bluuebunny/crossref_metadata_2025_split huggingface dataset:
Demographic viability of populations of Silene regia in midwestern prairies: relationships with fire management, genetic variation, geographic location, population size and isolation
Authors: Menges Eric S. , Dolan Rebecca W. 
Published: May 2003

1  We studied the demographic viability of populations of a long‐lived iteroparous prairie perennial, Silene regia, in relation to management regimes, population sizes, geographical region (Ohio and Indiana vs. Missouri and Arkansas), degree of isolation and amount of genetic variation. Demographic data were collected from 16 populations for up to 7 years. 2  This species has high survivorship, slow growth, frequent flowering and episodic seedling recruitment. Matrix projection methods were used to summarize population performance with and without recruitment. Median finite rates of increase by population varied from 0.57 to 1.82 and from 0.44 to 0.99, respectively. 3  Populations with the highest rates of increase had been burned. Six of eight populations, for which stochastic modelling predicted persistence for 1000 years, included fire in their management. None of the five populations with predicted 100‐year extinction probabilities of 100% was managed for conservation or burned. An intermediate group of three populations with at least 10% probability of extinction between 100 and 1000 years was not managed, but was none the less kept open by mowing and herbicide application. 4  Analysis of composite elasticities showed that growth and fecundity terms were higher for growing (vs. declining) populations and that growth elasticity was higher in burned than unburned populations. Lack of burning shifts the elasticity spectrum from that typical of open habitat herbs (higher growth and fecundity elasticities) to values usually found for closed habitat herbs (higher survival elasticities). 5  In multivariate analyses predicting finite rates of increase (with and without recruitment), fire management and region were the strongest predictors, followed by genetic variation, population size, isolation and interactions of population size and fire, and region and fire. Populations with the highest rates of increase were burned, eastern, more genetically diverse, larger and less isolated. Discrimination of populations with different extinction risks (three classes) was related mainly to fire, genetic variation and region. 6  Most of these conclusions support conservation biology predictions that population viability will be highest in larger, less‐isolated, more genetically diverse populations. However, management and geographic trends have overriding roles affecting demographic viability. Habitat fragmentation and genetic depletion have the potential to threaten residual prairie populations of S. regia, but lack of fire management appears to be the primary short‐term threat.
Interactive effects of elevation and burial with wrack on plant community structure in some Rhode Island salt marshes
Authors: Brewer J. Stephen , Levine Jonathan M. , Bertness Mark D. 
Published: May 2003

1  The effects of disturbances and elevation on marsh plant communities were examined using experimental disturbances along an elevation gradient in marshes with different disturbance histories. In addition, differences in species composition among five marshes were determined at elevations at which the greatest concentration of burial by wrack occurred. 2  Experimental wrack burial generally caused significant mortality of the high‐marsh competitive dominants, Juncus gerardi and Spartina patens, and strongly increased the abundance of the fugitive perennial, Distichlis spicata. 3  The effects of experimental wrack burial interacted strongly with abiotic factors associated with elevation to influence the distributions of both competitive dominants and annual fugitive plants. 4  Frequent wrack burial in a marsh appears to lead to a persistent assemblage of plants dominated by competitively subordinate fugitives. This assemblage of fugitives tends to occur at intermediate elevations within the marsh, where wrack gets stranded for long periods of time and where the resistance of Juncus gerardi to wrack burial is lowest. 5  We suggest that wrack‐burial disturbances interact strongly with marsh elevation to influence the zonation of plants in New England salt marshes, and discuss some implications of our results.
Flat colonic adenomas in Malaysia: Fact or fancy?
Authors: RAJENDRA SHANMUGARAJAH , KUTTY KANNAN , KARIM NORAIN 
Published: May 2003

AbstractBackground: Some two‐thirds of colorectal carcinomas arise from adenomatous polyps, and as such, screening by colonoscopy and polyp removal should significantly reduce colorectal cancer. This has not been the case, as evidenced by recent studies, which revealed that endoscopy failed to prevent up to 50% of all subsequent carcinomas. Flat or depressed adenomas, frequently reported from Japan but rarely elsewhere, might explain the ‘missed carcinomas.’ Detection of flat adenomas has not been previously reported from Malaysia.Methods: In the present prospective study, 426 consecutive patients underwent colonoscopic examination between March 1997 and January 2000, for a variety of bowel symptoms. The examinations were performed by an experienced endoscopist using a standard colonoscope and methylene blue dye spraying technique. Macroscopically, flat adenomas were defined using the criteria proposed by Sawada.Results: Twenty‐nine adenomas were identified in 12 patients, of which 15 were polypoid and 14 were flat, with no depressed lesions. Eight polypoidal lesions and all the flat adenomas contained mild or moderate areas of epithelial dysplasia. Seven severely dysplastic polyps were identified. One Duke's A polypoidal cancer and two advanced carcinomas were also found. All the severely dysplastic lesions and Duke's A carcinomas were found in polyps greater than 10 mm in mean size. The flat adenomas were all less than 5 mm in size.Conclusions: A significant proportion of colonic adenomas in Malaysian patients appear as small flat lesions, which could easily be missed during endoscopy. Increased recognition and treatment of flat adenomas among colonoscopists is warranted.
Epidemiology of childhood nocturnal enuresis in Malaysia
Authors: Kanaheswari Y 
Published: May 2003

Objectives:  To estimate the prevalence of nocturnal enuresis in primary school children in Malaysia and to determine the factors associated with primary nocturnal enuresis.Methods:  This was a cross‐sectional survey. A total of 3371 self‐administered questionnaires were distributed to parents of children aged 7, 9 and 12 years attending four primary schools in the city. The ICD‐10 definition of enuresis was used.Results:  From an overall response rate of 73.8%, nocturnal enuresis was reported in 200 children (8%), primary nocturnal enuresis in 156 children (6.2%) and secondary nocturnal enuresis in 44 children (1.8%). Fifty‐three percent of those with primary enuresis had a positive family history, and 54% had two or more wet nights per week. Eighty‐seven percent had not sought any form of treatment despite 74% admitting to being embarrassed. Using logistic regression analysis, only three factors were significant predictors of primary nocturnal enuresis. These were: (i) younger age (P < 0.001); (ii) male sex (P < 0.033); and (iii) Indian ethnic group (P < 0.044) compared to Chinese.Conclusion:  The prevalence of nocturnal enuresis in urban‐dwelling Malaysian children is similar to that reported from Korea and Taiwan but appears to be lower than that reported from developed countries. Predictive factors associated with primary nocturnal enuresis included lower age group, male sex and Indian ethnicity.
Acute administration of conjugated equine oestrogen does not improve exercise‐induced myocardial ischaemia in men with coronary artery disease
Authors: Davis S. R. , Bradbury J. , Bell R. , Johns J. A. 
Published: May 2003

AbstractBackground:  The parenteral administration of oestradiol acutely protects against exercise‐induced myocardial ischaemia in women, but whether this effect is sex ­specific is not known.Aims:  The effects of acutely administered conjugated equine oestrogen on exercise‐induced myocardial ischaemia in men with established coronary heart disease were investigated in a randomized, placebo‐­controlled, double‐blind cross‐over trial.Methods:  Twenty men, aged 62 ± 11.6 years, with reproducible exercise‐induced myocardial ischaemia were treated with either intravenous conjugated equine oestrogen (25 mg) or saline prior to undergoing an exercise stress test. Primary end‐points were total exercise time and time to 1 mm ST‐segment depression.Results:  All participants completed the protocol. Total exercise time exceeded the baseline value in 17 of the 20 men following saline, and in 17 of the 20 men following oestrogen pretreatment. Time to 1 mm ST‐segment depression exceeded the baseline value in 14 of the 19 men following saline, and following oestrogen administration, exceeded baseline in 13 of the 19 men. There was no significant difference between the two treatments in either time to 1 mm ST‐segment depression or total exercise time. A period effect was apparent for total exercise time (P = 0.05) but not for time to ST‐segment depression.Conclusion:  Acute parenteral oestrogen therapy did not increase total exercise time or time to the onset of electrocardiographic changes of ischaemia in men with chronic stable coronary artery disease. These findings contrast the favourable effects of oestrogen in women in comparable studies and indicate a sex specificity for the acute cardiovascular effects of oestrogen. (Intern Med J 2003; 33: 221−224)
Chronic renal insufficiency and renoprotective strategies
Authors: Wyburn K. R. , Horvath J. S. 
Published: May 2003

AbstractThe increasing incidence in the number of patients with end‐stage renal disease is a major public health and economic concern. There is growing awareness that early detection and intervention can have a significant impact on delaying the progression of chronic renal insufficiency and the associated comorbidities. By implementing renoprotective measures early, even modest improvements can equate to significant benefits in the long term, hence the importance of identifying at‐risk patients and early referrals to specialist multidisciplinary teams. In this review, some of the evidence‐based renoprotective measures available are examined. (Intern Med J 2003; 33: 237−241)
Bacterial community structure and function in a metal‐working fluid
Authors: Van Der Gast Christopher J. , Whiteley Andrew S. , Lilley Andrew K. , Knowles Christopher J. , Thompson Ian P. 
Published: May 2003

SummaryThe diversity of bacterial populations colonizing spatially and temporally separated samples of the same metal‐working fluid (MWF) formulation was investigated. Analyses were performed with a view to improve strategies for bioaugmentation of waste MWF in bioreactor systems and prevention of in‐use MWF biodeterioration in engineering workshops. Significantly, complementary phenotypic, genotypic and in situ methods revealed that the bacterial communities in operationally exhausted MWFs had low diversity and were similar in species composition from different locations and uses. Of the 179 bacterial isolates studied, only 11 genera and 15 species were identified using fatty acid methyl ester (FAME) analysis, with culture independent analyses by 16S rDNA denaturing gradient gel electrophoresis (DGGE) and fluorescent in situ hybridization being congruent with these FAME data. In order to gain some insight into functional role of detected populations, we correlated the MWF chemical composition and potential pollution load with bacterial abundance and community composition detected within samples.
The synthesis of the UV‐screening pigment, scytonemin, and photosynthetic performance in isolates from closely related natural populations of cyanobacteria (Calothrix sp.)
Authors: Dillon Jesse G. , Castenholz Richard W. 
Published: May 2003

SummaryTwo populations of the cyanobacterium Calothrix sp. found in Yellowstone thermal spring outflows differ greatly in their contents of scytonemin, a UV‐screening pigment, and in their photosynthetic carbon assimilation rates. Clonal isolates from both populations were used to investigate these phenotypic differences. Identical partial 16S rDNA sequences (∼900 bp) suggest a very close relationship between the two Calothrix populations and indicate that environmental differences may, in part, explain the field observations. The effects of native spring water on scytonemin synthesis and photosynthesis were tested during experiments using plated cells. Results show differences in the spring water environment were at least partly responsible for the differences in scytonemin content observed in the field. Furthermore, spring water effects on photosynthetic performance suggest adaptation in these strains to their spring of origin. Controlled experiments performed using cultures grown in artificial liquid medium showed no significant difference in photosynthetic carbon uptake between strains. However, significant differences were detected in their ability to synthesize scytonemin indicating genetic differences between populations. These findings suggest that both genetic and environmental differences are responsible for the naturally occurring variation in scytonemin content and photosynthetic ability in these two closely related populations.
Local Government and the Politics of Decency*
Authors: Sharp Elaine B. 
Published: May 2003

Objective.Local government officials exhibit a variety of responses to morality issues involving “decency” (i.e., pornography, prostitution, sexually explicit businesses). The purpose of this research is to account for these differences.Methods.This research analyzes a subset of data from a larger study of morality policy making at the local level, that is, all cases of decision making on decency issues (e.g., pornography, prostitution, regulation of sexually explicit businesses, etc.) that occurred in the period 1994–2000 in 10 of the 52 largest cities in the United States.Results.In mayoral settings, decision making on decency cases is likely to evoke pro‐decency action from officials when a high level of issue salience is combined with high levels of church adherence, low levels of women's political empowerment, low levels of fundamentalist religious attachment, and higher levels of per capita income. Officials in city manager settings act more favorably toward decency activists if (1) higher levels of salience combine with a lower prevalence of fundamentalist religious adherents and higher levels of per capita income or (2) there is an interaction of salience and low levels of female political empowerment and high unemployment.Conclusions.Although exploratory in nature, the results confirm conventional expectations concerning the importance of salience and the prevalence of church affiliation; the results are counterintuitive with respect to the prevalence of fundamentalist forces and the extent of female political empowerment.
The Contours and Sources of Ethnic Identity Choices Among Asian Americans*
Authors: Lien Pei‐te , Margaret Conway M. , Wong Janelle 
Published: May 2003

Objective. How do individuals of Asian descent in the United States identify themselves in ethnic terms and why? The purpose of this research is to map the contours of ethnic self‐identities among Asian adults and explain their identity preferences in this immigrant community of color.Methods. We analyze a new and large‐scale survey that collected public opinion from randomly selected individuals of the six largest Asian American descents who resided in five major metropolitan areas in 2000–2001.Results. We find that two‐thirds of the respondents prefer to identify themselves in ethnic‐specific modes. Although only one in six respondents preferred to identify themselves as “Asian American,” close to six in ten respondents indicated acceptance to this panethnic term as part of their identification. Using multinomial regression analysis, we show that indicators of primordial ties and prior socialization, in addition to cultural, social, and political integration, are instrumental in structuring ethnic identity preferences among Asian Americans.Conclusions. Our results confirm ethnic identity as a fluid, malleable, and layered phenomenon that depends on context. Our findings also highlight the need for reconsideration and expansion of the extant conceptual frameworks on studying ethnic identity formation for a nonwhite, multiethnic, multilingual, and globally connected population.
Attenuation of
Mycobacterium tuberculosis
by Disruption of a
mas
-Like Gene or a Chalcone Synthase-Like Gene, Which Causes Deficiency in Dimycocerosyl Phthiocerol Synthesis
Authors: Sirakova Tatiana D. , Dubey Vinod S. , Cynamon Michael H. , Kolattukudy Pappachan E. 
Published: May 2003

ABSTRACT

Tuberculosis is one of the leading preventable causes of death. Emergence of drug-resistant tuberculosis makes the discovery of new targets for antimycobacterial drugs critical. The unique mycobacterial cell wall lipids are known to play an important role in pathogenesis, and therefore the genes responsible for their biosynthesis offer potential new targets. To assess the possible role of some of the genes potentially involved in cell wall lipid synthesis, we disrupted a
mas
-like gene,
msl7
, and a chalcone synthase-like gene,
pks10
, with phage-mediated delivery of the disruption construct, in which the target gene was disrupted by replacement of an internal segment with the hygromycin resistance gene (
hyg
). Gene disruption by allelic exchange in the case of each disruptant was confirmed by PCR and Southern blot analyses. Neither
msl7
nor
pks10
mutants could produce dimycocerosyl phthiocerol, although both could produce mycocerosic acids. Thus, it is concluded that these gene products are involved in the biosynthesis of phthiocerol. Both mutants were found to be attenuated in a murine model, supporting the hypothesis that dimycocerosyl phthiocerol is a virulence factor and thus the many steps involved in its biosynthesis offer potential novel targets for antimycobacterial therapy.
Roles of DegP in Prevention of Protein Misfolding in the Periplasm upon Overexpression of Penicillin Acylase in
Escherichia coli
Authors: Pan Kao-Lu , Hsiao Hsu-Chou , Weng Chiao-Ling , Wu Ming-Sheng , Chou C. Perry 
Published: May 2003

ABSTRACT

Enhancement of the production of soluble recombinant penicillin acylase in
Escherichia coli
via coexpression of a periplasmic protease/chaperone, DegP, was demonstrated. Coexpression of DegP resulted in a shift of in vivo penicillin acylase (PAC) synthesis flux from the nonproductive pathway to the productive one when
pac
was overexpressed. The number of inclusion bodies, which consist primarily of protein aggregates of PAC precursors in the periplasm, was highly reduced, and the specific PAC activity was highly increased. DegP was a heat shock protein induced in response to
pac
overexpression, suggesting that the protein could possibly suppress the physiological toxicity caused by
pac
overexpression. Coexpression of DegP
S210A
, a DegP mutant without protease activity but retaining chaperone activity, could not suppress the physiological toxicity, suggesting that DegP protease activity was primarily responsible for the suppression, possibly by degradation of abnormal proteins when
pac
was overexpressed. However, a shortage of periplasmic protease activity was not the only reason for the deterioration in culture performance upon
pac
overexpression because coexpression of a DegP-homologous periplasmic protease, DegQ or DegS, could not suppress the physiological toxicity. The chaperone activity of DegP is proposed to be another possible factor contributing to the suppression.
Leucines 193 and 194 at the N-Terminal Domain of the XylS Protein, the Positive Transcriptional Regulator of the TOL
meta
-Cleavage Pathway, Are Involved in Dimerization
Authors: Ruíz Raquel , Marqués Silvia , Ramos Juan L. 
Published: May 2003

ABSTRACT

Members of the AraC/XylS family of transcriptional regulators are usually organized in two domains: a conserved domain made up of 100 amino acids and frequently located at the C-terminal end, involved in DNA binding; and an N-terminal nonconserved domain involved in signal recognition, as is the case for regulators involved in the control of carbon metabolism (R. Tobes and J. L. Ramos, Nucleic Acids Res.
30:
318-321, 2002). The XylS protein, which is extremely insoluble, controls expression of the
meta
-cleavage pathway for alkylbenzoate metabolism. We fused the N-terminal end of XylS to the maltose-binding protein (MBP) in vitro and found in glutaraldehyde cross-linking assays that the protein dimerized. Experiments with a chimeric N-terminal XylS linked to a ′LexA protein showed that the dimer was stabilized in the presence of alkylbenzoates. Sequence alignments with AraC and UreR allowed us to identify three residues, Leu193, Leu194, and Ile205, as potentially being involved in dimerization. Site-directed mutagenesis of XylS in which each of the above residues was replaced with Ala revealed that Leu193 and Leu194 were critical for activity and that a chimera in which LexA was linked to the N terminus of XylSLeu193Ala or XylSLeu194Ala was not functional. Dimerization of the chimeras MBP-N-XylSLeu193Ala and MBP-N-XylSLeu194Ala was not observed in cross-linking assays with glutaraldehyde.
Characterization of the Double-Partitioning Modules of R27: Correlating Plasmid Stability with Plasmid Localization
Authors: Lawley Trevor D. , Taylor Diane E. 
Published: May 2003

ABSTRACTPlasmid R27 contains two independent partitioning modules, designated Par1 and Par2, within transfer region 2. Par1 is member of the type I partitioning family (Walker-type ATPase), and Par2 is a member of the type II partitioning family (actin-type ATPase). Stability tests of cloned Par1 and Par2 and insertional disruptions of Par1 and Par2 within R27 demonstrated that Par1 is the major stability determinant whereas Par2 is the minor stability determinant. Creation of double-partitioning mutants resulted in R27 integrating into the chromosome, suggesting that at least one partitioning module is required for R27 to exist in the extrachromosomal form. Using thelacO/LacI-green fluorescent protein (GFP) system, we labeled and visualized R27 and R27 partitioning mutants (Par1−and Par2−) under different growth conditions in liveEscherichia colicells. Plasmid R27 was visualized as the discrete GFP foci present at the mid- and quarter-cell regions in >99% of the cells. Time lapse experiments demonstrated that an increase in R27 plasmid foci resulted from focus duplication in either the mid- or quarter-cell regions ofE. coli. Both R27 Par−variants gave a high percentage of plasmidless cells, as suggested by a uniform GFP signal, and cells with GFP patterns scattered throughout the entire cell, suggesting that plasmid molecules are randomly distributed throughout the cytoplasm. Those cells that did contain R27 Par−with one or two discrete foci had localization patterns that were statistically different from those formed with wild-type R27. Therefore, these results suggest that partitioning-impaired plasmids are characterized by individual and clustered plasmids that are randomly located within the host cytoplasm.