Impact of field heterogeneity on the dynamics of the forced Kuramoto model

We studied the impact of field heterogeneity on entrainment in a system of uniformly interacting phase oscillators. Field heterogeneity is shown to induce dynamical heterogeneity in the system. In effect, the heterogeneous field partitions the system into interacting groups of oscillators that feel the same local field strength and phase. Based on numerical and analytical analysis of the explicit dynamical equations derived from the periodically forced Kuramoto model, we found that the heterogeneous field can disrupt entrainment at different field frequencies when compared to the homogeneous field. This transition occurs when the phase- and frequency-locked synchronization between groups of oscillators is broken at a critical field frequency, causing each group to enter a new dynamical state (disrupted state). Strikingly, it is shown that disrupted dynamics can differ between groups.

Empirical assessment of biases in cerebrospinal fluid biomarkers of Alzheimer's disease: an umbrella review and re-analysis of data from meta-analyses

OBJECTIVE

Alzheimer's disease (AD) is a leading cause of years lived with disability in older age, and several cerebrospinal fluid (CSF) markers have been proposed in individual meta-analyses to be associated with AD but field-wide evaluation and scrutiny of the literature is not available.

MATERIALS AND METHODS

We performed an umbrella review for the reported associations between CSF biomarkers and AD. Data from available meta-analyses were reanalyzed using both random and fixed effects models. We also estimated between-study heterogeneity, small-study effects, excess significance, and prediction interval.

RESULTS

A total of 38 meta-analyses on CSF markers from 11 eligible articles were identified and reanalyzed. In 14 (36%) of the meta-analyses, the summary estimate and the results of the largest study showed non-concordant results in terms of statistical significance. Large heterogeneity (I2≥75%) was observed in 73% and small-study effects under Egger's test were shown in 28% of CSF biomarkers.

CONCLUSIONS

Our results suggest that there is an excess of statistically significant results and significant biases in the literature of CSF biomarkers for AD. Therefore, the results of CSF biomarkers should be interpreted with caution.

Direct Reprogramming Induces Vascular Regeneration Post Muscle Ischemic Injury

Reprogramming non-cardiomyocytes (non-CMs) into cardiomyocyte (CM)-like cells is a promising strategy for cardiac regeneration in conditions such as ischemic heart disease. Here, we used a modified mRNA (modRNA) gene delivery platform to deliver a cocktail, termed 7G-modRNA, of four cardiac-reprogramming genes—Gata4 (G), Mef2c (M), Tbx5 (T), and Hand2 (H)—together with three reprogramming-helper genes—dominant-negative (DN)-TGFβ, DN-Wnt8a, and acid ceramidase (AC)—to induce CM-like cells. We showed that 7G-modRNA reprogrammed 57% of CM-like cells in vitro. Through a lineage-tracing model, we determined that delivering the 7G-modRNA cocktail at the time of myocardial infarction reprogrammed ∼25% of CM-like cells in the scar area and significantly improved cardiac function, scar size, long-term survival, and capillary density. Mechanistically, we determined that while 7G-modRNA cannot create de novo beating CMs in vitro or in vivo, it can significantly upregulate pro-angiogenic mesenchymal stromal cells markers and transcription factors. We also demonstrated that our 7G-modRNA cocktail leads to neovascularization in ischemic-limb injury, indicating CM-like cells importance in other organs besides the heart. modRNA is currently being used around the globe for vaccination against COVID-19, and this study proves this is a safe, highly efficient gene delivery approach with therapeutic potential to treat ischemic diseases.

POS1413 INTERVAL BETWEEN SYMPTOM ONSET AND DIAGNOSIS AMONG PATIENTS WITH AUTOIMMUNE RHEUMATIC DISEASES IN A MULTI-ETHNIC ASIAN POPULATION

Background:

The interval between symptom onset and diagnosis can often be longer than is ideal in autoimmune rheumatic diseases (ARDs).

Objectives:

We aimed to characterise this interval among patients newly diagnosed with ARDs in a multi-ethnic Asian population and to identify factors associated with a longer interval.

Methods:

We used Scott’s model of pathways to treatment to characterise the interval between symptom onset and diagnosis into 4 intervals: #1 between symptom onset and first seeking medical attention, #2 between first medical attention and rheumatology referral, #3 between rheumatology referral and first rheumatology assessment, and #4 between first rheumatology assessment and diagnosis. Linear regression models were used to identify factors associated with a longer the overall interval between symptom onset and diagnosis and Interval #1.

Results:

Among 259 patients (age: 51±15 years, female: 71%, most common three ARDs: rheumatoid arthritis (n = 75), axial spondyloarthritis (n = 40) and psoriatic arthritis (n = 35)), the median overall interval was 11.5 months. Interval #1 (median = 4.9 months) was significantly longer than the other intervals (Table 1). Patients with axial spondyloarthritis had a significantly longer overall interval (median = 38.7 months) and Interval #1 (median = 26.6 months) compared to patients with RA (median = 7.6 and 3.5 months, respectively), PsA (median = 7.0 and 2.6 months, respectively) and the other ARDs. Gender was the only patient-related factor significantly associated with the overall interval (reference = male, coefficient = -15.3, p = 0.033) in regression models.

Conclusion:

A longer than ideal interval between symptom onset and diagnosis was observed among patients with ARDs. This was primarily due to a relatively long interval between symptom onset and first seeking medical attention, and highlights the importance of interventions targeting patients prior to first medical attention in reducing the duration between symptom onset and diagnosis.

References:

[1]Scott SE, Walter FM, Webster A, Sutton S, Emery J. The model of pathways to treatment: conceptualization and integration with existing theory. Br J Health Psychol. 2013;18(1):45-65.

Table 1.

Interval between symptom onset and diagnosis

Overall interval, months, median (lower and upper quartiles)†Interval #1, months, median (lower and upper quartiles)Interval #2, months, median (lower and upper quartiles)Interval #3, months, median (lower and upper quartiles)Interval #4, months, median (lower and upper quartiles)Overall(n = 259)11.5(4.7 – 36.0)4.9(1.0 – 24.0)0.3(0.0 – 3.9)1.5(0.8 – 1.8)0.0(0.0 – 1.2)RA(n = 75)7.6(3.1 – 14.8)3.5(1.3 – 11.6)0.2(0.0 – 2.5)1.3(0.6 – 1.6)0.0(0.0 – 0.2)AxSpA(n = 40)38.7(9.6 – 66.7)26.6(4.2 – 56.1)1.6(0.0 – 7.6)1.6(1.2 – 2.3)0.0(0.0 – 2.0)PsA(n = 35)7.0(3.0 – 28.4)2.6(0.2 – 11.3)0.5(0.2 – 3.9)1.6(0.6 – 1.7)0.0(0.0 – 0.0)Seronegative IA(n = 21)12.0(4.7 – 22.8)6.4(1.9 – 34.4)0.1(0.0 – 4.6)1.4(1.3 – 1.5)0.0(0.0 – 0.8)SjS(n = 27)14.2(6.0 – 48.0)4.6(0.6 – 19.0)0.3(0.0 – 3.9)1.6(0.9 – 1.9)0.8(0.0 – 2.3)UCTD(n = 27)15.7(5.1 – 39.8)2.2(0.7 – 24.0)0.8(0.1 – 8.1)1.6(0.5 – 1.8)1.2(0.0 – 2.1)Other ARDs(n = 34)8.1(5.3 – 36.0)6.3(0.9 – 31.7)0.2(0.0 – 1.1)1.5(1.2 – 1.8)0.3(0.0 – 1.1)

Overall interval and Intervals #1-4: refer to abstract for definitions; RA: rheumatoid arthritis; axSpA: axial spondyloarthritis; PsA: psoriatic arthritis; IA: inflammatory arthritis; SjS: Sjögren’s syndrome; UCTD: undifferentiated connective tissue disease; other ARDs: systemic lupus erythematosus, systemic sclerosis, idiopathic inflammatory myopathies, palindromic rheumatism and overlap syndromes.

†Intervals #1-4 did not sum to the overall interval mainly due to the fact that Intervals #1-4 might not available for all patients.

Disclosure of Interests:

None declared

Virtual reality as a learning tool in spinal anatomy and surgical techniques

Background

Surgical simulation is a valuable educational tool for trainees to practice in a safe, standardized, and controlled environment. Interactive feedback-based virtual reality (VR) has recently moved to the forefront of spine surgery training, with most commercial products focusing on instrumentation. There is a paucity of learning tools directed at decompression principles. The purpose of this study was to evaluate the efficacy of VR simulation and its educational role in learning spinal anatomy and decompressive techniques.

Methods

A VR simulation module was created with custom-developed software. Orthopaedic and neurosurgical trainees were prospectively enrolled and interacted with patient-specific 3D models of lumbar spinal stenosis while wearing a headset. A surgical toolkit allowed users to perform surgical decompression, specifically removing soft tissues and bone. The module allowed users to perform various techniques in posterior decompressions and comprehend anatomic areas of stenosis. Pre- and post-module testing, and utility questionnaires were administered to provide both quantitative and qualitative evaluation of the module as a learning device.

Results

28 trainees were enrolled (20-orthopaedic, 8-neurosurgery) in the study. Pre-test scores on anatomic knowledge progressively improved and showed strong positive correlation with year-in-training (Pearson's r = 0.79). Following simulation, the average improvement in post-test scores was 11.4% in junior trainees (PGYI-III), and 1.0% in senior trainees (PGYIII-Fellows). Knowledge improvement approached statistical significance amongst junior trainees (p = 0.0542). 89% of participants found the VR module useful in understanding and learning the pathology of spinal stenosis. 71% found it useful in comprehending decompressive techniques. 96% believed it had utility in preoperative planning with patient-specific models.

Conclusions

Our original VR spinal decompression simulation has shown to be overwhelmingly positively received amongst trainees as both a learning module of patho-anatomy and patient-specific preoperative planning, with particular benefit for junior trainees.

P10.01 Anti-migration and anti-invasion effects of curcumin via suppression of fascin expression in glioblastoma cells

BACKGROUND

The natural compound Curcumin was known to inhibit migration and invasion of glioblastoma (GBM) cells. Fascin, a kind of actin-binding proteins, is correlated with migration and invasion of GBM cells. The purpose of this study was to investigate anti-migration and anti-invasion effects of Curcumin via suppression of fascin expression in GBM cells.

MATERIAL AND METHODS

U87 cell line was used as an experimental model of GBM. Fascin was quantified by Western blot analysis. And, the signal transducer and activator of transcription 3 (STAT3), known to play an important role in migration and invasion of tumor cells, were analyzed by sandwich-ELISA. Migration and invasion capacities were assessed by attachment, migration and invasion assays. Cellular morphology was demonstrated by immunofluorescence.

RESULTS

At various concentrations of curcumin and exposure times, fascin expression decreased. After temporarily exposure to 10μM/L Curcumin during 6 hours as less invasive concentration and time, fascin expression temporarily decreased at 12 hours (18.4%, p=0.024), and since then recovered. And, the change of phosphrylated STAT3 level also reflected the temporarily decreased pattern of fascin expression at 12 hours (19.7%, p=0.010). Attachment, migration, and invasion capacities consistently decreased at 6, 12, and 24 hours. And, immunofluorescence showed the change of shape and the reduction of filopodia formation in cells.

CONCLUSION

Curcumin is likely to suppress the fascin expression in GBM cells, and this might be a possible mechanism for anti-migration and anti-invasion effects of Curcumin via inhibition of STAT3 phosphorylation.

P14.27 The significance of multicentric noncontrast-enhancing lesions distant from surgically resected glioblastoma: Case series of 3 patients

BACKGROUND

Glioblastoma is the most malignant primary brain tumor. The tumor location and multiplicity plays an important role in surgical and further treatment. The incidence of multiple lesions at the time of diagnosis was known as 1–20%, which showed a poor prognostic factor. Most researches has focused on multiple contrast-enhancing lesions, however, multicentric non-enhancing lesions distant from glioblastoma has been rarely evaluated. The authors reported the case series of the patient who showed multicentric non contrast-enhancing lesions without connection to histologically-proven glioblastoma.

MATERIAL AND METHODS

Multicentric non contrast-enhancing lesions were defined as areas of FLAIR hyperintensity and mass effect without post-contrast enhancement, separated from the histologically-proven glioblastoma in a newly diagnosed disease. Three patients who showed distant non-enhancing lesions with appearance of a multicentric low-grade glioma were included in this study. The typical enhancing lesions were surgically resected and standard chemo-radiotherapy was followed in all patients.

RESULTS

All patients were male and their age was 38, 60 and 65 years old respectively. Multicentric tumor location was as follows: Case 1, left frontal lobe with non-enhancing lesion in left parahippocampal gyrus; Case 2, left parietal with non-enhancing lesion in left anteromedial temporal lobe; Case 3, left thalamus with non-enhancing lesions in both basal frontal and right temporal lobe. Pathologically, the resected enhancing tumor revealed glioblastoma in 2 patients and diffuse midline glioma in 1. All tumors were IDH-wild type. The resected enhanced lesion showed no progression but all non-enhancing lesions developed contrast-enhancing tumors at 3, 13 and 17 months after initial treatment, with high tracer uptake on 18FDG-PET or 18FDOPA-PET. Despite multidisciplinary treatment, two patients died from disease progression at 30 and 32 months after diagnosis and one patient is still alive with overall survival of 15 months.

CONCLUSION

The appearance of multicentric non-enhancing lesions distant from a typically enhancing tumor showed an uncommon finding in glioblastoma and poor prognostic features. These lesions progress faster than expected for a low-grade glioma. These lesions should be distinguished from typical low-grade glioma and should be considered more advanced lesions than their appearances suggest.