bluuebunny/crossref_metadata_2025_split huggingface dataset:
Helicobacter pylori HP1034 (ylxH) is required for motility
Authors: Van Amsterdam Karin , Van Der Ende Arie 
Published: September 2004

ABSTRACTBackground.  Helicobacter pylori motility is essential for the colonization and persistence in the human gastric mucosa. So far, more than 50 genes have been described to play a role in flagellar biosynthesis. H. pylori YlxH (HP1034) is annotated as an ATP‐binding protein. However, H. pylori YlxH shows similarity to proteins involved in the flagellar biosynthesis of other bacterial species. Moreover, H. pylori ylxH is found adjacent to genes involved in flagellar biosynthesis in the sequenced genomes of H. pylori 26695 and J99. We therefore aimed to determine the role of YlxH in H. pylori motility.Materials and methods.  Motility, flagellar biosynthesis and transcriptional regulation of genes encoding flagellar proteins was compared between H. pylori 11A and a knockout of ylxH in H. pylori 11A.Results.  The ylxH knockout in H. pylori 11A was nonmotile on soft agar plates, whereas H. pylori 11A was motile. Furthermore, the H. pylori 11A ylxH knockout lacked flagella, while H. pylori 11A possessed two to three flagella. Transcription of H. pylori flaG (HP0751), fliM (HP1031) and fliA (HP1032) was reduced in the H. pylori 11A ylxH¯ knockout, whereas transcription of flaA (HP0601) was not altered. However, Western blot analysis showed substantially reduced amounts of the major flagellin subunit FlaA in the H. pylori 11A ylxH knockout compared to H. pylori 11A.Conclusions.  H. pylori YlxH is essential for the assembly of flagella and hence for the motility of H. pylori.
Effect of H. pylori on the Expression of TRAIL, FasL and their Receptor Subtypes in Human Gastric Epithelial Cells and their Role in Apoptosis
Authors: Martin Jan Hendrik , Potthoff Andrej , Ledig Susanne , Cornberg Markus , Jandl Oliver , Manns Michael P. , Kubicka Stefan , Flemming Peer , Athmann Christoph , Beil Winfried , Wagner Siegfried 
Published: September 2004

ABSTRACTBackground and Aims.  In the human stomach expression of TNF‐related apoptosis inducing ligand (TRAIL) and its receptors and the modulatory role of Helicobacter pylori are not well described. Therefore, we investigated the effect of H. pylori on the expression of TRAIL, FasL and their receptors (TRAIL‐R1‐R4, Fas) in gastric epithelial cells and examined their role in apoptosis.Materials and Methods.  mRNA and protein expression of TRAIL, FasL and their receptors were analyzed in human gastric epithelial cells using RT‐PCR, Western blot, and immunohistochemistry. Gastric epithelial cells were incubated with FasL, TRAIL and/or H. pylori, and effects on expression, cell viability and epithelial apoptosis were monitored. Apoptosis was analyzed by histone ELISA, DAPI staining and immunohistochemistry.Results.  TRAIL, FasL and their receptor subtypes were expressed in human gastric mucosa, gastric epithelial cell primary cultures and gastric cancer cells. TRAIL, FasL and H. pylori caused a time‐ and concentration‐dependent induction of DNA fragmentation in gastric cancer cells with synergistic effects. In addition, H. pylori caused a selective up‐regulation of TRAIL, TRAIL‐R1 and Fas mRNA and protein expression in gastric cancer cells.Conclusions.  Next to FasL and Fas, TRAIL and all of its receptor subtypes are expressed in the human stomach and differentially modulated by H. pylori. TRAIL, FasL and H. pylori show complex interaction mediating apoptosis in human gastric epithelial cells. These findings might be important for the understanding of gastric epithelial cell kinetics in patients with H. pylori infection.
The rdxA Gene Plays A More Major Role Than frxA Gene Mutation in High‐level Metronidazole Resistance of Helicobacter pylori in Taiwan
Authors: Yang Yao‐Jong , Wu Jiunn‐Jong , Sheu Bor‐Shyang , Kao Ai‐Wen , Huang Ay‐Huey 
Published: September 2004

ABSTRACTBackground.  Metronidazole‐resistant H. pylori associating with mutations of rdxA or frxA is still a debated topic. This study investigates whether rdxA and frxA mutations of H. pylori accounted for the high MIC value (≥ 64 µg/ml) of metronidazole (Mtz).Material and Methods.  From 126 clinical H. pylori isolates, we examined 14 Mtz‐sensitive, 18 Mtz‐resistant H. pylori, and eight pairs of Mtz‐sensitive and Mtz‐resistant colonies simultaneously present within a single gastric biopsy. The paired strains from one single biopsy were proven identical by PCR‐RFLP. MICs of Mtz were checked by the E‐test and agar dilution method. The mutations of rdxA and frxA sequencing were matched with the Mtz‐susceptible ATCC 26695 and J99.Results.  There were 89% (16/18) of Mtz‐resistant isolates with mutation of RdxA. Half of the 14 Mtz‐sensitive strains, all without mutation of RdxA, still contained truncation of FrxA. Within the paired isolates from a single biopsy, rdxA mutation (86%) was more common than frxA mutation (43%) in those isolates with high‐level Mtz‐resistant H. pylori. RdxA truncation was more prevalent in Mtz‐resistant strains with high MICs than in those with low to moderate MICs (75% vs. 20%, p = .01, OR: 12, 95% CI: 1.8–81.7).Conclusion.  Mutations in the rdxA gene rather than the frxA gene generally determine a high MIC level of Mtz‐resistant H. pylori in Taiwan.
Temporal changes in fishing motivation among fishing club anglers in the United States
Authors: Schramm H. L. , Gerard P. D. 
Published: September 2004

AbstractResponses from freshwater anglers (n = 4287) to a nationwide survey of the US fishing club members were used to assess differences in the importance of 16 fishing motivation items between 1987 and 1997, dates that preceded and followed a period of substantial decline in recreational fishing participation in the US. Comparison of respondents’ motivations for fishing in 1997 and 10 years earlier indicated consistency in the paramount importance of being outdoors, relaxation and the experience of the catch. However, the importance of family recreation and being with friends in 1987 were replaced by escape items in 1997. Anglers with fewer dependents and living in areas with higher population density were more likely to decrease the importance of family recreation. Younger anglers were more likely to decrease the importance of being with friends. Anglers who had higher household income, fished more and had higher fishing expenditures were more likely to decrease the importance of obtaining fish to eat. The results of this study suggest that managers should be less concerned about angler opposition to liberal regulations that allow anglers to harvest fish, and that heightened efforts to recruit and retain recreational anglers, which presently focus on family recreation, should be broadened to include outdoor experience, relaxation and escape aspects of fishing.
Discards from the commercial gillnet fishery for dusky flathead, Platycephalus fuscus, in New South Wales, Australia: spatial variability and initial effects of change in minimum legal length of target species
Authors: Gray C. A. , Johnson D. D. , Young D. J. , Broadhurst M. K. 
Published: September 2004

AbstractA scientific observer programme was used to quantify the composition and magnitude of discards in the gillnet fishery for dusky flathead, Platycephalus fuscus (Cuvier), in three barrier estuaries in New South Wales, Australia, during the 2001 fishing season. Regulations only permit the retention of legal‐sized dusky flathead and legal‐sized blue swimmer crab, Portunus pelagicus L., and mud crab, Scylla serrata (Forskål); all other organisms were discarded. Sampling was stratified into two time periods; before and after 1 July 2001 which coincided with the increase in the minimum legal length (MLL) of dusky flathead from 33 to 36 cm total length (TL). Eighty one catches were sampled, yielding 38 finfish species and two portunid crab species. Legal‐sized dusky flathead were the most abundant organism captured, accounting for 23–47% by number and 34–54% by weight of the mean observed catch depending on the estuary and survey period, with a mean catch of 25–59 flathead weighing 13–25 kg per fishing‐night. Species composition and relative abundance of catches differed among estuaries, but not between sampling periods. Predominant bycatch species included legal and undersize blue swimmer crab, sea mullet, Mugil cephalus L., luderick, Girella tricuspidata (Quoy & Gaimard), bream, Acanthopagrus australis (Günther) and yellowfin leatherjacket, Meuschenia trachylepis (Günther). These five species accounted for 82% of total bycatch by number and 71% by weight, pooled across the three estuaries. More crabs were retained than discarded, with retained legal‐size crabs (byproduct) accounting for 16% of total bycatch by number and 13% by weight, with an average of 5–22 crabs weighing 1–6 kg being caught per fishing‐night, depending on the estuary. Overall, 7% of dusky flathead captured (number) were below the MLL of 36 cm and discarded, suggesting the nets as currently configured may be relatively selective in catching legal‐size flathead. However, 41% of dusky flathead were <40 cm TL, indicating that if the MLL for this species is increased to this length as proposed, new nets must be introduced into the fishery. The findings are discussed in terms of making the flathead fishery more sustainable, including alternative management strategies for the fishery.
Fish assemblages of perennial floodplain ponds of the Sacramento River, California (USA), with implications for the conservation of native fishes
Authors: Feyrer F. , Sommer T. R. , Zeug S. C. , O'Leary G. , Harrell W. 
Published: September 2004

AbstractTo assess the likelihood of enhancing native fish populations by means of floodplain restoration projects, habitat characteristics and fish assemblages of seven perennial floodplain ponds in Yolo Bypass, the primary floodplain of the Sacramento River, California (USA), were examined during summer 2001. Although all ponds were eutrophic, based upon high chlorophyll a or dissolved nutrient concentrations, relatively large shallow ponds generally exhibited higher specific conductivity and dissolved phosphorus concentrations than small deep ponds, which exhibited greater water transparency and total dissolved nitrogen concentrations. Using multiple gear types, 13 688 fishes comprising 23 species were collected. All ponds were dominated by alien fishes; only three native species contributing <1% of the total number of individuals and <3% of overall biomass were captured. Fish assemblage structure varied among ponds, notably between engineered vs. natural ponds, and was related to specific conductance, total dissolved solids and water transparency.
Environmental influences on largemouth bass Micropterus salmoides populations in shallow Nebraska lakes
Authors: Paukert C. P. , Willis D. W. 
Published: September 2004

AbstractThe influence of environmental variables on largemouth bass Micropterus salmoides (Lacépède) populations in 22 shallow (mean depth 1.0–2.9 m) Nebraska lakes was evaluated. Largemouth bass exhibited density‐dependent size structure and growth, but not condition. Total annual mortality averaged only 30%. Deeper lakes contained low density largemouth bass populations with a high proportion of fish >380 mm, whereas larger lakes with little submerged vegetation had faster growth. The proportion of largemouth bass >380 mm and relative abundance tended to increase with emergent vegetation coverage. More stable recruitment was evident in shallower lakes with increased emergent vegetation coverage. Strong year classes were associated with cooler September air temperatures. Largemouth bass populations exhibited density‐dependent effects in lakes up to 332 ha. Lake depth, emergent vegetation and autumn air temperatures may influence largemouth bass populations more than previously suggested.
Effects of hot dry summers on the loss of Atlantic salmon, Salmo salar, from estuaries in South West England
Authors: Solomon D. J. , Sambrook H. T. 
Published: September 2004

AbstractSalmon, Salmo salar L., were radio tagged in four estuaries in South West England. At medium to high summer flows, most salmon entering the river did so within 10 days of tagging. Lower flows were associated with an increased tendency for fish to remain in tidal water for a protracted period, and for those delayed fish to fail to enter the river. The delay was correlated with low freshwater flow, but it was concluded that high water temperature, and in some situations low dissolved oxygen, were likely to be the major influences. The causes of failure to enter the river by the delayed fish include lethally low levels of oxygen in some situations, but a major factor may be missed physiological opportunity. Implications in terms of water resource management, fisheries management and climate change are discussed.
Elevated CO2effects on decomposition processes in a grazed grassland
Authors: Allard Vincent , Newton Paul C. D. , Lieffering Mark , Soussana Jean‐Francois , Grieu Phillipe , Matthew Cory 
Published: September 2004

AbstractThe effects of elevated atmospheric CO2(475 μL L−1) onin situdecomposition of plant litter and animal faecal material were studied over 2 years in a free air CO2enrichment (FACE) facility. The pasture was grazed by sheep and contained a mixture of C3and C4grasses, legumes and forbs. There was no effect of elevated CO2on decomposition within plant species but marked differences between species with faster decomposition in dicots; a group that increased in abundance at elevated CO2. Decomposition of mixed herbage root material occurred at a similar rate to that of leaf litter suggesting that any CO2‐induced increase in carbon allocation to roots would not reduce rates of decomposition. Sheep faeces resulting from a ‘high‐CO2diet’ decomposed significantly slower during summer but not during winter. The overall outcome of these experiments were explored using scenarios that took account of changes in botanical composition, allocation to roots and the presence of herbivores. In the absence of herbivores, elevated CO2led to a 15% increase in the rate of mass loss and an 18% increase in the rate of nitrogen (N) release. In the presence of herbivores, these effects were partially removed (11% increase in rate of mass loss and 9% decrease in N release rate) because of the recycling occurring through the animals in the form of faeces.
The effects of elevated CO2and temperature on the resistance of winter‐dormant birch seedlings (Betula pendula) to hares and voles
Authors: Kuokkanen K. , Niemelä P. , Matala J. , Julkunen‐Tiitto R. , Heinonen J. , Rousi M. , Henttonen H. , Tahvanainen J. , Kellomäki S. 
Published: September 2004

AbstractThe effects of elevated CO2and temperature on the resource allocation pattern and resistance against mammalian herbivores of silver birch (Betula pendulaRoth) were studied. Birch seedlings were grown through two growing seasons in closed‐top chambers exposed to four different treatments: ambient CO2and temperature, elevated atmospheric CO2(700 ppm) and ambient temperature, elevated temperature (+3°C above ambient) and ambient CO2, and a combination of elevated CO2and temperature. After winter hardening of the seedlings, the growth of the seedlings was measured and the concentration of secondary compounds such as phenolics and papyriferic acid determined. The top parts of the stem were fed to hares, and the basal parts of the same stems were offered to voles.Elevated CO2increased the height and basal diameter of the shoots, shoot biomass and total biomass of the seedlings but did not have any effect on secondary chemistry. Elevated temperature increased the height and shoot biomass, but did not have a significant effect on the total biomass of the seedlings. Elevated temperature decreased the concentration of condensed tannins and their precursor, (+)‐catechin, in the top part of the stems, but only the concentration of (+)‐catechin in the basal part of the stems. There were no significant interactive effects between CO2and temperature on phenolics in the stems, while the concentration of papyriferic acid showed significant interaction in the top part of the stems. This indicates high accumulation of papyriferic acid in ambient CO2under increased temperature. Consequently, elevated temperature increased the resistance of birch against hares, but did not affect the resistance of the basal parts of the same birches to voles. Our results indicate that the predicted climatic change will not necessarily lead to increased browsing damage by the mountain hare and the field vole to silver birch.
Plant species richness and composition of heathland relics in north‐western Belgium: evidence for a rescue‐effect?
Authors: Piessens Katrien , Honnay Olivier , Nackaerts Kris , Hermy Martin 
Published: September 2004

AbstractAim  To study the effects of the degree of fragmentation of heathland patches on their species richness and species composition, and to infer the ecological mechanisms behind the observed patterns.Location  The heathland patches of the north‐western part of Flanders, Belgium. During the last 200 years, the heathland area in this study area has been reduced from c. 10,000 to c. 40 ha, yielding c. 150 small and highly isolated relic fragments.Methods  Different isolation measures were calculated for each of the 153 inventoried heathland patches. The influence of isolation, area and habitat diversity on species richness was investigated using correlation techniques. Community composition of the patches was tested for nestedness, and the mechanisms potentially underlying this pattern were determined.Results and main conclusions  Both the analyses at the species richness and community composition level yielded evidence for a positive species–area relation. This relation was not caused by higher habitat heterogeneity in larger patches. Patch isolation, measured in different ways, however seemed much more important in explaining species richness and community composition than fragment area. Our results indicate that area effects are overcompensated by the rescue‐effect: if a patch is close to other patches, species can disperse between them and prevent the species from going extinct. Species having a short living seed bank were also more sensitive to isolation than species with a long living seed bank, indicating that the latter most probably depend on the seed bank to survive periods when environmental conditions are harsh. Analogously to the spatial rescue‐effect, the existence of a persistent seed bank may lead to a sort of temporal rescue‐effect, where the extinction of a plant species is prevented through survival in the seed bank of a patch.
Modelling pollen sedimentation in Danish lakes at c.ad 1800: an attempt to validate the POLLSCAPE model
Authors: Nielsen Anne Birgitte 
Published: September 2004

AbstractAims  To validate the POLLSCAPE simulation model of pollen dispersal and deposition, and evaluate the effect of factors such as pollen productivity, wind speed and regional plant abundance, using a data set of ad 1800 pollen assemblages and historical land cover data.Location  Denmark.Methods  ad 1800 land cover from historical maps is digitized for 2000 m radii around 30 Danish lakes (3.5–33 ha). The simulation model POLLSCAPE is used to predict sedimentary pollen assemblages in the lakes from the plant abundance data inferred from these maps, with different model parameter settings for wind speed, pollen productivity, regional pollen loading, etc. The model predictions are compared with observed ad 1800 pollen assemblages from the lake sediment records. Furthermore, pollen productivity is estimated from the ad 1800 pollen and vegetation data using the Extended R‐value model.Results  Generally the model reproduces the patterns in the observed pollen assemblages, and for most pollen types there are significant correlations between observed and predicted pollen proportions. The pollen proportions predicted by the POLLSCAPE model are sensitive to the pollen productivity estimates used, the regional background pollen loading and average wind speed. There is a difference in background pollen loading between eastern and western Denmark, especially of Calluna pollen. The fit between predicted and observed pollen assemblages is best at wind speeds around 2.5 m s−1, and decreases rapidly at lower wind speeds. The pollen productivity estimates from the ad 1800 data set are comparable with estimates from moss polsters in modern analogues of traditional cultural landscapes in Sweden and Norway.Main conclusions  The POLLSCAPE model reproduces the patterns in the observed pollen assemblages from the lakes well, considering the uncertainty in the historical plant abundance data. This study indicates that the simulation model can be a useful tool for investigating relationships between vegetation and pollen composition, but also that the simulated pollen proportions are sensitive to the pollen productivity estimates, the regional background and to wind speed.
Validation of a clinical guideline on prevention of venous thromboembolism in medical inpatients: a before‐and‐after study with systematic ultrasound examination
Authors: Labarere J. , Bosson J.‐L. , Brion J.‐P. , Fabre M. , Imbert B. , Carpentier P. , Pernod G. 
Published: September 2004

Abstract.Background.  Clinical practice guidelines on prevention of venous thromboembolism in medical inpatients have been implemented in various settings, although few studies have assessed their impact on venous thromboembolism events.Objective.  To determine whether the implementation of a locally developed guideline is followed by changes in the rate of deep vein thrombosis.Design.  A before‐and‐after study consisting in two ‘1‐day’ cross‐sectional studies.Setting.  Thirteen adult medical wards in a teaching hospital in France.Subjects.  All the patients hospitalized on the day of the cross‐sectional study.Intervention.  A clinical guideline integrating scientific evidence and data on target medical providers’ practices was developed by a local expert panel and implemented through a multifaceted intervention.Measurements.  Prevalence of deep vein thrombosis detected by systematic ultrasound examination.Results.  The study included 338 patients in the preintervention sample and 340 in the postintervention sample. The prevalence of deep vein thrombosis decreased from 9.5% (95% CI, 6.6–13.1) in the preintervention sample to 3.2% (95% CI, 1.6–5.7) in the postintervention sample (P < 0.01). The decrease in the rate of thrombosis involved all deep veins of the lower limbs and remained significant after adjustment for risk factors (adjusted odds ratio = 0.47, 95% CI, 0.32–0.70). No additional cases of pulmonary embolism or deep vein thrombosis were reported either on the day of the study or in the following 2 days.Conclusions.  Active implementation of a clinical practice guideline directed at medical providers (doctors, nurses and physical therapists) can be followed by a significant decrease in prevalence of deep vein thrombosis.