SiGe nano-heteroepitaxy on Si and SiGe nano-pillars.

In this paper, SiGe nano-heteroepitaxy on Si and SiGe nano-pillars was investigated in a 300 mm industrial reduced pressure-chemical vapour deposition tool. An integration scheme based on diblock copolymer patterning was used to fabricate nanometre-sized templates for the epitaxy of Si and SiGe nano-pillars. Results showed highly selective and uniform processes for the epitaxial growth of Si and SiGe nano-pillars. 200 nm thick SiGe layers were grown on Si and SiGe nano-pillars and characterised by atomic force microscopy, x-ray diffraction and transmission electron microscopy. Smooth SiGe surfaces and full strain relaxation were obtained in the 650 °C-700 °C range for 2D SiGe layers grown either on Si or SiGe nano-pillars.

Overestimation of moderate carotid stenosis assessed by both Doppler US and contrast enhanced 3D-MR angiography in the CARMEDAS study.

PURPOSE: To evaluate the agreement and diagnostic accuracy of Contrast enhanced magnetic resonance angiography (CE-MRA), Doppler ultrasound (DUS) and Digital subtraction angiography (DSA) in the assessment of carotid stenosis. METHODS: DUS, CE-MRA and DSA were performed in 56 patients included in the Carotide-angiographie par résonance magnétique-échographie-doppler-angioscanner (CARMEDAS) multicenter study with a carotid stenosis ≥ 50%. Three readers evaluated stenoses on CE-MRA and DSA (NASCET criteria). Velocities criteria were used for stenosis estimation on DUS. RESULTS: CE-MRA had a sensitivity and specificity of 96-98% and 66-83% respectively for carotid stenoses ≥ 50% and a sensitivity and specificity of 94% and 76-84% respectively for carotid stenoses ≥ 70%. The interobserver agreement of CE-MRA was excellent, except for moderate stenoses (50-69%). DUS had a sensitivity and specificity of 88 and 75% respectively for carotid stenoses ≥ 50% and a sensitivity and specificity of 83 and 86% respectively for carotid stenoses ≥ 70%. Combined concordant CE-MRA and DUS had a sensitivity and specificity of 100 and 85-90% respectively for carotid stenoses ≥ 50% and a sensitivity and specificity of 96-100% and 80-87% respectively for carotid stenoses ≥ 70%. The positive predictive value of the association CE-MRA and DUS for carotid stenoses ≥ 70% is calculated between 77 and 82% while the negative predictive value is calculated between 97 and 100%. CE-MRA and DUS have concordant findings in 63-72%, and the overestimations cases were recorded only for carotid stenosis ≤ 69%. CONCLUSION: Combined DUS-CE-MRA is excellent for evaluation of severe stenosis but remains debatable in moderate stenosis (50-69%) due to the risk of overestimations.

Particles in model filled rubber: dispersion and mechanical properties.

We have been able to design model filled rubbers with exactly the same chemical structure but different filler arrangements. From these model systems, we show that the particle arrangement in the elastomeric matrix controls the strain softening at small strain amplitude known as the Payne effect, as well as the elastic modulus dependence on the temperature. More precisely, we observed that the Payne effect disappears and the elastic modulus only weakly depends on the temperature when the particles are well separated. On the contrary, samples with the same interfacial physical chemistry but with aggregated particles show large amplitudes of the Payne effect and their elastic modulus decreases significantly with the temperature. We discuss these effects in terms of glassy bridge formation between filler particles. The observed effects provide evidence that glassy bridges play a key role on the mechanical properties of filled rubbers.

[MRI aspects of anoxic-ischemic encephalopathy of the term and premature newborn]. / Aspects IRM de l'encéphalopathie anoxo-ischémique du nouveau-né à terme et du prémature.

These past few years have seen an increasing role of MRI in the investigation of neonatal cerebral anoxic-ischemic pathology. This is due not only to greater precision in diagnosing lesion extension, but also to earlier detection of lesions with the diffusion of weighted imagery. The aim of this iconographic review is to illustrate the main MRI aspects of anoxic-ischemic encephalopathy in a pedagogical way. After a brief physiopathology reminder, the different cerebral lesions are studied in a first chapter on the premature newborn pathology and a second chapter on full-term newborn pathology.

[Conventional and diffusion magnetic resonance imaging in the acute phase of severe traumatic brain injury]. / Apports de l'IRM conventionnelle et de l'IRM de diffusion à la phase aiguë du traumatisme crânien grave.

Neuro-imaging is essential for the initial evaluation and subsequent control in the acute stage of severe head injury. In these indications tomodensitometry (TDM) has a pivotal role. Despite the well recognized contribution of magnetic resonance imaging (MRI) to the investigation of most of acute neurological pathologies, MRI is not still a routine procedure for the initial investigation of patients with acute head injury. The superiority of morphological and functional MRI on TDM in this indication is discussed.

Supratentorial primitive neuroectodermal tumours of the brain: multidirectional differentiation does not influence prognosis. A clinicopathological report of 18 patients.

AIMS: To examine the clinical and pathological characteristics of supratentorial primitive neuroectodermal tumours (PNETs) in a retrospective series of 18 patients, according to the strict definition of the World Health Organization classification of tumours that excludes other types of malignant embryonal tumours of the brain. METHODS AND RESULTS: Eleven children and seven adults with supratentorial PNETs were diagnosed between 1993 and 2002 and their medical records were reviewed. An immunohistochemical study was performed on formalin-fixed paraffin-embedded tissue of 18 primary tumours and five recurrences with antibodies for neuronal (neuron specific enolase, synaptophysin, neurofilament, chromogranin A), epithelial [epithelial membrane antigen (EMA), cytokeratin], glial [glial fibrillary acidic protein (GFAP)], muscle (desmin, h-caldesmon, alpha-smooth muscle actin, myogenin) differentiation and with two anti-CD99 antibodies. All tumours showed at least one neuronal marker except chromogranin A; a variable number of cells were GFAP+ or EMA+ in 18/23 tumours. Six primary tumours and one recurrence were positive for cytokeratin and/or one muscle antigen except myogenin. CD99 was observed in 33% of the cases. The mean duration of overall survival was 20 months. The estimated overall survival rates were 61% at 1 year, 29% at 2 years, and 18% at 3 years. Two factors of poor prognosis were identified by univariate analysis: a positive cerebrospinal fluid cytology at diagnosis and the absence of complete resection. No distinct immunophenotype was statistically related to survival. CONCLUSIONS: A multidirectional differentiation is a frequent event in supratentorial PNETs but has no apparent influence on the outcome of this aggressive neoplasm.

[Emergency imaging of cerebrovascular accidents]. / Imagerie des accidents vasculaires cerebraux en urgence.

Over the last 25 years, advances in neuroimaging have significantly changed the evaluation and management of acute stroke syndromes. In the seventies, computed tomography (CT) could differentiate between ischemic and hemorrhagic stroke. Magnetic resonance imaging (MRI) is nowadays the imaging modality of choice in the initial assessment of acute stroke. MRI images can better discriminate acute, subacute and chronic infarcts, differentiate venous from arterial infarcts, detect arterial dissection, stenosis or occlusion. Diffusion-weighted images are highly sensitive and specific to acute infarction and the combination with perfusion technique is suitable to define potentially reversible ischemia (area of cerebral "mismatch" which is thought to represent the so-called ischemic penumbra). This penumbra is a potential therapeutic target of valuable interest for the treating physician.

Treatment of epistaxis in Rendu-Osler-Weber disease by in situ Ethibloc injections.

After a brief review of Rendu-Osler-Weber disease, we present the results from a series of 13 patients treated by Ethibloc injections for epistaxis. Based on a review of the literature, typical treatments are presented along with discussion of their efficacy and side effects. In our series, 90% of patients improved after only one injection. All patients reported a decrease in hemorrhage, especially patients with recurrent epistaxis. Five of nine patients reported a decrease in the length of the bleeding episodes. Improvement was reported by 85% of patients within one month following Ethibloc injection. Fifty percent of these patients have persistent good results at 4 Year follow-up. Our results indicate that Ethibloc injections are safe and effective as an alternative treatment for patients that have failed standard treatment options.

[Trismus, pseudobulbar syndrome and cerebral deep venous thrombosis]. / Trismus, syndrome pseudobulbaire et thrombose veineuse profonde cérébrale.

We report a case of cerebral deep venous thrombosis that manifested clinically by a pseudobulbar syndrome with major trismus, abnormal movements and static cerebellar syndrome. To our knowledge, only three other cases of deep cerebral venous thrombosis associated with cerebellar or pseudobulbar syndrome have been published since 1985. The relatively good prognosis in our patient could be explained by the partially intact internal cerebral veins as well as use of early anticoagulant therapy. There was a spontaneous hyperdensity of the falx cerebri and the tentorium cerebelli on the brain CT scan, an aspect highly contributive to diagnosis. This hyperdensity of the falx cerebri was found in 19 out of 22 cases of deep venous thrombosis detailed in the literature.

Use of half-dose gadolinium-enhanced MRI and magnetization transfer saturation in brain tumors.

The aim of this study was to search if half-dose gadolinium (Gd)-enhanced MR imaging with magnetization transfer saturation (MT) can replace standard-dose T1-weighted spin echo (SE) without MT saturation in brain tumors. Thirty patients with a total of 33 brain tumors (14 gliomas, 13 meningiomas, 6 metastases) were prospectively studied using T1-weighted SE half-dose of Gd with MT, and T1-weighted SE standard-dose Gd without MT. The contrast-to-noise ratio (CNR) of the two sequences was calculated and four radiologists reviewed qualitatively the images of the two sequences. There was no significant difference between both techniques for quantitative analysis (Wilcoxon test). However, there was a good agreement between sequences to evidence an intraclass correlation coefficient (r = 0.70) of all lesions. In cases of meningioma, the agreement was better (r = 0.84). The results show a difference in the qualitative data between the two sequences, suggesting the use of the T1-weighted MR images with MT and half-dose of Gd with good results in the whole tested parameters except the lesional edema and the presence of artifacts. Half-dose T1-weighted SE with MT can replace standard-dose T1-weighted SE without MT with no loss of contrast enhancement in investigation of meningiomas and saving 50% of the contrast material.

[Unusual complication of rendu-osler-weber disease: paramedian bulbar syndrome]. / Complication inhabituelle de la maladie de Rendu-Osler-Weber : le syndrome bulbaire paramédian.

We report a case of arteriovenous malformation of the brainstem, revealed by a progressive right pyramidal syndrome and an atrophy of the left hemi-tongue in a man presenting a Rendu-Osler-Weber disease. After embolization the clinical course was stationary.

[Post-traumatic intracranial arterial aneurysm. Two cases with review of the literature]. / Anévrismes artériels intracrâniens post-traumatiques. A propos de deux cas et revue de la littérature.

Post-traumatic intracranial aneurysms are rare entity, which can appear following even benign head injuries. Their clinical manifestations are various, from a typical SAH to an uncommon intracerebral hematoma. Medical history runs usually from a couple of days to several years. Two cases of intracranial aneurysm have been observed from 1995 to 1998. The first case presented as a cortical aneurysm in a cerebral contusion following a week of evolution. The second case presented as a cortical hematoma with a head trauma 10 years before. All patients were operated on with uneventful follow-up. Post-traumatic intracranial aneurysms can exhibit an increase in size or a spontaneous thrombosis. Diagnosis is made by angiography, which has to be repeated if treatment has to be delayed. Best results are obtained by exclusion of the lesion, if allowed by the patient's condition.

Is there a correlation between scores of nociceptive behavioral responses to formalin injections given at different body sites in the rat?

Correlations between behavioural nociceptive responses to an injection of formalin solution in the hindpaw and upper lip were sought in 28 male rats divided into two groups. One group received a first injection in the hindpaw and 7 days later, a second one in the lip (paw-lip group). The injection order was reversed in the second group (lip-paw group). After each injection, the duration of lip rubbing for the orofacial formalin test, the duration of paw licking and the number of paw flinchings for the hindpaw test were measured. The Spearman test revealed no correlation between lip rubbing and paw flinching in either group but a significant correlation between lip rubbing and paw licking occurred in both groups.

Predictibility of the cervical origin of the anterior spinal artery.

SUMMARY: The anatomic study (under a surgical microscope) of 25 brains that had previously been injected with colored latex confirmed the fact that in the majority of cases, the anterior spinal artery results from the merging of two arterioles which both derive from two vertebral arteries. This bilateral nature is determined by the symmetric origin of the posterior inferior cerebellar arteries. When the conformation is asymmetrical, a single anterior spinal artery branches off from the vertebral artery that supplies the closest posterior inferior cerebellar artery.

The anterolateral transpetrosal approach to the clivus and the pons. Preoperative embolisation of the inferior petrosal sinus.

SUMMARY: Resection of skull base tumors is a real challenge in the field of neurosurgery. Anterior petrosectomy gives one of the best approaches to reach the clivus and the pons while avoiding cerebral retractions which are responsable for postoperative complications. Using a subtemporal extradural or an infratemporal preauricular route, the anterolateral transpetrosal approaches produce a resection of the anterior pyramidal bone around the petrous carotid artery. These approaches offer a direct view of the posterior fossa dura between the two petrosal sinuses, to give access to the petroclival area. However, exposure of the intradural structures in the foramen magnum area is always restricted because of the inferior petrosal sinus. Its peroperative hemostasis is always truly challenging on account of its size and encasement within a wide petrooccipital suture. The goal of the preoperative embolisation of the inferior petrosal sinus, whenever possible, is to allow its peroperative section without haemorrhage for a wider exposure along the lower clivus.

[Vascular complications during surgery of lumbar disk herniation. Apropos of 3 personal cases and 37 cases from a national investigation]. / Accidents vasculaires au cours de la chirurgie de la hernie discale lombaire. A propos de 3 cas personnels et de 37 cas colligés dans une enquête nationale.

Three personal cases of iatrogenic vascular complications (two arterial wounds and one arteriovenous fistula) induced by lumbar herniation surgery led to a French national investigation among vascular and neurosurgical units where 37 other such cases have been discovered over 10 years (1984-1994). In 23 cases, the initial symptomatology was collapses by arterial (22 cases) or venous (one case) hemorrhage requiring emergency vascular repair surgery; in 17 cases an arterio-venous fistula was found in a period varying from a few hours to 5 years after surgery; it was revealed by cardiac failure, lower limb edema or abdominal thrill. Among the 40 cases, 77% occurred at the L4-L5 level; the mortality was 5%, and the morbidity was 27%. Origin, causes and prevention are discussed.