Differentially expressed circRNA and functional pathways in the hippocampus of epileptic mice based on next-generation sequencing.

Epilepsy is a clinical syndrome caused by the highly synchronized abnormal discharge of brain neurons. It has the characteristics of paroxysmal, transient, repetitive, and stereotyped. Circular RNAs (circRNAs) are a recently discovered type of noncoding RNA with diverse cellular functions related to their excellent stability; additionally, some circRNAs can bind and regulate microRNAs (miRNAs). The present study was designed to screen the differentially expressed circRNA in an acute seizure model of epilepsy in mice, analyze the related miRNA and mRNA, and study their participating functions and enrichment pathways. In order to obtain the differential expression of circRNA in epilepsy and infer their function, we used next-generation sequencing and found significantly different transcripts. CIRI (circRNA identifier) software was used to predict circRNA from the hippocampus cDNA, EdgeR was applied for the differential circRNA analysis between samples, and Cytoscape 3.7.2 software was used to draw the network diagram. A total of 10,388 differentially expressed circRNAs were identified, of which 34 were upregulated and 66 were downregulated. Among them, mm9_circ_008777 and mm9_circ_004424 were the key upregulated genes, and their expression in the epilepsy group was verified using Quantitative real-time PCR (QPCR). The analysis indicated that the extracted gene ontology terms and Kyoto Encyclopedia of Genes and Genomes pathways were closely related to several epilepsy-associated processes. This study determined that mm9_circ_008777 and mm9_circ_004424 are potential biomarkers of epilepsy, which play important roles in epilepsy-related pathways. These results could help improve the understanding of the biological mechanisms of circRNAs and epilepsy treatments.

[Preparation of a novel targeted MR contrast agent Gd-DTPA-streptavidin and exploration of its reaction conditions].

OBJECTIVE: To explore the optimal reaction condition of DTPA-coupled streptavidin labeled with gadolinium ion. METHODS: The number streptavidin-coupled of gadolinium ions and maximum biotin-binding capacity of Gd-DTPA-SA complex were analyzed at different DTPA-to-SA molar ratios (1000, 500, 200, 100) and in buffer solutions of different pH values (pH 5, 6, 7, and 8, respectively). RESULTS: The number of streptavidin-coupled gadolinium ions increased with the pH value of the reaction system. When the DTPA-to-SA molar ratio was below 500, the number of gadolinium ions that SA-DTPA coupled increased with the DTPA-to-SA molar ratio, but tended to decrease when the ratio was 1,000. No significant difference in the maximum biotin-binding capacity of Gd-DTPA-SA complex was noted between the groups. CONCLUSIONS: The number of gadolinium ions that streptavidin coupled depends on the pH value of the reaction system and DTPA-to-SA molar ratio, but the maximum biotin-binding capacity of Gd-DTPA-SA complex is not affected by the reaction conditions.

[Magnetic resonance imaging enhanced by superparamagnetic iron oxide particles in detecting lymph node metastasis of tumors: an experimental study].

OBJECTIVE: To investigate the value of superparamagnetic iron oxide particles (SPIO) in magnetic resonance (MR) imaging for detecting lymph node metastasis of tumors. METHODS: Twelve New Zealand rabbits were used in this study, 6 of which received unilateral intra-muscular inoculation of VX2 carcinoma cells to induce lymph node metastasis of the tumor, and the other 6 served as normal control group. MR images of the lymph nodes of the rabbits were obtained before and 12 h after subcutaneous injection of SPIO, followed by image analysis in correlation with pathological examinations. RESULTS: On plain MR images, normal and metastatic lymph nodes showed similar signal characteristics. After administration of SPIO, the signal intensity of both normal lymph nodes and metastatic ones remained unchanged in spin echo (SE) T1-weighted images. On SE T2-weighted images, the signal intensity of normal lymph nodes significantly decreased heterogeneously, while that of all metastatic lymph nodes remained unchanged. In gradient recalled echo (GRE) T2-weighted images, the signal intensity of normal lymph nodes decreased significantly and homogeneously, while that of 4 rabbits in metastasis group remained unchanged, with the signal intensity in the other 2 rabbits decreased heterogeneously. CONCLUSION: SPIO-enhanced MR imaging can be applied to detect lymph node metastasis of the tumors.

[Superparamagnetic iron oxide-enhanced magnetic resonance imaging of hepatocellular carcinoma in rats].

OBJECTIVE: To evaluate the value of superparamagnetic iron oxide (SPIO)-enhanced magnetic resonance (MR) imaging in the diagnoses of focal liver lesions. METHODS: Twenty rat models of hepatocellular carcinoma were induced by feeding the rats with N-nitrosodiethylamine. Before and after SPIO injection into the rats, MR imaging was performed including the sequences of spin-echo (SE) T1WI (390 ms/14 ms), TSE T2WI (4 100 ms/99 ms), SE Dual-echoes (1 800 ms/20 ms/70 ms), GRE FLASH T2*WI (600 ms/15 ms/15 ), and GRE FLASH T1WI (150 ms/14 ms/70 ). Another 5 normal rats were selected as negative control, which also received SPIO and MR imaging in the same manner as described above. The characteristics of SPIO-enhanced MRI of different liver lesions were analyzed. RESULTS: After SPIO enhancement, the signal intensity of normal liver and cirrhotic liver both decreased, especially on GRE T2*WI. The signal intensity of hepatocellular carcinoma (HCC), regenerative nodules (RN), and focal nodule hyperplasia (FNH) all increased on T1WI images. On T2WI and T2*-weighted images, the signal intensity of HCC remained high, while significant signal loss occurred in RN and FNH. After SPIO administration, the contrast-to-noise (CNR) of HCC on GRE T2*-weighted images was greater than that of other sequences. CONCLUSION: SPIO has not only considerable T2-negative effect but also slightly T1-shortening effect, which is of great value in the differential diagnosis of focal liver lesions.