Relationships between hydraulic traits and habitat preference for six Acer species occurring in the French Alps

Xylem hydraulic properties and vulnerability to cavitation were studied in six Acer species which occur, in the French Alps, along a soil moisture gradient from the moist valleys to the drier mountain stands. The results obtained suggest that a relationship existed between hydraulic properties and the species moisture preference. Maples located in dry zones (A. opalus, A. monspessulanum) proved more resistant to drought-induced cavitation than species that occurred in an irrigated area (A. negundo, A. pseudoplatanus, A. platanoides, A. campestre). The most vulnerable species to cavitation (A. negundo, A. pseudoplatanus, A. platanoides, A. campestre) showed the highest hydraulic conductances, whereas more cavitation-resistant species (A. opalus, A. monspessulanum) had the lowest conductances. This suggests a tradeoff between hydraulic efficiency and cavitation vulnerability. The possible ecological significances of these data are discussed in relation to the distribution of Acer species in their natural habitats

Silencing mutated β-catenin inhibits cell proliferation and stimulates apoptosis in the adrenocortical cancer cell line H295R

Adrenocortical carcinoma (ACC) is a rare and highly aggressive endocrine neoplasm, with limited therapeutic options. Activating β-catenin somatic mutations are found in ACC and have been associated with a poor clinical outcome. In fact, activation of the Wnt/β-catenin signaling pathway seems to play a major role in ACC aggressiveness, and might, thus, represent a promising therapeutic target. Similar to patient tumor specimen the H295 cell line derived from an ACC harbors a natural activating β-catenin mutation. We herein assess the in vitro and in vivo effect of β-catenin inactivation using a doxycyclin (dox) inducible shRNA plasmid in H295R adrenocortical cancer cells line (clone named shβ). Following dox treatment a profound reduction in β-catenin expression was detectable in shβ clones in comparison to control clones (Ctr). Accordingly, we observed a decrease in Wnt/βcatenin-dependent luciferase reporter activity as well as a decreased expression of AXIN2 representing an endogenous β-catenin target gene. Concomitantly, β-catenin silencing resulted in a decreased cell proliferation, cell cycle alterations with cell accumulation in the G1 phase and increased apoptosis in vitro. In vivo, on established tumor xenografts in athymic nude mice, 9 days of β-catenin silencing resulted in a significant reduction of CTNNB1 and AXIN2 expression. Moreover, continous β-catenin silencing, starting 3 days after tumor cell inoculation, was associated with a complete absence of tumor growth in the shβ group while tumors were present in all animals of the control group. In summary, these experiments provide evidences that Wnt/β-catenin pathway inhibition in ACC is a promising therapeutic target

Head and thorax elevation prevents the rise of intracranial pressure during extracorporeal resuscitation in swine

Aim: Head and thorax elevation during cardiopulmonary resuscitation improves cerebral hemodynamics and ultimate neurological outcome after cardiac arrest. Its effect during extracorporeal cardiopulmonary resuscitation (E-CPR) is unknown. We tested whether this procedure could improve hemodynamics in swine treated by E-CPR. Methods and Results: Pigs were anesthetized and submitted to 15 minutes of untreated ventricular fibrillation followed by E-CPR. Animals randomly remained in flat position (flat group) or underwent head and thorax elevation since E-CPR institution (head-up group). Electric shocks were delivered after 30 minutes until the return of spontaneous circulation (ROSC). They were followed during 120 minutes after ROSC. After 30 minutes of E-CPR, ROSC was achieved in all animals, with no difference regarding blood pressure, heart rate, and extracorporeal membrane of oxygenation flow among groups. The head-up group had an attenuated increase in ICP as compared with the flat group after cardiac arrest (13 ± 1 vs. 26 ± 2 mm Hg at the end of the follow-up, respectively). Cerebral perfusion pressure tended to be higher in the head-up versus flat group despite not achieving statistical difference (66 ± 1 vs 46 ± 1 mm Hg at the end of the follow-up). Carotid blood flow and cerebral oxygen saturation were not significantly different among groups. Conclusion: During E-CPR, head and thorax elevation prevents ICP increase. Whether it could improve the ultimate neurological outcome in this situation deserves further investigation.The study was supported by grants LIVE-RESP and AREG-SHOCK from Agence Nationale pour la Recherche. Y. Levy was supported by ADEREMVeterinari

The Warburg Effect Is Genetically Determined in Inherited Pheochromocytomas

The Warburg effect describes how cancer cells down-regulate their aerobic respiration and preferentially use glycolysis to generate energy. To evaluate the link between hypoxia and Warburg effect, we studied mitochondrial electron transport, angiogenesis and glycolysis in pheochromocytomas induced by germ-line mutations in VHL, RET, NF1 and SDH genes. SDH and VHL gene mutations have been shown to lead to the activation of hypoxic response, even in normoxic conditions, a process now referred to as pseudohypoxia. We observed a decrease in electron transport protein expression and activity, associated with increased angiogenesis in SDH- and VHL-related, pseudohypoxic tumors, while stimulation of glycolysis was solely observed in VHL tumors. Moreover, microarray analyses revealed that expression of genes involved in these metabolic pathways is an efficient tool for classification of pheochromocytomas in accordance with the predisposition gene mutated. Our data suggest an unexpected association between pseudohypoxia and loss of p53, which leads to a distinct Warburg effect in VHL-related pheochromocytomas

Cushing's Syndrome and Fetal Features Resurgence in Adrenal Cortex–Specific Prkar1a Knockout Mice

Carney complex (CNC) is an inherited neoplasia syndrome with endocrine overactivity. Its most frequent endocrine manifestation is primary pigmented nodular adrenocortical disease (PPNAD), a bilateral adrenocortical hyperplasia causing pituitary-independent Cushing's syndrome. Inactivating mutations in PRKAR1A, a gene encoding the type 1 α-regulatory subunit (R1α) of the cAMP–dependent protein kinase (PKA) have been found in 80% of CNC patients with Cushing's syndrome. To demonstrate the implication of R1α loss in the initiation and development of PPNAD, we generated mice lacking Prkar1a specifically in the adrenal cortex (AdKO). AdKO mice develop pituitary-independent Cushing's syndrome with increased PKA activity. This leads to autonomous steroidogenic genes expression and deregulated adreno-cortical cells differentiation, increased proliferation and resistance to apoptosis. Unexpectedly, R1α loss results in improper maintenance and centrifugal expansion of cortisol-producing fetal adrenocortical cells with concomitant regression of adult cortex. Our data provide the first in vivo evidence that loss of R1α is sufficient to induce autonomous adrenal hyper-activity and bilateral hyperplasia, both observed in human PPNAD. Furthermore, this model demonstrates that deregulated PKA activity favors the emergence of a new cell population potentially arising from the fetal adrenal, giving new insight into the mechanisms leading to PPNAD

Conception d'un système de récupération d'énergie très large bande

National audienceCet article présente la réalisation d'un système très large bande pour des applications de transfert et de récupération d'énergie. Il est constitué d'un circuit de redressement et d'une antenne. Le circuit de redressement, réalisé en technologie MMIC, a été validé expérimentalement sur des bandes de fréquences allant de 434 MHz jusqu'à 20 GHz, ce qui lui permet d'être opérationnel sur de nombreuses bandes de fréquences. Des pistes d'augmentation du niveau de tension redressé par des circuits élévateurs sont également proposées. Enfin, une antenne spirale large bande est présentée, dans le but de réaliser un rectenna complet

Broadband rectenna for ambient RF energy harvesting applications

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Mélangeur double-grille et amplificateur filtrant MMIC à 5.8 GHz

International audienceCet article présente la réalisation, en technologie MMIC sur substrat d'AsGa, de deux circuits , un mélangeur double grille et un amplificateur filtrant à 5. 8 GHz (bande ISM). Pour chaque circuit, un compromis a été recherché entre simplicité et performances dans le but d'obtenir des dispositifs compacts, faciles à intégrer en MMIC et faciles à tester, avec des caractéristiques suffisantes pour une intégration dans une chaîne de réception RF

Réalisation d’un rectenna dans la bande des 1.8 GHz, fonctionnant à faibles niveaux de puissance RF et optimisé par des techniques source-pull

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Rectenna bi-bande 900 MHz-1800 MHz pour des applications de récupération d’énergie ambiante

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