Biomedical subjects
Publications and source records attributed to B M Gekht.
The article covers clinical and ophthalmologic characteristics of oculomotor disturbances in myastenic patients with endocrine ophtalmopathy, and differential diagnostic signs and peculiarities of endocrine ophtalmopathy in patients with a combination of the two diseases.
Diagnostic significance of quantitative measurement of muscle acetylcholine receptor (AChR) antibodies by ELISA in patients with myasthenia was shown. Blood serum analysis of 111 patients (30 in dynamics for various treatment types) was carried out. The most essential elevation of antibodies quantity was observed in patients with generalized myasthenia type. After thymectomy it was significantly reduced. Quantitative antibodies measurement by interaction with AChR domen in ELISA is supposed to be used as additional diagnostic method of autoimmune myasthenia.
Photopheresis with blood lymphocytes UV radiation exposure was for the first time used in the treatment of patients with myasthenia. Twenty-three patients with generalized form of the disease, aged 23-66 years, were treated. Twenty patients (87%) exhibited clinical improvement after a treatment course (4 sessions). One photopheresis session was shown to be more or less beneficial in 16 out of 23 patients (70%). The treatment resulted in strengthening of all the muscles studied, especially of mimic, platysma, biceps, deltoid, illiopsoas and gastrocnemius. Photopheresis was effective not only in a mild and moderate but in severe form of myasthenia as well. Compared to plasmapheresis, photopheresis exerts a more prolonged effect. Clinical improvement correlated with positive changes in immune status of the patients.
Mutations in the epsilon-acetylcholine receptor (AChR epsilon) subunit gene cause congenital myasthenic syndromes (CMS) with postsynaptic neural transmission defects. We present 3 male and 2 female patients from three unrelated Croatian, Hungarian, and Russian families with autosomal recessive CMS. All patients manifested with variable degrees of ophthalmoparesis and generalized, fatiguable muscle weakness since birth or early infancy. Electrophysiological studies showed a decremental response in all patients indicating a neuromuscular transmission defect. Pyridostigmine treatment improved the proximal muscle weakness whereas the ophthalmoparesis remained unchanged in all patients. Analysis of the AChR epsilon subunit gene showed homozygosity for a novel splice site mutation of intron 7 epsilon(IVS7-2A/G) in the two Croatian siblings. epsilon-mRNA analysis by RT-PCR and direct sequencing revealed that exon 7 was spliced directly to exon 9 with skipping of exon 8. The Hungarian and Russian patients were heteroallelic carriers of the same mutation epsilon(IVS7-2A/G) and of a frameshifting mutation epsilon 70insG and epsilon 1293insG, respectively. We hypothesize that altered splice products may not be expressed as functional receptors at the cell surface. A haplotype analysis with polymorphic markers revealed a high degree of similarity for the epsilon(IVS7-2A/G) carrying allele in all families and may therefore indicate a common origin of the mutation.
Acethylcholine receptor (AChR) antibodies in patients with myasthenia were studied for the first time in Russia with radioimmuno-assay application. Seronegative result (antibody titer lower than 0.2 nmol/l) was obtained for 33% of the patients and seropositive one (antibody titer higher than 0.2 nmol/l)--for 67%. AChR antibodies level varied from 1.9 to 115.0 nmol/l. The AChR antibodies were found more frequently and in higher titers in women than in men. Correlation analysis revealed strong correlation between AChR antibodies level and severity of myasthenia.
HLA-phenotype was determined in 59 juvenile patients of Russian nationality and in their 50 relatives by means of lymphocytotoxic test. There was a positive association with HLA-A1, B8 and DR3 and the negative one--with HLA-A2, A9, B5, B7, and DR7. The frequencies of HLA-A1, B8, DR3 were higher in boys than in girls with myasthenia. There were no significant changes of HLA frequencies in ocular form of the disease in comparison with the healthy group. The frequencies of HLA-B8 and DR3 were significantly higher in relatives of the patients with juvenile myasthenia than in control population.
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The distribution of ABO blood groups and rhesus factor was studied in patients with myasthenia as compared with the control. There was a statistically significant association of the diseases with the rhesus-negative phenotype and that of generalized myasthenia concurrent with thymoma with the B (III) blood group. The examination revealed no other determinants of the significant association with the disease. The values of a disease risk were obtained for persons having myasthenia-associated signs. It is concluded that the Rh-negative phenotype shows a 1.3-fold increase in the risk of the disease as compared with those having Rh-positive persons.
Magnetic stimulation of the cerebral cortex and roots CVI--CVII and LII--LIV was performed in 19 healthy subjects, 45 multiple sclerosis (MS), 21 lateral amyotrophic sclerosis and 24 demyelinating polyneuropathy patients. M-response of m. abductor digiti min (AdV) and m. tibialis ant. (TA) was registered. The difference of M-response latent time induced by the stimulation, CVI--CVII and LII--LIV determined the time of the impulse central conduction (ICC) to the corresponding roots. In healthy subjects ICC--C amounts to 8.28 +/- 1 ms (maximum 10.3 ms), ICC--S is equal to 14.6 +/- 1.46 ms (maximum 16.8 ms). In patients with the above affections increased ICC was a frequent finding which also occurred in subclinical pyramidal lesions.
The work deals with the clinical analysis of the richest experience in the surgical treatment of patients with generalized myasthenia in the country. The efficacy of various methods for the diagnosis of affection of the thymus is studied comparatively. It is shown that for more effective diagnosis of neoplastic lesions of the thymus wider use of computerized and magneto-resonance tomography is expedient and that they must replace the insufficiently informative and invasive examination methods used today (pneumonodiastinography, phlebography, scintigraphy, etc.) which still form the basis for the system of diagnostic research in patients with myasthenia. The authors determined the indications and contraindications for, the optimum terms for undertaking the surgical intervention and its volume in neoplastic and nonneoplastic diseases of the thymus in adults and children. Comparative evaluation of various means of preoperative management was conducted. It is shown that to improve the patient's condition and stabilize the myasthenic status on the possibly minimal doses of anticholesteremic agents glucocorticoid hormones should be included in the complex of preoperative management. The indications for hormonotherapy were determined. The efficacy of plasmapheresis, radiotherapy, and glomectomy with denervation of the sinocarotid zone was evaluated and their place in the complex treatment of patients was determined. From study of the late-term results of treatment of a large group of patients (children, adults with a thymus) the main causes of unsuccessful surgical treatment of generalized myasthenia were identified and the concrete means of improving the results of treatment were planned. Two types of changes in the clinico-immuno-morphological values were revealed in patients with generalized myasthenia, differing evidently in pathogenesis. New clinico-immuno-morphological correlations and prognostic factors were discovered, and a method for prognosticating the effect of thymectomy was suggested. It is shown that splenectomy has a favorable effect in the most severe category of patients in unsuccessful operative and nonoperative treatment. The tactics of management of patients accepted in the clinic led to a uncomplicated course of the postoperative period in the majority of patients in the last years.
The authors describe the results of clinical and electromyography examinations of 20 patients with grave generalized myasthenia, carried out within the short-term (up to 2 weeks) and long-term period (up to 1 year) after splenectomy. In these patients, the preceding therapy (thymectomy, gamma-therapy of the thymic area, the treatment with prednisolone, azathioprine, plasmapheresis, etc) had not produced any beneficial effect. The efficacy of splenectomy was assessed according to the Keens classification (A-E). In the short-term period after splenectomy the C effect was recorded in 13 out of the 20 patients. Out of 9 patients examined in the long-term period, the B effect was revealed in 3 patients, the C effect persisted in 3 patients, and 3 patients manifested the return to the initial status, namely to the E effect. Therefore in the group of patients with grave generalized myasthenia, the efficacy of splenectomy amounted to 65%. In view of this fact the inclusion of the given treatment method into the multimodality treatment of myasthenic patients is regarded advisable.
The authors discuss the results of splenectomy carried out on 20 patients with generalized myasthenia in whom previous complex treatment including thymectomy, corticosteroid and azathioprine therapy, repeated courses of plasmapheresis during medication with anticholinesterase agents, did not cause any essential improvement. Different values of homeostasis and immunological status were studied before and in different periods after splenectomy. The condition improved in 65% of patients, which was confirmed by the results of myography; the doses of corticosteroids and anticholinesterase agents were reduced. Bearing in mind the severe condition of patients selected for splenectomy, it is recommended to treat them only in medical centers possessing sufficient experience in treatment of myasthenia. The indications and contraindications for splenectomy in complex treatment of myasthenia must be specified further.
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Based on the investigation of 33 distal and 163 proximal muscles in myasthenic patients in which posttetanic and postactivation facilitation was studied and adequate proserin doses injected, the authors have shown the "block" phenomenon to be most pronounced in proximal muscles. The authors offered to use the reversibility coefficient as reflecting the possible restoration of neuromuscular conduction. Evaluation of the "block" and a reversibility coefficient plays major role in assessment of contribution of presynaptic structures to operation of mechanisms dicturbing the neuromuscular conductance in myasthenia.