bluuebunny/crossref_metadata_2025 huggingface dataset:
Mycobacterium smegmatis whmD and its homologue Mycobacterium tuberculosis whiB2 are functionally equivalent
Authors: Raghunand Tirumalai R. , Bishai William R.
Published: August 2006

Mycobacterium smegmatis whmDis is an essential gene involved in cell division. This paper shows thatwhmDand its homologuewhiB2inMycobacterium tuberculosisare functionally equivalent. The genes are syntenous, and share significant homology in both their coding and non-coding DNA sequences. Transcription site mapping showed that the two genes possess near-identical promoter elements, and they displayed comparable promoter strengths in a reporter gene assay. The two proteins show near identity in their C-terminus, and polyclonal antiserum to WhmD specifically cross-reacts with a ∼15 kDa band inM. tuberculosislysates. Following overexpression of sense and anti-sense constructs in their cognate mycobacterial hosts,whiB2andwhmDtransformants displayed a small-colony phenotype, exhibited filamentation, and showed a reduction in viability. These observations reveal that the two proteins are functionally homologous and that their intracellular concentration is critical for septation in mycobacteria. Colonies ofM. tuberculosisoverexpressingwhiB2were spherical and glossy, suggesting a change in composition of the cell envelope. Filaments of the conditionally complementedM. smegmatis whmDmutant were non-acid-fast, also indicating changes in characteristics of surface lipids.M. smegmatistransformants carrying awhmD–gfpfusion showed a diffuse pattern of fluorescence, consistent with the putative role of WhmD as a regulator. These observations strongly suggest thatM. tuberculosis whiB2is an essential gene and its protein product in all likelihood regulates the expression of genes involved in the cell division cascade.
Plasmids from freshwater environments capable of IncQ retrotransfer are diverse and include pQKH54, a new IncP-1 subgroup archetype
Authors: Haines Anthony S. , Akhtar Parveen , Stephens Elton R. , Jones Karen , Thomas Christopher M. , Perkins Caroline D. , Williams Jacqueline R. , Day Martin J. , Fry John C.
Published: August 2006

Nine mercury-resistance plasmids isolated from river epilithon were assessed for their ability to retrotransfer the non-conjugative IncQ plasmid, R300B, derivatives of which have commercial uses that may result in accidental or deliberate release into the environment. Retrotransfer frequencies ranging from 2.1×10−4 to 1.75×10−5 were obtained for five of the nine plasmids – the remaining plasmids showed low or undetectable retrotransfer ability. The majority of the retrotransfer-proficient plasmids could not be classified by the tests used. Classical incompatibility testing with RP4 identified pQKH6, pQKH54 and pQM719 as IncP-1. Hybridization to replicon probes confirmed this for pQKH6 and pQM719 and added pQKH33. PCR with primers designed to amplify trfA and korA regions of IncP-1 plasmids did not identify any other plasmids. Plasmids pQKH6 and pQM719 but not pQKH54 produced similar SphI restriction profiles to the IncP-1β subgroup. The complete nucleotide sequence of pQKH54 was determined, revealing it to have a complete IncP-1 backbone but belonging to a new distinct subgroup which was designated IncP-1γ. The results emphasize the ubiquity and diversity of IncP-1 plasmids in the environment but demonstrate that plasmids of as yet unknown groups are also able to retrotransfer IncQ plasmids efficiently.
Involvement of the S-layer proteins Hpi and SlpA in the maintenance of cell envelope integrity in Deinococcus radiodurans R1
Authors: Rothfuss Heather , Lara Jimmie C. , Schmid Amy K. , Lidstrom Mary E.
Published: August 2006

The potential functions have been investigated of two proteins in Deinococcus radiodurans R1 predicted to be involved in the maintenance and integrity of the S layer: the hexagonally packed intermediate (Hpi) protein, and SlpA (DR2577), a homologue of an S-layer SlpA protein in Thermus thermophilus. Deletion of the hpi gene had little effect on the structure of the cell envelope or on shear- or solvent-induced stress responses. However, deletion of the slpA gene caused substantial alterations in cell envelope structure, and a significant defect in resistance to solvent and shear stresses compared to the wild-type. Ultrastructural analysis of slpA mutant cells indicated loss of much of the outer Hpi protein carbohydrate coat, the ‘pink envelope’, and the membrane-like backing layer. Together these results suggest that the SlpA protein may be involved in attachment of the Hpi surface layer to the inner cell envelope, and that SlpA may play an important role in the maintenance of cell envelope integrity in D. radiodurans.
Cyt1Ca from Bacillus thuringiensis subsp. israelensis: production in Escherichia coli and comparison of its biological activities with those of other Cyt-like proteins
Authors: Manasherob Robert , Itsko Mark , Sela-Baranes Nadine , Ben-Dov Eitan , Berry Colin , Cohen Shmuel , Zaritsky Arieh
Published: August 2006

The larvicidal activity ofBacillus thuringiensissubsp.israelensisagainst dipteran larvae is determined by four major polypeptides of the parasporal crystalline body produced during sporulation. Cyt1Aa shows the lowest toxicity when used alone but is the most synergistic with any of the other proteins. The sequence of the plasmid pBtoxis, which contains all the toxin genes in this subspecies, revealed a newcyt-like coding sequence namedcyt1Ca. In addition to the Cyt-like region, the predicted Cyt1Ca contained an extra domain at the C terminus, which appeared to be aβ-trefoil carbohydrate-binding motif, as found in several ricin-like toxins. The gene was PCR-amplified from pBtoxis and cloned in several vectors, allowing high-level expression inEscherichia coli. Cyt1Ca was purified by nickel-nitrilotriacetic acid affinity chromatography, characterized, and its biological activity was determined. Toxicity against larvae ofAedes aegyptiof Cyt1Ca in recombinantE. colicells was compared with that of Cyt1Aa and Cyt2Ba, and the ability of these proteins to enhance the activity of Cry4Aa was assessed. Although Cyt2Ba appeared able to interact with Cry4Aa, no activity for Cyt1Ca was observed, even when produced in truncated form. Furthermore, in contrast to Cyt1Aa, Cyt1Ca did not lyse sheep erythrocytes, and it was not bactericidal to the host cell.
Rho-dependent terminators and transcription termination
Authors: Ciampi M. Sofia
Published: August 2006

Rho-dependent transcription terminators participate in sophisticated genetic regulatory mechanisms, in both bacteria and phages; they occur in regulatory regions preceding the coding sequences of genes and within coding sequences, as well as at the end of transcriptional units, to prevent readthrough transcription. Most Rho-dependent terminators have been found in enteric bacteria, but they also occur in Gram-positive bacteria and may be widespread among bacteria. Rho-dependent termination requires bothcis-acting elements, on the mRNA, andtrans-acting factors. The onlycis-acting element common to Rho-dependent terminators is richness in rC residues. Additional sequence elements have been observed at different Rho termination sites. These ‘auxiliary elements' may assist in the termination process; they differ among terminators, their occurrence possibly depending on the function and sequence context of the terminator. Specific nucleotides required for termination have also been identified at Rho sites. Rho is the main factor required for termination; it is a ring-shaped hexameric protein with ATPase and helicase activities. NusG, NusA and NusB are additional factors participating in the termination process. Rho-dependent termination occurs by binding of Rho to ribosome-free mRNA, C-rich sites being good candidates for binding. Rho's ATPase is activated by Rho–mRNA binding, and provides the energy for Rho translocation along the mRNA; translocation requires sliding of the message into the central hole of the hexamer. When a polymerase pause site is encountered, the actual termination occurs, and the transcript is released by Rho's helicase activity. Many aspects of this process are still being studied. The isolation of mutants suppressing termination, site-directed mutagenesis ofcis-acting elements in Rho-dependent termination, and biochemistry, are and will be contributing to unravelling the still undefined aspects of the Rho termination machinery. Analysis of the more sophisticated regulatory mechanisms relying on Rho-dependent termination may be crucial in identifying new essential elements for termination.
Prediction of whole-genome DNA–DNA similarity, determination of G+C content and phylogenetic analysis within the family Pasteurellaceae by multilocus sequence analysis (MLSA)
Authors: Kuhnert Peter , Korczak Bożena M.
Published: August 2006

Genome predictions based on selected genes would be a very welcome approach for taxonomic studies, including DNA–DNA similarity, G+C content and representative phylogeny of bacteria. At present, DNA–DNA hybridizations are still considered the gold standard in species descriptions. However, this method is time-consuming and troublesome, and datasets can vary significantly between experiments as well as between laboratories. For the same reasons, full matrix hybridizations are rarely performed, weakening the significance of the results obtained. The authors established a universal sequencing approach for the three genesrecN,rpoAandthdFfor thePasteurellaceae, and determined if the sequences could be used for predicting DNA–DNA relatedness within the family. The sequence-based similarity values calculated using a previously published formula proved most useful for species and genus separation, indicating that this method provides better resolution and no experimental variation compared to hybridization. By this method, cross-comparisons within the family over species and genus borders easily become possible. The three genes also serve as an indicator of the genome G+C content of a species. A mean divergence of around 1 % was observed from the classical method, which in itself has poor reproducibility. Finally, the three genes can be used alone or in combination with already-established 16S rRNA,rpoBandinfBgene-sequencing strategies in a multisequence-based phylogeny for the familyPasteurellaceae. It is proposed to use the three sequences as a taxonomic tool, replacing DNA–DNA hybridization.
Transcriptional profiling of Borrelia burgdorferi containing a unique bosR allele identifies a putative oxidative stress regulon
Authors: Hyde Jenny A. , Seshu J. , Skare Jonathan T.
Published: August 2006

Borrelia burgdorferi regulates gene expression in response to environmental conditions, including temperature, pH, redox potential and host factors. B. burgdorferi encodes a PerR homologue designated BosR, which presumably serves as a global regulator of genes involved in the oxidative stress response. Infectious B. burgdorferi strain B31 is resistant to oxidative stressors in vitro, whereas the non-infectious isolate was sensitive due, in part, to a point mutation that converts an arginine to a lysine at residue 39 of BosR. Subsequent insertional inactivation of this bosRR39K allele (bosRR39K : : kanR) restored resistance to oxidative stressors. These observations suggest that the B. burgdorferi non-infectious bosRR39K : : kanR strain may transcribe genes that are also expressed in infectious B. burgdorferi cells, but are repressed in the bosRR39K background, thus explaining the different oxidative stress phenotypes observed between these isolates. To test this hypothesis, macroarray technology and quantitative RT-PCR were utilized to compare the transcriptional profiles from the isogenic bosRR39K and bosRR39K : : kanR isolates. Array data indicated that 88 ORFs were significantly expressed in the absence of BosRR39K. Since most affected genes mapped to the chromosome, it is likely that these genes define an important physiologic response for B. burgdorferi. Included within the genes identified was the detoxification gene sodA, as well as other loci not overtly linked to oxidative stress. These results suggest that a putative BosR regulon, as defined by the bosRR39K allele, is required to combat toxic oxidative intermediates, but may also be involved in adaptive strategies that are independent of reactive oxygen species.
Bacterial factors influencing adhesion of Pseudomonas aeruginosa strains to a poly(ethylene oxide) brush
Authors: Roosjen Astrid , Busscher Henk J. , Norde Willem , van der Mei Henny C.
Published: August 2006

Most bacterial strains adhere poorly to poly(ethylene oxide) (PEO)-brush coatings, with the exception of a Pseudomonas aeruginosa strain. The aim of this study was to find factors determining whether P. aeruginosa strains do or do not adhere to a PEO-brush coating in a parallel plate flow chamber. On the basis of their adhesion, a distinction could be made between three adhesive and three non-adhesive strains of P. aeruginosa, while bacterial motilities and zeta potentials were comparable for all six strains. However, water contact angles indicated that the adhesive strains were much more hydrophobic than the non-adhesive strains. Furthermore, only adhesive strains released surfactive extracellular substances, which may be engaged in attractive interactions with the PEO chains. Atomic force microscopy showed that the adhesion energy, measured from the retract curves of a bacterial-coated cantilever from a brush coating, was significantly more negative for adhesive strains than for non-adhesive strains (P<0.001). Through surface thermodynamic and extended-DLVO (Derjaguin, Landau, Verwey, Overbeek) analyses, these stronger adhesion energies could be attributed to acid–base interactions. However, the energies of adhesion of all strains to a brush coating were small when compared with their energies of adhesion to a glass surface. Accordingly, even the adhesive P. aeruginosa strains could be easily removed from a PEO-brush coating by the passage of a liquid–air interface. In conclusion, cell surface hydrophobicity and surfactant release are the main factors involved in adhesion of P. aeruginosa strains to PEO-brush coatings.
DNA secretion and gene-level selection in bacteria
Authors: Draghi Jeremy A. , Turner Paul E.
Published: August 2006

Natural genetic transformation can facilitate gene transfer in many genera of bacteria and requires the presence of extracellular DNA. Although cell lysis can contribute to this extracellular DNA pool, several studies have suggested that the secretion of DNA from living bacteria may also provide genetic material for transformation. This paper reviews the evidence for specific secretion of DNA from intact bacteria into the extracellular environment and examines this behaviour from a population-genetics perspective. A mathematical model demonstrates that the joint action of DNA secretion and transformation creates a novel type of gene-level natural selection. This model demonstrates that gene-level selection could explain the existence of DNA secretion mechanisms that provide no benefit to individual cells or populations of bacteria. Additionally, the model predicts that any trait affecting DNA secretion will experience selection at the gene level in a transforming population. This analysis confirms that the secretion of DNA from intact bacterial cells is fully explicable with evolutionary theory, and reveals a novel mechanism for bacterial evolution.
Trehalose metabolism is important for heat stress tolerance and spore germination of Botrytis cinerea
Authors: Doehlemann Gunther , Berndt Patrick , Hahn Matthias
Published: August 2006

To analyse the role of trehalose as stress protectant and carbon storage compound in the grey mould fungusBotrytis cinerea, mutants defective in trehalose-6-phosphate synthase (TPS1) and neutral trehalase (TRE1) were constructed. The Δtps1mutant was unable to synthesize trehalose, whereas the Δtre1mutant showed elevated trehalose levels compared to the wild-type and was unable to mobilize trehalose during conidial germination. Both mutants showed normal vegetative growth and were not affected in plant pathogenicity. Growth of the Δtps1mutant was more heat sensitive compared to the wild-type. Similarly, Δtps1conidia showed a shorter survival under heat stress, and their viability at moderate temperatures was strongly reduced. In germinating wild-type conidia, rapid trehalose degradation occurred only when germination was induced in the presence of nutrients. In contrast, little trehalose breakdown was observed during germination on hydrophobic surfaces in water. Here, addition of cAMP to conidia induced trehalose mobilization and accelerated the germination process, probably by activation of TRE1. In accordance with these data, both mutants showed germination defects only in the presence of sugars but not on hydrophobic surfaces in the absence of nutrients. The data indicate that inB. cinereatrehalose serves as a stress protectant, and also as a significant but not essential carbon source for germination when external nutrients are low. In addition, evidence was obtained that trehalose 6-phosphate plays a role as a regulator of glycolysis during germination.
Biofilm formation by a Bacillus subtilis strain that produces γ-polyglutamate
Authors: Morikawa Masaaki , Kagihiro Shinji , Haruki Mitsuru , Takano Kazufumi , Branda Steve , Kolter Roberto , Kanaya Shigenori
Published: August 2006

The extracellular matrix produced by Bacillus subtilis B-1, an environmental strain that forms robust floating biofilms, was purified, and determined to be composed predominantly of γ-polyglutamate (γ-PGA), with a molecular mass of over 1000 kDa. Both biofilm formation and γ-PGA production by B. subtilis B-1 increased with increasing Mn2+ or glycerol concentration. γ-PGA was produced in a growth-associated manner in standing culture, and floating biofilms were formed. However, γ-PGA was produced in a non-growth-associated manner in shaking culture conditions. When B. subtilis B-1 was grown in a microaerated culture system, floating biofilm formation and γ-PGA production were significantly retarded, suggesting that oxygen depletion is involved in the initial steps of floating biofilm formation in standing culture. Proteomic analysis of membrane proteins demonstrated that flagellin, oligopeptide permease and Vpr protease precursor were the major proteins produced by cells in a floating biofilm and a colony.
Identification and characterization of msa (SA1233), a gene involved in expression of SarA and several virulence factors in Staphylococcus aureus
Authors: Sambanthamoorthy Karthik , Smeltzer Mark S. , Elasri Mohamed O.
Published: August 2006

The staphylococcal accessory regulator (sarA) plays a central role in the regulation of virulence in Staphylococcus aureus. To date, studies involving sarA have focused on its activity as a global regulator that modulates transcription of a wide variety of genes (>100) and its role in virulence. However, there is also evidence to suggest the existence of accessory elements that modulate SarA production and/or function. A reporter system was developed to identify such elements, and a new gene, msa (SA1233), mutation of which results in reduced expression of SarA, was identified and characterized. Additionally, it was shown that mutation of msa resulted in altered transcription of the accessory gene regulator (agr) and the genes encoding several virulence factors including alpha toxin (hla) and protein A (spa). However, the impact of mutating msa was different in the laboratory strain RN6390 and the clinical isolate UAMS-1. For instance, mutation of msa caused a decrease in spa and hla transcription in RN6390 but had a different effect in UAMS-1. The strain-dependent effects of the msa mutation were similar to those observed previously, which suggests that msa may modulate the production of specific virulence factors through its impact on sarA. Interestingly, sequence analysis of Msa suggests that it is a putative membrane protein with three membrane-spanning regions, indicating that Msa might interact with the environment. The findings show that msa is involved in the expression of SarA and several virulence factors.
Hypermutable bacteria isolated from humans – a critical analysis
Authors: Hall Lucinda M. C. , Henderson-Begg Stephanie K.
Published: August 2006

Hypermutable bacteria of several species have been described among isolates recovered from humans over the last decade. Interpretation of the literature in this area is complicated by diversity in the determination and definition of hypermutability, and this review outlines the different methods used. Inactivation of the mismatch repair genemutSis often implicated in the mutator phenotype; the reported effect ofmutSinactivation on mutation frequency varies widely between species, from under 10-fold to nearly 1000-fold, but also varies among different reports on the same species. Particularly high proportions of mutators have been reported amongPseudomonas aeruginosaand other species in the cystic fibrosis lung, epidemic serogroup ANeisseria meningitidis, andHelicobacter pylori. Aspects of the biology of these infections that could be relevant to hypermutability are discussed, and some future directions that may increase our understanding of mutators among bacteria isolated from humans are considered.
Plasmid pSci6 from Spiroplasma citri GII-3 confers insect transmissibility to the non-transmissible strain S. citri 44
Authors: Berho Nathalie , Duret Sybille , Danet Jean-Luc , Renaudin Joël
Published: August 2006

The insect-transmissible strain GII-3 of Spiroplasma citri contains plasmids pSci1–6, five of which (pSci1–5) encode adhesin-like proteins and one (pSci6) encodes protein P32, which has been associated with insect transmissibility. In contrast, S. citri strains ASP-1 and 44, which cannot be transmitted via injection into the leafhopper vector Circulifer haematoceps, lack these proteins and also do not carry plasmids pSci1–6. To further study the apparent relationship between the presence of plasmids and insect transmissibility, plasmids from S. citri GII-3 were introduced into the insect-non-transmissible S. citri strain 44 by electrotransformation using the tetM gene as the selection marker. Tetracycline-resistant transformants were shown to carry one, two or three distinct plasmids. Plasmids pSci1–6 were all detected in the transformants, pSci1 being the most frequently found, alone or together with other plasmids. Selected S. citri 44 transformants having distinct plasmid contents were submitted, separately or in combination, to experimental transmission to periwinkle (Catharanthus roseus) plants via injection into the leafhopper vector. The occurrence of symptomatic plants indicated that, in contrast to S. citri 44, spiroplasmal transformants were transmitted to the host plant, in which they multiplied. Spiroplasma cultures isolated from these infected plants all contained pSci6, leading to the conclusion that, under the experimental conditions used, transformation by pSci6 conferred insect transmissibility to S. citri strain 44. This is believed to be the first report of a phenotypic change associated with transformation of S. citri by natural plasmids.
Habitat requirements and foraging behaviour of the Corsican nuthatch Sitta whiteheadi
Authors: Thibault Jean‐Claude , Prodon Roger , Villard Pascal , Seguin Jean‐François
Published: August 2006

We examined the relationship between the Corsican nuthatch Sitta whiteheadi, a passerine endemic to the island of Corsica and Corsican pine Pinus nigra laricio forest, its virtually exclusive habitat, currently restricted to inland mountains. The Corsican nuthatch prefers older Corsican pine stands with tall, large trees, and avoids younger stands, both in the breeding and wintering seasons. This preference is explained by the greater availability of pine seeds from older trees. Territorial adults are almost completely sedentary, a trait that is influenced by seed hoarding behaviour. From late autumn to early spring (i.e., when cones are mature), and during sunny weather (i.e., when cones are open), nuthatches remove pine seeds from cones and cache them on branches and under the bark of trunks. The birds retrieve the cached seeds in cold and wet weather. The presence of old Corsican pine stands appears to be a key‐factor in the survival of the Corsican nuthatch, whose habitat is currently threatened by logging and fires.
Non‐invasive corticosterone treatment changes foraging intensity in red‐eyed vireos Vireo olivaceus
Authors: Lõhmus Mare , Sundström L. Fredrik , Moore Frank R.
Published: August 2006

Corticosterone is thought to play an important role in food caching and foraging behaviour. However, the direct influence of increased plasma corticosterone on feeding behaviour is still unclear. In this study the effect of increased corticosterone on feeding behaviour in migratory active red‐eyed vireos Vireo olivaceus was investigated. We hypothesized that if increased corticosterone levels facilitate foraging behaviour, an increased number of visits to the food bowl by corticosterone treated birds would be seen. In addition to ad lib food during the experiment, the vireos were fed every full hour between 09.00–13.00 h with one meal worm injected either with 4 μg corticosterone dissolved in 20 μl DMSO, or with DMSO only as a control treatment. The presence or absence of a bird in the food bowl was recorded by a motion detector between 09.00–15.00 h. The non‐invasive corticosterone treatment increased plasma corticosterone levels and caused vireos to visit the food bowl more frequently compared to control treated individuals between 11.00–12.00 h and 13.00–15.00 h. Our data indicate that corticosterone has an effect on feeding behaviour in birds.
Review article: genetic susceptibility and application of genetic testing in clinical management of inflammatory bowel disease
Authors: VERMEIRE S.
Published: August 2006

The volume of research undertaken on the genetic susceptibility of inflammatory bowel disease (IBD) has been tremendous, and over 10 chromosomal regions have been identified by genome‐wide scanning.

Fine‐mapping approaches and candidate gene studies have already led to the identification of several susceptibility genes, including CARD15 (NOD2), DLG5, novel organic cation transporter (OCTN) 1 and 2, and CARD4 (NOD1). The CARD15 gene is the most understood at present and explains around 20% of the genetic predisposition to Crohn's disease.

Although the clinical implications of genetic testing are limited at present, genetic research has advanced our understanding of the clinical heterogeneity and the complex interactions between genetic and environmental risk factors in IBD.

Genes also interfere with the metabolism of drugs and may influence the clinical response and drug‐related toxicity. Ultimately, researchers and clinicians aim to personalize medicine based on a patient's genotype, although azathioprine (thiopurine methyltransferase polymorphisms) is the only drug to date where pharmacogenetics has shown clinical relevance in IBD.

In the future, it is anticipated that genetic markers will be implemented in an integrated molecular diagnostic and prognostic approach to managing our patients.
Review article: high‐dose aminosalicylates to induce and maintain remissions in ulcerative colitis
Authors: HANAUER S. B.
Published: August 2006

Sulfasalazine was the first aminosalicylate to be used for induction and maintenance therapy of ulcerative colitis (UC). Initial trials demonstrated a dose response that was compromised by dose‐related intolerance.

Recognition that the 5‐aminosalicylic acid moiety (5‐ASA, mesalazine) is the active ingredient of sulfasalazine has allowed the development of sulpha‐free formulations of mesalazine and alternative azo‐bond derivatives (olsalazine, balsalazide) that substantially reduce the dose‐related (and allergic) consequences of the sulfapyridine moiety of sulfasalazine.

Dose‐ranging studies of mesalazine formulations for induction of remission have demonstrated increased efficacy of oral mesalazine up to 4–4.8 g/day, particularly in patients with more moderate disease activity. Combination therapy with oral and rectal mesalazine provide additional efficacy for patients with both distal and extensive colitis.

The mesalazine formulations have dose‐related benefits without dose‐related side effects. In contrast, the azo‐bond formulations are compromised by secretory diarrhoea at doses providing greater than 2–2.4 g/day of mesalazine. There are less data regarding dose‐related benefits of aminosalicylates to maintain remissions in UC greater than 1.6 g/day of mesalazine, although the absence of dose‐related side effects allows continuation of the same inductive dose through maintenance treatment without dose‐related toxicity.
Review article: colorectal cancer surveillance in ulcerative colitis – what should we be doing?
Authors: OBRADOR A. , GINARD D. , BARRANCO L.
Published: August 2006

Different societies have published guidelines for colorectal cancer (CRC) surveillance in ulcerative colitis (UC). While it would seem that most gastroenterologists and endoscopists agree with these guidelines, different studies have shown that in clinical practice, the concept of dysplasia is not fully understood, and therefore, the guidelines are not always followed. According to some studies, the reason why gastroenterologists do not follow the recommendations is inadequate education.

The main advance in recent years in this subject is in endoscopic diagnosis of dysplasia. The magnification and chromoendoscopy allow targeted biopsies to be taken. Some studies indicate that nontargeted biopsies are not useful in ruling out dysplasia. It is also important to realize that most dysplasia is visible in conventional colonoscopy. In colonoscopy, it is not only significant to detect dysplasia‐associated lesions or masses; the endoscopist should also be trained to detect, in the course of conventional exploration, subtle changes in colour or in mucosal surfaces that imply dysplasia.

Adherence to guidelines had been extensively assessed in other disease conditions (asthma, hypertension, etc.). According to our knowledge there are no such data regarding CRC surveillance in UC.

Some barriers that may affect physicians include: (i) knowledge (lack of awareness or lack of familiarity); (ii) attitudes (lack of agreement, lack of self‐efficacy, lack of outcome expectancy, or the inertia of previous practice) and (iii) behaviour (external barriers).

In conclusion, we need new guidelines for CRC surveillance in UC, which must take into account the advances in risk factors of dysplasia and new technologies to study colon dysplasia.

‘The important thing in science is not so much to obtain new facts as to discover new ways of thinking about them’ Sir William Bragg (1862–1942)
Review article: the effect of aminosalicylates and immunomodulation on cancer risk in inflammatory bowel disease
Authors: STANGE E. F.
Published: August 2006

Ulcerative colitis and, maybe to a similar extent, Crohn's disease are associated with an increased risk of colorectal carcinoma. As a consequence of this increased risk, surveillance strategies have been proposed to prevent colorectal carcinoma through early detection of dysplasia, which may herald malignant disease. These surveillance strategies are controversial for several reasons discussed in this review.

It may be concluded from the relevant studies that regular use of at least 1.2 g of mesalazine per day may effectively prevent about two out of three colon cancers in ulcerative colitis. In contrast, there seems to be no role for either mercaptopurine or folic acid in protection from colon cancer.
Review article: gastrointestinal bleeding with low‐dose aspirin – what's the risk?
Authors: LAINE L.
Published: August 2006

This review examines ulcers and gastrointestinal bleeding with low‐dose aspirin, focusing on randomized placebo‐controlled trials.

The single endoscopic trial assessing ulcers showed no significant difference in 12‐week ulcer incidence: 6% of 381 given placebo vs. 7% of 387 given 81 mg enteric‐coated aspirin.

The relative risk of major gastrointestinal bleeding with low‐dose aspirin in a meta‐analysis of placebo‐controlled trials of vascular protection was 2.07 (95% CI: 1.61–2.66). The absolute rate increase with aspirin above placebo was 0.12% per year (95% CI: 0.07–0.19%) with a number‐needed‐to‐harm of 833 patients (95% CI: 526–1429). A meta‐analysis of aspirin 50–1500 mg daily reported an odds ratio for any gastrointestinal bleeding of 1.68 (95% CI: 1.51–1.88) with an number‐needed‐to‐harm at 1 year of 247. The relative risk of hospitalization for upper gastrointestinal bleeding with low‐dose aspirin in a large Danish cohort study was 2.6 (95% CI: 2.2–2.9) with an absolute annual incidence of 0.6%.

Factors that may increase the risk of gastrointestinal bleeding include prior history of ulcers or gastrointestinal bleeding, corticosteroid use, anticoagulant therapy and addition of a non‐aspirin non‐steroidal anti‐inflammatory drug.

When determining whether low‐dose aspirin is appropriate for an individual patient, the cardiovascular benefit must be weighed against the potential for clinical events such as gastrointestinal bleeding.
Review article: modulation of the brain–gut axis as a therapeutic approach in gastrointestinal disease
Authors: MAYER E. A. , TILLISCH K. , BRADESI S.
Published: August 2006

Background

The importance of bi‐directional brain‐gut interactions in gastrointestinal illness is increasingly being recognized, most prominently in the area of functional gastrointestinal disorders. Numerous current and emerging therapies aimed at normalizing brain–gut interactions are a focus of interest, particularly for irritable bowel syndrome and functional dyspepsia.

Methods

A literature search was completed for preclinical and clinical studies related to central modulation of gastrointestinal functions and published in English between 1980 and 2006.

Results

Existing data, while sparse, support the use of different classes of antidepressant drugs, including tricyclics, and selective and non‐selective serotonin reuptake inhibitors in irritable bowel syndrome. Serotonin receptor agonists and antagonists with peripheral and possibly central effects are effective in treating specific subtypes of irritable bowel syndrome. Based largely on theoretical and preclinical evidence, several novel compounds that selectively target receptors at multiple levels within the brain–gut axis such as neurokinin, somatostatin and corticotropin‐releasing factor receptor antagonists are promising.

Conclusions

This review discusses the rationale for modulation of the brain–gut axis in the treatment of functional gastrointestinal disorders and highlights the most promising current and future therapeutic strategies.
Discontinuation of proton pump inhibitors in patients on long‐term therapy: a double‐blind, placebo‐controlled trial
Authors: BJÖRNSSON E. , ABRAHAMSSON H. , SIMRÉN M. , MATTSSON N. , JENSEN C. , AGERFORZ P. , KILANDER A.
Published: August 2006

Background

The proportion of proton pump inhibitor users on long‐term therapy who can discontinue proton pump inhibitor (PPI) medication without developing symptoms is unknown.

Aim

To determine the proportion of patients on long‐term PPI therapy who are able to discontinue PPIs without developing symptoms.

Methods

Patients on long‐term PPIs, without a history of peptic ulcer or esophagitis underwent upper endoscopy. Patients were randomized double‐blindly to taper down or continue a constant dosage of omeprazole for three weeks. Thereafter, all patients discontinued PPIs.

Results

Of the 97 patients enrolled, had used PPIs for 48 months, 78% had GERD. A total of 27% did not use PPIs during the year after discontinuation, 31% of the patients randomized to tapering discontinued PPIs and 22% of those who did not could discontinue therapy (NS). Gastro‐oesophageal reflux disease (GERD) patients were more prone to continue PPIs than non‐GERD patients. Only 16 (21%) of GERD patients were off PPIs vs. 48% of patients without GERD (p < 0.05). Serum gastrin was higher at baseline in GERD patients who resumed PPIs versus non‐resumers (p < 0.05). GERD and serum gastrin were independent predictors of PPI requirement.

Conclusions

Discontinuation of PPI was successful in 27% of long‐term PPI users. GERD patients had more difficulty discontinuing PPIs than non‐GERD patients.
Meta‐analysis: terlipressin therapy for the hepatorenal syndrome
Authors: FABRIZI F. , DIXIT V. , MARTIN P.
Published: August 2006

Background

The hepatorenal syndrome is a severe and well‐known complication of end‐stage liver disease, but its management is controversial. Recent reports have shown the efficacy of terlipressin therapy, a vasopressin analogue, in hepatorenal syndrome patients.

Aim

To evaluate the efficacy and safety of terlipressin in the treatment of hepatorenal syndrome.

Methods

We performed a systematic review of the literature with a meta‐analysis of clinical trials. The primary outcome (as a measure of efficacy) was the rate of responder patients (i.e. patients who had hepatorenal syndrome reversal after terlipressin therapy). The secondary outcomes were the rate of responders who had hepatorenal syndrome recurrence after terlipressin withdrawal, and the drop‐out rate (as a measure of tolerability). We used the random effects model of DerSimonian and Laird with heterogeneity and sensitivity analysis.

Results

We identified 10 clinical trials (154 unique patients); two (20.0%) were randomized, controlled trials. The pooled rate of patients who reversed hepatorenal syndrome after terlipressin therapy was 0.52 (95% CI, 0.42; 0.61), P = 0.0001; I2 = 24.6%. The pooled frequency of responder patients who showed hepatorenal syndrome recurrence after terlipressin withdrawal was 0.55 (95% CI, 0.40; 0.69), P = 0.00001; I2 = 44.3%. The pooled rate of patients who showed side‐effects to terlipressin therapy was 0.29 (95% CI, 0.17; 0.42), P < 0.0001, I2 = 66.6%. The drop‐out rate was 0%. The pooled OR for mortality rate in hepatorenal syndrome patients who were not responders to terlipressin vs. responder patients was 5.746 (95% CI, 1.5; 21.9). We did not find any predictive factor of response to terlipressin therapy.

Conclusions

This meta‐analysis shows efficacy and safety of terlipressin in the treatment of hepatorenal syndrome. However, a significant number of responder patients relapsed after terlipressin withdrawal. Further studies are in progress to address the link between terlipressin and survival in hepatorenal syndrome patients.
Risk factors for cardiopulmonary events during propofol‐mediated upper endoscopy and colonoscopy
Authors: VARGO J. J. , HOLUB J. L. , FAIGEL D. O. , LIEBERMAN D. A. , EISEN G. M.
Published: August 2006

Background

Propofol‐mediated sedation for endoscopy is popular because of its rapid onset and recovery profile.

Aim

To examine procedure‐specific occurrence and risk factors for cardiopulmonary events during propofol‐mediated upper endoscopy (EGD) and colonoscopy.

Design

A cohort study using the Clinical Outcomes Research Initiative database was used to determine the frequency of cardiopulmonary events. Clinical Outcomes Research Initiative consisted of 69 practice sites comprising 593 US endoscopists. Multivariate logistic regression analysis used variables, such as age, ASA classification and propofol administration by monitored anaesthesia care or gastroenterologist‐administered propofol to determine the risk of cardiopulmonary events.

Results

The overall cardiopulmonary event rate for 5928 EGDs and 11 683 colonoscopies was 11.7/1000 cases. For colonoscopy, ascending ASA classification was associated with an increased risk. Monitored anaesthesia care was associated with a decreased adjusted relative risk (0.5, 95% CI: 0.36–0.72). ASA I and II patients receiving monitored anaesthesia care for EGD exhibited a significantly lower relative risk (ARR 0.29, 95% CI: 0.14–0.64). For subjects with ASA class III or greater, there was no difference in the risk between monitored anaesthesia care and gastroenterologist‐administered propofol.

Conclusions

There are procedure‐specific risk factors for cardiopulmonary events during propofol‐mediated EGD and colonoscopy. These should be taken into account during future prospective comparative trials.
Population pharmacokinetics of darbepoetin alfa in haemodialysis and peritoneal dialysis patients after intravenous administration
Authors: Takama Hirotaka , Tanaka Hideji , Nakashima Daisuke , Ogata Hiroyasu , Uchida Eiji , Akizawa Tadao , Koshikawa Shozo
Published: August 2006

Aims

To characterize the pharmacokinetics of darbepoetin alfa and covariate relationships in haemodialysis (HD) and peritoneal dialysis (PD) patients.

Methods

Data were collected from 131 (63 HD and 68 PD) patients who received darbepoetin alfa intravenously. A total of 917 serum concentrations were available. The data were analysed by nonlinear mixed effect modelling using NONMEM with a model including endogenous erythropoietin production. In addition, the final model was evaluated using bootstrap resampling.

Results

The selected basic model was a two‐compartment model with a combination of additive and the constant coefficient of variation error models. The significant covariates were weight (WT) for clearance (CL) and the volume of central compartment (V1), and the dialysis technique (DIA) for V1. The typical values of CL and V1 were 0.0807 l h−1 and 2.51 l, respectively. V1 in PD patients was 17% higher than in HD patients. With the introduction of WT in CL and WT and DIA in V1, interindividual variability decreased from 27.1% to 20.6% in CL and from 29.1% to 21.8% in V1. The mean parameter estimates from the bootstrap datasets were similar to those from the original dataset. Evaluation by bootstrapping showed that the final model was stable.

Conclusions

The results of the present analysis suggest no dosage regimen change is warranted for darbepoetin alfa in HD and PD patients over the range of distribution of covariates included in this study.
Recent insights into the pathogenesis of Diamond–Blackfan anaemia
Authors: Gazda Hanna T. , Sieff Colin A.
Published: August 2006

Diamond–Blackfan anaemia (DBA) is a congenital anaemia and broad developmental disease that develops soon after birth. The anaemia is due to failure of erythropoiesis, with normal platelet and myeloid lineages, and it can be managed with steroids, blood transfusions, or stem cell transplantation. Normal erythropoiesis after transplantation shows that the defect is intrinsic to an erythroid precursor. DBA is inherited in about 10–20% of cases, and genetic studies have identified mutations in a ribosomal protein gene, RPS19, in 25% of cases; there is evidence for involvement of at least two other genes. In yeast, RPS19 deletion leads to a block in ribosomal RNA biogenesis. The critical question is how mutations in RPS19 lead to the failure of proliferation and differentiation of erythroid progenitors. While this question has not yet been answered, understanding the biology of DBA may provide insight not only into the defect in erythropoisis, but also into the other developmental abnormalities that are present in about 40% of patients, and into the cancer predisposition that is inherent to DBA.
Mycobacterium tuberculosis-susceptible I/St mice develop severe disease following infection with taxonomically distant bacteria,Salmonella entericaandChlamydia pneumoniae
Authors: Nesterenko L N , Balunets D V , Tomova A S , Romanova J M , Alyapkina J S , Zigangirova N A , Kapina M A , Kondratieva E V , Pichugin A V , Majorov K B , Apt A S
Published: August 2006

Mice of I/St strain develop severe lung inflammation and die shortly following infection with virulent mycobacteria. To find out whether tuberculosis (TB)-susceptible I/St mice are susceptible to other intracellular bacteria, we investigated two different taxonomically distant pathogens, Chlamydia pneumoniae and Salmonella enterica serovar Typhimurium. Comparison of I/St and TB-resistant A/Sn mice (both Nramp1r) demonstrated that the former are more susceptible to both salmonella and chlamydia, displaying a significantly shortened survival time following challenge. Lung pathology develops more rapidly in I/St compared to A/Sn mice following infection with chlamydia, despite their similar ability to control bacterial multiplication. Following infection with salmonella, substantial (∼ 3 log) but very short (second day post-infection) interstrain differences in bacterial loads were observed, accompanied by higher levels of interleukin (IL)-6 and tumour necrosis factor (TNF)-α in the peritoneal cavities of I/St mice. I/St macrophages were more permissive for salmonella growth during the first 24 h following infection in vitro. Because the prominent differences in survival time did not correlate with permanent differences in bacterial multiplication, we suggest that both infections trigger fatal pathological processes whose dynamics depend strongly upon the host genetics.
High-dose intravenous immunoglobulin pulse therapy in patients with progressive immunoglobulin A nephropathy: a long-term follow-up
Authors: Rasche F M , Keller F , Lepper P M , Aymanns C , Karges W , Sailer L-C , von Müller L , Czock D
Published: August 2006

In progressive immunoglobulin A nephropathy (IgAN), intravenous immunoglobulin (IVIg) treatment has been used to delay disease progression, but the long-term efficacy is largely unknown. We report the clinical outcomes after IVIg therapy in six male patients with progressive IgAN [median glomerular filtration rate (GFR) 31 ml/min per 1·73 m2] followed for a median observation period of 8 years. In this single-arm, non-randomized study, IVIg was given monthly at a dose of 2 g/kg body weight for 6 months. The course of renal function was assessed by linear regression analysis of GFR and proteinuria, and was compared to eight patients with IgAN (median GFR 29 ml/min per 1·73 m2) without IVIg as a contemporaneous control group. IgAN disease progression was delayed after IVIg therapy on average for 3 years. The mean loss of renal function decreased from − 1·05 ml/min per month to − 0·15 ml/min per month (P = 0·024) and proteinuria decreased from 2·4 g/l to 1·0 g/l (P = 0·015). The primary end-point (GFR < 10 ml/min or relapse) occurred 5·2 years (median; range 0·4–8·8) after the first IVIg pulse, and after 1·3 years (median; range 0·8–2·4) in the control group (P = 0·043). In Kaplan–Meier analysis, the median renal survival time with IVIg was prolonged by 3·5 years (IVIg 4·7 years versus control 1·2 years; P = 0·006). IVIg pulse therapy may be considered as a treatment option to reduce the loss of renal function and improve proteinuria in patients with progressive IgAN.
Cellular autoreactivity against heat shock protein 60 in renal transplant patients: peripheral and graft-infiltrating responses
Authors: Caldas C , Luna E , Spadafora-Ferreira M , Porto G , Iwai L K , Oshiro S E , Monteiro S M , Fonseca J A , Lemos F , Hammer J , Ho P L , Kalil J , Coelho V
Published: August 2006

Autoreactivity to heat shock protein 60 (Hsp60) has been implicated in the pathogenesis and regulation of chronic inflammation, especially in autoimmune diseases. In transplantation, there is a lack of information regarding the cytokine profile and specificity of cells that recognize self-Hsp60 as well as the kinetics of autoreactivity following transplantation. We studied the cellular reactivity of peripheral and graft-infiltrating lymphocytes against Hsp60 in renal transplant patients. Cytokine production induced by this protein in peripheral blood mononuclear cells indicated a predominance of interleukin (IL)-10 during the late post-transplantation period, mainly in response to intermediate and C-terminal peptides. Patients with chronic rejection presented reactivity to Hsp60 with a higher IL-10/interferon (IFN)-γ ratio compared to long-term clinically stable patients. Graft-infiltrating T cell lines, cocultured with antigen-presenting cells, preferentially produced IL-10 after Hsp60 stimulation. These results suggest that, besides its proinflammatory activity, autoreactivity to Hsp60 in transplantation may also have a regulatory role.