ABSTRACT
For the first time, we have used phase-contrast x-ray tomography to characterize the three-dimensional (3d) structure of cardiac tissue from patients who succumbed to Covid-19. By extending conventional histopatholocigal examination by a third dimension, the delicate pathological changes of the vascular system of severe Covid-19 progressions can be analyzed, fully quantified and compared to other types of viral myocarditis and controls. To this end, cardiac samples with a cross section of 3.5mm were scanned at the synchrotron in a parallel beam configuration. The vascular network was segmented by a deep learning architecture suitable for 3d datasets (V-net), trained by sparse manual annotations. Pathological alterations of vessels, concerning the variation of diameters and the amount of small holes, were observed, indicative of elevated occurrence of intussusceptive angiogenesis, also confirmed by scanning electron microscopy. Further, we implemented a fully automated analysis of the tissue structure in form of shape measures based on the structure tensor. The corresponding distributions show that the histopathology of Covid-19 differs from both influenza and typical coxsackie virus myocarditis.
ABSTRACT
Overshooting immune reactions can occur during inflammatory responses that accompany severe infections, such as COVID-19. Cytokines, damage-associated molecular patterns (DAMPs), and reactive oxygen and nitrogen species can generate positive feedback loops of inflammation, leading to long-term complications such as vascular endothelialitis, thrombosis, endothelial dysfunction, neurological impairments, and chronic fatigue. Dexamethasone can limit inflammation by inhibiting the activation of pro-inflammatory transcription factors. High dose dexamethasone, however, has undesirable side effects. Here, we show that Ceylon cinnamon and its major compound cinnamaldehyde can mitigate inflammatory signaling in vitro. Cinnamaldehyde interferes with the dimerization of toll-like receptor 4 (TLR4), which can be activated by DAMPs like HSP60 and HMGB1. Our results suggest that supplementary treatment with Ceylon cinnamon may allow administration of lower doses of dexamethasone to avoid high dose steroid side effects. Moreover, preliminary results indicate that Ceylon cinnamon modulates angiogenesis, which is a reactive phenomenon in COVID-19.
ABSTRACT
In order to save time and resources in early drug development, in vitro methods that correctly predict the formulation effect on oral drug absorption are necessary. The aim of this study was to 1) evaluate various BCS class II drug formulations with in vitro methods and in vivo in order to 2) determine which in vitro method best correlates with the in vivo results. Clarithromycin served as model compound in formulations with different particle sizes and content of excipients. The performed in vitro experiments were dissolution and dissolution/permeation experiments across two types of membrane, Caco-2 cells and excised rat intestinal sheets. The in vivo study was performed in rats. The oral absorption was enhanced by downsizing drug particles and by increasing the excipient concentration. This correlated strongly with the flux across Caco-2 cells but not with the other in vitro experiments. The insufficient correlation with the dissolution experiments can be partly explained by excipient caused problems during the filtration step. The very poor correlation of the in vivo data with the flux across excised rat intestinal sheets might be due to an artificially enlarged mucus layer ex vivo. In conclusion, downsizing BCS class II drug particles and the addition of surfactants enhanced the in vivo absorption, which was best depicted by dissolution/permeation experiments across Caco-2 cells. This setup is proposed as best model to predict the in vivo formulation effect. Also, this is the first study to evaluate the impact of the nature of the permeation membrane in dissolution/permeation experiments.
