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Biomedical subjects

J M Vallat

Publications and source records attributed to J M Vallat.

At least 37 records · Page 2Linked to original sources
PubMed2001

The clinical and laboratory features of chronic sensory ataxic neuropathy with anti-disialosyl IgM antibodies.

The clinical and laboratory phenotype of a paraproteinaemic neuropathy syndrome termed chronic sensory ataxic neuropathy with anti-disialosyl IgM antibodies is described in a series of 18 cases. Previous single case reports have outlined some features of this syndrome. All 18 cases were defined by the presence of serum IgM antibodies which react principally with NeuAc (alpha2-8)NeuAc(alpha2-3)Gal-configured disialosyl epitopes common to many gangliosides including GDlb, GD3, GTlb and GQlb. In 17 out of 18 cases, the serum contained benign IgM paraproteins, and in four of these cases at least two IgM paraproteins were present. The IgM antibodies were also cold agglutinins in 50% of cases. The clinical picture comprised a chronic neuropathy with marked sensory ataxia and areflexia, and with relatively preserved motor function in the limbs. In addition, 16 out of 18 cases had motor weakness affecting oculomotor and bulbar muscles as fixed or as relapsing-remitting features. When present in their entirety, these clinical features have been described previously under the acronym CANOMAD: chronic ataxic neuropathy, ophthalmoplegia, IgM paraprotein, cold agglutinins and disialosyl antibodies. This distribution of clinical features is reminiscent of Miller Fisher syndrome, in which acute-phase anti-disialylated ganglioside IgG antibodies are found. Clinical electrophysiology and nerve biopsy show both demyelinating and axonal features. A partial response to intravenous immunoglobulin and other treatments is reported in some cases.

Adult↗
PubMed2000

Absence of P0 leads to the dysregulation of myelin gene expression and myelin morphogenesis.

P0, the major peripheral nervous system (PNS) myelin protein, is a member of the immunoglobulin supergene family of membrane proteins and can mediate homotypic adhesion. P0 is an essential structural component of PNS myelin; mice in which P0 expression has been eliminated by homologous recombination (P0-/-) develop a severe dysmyelinating neuropathy with predominantly uncompacted myelin. Although P0 is thought to play a role in myelin compaction by promoting adhesion between adjacent extracellular myelin wraps, as an adhesion molecule it could also have a regulatory function. Consistent with this hypothesis, Schwann cells in adult P0-/- mice display a novel molecular phenotype: PMP22 expression is down-regulated, MAG and PLP expression are up-regulated, and MBP expression is unchanged. As in quaking viable mutant mice (qk(v)), which have uncompacted myelin morphologically similar to that found in P0-/- mice, neither the qKI-6 or qKI-7 proteins are expressed in P0-/- peripheral nerve. In addition to these changes in gene expression in the P0 knockout, PLP/DM-20 accumulates in the endoplasmic reticulum of P0-/- Schwann cells, whereas MAG accumulates in redundant loops of uncompacted myelin, not at nodes of Ranvier or Schmidt-Lantermann incisures. Taken together, these results demonstrate that P0 is involved, either directly or indirectly, in the regulation of both myelin gene expression and myelin morphogenesis.

Animals↗
PubMed2000

[Histology and elementary pathology of the peripheral nerve].

The lesions which give rise to peripheral neuropathy are induced by a variety of mechanisms. Their etiology can often be established from the results of electrophysiological examination and (or) study of nerve biopsy; knowledge of the etiology will guide the treatment strategy. In this chapter, we discuss typical lesional mechanisms including: axonal involvement (Wallerian degeneration, axonopathies) and demyelinating lesions (whether segmental, indicative of an acquired inflammatory process, or of a more extensive nature, indicative of a genetic origin). The indication for nerve biopsy, which enables identification of the lesions, should be considered on a case by case basis.

Axons↗
PubMed2000

Homogeneous phenotype of the gypsy limb-girdle MD with the gamma-sarcoglycan C283Y mutation.

OBJECTIVE: To characterize the clinical phenotype of LGMD2C in gypsies. BACKGROUND: Limb-girdle muscular dystrophy (LGMD) in gypsies of Western Europe is caused by a homozygous C283Y mutation on the same haplotype, suggesting a founder effect. METHODS: We performed clinical, laboratory, and muscle imaging studies of 40 patients. RESULTS: Mean age at onset was 5.3 years. One half of the patients had loss of ambulation by the age of 12; 13% still could walk after age 16. Calf hypertrophy, scapular winging, macroglossia, and lumbar hyperlordosis were common. Girdle, trunk, and proximal limb flexor muscles had earlier and more severe involvement. Cardiomyopathy was not observed. Five patients in the third decade of life required mechanical ventilation. Scoliosis was common in the nonambulatory stage. CONCLUSIONS: LGMD2C in gypsy patients with C283Y mutation presents a rather homogeneous phenotype, characterized by an initial Duchenne-like progressive course followed by a more prolonged survival rate possibly due to the absence of early respiratory impairment and cardiac failure.

Adolescent↗
PubMed2000

Inducible nitric oxide synthase and nitrotyrosine in the central nervous system of mice chronically infected with Trypanosoma brucei brucei.

Human African trypanosomiasis, or sleeping sickness, evolves toward a meningoencephalitic stage, with a breakage in the blood-brain barrier, perivascular infiltrates, and astrocytosis. The involvement of nitric oxide (NO) has been evoked in the pathogenic development of the illness, since NO was found to be increased in the brain of animals infected with Trypanosoma brucei (T. b.) brucei. An excessive NO production can lead to alterations of neuronal signaling and to cell damage through the cytotoxicity of NO and its derivatives, especially peroxynitrites. In African trypanosomiasis, the sites of NO production and its role in the pathogenicity of lesions in the central nervous system (CNS) are unknown. In a chronic model of African trypanosomiasis (mice infected with T. b. brucei surviving with episodic suramin administration), NADPH-diaphorase staining of brain slides revealed that NO synthase (NOS) activity is located not only in endothelial cells, choroid plexus ependymal cells, and neurons as in control mice but also in mononuclear inflammatory cells located in perivascular and parenchyma infiltrates. An immunohistochemical study showed that the mononuclear inflammatory cells expressed an inducible NOS activity. Furthermore, the presence of nitrotyrosine in inflammatory lesions demonstrated an increased NO production and the intermediate formation of peroxynitrites. The detection of extensive formation of nitrotyrosine in the CNS parenchyma was observed in mice having shown neurological disorders, suggesting the role of peroxynitrites in the appearance of neurological troubles. In conclusion, this study confirmed the increased NO synthesis in the CNS of mice infected with T. b. brucei and suggests a deleterious role for NO, through the formation of peroxynitrites, in the pathogenesis of African CNS trypanosomiasis.

Animals↗
PubMed2000

Prevalence and clinical significance of anti-phospholipid antibodies in multiple sclerosis: a study of 89 patients.

The prevalence of serum anti-phospholipid antibodies (aPL) was evaluated in multiple sclerosis (MS) patients to search for a possible association with a distinct form of the disease. Anti-cardiolipin antibodies (Ab) (aCL) and anti-beta 2 glycoprotein I Ab (abeta2GPI) were measured together with antinuclear Ab (ANA), anti-double-stranded DNA Ab (anti-ds DNA) and anti-myelin Ab in 89 patients. Twenty-nine (32.6%) patients had serum aPL, 19xaCL (15 of the IgG and four of the IgM isotype), 14 abeta2GPI (two IgG and 12 IgM) (four of these patients had both Ab). Prevalence of aCL correlated with that of ANA, which were positive in 52 patients (P=0. 005) and with anti-myelin Ab detected in two patients (P=0.046) but not with that of anti-ds DNA (mostly of the IgM class) detected in 28% of case by ELISA. No correlation could be found between aPL and age, sex, duration of the disease from diagnosis, category of MS, clinical course, clinical symptoms, serum IgM levels nor atypical lesions by magnetic resonance imaging. Hence, aCL and abeta2GPI are neither rare in MS nor associated with a specific clinical form of the disease and they cannot be a diagnosis exclusion criteria.

Adult↗
PubMed2000

Estimation of the amyotrophic lateral sclerosis incidence by capture-recapture method in the Limousin region of France.

Amyotrophic lateral sclerosis (ALS) is a rapidly fatal degenerative neurological disease categorized among motor neuron diseases. In the literature, the incidence of ALS varies between 0.7 and 2.4 per 100, 000 inhabitants. A study using the capture-recapture method (multiple records system analysis) was undertaken in Limousin (France) ascertaining all patients having onset of definite or probable ALS during the period 1994-1995. Three information sources able to identify these new ALS cases were selected: the first source was a computerized database of the Neurology Department of the University Hospital of Limoges; the second source consisted of the neurologists of the Limousin region and neighboring provinces (county-sized regions); the third source grouped the hospitals of the Limousin region and neighboring provinces (county-sized regions). During this period, 46 new cases of ALS were seen, corresponding to an observed mean annual incidence of 3.2 (+/-0.6) per 100,000 inhabitants. After standardization for age, the annual incidence was 2.5 per 100,000 inhabitants. The number of new cases estimated by the capture-recapture method was 70, corresponding to an estimated mean annual incidence of 4.9 (+/-1.0) for 100,000 inhabitants. Hence, statistical modeling utilizing partially overlapping information sources permitted a more exhaustive compendium of the new cases of ALS and may be a truer reflection of actual disease incidence than has been previously reported.

Amyotrophic Lateral Sclerosis↗
PubMed2000

Charcot-Marie-Tooth 2-like presentation of an Algerian family with giant axonal neuropathy.

Giant axonal neuropathy is a rare autosomal recessive childhood disorder characterized by a peripheral neuropathy and features of central nervous system involvement. We describe four patients belonging to a consanguineous Algerian family with late onset (6-10 years) slowly progressive autosomal recessive giant axonal neuropathy. The propositus presented with a Charcot-Marie-Tooth 2-like phenotype with foot deformity, distal amyotrophy of lower limbs, areflexia and distal lower limb hypoesthesia. Central nervous system involvement occurred 10 years later with mild cerebellar dysarthria and nystagmus in the propositus and 16 years after onset, a spastic paraplegia in the oldest patient. The two youngest patients (13 and 8 years old) do not present any signs of central nervous involvement. Magnetic resonance imaging showed cerebellar atrophy in the two older. Nerve biopsy showed moderate axonal loss with several giant axons filled with neurofilaments. Genetic study established a linkage to chromosome 16q locus. This clinical presentation differs from the classical form of giant axonal neuropathy.

Adolescent↗
PubMed2000

Nutritional assessment and survival in ALS patients.

Malnutrition, present in 16-50% of ALS patients, is an independent prognostic factor for worsened survival. It is caused primarily by swallowing dysfunction, resulting from involvement of the lower sets of cranial nerves, but hypermetabolism is also implicated. Malnutrition itself can produce neuromuscular weakness and adversely affect patients' quality of life, thereby creating a vicious circle. The nutritional status of ALS patients can be assessed with dietary review and measurements of weight (W) and height (H). A body mass index (BMI = W/H2) below 18.5-20 kg/m2 indicates a state of malnutrition. Dietary counselling is important, but rapidly becomes insufficient, particularly in bulbar-onset ALS, where enteral nutritional support is then necessary. Percutaneous endoscopic gastrostomy tube placement is well tolerated, and provides more efficient enteral nutrition than nasogastric tube feeding. Enteral nutrition support can improve the respiratory status of ALS patients. The effect on survival remains to be confirmed.

Aged↗
PubMed2000

[Case study of 199 patients with multiple sclerosis: the use of EDMUS program].

European Database Multiple Sclerosis (EDMUS) is a standardized tool which allows the collection of clinical, biological, radiological and therapeutic data on multiple sclerosis (MS). A descriptive analysis of 199 patients was done using EDMUS (version 2.2). Most data agreed with previous published results, except a low 0.4 sex ratio. At the beginning of MS, 42 p. 100 of MS patients developed pyramidal and sensory involvements and 14 p. 100 retrobulbar optic neuritis. Optic neuritis was the most frequent initial symptom of relapsing-remitting MS (25.9 p. 100) but not in the chronic progressive form (5.5 p, 100; p < 0.01). Surprisingly, relapsing-remitting form occurred more frequently whereas the secondary progressive form was diagnosed less. The concordances between the three disability scales, EGS (EDMUS Grading Scale), EDSS (Expanded Disability Status Score) and AI (Hauser Ambulation Index) were correct. In clinical practice, EDMUS is user-friendly and rapid. The lack of radiological data and the necessary quantification of only one disability scale, EGS may be too restrictive. The analysis of most of clinical data is possible by using integrated selection within the software, but sometimes needs more complex procedures.

Databases as Topic↗
PubMed2000

[Interest of a computerized ALS database in the diagnosis and follow-up of patients with ALS].

The aim of the study is to present a computerized database of the Neurology department of Limoges University Hospital and the main results obtained from data of 340 patients suffering from amyotrophic lateral sclerosis (ALS), diagnosed between 1984 and 1997. It is a user friendly and can be accessed by all neurologists at any level of computer knowledge. This database is modular (6 modules) and flexible according to need. The software used, Access 7, is an open relation database, which allows export of data to statistical or other compatible software. One of the reasons, which led to the elaboration of this database was to develop a means of collecting data in an analyzable manner for therapeutic trials. During these trials, a great number of data can be collected during each clinic visit for the evaluation of the degree of impairment, disability, and handicap. We present part of the data from the patients followed, some of whom were treated with riluzole, the current reference molecule for ALS.

Aged↗
PubMed2000

Myelin widenings and MGUS-IgA: an immunoelectron microscopic study.

A few studies have reported a variety of nonspecific histological lesions in patients with IgA monoclonal gammopathies and polyneuropathy. In our case, using electron microscopy, we observed widenings of the myelin lamellae identical to those commonly described in IgM neuropathies with anti-myelin-associated glycoprotein activity. Using immunoelectron microscopy, we demonstrated a direct involvement of IgA in myelin lesions. The search for a direct link between monoclonal dysglobulinemia, regardless of type, and polyneuropathy is important and may influence treatment.

Aged↗