The Value of MicroRNAs as an Indicator of the Severity and the Acute Phase of Spinal Cord Injury

OBJECTIVE: To assess the role of miRNA-21 and miRNA-223 in a balloon-compression model of spinal cord injury (SCI). METHODS: A total of 50 male Wistar rats (n=50) were divided into the three groups: the group A (n=15, insertion of the unflated Fogarty balloon catheter), the group B (n=15, insertion of the Fogarty balloon catheter at a volume of 20 μL) and the group C (n=15, insertion of the Fogarty balloon catheter at a volume of 50 μL). After the behavioral test, RNA isolation, microRNA expression profiling using microarrays and quantitative polymerase chain reaction, measurements were compared between the three groups. RESULTS: Despite a lack of significant differences in time-dependent changes in miRNA-21 expression levels between the three groups at 4 hours, there were significant differences in them at 1, 3, and 7 days (p<0.05). Moreover, there were significant differences in time-dependent changes in miRNA-223 expression levels between the three groups at 4 hours and 1, 3, and 7 days (p<0.05). Furthermore, miRNA-223 expression levels reached the highest at 1 day but were decreased with time thereafter in all the three groups. CONCLUSION: Expression levels of miRNA-21 and miRNA-223 might be associated with the severity and acute phase of SCI, respectively. It is mandatory, however, to analyze changes in levels of inflammatory markers and the relevant biological pathways.

Hemodynamic Adaptations to Regular Exercise in People With Spinal Cord Injury

OBJECTIVE: To investigate the real-time cardiovascular response to the progressive overload exercise in different levels of spinal cord injury (SCI), and to find out whether regular exercise has effect on these cardiovascular responses. METHODS: The study enrolled 8 able-bodied individuals in the control group plus 15 SCI subjects who were divided into two groups by their neurological level of injury: high-level SCI group (T6 or above) and low-level SCI group (T7 or below). Also, subjects were divided into exercise group and non-exercise group by usual exercise habits. We instructed the subjects to perform exercises using arm ergometer according to the protocol and checked plethysmograph for the real time assessment of blood pressure, heart rate, and cardiac output. RESULTS: Six subjects were included in high-level SCI group (3 cervical, 3 thoracic injuries), 9 subjects in low-level SCI group (9 thoracic injuries), and 8 able-bodied individuals in control group. During arm ergometer-graded exercise, mean arterial pressure (MAP) was significantly lower in high-level SCI subjects of non-exercise group, compared with high-level SCI subjects of exercise group. In addition, HR was significantly higher in low-level SCI group compared with control group. CONCLUSION: There are significant differences in mean arterial pressure of high-level SCI group according to usual exercise habits. We discovered that even in non-athlete high-level SCI, regular exercise can bring cardiac modulation through blood pressure control.

Effect of Regular Exercise on Cardiopulmonary Fitness in Males With Spinal Cord Injury

OBJECTIVE: To evaluate the cardiopulmonary endurance of subjects with spinal cord injury by measuring the maximal oxygen consumption with varying degrees of spinal cord injury level, age, and regular exercise. METHODS: We instructed the subjects to perform exercises using arm ergometer on healthy adults at 20 years of age or older with spinal cord injury, and their maximal oxygen consumption (VO2max) was measured with a metabolic measurement system. The exercise proceeded stepwise according to the exercise protocol and was stopped when the subject was exhausted or when VO2 reached an equilibriu RESULTS: Among the 40 subjects, there were 10 subjects with cervical cord injury, 27 with thoracic cord injury, and 3 with lumbar cord injury. Twenty-five subjects who were exercised regularly showed statistically higher results of VO2max than those who did not exercise regularly. Subjects with cervical injury showed statistically lower VO2max than the subjects with thoracic or lumbar injury out of the 40 subjects with neurologic injury. In addition, higher age showed a statistically lower VO2max. Lastly, the regularly exercising paraplegic group showed higher VO2max than the non-exercising paraplegic group. CONCLUSION: There are differences in VO2max of subjects with spinal cord injury according to the degree of neurologic injury, age, and whether the subject participates in regular exercise. We found that regular exercise increased the VO2max in individuals with spinal cord injury.