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Biomedical subjects

Yuji Suzuki

Publications and source records attributed to Yuji Suzuki.

9 recordsLinked to original sources
PubMed2003

Absolute eigenvalue diffusion tensor analysis for human brain maturation.

The absolute eigenvalues of the diffusion tensor of white matter in sixteen normal subjects in two groups representing the early developmental stage (ages 1-10 years, n=8) and young adult stage (ages 18-34 years, n=8) were assessed using a high-field (3.0 T) magnetic resonance (MR) system. All three eigenvalues, including the largest eigenvalue, decreased significantly with brain maturation. The rate of the decline in the two small eigenvalues was, however, much higher than that of the largest eigenvalue, resulting in an actual increase in fractional anisotropy, a commonly measured relative index. The data demonstrate that an increase in anisotropy associated with brain maturation represents a significant decline in the small eigenvalue components, rather than an increase in the largest eigenvalue. The observed pattern of eigenvalue changes is best explained by the simultaneous occurrence of two of several independent phenomena within the axonal microenvironment during the myelination process, namely, (1) decline in unrestricted water content in extra-axonal space, and (2) increase in apparent diffusivity within the axon.

Adolescent↗
PubMed2003

Feasibility study of single region lambda chart analysis for pyramidal tract physiology.

Diffusion characteristics of the pyramidal tract were assessed in nine patients who had clinical evidence of pyramidal tract dysfunction, utilizing lambda chart analysis (LCA). The underlying pathologic process of tract dysfunction was varied and included Pelizaeus-Merzbacher disease (PMD), Alexander disease, adrenoleukodystrophy (adrenomyeloneuropathy (AMD) type and cerebral type), amyotrophic lateral sclerosis (ALS), and Wallerian degeneration (WD). While pyramidal tract diffusion characteristics in WD indicated a pathological process characterized by replacement of normal fibers by smaller cellular component such as degenerated small fibers and/or gliosis, pyramidal tract diffusion characteristics in patients with PMD, Alexander disease, and adreno leukodystrophy of the cerebral type indicated a pathological process characterized by replacement of normal fibers by larger cellular components such as spheroids or edematous space. Pyramidal tract diffusion characteristics of patients with ALS or adrenoleukodystrophy of AMD type were relatively intact suggesting a pathological process characterized by relatively preserved structural architecture. These findings are highly consistent with known pathophysiological indices and indicate the feasibility of the clinical utility of LCA for assessing pyramidal tract physiology.

Adolescent↗
PubMed2003

Alteration of citrate metabolism in cluster roots of white lupin.

Organic acid excretion plays a key role in the superior P(i)-acquisition of barely soluble inorganic P sources from soils. Seedlings of white lupin (Lupinus albus L.) grown for 37 d in -P nutrient solution showed typical -P symptoms, such as low P content, increased root/shoot ratio and the development of cluster roots which released large amounts of citrate. Citrate concentration in the cluster roots was 21.5 micro mol (g FW)(-1), which corresponded to a 4.3- and 2.6-fold increase of +P and -P root apexes, respectively. Cluster roots possessed higher phosphoenolpyruvate carboxylase and phosphoenolpyruvate phosphatase activity than those in +P root apexes, which could result in increasing the supply of substrate for citrate synthase. On the other hand, the cytosolic pathway which converts citrate to 2-oxoglutarate consists of aconitase and NADP-specific isocitrate dehydrogenase activity that was lower in the cluster roots than in +P root apexes, and may contribute to citrate accumulation. Thus, metabolic balance with these alterations would play an important role in increasing citrate concentration in the cluster roots. The molecular characterization of NADP-specific isocitrate dehydrogenase indicated that the cytosolic isoenzyme functions as a hetero-dimer, and that the activity would be regulated by the transcript levels for both isoforms.

Base Sequence↗
PubMed2003

Effects of lidocaine into knee on QF strength and EMG in patients with ACL lesion.

PURPOSE: In our previous study, we found that injection of lidocaine into intact knees reduced the maximal voluntary contraction (MVC) and integrated electromyogram (I-EMG) of the quadriceps femoris (QF). This study was designed to investigate changes in the MVC and I-EMG of the QF in response to lidocaine, in patients with anterior cruciate ligament (ACL) lesion, to evaluate alpha-motoneuron activity innervating the QF. METHODS: The MVC of knee extension and I-EMG of the vastus medialis (VM), vastus lateralis (VL), and rectus femoris (RF) muscles were measured in eight patients with ruptured ACL, before and after lidocaine injection into the knee. RESULTS: There were no significant differences between preinjection and postinjection values of MVC (preinjection: 167 +/- 49 N.m; postinjection: 164 +/- 55 N.m) and I-EMG (preinjection: VL: 0.11 +/- 0.06, VM: 0.13 +/- 0.10, RF: 0.09 +/- 0.04) (postinjection: VL: 0.12 +/- 0.07, VM: 0.13 +/- 0.10, RF: 0.09 +/- 0.05). CONCLUSION: Our results indicated that hindrance of afferent feedback from the knee in patients with ACL rupture did not significantly change alpha-motoneuron activity. Lidocaine injection into the knee joint of the subjects in this study only attenuated afferent feedback from mechanoreceptors in the knee joint cavity, but not in the ACL, as afferent feedback from ACL was already lost due to ACL rupture. This indicated that attenuation of afferent feedback from mechanoreceptors in the knee joint cavity other than the ACL did not significantly decrease the activity of alpha-motoneurons innervating the QF during MVC exertion. Therefore, our findings provide evidence that afferent feedback from the ACL has a major influence on the MVC exertion of the QF.

Adolescent↗
PubMed2002

High-energy, all-solid-state, ultraviolet laser power-amplifier module design and its output-energy scaling principle.

We demonstrate that a coaxially pumped, large-aperture ultraviolet power-amplifier module with solid-state tunable laser medium Ce(3+):LiCaAlF6 has 98-mJ, 290-nm, and 3-ns output pulses with a sufficient extraction efficiency of 25%. The detailed information of design parameters, including the gain-coefficient dependence on pump condition, is successfully accumulated for further energy scaling for a terawatt-class ultraviolet chirped pulse amplification laser system or a high-pulse-energy laser system.

Journal Article↗
PubMed2002

Generation and characterization of human hybrid neurons produced between embryonic CNS neurons and neuroblastoma cells.

A human hybrid neuronal cell line A1 has been generated by somatic fusion between a human fetal cerebral neuron and a human neuroblastoma cell, and RT-PCR, immunochemical, and electrophysiological studies of the hybrid cells indicated that the cells express faithfully of morphological, immunochemical, physiological, and genetic features of human cerebral neurons. A1 hybrid neurons express neuron-specific markers such as neurofilament-L (NF-L), NF-M, NF-H, MAP-2, and beta tubulin III. A1 human hybrid neurons express messages for various cytokines and cytokine receptors which are similar to parental human CNS neurons and different from the other parental cell line, SK-SH-SY5Y neuroblastoma. A1 hybrid neurons also express messages for choline acetyltransferase (ChAT), tyrosine hydroxylase (TH), and glutamic acid decarboxylase (GAD), indicating that they could differentiate into various subsets of neuronal types. Whole-cell patch clamp experiments showed that A1 hybrid neurons expressed Na+ currents, which were completely blocked by tetrodotoxin. In addition, depolarizing and hyperpolarizing voltage clamp steps evoked respective outward and inward K+ currents in these cells. When A1 hybrid neurons were exposed to beta amyloid for 72 hr, there was three-fold increase in TUNEL positive cells over controls, indicating that beta amyloid is neurotoxic to A1 hybrid neurons. The present study indicates that the A1 human hybrid neuronal cell line should serve as a valuable in vitro model for studies of biology, physiology, and pathology of human neurons in health and disease.

Amyloid beta-Peptides↗
PubMed2002

Prognostic value of 2-deoxy-2-[F-18]fluoro-D-glucose positron emission tomography imaging for patients with prostate cancer.

PURPOSE: The purpose of this study was to investigate the prognostic value of measuring glucose metabolism of primary prostate cancer lesions, using 2-Deoxy-2-[F-18]Fluoro-D-Glucose positron emission tomography (FDG-PET). PROCEDURES: Forty-two patients with prostate cancer were investigated with FDG-PET, and standardized uptake value (SUV) of the prostate was calculated. After PET study, radical prostatectomy was performed in 17 patients (RPT group), and endocrine therapy in 25 patients (ET group). Relapse-free survival curves were created by the Kaplan-Meier method. RESULTS: In the RPT group, the patients with high SUV had a poorer prognosis compared to those with low SUV (P = 0.033). In the ET group, the patients with high SUV were likely to have a poorer prognosis with low significance at a level of P = 0.087. CONCLUSIONS: FDG-PET appeared to have a defined prognostic value for patients with prostate cancer undergoing radical prostatectomy, and more patients need to be studied for patients undergoing endocrine therapy.

Journal Article↗
PubMed2002

11C-acetate PET imaging of prostate cancer.

UNLABELLED: 11C-Acetate can act as a probe of tissue metabolism through entry into catabolic or anabolic metabolic pathways as mediated by acetyl-coenzyme A. The uptake of (11)C-acetate in prostate cancer was investigated to determine whether this tracer has potential in tumor identification. METHODS: Twenty-two patients with prostate cancer underwent PET after intravenous administration of 740 MBq (11)C-acetate. Eighteen of the 22 patients were also investigated with (18)F-FDG PET. Standardized uptake values (SUVs) for each tumor were investigated for tracer activity at 10-20 min after (11)C-acetate and 40-60 min after (18)F-FDG administration. RESULTS: Adenocarcinoma of the prostate showed variable uptake of (11)C-acetate, with SUVs ranging from 3.27 to 9.87. In contrast, SUVs for (18)F-FDG ranged from 1.97 to 6.34. By visual inspection, (11)C-acetate accumulation in primary prostate tumors was positive in all patients, whereas (18)F-FDG accumulation was positive in only 15 of 18 patients. (11)C-Acetate PET in a patient with lymph node metastasis showed high intrapelvic accumulation corresponding to metastatic sites. Similarly, 2 patients with bone metastases were (11)C-acetate avid. CONCLUSION: (11)C-Acetate shows marked uptake in prostate cancer and is more sensitive in detection of prostate cancer than is (18)F-FDG PET. (11)C-Acetate represents a new tracer for detection of prostate cancer with PET, measuring radiopharmaceutical uptake pathways that are different from those measured by (18)F-FDG.

Acetates↗