Установка для исследования характеристик теплообменного аппарата

Приведено обоснование актуальности применения методов интенсификации теплообмена. Спроектирована экспериментальная установка для исследования характеристик теплообменного аппарата. Средствами вычислительной гидродинамики проведено экспериментальное исследование теплоотдачи и гидравлического сопротивления в трубах с проволочными винтовыми вставками и вставками пропеллерного типа. Проведен анализ полученных экспериментальных данных. Получены критериальные зависимости.The substantiation of the relevance of the application of heat exchange intensification methods is given. The experimental installation for research the characteristics of the heat exchanger is designed. With the help of computational fluid dynamics, an experimental study of heat transfer and hydraulic resistance in pipes with wire helical inserts and propeller-type inserts was carried out. The obtained experimental data are analyzed. Criterial dependencies are obtained

A Glial Signature and Wnt7 Signaling Regulate Glioma-Vascular Interactions and Tumor Microenvironment.

Gliomas comprise heterogeneous malignant glial and stromal cells. While blood vessel co-option is a potential mechanism to escape anti-angiogenic therapy, the relevance of glial phenotype in this process is unclear. We show that Olig2+ oligodendrocyte precursor-like glioma cells invade by single-cell vessel co-option and preserve the blood-brain barrier (BBB). Conversely, Olig2-negative glioma cells form dense perivascular collections and promote angiogenesis and BBB breakdown, leading to innate immune cell activation. Experimentally, Olig2 promotes Wnt7b expression, a finding that correlates in human glioma profiling. Targeted Wnt7a/7b deletion or pharmacologic Wnt inhibition blocks Olig2+ glioma single-cell vessel co-option and enhances responses to temozolomide. Finally, Olig2 and Wnt7 become upregulated after anti-VEGF treatment in preclinical models and patients. Thus, glial-encoded pathways regulate distinct glioma-vascular microenvironmental interactions

Two-photon microscopic imaging in the vasculature : a sub-cellular window for imaging nitric oxide and thrombus

The domain of the vascular biology is a complex system consisting of different types of blood vessels, cells, and signaling molecules. It is now recognized that these vessels and molecules are part of a subtle regulatory system with differential properties along the vascular tree. Altered production of these molecules is a molecular clue for dysfunctionality of cells or alterations of vessel properties that may lead to various acute and chronic diseases. Current knowledge of such vascular alterations is mostly based on histological studies of isolated samples that have lost their viability. Functional properties of various compounds are still largely unknown. Better understanding of the functionality of these molecules in the context of cardiovascular functioning can increase insight in early stage of disease condition. Thus studying these properties in vivo or in viable arteries ex vivo is indispensable. This thesis focuses on the vessel wall of large murine arteries and cultured cell systems using TPLSM as an imaging tool for studying alterations in vessel wall properties as well as important molecules and their functional consequences. In this thesis, I first addressed the concept of NO imaging in vasculature with a novel method. Nitric oxide analysis with Cu2FL2E in combination with TPLSM allowed specific detection and semi-quantification of endogenous NO production both in vitro and ex vivo. With the use of Cu2FL2 and TPLSM we were able to unravel the structural-functional relationship of NO in the vessel wall. Presence of NO in various vascular cells could be monitored ex vivo for several physiological NO-stimuli. The Cu2FL2E-TPLSM approach provides a valid method to study the role of NO in vascular biology at an unprecedented level and can enable investigation of the regulatory pathways in the complex interplay between NO and vascular (dys)function. In the second part, NO production was studied with TPLSM in murine endotoxemia. Impact of arginine supplementation in wild type and ARG-1 -/- mouse, in NO metabolism was investigated. A disturbed arginine-nitric oxide metabolism is associated with endotoxemia. Therefore, the effect of L-arginine supplementation on eNOS-induced intracellular NO production was studied in wild type and a non-lethal prolonged endotoxemia model in mice. TPLSM revealed that the L-arginine supplementation restored intracellular NO production during endotoxemia. However, further investigation is needed to find out if this NO improves the microcirculation during endotoxemia. Arginase-I also contributes to endothelial dysfunction during endotoxemia as it competes with NOS3 for arginine availability. Therefore, I investigated the effects of cell-specific arginase-1 deficiency on the arginine availability, the NOS3-derived NO production during murine endotoxemia. Arginase-I plays a crucial role in controlling NOS2 during inflammation in endothelial cells. Modulating the arginase activity resulted in an inflammatory response an increased NO production by NOS2. Therefore, modulating arginase activity during endotoxemia needs to aim at restoring the balance between arginase and NOS2 during inflammatory conditions, as this may be the key to an improved endothelial function. In the final part, visualization of fresh thrombus formation has been described using fibrin-targeted peptide conjugated with C-Dot. Thrombosis plays a major role in several vascular diseases and early detection of thrombus formation is a hitherto unmet requirement in clinical practice. Further validation of this method might help in translation of early detection strategy of thrombus in clinical scenario. In general discussion, I contemplate various ideas regarding the topics described and open new avenues and possible future outcomes for application of these novel studies. I conclude that the described techniques (in the forefront of TPLSM imaging) offer a new and different view on healthy and diseased arteries and provide new insight in various structural and functional properties of vessels. Further development of these techniques holds potential for future applications in both a scientific and clinical environment

Two-photon microscopic imaging in the vasculature : a sub-cellular window for imaging nitric oxide and thrombus

The domain of the vascular biology is a complex system consisting of different types of blood vessels, cells, and signaling molecules. It is now recognized that these vessels and molecules are part of a subtle regulatory system with differential properties along the vascular tree. Altered production of these molecules is a molecular clue for dysfunctionality of cells or alterations of vessel properties that may lead to various acute and chronic diseases. Current knowledge of such vascular alterations is mostly based on histological studies of isolated samples that have lost their viability. Functional properties of various compounds are still largely unknown. Better understanding of the functionality of these molecules in the context of cardiovascular functioning can increase insight in early stage of disease condition. Thus studying these properties in vivo or in viable arteries ex vivo is indispensable. This thesis focuses on the vessel wall of large murine arteries and cultured cell systems using TPLSM as an imaging tool for studying alterations in vessel wall properties as well as important molecules and their functional consequences. In this thesis, I first addressed the concept of NO imaging in vasculature with a novel method. Nitric oxide analysis with Cu2FL2E in combination with TPLSM allowed specific detection and semi-quantification of endogenous NO production both in vitro and ex vivo. With the use of Cu2FL2 and TPLSM we were able to unravel the structural-functional relationship of NO in the vessel wall. Presence of NO in various vascular cells could be monitored ex vivo for several physiological NO-stimuli. The Cu2FL2E-TPLSM approach provides a valid method to study the role of NO in vascular biology at an unprecedented level and can enable investigation of the regulatory pathways in the complex interplay between NO and vascular (dys)function. In the second part, NO production was studied with TPLSM in murine endotoxemia. Impact of arginine supplementation in wild type and ARG-1 -/- mouse, in NO metabolism was investigated. A disturbed arginine-nitric oxide metabolism is associated with endotoxemia. Therefore, the effect of L-arginine supplementation on eNOS-induced intracellular NO production was studied in wild type and a non-lethal prolonged endotoxemia model in mice. TPLSM revealed that the L-arginine supplementation restored intracellular NO production during endotoxemia. However, further investigation is needed to find out if this NO improves the microcirculation during endotoxemia. Arginase-I also contributes to endothelial dysfunction during endotoxemia as it competes with NOS3 for arginine availability. Therefore, I investigated the effects of cell-specific arginase-1 deficiency on the arginine availability, the NOS3-derived NO production during murine endotoxemia. Arginase-I plays a crucial role in controlling NOS2 during inflammation in endothelial cells. Modulating the arginase activity resulted in an inflammatory response an increased NO production by NOS2. Therefore, modulating arginase activity during endotoxemia needs to aim at restoring the balance between arginase and NOS2 during inflammatory conditions, as this may be the key to an improved endothelial function. In the final part, visualization of fresh thrombus formation has been described using fibrin-targeted peptide conjugated with C-Dot. Thrombosis plays a major role in several vascular diseases and early detection of thrombus formation is a hitherto unmet requirement in clinical practice. Further validation of this method might help in translation of early detection strategy of thrombus in clinical scenario. In general discussion, I contemplate various ideas regarding the topics described and open new avenues and possible future outcomes for application of these novel studies. I conclude that the described techniques (in the forefront of TPLSM imaging) offer a new and different view on healthy and diseased arteries and provide new insight in various structural and functional properties of vessels. Further development of these techniques holds potential for future applications in both a scientific and clinical environment

The Interplay of Tumor Vessels and Immune Cells Affects Immunotherapy of Glioblastoma

Immunotherapies with immune checkpoint inhibitors or adoptive cell transfer have become powerful tools to treat cancer. These treatments act via overcoming or alleviating tumor-induced immunosuppression, thereby enabling effective tumor clearance. Glioblastoma (GBM) represents the most aggressive, primary brain tumor that remains refractory to the benefits of immunotherapy. The immunosuppressive immune tumor microenvironment (TME), genetic and cellular heterogeneity, and disorganized vasculature hinder drug delivery and block effector immune cell trafficking and activation, consequently rendering immunotherapy ineffective. Within the TME, the mutual interactions between tumor, immune and endothelial cells result in the generation of positive feedback loops, which intensify immunosuppression and support tumor progression. We focus here on the role of aberrant tumor vasculature and how it can mediate hypoxia and immunosuppression. We discuss how immune cells use immunosuppressive signaling for tumor progression and contribute to the development of resistance to immunotherapy. Finally, we assess how a positive feedback loop between vascular normalization and immune cells, including myeloid cells, could be targeted by combinatorial therapies with immune checkpoint blockers and sensitize the tumor to immunotherapy

Dysfunction of mouse cerebral arteries during early aging

Aging leads to a gradual decline in the fidelity of cerebral blood flow (CBF) responses to neuronal activation, resulting in an increased risk for stroke and dementia. However, it is currently unknown when age-related cerebrovascular dysfunction starts or which vascular components and functions are first affected. The aim of this study was to examine the function of microcirculation throughout aging in mice. Microcirculation was challenged by inhalation of 5% and 10% CO2 or by forepaw stimulation in 6-week, 8-month, and 12-month-old FVB/N mice. The resulting dilation of pial vessels and increase in CBF was measured by intravital fluorescence microscopy and laser Doppler fluxmetry, respectively. Neurovascular coupling and astrocytic endfoot Ca2+ were measured in acute brain slices from 18-month-old mice. We did not reveal any changes in CBF after CO2 reactivity up to an age of 12 months. However, direct visualization of pial vessels by in vivo microscopy showed a significant, age-dependent loss of CO2 reactivity starting at 8 months of age. At the same age neurovascular coupling was also significantly affected. These results suggest that aging does not affect cerebral vessel function simultaneously, but starts in pial microvessels months before global changes in CBF are detectable

Targeting Treg cells with GITR activation alleviates resistance to immunotherapy in murine glioblastomas

International audienceAbstract Immune checkpoint blockers (ICBs) have failed in all phase III glioblastoma (GBM) trials. Here, we show that regulatory T (Treg) cells play a key role in GBM resistance to ICBs in experimental gliomas. Targeting glucocorticoid-induced TNFR-related receptor (GITR) in Treg cells using an agonistic antibody (αGITR) promotes CD4 Treg cell differentiation into CD4 effector T cells, alleviates Treg cell-mediated suppression of anti-tumor immune response, and induces potent anti-tumor effector cells in GBM. The reprogrammed GBM-infiltrating Treg cells express genes associated with a Th1 response signature, produce IFNγ, and acquire cytotoxic activity against GBM tumor cells while losing their suppressive function. αGITR and αPD1 antibodies increase survival benefit in three experimental GBM models, with a fraction of cohorts exhibiting complete tumor eradication and immune memory upon tumor re-challenge. Moreover, αGITR and αPD1 synergize with the standard of care treatment for newly-diagnosed GBM, enhancing the cure rates in these GBM models

Arginase-1 deficiency regulates arginine concentrations and NOS2-mediated NO production during endotoxemia

Arginase-1 is an important component of the intricate mechanism regulating arginine availability during immune responses and nitric oxide synthase (NOS) activity. In this study Arg1(fl/fl)/Tie2-Cre(tg/-) mice were developed to investigate the effect of arginase-1 related arginine depletion on NOS2- and NOS3-dependent NO production and jejunal microcirculation under resting and endotoxemic conditions, in mice lacking arginase-1 in endothelial and hematopoietic cells. Arginase-1-deficient mice as compared with control mice exhibited higher plasma arginine concentration concomitant with enhanced NO production in endothelial cells and jejunal tissue during endotoxemia. In parallel, impaired jejunal microcirculation was observed in endotoxemic conditions. Cultured bone-marrow-derived macrophages of arginase-1 deficient animals also presented a higher inflammatory response to endotoxin than control littermates. Since NOS2 competes with arginase for their common substrate arginine during endotoxemia, Nos2 deficient mice were also studied under endotoxemic conditions. As Nos2(-/-) macrophages showed an impaired inflammatory response to endotoxin compared to wild-type macrophages, NOS2 is potentially involved. A strongly reduced NO production in Arg1(fl/fl)/Tie2-Cre(tg/-) mice following infusion of the NOS2 inhibitor 1400W further implicated NOS2 in the enhanced capacity to produce NO production Arg1(fl/fl)/Tie2-Cre(tg/-) mice. Reduced arginase-1 activity in Arg1(fl/fl)/Tie2-Cre(tg/-) mice resulted in increased inflammatory response and NO production by NOS2, accompanied by a depressed microcirculatory flow during endotoxemia. Thus, arginase-1 deficiency facilitates a NOS2-mediated pro-inflammatory activity at the expense of NOS3-mediated endothelial relaxatio

Functional imaging of NO in pre-contracted arteries.

<p>3D reconstruction and luminal diameter measured from explanted murine carotid arteries <i>ex </i><i>vivo</i> using Cu ₂FL2E (20 µM) (<b>a</b>) before precontraction (<b>b</b>) after precontraction with NA, (<b>c</b>) in post NA and ACh stimulation (2.5min), error bars indicate s.d. (n=3), (<b>d</b>) luminal diameter measured from arteries with conditions mentioned in a, b and c, error bars indicate s.d. (n=3).</p

Detection of NO produced in explanted murine carotid arteries <i>ex</i><i>vivo</i> using Cu ₂FL2E (20 µM).

<p>(<b>a</b>) & (<b>b</b>) Magnified images of vessel showing basal NO signal detected after 5 min incubation of Cu ₂FL2E without any stimulus at medial and intimal focal planes, respectively. (<b>c</b>) NO signal detected in smooth muscle cells (SMCs) and (<b>d</b>) endothelial cells (ECs) of the tissue with 5 min incubation of Cu ₂FL2Eand, subsequently 45min incubation of H₂O₂ (150 µM). Scale bar is 50 µm, (<b>e</b>) & (<b>f</b>) Magnified images of vessel showing NO signal detected after 5 min incubation of Cu ₂FL2E and subsequently, 45 min incubation of H₂O₂ (150 µM) in SMCs at medial plane and in ECs at intimal plane respectively, (<b>g</b>) Quantification of spatial distribution of fluorescence intensity as measure of NO in cells of vessel wall stimulated with H₂O₂ (n = 5). (<b>h</b>) Quantification of spatial distribution of fluorescence intensity as measure of NO in cells of vessel wall stimulated with flow (flow rate= 2.1 Pa, time=45min), (n = 5).</p