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Biomedical subjects

F Chapon

Publications and source records attributed to F Chapon.

At least 19 recordsLinked to original sources

Lethal paradoxical cerebral vein thrombosis due to suspicious anticoagulant rodenticide intoxication with chlorophacinone.

Superwarfarin exposure is a growing health problem, described in many countries. The authors report a case of suspicious chlorophacinone poisoning with a problematic diagnosis. They review the literature and discuss particularities of anticoagulant rodenticide intoxication, as well as the apparent contradiction between anticoagulant intoxication and lethal thrombosis.

Adult↗

Screening of TP53 mutations by DHPLC and sequencing in brain tumours from patients with an occupational exposure to pesticides or organic solvents.

The aetiology of brain tumours remains unclear. Occupational exposures to pesticides and organic solvents are suspected risk factors. The case-control study CEREPHY (221 cases, 442 controls) carried in the Departement de la Gironde in France revealed a significantly increased risk of brain tumours for subjects most exposed to pesticides. In some cancers, TP53 mutations could reflect exposure to specific carcinogens. These mutations are present in approximately 30% of astrocytic brain tumours. In a pilot study, we explored the hypothesis that pesticide or solvent exposure could raise the frequency of TP53 mutations in brain tumour cells. We investigated TP53 mutations in exons 2-11 by denaturing high performance liquid chromatography (DHPLC) and sequencing, and p53 accumulation by immunohistochemistry in brain tumour of the 30 patients from CEREPHY study with a history of occupational exposure to pesticides (n = 21) and/or organic solvents (n = 14) for whom tumoral tissue was available. Included cases concerned 27% of CEREPHY cases exposed to pesticides and, based on the cumulative index of occupational exposure, they were more exposed to pesticides. There were 12 gliomas, 6 meningiomas, 7 neurinomas, 2 central nervous system lymphomas and 3 tumours of other histological types. We detected TP53 mutations in three tumours, which is similar to the expected number (3.3) calculated from 46 published studies referenced in the IARC TP53 mutations database, taking into account histological types. Considering TP53 mutations previously detected in the laboratory by DHPLC and the frequency of TP53 polymorphisms detected in this sample (similar to published data), the TP53 mutations rate is probably not underestimated. These preliminary results, even if it was on a limited number of tumours, are not in favour of the role of pesticide or organic solvent exposure in the occurrence of TP53 mutations in brain tumours.

Brain Neoplasms↗

[Metabolic imaging for supratentorial oligodendrogliomas].

Metabolic imaging with positron emission tomography (PET) provides, in neuro-oncology, information complementary to that provided by anatomic imaging obtained with CT-scanner or MRI. Only a few publications have yet reported its use in oligodendroglial tumors. These findings and partial results obtained in ongoing work, suggest some preliminary conclusions: 11C-MET (L-methyl-methionine) is a more appropriate tracer than 18F-FDG (fluoro-deoxy-glucose), in terms of both specificity and sensitivity, for the assessment of patients with this category of tumor. PET/MET allows differentiation between grade II and grade III oligodendrogliomas; better targeting for stereotactic biopsy; more accurate assessment of the post-operative residual tumor; identification of progression from low-grade to anaplastic grade during the disease course; differentiation between recurrence and a post-radiation processes. PET/MET allows, to some extent, prediction of response to radiotherapy; and, probably, to chemotherapy.

Adult↗

[Stent-graft treatment of a ruptured aortic graft: a case report].

The authors report the clinical and imaging features of a patient with rupture of an aortoiliac graft successfully treated by endovascular approach. The endovascular treatment is easy to perform and effective. The main pitfall of this technique is the limited availability of stent-grafts.

Anastomosis, Surgical↗

[A case of nasal septum schwannoma: endoscopic resection].

OBJECTIVES: To define clinical and radiological characteristics of nasal septal schwannoma, and to propose endoscopic surgery. PATIENT AND METHODS: We report a case of an isolated schwannoma of the anterior part of the nasal septum, without involvement of any local structure. The only preoperative symptom was nasal obstruction. Imaging study included a CT scan and an MRI study. RESULTS: Schwannoma is a sheath tumor originating from Schwann cells of peripheral nerves. It rarely occurs in nasal and paranasal sinuses and its development on the nasal septum is extremely rare. Complete removal of the tumor was performed by endoscopic sinus surgery technique. Limits of the excision were free of tumor and the histological type was Antoni type A Schwannoma. After a year of follow up, the patient is free of recurrence. CONCLUSION: The Schwannoma of the nasal septum is a rare tumour whose clinical and radiological diagnosis by CT scan and IRM is relatively easy. Its treatment is surgical and the endoscopic surgery can be proposed in the forms slightly extensive.

Endoscopy↗

Hemorrhagic stroke associated with the Iowa amyloid precursor protein mutation.

The authors searched for mutations in the beta-amyloid precursor protein in a Spanish family with a hereditary syndrome of hemorrhagic stroke, dementia, leukoencephalopathy, and occipital calcifications. DNA from two affected members demonstrated the Iowa amyloid precursor protein mutation previously identified as a cause of severe amyloid angiopathy without hemorrhagic stroke. These data point to other genetic or environmental factors that may determine the occurrence of symptomatic hemorrhage in amyloid angiopathy.

Age of Onset↗

Hereditary infantile hemiparesis, retinal arteriolar tortuosity, and leukoencephalopathy.

BACKGROUND: The main hereditary vascular conditions involving both retinal and cerebral vessels include cerebroretinal vasculopathy, HERNS (hereditary endotheliopathy with retinopathy, nephropathy, and stroke), and hereditary vascular retinopathy; all are linked to the same locus on chromosome 3p21. Hereditary retinal arteriolar tortuosity is a distinct, autosomal dominant condition characterized by retinal arteriolar tortuosity and recurrent retinal hemorrhages. This condition is known to affect only retinal vessels. METHODS: Clinical and brain MRI investigations of eight members of a three-generation family and extensive biological and systemic vascular investigations within one affected family member were conducted. RESULTS: Six of eight family members were clinically symptomatic; disorders included infantile hemiparesis (2), migraine with aura (3), and retinal hemorrhage (1). Five individuals had retinal arteriolar tortuosities. A diffuse leukoencephalopathy in association with dilated perivascular spaces was observed in six individuals. Two family members had silent, deep cerebral infarcts as demonstrated on MRI. Genetic linkage analysis strongly suggests that this disorder is not linked to the 3p21 hereditary vascular retinopathy/cerebroretinal vasculopathy/HERNS locus. CONCLUSIONS: The authors describe a novel hereditary autosomal dominant condition affecting both retinal and cerebral vessels and characterized by infantile hemiparesis, migraine with aura, retinal hemorrhage, retinal arterial tortuosity, and leukoencephalopathy with dilatation of perivascular spaces and microbleeds on brain MRI. Investigation of additional families should help to map the gene and to better categorize the spectrum of hereditary cerebroretinal small vessel diseases.

Adolescent↗

CDKN2A, CDKN2B and p14ARF are frequently and differentially methylated in ependymal tumours.

Ependymal tumours are histologically and clinically varied lesions. Numerical abnormalities of chromosome 9 are frequently associated with these tumours. Nevertheless, the three important tumour suppressor genes located in this chromosome, CDKN2A, CDKN2B and p14 ARF, have not been reported to be commonly altered in them. We studied promoter methylation of these genes, an important mechanism associated with gene silencing in a series of 152 ependymal tumours of WHO grades I to III. Methylation status of the CDKN2A, CDKN2B and p14 ARF promoters was assessed by methylation-specific polymerase chain reaction and the genetic results were correlated to clinicopathological features. We observed promoter methylation for CDKN2A in 21% (26/123) of tumours, for CDKN2B in 32% (23/71) and p14 ARF in 21% (23/108). For all three genes, posterior fossa ependymomas were less frequently methylated in paediatric patients than in adults. For CDKN2B, extracranial tumours were more frequently methylated than intracranial ones. For CDKN2B and p14 ARF, methylation was more frequent in low-grade tumours; the reverse was observed for CDKN2A. CDKN2A, CDKN2B and p14 ARF promoters were methylated in 21-32% of the tumours. Frequencies of methylation varied according to clinicopathological features. This suggests a role for these genes in ependymoma tumorigenesis.

Adolescent↗

[Sphenoid sinusitis].

Sphenoid sinusitis is uncommon, with an incidence of about 2.7%. Failure to diagnose and treat sphenoid sinus disease has been shown to lead to serious neurologic sequellae. Plain radiographs play a limited role in the management of sinusitis. CT scan can provide a positive diagnosis by the visualization of mucosal thickening, air-fluid level and complete opacification of the sinusal cavities. In addition, CT can provide more information about the anatomy and abnormalities of the sphenoid sinus. MRI is used in cases of suspected tumors or neurologic involvement. The most common presenting symptom is headache that arise characteristically, but rarely, from the vertex. Sphenoiditis has a high risk of severe neurologic involvement, cavernous sinus thrombosis being one of the most serious complications.

Cavernous Sinus Thrombosis↗

Krit1/cerebral cavernous malformation 1 mRNA is preferentially expressed in neurons and epithelial cells in embryo and adult.

Cavernous malformations are capillaro-venous lesions mostly located within the central nervous system (CCM/OMIM#116860) and occasionally within the skin and/or retina. They occur as a sporadic or hereditary condition. Three CCM loci have been mapped, and the sole gene identified so far, CCM1, has been shown to encode KRIT1, a protein of unknown function. In an attempt to get some insight on the relationship between KRIT1 mutations and CCM lesions, we investigated Krit1 mRNA expression during mouse development from E7.5 to E20.5 and in adult tissues, of both mouse and human origin. A ubiquitous Krit1 mRNA expression was detected from E7.5 up to E9.5. Then, it became progressively restricted from E10.5 to E12.5, to become detectable later essentially in the nervous system and various epithelia. Strong labelling was observed in neurons in the brain, cerebellum, spinal cord, retina and dorsal root ganglia. In epithelia, Krit1 mRNA expression was detected in differentiating epidermal, digestive, respiratory, uterine and urinary epithelia. A similar pattern of expression persisted in mouse and man adult nervous system and epithelia. Unexpectedly, in vascular tissues, expression of Krit1 was detected only in large blood vessels of the embryo.

Adult↗

Familial occipital calcifications, hemorrhagic strokes, leukoencephalopathy, dementia, and external carotid dysplasia.

OBJECTIVE: To describe a new familial association of late-onset dementia, patchy leukoencephalopathy, intracerebral hemorrhages, bilateral occipital calcifications (BOC), and external carotid artery dysplasia (ECAD). METHODS: At age 62, the proband, who was of Spanish descent, had left temporal hemorrhage in a background of progressive mental deterioration. Neuroimaging revealed fine tram-line BOC, extensive leukoencephalopathy, and bilateral ECAD. Biologic screening for celiac disease was negative. Skin biopsy with ultrastructural study revealed heretofore unreported changes in the basal lamina of capillaries, with multilayered appearance and round-shaped microcalcifications. Of 19 next-of-kin who survived beyond 60 years of age, six had brain disorders; four of the six presented at least three components of the syndrome. The proband's mother had died at age 83 with profound dementia; one sister, who was diagnosed with dementia with BOC and leukoencephalopathy at age 67, died 2 years later from intracerebral hemorrhage; a brother had an occipital hemorrhage at age 58, at which time BOC and leukoencephalopathy were discovered; and another brother died after a minor stroke at age 70 with dementia, leukoaraiosis, BOC, and ECAD. A proband's cousin also had an unexplained ischemic stroke at age 55, but without other features of the entity. In no subject was there evidence of seizures, facial angioma, or intracranial vascular malformation, and arterial hypertension was neither constant nor severe. CONCLUSION: These clinical, neuroradiologic, and histologic features suggest a new familial cerebrovascular entity with widespread microvascular calcifications and autosomal (presumably dominant) inheritance. We suggest the acronym FOCHS-LADD, for familial occipital calcifications, hemorrhagic strokes, leukoencephalopathy, arterial dysplasia, and dementia.

Aged↗

Non-invasive grading of oligodendrogliomas: correlation between in vivo metabolic pattern and histopathology.

Several studies have shown that the prognosis of oligodendrogliomas is dependent on their histological grade. In order to identify a non-invasive method for the primary diagnosis and follow-up of these tumours, we investigated the relationship between their in vivo metabolism, assessed by positron emission tomography (PET), and their histological grade assessed at the same time. Forty-seven patients with histologically confirmed oligodendrogliomas were investigated. Conventional neuroradiological assessment by computed tomography and magnetic resonance imaging (MRI) was performed in all the patients. All the histology slices were reviewed by the same pathologist after referral from various pathology laboratories. The PET investigation included a carbon-1 methionine (11C-MET) uptake study and, in the majority of cases, a fluorine-18 fluorodeoxyglucose (18F-FDG) uptake study, in order to investigate at the same time both amino acid metabolism and glycolysis. The sampled tumour region of interest (ROI) was defined from the T1-weighted 3D MR scan matched with the PET scan. Tracer concentration in each voxel of the tumour ROI was divided by the mean concentration in an ROI of the same size located in the healthy brain tissue. For each tumour and each tracer, we characterized the metabolic pattern on the basis of the mean and the maximum tumour to healthy tissue concentration ratio, and also the standard deviation and range of the ratios, which indicate the degree of metabolic heterogeneity of the tumour. The histological criteria for differentiating between high- and low-grade tumours were those of the WHO and, partially, of the Sainte-Anne-Daumas-Duport classification. Highly significant differences between high- and low-grade oligodendrogliomas (Mann-Whitney test: P<0.0001) were observed for all the assessed parameters of 11C-MET uptake. On the other hand, the pattern of 18F-FDG uptake showed only moderate differences between the two tumour groups.

Adult↗

The ectodomain of the Notch3 receptor accumulates within the cerebrovasculature of CADASIL patients.

Mutations in Notch3 cause CADASIL (cerebral autosomal dominant adult onset arteriopathy), which leads to stroke and dementia in humans. CADASIL arteriopathy is characterized by major alterations of vascular smooth muscle cells and the presence of specific granular osmiophilic deposits. Patients carry highly stereotyped mutations that lead to an odd number of cysteine residues within EGF-like repeats of the Notch3 receptor extracellular domain. Such mutations may alter the processing or the trafficking of this receptor, or may favor its oligomerization. In this study, we examined the Notch3 expression pattern in normal tissues and investigated the consequences of mutations on Notch3 expression in transfected cells and CADASIL brains. In normal tissues, Notch3 expression is restricted to vascular smooth muscle cells. Notch3 undergoes a proteolytic cleavage leading to a 210-kDa extracellular fragment and a 97-kDa intracellular fragment. In CADASIL brains, we found evidence of a dramatic and selective accumulation of the 210-kDa Notch3 cleavage product. Notch3 accumulates at the cytoplasmic membrane of vascular smooth muscle cells, in close vicinity to but not within the granular osmiophilic material. These results strongly suggest that CADASIL mutations specifically impair the clearance of the Notch3 ectodomain, but not the cytosolic domain, from the cell surface.

Aged↗

[Familial myopathy with desmin storage seen as a granulo-filamentar, electron-dense material with mutation of the alphaB-cristallin gene].

Two familial cases of a myopathy remarkable by the presence of a granulo-filamentar, electron dense material were reported in 1978. In a second step, in 1988, it was demonstrated that this material contained an abnormally-phosphorylated desmin. During the last twenty years, the occurrence of new cases in this family confirmed the autosomal dominant inheritance of the disease, and made it potentially informative for molecular genetics studies. This allowed first to map the disease on chromosome11q21-23, and afterwards to identify a mutation within a gene coding for a chaperone protein, alphaBcrystallin. An extensive clinical, pathological and genetic study of this princeps family is herein reported in detail. First, it showed the possible detection of histopathological changes in presymptomatic patients. Second, it allowed to demonstrate the simultaneous occurrence of both alphaBcrystallin and desmin in the granulo-filamentar aggregates. Third, this study provided a precise knowledge of the evolution rate of the disease. The analysis of similar observations reported in the literature clearly shows the clinical, pathological and genetic heterogeneity of this new neuro-muscular disorder.

Actin Cytoskeleton↗

Ultrastructural protein zero expression in Charcot-Marie-Tooth type 1B disease.

Charcot-Marie-Tooth type 1B (CMT 1B) disease, an inherited demyelinating peripheral neuropathy, results from different point mutations located in the P0 gene on chromosome 1 q21-23. We have quantified, at the ultrastructural level, the immunocytochemical expression of the P0 protein in two unrelated CMT 1B patients with mutations (Ser 78 to Leu and Asn 122 to Ser) located in two different exons in the extracellular domain of the protein. A twofold decrease in P0 expression was observed in compact myelin in each case, compared with age-matched controls. The severity of the phenotypes showed no direct relationship to the levels of P0 protein expression in these 2 patients.

Amino Acid Substitution↗

Desmin phosphorylation abnormalities in cytoplasmic body and desmin-related myopathies.

Cytoplasmic body myopathy (CBM) and desmin-related myopathy (DRM) are both characterized by an abnormal accumulation of desmin. To determine whether these abnormalities involve similar or different forms of desmin, we performed desmin two-dimensional electrophoresis: our results showed an increase in the two acidic isoforms in CBM muscles as compared with an increase in the number of acidic isovariants in DRM samples. A process of hyperphosphorylation involved in these acidic forms was confirmed by alkaline phosphatase application onto the muscle samples in both pathological conditions.

Cytoplasm↗

Study of some components of the cytoskeleton in muscular disorders with nonspecific cytoplasmic bodies.

To gain a better understanding of the mechanisms involved in the formation of cytoplasmic bodies (CBs), the immunohistochemical and biochemical features of muscle samples with nonspecific CBs were compared to those previously described by our group in cytoplasmic body myopathy (CBM), a congenital disease in which specific CBs are found. Accordingly, we studied nonspecific CBs found in the muscle biopsies of 15 patients with the following diseases: peripheral neuropathy (n = 5), polymyositis (n = 3), myotonic dystrophy (n = 2), sarcoidosis (n = 1), inclusion body myositis (n = 1), hereditary inclusion body myopathy (n = 1), hypothyroidism (n = 1), and muscle atrophy in a patient with multiple brain infarctions (n = 1). Nonspecific inclusions were stained at their periphery by anti-desmin but not by anti-dystrophin antibodies, except in the case of hypothyroidism in which immunostaining was observed with both antibodies. Biochemical studies showed normal amounts of desmin and phosphorylation pattern (the latter data are available for only four patients) as compared to control specimens. Our results differ from those previously reported in CBM, in which CBs were stained by both antidesmin and anti-dystrophin antibodies and in which a hyperphosphorylation of desmin was found. Hypothyroidism is, thus, the only disease in which nonspecific CBs show the same immunostaining pattern as specific CBs from CBM patients. These findings indicate that CBs may result from different mechanisms, and that one of these mechanisms may be shared by CBM and hypothyroidism.

Actins↗