Multimodal ultrasound imaging with conventional B-mode, elastography, and parametric analysis of contrast-enhanced ultrasound (CEUS): A novel approach to assess small bowel manifestation in severe COVID-19 disease.

The aim was to describe the small bowel morphology with conventional B-mode and elastography and additionally to evaluate dynamic effects of COVID-19 associated small bowel microvascularization using CEUS with color coded perfusion parameters.Thirteen patients with severe COVID-19 acute respiratory distress syndrome (ARDS) were investigated. 13 patients required intensive care treatment with mechanical ventilation. Five patients required extracorporeal membrane oxygenation (ECMO). Contrast-enhanced ultrasound (CEUS) was performed by an experienced investigator as a bolus injection of up to 2.4 ml sulfur hexafluoride microbubbles via a central venous catheter. In the parametric analysis of CEUS, the flare of microbubbles over time is visualized with colors. This is the first work using parametric analysis of CEUS to detect perfusion differences in the small bowel.Parametric analysis of CEUS in the intestinal phase was carried out, using DICOM loops for 20 seconds. In 5 patients, parametric analysis revealed intraindividual differences in contrast agent behavior in the small bowel region. Analogous to the computed tomography (CT) images parametric analysis showed regions of simultaneous hyper- and hypoperfusion of the small intestine in a subgroup of patients. In 5 patients, the parametric image of transmural global contrast enhancement was visualized.Our results using CEUS to investigate small bowel affection in COVID-19 suggest that in severe COVID-19 ARDS systemic inflammation and concomitant micro embolisms may lead to disruption of the epithelial barrier of the small intestine.This is the first study using parametric analysis of CEUS to evaluate the extent of small bowel involvement in severe COVID-19 disease and to detect microemboli. In summary, we show that in COVID-19 the small bowel may also be an important interaction site. This is in line with the fact that enterocytes have been shown to a plenitude of angiotensin converting enzyme (ACE)-2 receptors as entry sites of the virus.

Contrast enhanced ultrasonography (CEUS) a novel tool to detect intestinal epithelial barrier dysfunction in severe COVID-19 disease.

Ten patients with confirmed COVID-19 disease were studied. Nine patients required intensive care treatment, among them four needed extracorporeal membrane oxygenation (ECMO). Contrast enhanced ultrasonography (CEUS) was performed by one experienced investigator as a bolus injection of up to 2.4 ml of sulphur hexafluoride microbubbles via a central venous catheter. B-Mode evaluation and strain elastography showed mural edema of the small bowel with a thickness of up to 10 mm in all patients. We applied color coded Doppler sonography (CCDS) and power mode with flow-adapted parameters and early, dynamic capillary arterial contrast enhancement of bowel wall structures <10 s to assess perfusion of the small bowel. In all patients, reactive hyperemia was seen in the entire small bowel. In a subgroup of seven patients microbubbles translocated into the intestinal lumen. Thus, high-grade intestinal barrier disruption secondary to SARSCoV-2 infection can be postulated in these patients.This is the first description of perfusion changes and a disruption of the small bowel epithelial barrier in COVID-19 Patients using contrast ultrasonography and elastography.

TNF-α mediates mitochondrial uncoupling and enhances ROS-dependent cell migration via NF-κB activation in liver cells.

Development of hepatocellular carcinoma (HCC) is accompanied by a continuous increase in reactive oxygen species (ROS) levels. To investigate the primary source of ROS in liver cells, we used tumor necrosis factor-alpha (TNF-α) as stimulus. Applying inhibitors against the respiratory chain complexes, we identified mitochondria as primary source of ROS production. TNF-α altered mitochondrial integrity by mimicking a mild uncoupling effect in liver cells, as indicated by a 40% reduction in membrane potential and ATP depletion (35%). TNF-α-induced ROS production activated NF-κB 3.5-fold and subsequently enhanced migration up to 12.7-fold. This study identifies complex I and complex III of the mitochondrial respiratory chain as point of release of ROS upon TNF-α stimulation of liver cells, which enhances cell migration by activating NF-κB signalling.

AF-1 a novel regulator of the redox equilibrium during aging.

Multicellular organisms generally undergo qualitative changes within time that are associated with progressive degeneration of biological functions, increased susceptibility to diseases, and increased probability to die within a given time period (aging). One of the major factors contributing to aging is accumulation of oxidative damage. We show that Aging Factor-1 (AF-1) negatively influences the redox balance during aging. AF-1 expression is greatly enhanced in various human cell types of aged individuals which leads to decreased stress resistance towards oxidative damage. We used Drosophila melanogaster as an in vivo model system. Functional knockdown of AF-1 in Drosophila melanogaster reveals a gender-specific effect on lifespan. Whereas female flies show a prolonged healthy lifespan, males show no difference (or even a shortened lifespan). Altogether our data suggest AF-1 expression during aging to be a mechanism that affects healthy aging and age-related stress resistance depending on the gender of the fly.

MHC class I molecules compete in the endoplasmic reticulum for access to transporter associated with antigen processing.

We have used the functionally distinct TAP alleles of the rat in cellular transfectants as tools to investigate how newly formed rat class I (RT1.A) molecules with distinct peptide requirements gain access to suitable peptides in the endoplasmic reticulum (ER). Normal maturation of RT1.Aa depends on the presence in the ER of peptides with C-terminal arginine, while restrictive TAP-B allelic group transporters fail to transport such peptides. In this situation, RT1.Aa is retained in the ER. We show that this retention is accompanied by accumulation of RT1.Aa in the ER, partly associated with TAP and partly free. In such cells, access to TAP of a second allelic product, RT1.Au, which does not require C-terminal arginine peptides, is competitively inhibited by the build-up of RT1.Aa. Nevertheless, RT1.Au loads and matures normally. Introduction of a permissive TAP-A allele competent to transport C-terminal arginine peptides releases RT1.Aa from the ER and restores RT1.Au interaction with TAP. Both class I alleles associate indiscriminately with permissive and restrictive TAP alleles. The data support the view that interaction with TAP is not a prerequisite for peptide loading by class I molecules, so long as suitable peptides are available in the ER. They further show that TAP association of a class I molecule depends on a competitive balance in the ER defined by the extent to which the peptide requirements of other class I molecules present are satisfied and not only by the intrinsic strength of the interaction with TAP.