Distinct roles of vaccine-induced SARS-CoV-2-specific neutralizing antibodies and T cells in protection and disease.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-specific neutralizing antibodies (NAbs) lack cross-reactivity between SARS-CoV species and variants and fail to mediate long-term protection against infection. The maintained protection against severe disease and death by vaccination suggests a role for cross-reactive T cells. We generated vaccines containing sequences from the spike or receptor binding domain, the membrane and/or nucleoprotein that induced only T cells, or T cells and NAbs, to understand their individual roles. In three models with homologous or heterologous challenge, high levels of vaccine-induced SARS-CoV-2 NAbs protected against neither infection nor mild histological disease but conferred rapid viral control limiting the histological damage. With no or low levels of NAbs, vaccine-primed T cells, in mice mainly CD8+ T cells, partially controlled viral replication and promoted NAb recall responses. T cells failed to protect against histological damage, presumably because of viral spread and subsequent T cell-mediated killing. Neither vaccine- nor infection-induced NAbs seem to provide long-lasting protective immunity against SARS-CoV-2. Thus, a more realistic approach for universal SARS-CoV-2 vaccines should be to aim for broadly cross-reactive NAbs in combination with long-lasting highly cross-reactive T cells. Long-lived cross-reactive T cells are likely key to prevent severe disease and fatalities during current and future pandemics.

The D ~ Sense ex-vivo viability assay application in a patient with stage IV lung adenocarcinoma: a case report.

BACKGROUND: The treatment resistance is a problem for lung cancer. In this study, we used a vitro tissue culturing system to select a new therapy strategy for a patient with tyrosine kinase inhibitors (TKIs) resistance. CASE PRESENTATION: A 42-year-old male Asian patient was diagnosed with advanced lung adenocarcinoma harboring an exon 19 deletion in the epidermal growth factor receptor (EGFR) gene. The patient was treated with Gefitinib, resulting in an almost complete remission for over a year. The patient relapsed after 13 months treatment, and received four cycles of chemotherapy. At 20 months, the patient had developed multiple lung metastases and a solitary cerebellar metastasis. An EGFR T790M mutation was identified in the peripheral blood sample. Subsequent treatment with Osimertinib resulted in a complete response of the intracranial metastasis. By 33 months, the patient had developed a mediastinal tumor mass that responded well to local radiotherapy. By 39 months, an EGFR C797S cis-mutation had been identified and the patient was treated with Brigatinib and Cetuximab. By 44 months, the tumor cells from the pleural effusion had been tested for sensitivity against 30 targeted and cytostatic drugs using the D ~ Sense ex-vivo viability assay. The assay identified 8 drugs with moderate to high sensitivity. Combination therapy of Gemcitabin and Lobaplatin had resulted in disease stabilization. CONCLUSIONS: The case showed that individualized treatment aided by D ~ Sense ex-vivo viability assay can be a viable option for patients with advanced lung adenocarcinoma with pleural effusions.

Fractional Flow Reserve-Guided PCI or Coronary Bypass Surgery for 3-Vessel Coronary Artery Disease: 3-Year Follow-Up of the FAME 3 Trial.

BACKGROUND: Previous studies comparing percutaneous coronary intervention (PCI) with coronary artery bypass grafting (CABG) in patients with multivessel coronary disease not involving the left main have shown significantly lower rates of death, myocardial infarction (MI), or stroke after CABG. These studies did not routinely use current-generation drug-eluting stents or fractional flow reserve (FFR) to guide PCI. METHODS: FAME 3 (Fractional Flow Reserve versus Angiography for Multivessel Evaluation) is an investigator-initiated, multicenter, international, randomized trial involving patients with 3-vessel coronary artery disease (not involving the left main coronary artery) in 48 centers worldwide. Patients were randomly assigned to receive FFR-guided PCI using zotarolimus drug-eluting stents or CABG. The prespecified key secondary end point of the trial reported here is the 3-year incidence of the composite of death, MI, or stroke. RESULTS: A total of 1500 patients were randomized to FFR-guided PCI or CABG. Follow-up was achieved in >96% of patients in both groups. There was no difference in the incidence of the composite of death, MI, or stroke after FFR-guided PCI compared with CABG (12.0% versus 9.2%; hazard ratio [HR], 1.3 [95% CI, 0.98-1.83]; P=0.07). The rates of death (4.1% versus 3.9%; HR, 1.0 [95% CI, 0.6-1.7]; P=0.88) and stroke (1.6% versus 2.0%; HR, 0.8 [95% CI, 0.4-1.7]; P=0.56) were not different. MI occurred more frequently after PCI (7.0% versus 4.2%; HR, 1.7 [95% CI, 1.1-2.7]; P=0.02). CONCLUSIONS: At 3-year follow-up, there was no difference in the incidence of the composite of death, MI, or stroke after FFR-guided PCI with current-generation drug-eluting stents compared with CABG. There was a higher incidence of MI after PCI compared with CABG, with no difference in death or stroke. These results provide contemporary data to allow improved shared decision-making between physicians and patients with 3-vessel coronary artery disease. REGISTRATION: URL: https://www. CLINICALTRIALS: gov; Unique identifier: NCT02100722.

AtlasGrabber: a software facilitating the high throughput analysis of the human protein atlas online database.

BACKGROUND: The human protein atlas (HPA) is an online database containing large sets of protein expression data in normal and cancerous tissues in image form from immunohistochemically (IHC) stained tissue microarrays. In these, the tissue architecture is preserved and thus provides information on the spatial distribution and localization of protein expression at the cellular and extracellular levels. The database is freely available online through the HPA website but currently without support for large-scale screening and analysis of the images in the database. Features like spatial information are typically lacking in gene expression datasets from homogenized tissues or single-cell analysis. To enable high throughput analysis of the HPA database, we developed the AtlasGrabber software. It is available freely under an open-source license. Based on a predefined gene list, the software fetches the images from the database and displays them for the user. Several filters for specific antibodies or images enable the user to customize her/his image analysis. Up to four images can be displayed simultaneously, which allows for the comparison of protein expression between different tissues and between normal and cancerous tissues. An additional feature is the XML parser that allows the extraction of a list of available antibodies, images, and genes for specific tissues or cancer types from the HPA's database file. RESULTS: Compared to existing software designed for a similar purpose, ours provide more functionality and is easier to use. To demonstrate the software's usability, we identified six new markers of basal cells of the prostate. A comparison to prostate cancer showed that five of them are absent in prostate cancer. CONCLUSIONS: The HPA is a uniquely valuable database. By facilitating its usefulness with the AtlasGrabber, we enable researchers to exploit its full capacity. The loss of basal cell markers is diagnostic for prostate cancer and can help refine the histopathological diagnosis of prostate cancer. As proof of concept, with the AtlasGrabber we identified five new potential biomarkers specific for prostate basal cells which are lost in prostate cancer and thus can be used for prostate cancer diagnostics.

COVID-19 instigates adipose browning and atrophy through VEGF in small mammals.

Patients with COVID-19 frequently manifest adipose atrophy, weight loss and cachexia, which significantly contribute to poor quality of life and mortality1,2. Browning of white adipose tissue and activation of brown adipose tissue are effective processes for energy expenditure3-7; however, mechanistic and functional links between SARS-CoV-2 infection and adipose thermogenesis have not been studied. In this study, we provide experimental evidence that SARS-CoV-2 infection augments adipose browning and non-shivering thermogenesis (NST), which contributes to adipose atrophy and body weight loss. In mouse and hamster models, SARS-CoV-2 infection activates brown adipose tissue and instigates a browning or beige phenotype of white adipose tissues, including augmented NST. This browning phenotype was also observed in post-mortem adipose tissue of four patients who died of COVID-19. Mechanistically, high levels of vascular endothelial growth factor (VEGF) in the adipose tissue induces adipose browning through vasculature-adipocyte interaction. Inhibition of VEGF blocks COVID-19-induced adipose tissue browning and NST and partially prevents infection-induced body weight loss. Our data suggest that the browning of adipose tissues induced by COVID-19 can contribute to adipose tissue atrophy and weight loss observed during infection. Inhibition of VEGF signaling may represent an effective approach for preventing and treating COVID-19-associated weight loss.

Proteomic Analysis of Pleural Effusions from COVID-19 Deceased Patients: Enhanced Inflammatory Markers.

Critically ill COVID-19 patients with pleural effusion experience longer hospitalization, multisystem inflammatory syndrome, and higher rates of mortality. Generally, pleural effusion can serve as a diagnostic value to differentiate cytokine levels. This study aimed to evaluate the pleural effusions of COVID-19 deceased patients for 182 protein markers. Olink® Inflammation and Organ Damage panels were used to determine the level of 184 protein markers, e.g., ADA, BTC, CA12, CAPG, CD40, CDCP1, CXCL9, ENTPD2, Flt3L, IL-6, IL-8, LRP1, OSM, PD-L1, PTN, STX8, and VEGFA, which were raised significantly in COVID-19 deceased patients, showing over-stimulation of the immune system and ravaging cytokine storm. The rises of DPP6 and EDIL3 also indicate damage caused to arterial and cardiovascular organs. Overall, this study confirms the elevated levels of CA12, CD40, IL-6, IL-8, PD-L1, and VEGFA, proposing their potential either as biomarkers for the severity and prognosis of the disease or as targets for therapy. Particularly, this study reports upregulated ADA, BTC, DPP6, EDIL3, LIF, ENTPD2, Flt3L, and LRP1 in severe COVID-19 patients for the first time. Pearson's correlation coefficient analysis indicates the involvement of JAK/STAT pathways as a core regulator of hyperinflammation in deceased COVID-19 patients, suggesting the application of JAK inhibitors as a potential efficient treatment.

Minimally invasive apical cannulation and cannula design for short-term mechanical circulatory support devices.

BACKGROUND: Refractory cardiogenic shock is still a major clinical challenge with high mortality rates, although several devices can be used to conquer this event. These devices have different advantages and disadvantages originating from their insertion or cannulation method, therefore many complications can occur during their use. The aim of our study was to develop and create prototypes of a novel minimal invasively insertable, transapical cannula for surgical ventricular assist devices, which uniquely incorporates the inflow and outflow routes for the blood of the patient in itself, therefore it enables the use for only one cannula for patients in cardiogenic shock. METHODS: To define the available space for the planned cannula in the left ventricle and ascending aorta, we analyzed computed tomography scans of 24 heart failure patients, who were indicated to left ventricular assist device therapy. Parallel to these measurements, hydrodynamical calculations were performed to determine the sizes of the cannulas, which were necessary to provide effective cardiac output. RESULTS: After the designing steps, we produced prototypes of double-lumened, tube-in-tube apically insertable devices for three different patient groups, which included a separated venous and an arterial part using 3D modelling and printing technology. All the created cannulas are able to provide 5 l/min circulatory support. CONCLUSION: As a result of our research we created a sizing method based on the specific analysis of computed tomography pictures of end stage heart failure patients and a cannula concept, which can provide effective antegrade flow for patients in cardiogenic shock. We believe the improved version of our tool could have a significant therapeutic role in the future after further development based on animal and in vivo tests.

Revision Stapedotomies: The Role of Periprosthetic Scar Tissue Formation in the Development of Unsatisfactory Hearing Results after Stapedotomy

Abstract Introduction Revision stapes surgeries are difficult to perform, and their audiological results are inferior to primary surgeries. Objective Our goal was to identify the most common and most influential postoperative reasons that cause persistent air-bone gap (ABG) after the primary surgery. Our focus was concentrated on the mechanical dysfunctions in the middle ear, with special regard to postoperative adhesion formation. Methods We performed a retrospective case series study with 23 cases that underwent revision stapedotomies. Results A significant improvement was seen in ABG and air conduction levels after surgery. The periprosthetic adhesion formation was seen in 65% of the cases, and it was the primary cause behind the unsatisfactory hearing result in 30% of cases. There was no significant difference in the level of persistent ABGs after the primary surgery, in case of the intratympanic adhesion presence, compared with the presence of other surgical failures. Concerning hearing and ABG gain after revision surgery, the non-inferiority of the negative effect associated with adhesion was shown compared with the other reasons. Conclusion The revision stapedotomy is an efficient treatment option in case of persistent ABG. Periprosthetic adhesions are the most common intratympanic reasons for compromised audiological outcomes after stapedotomy.

Revision Stapedotomies: The Role of Periprosthetic Scar Tissue Formation in the Development of Unsatisfactory Hearing Results after Stapedotomy.

Introduction Revision stapes surgeries are difficult to perform, and their audiological results are inferior to primary surgeries. Objective Our goal was to identify the most common and most influential postoperative reasons that cause persistent air-bone gap (ABG) after the primary surgery. Our focus was concentrated on the mechanical dysfunctions in the middle ear, with special regard to postoperative adhesion formation. Methods We performed a retrospective case series study with 23 cases that underwent revision stapedotomies. Results A significant improvement was seen in ABG and air conduction levels after surgery. The periprosthetic adhesion formation was seen in 65% of the cases, and it was the primary cause behind the unsatisfactory hearing result in 30% of cases. There was no significant difference in the level of persistent ABGs after the primary surgery, in case of the intratympanic adhesion presence, compared with the presence of other surgical failures. Concerning hearing and ABG gain after revision surgery, the non-inferiority of the negative effect associated with adhesion was shown compared with the other reasons. Conclusion The revision stapedotomy is an efficient treatment option in case of persistent ABG. Periprosthetic adhesions are the most common intratympanic reasons for compromised audiological outcomes after stapedotomy. Adhesion formations have the same negative effect on ABG development as any other surgical failure, and the revision could be more challenging in these cases. These findings highlight the use of the most atraumatic surgical technique and preservation of intact intratympanic mucosa during middle ear surgery.

Early postoperative gustatory dysfunction after middle ear surgery / Korai posztoperatív ízérzészavar középfülsebészeti beavatkozásokat követoen

Introduction: Preserving maximal quality of life is an important factor in middle ear surgery according to current standards. Taste disturbance is a common postoperative complication, which can be explained with the risk of injury due to the localisation of chorda tympani. The knowledge about this complication is mandatory for optimal surgical decision-making and for patient education as well. Objective: Investigation of early postoperative taste disturbances, to clarify the differences between the impact of different surgical interventions, and the impact of nerve manipulation. Methods: 15 stapes surgeries and 28 tympanoplasties were investigated. Patients answered subjective questionnaires before surgery and on the first postoperative day. Visual analogue scale (VAS) was used to measure the degree of disturbances (0-10). Degree of nerve manipulation was classified into 5 groups. Results: No significant differences between the impact of stapes surgeries and tympanoplasties could be found (9, 9.1; p = 0.861). In groups '0', '1' and '2', the VAS scores were 10, 9.26, and 8.5. Between the groups no manipulation (0) and significant manipulation without macroscopic injury (2), the difference was significant (10, 8.5; p = 0.039). In the stapes surgery group, no severe taste disturbance (VAS<5) was found. Discussion: In the case of adequate microscopic surgical technique, the rate of postoperative taste disturbances is relatively low. Conclusions: The rate of postoperative taste disturbance could be kept at a low level while the continuity of the chorda tympani could be preserved in the majority of cases. The postoperative morbidity rate is primarily influenced by the degree of nerve manipulation and not by the type of surgery.

Morphological changes without histological myocarditis in hearts of COVID-19 deceased patients.

Objective. Patients with underlying heart diseases have a higher risk of dying from Covid-19. It has also been suggested that Covid-19 affects the heart through myocarditis. Despite the rapidly growing research on the management of Covid-19 associated complications, most of the ongoing research is focused on the respiratory complications of Covid-19, and little is known about the prevalence of myocarditis. Design. This study aimed to characterize myocardial involvement by using a panel of antibodies to detect hypoxic and inflammatory changes and the presence of SARS-CoV-2 proteins in heart tissues obtained during the autopsy procedure of Covid-19 deceased patients. Thirty-seven fatal COVID-19 cases and 21 controls were included in this study. Results. Overall, the Covid-19 hearts had several histopathological changes like the waviness of myocytes, fibrosis, contract band necrosis, infiltration of polymorphonuclear neutrophils, vacuolization, and necrosis of myocytes. In addition, endothelial damage and activation were detected in heart tissue. However, viral replication was not detected using RNA in situ hybridization. Also, lymphocyte infiltration, as a hallmark of myocarditis, was not seen in this study. Conclusion. No histological sign of myocarditis was detected in any of our cases; our findings are thus most congruent with the hypothesis of the presence of a circulating endothelium activating factor such as VEGF, originating outside of the heart, probably from the hypoxic part of the Covid-19 lungs.

Fractional Flow Reserve-Guided PCI as Compared with Coronary Bypass Surgery.

BACKGROUND: Patients with three-vessel coronary artery disease have been found to have better outcomes with coronary-artery bypass grafting (CABG) than with percutaneous coronary intervention (PCI), but studies in which PCI is guided by measurement of fractional flow reserve (FFR) have been lacking. METHODS: In this multicenter, international, noninferiority trial, patients with three-vessel coronary artery disease were randomly assigned to undergo CABG or FFR-guided PCI with current-generation zotarolimus-eluting stents. The primary end point was the occurrence within 1 year of a major adverse cardiac or cerebrovascular event, defined as death from any cause, myocardial infarction, stroke, or repeat revascularization. Noninferiority of FFR-guided PCI to CABG was prespecified as an upper boundary of less than 1.65 for the 95% confidence interval of the hazard ratio. Secondary end points included a composite of death, myocardial infarction, or stroke; safety was also assessed. RESULTS: A total of 1500 patients underwent randomization at 48 centers. Patients assigned to undergo PCI received a mean (±SD) of 3.7±1.9 stents, and those assigned to undergo CABG received 3.4±1.0 distal anastomoses. The 1-year incidence of the composite primary end point was 10.6% among patients randomly assigned to undergo FFR-guided PCI and 6.9% among those assigned to undergo CABG (hazard ratio, 1.5; 95% confidence interval [CI], 1.1 to 2.2), findings that were not consistent with noninferiority of FFR-guided PCI (P = 0.35 for noninferiority). The incidence of death, myocardial infarction, or stroke was 7.3% in the FFR-guided PCI group and 5.2% in the CABG group (hazard ratio, 1.4; 95% CI, 0.9 to 2.1). The incidences of major bleeding, arrhythmia, and acute kidney injury were higher in the CABG group than in the FFR-guided PCI group. CONCLUSIONS: In patients with three-vessel coronary artery disease, FFR-guided PCI was not found to be noninferior to CABG with respect to the incidence of a composite of death, myocardial infarction, stroke, or repeat revascularization at 1 year. (Funded by Medtronic and Abbott Vascular; FAME 3 ClinicalTrials.gov number, NCT02100722.).

Stabilization of the classical phenotype upon integration of pancreatic cancer cells into the duodenal epithelium.

INTRODUCTION: Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive solid tumors. Based on transcriptomic classifiers, basal-like and classical PDAC subtypes have been defined that differ in prognosis. Cells of both subtypes can coexist in individual tumors; however, the contribution of either clonal heterogeneity or microenvironmental cues to subtype heterogeneity is unclear. Here, we report the spatial tumor phenotype dynamics in a cohort of patients in whom PDAC infiltrated the duodenal wall, and identify the duodenal epithelium as a distinct PDAC microniche. MATERIALS AND METHODS: We used serial multiplex quantitative immunohistochemistry (smq-IHC) for 24 proteins to phenotypically chart PDAC tumor cells in patients whose tumors infiltrated the duodenal epithelium. Additionally, we used a genetically engineered mouse model to study the PDAC cell phenotype in the small intestinal epithelium in a controlled genetic background. RESULT: We show that pancreatic cancer cells revert to non-destructive growth upon integration into the duodenal epithelium, where they adopt traits of intestinal cell differentiation, associated with phenotypical stabilization of the classical subtype. The integrated tumor cells replace epithelial cells in an adenoma-like manner, as opposed to invasive growth in the submucosa. Finally, we show that this phenomenon is shared between species, by confirming duodenal integration and phenotypic switching in a genetic PDAC mouse model. DISCUSSION: Our results identify the duodenal epithelium as a distinct PDAC microniche and tightly link microenvironmental cue to cancer transcriptional subtypes. The phenomenon of "intestinal mimicry" provides a unique opportunity for the systematic investigation of microenvironmental influences on pancreatic cancer plasticity.

Mechanistic insights into COVID-19 by global analysis of the SARS-CoV-2 3CLpro substrate degradome.

The main viral protease (3CLpro) is indispensable for SARS-CoV-2 replication. We delineate the human protein substrate landscape of 3CLpro by TAILS substrate-targeted N-terminomics. We identify more than 100 substrates in human lung and kidney cells supported by analyses of SARS-CoV-2-infected cells. Enzyme kinetics and molecular docking simulations of 3CLpro engaging substrates reveal how noncanonical cleavage sites, which diverge from SARS-CoV, guide substrate specificity. Cleaving the interactors of essential effector proteins, effectively stranding them from their binding partners, amplifies the consequences of proteolysis. We show that 3CLpro targets the Hippo pathway, including inactivation of MAP4K5, and key effectors of transcription, mRNA processing, and translation. We demonstrate that Spike glycoprotein directly binds galectin-8, with galectin-8 cleavage disengaging CALCOCO2/NDP52 to decouple antiviral-autophagy. Indeed, in post-mortem COVID-19 lung samples, NDP52 rarely colocalizes with galectin-8, unlike in healthy lungs. The 3CLpro substrate degradome establishes a foundational substrate atlas to accelerate exploration of SARS-CoV-2 pathology and drug design.

Direct contact between Plasmodium falciparum and human B-cells in a novel co-culture increases parasite growth and affects B-cell growth.

BACKGROUND: Plasmodium falciparum parasites cause malaria and co-exist in humans together with B-cells for long periods of time. Immunity is only achieved after repeated exposure. There has been a lack of methods to mimic the in vivo co-occurrence, where cells and parasites can be grown together for many days, and it has been difficult with long time in vitro studies. METHODS AND RESULTS: A new method for growing P. falciparum in 5% CO2 with a specially formulated culture medium is described. This knowledge was used to establish the co-culture of live P. falciparum together with human B-cells in vitro for 10 days. The presence of B-cells clearly enhanced parasite growth, but less so when Transwell inserts were used (not allowing passage of cells or merozoites), showing that direct contact is advantageous. B-cells also proliferated more in presence of parasites. Symbiotic parasitic growth was verified using CESS cell-line and it showed similar results, indicating that B-cells are indeed the cells responsible for the effect. In malaria endemic areas, people often have increased levels of atypical memory B-cells in the blood, and in this assay it was demonstrated that when parasites were present there was an increase in the proportion of CD19 + CD20 + CD27 - FCRL4 + B-cells, and a contraction of classical memory B-cells. This effect was most clearly seen when direct contact between B-cells and parasites was allowed. CONCLUSIONS: These results demonstrate that P. falciparum and B-cells undoubtedly can affect each other when allowed to multiply together, which is valuable information for future vaccine studies.

Pulmonary stromal expansion and intra-alveolar coagulation are primary causes of COVID-19 death.

Most COVID-19 victims are old and die from unrelated causes. Here we present twelve complete autopsies, including two rapid autopsies of young patients where the cause of death was COVID-19 ARDS. The main virus induced pathology was in the lung parenchyma and not in the airways. Most coagulation events occurred in the intra-alveolar and not in the intra-vascular space and the few thrombi were mainly composed of aggregated thrombocytes. The dominant inflammatory response was the massive accumulation of CD163 + macrophages and the disappearance of T killer, NK and B-cells. The virus was replicating in the pneumocytes and macrophages but not in bronchial epithelium, endothelium, pericytes or stromal cells. The lung consolidations were produced by a massive regenerative response, stromal and epithelial proliferation and neovascularization. We suggest that thrombocyte aggregation inhibition, angiogenesis inhibition and general proliferation inhibition may have a roll in the treatment of advanced COVID-19 ARDS.

Cell-type-resolved quantitative proteomics map of interferon response against SARS-CoV-2.

The commonly used laboratory cell lines are the first line of experimental models to study the pathogenicity and performing antiviral assays for emerging viruses. Here, we assessed the tropism and cytopathogenicity of the first Swedish isolate of SARS-CoV-2 in six different human cell lines, compared their growth characteristics, and performed quantitative proteomics for the susceptible cell lines. Overall, Calu-3, Caco2, Huh7, and 293FT cell lines showed a high-to-moderate level of susceptibility to SARS-CoV-2. In Caco2 cells, the virus can achieve high titers in the absence of any prominent cytopathic effect. The protein abundance profile during SARS-CoV-2 infection revealed cell-type-specific regulation of cellular pathways. Type-I interferon signaling was identified as the common dysregulated cellular response in Caco2, Calu-3, and Huh7 cells. Together, our data show cell-type specific variability for cytopathogenicity, susceptibility, and cellular response to SARS-CoV-2 and provide important clues to guide future studies.

Abrasive Sensitivity of Martensitic and a Multi-Phase Steels under Different Abrasive Conditions.

The wear behaviour of two martensitic and one multiphase steel targeted for abrasion and erosion applications in agriculture and mining industry were investigated in three abrasive test systems with different complexity. Scratch tests were performed with different indenter radii, shapes, and loads. The material behaviour was also investigated in multi-asperity contact systems. Pin-on-disc tests were performed with various loads and abrasive particles, as well as abrasive slurry-pot tests with different sliding velocities, distances, and impact angles of the abrasive media were performed. Comparing the test systems, the tested materials ranked similarly based on their wear performance, however, in each configuration, the dominant variable of the wear mechanism differed. The significance and contributions of test paramecenterters, the material's mechanical properties (H, σM, σY, E, εεM, εεB, W, σc, Ec) and the dimensionless numbers formed from them were investigated on the wear behaviour and the surface deformation. Correlation between parameters was established by multiple linear regression models. The sensitivity of the tested materials to abrasion was evaluated taking into account the wide range of influencing parameters.