Neuroprotective effect and possible mechanism of edaravone in rat models of spinal cord injury: a protocol for a systematic review and meta-analysis

BACKGROUND

Spinal cord injury (SCI) is one of the most disabling neurological conditions, afflicting thousands of human beings. Edaravone, a well-known reactive oxygen species scavenger, is expanding its new scope in field of SCI. The objective of this systematic review is to determine the neuroprotective effects and discuss the underlying mechanism of edaravone in management of SCI.

METHODS

The systematic review will include the controlled studies evaluating the neurological roles of edaravone on experiment rat models following SCI. The primary outcome will be the 21-point Basso, Beattie, and Bresnahan locomotor rating scale. The secondary outcomes will include the preservation of white matter areas and malondialdehyde levels. Two researchers will independently search PubMed, Embase, Web of Science, Scopus and Cochrane Library from their inception date. Following study selection, data extraction, and assessment of methodological quality in included studies using the SYRCLE's RoB tool, data from eligible studies will be pooled and analyzed using random-effects models with RevMan 5.3 software. In case of sufficient data, subgroup analyses with respect to species, age, gender, injury characteristics, or administration details will be carried out to explore the factors modifying efficacy of edaravone. For exploring the appropriate dose of edaravone, a network meta-analysis approach will be conducted based on the Bayesian method. Importantly, the proposed mechanisms and changes of related molecules will be also extracted from included studies for comprehensively investigating the mechanisms underlying the neuroprotective effects of edaravone.

DISCUSSION

In this study, we aim to quantitatively analyze the role of edaravone in locomotor recovery and tissue damage in SCI rat model. The efficacy of edaravone in distinct scenarios will be investigated by subgroup analyses, and we expect to predict the candidate dose that offers a superior treatment effect using network meta-analyses. Moreover, a comprehensive framework regarding the neuroprotective mechanisms behind edaravone will be constructed via a combination of systematic and traditional review. This study will bring implications for future preclinical studies and clinical applications of SCI. Nonetheless, in light of the anticipated limitations in animal experimental design and methodological quality, the results in this review should be interpreted with caution.

The effect of metformin on ameliorating neurological function deficits and tissue damage in rats following spinal cord injury: A systematic review and network meta-analysis

Spinal cord injury (SCI) is a devastating condition with few treatment options. Metformin, a classical antidiabetic and antioxidant, has extended its application to experimental SCI treatment. Here, we performed a systematic review to evaluate the neurobiological roles of metformin for treating SCI in rats, and to assess the potential for clinical translation. PubMed, Embase, China National Knowledge Infrastructure, WanFang data, SinoMed, and Vip Journal Integration Platform databases were searched from their inception dates to October 2021. Two reviewers independently selected controlled studies evaluating the neurobiological roles of metformin in rats following SCI, extracted data, and assessed the quality of methodology and evidence. Pairwise meta-analyses, subgroup analyses and network analysis were performed to assess the roles of metformin in neurological function and tissue damage in SCI rats. Twelve articles were included in this systematic review. Most of them were of moderate-to-high methodological quality, while the quality of evidence from those studies was not high. Generally, Basso, Beattie, and Bresnahan scores were increased in rats treated with metformin compared with controls, and the weighted mean differences (WMDs) between metformin and control groups exhibited a gradual upward trend from the 3rd (nine studies, n = 164, WMD = 0.42, 95% CI = −0.01 to 0.85, P = 0.06) to the 28th day after treatment (nine studies, n = 136, WMD = 3.48, 95% CI = 2.04 to 4.92, P < 0.00001). Metformin intervention was associated with improved inclined plane scores, tissue preservation ratio and number of anterior horn motor neurons. Subgroup analyses indicated an association between neuroprotection and metformin dose. Network meta-analysis showed that 50 mg/kg metformin exhibited greater protection than 10 and 100 mg/kg metformin. The action mechanisms behind metformin were associated with activating adenosine monophosphate-activated protein kinase signaling, regulating mitochondrial function and relieving endoplasmic reticulum stress. Collectively, this review indicates that metformin has a protective effect on SCI with satisfactory safety and we demonstrate a rational mechanism of action; therefore, metformin is a promising candidate for future clinical trials. However, given the limitations of animal experimental methodological and evidence quality, the findings of this pre-clinical review should be interpreted with caution.

[Investigation on the awareness of snoring hazard and prevalence of obstructive sleep apnea among civil servants]

Objective: To investigate the awareness of snoring hazard and prevalence of obstructive sleep apnea (OSA) among civil servants. Methods: A cross-sectional survey was conducted to investigate the awareness of snoring hazards among in-service civil servants who had annual medical examination in a Guangdong provincial institution from September to November 2017. The high-risk group for OSA was screened and diagnosed by sleep monitoring. Results: 1 036 of 1 241 civil servants were enrolled in the study for integral data. 60.1% (623/1 036) of the subjects realized that snoring was harmful to health. The most common source to develop OSA awareness was network (59.6%, 371/623), followed by television (48.0%), relatives and friends (46.6%), newspaper (44.5%) and radio (18.9%). The awareness rate of snoring consequences was as follows: decreased sleep quality (71.9%, 448/623), sudden death (52.2%), daytime sleepiness (44.3%), cardiovascular and cerebrovascular diseases (42.9%), hypertension (24.4%) and sexual dysfunction (16.7%). 22.0% (228 / 1 036) of the cases were classified into high-risk OSA. The prevalence of OSA among high-risk group was 46.05%(105/228)and only 0.9% (2/228) of them had been diagnosed with OSA. Conclusion: Civil servants had awareness of snoring hazard to a certain extent. Among civil servants classified into high-risk OSA, the OSA perveance was high but the rate of diagnosis and treatment was very low.

[Clinical significance and correlation of ductular reaction in hepatobiliary diseases]

Ductular reaction is a kind of repair response to biliary and hepatocellular injury, and the pathological changes include lobular bile duct hyperplasia, matrix change and inflammatory cell infiltrations. In human liver, a ductular reaction originates from the activation and proliferation of hepatic progenitor cells. The activated hepatic progenitor cells, the intermediate hepatocytes and the reactive small bile duct cells together form the cell complex of ductular reaction, which has the dual characteristics of hepatobiliary system and co-expresses the hepatocyte and cholangiocyte antigen. Ductular reaction appears in all kinds of acute and chronic hepatobiliary injury, and plays an important role in liver regeneration and repair, fibrogenesis, cirrhosis formation, and hepatobiliary cancer occurrence and development. Understanding the pathological features and pathophysiological mechanisms of ductular reaction in various clinical hepatobiliary diseases and their role in liver regeneration can provide important suggestion for further exploring new-targeted treatment approach.

[Role of Yes-associated protein 1 in angiotensinⅡ-induced pulmonary fibrosis in rats]

Objective: To explore the mechanism of Yes-associated protein 1 (Yap1) in angiotensinⅡ(AngⅡ)-induced pulmonary fibrosis. Methods:In vivo, 18 male Wistar rats were randomly divided into three equal groups with 6 rats in each group, including control group, bleomycin-treated group (BLM), and BLM+ AngⅡ group. 28 days later, the lung tissues in all groups were harvested for the HE and Masson staining as well as the immunohistochemical (IHC) staining for Yap1. In vitro, the isolated fibroblasts were treated with 10(-7) mmol/L AngⅡor the AngⅡ-targeted inhibitor irbesartan for the scheduled time for mRNA and protein expressions of Yap1, PDZ-binding motif (TAZ), and collagen Ⅰusing PCR and Western blot, as well as the translocation test from the nucleus to the cytoplasm of Yap1 and TAZ. Subsequently, the fibroblasts were assigned into 4 groups: the empty plasmid (vector) group, the vector+ AngⅡ group, the Yap1 shRNA group, and the Yap1 shRNA+ AngⅡ group. Western blot was used to detect the relative expressions of Yap1, TAZ, Smad3 and collagen Ⅰ. The CCK-8 and EdU assays were performed to determine the proliferative capacity. Results:In vivo, severe lung fibrosis and increased Yap1 expression of IHC staining were found in BLM group. Additionally, more severe lung fibrosis and higher Yap1 expression were detected in the BLM+ AngⅡ group than the BLM group (both P<0.05). In vitro, both the mRNA and protein relative expressions of Yap1, TAZ and collagenⅠ were markedly higher in AngⅡ-treated groups than the control group (all P<0.05). Meanwhile, the relative expression of phosphorylated Yap1 reached its peak at 2 h after AngⅡ stimulation. In the protein translocation tests, after treated with AngⅡ for 24 h, the relative protein levels of Yap1 and TAZ in the nucleus of the AngⅡ group were significantly higher than those in the control group (0.382±0.007 vs 0.031±0.001, 1.097±0.030 vs 0.357±0.015). However, the relative protein expressions in the cytoplasm of the AngⅡ group were obviously less than that in the control group (0.323±0.058 vs 0.418±0.044, 0.858±0.059 vs 1.201±0.015). Compared with the AngⅡ group, the expressions of Yap1 and TAZ in the AngⅡ+ irbesartan group were higher in cytoplasm (0.598±0.060 vs 0.323±0.058, 1.495±0.052 vs 0.858±0.059), while lower in the nucleus (0.323±0.058 vs 0.418±0.044, 0.858±0.059 vs 1.201±0.015) (all P<0.05). Furthermore, the relative protein expressions of Yap1, TAZ, Smad3 and collagenⅠin Yap1 shRNA+ AngⅡ group were distinctly lower than the vector+ AngⅡ group (all P<0.05). In the cell proliferation tests, the absorbance and the percentage of EdU positive cells of vector+ AngⅡ group exceeded that of vector group (both P<0.05). However, the absorbance and the percentage of EdU positive cells in the Yap1 shRNA+ AngⅡgroup were less than the vector+ AngⅡ group (both P<0.05). Conclusion: AngiotensinⅡ promoted the collagen synthesis and cell proliferation in primary lung fibroblasts by increasing the Yap1 activity, leading to the progress of fibrosis.

[A cross-sectional survey of treatment acceptance and influence factors in patients with obstructive sleep apnea]

Objective: To investigate the treatment acceptance in patients with obstructive sleep apnea (OSA) and its influence factors. Methods: This cross-sectional survey recruited OSA patients diagnosed at sleep center in Guangdong General Hospital from January 2014 to December 2015. By phone follow-up, a pre-designed questionnaire was performed for all adults, which composed of the following sections: treatment or none, treatment method, reason for non-treatment, revisit or none. Results: From 524 OSA patients with completed contact information, 480 (91.6%) valid questionnaires were collected. The apnea hypopnea index was (36.1±21.4) /h. The mild, moderate, severe OSA patients accounted for 12.5%(60 cases), 33.1%(159 cases), 54.4%(261 cases) respectively. For all 480 included subjects, 200 (41.7%) received treatment and among them 184 (92.0%) were treated by continuous positive airway pressure. The treatment rate was lower in mild OSA, non-obesity, female, and patients without daytime sleepiness. Receiving treatment was negative correlated to difficult falling asleep. The first reason of non-treatment was self-determined behavioral intervention and the second was self-concept of no requirement for treatment. The specialist revisit rate was 3.8%, which was slightly higher in treated patients and those with sudden awakening when feeling asphyxia. Conclusion: A majority of OSA patients do not receive treatment, primarily as a result of their self-determined behavior intervention and self-concept of no requirement for treatment.

[The risk factors analysis and optimal timing for drainage of lymphocele infection after pelvic lymphadenectomy in patients with endometrial cancer]

Objcetive: To investigate the incidence and risk factors of Lymphocele infection and the optimal timing for drainage after pelvic lymphadenectomy. Methods: This retrospective study was carried out on 397 patients who received a pelvic lymphadenectomy with or without a para-aortic lymphadenectomy between January 2009 and April 2016, due to endometrial cancer in General hospital of Tianjin medical university.A total of 76 patients developed lymphocele and 20 patients developed lymphocele infection. Results: (1)The incidence of lymphocele infection was 5.04% (20/397). Single factor analysis indicated diameter of lymphocele ≥5 cm and postoperative anemia were associated with lymphocele formation (P<0.001, P=0.023). Multiple factors Logistic analysis through the adjustment of the factors showed diameter of lymphocele ≥5 cm was the independent risk factors for lymphocyst infection (P<0.001). (2)The total treatment period of cases treated only with antibiotics tended to be shorter than that of cases treated with combined antibiotics and drainage (P=0.008). However, for severe cases which needed drainage, initiating the drainage by day 3 significantly shortened the total treatment period compared with cases started on or after day 4 (P=0.048). Conclusion: To identify the risk factors of the lymphocele infection is useful to help reduce the incidence of them with effective measurement.When drainage is required in addition to antibiotics, the earlier the drainage is performed, the shorter the treatment period is.

[Mechanism of angiotensin-converting enzyme 2 overexpression improving collagen synthesis in lung]

Objective: To explore the mechanism of angiotensin-converting enzyme 2 (ACE2) overexpression improving collagen synthesis in lung. Methods: Lung fibroblasts of mice over-expressing ACE2 and the wild type (WT) were cultured in vitro and divided into 5 groups: WT-control, WT-AngiotensinⅡ (AngⅡ), ACE2(+ /+) -control, ACE2(+ /+) -AngⅡ and ACE2(+ /+) -AngⅡ+ A779. The protein relative expression levels of ACE2, collagen Ⅰ, nicotinamide adenine dinucleotide phosphate oxidase 4 (NOX4), nucleotide binding and oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3), autophagy-related protein (Beclin1), ubiquitin-binding protein p62 (P62), microtubule-associated proteins light chain 3-Ⅱ (LC3-Ⅱ) were measured by Western blot and triphosadenine (ATP) level was measured by ATP Assay Kit. Fibroblasts over-expressing ACE2 were pretreated with or without the autophagy inhibitor and were separated into 4 groups: ACE2(+ /+) -control, ACE2(+ /+) -AngⅡ, ACE2(+ /+) -AngⅡ+ 3-MA and ACE2(+ /+) -3-MA. In vivo, random allocation was used to averagely divide mice into four groups: WT-control, WT-Bleomycin (BLM), ACE2(+ /+) - control, ACE2(+ /+) -BLM. Wild type and ACE2 over-expressing mice were instilled with bleomycin endotracheally (3.5 mg/kg) or the same volume saline. All mice were sacrificed after 28 days and the lung tissue were used for HE and Masson staining as well as immunohistochemical staining for NOX4, P62 and LC3. Results: The vimentin in lung fibroblasts isolated from mice was proved to be positive by both immunohistochemical and immunofluorescence. The ACE2 protein level of lung fibroblasts over-expressing ACE2 was higher than the wild type (0.202±0.062 and 0.067±0.040, P<0.05). The protein levels of collagenⅠ, NOX4 and NLRP3 in WT-AngⅡ group were obviously higher than the WT-control group (0.861±0.129 and 0.417±0.076, 0.432±0.036 and 0.318±0.058, 0.367±0.125 and 0.045±0.012, all P<0.05). The difference of collagenⅠand NLRP3 between ACE2(+ /+) -AngⅡ group and ACE2(+ /+) -control group had no statistical significance (all P>0.05). CollagenⅠand NOX4 protein level in ACE2(+ /+) -AngⅡ+ A779 group were observably higher than ACE2(+ /+) - AngⅡ group (0.707±0.155 and 0.458±0.108, 0.299±0.038 and 0.149±0.090, all P<0.05). The autophagy related protein levels of Beclin1, P62 and LC3-Ⅱ in ACE2(+ /+) -control group were distinctly higher than WT-control group (0.834±0.051 and 0.274±0.018, 0.467±0.078 and 0.093±0.025, 0.494±0.065 and 0.150±0.054, all P<0.05). However, these protein levels in ACE2(+ /+) -AngⅡ+ A779 group were lower than ACE2(+ /+) -AngⅡ group (1.331±0.203 and 1.565±0.069, 0.298±0.096 and 0.438±0.077, 0.464±0.093 and 0.768±0.071, all P<0.05). ACE2(+ /+) -AngⅡ+ 3-MA group had higher collagenⅠ (0.383±0.125 and 0.032±0.013, P<0.05) and lower LC3-Ⅱ protein level (1.177±0.140 and 1.387±0.183, P<0.05) than AngⅡ group. In bleomycin induced lung fibrosis in mice, ACE2(+ /+) -BLM mice exhibited milder lung fibrosis and lower NOX4 protein level but higher LC3-Ⅱprotein level compared with WT-BLM mice. Conclusion: ACE2 over-expression ameliorated collagen synthesis through enhancing autophagy in lung.

Fast Surface Dynamics of Metallic Glass Enable Superlatticelike Nanostructure Growth

Contrary to the formation of complicated polycrystals induced by general crystallization, a modulated superlatticelike nanostructure, which grows layer by layer from the surface to the interior of a Pd_{40}Ni_{10}Cu_{30}P_{20} metallic glass, is observed via isothermal annealing below the glass transition temperature. The generation of the modulated nanostructure can be solely controlled by the annealing temperature, and it can be understood based on the fast dynamic and liquidlike behavior of the glass surface. The observations have implications for understanding the glassy surface dynamics and pave a way for the controllable fabrication of a unique and sophisticated nanostructure on a glass surface to realize the properties' modification.

Understanding Atomic-Scale Features of Low Temperature-Relaxation Dynamics in Metallic Glasses

Being a key feature of a glassy state, low temperature relaxation has important implications on the mechanical behavior of glasses; however, the mechanism of low temperature relaxation is still an open issue, which has been debated for decades. By systematically investigating the influences of cooling rate and pressure on low temperature relaxation in the Zr₅₀Cu₅₀ metallic glasses, it is found that even though pressure does induce pronounced local structural change, the low temperature-relaxation behavior of the metallic glass is affected mainly by cooling rate, not by pressure. According to the atomic displacement and connection mode analysis, we further demonstrate that the low temperature relaxation is dominated by the dispersion degree of fast dynamic atoms rather than the most probable atomic nonaffine displacement. Our finding provides the direct atomic-level evidence that the intrinsic heterogeneity is the key factor that determines the low temperature-relaxation behavior of the metallic glasses.

Structural Signature of Plasticity Unveiled by Nano-Scale Viscoelastic Contact in a Metallic Glass

Room-temperature plasticity in metallic glasses (MGs) is commonly associated with local structural heterogeneity; however, direct observation of the subtle structural change caused by plasticity is vitally important but the data are extremely scarce. Based on dynamic atomic force microscopy (DAFM), here we show that plasticity-induced structural evolution in a Zr-Ni MG can be revealed via nano-scale viscoelastic contacts between an AFM tip and plastically deformed MG surface layers. Our experimental results clearly show a spatial amplification of the nano-scale structural heterogeneity caused by the distributed plastic flow, which can be linked to the limited growth, reorientation and agglomeration of some nano-scale energy-absorbing regions, which are reminiscent of the behavior of the defect-like regions with non-affine deformation as conceived in many theories and models. Furthermore, we are able to experimentally extract the thermodynamic properties of these nano-scale regions, which possess an energy barrier of 0.3–0.5 eV, about half of that for a typical shear transformation event that usually occurs at the onset of plasticity. The outcome of our current work sheds quantitative insights into the correlation between plasticity and structural heterogeneity in MGs.

Shear-banding Induced Indentation Size Effect in Metallic Glasses

Shear-banding is commonly regarded as the “plasticity carrier” of metallic glasses (MGs), which usually causes severe strain localization and catastrophic failure if unhindered. However, through the use of the high-throughput dynamic nanoindentation technique, here we reveal that nano-scale shear-banding in different MGs evolves from a “distributed” fashion to a “localized” mode when the resultant plastic flow extends over a critical length scale. Consequently, a pronounced indentation size effect arises from the distributed shear-banding but vanishes when shear-banding becomes localized. Based on the critical length scales obtained for a variety of MGs, we unveil an intrinsic interplay between elasticity and fragility that governs the nanoscale plasticity transition in MGs. Our current findings provide a quantitative insight into the indentation size effect and transition mechanisms of nano-scale plasticity in MGs.

The equipment for the preparation of micro and nanoscale metallic glassy fibers

A supercooled liquid extraction method and apparatus for micro and nanoscale metallic glassy fiber preparation was developed. Using the fiber fabrication equipment, micro to nanoscale metallic glassy fibers with diameter ranging from 70 nm to 300 μm can be obtained by wire drawing in the supercooled liquid region of metallic glasses via superplastic deformation. The obtained metallic glassy fibers possess precisely designed and controlled sizes, high structural uniformity and high degree of surface smoothness.

Nanoscale periodic morphologies on the fracture surface of brittle metallic glasses

Out-of-plane, nanoscale periodic corrugations are observed in the dynamic fracture surface of brittle bulk metallic glasses with fracture toughness approaching that of silica glasses. A model based on the meniscus instability and plastic zone theory is used to explain such dynamic crack instability. The results indicate that the local softening mechanism in the fracture is an essential ingredient for controlling the formation of the unique corrugations, and might provide a new insight into the origin of fracture surface roughening in brittle materials.

Amorphous metallic plastic

We report cerium-based bulk metallic glasses with an exceptionally low glass transition temperature Tg, similar to or lower than that of many polymers. We demonstrate that, in near-boiling water, these materials can be repeatedly shaped, and can thus be regarded as metallic plastics. Their resistance to crystallization permits extended forming times above Tg and ensures an adequate lifetime at room temperature. Such materials, combining polymerlike thermoplastic behavior with the distinctive properties of metallic glasses, are highly unusual for metallic alloys and have great potential in applications and can also facilitate studies of the supercooled liquid state.

Fracture of brittle metallic glasses: brittleness or plasticity

We report a brittle Mg-based bulk metallic glass which approaches the ideal brittle behavior. However, a dimple structure is observed at the fracture surface by high resolution scanning electron microscopy, indicating some type of "ductile" fracture mechanism in this very brittle glass. We also show, from the available data, a clear correlation between the fracture toughness and plastic process zone size for various glasses. The results indicate that the fracture in brittle metallic glassy materials might also proceed through the local softening mechanism but at different length scales.

[A survey on mother's nutritional knowledge-attitude on the feeding of young child in Guangdong province]

A survey on mother's nutrition knowledge-attitude on the feeding of young child was conducted in Guangdong province in 1995 among 414 mothers of 0 to 18 months old children. The results showed that the nutritional knowledge-attitude level of the mothers was low in both city and township. Only 51% of them had qualified level. The level of general nutritional concepts and the nutritional knowledge-attitude during weaning period were significantly lower than that of breastfeeding and follow-weaning. It suggests that the promotion of nutritional education in the feeding of young children is urgent in Guangdong province especially in township and rural area. It is necessary to focus on the improvement of nutritional knoweledge in weaning period and general nutrition concepts.

Does compliance mismatch alone cause neointimal hyperplasia?

To define the relationship between compliance mismatch and the development of neointimal hyperplasia, one 3 cm segment of common iliac artery was externally banded in seven dogs, thereby fixing the arterial diameter at end diastole. To quantify compliance, end-diastole diameter and its change with pulse pressure were measured by induction angiometry. This technique uses intravascular soft trifilar wire probes introduced through distally placed polytetrafluoroethylene sidearms. Compliance was checked in the banded and contralateral undissected unbanded control iliac arteries at 3 and 6 months, at which times the vessels were fixed by perfusion, excised, and examined histologically. Sustained (6-month) compliance mismatch was successfully induced within the banded segments (p less than 0.0001), and no compliance mismatch was seen in the control segments (p = 0.357). The intima of all banded vessels was virtually indistinguishable from that in controls grossly and histologically. Mild focal intimal thickening, less than 3 cell layers thick involving less than 5% of the vessel circumference, was typically seen in both banded and control vessels (range 6.57 +/- 6.80 micron to 38.86 +/- 57.16 micron). In marked contrast, at the sites of the polytetrafluoroethylene-to-femoral artery anastomosis, near-occlusive neointimal hyperplasia (1714 +/- 415.47 micron) was seen in all animals. Residual lumen area in the banded and control vessels was only minimally abnormal (range 98.65% +/- 2.18% to 99.96% +/- 0.08%). These data indicate that compliance mismatch alone is an insufficient stimulus for the development of neointimal hyperplasia in the canine model.