bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparing United States versus International Medical School Graduate Physicians Who Serve African‐ American and White Elderly
Authors: Howard Daniel L. , Bunch Carol D. , Mundia Wilberforce O. , Konrad Thomas R. , Edwards Lloyd J. , Ahinee Amamoo M. , Jallah Yhenneko 
Published: June 2006

Objective.To examine the relationship that international medical school graduates (IMGs) in comparison with United States medical school graduates (USMGs) have on health care‐seeking behavior and satisfaction with medical care among African‐American and white elderly.Data Sources.Secondary data analysis of the 1986–1998 Piedmont Health Survey of the Elderly, Established Populations for the Epidemiological Study of the Elderly, a racially oversampled urban and rural cohort of elders in five North Carolina counties.Study Design.Primary focus of analyses examined the impact of the combination of elder race and physician graduate status across time using a linear model for repeated measures analyses and χ2tests. Separate analyses using generalized estimating equations were conducted for each measure of elder characteristic and health behavior. The analytic cohort included 341 physicians and 3,250 elders (65 years old and older) in 1986; by 1998, 211 physicians and 1,222 elders.Data Collection/Extraction Methods.Trained personnel collected baseline measures on 4,162 elders (about 80 percent responses) through 90‐minute in‐home interviews.Principal Findings.Over time, IMGs treated more African‐American elders, and those who had less education, lower incomes, less insurance, were in poorer health, and who lived in rural areas. White elders with IMGs delayed care more than those with USMGs. Both races indicated being unsure about where to go for medical care. White elders with IMGs were less satisfied than those with USMGs. Both races had perceptions of IMGs that relate to issues of communication, cultural competency, ageism, and unnecessary expenses.Conclusion.IMGs do provide necessary and needed access to medical care for underserved African Americans and rural populations. However, it is unclear whether concerns regarding cultural competency, communication and the quality of care undermine the contribution IMGs make to these populations.
Preparing and Presenting Effective Research Posters
Authors: Miller Jane E. 
Published: June 2006

Objectives. Posters are a common way to present results of a statistical analysis, program evaluation, or other project at professional conferences. Often, researchers fail to recognize the unique nature of the format, which is a hybrid of a published paper and an oral presentation. This methods note demonstrates how to design research posters to convey study objectives, methods, findings, and implications effectively to varied professional audiences.Methods. A review of existing literature on research communication and poster design is used to identify and demonstrate important considerations for poster content and layout. Guidelines on how to write about statistical methods, results, and statistical significance are illustrated with samples of ineffective writing annotated to point out weaknesses, accompanied by concrete examples and explanations of improved presentation. A comparison of the content and format of papers, speeches, and posters is also provided.Findings. Each component of a research poster about a quantitative analysis should be adapted to the audience and format, with complex statistical results translated into simplified charts, tables, and bulleted text to convey findings as part of a clear, focused story line.Conclusions. Effective research posters should be designed around two or three key findings with accompanying handouts and narrative description to supply additional technical detail and encourage dialog with poster viewers.
The Association of Natural, Social and Economic Factors with Bird Species Richness in Rural England
Authors: Huby M. , Cinderby S. , Crowe A. M. , Gillings S. , McClean C. J. , Moran D. , Owen A. , White P. C. L. 
Published: June 2006

AbstractAt a global level, increasing emphasis on sustainable development highlights the importance of maintaining and enhancing biodiversity. Within the European Union, agricultural reforms will have a considerable influence on the links between biodiversity, agriculture and rural communities over the next 10–20 years. An understanding of the associations between biodiversity and the rural economy is important for the development of policies to promote environmentally sustainable economic and social well‐being. However, investigations of this type are frequently hindered by the different ways in which data in the natural and social sciences are collected. In this paper, we develop an innovative approach to combine data using a common spatial unit. We illustrate the application of this approach by examining associations between bird species richness, environmental and socio‐economic variables. Our results show how the statistical relationship between biodiversity and environmental factors is strengthened and contextualised by prevailing socio‐economic conditions. This example highlights the additional insights that can be gained from such an integrative approach, especially in terms of the questions it raises about the inter‐relationships between the social, physical and ecological dynamics of rural environments.
Bat Pollination Breakdown in the Caribbean Columnar Cactus Pilosocereus royenii1
Authors: Rivera‐Marchand Bert , Ackerman James D. 
Published: June 2006

ABSTRACTGeneralized pollination systems may be advantageous on island systems or regions of substantial disturbance. We examined whether or not specialization breakdown has occurred in a presumably bat‐pollinated columnar cactus, Pilosocereus royenii, on Puerto Rico, an island subjected to periodic hurricanes. The flowers show characteristics related to bat pollination including nocturnal anthesis, morphology, and amount and quality of nectar reward. The cactus produces flowers whose styles are temporally and mechanically separated from its anthers and do not self‐pollinate. Hand manipulations indicated that it is partially self‐incompatible or suffers some inbreeding depression. In 217 h of observations conducted biweekly over the course of 1 yr, P. royenii received visits from bats, moths, bees, and birds, but the only effective pollinator was the carpenter bee, Xylocopa mordax. Only four bat visits were recorded, all prior to stigma receptiveness. Floral morphology of P. royenii was significantly more variable than that of other bat‐pollinated species of the genus. We propose that infrequent bat visits are a consequence of a population crash and that floral variability is due to either relaxed selection for bat pollination or a transitional stage from bat pollination to bee pollination.
Nutritional Correlates of Population Density Across Habitats and Logging Intensities in Redtail Monkeys (Cercopithecus ascanius)1
Authors: Rode Karyn D. , Chapman Colin A. , McDowell Lee R. , Stickler Claudia 
Published: June 2006

ABSTRACTFood resources are arguably the most common limiting factor for most species, yet little is known about how food quantity and quality interact to determine the size and distribution of wildlife populations. Frugivores may be limited by food quality since fruits, unlike leaves, are typically low in protein and minerals. Understanding the factors influencing frugivore population dynamics is particularly important due to rapid habitat loss and the need to construct informed management plans. Therefore, this study used redtail monkeys in Kibale National Park, Uganda as a model frugivore to (1) compare nutrient intake, reproduction, and habitat use patterns for three redtail groups in an unlogged and heavily logged area; and (2) examine relationships between nutrient intake and redtail population densities across five habitats. Feeding time and intake of crude protein, lipids, and minerals were higher in diets consumed by groups in unlogged areas than heavily logged areas. Intake of both copper and sodium intake was below NRC requirement levels suggested for macaques. Food availability in the unlogged areas was 3.5 times higher than the heavily logged area. Across five study sites, absorbable copper and the ratio of copper to caloric intake in redtail diets were significantly related to redtail population density. These results suggest that food quality is an important factor determining frugivore population density in anthropogenically disturbed frugivore habitats. Copper deficiency, which has been associated with population declines of wild herbivores, has the potential to be a key factor limiting densities of frugivores in tropical habitats.
In Vivo Dissection of theHelicobacter pyloriFur Regulatory Circuit by Genome-Wide Location Analysis
Authors: Danielli Alberto , Roncarati Davide , Delany Isabel , Chiarini Valentina , Rappuoli Rino , Scarlato Vincenzo 
Published: June 2006

ABSTRACTIron homeostasis is particularly important in pathogenic bacteria, which need to compete with the host for this essential cofactor. InHelicobacter pylori, a causative agent of several gastric pathologies, iron uptake and storage genes are regulated at the transcriptional level by the ferric uptake regulator Fur. The regulatory circuit of Fur has recently come under focus because of an intimate interlink with a broader regulatory network governing metal homeostasis, acidic response, and virulence. To dissect the Fur regulatory circuit and identify in vivo targets of regulation, we developed a genome-wide location analysis protocol which allowed the identification of 200 genomic loci bound by Fur as well as the investigation of the binding efficiency of the protein to these loci in response to iron. Comparative analysis with transcriptomes of wild-type andfurdeletion mutant strains allowed the distinction between targets associated with Fur regulation and genes indirectly influenced by thefurmutation. The Fur regulon includes 59 genes, 25 of which appear to be positively regulated. A case study conducted by primer extension analysis of two oppositely regulated genes,hpn2andflaB, suggests that negative regulation as well as positive regulation occurs at the transcriptional level. Furthermore, the results revealed the existence of 13 Fur targeted loci within polycistronic operons, which were associated with transcript deregulation in thefurmutant strain. This study provides a systematic insight of Fur regulation at the genome-wide level inH. pyloriand points to regulatory functions extending beyond the classical Fur repression paradigm.
Interactions between
Streptomyces coelicolor
and
Bacillus subtilis
: Role of Surfactants in Raising Aerial Structures
Authors: Straight Paul D. , Willey Joanne M. , Kolter Roberto 
Published: June 2006

ABSTRACT

Using mixed-species cultures, we have undertaken a study of interactions between two common spore-forming soil bacteria,
Bacillus subtilis
and
Streptomyces coelicolor
. Our experiments demonstrate that the development of aerial hyphae and spores by
S. coelicolor
is inhibited by surfactin, a lipopeptide surfactant produced by
B. subtilis
. Current models of aerial development by sporulating bacteria and fungi postulate a role for surfactants in reducing surface tension at air-liquid interfaces, thereby removing the major barrier to aerial growth.
S. coelicolor
produces SapB, an amphipathic peptide that is surface active and required for aerial growth on certain media. Loss of aerial hyphae in developmental mutants can be rescued by addition of purified SapB. While a surfactant from a fungus can substitute for SapB in a mutant that lacks aerial hyphae, not all surfactants have this effect. We show that surfactin is required for formation of aerial structures on the surface of
B. subtilis
colonies. However, in contrast to this positive role, our experiments reveal that surfactin acts antagonistically by arresting
S. coelicolor
aerial development and causing altered expression of developmental genes. Our observations support the idea that surfactants function specifically for a given organism regardless of their shared ability to reduce surface tension. Production of surfactants with antagonistic activity could provide a powerful competitive advantage during surface colonization and in competition for resources.
Coregulation by Phenylacetyl-Coenzyme A-Responsive PaaX Integrates Control of the Upper and Lower Pathways for Catabolism of Styrene by
Pseudomonas
sp. Strain Y2
Authors: del Peso-Santos Teresa , Bartolomé-Martín David , Fernández Cristina , Alonso Sergio , García José Luis , Díaz Eduardo , Shingler Victoria , Perera Julián 
Published: June 2006

ABSTRACT

The

P
styA

promoter of
Pseudomonas
sp. strain Y2 controls expression of the
styABCD
genes, which are required for the conversion of styrene to phenylacetate, which is further catabolized by the products of two
paa
gene clusters. Two PaaX repressor proteins (PaaX1 and PaaX2) regulate transcription of the
paa
gene clusters of this strain. In silico analysis of the

P
styA

promoter region revealed a sequence located just within
styA
that is similar to the reported PaaX binding sites of
Escherichia coli
and the proposed PaaX binding sites of the
paa
genes of
Pseudomonas
species. Here we show that protein extracts from some
Pseudomonas
strains that have
paaX
genes, but not from a
paaX
mutant strain, can bind and retard the migration of a

P
styA

specific probe. Purified maltose-binding protein (MBP)-PaaX1 fusion protein specifically binds the

P
styA

promoter proximal PaaX site, and this binding is eliminated by the addition of phenylacetyl-coenzyme A. The sequence protected by MBP-PaaX1 binding was defined by DNase I footprinting. Moreover, MBP-PaaX1 represses transcription from the

P
styA

promoter in a phenylacetyl-coenzyme A-dependent manner in vitro. Finally, the inactivation of both
paaX
gene copies of
Pseudomonas
sp. strain Y2 leads to a higher level of transcription from the

P
styA

promoter, while heterologous expression of the PaaX1 in
E. coli
greatly decreases transcription from the

P
styA

promoter. These findings reveal a control mechanism that integrates regulation of styrene catabolism by coordinating the expression of the styrene upper catabolic operon to that of the
paa
-encoded central pathway and support a role for PaaX as a major regulatory protein in the phenylacetyl-coenzyme A catabolon through its response to the levels of this central metabolite.
Arginine Homeostasis in J774.1 Macrophages in the Context of
Mycobacterium bovis
BCG Infection
Authors: Talaue Meliza T. , Venketaraman Vishwanath , Hazbón Manzour Hernando , Peteroy-Kelly Marcy , Seth Anjali , Colangeli Roberto , Alland David , Connell Nancy D. 
Published: June 2006

ABSTRACT

The competition for
l
-arginine between the inducible nitric oxide synthase and arginase contributes to the outcome of several parasitic and bacterial infections. The acquisition of
l
-arginine, however, is important not only for the host cells but also for the intracellular pathogen. In this study we observe that strain AS-1, the
Mycobacterium bovis
BCG strain lacking the Rv0522 gene, which encodes an arginine permease, perturbs
l
-arginine metabolism in J774.1 murine macrophages. Infection with AS-1, but not with wild-type BCG, induced
l
-arginine uptake in J774.1 cells. This increase in
l
-arginine uptake was independent of activation with gamma interferon plus lipopolysaccharide and correlated with increased expression of the MCAT1 and MCAT2 cationic amino acid transport genes. AS-1 infection also enhanced arginase activity in resting J774.1 cells. Survival studies revealed that AS-1 survived better than BCG within resting J774.1 cells. Intracellular growth of AS-1 was further enhanced by inhibiting arginase and ornithine decarboxylase activities in J774.1 cells using
l
-norvaline and difluoromethylornithine treatment, respectively. These results suggest that the arginine-related activities of J774.1 macrophages are affected by the arginine transport capacity of the infecting BCG strain. The loss of Rv0522 gene-encoded arginine transport may have induced other cationic amino acid transport systems during intracellular growth of AS-1, allowing better survival within resting macrophages.
Characterization of the StcE Protease Activity of
Escherichia coli
O157:H7
Authors: Grys Thomas E. , Walters Laura L. , Welch Rodney A. 
Published: June 2006

ABSTRACT

The StcE zinc metalloprotease is secreted by enterohemorrhagic
Escherichia coli
(EHEC) O157:H7 and contributes to intimate adherence of this bacterium to host cells, a process essential for mammalian colonization. StcE has also been shown to localize the inflammatory regulator C1 esterase inhibitor (C1-INH) to cell membranes. We tried to more fully characterize StcE activity to better understand its role in EHEC pathogenesis. StcE was active at pH 6.1 to 9.0, in the presence of NaCl concentrations ranging from 0 to 600 mM, and at 4°C to 55°C. Interestingly, antisera against StcE or C1-INH did not eliminate StcE cleavage of C1-INH. Treatment of StcE with the proteases trypsin, chymotrypsin, human neutrophil elastase, and
Pseudomonas aeruginosa
elastase did not eliminate StcE activity against C1-INH. After StcE was kept at 23°C for 65 days, it exhibited full proteolytic activity, and it retained 30% of its original activity after incubation for 8 days at 37°C. Together, these results show the StcE protease is a stable enzyme that is probably active in the environment of the colon. Additionally,
k
cat
/
K
m
data showed that StcE proteolytic activity was 2.5-fold more efficient with the secreted mucin MUC7 than with the complement regulator C1-INH. This evidence supports a model which includes two roles for StcE during infection, in which StcE acts first as a mucinase and then as an anti-inflammatory agent by localizing C1-INH to cell membranes.
A Variation of the Translation Attenuation Model Can Explain the Inducible Regulation of the pBC16 Tetracycline Resistance Gene in
Bacillus subtilis
Authors: Lodato Patricia B. , Rogers Elizabeth J. , Lovett Paul S. 
Published: June 2006

ABSTRACT

Expression of the
tet
resistance gene from plasmid pBC16 is induced by the antibiotic tetracycline, and induction is independent of the native promoter for the gene. The nucleotide sequence at the 5′ end of the
tet
mRNA (the leader region) is predicted to assume a complex secondary structure that sequesters the ribosome binding site for the
tet
gene. A spontaneous, constitutively expressed
tet
gene variant contains a mutation predicted to provide the
tet
gene with a nonsequestered ribosome binding site. Lastly, comparable levels of
tet
mRNA can be demonstrated in tetracycline-induced and uninduced cells. These results are consistent with the idea that the pBC16
tet
gene is regulated by translation attenuation, a model originally proposed to explain the inducible regulation of the
cat
and
erm
genes in gram-positive bacteria. As with inducible
cat
and
erm
genes, the pBC16
tet
gene is preceded by a translated leader open reading frame consisting of a consensus ribosome binding site and an ATG initiation codon, followed by 19 sense codons and a stop codon. Mutations that block translation of
cat
and
erm
leaders prevent gene expression. In contrast, we show that mutations that block translation of the
tet
leader result in constitutive expression. We provide evidence that translation of the
tet
leader peptide coding region blocks
tet
expression by preventing the formation of a secondary-structure complex that would, in the absence of leader translation, expose the
tet
ribosome binding site. Tetracycline is proposed to induce
tet
by blocking or slowing leader translation. The results indicate that
tet
regulation is a variation of the translation attenuation model.
Isolation of a High-Affinity Functional Protein Complex between OmcA and MtrC: Two Outer Membrane Decaheme
c
-Type Cytochromes of
Shewanella oneidensis
MR-1
Authors: Shi Liang , Chen Baowei , Wang Zheming , Elias Dwayne A. , Mayer M. Uljana , Gorby Yuri A. , Ni Shuison , Lower Brian H. , Kennedy David W. , Wunschel David S. , Mottaz Heather M. , Marshall Matthew J. , Hill Eric A. , Beliaev Alexander S. , Zachara John M. , Fredrickson James K. , Squier Thomas C. 
Published: June 2006

ABSTRACT

Shewanella oneidensis
MR-1 is a facultatively anaerobic bacterium capable of using soluble and insoluble forms of manganese [Mn(III/IV)] and iron [Fe(III)] as terminal electron acceptors during anaerobic respiration. To assess the structural association of two outer membrane-associated
c
-type decaheme cytochromes (i.e., OmcA [SO1779] and MtrC [SO1778]) and their ability to reduce soluble Fe(III)-nitrilotriacetic acid (NTA), we expressed these proteins with a C-terminal tag in wild-type
S. oneidensis
and a mutant deficient in these genes (i.e., Δ
omcA mtrC
). Endogenous MtrC copurified with tagged OmcA in wild-type
Shewanella
, suggesting a direct association. To further evaluate their possible interaction, both proteins were purified to near homogeneity following the independent expression of OmcA and MtrC in the Δ
omcA mtrC
mutant. Each purified cytochrome was confirmed to contain 10 hemes and exhibited Fe(III)-NTA reductase activity. To measure binding, MtrC was labeled with the multiuse affinity probe 4′,5′-bis(1,3,2-dithioarsolan-2-yl)fluorescein (1,2-ethanedithiol)
2
, which specifically associates with a tetracysteine motif engineered at the C terminus of MtrC. Upon titration with OmcA, there was a marked increase in fluorescence polarization indicating the formation of a high-affinity protein complex (

K
d

< 500 nM) between MtrC and OmcA whose binding was sensitive to changes in ionic strength. Following association, the OmcA-MtrC complex was observed to have enhanced Fe(III)-NTA reductase specific activity relative to either protein alone, demonstrating that OmcA and MtrC can interact directly with each other to form a stable complex that is consistent with their role in the electron transport pathway of
S. oneidensis
MR-1.
Growth Phase-Dependent Regulation of the Extracytoplasmic Stress Factor, σ
E
, by Guanosine 3′,5′-Bispyrophosphate (ppGpp)
Authors: Costanzo Alessandra , Ades Sarah E. 
Published: June 2006

ABSTRACT

The sigma subunit of procaryotic RNA polymerases is responsible for specific promoter recognition and transcription initiation. In addition to the major sigma factor, σ
70
, in
Escherichia coli
, which directs most of the transcription in the cell, bacteria possess multiple, alternative sigma factors that direct RNA polymerase to distinct sets of promoters in response to environmental signals. By activating an alternative sigma factor, gene expression can be rapidly reprogrammed to meet the needs of the cell as the environment changes. Sigma factors are subject to multiple levels of regulation that control their levels and activities. The alternative sigma factor σ
E
in
Escherichia coli
is induced in response to extracytoplasmic stress. Here we demonstrate that σ
E
can also respond to signals other than extracytoplasmic stress. σ
E
activity increases in a growth phase-dependent manner as a culture enters stationary phase. The signaling pathway that activates σ
E
during entry into stationary phase is dependent upon the alarmone guanosine 3′,5′-bispyrophosphate (ppGpp) and is distinct from the pathway that signals extracytoplasmic stress. ppGpp is the first cytoplasmic factor shown to control σ
E
activity, demonstrating that σ
E
can respond to internal signals as well as signals originating in the cell envelope. ppGpp is a general signal of starvation stress and is also required for activation of the σ
S
and σ
54
alternative sigma factors upon entry into stationary phase, suggesting that this is a key mechanism by which alternative sigma factors can be activated in concert to provide a coordinated response to nutritional stress.