Adkins, J. M. | Search bioRxiv

bioRxiv2020

Comparison of antimicrobial activity between intraoperatively soaked bacitracin sutures and triclosan coated suture

With the easily available option for surgeons to soak their suture in anti-biotic irrigating solution intraoperatively in mind, this study was designed to evaluate the ability of suture soaked in bacitracin irrigating solution to inhibit the growth of Staphylococcus aureus and Methicillin-resistant Staphylococcus aureus. Using standard experimental procedure, sterile suture was soaked in Bacitracin suture, and dried for 10 minutes or 6 hours, incubated for 24 h on inoculated plates, and examined for zone of inhibition around the suture. This was compared to control unsoaked suture and antimicrobial suture (AMS) currently on the market to determine if the minor intra operative procedural change of placing suture in antibiotic irrigation solution instead of on the sterile table could confer some antimicrobial activity. The study found the Bacitracin soaked suture (BSS) consistently inhibited the growth of the test organisms. For both organisms, the BSS exhibited a significantly larger zone of inhibition compared to the unsoaked control suture. However, the AMS currently on the market exhibited a larger zone of inhibition compared to the BSS. Placing sutures in a bacitracin irrigation solution intraoperatively instead of directly on the sterile table can achieve some of the in vitro antimicrobial effect seen from AMS currently on the market. This may result in reduced rates of SSIs and associated costs without major procedural change and at reduced overhead.

microbiology↗

bioRxiv2019

Anterior cingulate cortex and ventral hippocampal inputs to the basolateral amygdala selectively control generalized fear

Nearly one third of Americans have been afflicted with an anxiety disorder. A common symptom of anxiety disorders is the over generalization of fear across a broad range of contextual cues. We previously found that the anterior cingulate cortex and ventral hippocampus (vHPC) regulate generalized fear. Here, we investigate the functional projections from the ACC and vHPC to the amygdala and their role in governing generalized fear in a preclinical rodent model. A chemogenetic approach (DREADDs) was used to inhibit glutamatergic projections from the ACC or vHPC that terminate within the basolateral amygdala (BLA) at recent (1 day) or remote (28 days) time points after contextually fear conditioning male mice. Inactivating ACC or vHPC projections to the BLA significantly reduced generalized fear to a novel, nonthreatening context but had no effect on fear to the training context. Further, our data indicate that the ACC-BLA circuit supports generalization in a time-independent manner. We also identified for the first time a strictly time-dependent role of the vHPC-BLA circuit in supporting remote generalized contextual fear. Dysfunctional signaling to the amygdala from the ACC or the hippocampus could underlie over-generalized fear responses that are associated with anxiety disorders. Our findings demonstrate that the ACC and vHPC regulate fear expressed in novel, nonthreatening environments via projections to the BLA but do so as a result of training intensity or time, respectively.\n\nSignificance StatementAnxiety disorders are characterized by a common symptom that promotes overgeneralization of fear in non-threatening environments. Dysregulation of the amygdala, anterior cingulate cortex (ACC), or hippocampus has been hypothesized to contribute to increased fear associated with anxiety disorders. Our findings show that the ACC and HPC projections to the basolateral amygdala regulate generalized fear in non-threatening, environments. However, descending ACC projections control fear generalization independent of time, whereas HPC projections play a strictly time-dependent role in regulating generalized fear. Thus, dysfunctional ACC/HPC signaling to the BLA may be a predominant underlying mechanism of non-specific fear associated with anxiety disorders. Our data have important implications for predictions made by theories about aging memories and interactions between the hippocampus and cortical regions.

neuroscience↗