Biomedical subjects

Kei Suzuki

Publications and source records attributed to Kei Suzuki.

6 recordsLinked to original sources

PubMed2005

Sign and speech: amodal commonality in left hemisphere dominance for comprehension of sentences.

The neural basis of functional lateralization in language processing is a fundamental issue in systems neuroscience. We used functional MRI (fMRI) to examine hemispheric dominance during the processing of signed and spoken sentences. By using tasks involving comprehension of sentences (Sc) and sentential non-word detection (Sn), we compared different groups and stimulus conditions. Under the sign condition with sentence stimuli in Japanese Sign Language (JSL), we tested two groups of subjects: Deaf signers (Deaf) of JSL, and hearing bilinguals (children of Deaf adults, CODA) of JSL and Japanese (JPN). Under the speech condition, we tested hearing monolinguals (Mono) of JPN with auditory JPN stimuli alone (AUD), or with an audiovisual presentation of JPN and JSL stimuli (A&V). We found that the overall bilateral activation patterns under the four experimental conditions of Deaf, CODA, AUD and A&V were almost identical, despite differences in stimuli (JSL and JPN) and groups (Deaf, CODA and Mono). Moreover, consistently left-dominant activations involving frontal and temporo-parietal regions were observed across all four conditions. Furthermore, irrespective of the modalities of sign and speech, the main effects of task (Sc-Sn) were found primarily in the left regions: the ventral part of the inferior frontal gyrus (F3t/F3O), the precentral sulcus, the superior frontal gyrus, the middle temporal gyrus, the angular gyrus and the inferior parietal gyrus. Among these regions, only the left F3t/F3O showed no main effects of modality condition. These results demonstrate amodal commonality in the functional dominance of the left cortical regions for comprehension of sentences, as well as the essential and universal role of the left F3t/F3O in processing linguistic information from both signed and spoken sentences.

Acoustic Stimulation↗

PubMed2004

Neuroselective current perception threshold evaluation of bladder mucosal sensory function.

OBJECTIVE: To evaluate human bladder mucosal sensory function by neuroselective Current Perception Threshold (CPT) measures from healthy and neuropathic bladders. METHODS: Eight healthy volunteers and 38 patients with urinary symptoms underwent conventional urodynamic tests including water-filling cystometry and ice water test. Standardized neuroselective CPT measures were obtained from the left index finger and the mucosa of the posterior bladder wall. Three different CPTs were obtained from each test site using a constant alternating current sinusoid waveform electrical stimulus presented at 2000Hz, 250Hz and 5Hz stimulation frequencies, which could selectively reflect the functions of the large myelinated fibers (A-beta-fiber), the small myelinated fibers (A-delta-fiber), and the unmyelinated fibers (C-fiber), respectively. RESULTS: As the determination of CPT values on the finger skin, the CPT values in the bladder could be determined using the neuroselective measures in all patients but three who had no sensory response (absence of sensation) caused by complete spinal injury. In the 8 patients with detrusor hyperreflexia due to incomplete spinal cord injury (supra-sacral lesion), the bladder CPT value (4.0+/-1.9) at 5Hz was significantly lower (p<0.01) than that in the controls (26.2+/-17.7). In the neurogenic bladders determined to be underactive (n=11, including post pelvic surgery, post infra-sacral level spinal cord injury and diabetes patients), the higher CPT values of bladder mucosal sensory functions were found at 5Hz (p<0.05), 250Hz (p=0.07), and 2000Hz (p<0.05) compared to the controls. CONCLUSIONS: Quantitative neuroselective measurement of CPT values in the human bladder mucosal function was feasible. Hypersensitivity or hyposensitivity of the urinary sensory function could be determined using the CPT values in comparison to control. The quantitative neuroselective estimation of the bladder sensory functions in different types of sensory peripheral nerve fibers may contribute to the appropriate selection of therapeutic strategy in patients with urinary sensory dysfunction.

Adult↗

PubMed2004

Possible contribution of prostatic anterior fibromuscular stroma to age-related urinary disturbance in reference to pressure-flow study.

Recently, we reported that the anterior fibromuscular stroma (AFMS) of the prostate has significant different innervation compared with the other glandular regions of the prostate. In healthy volunteers (n = 12) using transrectal ultrasound (US), or TRUS, monitoring during voiding, we observed dynamic change (p < 0.0001) of the thickness of the AFMS during voiding. The aim of this study was to reveal the possible functional contribution of the AFMS to micturition, as well as the age-related voiding dysfunction. In the patients (n = 56) with voiding dysfunction who underwent both pressure-flow study (PFS) for determining obstruction and TRUS monitoring during voiding, we measured the ultrasonic dynamic change of the lower urinary tract during voiding. In old men with voiding dysfunction, ultrasonic measurements of dynamic change in the AFMS (p < 0.01) as well as the opening urethra (p < 0.05) could contribute to diagnosing of the anatomical localization of obstructive lesions. The poor movement of AFMS could account for the age-related urinary disturbance in the patients without benign prostatic enlargement and without bladder neck obstruction.

Aged↗

PubMed2004

[A case of young adult presenting with cerebral infarction caused by homocystinuria].

Homocystinuria is a congenital metabolic disorder, and has been known as life-threatening risk factor of vascular disease including ischemic stroke. We report a case of cerebral infarction due to homocystinuria. The patient was a 21-year-old woman exhibiting left hemiparesis and a previous history of ectopia lentis. Magnetic resonance imaging showed multiple fresh infarctions in the right frontal and temporal lobes, basal ganglia, corona radiata, and internal capsule. The right common carotid angiogram demonstrated complete occlusion at the origin of the right internal carotid artery. Further investigation clarified increased level of serum methionine and homocysteine and urinary homocystin due to cystathionine beta-synthase deficiency. Homocystinuria was diagnosed as the cause of cerebral infarction. The patient was treated by low methionine diet and administration of folic acid, cobalamin, and aspirin. It should be recognized that some patients with homocystinuria are missed in the neonatal screening for congenital metabolic disorders. Recent studies indicated that the homocysteinemia is one of risk factors of ischemic stroke in the general population as well as in the patients of homocystinuria. We recommend metabolic screening for homocystinuria, when treating a juvenile patient with ischemic stroke of unknown etiology.

Adult↗

PubMed2003

An event-related fMRI study of explicit syntactic processing of normal/anomalous sentences in contrast to implicit syntactic processing.

Using event-related functional magnetic resonance imaging (fMRI), we examined activation of cortical language areas for explicit syntactic processing. In a syntactic decision (Syn) task, the participants judged whether the presented sentence was syntactically correct, where syntactic knowledge about the distinction between transitive and intransitive verbs was required. In a semantic decision (Sem) task, lexico-semantic knowledge about selectional restrictions was indispensable. In a phonological decision (Pho) task, phonological knowledge about accent patterns was required. The Sem and Pho tasks involved implicit syntactic processing, as well as explicit semantic and phonological processing, respectively. We also tested a voice-pitch comparison (Voi) task in which no explicit linguistic knowledge was required. In the direct comparison of Syn - (Sem + Pho + Voi), we found localized activation in the left inferior frontal gyrus (F3op/F3t), indicating that activation of the left F3op/F3t is more prominently enhanced in explicit syntactic processing than in implicit syntactic processing. Moreover, we determined that its activation is selective to syntactic judgments regarding both normal and anomalous sentences. These results suggest that explicit information processing in the syntactic domain critically involves the left F3op/F3t, which is functionally separable from other regions.

Acoustic Stimulation↗

PubMed2003

Enzymatic preparation of ginsenosides Rg2, Rh1, and F1.

During investigation of the hydrolysis of a protopanaxatriol-type saponin mixture by various glycoside hydrolases, crude preparations of beta-galactosidase from Aspergillus oryzae and lactase from Penicillium sp. were found to produce two minor saponins, ginsenoside Rg(2) [6-O-(alpha-L-rhamnopyranosyl-(1-->2)-beta-D-glucopyranosyl)-20(S)-protopanaxatriol] and ginsenoside Rh(1) (6-O-beta-D-glucopyranosyl-20(S)-protopanaxatriol), respectively, in high yields. Moreover, a naringinase preparation from Penicillium decumbens readily gave an intestinal bacterial metabolite, ginsenoside F(1) (20-O-beta-D-glucopyranosyl-20(S)-protopanaxatriol), as the main product, with a small amount of 20(S)-protopanaxatriol from a protopanaxatriol-type saponin mixture. Also, a hesperidinase from Penicillium sp. selectively hydrolyzed ginsenoside Re into ginsenoside Rg(1). This is the first report on the enzymatic preparation of minor saponins, ginsenosides Rg(2) and Rh(1), and of an intestinal bacterial metabolite, ginsenoside F(1), with high efficiency from a protopanaxatriol-type saponin mixture.

Enzyme Activation↗