BRAFΔß3-αC in-frame deletion mutants differ in their dimerization propensity, HSP90 dependence, and druggability.

In-frame BRAF exon 12 deletions are increasingly identified in various tumor types. The resultant BRAFΔß3-αC oncoproteins usually lack five amino acids in the ß3-αC helix linker and sometimes contain de novo insertions. The dimerization status of BRAFΔß3-αC oncoproteins, their precise pathomechanism, and their direct druggability by RAF inhibitors (RAFi) has been under debate. Here, we functionally characterize BRAFΔLNVTAP>F and two novel mutants, BRAFdelinsFS and BRAFΔLNVT>F, and compare them with other BRAFΔß3-αC oncoproteins. We show that BRAFΔß3-αC oncoproteins not only form stable homodimers and large multiprotein complexes but also require dimerization. Nevertheless, details matter as aromatic amino acids at the deletion junction of some BRAFΔß3-αC oncoproteins, e.g., BRAFΔLNVTAP>F, increase their stability and dimerization propensity while conferring resistance to monomer-favoring RAFi such as dabrafenib or HSP 90/CDC37 inhibition. In contrast, dimer-favoring inhibitors such as naporafenib inhibit all BRAFΔß3-αC mutants in cell lines and patient-derived organoids, suggesting that tumors driven by such oncoproteins are vulnerable to these compounds.

Mast cell deficiency prevents BCR::ABL1 induced splenomegaly and cytokine elevation in a CML mouse model.

The persistence of leukemic stem cells (LSCs) represents a problem in the therapy of chronic myeloid leukemia (CML). Hence, it is of utmost importance to explore the underlying mechanisms to develop new therapeutic approaches to cure CML. Using the genetically engineered ScltTA/TRE-BCR::ABL1 mouse model for chronic phase CML, we previously demonstrated that the loss of the docking protein GAB2 counteracts the infiltration of mast cells (MCs) in the bone marrow (BM) of BCR::ABL1 positive mice. Here, we show for the first time that BCR::ABL1 drives the cytokine independent expansion of BM derived MCs and sensitizes them for FcεRI triggered degranulation. Importantly, we demonstrate that genetic mast cell deficiency conferred by the Cpa3Cre allele prevents BCR::ABL1 induced splenomegaly and impairs the production of pro-inflammatory cytokines. Furthermore, we show in CML patients that splenomegaly is associated with high BM MC counts and that upregulation of pro-inflammatory cytokines in patient serum samples correlates with tryptase levels. Finally, MC-associated transcripts were elevated in human CML BM samples. Thus, our study identifies MCs as essential contributors to disease progression and suggests considering them as an additional target in CML therapy. Mast cells play a key role in the pro-inflammatory tumor microenvironment of the bone marrow. Shown is a cartoon summarizing our results from the mouse model. BCR::ABL1 transformed MCs, as part of the malignant clone, are essential for the elevation of pro-inflammatory cytokines, known to be important in disease initiation and progression.

Sugar infusion into trees: A novel method to study tree carbon relations and its regulations.

Many carbon-related physiological questions in plants such as carbon (C) limitation or starvation have not yet been resolved thoroughly due to the lack of suitable experimental methodology. As a first step towards resolving these problems, we conducted infusion experiments with bonsai trees (Ficus microcarpa) and young maple trees (Acer pseudoplatanus) in greenhouse, and with adult Scots pine trees (Pinus sylvestris) in the field, that were "fed" with 13C-labelled glucose either through the phloem or the xylem. We then traced the 13C-signal in plant organic matter and respiration to test whether trees can take up and metabolize exogenous sugars infused. Ten weeks after infusion started, xylem but not phloem infusion significantly increased the δ13C values in both aboveground and belowground tissues of the bonsai trees in the greenhouse, whereas xylem infusion significantly increased xylem δ13C values and phloem infusion significantly increased phloem δ13C values of the adult pines in the field experiment, compared to the corresponding controls. The respiration measurement experiment with young maple trees showed significantly increased δ13C-values in shoot respired CO2 at the time of four weeks after xylem infusion started. Our results clearly indicate that trees do translocate and metabolize exogenous sugars infused, and because the phloem layer is too thin, and thus xylem infusion can be better operated than phloem infusion. This tree infusion method developed here opens up new avenues and has great potential to be used for research on the whole plant C balance and its regulation in response to environmental factors and extreme stress conditions.

The secreted inhibitor of invasive cell growth CREG1 is negatively regulated by cathepsin proteases.

Previous clinical and experimental evidence strongly supports a breast cancer-promoting function of the lysosomal protease cathepsin B. However, the cathepsin B-dependent molecular pathways are not completely understood. Here, we studied the cathepsin-mediated secretome changes in the context of the MMTV-PyMT breast cancer mouse model. Employing the cell-conditioned media from tumor-macrophage co-cultures, as well as tumor interstitial fluid obtained by a novel strategy from PyMT mice with differential cathepsin B expression, we identified an important proteolytic and lysosomal signature, highlighting the importance of this organelle and these enzymes in the tumor micro-environment. The Cellular Repressor of E1A Stimulated Genes 1 (CREG1), a secreted endolysosomal glycoprotein, displayed reduced abundance upon over-expression of cathepsin B as well as increased abundance upon cathepsin B deletion or inhibition. Moreover, it was cleaved by cathepsin B in vitro. CREG1 reportedly could act as tumor suppressor. We show that treatment of PyMT tumor cells with recombinant CREG1 reduced proliferation, migration, and invasion; whereas, the opposite was observed with reduced CREG1 expression. This was further validated in vivo by orthotopic transplantation. Our study highlights CREG1 as a key player in tumor-stroma interaction and suggests that cathepsin B sustains malignant cell behavior by reducing the levels of the growth suppressor CREG1 in the tumor microenvironment.

Item Response Model Validation of the German ICD-11 International Trauma Questionnaire for PTSD and CPTSD.

Background: In the 11th revision of the International Classification of Diseases (ICD-11) posttraumatic stress disorder (PTSD) and the complex variant (CPTSD) were newly conceptualised. The International Trauma Questionnaire (ITQ) was developed as a brief self-report measure to screen for both disorders. The English original version has been rigorously tested and presents convincing psychometric properties. The aim of the current study was to validate the German version by means of item response theory (IRT). Method: This is a secondary analysis of a representative, trauma-exposed adult sample from the German general population (N = 500). 1- and 2-parameter logistic IRT models (i.e. examination on an item level), diagnostic rates and confirmatory factor analyses were calculated. Results: All items showed good model fit and acceptable to good performance aligning with the items of the English original except for item C1 (Long time to calm down) which had a high endorsement rate and a low discriminatory power yielding low information gain. CPTSD diagnostic rate of 3.2% was lower than in comparable literature. Confirmatory factor analysis deemed the six first-order, two second-order factors model superior. Conclusion: Measurement and factorial validity of the German version of the ITQ was confirmed. The German translation matches the English original in most psychometric properties and can thus be used for research and clinical practice.

[Immunosuppression, Surgery, Complication?] / Immunsuppression, Operation, Komplikation?

Immunosuppression, Surgery, Complication? Abstract. Surgical conditions sometimes pose major diagnostic and therapeutic challenges for immunosuppressed patients. Especially in patients suffering from diseases with potential septic emergencies or postoperative complications, the indication for elective surgery should be discussed at an early stage. This is best done across disciplines, involving all experts and the patient.

Deaths caused by malaria in Switzerland 1988-2002.

Despite sophisticated intensive medicine, between one and three malaria-associated deaths occur annually in Switzerland. In this retrospective study, 33 deaths (25 men and 8 women) caused by falciparum malaria reported in Switzerland from 1988 to 2002 were analyzed. The case fatality ratio (CFR) for the falciparum infections for the 15-year period was 1.2%, with a peak of 2.2% in 1991. Sub-Saharan Africa was the source of all the imported fatal infections. Non-immune Europeans had a significantly higher case fatality ratio than the non-Europeans (1.7% versus 0.2%; P < 0.001). Careless use or non-use of prophylaxis, sometimes because of physicians giving unsatisfactory pre-travel advice, and initially missed diagnosis post-travel were factors that contributed to the development of severe infections leading to death. Travelers should be sensitized to the risk of malaria by well-informed general practitioners. Updated information is readily available (www.safetravel.ch). Regarding diagnosis and treatment, greater physician awareness of the disease is needed, and expert advice should be sought without hesitation. Rapid malaria tests may be a useful diagnostic adjunct in centers where microscopic expertise is lacking. Falciparum malaria in a non-immune patient is an emergency requiring immediate treatment.

Multidimensional analysis of learning curves in laparoscopic sigmoid resection: eight-year results.

PURPOSE: The number of operations to reach a plateau phase in colorectal laparoscopic surgery is still under debate. There are few publications reporting on multidimensional assessment of the learning curve, including operation time and complication and conversion rates. The purpose of this study was to define a multidimensional learning curve for sigmoid resection performed by two surgeons with experience in laparoscopic surgery. METHODS: Between 1993 and 2001 from a total of 715 laparoscopic colorectal procedures, two surgeons performed self-educated 338 sigmoid resections. Demographic data, indications for surgery, procedure performed, operation time, frequency and kind of complications, conversion rate, and days to discharge were recorded. The moving average method was used to demonstrate the change of the operation time. The cumulative sum technique was used to chart the changes in the conversion and complication rates. RESULTS: Surgeon A performed 199 and Surgeon B 139 sigmoid resections. The operation time decreased from 225 minutes to 169 minutes after approximately 90 operations for Surgeon A and from 270 minutes to 223 minutes after 110 operations for Surgeon B. Based on a decline in intraoperative complications and conversion rate, the steady state was reached after approximately 70 to 80 interventions for both surgeons. CONCLUSIONS: The assessment of a learning curve should not be limited to measurement of a decrease in operation time but should also include the conversion and complication rates. The cumulative sum technique and moving average method as proposed in this study seem appropriate to evaluate the learning curve in this clinical domain. Our findings might be especially useful for those planning training programs in laparoscopic surgery.