Clinical characteristics of late-onset myasthenia gravis.

Objective: Late-onset myasthenia gravis (LOMG) often has comorbidities, and its initial symptoms may be ignored or misdiagnosed as other diseases. There were few large surveys on LOMG. Our study aimed to summarize clinical characteristics of LOMG to improve the rate of correct MG diagnosis. Methods: A retrospective cohort study included 240 LOMG patients with onset age ≥65 years old who were treated at PLA General Hospital from January 1, 2003 to January 1, 2023. Results: The male to female ratio was 1:1.2 (P = 0.699). MGFA clinical classification: Class I 31.3%, Class IIa 12.9%, Class IIb 51.3%, Class IIIa 0.8%, Class IIIb 0.8%, Class IV 0.4%, Class V2.5%. The onset symptom was ptosis in 78.8% and diplopia was in 18.8%. Swallowing dysfunction in the stage of LOMG was in 41.7%. The incidence of thymoma in LOMG was 14.2%. 85.4% of patients antibodies against the muscle acetylcholine receptor (AChR) are detected. The overall incidence of supramaximal repetitive nerve stimulation (Jolly test) was 57.1%, among which the highest positive rate (50.7%) was in the facial nerve. Jolly test of Class IIb was tested in the highest positive rate and Class I was in the lowest one (χ2 = 7.023, P = 0.030). Conclusion: There was no significant difference in the incidence of LOMG between males and females. The clinical manifestations were mainly Class I and Class II, and severe MG was rare. The most common onset symptom was ptosis. The incidence of LOMG with thymoma was low. Supramaximal repetitive nerve stimulation (Jolly test) of the facial nerve was the easiest to detect and Jolly test of Class IIb was tested in the highest positive rate and Class I was in the lowest one.

Dilemma in Differentiation of Spinocerebellar Ataxia Type 17 from Huntington's Disease：Comorbidity or Independent Disease?

Both Huntington's disease (HD) and Spinocerebellar ataxia 17 (SCA17) mutations showed expanded CAG repeats, with overlapping clinical manifestation: motor disorders, psychiatric symptoms and cognitive impairments. Therefore, SCA17 is also called Huntington like disease (HD-like, HDL) type 4. In this paper, we reported that one patient had 47 CAG repeats in HTT gene and 42 CAG repeats in TBP gene. There is a dilemma in differentiation of SCA 17 from HD in one patient, never been reported before. Is the diagnosis comorbidity of HD with SCA17 or HD only?

The High Value of External Anal- and Urethral-Sphincter Electromyography in Differential Diagnosis with MSA-P, PD, and PSP.

Objective: It is a challenge to differentiate multiple system atrophy parkinsonism (MSA-P), Parkinson's disease (PD), and progressive supranuclear palsy (PSP). We aimed to explore the value of external anal-sphincter electromyography (EAS-EMG) and urethral-sphincter electromyography (US-EMG) in differential diagnosis with MSA-P, PD, and PSP. Methods: A total of 149 subjects, including 27 MSA-P, 100 PD, and 22 PSP, were recruited. The average duration and amplitude of motor unit potentials (MUPs), percentage of polyphasic MUPs, amplitude during strong contraction, and recruitment pattern during maximal voluntary contraction were recorded. The differences in EAS-EMG and US-EMG results between MSA-P, PD, and PSP were analyzed. Results: In EAS-EMG examination, the average duration of MUPs of MSA-P was significantly longer than that of PD and PSP; the percentage of polyphasic MUPs and the ratio of simple phase and simple-mix phase of MSA-P and PSP were significantly higher than that of PD; the amplitude during strong contraction of MSA-P was significantly lower than that of PD. In US-EMG examination, the average duration of MUPs in male MSA-P was significantly longer than that in male PD and PSP; the ratio of simple phase and simple-mix phase in male MSA-P was significantly higher than that in male PD; there was no statistical difference in US-EMG indexes between male PD and PSP male. And because only one female PSP was examined, only female MSA-P and PD were compared, the average duration of MUPs in female MSA-P was significantly longer than that in female PD; the ratio of simple phase and simple-mix phase in female MSA-P was significantly higher than that in female PD. Conclusion: The average duration of MUPs and the ratio of the simple phase and simple-mix phase of EAS-EMG and US-EMG all can provide the basis for the differential diagnosis between MSA-P and PD. US-EMG can be used as a supplement to differentiate MSA-P from PD when EAS-EMG is limited. The only discriminating indicator between MSA-P and PSP seems to be the average duration of MUPs of EAS-EMG and US-EMG. There is still a lack of diagnostic electromyography indicators between PD and PSP.

Late-Onset Anti-GABAB Receptor Encephalitis: Clinical Characteristics and Outcomes Differing From Early-Onset Patients.

BACKGROUND AND OBJECTIVES: Existing evidence indicates anti-GABAB receptor encephalitis (GABABR-E) seems to occur more commonly later in life, yet the age-associated differences in clinical features and outcomes are not well determined. This study aims to explore the demographic, clinical characteristics, and prognostic differences between late-onset and early-onset GABABR-E and identify predictors of favorable long-term outcomes. METHODS: This is an observational retrospective study conducted in 19 centers from China. Data from 62 patients with GABABR-E were compared between late-onset (aged 50 years or older) and early-onset (younger than 50 years) groups and between groups with favorable outcomes (modified Rankin scale (mRS) ≤ 2) and poor outcomes (mRS >2). Logistic regression analyses were applied to identify factors affecting long-term outcomes. RESULTS: Forty-one (66.1%) patients experienced late-onset GABABR-E. A greater proportion of males, a higher mRS score at onset, higher frequencies of ICU admission and tumors, and a higher risk of death were demonstrated in the late-onset group than in the early-onset group. Compared with poor outcomes, patients with favorable outcomes had a younger onset age, a lower mRS score at onset, lower frequencies of ICU admission and tumors, and a greater proportion with immunotherapy maintenance for at least 6 months. On multivariate regression analysis, age at onset (OR, 0.849, 95% CI 0.739-0.974, p = 0.020) and the presence of underlying tumors (OR, 0.095, 95% CI 0.015-0.613, p = 0.013) were associated with poorer long-term outcomes, whereas immunotherapy maintenance for at least 6 months was associated with favorable outcomes (OR, 10.958, 95% CI 1.469-81.742, p = 0.020). DISCUSSION: These results demonstrate the importance of risk stratification of GABABR-E according to age at onset. More attention should be paid to older patients especially with underlying tumors, and immunotherapy maintenance for at least 6 months is recommended to achieve a favorable outcome.

The value of convolutional neural networks-based deep learning model in differential diagnosis of space-occupying brain diseases.

Objectives: It is still a challenge to differentiate space-occupying brain lesions such as tumefactive demyelinating lesions (TDLs), tumefactive primary angiitis of the central nervous system (TPACNS), primary central nervous system lymphoma (PCNSL), and brain gliomas. Convolutional neural networks (CNNs) have been used to analyze complex medical data and have proven transformative for image-based applications. It can quickly acquire diseases' radiographic features and correct doctors' diagnostic bias to improve diagnostic efficiency and accuracy. The study aimed to assess the value of CNN-based deep learning model in the differential diagnosis of space-occupying brain diseases on MRI. Methods: We retrospectively analyzed clinical and MRI data from 480 patients with TDLs (n = 116), TPACNS (n = 64), PCNSL (n = 150), and brain gliomas (n = 150). The patients were randomly assigned to training (n = 240), testing (n = 73), calibration (n = 96), and validation (n = 71) groups. And a CNN-implemented deep learning model guided by clinical experts was developed to identify the contrast-enhanced T1-weighted sequence lesions of these four diseases. We utilized accuracy, sensitivity, specificity, and area under the curve (AUC) to evaluate the performance of the CNN model. The model's performance was then compared to the neuroradiologists' diagnosis. Results: The CNN model had a total accuracy of 87% which was higher than senior neuroradiologists (74%), and the AUC of TDLs, PCNSL, TPACNS and gliomas were 0.92, 0.92, 0.89 and 0.88, respectively. Conclusion: The CNN model can accurately identify specific radiographic features of TDLs, TPACNS, PCNSL, and gliomas. It has the potential to be an effective auxiliary diagnostic tool in the clinic, assisting inexperienced clinicians in reducing diagnostic bias and improving diagnostic efficiency.

Central nervous system tumefactive demyelinating lesions: Risk factors of relapse and follow-up observations.

Objective: To track the clinical outcomes in patients who initially presented with tumefactive demyelinating lesions (TDLs), we summarized the clinical characteristics of various etiologies, and identified possible relapse risk factors for TDLs. Methods: Between 2001 and 2021, 116 patients initially presented with TDLs in our hospital were retrospectively evaluated. Patients were followed for relapse and clinical outcomes, and grouped according to various etiologies. Demographic information, clinical data, imaging data, and laboratory results of patients were obtained and analyzed. The risk factors of relapse were analyzed by the Log-Rank test and the Cox proportional hazard model in multivariate analysis. Result: During a median follow-up period of 72 months, 33 patients were diagnosed with multiple sclerosis (MS), 6 patients with Balo, 6 patients with neuromyelitis optica spectrum disorders (NMOSD), 10 patients with myelin oligodendrocyte glycoprotein antibody-associated demyelination (MOGAD), 1 patient with acute disseminated encephalomyelitis (ADEM), and the remaining 60 patients still have no clear etiology. These individuals with an unknown etiology were categorized independently and placed to the other etiology group. In the other etiology group, 13 patients had recurrent demyelinating phases, while 47 patients did not suffer any more clinical events. Approximately 46.6% of TDLs had relapses which were associated with multiple functional system involvement, first-phase Expanded Disability Status Scale score, lesions morphology, number of lesions, and lesions location (P<0.05). And diffuse infiltrative lesions (P=0.003, HR=6.045, 95%CI:1.860-19.652), multiple lesions (P=0.001, HR=3.262, 95%CI:1.654-6.435) and infratentorial involvement (P=0.006, HR=2.289, 95%CI:1.064-3.853) may be independent risk factors for recurrence. Relapse free survival was assessed to be 36 months. Conclusions: In clinical practice, around 46.6% of TDLs relapsed, with the MS group showing the highest recurrence rate, and lesions location, diffuse infiltrative lesions, and multiple lesions might be independent risk factors for relapse. Nevertheless, despite extensive diagnostic work and long-term follow-up, the etiology of TDLs in some patients was still unclear. And these patients tend to have monophase course and a low rate of relapse.

Neuroimaging and clinicopathological differences between tumefactive demyelinating lesions and sentinel lesions of primary central nervous system lymphoma.

Objective: It is still a challenge to distinguish sentinel lesions of primary central nervous system lymphoma (PCNSL) from atypical tumefactive demyelinating lesions (TDLs) in clinical practice. We aimed to investigate potential differences of clinical features, neuroimaging findings and pathological characteristics between PCNSL and TDLs, improving early accurate diagnosis. Methods: It was a retrospective study involving 116 patients with TDLs and 150 patients with PCNSLs. All cases were pathologically confirmed. Clinical features, neuroimaging findings and pathological characteristics between two groups were analyzed. Results: The onset age was 37 ± 14 years in TDLs and 58 ± 13 years in PCNSL(p=0.000). Main onset symptom was headache in TDLs, while cognitive impairment was frequently noted in PCNSL. CT brain scan image showed hypodense lesions in most cases of TDL (110/116, 94.8%), while approximately 80% patients (120/150) with PCNSL had hyperdense lesions. Furthermore, we found that the presence of Creutzfeldt-Peters cells (might be misdiagnosed as tumor cells) may serve as an important feature in TDLs. Conclusions: Onset age of patients with TDLs was younger than PCNSL. Neuroimaging features on brain CT scan might provide clues to make a differential diagnosis. Pathological features of PCNSL with sentinel lesions or following steroids therapy might mimic TDLs. Dynamic neuroimaging pathological and follow-up information were essential for an accurate diagnosis.

COVID-19 pandemic impacts on the elderly: the relationship between PPPD and prefrontal alpha rhythm.

BACKGROUND: In the COVID-19 epidemic more patients presented with persistent postural-perceptual dizziness (PPPD), but it has received little attention by the doctors in China and many patients reject psychological measurements or scales. Therefore, there is an urgent need for an objective method to diagnose and evaluate PPPD. OBJECTIVE: To investigate the effect of the COVID-19 epidemic on elderly PPPD patients and define the relationship between prefrontal alpha rhythm asymmetry (FAA) by Electroencephalography (EEG) and PPPD. METHODS: This case-control study was conducted to discuss the differences of elderly outpatients (>60 years) with PPPD during the peak period of COVID-19 in 2020 and the corresponding period in 2019, and collect the prefrontal FAA value in PPPD during COVID-19 outbreak, which were compared to its FAA in healthy control. RESULTS: Compared with the same period in 2019, the number of elderly PPPD patients during the epidemic period in 2020 increased significantly (16.4%, p = 0.000, x2 =31.802) . The left alpha wave signal power (F3) was significantly higher than the right alpha wave signal power (F4) (Z= -3.073, p = 0.002). In PPPD patients FAA were significantly lower in patients compared to control group (Z = -11.535, p = 0.000). There was a negative correlation between FAA and HAMA scores (R2 =0.906, p < 0.05) and a negative correlation between FAA and HAMD scores (R2 =0.859, p < 0.05), too. CONCLUSIONS: The increase in cases of elderly PPPD patients is most likely attributed to the mental health in older adults during the COVID-19 pandemic. Less left frontal brain activity in EEG may be related to elderly PPPD.

Efficacy of Pharmaceutical Care in Patients with Type 2 Diabetes Mellitus and Hypertension: A Randomized Controlled Trial.

Background: The rates of treatment adherence and treat-to-target rates of blood pressure and blood glucose-related indexes in patients with hypertension and type 2 diabetes mellitus (T2DM) are associated with prognosis. This study aimed to investigate the efficacy of pharmaceutical care postdischarge for treatment adherence in hypertensive patients with type 2 diabetes mellitus (T2DM). Methods: This was a randomized controlled trial of patients with combined T2DM and hypertension treated between January and May 2018. Pharmaceutical care included free access to a clinical pharmacist, education material, a WeChat account for live discussion, and a telephone follow-up. The primary endpoint was the 3-month medication adherence. The secondary endpoints included the achieving levels of target rates and values of fasting plasma glucose (FPG), 2 h postprandial glucose (2hPG), and hemoglobin A1c (HbA1c) and the rates of reaching the achieving target rate of blood pressure target <130/80. Results: In 80 participants, the 3-month medication adherence was higher in the pharmaceutical care group than the routine group (90.0% vs. 52.5%, P < 0.001). In terms of FPG, 2hPG, and HbA1c, there were also significant differences between the pharmaceutical care and routine groups (FPG, 6.50 (6.00, 7.18) vs. 7.00 (6.83, 7.78) mmol/L, P=0.004; 2hPG, 8.45 (7.45, 9.28) vs. 9.35 (8.23, 10.15), P=0.007; HbA1c, 6.5% (6.3%, 7.0%) vs. 7.0% (6.5%, 7.4%), P=0.007). The achieving target rate of reaching the blood pressure target in the pharmaceutical care group (92.5%) was significantly higher than that in the routine group (62.5%; P < 0.05). Conclusion: The postdischarge pharmaceutical care program in patients with T2DM and hypertension improves medication adherence.

Regulatory B Cells Are Decreased and Functionally Impaired in Myasthenia Gravis Patients.

Myasthenia gravis (MG) is an autoimmune disease mediated by B cells secreting autoantibodies. Regulatory B (Breg) cells confirmed to have an immunosuppressive function play an important role in many autoimmune diseases. However, what about the changes in Breg cells in the thymus and peripheral blood of MG patients? The changes in the proportion of Breg cells in the peripheral blood of 41 MG patients without any drug treatment and 30 healthy controls were detected by flow cytometry. We found that the proportions of CD19+ IL-10+ cells and CD19+CD24hiCD38hi cell subsets in MG patients were significantly lower than those in healthy controls. Then, we detected the proportion of CD19+ IL-10+ cells in thymus tissues of 10 healthy children, 4 healthy adults, and 12 MG patients by flow cytometry. However, the percentage of CD19+ IL-10+ cells was highest in healthy children (~8%), followed by healthy adults (~3%), and was lowest in MG patients (~0.5%). CD19+CD24hiCD38hi B cells exerted immunosuppressive functions in healthy people but were refractory in MG patients. Moreover, p-STAT3 downstream of CD40 may be impaired in CD24hiCD38hi B cells from the peripheral blood of MG patients.

The role of the microRNA regulatory network in Alzheimer's disease: a bioinformatics analysis.

INTRODUCTION: Alzheimer's disease (AD) is a neurodegenerative disease which presents with an earlier age of onset and increased symptom severity. The objective of this study was to evaluate the relationship between regulation of miRNAs and AD. MATERIAL AND METHODS: We completed a bioinformatic analysis of miRNA-AD studies through multiple databases such as TargetScan, Database for Annotation, Visualization and Integrated Discovery (DAVID), FunRich and String and assessed which miRNAs are commonly elevated or decreased in brain tissues, cerebrospinal fluid (CSF) and blood of AD patients. All identified articles were assessed using specific inclusion and exclusion criteria. RESULTS: MiRNAs related to AD of twenty-eight studies were assessed in this study. A wide range of miRNAs were up-regulated or down-regulated in tissues of AD patients' brain, blood and CSF. Twenty-seven differentially dysregulated miRNAs involved in amyloidogenesis, inflammation, tau phosphorylation, apoptosis, synaptogenesis, neurotrophism, neuron degradation, and activation of cell cycle entry were identified. Additionally, our bioinformatics analysis identified the top ten functions of common miRNAs in candidate studies. The functions of common up-regulated miRNAs primarily target the nucleus and common down-regulated miRNAs primarily target transcription, DNA-templated. CONCLUSIONS: Comprehensive analysis of all miRNA studies reveals cooperation in miRNA signatures whether in brain tissues or in CSF and peripheral blood. More and more studies suggest that miRNAs may play crucial roles as diagnostic biomarkers and/or as new therapeutic targets in AD. According to biomarkers, we can identify the preclinical phase early, which provides an important time window for therapeutic intervention.

Application Effect of the Standard Operating Procedure in the Prevention of Venous Thromboembolism.

OBJECTIVE: To investigate the application effect of the standard operating procedure (SOP) in the prevention of venous thromboembolism (VTE). METHODS: The clinical data of patients admitted to respiratory, cardiovascular, neurological, and geriatric departments in the hospital (November 2020-May 2021) were retrospectively analyzed, and the patients in line with the inclusion criteria were equally randomized into the observation group (OG) and the control group (CG). The CG was treated with the routine nursing, and the OG received the SOP of VTE prevention additionally. After the record of the incidence of VTE and nursing satisfaction of the two groups, scores of VTE awareness were compared. RESULTS: One hundred and twenty patients were included in this study, and no obvious difference was found in the general data of patients (P > 0.05). Compared with the CG, the incidence of VTE of the OG was obviously lower (P < 0.05). After nursing, compared with the CG, scores of VTE awareness in the OG were conspicuously higher (P < 0.001), and scores of VTE awareness of the nursing staff were conspicuously higher than those before nursing (P < 0.001). Compared with the CG, nursing satisfaction of the OG was obviously higher (P < 0.001). CONCLUSION: SOP can reduce the incidence of VTE of patients, improve their disease awareness, and enhance their nursing satisfaction, which should be popularized in practice.

Acute-onset paraneoplastic cerebellar degeneration secondary to neuroendocrine carcinoma with atypical prognosis: a case report.

Paraneoplastic cerebellar degeneration (PCD) is a neurological syndrome that is likely caused by tumor-induced autoimmunity against the cerebellum. Neuroendocrine carcinoma (NEC) is a type of neoplasm with high-grade malignant histology and biological behavior. The prognosis for both PCD and NEC is typically poor. We report a case of PCD secondary to metastatic NEC in the lymph nodes, with an unknown primary origin. The case presented acute cerebellar manifestations with typical neuroimaging findings, but with atypical prognosis after lymph node dissection. Neurological symptoms can provide clues to potential tumors, and early antitumor treatment may have contributed to the positive prognosis of PCD secondary to NEC in the present case.

Differential value of external anal- and urethral-sphincter electromyography in multiple system atrophy cerebellar type and spinocerebellar ataxias.

OBJECTIVE: Clinically differentiating multiple system atrophy cerebellar type (MSA-C) and spinocerebellar ataxias (SCAs) is challenging, especially at early disease stages, because of their similarities in clinical manifestation and imaging results. The purpose of this study was to explore the value of external anal-sphincter electromyography (EAS-EMG) and urethral-sphincter electromyography (US-EMG) for distinguishing between MSA-C and SCAs. METHODS: A total of 51 subjects, including 33 MSA-C and 18 SCAs, were recruited. Average duration and amplitude of motor unit potentials (MUPs), percentage of polyphasic MUPs, amplitude during strong contraction and recruitment pattern during maximal voluntary contraction were recorded and analyzed to identify differential diagnostic results of EAS-EMG and US-EMG for MSA-C and SCAs. RESULTS: Significant differences in average MUP duration, percentage of polyphasic MUPs, and ratio of simple phase and simple-mix phase using EAS-EMG were noted between patients with MSA-C and SCAs. These same parameters also differed significantly between MSA-C and SCAs male patients using US-EMG. CONCLUSIONS: EAS-EMG may serve as a potential method for early differential diagnosis between patients with MSA-C and SCAs. Furthermore, US-EMG could be a supplementary method for males when EAS-EMG is not available.

Expanded teased nerve fibre pathological conditions in disease association.

OBJECTIVE: To describe an expanded teased nerve fibre classification in disease association. METHODS: We reviewed four newly proposed teased nerve fibre types (Types J-M): Type J, rope-like fibres; K, fibril-like clumps of osmium positivity; L, cellular debris along and within nerve fibres; M, circular axonal inclusions surrounded by thin myelin. Different clinical pathological entities were studied for these fibre types including chronic inflammatory demyelinating polyradiculoneuropathy (CIDP: N=20); amyloid polyneuropathy (N=20); intraneural B-cell lymphoma (N=20) or adult-onset polyglucosan body disease (APBD: N=6) in comparison with 112 disease controls. Student's t-test was used to test significance of association between the identified fibre types and the specific clinical diagnosis. RESULTS: Each fibre type significantly associated (p<0.001) with particular disease categories: Type J, 60% of CIDP cases; Type K, 75% of amyloid cases; Type L, 75% of intraneural lymphoma cases; Type M, 100% of APBD cases. Rarely were these fibres found in the other disease control cases ≤3% of cases. In three cases, the teased fibre findings were so striking additional paraffin nerve preparations were made to make the pathological diagnosis when initial paraffin sections were non-diagnostic. CONCLUSIONS: Teased nerve fibre Types J-M associate with commonly seen pathological diagnosis and are helpful in the consideration of specific neuropathy diagnoses.

Evaluation of Problem- and Simulator-Based Learning in Lumbar Puncture in Adult Neurology Residency Training.

BACKGROUND: Lumbar puncture (LP) is an essential part of adult neurology residency training. Technologic as well as nontechnologic training is needed. However, current assessment tools mostly focus on the technologic aspects of LP. We propose a training method-problem- and simulator-based learning (PSBL)-in LP residency training to develop overall skills of neurology residents. METHODS: We enrolled 60 neurology postgraduate-year-1 residents from our standardized residents training center and randomly divided them into 2 groups: traditional teaching group and PSBL group. After training, we assessed the extent that the residents were ready to perform LP and tracked successful LPs performed by the residents. We then asked residents to complete questionnaires about the training models. Performance scores and the results of questionnaires were compared between the 2 groups. RESULTS: Students and faculty concluded that PSBL provided a more effective learning experience than the traditional teaching model. Although no statistical difference was found in the pretest, posttest, and improvement rate scores between the 2 groups, based on questionnaire scores and number of successful LPs after training, the PSBL group showed a statistically significant improvement compared with the traditional group. Findings indicated that nontechnical elements, such as planning before the procedure and controlling uncertainties during the procedure, are more crucial than technical elements. CONCLUSIONS: Compared with traditional teaching model, PSBL for LP training can develop overall surgical skills, including technical and nontechnical elements, improving performance. Residents in the PSBL group were more confident and effective in performing LP.

Effect of problem and scripting-based learning on spine surgical trainees' learning outcomes.

PURPOSE: To assess the impact of problem and scripting-based learning (PSBL) on spine surgical trainees' learning outcomes. METHODS: 30 spine surgery postgraduate-year-1 residents (PGY-1s) from the First Hospital of China Medical University were randomly divided into two groups. The first group studied spine surgical skills and developed individual judgment under a conventional didactic model, whereas the PSBL group used PBL and Scripted model. A feedback questionnaire and the satisfaction of residents were evaluated by the first assistant surgeon immediately following each procedure. At the end of the study, residents filled out questionnaires focused on identifying the strengths of each teaching method and took a multiple-choice theoretical examination. The results were analyzed by t tests. RESULTS: Significant difference was found between the two groups in total mean score of preparedness and performance feedback statement (P = 0.01) and the questionnaire by PGY-1's opinion on the effectiveness of the two teaching methods (P = 0.004). Compared with the non-PSBL group, the PSBL group had significantly higher mean score of pre-operative preparedness (P = 0.01), but there was no significant difference between the two groups in theoretical examination, intra-operative performance, and overall satisfaction with the PGY-1s. The residents found that PSBL could develop their judgment (P = 0.03) and provide greater satisfaction (P = 0.02), and would like to repeat the experience (P = 0.03). CONCLUSIONS: The PSBL method can activate spine residents' prior knowledge and building on existing cognitive frameworks, which is an important tool for improving pre-operative preparedness. We believe that PSBL is an important first step in training spine residents to become confident and safe spine surgeons.

Study on Emission Spectrum of OH Radicals in a Combination System of Pulsed Discharge Plasma and Activated Carbon.

Based on the higher oxidation potential of OH radicals (2.8 V), the synergetic effect of pulsed discharge plasma (PDP) and activated carbon (AC) and the advantages of emission spectroscopic detection, such as easy operation, high accuracy and high sensitivity, the relative emission spectra of the OH radicals generated in the PDP/AC system with oxygen flow were measured by the emission spectroscopic detection technique and the spectral intensity of the OH radicals was used to represent the relative amount of the OH radicals formed in the reaction system. The effect of additive amount of the AC, peak pulse voltage and electrode gap on the relative emission spectrum intensities of OH radicals were investigated to illustrate the crucial factors for the OH radicals formation in the PDP/AC system. In addition, the formation of OH radicals in the two liquid phases of distilled water and acid orange 7 (AO7) solution in the sole PDP system and the PDP/AC system were investigated to testify the synergetic mechanism of PDP/AC and the oxidization of OH radicals on the organic compounds in the reaction system. The obtained results showed that the catalytic effect of the AC increased with the increase of the additive amount of the AC in the PDP system, which led to the increase of the relative emission spectral intensities of the formed OH radicals in the synergistic system; higher peak pulse voltage was in favor of the energy input in the discharge system and then enhanced the formation of OH radicals; increase of the electrode gap led to the decrease of energy efficiency in the reaction system and the decrease of the formed OH radicals in the PDP/AC system; the formation of OH radicals in the PDP/AC system was higher than that in the sole PDP system both in the distilled water and in the AO7 solution; the formation of OH radicals in the distilled water was higher than those in the AO7 solution no matter the reaction system was the sole PDP system or the PDP/AC system. The two results indicated that the AC addition was beneficial to the formation of OH radicals in the PDP system and the OH radicals had an important effect on the organic compounds degradation both in the sole PDP system and in the PDP/AC system.

Expression and refolding of bioactive α-bungarotoxin V31 in E. coli.

In order to obtain bioactive α-bungarotoxin (αBtx) using recombinant protein technique, a codon-optimized synthetic gene was expressed in fusion with the N-terminal 10-His-tag and C-terminal Strep-tag in Escherichia coli. Further optimization through site-directed mutagenesis enabled moderate expression of the protein without the N-terminal His-tag or the C-terminal Strep-tag. Two such recombinant αBtx (rαBtx) were obtained, both with an additional methionine and a glycine at the N-terminal and one with (G4S1)2-Strep-tag at the C-terminal. The rαBtx proteins were refolded using a novel protocol, which efficiently produced final products with activity similar to its natural counterpart. The protocol could easily be scale up, which produced 0.3-1mg of pure and highly active rαBtx per liter of E. coli culture.

Improved methodology to obtain large quantities of correctly folded recombinant N-terminal extracellular domain of the human muscle acetylcholine receptor for inducing experimental autoimmune myasthenia gravis in rats.

INTRODUCTION: Human myasthenia gravis (MG) is an autoimmune disorder of the neuromuscular system. Experimental autoimmune myasthenia gravis (EAMG) is a well-established animal model for MG that can be induced by active immunization with the Torpedo californica-derived acetylcholine receptor (AChR). Due to the expensive cost of purifying AChR from Torpedo californica, the development of an easier and more economical way of inducing EAMG remains critically needed. MATERIAL AND METHODS: Full-length cDNA of the human skeletal muscle AChR α1 subunit was obtained from TE671 cells. The DNA fragment encoding the extracellular domain (ECD) was then amplified by polymerase chain reaction (PCR) and inserted into pET-16b. The reconstructed plasmid was transformed into the host strain BL21(DE3)pLysS, which was derived from Escherichia coli. Isopropyl-ß-D-thiogalactopyranoside (IPTG) was used to induce the expression of the N-terminal ECD. The produced protein was purified with immobilized Ni(2+) affinity chromatography and refolded by dialysis. RESULTS: The recombinant protein was efficiently refolded to soluble active protein, which was verified by ELISA. After immunization with the recombinant ECD, all rats acquired clinical signs of EAMG. The titer of AChR antibodies in the serum was significantly higher in the EAMG group than in the control group, indicating successful induction of EAMG. CONCLUSIONS: We describe an improved procedure for refolding recombinant ECD of human muscle AChR. This improvement allows for the generation of large quantities of correctly folded recombinant ECD of human muscle AChR, which provides for an easier and more economical way of inducing the animal model of MG.