[Correlation between clinical manifestation, prognosis and antibody in anti-muscle-specific tyrosine kinase antibody positive myasthenia gravis].

Objective: To determine the correlation between the titer of anti-muscle-specific tyrosine kinase (anti-MuSK) antibodies (Abs) and the severity and prognosis of Musk-associated myasthenia gravis (Musk-MG). Methods: A total of 33 MuSK-MG patients diagnosed at Department of Neurology, Peking Union Medical College Hospital from May 2018 to June 2020 were prospectively included. Patients were divided into different groups according to immune state, and the immune naive patients were further divided by the Myasthenia Gravis Foundation of America (MGFA) classification. There were 28 Musk-MG patients who completed the follow-up and subdivided into different groups according to post-intervention status (PIS). Twenty-five patients who received immunotherapy were divided into corticosteroid monotherapy group (n=17) and corticosteroid combined with immunosuppressant group (n=8). The comparison of Ab titers between different MGFA groups and PIS groups was determined by Kruskal-Wallis method, and the comparison of Ab titers between different time points was analyzed by Mann-Whitney U method. Results: There were 11 males and 22 females included in the study, with an onset age of 48 (18, 73) years, of which 16 cases were immune naive and 17 cases were treated with corticosteroids or immunosuppressant at least once. In immune naive population, a significant difference of Ab titers among different MGFA phenotypes was detected (P=0.04). Ab titers were reduced by immunosuppression therapy (the median value decreased from 1.20 to 0.87, P=0.01). Twenty-four (85.7%) MuSK-MG patients achieved a good prognosis (PIS-PR/MM), 1 (3.6%) case achieved improvement (PIS-I), and 3 (10.7%) patients' condition worsened (PIS-W), there was no significant difference of Ab titers among the three groups (P=0.21). Meanwhile, there was no significant difference of Ab titers between different treatment groups (P=0.95). Conclusions: In the immune naive state, the concentration of MuSK-Ab is consistent with the severity of the disease, and the Ab titers decrease after immunotherapy. Change of Ab titers is related to the daily dosage of corticosteroid and is not consistent with PIS grades.

MiR-223-5p inhibitor suppresses microglia inflammation and promotes Nrg-1 in rats of spinal cord injury.

OBJECTIVE: The aim of this study was to investigate the role of microRNA-233-5p (miR-233-5p) in spinal cord injury (SCI), and to explore the possible underlying mechanism. MATERIALS AND METHODS: Microglia were first isolated from neonate rats and cultured in a suitable environment in vitro. Lipopolysaccharide (LPS) and interleukin-4 (IL-4) were used to activate microglia. The expressions of miR-223-5p, inducible nitric oxide synthase (iNOS) and arginase 1 (Arg-1) were measured by qRT-PCR, respectively. After transfection of miR-233-5p inhibitor, the expression levels of miR-223-5p, iNOS and Arg-1 in cells were detected as well. A moderate SCI model was successfully established in rats (10 g fallen on T10 spinal cord at the height of 5 cm). Subsequently, inflammation indexes at miR-223-5p peak moment were observed. Meanwhile, its neuro-protective effect at 28 days after SCI was estimated. Finally, Basso, Beattie, and Bresnahan (BBB) rating scale was applied to evaluate the hindlimb locomotor function of rats at 1, 3, 7, 14, 21, 28 days after SCI. RESULTS: MiR-223-5p inhibitor significantly promoted M2 microglia expression and degenerated M1 microglia expression in vitro. SCI elevated the level of miR-223-5p in injured spinal cord tissues within one week, which reached a peak at 5 days after injury. Meanwhile, miR-223-5p inhibitor remarkably reduced the expressions of inflammatory factors, including interleukin-1 beta (IL-1ß), interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-α) at 3 days after SCI, as well as increased neuregulin1 (NRG-1) expression. However, miR-223-5p inhibitor significantly declined the levels of apoptosis key enzyme-caspase-3 and glia reaction marker-glial fibrillary acidic protein (GFAP) at 7 and 28 days after SCI, respectively. As a result, BBB rating scale demonstrated that hindlimb locomotor function was significantly recovered in miR-223-5p injection group. CONCLUSIONS: MiR-223-5p was up-regulated in M1 microglia, whereas down-regulated in M2 microglia. MiR-223-5p inhibitor could significantly increase M2 microglia expression, while decrease M1 microglia expression in vitro. In vivo, miR-223-5p inhibitor suppressed the inflammatory response and reinforced NRG-1 level to reduce glia reaction and neuron apoptosis. Thereby, its treatment promoted the hindlimb locomotor function of rats.

[Glucose and lipid metabolic disorders in myasthenia gravis patients and its mechanisms].

Objective: To investigate the glucose and lipid metabolic disorders in patients with myasthenia gravis (MG) without glucocorticoid therapy, and the relationships between insulin, insulin resistance, muscle strength, serum levels of osteocalcin, 25-hydroxy vitamin D (25OHD) and glucose and lipid metabolism. Methods: A total of 102 MG patients [(40±11) years old, 43 males and 59 females] without glucocorticoid treatment were enrolled in this cross-sectional study. Height, weight and the handgrip of dominant hands were measured. Serum levels of fasting blood glucose (FBG), 2-hour postprandial blood glucose (2 h PBG), glycosylated hemoglobin (HbA1c), fasting insulin (FINS), 2-hour postprandial insulin (2 h PINS), total cholesterol (TC), triglyceride (TG), high density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C) and osteocalcin, 25OHD were detected. Insulin resistance was assessed using homeostasis model assessment of insulin resistance (HOMA-IR). Results: The proportion of impaired fasting glucose or impaired glucose tolerance, type 2 diabetes, dyslipidemia, hyperinsulinemia in male and female were 30.0%, 10.0%, 50.0%, 33.3% and 17.5%, 3.5%, 27.7%, 7.1%, respectively. Serum osteocalcin levels in male and female were 2.8 (1.7, 4.4) µg/L and 2.3 (1.3, 3.9) µg/L, respectively. And 25OHD levels in male and female were (93.5±34.9) nmol/L and (81.0±30.5) nmol/L, respectively. Handgrip of male and female was (37.0±9.4) kg and (20.5±6.3) kg. After adjusted for age, FINS (r=0.619, P<0.001), 2 h PINS (r=0.640, P<0.001), HOMA-IR (r=0.534, P<0.001) were positively correlated with 2 h PBG, and the handgrip was negatively correlated with TC (r=-0.486, P=0.026), LDL-C (r=-0.485, P=0.026) in male. FINS (r=0.352, P=0.008; r=0.300, P=0.026; r=0.646, P<0.001) and 2 h PINS (r=0.278, P=0.040; r=0.518, P<0.001; r=0.382, P=0.006) and HOMA-IR (r=0.695, P<0.001; r=0.583, P<0.001; r=0.818, P<0.001) were positively correlated with FBG, 2 h PBG, HbA1c, and the handgrip were negatively correlated with FBG (r=-0.424, P=0.016), 2 h PINS (r=-0.345, P=0.034) and positively correlated with HDL-C (r=0.389, P=0.037) in female. There was no association between osteocalcin, 25OHD and glucose and lipid metabolism. Multivariate linear regression analysis also found that there were significant relationships between handgrip, insulin, insulin resistance levels and glucose and lipid metabolic disorders. Conclusion: There was a high proportion of glucose and lipid metabolic disorders in MG patients without glucocorticoid treatment, and the mechanism may be related to insulin resistance induced by muscle weakness.

[Sample size for the estimation of F-wave parameters in healthy volunteers and amyotrophic lateral sclerosis patients].

Objective: The study aimed to investigate whether sample sizes of F-wave study differed according to different nerves, different F-wave parameters, and amyotrophic lateral sclerosis(ALS) patients or healthy subjects. Methods: The F-waves in the median, ulnar, tibial, and deep peroneal nerves of 55 amyotrophic lateral sclerosis (ALS) patients and 52 healthy subjects were studied to assess the effect of sample size on the accuracy of measurements of the following F-wave parameters: F-wave minimum latency, maximum latency, mean latency, F-wave persistence, F-wave chronodispersion, mean and maximum F-wave amplitude. A hundred stimuli were used in F-wave study. The values obtained from 100 stimuli were considered "true" values and were compared with the corresponding values from smaller samples of 20, 40, 60 and 80 stimuli. F-wave parameters obtained from different sample sizes were compared between the ALS patients and the normal controls. Results: Significant differences were not detected with samples above 60 stimuli for chronodispersion in all four nerves in normal participants. Significant differences were not detected with samples above 40 stimuli for maximum F-wave amplitude in median, ulnar and tibial nerves in normal participants. When comparing ALS patients and normal controls, significant differences were detected in the maximum (median nerve, Z=-3.560, P<0.01; ulnar nerve, t=5.019, P<0.01; tibial nerve, Z=-2.475, P<0.05; peroneal nerve, Z=-2.088, P<0.05)and mean F-wave latency (median nerve, Z=-3.243, P<0.01; ulnar nerve, t=3.876, P<0.01; tibial nerve, Z=-2.206, P<0.05; peroneal nerve, Z=-2.205, P<0.05)in all four nerves, F-wave chronodispersion (Z=-3.152, P<0.01)in the ulnar nerve, F-wave persistence in the median (Z=6.139, P<0.01)and ulnar nerves(Z=5.350, P<0.01), mean F-wave amplitude in the tibial nerve(t=2.981, P<0.01), maximum F-wave amplitude in the ulnar (Z=-2.134, P<0.05)and tibial nerves (t=2.746, P<0.01)with 20 stimuli; for chronodispersion in tibial nerve (t=2.551, P<0.05)100 stimuli, for chronodispersion in peroneal nerve (Z=-2.086, P<0.05)80 stimuli, for F-wave persistence in tibial nerve (Z=2.119, P<0.05) 60 stimuli, for mean F-wave amplitude in ulnar (Z=-2.552, P<0.05)and peroneal nerve (Z=-2.228, P<0.05)40 stimuli, for maximum F-wave amplitude in peroneal nerve (t=2.693, P<0.01)60 stimuli were necessary to detect differences. Conclusions: Sample sizes of F-wave study differed according to different nerves, different F-wave parameters , and ALS patients or healthy subjects.

Glycine blocks long-term potentiation of GABAergic synapses in the ventral tegmental area.

The mesocorticolimbic dopamine system, originating in the ventral tegmental area (VTA) is normally constrained by GABA-mediated synaptic inhibition. Accumulating evidence indicates that long-term potentiation of GABAergic synapses (LTPGABA) in VTA dopamine neurons plays an important role in the actions of drugs of abuse, including ethanol. We previously showed that a single infusion of glycine into the VTA of rats strongly reduces ethanol intake for 24h. In the current study, we examined the effect of glycine on the electrophysiological activities of putative dopamine VTA neurons in midbrain slices from ethanol-naïve rats. We report here that a 15-min exposure to 10 µM glycine prevented trains of high-frequency stimulation (HFS) from producing LTPGABA, which was rescued by the glycine receptor (GlyR) antagonist strychnine. Glycine also concentration-dependently decreased the frequency of spontaneous excitatory postsynaptic currents (sEPSCs). By contrast, glycine pretreatment did not prevent potentiation of inhibitory postsynaptic currents (IPSCs) during a continuous exposure to the nitric oxide (NO) donor, SNAP (S-nitroso-N-acetylpenicillamine), or a brief exposure to 10 µM glycine and 10 µM NMDA (N-methyl-D-aspartate), an agonist of NMDA-type glutamate receptors. Thus, the blockade of LTPGABA by glycine is probably resulted from suppressing glutamate release by activating the GlyRs on the glutamatergic terminals. This effect of glycine may contribute to the reduction in ethanol intake induced by intra-VTA glycine observed in vivo.

Binding of E. coli to human blood leukocytes.

The spontaneous binding of both piliated and non-piliated E. coli to human lymphocytes, monocytes, and polymorphonuclear leukocytes (PMN) was investigated. It was found that the piliated E. coli showed a higher binding percentage to lymphocytes than the nonpiliated bacteria. A specific antiserum raised in rabbit against E. coli strongly inhibited the binding of the homologous E. coli strain to lymphocytes and monocytes. On the other hand there was no difference in the binding of piliated and non-piliated E. coli to PMNs, and the specific E. coli antiserum did not inhibit the binding. The binding of E. coli to human lymphocytes obtained from healthy donors was investigated in a 3-week follow-up experiment. It was shown that there were significant differences between the binding of cells from different individuals, whereas there were no differences in the binding ability of the cells from the same individual in the 3-week follow up.