1,721,038 research outputs found
Editorial for the special issue on “Tissue and cell crosstalk at feto-maternal interface”
No full textDisruption of BMP9 signalling contributes to altered acid ceramidase expression and processing in preeclampsia
No full textSphingolipids are critical bioactive mediators of cellular events. Ceramide (CER) is central to sphingolipid metabolism and its levels are kept in balance via the action of key regulatory enzymes that function by modulating its synthesis and breakdown in a variety of patho-physiological conditions. In particular, lysosomal acid ceramidase (ASAH1) is responsible for hydrolyzing CER into sphingosine (SPH). We have recently reported that altered sphingolipid metabolism in preeclampsia and IUGR, is in part due to impaired TGFß signaling. Bone morphogenetic protein 9 is a member of the TGFß superfamily that functions as a high affinity ligand for the Activin Receptor-like Kinase 1(ALK1) thereby activating R-SMAD1 signalling. Herein, we investigated the role of BMP9 in regulating ASAH1 expression in physiological and pathological conditions. Human choriocarcinoma JEG3 cells were treated with BMP9 (5–10 ng/ml) or control vehicle and examined ASAH1 protein expression by Western Blotting. Exposure of JEG3 cells to BMP9 resulted in increased ASAH1 protein expression. Inhibition of ALK1 signalling using the ALK1 inhibitor Dorsomorphin reversed the BMP9 stimulatory effect and led to an accumulation of inactive ASAH1 precursors. Immunoprecipitation of ASAH1 followed by immunoblotting with concanavalin A (identifies N-glycans) revealed decreased ASAH1 glycosylation following dorsomorphin treatment indicating an ALK1 signalling dependent regulation of ASAH1 maturation. Immunofluorescence analysis showed that dorsomorphin treatment resulted in co-localization of ASAH1with the endoplasmic reticulum marker (ER) calreticulin, in line with reduced glycosylation and trafficking of ASAH1 from the ER to the lysosomes. Of clinical relevance, BMP9, ALK1 and pophorylated SMAD1 protein expression levels were markedly decreased in preeclamptic placentae relative to age-matched controls. Our data implicates a novel role for BMP9 signaling via ALK1 in regulating ASAH1 expression, processing and trafficking in the human placenta. Disruption of this signalling pathway may in part contribute to altered sphingolipid metabolism found in preeclampsia. (Supported by CIHR
Disruption of Prolyl hydroxylase domain protein-2 (PHD2) activity impairs TGFβ-dependent sphingolipid metabolism in murine placenta
No full textObjectives: Impairment of O2-dependent TGFβ3 signaling characterizes placental pathologies such as preeclampsia and IUGR and causes altered sphingolipid metabolism leading to increased trophoblast cell death. Under normoxic condition, degradation of the alpha subunit of hypoxia-inducible factor (HIF1A), a regulator of oxygen homeostasis, is tightly controlled by prolyl hydroxylase enzymes (PHD1-3). Ample evidence indicates that PHD2 is the key hydroxylase involved in regulating HIF1A stability in the human placenta. Our objective was to characterize the biological relevance of the O2/TGFβ3 axis in controlling sphingolipid metabolism in the murine placenta.
Methods: We generated a pharmacological hypoxic mouse model by inhibiting PHD2 activity using FG-4592, a small-molecule PHD inhibitor. Pregnant mice injected daily between E7.5 and E13.5 with FG-4592 (0.5 mg/kg) were sacrificed at E13.5. Control mice were injected with an equivalent volume of DMSO. Placentae were collected and processed for protein and sphingolipidomic analyses using immunohistochemistry, Western Blotting and liquid chromatography linked to tandem mass spectrometry (LC-MS/MS), respectively.
Results: PHD2 inhibition increased placental HIF1A, decreased its hydroxylation at the proline P564 residue, and stimulated TGFβ signaling. Administration of FG-4592 resulted in reduced placental and pup weights. Striking placental morphological defects including compaction of labyrinth zone and reduced vascularization were found. In addition, PHD2 inhibition resulted in decreased levels of sphingolipid regulatory enzymes, acid ceramidase (ASAH1) and sphingosine kinase (SPHK1), and this associated with elevated ceramide content as well as increased autophagy markers.
Conclusion: These results highlight the importance of the O2/TGFβ axis on murine placental development and function. A simulated condition of hypoxia with FG-4592 triggers TGFβ signaling, thereby impacting on sphingolipid metabolism and affecting placental cell homeostasis
Evidence that large vessels do affect near infrared spectroscopy
Full text linkThe influence of large vessels on near infrared spectroscopy (NIRS) measurement is generally considered negligible. Aim of this study is to test the hypothesis that changes in the vessel size, by varying the amount of absorbed NIR light, could profoundly affect NIRS blood volume indexes. Changes in haemoglobin concentration (tHb) and in tissue haemoglobin index (THI) were monitored over the basilic vein (BV) and over the biceps muscle belly, in 11 subjects (7 M – 4 F; age 31 ± 8 year) with simultaneous ultrasound monitoring of BV size. The arm was subjected to venous occlusion, according to two pressure profiles: slow (from 0 to 60 mmHg in 135 s) and rapid (0 to 40 mmHg maintained for 30 s). Both tHb and THI detected a larger blood volume increase (1.7 to 4 fold; p < 0.01) and exhibited a faster increase and a greater convexity on the BV than on the muscle. In addition, NIRS signals from BV exhibited higher correlation with changes in BV size than from muscle (r = 0.91 vs 0.55, p < 0.001 for THI). A collection of individual relevant recordings is also included. These results challenge the long-standing belief that the NIRS measurement is unaffected by large vessels and support the concept that large veins may be a major determinant of blood volume changes in multiple experimental conditions
Approximate Entropy of Spiking Series of a Neuronal Network in Either Subcritical or Critical State
No full textApproximate Entropy of Spiking Series Reveals Different Dynamical States in Cortical Assemblies
Full text linkSelf-organized criticality theory proved that information transmission and computational
performances of neural networks are optimal in critical state. By using recordings of the spontaneous
activity originated by dissociated neuronal assemblies coupled to Micro-Electrode Arrays (MEAs),
we tested this hypothesis using Approximate Entropy (ApEn) as a measure of complexity and
information transfer. We analysed 60 min of electrophysiological activity of three neuronal cultures
exhibiting either sub-critical, critical or super-critical behaviour. The firing patterns on each electrode
was studied in terms of the inter-spike interval (ISI), whose complexity was quantified using ApEn.
We assessed that in critical state the local complexity (measured in terms of ApEn) is larger than in
sub- and super-critical conditions (mean ± std, ApEn about 0.93 ± 0.09, 0.66 ± 0.18, 0.49 ± 0.27,
for the cultures in critical, sub-critical and super-critical state, respectively—differences statistically
significant). Our estimations were stable when considering epochs as short as 5 min (pairwise cross-
correlation of spatial distribution of mean ApEn of 94 ± 5%). These preliminary results indicate that
ApEn has the potential of being a reliable and stable index to monitor local information transmission
in a neuronal network during maturation. Thus, ApEn applied on ISI time series appears to be
potentially useful to reflect the overall complex behaviour of the neural network, even monitoring a single specific location
Expression of CD52 mRNA in the rat embryo
No full textCD52 is a leukocyte differentiation antigen first discovered in humans as expressed on the surface of lymphocytes,
monocytes and eosinophils. The human CD52 is found on chromosome 1, and two alleles are both known to be
reasonably common. A closely homologous gene has been identified in the cynomologous monkey and related
genes have been found in mouse, rat and dog. The role of CD52 in lymphocyte is still unclear but the anti-CD52
antibodies named CAMPATH-1 antibodies are largely used for therapy where depletion of lymphocytes is required.
In the past expression of the antigen on progenitors of leukocytes in bone marrow had been excluded, but recent
work indicates CD52 is highly expressed on cells with colony-forming and NOD/SCID (non-obese diabetic-severe
combined immunodeficiency)-engrafting capacities, both at the mRNA and membrane protein level. We have
investigated CD52 expression during development in rat embryos by in situ hybridization. We report here that
the antigen is highly expressed in the liver that is the major organ where multipotent hematopietic stem cells
differentiate but also in the splancnopleuric mesoderm, at early stages of embryo differentiation, where hematopietic
stem cells are suggested to arise. CD52+ cells were found in areas active in vasculogenesis at early embryo stages
and in the walls of the vessels in the liver at mid gestation. CD52+ cells were also found to emerge among c-Kit
positive cells
Objective Assessment of Venous Pulse Wave Velocity in Healthy Humans
Full text linkCentral venous pressure and volume status are relevant parameters for characterization of a patient's hemodynamic condition; however, their invasive assessment is affected by various risks while non-invasive approaches provide limited and subjective indications. Here we explore the possibility of assessing venous pulse wave velocity (vPWV), a potential indicator of venous pressure changes. In eight healthy patients, pressure pulses were generated artificially in the leg veins by rapid compression of the foot, and their propagation was detected at the level of the superficial femoral vein with Doppler ultrasound. Changes in leg venous pressure were obtained by raising the trunk from the initial supine position by 30° and 60°. vPWV increased from 1.78 ± 0.06 m/s (supine) to 2.26 ± 0.19 m/s (60°) (p < 0.01) and exhibited an overall linear relationship with venous pressure. These results indicate that vPWV can be easily assessed, and is a non-invasive indicator of venous pressure changes
Urban planning, flood risk and public policy: The case of the Arno River, Firenze, Italy
No full textUrban planning and hydraulic risk management are a worldwide necessity which is best achieved when natural and artificial elements located closely to watercourses are known in great detail. A geodatabase is a practical tool to store and manage such information. When working at small scales, however, any well established methodology exists to map the position and the height of the various elements with centimetric accuracy. For this purpose we propose a methodology that we tested on the Arno river (Italy) and its most urbanized tributaries, a demonstrative case of hydrological risk around large fluvial systems.
We surveyed 116 km of river traits to collect GPS measurements and information about all the natural and artificial elements connected to hydraulic risk and fluvial dynamics. The mapped elements include (but are not limited to) buildings, assets, bridges, hydraulic works, weirs, drainage outlets, dikes, riverbanks, structural damages, fluvial bars and eroding banks. All these elements were mapped with high accuracy, in particular a local geoid model, related only to the study area, was developed to obtain orthometric heights affected with errors ≤0.05 m. Consequently a GIS geodatabase was built to visualize the spatial distribution of the mapped elements and to store a series of technical data, including the present preservation condition for man-made objects. The geodatabase provides an overview of the territories connected with the fluvial dynamics, highlighting that in the studied territory, the more is urbanized, the more it is exposed to hydraulic risk. In a similar context, the geodatabase itself represents a useful tool for the management of the hydrological risk and for hydraulic policy and urban planning
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