Multiple Doses of Erythropoietin Impair Liver Regeneration by Increasing TNF-α, the Bax to Bcl-xL Ratio and Apoptotic Cell Death

BACKGROUND: Liver resection and the use of small-for-size grafts are restricted by the necessity to provide a sufficient amount of functional liver mass. Only few promising strategies to maximize liver regeneration are available. Apart from its erythropoiesis-stimulating effect, erythropoietin (EPO) has meanwhile been recognized as mitogenic, tissue-protective, and anti-apoptotic pleiotropic cytokine. Thus, EPO may support regeneration of hepatic tissue. METHODOLOGY: Rats undergoing 68% hepatectomy received daily either high dose (5000 IU/kg bw i.v.) or low dose (500 IU/kg bw i.v.) recombinant human EPO or equal amounts of physiologic saline. Parameters of liver regeneration and hepatocellular apoptosis were assessed at 24 h, 48 h and 5 d after resection. In addition, red blood cell count, hematocrit and serum EPO levels as well as plasma concentrations of TNF-alpha and IL-6 were evaluated. Further, hepatic Bcl-x(L) and Bax protein expression were analyzed by Western blot. PRINCIPAL FINDINGS: Administration of EPO significantly reduced the expression of PCNA at 24 h followed by a significant decrease in restitution of liver mass at day 5 after partial hepatectomy. EPO increased TNF-alpha levels and shifted the Bcl-x(L) to Bax ratio towards the pro-apoptotic Bax resulting in significantly increased hepatocellular apoptosis. CONCLUSIONS: Multiple doses of EPO after partial hepatectomy increase hepatocellular apoptosis and impair liver regeneration in rats. Thus, careful consideration should be made in pre- and post-operative recombinant human EPO administration in the setting of liver resection and transplantation

Recurrence of chronic subdural hematoma due to low-grade infection

Despite the high incidence and multitudes of operative techniques, the risk factors for chronic subdural hematoma (CSDH) recurrence are still under debate and a universal consensus on the pathophysiology is lacking. We hypothesized that clinically inapparent, a low-grade infection could be responsible for CSDH recurrence. This investigation is a single-center prospective observational study including patients with recurrent CSDH. In total, 44 patients with CSDH recurrence received an intraoperative swab-based microbiological test. The intraoperative swab revealed an inapparent low-grade hematoma infection in 29% of the recurrent CSDH cases. The majority (69%) of the identified germs belonged to the staphylococcus genus. We therefore, propose a novel potential pathophysiology for CSDH recurrence

Improving 3D convolutional neural network comprehensibility via interactive visualization of relevance maps: Evaluation in Alzheimer's disease

Background: Although convolutional neural networks (CNN) achieve high diagnostic accuracy for detecting Alzheimer's disease (AD) dementia based on magnetic resonance imaging (MRI) scans, they are not yet applied in clinical routine. One important reason for this is a lack of model comprehensibility. Recently developed visualization methods for deriving CNN relevance maps may help to fill this gap. We investigated whether models with higher accuracy also rely more on discriminative brain regions predefined by prior knowledge. Methods: We trained a CNN for the detection of AD in N=663 T1-weighted MRI scans of patients with dementia and amnestic mild cognitive impairment (MCI) and verified the accuracy of the models via cross-validation and in three independent samples including N=1655 cases. We evaluated the association of relevance scores and hippocampus volume to validate the clinical utility of this approach. To improve model comprehensibility, we implemented an interactive visualization of 3D CNN relevance maps. Results: Across three independent datasets, group separation showed high accuracy for AD dementia vs. controls (AUC$\geq$0.92) and moderate accuracy for MCI vs. controls (AUC$\approx$0.75). Relevance maps indicated that hippocampal atrophy was considered as the most informative factor for AD detection, with additional contributions from atrophy in other cortical and subcortical regions. Relevance scores within the hippocampus were highly correlated with hippocampal volumes (Pearson's r$\approx$-0.86, p<0.001). Conclusion: The relevance maps highlighted atrophy in regions that we had hypothesized a priori. This strengthens the comprehensibility of the CNN models, which were trained in a purely data-driven manner based on the scans and diagnosis labels.Comment: 24 pages, 9 figures/tables, supplementary material, source code available on GitHu

Hepatocellular apoptosis.

<p>Apoptotic cell death, as assessed by TUNEL-analysis in animals at 24 h, 48 h and 5 d after pHx and daily administration of high dose EPO (5000 IU/kg bw iv; closed bars) or physiologic saline solution (open bars) (A). Representative images at day 5 after pHx of a saline-treated control (B) and an EPO-treated animal (C). Arrowhead indicate TUNEL-positive apoptotic hepatocytes. Bars represent 50 µm. Means±SEM; unpaired Student's t-test. * P<0.05 vs the saline-treated group at the respective time point.</p

Transaminase and cytokine release.

<p>Plasma levels of ALT (A), TNF-α (B), and IL-6 (C) in animals at 24 h, 48 h and 5 d after pHx and daily administration of high dose EPO (5000 IU/kg bw iv; closed bars) or physiologic saline solution (open bars). Means±SEM; unpaired Student's t-test. * P<0.05 vs the saline-treated group at the respective time point.</p

Serum EPO concentration, hematocrit and red blood cell count

<p>Serum EPO concentration, hematocrit and red blood cell (RBC) count in animals at 24 h, 48 h and 5 d after pHx and daily administration of EPO at a dose of either 5000 IU/kg bw or 500 IU/kg bw. Control animals received equivalent volumes of physiologic saline (Con). For determination of physiological baseline values blood samples were obtained from non-resected, untreated rats (baseline). Data are given as means±SEM; Mann-Whitney rank sum test, ^* P<0.05 vs Con at the respective time point and EPO dose.</p

Anti-apoptotic Bcl-x_L and pro-apoptotic Bax as well as the Bcl-x_L/Bax ratio.

<p>Protein expression of anti-apoptotic Bcl-x_L (A) and pro-apoptotic Bax (B) as well as the Bcl-x_L/Bax ratio (C) in animals at 24 h, 48 h and 5 d after pHx and daily administration of high dose EPO (5000 IU/kg bw iv; closed bars) or physiologic saline solution (open bars). Data are normalized to ß-actin as loading control. Means±SEM; unpaired Student's t-test. * P<0.05 vs the saline-treated group at the respective time point.</p