Spatial variations in the osteocyte lacuno-canalicular network density and analysis of the connectomic parameters

by Junning Chen, Marta Aido, Andreas Roschger, Alexander van Tol, Sara Checa, Bettina M. Willie, Richard Weinkamer

Osteocyte lacuno-canalicular network (LCN) is comprised of micrometre-sized pores and submicrometric wide channels in bone. Accumulating evidence suggests multiple functions of this network in material transportation, mechanobiological signalling, mineral homeostasis and bone remodelling. Combining rhodamine staining and confocal laser scanning microscopy, the longitudinal cross-sections of six mouse tibiae were imaged, and the connectome of the network was quantified with a focus on the spatial heterogeneities of network density, connectivity and length of canaliculi. In-vivo loading and double calcein labelling on these tibiae allowed differentiating the newly formed bone from the pre-existing regions. The canalicular density of the murine cortical bone varied between 0.174 and 0.243 μm/μm³, and therefore is three times larger than the corresponding value for human femoral midshaft osteons. The spatial heterogeneity of the network was found distinctly more pronounced across the cortex than along the cortex. We found that in regions with a dense network, the LCN conserves its largely tree-like character, but increases the density by including shorter canaliculi. The current study on healthy mice should serve as a motivating starting point to study the connectome of genetically modified mice, including models of bone diseases and of reduced mechanoresponse.

Risk factors associated with surgical site infections in patients undergoing cardiothoracic surgery: A systematic review and meta‐analysis

Abstract

Surgical site infections (SSIs) following cardiothoracic surgery can pose significant challenges to patient recovery and outcome. This systematic review and meta-analysis aim to identify and quantify the risk factors associated with SSIs in patients undergoing cardiothoracic surgery. A comprehensive literature search adhering to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and based on the PICO paradigm was conducted across four databases: PubMed, Embase, Web of Science and the Cochrane Library, without any temporal restrictions. The meta-analysis incorporated studies detailing the risk factors for post-operative sternal infections, especially those reporting odds ratios (OR) or relative risks with 95% confidence intervals (CI). Quality assessment of the studies was done using the Newcastle-Ottawa Scale. Statistical analysis was executed using the chi-square tests for inter-study heterogeneity, with further analyses depending on I ² values. Sensitivity analyses were performed, and potential publication bias was also assessed. An initial dataset of 2442 articles was refined to 21 articles after thorough evaluations based on inclusion and exclusion criteria. Patients with diabetes mellitus have an OR of 1.80 (95% CI: 1.40–2.20) for the incidence of SSIs, while obese patients demonstrate an OR of 1.63 (95% CI: 1.40–1.87). Individuals who undergo intraoperative blood transfusion present an OR of 1.13 (95% CI: 1.07–1.18), and smokers manifest an OR of 1.32 (95% CI: 1.03–1.60). These findings unequivocally indicate a pronounced association between these factors and an elevated risk of SSIs post-operatively. This meta-analysis confirms that diabetes, obesity, intraoperative transfusion and smoking heighten the risk of SSIs post-cardiac surgery. Clinicians should be alert to these factors to optimise patient outcomes.