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Sonstige beteiligte Institutionen
- Johns Hopkins School of Medicine (18)
- IZKF Nachwuchsgruppe Geweberegeneration für muskuloskelettale Erkrankungen (7)
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ResearcherID
- D-1221-2009 (1)
Background
Colorectal cancer is a leading cause of cancer-related deaths worldwide. The best method to prevent CRC is a colonoscopy. However, not all colon polyps have the risk of becoming cancerous. Therefore, polyps are classified using different classification systems. After the classification, further treatment and procedures are based on the classification of the polyp. Nevertheless, classification is not easy. Therefore, we suggest two novel automated classifications system assisting gastroenterologists in classifying polyps based on the NICE and Paris classification.
Methods
We build two classification systems. One is classifying polyps based on their shape (Paris). The other classifies polyps based on their texture and surface patterns (NICE). A two-step process for the Paris classification is introduced: First, detecting and cropping the polyp on the image, and secondly, classifying the polyp based on the cropped area with a transformer network. For the NICE classification, we design a few-shot learning algorithm based on the Deep Metric Learning approach. The algorithm creates an embedding space for polyps, which allows classification from a few examples to account for the data scarcity of NICE annotated images in our database.
Results
For the Paris classification, we achieve an accuracy of 89.35 %, surpassing all papers in the literature and establishing a new state-of-the-art and baseline accuracy for other publications on a public data set. For the NICE classification, we achieve a competitive accuracy of 81.13 % and demonstrate thereby the viability of the few-shot learning paradigm in polyp classification in data-scarce environments. Additionally, we show different ablations of the algorithms. Finally, we further elaborate on the explainability of the system by showing heat maps of the neural network explaining neural activations.
Conclusion
Overall we introduce two polyp classification systems to assist gastroenterologists. We achieve state-of-the-art performance in the Paris classification and demonstrate the viability of the few-shot learning paradigm in the NICE classification, addressing the prevalent data scarcity issues faced in medical machine learning.
Background
The impact of sex hormones on right and left auricular contractile apparatus function is largely unknown. We evaluated the impact of sex hormones on left and right heart contractility at the level of myocardial filaments harvested from left and right auricles during elective coronary artery bypass surgery.
Methods
150 patients (132 male; 18 female) were enrolled. Preoperative testosterone and estradiol levels were measured with Immunoassay. Calcium induced force measurements were performed with left- and right auricular myofilaments in a skinned fiber model. Correlation analysis was used for comparison of force values and levels of sex hormones and their ratio.
Results
Low testosterone was associated with higher top force values in right-sided myofilaments but not in left-sided myofilaments for both sexes (p = 0.000 in males, p = 0.001 in females). Low estradiol levels were associated with higher top force values in right-sided myofilaments (p 0.000) in females and only borderline significantly associated with higher top force values in males (p 0.056). In females, low estradiol levels correlated with higher top force values in left sided myofilaments (p 0.000). In males, higher Estradiol/Testosterone ratio (E/T ratio) was only associated with higher top force values from right auricular myofilaments (p 0.04) In contrast, in females higher E/T ratio was associated with lower right auricular myofilament top force values (p 0.03) and higher top force values in left-sided myofilaments (p 0.000).
Conclusions
This study shows that patients’ comorbidities influence left and right sided contractility and may blur results concerning influence of sex hormones if not eliminated. A sex hormone dependent influence is obvious with different effects on the left and right ventricle. The E/T ratio and its impact on myofilament top force showed divergent results between genders, and may partially explain gender differences in patients with cardiovascular disease.
Background
Left atrial appendage (LAA) is the origin of most heart thrombi which can lead to stroke or other cerebrovascular event in patients with non-valvular atrial fibrillation (AF). This study aimed to prove safety and low complication rate of surgical LAA amputation using cut and sew technique with control of its effectiveness.
Methods
303 patients who have undergone selective LAA amputation were enrolled in the study in a period from 10/17 to 08/20. The LAA amputation was performed concomitant to routine cardiac surgery on cardiopulmonary bypass with cardiac arrest with or without previous history of AF. The operative and clinical data were evaluated. Extent of LAA amputation was examined intraoperatively by transoesophageal echocardiography (TEE). Six months in follow up, the patients were controlled regarding clinical status and episodes of strokes.
Results
Average age of study population was 69.9 ± 19.2 and 81.9% of patients were male. In only three patients was residual stump after LAA amputation larger than 1 cm with average stump size 0.28 ± 0.34 cm. 3 patients (1%) developed postoperative bleeding. Postoperatively 77 (25.4%) patients developed postoperative AF (POAF), of which 29 (9.6%) still had AF at discharge. On 6 months follow up only 5 patients had NYHA class III and 1 NYHA class IV. Seven patients reported with leg oedema and no patient experienced any cerebrovascular event in early postoperative follow up.
Conclusion
LAA amputation can be performed safely and completely leaving minimal to no LAA residual stump.
Background
Data on the routine use of video-assisted laryngoscopy in peri-operative intubations are rather inconsistent and ambiguous, in part due to small populations and non-uniform outcome measures in past trials. Failed or prolonged intubation procedures are a reason for relevant morbidity and mortality. This study aims to determine whether video-assisted laryngoscopy (with both Macintosh-shaped and hyperangulated blades) is at least equal to the standard method of direct laryngoscopy with respect to the first-pass success rate. Furthermore, validated tools from the field of human factors will be applied to examine within-team communication and task load during this critical medical procedure.
Methods
In this randomized, controlled, three-armed parallel group design, multi-centre trial, a total of more than 2500 adult patients scheduled for perioperative endotracheal intubation will be randomized. In equally large arms, video-assisted laryngoscopy with a Macintosh-shaped or a hyperangulated blade will be compared to the standard of care (direct laryngoscopy with Macintosh blade). In a pre-defined hierarchical analysis, we will test the primary outcome for non-inferiority first. If this goal should be met, the design and projected statistical power also allow for subsequent testing for superiority of one of the interventions.
Various secondary outcomes will account for patient safety considerations as well as human factors interactions within the provider team and will allow for further exploratory data analysis and hypothesis generation.
Discussion
This randomized controlled trial will provide a solid base of data in a field where reliable evidence is of major clinical importance. With thousands of endotracheal intubations performed every day in operating rooms around the world, every bit of performance improvement translates into increased patient safety and comfort and may eventually prevent significant burden of disease. Therefore, we feel confident that a large trial has the potential to considerably benefit patients and anaesthetists alike.
Trial registration
ClincalTrials.gov NCT05228288.
Protocol version
1.1, November 15, 2021.
Background
Perioperative bridging of oral anticoagulation increases the risk of bleeding complications after elective general and visceral surgery. The aim of this study was to explore, whether an individual risk-adjusted bridging regimen can reduce bleeding events, while still protecting against thromboembolic events.
Methods
We performed a quality improvement study comparing bridging parameters and postoperative outcomes before (period 1) and after implementation (period 2) of a new risk-adjusted bridging regimen. The primary endpoint of the study was overall incidence of postoperative bleeding complications during 30 days postoperatively. Secondary endpoints were major postoperative bleeding, minor bleeding, thromboembolic events, postoperative red blood cell transfusion, perioperative length-of-stay (LOS) and in-hospital mortality.
Results
A total of 263 patients during period 1 and 271 patients during period 2 were compared. The included elective operations covered the entire field of general and visceral surgery. The overall incidence of bleeding complications declined from 22.1% during period 1 to 10.3% in period 2 (p < 0.001). This reduction affected both major as well as minor bleeding events (8.4% vs. 4.1%; p = 0.039; 13.7% vs. 6.3%; p = 0.004). The incidence of thromboembolic events remained low (0.8% vs. 1.1%). No changes in mortality or length-of-stay were observed.
Conclusion
It is important to balance the individual thromboembolic and bleeding risks in perioperative bridging management. The risk adjusted bridging regimen reduces bleeding events in general and visceral surgery while the risk of thromboembolism remains comparably low.
The treatment landscape in multiple myeloma (MM) is shifting from genotoxic drugs to immunotherapies. Monoclonal antibodies, immunoconjugates, T-cell engaging antibodies and CART cells have been incorporated into routine treatment algorithms, resulting in improved response rates. Nevertheless, patients continue to relapse and the underlying mechanisms of resistance remain poorly understood. While Impaired death receptor signaling has been reported to mediate resistance to CART in acute lymphoblastic leukemia, this mechanism yet remains to be elucidated in context of novel immunotherapies for MM. Here, we describe impaired death receptor signaling as a novel mechanism of resistance to T-cell mediated immunotherapies in MM. This resistance seems exclusive to novel immunotherapies while sensitivity to conventional anti-tumor therapies being preserved in vitro. As a proof of concept, we present a confirmatory clinical case indicating that the FADD/BID axis is required for meaningful responses to novel immunotherapies thus we report impaired death receptor signaling as a novel resistance mechanism to T-cell mediated immunotherapy in MM.
Transmission of Trypanosoma brucei by tsetse flies involves the deposition of the cell cycle-arrested metacyclic life cycle stage into mammalian skin at the site of the fly’s bite. We introduce an advanced human skin equivalent and use tsetse flies to naturally infect the skin with trypanosomes. We detail the chronological order of the parasites’ development in the skin by single-cell RNA sequencing and find a rapid activation of metacyclic trypanosomes and differentiation to proliferative parasites. Here we show that after the establishment of a proliferative population, the parasites enter a reversible quiescent state characterized by slow replication and a strongly reduced metabolism. We term these quiescent trypanosomes skin tissue forms, a parasite population that may play an important role in maintaining the infection over long time periods and in asymptomatic infected individuals.
Diese retrospektive Studie an der Universitätsklinik Würzburg diente der Beurteilung der longitudinalen Funktion in Bezug auf die Gesamtmortalität bei Patienten mit HFmrEF und HFrEF. Die Gruppierung erfolgte anhand der jeweiligen Baseline LVEF. Eine weitere Unterteilung erfolgte in eine ischämische oder nicht-ischämische Genese der HF. Die Subgruppen wurden anhand der Baseline klinischen Charakteristika sowie der echokardiographischen Parameter verglichen. Hier ließ sich ein relativ ähnliches Patientenklientel mit vergleichbarem Alter, Geschlecht, BMI sowie kardialen Risikofaktoren zeigen. Signifikante Unterschiede ergab der Vergleich des NYHA-Stadiums, der Nierenfunktion sowie des Auftretens von Myokardinfarkten.
Die Veränderung der LVEF über die Zeit hat einen zentralen Stellenwert zur Evaluation des Outcomes von Patienten mit HFmrEF und HFrEF. Eine Verbesserung der LVEF fand sich signifikant häufiger bei HFrEF Patienten als bei HFmrEF Patienten, welche über die Zeit signifikant häufiger eine stabile LVEF aufwiesen.
Außerdem war nach Auswertung der Überlebenskurven nach Kaplan-Meier in HFmrEF Patienten eine verbesserte oder unveränderte LVEF über die Zeit mit einem besseren Überleben verbunden, vor allem bei Patienten mit ischämischer Ätiologie. In der HFrEF Gruppe konnte gezeigt werden, dass sowohl Patienten mit ischämischer als auch mit nicht-ischämischer Ätiologie bei Vorliegen einer verbesserten oder unveränderten LVEF über die Zeit ein besseres Outcome aufwiesen.
Eine erniedrigte MAPSE bedeutete vor allem bei HFmrEF Patienten mit nicht-ischämischer Ätiologie ein schlechteres Outcome.
Die Ergebnisse dienten unter anderem der weiteren Charakterisierung der HFmrEF und HFrEF Gruppe sowie der Identifikation von Faktoren zur Beurteilung der Veränderung der LVEF über die Zeit und der Prognose des Langzeitüberlebens beider Gruppen. Ziel für die Zukunft sollte sein, auch für HFmrEF Patienten evidenzbasierte Herzinsuffizienz Therapien zu etablieren.
In vitro models mimic the tissue-specific anatomy and play essential roles in personalized medicine and disease treatments. As a sophisticated manufacturing technology, 3D printing overcomes the limitations of traditional technologies and provides an excellent potential for developing in vitro models to mimic native tissue. This thesis aims to investigate the potential of a high-resolution 3D printing technology, melt electrowriting (MEW), for fabricating in vitro models. MEW has a distinct capacity for depositing micron size fibers with a defined design. In this thesis, three approaches were used, including 1) extending the MEW polymer library for different biomedical applications, 2) developing in vitro models for evaluation of cell growth and migration toward the different matrices, and 3) studying the effect of scaffold designs and biochemical cues of microenvironments on cells.
First, we introduce the MEW processability of (AB)n and (ABAC)n segmented copolymers, which have thermally reversible network formulation based on physical crosslinks. Bisurea segments are combined with hydrophobic poly(dimethylsiloxane) (PDMS) or hydrophilic poly(propylene oxide)-poly(ethylene oxide)-poly(propylene oxide) (PPO-PEG-PPO) segments to form the (AB)n segmented copolymers. (ABAC)n segmented copolymers contain all three segments: in addition to bisurea, both hydrophobic and hydrophilic segments are available in the same polymer chain, resulting in tunable mechanical and biological behaviors. MEW copolymers either support cells attachment or dissolve without cytotoxic side effects when in contact with the polymers at lower concentrations, indicating that this copolymer class has potential in biological applications. The unique biological and surface properties, transparency, adjustable hydrophilicity of these copolymers could be beneficial in several in vitro models.
The second manuscript addresses the design and development of a melt electrowritten competitive 3D radial migration device. The approach differs from most of the previous literature, as MEW is not used here to produce cell invasive scaffolds but to fabricate an in vitro device. The device is utilized to systematically determine the matrix which promotes cell migration and growth of glioblastoma cells. The glioblastoma cell migration is tested on four different Matrigel concentrations using a melt electrowritten radial device. The glioblastoma U87 cell growth and migration increase at Matrigel concentrations 6 and 8 mg mL-1 In the development of this radial device, the accuracy, and precision of melt electrowritten circular shapes were investigated. The results show that the printing speed and design diameter are essential parameters for the accuracy of printed constructs. It is the first instance where MEW is used for the production of in vitro devices.
The influence of biochemical cues and scaffold designs on astrocytes and glioblastoma is investigated in the last manuscript. A fiber comprising the box and triangle-shaped pores within MEW scaffolds are modified with biochemical cues, including RGD and IKVAV peptides using a reactive NCO-sP(EO-stat-PO) macromer. The results show that astrocytes and glioblastoma cells exhibit different phenotypes on scaffold designs and peptide-coated scaffolds.
The hallmark oncoprotein Myc is a major driver of tumorigenesis in various human cancer entities. However, Myc’s structural features make it challenging to develop small molecules against it. A promising strategy to indirectly inhibit the function of Myc is by targeting its interactors. Many Myc-interacting proteins have reported scaffolding functions which are difficult to target using conventional occupancy- driven inhibitors. Thus, in this thesis, the proteolysis targeting chimera (PROTAC) approach was used to target two oncoproteins interacting with Myc which promote the oncogenicity of Myc, Aurora-A and WDR5. PROTACs are bifunctional small molecules that bind to the target protein with one ligand and recruit a cellular E3- ligase with the other ligand to induce target degradation via the ubiquitin- proteasome system. So far, the most widely used E3-ligases for PROTAC development are Cereblon (CRBN) and von Hippel–Lindau tumor suppressor (VHL). Furthermore, there are cases of incompatibility between some E3-ligases and proteins to bring about degradation. Hence there is a need to explore new E3- ligases and a demand for a tool to predict degradative E3-ligases for the target protein in the PROTAC field.
In the first part, a highly specific mitotic kinase Aurora-A degrader, JB170, was developed. This compound utilized Aurora-A inhibitor alisertib as the target ligand and thalidomide as the E3-ligase CRBN harness. The specificity of JB170 and the ternary complex formation was supported by the interactions between Aurora-A and CRBN. The PROTAC-mediated degradation of Aurora-A induced a distinct S- phase defect rather than mitotic arrest, shown by its catalytic inhibition. The finding demonstrates that Aurora-A has a non-catalytic role in the S-phase. Furthermore, the degradation of Aurora-A led to apoptosis in various cancer cell lines.
In the second part, two different series of WDR5 PROTACs based on two protein- protein inhibitors of WDR5 were evaluated. The most efficient degraders from both series recruited VHL as a E3-ligase and showed partial degradation of WDR5. In addition, the degradation efficiency of the PROTACs was significantly affected by the linker nature and length, highlighting the importance of linker length and composition in PROTAC design. The degraders showed modest proliferation defects at best in cancer cell lines. However, overexpression of VHL increased the degradation efficiency and the antiproliferative effect of the PROTACs.
In the last part, a rapamycin-based assay was developed to predict the degradative E3-ligase for a target. The assay was validated using the WDR5/VHL and Aurora- A/CRBN pairs. The result that WDR5 is degraded by VHL but not CRBN and Aurora-A is degraded by CRBN, matches observations made with PROTACs. This technique will be used in the future to find effective tissue-specific and essential E3-ligases for targeted degradation of oncoproteins using PROTACs.
Collectively, the work presented here provides a strategy to improve PROTAC development and a starting point for developing Aurora-A and WDR5 PROTACs for cancer therapy.