Beyond chemicals: Opportunities and challenges of integrating non-chemical stressors in adverse outcome pathways

The adverse outcome pathways (AOPs) were developed to accelerate evidence-based chemical risk assessment by leveraging data from new approach methodologies. Thanks to their stressor-agnostic approach, AOPs were seen as instrumental in other fields. Here, we present AOPs that report non-chemical stressors along with the challenges encountered for their development. Challenges regarding AOPs linked to nanomaterials include non-specific molecular initiating events, limited understanding of nanomaterial biodistribution, and needs for adaptations of the in silico modeling and testing systems. Development of AOPs for radiation face challenges in how to incorporate ionizing events type, dose rate, energy deposition, and how to account for targeting multiple macromolecules. AOPs for COVID-19 required the inclusion of SARS-CoV-2-specific replicative steps to capture the essential events driving the disease. Developing AOPs to evaluate efficacy and toxicity of cell therapies necessitates addressing the cellular nature and the therapeutic function of the stressor. Finally, addressing toxicity of emerging biological stressors like microbial pesticides can learn from COVID-19 AOPs. We further discuss that the adaptations needed to expand AOP applicability beyond chemicals are mainly at the molecular and cellular levels while downstream key events at tissue or organ level, such as inflammation, are shared by many AOPs initiated by various stressors. In conclusion, although it is challenging to integrate non-chemical stressors within AOPs, this expands opportunities to account for real-world scenarios, to identify vulnerable individuals, and to bridge knowledge on mechanisms of adversity.

Gut as an Alternative Entry Route for SARS-CoV-2: Current Evidence and Uncertainties of Productive Enteric Infection in COVID-19

The gut has been proposed as a potential alternative entry route for SARS-CoV-2. This was mainly based on the high levels of SARS-CoV-2 receptor expressed in the gastrointestinal (GI) tract, the observations of GI disorders (such as diarrhea) in some COVID-19 patients and the detection of SARS-CoV-2 RNA in feces. However, the underlying mechanisms remain poorly understood. It has been proposed that SARS-CoV-2 can productively infect enterocytes, damaging the intestinal barrier and contributing to inflammatory response, which might lead to GI manifestations, including diarrhea. Here, we report a methodological approach to assess the evidence supporting the sequence of events driving SARS-CoV-2 enteric infection up to gut adverse outcomes. Exploring evidence permits to highlight knowledge gaps and current inconsistencies in the literature and to guide further research. Based on the current insights on SARS-CoV-2 intestinal infection and transmission, we then discuss the potential implication on clinical practice, including on long COVID. A better understanding of the GI implication in COVID-19 is still needed to improve disease management and could help identify innovative therapies or preventive actions targeting the GI tract.

Mechanisms Leading to Gut Dysbiosis in COVID-19: Current Evidence and Uncertainties Based on Adverse Outcome Pathways

Alteration in gut microbiota has been associated with COVID-19. However, the underlying mechanisms remain poorly understood. Here, we outlined three potential interconnected mechanistic pathways leading to gut dysbiosis as an adverse outcome following SARS-CoV-2 presence in the gastrointestinal tract. Evidence from the literature and current uncertainties are reported for each step of the different pathways. One pathway investigates evidence that intestinal infection by SARS-CoV-2 inducing intestinal inflammation alters the gut microbiota. Another pathway links the binding of viral S protein to angiotensin-converting enzyme 2 (ACE2) to the dysregulation of this receptor, essential in intestinal homeostasis-notably for amino acid metabolism-leading to gut dysbiosis. Additionally, SARS-CoV-2 could induce gut dysbiosis by infecting intestinal bacteria. Assessing current evidence within the Adverse Outcome Pathway framework justifies confidence in the proposed mechanisms to support disease management and permits the identification of inconsistencies and knowledge gaps to orient further research.

Off-pump versus on-pump coronary artery bypass grafting: a propensity score-matching analysis of safety and long-term results

Background

The role and the indications for using off-pump coronary artery bypass surgery (OPCAB), instead of the traditional on-pump (ONCAB), is still to be addressed.

Aim

To describe our centre experience and to compare 15-years survival and early safety outcomes between OPCAB and ONCAB.

Methods

Single-centre retrospective cohort including 9-years of isolated first CABG (2005–2013). Multi-vessel disease with at least 2 surgical grafts patients were considered and the first 50 surgeries of each surgeon with each technique were excluded to account for the learning curve effect. Emergent surgeries and on-pump beating heart procedures were also excluded. A propensity-score matching (PSM) analysis was performed to balance groups and both survival and early outcomes comparison was done within the matched cohort using Kaplan-Meier or Cox stratified and paired tests, respectively. The median follow-up was 9 years, maximum 15 years.

Results

From 3012 multi-vessel patients with at least 2 surgical grafts, 2503 were included at the main analysis: 1487 ONCAB and 1016 OPCAB. ONCAB patients presented more frequently 3-vessels disease and left ventricular dysfunction, but received similar number of grafts than OPCAB, who in turn, received more frequently multiple arterial grafts. The surgical completeness of revascularization (CR) was similar, but hybrid procedures were more frequent in OPCAB raising CR rate in this group. After PSM (646 pairs), both groups were similar regarding pre and peri-operative characteristics. The long-term survival was similar (HR stratified by pair: 1.02 (0.81–1.30), but OPCAB evidenced benefits at early term results including bleeding, postoperative atrial fibrillation and stroke incidence.

Conclusion

At our centre, OPCAB performed by experienced surgeons provides rates of complete revascularization and long-term survival similar to ONCAB. In-hospital results favoured OPCAB.

Funding Acknowledgement

Type of funding sources: Other. Main funding source(s): Universidade do Porto/FMUP; Social European Fund; FCT-Fundação para a Ciência e a Tecnologia

Nuclear export of influenza A virus mRNAs requires ongoing RNA polymerase II activity

Influenza A virus transcribes its segmented negative sense RNA genome in the nuclei of infected cells in a process long known to require host RNA polymerase II (RNAP-II). RNA polymerase II synthesizes pre-mRNAs whose 5'-cap structures are scavenged by the viral RNA-dependent RNA polymerase during synthesis of viral mRNAs. Drugs that inhibit RNAP-II therefore block viral replication, but not necessarily solely by denying the viral polymerase a source of cap-donor molecules. We show here that 5,6-dichloro-1-beta-D-ribofuranosyl-benzimidazole (DRB), a compound that prevents processive transcription by RNAP-II, inhibits expression of the viral HA, M1 and NS1 genes at the post-transcriptional level. Abundant quantities of functionally and structurally intact viral mRNAs are made in the presence of DRB but with the exception of NP and NS2 mRNAs, are not efficiently translated. Taking M1 and NP mRNAs as representatives of DRB-sensitive and insensitive mRNAs, respectively, we found that the block to translation operates at the level of nuclear export. Furthermore, removal of DRB reversed this block unless a variety of chemically and mechanistically distinct RNAP-II inhibitors were added instead. We conclude that influenza A virus replication requires RNAP-II activity not just to provide capped mRNA substrates but also to facilitate nuclear export of selected viral mRNAs.

Bioavailability and toxicokinetics of (14)C-lindane (gamma-HCH) in the enchytraeid Enchytraeus albidus in two soil types: the aging effect

Enchytraeids are important members of the soil fauna living in the true soil layer instead of the humus like most earthworms, resulting in a different interaction with chemicals in soil. It is well known that the detectable concentration of contaminants in the soil cannot fully predict a biological effect; therefore bioaccumulation studies are of great importance. In this study the bioaccumulation pattern of the pesticide lindane ([(14)C]gamma-HCH) in Enchytraeus albidus was analyzed in two different soil types, an artificial Organisation for Economic Co-operation and Development (OECD) soil and a natural agricultural soil. The effect of aging on bioaccumulation and bioavailability was also analyzed. Aging experiments consisted of having the same procedures at different times after soil contamination: Immediately after contamination and 1, 2, 4, 6, and 10 months after that. Major differences occurred within the first month. Considering the overall data (10 months), it is possible to observe that in OECD soil there is a correlation between concentration in soil and in the organisms, but that was not observed for the natural soil. The decrease patterns for concentration in soil and in watery soil extracts were different: monophasic behavior occurred in OECD soil, and a biphasic pattern was measured in natural soil. It was observed that the bioavailable ( i.e., water-extractable) fraction of lindane in the natural soil decreased faster than the total soil concentration. In natural soil the decrease of concentration appeared faster than in OECD soil; this may be related to the lower amount of organic matter content.

Microparticles for delivering therapeutic peptides and proteins to the lumen of the small intestine

Several different peptides and proteins, such as the pancreatic trypsin inhibitor, growth factors and trefoil peptides, are known to play important roles in maintaining the structure and function of the gastrointestinal wall. With the advent of recombinant biotechnology, it has become feasible to test some of these proteins as therapeutics in different inflammatory conditions of the intestines. However, the harsh pH and enzymatic conditions of the stomach can lead to their inactivation. This research was aimed at the development of particulate, gastric-resistant pharmaceutical forms, incorporating those bioactive molecules. Mixtures of proteins in powder form were coated with cellulose acetate phthalate, Eudragit S100 or Eudragit RS PO, using simple preparation techniques based on single emulsion/solvent evaporation. Using aprotinin as a model drug, it was found that these procedures were effective in microencapsulating protein in the solid form without affecting its biological activity. Furthermore, and in particular with the first two polymers above, particles showed adequate in vitro release patterns for the applications envisioned.

Atrioventricular septal defect following blunt chest trauma

The authors describe an acquired atrioventricular septal defect that has resulted from a blunt chest trauma. Besides being an uncommon traumatic heart injury, this case has the particularities of the non-involvement of other adjacent anatomical structures and the long delay between the accident and the occurrence of the myocardial rupture.