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B Eymard

Publications and source records attributed to B Eymard.

121 records · Page 7Linked to original sources
PubMed1989

[Autoimmune myasthenia and Lambert-Eaton myasthenic syndrome. Physiopathologic concepts].

Physiopathological concepts concerning myasthenia gravis and Lambert-Eaton myasthenic syndrome are reported. Autoantibodies are present in both cases. In myasthenia gravis, they are directed against the acetylcholine receptor. The poorly understood physiopathological aspects of this disease are discussed: the lack of correlation between antibody titer and severity, the role of the thymus and the factors triggering the disease. In Lambert-Eaton syndrome, the autoantibodies are directed against the voltage-gated calcium channels of motor nerve terminals. These calcium channels are also present in a cell line derived from a small cell carcinoma, a tumor found in 60% of Lambert-Eaton syndrome patients.

Autoantibodies↗
PubMed1989

[Myasthenia and pregnancy: a clinical and immunologic study of 42 cases (21 neonatal myasthenia cases)].

Forty-two pregnancies in 39 myasthenic mothers were studied between 1978 and 1987. In 4 cases myasthenia gravis began during pregnancy and for 20 patients the clinical condition exacerbated in 15 cases, usually during the first 3 months, or during the postpartum. Except for 1 case, clinical exacerbation was controlled by anticholinesterase drug adjustment. Obstetrical problems were uncommon: abortion in 1 case and premature delivery in 4 cases. In 2 babies with severe fetal involvement polyhydramnios was present. Twenty-one babies had neonatal myasthenia gravis (NMG). In 17 cases, transient symptoms were present at delivery or shortly afterwards and full recovery occurred from a few days to 4 months. In 4 babies the clinical presentation was atypical: 1 showed a long evolution (15 months) and residual facial bilateral weakness, and three others presented fetal involvement (arthrogryposis). In these latter cases, presentation was severe with polyhydramnios, respiratory failure and long standing evolution in 2 cases (4 months and 1 year). Antiacetylcholine receptor antibodies (anti-AChR Ab) were found in all myasthenic babies and in 19 out of 20 asymptomatic babies. Maternal antibody titers were usually slightly higher than umbilical cord titers. There was a good correlation between maternal titer and onset or severity of disorder in baby. Among the 15 high titer mothers (greater than 60 nM), 13 had a myasthenic baby, 6 of them with serious disease. Conversely all low titer mothers (less than 10 nM) had a symptom-free baby. Therefore, anti-AChR Ab titration in the mother is predictive for NMG onset. Mother's myasthenia gravis severity and treatment were not correlated to the clinical condition of the newborns.

Acetylcholine↗
PubMed1988

Cellular aspects of myasthenia gravis.

Several cellular aspects were investigated in a large series of patients with MG. First, non-Ag-specific proliferation was tested by measuring the response to r-IL2. Thymocytes from most MG patients showed hyperactivity to r-IL2. Peripheral blood lymphocytes (PBL) from some patients also showed a high response to r-IL2. These responding patients were generally those tested before thymectomy, presenting a high anti-AChR Ab titer and a severe form of the disease. Second, Ag-specific proliferation of MG PBL was assayed using 8 synthetic peptides corresponding to selected domains of torpedo or human AChR. Only 2 peptides gave a positive response in a significant number of patients, essentially in those presenting high anti-AChR Ab titer. The first is located near the alpha-bungarotoxin binding site and the second is in a cytoplasmic domain, according to models predicting the AChR transmembrane orientation. The positive results were essentially obtained with the human peptides; the corresponding torpedo peptides were positive in very few patients. Both human and torpedo peptides which include a part of the alpha-bungarotoxin binding site were negative. Finally, although morphological abnormalities were clearly visible in thymic hyperplasia, no correlation could be established between the thymus type and the cellular proliferation either to r-IL2, or to the peptides. Overall, our data indicate that cell-dependent mechanisms participate in the pathogenesis of MG, but the level of their involvement deserves further investigation.

Humans↗
PubMed1988

Effect of myasthenic patient sera on the number and distribution of acetylcholine receptors in muscle and nerve-muscle cultures from rat. Correlations with clinical state.

We studied the functional activities (FA) of sera obtained from 83 myasthenic patients on rat muscle cultures. Using the same sets of cultures, two parameters were evaluated after exposure to sera: residual fraction (RF) of acetylcholine receptors (AChR) coupled to 125I-labelled alpha-bungarotoxin (alpha Bgt) (81 sera) and the number of rhodamine labelled clusters (56 sera). Two types of culture were assayed: muscle alone and nerve-muscle cocultures (12 cases). In all combinations (fluorescence, radiolabelling, muscle alone and nerve-muscle cocultures), we found a significant correlation between FA and antibody (Ab) titre, and no correlation between FA and clinical severity: only sera with a high or intermediate Ab titre were effective, whatever the clinical severity of disease. With active sera, AChR loss was about 50% whereas the disappearance of AChR clusters was quite complete, which suggests AChR redistribution induced by MG sera.

Animals↗
PubMed1988

Neonatal myasthenia gravis: a new clinical and immunologic appraisal on 30 cases.

Anti-acetylcholine receptor (AChR) antibody titers, toxin binding blocking antibody, functional activity of serum on rat myotube cultures, IgG subclasses, and clinical data were studied in relation to the onset of neonatal myasthenia gravis (NMG) in 30 children of myasthenic mothers. Fourteen had NMG, including 4 atypical cases. Anti-AChR antibody titer was the best indication of NMG onset. NMG in a previous baby was also predictive. Pattern of IgG subclasses, presence of toxin-binding blocking antibodies, and serum functional activity were less predictive, but cast light on the mechanism of anti-AChR antibody pathogenicity.

Animals↗
PubMed1986

[Assay of anti-acetylcholine receptor antibodies in myasthenic syndromes of newborn infants].

Eighteen neonates were investigated for antibodies directed against acetylcholine receptors. No antibody was detected in 3 cases of congenital myasthenic syndrome, whereas positive results (3.5 to 250 nM) were obtained in 7 cases of transitory neonatal myasthenia and in 7 of 8 asymptomatic infants born to myasthenic mothers. The neonatal antibodies are fully cleared within 1 to 6 months (half-life: 9 days to 2 and a half months). The prognostic value of the maternal and infantile antibody titers is limited: maternal titer at the end of pregnancy, though usually higher in the mothers of myasthenic children, do not predict or preclude the occurrence of transitory myasthenia, and there is no clear correlation between the severity and duration of the myasthenia and the initial titer or the level of the child's antibodies. The assay which measures antibodies against acetylcholine receptors is useful in that it confirms the diagnosis of transitory myasthenia and excludes congenital myasthenic syndromes.

Amniotic Fluid↗
PubMed1986

[Marfan's disease and familial neuropathy with sausage-shaped swelling. A case of fortuitous association].

A 25-year-old patient and his sister had Marfan's syndrome and recurrent pressure neuropathy. Marfan's syndrome was inherited from their father while the neuropathy was inherited from their mother. Thus, the association of both disorders in the same patient was fortuitous. However it is suggested that the ligamentous hyperlaxity related to Marfan's syndrome may favour the occurrence of the neuropathy due to pressure.

Adult↗
PubMedDate not supplied

Late-onset rod myopathy associated with monoclonal gammopathy.

A 31-yr-old woman presented with a severe and rapidly progressive myopathy affecting proximal limbs, neck flexors and respiratory muscles. Muscle biopsy revealed numerous atrophic fibres with marked structural alterations, without inflammatory infiltrate. By electron microscopy, atrophic fibres displayed many rods. A benign monoclonal gammopathy (IgG, lambda chain) was evident in serum. A sarcolemmal deposit of IgG, lambda chain was found by immunostaining. Plasmapheresis and immunosuppressive therapies produced a decrease in paraproteinemia and a partial clinical improvement. This observation is the third to associate monoclonal gammopathy with "late-onset rod myopathy". The pathogenetic role of paraproteinemia remains unclear.

Adult↗
PubMedDate not supplied

[Exercise intolerance caused by muscular phosphorylase kinase deficiency. Contribution of in vivo metabolic studies].

A 33 year old man has been presenting since childhood an exertional muscle pain syndrome without myoglobinuria. Muscle biopsy revealed a vacuolar myopathy with glycogen excess in subsarcolemmal and intermyofibrillar spaces which was confirmed by electron microscopy. Plasma production of ammonia was abnormally high during exercise on a bicycle ergometer while the raise of lactate was normal. NMR spectroscopy showed an increased muscle glycogen content, with a slight and delayed drop of the pH during exercise. Phosphorylase b kinase activity was undetectable in muscle specimen whereas activities of others enzymes of carbohydrate metabolism were normal. Clinical presentation of our patient is compared to that of the reported cases of phosphorylase b kinase deficiency.

Adult↗