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P Fleury

Publications and source records attributed to P Fleury.

At least 19 recordsLinked to original sources
PubMed2005

Discovery of very high energy gamma rays associated with an x-ray binary.

X-ray binaries are composed of a normal star in orbit around a neutron star or stellar-mass black hole. Radio and x-ray observations have led to the presumption that some x-ray binaries called microquasars behave as scaled-down active galactic nuclei. Microquasars have resolved radio emission that is thought to arise from a relativistic outflow akin to active galactic nuclei jets, in which particles can be accelerated to large energies. Very high energy gamma-rays produced by the interactions of these particles have been observed from several active galactic nuclei. Using the High Energy Stereoscopic System, we find evidence for gamma-ray emission of >100 gigaelectron volts from a candidate microquasar, LS 5039, showing that particles are also accelerated to very high energies in these systems.

Journal Article↗
PubMed2005

A new population of very high energy gamma-ray sources in the Milky Way.

Very high energy gamma-rays probe the long-standing mystery of the origin of cosmic rays. Produced in the interactions of accelerated particles in astrophysical objects, they can be used to image cosmic particle accelerators. A first sensitive survey of the inner part of the Milky Way with the High Energy Stereoscopic System (HESS) reveals a population of eight previously unknown firmly detected sources of very high energy gamma-rays. At least two have no known radio or x-ray counterpart and may be representative of a new class of "dark" nucleonic cosmic ray sources.

Journal Article↗
PubMed2004

High-energy particle acceleration in the shell of a supernova remnant.

A significant fraction of the energy density of the interstellar medium is in the form of high-energy charged particles (cosmic rays). The origin of these particles remains uncertain. Although it is generally accepted that the only sources capable of supplying the energy required to accelerate the bulk of Galactic cosmic rays are supernova explosions, and even though the mechanism of particle acceleration in expanding supernova remnant (SNR) shocks is thought to be well understood theoretically, unequivocal evidence for the production of high-energy particles in supernova shells has proven remarkably hard to find. Here we report on observations of the SNR RX J1713.7 - 3946 (G347.3 - 0.5), which was discovered by ROSAT in the X-ray spectrum and later claimed as a source of high-energy gamma-rays of TeV energies (1 TeV = 10(12) eV). We present a TeV gamma-ray image of the SNR: the spatially resolved remnant has a shell morphology similar to that seen in X-rays, which demonstrates that very-high-energy particles are accelerated there. The energy spectrum indicates efficient acceleration of charged particles to energies beyond 100 TeV, consistent with current ideas of particle acceleration in young SNR shocks.

Journal Article↗
PubMed1997

[Neurofibromatosis type 1: a survey of 195 patients].

OBJECTIVE: To analyse symptoms and complications in patients with neurofibromatosis type 1 (NF1). All patients were examined in a multidisciplinary outpatient neurofibromatosis clinic during a period of 10 years. DESIGN: Retrospective. SETTING: Academic Medical Center, University Hospital Amsterdam, the Netherlands. METHOD: All data on 450 persons visiting the neurofibromatosis clinic were stored in a database. Data were collected on the results of dermatological, neurological, ophthalmological and general examinations and on family history. For this study the follow-up data of 196 patients with a definite diagnosis of 'NF1' were analysed. RESULTS: In childhood diagnosis NF1 is predominantly based on specific dermatological symptoms such as > 6 café-au-lait (CAL) spots and freckling and on the presence of characteristic ophthalmological signs as two or more Lisch nodules. In this study the frequencies of these symptoms were 98% (CAL). 92% (freckles), and 93% (Lisch nodules) respectively. The frequencies of well-known complications of this disorder are comparable with the literature findings. In this study we found optic pathway glioma (OPG) in 10%, macrocephaly in 36%, hydrocephalus in 5%, retardation in 14%, brain tumours in 5%, kyphoscoliosis in 13%. renal artery stenosis in 0.5% and neurofibrosarcoma in 0.5% of NF1 patients. In children the degree of severity of this disorder is less than in adults, demonstrating the progressive character of the disease. CONCLUSION: The diagnosis of 'NF1' can usually be made by dermatological and ophthalmological examination. In case of a definite diagnosis in childhood regular follow-up is recommended since severe complications, such as OPG and kyphoscoliosis, may occur specifically in childhood and adolescence. For adult patients determination of the degree of severity is essential for the decision whether or not they need regular follow-up; they should have their blood pressure measured annually.

Adolescent↗
PubMed1997

[Axillary lymph node microcalcifications disclosing breast cancer].

Intra nodal calcifications associate with breast cancer are uncommon. The rare publications always describe malignant microcaocifications in axillary lymph nodes, evolving with the primary breast tumor imaged on mammography. In the reported observation, we observed calcified metastatic neoplasm in axillary nodes, preceding the intramammary lesion.

Adult↗
PubMed1995

Family with neurofibromatosis type 2 and autosomal dominant hearing loss: identification of carriers of the mutated NF2 gene.

A family is presented in which neurofibromatosis type 2 (NF2) and autosomal dominant hearing loss segregate in an apparently independent way. The presence of the latter condition caused anxiety in all family members at risk for NF2 in whom hearing loss became apparent. Previously, we identified a G-->A transition in the donor splice site of exon 5 of the NF2 gene in a family member with proven NF2. As expected, the mutation was present in two other family members who fulfilled the diagnostic criteria for NF2. Four out of five family members at risk for NF2 developed hearing loss. Two of these had the G-->A transition. The mutation was absent in the two other individuals with hearing loss and in the fifth family member without hearing loss or other clinical symptoms. In this family, the identification of the underlying NF2 gene mutation excluded NF2 as the cause of hearing loss in two potential carriers of the mutated gene. On the other hand, it enabled the identification of two carriers of the NF2 gene mutation who did not fulfill the diagnostic criteria for NF2. They will have to be monitored very carefully for the development of NF2-associated tumors. The consistent association within this family of a relatively mild clinical phenotype with the NF2 mutation, supports earlier suggestions that intrafamilial variability is small in NF2.

Adult↗
PubMed1994

[Radiosurgical correlations of 61 breast microcalcification foci].

OBJECTIVE. Diagnostic value of breast clustered microcalcifications discovered by mammography. DESIGN. A retrospective study. SETTING. Oncology Center of Rennes. SUBJECTS. 58 women (study group) with breast clustered microcalcifications without palpable tumour were operated. SURGERY. Prior to surgical removal of microcalcification, needle localization was performed. Histological results. We observed, 36 benign lesions (59%), 25 carcinomas (45%), 10 of them in situ and 15 infiltrative. RESULTS. Different radiological parameters were studied in relation to histological results, the vermicular morphology of microcalcification, an increased number, their triangular aspect, provide clue to the presence of breast carcinoma. The cluster of stippled calcification is not, in our series suggestive of a carcinoma, but also requires histopathological study, owig to the fact that in such cases, we have as many carcinomas as benign lesions. FINDING. Careful analysis of microcalcifications, within the clinical context, ensures a safe attitude, and enables one to operate only carcinomas.

Adult↗
PubMed1990

[The clinical aspects and treatment of renal angiolipomas in patients with tuberous sclerosis].

The incidence of multiple and bilateral renal angiomyolipomas in tuberous sclerosis patients is 40-80%. These benign abundantly vascularised tumours are almost always asymptomatic. Most of the symptomatic renal angiomyolipomas measure more than 4 cm. These lesions are attended by a high risk of spontaneous rupture and massive haemorrhage. In our series of 23 tuberous sclerosis patients with renal angiomyolipomas 4 became symptomatic. Three of them were successfully treated wtih transcatheter selective embolization. Preventive embolization of renal angiomyolipomas appears indicated if these measure more than 4 cm. A fifth patient became symptomatic before the diagnosis of tuberous sclerosis was made. She had a forme fruste. She was also successfully treated by the same method.

Adolescent↗
PubMed1990

Genetic heterogeneity in tuberous sclerosis.

Tuberous sclerosis (TSC) is an autosomal dominant disorder characterized by widespread hamartosis. Preliminary evidence of linkage between the TSC locus and markers on chromosome 9q34 was established, but subsequently disputed. More recently, a putative TSC locus on chromosome 11 has been suggested and genetic heterogeneity seems likely. Here we describe an approach combining multipoint linkage analysis and heterogeneity tests that has enabled us to obtain significant evidence for locus heterogeneity after studying a relatively small number of families. Our results support a model with two different loci independently causing the disease. One locus (TSC1) maps in the vicinity of the Abelson oncogene at 9q34 and a second locus (TSC2) maps in the region of the anonymous DNA marker Lam L7 and the dopamine D2 receptor gene at 11q23.

Chromosome Mapping↗
PubMed1990

Renal angiomyolipomas: could the histology serve as a marker for tuberous sclerosis?

The histological features of 43 renal angiomyolipomas were studied in an attempt to evaluate whether the isolated forms and those that present as part of the tuberous sclerosis complex can be distinguished. In two patients the mass was classified as an angioleiomyoma, because no adipose tissue was present. All renal angiomyolipomas showed the same basic histological picture. The combined forms, however, showed additional features such as extension into pre-existent renal parenchyma, scattered foci of hamartomatous lesions, calcified spicules and tubular inclusions. The findings suggest that these features, in an otherwise classical angiomyolipoma, should alert the pathologist to the possibility of tuberous sclerosis.

Biomarkers↗
PubMed1990

Cerebrovascular disease in Ehlers-Danlos syndrome type IV.

We describe two patients with cerebrovascular complications of Ehlers-Danlos syndrome type IV. A 16-year-old girl with spontaneous internal carotid artery dissection and a 46-year-old woman with aneurysmal subarachnoid hemorrhage and multiple aortic dissections were both deficient in collagen type III, analyzed in cultured skin fibroblasts. To our knowledge, spontaneous carotid artery dissection associated with collagen type III deficiency has not been reported previously. Early clinical recognition of this syndrome is of great importance in view of the hazards of angiography and surgery. Collagen type III deficiency plays a role in the pathogenesis of intracranial saccular aneurysms and may also be involved in the pathogenesis of carotid cavernous fistulas and dissections of the cervical arteries.

Adolescent↗
PubMed1990

Percutaneous transcatheter embolization of symptomatic renal angiomyolipomas: a report of four cases.

Successful percutaneous transcatheter embolization of renal angiomyolipoma is reported in four female patients. The angiomyolipomas measured more than 4 cm in diameter. Three patients had severe haemorrhage and one patient had a growing angiomyolipoma in a solitary kidney. This patient had percutaneous transcatheter embolization to prevent further deterioration of kidney function. Three patients had multiple renal angiomyolipomas as part of tuberous sclerosis. Two of them had selective transcatheter embolization of more than one angiomyolipoma. After embolization, one patient had partial loss of kidney function and one patient developed an abscess that could successfully be drained percutaneously under ultrasound guidance. The following conclusions can be drawn. All patients with tuberous sclerosis should be screened for renal angiomyolipomas. All symptomatic renal angiomyolipomas and all angiomyolipomas that measure more than 4 cm in diameter require treatment. Embolization should be considered as a primary therapeutic modality for multiple angiomyolipomas.

Adult↗
PubMed1989

[Cholesteatoma of the ear].

Cholesteatoma of the ear is characterized by the presence of a keratinizing squamous epithelium in the cavities of the middle ear. The epithelium invades the ear either by direct migration or by retraction of the eardrum. Owing to is potentials for migration, desquamation, bone erosion and infection, it is for most of the complications of chronic otitis and fully justifies the adjective "dangerous" applied to chronic cholesteatomatous otitis. The clinical diagnosis rests on microscope otoscopy. Audiometry informs on the degree of hearing loss and on the state of the contralateral ear. Standard radiography and computerized tomography of the petrous bone evaluate the extent of the lesion. Treatment is purely surgical: it consists of excision of the entire epithelium that has entered the middle ear and, secondarily, conservation or improvement of hearing. Whatever the surgical technique used, the frequency of recurrences calls for long-term follow-up.

Cholesteatoma↗
PubMed1989

Tuberous sclerosis and the relation with renal angiomyolipoma. A genetic study on the clinical aspects.

Renal angiomyolipomas were present in 23 out of a series of 38 patients with proven tuberous sclerosis (60.5%). Multiplicity and bilateral localization of combined renal angiomyolipomas were important differences between this category and the isolated, usually solitary, angiomyolipomas. One of the parents of a patient with tuberous sclerosis had small renal angiomyolipomas without signs of tuberous sclerosis. This indicates that renal angiomyolipomas might be a forme fruste of tuberous sclerosis. Two patients with suspected isolated renal angiomyolipomas proved to have tuberous sclerosis. From this study we can conclude that multiple angiomyolipomas, or a combination of a single renal hamartoma with one of the signs suggestive of tuberous sclerosis, warrant a thorough examination to exclude tuberous sclerosis.

Adolescent↗