FORTE - a multipurpose high-vacuum diffractometer for tender X-ray diffraction and spectroscopy at the SIRIUS beamline of Synchrotron SOLEIL.

A new high-vacuum multipurpose diffractometer (called FORTE from the French acronyms of the project) has recently been installed at the tender/hard X-ray SIRIUS beamline of Synchrotron SOLEIL, France. The geometry chosen allows one to work either in the classical Eulerian four-circle geometry for bulk X-ray diffraction (XRD) or in the z-axis geometry for surface XRD. The diffractometer nicely fits the characteristics of the SIRIUS beamline, optimized to work in the 1.1-4.5 keV range, and allows one to perform unprecedented diffraction anomalous fine structure (DAFS) experiments in the tender X-ray region, also around non-specular reflections, covering a large reciprocal-space volume. Installation of an X-ray fluorescence detector on a dedicated flange allows simultaneous DAFS and X-ray absorption (XAS) measurements. The access to the tender X-ray region paves the way to resonant investigations around the L-edges of second-row transition elements which are constituents of functional oxide materials. It also enables access to several edges of interest for semiconductors. Finally, the control architecture based on synchronized Delta Tau units opens up exciting perspectives for improvement of the mechanical sphere of confusion.

Nephron sparing surgery in tumours greater than 7cm.

INTRODUCTION: Partial nephrectomy (PN) is the gold standard treatment for renal cell carcinomas under 4cm. No robust data exists to recommend PN for tumours>7cm (cT2). The objective of this work is to evaluate the results of PN for cT2 tumours. PATIENTS AND METHODS: All patients who underwent PN or radical nephrectomy (RN) for cT2 tumours between 2000 and 2013 at our institution have been included. Patient demographics, postoperative data including renal function, morbidity, mortality and oncologic outcomes were reviewed retrospectively and compared using χ2 test, Mann-Whitney test, Kaplan-Meier method and log rank test. RESULTS: We included 130 patients, 49 (38%) in the PN group and 81 (62%) in the RN group, with a median follow-up of 42 months [19-69]. Variation of postoperative renal function at day 5 and last recorded value was significantly different between the groups (P=0.03 and P<0.001). The PN group had a significantly higher complication rate as compared with RN group (37% versus 14%, P=0.002). There were no significant differences between the two groups for overall, recurrence free and specific survival (P=0.55, P=0.55, P=0.24, respectively). In univariate analysis, the type of surgery (PN versus RN) was not associated with a significant difference of oncologic outcome (margins, survival). CONCLUSION: PN can be offered for cT2 tumours with oncological outcomes similar to RN. Despite an increased morbidity, it remains acceptable with the demonstrated advantage of preservation of renal function. LEVEL OF EVIDENCE: 4.

Distribution and functional characterization of pituitary adenylate cyclase-activating polypeptide receptors in the brain of non-human primates.

The distribution and density of pituitary adenylate cyclase-activating polypeptide (PACAP) binding sites have been investigated in the brain of the primates Jacchus callithrix (marmoset) and Macaca fascicularis (macaque) using [(125)I]-PACAP27 as a radioligand. PACAP binding sites were widely expressed in the brain of these two species with particularly high densities in the septum, hypothalamus and habenula. A moderate density of recognition sites was seen in all subdivisions of the cerebral cortex with a heterogenous distribution, the highest concentrations occurring in layers I and VI while the underlying white matter was almost devoid of binding sites. Reverse transcriptase-polymerase chain reaction (RT-PCR) analysis revealed intense expression of the mRNAs encoding the short and hop-1 variants of pituitary adenylate cyclase-activating polypeptide-specific receptor (PAC1-R) in the cortex of both marmoset and macaque, whereas vasoactive intestinal polypeptide/pituitary adenylate cyclase-activating polypeptide mutual receptor, subtype 1 (VPAC1-R) and vasoactive intestinal polypeptide/pituitary adenylate cyclase-activating polypeptide mutual receptor, subtype 2 (VPAC2-R) mRNAs were expressed at a much lower level. In situ hybridization histochemistry showed intense expression of PAC1-R and weak expression of VPAC1-R mRNAs in layer IV of the cerebral cortex. Incubation of cortical tissue slices with PACAP induced a dose-dependent stimulation of cyclic AMP formation, indicating that PACAP binding sites correspond to functional receptors. Moreover, treatment of primate cortical slices with 100 nM PACAP significantly reduced the activity of caspase-3, a key enzyme of the apoptotic cascade. The present results indicate that PACAP should exert the same neuroprotective effect in the brain of primates as in rodents and suggest that PAC1-R agonists may have a therapeutic value to prevent neuronal cell death after stroke or in specific neurodegenerative diseases.

Interactions of PACAP and ceramides in the control of granule cell apoptosis during cerebellar development.

Pituitary adenylate cyclase-activating polypeptide (PACAP) is a neuropeptide that belongs to the secretin/glucagon/vasoactive intestinal polypeptide superfamily. The PACAPergic system is actively expressed in the developing cerebellum of mammals. In particular, PACAP receptors are expressed by granule cell precursors suggesting a role of the peptide in neurogenesis of this cell type. Consistent with this hypothesis, several studies reported antiapoptotic effects of PACAP in the developing cerebellum. On the other hand, the sphingomyelin metabolites ceramides are recognized as important signaling molecules that play pivotal roles during neuronal development. Ceramides, which production can be induced by death factors such as FasL or TNFalpha, are involved in the control of cell survival during brain development through activation of caspase-dependent mechanisms. The present review focuses on the interactions between PACAP and ceramides in the control of granule cell survival and on the transduction mechanisms associated with the anti- and proapoptotic effects of PACAP and ceramides, respectively.

Maternal perinatal undernutrition impairs chromaffin cells proliferation in the postnatal rat.

Numerous data show that malnutrition during early life programs chronic diseases in adulthood. Many of these disorders may result from alterations in the development of neuroendocrine systems, such as the hypothalamo-pituitary-adrenal axis and the sympathoadrenal system. We have previously reported that maternal 50% food restriction during late pregnancy and lactation reduces adrenal weight and impairs chromaffin cell differentiation in male rats at weaning. In addition, maternal undernutrition modifies the expression of several genes involved in proliferation and apoptosis. This study therefore investigated the impact of maternal food restriction on adrenal cell growth in the late postnatal rat. Histological analysis showed that the number of proliferating chromaffin cells assessed by nuclear labelling with BrdU was reduced by 45%, whereas the level of apoptosis visualised by caspase-3 immunoreactivity was increased by 340% in adrenal medulla of offspring from undernourished mothers. In contrast, maternal food restriction did not affect proliferation and apoptosis in cortical cells of rats. These developmental changes were associated with overexpression of TGFbeta2. These data show that perinatal undernutrition impairs the balance between chromaffin cell proliferation and apoptosis. These modifications may lead to "malprogramming" of adrenal medulla development, which could contribute to the pathogenesis of chronic diseases in adulthood.

Bax siRNA promotes survival of cultured and allografted granule cell precursors through blockade of caspase-3 cleavage.

Transplantation of neuronal precursor cells (NPCs) into the central nervous system could represent a powerful therapeutical tool against neurodegenerative diseases. Unfortunately, numerous NPCs die shortly after transplantation, predominantly due to caspase-dependent apoptosis. Using a culture of cerebellar neuronal precursors, we have previously demonstrated protective effect of the neuropeptide PACAP, which suppresses ceramide-induced apoptosis by blockade of the mitochondrial apoptotic pathway. The main objective of this study was to determine whether Bax repression can promote survival of NPCs allotransplanted into a host animal. In vivo and ex vivo experiments revealed that C2-ceramide increases Bax expression, while PACAP reverses this effect. In vitro tests using cerebellar NPCs demonstrated that the Bax-specific small interfering RNA (siRNA) could reduce their death and caspase-3 cleavage within the first 24 h. BrdU-labelled NPCs were subjected to transfection procedure with or without siRNA introduction before using for in vivo transplantation. Twenty-four hours after, the allografted NPCs containing siRNA showed significantly reduced level of caspase-3 cleavage, and the volume of their implants was almost twofold higher than in the case of empty-transfected precursors. These data evidence an important role of Bax in life/death decision of grafted NPCs and suggest that RNA interference strategy may be applicable for maintaining NPCs survival within the critical first hours after their transplantation.

The neuropeptide pituitary adenylate cyclase-activating polypeptide exerts anti-apoptotic and differentiating effects during neurogenesis: focus on cerebellar granule neurones and embryonic stem cells.

Pituitary adenylate cyclase-activating polypeptide (PACAP) was originally isolated from ovine hypothalamus on the basis of its hypophysiotrophic activity. It has subsequently been shown that PACAP and its receptors are widely distributed in the central nervous system of adult mammals, indicating that PACAP may act as a neurotransmitter and/or neuromodulator. It has also been found that PACAP and its receptors are expressed in germinative neuroepithelia, suggesting that PACAP could be involved in neurogenesis. There is now compelling evidence that PACAP exerts neurotrophic activities in the developing cerebellum and in embryonic stem (ES) cells. In particular, the presence of PACAP receptors has been demonstrated in the granule layer of the immature cerebellar cortex, and PACAP has been shown to promote survival, inhibit migration and activate neurite outgrowth of granule cell precursors. In cerebellar neuroblasts, PACAP is a potent inhibitor of the mitochondrial apoptotic pathway through activation of the MAPkinase extracellular regulated kinase. ES cells and embryoid bodies (EB) also express PACAP receptors and PACAP facilitates neuronal orientation and induces the appearance of an electrophysiological activity. Taken together, the anti-apoptotic and pro-differentiating effects of PACAP characterised in cerebellar neuroblasts as well as ES and EB cells indicate that PACAP acts not only as a neurohormone and a neurotransmitter, but also as a growth factor.

Consequences of labetalol administration on myocardial beta adrenergic receptors in the brain dead pig.

OBJECTIVES: Cardiac dysfunction following brain death is associated with highly increased myocardial norepinephrine, lactate and adenosine concentrations. Administration of labetalol, a mixed alpha-, beta-adrenergic receptor antagonist, attenuates metabolic disturbances and improves myocardial function. The purpose of this study was to investigate beta-adrenergic receptor (beta AR) density and affinity in the presence or absence of labetalol administration, as a possible mechanism of the protective effects of this drug. METHODS: Experimental animals were divided into three groups: sham-operated, brain-dead pigs, and brain-dead pigs treated with labetalol (10 +/- 3 mg/kg). The maximum number of binding sites (Bmax) and the dissociation constant (Kd) of beta AR were determined with (-)-[125I]cyanopindolol on myocardial samples harvested 3 hours after brain death. RESULTS: Left ventricular beta AR density and affinity were identical in brain-dead and sham-operated animals. Labetalol-treated pigs exhibited a significant decrease of Bmax and an increase of Kd as compared with brain-dead pigs. Bmax decrease was due to the persistence of labetalol in the membrane preparations. Increased Kd was too low to be biologically significant. Therefore, beta AR number and affinity can be considered as unchanged after adrenergic blockade with labetalol. CONCLUSIONS: The protective mechanism of labetalol on brain death-induced myocardial dysfunction cannot be explained by changes in beta AR density and affinity but is probably related to a preservation of the oxygen consumption/oxygen delivery balance during the autonomic storm.

Absence of effect of heparin on insulin secretion.

Bioartificial pancreatic devices containing isolated islets of Langerhans have been designed, in which the blood of the recipient circulates in contact with an artificial membrane, protecting the islets against immune rejection. This system assumes that heparin, required to prevent blood clotting, does not alter insulin secretion. However, heparin has been reported to inhibit in vitro insulin secretion by rat islets and to suppress in vivo insulin secretion in dogs. Therefore, the following evaluation was made on the effect of different heparin preparations on insulin secretion. (a) Isolated rat islets of Langerhans were perfused or incubated in the absence or presence of 20 micrograms/ml heparin; insulin secretion in response to a stimulation by glucose 20 mM was not altered by the presence of heparin. (b) Insulin secretion by an insulin-secreting cell line (RINm5F) in response to leucine and theophylline was not suppressed by heparin up to 100 micrograms/ml concentration. However, an inhibitory effect was observed at 200 micrograms/ml, which is 100 times higher than the heparin concentration commonly used for therapeutic use. (c) Neither in normal rats nor in dogs did heparin alter portal plasma insulin levels and the increase in plasma insulin following an intravenous injection of glucose. In conclusion, these data do not confirm the formerly observed inhibitory effect of heparin, which can therefore be used for the in vivo evaluation of a bioartificial pancreas.

Reversible morphological and functional abnormalities of RINm5F cells cultured on polystyrene sulfonate beads.

RINm5F cells (an insulin-secreting cell line) were cultured on PSSO3Na microbeads under static conditions. The cell growth rate was either identical to that of cells grown on plastic wells or slower, depending on the initial cell concentration. With both supports, it was similarly influenced by the fetal calf serum concentration in the culture medium, and protein content per cell was identical. However, no spreading was observed when cells were cultured on microbeads. RINm5F cells cultured on plastic wells responded to arginine + theophylline and to leucine + theophylline by a significant increase in insulin secretion. By contrast, in cells cultured on PSSO3Na microbeads, the increase in this secretion was only slight or nil. All these abnormalities were reversible. Thus, when cells cultured on microbeads were detached and seeded on plastic wells, normal spreading and insulin secretion were observed. Lastly, PSSO3Na beads had an acute suppressive effect on insulin secretion by cells cultured on plastic wells. This study provides an example of cell-biomaterial interaction in which cell growth is possible, but with altered cell function.

Anticoagulant hydrogels derived from crosslinked dextran. Part II: Mechanism of thrombin inactivation.

Sephadex derivatives bearing carboxymethyl, sulphonated benzylamine and amino acid groups exhibit heparin-like behaviour as demonstrated by the kinetic study of the thrombin inactivation in the presence of antithrombin III. Furthermore, whatever the chemical composition of these hydrogels, the diffusion coefficient of thrombin remained approximately constant and could not be connected with the variation of the antithrombin activity of the resins. Hence, in the heparin-like mechanism, the diffusion rate of thrombin inside the beads of hydrogels was not the limiting step. In fact, the swelling ratio (varying according to the chemical composition of these biomaterials) was involved in the anticoagulant properties of the resins.

Anticoagulant hydrogels derived from crosslinked dextran. Part I: Synthesis, characterization and antithrombic activity.

Hydrogels have been prepared by binding various amino acids to Sephadex derivatives bearing carboxymethyl and sulphonated benzylamide groups. Depending on the chemical nature and content of the amino acid substituent, these insoluble strongly hydrophilic materials may absorb 7 to 19 volumes of buffer per volume of dry material. These hydrogels present antithrombic activity in relation to their swelling ratio. The adsorption of thrombin might partially explain the anticoagulant effect as shown by the evaluated affinity constants between the hydrogels and the enzyme i.e. 1 to 2 X 10(6) I/M.

[Are auditory prostheses a contraindication to magnetic resonance imaging?]. / Les prothèses auditives sont-elles une contre-indication à l'I.R.M.?

Prior to the use of nuclear magnetic resonance imaging (NMRI) in patients with metallic ossicular prostheses their compatibility must be investigated with the intense magnetic fields generated by NMRI. Implanted auditory prostheses are an absolute contraindication to NMRI, but an experimental study of its possible interaction with metallic stapedial prostheses has shown absence of their displacement. The artefact induced may alter images of middle ear but do not affect internal auditory canal. Nevertheless, manufacturers should conduct tests of magnetism of prostheses before they are passed as satisfactory.

Antithrombic activity of some polysaccharide resins.

Crosslinked dextrans (Sephadex) bearing essentially carboxymethyl, benzylsulphonate and alpha-amino acid groups have been synthesized. The antithrombic activity of the resins may be the result of a cooperative effect between the functional groups. The binding of benzylsulphonate to carboxymethylated Sephadex endows these materials with activity. However the highest activity is obtained when the resins contain simultaneously benzylsulphonate, alpha-amino acid and carboxylic acid groups.