Preparation and Characterizations of Chitosan/Citral Nanoemulsions and their Antimicrobial Activity

Background and Objective: The antimicrobial activity of essential oils has been long recognized, however, they easily evaporate and/or decompose during preparation, owing to direct exposure to heat, pressure and light. The current study deals with the formulation and characterization of bio-based oil in water nanoemulsions and their antimicrobial activity against plant pathogens.Material and Methods: Citral oil and low molecular weight chitosan were used for preparation of nanoemulsions in the presence of sodium tripolyphosphate. Nanoemulsions were prepared by adding dropwise citral at different ratios into an aqueous solution containing chitosan, sodium tripolyphosphate and surfactant with continuous stirring and then ultrasonication. The success of formulation was confirmed by dynamic light scattering and scanning electron microscopy techniques. Physical stability and viscosity were investigated in details. The antimicrobial activity was evaluated against Erwinia carotovora, Aspergillus niger and Rhizopus stolonifer. Results and Conclusion: The nanoemulsions had a polydispersity index ranged from 0.508 to 0.614 and particle size from 27 to 1283 nm. The highest antimicrobial activity was observed with F1 formulation (EC50 = 23, 278 and 221 mg L-1, against Erwinia carotovora, Aspergillus niger and Rhizopus stolonifer, respectively). Based on the antimicrobial activity, the prepared chitosan/citral nanoemulsions can be a cost-effective way to protect crops from microbial pathogens. Because such formulations contain bioactive products, the development of resistant pathogens can be delayed.Conflict of Interest: The authors declare no conflict of interest.

Large expert-curated database for benchmarking document similarity detection in biomedical literature search

Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe

Burnout among surgeons before and during the SARS-CoV-2 pandemic: an international survey

Background: SARS-CoV-2 pandemic has had many significant impacts within the surgical realm, and surgeons have been obligated to reconsider almost every aspect of daily clinical practice. Methods: This is a cross-sectional study reported in compliance with the CHERRIES guidelines and conducted through an online platform from June 14th to July 15th, 2020. The primary outcome was the burden of burnout during the pandemic indicated by the validated Shirom-Melamed Burnout Measure. Results: Nine hundred fifty-four surgeons completed the survey. The median length of practice was 10 years; 78.2% included were male with a median age of 37 years old, 39.5% were consultants, 68.9% were general surgeons, and 55.7% were affiliated with an academic institution. Overall, there was a significant increase in the mean burnout score during the pandemic; longer years of practice and older age were significantly associated with less burnout. There were significant reductions in the median number of outpatient visits, operated cases, on-call hours, emergency visits, and research work, so, 48.2% of respondents felt that the training resources were insufficient. The majority (81.3%) of respondents reported that their hospitals were included in the management of COVID-19, 66.5% felt their roles had been minimized; 41% were asked to assist in non-surgical medical practices, and 37.6% of respondents were included in COVID-19 management. Conclusions: There was a significant burnout among trainees. Almost all aspects of clinical and research activities were affected with a significant reduction in the volume of research, outpatient clinic visits, surgical procedures, on-call hours, and emergency cases hindering the training. Trial registration: The study was registered on clicaltrials.gov "NCT04433286" on 16/06/2020

Retrospective evaluation of whole exome and genome mutation calls in 746 cancer samples

Funder: NCI U24CA211006Abstract: The Cancer Genome Atlas (TCGA) and International Cancer Genome Consortium (ICGC) curated consensus somatic mutation calls using whole exome sequencing (WES) and whole genome sequencing (WGS), respectively. Here, as part of the ICGC/TCGA Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium, which aggregated whole genome sequencing data from 2,658 cancers across 38 tumour types, we compare WES and WGS side-by-side from 746 TCGA samples, finding that ~80% of mutations overlap in covered exonic regions. We estimate that low variant allele fraction (VAF < 15%) and clonal heterogeneity contribute up to 68% of private WGS mutations and 71% of private WES mutations. We observe that ~30% of private WGS mutations trace to mutations identified by a single variant caller in WES consensus efforts. WGS captures both ~50% more variation in exonic regions and un-observed mutations in loci with variable GC-content. Together, our analysis highlights technological divergences between two reproducible somatic variant detection efforts

Toxicity and biochemical changes in the honey bee Apis mellifera exposed to four insecticides under laboratory conditions

International audienceThe toxicity and biochemical changes in honey bees (Apis mellifera) treated with four insecticides—acetamiprid, dinotefuran, pymetrozine, and pyridalyl—were evaluated under controlled laboratory conditions. Foraging bees were exposed to different dosages of tested insecticides by oral feeding at different dosages recommended by the manufacturers for agricultural crops in Egypt (0.01-, 0.02-, 0.04-, 0.1-, and onefold). Moreover, the acute toxicity of these insecticides was evaluated by topical application on the thorax of foragers to calculate the LD50 values. The specific activities of acetylcholinesterase (AChE), carboxylesterase, glutathione S-transferase (GST), and polyphenol oxidase (PPO) were measured in different tissues of surviving foragers after 24 h of treatment to explore the possible mode of action of insecticides and honey bees' strategies for detoxification and tolerance. The results indicated that regardless of how the bees were exposed to insecticides, dinotefuran was extremely toxic to adult A. mellifera (topical LD50 = 0.0006 μg/bee and oral feeding LC50 = 1.29 mg/L). Pyridalyl showed moderate toxicity compared to dinotefuran at the recommended application rate; however, acetamiprid and pymetrozine were relatively less toxic to bees (<25 % mortality at the recommended application rates). Data showed that tested insecticides varied in their influence on AChE, carboxylesterase, GST, and PPO activities that were highly correlated to their toxicity against A. mellifera. The biochemical analysis of carboxylesterase and GST showed that these enzymes detoxified the low doses of acetamiprid, pymetrozine, and pyridalyl, but not dinotefuran. Overall, our results are valuable not only in evaluating the toxicity of common insecticides onto honey bees, but also in highlighting the validity of enzymes activities as proper indicators for exposure to agrochemicals