Cu segregation in Au-Cu nanoparticles exposed to hydrogen atmospheric pressure: how is fcc symmetry maintained?

In a recent work [A. Nassereddine et al., Small 2021, 17, 2104571] we reported the atomic-scale structure and dynamics of sub-4 nm sized Au nanoparticles (NPs) supported on titania in H2 at atmospheric pressure obtained by using aberration-corrected environmental transmission electron microscopy (ETEM), density functional theory (DFT) optimizations and ab initio molecular dynamic (AIMD) simulations. Our results showed unstable Au NPs losing their face-centred cubic (fcc) symmetry (from fcc to non-fcc symmetries) and revealed the drastic effect of hydrogen adsorption. In this work, we use the same approach to study the dynamics of equiatomic Au-Cu NPs in the same range of size and the results show an enhanced structural stability upon alloying by Cu. In spite of the morphology evolution from facetted to rounded shapes, the observed Au-Cu NPs are found to keep their fcc symmetry under atmospheric hydrogen pressure. AIMD simulation evidences a Cu segregation process from the sub-surface toward the upper surface layer, and a reversed segregation of Au atoms from the surface towards the sub-surface sites. The analysis of the chemical ordering in the core shows a tendency to a local chemical ordering where Au-Cu hetero-atomic bindings are favoured. The segregating Cu seems to play a major role in reducing the fluxionality of Au-Cu NPs in H2 and thus, maintaining their fcc symmetry.

[Interest of systematic shavings to reduce reoperation in breast-conserving surgery of breast cancer]. / Intérêt des recoupes systématiques pour éviter les réinterventions dans la chirurgie conservatrice du cancer du sein.

OBJECTIVE: The INCa and HAS have developed quality and safety indicators for care specific to breast cancer. Among these, in the conservative surgery of this cancer includes the reoperation rate: target˂10%, alert>20%. The main objective of our study was to evaluate whether the practice of systematic recuts still called "shaving" would meet the objectives of the indicators. METHODS: Observational, retrospective, single-center study over two years in a regional referral center. Two groups of patients were compared: one with "shaving" and one without (no shaving or oriented shaving). RESULTS: In total, 381 patients were operated on, including 48 (12.6%) with shaving and 333 (87.4%) without. Revision rates for damaged margins were 18.75% (9/48) in the shaving group which met the quality criterias vs. 23.7% (79/333) which did not satisfy them; P=0.4. Furthermore, the rate of discovery of occult sites on recuts was higher in the shaving group: 22.9% (11/48) vs. 9.9% (33/333); P=0.02. In the shaving group, 10.4% (5/48) of the patients were resected again for damaged margins for the initial cancer vs. 18.6% (62/333) in the group without shaving; P=0.23. CONCLUSION: Our study confirms the interest of performing "shaving" to meet the requirements of the INCa and HAS quality criteria. The absence of systematic cross-sectioning leads to the risk of not recognizing the existence of occult sites. However, the discovery of occult cancers does not significantly reduce the rate of repeat surgery.

C-Terminal region of teneurin-1 co-localizes with dystroglycan and modulates cytoskeletal organization through an extracellular signal-regulated kinase-dependent stathmin- and filamin A-mediated mechanism in hippocampal cells.

The pyramidal neurons in the hippocampus are extremely neuroplastic, and the complexity of dendritic branches can be dynamically altered in response to a variety of stimuli, including learning and stress. Recently, the teneurin family of proteins has emerged as an interneuronal and extracellular matrix signaling system that plays a significant role in brain development and neuronal communication. Encoded on the last exon of the teneurin genes is a new family of bioactive peptides termed the teneurin C-terminal-associated peptides (TCAPs). Previous studies indicate that TCAP-1 regulates axon fasciculation and dendritic morphology in the hippocampus. This study was aimed at understanding the molecular mechanisms by which TCAP-1 regulates these changes in the mouse hippocampus. Fluoresceinisothiocyanate (FITC)-labeled TCAP-1 binds to the pyramidal neurons of the CA2 and CA3, and dentate gyrus in the hippocampus of the mouse brain. Moreover, FITC-TCAP-1 co-localizes with ß-dystroglycan upon binding to the plasma membrane of cultured immortalized mouse E14 hippocampal cells. In culture, TCAP-1 stimulates ERK1/2-dependent phosphorylation of the cytoskeletal regulatory proteins, stathmin at serine-25 and filamin A at serine-2152. In addition, TCAP-1 induces actin polymerization, increases immunoreactivity of tubulin-based cytoskeletal elements and causes a corresponding increase in filopodia formation and mean filopodia length in cultured hippocampal cells. We postulate that the TCAP-1 region of teneurin-1 has a direct action on the cytoskeletal reorganization that precedes neurite and process development in hippocampal neurons. Our data provides novel evidence that functionally links the teneurin and dystroglycan systems and provides new insight into the molecular mechanisms by which TCAP-1 regulates cytoskeletal dynamics in hippocampal neurons. The TCAP-dystroglycan system may represent a novel mechanism associated with the regulation of hippocampal-function.

Type A dissection of the thoracic aorta: use of MR imaging for long-term follow-up.

PURPOSE: To evaluate routine magnetic resonance (MR) imaging for long-term follow-up in patients who undergo surgery for type A aortic dissection. MATERIALS AND METHODS: Ninety-two MR examinations were performed in 36 patients. Standard spin-echo images were obtained with electrocardiographic gating (n = 92) and rapid images with a fast low-angle shot sequence and intravenous administration of gadopentetate dimeglumine (n = 25). All segments of the native thoracic aorta were evaluated. Anastomoses of the prosthesis and periprosthetic hematoma were carefully analyzed. RESULTS: Of 22 complications that occurred in 18 patients, 18 were diagnosed at MR imaging (nine false aneurysms and nine aneurysms distal to the graft). Nine patients underwent reoperation. The findings at MR imaging correlated with those at surgery. CONCLUSION: Routine follow-up with MR imaging should improve long-term survival in patients who survive emergency surgical repair of type A aortic dissection.

Dehiscence of the lamina papyracea of the ethmoid bone: CT findings.

PURPOSE: To describe the CT findings characterizing dehiscence of the lamina papyracea. METHODS: Axial and coronal CT scanning of the paranasal sinuses was performed on 783 patients. RESULTS: Dehiscence of the lamina papyracea was noted incidentally in six patients. In all cases dehiscence was characterized by protrusion of orbital fat through a gap in the anterior ethmoid. The posterior limit of the dehiscence was always the basal lamella. The anterior limit varied. CONCLUSION: CT scans are often taken to detect polyps or assess chronic sinusitis. Awareness of dehiscence of the lamina papyracea is important to avoid misdiagnosis as infectious or tumoral process and possible injury of the orbit during endoscopic surgery.

[Extrapleural hematoma]. / Hématome extra-pleural.

The authors report a case of a voluminous extra-pleural hematoma in relation to a fracture of the body of the eleventh thoracic vertebra on a 74 year-old man after craniothoracic injury. Thoracic CT Scan showed a homogeneous posterior parietal mass of tissue density (40 HU) outlined by a fatty lining associated with a fracture of the eleventh thoracic vertebra. This allowed a modification in the diagnosis of a hemothorax established previously on conventional radiography. The authors insist on the gravity of this affection when the volume of the hematoma is important. But this is very rare (6 cases out of which 5 were autopsic findings). If present it requise an urgent surgical treatment without forgetting the fiability of CT Scan which relies on putting into evidence the pleural lining sign.

[Ioversol 300 and iopamidol 300 in "whole body" computed tomography. A double-blind clinical trial]. / Ioversol 300 et iopamidol 300 en tomodensitométrie "corps-entier". Essai clinique en double insu.

The authors compared ioversol 300 to iopamidol 300 by double blind study in patients undergoing enhanced computed body tomography. There was no significant difference in clinical tolerance and efficacy between the two products. Only minor reactions were recorded in both groups. Contrast media were not considered to be responsible for the poor diagnostic quality of a few explorations. Ioversol 300 appears as a well tolerated and effective contrast medium for computed body tomography.

The normal uterus on magnetic resonance imaging and variations associated with the hormonal state.

Magnetic Resonance Imaging of the pelvis has lead to a new radioanatomical description of the uterus. Variations in the anatomical zones of the uterus were noted with different sequences used in MRI. There was also structural and signal variation depending on hormonal impregnation. Twenty seven MRIs of pelvices were carried out on 16 female volunteers. Eight of them were on oestroprogesterone as the method of contraception (Group I) and had a single MRI. Six were not taking contraceptives (Group II) and had different MRI's during the same cycle. Two women already had already gone through the menopause (Group III). Results showed differences in the size of the uterus (uterine height, length of the uterine body and cervix, diameter of the cervix) between groups I and II but no cyclic changes were observed within group II. The myometrium was found to be thicker in group I and in the luteal phase of group II females in comparison to the follicular phase in the same group. The endometrial cavity was seen in 40% of cases on T1 weighted sequences; on T2 weighted sequences it was seen in all the cases. It was thicker during the second phase in group II than in group I and III. The myometrial signal compared to that of the bladder content (urine) showed a significant increase between early and late echoes on T2 weighted sequences in group I and during the second phase of the menstrual cycle in group II. No variations, or at times a decrease in signal, were observed during the first phase of the cycle in group II.(ABSTRACT TRUNCATED AT 250 WORDS)

PIP: 16 healthy 20-71 year old women underwent magnetic resonance imaging (MRI) in Marseille, France so the radiologists could better understand the anatomy of the uterus under various hormonal states. Group I included 8 women who were taking oral contraceptives (OCs) and underwent only 1 MRI. Group II were 6 women who did not take OCs and underwent 2-4 MRIs during 2 phases of the same menstrual cycle. Group III included 2 postmenopausal women. Uterine height, cervix diameter, and uterine body length were greater in group II than group I (76.9 mm vs. 80 mm; 25.6 mm vs. 28.3 mm; and 49.1 mm vs. 46.25 mm respectively). Cervix length was greater in group I than group II (30.6 mm vs. 29.7 mm). The radiologists did not notice any cyclic changes within group II. The myometrium was thicker in group I (16.9 mm) and in the luteal phase of group II (15.8 mm) compared to the follicular phase of group II (13.75 mm). T2 weighted sequences revealed the endometrial cavity of all cases, but T1 weighted sequences revealed the cavity in 40% of cases. The endometrial cavity was thicker in group II women (6.5 mm [1st phase] and 9.9 mm [2nd phase]) than either group I (2.4 mm) or group II (1 mm) women. T2 weighted sequences in group I and during the 2nd phase of the menstrual cycle in group II showed a great increase in the myometrial signal compared to bladder content between early and late echoes. Further only T2 weighted sequences uncovered the junctional zone. The junctional zone was thickest during the 1st phase of the cycle of group II women than during the 2nd phase. T2 weighted sequence could only reveal the junctional zone in only 1 woman in group III. Knowing the zonal anatomy of the uterus and its changes is helpful in diagnosing adenomyosis, myometrial extension of endometrial carcinomas, extension of cervical carcinomas.

[Uterine cervix cancers: staging by magnetic resonance imaging]. / Cancers du col utérin: stadification par imagerie par résonance magnétique.

The accuracy of Magnetic Resonance Imaging in cervical carcinoma staging for clinical stages superior to IB was studied retrospectively in 27 patients. The MRI results were then correlated with operative findings in 12 cases and with examination carried out under general anesthesia in 15 cases for myometrial, bladder, rectal, parametrial, parietal and vaginal extension. The accuracy of MRI was 81.5% for bladder, 92.5% for rectal, 87% for parametrial and 73% for vaginal extension. The accuracy of staging by MRI was 59%. The contribution of MRI in pre-operative studies for cervical carcinomas has not been properly defined until now. Nevertheless it is a particularly valuable technique due to its non invasive nature.

[Study of congenital hemiplegia: value of x-ray computed tomography of the brain and of somatosensory evoked potentials]. / Exploration de l'hémiplégie congénitale: intéret de la tomodensitometrie cerebrale et des potentiels évoqués somesthésiques.

21 cases of children with congenital hemiparesis have been studied by computerized tomography (CT) of the head and somatosensory evoked potentials (SEP). Computerized tomography is correlated with clinical features and may disclose cerebral lesions and their physiopathological mechanisms. Somatosensory evoked potentials allow a more functional approach of the handicap but are not perfectly correlated with the motor deficit. SEP are correlated with the topography of cerebral lesions showed by CT. These two investigations seem to be interesting and complementary for the exploration of congenital hemiparesis.

Reissner's fiber and the wall of the central canal in the lumbo-sacral region of the bovine spinal cord. Comparative immunocytochemical and ultrastructural study.

Reissner's fiber (RF) of the subcommissural organ (SCO), the central canal and its bordering structures, and the filum terminale were investigated in the bovine spinal cord by use of transmission electron microscopy, histochemical methods and light-microscopic immunocytochemistry. The primary antisera were raised against the bovine RF, or the SCO proper. Comparative immunocytochemical studies were also performed on the lumbo-sacral region of the rat, rabbit, dog and pig. At all levels of the bovine spinal cord, RF was strongly immunoreactive with both antisera. From cervical to upper sacral levels of the bovine spinal cord there was an increasing number of ependymal cells immunostainable with both antisera. The free surface of the central canal was covered by a layer of immunoreactive material. At sacral levels small subependymal immunoreactive cells were observed. From all these structures sharing the same immunoreactivity, only RF was stained by the paraldehyde-fuchsin and periodic-acid-Schiff methods. At the ultrastructural level, ependymal cells with numerous protrusions extending into the central canal were seen in the lower lumbar segments, whereas cells displaying signs of secretory activity were principally found in the ependyma of the upper sacral levels. A few cerebrospinal fluid-contacting neurons were observed at all levels of the spinal cord; they were immunostained with an anti-tubulin serum. The lumbo-sacral segments of the dog, rat and rabbit, either fixed by vascular perfusion or in the same manner as the bovine material, did not show any immunoreactive structure other than RF. The possibilities that the immunoreactive ependymal cells might play a secretory or an absorptive role, or be the result of post-mortem events, are discussed.

Cellular organization of the lateral and postinfundibular regions of the median eminence in the rat.

The structural organization of the rostral, lateral and postinfundibular regions of the median eminence (ME) of 5-day cyclic diestrous rats was studied with light and electron microscopic methods. The ependymal cells lining (i) the floor of the infundibular recess (IR) at rostral levels, (ii) the lateral extensions of the IR, and (iii) the floor of the premammillary recess appear to represent the same type of tanycyte ependyma (beta 1 tanycytes). In the entire width of the rostral and postinfundibular palisade regions, as well as in the lateral palisade region of the preinfundibular ME, the processes of the beta 1 tanycytes form a continuous cuff. This cuff separates the nerve endings from the blood vessels and the pars tuberalis. At this level, synaptoid contacts between neurosecretory axons and the ependymal cuff can be observed. The ultrastructural characteristics of the beta 1 tanycytes are described and their ependymal endings tentatively classified into three types. In the lateral regions of the ME, the Golgi study revealed the presence of two fiber systems: (i) one possessing a latero-medial trajectory and distributed in the subependymal region; (ii) the other formed by a loose longitudinal tract originating from neurons of the arcuate nucleus. Some functional implications of the cellular organization of the rat ME are discussed.