A series of patients with refractory myasthenia gravis

INTRODUCTION

Advances in the treatment of myasthenia gravis (MG) have improved quality of life and prognosis for the majority of patients. However, 10%-20% of patients present refractory MG, with frequent relapses and significant functional limitations.

PATIENTS AND METHODS

Patients with refractory MG were selected from a cohort of patients diagnosed with MG between January 2008 and June 2019. Refractory MG was defined as lack of response to treatment with prednisone and at least 2 immunosuppressants, inability to withdraw treatment without relapse in the last 12 months, or intolerance to treatment with severe adverse reactions.

RESULTS

We identified 84 patients with MG, 11 of whom (13%) met criteria for refractory MG. Mean (standard deviation) age was 47 (18) years; 64% of patients with refractory MG had early-onset generalised myasthenia (as compared to 22% in the group of patients with MG; P < .01), with a higher proportion of women in this group (P < .01). Disease severity at diagnosis and at the time of data analysis was higher among patients with refractory MG, who presented more relapses during follow-up. Logistic regression analysis revealed an independent association between refractory MG and the number of severe relapses.

CONCLUSIONS

The percentage of patients with refractory MG in our series (13%) is similar to those reported in previous studies; these patients were often women and presented early onset, severe forms of onset, and repeated relapses requiring hospital admission during follow-up.

A series of patients with refractory myasthenia gravis

INTRODUCTION

Advances in the treatment of myasthenia gravis (MG) have improved quality of life and prognosis for the majority of patients. However, 10%-20% of patients present refractory MG, with frequent relapses and significant functional limitations.

PATIENTS AND METHODS

Patients with refractory MG were selected from a cohort of patients diagnosed with MG between January 2008 and June 2019. Refractory MG was defined as lack of response to treatment with prednisone and at least 2 immunosuppressants, inability to withdraw treatment without relapse in the last 12 months, or intolerance to treatment with severe adverse reactions.

RESULTS

We identified 84 patients with MG, 11 of whom (13%) met criteria for refractory MG. Mean (standard deviation) age was 47 (18) years; 64% of patients with refractory MG had early-onset generalised myasthenia (as compared to 22% in the group of patients with MG; P<.01), with a higher proportion of women in this group (P<.01). Disease severity at diagnosis and at the time of data analysis was higher among patients with refractory MG, who presented more relapses during follow-up. Logistic regression analysis revealed an independent association between refractory MG and the number of severe relapses.

CONCLUSIONS

The percentage of patients with refractory MG in our series (13%) is similar to those reported in previous studies; these patients were often women and presented early onset, severe forms of onset, and repeated relapses requiring hospital admission during follow-up.

[Cognitive Reserve Scale: testing the theoretical model and norms]

INTRODUCTION

The cognitive reserve theory may contribute to explain cognitive performance differences among individuals with similar cognitive decline and among healthy ones. However, more psychometric analysis are needed to guarantee the usage of tests for assessing cognitive reserve.

AIMS

To study validity evidences in relation to the structure of the Cognitive Reserve Scale (CRS) and to create reference norms to interpret the scores.

SUBJECTS AND METHODS

A total of 172 participants completed the scale and they were classified into two age groups: aged 36-64 years (n = 110) and 65-88 years (n = 62).

RESULTS

The exploratory factor analysis using ESEM revealed that the data fitted the proposed model. Overall, the discriminative indices were acceptable (between 0.21 and 0.50) and congruence was observed in the periods of young adulthood, adulthood and late adulthood, in both age group. Besides, the index of reliability (Cronbach's alpha: 0.80) and the typical mean error test (mean: 51.40 ± 11.11) showed adequate values for this type of instrument.

CONCLUSION

The CRS seemed to be set under the hypothetical theoretical model, and the scores might be interpreted by the norms showed. This study provided guarantees for the usage of the CRS in research.

Structure of the C2 domain from novel protein kinase Cepsilon. A membrane binding model for Ca(2+)-independent C2 domains

Protein kinase Cepsilon (PKCepsilon) is a member of the novel PKCs which are activated by acidic phospholipids, diacylglycerol and phorbol esters, but lack the calcium dependence of classical PKC isotypes. The crystal structures of the C2 domain of PKCepsilon, crystallized both in the absence and in the presence of the two acidic phospholipids, 1,2-dicaproyl-sn-phosphatidyl-l-serine (DCPS) and 1,2-dicaproyl-sn-phosphatidic acid (DCPA), have now been determined at 2.1, 1.7 and 2.8 A resolution, respectively. The central feature of the PKCepsilon-C2 domain structure is an eight-stranded, antiparallel, beta-sandwich with a type II topology similar to that of the C2 domains from phospholipase C and from novel PKCdelta. Despite the similar topology, important differences are found between the structures of C2 domains from PKCs delta and epsilon, suggesting they be considered as different PKC subclasses. Site-directed mutagenesis experiments and structural changes in the PKCepsilon-C2 domain from crystals with DCPS or DCPA indicate, though phospholipids were not visible in these structures, that loops joining strands beta1-beta2 and beta5-beta6 participate in the binding to anionic membranes. The different behavior in membrane-binding and activation between PKCepsilon and classical PKCs appears to originate in localized structural changes, which include a major reorganization of the region corresponding to the calcium binding pocket in classical PKCs. A mechanism is proposed for the interaction of the PKCepsilon-C2 domain with model membranes that retains basic features of the docking of C2 domains from classical, calcium-dependent, PKCs.

Determination of parameters that characterize effector-target conjugation of human NK and LAK cells by flow cytometry

Effector-target conjugation between different cell populations of human NK cells and K562 tumor cells has been studied from binding isotherms obtained from data of effector (alpha) and target (beta) conjugate frequencies measured by flow cytometry analysis at different effector-to-target ratios. Non-linear and linear regression methods were applied to these isotherms to calculate the binding parameters that characterize the process of conjugation, namely, the maximum effector and target conjugate frequencies, the dissociation constant of the conjugates formed, the binding units and the area under the binding isotherms. The results obtained show that: (1) flow cytometry analysis of effector-target conjugation is faster, unbiased and more suitable than microscopic counting of conjugates, thereby permitting the analysis of larger number of conjugates in shorter times, (2) the binding parameters derived from conjugate frequencies obtained by flow cytometry analysis differ from those obtained by microscopy, (3) the discrepancies between the two methods are due to the presence of several cells engaged in multicellular conjugates that are detected as single particles by flow cytometry and (4) the analysis of population distributions of the conjugates formed at different values of the effector-to-target ratio permit the above discrepancies to be corrected.