bluuebunny/crossref_metadata_2025 huggingface dataset:
Involvement of trichothecenes in fusarioses of wheat, barley and maize evaluated by gene disruption of the trichodiene synthase (Tri5) gene in three field isolates of different chemotype and virulence
Authors: MAIER FRANK J. , MIEDANER THOMAS , HADELER BIRGIT , FELK ANGELIKA , SALOMON SIEGFRIED , LEMMENS MARC , KASSNER HELMUT , SCHÄFER WILHELM
Published: September 2006

Fusarium graminearum is the main causative agent of Fusarium head blight on small grain cereals and of ear rot on maize. The disease leads to dramatic yield losses and to an accumulation of mycotoxins. The most dominant F. graminearum mycotoxins are the trichothecenes, with deoxynivalenol and nivalenol being the most prevalent derivatives. To investigate the involvement of trichothecenes in the virulence of the pathogen, the gene coding for the initial enzyme of the trichothecene pathway was disrupted in three field isolates, differing in chemotype and in virulence. From each isolate three individual disruption mutants were tested for their virulence on wheat, barley and maize. Despite the different initial virulence of the three wild‐type progenitor strains on wheat, all disruption mutants caused disease symptoms on the inoculated spikelet, but the symptoms did not spread into other spikelets. On barley, the trichothecene deficient mutants showed no significant difference compared to the wild‐type strains: all were equally aggressive. On maize, mutants derived from the NIV‐producing strain caused less disease than their wild‐type progenitor strain, while mutants derived from DON‐producing strains caused the same level of disease as their progenitor strains. These data demonstrate that trichothecenes influence the virulence of F. graminearum in a highly complex manner, which is strongly host as well as moderately chemotype specific.
Population genetic structure of Plasmopara viticola after 125 years of colonization in European vineyards
Authors: GOBBIN DAVIDE , RUMBOU ARTEMIS , LINDE CELESTE C. , GESSLER CESARE
Published: September 2006

To examine the within‐ and among‐population genetic structure of Plamopara viticola oosporic populations in Europe, 8991 lesions from 32 vineyard plots were collected and analysed. Four multi‐allelic microsatellite markers were used to genotype the pathogen. All populations had high levels of gene and genotypic diversity. Most populations were in Hardy–Weinberg equilibrium and thus randomly mating. Among P. viticola populations, significant low to moderate genetic differentiation was observed, even between geographically close populations. This genetic differentiation was also evident in the neighbour‐joining phylogenetic genetic distance tree, showing clear substructure and distinguishing mainly five clusters based on geographical origin. Significant isolation by distance was found in central European P. viticola populations, suggesting a step‐wise migration model. No significant isolation by distance was found within Greek populations, most probably owing to natural geographical barriers such as the sea and mountains, as well as the frequent population bottlenecks occurring in these populations, preventing natural migration among populations. The high variability of P. viticola provides explanation for its successful infestation of the heterogeneous European vineyards in the last 125 years after its introduction.
Review article: immune suppression and colorectal cancer
Authors: EVANS C. , DALGLEISH A. G. , KUMAR D.
Published: September 2006

Background

Advances in immunology and molecular biology have shown that colorectal cancer is potentially immunogenic and that host immune responses influence survival. However, immune surveillance and activation is frequently ineffective in preventing and/or controlling tumour growth.

Aim

To discuss potential ways in which colorectal cancer induces immune suppression, its effect upon prognosis and avenues for therapeutic development.

Method

A literature review was undertaken for evidence of colorectal cancer‐induced immune suppression using PubMed and Medline searches. Further studies were identified from the reference lists of identified papers.

Results

Immune suppression occurs at a molecular and cellular level and can result in a shift from cellular to humoral immunity. Several mechanisms for immune suppression have been described affecting innate and adaptive immunity with suppression linked to poorer clinical outcome.

Conclusions

Colorectal cancer causes direct inhibition of the host's immune response with a detrimental effect upon prognosis. Immunotherapy offers a therapeutic strategy to counteract these effects with promising results seen particularly in precancerous conditions and early tumours. This review strongly suggests that immunotherapy should be incorporated into adjuvant therapeutic trials for stage 2 tumours and be considered as adjuvant treatment in conjunction with standard chemotherapy regimes for advanced disease.
Survival and dependence on home parenteral nutrition: experience over a 25‐year period in a UK referral centre
Authors: LLOYD D. A. J. , VEGA R. , BASSETT P. , FORBES A. , GABE S. M.
Published: September 2006

Background

Home parenteral nutrition (HPN) is the standard treatment for severe intestinal failure in the United Kingdom.

Aim

To review long‐term survival and ongoing HPN dependence of patients receiving HPN treated at a specialist UK referral centre.

Methods

Medical records of patients commenced on HPN between 1979 and 2003 were reviewed retrospectively. Regression analysis was employed to identify factors associated with poor prognosis.

Results

Case notes of 188 patients were reviewed. Overall probability of survival was 86%, 77%, 73% and 71% at 1, 3, 5 and 10 years after starting treatment. In multivariate analysis, association was seen between mechanism of intestinal failure and survival: short bowel syndrome associated with a favourable prognosis, and intestinal dysfunction, dysmotility and obstruction with poorer prognoses. There was an association between increasing age and poor prognosis, but increased mortality was also seen in the youngest age groups. Only 9% of deaths were due to complications of HPN. Continued HPN dependence was 89%, 87%, 84% and 84% at 1, 3, 5 and 10 years in survivors.

Conclusions

Long‐term survival of patients receiving HPN remains better than that reported after intestinal transplantation. Mortality predominantly relates to underlying disease rather than complications of HPN.
Traditional Chinese medicine causing hepatotoxicity in patients with chronic hepatitis B infection: a 1‐year prospective study
Authors: YUEN M.‐F. , TAM S. , FUNG J. , WONG D. K.‐H. , WONG B. C.‐Y. , LAI C.‐L.
Published: September 2006

Background

Safety of traditional Chinese medicine in patients with chronic hepatitis B is unknown.

Aim

To study the clinical outcome of traditional Chinese medicine‐induced hepatotoxicity in chronic hepatitis B patients.

Patients and methods

All chronic hepatitis B patients in 2004 with liver dysfunction requiring hospitalization were screened prospectively for traditional Chinese medicine intake. The hepatotoxicity of individual traditional Chinese medicine elements was determined by extensive search of both English and Chinese publications.

Results

Of 45 chronic hepatitis B patients, the liver dysfunction in seven (15.6%) was attributable to traditional Chinese medicine. All had liver dysfunction pattern resembling those of acute exacerbation of chronic hepatitis B. Three patients had adverse outcomes (two deaths, one liver transplantation). One patient had accelerated course of cirrhosis now awaiting liver transplantation. The identified hepatotoxic components were Polygonum multiflorum Thunb, Cassia obtusifolia L, Melia toosendan Sieb., Rheum palmatum L., Scolopendra subspinipes mutilans L, Alisma orientale Juzepe, Glycyrrhiza uralensis Fisch. and Mentha haplocalyx Briq. One traditional Chinese medicine formula was adulterated with a highly hepatotoxic agent, N‐nitrosofenfluramine.

Conclusions

Traditional Chinese medicine‐related hepatotoxicity resulted in high mortality in chronic hepatitis B patients. Prospective randomized‐controlled trials with the same stringent criteria as western medicine clinical trials are required for Chinese medicines, to document their efficacies and safety before they can be advocated for the treatment of patients.
Prevalence of undiagnosed diabetes and postchallenge hyperglycaemia in Chinese patients with non‐alcoholic fatty liver disease
Authors: WONG V. W. S. , HUI A. Y. , TSANG S. W. C. , CHAN J. L. Y. , WONG G. L. H. , CHAN A. W. H. , SO W. Y. , CHENG A. Y. S. , TONG P. C. Y. , CHAN F. K. L. , SUNG J. J. Y. , CHAN H. L. Y.
Published: September 2006

Background

Non‐alcoholic fatty liver disease is prevalent in affluent countries and is strongly associated with metabolic syndrome.

Aim

To study the prevalence of undiagnosed diabetes and postchallenge hyperglycaemia in Chinese patients with non‐alcoholic fatty liver disease.

Methods

73 consecutive patients with biopsy‐proven non‐alcoholic fatty liver disease and no history of diabetes underwent comprehensive metabolic screening. Diagnosis of diabetes and impaired glucose regulation was based on the 2006 American Diabetes Association criteria.

Results

The prevalence of undiagnosed diabetes and impaired glucose tolerance in non‐alcoholic fatty liver disease patients was 33% and 29%, respectively. Among patients with 2‐h plasma glucose above 7.8 mm, 47% had normal fasting glucose (below 5.6 mm). Impaired glucose tolerance was more common in patients with non‐alcoholic steatohepatitis than those with simple hepatic steatosis (P = 0.036), and 2‐h plasma glucose correlated with fibrosis stage (Spearman coefficient: 0.25, P = 0.046). In a binary logistic regression analysis, high fasting glucose and low high‐density lipoprotein cholesterol were independent factors associated with diabetes. Nevertheless, if oral glucose tolerance test was only performed in non‐alcoholic fatty liver disease patients with impaired fasting glucose, 20.8% of diabetes cases would be missed.

Conclusions

Isolated postchallenge hyperglycaemia is common among Chinese non‐alcoholic fatty liver disease patients without history of diabetes. It is associated with histological severe disease, and cannot be accurately predicted by any fasting glucose cut‐off.
Effects of phlebotomy therapy on cytochrome P450 2e1 activity and oxidative stress markers in dysmetabolic iron overload syndrome: a randomized trial
Authors: LAINÉ F. , REYMANN J. M. , MOREL F. , LANGOUËT S. , PERRIN M. , GUILLYGOMARC'H A. , BRISSOT P. , TURMEL V. , MOUCHEL C. , PAPE D. , BELLISSANT E. , DEUGNIER Y.
Published: September 2006

Aim

To assess the effects of iron removal on cytochrome P450 2E1 activity and oxidative stress in dysmetabolic iron overload syndrome.

Methods

Forty‐eight patients were randomized to phlebotomy therapy consisting of removal of 300–500 mL of blood every 14 days until serum ferritin levels dropped under 100 μg/L or to follow‐up without phlebotomy therapy. Cytochrome P450 2E1 activity was measured at baseline and at the end of treatment by using the 6‐hydroxychlorzoxazone/chlorzoxazone blood metabolic ratio, 2 h after the intake of 500 mg of chlorzoxazone.

Results

In the treatment group, a mean of 3.9 ± 1.3 L of blood was removed and serum ferritin levels dropped from 715 ± 397 to 74 ± 34 μg/L. Variation of cytochrome P450 2E1 activity was not significantly different between the 2 groups (0.07 ± 0.26 vs. 0.03 ± 0.19, P = 0.36). In the treatment group, low‐density lipoprotein cholesterol and vitamin E were lowered after treatment compared with control group (−0.15 ± 0.51 vs. 0.24 ± 0.58, P = 0.002 and −1.3 ± 4.4 vs. 2.3 ± 5.2, P = 0.03, respectively). Inversely, vitamin C was increased (0.5 ± 3.5 vs. −1.8 ± 3.9, P = 0.03).

Conclusions

In dysmetabolic iron overload syndrome, reduction of iron stores does not significantly influence cytochrome P450 2E1 activity but is associated with a significant decrease of low‐density lipoprotein cholesterol, suggesting that venesection therapy may be a suitable option in these patients.
Separating the effects of climate and vegetation on evapotranspiration along a successional chronosequence in the southeastern US
Authors: STOY PAUL C. , KATUL GABRIEL G. , SIQUEIRA MARIO B. S. , JUANG JEHN‐YIH , NOVICK KIMBERLY A. , McCARTHY HEATHER R. , CHRISTOPHER OISHI A. , UEBELHERR JOSHUA M. , KIM HYUN‐SEOK , OREN RAM
Published: September 2006

We combined Eddy‐covariance measurements with a linear perturbation analysis to isolate the relative contribution of physical and biological drivers on evapotranspiration (ET) in three ecosystems representing two end‐members and an intermediate stage of a successional gradient in the southeastern US (SE). The study ecosystems, an abandoned agricultural field [old field (OF)], an early successional planted pine forest (PP), and a late‐successional hardwood forest (HW), exhibited differential sensitivity to the wide range of climatic and hydrologic conditions encountered over the 4‐year measurement period, which included mild and severe droughts and an ice storm. ET and modeled transpiration differed by as much as 190 and 270 mm yr−1, respectively, between years for a given ecosystem. Soil water supply, rather than atmospheric demand, was the principal external driver of interannual ET differences. ET at OF was sensitive to climatic variability, and results showed that decreased leaf area index (L) under mild and severe drought conditions reduced growing season (GS) ET (ETGS) by ca. 80 mm compared with a year with normal precipitation. Under wet conditions, higher intrinsic stomatal conductance (gs) increased ETGS by 50 mm. ET at PP was generally larger than the other ecosystems and was highly sensitive to climate; a 50 mm decrease in ETGS due to the loss of L from an ice storm equaled the increase in ET from high precipitation during a wet year. In contrast, ET at HW was relatively insensitive to climatic variability. Results suggest that recent management trends toward increasing the land‐cover area of PP‐type ecosystems in the SE may increase the sensitivity of ET to climatic variability.
Prediction of bird‐day carrying capacity on a staging site: a test of depletion models
Authors: NOLET BART A. , GYIMESI ABEL , KLAASSEN RAYMOND H. G.
Published: September 2006

The carrying capacity of a site for migratory water birds, expressed in bird‐days, can be of particular conservation value. Several attempts have been made to model this carrying capacity using ideal free distribution models such as, for instance, depletion models, in which the distribution is fully determined by exploitative competition.

In the tests of depletion models carried out so far, no alternative models were compared; rather, one specific model was tested. We tested whether bird‐days were more in accordance with birds depleting the food resource (a1) until a critical food density which just enabled survival or (a2) until a threshold food density which renders the site as profitable as an alternative site; and birds (b1) satisfying their daily requirements or (b2) maximizing daily intake.

We studied Bewick's swans feeding on below‐ground tubers of fennel pondweed in one part of an autumn staging site. In most years between 1995 and 2005, we measured tuber biomass densities around September, November and March, and counted swans daily during their stopover in October.

The best fit between observed and predicted bird‐days was obtained by assuming that the swans were maximizing their daily intake and depleting the tubers until a threshold biomass density (which yielded the same energetic return as the alternative food source after accounting for a small part of the initial tuber biomass being out of reach of the swans). Also in line with daily intake maximization, the daily feeding time did not differ from 10 h day−1, the value predicted for Bewick's swans based on their feeding costs.

Our results suggests that the applicable model to calculate carrying capacity may depend strongly on whether birds use a site to stopover or to winter, because it determines whether the birds are more likely to use a threshold or critical food density, and to behave as energy maximizers or satisficers.
Contrasting patterns in genetic diversity following multiple invasions of fresh and brackish waters
Authors: KELLY DAVID W. , MUIRHEAD JAMES R. , HEATH DANIEL D. , MACISAAC HUGH J.
Published: September 2006

Biological invasions may combine the genetic effects of population bottlenecks and selection and thus provide valuable insight into the role of such processes during novel environmental colonizations. However, these processes are also influenced by multiple invasions, the number of individuals introduced and the degree of similarity between source and receiving habitats. The amphipod Gammarus tigrinus provides a useful model to assess these factors, as its invasion history has involved major environmental transitions. This species is native to the northwest Atlantic Ocean, although it invaded both brackish and freshwater habitats in the British Isles after introduction more than 65 years ago. It has also spread to similar habitats in Western Europe and, most recently, to Eastern Europe, the Baltic Sea, and the Laurentian Great Lakes. To examine sources of invasion and patterns of genetic change, we sampled populations from 13 native estuaries and 19 invaded sites and sequenced 542 bp of the mitochondrial COI gene. Strong native phylogeographical structure allowed us to unambiguously identify three allopatrically evolved clades (2.3–3.1% divergent) in invading populations, indicative of multiple introductions. The most divergent clades occurred in the British Isles and mainland Europe and were sourced from the St Lawrence and Chesapeake/Delaware Bay estuaries. A third clade was found in the Great Lakes and sourced to the Hudson River estuary. Despite extensive sampling, G. tigrinus did not occur in freshwater at putative source sites. Some European populations showed reduced genetic diversity consistent with bottlenecks, although selection effects cannot be excluded. The habitat distribution of clades in Europe was congruent with the known invasion history of secondary spread from the British Isles. Differences in salinity tolerance among lineages were suggested by patterns of habitat colonization by different native COI clades. Populations consisting of admixtures of the two invading clades were found principally at recently invaded fresh and brackish water sites in Eastern Europe, and were characterized by higher genetic diversity than putative source populations. Further studies are required to determine if these represent novel genotypes. Our results confirm that biological invasions need not result in diminished genetic diversity, particularly if multiple source populations, each with distinctive genetic composition, contribute to the founding populations.
Phylogeography of theBothrops jararacacomplex (Serpentes: Viperidae): past fragmentation and island colonization in the Brazilian Atlantic Forest
Authors: GRAZZIOTIN FELIPE G. , MONZEL MARKUS , ECHEVERRIGARAY SERGIO , BONATTO SANDRO L.
Published: September 2006

The Brazilian Atlantic Forest is one of the world's major biodiversity hotspots and is threatened by a severe habitat loss. Yet little is known about the processes that originated its remarkable richness of endemic species. Here we present results of a large‐scale survey of the genetic variation at the mitochondrial cytochromebgene of the pitviper, jararaca lancehead (Bothrops jararaca), and two closely related insular species (Bothrops insularisandBothrops alcatraz), endemic of this region. Phylogenetic and network analyses revealed the existence of two well‐supported clades, exhibiting a southern and a northern distribution. The divergence time of these two phylogroups was estimated at 3.8 million years ago, in the Pliocene, a period of intense climatic changes and frequent fragmentation of the tropical rainforest. Our data also suggest that the two groups underwent a large size expansion between 50 000 and 100 000 years ago. However, the southern group showed a more marked signal of population size fluctuation than the northern group, corroborating evidences that southern forests may have suffered a more pronounced reduction in area in the late Pleistocene. The insular speciesB. alcatrazandB. insularispresented very low diversity, each one sharing haplotypes with mainland individuals placed in different subclades. Despite their marked morphological and behavioural uniqueness, these two insular species seem to have originated very recently and most likely from distinct costalB. jararacapopulations, possibly associated with late Pleistocene or Holocene sea level fluctuations.
Genetic evidence for kin aggregation in the intertidal acorn barnacle (Semibalanus balanoides)
Authors: VELIZ DAVID , DUCHESNE PIERRE , BOURGET EDWIN , BERNATCHEZ LOUIS
Published: September 2006

It is generally assumed that larvae of benthic species are thoroughly mixed in the plankton and distributed randomly at settlement. Yet, it has also been hypothesized that a combination of larval gregarious behaviour coupled with particular oceanographic conditions may prevent larvae from mixing completely, and result in nonrandom spatial distributions following settlement. Using microsatellite markers, the main objective of this study was to investigate the occurrence of statistical connections between relatedness and settlement in the intertidal acorn barnacle from the Gulf of St Lawrence, Canada. A second objective was to test the hypothesis that patches of kin‐related individuals came from a common parental site. Our results indicated that a significant number of barnacles within a given sample were more closely related than expected by chance despite the enormous potential for admixture during the planktonic phase. Thus, eight out of 37 samples analysed had relatedness values significantly higher than expected from random settlement. Moreover, analyses of sibship network construction and network complexity tests provided evidence for the occurrence of networks within several samples that were characterized by strong connections among individuals. Thus, nonrandom planktonic dispersal associated with relatively stable oceanic currents, as well as additional ecological factors to be rigorously investigated (e.g. behavioural mechanisms), may be more important in determining patterns of genetic structure in marine benthic invertebrates than generally assumed. Therefore, documenting genetic patterns associated with kin aggregation should be a fruitful and an important avenue for future studies in marine invertebrates.
Cell wall‐inhibitory antibiotics activate the alginate biosynthesis operon in Pseudomonas aeruginosa: roles of σ22 (AlgT) and the AlgW and Prc proteases
Authors: Wood Lynn F. , Leech Andrew J. , Ohman Dennis E.
Published: September 2006

A bioassay was developed to identify stimuli that promote the transcriptional induction of the algD operon for alginate biosynthesis in Pseudomonas aeruginosa. Strain PAO1 carried the algD promoter fused to a chloramphenicol acetyl‐transferase cartridge (PalgD‐cat), and > 50 compounds were tested for promoting chloramphenicol resistance. Most compounds showing PalgD‐cat induction were cell wall‐active antibiotics that blocked peptidoglycan synthesis. PalgD‐cat induction was blocked by mutations in the genes for σ22 (algT/algU) or regulators AlgB and AlgR. Anti‐sigma factor MucA was the primary regulator of σ22 activity. A transcriptome analysis using microarrays verified that the algD operon undergoes high induction by d‐cycloserine. A similar σE–RseAB complex in Escherichia coli responds to envelope stress, which requires DegS protease in a regulated intramembrane proteolysis (RIP) cascade to derepress the sigma. Mutant phenotypic studies in P. aeruginosa showed that AlgW (PA4446) is likely to be the DegS functional homologue. A mutation in algW resulted in a complete lack of PalgD‐cat induction by d‐cycloserine. Overexpression of algW in PAO1 resulted in a mucoid phenotype and alginate production, even in the absence of cell wall stress, suggesting that AlgW protease plays a role in σ22 activation. In addition, a mutation in gene PA3257 (prc), encoding a Prc‐like protease, resulted in poor induction of PalgD‐cat by d‐cycloserine, suggesting that it also plays a role in the response to cell wall stress.
The carrier Msn5p/Kap142p promotes nuclear export of the hsp70 Ssa4p and relocates in response to stress
Authors: Quan XinXin , Tsoulos Panagiotis , Kuritzky Alexandra , Zhang Rui , Stochaj Ursula
Published: September 2006

Cytoplasmic hsp70s like yeast Ssa4p shuttle between nucleus and cytoplasm under normal growth conditions but accumulate in nuclei upon stress. This nuclear accumulation is only transient, and Ssa4p relocates to the cytoplasm when cells recover. We show here that Ssa4p nuclear export is independent of Xpol/Crm1 and identify the importin‐β family member Msn5p/Kap142p as the exporter for Ssa4p. In growing cells and in vitro, Msn5p and Ssa4p generate genuine export complexes that require Ran/Gsp1p‐GTP. Furthermore, nucleoporin Nup82p, which plays a role in Msn5p‐mediated transport, is necessary for efficient export of Ssa4p. In living cells, stress not only regulates Ssa4p localization, but also controls the distribution of Msn5p. Msn5p is concentrated in nuclei of unstressed cells, but appears in the cytoplasm upon exposure to ethanol, heat, starvation or severe oxidative stress. In addition, growth on non‐fermentable carbon sources relocates a portion of Msn5p to the cytoplasm and leads to a partial nuclear accumulation of Ssa4p. Taken together, growth and stress conditions that localize the transporter Msn5p to the cytoplasm also induce the nuclear accumulation of its cargo Ssa4p.
Heterochromatin‐mediated control of virulence gene expression
Authors: Merrick Catherine J. , Duraisingh Manoj T.
Published: September 2006

In recent years, the sequencing and annotation of complete genomes, together with the development of genetic and proteomic techniques to study previously intractable eukaryotic microbes, has revealed interesting new themes in the control of virulence gene expression. Families of variantly expressed genes are found adjacent to telomeres in the genomes of both pathogenic and non‐pathogenic organisms. This subtelomeric DNA is normally heterochromatic and higher‐order chromatin structure has now come to be recognized as an important factor controlling both the evolution and expression dynamics of these multigene families. In eukaryotic cells, higher‐order chromatin structure plays a central role in many DNA processes including the control of chromosome integrity and recombination, DNA partitioning during cell division, and transcriptional control. DNA can be packaged in two distinct forms: euchromatin is relatively accessible to DNA binding proteins and generally contains active genes, while heterochromatin is densely packaged, relatively inaccessible and usually transcriptionally silent. These features of chromatin are epigenetically inherited from cell cycle to cell cycle. This review will focus on the epigenetic mechanisms used to control expression of virulence genes in medically important microbial pathogens. Examples of such control have now been reported in several evolutionarily distant species, revealing what may be a common strategy used to regulate many very different families of genes.
Complete alanine scanning of the two‐component lantibiotic lacticin 3147: generating a blueprint for rational drug design
Authors: Cotter Paul D. , Deegan Lucy H. , Lawton Elaine M. , Draper Lorraine A. , O'Connor Paula M. , Hill Colin , Ross R. Paul
Published: September 2006

Lantibiotics are post‐translationally modified antimicrobial peptides which are active at nanomolar concentrations. Some lantibiotics have been shown to function by targeting lipid II, the essential precursor of cell wall biosynthesis. Given that lantibiotics are ribosomally synthesized and amenable to site‐directed mutagenesis, they have the potential to serve as biological templates for the production of novel peptides with improved functionalities. However, if a rational approach to novel lantibiotic design is to be adopted, an appreciation of the roles of each individual amino acid (and each domain) is required. To date no lantibiotic has been subjected to such rigorous analysis. To address this issue we have carried out complete scanning mutagenesis of each of the 59 amino acids in lacticin 3147, a two‐component lantibiotic which acts through the synergistic activity of the peptides LtnA1 (30 amino acids) and LtnA2 (29 amino acids). All mutations were performed in situ in the native 60kb plasmid, pMRC01. A number of mutations resulted in the elimination of detectable bioactivity and seem to represent an invariable core within these and related peptides. Significantly however, of the 59 amino acids, at least 36 can be changed without resulting in a complete loss of activity. Many of these are clustered to form variable domains within the peptides. The information generated in this study represents a blue‐print that will be critical for the rational design of lantibiotic‐based antimicrobial compounds.
A novel oxalosuccinate‐forming enzyme involved in the reductive carboxylation of 2‐oxoglutarate in Hydrogenobacter thermophilus TK‐6
Authors: Aoshima Miho , Igarashi Yasuo
Published: September 2006

We have previously demonstrated that the reductive carboxylation of 2‐oxoglutarate in Hydrogenobacter thermophilus TK‐6 is not simply a reversal of the oxidative decarboxylation catalysed by isocitrate dehydrogenase (ICDH). The reaction involves a novel biotin protein (carboxylating factor for ICDH – CFI) and ATP. In this study, we have analysed the ICDH/CFI system responsible for the carboxylation reaction. Sequence analysis revealed a close relationship between CFI and pyruvate carboxylase. Rather unexpectedly, the rate of ATP hydrolysis was greater than that of isocitrate formation or NADH oxidation. Furthermore, ATP hydrolysis catalysed by CFI was dependent on 2‐oxoglutarate but not on ICDH, suggesting that a carboxylated product is formed in the absence of ICDH. The product, which was detectable only at low temperatures, was identified as oxalosuccinate. Thus, CFI was confirmed to be a novel enzyme that catalyses the carboxylation of 2‐oxoglutarate to form oxalosuccinate, which corresponds to the first step of the reductive carboxylation from 2‐oxoglutarate to isocitrate. The CFI‐ICDH system may also be present in mammals, where it could play a significant role in modulating central metabolism.
nilR is necessary for co‐ordinate repression of Xenorhabdus nematophila mutualism genes
Authors: Cowles Charles E. , Goodrich‐Blair Heidi
Published: September 2006

The bacterial mutualist Xenorhabdus nematophila colonizes a specific region of its nematode host Steinernema carpocapsae. We previously reported the identification of a chromosomal locus encoding three X. nematophila genes of unknown function, nilA, B and C, that are each necessary for colonization. Subsequent work indicated the global regulator Lrp is a repressor of nilC: nilC transcription is elevated in an lrp mutant and Lrp interacts directly with the nilC promoter. In this manuscript, we report the identification of an additional gene, nilR, required for repression of nilC transcription. We show that nilR and lrp mutants also have elevated expression of nilA and nilB, demonstrating that nilA, B and C are co‐ordinately regulated. nil gene expression is derepressed most strongly when both nilR and lrp are lacking, suggesting NilR and Lrp synergistically repress nil transcription. NilR contains a helix–turn–helix‐type DNA binding domain and likely acts directly at promoters. A comparison of the wild type and nilR proteomes indicates that NilR, unlike Lrp, regulates a small number of genes. Finally, X. nematophila carrying an ectopic copy of nilR colonizes at ∼60‐fold lower levels than the control strain, suggesting that derepression of nil gene expression is necessary for nematode colonization.
A specific secretion system mediates PPE41 transport in pathogenic mycobacteria
Authors: Abdallah Abdallah M. , Verboom Theo , Hannes Fredericke , Safi Mohamad , Strong Michael , Eisenberg David , Musters René J. P. , Vandenbroucke‐Grauls Christina M. J. E. , Appelmelk Ben J. , Luirink Joen , Bitter Wilbert
Published: September 2006

Mycobacterial genomes contain two unique gene families, the so‐called PE and PPE gene families, which are highly expanded in the pathogenic members of this genus. Here we report that one of the PPE proteins, i.e. PPE41, is secreted by pathogenic mycobacteria, both in culture and in infected macrophages. As PPE41 lacks a signal sequence a dedicated secretion system must be involved. A single gene was identified in Mycobacterium marinum that showed strongly reduced PPE41 secretion. This gene was located in a gene cluster whose predicted proteins encode components of an ESAT‐6‐like secretion system. This cluster, designated ESX‐5, is conserved in various pathogenic mycobacteria, but not in the saprophytic species Mycobacterium smegmatis. Therefore, different regions of this cluster were introduced in M. smegmatis. Only introduction of the complete ESX‐5 locus resulted in efficient secretion of heterologously expressed PPE41. This PPE secretion system is also involved in the virulence of pathogenic mycobacteria, as the ESX‐5 mutant of M. marinum was affected in spreading to uninfected macrophages.
Using system analysis to build a safety culture: improving the reliability of epidural analgesia
Authors: Garnerin P. , Huchet‐Belouard A. , Diby M. , Clergue F.
Published: September 2006

Background:  A potentially dangerous situation was revealed by an incident report describing the use of an inappropriate device to administer post‐operative epidural analgesia to a patient on a surgical ward. The incident occurred in a 1200‐bed university affiliated tertiary hospital (Geneva University Hospitals, HUG) and involved three clinical departments: anaesthesiology, the surgical intensive care unit and urology.

Methods:  A multidisciplinary system analysis was carried out to identify care‐delivery problems and contributory factors. Corrective actions were devised on the basis of their ability to prevent and absorb unsafe situations.

Results:  The system analysis identified three care‐delivery problems in relation to the management of epidural analgesia. It enabled medical and nursing managers to adopt an interdepartmental set of corrective actions: a common protocol for post‐operative epidural analgesia, leading to the exclusive use of patient‐controlled epidural analgesia (PCEA) pumps; greater availability of the patient‐controlled pumps; the dissemination of guidelines; permanent proactive training of nurses by the acute‐pain team; the clarification of medical responsibilities; and a common help‐line phone number for all surgical departments.

Discussion:  The analysis provided a convincing exposure of various care‐delivery problems and their corresponding contributory factors, as well as an opportunity to address a systemic issue in a multidisciplinary way. By thus facilitating decisions and corrective actions, the analysis was instrumental in strengthening our safety culture.
A case of anaphylactic shock possibly caused by intravesical Hexvix®
Authors: Colapaoli L. , Thorsen J. , Nopp A. , Guttormsen A. B.
Published: September 2006

Background:  We report a case of a 69‐year‐old Caucasian male who experienced a severe drop in blood pressure and a skin rash after fluorescence cystoscopy and transurethral resection of the prostate. The diagnostic agent used for fluorescence cystoscopy and suspected of causing the anaphylaxis was hexaminolevulinate hydrochloride (Hexvix®).

Incident:  A profound fall in blood pressure associated with atrial fibrillation, the appearance of a rash, vomiting and transient loss of consciousness occurred immediately after surgery. The hypotension persisted for several hours despite intensive treatment. The reaction commenced approximately 5 h after exposure to Hexvix®. There was an increase in serum tryptase (almost nine‐fold) and a positive skin prick test to undiluted Hexvix®.

Conclusion:  The mechanism of the anaphylaxis is uncertain, but is considered likely to be a non‐immunoglobulin E‐mediated allergic reaction possibly caused by Hexvix®. This is the first reported case of a severe allergic reaction after intravesical instillation of Hexvix®.
A single‐model solution for volume kinetic analysis of isotonic fluid infusions
Authors: Drobin D.
Published: September 2006

Background:  Volume kinetics was developed to analyze the distribution and elimination of intravenously given fluid. However, when groups of patients are being compared, the current approach is limited by the need for several models, which yield parameters that cannot be compared. To meet the requirement to handle all patients in a group individually and without pooling, a new all‐encompassing model was designed. The aim of this paper was to test whether the new model could be used to analyze all patients in a group.

Methods:  The new model consists of ‘rate’ and ‘amount’ parameters instead of ‘clearance’ and ‘dilution’ parameters. With this change, a redundant parameter can be taken out, but the biexponential nature is retained. The new parameters are the volume of distribution V1 (ml), the intercompartmental rate constant kt (/min) and the elimination rate constant kr (/min). The success rates of the new and original models in producing results within a set of pre‐determined quality requirements were compared using blood dilution data from 10 volunteers challenged with intravenous lactated Ringer’s solution.

Results:  The new model could be used to analyze all 10 cases within the pre‐determined criteria, but the original biexponential model failed in 70% of cases. The residuals improved with the new model. The medians (interquartile ranges) were as follows: V1, 4931 ml (4239–6149 ml); kt, 0.0384/min (0.0024–0.1140/min); kr, 0.0140/min (0.0015–0.0043/min).

Conclusion:  The new model was suited to the analysis of all cases, and is therefore a better approach to study how clinical conditions change the distribution and elimination of infused fluid.
Agreement between PiCCO pulse‐contour analysis, pulmonal artery thermodilution and transthoracic thermodilution during off‐pump coronary artery by‐pass surgery
Authors: Halvorsen P. S. , Espinoza A. , Lundblad R. , Cvancarova M. , Hol P. K. , Fosse E. , Tønnessen T. I.
Published: September 2006

Background:  Haemodynamic instability during off‐pump coronary artery bypass surgery (OPCAB) may appear rapidly, and continuous monitoring of the cardiac index (CI) during the procedure is advisable. With the PiCCO monitor, CI can be measured continuously and almost real time with pulse‐contour analysis and intermittently with transthoracic thermodilution. The agreement between pulmonal artery thermodilution CI (Tpa), transthoracic thermodilution CI (Tpc) and pulse‐contour CI (PCCI) during OPCAB surgery has not been evaluated sufficiently.

Methods:  In 30 patients scheduled for OPCAB surgery, a pulmonary artery catheter and a PiCCO catheter were inserted. At different time points during surgery, Tpa, Tpc and PCCI were compared. Measurements were performed after induction of anesthesia (T1), after pericardiothomy (T2), after grafting on the anterior (T3), posterior (T4) and lateral (T5) walls and after chest closure (T6). The PCCI was recalibrated at time point T2–T6.

Results:  Mean difference and the limits of agreements (percentage error) between Tpa and Tpc were: –0.14 ± 0.60 (22.0%) l/min/m2, between Tpa and PCCI: –0.07 ± 0.92 (33.5%) l/min/m2 and between Tpc and PCCI: 0.10 ± 1.00 (35.5%) l/min/m2. For changes in CI from one time point to the next (ΔCI), the limits of agreements between ΔCI Tpa and ΔCI Tpc were 0.04 ± 0.90 l/min/m2, between ΔCI Tpa and ΔCI PCCI: –0.02 ± 1.22 l/min/m2 and between ΔCI Tpc and ΔCI PCCI: –0.08 ± 1.32 l/min/m2.

Conclusion:  In OPCAB surgery, limits of agreement comparing thermodilution methods were smaller than comparing PCCI with thermodilution. Recalibration of PCCI is therefore advisable.
Propofol inhibits phorbol 12, 13‐dibutyrate‐induced, protein kinase C‐mediated contraction of rat aortic smooth muscle
Authors: Yu J. , Kakutani T. , Mizumoto K. , Hasegawa A. , Hatano Y.
Published: September 2006

Background: Propofol induces dose‐dependent vasodilation and hypotension in the clinical situation, and protein kinase C (PKC)‐mediated Ca2+sensitization plays an important role in vascular smooth muscle contraction. This study is designed to examine the effects of propofol on the active phorbol ester (phorbol 12, 13‐dibutyrate; PDBu)‐induced, PKC‐mediated contraction of rat aortic smooth muscle.

Methods: The PDBu‐induced contraction of endothelium‐denuded rat aortic rings was measured in the presence or absence of PKC inhibitor, bisindolylmaleimide I, or propofol, using isometric force transducers. The PDBu‐induced PKC phosphorylation of endothelium‐denuded rat aortic strips was detected in the presence or absence of bisindolylmaleimide I or propofol, using Western blotting.

Results: PDBu, but not the inactive phorbol ester, 4‐α‐phorbol 12‐myristate‐13‐acetate, dose‐dependently induced both a slowly developing sustained contraction and PKC phosphorylation of rat aortic smooth muscle, reaching the peak level at the concentration of 10−6M. The PDBu (10−6M)‐induced contraction was dose‐dependently inhibited by bisindolylmaleimide I with reductions of 6.8 ± 1.8% (P> 0.05), 39.8 ± 8.7% (P< 0.01) and 96.7 ± 1.4% (P< 0.01) in response to concentrations of 5 × 10−7M, 10−6× M and 5 × 10−6M, respectively, and by propofol with decreases of 5.2 ± 1. 6% (P> 0.05), 9.4 ± 1.7% (P< 0.05), 65.3 ± 9.2% (P< 0.01) and 96.2 ± 1.6% (P< 0.01) in response to concentrations of 5 × 10−7M, 10−6M, 5 × 10−6M and 10−5M, respectively. Both bisindolylmaleimide I and propofol also inhibited the PDBu‐induced increase in the density of the phosphorylated PKC bands in a dose‐dependent manner, with decreases of 6.3 ± 2.8% (P> 0.05), 42.9 ± 3.2% (P< 0.01) and 96.6 ± 3.4% (P< 0.01) in response to 5 × 10−7M, 10−6M or 5 × 10−6M bisindolylmaleimide I, respectively, and with decreases of 4.2 ± 2.5% (P> 0.05), 13.5 ± 1.7% (P< 0.05), 69.5 ± 3.5% (P< 0.01) and 95.3 ± 4.3% (P< 0.01) in response to 5 × 10−7M, 10−6M, 5 × 10−6M and 10−5M propofol, respectively.

Conclusion: Propofol dose‐dependently inhibits PDBu‐induced, PKC‐mediated contraction of rat aortic smooth muscle.
Comparison of auditory evoked potential parameters for predicting clinically anaesthetized state
Authors: Kumar A. , Anand S. , Yaddanapudi L. N.
Published: September 2006

Background:  Most of the research efforts to monitor the depth of anaesthesia using the mid‐latency auditory evoked potential (MLAEP) signal in humans are based on the detection of the amplitudes and latencies of the signal peaks. Attempts have also been made to combine different time‐domain and frequency‐domain parameters. A comparison of different parameters is required to identify those which best discriminate the awake state from the anaesthetized state.

Methods:  Although the sensitivity of MLAEP signal peaks is appreciable in awake and light anaesthesia states, it is reduced considerably at the moderate anaesthesia level, rendering this method unsuitable for predicting the surgical stage of anaesthesia. To overcome this problem, a numerically derived quantity – the morphology index – was used which does not require location of the peaks of the signal, but, at the same time, reflects the changes in both the latency and amplitude of the peaks. AEPs were recorded in the hospital for 18 patients during various states, i.e. awake, induction, unconscious and after regaining consciousness from halothane anaesthesia. The peak latencies, amplitudes, morphology index and peak power frequency (PPF) were calculated.

Results:  The sensitivity and specificity of PPF (89% and 95%, respectively) were found to be better than those for Pa and Nb peak amplitudes, their latencies and the morphology index. In addition, PPF showed minimum inter‐patient variation. The mean value (standard deviation) of this parameter was 26.9 (0.67) during the awake state, decreased to 17.1 (1.2) during the anaesthetized state, and increased again to 26.1 (0.93) when the patients regained full consciousness.

Conclusion:  PPF is the best of the four studied MLAEP parameters for the clinical characterization of the anaesthetized state during surgery.
Outcome after heroin overdose and cardiopulmonary resuscitation
Authors: Boyd J. J. , Kuisma M. J. , Alaspää A. O. , Vuori E. , Repo J. V. , Randell T. T.
Published: September 2006

Background:  The survival of heroin overdose patients resuscitated from cardiac arrest is reported to be poor. The aim of our study was to investigate the outcome and characteristics of survivors after cardiac arrest caused by heroin overdose.

Methods:  This was a retrospective study in a medium‐sized city (population, 560,000). Between 1 January 1997 and 31 December 2000, there were 94 combined cardiac arrests caused by acute drug poisonings. The main outcome measure was survival to discharge.

Results:  Cardiopulmonary resuscitation was attempted in 19 heroin overdose patients (group A) and in 53 patients with cardiac arrest caused by other poisonings (group B). Three (16%) vs. six (11%) patients were discharged alive (group A vs. B, respectively). The survivors in group A had an Emergency Medical Service (EMS)‐witnessed cardiac arrest or the Emergency Dispatching Centre was called before the arrest occurred. There was no statistically significant difference between the two groups in terms of survival. Survivors in both groups suffered from acute renal failure (two), hypoglycaemia (four) and hypothermia (three).

Conclusion:  Survival after cardiac arrest caused by heroin overdose is possible if the arrest is EMS witnessed or the Emergency Dispatching Centre is called before the cardiac arrest occurs. In comparison with cardiac arrests caused by other poisonings, there was no difference in survival. The incidence and mechanism of hypoglycaemia should be examined in further studies.
Semen Technologies in Dog Breeding: an Update
Authors: Peña FJ , Núñez‐Martínez I , Morán JM
Published: September 2006

Contents

Pure dog breeding is experiencing growing interest. Assisted reproductive technologies are each time demanded more by the small animal practitioner. In this paper different semen technologies are briefly reviewed under the perspective of the authors. In addition, new trends in the evaluation of canine ejaculates, developed in the laboratory of the authors are discussed. The existence of sperm subpopulations defined based both on kinematics and morphometric characteristics of the spermatozoa is now widely accepted by the scientific community. In the laboratory of the authors new, simpler and more straightforward statistical tools have been used to disclose the sperm subpopulation structure in the canine ejaculate. The study of the sperm subpopulation structure and its changes after cryopreservation has allowed us to gain an insight into the differences in freezeability among dogs, and also predict to a great extent the outcome of a cryopreservation procedure of a given semen sample. New techniques to evaluate early membrane changes have also been recently developed in our laboratory.