Search

Abstract Background This phase I/II-trial assessed the dose-limiting toxicities (DLT) and maximum tolerated dose (MTD) of neoadjuvant radiochemotherapy (RCT) with docetaxel and oxaliplatin in patients with locally advanced adenocarcinoma of the oesophagogastric junction. Methods Patients received neoadjuvant radiotherapy (50.4 Gy) together with weekly docetaxel (20 mg/m2 at dose level (DL) 1 and 2, 25 mg/m2 at DL 3) and oxaliplatin (40 mg/m2 at DL 1, 50 mg/m2 at DL 2 and 3) over 5 weeks. The primary endpoint was the DLT and the MTD of the RCT regimen. Secondary endpoints included overall response rate (ORR) and progression-free survival (PFS). Results A total of 24 patients were included. Four patients were treated at DL 1, 13 patients at DL 2 and 7 patients at DL 3. The MTD of the RCT was considered DL 2 with docetaxel 20 mg/m2 and oxaliplatin 50 mg/m2. Objective response (CR/PR) was observed in 32% (7/22) of patients. Eighteen patients (75%) underwent surgery after RCT. The median PFS for all patients (n = 24) was 6.5 months. The median overall survival for all patients (n = 24) was 16.3 months. Patients treated at DL 2 had a median overall survival of 29.5 months. Conclusion Neoadjuvant RCT with docetaxel 20 mg/m2 and oxaliplatin 50 mg/m2 was effective and showed a good toxicity profile. Future studies should consider the addition of targeted therapies to current neoadjuvant therapy regimens to further improve the outcome of patients with advanced cancer of the oesophagogastric junction. Trial Registration NCT00374985

Abstract Multiple activations of individual genes during embryonic liver and HCC development have repeatedly prompted speculations about conserved embryonic signatures driving cancer development. Recently, the emerging discussion on cancer stem cells and the appreciation that generally tumors may develop from progenitor cells of diverse stages of cellular differentiation has shed increasing light on the overlapping genetic signatures between embryonic liver development and HCC. However there is still a lack of systematic studies investigating this area. We therefore performed a comprehensive analysis of differentially regulated genetic signaling pathways in embryonic and liver cancer development and investigated their biological relevance. Genetic signaling pathways were investigated on several publically available genome wide microarray experiments on liver development and HCC. Differentially expressed genes were investigated for pathway enrichment or underrepresentation compared to KEGG annotated pathways by Fisher exact evaluation. The comparative analysis of enrichment and under representation of differentially regulated genes in liver development and HCC demonstrated a significant overlap between multiple pathways. Most strikingly we demonstrated a significant overlap not only in pathways expected to be relevant to both conditions such as cell cycle or apoptosis but also metabolic pathways associated with carbohydrate and lipid metabolism. Furthermore, we demonstrated the clinical significance of these findings as unsupervised clustering of HCC patients on the basis of these metabolic pathways displayed significant differences in survival. These results indicate that liver development and liver cancer share similar alterations in multiple genetic signaling pathways. Several pathways with markedly similar patterns of enrichment or underrepresentation of various regulated genes between liver development and HCC are of prognostic relevance in HCC. In particular, the metabolic pathways were identified as novel prognostically relevant players in HCC development.

Abstract Background 15-20% of all patients initially diagnosed with colorectal cancer develop metastatic disease and surgical resection remains the only potentially curative treatment available. Current 5-year survival following R0-resection of liver metastases is 28-39%, but recurrence eventually occurs in up to 70%. To date, adjuvant chemotherapy has not improved clinical outcomes significantly. The primary objective of the ongoing LICC trial (L-BLP25 In Colorectal Cancer) is to determine whether L-BLP25, an active cancer immunotherapy, extends recurrence-free survival (RFS) time over placebo in colorectal cancer patients following R0/R1 resection of hepatic metastases. L-BLP25 targets MUC1 glycoprotein, which is highly expressed in hepatic metastases from colorectal cancer. In a phase IIB trial, L-BLP25 has shown acceptable tolerability and a trend towards longer survival in patients with stage IIIB locoregional NSCLC. Methods/Design This is a multinational, phase II, multicenter, randomized, double-blind, placebo-controlled trial with a sample size of 159 patients from 20 centers in 3 countries. Patients with stage IV colorectal adenocarcinoma limited to liver metastases are included. Following curative-intent complete resection of the primary tumor and of all synchronous/metachronous metastases, eligible patients are randomized 2:1 to receive either L-BLP25 or placebo. Those allocated to L-BLP25 receive a single dose of 300 mg/m2 cyclophosphamide (CP) 3 days before first L-BLP25 dose, then primary treatment with s.c. L-BLP25 930 μg once weekly for 8 weeks, followed by s.c. L-BLP25 930 μg maintenance doses at 6-week (years 1&2) and 12-week (year 3) intervals unless recurrence occurs. In the control arm, CP is replaced by saline solution and L-BLP25 by placebo. Primary endpoint is the comparison of recurrence-free survival (RFS) time between groups. Secondary endpoints are overall survival (OS) time, safety, tolerability, RFS/OS in MUC-1 positive cancers. Exploratory immune response analyses are planned. The primary endpoint will be assessed in Q3 2016. Follow-up will end Q3 2017. Interim analyses are not planned. Discussion The design and implementation of such a vaccination study in colorectal cancer is feasible. The study will provide recurrence-free and overall survival rates of groups in an unbiased fashion. Trial Registration EudraCT Number 2011-000218-20

Abstract Background Organic cation transporters (OCT) are responsible for the uptake and intracellular inactivation of a broad spectrum of endogenous substrates and detoxification of xenobiotics and chemotherapeutics. The transporters became pharmaceutically interesting, because OCTs are determinants of the cytotoxicity of platin derivates and the transport activity has been shown to correlate with the sensitivity of tumors towards tyrosine kinase inhibitors. No data exist about the relevance of OCTs in hepatocellular carcinoma (HCC). Methods OCT1 (SLC22A1) and OCT3 (SLC22A3) mRNA expression was measured in primary human HCC and corresponding non neoplastic tumor surrounding tissue (TST) by real time PCR (n = 53). Protein expression was determined by western blot analysis and immunofluorescence. Data were correlated with the clinicopathological parameters of HCCs. Results Real time PCR showed a downregulation of SLC22A1 and SLC22A3 in HCC compared to TST (p ≤ 0.001). A low SLC22A1 expression was associated with a worse patient survival (p < 0.05). Downregulation was significantly associated with advanced HCC stages, indicated by a higher number of T3 tumors (p = 0.025) with a larger tumor diameter (p = 0.035), a worse differentiation (p = 0.001) and higher AFP-levels (p = 0.019). In accordance, SLC22A1 was less frequently downregulated in tumors with lower stages who underwent transarterial chemoembolization (p < 0.001) and liver transplantation (p = 0.001). Tumors with a low SLC22A1 expression (< median) showed a higher SLC22A3 expression compared to HCC with high SLC22A1 expression (p < 0.001). However, there was no significant difference in tumor characteristics according to the level of the SLC22A3 expression. In the western blot analysis we found a different protein expression pattern in tumor samples with a more diffuse staining in the immunofluorescence suggesting that especially OCT1 is not functional in advanced HCC. Conclusion The downregulation of OCT1 is associated with tumor progression and a worse patient survival.

Abstract Background Parvovirus H-1 (H-1PV) infects and lyses human tumor cells including melanoma, hepatoma, gastric, colorectal, cervix and pancreatic cancers. We assessed whether the beneficial effects of chemotherapeutic agents or targeted agents could be combined with the oncolytic and immunostimmulatory properties of H-1PV. Methods Using human ex vivo models we evaluated the biological and immunological effects of H-1PV-induced tumor cell lysis alone or in combination with chemotherapeutic or targeted agents in human melanoma cells +/- characterized human cytotoxic T-cells (CTL) and HLA-A2-restricted dendritic cells (DC). Results H-1PV-infected MZ7-Mel cells showed a clear reduction in cell viability of >50%, which appeared to occur primarily through apoptosis. This correlated with viral NS1 expression levels and was enhanced by combination with chemotherapeutic agents or sunitinib. Tumor cell preparations were phagocytosed by DC whose maturation was measured according to the treatment administered. Immature DC incubated with H-1PV-induced MZ7-Mel lysates significantly increased DC maturation compared with non-infected or necrotic MZ7-Mel cells. Tumor necrosis factor-α and interleukin-6 release was clearly increased by DC incubated with H-1PV-induced SK29-Mel tumor cell lysates (TCL) and was also high with DC-CTL co-cultures incubated with H-1PV-induced TCL. Similarly, DC co-cultures with TCL incubated with H-1PV combined with cytotoxic agents or sunitinib enhanced DC maturation to a greater extent than cytotoxic agents or sunitinib alone. Again, these combinations increased pro-inflammatory responses in DC-CTL co-cultures compared with chemotherapy or sunitinib alone. Conclusions In our human models, chemotherapeutic or targeted agents did not only interfere with the pronounced immunomodulatory properties of H-1PV, but also reinforced drug-induced tumor cell killing. H-1PV combined with cisplatin, vincristine or sunitinib induced effective immunostimulation via a pronounced DC maturation, better cytokine release and cytotoxic T-cell activation compared with agents alone. Thus, the clinical assessment of H-1PV oncolytic tumor therapy not only alone but also in combination strategies is warranted.

Abstract Background Cancer cells are characterized by massive dysegulation of physiological cell functions with considerable disruption of transcriptional regulation. Genome-wide transcriptome profiling can be utilized for early detection and molecular classification of cancers. Accurate discrimination of functionally different tumor types may help to guide selection of targeted therapy in translational research. Concise grouping of tumor types in cancer maps according to their molecular profile may further be helpful for the development of new therapeutic modalities or open new avenues for already established therapies. Methods Complete available human tumor data of the Stanford Microarray Database was downloaded and filtered for relevance, adequacy and reliability. A total of 649 tumor samples from more than 1400 experiments and 58 different tissues were analyzed. Next, a method to score deregulation of KEGG pathway maps in different tumor entities was established, which was then used to convert hundreds of gene expression profiles into corresponding tumor-specific pathway activity profiles. Based on the latter, we defined a measure for functional similarity between tumor entities, which yielded to phylogeny of tumors. Results We provide a comprehensive, easy-to-interpret functional cancer map that characterizes tumor types with respect to their biological and functional behavior. Consistently, multiple pathways commonly associated with tumor progression were revealed as common features in the majority of the tumors. However, several pathways previously not linked to carcinogenesis were identified in multiple cancers suggesting an essential role of these pathways in cancer biology. Among these pathways were 'ECM-receptor interaction', 'Complement and Coagulation cascades', and 'PPAR signaling pathway'. Conclusion The functional cancer map provides a systematic view on molecular similarities across different cancers by comparing tumors on the level of pathway activity. This work resulted in identification of novel superimposed functional pathways potentially linked to cancer biology. Therefore, our work may serve as a starting point for rationalizing combination of tumor therapeutics as well as for expanding the application of well-established targeted tumor therapies.

Abstract Background Systems biology approaches offer novel insights into the development of chronic liver diseases. Current genomic databases supporting systems biology analyses are mostly based on microarray data. Although these data often cover genome wide expression, the validity of single microarray experiments remains questionable. However, for systems biology approaches addressing the interactions of molecular networks comprehensive but also highly validated data are necessary. Results We have therefore generated the first comprehensive database for published molecular associations in human liver diseases. It is based on PubMed published abstracts and aimed to close the gap between genome wide coverage of low validity from microarray data and individual highly validated data from PubMed. After an initial text mining process, the extracted abstracts were all manually validated to confirm content and potential genetic associations and may therefore be highly trusted. All data were stored in a publicly available database, Library of Molecular Associations http://www.medicalgenomics.org/databases/loma/news, currently holding approximately 1260 confirmed molecular associations for chronic liver diseases such as HCC, CCC, liver fibrosis, NASH/fatty liver disease, AIH, PBC, and PSC. We furthermore transformed these data into a powerful resource for molecular liver research by connecting them to multiple biomedical information resources. Conclusion Together, this database is the first available database providing a comprehensive view and analysis options for published molecular associations on multiple liver diseases.

Abstract Background Prognosis of esophageal cancer is poor despite curative surgery. The chemokine receptor CXCR4 has been proposed to distinctly contribute to tumor growth, dissemination and local immune escape in a limited number of malignancies. The aim of our study was to evaluate the role of CXCR4 in tumor spread of esophageal cancer with a differentiated view of the two predominant histologic types – squamous cell and adenocarcinoma. Methods Esophageal cancer tissue samples were obtained from 102 consecutive patients undergoing esophageal resection for cancer with curative intent. The LSAB+ System was used to detect the protein CXCR4. Tumor samples were classified into two groups based on the homogeneous staining intensity. A cut-off between CXCR4w (= weak expression) and CXCR4s (= strong expression) was set at 1.5 (grouped 0 – 1.5 versus 2.0 – 3). Long-term survival rates were calculated using life tables and the Kaplan-Meier method. Using the Cox's proportional hazards analysis, a model of survival prediction was established. Results The overall expression rate for CXCR4 in esophageal squamous cell carcinoma was 94.1%. Subdividing these samples, CXCR4w was found in 54.9% and CXCR4s in 45.1%. In adenocarcinoma, an overall expression rate of 89.1% was detected with a weak intensitiy in 71.7% compared to strong staining in 29.3% (p = 0.066 squamous cell versus adenocarcinoma). The Cox's proportional hazards analysis identified the pM-category with a hazard ratio (HR) of 1.860 (95% CI: 1.014–3.414) (p = 0.045), the histologic tumor type (HR: 0.334; 95% CI: 0.180–0.618) (p = 0.0001) and the operative approach (transthoracic > transhiatal esophageal resection) (HR: 0.546; 95% CI: 0.324–0.920) (p = 0.023) as independent factors with a possible influence on the long-term prognosis in patients with esophageal carcinoma, whereas CXCR4 expression was statistically not significant (>0.05). Conclusion Expression of the chemokine receptor CXCR4 in esophageal cancer is of major relevance in both histologic entities – squamous cell and adenocarcinoma. Though with lack of statistical significance, strong CXCR4 expression revealed a poorer long-term prognosis following curative esophagectomy in both histologic subtypes. Thus, the exact biological functions of CXCR4 in terms of tumor dissemination of esophageal cancer is yet undetermined. Inhibition of esophageal cancer progression by CXCR4 antagonists might be a promising therapeutic option in the future.

Abstract Background Hepatocelluar carcinoma (HCC) is one of the most common cancers worldwide and a major cause of cancer-related mortality. HCC is highly resistant to currently available chemotherapeutic drugs. Defects in apoptosis signaling contribute to this resistance. Myeloid cell leukemia-1 (Mcl-1) is an anti-apoptotic member of the Bcl-2 protein family which interferes with mitochondrial activation. In a previous study we have shown that Mcl-1 is highly expressed in tissues of human HCC. In this study, we manipulated expression of the Mcl-1 protein in HCC cells by RNA interference and analyzed its impact on apoptosis sensitivity of HCC cells in vitro. Methods RNA interference was performed by transfecting siRNA to specifically knock down Mcl-1 expression in HCC cells. Mcl-1 expression was measured by quantitative real-time PCR and Western blot. Induction of apoptosis and caspase activity after treatment with chemotherapeutic drugs and different targeted therapies were measured by flow cytometry and fluorometric analysis, respectively. Results Here we demonstrate that Mcl-1 expressing HCC cell lines show low sensitivity towards treatment with a panel of chemotherapeutic drugs. However, treatment with the anthracycline derivative epirubicin resulted in comparatively high apoptosis rates in HCC cells. Inhibition of the kinase PI3K significantly increased apoptosis induction by chemotherapy. RNA interference efficiently downregulated Mcl-1 expression in HCC cells. Mcl-1 downregulation sensitized HCC cells to different chemotherapeutic agents. Sensitization was accompanied by profound activation of caspase-3 and -9. In addition, Mcl-1 downregulation also increased apoptosis rates after treatment with PI3K inhibitors and, to a lower extent, after treatment with mTOR, Raf I and VEGF/PDGF kinase inhibitors. TRAIL-induced apoptosis did not markedly respond to Mcl-1 knockdown. Additionally, knockdown of Mcl-1 efficiently enhanced apoptosis sensitivity towards combined treatment modalities: Mcl-1 knockdown significantly augmented apoptosis sensitivity of HCC cells towards chemotherapy combined with PI3K inhibition. Conclusion Our data suggest that specific downregulation of Mcl-1 by RNA interference is a promising approach to sensitize HCC cells towards chemotherapy and molecularly targeted therapies.

Abstract Background Extensive disease of cholangiocarcinoma (CC) determines the overall outcome and limits curative resection. Despite chemotherapy, which has been introduced to improve the outcome of biliary tract malignancies, the benefit in survival is still marginal. Case presentation We report a 69-year-old patient with non-resectable CC showing hepatic metastasis and peritoneal carcinomatosis. Diagnosis was based on computed tomography, mini-laparoscopy and bioptic specimens. Histology revealed an adenocarcinoma of the biliary tract with expression of epithelial growth factor receptor. After informed consent the patient received experimental gemcitabine (1000 mg/m2) every other week and cetuximab (250 mg/m2) weekly for palliative chemotherapy. During the reported follow up (since time of first presentation) 20 cycles of chemotherapy were administered. Relevant chemotherapy-related toxicity was limited on gemcitabine-associated side effects. Predominantly, haematological toxicity (CTC, grade 3) and neutropenic fever (CTC, grade 3) promoted by catheter-related sepsis were observed. Cetuximab caused only mild skin toxicity (CTC, grade 1). Chemotherapy led to a partial response (> 30% reduction, according to RECIST) of the target lesions and disappearance of the peritoneal carcinomatosis as shown by computed tomography. Partial response occurred after 17 weeks of treatment and remained stable during the entire course of chemotherapy for 9.7 months. In parallel, Ca 19-9 serum levels, which were elevated 5-fold at time of diagnosis, returned to normal after 16 weeks of treatment. The performance status stabilized and intravenous alimentation could be discontinued. Conclusion Our experience from one patient with CC suggests, that a combination of cytotoxic chemotherapy together with cetuximab may show promising efficacy in respect to survival and quality of life. Therefore cetuximab, as a component of palliative chemotherapy in biliary tract cancer, needs further evaluation in prospective randomized trials.

Abstract Background Combination therapy of irinotecan, folinic acid (FA) and 5-fluorouracil (5-FU) has been proven to be highly effective for the treatment of metastatic colorectal cancer. However, in light of safety and efficacy concerns, the best combination regimen for first-line therapy still needs to be defined. The current study reports on the bimonthly FOLFIRI protocol consisting of irinotecan with continuous FA/5-FU in five German outpatient clinics, with emphasis on the safety and efficiency, quality of life, management of delayed diarrhea, and secondary resection of regressive liver metastases. Methods A total of 35 patients were treated for metastatic colorectal cancer. All patients received first-line treatment according to the FOLFIRI regimen, consisting of irinotecan (180 mg/m2), L-FA (200 mg/m2) and 5-FU bolus (400 mg/m2) on day 1, followed by a 46-h continuous infusion 5-FU (2400 mg/m2). One cycle contained three fortnightly administrations. Staging was performed after 2 cycles. Dosage was reduced at any time if toxicity NCI CTC grade III/IV was observed. Chemotherapy was administered only to diarrhea-free patients. Results The FOLFIRI regimen was generally well tolerated. It was postponed for one-week in 51 of 415 applications (12.3%). Dose reduction was necessary in ten patients. Grade III/IV toxicity was rare, with diarrhea (14%), nausea/vomiting (12%), leucopenia (3%), neutropenia (9%) and mucositis (3%). The overall response rate was 31% (4 CR and 7 PR), with disease control in 74%. After primary chemotherapy, resection of liver metastases was achieved in three patients. In one patient, the CR was confirmed pathologically. Median progression-free and overall survival were seven and 17 months, respectively. Conclusions The FOLFIRI regimen proved to be safe and efficient. Outpatient treatment was well tolerated. Since downstaging was possible, combinations of irinotecan and continuous FA/5-FU should further be investigated in neoadjuvant protocols.

Abstract Background Clinically significant portal hypertension (CSPH) has been identified as an important prognostic factor in patients with hepatocellular carcinoma (HCC) undergoing curative treatment. This study aimed to assess PH estimates as prognostic factors in patients with HCC treated with immunotherapy. Methods All patients with HCC treated with an immunotherapeutic agent in first or subsequent lines at our tertiary care center between 2016 and 2021 were included (n = 50). CSPH was diagnosed using the established PH score for non-invasive PH estimation in pre-treatment CT data (cut-off ≥ 4). Influence of PH on overall survival (OS) and progression-free survival (PFS) was assessed in uni- and multivariable analyses. Results Based on the PH score, 26 patients (52.0%) were considered to have CSPH. After treatment initiation, patients with CSPH had a significantly impaired median OS (4.1 vs 33.3 months, p

Abstract Background Synechocystis sp. PCC 6803 utilizes pyruvate and glyceraldehyde 3-phosphate via the methylerythritol 4-phosphate (MEP) pathway for the biosynthesis of terpenoids. Considering the deep connection of the MEP pathway to the central carbon metabolism, and the low carbon partitioning towards terpenoid biosynthesis, significant changes in the metabolic network are required to increase cyanobacterial production of terpenoids. Results We used the Hfq-MicC antisense RNA regulatory tool, under control of the nickel-inducible P nrsB promoter, to target 12 different genes involved in terpenoid biosynthesis, central carbon metabolism, amino acid biosynthesis and ATP production, and evaluated the changes in the performance of an isoprene-producing cyanobacterial strain. Six candidate targets showed a positive effect on isoprene production: three genes involved in terpenoid biosynthesis (crtE, chlP and thiG), two involved in amino acid biosynthesis (ilvG and ccmA) and one involved in sugar catabolism (gpi). The same strategy was applied to interfere with different parts of the terpenoid biosynthetic pathway in a bisabolene-producing strain. Increased bisabolene production was observed not only when interfering with chlorophyll a biosynthesis, but also with carotenogenesis. Conclusions We demonstrated that the Hfq-MicC synthetic tool can be used to evaluate the effects of gene knockdown on heterologous terpenoid production, despite the need for further optimization of the technique. Possible targets for future engineering of Synechocystis aiming at improved terpenoid microbial production were identified.

Abstract Background Increasing physical activity is one of the most promising and challenging interventions to delay or prevent cognitive decline and dementia. Methods We conducted a randomized controlled trial to assess the effects of a physical activity intervention, aimed at increasing step count, in elderly with low levels of physical activity on measures of strength, balance, aerobic capacity, and cognition. Participants were assigned to 9 months of exercise counseling or active control. Results The intention-to-treat analyses show that the intervention, compared to control, increases the level of physical activity, but has no significant effect on physical fitness and cognition. Those who increased their physical activity with 35% or more show significant improvements in aerobic capacity, gait speed, verbal memory, executive functioning, and global cognition, compared to those who did not achieve a 35% increase. Limitations The number of participants that achieved the intended improvement was lower than expected. Conclusion Responder analyses suggest an improvement of physical fitness and cognition in those who achieved an increase in physical activity of at least 35%. Trial registration The trial protocol is registered at the Dutch Trial Register NL5675, August 1, 2016.

Abstract Background Histone lactylation has been recently described as a novel histone post-translational modification linking cellular metabolism to epigenetic regulation. Results Given the expected relevance of this modification and current limited knowledge of its function, we generate genome-wide datasets of H3K18la distribution in various in vitro and in vivo samples, including mouse embryonic stem cells, macrophages, adipocytes, and mouse and human skeletal muscle. We compare them to profiles of well-established histone modifications and gene expression patterns. Supervised and unsupervised bioinformatics analysis shows that global H3K18la distribution resembles H3K27ac, although we also find notable differences. H3K18la marks active CpG island-containing promoters of highly expressed genes across most tissues assessed, including many housekeeping genes, and positively correlates with H3K27ac and H3K4me3 as well as with gene expression. In addition, H3K18la is enriched at active enhancers that lie in proximity to genes that are functionally important for the respective tissue. Conclusions Overall, our data suggests that H3K18la is not only a marker for active promoters, but also a mark of tissue specific active enhancers.

Abstract Background Early tumor shrinkage (ETS) has been identified as a promising imaging biomarker for patients undergoing immunotherapy for several cancer entities. This study aimed to validate the potential of ETS as an imaging biomarker for patients undergoing immunotherapy for hepatocellular carcinoma (HCC). Methods We screened all patients with HCC that received immunotherapy as the first or subsequent line of treatment at our tertiary care center between 2016 and 2021. ETS was defined as the reduction in the sum of the sizes of target lesions, between the initial imaging and the first follow-up. The ETS was compared to the radiologic response, according to the modified response evaluation criteria in solid tumors (mRECIST). Furthermore, we evaluated the influence of ETS on overall survival (OS), progression-free survival (PFS), and the alpha-fetoprotein (AFP) response. Results The final analysis included 39 patients with available cross-sectional imaging acquired at the initiation of immunotherapy (baseline) and after 8–14 weeks. The median ETS was 5.4%. ETS was significantly correlated with the response according to mRECIST and with the AFP response. Patients with an ETS ≥10% had significantly longer survival times after the first follow-up, compared to patients with

Abstract Background Patients with liver cirrhosis suffer from significantly reduced health-related quality of life and are often dependent on support from caregivers. In this context, caregivers often suffer from impaired quality of life (QoL) as well as psychosocial burden (PB). The aim of the present study was to identify factors influencing QoL and PB of caregivers in order to improve the social care of patients and caregivers. Methods In this cross-sectional study, 106 patients with liver cirrhosis and their caregivers were included. (Health-related) QoL was surveyed in patients (CLDQ) and caregivers (SF-36) and PB was determined by Zarit Burden Interview. Results Alcohol related liver cirrhosis (55%) was the predominant etiology of liver cirrhosis and the median MELD of the cohort was 14. QoL did not differ between patients with and without alcohol-related liver cirrhosis (p = 0.6). In multivariable analysis, continued alcohol consumption (p = 0.020), a history of hepatic encephalopathy (HE) (p = 0.010), poorer QoL of patients (p = 0.030) and poorer QoL of caregivers (p = 0.005) were associated with a higher PB of caregivers. Factors independently associated with poorer QoL of caregivers were continued alcohol consumption (p = 0.003) and a higher PB of caregivers (p = 0.030). Conclusion Caregivers of patients with liver cirrhosis suffer from impaired QoL and PB, especially in case of continued alcohol consumption or the occurrence of HE.

Abstract Background The PAGE-B score (Platelet Age GEnder–HBV) selects chronic hepatitis B (cHB) patients showing no relevant 5-year risk for hepatocellular carcinoma (HCC). We, therefore, explored potential cost reduction following the introduction of a PAGE-B tailored ultrasound screening in a single center cohort of cHB patients receiving stable antiviral therapy. Methods cHB patients attending throughout the year 2018 were documented. Patients eligible for PAGE-B score were classified into high (≥18 points), intermediate (10–17 points) and low (≤9 points) HCC risk groups. Patients of the low HCC risk group could postpone HCC screening to reduce HCC screening expenses. Full costs for hepatic ultrasound were assessed. Results Throughout the year cHB patients (n = 607) attended our clinic, which included PAGE-B eligible patients (n = 227, 37.4%) of whom n = 94 (15.8%) were allocated to the low HCC risk group. Sonographic HCC screening during a median exam time of 12.4 min (IQR 9.2–17.2) resulted in total costs of 22.82 Euro/exam. Additional opportunistic expenses caused by patient’s lost earnings or productivity were 15.6–17.5 €/exam and 26.7 €/exam, respectively. Following a PAGE-B tailored HCC screening at our institution annual full costs for cHB patients could be reduced by 15.51%, which equals a cost reduction by 1.91% for our total sonography unit. In comparison, 1.35% up to 7.65% of HBV-infected patients of Caucasian descent could postpone HCC screening according to population-based estimates from Germany. Conclusions PAGE-B risk score adapted screening for HCC is an efficient and cost neutral tool to reduce costs for sonography in Caucasian patients with chronic hepatitis B receiving antiviral treatment.

Abstract Background The study evaluated the cost of baroreflex activation therapy plus guideline directed therapy (BAT + GDT) compared to GDT alone for HF patients with reduced ejection fraction and New York Heart Association Class III or II (with a recent history of III). Baroreflex activation therapy (BAT) is delivered by an implantable device that stimulates the baroreceptors through an electrode attached to the outside of the carotid artery, which rebalances the autonomic nervous system to regain cardiovascular (CV) homeostasis. The BeAT-HF trial evaluated the safety and effectiveness of BAT. Methods A cost impact model was developed from a U.S. health care payer or integrated delivery network perspective over a 3-year period for BAT + GDT versus GDT alone. Expected costs were calculated by utilizing 6-month data from the BeAT-HF trial and existing literature. HF hospitalization rates were extrapolated based on improvement in NT-proBNP. Results At baseline the expected cost of BAT + GDT were $29,526 per patient more than GDT alone due to BAT device and implantation costs. After 3 years, the predicted cost per patient was $9521 less expensive for BAT + GDT versus GDT alone due to lower rates of significant HF hospitalizations, CV non-HF hospitalizations, and resource intensive late-stage procedures (LVADs and heart transplants) among the BAT + GDT group. Conclusions BAT + GDT treatment becomes less costly than GDT alone beginning between years 1 and 2 and becomes less costly cumulatively between years 2 and 3, potentially providing significant savings over time. As additional BeAT-HF trial data become available, the model can be updated to show longer term effects.

Abstract Background Midwifery care plays a vital role in the reduction of preventable maternal and newborn mortality and morbidity. There is a growing concern about the quality of care during facility based childbirth and the occurrence of disrespect and abuse (D&A) worldwide. While several studies have reported a high prevalence of D&A, evidence about the drivers of D&A is scarce. This study aims to explore midwives’ professional identity and perspectives on the occurrence of D&A in urban Mozambique. Methods A qualitative study took place in the central hospital of Maputo, Mozambique. Nine focus group discussions with midwives were conducted, interviewing 54 midwives. RQDA software was used for analysing the data by open coding and thematic analysis from a grounded theory perspective. Results Midwives felt proud of their profession but felt they were disrespected by the institution and wider society because of their inferior status compared to doctors. Furthermore, they felt blamed for poor health outcomes. The occurrence of D&A seemed more likely in emergency situations but midwives tended to blame this on women being “uncooperative”. The involvement of birth companions was a protective factor against D&A together with supervision. Conclusion In order to improve quality of care and reduce the occurrence of D&A midwives will need to be treated with more respect within the health system. Furthermore, they should be trained in handling obstetric emergency situations with respect and dignity for the patient. Systematic and constructive supervision might be another promising strategy for preventing D&A.

Abstract Background The role of the male partner and wider family in maternal health, especially in case of emergencies, has been receiving increasing attention over the last decade. Qualitative research has highlighted that women depend on others to access high quality maternity care. Currently little is known about these factors in relation to maternal health in Mozambique. Methods A cross sectional household survey was conducted with men and women in southern Mozambique about decision making, financial support and knowledge of danger signs. A multivariable logistic model was used to identify factors associated with knowledge of danger signs and Cohen’s kappa for agreement among couples. Results A total of 775 men and women from Marracuene and Manhica districts were interviewed. Maternal health care decisions were frequently made jointly by the couple (32–49%) and financial support was mainly provided by the man (46–80%). Parental and parent-in-law involvement in decision making and financial support was minimal (0–3%). The average number of danger signs respondents knew was 2.05 and no significant difference (p = 0.294) was found between men and women. Communication with the partner was a significant predictor for higher knowledge of danger signs for both men (p = 0.01) and women (p = 0.03). There was very low agreement within couples regarding decision making (p = 0.04), financial support (p = 0.01) and presence at antenatal care consultations (p = 0.001). Results suggest women and men have a high willingness for more male participation in antenatal care, although their understanding of what constitutes this participation is not clear. Conclusion The study findings highlight the important role men play in decision making and financial support for maternal health care issues. Strengthening male involvement in antenatal care services, by investing in counselling and receiving couples, could help accelerate gains in maternal health in Mozambique. Maternal health care studies should collect more data from men directly as men and women often report different views and behavior regarding maternal health care issues and male involvement.

Abstract Background Patients with liver cirrhosis often suffer from complications such as ascites, gastrointestinal bleeding, and infections, resulting in impaired quality of life. Frequently, the close relatives of patients also suffer from a lower quality of life in chronic diseases. In recent years, acute-to-chronic liver failure has been defined as a separate entity with high mortality. Often several organs are affected which makes intensive care therapy necessary. Little is known about the influence of acute-on-chronic-liver failure (ACLF) on the quality of life of patients and the psychosocial burden on close relatives. Aim The purpose of this prospective study is to investigate the influence of decompensated liver cirrhosis and the onset of ACLF of the patient’s’ quality of life and the psychosocial burden of close relatives. Method In this non – randomized prospective cohort study a total of 63 patients with acute decompensation of liver cirrhosis and hospital admission were enrolled in the study. To assess the quality of life of patients, the disease specific CLDQ questionnaire was assessed. In addition. Quality of life and psychosocial burden of first degree relatives was measured using the generic SF-36 questionnaire as well as the Zarit Burden Score. Results 21 of the 63 patients suffered from ACLF. Patients with ACLF showed a lower quality of life in terms of worries compared to patients with only decompensated liver cirrhosis (3,57 ± 1,17 vs. 4,48 ± 1,27; p value: 0,008) and increased systemic symptoms (3,29 ± 1,19 vs. 4,48 ± 1,58; p value: 0,004). The univariate analysis confirmed the link between the existence of an ACLF and the concerns of patients. (p value: 0,001). The organ failure score was significantly associated with overall CLDQ scores, especially with worries and systemic symptoms of patients. Interestingly the psychosocial burden and quality of life of close relative correlates with patient’s quality of life and was influenced by the onset of an acute-on-chronic liver failure. Conclusion Patients with decompensated liver cirrhosis suffer from impaired quality of life. In particular, patients with ACLF have a significantly reduced quality of life. The extent of the psychosocial burden on close relative correlates with poor quality of life in patients with decompensated liver disease and is influenced by the existence of ACLF.

Abstract Background Evidence suggests that many women experience mistreatment during childbirth in health facilities across the world, but the magnitude of the problem is unknown. The occurrence of disrespect and abuse (D&A) in maternity care services affects the overall quality of care and may undermine women’s trust in the health system. Studies about the occurrence of disrespect and abuse in Mozambican health facilities are scarce. The aim of this study was to explore the experience of women giving birth in hospital in different settings in Maputo City and Province, Mozambique. Methods A cross sectional descriptive survey was conducted between April and June 2018 in the Central Hospital of Maputo (HCM) and district hospitals of Manhiça and Marracuene, Maputo Province, Mozambique. Five hundred seventy-two exit interviews were conducted with women leaving the hospital after delivery. The questionnaire consisted of the following components: socio-demographic characteristics, the occurrence of disrespect and abuse, male involvement during labor and childbirth and intrapartum family planning counselling and provision. Results Prevalence of disrespect and abuse ranged from 24% in the central hospital to 80% in the district hospitals. The main types of D&A reported were lack of confidentiality/privacy, being left alone, being shouted at/scolded, and being given a treatment without permission. While very few women’s partners attended the births, the majority of women (73-80%) were in favor of involving their partner as a birth companion. Intrapartum counseling of family planning was very low (9-17%). Conclusion The occurrence of disrespect and abuse was much higher in the district hospitals compared to the central hospital, emphasizing the high need for interventions outside Maputo City. Allowing male partners as birth companions should be explored further, as women seem in favor of involving their partners. Investing in intrapartum counselling for family planning is currently a missed opportunity for improving the uptake of contraception in the country.

Abstract Background Increasing male involvement during pregnancy is considered an important, but often overlooked intervention for improving maternal health in sub-Saharan Africa. Intervention studies aimed at improving maternal health mostly target mothers hereby ignoring the crucial role their partners play in their ability to access antenatal care (ANC) and to prevent and treat infectious diseases like HIV and malaria. Very little is known about the current level of male involvement and barriers at different levels. This study explores the attitudes and beliefs of health policymakers, health care providers and local communities regarding men’s involvement in maternal health in southern Mozambique. Methods Ten key informant interviews with stakeholders were carried out to assess their attitudes and perspectives regarding male involvement in programmes addressing maternal health, followed by 11 days of semi structured observations in health care centers. Subsequently 16 focus group discussions were conducted in the community and at provider level, followed by three in depth couple interviews. Analysis was done by applying a socio-ecological systems theory in thematic analysis. Results Results show a lack of strategy and coherence at policy level to stimulate male involvement in maternal health programmes. Invitation cards for men are used as an isolated intervention in health facilities but these have not lead to the expected success. Providers have a rather passive attitude towards male involvement initiatives. In the community however, male attendance at ANC is considered important and men are willing to take a more participating role. Main barriers are the association of male attendance at ANC with being HIV infected and strong social norms and gender roles. On the one hand men are seen as caretakers of the family by providing money and making the decisions. On the other hand, men supporting their wife by showing interest in their health or sharing household tasks are seen as weak or as a manifestation of HIV seropositivity. Conclusion A clear strategy at policy level and a multi-level approach is needed. Gender-equitable relationships between men and women should be encouraged in all maternal health interventions and providers should be trained to involve men in ANC.

Abstract Background Mismatch repair (MMR)-deficiency increases the risk of colorectal tumorigenesis. To determine whether the tumors develop on a normal or disturbed epigenetic background and how radiation affects this, we quantified genome-wide histone H3 methylation profiles in macroscopic normal intestinal tissue of young radiated and untreated MMR-deficient VCMsh2 LoxP/LoxP (Msh2 −/− ) mice months before tumor onset. Results Histone H3 methylation increases in Msh2 −/− compared to control Msh2 +/+ mice. Activating H3K4me3 and H3K36me3 histone marks frequently accumulate at genes that are H3K27me3 or H3K4me3 modified in Msh2 +/+ mice, respectively. The genes recruiting H3K36me3 enrich in gene sets associated with DNA repair, RNA processing, and ribosome biogenesis that become transcriptionally upregulated in the developing tumors. A similar epigenetic effect is present in Msh2 +/+ mice 4 weeks after a single-radiation hit, whereas radiation of Msh2 −/− mice left their histone methylation profiles almost unchanged. Conclusions MMR deficiency results in genome-wide changes in histone H3 methylation profiles preceding tumor development. Similar changes constitute a persistent epigenetic signature of radiation-induced DNA damage.

Abstract Background To date, the cornerstone of treatment in patients with advanced or metastatic cholangiocarcinoma (CCA) is systemic chemotherapy based on a combination of gemcitabine and a platinum derivative. Other therapeutic approaches including targeted agents and tyrosine kinase inhibitors (TKI) have demonstrated disappointing results, highlighting the complexity of CCA. Recently, drugs aiming at the inhibition of HER-receptors have shown first therapeutic benefit in patients with late stage disease. The aim of this phase I study was to test the dose level toxicities (DLTs), safety and efficacy of afatinib, a highly specific panErbB family receptor TKI, in chemotherapy naive patients with advanced CCA in conjunction with an extensive biomarker program. Methods Afatinib was administered continuously p. o. as add-on in patients with advanced CCA who received conventional chemotherapy with gemcitabine/cisplatin. A classical 3 + 3 phase I study was employed, while the maximum tolerated dose (MTD) of oral afatinib was determined in a 2 step dose escalation. Safety, overall survival (OS) and progression free survival (PFS) were evaluated for all patients. Finally, a translational biomarker analysis was conducted for the EGFR and VEGF signalling cascades. Results Overall, 9 patients were enrolled. Further recruitment was discontinued due to lack of efficacy results of the tested drug in other indications. 30 mg afatinib could be safely administered as add-on to 80% of standard dose gemcitabine/cisplatin. The mOS and mPFS were 7.7 and 6.0 months, respectively. Diarrhoea and haematological disorders were the most common observed AEs. Almost all patients overexpressed EGFR on their tumour tissues, whereas none of them expressed mutations in Exons 18, 19 and 21. Non-responders showed a higher variation of VEGF-C, −D, leptin and sEGFR in their sera. Conclusions Afatinib failed to show survival benefits in combination with gemcitabine/cisplatin in patients with advanced CCA. Mutational analysis of EGFR and pathways associated with VEGF-C, −D and leptin might show promising results in future studies. Clinical trials registration NCT01679405 August, 2012.

Abstract Background In Mozambique, both the government and partners have undertaken efforts over the last decade to improve FP (family planning) services, especially through training health care providers and promoting the uptake of LARCs (Long Acting Reversible Contraceptives). Despite this, uptake of FP methods has not increased significantly. This study aims to examine women’s knowledge on LARCs, including their main sources of information, and the quality of care of FP services in rural areas. Methods We conducted a repeated cross-sectional study, interviewing 417 women leaving FP consultations in 15 health facilities in Maputo Province, Mozambique. The main quality outputs measured were: 1)discussed, preferred and received contraceptive methods, 2)information received on usage and side-effects, 3)client-provider interaction, 4)being informed about the need for a follow-up visit 5)health examinations conducted and travel time to the facility. In addition, knowledge on LARCs was measured among the clients as well as sources of information regarding FP methods. Taking into account the design effect of the study, Chi-square statistics were used to detect differences between groups and linear regression analyses to identify associations between sources of information and higher knowledge. Results We found that IUDs (intrauterine devices) and implants were discussed in 23 and 33% of the consultations respectively, but only administered in a very few cases(

Abstract Background The uptake of findings from sexual and reproductive health and rights research into policy-making remains a complex and non-linear process. Different models of research utilisation and guidelines to maximise this in policy-making exist, however, challenges still remain for researchers to improve uptake of their research findings and for policy-makers to use research evidence in their work. Methods A participatory workshop with researchers was organised in November 2017 by the Academic Network for Sexual and Reproductive Health and Rights Policy (ANSER) to address this gap. ANSER is a consortium of experienced researchers, some of whom have policy-making experience, working on sexual and reproductive health and rights issues across 16 countries and 5 continents. The experiential learning cycle was used to guide the workshop discussions based on case studies and to encourage participants to focus on key lessons learned. Workshop findings were thematically analysed using specific stages from Hanney et al.’s (Health Res Policy Syst 1:2, 2003) framework on the place of policy-making in the stages of assessment of research utilisation and outcomes. Results The workshop identified key strategies for translating research into policy, including joint agenda-setting between researchers and policy-makers, as well as building trust and partnerships with different stakeholders. These were linked to stages within Hanney et al.’s framework as opportunities for engaging with policy-makers to ensure uptake of research findings. Conclusion The engagement of stakeholders during the research development and implementation phases, especially at strategic moments, has a positive impact on uptake of research findings. The strategies and stages described in this paper can be applied to improve utilisation of research findings into policy development and implementation globally.

Abstract Background Many gait impairments are characterized by asymmetry and result in reduced mobility. Exoskeletons could be useful for restoring gait symmetry by assisting only one leg. However, we still have limited understanding of the effects of unilateral exoskeleton assistance. Our aim was to compare the effects of unilateral and bilateral assistance using a within-subject study design. Methods Eleven participants walked in different exoskeleton conditions. In the Unilateral conditions, only one leg was assisted. In Bilateral Matched Total Work, half of the assistance from the Unilateral conditions was applied to both legs such that the bilateral sum was equal to that of the Unilateral conditions. In Bilateral Matched Work Per Leg, the same assistance as in the Unilateral conditions was provided to both legs such that the bilateral sum was the double of that of the Unilateral conditions. In the Powered-Off condition, no assistance was provided. We measured metabolic energy consumption, exoskeleton mechanics and kinematics. Results On average, the Unilateral, Bilateral Matched Total Work and Bilateral Matched Work Per Leg conditions reduced the metabolic rate by 7, 11 and 15%, respectively, compared with the Powered-Off condition. A possible explanation for why the Unilateral conditions effectively reduced the metabolic rate could be that they caused only very little asymmetry in gait biomechanics, except at the ankle and in the horizontal center-of-mass velocity. We found the highest ratio of metabolic rate reduction versus positive work assistance with bilateral assistance and low work per leg (Bilateral Matched Total Work). Statistical analysis indicated that assistance symmetry and assistance per leg are more important than the bilateral summed assistance for reducing the metabolic rate of walking. Conclusions These data bridge the gap between conclusions from studies with unilateral and bilateral exoskeletons and inform how unilateral assistance can be used to influence gait parameters, such as center-of-mass velocity.

Abstract Background In hepatocellular carcinoma (HCC), the third leading cause of cancer-related mortality worldwide, the Child-Turcotte-Pugh score (CTP) is one of the most established tools to assess hepatic reserve and determine survival. Serum levels of insulin-like growth factor-1 (IGF-1) are decreased in patients with chronic liver disease or HCC. A modified score combining circulating IGF-1 with the CTP score (IGF-CTP) was recently proposed. Methods IGF-CTP scoring was evaluated in 216 patients diagnosed with HCC between 2007 and 2017 to assess the predictive value of serum IGF-1 levels for patient risk stratification and overall survival (OS). Results Liver cirrhosis was identified in 80.1% of the study cohort, and alcohol-induced liver disease was the most frequent underlying cause of HCC (44.4%). Serum IGF-1 levels were significantly lower in patients with HCC in cirrhosis compared with non-cirrhotic HCC (p

Abstract Background Transarterial chemoembolisation is the standard of care for intermediate stage (BCLC B) hepatocellular carcinoma, but it is challenging to decide when to repeat or stop treatment. Here we performed the first external validation of the SNACOR (tumour Size and Number, baseline Alpha-fetoprotein, Child-Pugh and Objective radiological Response) risk prediction model. Methods A total of 1030 patients with hepatocellular carcinoma underwent transarterial chemoembolisation at our tertiary referral centre from January 2000 to December 2016. We determined the following variables that were needed to calculate the SNACOR at baseline: tumour size and number, alpha-fetoprotein level, Child-Pugh class, and objective radiological response after the first transarterial chemoembolisation. Overall survival, time-dependent area under receiver-operating characteristic curves, Harrell’s C-index, and the integrated Brier score were calculated to assess predictive ability. Finally, multivariate analysis was performed to identify independent predictors of survival. Results The study included 268 patients. Low, intermediate, and high SNACOR scores predicted a median survival of 31.5, 19.9, and 9.2 months, respectively. The areas under the receiver-operating characteristic curve for overall survival were 0.641, 0.633, and 0.609 at 1, 3, and 6 years, respectively. Harrell’s C-index was 0.59, and the integrated Brier Score was 0.175. Independent predictors of survival included tumour size (P

Abstract Many active European volcanoes and volcano observatories are island-based and located far from their administrative “mainland”. Consequently, Governments have developed multisite approaches, in which monitoring is performed by a network of individuals distributed across several national research centers. At a transnational level, multinational networks are also progressively emerging. Piton de la Fournaise (La Réunion Island, France) is one such example. Piton de la Fournaise is one of the most active volcanoes of the World, and is located at the greatest distance from its “mainland” than any other vulnerable “overseas” site, the observatory being 9365 km from its governing body in Paris. Effusive risk is high, so that a well-coordinated and rapid response involving near-real time delivery of trusted, validated and operational product for hazard assessment is critical. Here we review how near-real time assessments of lava flow propagation were developed using rapid provision, and update, of key source terms through a dynamic and open integration of near-real time remote sensing, modeling and measurement capabilities on both the national and international level. The multi-national system evolved during the five effusive crises of 2014–2015, and is now mature for Piton de la Fournaise. This review allows us to identify strong and weak points in an extended observatory system, and demonstrates that enhanced multi-national integration can have fundamental implications in scientific hazard assessment and response during an on-going effusive crisis.

Abstract Backrgound Good progress is being made towards universal access to contraceptives, however stock-outs still jeopardize progress. A seldom considered but important building block in optimizing supply management is the degree to which health workers feel motivated and responsible for monitoring supply. We explored how and to what extent motivation can be improved, and the impact this can have on avoiding stock-outs. Methods Fifteen health facilities in Maputo Province, Mozambique, were divided into 3 groups (2 intervention groups and 1 control), and 10 monthly audits were implemented in each of these 15 facilities to collect data through examination of stock cards and stock-counts of 6 contraceptives. Based on these audits, the 2 intervention groups received a monthly evaluation report reflecting the quality of their supply management. One of these 2 groups was also awarded material incentives conditional on their performance. A Wilcoxon-Mann Whitney test was used to detect differences between the groups in the average number of stocked-out centres, while changes over time were verified through applying a Friedman test. Additionally, staff motivation was measured through interviewing health care providers of all centres at baseline, and after 5 and 10 months. To detect differences between the groups and changes over time, a Kruskal Wallis and a Wilcoxon signed-rank test were applied, respectively. Results Motivation reported by providers (n = 55, n = 40 and n = 39 at baseline, 1st and 2nd follow-up respectively) was high in all groups, during all rounds, and did not change over time. Facilities in the intervention groups had better supply management results (including less stock-outs) during the entire intervention period compared with those in the control group, but the difference was only significant for the group receiving both material incentives and a monthly evaluation. However, our data also suggest that supply management also improved in control facilities, receiving only a monthly audit. During this study, more stock-outs occurred for family planning methods with lower demand, but the number of stock-outs per family planning method in the intervention groups was only significantly lower, compared with the control group, for female condoms. Conclusions While a rise in motivation was not measurable, stock management was enhanced possibly as a result of the monthly audits. This activity was primarily for data collection, but was described as motivating and supportive, indicating the importance of feedback on health workers’ accomplishments. More research is needed to quantify the additional impact of the interventions (distribution of evaluation reports and material incentives) on staff motivation and supply management. Special attention should be paid to supply management of less frequently used contraceptive methods.

Abstract Background Powered ankle-foot exoskeletons can reduce the metabolic cost of human walking to below normal levels, but optimal assistance properties remain unclear. The purpose of this study was to test the effects of different assistance timing and power characteristics in an experiment with a tethered ankle-foot exoskeleton. Methods Ten healthy female subjects walked on a treadmill with bilateral ankle-foot exoskeletons in 10 different assistance conditions. Artificial pneumatic muscles assisted plantarflexion during ankle push-off using one of four actuation onset timings (36, 42, 48 and 54% of the stride) and three power levels (average positive exoskeleton power over a stride, summed for both legs, of 0.2, 0.4 and 0.5 W∙kg−1). We compared metabolic rate, kinematics and electromyography (EMG) between conditions. Results Optimal assistance was achieved with an onset of 42% stride and average power of 0.4 W∙kg−1, leading to 21% reduction in metabolic cost compared to walking with the exoskeleton deactivated and 12% reduction compared to normal walking without the exoskeleton. With suboptimal timing or power, the exoskeleton still reduced metabolic cost, but substantially less so. The relationship between timing, power and metabolic rate was well-characterized by a two-dimensional quadratic function. The assistive mechanisms leading to these improvements included reducing muscular activity in the ankle plantarflexors and assisting leg swing initiation. Conclusions These results emphasize the importance of optimizing exoskeleton actuation properties when assisting or augmenting human locomotion. Our optimal assistance onset timing and average power levels could be used for other exoskeletons to improve assistance and resulting benefits.