Diffusion tensor imaging reveals brain structure changes in dogs after spinal cord injury

Based on the Wallerian degeneration in the spinal cord pathways,the changes in synaptic connections,and the spinal cord-related cellular responses that alter the cellular structure of the brain,we presumed that brain diffusion tensor imaging(DTI)parameters may change after spinal cord injury.However,the dynamic changes in DTI parameters remain unclear.We established a Beagle dog model of T10 spinal cord contusion and performed DTI of the injured spinal cord.We found dynamic changes in DTI parameters in the cerebral peduncle,posterior limb of the internal capsule,pre-and postcentral gyri of the brain within 12 weeks after spinal cord injury.We then performed immunohistochemistry to detect the expression of neurofilament heavy polypeptide(axonal marker),glial fibrillary acidic protein(glial cell marker),and NeuN(neuronal marker).We found that these pathological changes were consistent with DTI parameter changes.These findings suggest that DTI can display brain structure changes after spinal cord injury.

Dynamic correlation of diffusion tensor imaging and neurological function scores in beagles with spinal cord injury

Exploring the relationship between different structure of the spinal cord and functional assessment after spinal cord injury is important. Quantitative diffusion tensor imaging can provide information about the microstructure of nerve tissue and can quantify the pathological damage of spinal cord white matter and gray matter. In this study, a custom-designed spinal cord contusion-impactor was used to damage the T_（10） spinal cord of beagles. Diffusion tensor imaging was used to observe changes in the whole spinal cord, white matter, and gray matter, and the Texas Spinal Cord Injury Score was used to assess changes in neurological function at 3 hours, 24 hours, 6 weeks, and 12 weeks after injury. With time, fractional anisotropy values after spinal cord injury showed a downward trend, and the apparent diffusion coefficient, mean diffusivity, and radial diffusivity first decreased and then increased. The apparent diffusion-coefficient value was highly associated with the Texas Spinal Cord Injury Score for the whole spinal cord（R = 0.919, P = 0.027）, white matter（R = 0.932, P = 0.021）, and gray matter（R = 0.882, P = 0.048）. Additionally, the other parameters had almost no correlation with the score（P 〉 0.05）. In conclusion, the highest and most significant correlation between diffusion parameters and neurological function was the apparent diffusion-coefficient value for white matter, indicating that it could be used to predict the recovery of neurological function accurately after spinal cord injury.

Effectiveness of oral motor respiratory exercise and vocal intonation therapy on respiratory function and vocal quality in patients with spinal cord injury:a randomized controlled trial

Singing,as a method of combining respiratory function exercise and vocal intonation therapy,provides a new direction for respiratory function exercise in patients with spinal cord injury.This randomized controlled trial investigated the effects of oral motor respiratory exercise and vocal intonation therapy on respiratory function and vocal quality in patients with spinal cord injury.Among 31 included patients with spinal cord injury,18 completed the treatment.These 18 patients were randomly assigned to undergo music therapy(intervention group,30 min/d,5 times a week,for a total of 12 weeks;n=9,7 males and 2 females;30.33±11.74 years old)or normal respiratory training(control group,n=9;8 males and 1 female;34.78±11.13 years old).Both patient groups received routine treatment concurrently.Before and at 6 and 12 weeks after intervention,a standard respiratory function test,a voice test,the St.George's Respiratory Questionnaire,and a quality of life questionnaire were administered.The results showed that the inspiratory capacity,forced expiratory volume in 1 second,forced vital capacity,maximal mid-expiratory flow rate,sing-loud pressure level,and sustained note length were significantly increased in the intervention group compared with the control group.The St.George's Respiratory Questionnaire and quality of life results of patients in the intervention group were significantly superior to those in the control group.These findings suggest that oral motor respiratory exercise and vocal intonation therapy,as respiratory training methods in music therapy,are effective and valuable for improving respiratory dysfunction and vocal quality in patients with spinal cord injury.This study was approved by the Ethics Committee of China Rehabilitation Research Center(approval No.2019-78-1)on May 27,2019 and was registered with the Chinese Clinical Trial Registry(registration number:Chi CTR1900026922)on October 26,2019.

Pathological significance of tRNA-derived small RNAs in neurological disorders

Non-coding RNAs(ncRNAs) are a type of RNA that is not translated into proteins. Transfer RNAs(tRNAs), a type of ncRNA, are the second most abundant type of RNA in cells. Recent studies have shown that tRNAs can be cleaved into a heterogeneous population of ncRNAs with lengths of 18–40 nucleotides, known as tRNA-derived small RNAs(tsRNAs). There are two main types of tsRNA, based on their length and the number of cleavage sites that they contain: tRNA-derived fragments and tRNA-derived stress-induced RNAs. These RNA species were first considered to be byproducts of tRNA random cleavage. However, mounting evidence has demonstrated their critical functional roles as regulatory factors in the pathophysiological processes of various diseases, including neurological diseases. However, the underlying mechanisms by which tsRNAs affect specific cellular processes are largely unknown. Therefore, this study comprehensively summarizes the following points:(1) The biogenetics of tsRNA, including their discovery, classification, formation, and the roles of key enzymes.(2) The main biological functions of tsRNA, including its miRNA-like roles in gene expression regulation, protein translation regulation, regulation of various cellular activities, immune mediation, and response to stress.(3) The potential mechanisms of pathophysiological changes in neurological diseases that are regulated by tsRNA, including neurodegeneration and neurotrauma.(4) The identification of the functional diversity of tsRNA may provide valuable information regarding the physiological and pathophysiological mechanisms of neurological disorders, thus providing a new reference for the clinical treatment of neurological diseases. Research into tsRNAs in neurological diseases also has the following challenges: potential function and mechanism studies, how to accurately quantify expression, and the exact relationship between tsRNA and miRNA. These challenges require future research efforts.

Dynamic changes in intramedullary pressure 72 hours after spinal cord injury

Intramedullary pressure increases after spinal cord injury, and this can be an important factor for secondary spinal cord injury. Until now there have been no studies of the dynamic changes of intramedullary pressure after spinal cord injury. In this study, telemetry systems were used to observe changes in intramedullary pressure in the 72 hours following spinal cord injury to explore its pathological mechanisms. Spinal cord injury was induced using an aneurysm clip at T10 of the spinal cord of 30 Japanese white rabbits, while another 32 animals were only subjected to laminectomy. The feasibility of this measurement was assessed. Intramedullary pressure was monitored in anesthetized and conscious animals. The dynamic changes of intramedullary pressure after spinal cord injury were divided into three stages: stage I(steep rise) 1–7 hours, stage Ⅱ(steady rise) 8–38 hours, and stage Ⅲ(descending) 39–72 hours. Blood-spinal barrier permeability, edema, hemorrhage, and histological results in the 72 hours following spinal cord injury were evaluated according to intramedullary pressure changes. We found that spinal cord hemorrhage was most severe at 1 hour post-spinal cord injury and then gradually decreased; albumin and aquaporin 4 immunoreactivities first increased and then decreased, peaking at 38 hours. These results confirm that severe bleeding in spinal cord tissue is the main cause of the sharp increase in intramedullary pressure in early spinal cord injury. Spinal cord edema and blood-spinal barrier destruction are important factors influencing intramedullary pressure in stages Ⅱ and Ⅲ of spinal cord injury.

Effect of Cooling Rate on the Formation and Morphology of (W,V)Cx in VC-doped WC–Co Cemented Carbide

The grain growth retardation mechanism and the effect of cooling rate on VC-doped WC–Co cemented carbides were investigated in this work.WC–30Co and WC–30Co–VC were prepared by powder metallurgy,liquid-phase sintering at 1400 ℃ and followed by water quenching（[150 ℃/s） or furnace cooling（＊0.083 ℃/s）.Based on the results of electron probe microanalysis（EPMA）,we found that WC concentration in the Co binder was independent of VC doping during liquid-phase sintering,hence barely contributing to the retardation of WC grain growth.In contrast,the（W,V）Cx phase formed at the WC/Co interfaces played a major role in retarding WC grain growth during liquid-phase sintering.The effect of cooling rate on the morphology of（W,V）Cxwas revealed by high-resolution transmission electron microscopy（HRTEM） and energy-dispersive spectroscopy（EDS）.In the water-quenched WC–30Co–VC,（W,V）Cxprecipitates were found as thin layers at the WC/Co interfaces.In contrast,both thin layers of similar thickness and nanoparticles of（W,V）Cx were observed in the furnace-cooled counterpart.These observations listed above suggested that thin（W,V）Cxlayers were stable structures effectively suppressing the growth of WC grains and their thickness remained independent of the cooling rate.The（W,V）Cxnanoparticles,however,may be inhibited through rapid cooling,ensuring the VC-doped WC–Co cemented carbides desired toughness.

An Improved Urethral Catheterization in Female Pigs： A Pilot Study

With the popularity of urine flow dynamic monitoring and indwelling catheter technologies in animal experiments,the urethral catheterization has become a common technique in scientific research.The miniature pig is considered as one of the major animal species used in scientific research and is increasingly being used as an alternative to a dog or monkey as the nonrodent species of choice in the preclinical toxicological testing of pharmaceuticals.[1] Since there are three acute angles bending in the urethra of the male miniature pig,and the end of the penis head is cork-screw shaped,it is difficult to implement routine urethral catheterization in male miniature pigs.Currently,researchers usually implement bladder colostomies or dissections in male miniature pigs,while transurethral urethral catheterization can be implemented in female miniature pigs.According to the existing reports,implementing transurethral urethral catheterization in female miniature pigs is seldom seen.[2] We chose 3-month-old female Bama miniature pigs in our experiments and employ the following methods：first,use a ＂V＂-shaped platform with an angle of about 30° to the horizontal plane;second,utilize a pediatric laryngoscope for deep lighting;third,bend the lower limbs and press down to the ventral side.Satisfactory results through transurethral urethral catheterization were achieved in the end.