Takeshi Kamikubo

Dynamic Postural Control in Patients with Hemiparesis

Ikai T, Kamikubo T, Takehara I, Nishi M, Miyano M: Dynamic postural control in patients with hemiparesis. Am J Phys Med Rehabil 2003;82:463–469. Objective Decreased postural stability is a common problem associated with hemiparesis secondary to stroke. The purpose of this study was to evaluate dynamic postural control in patients with hemiparesis and in normal subjects matched for age. Design Quantitative posturography (EquiTest System) was performed to assess the response of subjects to sudden perturbations. A total of 59 patients with hemiparesis and 98 healthy volunteers were evaluated. All the patients were able to walk inside their house without lower limb orthoses. Both the patients and the healthy volunteers were subjected to forward and backward perturbations while standing on a movable force platform. Balance responses were analyzed in terms of weight symmetry, latency, amplitude (relative response strength), and strength symmetry. They were also subjected to toes-up and toes-down perturbations to evaluate their response to a disruptive balance force. Results The response latency to perturbations was longer and the response strength was weaker on the paretic side of patients with hemiparesis. The dynamic postural control was impaired in patients with hemiparesis as compared with healthy subjects. Conclusion The results suggest that patients with hemiparesis tend to fall easily and that the risk of falls toward the paretic side is high.

Changes in proteasome activity following transient ischemia.

Succinyl-Leu-Leu-Val-Tyr-4-methylcoumaryl-7-amide (Suc-LLVY-MCA) hydrolyzing activities of the 20S and 26S proteasomes in the gerbil cortex following transient forebrain ischemia were examined. Using extraction solutions without ATP, only 20S proteasome activity was noted after separation with glycerol gradient centrifugation. When these extracts were incubated with ATP and an ATP-regenerating system prior to glycerol gradient separation, both 20S and 26S proteasome activities were detected. Following 10 min of ischemia, the activity of the 26S proteasomes decreased, whereas the 20S proteasome activity increased after 30 min of reperfusion. These changes returned to the control level after 1 h. The active 26S proteasomes were formed with ATP-dependent association with the 20S proteasomes and several subunits and the 26S proteasomes degraded ubiquitin-protein conjugates. These results indicate that proteasome activity might not be irreversibly impaired after transient ischemia. However, transient inhibition of ATP-dependent conversion of 20S to 26S proteasomes in vitro must be one of the causes of the accumulation of the ubiquitin-protein conjugates in the early reperfusion period.

Increase in ubiquitin conjugates dependent on ischemic damage

Insoluble ubiquitin conjugates (UC) in the mitochondrial fraction of the gerbil cortex were analyzed following transient forebrain ischemia. At 1 h of reperfusion after 2-10 min of ischemia, UC increased as the duration of ischemia was prolonged. Pre-treatment with pentobarbital, rather than post-treatment immediately after recirculation, reduced the increase of UC at 1 h of reperfusion following 5 min of ischemia. Pentobarbital had no effect on in vitro ubiquitination of heat-denatured lysozyme by the extract of gerbil cortex. These results suggest that increase in UC is dependent on ischemic damage and pentobarbital attenuates the increase of UC by relieving injury during ischemia.

Lack of effect of transient ischemia on ubiquitin conjugation

Ubiquitin-conjugating activities in the soluble fractions of gerbil cortex and hippocampus following transient ischemia were examined in vitro. Ten minutes of ischemia did not affect the ubiquitination of heat-denatured lysozyme both in the cortex and in the hippocampus. No reduction of the conjugating activities following ischemia was also confirmed using the partially purified ubiquitin conjugating enzymes from the cortex. These results indicate that protein ubiquitination might not be impaired following transient ischemia.

Evaluation of Intellectual Function Associated with Maternal and Pediatric Thyroid Dysfunction

Objective: The purpose of this study was to evaluate the characteristics of intellectual function of children whose mother had thyroid dysfunction, as well as children with hypothyroidism. Methods: A total of 47 children aged five to seven, who were referred to the center for developmental evaluation at the national child health and development in Tokyo, Japan, were included in this study. The children were divided into two groups: Group A, children with euthyroidism whose mothers had thyroid dysfunction; Group B, children with hypothyroidism. For each group, unpaired t-test was conducted by comparing with the scores of the Japanese version of the Wechsler intelligence scale for children-fourth edition (WISC-IV). Results: There were 26 children in Group A, 21 in Group B. The scores of Full Scale Intelligence Quotient (FSIQ), Verbal Comprehension Index (VCI), Perceptual Reasoning Index (PRI), Working Memory Index (WMI) and Processing Speed Index (PSI) by WISC-IV were significantly higher in Group A than Group B (FSIQ, VCI; P < 0.01, PRI, WMI, PSI; P < 0.05). Conclusions: There were differences in intellectual function between the children with hypothyroidism and the children who did not have low thyroid hormone level. Low level of thyroid hormone during the neonatal period may be important for intellectual development.

Summary of the profiles of 22 children with traumatic brain injury tacted with the Japanese version of the WISC-IV

The Japanese version of the Wechsler intelligence scale for children-fourth edition (WISC-IV) is often used to assess cognitive dysfunction in children with traumatic brain injury (TBI). To reveal the characteristics of cognitive impairment in pediatric TBI, we retrospectively analyzed the results of 22 children with TBI on the WISC-IV that was conducted at the Developmental Evaluation Center of the National Center for Child Health and Development over three years from July 2011 to July 2014. It has been hypothesized that the WISC-IV is limited for revealing neuropsychological dysfunction after traumatic brain injury.