Time-series incubations in a coastal environment illuminates the importance of early colonizers and the complexity of bacterial biofilm dynamics on marine plastics

The problematic of microplastics pollution in the marine environment is tightly linked to their colonization by a wide diversity of microorganisms, the so-called plastisphere. The composition of the plastisphere relies on a complex combination of multiple factors including the surrounding environment, the time of incubation along with the polymer type, making it difficult to understand how the biofilm evolves during the microplastic lifetime over the oceans. To better define bacterial community assembly processes on plastics, we performed a 5 months spatio-temporal survey of the plastisphere in an oyster farming area in the Bay of Brest (France). We deployed three types of plastic pellets in two positions in the foreshore and in the water column. Plastic-associated biofilm composition in all these conditions was monitored using 16 S rRNA metabarcoding and compared to free-living and attached bacterial members of seawater. We observed that bacterial families associated to plastic pellets were significantly distinct from the ones found in seawater, with a significant prevalence of filamentous Cyanobacteria on plastics. No convergence towards a unique plastisphere was detected between polymers exposed in the intertidal and subtidal area, emphasizing the central role of the surrounding environment on constantly shaping the plastisphere community diversity. However, we could define a bulk of early-colonizers of marine biofilms such as Alteromonas, Pseudoalteromonas or Vibrio. These early-colonizers could reach high abundances in floating microplastics collected in field-sampling studies, suggesting the plastic-associated biofilms could remain at early development stages across large oceanic scales. Our study raises the hypothesis that most members of the plastisphere, including putative pathogens, could result of opportunistic colonization processes and unlikely long-term transport.

Risk management in an anticancer drug preparation unit: use of Preliminary Risk Analysis method and application to the preparation process

Objectives

Preparation of injectable anticancer drugs in hospital pharmacies, in particular of cytotoxics, is a high-risk activity. We used Preliminary Risk Analysis (PRA) to analyse the risks in the different steps of our anticancer drug circuit, including the preparation step (PRA1). Then, to prepare an important change in management of the circuit with the software Chimio® (pooling of three databases for subcontracting), we repeated the analysis of preparation step (PRA2). PRA is known to be time and resource consuming. To overcome this, we developed a strict organisational framework to perform the analysis within a reasonable amount of time. We present the PRA method including its practical implementation, and its application to the anticancer drug preparation process, before and after pooling of Chimio® databases.

Methods

PRA has two main stages, PRA “system” and PRA “scenario”. A multidisciplinary working group is created for the entire PRA process. PRA “system” is an exploratory and qualitative stage. PRA “scenario” requires the creation of risk assessment tools and decision tools before actually developing, analysing and treating scenarios, with risk reduction actions structured in an action plan. For PRA2 we used the same working group, assessment and decision tools as for PRA1 and we only analysed dangerous situations (DS) that appeared or changed towards more risk, requiring a new action plan. The different PRA only required four 2 h meetings thanks to the investment of a coordinator who is expert in the method.

Results

In PRA1, the riskiest phase was production while it was the verification and delivery of the finished product in PRA2. The risks were mainly related to management, human and technical dangers in PRA1. Human danger was found to be the main danger in PRA2, followed by organisational danger. Among the 264 scenarios described in PRA1, six of criticality 3 and 69 of criticality 2 have been associated with risk reduction actions. These actions mainly involved managing the risk of human error, with the control system Drugcam® and the standardisation of the pharmaceutical assistants’ training program. In PRA2, 11 scenarios were analysed, including three of criticality 3 and 4 of criticality 2 for which risk reduction measures were taken.

Conclusions

PRA allowed us to perform an in depth analysis of the highly specific and technical process of anticancer drug preparation. Human danger was one of the most important dangers identified, and it should always be taken into consideration, whatever the measures taken to prevent it. PRA2 was extremely useful to plan the organisation that would result from the new Chimio® database, while involving the team and winning its commitment. It allowed an exhaustive and structured anticipation of this major change. Practical aspects of PRA method implementation we have adopted facilitate its application and can help to deploy it on many areas in our hospitals. Indeed, besides an exhaustive analysis of the risks, this approach promotes collaboration, develops a quality culture and is an excellent tool for team and project management, as well as communication.

Deficiency or blockade of angiotensin II type 2 receptor delays tumorigenesis by inhibiting malignant cell proliferation and angiogenesis

Despite significant expression level in cancer cells, the role of the angiotensin II Type 2 receptor (AT2R) in cancer progression remains poorly understood. We aimed to investigate the involvement of AT2R in tumorigenesis, hypothesizing a role in tumor cell proliferation and/or tumor angiogenesis. Two animal tumor models were used: fibrosarcoma induced by 3-methylcholanthrene (3-MCA) in FVB/N mice invalidated for AT2R (AT2R-KO) and carcinoma LL/2 cells injected in C57BL/6N mice treated with AT2R antagonist PD123,319. Tumor growth was monitored, microvascular density (MVD) evaluated by CD31 staining. Proliferation index of LL/2 and 3-MCA tumor cells was evaluated by expression of Ki-67. Angiogenesis was assessed by aorta ring assay and angiogenic mediators' expression by real-time RT-PCR. Tumor induction by 3-MCA was significantly delayed in AT2R-KO compared to wild-type mice (56 days vs. 28 days). Tumorigenesis following LL/2 cell injection in mice was also significantly reduced by early administration of the antagonist PD123,319. In vitro, inactivation or invalidation of AT2R inhibited proliferation of LL/2 and 3-MCA tumor cells, respectively. Tumor MVD was reduced in mice treated early with PD123,319. Ex vivo experiments revealed a significant decrease in angiogenesis after PD123,319 treatment or in AT2R-KO mice. Finally, we identified vascular endothelial growth factor (VEGF) as a soluble proangiogenic factor produced by LL/2 cells and we showed that in LL/2 and 3-MCA tumor cells, inhibition or deficiency of AT2R was associated with impaired production of proangiogenic factors included VEGF. This study uncovered novel mechanisms by which AT2R would promote tumor development, favoring both malignant cell proliferation and tumor angiogenesis.