How do medical professionals make sense (or not) of AI? A social-media-based computational grounded theory study and an online survey.

To investigate opinions and attitudes of medical professionals towards adopting AI-enabled healthcare technologies in their daily business, we used a mixed-methods approach. Study 1 employed a qualitative computational grounded theory approach analyzing 181 Reddit threads in the several subreddits of r/medicine. By utilizing an unsupervised machine learning clustering method, we identified three key themes: (1) consequences of AI, (2) physician-AI relationship, and (3) a proposed way forward. In particular Reddit posts related to the first two themes indicated that the medical professionals' fear of being replaced by AI and skepticism toward AI played a major role in the argumentations. Moreover, the results suggest that this fear is driven by little or moderate knowledge about AI. Posts related to the third theme focused on factual discussions about how AI and medicine have to be designed to become broadly adopted in health care. Study 2 quantitatively examined the relationship between the fear of AI, knowledge about AI, and medical professionals' intention to use AI-enabled technologies in more detail. Results based on a sample of 223 medical professionals who participated in the online survey revealed that the intention to use AI technologies increases with increasing knowledge about AI and that this effect is moderated by the fear of being replaced by AI.

Brucella melitensis 16M produces a mannan and other extracellular matrix components typical of a biofilm.

Mutations in the Brucella melitensis quorum-sensing (QS) system are involved in the formation of clumps containing an exopolysaccharide. Here, we show that the overexpression of a gene called aiiD in B. melitensis gives rise to a similar clumping phenotype. The AiiD enzyme degrades AHL molecules and leads therefore to a QS-deficient strain. We demonstrated the presence of exopolysaccharide and DNA, two classical components of extracellular matrices, in clumps produced by this strain. We also observed that the production of outer membrane vesicles is strongly increased in the aiiD-overexpressing strain. Moreover, this strain allowed us to purify the exopolysaccharide and to obtain its composition and the first structural information on the complex exopolysaccharide produced by B. melitensis 16M, which was found to have a molecular weight of about 16 kDa and to be composed of glucosamine, glucose and mostly mannose. In addition, we found the presence of 2- and/or 6-substituted mannosyl residues, which provide the first insights into the linkages involved in this polymer. We used a classical biofilm attachment assay and an HeLa cell infection model to demonstrate that the clumping strain is more adherent to polystyrene plates and to HeLa cell surfaces than the wild-type one. Taken together, these data reinforce the evidence that B. melitensis could form biofilms in its lifecycle.

Mutations of the quorum sensing-dependent regulator VjbR lead to drastic surface modifications in Brucella melitensis.

Successful establishment of infection by bacterial pathogens requires fine-tuning of virulence-related genes. Quorum sensing (QS) is a global regulation process based on the synthesis of, detection of, and response to small diffusible molecules, called N-acyl-homoserine lactones (AHL), in gram-negative bacteria. In numerous species, QS has been shown to regulate genes involved in the establishment of pathogenic interactions with the host. Brucella melitensis produces N-dodecanoyl homoserine lactones (C(12)-HSL), which down regulate the expression of flagellar genes and of the virB operon (encoding a type IV secretion system), both of which encode surface virulence factors. A QS-related regulator, called VjbR, was identified as a transcriptional activator of these genes. We hypothesized that VjbR mediates the C(12)-HSL effects described above. vjbR alleles mutated in the region coding for the AHL binding domain were constructed to test this hypothesis. These alleles expressed in trans in a DeltavjbR background behave as constitutive regulators both in vitro and in a cellular model of infection. Interestingly, the resulting B. melitensis strains, unable to respond to AHLs, aggregate spontaneously in liquid culture. Preliminary characterization of these strains showed altered expression of some outer membrane proteins and overproduction of a matrix-forming exopolysaccharide, suggesting for the first time that B. melitensis could form biofilms. Together, these results indicate that QS through VjbR is a major regulatory system of important cell surface structures of Brucella and as such plays a key role in host-pathogen interactions.