Shinichi Izumi

Facilitatory effect of thinking about movement on motor-evoked potentials to transcranial magnetic stimulation of the brain

Two experiments using transcranial magnetic stimulation (TMS) were undertaken to investigate facilitatory effects of thinking about a specific movement without voluntary discharges on motor-evoked potentials (MEP). First, surface electromyographic (EMG) responses from the abductor pollicis brevis were recorded with maximal stimulator output in the three conditions: the muscle being at rest, contracting with 10% of maximal muscle activity, and with the subject only thinking about thumb abduction (nine subjects). Median value of MEP amplitudes during only thinking was twice that at rest (P = 0.008) and one-half that during voluntary contraction (P = 0.008). Second, needle EMG responses from the first dorsal interosseus were compared at rest, during thinking about index finger abduction, and during TMS at threshold intensity. Four normal subjects were tested with stimulation of each cerebral hemisphere for a total of eight tests. The number of detectable MEP responses of 20 stimuli to one hemisphere was counted for each condition of rest or thinking. The mean MEP response rate during thinking (58%) was higher than that at rest (12%) (P < 0.005). These results demonstrate that thinking about a specific movement has facilitatory effects on MEP and that the degree of facilitation in thinking is smaller than in voluntary contraction.

Reliability and Validity of the Manual Function Test in Patients with Stroke

Miyamoto S, Kondo T, Suzukamo Y, Michimata A, Izumi S-I: Reliability and validity of the manual function test in patients with stroke. Am J Phys Med Rehabil 2009;88:247-255. Objective:The Manual Function test (MFT) is an upper-limb function assessment measure for hemiparetic patients after stroke. This study represents the reliability and validity of the MFT. Design:Ninety patients within half a year after stroke onset were hospitalized from August 2005 through November 2006. Test-retest reliability, interrater reliability, and internal consistency reliability of MFT were investigated. Validity of the MFT was evaluated with the Brunnstrom Stage, the Stroke Impairment Assessment Set, and the Barthel Index. Results:The test-retest reliability coefficient and interrater reliability of the MFT were consistently above 0.95. Cronbach’s &agr; coefficient as internal consistency of eight items was also 0.95. With respect to the validity of the MFT, it had a correlation of >0.8 with both the Brunnstrom Stage and the Stroke Impairment Assessment Set. The correlation among task items within each category was also high. There was a higher correlation (&rgr; = 0.647) between the MFT and Barthel Index. Among the Barthel Index items, “dressing” had the highest correlation with the MFT, which indicates that upper-limb functions and degree of independence in dressing are highly correlated. Conclusions:It was concluded that the MFT offers reliable and valid methods for assessing for upper-limb functional disorders.

Detection of silent cerebrovascular lesions in individuals with 'masked' and 'white-coat' hypertension by home blood pressure measurement: the Ohasama study.

Objective To investigate the risk of silent cerebrovascular lesions in individuals with masked hypertension (MHT) and white-coat hypertension. Methods Self-measured home blood pressure (HBP) and casual blood pressure (CBP) measurements were recorded in 1060 individuals at least 55 years of age (mean age, 66.3 years) in a general population of Ohasama, Japan. The relationships between silent cerebrovascular lesions (white matter hyperintensity and lacunar infarct) detected on MRI and four blood pressure groups [sustained normal blood pressure (SNBP), HBP <135/85 mmHg, CBP <140/90 mmHg; white-coat hypertension, HBP <135/85 mmHg, CBP ≥140/90 mmHg; MHT, HBP ≥135/85 mmHg, CBP <140/90 mmHg; sustained hypertension, HBP ≥135/85 mmHg, CBP ≥140/90 mmHg] were examined using multivariate analysis adjusted for possible confounding factors. Results The odds ratios of sustained hypertension (1.74, 95% confidence interval 1.18–2.57) and MHT (2.31, 95% confidence interval 1.32–4.04) for the presence of silent cerebrovascular lesions were significantly higher than the odds ratio of SNBP, whereas there was no significant difference between white-coat hypertension and SNBP (1.03, 95% confidence interval 0.75–1.41). The odds ratios for the presence of either lacunar infarct or white matter hyperintensity in the four groups were similar to those for silent cerebrovascular lesions. Conclusion The present study is the first to demonstrate that the risk of silent cerebrovascular lesions is higher with MHT than with SNBP and similar to that of sustained hypertension.

Immunocytochemical Study of Glutathione Peroxidase in Normal Rat Kidney

In the normal rat kidney, immunohistochemical localization of glutathione peroxidase (GSH-Po) was mainly in the proximal tubules (PTs), where the proximal portions (S1 + S2) were more intensely stained than the distal portion (S3). Immunocytochemically, GSH-Po was localized in cytosol including the core of microvilli and lysosomes of the epithelial cells in the PTs. Since albumin and IgG were not found in cytosol, it is suggested that cytosolic GSH-Po may be generated in situ, but is not derived from the serum.