Publications by authors named "David Willis"

61 Publications

Parentage-based tagging combined with genetic stock identification is a cost-effective and viable replacement for coded-wire tagging in large-scale assessments of marine Chinook salmon fisheries in British Columbia, Canada.

Evol Appl 2021 May 19;14(5):1365-1389. Epub 2021 Mar 19.

Fisheries and Oceans Canada Pacific Biological Station Nanaimo British Columbia Canada.

Wild Pacific salmon, including Chinook salmon , have been supplemented with hatchery propagation for over 50 years in support of increased ocean harvest, mitigation for hydroelectric development, and conservation of threatened populations. In Canada, the Wild Salmon Policy for Pacific salmon was established with the goal of maintaining and restoring healthy and diverse Pacific salmon populations, making conservation of wild salmon and their habitats the highest priority for resource management decision-making. For policy implementation, a new approach to the assessment and management of Chinook salmon and the associated hatchery production and fisheries management are needed. Implementation of genetic stock identification (GSI) and parentage-based tagging (PBT) for marine fisheries assessment may overcome problems associated with coded-wire tag-based (CWT) assessment and management of Chinook salmon fisheries, providing at a minimum information equivalent to that derived from the CWT program. GSI and PBT were used to identify Chinook salmon sampled in 2018 and 2019 marine fisheries (18,819 individuals genotyped) in British Columbia to specific conservation units (CU), populations, and broodyears. Individuals were genotyped at 391 single nucleotide polymorphisms via direct sequencing of amplicons. Very high accuracy of assignment to population and age (>99.5%) via PBT was observed for 1994 Chinook salmon of ages 2-4 years, with a 105,722-individual, 380-population baseline available for assignment. Application of a GSI-PBT system of identification to individuals in 2019 fisheries provided high-resolution estimates of stock composition, catch, and exploitation rate by CU or population, with fishery exploitation rates directly comparable to those provided by CWTs for 13 populations. GSI and PBT provide an alternate, cheaper, and more effective method in the assessment and management of Canadian-origin Chinook salmon relative to CWTs, and an opportunity for a genetics-based system to replace the current CWT system for salmon assessment.
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http://dx.doi.org/10.1111/eva.13203DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8127719PMC
May 2021

Insights on the concept of indicator populations derived from parentage-based tagging in a large-scale coho salmon application in British Columbia, Canada.

Ecol Evol 2020 Jul 18;10(13):6461-6476. Epub 2020 May 18.

Fisheries and Oceans Canada Pacific Biological Station Nanaimo BC Canada.

For Pacific salmon, the key fisheries management goal in British Columbia (BC) is to maintain and restore healthy and diverse Pacific salmon populations, making conservation of salmon biodiversity the highest priority for resource management decision-making. Salmon status assessments are often conducted on coded-wire-tagged subsets of indicator populations based on assumptions of little differentiation within or among proximal populations. In the current study of southern BC coho salmon () populations, parentage-based tagging (PBT) analysis provided novel information on migration and life-history patterns to test the assumptions of biological homogeneity over limited (generally < 100 km) geographic distances and, potentially, to inform management of fisheries and hatchery broodstocks. Heterogeneity for location and timing of fishery captures, family productivity, and exploitation rate was observed over small geographic scales, within regions that are, or might be expected to be, within the area encompassed by a single-tagged indicator population. These results provide little support for the suggestion that information gained from tagged indicator populations is representative of marine distribution, productivity, and exploitation patterns of proximal populations.
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http://dx.doi.org/10.1002/ece3.6383DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7381759PMC
July 2020

Variation in migration pattern, broodstock origin, and family productivity of coho salmon hatchery populations in British Columbia, Canada, derived from parentage-based tagging.

Ecol Evol 2019 Sep 18;9(17):9891-9906. Epub 2019 Aug 18.

Fisheries and Oceans Canada Pacific Biological Station Nanaimo BC Canada.

In salmonid parentage-based tagging (PBT) applications, entire hatchery broodstocks are genotyped, and subsequently, progeny can be nonlethally sampled and assigned back to their parents using parentage analysis, thus identifying their hatchery of origin and brood year (i.e., age). Inter- and intrapopulation variability in migration patterns, life history traits, and fishery contributions can be determined from PBT analysis of samples derived from both fisheries and escapements (portion of a salmon population that does not get caught in fisheries and returns to its natal river to spawn). In the current study of southern British Columbia coho salmon () populations, PBT analysis provided novel information on intrapopulation heterogeneity among males in the total number of progeny identified in fisheries and escapements, the proportion of progeny sampled from fisheries versus escapement, the proportion of two-year-old progeny (jacks) produced, and the within-season return time of progeny. Fishery recoveries of coho salmon revealed heterogeneity in migration patterns among and within populations, with recoveries from north and central coast fisheries distinguishing "northern migrating" from "resident" populations. In northern migrating populations, the mean distance between fishery captures of sibs (brothers and sisters) was significantly less than the mean distance between nonsibs, indicating the possible presence of intrapopulation genetic heterogeneity for migration pattern. Variation among populations in productivity and within populations in fish catchability indicated that population selection and broodstock management can be implemented to optimize harvest benefits from hatcheries. Application of PBT provided valuable information for assessment and management of hatchery-origin coho salmon in British Columbia.
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http://dx.doi.org/10.1002/ece3.5530DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6745653PMC
September 2019

Paediatric image-guided radiation therapy: determining and evaluating appropriate kilovoltage planar exposure factors for the Varian on-board imager.

J Med Radiat Sci 2020 Mar 3;67(1):16-24. Epub 2019 Sep 3.

Radiation Therapy Department, Sunshine Coast University Hospital, Birtinya, Queensland, Australia.

Introduction: Kilovoltage (kV) orthogonal imaging is commonly used for image-guided radiation therapy (IGRT) in paediatrics. Paediatrics have an increased sensitivity to radiation. Exposure factors need to be optimised so that imaging dose is kept as low as reasonably achievable (ALARA).

Methods: A table of low-dose IGRT radiographic exposure factors for paediatric IGRT was determined through a phantom study. Four anatomical sites, head and neck, thorax, abdomen and pelvis, were investigated. The table was evaluated against standard manufacturer pre-sets. Dose was evaluated in terms of system-reported entrance surface air kerma (ESAK). Qualified participants volunteered to perform offline image matching in a further phantom study, recording misalignments detected and providing subjective assessments of image quality using an electronic survey tool. A statistical comparison of matching accuracy was conducted.

Results: Twelve radiation therapists or radiation oncologists completed the image matching task and survey. The low-dose exposure table reduced imaging dose by 20-94% compared to manufacturer pre-sets. No significant difference was observed in the accuracy of image matching (head and neck P = 0.82, thorax P = 0.15, abdomen P = 0.33, pelvis P = 0.59). Participant image exposure preference was largely equivocal.

Conclusions: Optimising radiographic exposures in paediatric IGRT is feasible, logical and therefore reasonably achievable. Implementation of the low-dose exposure table presented in this study should be considered by paediatric radiotherapy departments wishing to image gently without compromising the potential to detect set up errors. Further study using a contrast detail phantom and contrast to noise image analysis software is recommended.
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http://dx.doi.org/10.1002/jmrs.352DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7063249PMC
March 2020

Comparison of coded-wire tagging with parentage-based tagging and genetic stock identification in a large-scale coho salmon fisheries application in British Columbia, Canada.

Evol Appl 2019 Feb 11;12(2):230-254. Epub 2018 Oct 11.

Fisheries and Oceans Canada Pacific Biological Station Nanaimo BC Canada.

Wild Pacific salmon, including Coho salmon , have been supplemented with hatchery propagation for over 50 years in support of increased ocean harvest and conservation of threatened populations. In Canada, the Wild Salmon Policy for Pacific salmon was established with the goal of maintaining and restoring healthy and diverse Pacific salmon populations, making conservation of wild salmon and their habitats the highest priority for resource management decision-making. A new approach to the assessment and management of wild coho salmon, and the associated hatchery production and fishery management is needed. Implementation of parentage-based tagging (PBT) may overcome problems associated with coded-wire tag-based (CWT) assessment and management of coho salmon fisheries, providing at a minimum information equivalent to that derived from the CWT program. PBT and genetic stock identification (GSI) were used to identify coho salmon sampled in fisheries (8,006 individuals) and escapements (1,692 individuals) in British Columbia to specific conservation units (CU), populations, and broodyears. Individuals were genotyped at 304 single nucleotide polymorphisms (SNPs) via direct sequencing of amplicons. Very high accuracy of assignment to population (100%) via PBT for 543 jack (age 2) assigned to correct age and collection location and 265 coded-wire tag (CWT, age 3) coho salmon assigned to correct age and release location was observed, with a 40,774-individual, 267-population baseline available for assignment. Coho salmon from un-CWTed enhanced populations contributed 65% of the catch in southern recreational fisheries in 2017. Application of a PBT-GSI system of identification to individuals in 2017 fisheries and escapements provided high-resolution estimates of stock composition, catch, and exploitation rate by CU or population, providing an alternate and more effective method in the assessment and management of Canadian-origin coho salmon relative to CWTs, and an opportunity for a genetic-based system to replace the current CWT system for coho salmon assessment.
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http://dx.doi.org/10.1111/eva.12711DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6346672PMC
February 2019

Redesigning the Maternal, Infant and Early Childhood Home Visiting Program Performance Measurement System.

Matern Child Health J 2018 04;22(4):467-473

Maternal and Child Health Bureau, Health Resources and Services Administration, 5600 Fishers Lane, Rockville, MD, 20857, USA.

Objectives Statute for the Maternal, Infant and Early Childhood Home Visiting (MIECHV) Program requires that states and territories receiving Program funding assess improvements for participating families across six areas that address maternal and child well-being. In 2015, the MIECHV Program performance measurement system was redesigned to allow for national-level analyses and cross-grantee comparisons. The new measures were aligned with other federal performance measures to help ensure context for program analyses. The number of measures was also reduced to lessen reporting burden. This paper describes the redesign process and resulting national performance measures. Methods The redesign process included holding listening sessions with stakeholders and experts; reviewing the findings from other home visiting performance initiatives; consulting with experts; soliciting and responding to public comment on draft measures; seeking clearance from the Office of Management and Budget; and specifying each measure with detailed eligibility criteria, the timing and frequency of assessments, and the window for data collection. Results The redesign resulted in a set of 19 measures that all MIECHV-funded home visiting programs began collecting in 2016. This is nearly half the number of measures that MIECHV awardees had been reporting prior to the redesign. The measures are aligned with other federal measures, including those used in Healthy People 2020 and those used for other maternal and child health programs. Conclusions for Practice Data reported by MIECHV Program awardees will be used to assess their performance, identify areas for targeted technical assistance to support continuous improvement, and ensure meaningful impacts for at-risk families.
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http://dx.doi.org/10.1007/s10995-018-2486-1DOI Listing
April 2018

TOPGEAR: A Randomized, Phase III Trial of Perioperative ECF Chemotherapy with or Without Preoperative Chemoradiation for Resectable Gastric Cancer: Interim Results from an International, Intergroup Trial of the AGITG, TROG, EORTC and CCTG.

Ann Surg Oncol 2017 Aug 23;24(8):2252-2258. Epub 2017 Mar 23.

Princess Margaret Hospital, Toronto, ON, Canada.

Background: Postoperative chemoradiation and perioperative chemotherapy using epirubicin/cisplatin/5-fluorouracil (ECF) represent two standards of care for resectable gastric cancer. In the TOPGEAR (Trial Of Preoperative therapy for Gastric and Esophagogastric junction AdenocaRcinoma) trial, we hypothesized that adding preoperative chemoradiation to perioperative ECF will improve survival; however, the safety and feasibility of preoperative chemoradiation have yet to be determined.

Methods: TOPGEAR is an international phase III trial in which patients with adenocarcinoma of the stomach were randomized to perioperative ECF alone or with preoperative chemoradiation. The ECF-alone group received three preoperative cycles of ECF, while the chemoradiation group received two cycles of preoperative ECF followed by chemoradiation. Both groups received three postoperative cycles of ECF. A planned interim analysis of the first 120 patients was conducted, and was reviewed by the Independent Data Safety Monitoring Committee to assess treatment compliance, toxicity/safety, and response rates.

Results: The proportion of patients who received all cycles of preoperative chemotherapy was 93% (ECF group) and 98% (chemoradiation group), while 65 and 53%, respectively, received all cycles of postoperative chemotherapy. Overall, 92% of patients allocated to preoperative chemoradiation received this treatment. The proportion of patients proceeding to surgery was 90% (ECF group) and 85% (chemoradiation group). Grade 3 or higher surgical complications occurred in 22% of patients in both groups. Furthermore, grade 3 or higher gastrointestinal toxicity occurred in 32% (ECF group) and 30% (chemoradiation group) of patients, while hematologic toxicity occurred in 50 and 52% of patients.

Conclusions: These results demonstrate that preoperative chemoradiation can be safely delivered to the vast majority of patients without a significant increase in treatment toxicity or surgical morbidity.
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http://dx.doi.org/10.1245/s10434-017-5830-6DOI Listing
August 2017

Meeting radiation therapy patients informational needs through educational videos augmented by 3D visualisation software.

J Med Radiat Sci 2017 Mar 27;64(1):35-40. Epub 2017 Feb 27.

Department of Radiation Oncology, North West Cancer Centre, Tamworth, New South Wales, Australia.

Introduction: Misconceptions and uncertainties about radiotherapy compound the anxiety patients experience at the commencement of treatment. This project investigated the utility of locally produced treatment process videos in meeting patients' informational needs.

Methods: In-house video production was conducted on a voluntary basis by staff and patients at a regional Australian radiotherapy centre. Videos included real footage and animated sections created with PEARL 3D visualisation software (Vertual Ltd, UK) to meet specific key content objectives. Quantitative cross sectional analysis was conducted. Patients attending for simulation watched a relevant video. After their first fraction of radiotherapy they were asked to complete an ethics-reviewed questionnaire about how well the video addressed their information needs.

Results: The survey completion rate was 29% (n = 61/212). Surveys were collected over 9 months from August 2014 to April 2015. Statistical analysis found 98% of patients reported that the video was useful in meeting one or more of the learning objectives. Forty-nine percent of patients also reported a reduction in fear and anxiety as a result of watching the video. Patients reported subsequent review of videos at home (39%), primarily to explain treatment processes to loved ones (46%).

Conclusion: The combination of real footage and 3D visualisation software assisted in meeting learning objectives regarding the treatment process. Standardised videos provided consistency of information provision to patients and facilitated multiple viewings of the video if desired.
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http://dx.doi.org/10.1002/jmrs.220DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5355370PMC
March 2017

Molecular Identification of Sclerotinia trifoliorum and Sclerotinia sclerotiorum Isolates from the United States and Poland.

Plant Dis 2017 Jan 11;101(1):192-199. Epub 2016 Oct 11.

Department of Plant Pathology, University of Wisconsin-Madison, Madison 53706.

Symptoms of clover rot caused by Sclerotinia trifoliorum or S. sclerotiorum are identical, making differentiation and identification of the causal species difficult and time consuming. Polymerase chain reaction (PCR) amplification and nucleotide sequencing were used to examine 40 isolates of S. trifoliorum (29 from Poland, 11 from the United States) and 55 isolates of S. sclerotiorum (26 from Poland, 29 from the United States). We determined that amplification of the β-tubulin and calmodulin genes with TU1/TU2/TU3 and SscadF1/SscadR1 PCR primers and the presence of introns and single-nucleotide polymorphisms (SNP) within the ribosomal DNA (rDNA) as detected with NS1/NS8 and internal transcribed spacer (ITS)1/ITS4 PCR primers are effective for rapidly and accurately differentiating between the two species of Sclerotinia. In addition, our research revealed a lack of intraspecies variation within S. sclerotiorum isolates from the United States and Poland using these same molecular markers. We detected a relatively high degree of intraspecies variability among isolates of S. trifoliorum from the United States and Poland using the presence of introns and SNP within the rDNA. SNP and nuclear small-subunit rDNA analyses revealed distinct groups of S. trifoliorum among the isolates used in this study. The results of this study provide useful information for clover breeders and pathologists looking to develop clover varieties with durable resistance.
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http://dx.doi.org/10.1094/PDIS-06-16-0896-REDOI Listing
January 2017

Diguanylate Cyclases AdrA and STM1987 Regulate Salmonella enterica Exopolysaccharide Production during Plant Colonization in an Environment-Dependent Manner.

Appl Environ Microbiol 2016 02 11;82(4):1237-1248. Epub 2015 Dec 11.

Department of Plant Pathology, University of Wisconsin-Madison, Madison, Wisconsin, USA

Increasing evidence indicates that despite exposure to harsh environmental stresses, Salmonella enterica successfully persists on plants, utilizing fresh produce as a vector to animal hosts. Among the important S. enterica plant colonization factors are those involved in biofilm formation. S. enterica biofilm formation is controlled by the signaling molecule cyclic di-GMP and represents a sessile lifestyle on surfaces that protects the bacterium from environmental factors. Thus, the transition from a motile, planktonic lifestyle to a sessile lifestyle may represent a vital step in bacterial success. This study examined the mechanisms of S. enterica plant colonization, including the role of diguanylate cyclases (DGCs) and phosphodiesterases (PDEs), the enzymes involved in cyclic di-GMP metabolism. We found that two biofilm components, cellulose and curli, are differentially required at distinct stages in root colonization and that the DGC STM1987 regulates cellulose production in this environment independent of AdrA, the DGC that controls the majority of in vitro cellulose production. In addition, we identified a new function for AdrA in the transcriptional regulation of colanic acid and demonstrated that adrA and colanic acid biosynthesis are associated with S. enterica desiccation tolerance on the leaf surface. Finally, two PDEs with known roles in motility, STM1344 and STM1697, had competitive defects in the phyllosphere, suggesting that regulation of motility is crucial for S. enterica survival in this niche. Our results indicate that specific conditions influence the contribution of individual DGCs and PDEs to bacterial success, perhaps reflective of differential responses to environmental stimuli.
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http://dx.doi.org/10.1128/AEM.03475-15DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4751842PMC
February 2016

Validity of the Taylor-Sedov Theory for Studying Laser-Induced Phase Explosion and Shock Waves.

J Nanosci Nanotechnol 2015 Apr;15(4):3249-53

Phase explosion is a phase change process that occurs during short pulse laser ablation. Phase explosion is a result of homogeneous nucleation of vapor in the superheated melt and results in a rapid transition from a superheated melt to a mixture of vapor and liquid droplets that expand from the surface. The sudden phase transition results in rapid material removal, and if occurring in an ambient gas, causes a shock wave to propagate away from the surface. Measurements of this shock wave are commonly used with the Taylor-Sedov blast wave theory to estimate shock wave pressure and temperature. At low laser fluences the Mach number of the shock wave can be small, resulting in significant errors in pressure and temperature. The paper will demonstrate conditions for which the more general form of the Rankine-Hugoniot relations for thermo-fluid parameters simplifies to the Taylor-Sedov similarity solutions and when the Taylor-Sedov solutions are applicable. The results are compared to experimental shock wave data from the literature to explain why using the Taylor-Sedov blast wave solutions can result in large errors at low Mach numbers.
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http://dx.doi.org/10.1166/jnn.2015.9649DOI Listing
April 2015

Detecting initiation or risk for initiation of substance use before high school during pediatric well-child check-ups.

Drug Alcohol Depend 2015 May 2;150:54-62. Epub 2015 Mar 2.

University of Pittsburgh, Pittsburgh, PA, United States.

Background: Youth substance use (SU) is prevalent and costly, affecting mental and physical health. American Academy of Pediatrics and Affordable Care Act call for SU screening and prevention. The Youth Risk Index(©) (YRI) was tested as a screening tool for having initiated and propensity to initiate SU before high school (which forecasts SU disorder). YRI was hypothesized to have good to excellent psychometrics, feasibility and stakeholder acceptability for use during well-child check-ups.

Design: A high-risk longitudinal design with two cross-sectional replication samples, ages 9-13 was used. Analyses included receiver operating characteristics and regression analyses.

Participants: A one-year longitudinal sample (N=640) was used for YRI derivation. Replication samples were a cross-sectional sample (N=345) and well-child check-up patients (N=105) for testing feasibility, validity and acceptability as a screening tool.

Results: YRI has excellent test-retest reliability and good sensitivity and specificity for concurrent and one-year-later SU (odds ratios=7.44, CI=4.3-13.0) and conduct problems (odds ratios=7.33, CI=3.9-13.7). Results were replicated in both cross-sectional samples. Well-child patients, parents and pediatric staff rated YRI screening as important, acceptable, and a needed service.

Conclusions: Identifying at-risk youth prior to age 13 could reap years of opportunity to intervene before onset of SU disorder. Most results pertained to YRI's association with concurrent or recent past risky behaviors; further replication ought to specify its predictive validity, especially adolescent-onset risky behaviors. YRI well identifies youth at risk for SU and conduct problems prior to high school, is feasible and valid for screening during well-child check-ups, and is acceptable to stakeholders.
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http://dx.doi.org/10.1016/j.drugalcdep.2015.02.013DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4405881PMC
May 2015

Sclerotinia homoeocarpa overwinters in turfgrass and is present in commercial seed.

PLoS One 2014 21;9(10):e110897. Epub 2014 Oct 21.

Department of Plant of Plant Path Pathology, University of Wisconsin-Madison, Madison, Wisconsin, United States of America; Department of Plant Pathology, North Carolina State University, Raleigh, North Carolina, United States of America.

Dollar spot is the most economically important disease of amenity turfgrasses in the United States, yet little is known about the source of primary inoculum for this disease. With the exception of a few isolates from the United Kingdom, Sclerotinia homoeocarpa, the causal agent of dollar spot, does not produce spores. Consequently, it was assumed that overwintering of this organism in soil, thatch, and plant debris provides primary inoculum for dollar spot epidemics. Overwintering of S. homoeocarpa in roots and shoots of symptomatic and asymptomatic creeping bentgrass turfgrass was quantified over the course of a three-year field experiment. Roots did not consistently harbor S. homoeocarpa, whereas S. homoeocarpa was isolated from 30% of symptomatic shoots and 10% of asymptomatic shoots in the spring of two out of three years. The presence of stroma-like pathogen material on leaf blades was associated with an increase in S. homoeocarpa isolation and colony diameter at 48 hpi. Commercial seed has also been hypothesized to be a potential source of initial inoculum for S. homoeocarpa. Two or more commercial seed lots of six creeping bentgrass cultivars were tested for contamination with S. homoeocarpa using culture-based and molecular detection methods. A viable, pathogenic isolate of S. homoeocarpa was isolated from one commercial seed lot and contamination of this lot was confirmed with nested PCR using S. homoeocarpa specific primers. A sensitive nested PCR assay detected S. homoeocarpa contamination in eight of twelve (75%) commercial seed lots. Seed source, but not cultivar or resistance to dollar spot, influenced contamination by S. homoeocarpa. Overall, this research suggests that seeds are a potential source of initial inoculum for dollar spot epidemics and presents the need for further research in this area.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0110897PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4204931PMC
December 2015

Using technology to deliver mental health services to children and youth: a scoping review.

J Can Acad Child Adolesc Psychiatry 2014 May;23(2):87-99

TeleLink Mental Health Program, The Hospital for Sick Children, Toronto, Ontario ; The Ontario Child and Youth Telepsychiatry Program, Toronto, Ontario.

Objective: To conduct a scoping review on the use of technology to deliver mental health services to children and youth in order to identify the breadth of peer-reviewed literature, summarize findings and identify gaps.

Method: A literature database search identified 126 original studies meeting criteria for review. Descriptive numerical summary and thematic analyses were conducted. Two reviewers independently extracted data.

Results: Studies were characterized by diverse technologies including videoconferencing, telephone and mobile phone applications and Internet-based applications such as email, web sites and CD-ROMs.

Conclusion: The use of technologies plays a major role in the delivery of mental health services and supports to children and youth in providing prevention, assessment, diagnosis, counseling and treatment programs. Strategies are growing exponentially on a global basis, thus it is critical to study the impact of these technologies on child and youth mental health service delivery. An in-depth review and synthesis of the quality of findings of studies on effectiveness of the use of technologies in service delivery are also warranted. A full systematic review would provide that opportunity.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4032077PMC
May 2014

Can we predict plan quality for external beam partial breast irradiation: results of a multicenter feasibility study (Trans Tasman Radiation Oncology Group Study 06.02).

Int J Radiat Oncol Biol Phys 2013 Nov 21;87(4):817-24. Epub 2013 Sep 21.

Peter MacCallum Cancer Centre, Departments of Radiation Oncology, Physical Sciences and Radiation Therapy, Melbourne, Victoria, Australia; Sir Peter MacCallum Department of Oncology, University of Melbourne, Melbourne, Victoria, Australia; School of Science, Engineering and Technology, Royal Melbourne Institute of Technology University, Melbourne, Victoria, Australia. Electronic address:

Purpose: Partial breast irradiation (PBI) after lumpectomy may be an option for selected patients with early breast cancer. A feasibility study of accelerated PBI delivered using external beam 3-dimensional conformal radiation therapy (RT) was undertaken at 8 Australasian centers. The present study evaluated the impact of patient, tumor, and RT technique-related factors on the quality of RT plans as determined by the dose-volume parameters of organs at risk.

Methods And Materials: Forty-eight patients were enrolled in the study. All RT plans were centrally reviewed using predefined dosimetric criteria before commencement and after completion of protocol therapy. The RT plans of 47 patients met the dose-volume constraints, and all 47 patients received PBI to a prescribed dose of 38.5 Gy in 10 fractions. The RT plan quality was determined by volumes of the ipsilateral whole breast, lung, and heart that received 50% and 95%; 30%; and 5% of the prescribed dose, respectively. Patient, tumor, and RT technique-related factors were investigated for association with the parameters of RT plan quality.

Results: The ratio of the planning target volume to the ipsilateral whole-breast volume was significantly associated with the ipsilateral breast doses on multiple variable analyses. The distance of the postlumpectomy surgical cavity from the heart and lung were predictive for heart and lung doses, respectively. A distance between surgical cavity and heart of >4 cm typically resulted in <1% of the heart volume receiving 5 Gy or less. It was more difficult to meet the heart dose constraint for left-sided and medially located tumors.

Conclusions: Partial breast irradiation using 3-dimensional conformal RT was feasible within the study constraints. The ratio of planning target volume to ipsilateral whole-breast volume and the distance of surgical cavity from the heart were significant predictors of the quality of treatment plan for external beam PBI.
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http://dx.doi.org/10.1016/j.ijrobp.2013.07.036DOI Listing
November 2013

Radiotherapy of abdomen with precise renal assessment with SPECT/CT imaging (RAPRASI): design and methodology of a prospective trial to improve the understanding of kidney radiation dose response.

BMC Cancer 2013 Aug 10;13:381. Epub 2013 Aug 10.

Background: The kidneys are a principal dose-limiting organ in radiotherapy for upper abdominal cancers. The current understanding of kidney radiation dose response is rudimentary. More precise dose-volume response models that allow direct correlation of delivered radiation dose with spatio-temporal changes in kidney function may improve radiotherapy treatment planning for upper-abdominal tumours.

Methods/design: The Radiotherapy of Abdomen with Precise Renal Assessment with SPECT/CT Imaging (RAPRASI) is an observational clinical research study with participating sites at Sir Charles Gairdner Hospital (SCGH) in Perth, Australia and the Peter MacCallum Cancer Centre (PMCC) in Melbourne, Australia. Eligible patients are those with upper gastrointestinal cancer, without metastatic disease, undergoing conformal radiotherapy that will involve incidental radiation to one or both kidneys. For each patient, total kidney function is being assessed before commencement of radiotherapy treatment and then at 4, 12, 26, 52 and 78 weeks after the first radiotherapy fraction, using two procedures: a Glomerular Filtration Rate (GFR) measurement using the 51Cr-ethylenediamine tetra-acetic acid (EDTA) clearance; and a regional kidney perfusion measurement assessing renal uptake of 99mTc-dimercaptosuccinic acid (DMSA), imaged with a Single Photon Emission Computed Tomography / Computed Tomography (SPECT/CT) system. The CT component of the SPECT/CT provides the anatomical reference of the kidney's position. The data is intended to reveal changes in regional kidney function over the study period after the radiotherapy. These SPECT/CT scans, co-registered with the radiotherapy treatment plan, will provide spatial correlation between the radiation dose and regional renal function as assessed by SPECT/CT. From this correlation, renal response patterns will likely be identified with the purpose of developing a predictive model.

Trial Registration: Australian New Zealand Clinical Trials Registry: ACTRN12609000322235.
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http://dx.doi.org/10.1186/1471-2407-13-381DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3751853PMC
August 2013

The type III secreted effector DspE is required early in solanum tuberosum leaf infection by Pectobacterium carotovorum to cause cell death, and requires Wx(3-6)D/E motifs.

PLoS One 2013 3;8(6):e65534. Epub 2013 Jun 3.

Department of Plant Pathology, University of Wisconsin-Madison, Madison, Wisconsin, United States of America.

Pectobacterium species are enterobacterial plant-pathogens that cause soft rot disease in diverse plant species. Unlike hemi-biotrophic plant pathogenic bacteria, the type III secretion system (T3SS) of Pectobacterium carotovorum subsp. carotovorum (P. carotovorum) appears to secrete only one effector protein, DspE. Previously, we found that the T3SS regulator HrpL and the effector DspE are required for P. carotovorum pathogenesis on leaves. Here, we identified genes up-regulated by HrpL, visualized expression of dspE in leaves, and established that DspE causes host cell death. DspE required its full length and WxxxE-like motifs, which are characteristic of the AvrE-family effectors, for host cell death. We also examined expression in plant leaves and showed that hrpL is required for the expression of dspE and hrpN, and that the loss of a functional T3SS had unexpected effects on expression of other genes during leaf infection. These data support a model where P. carotovorum uses the T3SS early in leaf infection to initiate pathogenesis through elicitation of DspE-mediated host cell death.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0065534PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3670860PMC
January 2015

Percutaneous drainage of colonic diverticular abscess: is colon resection necessary?

Dis Colon Rectum 2013 May;56(5):622-6

Division of Colon and Rectal Surgery, Department of Surgery, University of Minnesota, Minneapolis, Minnesota 55455, USA.

Background: Recurrent diverticulitis has been reported in up to 30% to 40% of patients who recover from an episode of colonic diverticular abscess, so elective interval resection is traditionally recommended.

Objective: The aim of this study was to review the outcomes of patients who underwent percutaneous drainage of colonic diverticular abscess without subsequent operative intervention.

Design: This was an observational study.

Settings: This investigation was conducted at a tertiary care academic medical center and a single-hospital health system.

Patients: Patients treated for symptomatic colonic diverticular abscess from 2002 through 2007 were included.

Main Outcome Measures: The primary outcomes measured were complications, recurrence, and colectomy-free survival.

Results: Two hundred eighteen patients underwent percutaneous drainage of colonic diverticular abscesses. Thirty-two patients (15%) did not undergo subsequent colonic resection. Abscess location was pelvic (n = 9) and paracolic (n = 23), the mean abscess size was 4.2 cm, and the median duration of percutaneous drainage was 20 days. The comorbidities of this group of patients included severe cardiac disease (n = 16), immunodeficiency (n = 7), and severe pulmonary disease (n = 6). Freedom from recurrence at 7.4 years was 0.58 (95% CI 0.42-0.73). All recurrences were managed nonoperatively. Recurrence was significantly associated with an abscess size larger than 5 cm. Colectomy-free survival at 7.4 years was 0.17 (95% CI 0.13-0.21).

Limitations: This study was limited by its retrospective, nonexperimental design and short follow-up.

Conclusion: In selected patients, observation after percutaneous drainage of colonic diverticular abscess appears to be a safe and low-risk management option.
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http://dx.doi.org/10.1097/DCR.0b013e31828545e3DOI Listing
May 2013

Expression and mapping of anthocyanin biosynthesis genes in carrot.

Theor Appl Genet 2013 Jul 24;126(7):1689-702. Epub 2013 Mar 24.

Department of Horticulture, University of Wisconsin-Madison, 1575 Linden Drive, Madison, WI 53706, USA.

Anthocyanin gene expression has been extensively studied in leaves, fruits and flowers of numerous plants. Little, however, is known about anthocyanin accumulation in roots of carrots or other species. We quantified expression of six anthocyanin biosynthetic genes [phenylalanine ammonia-lyase (PAL3), chalcone synthase (CHS1), flavanone 3-hydroxylase (F3H), dihydroflavonol 4-reductase (DFR1), leucoanthocyanidin dioxygenase (LDOX2), and UDP-glucose:flavonoid 3-O-glucosyltransferase (UFGT)] in three carrot inbreds with contrasting root color: solid purple (phloem and xylem); purple outer phloem/orange xylem; and orange phloem and xylem. Transcripts for five of these genes (CHS1, DFR1, F3H, LDOX2, PAL3) accumulated at high levels in solid purple carrots, less in purple-orange carrot, and low or no transcript in orange carrots. Gene expression coincided with anthocyanin accumulation. In contrast, UFGT expression was comparable in purple and orange carrots and relatively unchanged during root development. In addition, five anthocyanin biosynthesis genes [FLS1 (flavonol synthase), F3H, LDOX2, PAL3, and UFGT] and three anthocyanin transcription factors (DcEFR1, DcMYB3 and DcMYB5) were mapped in a population segregating for the P 1 locus that conditions purple root color. P 1 mapped to chromosome 3 and of the eight anthocyanin biosynthesis genes, only F3H and FLS1 were linked to P 1. The gene expression and mapping data suggest a coordinated regulatory control of anthocyanin expression in carrot root and establish a framework for studying the anthocyanin pathway in carrots, and they also suggest that none of the genes evaluated is a candidate for P 1.
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http://dx.doi.org/10.1007/s00122-013-2084-yDOI Listing
July 2013

Movie making as a cognitive distraction for paediatric patients receiving radiotherapy treatment: qualitative interview study.

BMJ Open 2013 Jan 16;3(1). Epub 2013 Jan 16.

Centre for Program Evaluation, University of Melbourne, Melbourne, Victoria, Australia.

Objectives: To establish the outcomes achieved by using an innovative movie-making programme designed to reduce fear of radiotherapy among paediatric patients.

Design: Qualitative descriptive evaluation based on semistructured, qualitative interviews with purposeful sampling and thematic analysis.

Setting: Tertiary Cancer Centre.

Participants: 20 parents of paediatric patients who had produced a movie of their radiation therapy experience and were in a follow-up phase of cancer management.

Results: Participants attributed a broad range of outcomes to the movie-making program. These included that the programme had helped reduce anxiety and distress exhibited by paediatric patients and contributed to a willingness to receive treatment. Other outcomes were that the completed movies had been used in school reintegration and for maintaining social connections.

Conclusions: Allowing children to create a video of their experience of radiotherapy provided a range of benefits to paediatric patients that varied according to their needs. For some patients, movie-making offered a valuable medium for overcoming fear of the unknown as well as increasing understanding of treatment processes. For others, the development of a personalised video offered an important cognitive/attentional distraction through engaging with an age-appropriate activity. Together these outcomes helped children maintain self-control and a positive outlook.
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http://dx.doi.org/10.1136/bmjopen-2012-001666DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3549231PMC
January 2013

Adaptive radiotherapy for muscle-invasive bladder cancer: optimisation of plan sizes.

J Med Imaging Radiat Oncol 2012 Dec 12;56(6):661-7. Epub 2012 Sep 12.

Division of Radiation Oncology, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia.

Introduction: Plan-of-the-day adaptive radiotherapy (ART) that has not been optimally designed may result in inefficient plan sizes. This can lead to unused plans, which may potentially reduce overall conformality. We compared two methods of individualising ART plan sizes for muscle-invasive bladder cancer to determine which provides a more balanced distribution of plan selections.

Methods: Twenty-seven previously treated patients had small, medium and large ART plans generated from CTV contours on the simulation CT and initial cone beam CTs (CBCT). In the original clinical method, the smallest plan was based on the smallest CTV, while the experimental method used the Boolean summation of the two smallest CTVs. The large plan was identical in both methods. The medium plans were created midway between small and large CTVs. Credentialed treatment staff performed plan selection clinically for the original plans and retrospectively for the experimental plans.

Results: A total of 646 CBCTs from 26 patients were included. The small, medium and large adaptive CTVs, and the conventional CTV, were used 29.7%, 45.4%, 22.0% and 2.9% of the time, respectively, compared to the previous 9.8%, 49.2%, 39.5% and 1.5%. The differences were significant between previous and new CTV (small), and CTV (large).

Conclusions: The new design method resulted in the three adaptive CTV choices being selected more evenly, however, a reduction in a surrogate for normal tissue irradiation was not observed.
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http://dx.doi.org/10.1111/j.1754-9485.2012.02436.xDOI Listing
December 2012

The evolving role of laparoscopy in colonic diverticular disease: a systematic review.

World J Surg 2013 Mar;37(3):629-38

Division of Colon and Rectal Surgery, Department of Surgery, University of Minnesota, 420 Delaware St. SE, MMC 450, Minneapolis, MN 55455, USA.

Background: A PubMed search of the biomedical literature was carried out to systematically review the role of laparoscopy in colonic diverticular disease. All original reports comparing elective laparoscopic, hand-assisted, and open colon resection for diverticular disease of the colon, as well as original reports evaluating outcomes after laparoscopic lavage for acute diverticulitis, were considered. Of the 21 articles chosen for final review, nine evaluated laparoscopic versus open elective resection, six compared hand-assisted colon resection versus conventional laparoscopic resection, and six considered laparoscopic lavage. Five were randomized controlled trials.

Results: Elective laparoscopic colon resection for diverticular disease is associated with increased operative time, decreased postoperative pain, fewer postoperative complications, less paralytic ileus, and shorter hospital stay compared to open colectomy. Laparoscopic lavage and drainage appears to be a safe and effective therapy for selected patients with complicated diverticulitis.

Conclusions: Elective laparoscopic colectomy for diverticular disease is associated with decreased postoperative morbidity compared to open colectomy, leading to shorter hospital stay and fewer costs. Laparoscopic lavage has an increasing but poorly defined role in complicated diverticulitis.
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http://dx.doi.org/10.1007/s00268-012-1872-xDOI Listing
March 2013

A coupled kinematics-energetics model for predicting energy efficient flapping flight.

J Theor Biol 2013 Feb 16;318:173-96. Epub 2012 Oct 16.

Physics Department, University of Toronto, 60 St. George St., Toronto, Ontario, Canada M5S 1A7.

A new computational model based on an optimal power, wake-only aerodynamics method is presented to predict the interdependency of energetics and kinematics in bird and bat flight. The model is divided into offline, intermediate and online modules. In the offline module, a four-dimensional design space sweep is performed (lift, thrust, flapping amplitude and flapping frequency). In the intermediate stage, the physical characteristics of the animal are introduced (wing span, mass, wing area, aspect ratio, etc.), and a series of amplitude-frequency response surfaces are constructed for all viable flight speeds. In the online component, the amplitude-frequency response surfaces are mined for the specific flapping motions being considered. The method is applied to several biological examples including a medium sized fruit bat (Cynopterus brachyotis), and two birds: a thrush nightingale (Luscinia luscinia) and a budgerigar (Melopsittacus undulatus). For each of these animals, the power and kinematics predictions are compared with available experimental data. These examples demonstrate that this new method can reasonably predict animal flight energetics and kinematics.
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http://dx.doi.org/10.1016/j.jtbi.2012.10.008DOI Listing
February 2013

Copy number variation of multiple genes at Rhg1 mediates nematode resistance in soybean.

Science 2012 Nov 11;338(6111):1206-9. Epub 2012 Oct 11.

Department of Plant Pathology, University of Wisconsin, Madison, WI 53706, USA.

The rhg1-b allele of soybean is widely used for resistance against soybean cyst nematode (SCN), the most economically damaging pathogen of soybeans in the United States. Gene silencing showed that genes in a 31-kilobase segment at rhg1-b, encoding an amino acid transporter, an α-SNAP protein, and a WI12 (wound-inducible domain) protein, each contribute to resistance. There is one copy of the 31-kilobase segment per haploid genome in susceptible varieties, but 10 tandem copies are present in an rhg1-b haplotype. Overexpression of the individual genes in roots was ineffective, but overexpression of the genes together conferred enhanced SCN resistance. Hence, SCN resistance mediated by the soybean quantitative trait locus Rhg1 is conferred by copy number variation that increases the expression of a set of dissimilar genes in a repeated multigene segment.
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http://dx.doi.org/10.1126/science.1228746DOI Listing
November 2012

Effect of self-selected music on adults' anxiety and subjective experiences during initial radiotherapy treatment: a randomised controlled trial and qualitative research.

J Med Imaging Radiat Oncol 2012 Aug 28;56(4):473-7. Epub 2012 May 28.

Peter MacCallum Cancer Centre The University of Melbourne, Melbourne, Victoria, Australia.

Introduction: Patients may experience radiotherapy as anxiety provoking, especially during unfamiliar initial treatment. This study examines whether patients' use of self-selected music while undergoing first radiotherapy treatment reduces anxiety, and how patients describe their first radiotherapy experience with or without self-selected music.

Methods: Using quantitative and qualitative methods, 100 participants preparing to commence radiotherapy were assigned to the initial radiotherapy session either with self-selected music or without music. In both participant groups, the Spielberger State Anxiety Inventory measured pre- and post-radiotherapy levels, music preference questions examined future music desires during treatment and a semistructured questionnaire examined additional subjective experiences.

Results: Overall, participants were not highly anxious pre-radiotherapy, anxiety decreased in both music and control groups following radiotherapy (P = 0.008) and this change was not different between groups (P = 0.35). However, music group participants were significantly more likely to want music in future radiotherapy sessions (P = 0.007). Some reported a benefit from the music in terms of feeling supported, distracted or that treatment time seemed faster. Participants in both groups often commended helpful staff. Negative reactions were only occasional.

Conclusions: Although preferred music does not reduce anxiety, it can support some patients undergoing initial radiotherapy and departmental staff should invite patients to bring music to radiotherapy, provide music libraries and offer to play patient selected music during treatments.
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http://dx.doi.org/10.1111/j.1754-9485.2012.02395.xDOI Listing
August 2012

Target localisation for tumour bed radiotherapy in early breast cancer.

J Med Imaging Radiat Oncol 2012 Aug;56(4):452-7

Department of Radiation Oncology Radiation Therapy Service, East Melbourne University of Melbourne, Melbourne, Victoria, Australia.

Introduction: To compare clinical and CT techniques in localisation of the tumour bed in patients undergoing adjuvant breast radiotherapy for breast cancer.

Methods: Patients were CT scanned in the treatment position following clinical delineation of the whole breast, surgical scar and boost volume. Computed tomography boost volumes were contoured in three dimensions. A definitive treatment plan was generated to encompass the CT-localised planning target volume (PTV) with ≥90% isodose using electrons. A hypothetical plan was also generated to cover the clinically determined boost field for comparison. The primary end point was the difference in PTV coverage by the 90% isodose between the plans based on clinically and CT localised boost volumes.

Results: The plans for 50 patients were evaluated. The median percentage of PTV encompassed by the 90% isodose using the clinical and CT techniques was 29% (range 5-90%) and 83% (range 25-100%), respectively. PTV coverage by the 90% isodose using the clinical technique was at least 10% less than that using CT technique in 88% of patients (95% confidence interval 77-95%; P < 0.0001).

Conclusion: Tumour bed boost PTV coverage was insufficient using clinical determination as compared with CT localisation. This study supports CT planning for target volume localisation of the tumour bed boost in patients treated with breast-conserving therapy for breast cancer.
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http://dx.doi.org/10.1111/j.1754-9485.2012.02380.xDOI Listing
August 2012

Out-of-hospital cardiac arrest in Cork, Ireland.

Emerg Med J 2013 Jun 15;30(6):496-500. Epub 2012 Jun 15.

National Ambulance Service, HSE Southern Region, South Link Road, Cork, Ireland.

Background: Out-of-hospital cardiac arrest (OHCA) in Ireland accounts for approximately 5000 deaths annually. Little published evidence exists on survival from OHCA in this country to date. We aimed to characterise and describe 'presumed cardiac' OHCA in Cork City and County attended by the Ambulance Service.

Methods: Dispatch records, ambulance patient records and hospital records for a 1-year period were examined for patient demographics, OHCA characteristics, interventions and patient outcomes.

Results: There were 231 'presumed cardiac' OHCAs attended over the study period; 130 (56%) were in urban locations and 101 (44%) in rural. OHCAs were lay-witnessed in 20% (n=46), and 22% (n=50) received bystander CPR. Shockable rhythm was present in 36 cases (16%) on initial assessment, and there was no difference in presence of shockable rhythm between urban and rural OHCAs (18% vs 13%, p=0.31). Resuscitation was attempted in 176 cases (77.5%), of whom 27 (15%) achieved return of spontaneous circulation and 13 (7.4%) survived to leave hospital. Survival when the initial rhythm was shockable was 16.7% (6 of 36 patients). Despite longer response times for rural compared with urban OHCAs (median (IQR) 16.5 (11.0-23.5) vs 9 (7-12) min, p<0.001), survival to leave hospital alive where resuscitation was attempted was similar (7.4% vs 7.4%, p=0.99, respectively).

Conclusion: A survival rate of 16.7% in shockable rhythms indicates scope for improvement which would influence the overall survival rate which was found to be 7.4%. Real-time feedback of performance and quality of the continuum of patient care through a clinical-quality cardiac arrest registry would monitor and incentivise such initiatives.
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http://dx.doi.org/10.1136/emermed-2011-200888DOI Listing
June 2013

Requirement of siderophore biosynthesis for plant colonization by Salmonella enterica.

Appl Environ Microbiol 2012 Jul 20;78(13):4561-70. Epub 2012 Apr 20.

Department of Plant Pathology, University of Wisconsin-Madison, USA.

Contaminated fresh produce has become the number one vector of nontyphoidal salmonellosis to humans. However, Salmonella enterica genes essential for the life cycle of the organism outside the mammalian host are for the most part unknown. Screening deletion mutants led to the discovery that an aroA mutant had a significant root colonization defect due to a failure to replicate. AroA is part of the chorismic acid biosynthesis pathway, a central metabolic node involved in aromatic amino acid and siderophore production. Addition of tryptophan or phenylalanine to alfalfa root exudates did not restore aroA mutant replication. However, addition of ferrous sulfate restored replication of the aroA mutant, as well as alfalfa colonization. Tryptophan and phenylalanine auxotrophs had minor plant colonization defects, suggesting that suboptimal concentrations of these amino acids in root exudates were not major limiting factors for Salmonella replication. An entB mutant defective in siderophore biosynthesis had colonization and growth defects similar to those of the aroA mutant, and the defective phenotype was complemented by the addition of ferrous sulfate. Biosynthetic genes of each Salmonella siderophore, enterobactin and salmochelin, were upregulated in alfalfa root exudates, yet only enterobactin was sufficient for plant survival and persistence. Similar results in lettuce leaves indicate that siderophore biosynthesis is a widespread or perhaps universal plant colonization fitness factor for Salmonella, unlike phytobacterial pathogens, such as Pseudomonas and Xanthomonas.
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http://dx.doi.org/10.1128/AEM.07867-11DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3370490PMC
July 2012

The 3-hydroxy-2-butanone pathway is required for Pectobacterium carotovorum pathogenesis.

PLoS One 2011 18;6(8):e22974. Epub 2011 Aug 18.

Department of Plant Pathology, University of Wisconsin-Madison, Madison, Wisconsin, United States of America.

Pectobacterium species are necrotrophic bacterial pathogens that cause soft rot diseases in potatoes and several other crops worldwide. Gene expression data identified Pectobacterium carotovorum subsp. carotovorum budB, which encodes the α-acetolactate synthase enzyme in the 2,3-butanediol pathway, as more highly expressed in potato tubers than potato stems. This pathway is of interest because volatiles produced by the 2,3-butanediol pathway have been shown to act as plant growth promoting molecules, insect attractants, and, in other bacterial species, affect virulence and fitness. Disruption of the 2,3-butanediol pathway reduced virulence of P. c. subsp. carotovorum WPP14 on potato tubers and impaired alkalinization of growth medium and potato tubers under anaerobic conditions. Alkalinization of the milieu via this pathway may aid in plant cell maceration since Pectobacterium pectate lyases are most active at alkaline pH.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0022974PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3158072PMC
December 2011

Impact of MLC leaf width on the quality of the dose distribution in partial breast irradiation.

Med Dosim 2012 8;37(1):37-41. Epub 2011 Jul 8.

Radiation Therapy Services, Peter MacCallum Cancer Centre, St. Andrew's Place, East Melbourne, Victoria 3002, Australia.

Partial-breast irradiation (PBI) aims to limit the target volume for radiotherapy in women with early breast cancer after partial mastectomy to the region at highest risk of local recurrence, the tumor bed. Multileaf collimators are used to achieve conformal radiation beam portals required for PBI. Narrower leaf widths are generally assumed to allow more conformal shaping of beam portals around irregularly shaped target volumes. The aim was to compare 5-mm and 10-mm leaf widths for patients previously treated using PBI and assess subsequent planning target volume (PTV) coverage and organ at risk (OAR) doses for 16 patients. Several plans (5-mm leaf width or 10-mm leaf width) were generated for each patient using the original treated plan as the basis for attempts at further optimization. Alternating between different leaf widths found no significant difference in terms of overall PTV coverage and OAR doses between treatment plans. Optimization of the original treated plan allowed a small decrease in ipsilateral breast dose, which was offset by a lower PTV minimum. No significant dosimetric difference was found to support an advantage of 5-mm over 10-mm leaf width in this setting.
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http://dx.doi.org/10.1016/j.meddos.2010.12.011DOI Listing
June 2012
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