Layer filtering for seafloor scatterers imaging.

The image source method in acoustics is well known to simulate reverberation. It has also been recently used for characterization of seafloor sound-speed structure. The idea is to detect image sources by imaging techniques to obtain information about the environment. In this paper, the idea is to use the detection of image sources to remove reflections from plane interfaces in recorded signals and perform imaging with this filtered signal. This imaging process highlights scatterers because their wave front shapes are different than those from plane interfaces. Applications can be in seafloor buried object detection or scattering analysis from interface roughnesses or volume heterogeneities.

[Type 2 neurofibromatosis: intergenerational differences in genetic and clinical expression]. / Neurofibromatose de type 2 : différence inter-générationnelle d'expression génétique et clinique.

INTRODUCTION: Neurofibromatosis type 2 (NF2) is a rare dominantly inherited disease. Its clinical presentation can be completely different in children and adults and early diagnosis is often difficult. The NF2 gene molecular analysis can help for diagnosis, but its result can be negative in case of NF2 mosaicism. OBSERVATIONS: We report the case of a 43-year-old man who had developed a severe phenotype with bilateral vestibular schwannomas at 19 years of age. His son presented a retinal hamartoma with loss of vision in his right eye at 2 months of age. At 9 years of age, asymptomatic schwannomas of the cranial nerves were discovered: cranial nerves X (left), XI (left), and VIII (bilateral). Partial constitutional NF2 deletion (from exons 2-7) was detected in his son. The deletion was not detectable in the DNA blood of his father and we strongly suspect a mosaic form of NF2. CONCLUSION: Ophthalmological manifestations can be the initial sign of NF2 in childhood. These features must be actively sought during the first year of life in individuals at risk of NF2. NF2 mosaicism is often described as a mild form of NF2 with a very low risk of transmission to the carrier's children. We show that NF2 mosaicism can sometimes develop severe NF2 symptoms and we confirm that the transmission risk to the offspring depends on the proportion of zygotes carrying the mutation. NF2 remains a life-limiting and life-spoiling condition. Early diagnosis is necessary to prevent complications and the follow-up of NF2 patients must be organized throughout life in specialty centers.

Seafloor sound-speed profile and interface dip angle characterization by the image source method.

The image source method is an efficient way to perform a sound-speed tomography for seafloor characterization. To date, however, it has been limited by a locally range-independent approximation. In other words, the layer boundary had to be parallel and flat within the Fresnel zone of the measurement system. Here the method is extended to take into account realistic variations of interface dip angles. To do so, the elliptical wavefront shape approximation of the reflected waves is used. This permits a fairly simple equation relating travel time to the sine of the dip angle, and consequently to an equation for the equivalent medium sound speed. The Radon transform is exploited to extract the dip angle. Simulations with varying layer dip angles and curvature provide insight into the strengths and limitations of the method.

Range dependent sediment sound speed profile measurements using the image source method.

This paper presents a range dependent sediment sound speed profile measurement obtained using the image source method. This technique is based on the analysis of the seafloor reflected acoustic wave as a collection of image sources which positions are linked with the thick-nesses and the sound speed of the sediment stack. The data used were acquired by the NURC in 2009 during the Clutter09 experiment. The equipment used was an autonomous undersea vehicle towing a 1600-3500 Hz frequency band source and a 32 m horizontal line array of 32 hydrophones at 12 m above the seabed. Under the assumption of locally range independent seabed properties, the moving horizontal array provides successive range independent sediment sound speed profiles along a track to obtain the range and depth dependent structure of the seafloor. Two key steps include recovery of the time-varying unknown array shape from the data and spatial filtering of the successive sound speed profiles. A comparison of the image source method result and seismic data along nearly the same 14 km track indicates that the seabed stratigraphy is correctly mapped by this method.

Sound speed profile characterization by the image source method.

This paper presents the first results of an imaging technique that measures the geoacoustic structure of a seafloor in shallow water areas. The devices used were a broadband (100 Hz-6 kHz) acoustic source towed by a ship and a vertical array. Among all the acoustic paths existing in the water column, two are used: the direct one and the seabed-reflected one, the latter being composed of the reflections from the seafloor's surface as well as that from each buried layer. Due to the good time resolution of the signal and to the short range configuration, the reflected signal can be modeled as a sum of contributions coming from image sources relative to the seabed layers. The seabed geometry and the sound speed profile can then be recovered with the detection and localization of these image sources. The map of the image sources is obtained by a function that combines back-propagation of signals and knowledge of the emitted pulse. The thickness and sound-speed of each layer is finally obtained by a position analysis of the image sources. The results obtained by this data-driven algorithm on both at-sea and synthetic data are satisfactory.

Yolk and albumen corticosterone concentrations in eggs laid by white versus brown caged laying hens.

Maternal stress in birds can have permanent transgenerational effects through the transmission of stress hormones to offspring via the egg yolk. Previous studies have shown that White Leghorn hens show a heightened response to stress compared with Hy-Line Brown hens, producing significantly more corticosterone and displaying longer bouts of tonic immobility after handling, whereas baseline levels of corticosterone are similar between the strains. We tested the hypothesis that higher stress responsiveness would correspond to chronic accumulation and thus higher concentrations of corticosterone in egg yolks after exposure to stressors associated with routine maintenance. Eggs were collected from white and brown hens that were undisturbed except for daily feeding and routine egg collections. Corticosterone was quantified in plasma, egg yolks, and albumen and compared between strains. We predicted that corticosterone concentrations in yolk would be higher in eggs from white versus brown hens but that albumen corticosterone would not differ between strains due to the short term of albumen deposition. As predicted, yolk corticosterone concentrations were significantly higher in eggs produced by white hens, approximately twice those found in eggs laid by brown hens. Plasma and albumen concentrations of corticosterone were similar between groups. These results suggest that offspring hatching from eggs laid by White Leghorn hens are exposed to significantly more corticosterone through concentration in the egg yolk, which could permanently imprint offspring physiology and behavior.

[Usefulness of systematic brain magnetic resonance imaging in children with neurofibromatosis type 1]. / La réalisation systématique de l'imagerie par résonance magnétique cérébrale a-t-elle un intérêt chez l'enfant atteint de neurofibromatose de type 1?

BACKGROUND AND AIM: The aim of this study was to evaluate the usefulness of systematic screening of asymptomatic neurofibromatosis type 1 (NF1) children with magnetic resonance imaging (MRI). PATIENTS AND METHODS: We retrospectively reviewed the MRIs of children diagnosed with NF1 disease according to the National Institutes of Health criteria, who had been followed for at least 1 year by the department of pediatric neurology (Lyon, France). Brain MRI was systematically performed in asymptomatic patients under 6 years of age. RESULTS: One hundred patients with a median follow-up of 3.7 years (range, 1-8.6 years) were reviewed. Brain MRI was performed in a total of 94 children. Nine optic pathway gliomas were detected in symptomatic patients. Six children had symptoms caused by the tumor. Gliomas remained stable in 10 patients; 1 symptomatic glioma in an 8-year-old girl required treatment. Spontaneous regression was seen in 1 patient. CONCLUSION: Our results suggest that MRI screening of asymptomatic children to detect optic pathway gliomas does not improve the therapeutic decision and should not be performed systematically. We suggest further investigation in collaboration with the French NF Network.

Does the RET variant G691S influence the features of sporadic medullary thyroid carcinoma?

OBJECTIVE: The RET (rearranged during transfection) proto-oncogene G691S variant is over-represented in the germline of patients with sporadic medullary thyroid carcinoma (sMTC) vs. normal controls but so far is not associated with any medical or pathological features of the tumour. The aim of our study was to assess the influence of this variant on the age of onset, clinical, biological and pathological features of sMTC. DESIGN AND PATIENTS: One hundred patients with histologically proven MTC, for whom the germline genetic analysis of RET was negative and medical records were available, were included in the study. RESULTS: Patients with the heterozygous GS variant or the homozygous SS variant (n = 36) were on average 8.0 years younger than patients with the wild-type GG variant (n = 64, mean age 43.9 vs. 51.9 years, P < 0.01). The former group did not differ from the wild-type group in terms of MTC size, prevalence of C-cell hyperplasia (CCH) or papillary thyroid carcinoma (PTC). However, the prevalence of an increased preoperative basal calcitonin (bCT) level (> 1000 pg/ml) was 2.75-fold higher in the patients with the GS or SS variant than in those with the wild-type variant (P < 0.001). The proportion of patients with lymph node metastases was also higher in the former group (P < 0.05). Multivariate analysis confirmed that the presence of the RET variant is independently associated with higher preoperative bCT values (P = 0.011). CONCLUSIONS: Our data demonstrate that the RET G691S variant could modulate the age of onset of sMTC as demonstrated previously for familial tumours. Moreover, this variant is an independent predictor of a higher basal calcitonin synthesis rate in patients with sMTC.

[Utility of 18 FDG positon emission tomography in detection of sarcomatous transformation in neurofibromatosis type 1]. / Intérêt de la tomographie par émission de positons au fluorodéoxyglucose 18 dans la détection des neurofibrosarcomes au cours de la neurofibromatose de type 1.

BACKGROUND: The appearance of malignant peripheral nerve sheath tumours (MPNST) marks a critical stage in the course of neurofibromatosis type 1 (NF1). Since the diagnostic criteria are fairly non-specific, histological examination alone can confirm malignancy. We assessed the value of 18 FDG positron emission tomoscintigraphy (PET scan) in screening for such malignant tumours. PATIENTS AND METHODS: Between October 2000 and August 2006, all of our patients with NF1 and suspected MPNST underwent PET scan. Inclusion criteria consisted of clinical signs (increased tumour size or induration, pain) and/or laboratory values. Analysis of PET scan images, based upon determination of tumour/liver binding ratio with a cut-off point of 1.5 times hepatic binding, was used to classify lesions as non-suspect or pathological. In the case of suspect lesions, histological analysis was performed. For non-suspect lesions, patients either underwent monitoring or excision of the lesion where necessary and technically feasible. RESULTS: Thirty-eight patients with 49 tumours were included in the study. In 8 patients, PET scan showed suspect lesions (12 tumours), and histological analysis of these tumours revealed 6 MPNST. In 30 patients (37 tumours) PET scan showed non-suspect binding, and no malignant tumours were demonstrated either on histological examination or after mean follow-up of 33.5 months. PET scan thus demonstrated a sensitivity and negative predictive value of 100%, specificity of 86%, and a positive predictive value of 50%. The ratios of positive and negative probability were respectively 7.14 and 0. DISCUSSION: Our study, to our knowledge the most extensive yet performed, demonstrates the value of PET scan in detecting MPNST, particularly based on its 100% negative predictive value. To date, other than biopsy, no examinations allow diagnosis with any certainty. The literature reports 2 studies analysing the value of PET scan. The first involved 18 NF1 patients with 23 plexiform neurofibromas: of 7 tumours with hyperbinding, 5 were MPNST. The second study concerned 5 NF1 patients with a total of 15 tumours: 7 tumours showed hyperbinding, of which 6 were MPNST. Using the same evaluation criteria, our study yielded comparable results. The negative predictive value of 100% provides a strong argument in favour of a benign tumour. CONCLUSION: Our study confirms the value of PET scan in the detection of NF1 even though false positives require medical-surgical confirmation before any potentially detrimental therapeutic decisions may be made.

Rapid Determination of Rice Cultivar Responses to the Sheath Blight Pathogen Rhizoctonia solani Using a Micro-Chamber Screening Method.

An accurate greenhouse screening method has not been developed previously to identify host response to sheath blight disease caused by Rhizoctonia solani Kühn that causes significant economic losses in rice yield worldwide. The unavailability of a robust screening system in the greenhouse has made it difficult to quantify disease reactions to R. solani, and has hampered studies on the genetics of resistance and plant breeding efforts to improve resistance. In an effort to develop a standardized laboratory micro-chamber screening method to quantify resistance to R. solani in rice, five rice cultivars, representing a wide range of observed disease reactions under field conditions, were examined in a blind inoculation test at three locations (Arkansas, Texas, and Colombia). Rice seedlings were inoculated at the three- to four-leaf stage with potato dextrose agar plugs containing mycelium and then covered with a 2- or 3-liter transparent plastic bottle for maintaining high humidity after inoculation. Two cultivars, Jasmine 85 and Lemont, that consistently have shown the highest and lowest levels of resistance, respectively, in previous field and greenhouse studies, were used as standards. Concurrent field experiments in Arkansas and Texas also were performed to compare the greenhouse disease ratings with those observed under field conditions. Overall, the relative disease ratings of the seven test cultivars were consistent between test locations and with field evaluations. Thus, the micro-chamber screening method can be used as an effective approach to accurately quantify resistance to the sheath blight pathogen under controlled greenhouse conditions and should help expedite the selection process to improve resistance to this important pathogen.

[Neurofibromatosis type 1 or Von Recklinghausen's disease]. / La neurofibromatose 1 (NF1) ou maladie de Von Recklinghausen.

OBJECTIVES: Neurofibromatosis 1(NF1) is one of the most common genetic diseases. NF1 is an autosomal dominant genetic disorder and half of affected individuals have NF1 as the result of a new gene NF1 mutation. The offspring of an affected individual have a 50% risk of inheriting the altered NF1 gene. The disease manifestations are extremely variable, even within a family. NF1 is characterized by multiple cafe au lait spots, axillary and inguinal freckling, multiple discrete dermal neurofibromas, and iris Lisch nodules. Learning disabilities are frequent. Less common but potentially more serious manifestations include plexiform neurofibromas, optic and other central nervous system gliomas, malignant peripheral nerve sheath tumors, vasculopathy, and osseous lesions. CURRENT KNOWLEDGES AND KEY POINTS: Since the original National Institutes of Health consensus Development Conference in 1987, there have been significant progress toward a more complete understanding of the molecular-bases for neurofibromatosis 1 and the routine follow-up for the care of the NF1 patients. The authors review the present data on the clinical and molecular aspects of the neurofibromatosis 1. FUTURE PROSPECTS AND PROJECTS: NF1 requires life-long management adapted to age and multidisciplinary structures are particularly well adapted to the diversity of the manifestations of this pathology. The French NF-France Network has been created in 2001 to federate the French multidisciplinary structures for neurofibromatosis and harmonize the follow-up of NF1 patients in France.

[Congenital pseudarthrosis of the forearm in a neurofibromatosis patient: case report and review of the literature]. / Pseudarthrose congénitale de l'avant-bras associée à la neurofibromatose: à propos d'un cas et revue de la littérature.

We report a case of congenital pseudarthrosis of the forearm associated with neurofibromatosis type 1 which was treated by free vascularized periosteal flap transplant and repeated bone grafting. The young female patient recovered good hand and forearm function. A review of the literature revealed the rare occurrence of this disease (approximately 100 cases reported to date), which probably explains the wide variety of surgical proposals.

[Neurofibromatosis 1: recommendations for management]. / Neurofibromatose 1: recommandations de prise en charge.

Twenty experts, members of a French medical network devoted to neurofibromatosis 1 have elaborated recommendations for the management of the disease. Bibliography was obtained through a Medline of articles from 1966 to 1999 for the terms neurofibromatosis, NF1, neurofibroma and from textbooks. A consensual document was written taking into account extracted data. An annual careful clinical examination is recommended except in cases with complications. Screening investigations are not recommended due to the rarity of complications, generally symptomatic and easily detected during the clinical follow-up. The only controversial exception might be magnetic resonance imaging for early detection of optic pathway gliomas in young children. A co-ordinated follow-up in specialised multidisciplinary centres, providing patients with a rational management, is recommended.

[Cardiogenetics in the year 2000]. / La cardiogénétique en l'an 2000.

This review article presents the up-to-date of knowledge progression during the past decade in the genetics of cardiopathies. The cardiopathies presented here have all a mendelian type of inheritance but this list is not exhaustive.

Non-C282Y familial iron overload: evidence for locus heterogeneity in haemochromatosis.

Haemochromatosis (HC) is an autosomal recessive disease with progressive iron overload leading to midlife onset of clinical complications. The causal gene (HFE) maps to 6p, in close linkage with the HLA class I genes. An HFE candidate gene recently identified has two missense mutations (C282Y and H63D) associated with the disease. Here we document the phenotypic and genetic analysis of a nuclear family comprising two sibs with symptomatic and massive iron overload before the age of 25. The disease seemed to be recessively transmitted and fitted the agreed criteria for haemochromatosis, but was neither associated with the C282Y and H63D mutations nor linked with HLA markers. Our data strongly support locus heterogeneity in haemochromatosis by showing evidence that the gene responsible for juvenile haemochromatosis (JH) does not map to 6p. In the absence of clear cut phenotypic distinction from typical haemochromatosis, patients below 30 years of age and C282Y negative should be considered as putative juvenile cases. This has practical implications in genetic counselling and family management.