bluuebunny/crossref_metadata_2025_split huggingface dataset:
Species‐specific Response of Photosynthesis to Burning and Nitrogen Fertilization
Authors: Zhang Yanfang , Niu Shuli , Xu Wenhua , Han Yi 
Published: April 2008

Abstract The present study was conducted to examine photosynthetic characteristics of three dominant grass species (Agropyron cristatum, Leymus chinensis, and Cleistogenes squarrosa) and their responses to burning and nitrogen fertilization in a semiarid grassland in northern China. Photosynthetic rate (Pn), stomatal conductance (gs), and water use efficiency (WUE) showed strong temporal variability over the growing season. C. squarrosa showed a significantly higher Pn and WUE than A. cristatum and L. chinensis. Burning stimulated Pn of A. cristatum and L. chinensis by 24–59% (P < 0.05) in the early growing season, but not during other time periods. Light‐saturated photosynthetic rate (Pmax) in A. cristatum and the maximum apparent quantum yield (Φmax) in A. cristatum and L. chinensis were significantly enhanced by burning (16–67%) in both the fertilized and unfertilized plots. The main effect of burning on Pn, Pmax and Φmax was not significant in C. squarrosa. The burning‐induced changes in soil moisture could explain 51% (P = 0.01) of the burning‐induced changes in Pn of the three species. All three species showed positive responses to N fertilization in terms of Pn, Pmax, and Φmax. The stimulation of Pn under N fertilization was mainly observed in the early growing season when the soil extractable N content was significantly higher in the fertilized plots. The N fertilization‐induced changes in soil extractable N content could explain 66% (P = 0.001) of the changes in Pn under N fertilization. The photosynthetic responses of the three species indicate that burning and N fertilization will potentially change the community structure and ecosystem productivity in the semiarid grasslands of northern China.
Spatiotemporal Patterns and Dynamics of Species Richness and Abundance of Woody Plant Functional Groups in a Tropical Forest Landscape of Hainan Island, South China
Authors: Zhang Zhi‐Dong , Zang Run‐Guo , Qi Yao‐Dong 
Published: April 2008

Abstract Tropical forests are among the most species‐diverse ecosystems on Earth. Their structures and ecological functions are complex to understand. Functional group is defined as a group of species that play similar roles in an ecosystem. The functional group approach has been regarded as an effective way of linking the compositions of complex ecosystems with their ecological functions. To understand the variation of functional groups in species‐rich ecosystems after disturbance, the present study investigated the spatial pattern and temporal dynamics of woody plants in a typically fragmented natural forest landscape of Hainan Island in South China. The study area was classified into eight landscape types based on vegetation type, disturbance manner and the time of recovery. The woody plant species were aggregated into seven functional groups based on the growth form, successional status and plant size. The results gained from the present study showed that all functional groups, except for the emergent and canopy tree species, were present in all eight landscape types. Each landscape type had different numbers of dominant functional groups. There are similar species richness and stem abundance structure among functional groups between mid‐successional clear cut lowland rainforest and old growth tropical coniferous forest. This similarity exists in selective logged lowland rainforest and old‐growth lowland rainforest, as well as among landscape types of montane rainforest. The functional groups with the same successional status had similar patterns of species richness and stem abundance ratios among different landscape types. The variation patterns of functional groups along the successional stages in terms of species richness and stem abundance among the tropical lowland rainforest landscape types were more similar to each other than those in the tropical montane rainforest landscape types. This study provides further support for the competition‐colonization tradeoff and successional niche theory as opposed to models of neutrality and ecological equivalence.
Environmental Economic Geography
Authors: Hayter Roger 
Published: April 2008

AbstractThis article advocates evolutionary institutionalism as a conceptual platform to launch a systematic approach to environmental economic geography. Evolutionary institutionalism interprets industrial transitions through the lens of innovative behaviour that is shaped by reciprocal economic and non‐economic processes and periodically restructures economies in the form of new techno‐economic paradigms (TEP). In this approach, environment–economy relations need not be zero‐sum games, as is often assumed. Rather, as a result of innovation and choice, these relations have been recalibrated historically and can be redefined again towards developing a green TEP in which development and sustainability are co‐imperatives. It is argued that the mandate of environmental economic geography is to assess and prescribe how place makes and should make a difference to a green TEP and the article sketches a research agenda to promote this goal. This research agenda focuses on the themes of regions as institutions, remapping resource use and sustainable value chains.
Effectiveness of real‐time virtual sonography‐guided radiofrequency ablation treatment for patients with hepatocellular carcinomas
Authors: Kitada Takatoshi , Murakami Takamichi , Kuzushita Noriyoshi , Minamitani Kaori , Nakajo Kazuya , Osuga Keigo , Miyoshi Eiji , Nakamura Hironobu , Kishino Bunichiro , Tamura Shinji , Hayashi Norio 
Published: April 2008

Aim:  Real‐time virtual sonography (RVS) can synchronize B‐mode ultrasound (US) images with multiplanar reconstruction (MPR)–computed tomography (CT) images on the same screen in real time. The purpose of this study was to evaluate the effectiveness of RVS for radiofrequency ablation therapy (RFA) of hepatocellular carcinomas (HCC) in which it was difficult to identify contours or margins by B‐mode US.Methods:  Sixty‐three consecutive patients with a solitary HCC of less than 3.5 cm in diameter were enrolled in this study. Thirty‐nine patients with HCC clearly detectable by B‐mode US underwent conventional RFA, while the remaining 24 with obscure tumor lesions underwent RVS‐guided RFA. A follow‐up study of RFA treatment was performed every 3 months using enhanced CT imaging of the arterial and portal phase (at least 24 months). The accuracy of needle insertion was confirmed by measuring the gap between the needle insertion line and the center of the tumor from MPR–CT images.Results:  The local recurrence rate of the RVS‐guided RFA group was similar to that of the conventional RFA group (8.3% vs 7.7%), despite the difficulty of detecting tumor lesions in the former group. The mean gap between the needle insertion line and the center of the tumor was 1.6 mm (0–3.2 mm) in eight patients treated with RVS‐guided RFA.Conclusion:  RVS‐guided RFA can be useful for treating HCC that are difficult to detect by B‐mode US.
Effect of genipin on the biliary excretion of cholephilic compounds in rats
Authors: Mikami Masaki , Takikawa Hajime 
Published: April 2008

Aim:  Genipin, a metabolite of geniposide, is reported to stimulate the insertion of multidrug resistance protein 2 (Mrp2) in the bile canalicular membrane, and to cause choleresis by increasing the biliary excretion of glutathione, which has been considered to be a substrate of Mrp2. In the present study, the effect of colchicine on the choleretic effect of genipin was investigated. The effect of genipin on the biliary excretion of the substrates of bile salt export pump and Mrp2 was also studied.Methods:  After bile duct cannulation into rats, genipin was administered at the rate of 0.2 μmol/min/100 g, and the effect of colchicine pretreatment (0.2 mg/100 g) was examined. Metabolites of genipin in the bile were examined by a thin layer chromatography. Taurocholate (TC), sulfobromophthalein (BSP), and pravastatin were infused at the rate of 1.0, 0.2 and 0.3 μmol/min/100 g, respectively, and the effect of genipin co‐administration was examined.Results:  Genipin increased bile flow and the biliary glutathione excretion, and those increases were not inhibited by colchicine. The biliary excretion of genipin glucuronide was less than 10% of the genipin excreted into bile. The biliary excretion of TC, BSP, and pravastatin was unchanged by genipin co‐administration.Conclusion:  It was indicated that colchicine‐sensitive vesicular transport has no role on the genipin‐induced insertion of Mrp2 to the canalicular membrane. Choleresis of genipin is considered to be mainly due to the increased biliary glutathione excretion by genipin, not by the biliary excretion of glucuronide. TC had no effect on the biliary glutathione excretion.
A valine to phenylalanine mutation in the precore region of hepatitis B virus causes intracellular retention and impaired secretion of HBe‐antigen
Authors: Chen Chien Yu , Crowther Carol , Kew Michael C. , Kramvis Anna 
Published: April 2008

Aim:  Hepatitis B virus (HBV) e antigen (HBeAg) is translated from precore mRNA as a precore/core protein, which is post‐translationally modified to give rise to the protein that is secreted into the serum. The G1862T mutation in HBV occurs in the bulge of the encapsidation signal within the pregenomic RNA. When the precore mRNA is translated, this mutation results in a valine to phenylalanine substitution at the −3 position to the signal peptide cleavage site at the amino end of the precursor protein. The aim of this study was to determine whether this mutation could affect HBV replication and/or HBeAg expression.Methods:  Following transfection of Huh 7 cells, HBV replication was followed using real time polymerase reaction (PCR) and expression of HBeAg expression was monitored using confocal microscopy.Results:  HBV replication was reduced when this mutation was introduced into genotype D but not into genotype A replication‐competent constructs. Using mutant HBeAg‐expressing plasmids, we demonstrated a 54% reduction in HBeAg secretion relative to the wild type. Confocal microscopy demonstrated that the mutant HBeAg accumulated in the endoplasmic reticulum, endoplasmic reticulum intermediate compartment and Golgi. These aggregates of mutant protein increased in size following treatment of the cells with a proteasome inhibitor, MG132, and had the hallmark features of aggresomes. They attracted ubiquitin, heat shock proteins and proteasomes and were isolated from the cytosol by the intermediate filaments, vimentin and cytokeratin.Conclusion:  The formation of aggresomes, as a result of the G1862T mutation, may play a contributory role in HBV‐induced liver disease.
Unsteady Heat Transfer Measurements from Transonic Turbine Blades at
Engine Representative Conditions in a Transient Facility
Authors: Allan W. D. , Ainsworth R. , Thorpe S. 
Published: April 2008

Abstract
The unsteady heat transfer measurements about a transonic turbine blade at engine representative Mach and Reynolds numbers are presented. High density, fast-response thin film gauges are employed at the midheight streamline. A description of the novel development of gold gauges together with a brief overview of their calibration and signal processing is presented. Detailed time and phase-averaged measurements have been obtained, providing insight into the role of upstream nozzle guide vane (NGV) wakes and shock features. These heat transfer results compliment recent fast-response aerodynamic results on this and similar transonic profiles, which highlight the dominance of the upstream vane-rotor interaction over convected wake segments, particularly in light of unsteady turbine blade loading. From a heat transfer standpoint, however, while the periodic shock events contributed to abrupt, localized heat transfer enhancements, the influence of NGV wake segments on the boundary layer could not be discounted when duration of unsteadiness was considered.
Fitness Trade-Offs inblaTEMEvolution
Authors: Mroczkowska Joanna E. , Barlow Miriam 
Published: April 2008

ABSTRACTblaTEM-1expression results in penicillin resistance, whereas expression of manyblaTEM-1descendants, called extended-spectrum β-lactamases (ESBLs), results simultaneously in resistance to penicillins and extended-spectrum cephalosporins. Despite the expanded resistance phenotypes conferred by many ESBLs,blaTEM-1is still the most abundantblaTEMallele in many microbial populations. This study examines the fitness effects of the two amino acid substitutions, R164S and E240K, that have occurred repeatedly among ESBLblaTEM-1descendants. Using a single-nucleotide polymorphism-specific real-time quantitative PCR method, we analyzed the fitness of strains expressingblaTEM-1,blaTEM-10, andblaTEM-12. Our results show that bacteria expressing the ancestralblaTEM-1allele have a fitness advantage over those expressing eitherblaTEM-10orblaTEM-12when exposed to ampicillin. This observation, combined with the fact that penicillins are the most prevalent antimicrobials prescribed worldwide, may explain whyblaTEM-1has persisted as the most frequently encounteredblaTEMallele in bacterial populations.
The Human CXC Chemokine Granulocyte Chemotactic Protein 2 (GCP-2)/CXCL6 Possesses Membrane-Disrupting Properties and Is Antibacterial
Authors: Linge Helena M. , Collin Mattias , Nordenfelt Pontus , Mörgelin Matthias , Malmsten Martin , Egesten Arne 
Published: April 2008

ABSTRACTGranulocyte chemotactic protein 2 (GCP-2)/CXCL6 is a CXC chemokine expressed by macrophages and epithelial and mesenchymal cells during inflammation. Through binding and activation of its receptors (CXCR1 and CXCR2), it exerts neutrophil-activating and angiogenic activities. Here we show that GCP-2/CXCL6 itself is antibacterial. Antibacterial activity against gram-positive and gram-negative pathogenic bacteria of relevance to mucosal infections was seen at submicromolar concentrations (minimal bactericidal concentration at which 50% of strains tested were killed, 0.063 ± 0.01 to 0.37 ± 0.03 μM). In killed bacteria, GCP-2/CXCL6 associated with bacterial surfaces, which showed membrane disruption and leakage. A structural prediction indicated the presence of three antiparallel NH2-terminal β-sheets and a short amphipathic COOH-terminal α-helix; the latter feature is typical of antimicrobial peptides. However, when the synthetic derivatives corresponding to the NH2-terminal (50 amino acids) and COOH-terminal (19 amino acids, corresponding to the putative α-helix) regions were compared, higher antibacterial activity was observed for the NH2-terminus-derived peptide, indicating that the holopeptide is necessary for full antibacterial activity. An artificial model of bacterial membranes confirmed these findings. The helical content of GCP-2/CXCL6 in the presence or absence of lipopolysaccharide or negatively charged membranes was studied by circular dichroism. As with many antibacterial peptides, membrane disruption by GCP-2/CXCL6 was dose-dependently reduced in the presence of NaCl, which, we here demonstrate, inhibited the binding of the peptide to the bacterial surface. Compared with CXC chemokines ENA-78/CXCL5 and NAP-2/CXCL7, GCP-2/CXCL6 showed a 90-fold-higher antibacterial activity. Taken together, GCP/CXCL6, in addition to its chemotactic and angiogenic properties, is likely to contribute to direct antibacterial activity during localized infection.
ramR
Mutations Involved in Efflux-Mediated Multidrug Resistance in
Salmonella enterica
Serovar Typhimurium
Authors: Abouzeed Yousef M. , Baucheron Sylvie , Cloeckaert Axel 
Published: April 2008

ABSTRACT

In the sequenced genome of
Salmonella enterica
serovar Typhimurium strain LT2, an open reading frame (STM0580) coding for a putative regulatory protein of the TetR family is found upstream of the
ramA
gene. Overexpression of
ramA
results in increased expression of the AcrAB efflux pump and, consequently, multidrug resistance (MDR) in several bacterial species. The inactivation of the putative regulatory protein gene upstream of
ramA
in a susceptible serovar Typhimurium strain resulted in an MDR phenotype with fourfold increases in the MICs of unrelated antibiotics, such as quinolones/fluoroquinolones, phenicols, and tetracycline. The inactivation of this gene also resulted in a fourfold increase in the expression of
ramA
and a fourfold increase in the expression of the AcrAB efflux pump. These results indicated that the gene encodes a local repressor of
ramA
and was thus named
ramR
. In contrast, the inactivation of
marR
,
marA
,
soxR
, and
soxS
did not affect the susceptibilities of the strain. In quinolone- or fluoroquinolone-resistant strains of serovar Typhimurium overexpressing AcrAB, several point mutations which resulted in amino acid changes or an in-frame shift were identified in
ramR
; in addition, mutations interrupting
ramR
with an IS
1
element were identified in high-level fluoroquinolone-resistant serovar Typhimurium DT204 strains. One serovar Typhimurium DT104 isolate had a 2-nucleotide deletion in the putative RamR binding site found upstream of
ramA
. These mutations were confirmed to play a role in the MDR phenotype by complementing the isolates with an intact
ramR
gene or by inactivating their respective
ramA
gene. No mutations in the
mar
or
sox
region were found in the strains studied. In conclusion, mutations in
ramR
appear to play a major role in the upregulation of RamA and AcrAB and, consequently, in the efflux-mediated MDR phenotype of serovar Typhimurium.
Stronger Activity of Human Immunodeficiency Virus Type 1 Protease Inhibitors against Clinical Isolates of
Plasmodium vivax
than against Those of
P. falciparum
Authors: Lek-Uthai U. , Suwanarusk R. , Ruengweerayut R. , Skinner-Adams T. S. , Nosten F. , Gardiner D. L. , Boonma P. , Piera K. A. , Andrews K. T. , MacHunter B. , McCarthy J. S. , Anstey N. M. , Price R. N. , Russell B. 
Published: April 2008

ABSTRACT

Recent studies using laboratory clones have demonstrated that several antiretroviral protease inhibitors (PIs) inhibit the growth of
Plasmodium falciparum
at concentrations that may be of clinical significance, especially during human immunodeficiency virus type 1 (HIV-1) and malaria coinfection. Using clinical isolates, we now demonstrate the in vitro effectiveness of two HIV-1 aspartic PIs, saquinavir (SQV) and ritonavir (RTV), against
P. vivax
(
n
= 30) and
P. falciparum
(
n
= 20) from populations subjected to high levels of mefloquine and artesunate pressure on the Thailand-Myanmar border. The median 50% inhibitory concentration values of
P. vivax
to RTV and SQV were 2,233 nM (range, 732 to 7,738 nM) and 4,230 nM (range, 1,326 to 8,452 nM), respectively, both within the therapeutic concentration range commonly found for patients treated with these PIs. RTV was fourfold more effective at inhibiting
P. vivax
than it was at inhibiting
P. falciparum
, compared to a twofold difference in SQV sensitivity. An increased
P. falciparum mdr1
copy number was present in 33% (3/9) of isolates and that of
P. vivax mdr1
was present in 9% of isolates (2/22), but neither was associated with PI sensitivity. The inter-
Plasmodium
sp. variations in PI sensitivity indicate key differences between
P. vivax
and
P. falciparum
. PI-containing antiretroviral regimens may demonstrate prophylactic activity against both vivax and falciparum malaria in HIV-infected patients who reside in areas where multidrug-resistant
P. vivax
or
P. falciparum
is found.
Low β-Lactamase-Negative Ampicillin-Resistant
Haemophilus influenzae
Strains Are Best Detected by Testing Amoxicillin Susceptibility by the Broth Microdilution Method
Authors: García-Cobos Silvia , Campos José , Román Federico , Carrera Cristina , Pérez-Vázquez María , Aracil Belén , Oteo Jesús 
Published: April 2008

ABSTRACT

Ampicillin resistance in
Haemophilus influenzae
due to alterations in penicillin-binding proteins (β-lactamase negative ampicillin resistant [BLNAR]) is acquiring increasing clinical and epidemiological importance. BLNAR strains with low ampicillin MICs (0.5 to 4 μg/ml) represent the majority of this population in Europe and the United States, but separating them from susceptible isolates is challenging. To investigate the best method to identify low-BLNAR strains, we studied the antibiotic susceptibilities of 94 clinical isolates of
H. influenzae
by microdilution, Etest, and disk diffusion: 25 had no resistance mechanisms (gBLNAS), 34 had mutations in the
ftsI
gene only (gBLNAR), 20 were β-lactamase producers only (gBLPAR), and 15 showed β-lactamase production and mutations in the
ftsI
gene (gBLPACR). By current CLSI breakpoints, most gBLNAR isolates were ampicillin susceptible by microdilution (76.5%) or by Etest (88.2%). Most gBLNAR strains (79.4%) were nonsusceptible to amoxicillin (the most widely used community antibiotic in the United States and Europe) when tested by microdilution. By Etest, 15% of β-lactamase-positive isolates were nonresistant to ampicillin or amoxicillin. The poorest agreement between Etest and microdilution results was for the gBLPAR isolates (25% for ampicillin, 15% for amoxicillin, and 10% for cefaclor). Low-strength disks of ampicillin and amoxicillin-clavulanic acid poorly identified low-BLNAR isolates and are not recommended as a screening method. We suggest new amoxicillin breakpoints for BLNAR isolates as follows: susceptible, MIC ≤ 0.5 μg/ml (no resistance mechanisms; pharmacokinetic/pharmacodynamic [PK/PD] data favorable); intermediate, MICs = 1 to 2 μg/ml (resistance mechanisms present but PK/PD data favorable), and resistant, MICs ≥ 4 μg/ml (resistance mechanisms present and PK/PD data unfavorable).
Species Distribution and In Vitro Antifungal Susceptibility Patterns of 75 Clinical Isolates of
Fusarium
spp. from Northern Italy
Authors: Tortorano Anna Maria , Prigitano Anna , Dho Giovanna , Esposto Maria Carmela , Gianni Claudia , Grancini Anna , Ossi Cristina , Viviani Maria Anna 
Published: April 2008

ABSTRACT

Fusarium
isolates from 75 Italian patients were identified by molecular methods, and their susceptibilities to antifungals were tested in vitro.
Fusarium verticillioides
was the species most frequently isolated from deep-seated infections, and
F. solani
was the species most frequently isolated from superficial infections.
F. solani
isolates showed high azole MICs, while
F. verticillioides
isolates showed low posaconazole MICs.
Connection between Trimethoprim-Sulfamethoxazole Use and Resistance in
Streptococcus pneumoniae, Haemophilus influenzae
, and
Moraxella catarrhalis
Authors: Kärpänoja Pauliina , Nyberg Solja T. , Bergman Miika , Voipio Tinna , Paakkari Pirkko , Huovinen Pentti , Sarkkinen Hannu 
Published: April 2008

ABSTRACT

The association between trimethoprim-sulfamethoxazole use and resistance among the major respiratory tract pathogens was investigated by comparing regional consumption of the drug to regional resistance in the following year in 21 central hospital districts in Finland. A total of 23,530
Streptococcus pneumoniae
isolates, 28,320
Haemophilus influenzae
isolates, and 14,138
Moraxella catarrhalis
isolates were tested for trimethoprim-sulfamethoxazole susceptibility during the study period (1998-2004). Among the
S. pneumoniae
isolates, a statistically significant connection was found between regional consumption and resistance. No statistically significant connection was found between regional trimethoprim-sulfamethoxazole use and resistance among
H. influenzae
and
M. catarrhalis
isolates. According to our results, it seems that only in pneumococci can the development of trimethoprim-sulfamethoxazole resistance be influenced by restricting its use. However, trimethoprim-sulfamethoxazole remains an important antimicrobial agent because of its reasonable price. Hence, resistance to trimethoprim-sulfamethoxazole among these pathogens needs continuous monitoring.