bluuebunny/crossref_metadata_2025 huggingface dataset:
Cost‐effectiveness analysis of screening modalities for breast cancer in Japan with special reference to women aged 40–49 years
Authors: Ohnuki Koji , Kuriyama Shinichi , Shoji Narumi , Nishino Yoshikazu , Tsuji Ichiro , Ohuchi Noriaki
Published: August 2006

Although the introduction of screening mammography in Japan would be expected to reduce mortality from breast cancer, the optimal screening modality in terms of cost‐effectiveness remains unclear. We compared the cost‐effectiveness ratio, defined as the cost required for a life‐year saved, among the following three strategies: (1) annual clinical breast examination; (2) annual clinical breast examination combined with mammography; and (3) biennial clinical breast examination combined with mammography for women aged 30–79 years using a hypothetical cohort of 100 000. The sensitivity, specificity and early breast cancer rates were derived from studies conducted from 1995 to 2000 in Miyagi Prefecture. The treatment costs were based on a questionnaire survey conducted at 13 institutions in Japan. We used updated parameters that were needed in the analysis. Although the effectiveness of treatment in terms of the number of expected survival years was highest for annual combined modality, biennial combined modality had a higher cost‐effectiveness ratio, followed by annual combined modality and annual clinical breast examination in all age groups. In women aged 40–49 years, annual combined modality saved 852.9 lives and the cost/survival duration was 3 394 300 yen/year, whereas for biennial combined modality the corresponding figures were 833.8 and 2 025 100 yen/year, respectively. Annual clinical breast examination did not confer any advantages in terms of effectiveness (815.5 lives saved) or cost‐effectiveness (3 669 900 yen/year). While the annual combined modality was the most effective with respect to life‐years saved among women aged 40–49 years, biennial combined modality was found to provide the highest cost‐effectiveness. (Cancer Sci 2006; 97: 1242–1247)
Nutrition and allergic disease
Authors: Tricon S. , Willers S. , Smit H. A. , Burney P. G. , Devereux G. , Frew A. J. , Halken S. , Høst A. , Nelson M. , Shaheen S. , Warner J. O. , Calder P. C.
Published: August 2006

The prevalence of asthma and allergic diseases has increased dramatically over the past few decades with the highest incidence occurring in children. Most asthma and related atopic disorders have their origins in early life. Thus, it is imperative to understand the early life origins of the disease in order to identify targets for prevention and early intervention. Although atopic diseases have genetic determinants, the increased incidence of these diseases has occurred far too rapidly for genetic changes to explain the increase. This, most likely, results from changes in environmental influences acting on a pre‐existent genetic susceptibility. One of the environmental changes over the last 20–40 years that could have contributed to the recent increase in atopic diseases is diet. Food allergy is often one of the earliest manifestations of atopy, and sensitization to food is a risk factor for the subsequent appearance of respiratory allergy and asthma. However, studies investigating the effects of dietary restrictions on the prevention of allergy have been disappointing. On the other hand, current data suggests that exclusive breastfeeding should be encouraged for at least 4–6 months in infants at both high and low risk of atopy. Increased risk of asthma has also been observed in low birth weight infants, suggesting that under‐nutrition can detrimentally alter foetal development. Epidemiological and immunological studies also suggest that dietary modification or supplementation in the foetal and early life could reduce the development of atopic diseases. The current dietary hypotheses relate to antioxidants, lipids, electrolytes and probiotics. The aims of this report are: (i) to assess the best methods to analyse nutrient intake and nutrient status; (ii) to review the existing epidemiological evidence for an association between dietary intake (nutrients and food) and allergic diseases; and (iii) to define the windows of opportunity for nutritional supplementation to be used as a preventative strategy for asthma and allergy.
Influence of stream geomorphic condition on fish communities in Vermont, U.S.A.
Authors: SULLIVAN S. MAŽEIKA P. , WATZIN MARY C. , HESSION W. CULLY
Published: August 2006

1. Evaluations of stream geomorphic condition may increase our understanding of the composite effects of human‐induced habitat change on fish communities. Using systematic sampling of 44 reaches spread across 26 rivers in Vermont from 2002 through 2004, we tested the hypothesis that stream reaches in reference geomorphic condition would support fish assemblages that differed in diversity and productivity from fish communities found in reaches of poorer geomorphic condition.

2. At each study reach, we sampled the fish community, identified the morphological unit according to common stream classification systems and then evaluated the extent of deviation from reference geomorphic condition using a regionally adapted geomorphic assessment methodology.

3. We used principal component analysis (PCA) and linear regression to build exploratory models linking stream geomorphic condition to fish community characteristics.

4. Our results suggest that geomorphic condition significantly influences fish community diversity, productivity and condition. Geomorphic condition was a significant factor in all of our fish community models. In conjunction with additional reach characteristics, geomorphic condition explained up to 31% of the total variance observed in models for species diversity of fish communities, 44% of the variance in assemblage biomass and 45% of the variance in a regional index of biotic integrity.

5. Our work builds on single‐species evidence that geomorphic characteristics represent important local‐scale fish‐habitat variables, showing that stream geomorphic condition is a dominant factor affecting entire fish communities. Our results enhance our understanding of the hierarchy of factors that influences fish community diversity and organisation and support the use of geomorphic condition assessments in stream management.
The effect of whey protein concentrates and hydrocolloids on the texture and colour characteristics of chicken sausages
Authors: Andrès Silvina , Zaritzky Noemí , Califano Alicia
Published: August 2006

The effects of fat reduction by increasing water content and the addition of whey protein and hydrocolloids on the instrumental texture profile, microstructure and water holding capacity of low‐fat chicken sausages were analysed. Low‐fat sausages were prepared with fresh breast chicken meat; in all formulations, a 3:7 ratio guar/xanthan gum was used. A factorial design with three levels of added fat (0%, 1.98% and 4.96%), two levels of whey protein concentrate (0.64% and 1.94%), and two levels of the hydrocolloids (0.13% and 0.32%) was applied. Samples were heat‐processed (73 °C final internal temperature) and, after cooling, chemical composition of the sausages was determined and scanning electron microscopic images were obtained. Colour was measured with a tristimulus reflectance colorimeter. Texture profile analysis of sausages was performed and the results were related to sample formulations. Extra‐lean products with a fat content lower than 0.5 g/100 g product showed very good quality attributes determined by a sensory panel.
Heat transfer coefficients to canned green peas during end‐over‐end sterilisation
Authors: Garrote Raúl L. , Silva Enrique R. , Roa Rubén D. , Bertone Ricardo A.
Published: August 2006

The effect of temperature (110, 120 and 130 °C), rotation speed (5, 10 and 15 r.p.m.) and headspace (4, 8 and 12 mm) on heat transfer coefficients to canned green peas during end‐over‐end sterilisation was studied using response surface methodology. The models developed for fluid‐to‐particle heat transfer coefficient, hfp, and overall heat transfer coefficient, U, were adequate, showing no significant lack of fit and satisfactory correlation coefficients. For the two responses, temperature, rotation speed and headspace have a significant effect. U, ranged between 477 and 905 W m−2 °C−1, while hfp, fluctuated between 480 and 1950 W m−2 °C−1. The highest hfp and U values are obtained at high temperatures, rotation speeds and headspaces. The verification of the prediction models was satisfactory. Dimensionless correlations were developed for hfp and U, with equations showing a good agreement with the experimental data. Heat transfer to liquids and particles was modelled using the Reynolds number, the Prandtl number and adimensional headspace.
Lipase‐catalysed acidolysis of lard with caprylic acid to produce structured lipid
Authors: Zhao Haizhen , Lu Zhaoxin , Lu Fengxia , Bie Xiaomei , Liu Zhanmin , Zeng Xiaoxiong
Published: August 2006

Enzymatic acidolysis of lard with caprylic acid was investigated. Of the five lipases that were tested in the initial screening, immobilised lipase TL IM from Thermomyces lanuginosus resulted in the highest incorporation of caprylic acid into lard. This enzyme was further studied for the effect of enzyme load, organic solvent, substrate ratio, reaction time and temperature. HPLC was used to analyse the products from the acidolysis reaction. The highest incorporation was attained at 15% enzyme load. Among the solvents tested, n‐hexane was the best reaction medium for the acidolysis of lard with caprylic acid. Time course studied suggests that the incorporation of caprylic acid into lard was increased up to 37.7 mol% after 24 h. Desirable mole ratio of lard to caprylic acid was 1:2, caprylic acid incorporation up to 34.2 mol%. Temperature had no significant effect on enzyme activity in the range of 40–80 °C.
Improvement of the functionality of a potential fruit insoluble fibre by micron technology
Authors: Chau Chi‐Fai , Wen Yu‐Ling , Wang Yi‐Ting
Published: August 2006

An insoluble food fibre was micronised to different microsizes (6.77–29.5 μm) by three different micron technologies using optimised conditions. The effects of different micronisation treatments and particle sizes on the characteristics and various physicochemical properties of this insoluble fibre were studied. As particle size decreased, the bulk density of the insoluble fibre was significantly (P < 0.05) decreased. A redistribution of fibre components from insoluble to soluble fractions was observed. The treatments, especially the high‐pressure micronisation, effectively (P < 0.05) increased the physicochemical properties (e.g. water‐holding capacity, swelling capacity, oil‐holding capacity, cation‐exchange capacity and glucose‐adsorption capacity) and also the inhibitory activity towards α‐amylase and pancreatic lipase of the insoluble fibre to different extent (from several up to c. fifteenfold). Our results suggested that micronisation treatments would provide an opportunity to improve the functionality of the insoluble fibre and exploit its potential applications as a functional ingredient in fibre‐rich products.
Partial purification and characterisation of polyphenol oxidase from celery root (Apium graveolens L.) and the investigation of the effects on the enzyme activity of some inhibitors
Authors: Aydemir Tülin , Akkanlı Gülay
Published: August 2006

Polyphenol oxidase (PPO) of celery root was extracted and partially purified by (NH4)2SO4 fractionation and dialysis. Optimum pH and temperature were found at pH 7.0 and 30 °C, and Km and Vmax values were 29 mm and 5560 U mL−1 min−1 with catechol, respectively. The activation energy of the enzyme with catechol was 17.9 kJ mol−1 at pH 7.0. In electrophoretic seperation, six isoenzymes were detected with dl‐dopa substrate. PPO showed activity to catechol, 4‐methylcatechol, pyrogallol, gallic acid, dl‐dopa. l‐Tyrosine was also tested but was not oxidised by celery root PPO. β‐Mercaptoethanol was found to be the most effective inhibitor. (NH4)2SO4, NaCl, KCl and sucrose appeared to be protective agents of celery root PPO against thermal denaturation. Metal ions (Cu2+, Zn2+, Mn2+) were poor inhibitors of the celery root PPO at 1 mm. PPO activity was also inhibited by CaCl2, NaCl, BaCl2, FeSO4 and NiCl2.
Hydrological disturbance benefits a native fish at the expense of an exotic fish
Authors: LEPRIEUR F. , HICKEY M. A. , ARBUCKLE C. J. , CLOSS G. P. , BROSSE S. , TOWNSEND C. R.
Published: August 2006

Some native fish in New Zealand do not coexist with introduced salmonids. Previous studies of disjunct distributions of exotic brown troutSalmo truttaand native galaxiids demonstrated native extirpation except where major waterfalls prevented upstream migration of trout. In the Manuherikia River system, we predicted that water abstraction might be a further factor controlling the spatial distribution of both the invader and a native fish.

We applied multiple discriminant function analyses to test for differences in environmental conditions (catchment and instream scales) at sites with roundhead galaxiasGalaxias anomalusand brown trout in sympatry and allopatry. We then used a supervised artificial neural network (ANN) to predict the presence–absence ofG. anomalusand brown trout (135 sites). The quantification of contributions of environmental variables to ANN models allowed us to identify factors controlling their spatial distribution.

Brown trout can reach most locations in the Manuherikia catchment, and often occur upstream ofG. anomalus. Their largely disjunct distributions in this river are mediated by water abstraction for irrigation, together with pool habitat availability and valley slope. Trout are more susceptible than the native fish to stresses associated with low flows, and seem to be prevented from eliminating galaxiid populations from sites in low gradient streams where there is a high level of water abstraction.

Synthesis and applications. In contrast to many reports in the literature, our results show that hydrological disturbance associated with human activities benefits a native fish at the expense of an exotic in the Manuherikia River, New Zealand. Water abstraction is also known to have negative impacts on native galaxiids, therefore we recommend restoring natural low flows to maintain sustainable habitats for native galaxiids, implementing artificial barriers in selected tributaries to limit trout predation on native fish, and removing trout upstream.
Line‐intercept laboratory subsampling estimates periphyton biovolumes more efficiently than standard methods
Authors: FRAPPIER BRIAN , DUCEY MARK J.
Published: August 2006

Algal assemblages have been included in biological monitoring in a number of national, large‐scale and long‐term biological monitoring and assessment programmes of streams, lakes and wetlands. However, there has been no substantial investigation of alternative enumeration strategies.

We compared the sampling efficiency of the common periphyton subsampling strategies of counting 300 cells by strip counts or random fields and measuring 10 cells per taxon for biovolume, with line‐intercept sampling (LIS), using samples collected from four streams differing in canopy cover and discharge. We also simulated the optimum ratio of cells tallied to cells measured for biovolume for all approaches.

LIS was 1·6–5·5 times more efficient at estimating algal taxa biovolume than the 300‐cell count methods. LIS performed best relative to conventional 300‐cell count methods in streams with high biovolume, although efficiency gains were still noticeable in low biovolume streams. In addition, LIS tended to detect more taxa than the conventional 300‐cell target biological assessment methods.

In simulations, LIS was more efficient than the conventional methods for nearly all combinations of target cell count and cells measured for biovolume. No single optimal ratio of cells counted to cells measured was found. The target cell count that resulted in the greatest efficiency was higher in assemblages with large variation in cell density. Likewise, assemblages with high variance in taxa biovolume were most efficiently sampled by measuring more cells.

Synthesis and applications. An increase in sampling efficiency as a result of greater adoption of LIS sampling may result in more accurate estimation of the relationships between periphyton community composition and environmental factors, and more sensitive detection of impacts using stream periphyton. Additionally, LIS may improve estimates in other ecological research fields employing microscopic counting chambers.
Impacts of rain forest fragmentation on butterflies in northern Borneo: species richness, turnover and the value of small fragments
Authors: BENEDICK S. , HILL J. K. , MUSTAFFA N. , CHEY V. K. , MARYATI M. , SEARLE J. B. , SCHILTHUIZEN M. , HAMER K. C.
Published: August 2006

Widespread and rapid losses of tropical rain forests have made understanding the responses of species to rain forest fragmentation an area of major concern. In this study we examined the impacts of habitat fragmentation on the species richness and faunal composition of butterflies in tropical rain forests in Sabah, Borneo. We analysed patterns of both α‐ and β‐diversity to assess the relative importance of differences in patch size, isolation and vegetation structure on the diversity and similarity of species assemblages. We used additive partitioning to assess the relative contributions of intact forest and forest remnants to overall species richness at a landscape scale and we examined which traits of species best predicted their responses to fragmentation.

Species richness and diversity in rain forest remnants was significantly positively related to remnant size and significantly negatively related to isolation, in keeping with theories of island biogeography. Species assemblages at different sites were significantly nested, with those species most adversely affected by forest fragmentation having a narrow range of larval host‐plants and, to a lesser extent, being large‐bodied. No species endemic to Borneo was recorded in forest remnants smaller than 4000 ha, but even the smallest remnant (120 ha) supported species with geographical distributions confined within Sundaland (West Malaysia and the islands of the Sunda Shelf).

Although assemblages were significantly nested, they departed substantially from perfect nestedness, with some species recorded only or predominantly in small, relatively depauperate remnants. As a result there was substantial β‐diversity among sites, which was related to variation in both fragment size and vegetation structure. At the landscape scale, diversity within sites was less than that between sites, and the majority of the diversity between sites was related to variation in fragment size.

Synthesis and applications. Substantial diversity was added to the assemblage of butterflies in Bornean rain forests by virtue of species differences among fragments, which were related mainly to differences in patch size and vegetation structure. The data reported indicate that, despite having lower species richness, relatively small and isolated remnants of rain forest make a substantial contribution to regional diversity. Small isolated forest remnants are generally accorded low conservation status and given little protection, with the result that they often disappear over time because of continued anthropogenic disturbance. The results of this study indicate that the conservation value of small remnants of forest, in particular their contribution to environmental heterogeneity, should not be overlooked.
Using the stable isotope marker 44Ca to study dispersal and host‐foraging activity in parasitoids
Authors: WANNER HEIKE , GU HAINAN , HATTENDORF BODO , GÜNTHER DETLEF , DORN SILVIA
Published: August 2006

Dispersal and host‐foraging activity are important behavioural characteristics for parasitoid species used as biological control agents. Appropriate marking techniques are often needed for field investigations into these behaviours because of the small size of parasitoids. This study developed a novel technique using the rare stable calcium isotope 44Ca to mark parasitoids.

As demonstrated with a tri‐trophic model system consisting of cabbage plant Brassica oleracea, caterpillar Pieris brassicae and gregarious parasitoid Cotesia glomerata, marking parasitoids with the isotope 44Ca is systemic and non‐disruptive. Significant uptake and translocation of 44Ca occurred in cabbage plants after being drenched with 50 mMol aqueous isotope solution, and the isotope was transferred to wasps emerging from the parasitized host caterpillars that fed on the isotope‐enriched plant. The isotope enrichment did not adversely influence the survivorship of hosts or the development of parasitoids.

The 44Ca‐enriched female wasps could pass the isotope marker further via oviposition into the parasitized host caterpillars, hence allowing the marker to be transferred across parasitoid generations. Greenhouse release experiments validated the transferability of 44Ca from the enriched wasps to hosts through parasitism. The 95% upper confidence limit for the mean 44Ca/40Ca isotope ratio in the hosts without 44Ca enrichment (control) could be used as a statistical marking criterion to identify reliably the individual parasitized hosts within the first 3 days of parasitism.

Synthesis and applications. We have, for the first time, documented the efficient transfer of a stable isotope marker from enriched parasitoids to host insects through parasitism. This isotope technique enables the study of dispersal and host‐foraging activity of parasitoids in the field without having to recapture marked individual parasitoids. Information on the dispersal pattern and host‐foraging activity of the parasitoid species concerned is obtained from the spatial distribution of the parasitized marked host insects. Furthermore, this isotope technique can be used to quantify the efficacy of parasitism by the parasitoids released in the field.
Beyond control: wider implications for the management of biological invasions
Authors: HULME PHILIP E.
Published: August 2006

Government departments, environmental managers and conservationists are all facing escalating pressure to address and resolve a diversity of invasive alien species (IAS) problems. Yet much research to date is primarily concerned with quantifying the scale of the problem rather than delivering robust solutions and has not adequately addressed all stages of the invasion process, and only a few studies embrace the ecosystem approach.

Three successive steps, prevention, eradication and control, form the cornerstones of recommended best practices aimed at managing IAS. The goal of such actions is the restoration of ecosystems to preserve or re‐establish native biodiversity and functions.

Prevention is widely promoted as being a more environmentally desirable strategy than actions undertaken after IAS establishment, yet is hindered by the difficulty in separating invasive from non‐invasive alien species. Furthermore, the high number of candidate IAS, the investment required in taxonomic support and inspection capacity, and the expense of individual risk assessments may act against the net benefits of prevention. More rewarding avenues may be found by pursuing neural networks to predict the potential composition of pest assemblages in different regions and/or model introduction pathways to identify likely invasion hubs.

Rapid response should be consequent on early detection but, when IAS are rare, detection rates are compromised by low occurrence and limited power to discern significant changes in abundance. Power could be increased by developing composite indicators that track trends in a suite of IAS with similar life histories, shared pathways and/or habitat preferences.

The assessment of management options will benefit from an ecosystem perspective that considers the manipulation of native competitors, consumers and mutualists, and reviews existing management practices as well as mitigates other environmental pressures. The ease with which an IAS can be targeted should not only address the direct management effects on population dynamics but also indirect effects on community diversity and structure. Where the goal is to safeguard native biodiversity, such activities should take into account the need to re‐establish native species and/or restore ecosystem function in the previously affected area.

Synthesis and applications. A comprehensive approach to IAS management should include consideration of the: (i) expected impacts; (ii) technical options available; (iii) ease with which the species can be targeted; (iv) risks associated with management; (v) likelihood of success; and (vi) extent of public concern and stakeholder interest. For each of these issues, in addition to targeting an individual species, the management of biological invasions must also incorporate an appreciation of other environmental pressures, the importance of landscape structure, and the role of existing management activities and restoration efforts.
What controls the population dynamics of the invasive thistle Carduus nutans in its native range?
Authors: JONGEJANS EELKE , SHEPPARD ANDY W. , SHEA KATRIONA
Published: August 2006

The invasive thistle Carduus nutans causes major economic losses in the Americas, Australia and New Zealand. For the first time, we have modelled its population dynamics in its native range, Eurasia, where it rarely reaches problematic densities, in order to identify ways to improve management strategies for this weed in the invaded range.

In particular, we investigated whether specialist enemies in the thistle's native range suppress thistle populations, as predicted by the enemy‐release hypothesis, and, if so, how this effect relates to other factors that may limit population growth.

We constructed population transition matrix models with data from three French populations. A vital rate elasticity analysis revealed that reproduction determines between 33% and 61% of the projected growth rate of the populations, and thus is a key driver of the population dynamics of this monocarpic short‐lived perennial.

Decreases in population size were predicted by the models for all three populations (λ < 1). Using limiting factor omission analyses, we showed that the suite of native insect herbivores causing seed losses had a larger impact than the joint effects of rosette damage by sheep and summer drought acting on seedling establishment. Removal of insect herbivores increased the native population growth rate by 166% on average; removal of sheep damage and summer drought from the model increased population growth by 51%. Specialist herbivores and drought interacted synergistically to affect reproduction.

Synthesis and applications. We show that vital rate elasticity analysis provides more management information than elasticity analysis on the level of matrix elements, particularly when management options affect only certain vital rates. For example, it can be used to make predictions about the effectiveness of predispersal floral herbivores in control management. The model can also help identify ways in which biocontrol can be augmented using integrated weed management that reduces seedling establishment probabilities, for example by preventing overgrazing. This method illustrates how native range studies of invasive species can be used to generate insights into managing populations in the invaded range.
Secondary metabolic gene cluster silencing in Aspergillus nidulans
Authors: Bok Jin Woo , Noordermeer Daan , Kale Shubha P. , Keller Nancy P.
Published: August 2006

In contrast to most primary metabolism genes, the genes involved in secondary metabolism and certain nutrient utilization pathways are clustered in fungi. Recently a nuclear protein, LaeA, was found to be required for the transcription of several secondary metabolite gene clusters in Aspergillus nidulans. Here we show that LaeA regulation does not extend to nutrient utilization or the spoC1 sporulation clusters. One of the secondary metabolite clusters regulated by LaeA contains the positive regulatory (i.e. aflR) and biosynthetic genes required for biosynthesis of sterigmatocystin (ST), a carcinogenic toxin. Analysis of ST gene cluster expression indicates LaeA regulation of the cluster is location specific as transcription of genes bordering the ST cluster are unaffected in a ΔlaeA mutant and placement of a primary metabolic gene, argB, in the ST cluster resulted in argB silencing in the ΔlaeA background. ST cluster gene expression was remediated when an additional copy of aflR was placed outside of the cluster but not when placed in the cluster. Site‐specific mutation of an s‐adenosyl methionine (AdoMet) binding site in LaeA generated a ΔlaeA phenotype suggesting the protein to be a methyltransferase.
Eukaryotic cyclophilin as a molecular switch for effector activation
Authors: Coaker Gitta , Zhu George , Ding Zhaofeng , Van Doren Steven R. , Staskawicz Brian
Published: August 2006

Gram‐negative phytopathogenic bacteria, such as Pseudomonas syringae, deliver multiple effector proteins into plant cells during infection. It is hypothesized that certain plant and mammalian effector proteins need to traverse the type III secretion system unfolded and are delivered into host cells as inactive enzymes. We have previously identified cyclophilin as the Arabidopsis eukaryotic activator of AvrRpt2, a P. syringae effector that is a cysteine protease. Cyclophilins are general folding catalysts and possess peptidyl‐prolyl cis/trans isomerase (PPIase) activity. In this paper, we demonstrate the mechanism of AvrRpt2 activation by the Arabidopsis cyclophilin ROC1. ROC1 mutants lacking PPIase enzymatic activity were unable to activate AvrRpt2. Furthermore, nuclear magnetic resonance spectroscopy revealed a structural change in AvrRpt2 from an unfolded to a folded state in the presence of ROC1. Using in vitro binding assays, ROC1's consensus binding sequence was identified as GPxL, a motif present at four sites within AvrRpt2. The GPxL motifs are located in close proximity to AvrRpt2's catalytic triad and are required for protease activity both in vitro and in planta. These data suggest that after delivery into the plant cell during infection, cyclophilin binds AvrRpt2 at four sites and properly folds the effector protein by peptidyl‐prolyl cis/trans isomerization.
Attenuation of penicillin resistance in a peptidoglycan O‐acetyl transferase mutant of Streptococcus pneumoniae
Authors: Crisóstomo M. Inês , Vollmer Waldemar , Kharat Arun S. , Inhülsen Silja , Gehre Florian , Buckenmaier Stephan , Tomasz Alexander
Published: August 2006

The level of penicillin resistance in clinical isolates of Streptococcus pneumoniae depends not only on the reduced affinity of penicillin binding proteins (PBPs) but also on the functioning of enzymes that modify the stem peptide structure of cell wall precursors. We used mariner mutagenesis in search of additional genetic determinants that may further attenuate the level of penicillin resistance in the bacteria. A mariner mutant of the highly penicillin‐resistant S. pneumoniae strain Pen6 showed reduction of the penicillin minimum inhibitory concentration (MIC) from 6 to 0.75 μg ml−1. Decrease in penicillin MIC was also observed upon introduction of the mutation (named provisionally adr, for attenuator of drug resistance) into representatives of major epidemic clones of penicillin‐resistant pneumococci. Attenuation of resistance levels was specific for β‐lactams. The adr mutant has retained unchanged (low affinity) PBPs, unaltered murM gene and unchanged cell wall stem peptide composition, but the mutant became hypersensitive to exogenous lysozyme and complementation experiments showed that both phenotypes – reduced resistance and lysozyme sensitivity – were linked to the defective adr gene. DNA sequence comparison and chemical analysis of the cell wall identified adr as the structural gene of the pneumococcal peptidoglycan O‐acetylase.
The cell biology of secondary endosymbiosis – how parasites build, divide and segregate the apicoplast
Authors: Vaishnava Shipra , Striepen Boris
Published: August 2006

Protozoan parasites of the phylum Apicomplexa harbour a chloroplast‐like organelle, the apicoplast. The biosynthetic pathways localized to this organelle are of cyanobacterial origin and therefore offer attractive targets for the development of new drugs for the treatment of malaria and toxoplasmosis. The apicoplast also provides a unique system to study the cell biology of endosymbiosis. This organelle is the product of secondary endosymbiosis, the marriage of an alga and an auxotrophic eukaryote. This origin has led to a fascinating set of novel cellular mechanisms that are clearly distinct from those employed by the plant chloroplast. Here we explore how the apicoplast interacts with its ‘host’ to secure building blocks for its biogenesis and how the organelle is divided and segregated during mitosis. Considerable advances in parasite genetics and genomics have transformed apicomplexans, long considered hard to study, into highly tractable model organisms. We discuss how these resources might be marshalled to develop a detailed mechanistic picture of apicoplast cell biology.
Comparative proteomic analysis of two Entamoeba histolytica strains with different virulence phenotypes identifies peroxiredoxin as an important component of amoebic virulence
Authors: Davis Paul H. , Zhang Xiaochun , Guo Jianhua , Townsend R. Reid , Stanley Samuel L.
Published: August 2006

Entamoeba histolytica is a protozoan intestinal parasite that causes amoebic colitis and amoebic liver abscess. To identify virulence factors of E. histolytica, we first defined the phenotypes of two E. histolytica strains, HM‐1:IMSS, the prototype virulent strain, and E. histolytica Rahman, a strain that was reportedly less virulent than HM‐1:IMSS. We found that compared with HM‐1:IMSS, Rahman has a defect in erythrophagocytosis and the ability to cause amoebic colitis in human colonic xenografts. We used differential in‐gel 2D electrophoresis to compare the proteome of Rahman and HM‐1:IMSS, and identified six proteins that were differentially expressed above a fivefold level between the two organisms. These included two proteins with antioxidative properties (peroxiredoxin and superoxide dismutase), and three proteins of unknown function, grainin 1, grainin 2 and a protein containing a LIM‐domain. Overexpression of peroxiredoxin in Rahman rendered the transgenic trophozoites more resistant to killing by H2O2 in vitro, and infection with Rahman trophozoites expressing higher levels of peroxiredoxin was associated with higher levels of intestinal inflammation in human colonic xenografts, and more severe disease based on histology. In contrast, higher levels of grainin appear to be associated with a reduced virulence phenotype, and E. histolytica HM‐1:IMSS trophozoites infecting human intestinal xenografts show marked decreases in grainin expression. Our data indicate that there are definable molecular differences between Rahman and HM‐1:IMSS that may explain the phenotypic differences, and identify peroxiredoxin as an important component of virulence in amoebic colitis.
Treatment of Chlamydia trachomatis with a small molecule inhibitor of the Yersinia type III secretion system disrupts progression of the chlamydial developmental cycle
Authors: Wolf K. , Betts H. J. , Chellas‐Géry B. , Hower S. , Linton C. N. , Fields K. A.
Published: August 2006

The obligate intracellular bacterium Chlamydia trachomatis possesses a biphasic developmental cycle that is manifested by differentiation of infectious, metabolically inert elementary bodies (EBs) to larger, metabolically active reticulate bodies (RBs). The cycle is completed by asynchronous differentiation of dividing RBs back to a population of dormant EBs that can initiate further rounds of infection upon lysis of the host cell. Chlamydiae express a type III secretion system (T3SS) that is presumably employed to establish and maintain the permissive intracellular niche by secretion of anti‐host proteins. We hypothesize that T3SS activity is essential for chlamydial development and pathogenesis. However, the lack of a genetic system has confounded efforts to establish any role of the T3SS. We therefore employed the small molecule Yersinia T3SS inhibitor N’‐(3,5‐dibromo‐2‐hydroxybenzylidene)‐4‐nitrobenzohydrazide, designated compound 1 (C1), to examine the interdependence of the chlamydial T3SS and development. C1 treatment inhibited C. trachomatis but not T4SS‐expressing Coxiella burnetii development in a dose‐dependent manner. Although chlamydiae remained viable and metabolically active, they failed to divide significantly and RB to EB differentiation was inhibited. These effects occurred in the absence of host cell cytotoxicity and were reversible by washing out C1. We further demonstrate that secretion of T3S substrates is perturbed in C1‐treated chlamydial cultures. We have therefore provided evidence that C1 can inhibit C. trachomatis development and T3SS activity and present a model in which progression of the C. trachomatis developmental cycle requires a fully functional T3SS.
Extensive phage dynamics in Staphylococcus aureus contributes to adaptation to the human host during infection
Authors: Goerke Christiane , Wirtz Christiane , Flückiger Ursula , Wolz Christiane
Published: August 2006

Bacteriophages serve as a driving force in microbial evolution, adaptation to new environments and the pathogenesis of human bacterial infections. In Staphylococcus aureus phages encoding immune evasion molecules (SAK, SCIN, CHIPS), which integrate specifically into the β‐haemolysin (Hlb) gene, are widely distributed. When comparing S. aureus strain collections from infectious and colonizing situations we could detect a translocation of sak‐encoding phages to atypical genomic integration sites in the bacterium only in the disease‐related isolates. Additionally, significantly more Hlb producing strains were detected in the infectious strain collection. Extensive phage dynamics (intragenomic translocation, duplication, transfer between hosts, recombination events) during infection was shown by analysing cocolonizing and consecutive isolates of patients. This activity leads to the splitting of the strain population into various subfractions exhibiting different virulence potentials (Hlb‐production and/or production of immune evasion molecules). Thus, phage‐inducing conditions and strong selection for survival of the bacterial host after phage movement are typical for the infectious situation. Further in vitro characterization of phages revealed that: (i) SAK is encoded not only on serogroup F phages showing a conserved tropism for hlb but also on serogroup B phages which always integrate in a distinct intergenic region, (ii) the level of sak transcription correlates to phage inducibility but is independent of the phage localization in the chromosome, and (iii) phages can be stabilized extra‐chromosomally during their life cycle.
Salivary immunoglobulin A directed to oral microbial GroEL in patients with periodontitis and their potential protective role
Authors: Fukui M. , Hinode D. , Yokoyama M. , Tanabe S. , Yoshioka M.
Published: August 2006

The aim of this study was to identify salivary immunoglobulin A (IgA) directed to oral microbial GroEL in patients with periodontitis and to demonstrate their potential protective role through a reduction of inflammatory cytokine production induced by microbial GroEL. Using five different proteins belonging to the heat‐shock protein 60 family, Western immunoblot analysis of salivary IgA from 63 subjects revealed immunoreactivities with Campylobacter rectus GroEL and Porphyromonas gingivalis GroEL in subjects with periodontitis (P < 0.05) compared to control subjects. Using the BIACORE 1000 to measure the salivary IgA titers directed towards C. rectus GroEL, high resonance unit (RU) values were observed in the saliva samples from patients with periodontitis (P < 0.01). Furthermore, the number of teeth with deep pocket depth (≥5 mm) showed a high correlation coefficient with the RU value (r = 0.50, P < 0.01). C. rectus GroEL possessed the ability to stimulate the production of interleukin‐6 by gingival fibroblasts. Interestingly, salivary IgA antibody directed to C. rectus GroEL caused a partial inhibition of interleukin‐6 production. This study showed a relationship between high levels of salivary IgA directed to GroEL and periodontal disease severity. Although additional investigations are required, salivary IgA to GroEL may have a protective role by reducing the inflammatory response induced by GroEL derived from periodontopathogenic bacteria.
Production of interleukin‐8 in vitro by mononuclear cells isolated from human periapical lesions
Authors: Lukić A. , Vojvodic D. , Majstorović I. , Čolić M.
Published: August 2006

Introduction:  Interleukin‐8 (IL‐8) is an important mediator of inflammation. However, little is known about its production in chronic dental periapical lesions and this was the main aim of this work.

Methods:  Inflammatory cells were isolated from clinically different periapical lesions and analyzed by morphological criteria. The mononuclear cells were isolated, phenotypically analyzed by immunocytochemistry and cultivated in vitro. IL‐8 was measured in culture supernatants of these periapical lesion mononuclear cells (PL‐MNC) using a microbeads fluorescence assay.

Results:  We found a relatively high production of IL‐8 in 19 out of 21 periapical lesions included in the study. The level of IL‐8 and the proportion of neutrophil granulocytes were significantly higher in the group of symptomatic lesions, compared to the asymptomatic lesions, but there was no statistically significant correlation between these parameters. According to the predominance of CD3+ T cells and Ig+/CD19+ B cells and plasma cells, lesions were divided into T‐type and B‐type lesions, respectively. The levels of IL‐8 were significantly higher in the culture supernatants of PL‐MNC in the T‐type lesions and were positively correlated with the proportion of macrophages/dendritic cells (CD11c+ cells) and CD4+ T cells. Such a correlation was not shown in B‐type lesions.

Conclusion:  These results suggest that PL‐MNC are a significant source of IL‐8, which is probably an important chemokine for the migration and function of different cell types at the site of chronic inflammation.
Genotypic relatedness of yeasts in thrush and denture stomatitis
Authors: Song X. , Sun J. , Støre G. , Eribe E. R. K. , Hansen B. F. , Olsen I.
Published: August 2006

Background/aim:  Candida is an opportunistic pathogen. Understanding its genetic characters might increase our understanding of the pathogenesis of candidosis. We examined the genetic relationships of yeasts from the most common forms of oral candidosis: thrush and denture stomatitis.

Methods:  Yeasts were sampled from palate, buccal mucosa, gingival sulci/periodontal pockets and/or denture fitting surface of 19 thrush patients and 22 denture stomatitis patients. Random amplified polymorphic DNA and the Dendron computer‐assisted program were used to determine the genotypic relatedness of the yeasts.

Results:  A dendrogram generated from 105 thrush isolates had similarity coefficients (SAB) ranging from 0.58 to 1 with four clusters derived at SAB 68%. Another dendrogram was generated from 91 isolates from denture stomatitis, with SAB ranging from 0.59 to 1. Three clusters were established at SAB 71%. In a composite dendrogram incorporating the thrush and denture stomatitis data and orally healthy data compiled from a previous study, five genotypic clusters were generated at SAB 68%. Cluster II, the most dominant, comprised isolates from thrush, denture stomatitis and healthy conditions, while clusters III and IV contained yeasts mainly from thrush.

Conclusions:  Palatal yeast carriage was significantly increased in thrush and denture stomatitis, also after radiation, chemotherapy and denture wearing. The buccal mucosa was favorable for yeast colonization regardless of oral condition. Yeasts in thrush were more diverse than in conditions of oral health. The common clone (II) of infecting yeasts and commensals suggested that commensals could induce thrush and denture stomatitis, whereas the unique clones in thrush (III, IV) might have been established through strain replacement or maintenance with minor genetic variation.
Immunoglobulin G subclass antibody profiles in Porphyromonas gingivalis‐associated aggressive and chronic periodontitis patients
Authors: Takeuchi Y. , Aramaki M. , Nagasawa T. , Umeda M. , Oda S. , Ishikawa I.
Published: August 2006

Background/aims:  The immunoglobulin G (IgG) antibody response is considered to be protective and beneficial for the control of periodontal lesions. This study analysed IgG subclass antibody levels of Porphyromonas gingivalis in patients with both aggressive periodontitis (AgP) and chronic periodontitis (CP).

Methods:  Subgingival plaque and peripheral blood samples were collected from patients with localized AgP (n = 13), generalized AgP (n = 28) and generalized CP (n = 27) and from 14 periodontally healthy controls. P. gingivalis was identified in subgingival pockets using a polymerase chain reaction. Simultaneously, serum IgG subclass antibody against P. gingivalis whole cells/P. gingivalis fimbriae were measured using enzyme‐linked immunosorbent assay.

Results:  P. gingivalis was frequently detected in periodontitis patients. Anti‐P. gingivalis whole cell IgG1 was elevated in all P. gingivalis‐positive patients in the three periodontitis groups. Although increased anti‐P. gingivalis IgG1 was also observed in the bacterium‐positive healthy controls, the level was lower than that found in the three periodontitis groups. Levels of IgG1, IgG2, IgG3 and IgG4 to P. gingivalis did not differ among bacterium‐positive patients in the three periodontitis groups; a significant increase of IgG2 level was not observed in localized AgP. Anti‐fimbriae IgG subclass levels of IgG1, IgG2 and IgG4 did not differ among bacterium‐positive subjects in all groups, while the anti‐fimbriae IgG3 level in generalized CP was significantly higher than that in localized and generalized AgP.

Conclusions:  P. gingivalis infection elicited an IgG subclass antibody response in both periodontitis patients and healthy subjects, while higher anti‐P. gingivalis IgG1 levels were found in the three periodontitis groups compared with the healthy control group.