1,271 research outputs found
Interaction of hemodynamic and metabolic parameters during angiogenesis and angioadaptation
No full textDie strukturelle Adaptation der Gefäßbetten ist mit funktioneller Anpassung,
bedingt durch Interaktionen rheologischer, metabolischer, hämodynamischer und
molekularer Faktoren, assoziiert. Infolgedessen wachsen Gefäße oder werden
zurückgebildet, was eine sich ständig ändernde Sauerstoffverteilung zur Folge
hat. Aufgrund der engen Beziehung zwischen dem Sauerstoffangebot und der
Angioadaptation, ist die Bestimmung lokaler Sauerstoffkonzentration von sehr
großer Bedeutung. Um die lokale Sauerstoffsättigung (SO2) messen zu können,
wurde eine nichtinvasive multispektrale Methode entwickelt. Dieses Verfahren
macht sich die Unterschiede in den Absorptionscharakteristika zwischen Oxy-
und Desoxyhämoglobin für die Messung von SO2 und Hämatokrit während
Intravitalmikroskopie zunutze. Die Sauerstoffsättigung und der Hämatokrit wird
zweidimensional kartiert, die Kalkulation der Werte und die Erstellung der
Bilder erfolgt mithilfe einer Software, die speziell zu diesem Zweck
entwickelt wurde (Saturation of Oxygen Analysis Program=SOAP). Weiterhin wurde
ein mathematisches Modell ausgearbeitet, das die Flusseigenschaften der roten
Blutzellen beschreibt . Eine Analyse ausgewählter, für die Angioadaptation
relevanter, Gene wurde durchgeführt.The structural adaptation of vascular beds is associated with functional
alignment caused by the interaction of hemorheology, metabolics, hemodynamics
and gene expression. In consequence, vessels grow or degenerate, resulting in
an altered oxygen distribution in vascular networks. Because of the close
connection between oxygen availability and angioadaptation, the local oxygen
saturation in microvessels is of prime importance for intravital studies in
terminal vascular beds. In order to obtain vital status of tissues at the
local level a non invasive multispectral approach was developed. This method
based on differences in absorption spectra between oxygenated and deoxygenated
haemoglobin and allows oxygen saturation (SO2) and hematocrit measurement
during trans- and epi-ilumination intravital microscopy. The SO2 and
hematocrit values as 2D map of area under investigation could be calculated
using for this purpose developed analysis software (SOAP). This technique
allows generation of intravascular SO2 and hematocrit images for all vessels
in a microscopic field of view in vivo in different tissues and under
different conditions. Furthermore a two-dimensional computer simulation to
predict trajectories of single red blood cells was developed, since
rheological behaviour of erythrocytes influence oxygen distribution.
Supplementary an analysis angioadaptation related genes VEGFA, TIE2, ANG2 and
ADAMTS was carried out
Avian area vasculosa and CAM as rapid in vivo pro-angiogenic and antiangiogenic models.
No full textAngiogenesis, the development of new blood vessels from preexisting ones, is driven by coordinated signaling pathways governed by specific molecules, hemodynamic forces, and endothelial and periendothelial cells. The processes involve adhesion, migration, and survival machinery within the target endothelial and periendothelial cells. Factors that interfere with any of these processes may therefore influence angiogenesis either positively (pro-angiogenesis) or negatively (antiangiogenesis). The avian area vasculosa (AV) and the avian chorioallantoic membrane (CAM) are two useful tools for studying both angiogenesis and antiangiogenesis since they are amenable to both intravascular and topical administration of target, agents, are relatively rapid assays, and can be adapted very easily to study angiogenesis-dependent processes, such as tumor growth. Both models provide a physiological setting that permits investigation of pro-angiogenic and antiangiogenic agent interactions in vivo
Targeting class IA PI3K isoforms selectively impairs cell growth, survival, and migration in glioblastoma.
No full textThe phosphoinositide 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) pathway is frequently activated in human cancer and plays a crucial role in glioblastoma biology. We were interested in gaining further insight into the potential of targeting PI3K isoforms as a novel anti-tumor approach in glioblastoma. Consistent expression of the PI3K catalytic isoform PI3K p110α was detected in a panel of glioblastoma patient samples. In contrast, PI3K p110β expression was only rarely detected in glioblastoma patient samples. The expression of a module comprising the epidermal growth factor receptor (EGFR)/PI3K p110α/phosphorylated ribosomal S6 protein (p-S6) was correlated with shorter patient survival. Inhibition of PI3K p110α activity impaired the anchorage-dependent growth of glioblastoma cells and induced tumor regression in vivo. Inhibition of PI3K p110α or PI3K p110β also led to impaired anchorage-independent growth, a decreased migratory capacity of glioblastoma cells, and reduced the activation of the Akt/mTOR pathway. These effects were selective, because targeting of PI3K p110δ did not result in a comparable impairment of glioblastoma tumorigenic properties. Together, our data reveal that drugs targeting PI3K p110α can reduce growth in a subset of glioblastoma tumors characterized by the expression of EGFR/PI3K p110α/p-S6
Dynamics of the Developing Chick Chorioallantoic Membrane Assessed by Stereology, Allometry, Immunohistochemistry and Molecular Analysis.
No full textThe chick chorioallantoic membrane (CAM) is a widely used model for the study of angiogenesis, tumour growth, as well as drug efficacy. In spite of this, little is known about the developmental alteration from its appearance to the time of hatching. In the current study the CAM has been studied by classical stereology and allometry. Expression levels of selected angiogenesis-related molecules were estimated by RT-PCR and cell dynamics assessed by proliferation and apoptosis assays. Absolute CAM volume increased from a low of 0.47 ± 0.11 cm3 at embryonic day 8 (E8) to a high of 2.05 ± 0.27 cm3 at E18, and then decreased to 1.6 ± 0.47 cm3 at E20. On allometric analysis, three growth phases were identifiable. Between E8-13 (phase I), the CAM grew fastest; moderately in phase II (E13-18) but was regressing in phase III (E18-20). The chorion, the mesenchyme and the allantoic layers grew fastest in phase I, but moderately in phase II. The mesenchyme grew slowly in phase III while the chorion and allantois were regressing. Chorionic cell volume increased fastest in phase I and was regressing in phase III. Chorionic capillaries grew steadily in phase I and II but regressed in phase III. Both the chorion and the allantois grew by intrinsic cell proliferation as well as recruitment of cells from the mesenchyme. Cell proliferation was prominent in the allantois and chorion early during development, declined after E17 and apoptosis started mainly in the chorion from E14. VEGFR2 expression peaked at E11 and declined steadily towards E20, VEGF peaked at E13 and E20 while HIF 1α had a peak at E11 and E20. Studies targeting CAM growth and angiogenesis need to take these growth phases into consideration
Endoglin inhibition leads to intussusceptive angiogenesis via activation of factors related to COUP-TFII signaling pathway.
No full textAngiogenesis is a highly coordinated, extremely complex process orchestrated by multiple signaling molecules and blood flow conditions. While sprouting mode of angiogenesis is very well investigated, the molecular mechanisms underlying intussusception, the second mode of angiogenesis, remain largely unclear. In the current study two molecules involved in vascular growth and differentiation, namely endoglin (ENG/CD105) and chicken ovalbumin upstream promoter transcription factor II (COUP-TFII) were examined to unravel their specific roles in angiogenesis. Down- respectively up-regulation of both molecules tightly correlates with intussusceptive microvascular growth. Upon ENG inhibition in chicken embryo model, formation of irregular capillary meshwork accompanied by increased expression of COUP-TFII could be observed. This dynamic expression pattern of ENG and COUP-TFII during vascular development and remodeling correlated with formation of pillars and progression of intussusceptive angiogenesis. Similar findings could be observed in mammalian model of acute rat Thy1.1 glomerulonephritis, which was induced by intravenous injection of anti-Thy1 antibody and has shown upregulation of COUP-TFII in initial phase of intussusception, while ENG expression was not disturbed compared to the controls but decreased over the time of pillar formation. In this study, we have shown that ENG inhibition and at the same time up-regulation of COUP-TFII expression promotes intussusceptive angiogenesis
RNA interference screening identifies a novel role for PCTK1/CDK16 in medulloblastoma with c-Myc amplification.
No full textMedulloblastoma (MB) is the most common malignant brain tumor in children and is associated with a poor outcome. cMYC amplification characterizes a subgroup of MB with very poor prognosis. However, there exist so far no targeted therapies for the subgroup of MB with cMYC amplification. Here we used kinome-wide RNA interference screening to identify novel kinases that may be targeted to inhibit the proliferation of c-Myc-overexpressing MB. The RNAi screen identified a set of 5 genes that could be targeted to selectively impair the proliferation of c-Myc-overexpressing MB cell lines: AKAP12 (A-kinase anchor protein), CSNK1α1 (casein kinase 1, alpha 1), EPHA7 (EPH receptor A7) and PCTK1 (PCTAIRE protein kinase 1). When using RNAi and a pharmacological inhibitor selective for PCTK1, we could show that this kinase plays a crucial role in the proliferation of MB cell lines and the activation of the mammalian target of rapamycin (mTOR) pathway. In addition, pharmacological PCTK1 inhibition reduced the expression levels of c-Myc. Finally, targeting PCTK1 selectively impaired the tumor growth of c-Myc-overexpressing MB cells in vivo. Together our data uncover a novel and crucial role for PCTK1 in the proliferation and survival of MB characterized by cMYC amplification
Decrease in VEGF expression induces intussusceptive vascular pruning
No full textDiminution of VEGF level induces vascular tree regression by intussusceptive vascular pruning. This observation may allude to the mechanism underlying the "normalization" of tumor vasculature if treated with antiangiogenic drugs. The mechanism described here gives new insights into the understanding of the processes of vasculature regression and hence provides new and potentially viable targets for antiangiogenic and/or angio-modulating therapies during various pathological processes
Acute Lung Injury Causes Alveolar Stunning Associated With Impaired Alveolo-capillary Gas Exchange
No full textEinige überlegungen zu der zweiten gruppe navigantes in augustins dialog de beata vita
No full textAt the beginning of the series of Augustine’s earliest extant literary works are the three philosophical dialogues Contra Academicos, De beata vita and De ordine, which were composed in the autumn of 386 during Augustine’s otium philosophandi in Cassiciacum. In the introductions of all three works, the marine metaphors are widely used. The author compares human life with a stormy sea and sees as the only salvation the port of philosophy. In beata v. 1. 2 Augutin compares the people to whom philosophy can accommodate with navigantes, which he groups in tria genera. Although the people who belong to the respective group are described in detail, the author does not mention names. This arouses research interest and justifies the attempt to propose a representing person for each group.
The present work sets itself the goal by parallel reading of beata v. 1. 2, with some passages from Cicero’s Epistulae, Tusculanae disputationes and De officiis to make a new proposal. And this in addition to the currently existing assumption that Romanianus, to whom the dialogue Contra Academicos is dedicated, should be considered as a representative of the second group of seafarers. However, the author of the present work now ventures a completely new approach, in which Cicero can be accepted as a representative of this group
Adhesion-induced eosinophil cytolysis requires the receptor-interacting protein kinase 3 (RIPK3)-mixed lineage kinase-like (MLKL) signaling pathway, which is counterregulated by autophagy.
No full textBACKGROUND
Eosinophils are a subset of granulocytes that can be involved in the pathogenesis of different diseases, including allergy. Their effector functions are closely linked to their cytotoxic granule proteins. Release takes place through several different mechanisms, one of which is cytolysis, which is associated with release of intact granules, so-called clusters of free eosinophil granules. The mechanism underlying this activation-induced form of cell death in eosinophils has remained unclear.
OBJECTIVE
We aimed to elucidate the molecular mechanism of eosinophil cytolysis.
METHODS
Isolated blood eosinophils were incubated on glass coverslips coated with intravenous immunoglobulin and inactive complement component 3b. A morphologic characterization of the distinct stages of the proposed cascade was addressed by means of time-lapse automated fluorescence microscopy, electron microscopy, and immunohistochemistry. Experiments with pharmacologic inhibitors were performed to elucidate the sequence of events within the cascade. Tissue samples of patients with eosinophilic skin diseases or eosinophilic esophagitis were used for in vivo analyses.
RESULTS
After eosinophil adhesion, we observed reactive oxygen species production, early degranulation, and granule fusion processes, leading to a distinct morphology exhibiting cytoplasmic vacuolization and, finally, cytolysis. Using a pharmacologic approach, we demonstrate the presence of a receptor-interacting protein kinase 3 (RIPK3)-mixed lineage kinase-like (MLKL) signaling pathway in eosinophils, which, after its activation, leads to the production of high levels of reactive oxygen species in a p38 mitogen-activated protein kinase and phosphatidylinositol 3'-kinase-dependent manner. All these steps are required for cytoplasmic vacuolization and subsequent cytolysis to occur. Interestingly, triggering cytolysis is associated with an induction of autophagy in eosinophils, and additional stimulation of autophagy by means of pharmacologic inhibition of the mechanistic target of rapamycin counterregulates cell death. Moreover, MLKL phosphorylation, cytoplasmic vacuolization, and cytolysis were observed in eosinophils under in vivo inflammatory conditions.
CONCLUSION
We report that adhesion-induced eosinophil cytolysis takes place through RIPK3-MLKL-dependent necroptosis, which can be counterregulated by autophagy
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