Annalen Bleckmann

Impact of frailty on short- and long-term morbidity and mortality after transcatheter aortic valve implantation: risk assessment by Katz Index of activities of daily living.

AIMS Transcatheter aortic valve implantation (TAVI) represents a less invasive treatment option for elderly patients. Therefore, we aimed to determine the impact of frailty measured by the Katz Index of activities of daily living (ADL) on short- and long-term mortality after TAVI. METHODS AND RESULTS Our study included 300 consecutive patients (mean age, 82±5 years) who had undergone TAVI at our institution (158 transapical, 142 transfemoral procedures). At baseline, 144 patients were impaired in at least one ADL and therefore defined as frail (Katz Index <6). Regarding in-hospital outcome, all serious complications except for stage 3 acute kidney injury were equally distributed in both groups, but early mortality was significantly higher in frail persons (5.5% vs. 1.3%, p=0.04 for immediate procedural mortality; 17% vs. 5.8%, p=0.002 for 30-day mortality; and 23% vs. 6.4%, p<0.0001 for procedural mortality). The risk-score-based 30-day mortality estimates (29% vs. 24% for log. EuroSCORE I, 9.5% vs. 7.5% for EuroSCORE II, and 8.8% vs. 5.9% for STS score) reflected neither the observed 30-day mortality in both groups nor the threefold risk elevation in frail patients. In contrast, the Katz Index <6 was identified as a significant independent predictor of long-term all-cause mortality by multivariate analysis (HR 2.67 [95% CI: 1.7-4.3], p<0.0001). During follow-up (median observation period 537 days) 56% of frail vs. 24% of non-frail patients died. CONCLUSIONS Frailty status measured by the Katz Index represents a powerful predictor of adverse early and late outcome after TAVI, whereas commonly used risk scores lack calibration and discrimination in a TAVI-specific patient cohort. Therefore, we propose the incorporation of this simple and reproducible measure into pre-TAVI risk assessment.

Tumor-derived microvesicles mediate human breast cancer invasion through differentially glycosylated EMMPRIN

Tumor cells secrete not only a variety of soluble factors, but also extracellular vesicles that are known to support the establishment of a favorable tumor niche by influencing the surrounding stroma cells. Here we show that tumor-derived microvesicles (T-MV) also directly influence the tumor cells by enhancing their invasion in a both autologous and heterologous manner. Neither the respective vesicle-free supernatant nor MV from benign mammary cells mediate invasion. Uptake of T-MV is essential for the proinvasive effect. We further identify the highly glycosylated form of the extracellular matrix metalloproteinase inducer (EMMPRIN) as a marker for proinvasive MV. EMMPRIN is also present at high levels on MV from metastatic breast cancer patients in vivo. Anti-EMMPRIN strategies, such as MV deglycosylation, gene knockdown, and specific blocking peptides, inhibit MV-induced invasion. Interestingly, the effect of EMMPRIN-bearing MV is not mediated by matrix metalloproteinases but by activation of the p38/MAPK signaling pathway in the tumor cells. In conclusion, T-MV stimulate cancer cell invasion via a direct feedback mechanism dependent on highly glycosylated EMMPRIN.

Melusin protects from cardiac rupture and improves functional remodelling after myocardial infarction

AIMS Melusin is a muscle-specific chaperone protein whose expression is required for a compensatory hypertrophy response to pressure overload. Here, we evaluated the consequences of melusin overexpression in the setting of myocardial infarction (MI) using a comprehensive multicentre approach. METHODS AND RESULTS Mice overexpressing melusin in the heart (TG) and wild-type controls (WT) were subjected to permanent LAD ligation and both the acute response (Day 3) and subsequent remodelling (2 weeks) were examined. Mortality in wild-type mice was significant between Days 3 and 7, primarily due to cardiac rupture, but melusins overexpression strongly reduced mortality (43.2% in wild-type vs. 27.3% in melusin-TG, P = 0.005). At Day 3 after MI, a time point preceding the mortality peak, TG hearts had increased heat shock protein 70 expression, increased ERK1/2 signalling, reduced cardiomyocyte hyper-contractility and inflammatory cell infiltrates, and increased matricellular protein expression in the infarcted area. At 2 weeks after MI, melusin overexpression conferred a favourable adaptive remodelling characterized by reduced left ventricle dilatation and better preserved contractility in the presence of a comparable degree of hypertrophy. Adaptive remodelling in melusin TG mice was characterized by reduced apoptosis and fibrosis as well as increased cardiomyocyte contractility. CONCLUSIONS Consistent with its function as a chaperone protein, melusin overexpression exerts a dual protective action following MI reducing an array of maladaptive processes. In the early phase after MI, reduced inflammation and myocyte remodelling protect against cardiac rupture. Chronically, reduced myocyte loss and matrix remodelling, with preserved myocyte contractility, confer adaptive LV remodelling.

Carcinoma cells misuse the host tissue damage response to invade the brain

The metastatic colonization of the brain by carcinoma cells is still barely understood, in particular when considering interactions with the host tissue. The colonization comes with a substantial destruction of the surrounding host tissue. This leads to activation of damage responses by resident innate immune cells to protect, repair, and organize the wound healing, but may distract from tumoricidal actions. We recently demonstrated that microglia, innate immune cells of the CNS, assist carcinoma cell invasion. Here we report that this is a fatal side effect of a physiological damage response of the brain tissue. In a brain slice coculture model, contact with both benign and malignant epithelial cells induced a response by microglia and astrocytes comparable to that seen at the interface of human cerebral metastases. While the glial damage response intended to protect the brain from intrusion of benign epithelial cells by inducing apoptosis, it proved ineffective against various malignant cell types. They did not undergo apoptosis and actually exploited the local tissue reaction to invade instead. Gene expression and functional analyses revealed that the C‐X‐C chemokine receptor type 4 (CXCR4) and WNT signaling were involved in this process. Furthermore, CXCR4‐regulated microglia were recruited to sites of brain injury in a zebrafish model and CXCR4 was expressed in human stroke patients, suggesting a conserved role in damage responses to various types of brain injuries. Together, our findings point to a detrimental misuse of the glial damage response program by carcinoma cells resistant to glia‐induced apoptosis. GLIA 2013;61:1331–1346

The metastatic infiltration at the metastasis/brain parenchyma-interface is very heterogeneous and has a significant impact on survival in a prospective study

The current approach to brain metastases resection is macroscopic removal of metastasis until reaching the glial pseudo-capsule (gross total resection (GTR)). However, autopsy studies demonstrated infiltrating metastatic cells into the parenchyma at the metastasis/brain parenchyma (M/BP)-interface. Aims/Methods: To analyze the astrocyte reaction and metastatic infiltration pattern at the M/BP-interface with an organotypic brain slice coculture system. Secondly, to evaluate the significance of infiltrating metastatic tumor cells in a prospective biopsy study. Therefore, after GTR, biopsies were obtained from the brain parenchyma beyond the glial pseudo-capsule and analyzed histomorphologically. Results: The coculture revealed three types of cancer cell infiltration. Interestingly, the astrocyte reaction was significantly different in the coculture with a benign, neuroectodermal-derived cell line. In the prospective biopsy study 58/167 (34.7%) samples revealed infiltrating metastatic cells. Altogether, 25/39 patients (64.1%) had proven to exhibit infiltration in at least one biopsy specimen with significant impact on survival (OS) (3.4 HR; p = 0.009; 2-year OS was 6.6% versus 43.5%). Exceptionally, in the non-infiltrating cohort three patients were long-term survivors. Conclusions: Metastatic infiltration has a significant impact on prognosis. Secondly, the astrocyte reaction at the M/BP-interface is heterogeneous and supports our previous concept of the organ-specific defense against metastatic (organ-foreign) cells.

Inactivation of Patched1 in mice leads to development of gastrointestinal stromal-like tumors that express Pdgfrα but not kit.

BACKGROUND & AIMS A fraction of gastrointestinal stromal tumor (GIST) cells overexpress the platelet-derived growth factor receptor (PDGFR)A, although most overexpress KIT. It is not known if this is because these receptor tyrosine kinases have complementary oncogenic potential, or because of heterogeneity in the cellular origin of GIST. Little also is known about why Hedgehog (HH) signaling is activated in some GIST. HH binds to and inactivates the receptor protein patched homolog (PTCH). METHODS Ptch was conditionally inactivated in mice (to achieve constitutive HH signaling) using a Cre recombinase regulated by the lysozyme M promoter. Cre-expressing cells were traced using R26R-LacZ reporter mice. Tumors were characterized by in situ hybridization, immunohistochemistry, immunoblot, and quantitative reverse-transcriptase polymerase chain reaction analyses. Cell transformation was assessed by soft agar assay. RESULTS Loss of Ptch from lysozyme M-expressing cells resulted in the development of tumors of GIST-like localization and histology; these were reduced when mice were given imatinib, a drug that targets KIT and PDGFRA. The Hh signaling pathway was activated in the tumor cells, and Pdgfrα, but not Kit, was overexpressed and activated. Lineage tracing revealed that Cre-expressing intestinal cells were Kit-negative. These cells sometimes expressed Pdgfrα and were located near Kit-positive interstitial cells of Cajal. In contrast to KIT, activation of PDGFRA increased anchorage-independent proliferation and was required for tumor formation in mice by cells with activated HH signaling. CONCLUSIONS Inactivation of Ptch in mice leads to formation of GIST-like tumors that express Pdgfrα, but not Kit. Activation of Pdgfrα signaling appears to facilitate tumorigenesis.

Detection of Simultaneous Group Effects in MicroRNA Expression and Related Target Gene Sets

Expression levels of mRNAs are among other factors regulated by microRNAs. A particular microRNA can bind specifically to several target mRNAs and lead to their degradation. Expression levels of both, mRNAs and microRNAs, can be obtained by microarray experiments. In order to increase the power of detecting microRNAs that are differentially expressed between two different groups of samples, we incorporate expression levels of their related target gene sets. Group effects are determined individually for each microRNA, and by enrichment tests and global tests for target gene sets. The resulting lists of p-values from individual and set-wise testing are combined by means of meta analysis. We propose a new approach to connect microRNA-wise and gene set-wise information by means of p-value combination as often used in meta-analysis. In this context, we evaluate the usefulness of different approaches of gene set tests. In a simulation study we reveal that our combination approach is more powerful than microRNA-wise testing alone. Furthermore, we show that combining microRNA-wise results with ‘competitive’ gene set tests maintains a pre-specified false discovery rate. In contrast, a combination with ‘self-contained’ gene set tests can harm the false discovery rate, particularly when gene sets are not disjunct.

Accuracy of prehospital diagnoses by emergency physicians: comparison with discharge diagnosis.

Objective A correct prehospital diagnosis of emergency patients is crucial as it determines initial treatment, admitting specialty, and subsequent treatment. We evaluated the diagnostic accuracy of emergency physicians. Methods All patients seen by six emergency physicians staffing the local emergency ambulance and rescue helicopter services during an 8-month period were studied. The ambulance and helicopter physicians had 3 and 4 years, respectively, training in anesthesia and intensive care medicine. The admission diagnoses were compared with the discharge diagnoses for agreement. Time of day of the emergency call, patients’ age, and sex, living conditions, and presenting symptoms were evaluated as contributing factors. Results Three hundred and fifty-five ambulance and 241 helicopter deployment protocols were analyzed. The overall degree of agreement between initial and discharge diagnoses was 90.1% with no difference attributable to years of experience. The lowest agreement rate was seen in neurological disorders (81.5%), with a postictal state after an unobserved seizure often being diagnosed as a cerebrovascular accident. Inability to obtain a complete medical history (e.g. elderly patients, patients in nursing homes, neurological impairment) was associated with a lower agreement rate between initial and discharge diagnoses (P<0.05). Conclusion Medical history, physical examination, ECG, and blood glucose enabled a correct diagnosis in most cases, but some were impossible to resolve without further technical and laboratory investigations. Only a few were definitively incorrect. A detailed medical history is essential. Neurological disorders can present with misleading symptoms and when the diagnosis is not clear it is better to assume the worst case.

rBiopaxParser—an R package to parse, modify and visualize BioPAX data

MOTIVATION Biological pathway data, stored in structured databases, is a useful source of knowledge for a wide range of bioinformatics algorithms and tools. The Biological Pathway Exchange (BioPAX) language has been established as a standard to store and annotate pathway information. However, use of these data within statistical analyses can be tedious. On the other hand, the statistical computing environment R has become the standard for bioinformatics analysis of large-scale genomics data. With this package, we hope to enable R users to work with BioPAX data and make use of the always increasing amount of biological pathway knowledge within data analysis methods. RESULTS rBiopaxParser is a software package that provides a comprehensive set of functions for parsing, viewing and modifying BioPAX pathway data within R. These functions enable the user to access and modify specific parts of the BioPAX model. Furthermore, it allows to generate and layout regulatory graphs of controlling interactions and to visualize BioPAX pathways. AVAILABILITY rBiopaxParser is an open-source R package and has been submitted to Bioconductor.

Comparative study on gene set and pathway topology-based enrichment methods.

BackgroundEnrichment analysis is a popular approach to identify pathways or sets of genes which are significantly enriched in the context of differentially expressed genes. The traditional gene set enrichment approach considers a pathway as a simple gene list disregarding any knowledge of gene or protein interactions. In contrast, the new group of so called pathway topology-based methods integrates the topological structure of a pathway into the analysis.MethodsWe comparatively investigated gene set and pathway topology-based enrichment approaches, considering three gene set and four topological methods. These methods were compared in two extensive simulation studies and on a benchmark of 36 real datasets, providing the same pathway input data for all methods. ResultsIn the benchmark data analysis both types of methods showed a comparable ability to detect enriched pathways. The first simulation study was conducted with KEGG pathways, which showed considerable gene overlaps between each other. In this study with original KEGG pathways, none of the topology-based methods outperformed the gene set approach. Therefore, a second simulation study was performed on non-overlapping pathways created by unique gene IDs. Here, methods accounting for pathway topology reached higher accuracy than the gene set methods, however their sensitivity was lower.ConclusionsWe conducted one of the first comprehensive comparative works on evaluating gene set against pathway topology-based enrichment methods. The topological methods showed better performance in the simulation scenarios with non-overlapping pathways, however, they were not conclusively better in the other scenarios. This suggests that simple gene set approach might be sufficient to detect an enriched pathway under realistic circumstances. Nevertheless, more extensive studies and further benchmark data are needed to systematically evaluate these methods and to assess what gain and cost pathway topology information introduces into enrichment analysis. Both types of methods for enrichment analysis require further improvements in order to deal with the problem of pathway overlaps.