867 research outputs found
The heme sensing response regulator HssR in Staphylococcus aureus but not the homologous RR23 in Listeria monocytogenes modulates susceptibility to the antimicrobial peptide plectasin
<p>Abstract</p> <p>Background</p> <p>Host defence peptides (HDPs), also known as antimicrobial peptides (AMPs), have emerged as potential new therapeutics and their antimicrobial spectrum covers a wide range of target organisms. However, the mode of action and the genetics behind the bacterial response to HDPs is incompletely understood and such knowledge is required to evaluate their potential as antimicrobial therapeutics. Plectasin is a recently discovered HDP active against Gram-positive bacteria with the human pathogen, <it>Staphylococcus aureus </it>(<it>S. aureus</it>) being highly susceptible and the food borne pathogen, <it>Listeria monocytogenes </it>(<it>L. monocytogenes</it>) being less sensitive. In the present study we aimed to use transposon mutagenesis to determine the genetic basis for <it>S. aureus </it>and <it>L. monocytogenes </it>susceptibility to plectasin.</p> <p>Results</p> <p>In order to identify genes that provide susceptibility to plectasin we constructed bacterial transposon mutant libraries of <it>S. aureus </it>NCTC8325-4 and <it>L. monocytogenes </it>4446 and screened for increased resistance to the peptide. No resistant mutants arose when <it>L. monocytogenes </it>was screened on plates containing 5 and 10 fold Minimal Inhibitory Concentration (MIC) of plectasin. However, in <it>S. aureus</it>, four mutants with insertion in the heme response regulator (<it>hssR</it>) were 2-4 fold more resistant to plectasin as compared to the wild type. The <it>hssR </it>mutation also enhanced resistance to the plectasin-like defensin eurocin, but not to other classes of HDPs or to other stressors tested. Addition of plectasin did not influence the expression of <it>hssR </it>or <it>hrtA</it>, a gene regulated by HssR. The genome of <it>L. monocytogenes </it>LO28 encodes a putative HssR homologue, RR23 (in <it>L. monocytogenes </it>EGD-e lmo2583) with 48% identity to the <it>S. aureus </it>HssR, but a mutation in the <it>rr23 </it>gene did not change the susceptibility of <it>L. monocytogenes </it>to plectasin.</p> <p>Conclusions</p> <p><it>S. aureus </it>HssR, but not the homologue RR23 from <it>L. monocytogenes</it>, provides susceptibility to the defensins plectasin and eurocin. Our data suggest that a functional difference between response regulators HssR and RR23 is responsible for the difference in plectasin susceptibility observed between <it>S. aureus </it>and <it>L. monocytogenes</it>.</p
Shifting Home Energy Consumption Through a Holistic Understanding of the Home System of Practice
This chapter describes the concept of the home system of practice, which can be used to provide a deeper understanding of the social system of the home and inform long-term solutions for enabling domestic energy reduction. More traditional methods have attempted to persuade occupants to change behaviour through the use of information campaigns and feedback technology. However, these interventions are usually short lived as they ignore the underlying reasons for practices to occur. A more effective solution is through practice-oriented design, which co-creates innovative technology with the user. In addition, the emergence and use of automated technology enables practices to act independently of the user. Yet, the success of automation is also reliant on an understanding of the home system of practice, occupant needs and skills
How moving home influences appliance ownership: a Passivhaus case study
Low carbon dwellings shift the focus to electricity consumption and appliances by significantly lowering space heating energy consumption. Using a UK Passivhaus (low carbon) case study, interviews and pre/post-move-in appliance audits were employed to investigate how moving home can change the appliance requirements of appliance-using practices. Changes in appliance ownership were due to differences in how appliance-using practices (e.g. cooking, laundering, homemaking) were being performed. Existing/new appliances complemented/conflicted with a new home on the basis of whether the social meanings of specific appliance-using practices (e.g. stylishness, convenience, thermal comfort, cleanliness) could be met. This was evident, when moving home more generally, by households buying new modern appliances and managing spatial constraints. More specifically, regarding Passivhaus, hosting and homemaking practices were performed in ways that met thermal comfort expectations, in addition to appliance purchasing also being influenced by a fear that the Passivhaus technologies could fail. Whilst skills and competences were needed to perform appliance-using practices, these were less prominent in influencing appliance ownership changes. Conclusions include reflections on how the elements of appliance-using practices change when moving home, as well as what adhering to building standards could mean for the standardisation of appliance-using practices and domestic life more generally
Percentage density, Wolfe's and Tabár's mammographic patterns: agreement and association with risk factors for breast cancer
INTRODUCTION: The purpose of this report was to classify mammograms according to four methods and to examine their agreement and their relationship to selected risk factors for breast cancer. METHOD: Mammograms and epidemiological data were collected from 987 women, aged 55 to 71 years, attending the Norwegian Breast Cancer Screening Program. Two readers each classified the mammograms according to a quantitative method (Cumulus or Madena software) and one reader according to two qualitative methods (Wolfe and Tabár patterns). Mammograms classified in the reader-specific upper quartile of percentage density, Wolfe's P2 and DY patterns, or Tabár's IV and V patterns, were categorized as high-risk density patterns and the remaining mammograms as low-risk density patterns. We calculated intra-reader and inter-reader agreement and estimated prevalence odds ratios of having high-risk mammographic density patterns according to selected risk factors for breast cancer. RESULTS: The Pearson correlation coefficient was 0.86 for the two quantitative density measurements. There was moderate agreement between the Wolfe and Tabár classifications (Kappa = 0.51; 95% confidence interval 0.46 to 0.56). Age at screening, number of children and body mass index (BMI) showed a statistically significant inverse relationship with high-risk density patterns for all four methods (all P < 0.05). After adjustment for percentage density, the Wolfe classification was not associated with any of the risk factors for breast cancer, whereas the association with number of children and BMI remained statistically significant for the Tabár classification. Adjustment for Wolfe or Tabár patterns did not alter the associations between these risk factors and percentage mammographic density. CONCLUSION: The four assessments methods seem to capture the same overall associations with risk factors for breast cancer. Our results indicate that the quantitative methods convey additional information over the qualitative methods
Different measures of smoking exposure and mammographic density in postmenopausal Norwegian women: a cross-sectional study
Background: Recent cohort studies have suggested an
increased risk of breast cancer with long duration of smoking,
and with smoking initiation before first birth. Cigarette smoking
may have both carcinogenic effects and antiestrogenic effects
on the breast tissue. We decided to examine the relationship
between different measures of smoking exposure and
mammographic density.
Methods: Lifetime smoking history was collected through
interview and questionnaires among 907 postmenopausal
participants in the Tromsø Mammography and Breast Cancer
study. The mammograms were obtained from the governmental
Norwegian Breast Cancer Screening Program. Mammograms
were classified according to the percentage and absolute
mammographic densities using a previously validated computerassisted
method.
Results:Sixty-five percent of the women reported having ever
smoked cigarettes, while 34% were current smokers. After
adjustment for age, age at first birth, parity, age at menopause,
postmenopausal hormone therapy use, and body mass index,
smoking was inversely associated with both measures of
mammographic density (both trends P < 0.01). Both current
smokers and former smokers had significantly lower adjusted
mean percentage mammographic density compared with never
smokers (P = 0.003 and P = 0.006, respectively). An inverse
dose–response relationship with mammographic density was
found between both the number of cigarettes and the number of
pack-years smoked among current smokers. Current smokers
who smoked 11 cigarettes or more daily had a 3.7% absolute
(36% relative difference) lower percentage mammographic
density compared with current smokers who smoked seven
cigarettes or less daily (P = 0.008). When former smokers were
stratified according to time since smoking cessation, we found
that women who had stopped smoking less than 24 years ago
had a significantly lower mean percentage mammographic
density compared with never smokers (P < 0.001).
Conclusion: We found modest inverse dose–response
associations between numbers of cigarettes and of pack-years
smoked and both measures of mammographic density among
current smokers. Former smokers who had stopped smoking
less than 24 years ago also had a statistically significantly lower
mean percentage mammographic density when compared with
never smokers. These findings are consistent with an
antiestrogenic effect of cigarette smoking on the breast tissue
Two‐nucleon processes in pion‐induced double charge exchange in 4He: A coincidence measurement of the 4He(π+,π− p)3p reaction
Inclusive measurements of pion double‐charge‐exchange in 3He[1] and 4He[2] in the Δ(1232) resonance region suggest the dominance of a two‐step sequential single‐charge‐exchange mechanism involving quasi‐free nucleons. To investigate this reaction mechanism, we have observed protons in coincidence with the outgoing pion in π++4He→π−+4p at Tπ+=240 MeV. Pions were detected in a magnetic spectrometer at θπ−=32°, while protons were detected in a close‐packed array of plastic scintillator telescopes covering θp=67.5°–157.5° on the same side of the beam as the spectrometer, and θp=22.5°–157.5° on the opposite side. We will present preliminary results for the distributions in energy and angle of the coincident protons. © 1995 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87562/2/542_1.pd
Householders’ Mental Models of Domestic Energy Consumption: Using a Sort-And-Cluster Method to Identify Shared Concepts of Appliance Similarity
If in-home displays and other interventions are to successfully influence people's energy consumption, they need to communicate about energy in terms that make sense to users. Here we explore householders' perceptions of energy consumption, using a novel combination of card-sorting and clustering to reveal shared patterns in the way people think about domestic energy consumption. The data suggest that, when participants were asked to group appliances which they felt naturally 'went together', there are relatively few shared ideas about which appliances are conceptually related. To the extent participants agreed on which appliances belonged together, these groupings were based on activities (e.g., entertainment) and location within the home (e.g., kitchen); energy consumption was not an important factor in people's categorisations. This suggests messages about behaviour change aimed at reducing energy consumption might better be tied to social practices than to consumption itself
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