Published: December 2004

Large amounts of antimicrobial agents are in the production of food animals used for therapy and prophylactics of bacterial infections and in feed to promote growth. The use of antimicrobial agents causes problems in the therapy of infections through the selection for resistance among bacteria pathogenic for animals or humans. Current knowledge regarding the occurrence of antimicrobial resistance in food animals, the quantitative impact of the use of different antimicrobial agents on selection for resistance and the most appropriate treatment regimes to limit the development of resistance is incomplete. Programmes monitoring the occurrence and development of resistance are essential to determine the most important areas for intervention and to monitor the effects of interventions. When designing a monitoring programme it is important to decide on the purpose of the programme. Thus, there are major differences between programmes designed to detect changes in a national population, individual herds or groups of animals. In addition, programmes have to be designed differently according to whether the aim is to determine changes in resistance for all antimicrobial agents or only the antimicrobial agents considered most important in relation to treatment of humans. In 1995 a continuous surveillance for antimicrobial resistance among bacteria isolated from food animals was established in Denmark. Three categories of bacteria, indicator bacteria, zoonotic bacteria and animal pathogens are continuously isolated from broilers, cattle and pigs and tested for susceptibility to antimicrobial agents used for therapy and growth promotion by disc diffusion or minimal inhibitory concentration determinations. This programme will only detect changes on a national level. However, isolating the bacteria and testing for several antimicrobial agents will enable us to determine the effect of linkage of resistance. Since 1995 major differences in the consumption pattern of different antimicrobial agents have occurred in Denmark. The Danish monitoring programme has enabled us to determine the effect of these changes on the occurrence of resistance. The Danish monitoring is, however, not suited to determine changes on a herd level or to detect emergence of new types of resistance only occurring at a low level.
Complete resolution of pulmonary Rhizopus oryzae infection with itraconazole treatment: more evidence of the utility of azoles for zygomycosis
Authors: Eisen D. P. , Robson J.
Published: December 2004

Zygomycosis often requires aggressive surgical and antifungal therapy. We report a non‐neutropenic patient with myelodysplastic syndrome and iron overload receiving cytotoxic therapy who presented with pulmonary Rhizopus oryzae infection. This patient was cured through the use of itraconazole alone and the literature on the utility of azole antifungals for zygomycosis is reviewed.
Aspergillus niger infection in patients with haematological diseases: a report of eight cases
Authors: Fianchi L. , Picardi M. , Cudillo L. , Corvatta L. , Mele L. , Trapè G. , Girmenia C. , Pagano L.
Published: December 2004

In this paper we analysed clinical, laboratory characteristics and outcome of patients with haematological diseases who developed an Aspergillus niger infection, in a multicentre study involving 14 Italian Haematological Divisions during a 10‐year period. The study recorded 194 consecutive microbiologically documented aspergilloses, eight of which (4%) were due to A. niger, and were observed only in five of the participating centres. The primary localization of infection was lung in seven cases and paranasal sinus in one case. Seven patients died at the end of follow‐up. The death was mainly attributable to A. niger progression in six of them. Our study that collected the largest number of cases of A. niger infection in haematological malignancies confirms that this infrequent complication is characterized by a high mortality rate.
Phylogeny and typification of Madurella mycetomatis, with a comparison of other agents of eumycetoma
Authors: de Hoog G. S. , Adelmann D. , Ahmed A. O. A. , van Belkum A.
Published: December 2004

The genus Madurella, described for non‐sporulating agents of human mycetoma, is proven to be heterogeneous on the basis of rDNA small subunit (SSU) and Internal Transcribed Spacer (ITS) sequencing data. Madurella mycetomatis, the main agent of mycetoma in arid zones of Central and East Africa, probably belongs to the ascomycete order Sordariales. Madurella mycetomatis, the generic type species, is neotypified. Madurella grisea, with worldwide occurrence, is likely to be a member of the order Pleosporales, just as the mycetoma agents of Leptosphaeria, Pseudochaetosphaeronema, and Pyrenochaeta. Neotestudina rosatii belongs to the order Dothideales. Judging from ITS data, M. mycetomatis and N. rosatii are species complexes. The ex‐type strain of N. rosatii, from a human mycetome, has an ITS sequence that deviates from that of environmental strains of the species.
A clinical multicenter study comparing efficacy and tolerability of topical combination therapy with clotrimazole (Canesten®, two formats) with oral single dose fluconazole (Diflucan®) in vulvovaginal mycoses
Authors: Mendling Werner , Krauss Christian , Fladung Bernward
Published: December 2004

Two topical formats containing clotrimazole [500 mg single dose vaginal tablet (VT) or 10% single dose vaginal cream (VC) for intravaginal use] combined with additional clotrimazole cream for topical application to the vulval area (Canesten® 1 Combi, Bayer AG, Leverkusen, Germany) were compared with oral fluconazole 150 mg single dose treatment of vulvovaginal mycosis (VVM) in a single‐blind clinical study. The objective of the study was to demonstrate the equivalent efficacy of the clotrimazole combination therapies (VT + 1% cream and VC + 2% cream), and fluconazole 150 mg oral capsule (Diflucan® 1, Pfizer Gmbh, Karlsruhe, Germany) in terms of overall response defined as clinical cure and mycological resolution. Overall, combination therapies containing either clotrimazole 500 mg VTs or clotrimazole 10% VC were as effective as a single dose fluconazole 150 mg oral tablet in treating VVM with rates for overall response being 66%, 61% and 60%, respectively, after 14 days. There were no significant differences in the time to onset of symptom relief in the clotrimazole 500 mg tablet group and clotrimazole 10% VC compared with fluconazole 150 mg oral capsules. Only 50% of 88 patients across treatment groups with mycological recurrence also experienced return of symptoms over the entire 8 week follow‐up period. All treatments administered were safe and well‐tolerated and the number of patients experiencing adverse events was low.
Comparative serological evaluation of 10 Blastomyces dermatitidis yeast phase lysate antigens from different sources
Authors: Abuodeh R. O. , Chester E. M. , Scalarone G. M.
Published: December 2004

Yeast phase lysate antigens from 10 isolates of Blastomyces dermatitidis (dog, ERC‐2 and T‐58; T‐27, polar bear; woodpile, ER‐3; bat lung, 48938; human, B5929, B5895, B5896, B5931, and CAPP) from different geographical regions, in addition to a Histoplasma capsulatum (G217B) lysate preparation were compared with respect to their reactivity against serum specimens from dogs, rabbits and humans positive for blastomycosis using an indirect enzyme‐linked immunosorbent assay. In addition, the lysate antigens were also assayed against histoplasmosis‐positive human serum samples to study their cross‐reactivity. Variable results were obtained with T‐58 and T‐27 exhibiting the greatest reactivity. We also noticed that the lysate did not react consistently to serum samples across species with lesser reactivity evidenced when testing dog sera. Finally, T‐58 gave the highest cross‐reactivity with histoplasmosis‐positive sera. The study may prove valuable in the development of antigen candidates for blastomycosis serodiagnosis.
Endoscopic findings of adenocarcinoma arising from short‐segment Barrett's esophagus
Authors: YAGI KAZUYOSHI , NAKAMURA ATSUO , SEKINE ATSUO , TAMIYA YOICHI , OYAMATSU MANABU , WATANABE HIDENOBU
Published: December 2004

Abstract  Adenocarcinoma arising from short‐segment Barrett's esophagus (SSBE) is rare in Japan, although the incidence of this condition is increasing in Western countries. Four cases of early adenocarcinoma arising from SSBE were diagnosed and treated at Niigata‐prefectural Yoshida Hospital. All patients were male, variously 55, 71, 73 and 79 years of age. All four patients had long‐term gastroesophaeal reflux disease, although one patient had erosive esophagitis and three patients did not have erosive esophagitis. Three patients were diagnosed as having Helicobacter pylori‐free stomach. All adenocarcinomas occurred close to the squamocolumnar junction. Patients with SSBE should undergo detailed endoscopic examination of the squamocolumnar junction in order to detect early adenocarcinoma arising from SSBE.
Gastric electrical activity in patients with cholelithiasis undergoing laparoscopic cholecystectomy: A prospective controlled study
Authors: SGOUROS SPIROS N , VLACHOGIANNAKOS JIANNIS , KARAMANOLIS GEORGE , STEFANIDIS GERASIMOS , PAPADOPOULOU EUTHIMIA , PECHLIVANIDES GEORGE , NOUSIS GRIGORIOS , MANTIDES APOSTOLOS
Published: December 2004

Background:  The aim of the present study was to evaluate the effect of gallstone disease (GD) and laparoscopic cholecystectomy on gastric electrical activity of slow waves, which was recorded via transcutaneous electrogastrography (EGG).

Methods:  Twenty‐one consecutive patients (M/F: 12/9, 52.7 ± 15 years old) with GD and no previous history of abdominal operations or known disease affecting gastrointestinal motility were studied. The EGG was performed for 30 min prior to and 90 min after a standard meal, during a 4–6 month period prior to and after laparoscopic cholecystectomy. The percentile proportion of the three spectra of gastric slow waves frequency was studied, defined as follows: bradygastria, 1–2.1 cycles per min (c.p.m.); normogastria, 2.2–3.9 c.p.m.; and tachygastria, 4–9 c.p.m. The findings were compared to those of nine healthy subjects (M/F: 5/4, 49.5 ± 14.8 years old).

Results:  No statistically significant difference was found in percentile distribution of bradygastria, normogastria and tachygastria, pre‐ or post‐prandially, neither before or after laparoscopic cholecystectomy, nor between patients and controls.

Conclusions:  Patients with GD do not exhibit differences in gastric electrical activity of slow waves in comparison to normal subjects and laparoscopic cholecystectomy does not alter gastric electrical activity. These findings suggest that cholelithiasis does not seem to cause dyspeptic symptoms due to gastric dysrythmias.
Non‐alcoholic steatohepatitis in type 2 diabetes mellitus
Authors: GUPTE PARIJAT , AMARAPURKAR DEEPAK , AGAL SUBHASH , BAIJAL RAJIV , KULSHRESTHA PRAMOD , PRAMANIK SNEHANSU , PATEL NIKHIL , MADAN ARUNA , AMARAPURKAR ANJALI , HAFEEZUNNISA
Published: December 2004

Background and Aims:  Non‐alcoholic steatohepatitis (NASH) is commonly associated with type 2 diabetes mellitus (DM). Prevalence of NASH in type 2 DM has not been well studied and there is an epidemic rise in type 2 DM in Asian and Western populations. Its association with chronic liver disease in the form of NASH makes it an important health problem. Hence we have studied its prevalence and correlation of biochemical parameters with histological grades of non‐alcoholic fatty liver disease (NAFLD) in otherwise asymptomatic type 2 DM patients.

Methods:  One hundred and forty‐eight individuals were screened. Forty‐eight individuals were excluded due to history of alcohol intake or liver disease as a result of other causes. One hundred non‐alcoholic individuals with type 2 DM underwent abdominal ultrasonography (US abdomen). Forty‐nine patients had evidence of fatty liver on US abdomen, and 32 of these 49 patients underwent liver biopsy.

Results:  Four of 32 (12.5%) individuals had steatosis alone. Mild, moderate and severe NASH was present in 21/32 (65.5%), 4/32 (12.5%) and 3/32 (9.35%), respectively. Fibrosis was present in 7/32 (21.8%) patients (four grade 1 and three grade 3). There was no significant difference in body mass index (BMI), transaminase levels, serum cholesterol and triglyceride levels among patients with non‐alcoholic fatty liver disease.

Conclusion:  We conclude that the prevalence of NASH is high in type 2 DM patients and liver biopsy is the only investigation to differentiate between non‐alcoholic fatty liver and steatohepatitis.
Association between diet and esophageal cancer in Taiwan
Authors: HUNG HSIN‐CHIA , HUANG MENG‐CHUAN , LEE JANG‐MING , WU DENG‐CHYANG , HSU HON‐KI , WU MING‐TSANG
Published: December 2004

Background:  Several studies have reported the importance of dietary factors in the development of esophageal cancer. The purpose of the present study was to evaluate the effects of several common dietary factors on the risk of squamous cell carcinoma of the esophagus in a Taiwanese population.

Methods:  The association between diet and esophageal cancer was examined in 284 male patients and 480 male controls, who were recruited during 6 year period.

Results:  Consumption of preserved and overheated foods was found to be associated with increased risk of esophageal cancer, whereas intake of fresh fruits, vegetables, and tea was inversely associated with this risk. Men who consumed fermented bean products, salted food and preserved/pickled vegetables more than once a week after age 40 years had a 3.4‐fold risk (95% confidence interval (CI): 1.9–6.2), 2.3‐fold risk (95%CI: 1.2–4.2), and 2.5‐fold risk (95%CI: 1.3–4.5), respectively, compared to men eating these items less than once a week. It was further found that these preserved foods were more strongly associated with esophageal cancer among men who consumed fruit less than once per day than those who consumed fruits one or more times per day.

Conclusions:  These results suggest that a high intake of preserved foods and overheated drinks might increase the risk of esophageal cancer, and intake of fruit, vegetables, and tea might be negatively associated with risk of esophageal cancer. The results also suggest that diet is an important factor in the development of esophageal cancer in Taiwan.
Clinicopathological significance of vascular endothelial growth factor‐C and cyclooxygenase‐2 in esophageal squamous cell carcinoma
Authors: BYEON JEONG‐SIK , JUNG HWOON‐YONG , LEE YUN JUNG , LEE DON , LEE GIN HYUG , MYUNG SEUNG‐JAE , YANG SUK‐KYUN , HONG WEON‐SEON , KIM JIN‐HO , MIN YOUNG IL , KIM JUNG SUN
Published: December 2004

Background:  Vascular endothelial growth factor‐C (VEGF‐C) is a specific growth factor of lymphatics, which is known to play some role in tumor growth and metastasis to lymph nodes and distant organs in various malignancies. The purpose of the present study was to investigate the expression of VEGF‐C in human esophageal squamous cell carcinomas (ESCC) to elucidate its role in tumor progression and lymph node metastasis. Another aim of the study was to investigate the relation between VEGF‐C and cyclooxygenase‐2 (COX‐2) in ESCC.

Methods:  The expression of VEGF‐C and COX‐2 in ESCC was evaluated in 13 endoscopic mucosal resection specimens and in 21 surgical specimens by immunohistochemical staining. Clinical data were obtained from medical records.

Results:  The degree of VEGF‐C expression increased as the depth of primary tumor progressed (r = 0.521, P = 0.002), the stage progressed (r = 0.572, P < 0.001), and the degree of COX‐2 expression increased (r = 0.387, P = 0.024). The VEGF‐C positive rate was different between early cancers in which regional lymph node metastasis was thought to be absent and advanced cancers in which regional lymph node metastases were confirmed after surgery (20.0% vs 100.0%; P < 0.001).

Conclusions:  The VEGF‐C expression in ESCC is related to COX‐2 expression, and VEGF‐C is also associated with the depth of primary tumor, the stage, and probably lymph node metastasis. Thus the investigation of VEGF‐C expression in ESCC may assist in management planning.
Mutational spectrum of K‐ras oncogene among Indian patients with gallbladder cancer
Authors: SINGH MAHENDRA KUMAR , CHETRI KAMAL , PANDEY UDAI BHAN , KAPOOR VINAY KUMAR , MITTAL BALRAJ , CHOUDHURI GOURDAS
Published: December 2004

Background and Aim:  Gallbladder cancer (GBC) is a common abdominal malignancy in India with an obscure etiology. However, long‐standing stones and chronic infection in gallbladder have been suspected as possible etiologic factors. As carcinogenesis complicating chronic inflammation proceeds through the stages of dysplasia and metaplasia, mutation in the K‐ras gene may be an important marker for GBC. The aim of the present study was to detect K‐ras mutation in cytological smears from GBC.

Methods:  Malignant cells were marked on slides of cytological smears obtained from 39 patients with cytologically proven GBC. Marked cells were scraped off and DNA was extracted. Polymerase chain reaction coupled with restriction fragment length polymorphism (RFLP) analysis was performed to detect the point mutation in codon 12 of the K‐ras gene.

Results:  Mutation in codon 12 of K‐ras oncogene was detected in eight (38%) of 21 PCR amplified samples by this technique. Six of eight specimens with K‐ras (codon 12) mutation corresponded to coexisting gallstone disease. Five patients with K‐ras (codon 12) mutation were found to have stage IV malignancy.

Conclusions:  Mutation in codon 12 of the K‐ras oncogene occurs in more than one‐third of GBC in northern India. Its detection from fine‐needle aspirates may prove useful as an adjunct to cytological examination. The presence of this mutation suggests that chronic inflammation may play an etiologic role in gallbladder carcinogenesis.

© 2004 Blackwell Publishing Asia Pty Ltd
Clinical and pathological characteristics of the autoimmune hepatitis and primary biliary cirrhosis overlap syndrome
Authors: SUZUKI YOSHIYUKI , ARASE YASUJI , IKEDA KENJI , SAITOH SATOSHI , TSUBOTA AKIHITO , SUZUKI FUMITAKA , KOBAYASHI MASAHIRO , AKUTA NORIO , SOMEYA TAKASHI , MIYAKAWA YUZO , KUMADA HIROMITSU
Published: December 2004

Background and Aims:  The defining of the autoimmune hepatitis (AIH) and primary biliary cirrhosis (PBC) overlap syndrome as a separate clinicopathological entity has been controversial and temporally and geographically subjective.

Methods:  From 1979 until 2000, 227 patients diagnosed with AIH, PBC or the overlap thereof were treated. Cases with genuine AIH/PBC overlap syndrome were sorted out using close clinical follow up and serial liver biopsies.

Results:  Of the 227 patients, 19 (8.4%) were diagnosed with the AIH/PBC overlap syndrome. They all cleared a score >10 for the diagnosis of AIH, and tested positive for antimitochondrial antibodies during their courses. Long‐term follow up with frequent histological examinations, however, established the diagnosis of AIH/PBC overlap syndrome in only two (0.8%) patients. The most powerful factor distinguishing AIH from PBC was acidophilic bodies in lobules that were detected significantly more frequently in patients with AIH than PBC or spurious overlap syndrome (39/46 [85%]vs 3/85 [4%], P < 0.001). It was more reliable than bile‐duct lesions for the distinction of PBC from AIH.

Conclusions:  Although AIH/PBC overlap syndrome does exist, it is infrequent and needs to be diagnosed carefully using close clinical and histological follow up to enable timely and effective treatment.