A Dilp8-dependent time window ensures tissue size adjustment in Drosophila.

The control of organ size mainly relies on precise autonomous growth programs. However, organ development is subject to random variations, called developmental noise, best revealed by the fluctuating asymmetry observed between bilateral organs. The developmental mechanisms ensuring bilateral symmetry in organ size are mostly unknown. In Drosophila, null mutations for the relaxin-like hormone Dilp8 increase wing fluctuating asymmetry, suggesting that Dilp8 plays a role in buffering developmental noise. Here we show that size adjustment of the wing primordia involves a peak of dilp8 expression that takes place sharply at the end of juvenile growth. Wing size adjustment relies on a cross-organ communication involving the epidermis as the source of Dilp8. We identify ecdysone signaling as both the trigger for epidermal dilp8 expression and its downstream target in the wing primordia, thereby establishing reciprocal hormonal feedback as a systemic mechanism, which controls organ size and bilateral symmetry in a narrow developmental time window.

Studying radiolytic ageing of nuclear power plant electric cables with FTIR spectroscopy.

Due to the willingness to extend the nuclear power plants length of life, it is of prime importance to understand long term ageing effect on all constitutive materials. For this purpose gamma-irradiation effects on insulation of instrumentation and control cables are studied. Mid-infrared spectroscopy and principal components analysis (PCA) were used to highlight molecular modifications induced by gamma-irradiation under oxidizing conditions. In order to be closer to real world conditions, a low dose rate of 11Gyh-1 was used to irradiate insulations in full cable or alone with a dose up to 58 kGy. Spectral differences according to irradiation dose were extracted using PCA. It was then possible to observe different behaviors of the insulation constitutive compounds i.e. ethylene vinyl acetate (EVA), ethylene propylene diene monomer (EPDM) and aluminium trihydrate (ATH). Irradiation of insulations led to the oxidation of their constitutive polymers and a modification of filler-polymer ratio. Moreover all these modifications were observed for insulations alone or in full cable indicating that oxygen easily diffuses into the material. Spectral contributions were discussed considering different degradation mechanisms.

Coordination of organ growth: principles and outstanding questions from the world of insects.

In animal species undergoing determinate growth, the making of a full-size adult body requires a series of coordinated growth events culminating in the cessation of growth that precedes sexual maturation. The merger between physiology and genetics now coming to pass in the Drosophila model allows us to decipher these growth events with an unsurpassed level of sophistication. Here, we review several coordination mechanisms that represent fundamental aspects of growth control: adaptation of growth to environmental cues, interorgan coordination, and the coordination of growth with developmental transitions. The view is emerging of an integrated process where organ-autonomous growth is coordinated with both developmental and environmental cues to define final body size.

[Chiari type 1 malformation and magnetic resonance imaging]. / La malformation de Chiari de type 1 à l'ère de l'imagerie par résonance magnétique.

The Chiari type 1 malformation is common. Unlike the Chiari type 2 and 3 malformations, it may remain latent for a long time, becoming symptomatic only in adulthood. The introduction of MRI has resulted in an increased number of diagnoses of this malformation in pediatric patients. It appears to be related to underdevelopment of the posterior cranial fossa. It must be differentiated from acquired tonsillar herniation, particularly when herniation results from intracranial hypotension; these cases are sometimes reported as acquired Chiari I malformation with spontaneous resolution. Tonsillar ectopia may cause symptoms by its direct effect on any or all of the medulla and the cerebellar and upper spinal cord. The most suggestive of the oculomotor disturbances is oscillopsia with downbeat nystagmus. Dysphonia and dysphagia are common. Potentially serious autonomic disturbances are also frequent: sleep apnea, respiratory failure, syncope and even sudden death. Another risk is syrinx formation, resulting from obstruction of CSF circulation in the cisterna magna. Syringomyelia is detected in 32 to 74% of patients with Chiari I malformation. Treatment is surgical. Posterior fossa decompression is achieved by suboccipital craniectomy combined with laminectomy of the upper cervical segments. Surgical intervention is indicated when the malformation is symptomatic and there is no doubt that it is the cause of the symptoms. When a Chiari I malformation is identified fortuitously on MRI, long-term monitoring is essential. The risk of developing symptoms increases over time. Patients should be advised not to participate in contact sports.

[Disruption of the thoracic spinal cord with unilateral ligament damage and no spine fracture]. / Section traumatique de la moelle épinière thoracique sans lésion osseuse avec atteinte ligamentaire unilatérale.

We report a case of total spinal cord disruption confirmed surgically. The spinal cord injury resulted from a traumatic event involving the thoracic spine which did not provoke any bone lesion. The patient presented joint injury and unilateral ligament damage. No spinal fracture was observed. In patients with neurological signs, the imaging work-up should associate CT-scan and magnetic resonance imaging to obtain a complete study of the bone and joint structures as well as the ligaments and the spinal cord.

EPR study of gamma induced radicals in amino acid powders.

To better understand the composite character of amino acids EPR spectra, the radiolysis and reactions which occurred after irradiation of amino acids, a comparative EPR study of a few simple amino acids has been made in order to identify qualitatively and quantitatively the different radiation-induced radicals in amino acid powders. A spin-trapping methodology has been developed and carried out on irradiated glycine, alanine and valine.

Early sedimentation and crossover kinetics in an off-critical phase-separating liquid mixture.

Early sedimentation in a liquid mixture off-critically quenched in its miscibility gap was investigated with a light attenuation technique. The time evolution of the droplet distribution is characteristic of an emulsion coalescing by gravitational collisions. This sedimentation behavior gave access to the phase-separating kinetics, and a crossover on the way toward equilibrium was observed, which separates free growth from conserved order-parameter coarsening with a crossover time fitting well with theoretical predictions.

[Functional anatomy of the central nervous system]. / Anatomie fonctionnelle du système nerveux central.

The central nervous system (CNS) has a particular regional functional anatomy. The morphological support of cognitive functions can now be depicted using functional imaging. Lesions of the central nervous system may be responsible of specific symptoms based on their location. Current neuroimaging techniques are able to show and locate precisely macroscopic lesions. Therefore, the knowledge of functional anatomy of the central nervous system is useful to link clinical disorders to symptomatic lesions. Using radio-clinical cases, we present the functional neuro-anatomy related to common cognitive impairments.

[Primary acute disseminated encephalomyelitis in the adult. Study of 6 year follow-up of 2 patients]. / Encéphalomyélite aiguë disséminée primitive de l'adulte. Etude de deux patients suivis pendant 6 ans.

INTRODUCTION: The relationship between acute disseminated encephalomyelitis (ADEM), a monophasic disease, and multiple sclerosis (MS), a potentially progressive disease with periods of recurrence or remission, remains debatable. In a large number of patients, the diagnosis initially retained is that of ADEM, whilst the progression is subsequently towards a defined MS. This has incited some authors to consider that there is a continuum between these two diseases and to underline the frailty of the criteria retained for the diagnosis of ADEM. Further interest has presently been paid to this subject and the question of whether a basic treatment of MS should be started after the first episode has been raised, although such a treatment is obviously not justified if the diagnosis retained is an ADEM. OBJECTIVES: Two cases observed in adults, followed-up for 6 years, contribute to the validation of a number of clinical, biological and radiological arguments which are all in favor of the diagnosis of ADEM versus that of an initial episode of MS. CLINICAL ARGUMENTS: These are the absence of any neurological past history, the existence of a multi-focal neurological symptomatology right from the start and, particularly in children, the presence of a meningeal syndrome. BIOLOGICAL ARGUMENTS: Presence in the cephalo-spinal liquid, of an increase in cells and cervicospinal proteins to levels not usually found in MS. RADIOLOGICAL ARGUMENTS: MRI reveals multi-focal, extensive and bilateral lesions, beneath the cortex rather than peri-ventricular, which may extensively involve the thalamus and the bone marrow; these lesions are of the same age and often regress.

[Inflammatory hypertrophic cranial pachymeningitis]. / Les pachyméningites crâniennes hypertrophiques inflammatoires.

DEFINITION: Inflammatory cranial hypertrophic pachymeningitis (ICHP) is a fibrosing inflammatory process that thickens the dura mater. This condition is increasingly reported owing to the use of CT and MRI. CLINICAL ASPECTS: Chronic headache and cranial neuropathies are the main presentations. Generally the erythrocyte sedimentation rate is elevated and cerebrospinal fluid is inflammatory. DIAGNOSIS: Non-invasive imagery visualizes the thickening of the dura mater that may be focal or diffuse. On MRI diffuse intense enhancement due to intra cranial hypotension must not be confused with ICHP. Focal thickening of the dura may be tumoral. Biopsy of the thickened dura mater is useful for confirming the inflammatory nature of the process and for orienting the etiological diagnosis. "SECONDARY" ICHP: ICHP has many causes, infectious and noninfectious. It may be the presenting manifestation of systemic diseases as sarcoïdosis or Wegener's granulomatosis. "IDIOPATHIC" ICHP: A diagnosis of exclusion, ICHP might be an isolated intracranial localization of multifocal fibrosis, an ill-defined autoimmune disease. TREATMENT: A specific treatment is indicated in some cases of secondary ICHP. In most cases treatment relies on corticosteroids an/or immunosuppressive therapy.

Priapism in a sickle cell prepuberal child.

Between 1985 and 1995, six sickle cell children listed SS were hospitalized in our department for priapism persisting after 24 hours of medical treatment. Two cases regressed after 6 hours of treatment follow-up. Four children were treated by a corpus cavernosum puncture, through the gland, leading to priapism detumescence in 3 cases. In one of our cases, the persistence of priapism induced us to perform a spongiocavernous anastomosis at the 72nd hour. One of the children developed a cerebrovascular accident 10 days after the beginning of the priapism. The other children have been re-examined. They have not presented any reccurence and have normal erection after puberty. Starting from a literature review, we explain the principles we adopted. The physiopathology of priapism in sickle cell patients remains unclear, for both high and low flows do exist. In addition to the risks related to blood products, the treatment by transfusional exchange involves neurological risks and must not delay any surgery. Analgesic treatment is often required. Corpus cavernosum puncture is efficient, with no fibrosis risk. In case of failure, a cavernospongious shunt, with a biopsy needle, can be performed at the same time. Surgical anastomoses are then proposed in case of priapism persistence. General evolution is satisfactory. But the sickle cell patient's priapism needs a long-term follow-up in order to recognise any minor recurrences. The latter could be the principal cause of fibrosis and impotency.

Cerebral venous infarction following thrombosis of the draining vein of a venous angioma (developmental abnormality).

We report two cases of cerebral venous angioma presenting as venous infarction, one in the left parietal lobe, the other in the left frontal lobe. Cerebral imaging demonstrated thrombotic occlusion of the draining vein of the venous angioma associated in the latter case with thrombosis of the anterior part of the superior longitudinal sinus. Both patients were free of coagulopathy. They were treated with anticoagulant therapy. One completely recovered, while the other was left with slight residual disability. Thrombosis of the draining vein has been reported in only 6 previous cases, of whom only 2 received anticoagulant therapy. Discovery of a venous angioma in the diagnostic workup of a patient with recent neurological disorders should raise the question of a possible occlusion of the draining vein and lead to an appropriate therapy.

[Cerebral venous thromboses]. / Les thromboses veineuses cérébrales.

UNLABELLED: VARIABLE EXPRESSION: The clinical expression of cerebral venous thrombosis varies widely. The only manifestation may be an intracranial hypertension if the thrombus is limited to the superior longitudinal sinus or a predominant lateral sinus. Thrombosis of cortical veins, alone or in association with a sinus thrombus causes venous infarction. PROGNOSIS: Deep venous thrombosis generally leads to coma with signs of intracranial hypertension. However, partial or complete recovery is possible, even with a severe initial presentation, underlining the importance of early diagnosis and treatment. DIAGNOSTIC METHODS: Magnetic resonance imaging (MRI) coupled with magnetic resonance angiography (MRA) can usually confirm the diagnosis without conventional angiography. ETIOLOGICAL DIAGNOSIS: Cerebral venous thrombosis often follows prethrombotic conditions. Infectious causes only account for 10% of the cases and no cause can be identified in about 1 out of 5 cases. TREATMENT: Anticoagulation is indicated even in case of venous infarction with spontaneous bleeding. Thrombolysis can be proposed, particularly for deep venous thrombosis.