Active matter invasion.

Biologically active materials such as bacterial biofilms and eukaryotic cells thrive in confined micro-spaces. Here, we show through numerical simulations that confinement can serve as a mechanical guidance to achieve distinct modes of collective invasion when combined with growth dynamics and the intrinsic activity of biological materials. We assess the dynamics of the growing interface and classify these collective modes of invasion based on the activity of the constituent particles of the growing matter. While at small and moderate activities the active material grows as a coherent unit, we find that blobs of active material collectively detach from the cohort above a well-defined activity threshold. We further characterise the mechanical mechanisms underlying the crossovers between different modes of invasion and quantify their impact on the overall invasion speed.

Presence of the Posterior Communicating Artery Contributes to the Clinical Outcome After Endovascular Treatment of Patients with MCA Occlusions.

PURPOSE: In patients with acute occlusions of the middle cerebral artery, the collaterals play an important role in infarct growth and potentially on clinical outcome. As the primary collateral pathway, the posterior cerebral artery with the posterior communicating artery (PComA) is important. We analyzed the influence of the presence of an ipsilateral PComA on infarct growth and clinical outcome. METHODS: We included 101 patients with M1 occlusions and subsequent endovascular treatment and differentiated patients without an ipsilateral PComA from those with an ipsilateral PComA. RESULTS: There was no difference in the rate of successful recanalizations and procedural parameters between both groups. Of the patients with an existing PComA, 51% showed an excellent clinical outcome (90d mRS < 2), but only 28% of the patients without PComA had an excellent clinical outcome (p = 0.02). The presence of an ipsilateral PComA was independently associated with the rate of excellent clinical outcome (aOR 3.9, 95% CI 1.2-9.8; p = 0.021) and lower infarct volume (38 ± 8 cm3 vs. 78 ± 13 cm3, p = 0.032). CONCLUSION: The presence of an ipsilateral PComA is a predictor for excellent clinical outcome independently from the technical success of mechanical recanalization. This finding provides insights into the changes of circulation in patients suffering from an acute stroke and underlines the importance of collateralization.