Actinobacteria vs. Fusarium : battle of the toxins

Fusarium Head Blight (FHB) is a devastating disease in small-grain cereal, caused by the FHB species complex. Next to yield losses and deteriorated quality, the production of mycotoxins are a serious concern that challenges the global food chain. In a search for alternative methods to control mycotoxins in food and feed, the industry now turns to bacterial inoculants that prevent infection by toxigenic fungi, intervene when crops are being infected or remediate mycotoxin contaminated commodities. Actinobacteria harbour great potential for biocontrol and antifungal activity. In this study, 43 Rhodococcus spp. and 10 Streptomyces spp. were screened for their antifungal activity towards Fusarium graminearum, one of the most important species within the FHB species complex. After a preliminary study using a dual culture plate assay, strains that caused growth inhibition of the fungus were selected for further analysis. Remarkably, three S. rimosus strains caused complete growth inhibition, without any contact front. All three strains also significantly lowered the virulence of the GFP-tagged F. graminearum when applied on detached leaves and inhibited perithecia formation on wheat stubble. The S. rimosus strains were checked for the degradation and detoxification of two Fusarium mycotoxins: zearalenone (ZEN), produced as a defence mechanism, and deoxynivalenol (DON), an important virulence factor in FHB. All three strains showed 100% degradation and detoxification of ZEN. Results for DON degradation are currenlty being investigated. Degradation of these mycotoxins can not only give information regarding (one of multiple) biocontrol mechanisms, but also render the strains dual mode-of-action agents

Microbial detoxification of deoxynivalenol (DON), assessed via a Lemna minor L. bioassay, through biotransformation to 3-epi-DON and 3-epi-DOM-1

Mycotoxins are toxic metabolites produced by fungi. To mitigate mycotoxins in food or feed, biotransformation is an emerging technology in which microorganisms degrade toxins into non-toxic metabolites. To monitor deoxynivalenol (DON) biotransformation, analytical tools such as ELISA and liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) are typically used. However, these techniques do not give a decisive answer about the remaining toxicity of possible biotransformation products. Hence, a bioassay using Lemna minor L. was developed. A dose-response analysis revealed significant inhibition in the growth of L. minor exposed to DON concentrations of 0.25 mg/L and higher. Concentrations above 1 mg/L were lethal for the plant. This bioassay is far more sensitive than previously described systems. The bioassay was implemented to screen microbial enrichment cultures, originating from rumen fluid, soil, digestate and activated sludge, on their biotransformation and detoxification capability of DON. The enrichment cultures originating from soil and activated sludge were capable of detoxifying and degrading 5 and 50 mg/L DON. In addition, the metabolites 3-epi-DON and the epimer of de-epoxy-DON (3-epi-DOM-1) were found as biotransformation products of both consortia. Our work provides a new valuable tool to screen microbial cultures for their detoxification capacity

Global Retinoblastoma Presentation and Analysis by National Income Level.

Importance: Early diagnosis of retinoblastoma, the most common intraocular cancer, can save both a child's life and vision. However, anecdotal evidence suggests that many children across the world are diagnosed late. To our knowledge, the clinical presentation of retinoblastoma has never been assessed on a global scale. Objectives: To report the retinoblastoma stage at diagnosis in patients across the world during a single year, to investigate associations between clinical variables and national income level, and to investigate risk factors for advanced disease at diagnosis. Design, Setting, and Participants: A total of 278 retinoblastoma treatment centers were recruited from June 2017 through December 2018 to participate in a cross-sectional analysis of treatment-naive patients with retinoblastoma who were diagnosed in 2017. Main Outcomes and Measures: Age at presentation, proportion of familial history of retinoblastoma, and tumor stage and metastasis. Results: The cohort included 4351 new patients from 153 countries; the median age at diagnosis was 30.5 (interquartile range, 18.3-45.9) months, and 1976 patients (45.4%) were female. Most patients (n = 3685 [84.7%]) were from low- and middle-income countries (LMICs). Globally, the most common indication for referral was leukocoria (n = 2638 [62.8%]), followed by strabismus (n = 429 [10.2%]) and proptosis (n = 309 [7.4%]). Patients from high-income countries (HICs) were diagnosed at a median age of 14.1 months, with 656 of 666 (98.5%) patients having intraocular retinoblastoma and 2 (0.3%) having metastasis. Patients from low-income countries were diagnosed at a median age of 30.5 months, with 256 of 521 (49.1%) having extraocular retinoblastoma and 94 of 498 (18.9%) having metastasis. Lower national income level was associated with older presentation age, higher proportion of locally advanced disease and distant metastasis, and smaller proportion of familial history of retinoblastoma. Advanced disease at diagnosis was more common in LMICs even after adjusting for age (odds ratio for low-income countries vs upper-middle-income countries and HICs, 17.92 [95% CI, 12.94-24.80], and for lower-middle-income countries vs upper-middle-income countries and HICs, 5.74 [95% CI, 4.30-7.68]). Conclusions and Relevance: This study is estimated to have included more than half of all new retinoblastoma cases worldwide in 2017. Children from LMICs, where the main global retinoblastoma burden lies, presented at an older age with more advanced disease and demonstrated a smaller proportion of familial history of retinoblastoma, likely because many do not reach a childbearing age. Given that retinoblastoma is curable, these data are concerning and mandate intervention at national and international levels. Further studies are needed to investigate factors, other than age at presentation, that may be associated with advanced disease in LMICs

Microbial degradation of zearalenone by Actinobacteria : mind the toxicity

Mycotoxins are a worldwide problem that continues to challenge the whole food chain. An integrated crop protection system is needed to sufficiently manage fungal and mycotoxin contamination. Microbial and enzyme-based detoxification of contaminated food and feed is a promising bioremediation technique and has many advantages over the use of chemical treatments or physical binding agents. Actinobacteria are known to display a wide catabolic versatility for degradation of several environmental aromatic pollutants, including structurally related mycotoxins. In this research, a collection of Streptomyces sp. and Rhodococcus sp. is screened for the detoxification of zearalenone (ZEN), a non-steroidal estrogen harbouring a benzene ring. Degradation experiments were carried out in rich growth medium containing 5 mg/L ZEN during 72 hours. Microbial degradation was monitored through HPLC-FLD and confirmed through LC-MS/MS, whereas microbial detoxification is monitored through the BLYES assay which determines the estrogenic properties of possible metabolites. Screening of the Actinobacteria showed many strains capable of degrading ZEN, with degradation up to 91,20 % under the used experimental conditions. Remarkably, these high degradation rates coincided with both a significant decrease (-97,96%) and increase (+42,4%) in estrogenic properties of the resulting culture medium, highlighting the importance of toxicity monitoring in the screening process. Through a poly-omics approach combined with toxicity screening, we hope to unravel the degradation pathway of ZEN by the most performant strains and to depict which steps are crucial for detoxification

Remediation in an agroecosystem : microbial detoxification of deoxynivalenol

Mycotoxins are secondary metabolites produced by fungi. When these fungi are present on agricultural commodities, they can pose a high risk to animal and human health. As the European Commission imposes strict regulations on maximum levels of several mycotoxins, it is a prerequisite for farmers to meet these regulations to avoid complete loss of a contaminated batch. In an agro-ecosystem, farmers try to avoid fungal infection and the occurrence of mycotoxins in their commodities via prevention and intervention approaches, but often fail in completely eliminating the risk. Therefore, detoxification strategies are needed such as the use of binders or microorganisms able to detoxify these mycotoxins. Our project focuses on the microbial detoxification of deoxynivalenol (DON), a worldwide prevalent mycotoxin. Bacteria were screened from natural environments for their DON-detoxification capacity in minimal medium through HPLC-UV and non-targeted LC-MS/MS. Furthermore, the residual toxicity was measured with a bioassay using the aquatic bio-indicator plant Lemna minor. Pursuing this approach, two mixed cultures were obtained, originating from soil and activated sludge, capable of converting DON into the epimer of DON and the epimer of DOM-1, both conveying no residual toxicity for the Lemna minor plant

Cardiac isomerism : a 20 year retrospective cohort at a single institution

Cardiac isomerism or ‘isomerism of the atrial appendage’ is found in about 0,4-2% of congenital heart defects and is associated with a complex spectrum of anomalies. We reviewed isomerism cases from the last 20 years at a single institution. Methods Retrospective review of 48 patient records (Jan 2000-Dec 2020). Case selection was based on echocardiographic findings suggesting cardiac isomerism. Definitive diagnosis was made post-mortem or peri-operatively by identifying symmetrical morphological left or right atrial appendages. Results Left atrial isomerism (LAI) was diagnosed in 24 (10 confirmed), right atrial isomerism (RAI) in 24 cases (18 confirmed). Prenatal diagnosis was made in 33 cases (17 LAI; 16 RAI). Unconfirmed cases consist of 5 terminations of pregnancy were no autopsy was performed and 15 live-born patients who did not undergo cardiac surgery or autopsy. In LAI, 21 cases (87,5%) have anomalous systemic venous return, being the only cardiovascular abnormality present in 10 patients. Conduction or rhythm abnormalities were present in 11 cases (45,8%). In RAI, only complex univentricular heart defects were found with a large proportion of AVSD, transposition of the great arteries and pulmonary stenosis/atresia. Splenic function is disturbed in 86% of all live-born patients. While other extra-cardiac defects are more incidental, malrotation is more prevalent in this cohort (>10%) than in the general population. After exclusion of termination of pregnancy (n=11) and patients lost to follow-up (n=2), overall survival for isomerism patients is 60%, with a median time to follow-up of 9y. Compared to RAI, survival rates in patients with LAI are much higher: 84% (median follow-up 6y) compared to 31% (median follow-up 12ys). However, for those LAI patients that need univentricular palliation (n=3), survival rates are low (33%) and similar to RAI. Main causes of death are primary cardiac failure, abstinence of life-prolonging care and severe sepsis. Conclusion Survival rates for patients with cardiac isomerism are low for those who need univentricular palliation. These results can be used when counseling parents. Additional pathology like (functional) asplenia and malrotation add to the burden of disease

Observer training for computer-aided detection of pulmonary nodules in chest radiography

Item does not contain fulltextTo assess whether short-term feedback helps readers to increase their performance using computer-aided detection (CAD) for nodule detection in chest radiography.The 140 CXRs (56 with a solitary CT-proven nodules and 84 negative controls) were divided into four subsets of 35; each were read in a different order by six readers. Lesion presence, location and diagnostic confidence were scored without and with CAD (IQQA-Chest, EDDA Technology) as second reader. Readers received individual feedback after each subset. Sensitivity, specificity and area under the receiver-operating characteristics curve (AUC) were calculated for readings with and without CAD with respect to change over time and impact of CAD.CAD stand-alone sensitivity was 59 \% with 1.9 false-positives per image. Mean AUC slightly increased over time with and without CAD (0.78 vs. 0.84 with and 0.76 vs. 0.82 without CAD) but differences did not reach significance. The sensitivity increased (65 \% vs. 70 \% and 66 \% vs. 70 \%) and specificity decreased over time (79 \% vs. 74 \% and 80 \% vs. 77 \%) but no significant impact of CAD was found.Short-term feedback does not increase the ability of readers to differentiate true- from false-positive candidate lesions and to use CAD more effectively.• Computer-aided detection (CAD) is increasingly used as an adjunct for many radiological techniques. • Short-term feedback does not improve reader performance with CAD in chest radiography. • Differentiation between true- and false-positive CAD for low conspicious possible lesions proves difficult. • CAD can potentially increase reader performance for nodule detection in chest radiography