BACKGROUND:Studies have shown that there is a close association between spinal cord injury and ferroptosis,and that tetramethylpyrazine has the function of regulating redox reactions. OBJECTIVE:To investigate the regulatory effect of tetramethylpyrazine on ferroptosis in rats with spinal cord injury and its mechanism. METHODS:Thirty-six female specific pathogen-free Sprague-Dawley rats were randomly divided into sham-operated group,model group and tetramethylpyrazine group,with 12 rats in each group.Animal models of spinal cord injury were established using the modified Allen's method in the latter two groups.No treatment was given in the sham-operated group,while rats in the model and tetramethylpyrazine groups were given intraperitoneal injection of normal saline and tetramethylpyrazine solution,once a day,for 28 days. RESULTS AND CONCLUSION:The Basso,Beattie&Bresnahan Locomotor Rating Scale score in the tetramethylpyrazine group was lower than that in the sham-operated group but higher than that in the model group after 14,21,and 28 days of treatment(P＜0.05).After 28 days of treatment,hematoxylin-eosin staining showed that in the model group,the spinal cord tissue of rats showed cavity formation,necrotic tissue and inflammatory infiltration with fibrous tissue formation;in the tetramethylpyrazine group,the area of spinal cord tissue defects was smaller,and inflammatory infiltration and fibrous tissue formation were less than those in the model group.After 28 days of treatment,Prussian blue staining showed that a large amount of iron deposition was seen in the spinal cord tissue of rats in the model group,and less iron deposition was seen in the spinal cord tissue of rats in the tetramethylpyrazine group than in the model group.After 28 days of treatment,the levels of glutathione and superoxide dismutase in the rat spinal cord tissue were decreased(P＜0.05)and the level of malondialdehyde was increased in the model group compared with the sham-operated group(P＜0.05);the levels of glutathione and superoxide dismutase in the rat spinal cord tissue were increased(P＜0.05)and the level of malondialdehyde was decreased in the tetramethylpyrazine group compared with the model group(P＜0.05).After 28 days of treatment,qRT-PCR and western blot assay showed that the mRNA and protein levels of glutathione peroxidase 4,ferritin heavy chain,and ferroportin in the rat spinal cord tissue in the model group were decreased compared with those in the sham-operated group(P＜0.05),while the mRNA and protein levels of glutathione peroxidase 4,ferritin heavy chain,and ferroportin in the rat spinal cord tissue in the tetramethylpyrazine group were increased compared with those in the model group(P＜0.05).Immunofluorescence staining showed that after 28 days of treatment,the neuronal nuclei positive staining in the spinal cord of rats was the most in the sham-operated group and the least in the model group.To conclude,tetramethylpyrazine can improve motor function and play a neuroprotective role in rats with spinal cord injury by regulating ferroptosis.

Dynamic tracking analysis of monoclonal antibodies (mAbs) biotransformation in vivo is crucial, as certain modifications could inactivate the protein and reduce drug efficacy. However, a particular challenge (i.e. immune recognition deficiencies) in biotransformation studies may arise when modifications occur at the paratope recognized by the antigen. To address this limitation, a multi-epitope affinity technology utilizing the metal organic framework (MOF)@Au@peptide@aptamer composite material was proposed and developed by simultaneously immobilizing complementarity determining region (CDR) mimotope peptide (HH24) and non-CDR mimotope aptamer (CH1S-6T) onto the surface of MOF@Au nanocomposite. Comparative studies demonstrated that MOF@Au@peptide@aptamer exhibited significantly enhanced enrichment capabilities for trastuzumab variants in comparison to mono-epitope affinity technology. Moreover, the higher deamidation ratio for LC-Asn-30 and isomerization ratio for HC-Asn-55 can only be monitored by the novel bioanalytical platform based on MOF@Au@peptide@aptamer and liquid chromatography-quadrupole time of flight-mass spectrometry (LC-QTOF-MS). Therefore, multi-epitope affinity technology could effectively overcome the biases of traditional affinity materials for key sites modification analysis of mAb. Particularly, the novel bioanalytical platform can be successfully used for the tracking analysis of trastuzumab modifications in different biological fluids. Compared to the spiked phosphate buffer (PB) model, faster modification trends were monitored in the spiked serum and patients' sera due to the catalytic effect of plasma proteins and relevant proteases. Differences in peptide modification levels of trastuzumab in patients' sera were also monitored. In summary, the novel bioanalytical platform based on the multi-epitope affinity technology holds great potentials for in vivo biotransformation analysis of mAb, contributing to improved understanding and paving the way for future research and clinical applications.

Objective:To study the effects of tetramethylpyrazine on the expressions of ferroptosis related molecules after spinal cord injury; To explore the mechanism of tetramethylpyrazine promoting the repair of spinal cord injury (SCI).Methods:Totally 36 SD rats were divided into sham-operation group, model group and tetramethylpyrazine group according to random number table method, with 12 rats in each group. The rats in the sham-operation group underwent laminectomy without injury to the spinal cord. The SCI model was prepared in the other two groups. The rats in the tetramethylpyrazine group were intraperitoneally injected with tetramethylpyrazine of 80 mg/kg, and the rats in the sham-operation group and model group were intraperitoneally injected with the same volume of normal saline, once a day, continuous intervention for 28 days. One day before operation and 1, 3, 5, 7, 14, 21, 28 days after operation, BBB limb motor function score was used to evaluate the limb motor function of rats. Nissl staining was used to observe the morphology of neurons. Prussian staining was used to observe iron deposition. Assay kit was used to detect the contents of MDA and ROS in spinal cord tissue. Western blot was used to detect the protein expressions of xCT, GPX4 and ACSL4, and qPCR was used to detect the mRNA expressions of mRNA of xCT, GPX4 and ACSL4.Results:On the 14th, 21st and 28th days after operation, compared with the model group, the BBB score of tetramethylpyrazine group increased ( P<0.01); tetramethylpyrazine could significantly improve the morphology and structure of neurons and reduce the iron content in spinal cord tissue; compared with the model group, the contents of MDA and ROS in the spinal cord tissue of tetramethylpyrazine group decreased ( P<0.01); the levels of xCT and GPX4 mRNA and protein increased ( P<0.01), while the expression of ACSL4 mRNA and protein decreased ( P<0.01). Conclusion:Tetramethylpyrazine can regulate lipid peroxidation by regulating the expressions of ferroptosis related molecules, which is conducive to the recovery of limb motor function in rats with spinal cord injury.

Homocysteine (Hcy) is a sulfur-containing metabolic intermediate of methionine,which is normally at a lower level in the blood.Recent studies have shown that the elevated blood level of Hcy is an independent risk factor for ischemic stroke and increases the risk of occurrence of cerebral small vessel disease (CSVD).This article reviews the relationship between Hcy and CSCD.

Atrial fibrillation is a common type of arrhythmia. Cerebral microbleeds (CMBs) are a neuroimaging phenotype of cerebral small vessel disease, which is related to the tendency of intracranial hemorrhage. Studies have shown that the detection rate of CMBs in patients with atrial fibrillation is higher, and CMBs are also a risk factor for increasing the risk of stroke in patients with atrial fibrillation and death in patients with atrial fibrillation complicated with stroke. This article reviews the predictive factors of CMBs in patients with atrial fibrillation.

Objective To investigate the carotid arterial stiffness in patients with coronary slow flow ( CSF) .Methods forty-five patients with CSF and Forty -five persons having normal coronary arteries ( NCA) detected by coronary angiography with a similar distri-bution of risk factors were recruited .Stiffness parameter (β), pressure-strain elastic modulus (Ep), arterial compliance (AC) and lo-cal pulse-wave velocity (PWV) were obtained at the level of bilateral carotid artery by a real time echo -tracking system.Serum levels of high-sensitivity C-reactive protein ( hs-CRP) were measured in two groups of subjects .Linear regression analysis were performed to evaluate the correlation between hs -CRP and the parameters of the carotid artery stiffness .Results We found that stiffness parameter (β), Ep and PWV were significantly higher in CSF group those that of control group (β:11.80 ±3.19 vs 9.70 ±3.76,P<0.01;Ep:149.90 ±44.47 vs 130.10 ±41.56,P<0.05;PWV:7.40 ±0.84 vs 7.00 ±1.08,P<0.05), AC was lower than that of control group (0.640 ±0.180 vs 0.760 ±0.192 ,P<0.01).The levels of high-sensitivity C-reactive protein (hs-CRP) was significantly higher in CSF group than that of control group (13.90 ±10.66 vs 9.30 ±6.33,P<0.05).The levels of hs-CRP was positively correlated with theβ(r=0.272,P=0.005), Ep(r=0.411,P=0.003), and PWV(r=0.452,P=0.001), but negatively correlated with AC (r=-0.293,P=0.025).Conclusion Echo-tracking technology is a simple practical method to evaluate carotid artery stiffness in patients with CSF and correlation well with coronary slow flow and artery stiffness .