Intrathymic miR-548k modulating CXC chemokine ligand 13 expression in myasthenia gravis patients with thymic hyperplasia / 中华神经医学杂志

Objective To explore the microRNAs regulation of CXC chemokine ligand 13 (CXCL13) in patients with myasthenia gravis combined with thymic hyperplasia (MGH).Methods Thirteen MGH tissues and 13 normal thymus tissues,collected in our hospital from March 2012 to August 2013,were used in our study.Total RNAs from these tissues were extracted by trizol and hybridized with the microarray.The miRNAs targeting CXCL13 gene-3'untranslated region were predicted by using bioinformatics.Real-time fluorogenic quantitative PCR (QRT-PCR) was employed to detect the expressions ofCXCL13 mRNAs and microRNAs in thymus tissues.Luciferase assay was used to analyze the miRNAs modulated CXCL13 expression.Results The miRNA microarray chip analysis identified 33 miRNAs differentially expressed in MGH tissues as compared with those in the control group,miR-548k was one of most obvious down-regulated miRNAs (1.98 fold).Bioinformatical analysis indicated that miR-548k can target CXCL13 3' UTR.QRT-PCR showed that the expression of CXCL13 mRNA was up-regulated and miR-548k was down-regulated in thymus hyperplasia tissues of MGH group as compared with those in the control group(4.93±l.95 vs.1.04±0.20; 0.55±0.20 vs.1.33±0.36,P＜0.05); and they showed a negative correlation (r=-0.93,P=0).003).As compared with that in the control group (1.000±0.050),the luciferase activity of pmiR-RB-REPORTTM-CXCL13-3'UTR treated with miR-548k mimics (0.385±0.016) decreased 61.5％,with significant difference (P＜0.05).Conclusion MiR-548k inhibits CXCL13 expression by post-transcriptional gene silencing to promote MG development and progression.

Incidence of Thymoma in Myasthenia Gravis: A Systematic Review

BACKGROUND AND PURPOSE: Myasthenia gravis (MG) is usually comorbid with thymoma. More accurate estimates of the incidence thymoma in MG will help inform patients and their physicians, facilitate health policy discussions, provide etiologic clues, and optimize the management of MG. METHODS: We conducted a systematic review search of relevant English-language studies published between 1960 and 2012 using MEDLINE and Embase. We identified additional studies by reviewing the bibliographies of the retrieved articles and hand searched the main neurology journals. Only incidence studies and case series of unselected MG patients in which information about thymoma were included. RESULTS: Out of 2206 potentially relevant studies, 49 met the inclusion criteria. Although there was a considerable degree of heterogeneity, the pooled estimate of the incidence of thymoma in MG was 21% (95% confidence interval, 20-22%). The pooled incidence was significantly higher for surgery-based studies than for population- and hospital-based studies. A large proportion of the reported thymomas were noninvasive. Furthermore, thymoma appears to occur significantly more frequently among male MG patients and those older than 40 years at the onset of MG. CONCLUSIONS: Thymoma is common in MG patients, but appears to be found more often in male MG patients and those older than 40 years at the onset of MG. Further research is needed to expand our understanding of these association conditions.

Variations of brain magnetic resonance imaging among manganese-exposed workers / 中华预防医学杂志

<p><b>OBJECTIVE</b>Variations of the signal intensities in the magnetic resonance (MR) T(1)-weighted image (T(1)WI) of globus pallidus among manganese(Mn)-exposed workers were explored to provide a scientific basis for exposed biomarker of manganese-injured central nervous system (CNS).</p><p><b>METHODS</b>The brain MR T(1) and T(2) WI in eighteen male asymptomatic Mn-exposed, eight manganism and nine healthy control workers were examined routinely by adopting a 1.5 Tesla signal superconducting system. The SIGP and the signal intensity in frontal white matter (SIFWM) in the same side were determined, then pallidal index (PI) was calculated. Concentration of MnO(2) in workplaces and content of manganese in red blood cell (MnRBC) among workers were respectively determined by flame atomic absorption spectrometer (AAS) and inductively coupled plasma-atomic emission spectrophotometry (ICP-AES). The follow-up investigation in the eight high Mn-exposed workers was made one year later.</p><p><b>RESULTS</b>The results showed that the median of air MnO(2) in smelting workplace was 0.64 mg/m(3)(0.07 - 5.40 mg/m(3)), which were respective 0.56 mg/m(3)(0.09 - 1.71 mg/m(3)) in power distribution room (low Mn-exposure) and 0.89 mg/m(3) (0.07 - 5.40 mg/m(3)) in furnace (high Mn-exposure). PI in the Mn-exposed and high Mn-exposed workers were both higher than those of the manganism and control workers(116.4 +/- 8.2, 119.0 +/- 7.9, 105.3 +/- 8.4 and 102.2 +/- 1.5, respectively. Mn vs control, t' = 7.146, P = 0.000; Mn vs manganism, t = 3.181, P = 0.004. High Mn-exposure vs control, t' = 7.446, P = 0.000; high Mn-exposure vs manganism, t = 3.763, P = 0.001). The increased signal in T(1)WI of globus pallidus was observed in Mn-exposed workers, especially in high Mn-exposed workers. The content of manganese in red blood cell of Mn-exposed and control workers was significantly higher than those of the manganism workers [(151.6 +/- 40.5) ng/ml, (149.2 +/- 21.3) ng/ml, (154.5 +/- 46.6) ng/ml, (144.4 +/- 14.2) ng/ml, (20.8 +/- 7.4) ng/ml respectively. The difference was significant in statistics. Manganism vs control, t = 20.206, P = 0.000; manganism vs Mn, t' = 13.144, P = 0.000; manganism vs low and high Mn, t' = 12.964, 9.957, respectively, P = 0.000]. Only a decreased median of air MnO(2) in furnace was found one year later (0.89, 0.31 mg/m(3), Z = -2.142, P = 0.032). The difference was significant in statistics.</p><p><b>CONCLUSION</b>Our data suggests that SIGP of MR T(1)WI among workers was obviously increased by manganese-exposure. PI may be taken as the signal of CNS injury which was induced by manganese-exposure.</p>