bluuebunny/crossref_metadata_2025_split huggingface dataset:
REVISITING INFORMAL EMPLOYMENT AND SEGMENTATION IN THE SOUTH AFRICAN LABOUR MARKET
Authors: Heintz James , Posel Dorrit 
Published: April 2008

AbstractThis study revisits the definition of informal employment, and it investigates the puzzle of high open unemployment co‐existing with relatively limited informal employment in South Africa. We estimate earnings equations using data from the September 2004 Labour Force Survey and present evidence of persistent earnings differentials not only between formal and informal employment, but also between types of informal employment. These persistent earnings differentials are suggestive of complex segmentation in the South African labour market and challenge the presentation of informal employment as an undifferentiated residual with no barriers to entry or mobility.
HURDLE MODELS OF ALCOHOL AND TOBACCO EXPENDITURE IN SOUTH AFRICAN HOUSEHOLDS1
Authors: Ground Marc , Koch Steven F 
Published: April 2008

AbstractEstimates of participation or expenditure elasticities depend upon the assumptions made regarding the observation of zero expenditure at the household level. This research examines two single‐hurdle models across two commodities for which nearly two‐thirds of the observations are zero. The research shows that one hurdle model consistently outperforms the other, and does so for intuitively appealing reasons.
High Levels of Zidovudine (AZT) and Its Intracellular Phosphate Metabolites in AZT- and AZT-Lamivudine-Treated Newborns of Human Immunodeficiency Virus-Infected Mothers
Authors: Durand-Gasselin Lucie , Pruvost Alain , Dehée Axelle , Vaudre Genevieve , Tabone Marie-Dominique , Grassi Jacques , Leverger Guy , Garbarg-Chenon Antoine , Bénech Henri , Dollfus Catherine 
Published: April 2008

ABSTRACTNewborns from human immunodeficiency virus-infected mothers are given antiretroviral prophylaxis against mother-to-child transmission, including predominantly nucleoside reverse transcriptase inhibitors. Pharmacological monitoring of these drugs in newborns has so far been limited to plasma and cord blood. In this study, samples from newborns (up to 45 days old) treated with zidovudine (AZT) alone (n= 29) or in combination with lamivudine (3TC) (n= 20) were analyzed for both intracellular concentrations of phosphate metabolites in peripheral blood mononuclear cells and levels of parent drugs in plasma. Plasma AZT and intracellular AZT-monophosphate and AZT-triphosphate (TP) concentrations were significantly higher during the first 15 days of life (199 versus 52.7 ng/ml [P< 0.0001], 732 versus 282 fmol/106cells [P< 0.0001], and 170 versus 65.1 fmol/106cells [P< 0.0001], respectively) and then became comparable to those of adults. No difference in intracellular AZT metabolite concentrations was found when AZT- and AZT-3TC-treated groups were compared. Plasma 3TC levels (lower limit of quantification [LLOQ], 1,157 ng/ml; median, 412.5 ng/ml) were not associated with the newborn's age, gender, or weight. Intracellular 3TC-TP concentrations (LLOQ, 40.4 pmol/106cells; median, 18.9 pmol/106cells) determined for newborns receiving the AZT-3TC combination were associated with neither the age nor weight of the newborns. Concentrations in females were significantly higher (1.8-fold [P= 0.0415]) than those in males. Unexpectedly, newborns on AZT monotherapy whose mothers' treatment included 3TC displayed residual plasma 3TC and intracellular 3TC-TP levels up to 1 week after birth.
Mutagenesis in the α3α4 GyrA Helix and in the Toprim Domain of GyrB Refines the Contribution of
Mycobacterium tuberculosis
DNA Gyrase to Intrinsic Resistance to Quinolones
Authors: Matrat Stéphanie , Aubry Alexandra , Mayer Claudine , Jarlier Vincent , Cambau Emmanuelle 
Published: April 2008

ABSTRACT

The replacement of M74 in GyrA, A83 in GyrA, and R447 in GyrB of
Mycobacterium tuberculosis
gyrase by their
Escherichia coli
homologs resulted in active enzymes as quinolone susceptible as the
E. coli
gyrase. This demonstrates that the primary structure of gyrase determines intrinsic quinolone resistance and was supported by a three-dimensional model of N-terminal GyrA.
Characterization of the Ers Regulon of
Enterococcus faecalis
Authors: Riboulet-Bisson Eliette , Sanguinetti Maurizio , Budin-Verneuil Aurélie , Auffray Yanick , Hartke Axel , Giard Jean-Christophe 
Published: April 2008

ABSTRACT

Ers has been qualified as the PrfA-like transcriptional regulator of
Enterococcus faecalis
. In a previous study we reported that Ers is important for the survival within macrophages of this opportunist pathogenic bacterium. In the present work we have used proteomic and microarray expression profiling of
E. faecalis
JH2-2 and an
ers
-deleted mutant (Δ
ers
mutant) strains to define the Ers regulon. In addition to EF_0082 (encoding a putative facilitator family transporter), already known to be under Ers regulation, three genes or operons displayed a significant decrease (confirmed by reverse transcription quantitative PCR) in expression in the Δ
ers
mutant. The first locus corresponds to three genes:
arcA
,
arcB
, and
arcC1
(
arcABC
). These genes are members of the ADI operon, encoding enzymes of the arginine deiminase system. The second is the EF_1459 gene, which encodes a hypothetical protein and is located within a putative phage genetic element. Lastly, Ef_3319 is annotated as the alpha subunit of the citrate lyase encoded by
citF. citF
is a member of a putative 12-gene operon involved in citrate catabolism. Moreover, the promoter sequence, similar to the “PrfA box” and found in the promoter regions of
ers
and EF_0082, has been shown to be included in the DNA segment recognized by Ers. Phenotypic analysis of the Δ
ers
mutant strain revealed a growth defect when cultured with arginine or citrate as the energy source; this was not seen for the wild type. As expected, similar results were obtained with mutants in which
arcA
and
citF
were inactivated. In addition, in the mouse peritonitis model of virulence, the Δ
ers
mutant appeared significantly less lethal than the JH2-2 wild-type strain. Taken together, these results indicate that the regulator Ers has a pleiotropic effect, especially in the cellular metabolism and virulence of
E. faecalis
.
Suppression of T-Lymphocyte Activation and Chemotaxis by the Adenylate Cyclase Toxin ofBordetella pertussis
Authors: Paccani Silvia Rossi , Molin Federica Dal , Benagiano Marisa , Ladant Daniel , D'Elios Mario M. , Montecucco Cesare , Baldari Cosima T. 
Published: April 2008

ABSTRACTThe adenylate cyclase toxin (CyaA) released byBordetella pertussisis an essential virulence factor for colonization of the host. This toxin inhibits migration and activation of phagocytes, thereby preventing bacterial killing. In addition, CyaA interferes with the initiation of adaptive immunity by misdirecting dendritic cell differentiation to a suppressive rather than stimulatory phenotype. Here we show that CyaA directly affects adaptive responses by catalyzing cyclic AMP (cAMP) production in peripheral blood lymphocytes. Treatment with CyaA resulted in profound impairment of T-lymphocyte activation and chemotaxis. These effects resulted from inhibition of T-cell antigen receptor and chemokine receptor signaling via a cAMP/protein kinase A (PKA)-dependent pathway. A comparison of the activities of CyaA on T-cell and macrophage activation and migration revealed that the biological effects of the toxin were paralleled by inhibition of the activation of mitogen-activated protein (MAP) kinases, highlighting the conclusion that the ubiquitous and evolutionarily conserved MAP kinase modules are common targets of the PKA-mediated immunosuppressant activities of CyaA and underlining the potential of cAMP-elevating toxins as a means of evasion of immunity by bacterial pathogens.
Significant Role for
ladC
in Initiation of
Legionella pneumophila
Infection
Authors: Newton Hayley J. , Sansom Fiona M. , Dao Jenny , Cazalet Christel , Bruggemann Holger , Albert-Weissenberger Christiane , Buchrieser Carmen , Cianciotto Nicholas P. , Hartland Elizabeth L. 
Published: April 2008

ABSTRACT

Previously, we identified
ladC
in a cohort of genes that were present in
Legionella pneumophila
but absent in other
Legionella
species. Here we constructed a
ladC
mutant of
L. pneumophila
and assessed its ability to replicate in mammalian cell lines and
Acanthamoeba castellanii
. The
ladC
mutant was recovered in significantly lower numbers than wild-type
L. pneumophila
at early time points, which was reversed upon transcomplementation with
ladC
but not
ladC
N430A/R434A
, encoding a putative catalytically inactive derivative of the protein. In fact, complementation of
ladC
::Km with
ladC
N430A/R434A
resulted in a severe replication defect within human and amoeba cell models of infection, which did not follow a typical dominant negative phenotype. Using differential immunofluorescence staining to distinguish adherent from intracellular bacteria, we found that the
ladC
mutant exhibited a 10-fold reduction in adherence to THP-1 macrophages but no difference in uptake by THP-1 cells. When tested in vivo in A/J mice, the competitive index of the
ladC
mutant dropped fivefold over 72 h, indicating a significant attenuation compared to wild-type
L. pneumophila
. Although localization of LadC to the bacterial inner membrane suggested that the protein may be involved in signaling pathways that regulate virulence gene expression, microarray analysis indicated that
ladC
does not influence the transcriptional profile of
L. pneumophila
in vitro or during
A. castellanii
infection. Although the mechanism by which LadC modulates the initial interaction between the bacterium and host cell remains unclear, we have established that LadC plays an important role in
L. pneumophila
infection.
The Tick Salivary Protein Salp15 Inhibits the Killing of Serum-Sensitive
Borrelia burgdorferi
Sensu Lato Isolates
Authors: Schuijt Tim J. , Hovius Joppe W. R. , van Burgel Nathalie D. , Ramamoorthi Nandhini , Fikrig Erol , van Dam Alje P. 
Published: April 2008

ABSTRACT

Borrelia burgdorferi
, the agent of Lyme disease, is transmitted by ticks. During transmission from the tick to the host, spirochetes are delivered with tick saliva, which contains the salivary protein Salp15. Salp15 has been shown to protect spirochetes against
B. burgdorferi
-specific antibodies. We now show that Salp15 from both
Ixodes ricinus
and
Ixodes scapularis
protects serum-sensitive isolates of
Borrelia burgdorferi
sensu lato against complement-mediated killing.
I. ricinus
Salp15 showed strong protective effects compared to those of
I. scapularis
Salp15. Deposition of terminal C5b to C9 (one molecule each of C5b, C6, C7, and C8 and one or more molecules of C9) complement complexes, part of the membrane attack complex, on the surface of
B. burgdorferi
was inhibited in the presence of Salp15. In the presence of normal human serum, serum-sensitive
Borrelia burgdorferi
requires protection against complement-mediated killing, which is provided, at least in part, by the binding to the tick salivary protein Salp15.
The Inositol Phosphatase SHIP Controls
Salmonella enterica
Serovar Typhimurium Infection In Vivo
Authors: Bishop Jennifer L. , Sly Laura M. , Krystal Gerald , Finlay B. Brett 
Published: April 2008

ABSTRACT

The SH2 domain-containing inositol 5′-phosphatase, SHIP, negatively regulates various hematopoietic cell functions and is critical for maintaining immune homeostasis. However, whether SHIP plays a role in controlling bacterial infections in vivo remains unknown.
Salmonella enterica
causes human salmonellosis, a disease that ranges in severity from mild gastroenteritis to severe systemic illness, resulting in significant morbidity and mortality worldwide. The susceptibility of
ship
+/+
and
ship
−/−
mice and bone marrow-derived macrophages to
S. enterica
serovar Typhimurium infection was compared.
ship
−/−
mice displayed an increased susceptibility to both oral and intraperitoneal serovar Typhimurium infection and had significantly higher bacterial loads in intestinal and systemic sites than
ship
+/+
mice, indicating a role for SHIP in the gut-associated and systemic pathogenesis of serovar Typhimurium in vivo. Cytokine analysis of serum from orally infected mice showed that
ship
−/−
mice produce lower levels of Th1 cytokines than do
ship
+/+
animals at 2 days postinfection, and in vitro analysis of supernatants taken from infected bone marrow-derived macrophages derived to mimic the in vivo ship
−/−
alternatively activated (M2) macrophage phenotype correlated with these data. M2 macrophages were the predominant population in vivo in both oral and intraperitoneal infections, since tissue macrophages within the small intestine and peritoneal macrophages from
ship
−/−
mice showed elevated levels of the M2 macrophage markers Ym1 and Arginase 1 compared to
ship
+/+
cells. Based on these data, we propose that M2 macrophage skewing in
ship
−/−
mice contributes to ineffective clearance of
Salmonella
in vivo.
tRNA Modification by GidA/MnmE Is Necessary forStreptococcus pyogenesVirulence: a New Strategy To Make Live Attenuated Strains
Authors: Cho Kyu Hong , Caparon Michael G. 
Published: April 2008

ABSTRACTStudies directed at vaccine development and mucosal immunity againstStreptococcus pyogeneswould benefit from the availability of live attenuated strains. Our approach for production of candidate live attenuated strains was to identify mutations that did not alter growth in vitro and did not alter the overall complement of virulence factors produced but did result in reduced levels of expression of multiple secreted virulence factors. A global reduction but not elimination of expression would likely lead to attenuation while maximizing the number of antigenic targets available for stimulation of immunity. Adaptation of Tn5-based transposome mutagenesis toS. pyogeneswith initial screening for reduced expression of the SpeB protease resulted in identification of mutations ingidA, which encodes an enzyme involved in tRNA modification. Reduced SpeB expression was due to delayed onset ofspeBtranscription resulting from reduced translation efficiency of the message for RopB, a transcriptional activator. Overall, GidA−mutants had a nearly normal global transcription profile but expressed significantly reduced levels of multiple virulence factors due to impaired translation efficiencies. A translation defect was supported by the observation that mutants lacking MnmE, which functions in the same tRNA modification pathway as GidA, phenocopied GidA deficiency. The mutants stimulated a cytokine response in cultured macrophages identical to that in the wild type, with the exception of reduced levels of tumor necrosis factor alpha and interleukin-23. Significantly, GidA−mutants were highly attenuated in the murine ulcer model of soft tissue infection. These characteristics suggest that GidA pathway tRNA modification mutants are attractive candidates for further evaluation as live attenuated strains.
Reference intervals of common serum analytes of Hong Kong Chinese
Authors: Chan A O K , Lee K C , Leung J N S , Shek C C 
Published: April 2008

Aim:Setting up reference intervals from the local service populations is one of the major responsibilities of clinical laboratories. Yet, this task is difficult to achieve because it is costly and time consuming when compared with validating reference intervals from assay manufacturers.Methods:Following the recommendations of the International Federation of Clinical Chemistry, healthy local Chinese adults were recruited to set up reference intervals for common serum analytes. Statistical methods recommended by the National Committee for Clinical Laboratory Standards were used for defining the reference limits.Results:Data from 335 subjects were analysed. The reference intervals set up were broadly similar to those provided by the assay manufacturer, except for sodium and potassium. Glomerular filtration rate was estimated by the modification of diet in renal disease equation, with or without modification for Chinese. Body mass index had a significant impact on serum urate and alanine aminotransferase levels.Conclusion:Reference intervals of common serum analytes have been set up for the local Chinese population. A good example of quality laboratory service has also been set up to provide clinicians with reliable reference intervals that they can confidently rely on for the diagnosis and management of patients.
Population tobacco control interventions and their effects on social inequalities in smoking: systematic review
Authors: Thomas S , Fayter D , Misso K , Ogilvie D , Petticrew M , Sowden A , Whitehead M , Worthy G 
Published: April 2008

Objective:To assess the effects of population tobacco control interventions on social inequalities in smoking.Data sources:Medical, nursing, psychological, social science and grey literature databases, bibliographies, hand-searches and contact with authors.Study selection:Studies were included (n = 84) if they reported the effects of any population-level tobacco control intervention on smoking behaviour or attitudes in individuals or groups with different demographic or socioeconomic characteristics.Data extraction:Data extraction and quality assessment for each study were conducted by one reviewer and checked by a second.Data synthesis:Data were synthesised using graphical (“harvest plot”) and narrative methods. No strong evidence of differential effects was found for smoking restrictions in workplaces and public places, although those in higher occupational groups may be more likely to change their attitudes or behaviour. Smoking restrictions in schools may be more effective in girls. Restrictions on sales to minors may be more effective in girls and younger children. Increasing the price of tobacco products may be more effective in reducing smoking among lower-income adults and those in manual occupations, although there was also some evidence to suggest that adults with higher levels of education may be more price-sensitive. Young people aged under 25 are also affected by price increases, with some evidence that boys and non-white young people may be more sensitive to price.Conclusions:Population-level tobacco control interventions have the potential to benefit more disadvantaged groups and thereby contribute to reducing health inequalities.
Chemistry and ectomycorrhizal communities of coarse wood in young and old-growth forests in the Cascade Range of Oregon
Authors: Elliott J. C. , Smith J. E. , Cromack K. , Chen H. , McKay D. 
Published: April 2008

Coarse wood provides important ecosystem structure and function such as water and nutrient storage and critical habitat for the conservation of a variety of organisms, including ectomycorrhizal (EM) fungi. The chemistry and EM communities were compared in coarse wood samples collected from two advanced decay stages of logs in 12 paired young and old-growth stands in the Oregon Cascade Range. Average total C and nonpolar extractives were higher in young stands (15–55 years) (mean = 53.38%, 95% CI of 52.48–54.27 and mean = 8.54%, 95% CI of 6.92–10.16, respectively) compared with old-growth stands (200–500 years) (mean = 51.22%, 95% CI of 49.67–52.77 and mean = 6.75%, 95% CI of 5.88–7.62, respectively). Averages for total and extractable P were higher in old-growth stands (mean = 0.03%, 95% CI of 0.02–0.04 and mean = 82.91, 95% CI of 52.24–113.57, respectively) compared with young stands (mean = 0.02%, 95% CI of 0.02–0.02 and mean = 56.17, 95% CI of 45.84–66.50, respectively). Average pH and total N were highest in logs in the most advanced decay stage (mean = 4.17, 95% CI of 3.97–4.38 and mean = 0.35%, 95% CI of 0.29–0.40, respectively). No differences between log decay class or stand age were detected for water-soluble extractives, hemicellulose plus cellulose (or acid-hydrolyzable fraction), or acid-unhydrolyzable residue. Observed differences in average wood property values between decay stages and between young and old-growth stands were small and, although statistically significant, may not reflect an important difference in EM fungal habitat. EM communities were similar between young and old-growth stands and between logs in decay classes 4 and 5. Results suggest that down wood in advanced decay stages provides similar habitat for EM fungi in both old-growth and young, managed stands.
A novel rapid sampling method for pinewood nematode, Bursaphelenchus xylophilus (Nematoda: Parasitaphelenchidae)
Authors: Zhao Lilin , Wei Wei , Liu Xinzhong , Kang Le , Sun Jianghua 
Published: April 2008

The pinewood nematode, Bursaphelenchus xylophilus (Steiner & Buhrer) Nickle, is listed as a quarantine pest in the legislation of more than 40 countries. Rapid and accurate detection of the pinewood nematode in coniferous chips, sawn wood, and logs is critical in preventing the introduction of the nematode and forms the basis for quarantine regulations. The traditional but laborious Baermann-funnel sampling technique delays the detection of pinewood nematode. We applied the chemotactic response of pinewood nematode to its insect vector, Monochamus alternatus Hope, to develop a novel and rapid sampling method. A trap tube, baited with a blend of attractant terpenes (α-pinene, β-pinene, and longifolene, 1:2.7:1.1) is shown to effectively capture third-stage dispersal juveniles of pinewood nematode from infested wood under laboratory and field conditions. Nematodes were first isolated after a 2 h trapping period, and the number of nematodes recovered increased with the duration of trapping. This chemical attraction technique is simple, effective, and rapid and should assist greatly in the detection of pinewood nematode at both ports-of-entry and forest habitats.
Approximating natural landscape pattern using aggregated harvest
Authors: Carlson Matthew , Kurz Werner A. 
Published: April 2008

Successful implementation of the natural disturbance model for timber harvest is hindered by the lack of strategies to approximate landscape fire pattern. In the forests of Alberta, Canada, the fire regime is dominated by large fires that create large regions of same-aged forest. Current forestry practices disperse harvest blocks across the landscape, causing increased fragmentation as compared with fire. Aggregating harvest blocks is one potential strategy to improve approximation of natural landscape pattern. We used a simulation approach to compare landscape pattern created by aggregated harvest strategies, the current dispersed harvest approach, and the natural disturbance regime for a 270 000 ha forest landscape in northeastern Alberta. Compared with dispersed harvest, aggregated strategies increased compatibility with natural landscape pattern by reducing fragmentation. Capacity to aggregate harvest declined when the constraint of maintaining a constant proportion of deciduous to coniferous harvest was included. We conclude that aggregated harvest can improve implementation of the natural disturbance model by bringing several landscape metrics closer to the conditions that fall within the natural range of variability. Aggregated harvest alone, however, performed poorly at maintaining interior old forest, emphasizing that an explicit old-forest strategy is also required.