bluuebunny/crossref_metadata_2025 huggingface dataset:
Genetic population structure of turbot (Scophthalmus maximus L.) supports the presence of multiple hybrid zones for marine fishes in the transition zone between the Baltic Sea and the North Sea
Authors: Nielsen Einar E. , Nielsen Peter H. , Meldrup Dorte , Hansen Michael M.
Published: December 2004

Genetic population structure of turbot (Scophthalmus maximus L.) in the Northeast Atlantic was investigated using eight highly variable microsatellite loci. In total 706 individuals from eight locations with temporal replicates were assayed, covering an area from the French Bay of Biscay to the Aaland archipelago in the Baltic Sea. In contrast to previous genetic studies of turbot, we found significant genetic differentiation among samples with a maximum pairwise FST of 0.032. Limited or no genetic differentiation was found among samples within the Atlantic/North Sea area and within the Baltic Sea, suggesting high gene flow among populations in these areas. In contrast, there was a sharp cline in genetic differentiation going from the low saline Baltic Sea to the high saline North Sea. The data were explained best by two divergent populations connected by a hybrid zone; however, a mechanical mixing model could not be ruled out. A significant part of the genetic variance could be ascribed to variation among years within locality. Nevertheless, the population structure was relatively stable over time, suggesting that the observed pattern of genetic differentiation is biologically significant. This study suggests that hybrid zones are a common phenomenon for marine fishes in the transition area between the North Sea and the Baltic Sea and highlights the importance of using interspecific comparisons for inferring population structure in high gene flow species such as most marine fishes.
Divergence dates for Malagasy lemurs estimated from multiple gene loci: geological and evolutionary context
Authors: Yoder Anne D. , Yang Ziheng
Published: December 2004

The lemurs of Madagascar are a unique radiation of primates that show an extraordinary diversity of lifestyles, morphologies and behaviours. However, very little is known about the relative antiquity of lemuriform clades due to the lack of terrestrial fossils for the Tertiary of Madagascar. Here, we employ a Bayesian method to estimate divergence dates within the lemuriform radiation using several unlinked gene loci and multiple fossil calibrations outside the lemuriform clade. Two mitochondrial genes (cytochrome oxidase II and cytochromeb), two nuclear introns (transthyretin intron 1 and von Willebrand factor gene intron 11) and one nuclear exon (interphotoreceptor retinoid binding protein, exon 1) are used in separate and combined analyses. The genes differ in taxon sampling and evolutionary characteristics but produce congruent date estimates. Credibility intervals narrow considerably in combined analyses relative to separate analyses due to the increased amount of data. We also test the relative effects of multiple vs. single calibration points, finding that, when only single calibration points are employed, divergence dates are systematically underestimated. For the mitochondrial DNA data set, we investigate the effects of sampling density within the mouse lemur radiation (genusMicrocebus). When only two representative species are included, estimated dates throughout the phylogeny are more recent than with the complete‐species sample, with basal nodes less affected than recent nodes. The difference appears to be due to the manner in which priors on node ages are constructed in the two analyses. In nearly all analyses, the age of the lemuriform clade is estimated to be approximately 62–65 Ma, with initial radiation of mouse lemurs and true lemurs (genusEulemur) occurring approximately 8–12 Ma. The antiquity of the mouse lemur radiation is surprising given the near uniform morphology among species. Moreover, the observation that mouse lemurs and true lemurs are of similar ages suggests discrepancies in rates of morphological, behavioural and physiological evolution in the two clades, particularly with regard to characteristics of sexual signalling. These differences appear to correlate with the nocturnal vs. diurnal lifestyles, respectively, of these two primate groups.
Archaea: an archetype for replication initiation studies?
Authors: Kelman Lori M. , Kelman Zvi
Published: December 2004

Whereas the process of DNA replication is fundamentally conserved in the three domains of life, the archaeal system is closer to that of eukarya than bacteria. In the time since the complete genome sequences of several members of the archaeal domain became available, there has been a burst of research on archaeal DNA replication. These studies have led to both expected and surprising findings. This review summarizes the search for origins of replication in archaea, and our current knowledge of initiation, the process by which replication origins are recognized, the DNA molecule is unwound and the replicative helicase is loaded onto the DNA in preparation for DNA synthesis. The similarities and differences of the initiation process in archea, bacteria and eukarya are also summarized.
Phase variation of the 987P‐like CS18 fimbriae of human enterotoxigenic Escherichia coli is regulated by site‐specific recombinases
Authors: Honarvar Shaya , Choi Byung‐Kwon , Schifferli Dieter M.
Published: December 2004

The gene cluster of the CS18 (PCFO20) fimbriae of human enterotoxigenic Escherichia coli (ETEC) was found to include seven genes (fotA to fotG) that are similar to each of the seven structural and export proteins of the 987P fimbriae. However, no analogous gene to the fasH regulatory gene, which is located at the 3′ end of the 987P gene cluster and encodes an AraC‐like activator of transcription, could be detected. Surprisingly, two novel genes (fotS and fotT) encoding proteins similar to the site‐specific recombinases of the type 1 fimbriae (FimB and FimE) were identified at the 5′ end of the fot gene cluster. These genes were shown to be required for the catalysis of a 312 bp‐inversion just upstream of fotA. The inversion determines CS18 fimbrial phase variation. FotS participates in inverting the 312 bp‐segment in both the ON and OFF orientation, whereas FotT has a bias for the OFF oriented recombination. Similar regulators of fimbriation by phase variation were described in uropathogenic and commensal Enterobacteriaceae. In contrast, only AraC‐like transcriptional activators were previously described as regulators of the intestinal colonization factors of human ETEC isolates. Thus, the CS18 and 987P gene clusters encode similar components for fimbrial biogenesis but different types of regulators for fimbriation. The combination of blocks of genes encoding similar structural products but different regulatory proteins underlines how modular DNA rearrangements can evolve by serving pathogen diversification. Acquisition of a phase variation module to regulate fimbrial genes is proposed to be beneficial for the adaptation and transmission of pathogens.
Efficient sporulation in Clostridium difficile requires disruption of the σK gene
Authors: Haraldsen Jeralyn D. , Sonenshein Abraham L.
Published: December 2004

A 14.6 kb prophage‐like insertion, termed skinCd, was found to interrupt the sigK gene, which encodes an RNA polymerase sigma factor essential for sporulation, in six strains of Clostridium difficile. Until now, Bacillus subtilis was the only spore‐former shown to carry such an insertion, and the presence of the insertion is not required for efficient sporulation in this organism. The B. subtilis and C. difficile skin elements proved to be divergent in sequence, inserted at different sites within the sigK gene and in opposite orientations. The skinCd element was excised from the chromosome specifically during sporulation, forming a circular molecule. Two natural isolates of C. difficile lacked the skinCd element and were defective in sporulation. When a merodiploid strain was created that carries both interrupted and uninterrupted versions of the sigK gene, the cells became Spo–, showing that the uninterrupted gene is dominant and inhibits sporulation. C. difficile sigK genes, whether skinCd+ or skinCd–, lack the N‐terminal pro‐sequence found in all other sigK genes studied to date. Thus, regulated excision of skinCd appears to be a critical mechanism for achieving proper temporal activation of σK.
Regulatory network of acid resistance genes in Escherichia coli
Authors: Masuda Nobuhisa , Church George M.
Published: December 2004

Overexpression of the response regulator EvgA confers an acid‐resistant phenotype to exponentially growing Escherichia coli. This acid resistance is partially abolished by deletion of ydeP, yhiE or ydeO, genes induced by EvgA overexpression. Microarray analysis identified two classes of operons (genes). The first class contains seven operons induced by EvgA overexpression in the absence of ydeO, an AraC/XylS regulator gene. The second class contains 12 operons induced by YdeO overexpression. Operons in the second class were induced by EvgA overexpression only in the presence of ydeO. EvgA is likely to directly upregulate operons in the first class, and indirectly upregulate operons in the second class via YdeO. Analysis using the motif‐finding program alignace identified an 18 bp inverted repeat motif in six upstream regions of all seven operons directly regulated by EvgA. Gel mobility shift assays showed the specific binding of EvgA to the six sequences. Introduction of mutations into the inverted repeats upstream of ydeP and b1500‐ydeO resulted in reduction in EvgA‐induced ydeP and ydeO expression and acid resistance. These results suggest that EvgA binds to the inverted repeats and upregulates the downstream genes. Overexpression of YdeP, YdeO and YhiE conferred acid resistance to exponentially growing cells, whereas GadX overexpression did not. Microarray analysis also identified several GadX‐activated genes. Several genes induced by overexpression of YdeO and GadX overlapped; however, yhiE was induced only by YdeO. The acid resistance induced by YdeO overexpression was abolished by deletion of yhiE, gadC, slp‐yhiF, hdeA or hdeD, genes induced by YdeO overexpression, suggesting that several genes orchestrate YdeO‐induced acid resistance. We propose a model of the regulatory network of the acid resistance genes.
The avilamycin resistance determinants AviRa and AviRb methylate 23S rRNA at the guanosine 2535 base and the uridine 2479 ribose
Authors: Treede Irina , Jakobsen Lene , Kirpekar Finn , Vester Birte , Weitnauer Gabriele , Bechthold Andreas , Douthwaite Stephen
Published: December 2004

Avilamycin is an orthosomycin antibiotic that has shown considerable potential for clinical use, although it is presently used as a growth promoter in animal feed. Avilamycin inhibits bacterial protein synthesis by binding to the 50S ribosomal subunit. The ribosomes of the producer strain, Streptomyces viridochromogenes Tü57, are protected from the drug by the action of three resistance factors located in the avilamycin biosynthetic gene cluster. Two of the resistance factors, aviRa and aviRb, encode rRNA methyltransferases that specifically target 23S rRNA. Recombinant AviRa and AviRb proteins retain their activity after purification, and both specifically methylate in vitro transcripts of 23S rRNA domain V. Reverse transcriptase primer extension indicated that AviRa is an N‐methyltransferase that targets G2535 within helix 91 of the rRNA, whereas AviRb modified the 2′‐O‐ribose position of nucleotide U2479 within helix 89. MALDI mass spectrometry confirmed the exact positions of each of these modifications, and additionally established that a single methyl group is added at each nucleotide. Neither of these two nucleotides have previously been described as a target for enzymatic methylation. Molecular models of the 50S subunit crystal structure show that the N−1 of the G2535 base and the 2′‐hydroxyl of U2479 are separated by approximately 10 Å, a distance that can be spanned by avilamycin. In addition to defining new resistance mechanisms, these data refine our understanding of the probable ribosome contacts made by orthosomycins and of how these antibiotics inhibit protein synthesis.
Architecture of the ParF•ParG protein complex involved in prokaryotic DNA segregation
Authors: Barillà Daniela , Hayes Finbarr
Published: December 2004

The mechanism by which low copy number plasmids are segregated at cell division involves the concerted action of two plasmid‐encoded proteins that assemble on a centromere‐like site. This study explores the topology of the DNA segregation machinery specified by the parFG locus of TP228, a partition system which is phylogenetically distinct from more well‐characterized archetypes. A variety of genetic, biochemical and biophysical strategies revealed that the ParG protein is dimeric. ParF, which is more closely related to the cell division regulator MinD than to the prototypical ParA partition protein of plasmid P1, is instead multimeric and its polymeric state appears to be modulated by ATP which correlates with the proposed ATP‐binding activity of ParF. ParG interacts in a sequence‐specific manner with the DNA region upstream of the parFG locus and this binding is modulated by ParF. Intriguingly, the ParF and ParG proteins form at least two types of discrete complex in the absence of this region suggesting that the assembly dynamics of these proteins onto DNA is intricate.
The Erwinia chrysanthemi phoP‐phoQ operon plays an important role in growth at low pH, virulence and bacterial survival in plant tissue
Authors: Llama‐Palacios Arancha , López‐Solanilla Emilia , Poza‐Carrión César , García‐Olmedo Francisco , Rodríguez‐Palenzuela Pablo
Published: December 2004

We have studied the role of acidic pH as a barrier for the colonization of the plant apoplast by Erwinia chrysanthemi. A minitransposon containing a promoterless reporter gene, gus, was used for random mutagenesis of the bacterial genome. An acid‐sensitive mutant, named BT119, was isolated and had the following differential features with respect to the wild‐type strain: (i) inability to grow at pH ≤ 5.5; (ii) decreased survival at acid pH and in plant tissues; (iii) increased susceptibility to antimicrobial peptides; (iv) decreased virulence in chicory leaves and pear fruits; (v) reduced polygalacturonase production; and (vi) reduced ability to alkalinize chicory tissues after infection. The sequence of the interrupted gene was highly similar to the phoQ gene, which is involved in environmental sensing in several bacteria, such as Yersinia pseudotuberculosis, Erwinia carotovora, Salmonella typhimurium and Escherichia coli and thus, this designation was used for the E. chrysanthemi system. This gene was induced at low Mg2+ concentrations and in planta. These results suggest that E. chrysanthemi PhoP‐PhoQ system plays an important role in bacterial survival in plant tissues during the initial infection stages.
Self‐association of EPEC intimin mediated by the β‐barrel‐containing anchor domain: a role in clustering of the Tir receptor
Authors: Touzé Thierry , Hayward Richard D. , Eswaran Jeyanthy , Leong John M. , Koronakis Vassilis
Published: December 2004

Outer membrane intimin directs attachment of enteropathogenic Escherichia coli (EPEC) via its Tir receptor in mammalian target cell membranes. Phosphorylation of Tir triggers local actin polymerization and the formation of ‘pedestal‐like’ pseudopods. We demonstrate that the intimin protein contains three domains, a flexible N‐terminus (residues 40–188), a central membrane‐integrated β‐barrel (189–549), and a tightly folded Tir‐binding domain (550–939). Intimin was shown by electron microscopy to form ring‐like structures with a ∼7 nm external diameter and an electron dense core, and to form channels of 50picoSiemens conductance in planar lipid bilayers. Gel filtration, multiangle light scattering and cross‐linking showed that this central β‐barrel membrane‐anchoring domain directs intimin dimerization. Isothermal titration calorimetry revealed a high affinity, single‐binding site interaction of 2 : 1 stoichiometry between dimeric intimin and Tir, and modelling suggests that this interaction determines a reticular array‐like superstructure underlying receptor clustering. In support of this model, actin rearrangement induced in Tir‐primed cultured cells by intimin‐containing proteoliposomes was dependent on the concentration of both intimin and Tir, and co‐localized with clustered phosphorylated Tir.
Tomographic reconstruction of treponemal cytoplasmic filaments reveals novel bridging and anchoring components
Authors: Izard Jacques , McEwen Bruce F. , Barnard Rita M. , Portuese Thomas , Samsonoff William A. , Limberger Ronald J.
Published: December 2004

An understanding of the involvement of bacterial cytoplasmic filaments in cell division requires the elucidation of the structural organization of those filamentous structures. Treponemal cytoplasmic filaments are composed of one protein, CfpA, and have been demonstrated to be involved in cell division. In this study, we used electron tomography to show that the filaments are part of a complex with a novel molecular organization that includes at least two distinct features decorating the filaments. One set of components appears to anchor the filaments to the cytoplasmic membrane. The other set of components appears to bridge the cytoplasmic filaments on the cytoplasmic side, and to be involved in the interfilament spacing within the cell. The filaments occupy between 3 and 18% of the inner surface of the cytoplasmic membrane. These results reveal a novel filamentous molecular organization of independent filaments linked by bridges and continuously anchored to the membrane.
The function of RNase G in Escherichia coli is constrained by its amino and carboxyl termini
Authors: Deana Atilio , Belasco Joel G.
Published: December 2004

RNase G is a homologue of the essential Escherichia coli ribonuclease RNase E. Whereas RNase E plays a key role in the degradation of mRNA and the processing of tRNA and rRNA in E. coli, the biological functions of RNase G appear more limited. We report here that this difference in function is not merely a consequence of the significantly lower cellular concentration of RNase G, but also reflects differences in the intrinsic properties of these ribonucleases, as overproducing wild‐type RNase G at a level up to 20 times the usual cellular concentration of RNase E cannot normally compensate for the absence of RNase E in E. coli. Instead, RNase G can sustain significant growth of RNase E‐deficient E. coli cells only when it bears an unnatural extension at its amino terminus (e.g. MRKGINM) or carboxyl terminus (e.g. GHHHHHH). These extensions presumably enable RNase G to cleave critically important cellular RNAs whose efficient processing or degradation ordinarily requires RNase E. That extending the amino terminus of RNase G restores growth to E. coli cells lacking RNase E without detectably improving tRNA processing suggests that RNase E is not essential for tRNA production and is required for cell growth because it plays an indispensable role in the maturation or decay of essential E. coli RNAs other than tRNA.
Rectal sensorimotor characteristics in female patients with idiopathic constipation with or without paradoxical sphincter contraction
Authors: Sloots C. E. J. , Felt‐Bersma R. J. F.
Published: December 2004

Abstract Patients with chronic constipation fulfilling the Thompson criteria can show paradoxical sphincter contraction. Aim of this study was to evaluate rectal sensorimotor characteristics in patients with constipation with or without paradoxical sphincter contraction. Thirty female patients with chronic constipation and 22 female controls were investigated with anal manometry and rectal barostat. Paradoxical sphincter contraction was shown with manometry as a paradoxical increase of anal pressure during straining. Visceral sensitivity and compliance were tested by intermittent and continuous pressure‐controlled distension. Patients were classified according to their sensations and compliance into normal, hypersensitive, reduced compliant, insensitive or excessive compliant rectum. Postprandial rectal response (PRR) and phasic volume events (PVEs) were registered for 1 h after a 600‐kCal meal. Paradoxical sphincter contraction was found in 13 (43%) patients. In these patients, rectal sensitivity scores were higher (P = 0.045) than in patients without paradoxical contractions, but rectal compliance was not different. In 90% of patients an abnormal rectal sensitivity or compliance was found: excessively compliant in 35%, reduced compliant in 10%, hypersensitive in 27% and hyposensitive in 17%. Both patients with constipation (11%;P = 0.042) and controls (25%;P = 0.002) exhibited the presence of a postprandial rectal response. This response was not significantly different between idiopathic constipation, paradoxical sphincter contraction and controls. Patients with rectal hypersensitivity had lower response than other patients (P = 0.04). Patients with constipation had fewer basal PVEs compared controls (P = 0.03). Postprandial PVEs increased in both patients (P = 0.014) and controls (P < 0.001). Postprandial rectal response and PVE were not different in patients with or without paradoxical sphincter contraction. A total of 90% of female patients with idiopathic constipation show an abnormality in rectal sensation or compliance. The postprandial rectal response was comparable between patients with constipation and controls, however, PVEs were diminished. Patients with paradoxical sphincter contraction had higher rectal sensitivity but an unaltered compliance and postprandial rectal response. Future trials should investigate whether the classification of rectal abnormalities in patients with constipation has clinical importance.
Does ICC pacing require functional gap junctions between ICC and smooth muscle in mouse intestine?
Authors: Schultz T. , Daniel V. , Daniel E. E.
Published: December 2004

Abstract We tested the hypothesis that interstitial cells of Cajal (ICC) pace longitudinal and circular muscle of mouse intestine through gap junctions. Carbenoxolone (10−6, 10−5, 10−4 mol L−1), an inhibitor of gap junction conductance, was applied to segments of longitudinal or circular muscle with contractions driven by ICC after inhibition of nerve function by tetrodotoxin (10−6 mol L−1) and L‐NOARG (10−4 mol L−1). Carbenoxolone concentration‐ and time‐dependently inhibited the amplitude of contraction (0.2–1.5 g in controls) of segments of longitudinal muscle, but had no effect on the frequency of contractions (from 36–54 min). It also inhibited the amplitude of contractions of circular muscle segments and reduced the frequency slightly at 10−4 mol L−1. Carbenoxolone inhibited tonic contractions of longitudinal but not circular segments to 60 mmol L−1 KCl, suggesting that it directly inhibited contractions of longitudinal muscle. The responses to pacing by electrical field stimulation (40 V cm−1, 50–100 ms, 1 Hz) after block of nerve function were reduced insignificantly in amplitude, and not in frequency in both longitudinal and circular segments. We conclude that it is likely that only gap junctions within circular muscle are involved in pacing of muscle by ICC. Carbenoxolone also has effects on muscle contractility in longitudinal muscle.
Endogenous endothelin increases gallbladder tone and leads to acute cholecystitis in the Australian possum
Authors: Al‐Jiffry B. O. , Shaffer E. A. , Woods C. M. , Menadue M. , Young F. , Oliver J. , Thomas A. C. , Toouli J. , Saccone G. T. P.
Published: December 2004

Abstract  Endothelins are bioactive peptides produced by gallbladder epithelial cells. We aimed to determine the role of endothelins in acute cholecystitis. Escherichia coli lipopolysaccharide vs saline (sham) was instilled into the gallbladder lumen of Australian possums. Some animals received the non‐selective endothelin antagonist, tezosentan. At 4 or 24 h, plasma and gallbladder endothelins and white blood cell count (WBCC) were determined. Acute cholecystitis was assessed using a histopathology score. In other animals gallbladder tone was determined. At 4h, a dose‐dependent 60‐fold increase in gallbladder endothelin level occurred (P = 0.001) but other parameters remained comparable with sham animals. Epithelial cells were endothelin‐immunoreactive. At 24 h, the WBCC rose (P < 0.007), and severe cholecystitis developed. Gallbladder but not plasma endothelin levels remained elevated. Tezosentan pre‐treatment resulted in a histologically normal gallbladder, but the WBCC and gallbladder endothelin levels were elevated. Lipopolysaccharide or saline instillation also caused a time‐dependent increase in gallbladder tone over 4 h (P < 0.001), but not in control animals. This increase was reduced by tezosentan treatment. Gallbladder endothelin production is an early event in acute cholecystitis, increases gallbladder tone and plays a crucial role in the inflammatory process.
Capillary and arterial cerebral amyloid angiopathy in Alzheimer's disease: defining the perivascular route for the elimination of amyloid β from the human brain
Authors: Preston S. D. , Steart P. V. , Wilkinson A. , Nicoll J. A. R. , Weller R. O.
Published: December 2004

Accumulation of amyloid β (Aβ) in the extracellular spaces of the cerebral cortex and in blood vessel walls as cerebral amyloid angiopathy is a characteristic of Alzheimer's disease (AD) and the ageing human brain. Studies in animals suggest that Aβ is eliminated from the brain either directly into the blood or along perivascular interstitial fluid drainage channels. The aim of the present study is to define the perivascular route for the drainage of Aβ from the human brain. Smears and paraffin sections of post‐mortem cortical tissue from 17 cases of AD and from two controls were stained with thioflavin and for Aβ by immunohistochemistry. Histology and confocal microscopy showed that deposits of Aβ in the cortical parenchyma were continuous with Aβ in capillary walls but Aβ in artery walls was not in continuity with Aβ in brain parenchyma. Quantitative studies supported these observations. The results of this study suggest that when Aβ is eliminated from the extracellular spaces of the human brain by the perivascular route, it enters pericapillary spaces and from there drains along the walls of cortical arteries to leptomeningeal arteries. Factors such as overproduction of Aβ, entrapment of Aβ in drainage pathways and poor drainage of Aβ due to functional changes in ageing arteries might result in the failure of elimination of Aβ from the ageing brain and play a major role in the pathogenesis of AD. Such factors might affect therapies for AD that entail administration of anti‐Aβ antibodies to eliminate Aβ from the human brain.
Time‐course phosphorylation of the mitogen activated protein (MAP) kinase group of signalling proteins and related molecules following middle cerebral artery occlusion (MCAO) in rats
Authors: Krupinski J. , Slevin M. , Marti E. , Catena E. , Rubio F. , Gaffney J.
Published: December 2004

Recovery from the debilitating effects of ischaemic stroke is variable and unpredictable. To maximize patient recovery, a greater understanding of the molecular mechanisms involved in regulating both apoptosis and the repair processes affecting neuronal protection, particularly in the penumbra region, is desirable. We have previously shown, in human subjects, the increased expression of several growth factors soon after stroke, together with appearance of tyrosine phosphorylated proteins, in particular mitogen activated protein (MAP) kinase (ERK1/2). In this paper, we demonstrate a relatively short‐lasting (< 12 h), but substantial increase in expression of phosphorylated proteins, in particular, p‐JNK (phosphorylated c‐Jun N‐terminal kinase) and p‐ERK1/2 in both the grey matter penumbra and infarcted tissue of rats, following permanent middle cerebral artery occlusion. p‐ERK1/2 was associated with neurones and endothelial cells in the vicinity of the infarct while p‐JNK was mainly expressed in neurones. Expression of both p‐MEK3/6 and p‐p38 MAP kinase was also increased in neurones and astroglia, within 1 h of infarction, p‐p38 remaining elevated and associated with neurones and in particular with astroglia in the penumbra region for > 4 days. Evidence suggests that short‐term activation of these proteins may be detrimental to neuronal survival, while their transient nature makes them unlikely to support angiogenesis, revascularization and reperfusion over a period of days and weeks. On the other hand, short–medium‐term up‐regulation of neuronal p‐JNK, p‐c‐Jun, p‐Stat‐1 and p‐p38 might be a factor in the regulation of apoptosis. Therapeutic manipulation of phosphorylation/activation of these and other important signalling intermediates might form the basis of an appropriate treatment to maximize revascularization and neuronal protection after ischaemic stroke.
Effects of four generations of density-dependent selection on life history traits and their plasticity in a clonally propagated plant
Authors: Van Kleunen M. , Fischer M.
Published: December 2004

Life history evolution of many clonal plants takes place with long periods of exclusively clonal reproduction and under largely varying ramet densities resulting from clonal reproduction. We asked whether life history traits of the clonal herb Ranunculus reptans respond to density-dependent selection, and whether plasticity in these traits is adaptive. After four generations of exclusively clonal propagation of 16 low and 16 high ramet-density lines, we studied life history traits and their plasticities at two test ramet-densities. Plastic responses to higher test-density consisted of a shift from sexual to vegetative reproduction, and reduced flower production, plant size, branching frequency, and lengths of leaves and internodes. Plants of high-density lines tended to have longer leaves, and under high test-density branched less frequently than those of low-density lines. Directions of these selection responses indicate that the observed plastic branching response is adaptive, whereas the plastic leaf length response is not. The reverse branching frequency pattern at low test-density, where plants of high-density lines branched more frequently than those of low-density lines, indicates evolution of plasticity in branching. Moreover, when grown under less stressful low test-density, plants of high-density lines tended to grow larger than the ones of low-density lines. We conclude that ramet density affects clonal life-history evolution and that under exclusively clonal propagation clonal life-history traits and their plasticities evolve differently at different ramet densities.
Fitness-associated recombination on rugged adaptive landscapes
Authors: Hadany L. , Beker T.
Published: December 2004

A negative correlation between fitness and recombination rates seems to exist in various organisms. In this article we suggest that a correlation of that kind may play an important role in the evolution of complex traits. We study the effects of such fitness-associated recombination (FAR) in a simple two-locus deterministic model, as well as in a multi-loci NK rugged adaptive landscape. In both models studied, FAR results in faster adaptation and higher average population fitness, compared with uniform-rate recombination.
Morphological and microsatellite differentiation in Melospiza melodia (Aves) at a microgeographic scale
Authors: Chan Y. , Arcese P.
Published: December 2004

Geographical variation in microsatellite allele frequencies and morphology were compared for five subspecies of Melospiza melodia (song sparrow; M. m. samuelis, M. m. maxillaris, M. m. pusillula, M. m. gouldii, and M. m. heermanni) in 14 populations in the San Francisco Bay region to (a) assess divergence based on these estimates and (b) test the hypothesis that drift is responsible for morphological and genetic divergence. Morphological differentiation between subspecies was high despite low differentiation at microsatellite loci, indicating high gene flow and large effective population sizes. Low concordance of morphological and genetic estimates of divergence suggests that selection or phenotypic plasticity in morphology has caused morphological differentiation among the subspecies.
Characteristics of Lactoferrin Receptor in Bovine Intestine: Higher Binding Activity to the Epithelium Overlying Peyer's Patches
Authors: Talukder M. J. R. , Takeuchi T. , Harada E.
Published: December 2004

Several lines of evidence have recently demonstrated the occurrence of specific lactoferrin (Lf) receptors in different cells. We report here, for the first time, the characteristics of binding, and distribution of Lf receptors in the bovine intestinal tract with special emphasis on the epithelium overlying Peyer's patches (EOPP). Brush‐border membrane vesicles (BBMV) were prepared from the mucosa of duodenum, jejunum, ileum, colon, EOPP in jejunum and EOPP in ileum. Receptor binding assays were carried out using 125I‐labelled bovine Lf. Specific and saturable Lf receptors were found in BBMV of all the intestinal segments examined. Non‐linear regression and Scatchard plot analyses clearly revealed that EOPP had the highest binding maximal (Bmax), and lowest in colon. The maximum dissociation constant (Kd) 3.74 μm was in the ileum. We found that bovine transferrin competed with Lf for the same binding site of receptors. In contrast, no binding of bovine serum albumin occurred. It was concluded that Lf receptors in the mucosal lining are attributable to mediate multifunctional activities of Lf in the gut, especially in the EOPP.
Long‐term Follow‐up of Manipulative Treatment in a Horse with Back Problems
Authors: Faber M. J. , Van Weeren P. R. , Schepers M. , Barneveld A.
Published: December 2004

In order to objectively quantify the effect of manipulation on back‐related locomotion anomalies in the horse, a recently developed kinematic measuring technique for the objective quantification of thoracolumbar motion in the horse was applied in a dressage horse that was suffering from a back problem. In this horse, clinically, a right‐convex bending (scoliosis) from the 10th thoracic vertebra to the second lumbar vertebra was diagnosed. As a result, there was a marked asymmetric movement of the thoracolumbar spine. Functionally, there was severe loss of performance. Thoracolumbar motion was measured in terms of ventrodorsal flexion, lateral flexion, and axial rotation using an automated gait analysis system. Measurements were repeated before and 2 days after treatment, before the second treatment 3 weeks later, and at 4 weeks and 8 months after the second treatment to assess long‐term effect. At the same time, performance of the horse was assessed subjectively by the trainer as well. Symmetry of movement improved dramatically after the first treatment. After this, there was a slight decrease in symmetry, but 8 months after the last treatment the symmetry indexes for the various joints were still considerably better than during the first (pre‐treatment) measuring session. Subjectively, the trainer did not notice improvement until after measurement session 4. Between sessions 4 and 5 (at 4 weeks and 8 months after the second treatment) there was a change of trainer. The new trainer did not report any back problem, and succeeded in bringing the horse back to its former level in competition. It is concluded that manipulation had a measurable influence on the kinematics of the thoracolumbar spine. However, it is recognized that an improvement in symmetry of motion is not equivalent to clinical improvement and that other measures, such as changes in management, may be more decisive.
The Effect of Orally Administered Marbofloxacin on the Pharmacokinetics of Theophylline
Authors: Hirt R. A. , Teinfalt M. , Dederichs D. , Van Den Hoven R.
Published: December 2004

As certain quinolones can interfere with the metabolism of theophylline by competitive inhibition of the hepatic microsomal cytochrome P450 system, concomitant use of these drugs with theophylline could result in theophylline toxicity. This study investigated the effect of orally administered marbofloxacin (2 and 5 mg/kg each once daily) on steady‐state plasma pharmacokinetics of theophylline after concomitant oral administration of a sustained release theophylline preparation in dogs. Marbofloxacin caused some alteration in theophylline metabolism. A 2 mg/kg dose of marbofloxacin did not clearly result in an increased area under the concentration – time curve (AUC) or decreased clearance of theophylline, but at a dose of 5 mg/kg, a statistically significant increase in AUC and a decrease in the total clearance of theophylline was found. The 26% reduction in theophylline clearance is probably not clinically significant in healthy dogs, but for dogs with renal impairment, there might be a chance of theophylline accumulation when dosed concomitantly with marbofloxacin.
The Variations of White Blood Cell Count in Lipizzan Horses
Authors: Čebulj‐Kadunc N. , Kosec M. , Cestnik V.
Published: December 2004

Total and differential leucocyte counts (lymphocytes, neutrophils, monocytes, eosinophils and basophils) were measured in 140 stallions, 101 mares and 25 foals of Lipizzan breed. The values fell in the normal ranges for warm‐blooded horses. Differences between mares and stallions were not significant with the exception of foals, having higher white blood cell, neutrophil, lymphocyte, monocyte and basophil values in females than in males. Foals exhibited an age‐related increase of total leucocyte count during the first 4 months of life, accompanied by a decrease in neutrophil and increase in lymphocyte and eosinophil counts. In mares and stallions, the total number of leucocytes, lymphocytes, monocytes and basophils significantly decreased but the number of neutrophils and eosinophils remained almost unchanged with age gain.
Effect of a chitin derivative in combination with cleaning and preservation solutions for contact lenses on adherence of fungi
Authors: Rotman S. , Sandovsky‐Losica Hana , Sionov E. , Segal Esther
Published: December 2004

Summary The objective of the study was to evaluate the effect of supplementation of a chitin soluble extract (CSE) to clinically used commercial contact lenses’ cleaning/preservation solutions on adherence of Aspergillus niger and Candida albicans to contact lenses. CSE (25 mg ml−1) was added to Solocare® or Oxysept®. Adherence of A. niger or C. albicans to contact lenses was assessed by exposing lenses to fungi in test solutions and enumeration of fungal colony forming unit. The study included three parts: (i) the disinfecting and adherence‐inhibiting effect of Solocare and Oxysept; (ii) the adherence‐inhibiting effect of CSE; (iii) the effect of Solocare + CSE or Oxysept + CSE on the fungal adherence to contact lenses. The experiments showed that: (i) Solocare had a significant disinfecting effect on A. niger and C. albicans while that of Oxysept was only minimal. (ii) Neither Solocare nor Oxysept had an inhibitory effect on the fungal adherence. (iii) CSE inhibited significantly the adherence of A. niger and C. albicans. (iv) Addition of CSE to Solocare or Oxysept resulted in almost complete inhibition of adherence. Supplementing CSE to lenses’ maintenance solutions increases their antifungal potential by adding anti‐adherence activity to the disinfecting effect of these solutions, bearing the potential to serve as a prophylactic means.
In vitro antimicrobial activity of olive leaves. Antimikrobielle Wirksamkeit von Olivenblättern in vitro
Authors: Markin D. , Duek L. , Berdicevsky I.
Published: December 2004

We investigated the antimicrobial effect of olive leaves against bacteria and fungi. The microorganisms tested were inoculated in various concentrations of olive leaf water extract. Olive leaf 0.6% (w/v) water extract killed almost all bacteria tested, within 3 h. Dermatophytes were inhibited by 1.25% (w/v) plant extract following a 3‐day exposure whereas Candida albicans was killed following a 24 h incubation in the presence of 15% (w/v) plant extract. Olive leaf extract fractions, obtained by dialysis, that showed antimicrobial activity consisted of particles smaller than 1000 molecular rate cutoffs. Scanning electron microscopic observations of C. albicans, exposed to 40% (w/v) olive leaf extract, showed invaginated and amorphous cells. Escherichia coli cells, subjected to a similar treatment but exposed to only 0.6% (w/v) olive leaf extract showed complete destruction. These findings suggest an antimicrobial potential for olive leaves.
Pharmacokinetic investigation of oral itraconazole in stratum corneum level of tinea pedis
Authors: Morimoto K , Tanuma H , Kikuchi I , Kusunoki T , Kawana S
Published: December 2004

In the present study, the authors administered 100 mg itraconazole (ITCZ) twice daily for a period of 1 week to six patients with hyperkeratotic type tinea pedis, and examined its efficacy, safety profile, and usefulness. ITCZ concentration in stratum corneum was also measured to examine the mobility of the drug into the affected site of planta pedis. ITCZ concentration in the stratum corneum of the affected part was first detected at 1 week after the completion of administration, gradually increased over time, and peaked at 3 weeks, with the sum of ITCZ and hydroxyitraconazole (OH‐ITCZ) amounting to 163.7 ng g−1 on a average. It then gradually decreased to a total sum of 10.3 ng g−1 on average at 8 weeks following the completion of administration. When compared with the geometric mean minimum inhibitory concentration (MIC) of ITCZ against fresh clinical isolates of dermatophytes (Trichophyton rubrum) (0.06 μg ml−1), the stratum corneum ITCZ concentration in this study was 2.1‐fold of the geometric mean MIC at 2 weeks following the completion of administration, and 2.4‐fold at 4 weeks. Although ITCZ does not produce therapeutic effectiveness (fungistasis) during the period of administration, it starts appearing at 2 weeks after the completion of administration, and after it peaks out at 3–4 weeks, clinical symptoms started improving. These results suggest that satisfying effects can be achieved in a short‐term oral ITCZ at a dose of 100 mg twice daily for a period of 1 week in cases of hyperkeratotic type tinea pedis.
Diarrhea associated with lansoprazole
Authors: MUKHERJEE SANDEEP
Published: December 2004

Abstract  Lansoprazole is a proton pump inhibitor widely prescribed for gastroesophageal reflux and benign peptic ulcer disease. According to the manufacturer's package insert (TAP Pharmaceuticals, Lake Forest, IL, USA), the most common side‐effects are diarrhea, headache and abdominal pain, which occur in approximately 3% of patients and are reversible with drug discontinuation. An unusual case of microscopic colitis is reported in a previously asymptomatic patient who developed new‐onset diarrhea after initiation of lansoprazole. The case is reviewed and possible mechanisms of diarrhea secondary to proton pump inhibitors are discussed.

© 2003 Blackwell Publishing Asia Pty Ltd
Endoscopic hemostasis: Safe treatment for peptic ulcer patients aged 80 years or older?
Authors: YAMAGUCHI YASUHARU , YAMATO TARO , KATSUMI NAOYA , MOROZUMI KATSURO , ABE TAKASHI , ISHIDA HITOSHI , TAKAHASHI SHIN’ICHI
Published: December 2004

Background and Aim: Recently, the number of peptic ulcer patients aged 80 years or older has been increasing. However, little information is available concerning therapeutic endoscopy for these patients. The objective of this study was to evaluate the efficacy of endoscopic hemostasis for peptic ulcer bleeding in patients aged 80 years or older.

Methods: In this 7‐year study, bleeding peptic ulcer patients were divided into group A (≥80 years old) and group B (<80 years), for which prospective data, endoscopic findings and outcomes of endoscopic treatment were compared.

Results: Of the 459 patients who underwent endoscopic hemostasis for peptic ulcer bleeding, the 42 patients (average age 84 ± 3 years) in group A had a significantly higher incidence of concomitant disease, lower hemoglobin, transfusional requirement over 800 mL and lower serum albumin than the 417 patients (average age 55 ± 13 years) in group B. Significantly more patients in group A had large gastric ulcers. More patients in group A had ulcers located at the proximal third of the stomach, which is technically difficult to treat endoscopically. Nevertheless, all patients in groups A and B underwent initial hemostasis successfully. The rebleeding rate was not significantly different between group A and B. Neither group had hospital deaths nor complications related to endoscopic procedures.

Conclusions: Endoscopic hemostasis for peptic ulcer bleeding in patients aged 80 years or older is effective and safe. Increasing age may no longer be a risk factor for rebleeding and hospital death after endoscopic hemostasis for peptic ulcer bleeding.

© 2003 Blackwell Publishing Asia Pty Ltd
Loss of heterozygosity of chromosome 8p and 11p in the dysplastic nodule and hepatocellular carcinoma
Authors: KAHNG YOON SEOB , LEE YOUN SOO , KIM BYUNG KEE , PARK WON SANG , LEE JUNG YONG , KANG CHANG SUK
Published: December 2004

Background and Aim: In hepatocarcinogenesis, both de novo and multistep pathways have been suggested, and in the latter a dysplastic nodule is the proposed precancerous lesion. But genetic changes involved in the dysplastic nodule are not well understood. In this study, we tried to determine whether allelic loss of the chromosome 8p and/or 11p could be involved in the development of the dysplastic nodule and/or hepatocellular carcinoma. Platelet‐derived growth factor‐receptor beta‐like tumor suppressor gene (PRLTS) and deletion in liver cancer‐1 tumor suppressor gene are located at 8p21.3‐p22. The hepatitis B virus integration site and WT1 tumor suppressor gene are located at 11p13.

Methods: We therefore studied loss of heterozygosity (LOH) of chromosome 8p21.3–p22 and 11p13 in 22 dysplastic nodules and 21 hepatocellular carcinomas. The samples, microdissected from paraffin‐embedded tissues, were examined using a polymerase chain reaction‐based LOH assay using microsatellite markers.

Results: Loss of heterozygosity was detected for chromosome 8p21.3–p22 in nine (40.9%) of 22 dysplastic nodules and in eight (42.1%) of 19 hepatocellular carcinomas. D8S261, located adjacent to PRLTS, showed most frequent LOH: 28.6% in dysplastic nodule and 40.0% in hepatocellular carcinoma. Loss of heterozygosity on chromosome 11p13 was found in three (15.8%) of 19 dysplastic nodules and in six (31.6%) of 19 hepatocellular carcinomas. Loss of heterozygosity of D11S995 and D11S907 was found in 33.3% and 7.1% of dysplastic nodules, and 8.3% and 44.4% of hepatocellular carcinomas, respectively.

Conclusion: These results suggest that at least one putative tumor suppressor gene involved in the development and progression of hepatocellular carcinoma may be located on 8p21.3–p22 and 11p13. Particularly, PRLTS might be related to an early genetic event of hepatocarcinogenesis.

© 2003 Blackwell Publishing Asia Pty Ltd