The high frequency and clinical feature of seronegative myasthenia gravis in Southern China.

Anti-acetylcholine receptor antibodies (anti-AChR-Ab) are responsible for the failure of neuromuscular junction in myasthenia gravis (MG). Some anti-AChR-Ab-seronegative MG patients have anti-muscle-specific tyrosine kinase antibodies (anti-MuSk-Ab). Here, the anti-AChR-Ab was tested in 250 MG outpatients from Southern China. While anti-MuSk-Ab was tested in 66 patients who had no anti-AChR-Ab in blood serum, but none of them was positive. The antibodies were measured by a radioimmunoprecipitation assay. The frequency of anti-AChR-Ab was 51.2 %. The percentage of anti-AChR-Ab in ocular type was lower than generalized type (44.9 vs. 66.2 %, P = 0.002). Seronegative MG was characterized by a lower percentage of thymoma than seropositive patients (P = 0.013). It seemed to be less severe in seronegative MG than seropositive MG in these 250 patients. In ocular type, seronegative MG mainly manifesting blepharoptosis but seldom diplopia or eyeball fixation related to ocular movement disability (P = 0.016). While in generalized type, seronegative MG was characterized by a lower percentage of bulbar muscle involvements than seropositive patients (P = 0.005). Logistic regression analysis revealed that bulbar weakness was affected by the existence of anti-AChR antibodies (OR = 3.524, P = 0.015). Besides, seronegative MG tended to be characterized by a lower percentage of neck extensor involvement, but this did not reach significance. The percentage of anti-AChR antibodies was much lower than other countries. Seronegative MG has characteristic clinical features that are different from features of the remaining seropositive MG. This emphasises the predictive value of anti-AChR antibodies analysis in MG patients.

[Analysis of prognostic factors and efficacy of plasmapheresis in the treatment of myasthenia crisis].

OBJECTIVE: To examine the prognostic factors and efficacy of myasthenia gravis (MG) in crisis on plasmapheresis and detect the reasons for ineffective plasmapheresis. METHODS: The investigators analyzed a total of 69 MG patients in crisis on plasmapheresis by case control study. Gender, age at onset of myasthenic symptoms, duration between the onset of crisis and plasmapheresis, pre-therapeutic use of glucocorticoids, pulmonary infections, other complications, nutritional status, history of thymectomy in 48 hours before crisis, thymic pathology, combined intravenous immunoglobulin (IVIG) and total sessions of plasmapheresis were measured retrospectively. RESULTS: Univariate analysis showed that pulmonary infections (P = 0.000, OR = 29.250), history of thymectomy in 48 hours before crisis (P = 0.046, OR = 0.267), combined intravenous immunoglobulin (P = 0.003, OR = 0.136) and total sessions of plasmapheresis (P = 0.022, OR = 0.498) were all influencing factors of plasmapheresis. However the analysis of multivariate logistic regression revealed that pulmonary infections (P = 0.000, OR = 23.600) was an independent risk factor and combined intravenous immunoglobulin (P = 0.047, OR = 0.192) was an independent protection factor of plasmapheresis. CONCLUSION: Plasmapheresis is ineffective in MG crisis with pulmonary infections. Control of pulmonary infections and combined intravenous immunoglobulin can improve the response to plasmapheresis in patients with MG crisis.

[Expression of regulatory T cells in thymus of myasthenia gravis patients].

OBJECTIVE: To investigate the in situ expression of regulatory T cells (Tregs) in thymus and its significance for myasthenia gravis (MG). METHODS: Thirty nine MG patients who had not accepted immunosuppressive therapy before thymectomy were recruited as study group and 19 patients undergoing cardiosurgery as control. There was no significant statistical difference in age and gender between the two groups (P > 0.05). The location and proportion of Tregs in thymus were analyzed using indirect immunofluorescence double labeling immunohistochemistry and image analysis software. RESULTS: (1) Tregs were all located in medulla zone of thymus in control and MG groups. (2) Cells of germinal center had a high expression of CD25 and a low expression of CD4. It indicates that a majority of germinal center cells were B cells. (3) There were fewer Tregs around germinal center. (4) There was no statistical significant difference in absolute number of Tregs between the two groups (P > 0.05). But the proportion of Tregs was higher in control group (P < 0.05). CONCLUSION: The proportion of thymus Tregs decreases in MG so as to weaken the function of immuno-regulation and suppression. This is probably a precipitating factor of MG.

[Mediation of cellular immune response by TP5 in pathogenesis of myasthenia gravis].

OBJECTIVE: To evaluate the effects of TP5 upon the production of IFN-gamma and different T cell subsets by human peripheral blood mononuclear cells (PBMCs) from patients with myasthenia gravis (MG) and to provide experimental rationales for TP5 in clinical therapy of MG. METHODS: PBMCs were isolated from peripheral blood of MG individuals and cultured with anti-CD3. The level of IFN-gamma in culture supernatants was examined by ELISA. The subsets and frequency of IFN-gamma-producing cells were examined at a single-cell level by flow cytometry. RESULTS: After PBMCs stimulation with anti-CD3 and TP5 (300 microg/ml), the level of IFN-gamma expression was significantly inhibited (P(child) = 0.0001, P(adult) = 0.01); and the level of IFN-gamma expression from normal adult and child controls was also significantly inhibited (P(child) = 0.009, P(adult) = 0.0001). In addition, the inhibition of TP5 on the production of IFN-gamma by PBMCs from MG children was lower compared with normal child control. But as compared with normal adult control, the inhibition of TP5 showed no significant difference in MG adults (P(adult) = 0.481). TP5 inhibited the expression of IFN-gamma by CD8+ T cell and CD4+ T cell. CONCLUSION: TP5 can inhibit the response of cellular immune by decreasing the production of IFN-gamma in MG consequence display that the level of IFN-gamma significant decreased with the addition of TP5 and anti-CD3. But after considering the age, the level of IFN-gamma in MG children was no as much inhibited as normal child. TP5 inhibits the expression of IFN-gamma by CD8+ T and CD4+ T cells.

[Thymopentin 5 in treatment of relapse after extended thymectomy: a randomized comparative clinical trial of 135 patients with myasthenia gravis].

OBJECTIVE: To investigate the effect of thymopentin 5 (TP5) combined with immunosuppressive agents in treatment of relapse after extended thymectomy in patients with myasthenia gravis (MG). METHODS: One hundred thirty-five MG patients who were to undergo extended thymectomy, 62 adults and 73 children, were randomly assigned to 2 groups: non-TP5 group (n = 60) treated with intramuscular injection of prednisone + pyridostigmine daily for 3 months as a basic treatment, and TP5 group (n = 73), treated with prednisone + pyridostigmine + TP5 for 3 months. Follow-up was conducted for more than 1 year. RESULTS: The remission rates of children in the TP5 group at different time points were all markedly higher than those in the non-TP5 group, and the remission rates of children in the TP5 group during the period of 2 months to 2 years after thymectomy were all significantly higher (all P < 0.05). And the remission rates of the adults of the TP5 group during the period of 6 months to 2 years after thymectomy were all significantly higher than those of the non-TP5 group (all P < 0.05). In the pediatric cases the withdrawal rate of the TP5 group was significantly higher, and the relapse rate was significantly lower than those of the non-TP5 group. No side effect developed during the follow-up. CONCLUSION: TP5 is effective in reducing relapse and has a higher drug withdrawal rate, especially among children.

[Prognostic factors related to recurrence after extended thymectomy in patients with myasthenia gravis].

OBJECTIVE: To identify the recurrence-related factors in patients with myasthenia gravis (MG) after extended thymectomy. METHODS: Followed up was conducted on 271 MG patients, 127 males and 146 females, aged 31 (4-57), who underwent extended thymectomy for 18-84 months. Post-operational pathological examination showed 32 cases of thymoma and 239 cases of diseases other than thymoma. After operation the patients were treated with pyridostigmine only or combined with adrenocortical hormone. The relevant factors of the 135 patients with relapse were evaluated: sex, Osserman classification, age while being operated on, duration of preoperative period, pathologic type of thymus, use of steroid before operation, infection after operation, whether only taking anticholinesterase drugs after operation, use of steroid immediately after operation, stopping medicine or decreasing the dose of medicine within 1-3 months after remission of symptoms. RESULTS: COX univariate analysis revealed that failure to take steroid immediately after operation (OR = 2.914, P = 0.000), infection after operation (OR = 3.441, P = 0.000), only taking anticholinesterase drugs after operation (OR = 5.947, P = 0.000), and immediately stopping medicine use or decreasing the dose of medicine within 1-3 months after the remission of symptoms (OR = 2.242, P = 0.000) were prognostic factors for postoperative recurrence. On the other hand, multivariate logistic regression analysis revealed that infection after operation (OR = 47.63, P = 0.000), only taking anticholinesterase drugs after operation (OR = 62.38, P = 0.000), and stopping medicine or decreasing the dose of medicine 1-3 months after remission of symptoms (OR = 32.76, P = 0.000) were independent influencing factors of recurrence after operation. CONCLUSION: Post-operative infection, only taking pyridostigmine, and stopping medicine too early are independent factors of postoperative relapse. Regular treatment and timely use of adrenocortical hormone decrease the recurrence after operation.

[Correlation between pathogenesis of myasthenia gravis and thymus mature dendritic cells].

OBJECTIVE: To investigate the correlation between onset of myasthenia gravis (MG) and the changes of the number and distribution of thymus mature dendritic cells (mDC). METHODS: The specimens of thymus were obtained during operation from 39 MG patients who hadn't received immunosuppressive therapy before thymectomy and 19 sex- and age-matched patients who underwent cardiosurgery as controls. Immunohistochemistry with antibody against DC-LAMP, specific surface marker of DC, was used to examine the number and distribution of thymus mDCs. RESULTS: (1) mDCs were restricted in the medulla and cortex-medulla junctional zone of thymus in the control group; while were irregularly distributed in the cortex, medulla, and stroma in the MG group. (2) mDCs presented a roughly uniform distribution in the medulla of thymus in the control group, while clustering distribution was more often in the MG group, especially dense around the germinal center. (3) The relative ratio and numbers of mDCs per average field of vision in the positive areas of the MG group were (10.9% +/- 2.2%) and (50 +/- 9), both significantly higher than those of the control group [(8.5% +/- 1.5%) and (41 +/- 7) respectively, both P < 0.05]. CONCLUSION: The number and ratio of the thymus mDCs in MG are high, high, and the distribution abnormal. mDC actively may be actively involved in the pathogenesis of MG.

[The role of CD4+ CD25+ T cells in the mechanism of myasthenia gravis in children and adults].

OBJECTIVE: To investigate the role of CD4+CD25+ regulatory T cells in the mechanism of myasthenia gravis (MG) in children and adults. METHODS: Peripheral blood samples were collected from 13 MG patients, 5 being aged > 14 and 8 being aged

[Synthesis, characterization and fluorescence property of an unsymmetrical Schiff base and its copper complex].

An unsymmetrical tetradentate Schiff base ligand (H2L) was synthesized using 5-chloro-2-hydroxybenzophenone, o-phenylenediamine and salicylaldehyde. A solid complex of this ligand CuL was prepared and characterized by elemental analyses, IR spectra, UV spectra, TG-DTG and molar conductance. Possible structure of this complex was proposed. The fluorescence property of the ligand and complex was also studied. The result indicates that the Schiff base reagent exhibits a maximum of fluorescence emission spectrum at 385 nm. At pH 9.62, the copper complex of this reagent can cause fluorescence quenching of the reagent.

[Clinical value of the immune parameters in patients with myasthenia gravis].

OBJECTIVE: To evaluate the clinical value of the indices, including IgG, IgA, IgM, CD3, CD4 and CD8. METHODS: Detect CD3, CD4, CD8 by flow cytometry and detect IgG, IgA, IgM by turbidimetric method. We analyzed clinical features according to different classification of immune index, and changes of the level of these immune indices before and after treatment. RESULT: The level of IgG, IgA in patients with generalized MG was higher than that of ocular MG (P < 0.05). The ratio of CD4 to CD8 was classified into 3 groups: low (118 cases), high (60 cases), normal (68 cases). Likewise, the level of IgG, IgA, IgM was classified into 4 groups: low (156 cases), high (65 cases), disorder (31 cases), normal (67 cases). There was no statistically significance on changes of level of these immune indices before and after treatment. There was no statistically significance on clinical materials among different groups. In the low group of humoral immunity, the remission ratio of the patients with the treatment of gamma globulin was higher than that of patients without gamma globulin (95.2%, 28.8%, respectively. P < 0.01). CONCLUSION: The immune indices of IgG, IgA, IgM, CD3, CD4, CD8 seemed to be irrelevant to severity of disease and prognosis. To some extent, these immune indices can be reference in the aspect of treatment.