Biomedical subjects

T Yuasa

Publications and source records attributed to T Yuasa.

At least 55 records · Page 3Linked to original sources

PubMed2000

Diurnal variation in the P300 component of human cognitive event-related potential.

Diurnal variation in the P300 component of the human cognitive event-related potential (ERP) was examined. The P300 component is considered to be a measure of neuroelectric activity related to cognitive functions such as attention allocation and information processing. Nine diurnally active healthy male subjects whose sleep-wake rhythms were synchronized prior to the experiment were studied. The P300 components oral temperature, heart rate, left- and right-hand grip strength, reaction time, subjectively rated sleepiness, attention level, and fatigue were measured at 08:00, 11:00, 14:00, 17:00, and 20:00. Significant diurnal variations in P300 latency, P300 amplitude, oral temperature, heart rate, left- and right-hand grip strength, subjectively rated sleepiness, and attention level were observed. The P300 latency at 08:00 was significantly longer than at 11:00, 17:00, and 20:00, while the P300 amplitude at 08:00 was significantly greater than at 17:00 and 20:00. The P300 latency was correlated positively with subjectively rated sleepiness and negatively correlated with subjectively rated attention level. These results suggest the existence of diurnal variation in human cognitive functions.

Adult↗

PubMed2000

Circadian rhythm abnormalities of wrist activity of institutionalized dependent elderly persons with dementia.

BACKGROUND: The study objective was to clarify the descriptive characteristics of circadian rhythm abnormalities of wrist activity of the institutionalized elderly with dementia. METHODS: We studied 82 elderly persons with dementia who were institutionalized in a long-term medical care facility. The ambulatory continuous monitoring of their wrist activity was conducted for 7 days at 1-minute intervals. The time series data were analyzed using the double-plotted chronogram, spectral analysis was performed using the fast Fourier transformation and periodogram analysis was performed as well. RESULTS: The frequency of circadian rhythm abnormalities of wrist activity rhythm in elderly persons with dementia was 57.3% (47 out of 82). The abnormalities were classified into four categories: severely impaired circadian rhythm type with no boundary between day and night, free-running rhythm type, decreased circadian amplitude type, and accentuation of ultradian rhythm type. CONCLUSION: This four-category classification system provides a scientific approach for studying the mechanisms of circadian activity rhythm abnormalities of elderly persons with dementia.

Activity Cycles↗

PubMed2000

Low-dose atropine attenuates muscle sympathetic nerve activity in healthy humans.

Central muscarinic receptors play an important role in the regulation of cardiac vagal nerve activity. We studied the inhibition of central muscarinic receptors and sympathetic nerve function in humans, since very little information is currently available on this subject. We examined the effects of graded doses of atropine (five doses, range 0.001 to 0.016 mg/kg) on heart rate, arterial pressure, heart rate variability, and muscle sympathetic nerve activity in 13 healthy young volunteers. Atropine caused biphasic effects on heart rate and the high-frequency (HF) power of R-R interval variability. At lower doses (< or =0.002 mg/kg for heart rate, 0.001 mg/kg for HF power), atropine decreased heart rate and increased HF power. In contrast, at higher doses, atropine increased heart rate and decreased HF power. Low-dose atropine significantly attenuated muscle sympathetic nerve activity, burst rate (bursts/min) by -30.5 +/- 6.0% and burst incidence (bursts/100 heart beats) by -23.8 +/- 6.9% at 0.002 mg/kg. Systolic and diastolic arterial pressure did not change with atropine infusion. Low-dose atropine (< or =0.002 mg/kg) did not significantly affect either low frequency (LF) power or LF/HF. These results suggest that central muscarinic receptors may modulate not only cardiac vagal nerve activity but also sympathetic nerve activity in the skeletal muscle vasculature.

Adult↗

PubMed2000

Hedgehog proteins stimulate chondrogenic cell differentiation and cartilage formation.

Sonic hedgehog (Shh) and Indian hedgehog (Ihh) are important regulators of skeletogenesis, but their roles in this complex multistep process are not fully understood. Recent studies have suggested that the proteins participate in the differentiation of chondrogenic precursor cells into chondrocytes. In the present study, we have tested this possibility more directly. We found that implantation of dermal fibroblasts expressing hedgehog proteins into nude mice induces ectopic cartilage and bone formation. Immunohistological and reverse-transcription polymerase chain reaction (RT-PCR) analyses revealed that the ectopic tissues derived largely if not exclusively from host cells. We found also that treatment of clonal prechondrogenic RMD-1 and ATDC5 cells in culture with Ihh or recombinant amino half of Shh (recombinant N-terminal portion of Shh [rShh-N]) induced their differentiation into chondrocytes, as revealed by cytoarchitectural changes, Alcian blue staining and proteoglycan synthesis. Induction of RMD-1 cell differentiation by Ihh or rShh-N was synergistically enhanced by cotreatment with bone morphogenetic protein 2 (BMP-2) but was blocked by cotreatment with fibroblast growth factor 2 (FGF-2). Our findings indicate that hedgehog proteins have the ability to promote differentiation of chondrogenic precursor cells and that their action in this process can be influenced and modified by synergistic or antagonist cofactors.

Animals↗

PubMed2000

Reliability and validity of the questionnaire to determine the biosocial rhythms of daily living in the disabled elderly.

The questionnaire to determine the biosocial rhythms of daily living in the disabled elderly was newly developed. This questionnaire was aimed to evaluate a state of synchronization of biological rhythms in the disabled elderly. Eighteen items of the questionnaire relating to the synchronization of biological rhythms were finally selected by the test-retest method that was conducted for 68 disabled elderly living in a community with a duration of one year. The factor analysis showed that the questionnaire consisted of five factors: outdoor activities, ultradian rhythms, subjective evaluation of health status, social support, and sleep habits. The cumulative contribution rate of five factors was 53.2%. Reliability of the questionnaire was confirmed by a calculation of the Equal-length Spearman-Brown coefficients ranging from 0.60 to 0.80. Regarding the construct validity of the questionnaire, results of factor analysis showed five factors that were consistent with the synchronizers known in chronobiology. The total score of the questionnaire was significantly correlated to Barthel Index score and the competence score, suggesting that it partly reflects the activities of daily living of the disabled elderly. We conclude that a new questionnaire to determine the biosocial rhythm of daily living in the disabled elderly is useful to evaluate the biosocial synchronization of the disabled elderly because of its high reliability and validity.

Activities of Daily Living↗

PubMed2000

Blood lead level to induce significant increase in urinary delta-aminolevulinic acid level among lead-exposed workers: a statistical approach.

The present study was initiated to examine the quantitative relationship between blood lead (Pb-B) and urinary delta-aminolevulinic acid (ALA-U) among Pb-exposed workers, and to find a threshold Pb-B level to induce an increase in ALA-U. For this purpose, pairs of venous blood and spot urine samples were collected from 8,274 men and 5,856 women (14,130 workers in total) who were occupationally exposed to inorganic lead. The blood and urine samples were analyzed for Pb-B and ALA-U by atomic absorption spectrometry and colorimetry, respectively, and the correlation between pairs of measures were subjected to statistical analysis. The assumption of the 3rd degree regression for correlation gave a substantially greater correlation coefficient (0.645 for men and 0.619 for women) than 1st or 2nd degree regression, whereas only very small improvement in the coefficient was achieved with 4th to 6th degree ones. Logarithmic conversion of the parameters was not effective in improving the correlation. The assumption of the 3rd degree regression followed by calculation of the local minimum gave 22, 29 and 23 micrograms/100 ml Pb-B for men, women, and men + women, respectively, as the threshold Pb-B to induce ALA-U increase. Pb-B to elevate ALA-U to the 95% upper normal limit (8 mg/l, common to men and women) was 62, 50 and 58 micrograms/100 ml for men, women and men + women, respectively. The validity of the 3rd degree regression assumption as a tool to calculate a threshold from experimental or epidemiological data is discussed.

Adult↗

PubMed2000

Effects of capsaicin-containing yellow curry sauce on sympathetic nervous system activity and diet-induced thermogenesis in lean and obese young women.

The present study was designed to investigate the effect of capsaicin, a pungent component of red pepper, on the sympathetic nervous system (SNS) activity and energy metabolism in 16 age- and height-matched lean and obese young women. The sympatho-vagal activities were assessed by means of spectral analysis of heart rate variability (HRV) during the resting condition and after the meal (2,016 kJ) with capsaicin (3 mg). Energy expenditure was also measured under the two conditions. There was no significant difference in any of the parameters of the HRV between the obese and control groups at rest. After the capsaicin diet, however, the very low frequency component (0.007-0.035 Hz) associated with thermogenesis (315.8+/-78.0 vs. 814.8+/-211.7 ms2 x Hz(-1), p<0.05) as well as its responsiveness (delta changes: 14.6+/-104.4 vs. 369.2+/-121.7 ms2 x Hz(-1), p<0.05) were significantly lower in the obese than the control group. Energy expenditure was significantly increased in the control group after the meal (5,574.7+/-221.2 to 6,114.7+/-239.0 kJ day(-1); p<0.01), but no such significant thermogenic response was detected in the obese group despite nearly identical lean body mass of the control group. Our data indicate that regardless of the resting level of sympatho-vagal activities, the reduced sympathetic responsiveness to physiological perturbation such as a capsaicin diet, which may cause impaired diet-induced thermogenesis and further weight gain, could be an important etiological factor leading to obesity in young women.

Absorptiometry, Photon↗

PubMed2000

[Renal cell carcinoma in acquired cystic disease of the kidney manifested by spontaneous renal hemorrhage].

Acquired cystic disease of the kidney (ACDK) is a common phenomenon in long-term adult dialysis patients with end-stage renal disease. Renal hemorrhage and neoplastic transformation of the cyst are two major complications of this entity and these two can occur independently. Here we describe a 65-year-old man with a history of hemodialysis-dependent end-stage renal failure for 12 years presented with macroscopic hematuria and right flank pain. Investigations revealed right massive perirenal and subcapsular hematoma with ACDK. The hemorrhagic state required nephrectomy of the right kidney. Histological study showed ACDK with massive subcapsular and perinephric hematoma containing minimal clear cell carcinoma region(0.5 cm in diameter). Although a causal relationship between renal hemorrhage and renal cell carcinoma in this patient was unproven, the present case suggests radical surgery can be a recommendable treatment modality of hemorrhagic ACDK.

Aged↗

PubMed2000

Overexpression of wild-type Akt1 promoted insulin-stimulated p70S6 kinase (p70S6K) activity and affected GSK3 beta regulation, but did not promote insulin-stimulated GLUT4 translocation or glucose transport in L6 myotubes.

We have developed a simple, direct and sensitive method to detect GLUT4 on the cell surface. Using this system, we found that PI3-kinase plays a key role in the signaling pathway of insulin-stimulated GLUT4 translocation. One of the down stream effectors of PI3-kinase is serine-threonine kinase Akt (protein kinase B, RAK-PK), but the involvement of Akt in insulin-stimulated GLUT4 translocation is controversial. To investigate whether Akt1 regulates insulin-stimulated GLUT4 translocation and glucose uptake in L6 myotubes, we established L6 myotubes stably expressing c-myc epitope-tagged GLUT4 (GLUT4myc) and mouse wild type (WT) Akt1. We found that overexpression of WT Akt1 promoted insulin-stimulated p70S6 kinase (p70S6K) activity and increased the basal activity of GSK3 beta, but did not promote insulin-stimulated GLUT4 translocation or glucose uptake. These data supported the result that Akt is not a main signaling molecule to transmit the signal of insulin-stimulated GLUT4 translocation or glucose uptake from insulin-activated PI3-kinase.

Amino Acid Sequence↗

PubMed2000

Novel mutations, pseudo-dominant inheritance, and possible familial affects in patients with autosomal recessive juvenile parkinsonism.

Autosomal recessive juvenile parkinsonism is a hereditary neurodegenerative disorder, usually beginning before the age of 40. We found three exonic deletions and two novel point mutations (Arg33Stop and Cys431Phe) in six families with autosomal recessive juvenile parkinsonism. In 1 family, in which an autosomal dominant mode of inheritance was suspected, multiple mutant alleles were identified. Although a wide range of ages at onset was observed, there was no correlation between age at onset and genotype.

Adolescent↗

PubMed2000

Detection of circulating cancer cells by reverse transcription-polymerase chain reaction for uroplakin II in peripheral blood of patients with urothelial cancer.

Few attempts have been made at the molecular detection of urothelial cancer cells in the blood or lymph nodes mainly because of an absence of good candidate molecular or genetic changes specific to urothelial cancer or urothelium. In 1990, however, genes that encode urothelium-specific transmembrane proteins, uroplakins (UPs), were cloned. We have established a method of detecting circulating cancer cells in peripheral blood of patients with transitional cell carcinoma by nested reverse transcription-PCR assay for UP II. UP II mRNA-positive cells were detected in 3 (10.3%) of 29 patients with superficial cancers (pTa-1N0M0), 4 (28.6%) of 14 patients with muscularly invasive cancers (pT2-4N0M0), 2 (40.0%) of 5 loco-regional node-positive patients (pN1-2M0), and 6 (75.0%) of 8 patients with distant metastases. Positive rates, therefore, increased with tumor extension (P = 0.0033, Kruskal-Wallis test). Furthermore, sequential blood sampling was performed in three patients with metastases during and after systemic chemotherapy, and UP-II-positive cells were found to have disappeared in two patients who responded well to the systemic chemotherapy. These results suggest that our nested reverse transcription-PCR assay for UP II is highly specific and might be used as a tumor marker for molecular staging of urothelial cancers, although the sensitivity is not so optimal.

Adult↗

PubMed2000

New types of X-ray computed tomography (CT) with synchrotron radiation: fluorescent X-ray CT and phase-contrast X-ray CT using interferometer.

New types of X-ray computed tomography (CT), fluorescent X-ray CT and phase-contrast X-ray CT are being developed for biomedical research. While fluorescent scanning X-ray CT (FXCT) can detect specific contrast elements, or endogenous iodine, at very low content (less than 400 pg iodine of tissue in a volume of 8 x 10(-6) ml), the phase-contrast X-ray CT (PCCT) is a highly sensitive imaging technique to differentiate between different biological tissue types (based on their specific gravity variation) without the use of a contrast agent. Therefore, we can expect functional diagnosis with FXCT, and high contrast, high resolution biological imaging with PCCT. In this paper, a human thyroid gland imaged by FXCT, and a metastatic human cancerous lesion depicted using PCCT are presented. The latter method used a newly manufactured, large, monolithic, X-ray interferometer, which is described in this paper in detail.

Colonic Neoplasms↗

PubMed2000

[Therapeutic strategies for Parkinson's disease and guidelines for the 21st century].

Parkinson's disease(PD) is one of the most common neurodegenerative disorders, characterized clinically by resting tremor, rigidity and akinesia. The pathological hallmarks of PD is the loss of neurons of the substantia nigra and the existence of Lewy bodies. Among multifactorial theories of gene-environment interaction supporting the pathogenesis of this disease, recent topics focus on the findings of single gene mutations found in several forms of familial PDs. The mutations of the gene encode the protein alpha-synuclein, UCH-L1 and Parkin located on the chromosomes 4q21-23, 4p and 6p25.2-27 respectively. Molecular pathology and histochemical studies reveal that one of these proteins is closely associated with parts of Lewy bodies, or has the function of the ubiqitin system of protein metabolism. Although the typical PD shows good response to levodopa therapy, its side effects, which arise after 5 to 10 years of treatment, rather narrow the therapeutic window of PD. As a result we must make available various new therapeutic tools in order to prevent disability and get a favourable QOL in the PD patient's life span. The various tools adopted here include surgical treatments, transcraial magnetic stimulation methods, nonconvulsive electric stimulation therapy, and the design of new drugs. In this issue the frontier of PD therapy and research will be reviewed and new promising insights and guidelines for the current century will be discussed.

Forecasting↗

PubMed2000

[Clinical criteria for the diagnosis for PSP].

In attempts to improve the accuracy of its clinical identification, investigators have proposed numerous diagnostic criteria for progressive supranuclear palsy(PSP). We compared with six different sets of previously published criteria for the clinical diagnosis of PSP. Among of them, the NINDS-SPSP criteria are a most prominent diagnostic standard. But in the clinical area, the NINDS-SPSP criteria have some weak point. We plan to make up this point for using the neuroimaging techniques.

Humans↗

PubMed2000

[Parkinson's disease and depression].

Up to 40% of cases of Parkinson's disease are associated with the occurrence of depression. The symptoms of the patients' depressive state may be factors such as significant weight change, insomnia or hypersomnia, psychomotor retardation, fatigue or loss of energy, feelings of worthlessness or inappropriate guilt, decreased concentration and indecisiveness, and recurrent thoughts of death or suicidal ideation. Given these conditions, drugs prove ineffective in many cases. Electroconvulsive therapy (ECT) has been reported to be beneficial in cases of drug-resistant depression. ECT has also been applied to Parkinsonian patients with depression and found to be effective with both depression and the Parkinsonian symptom. Transcranial magnetic stimulation(TMS) has recently been investigated for application in cases of depression and has become known as a valuable tool for depression therapy. TMS is easily implemented even in outpatient therapy. TMS will make a great contribution to the therapy of depression with Parkinson's disease.

Depression↗

PubMed1999

Stimulatory function of paired immunoglobulin-like receptor-A in mast cell line by associating with subunits common to Fc receptors.

Paired Ig-like receptors (PIR) are polymorphic type I transmembrane proteins belonging to an Ig superfamily encoded by multiple isotypic genes. They are expressed on immune cells such as mast cells, macrophages, and B lymphocytes. Two subtypes of PIR have been classified according to the difference in the primary structure of the PIR transmembrane and cytoplasmic regions. These subtypes are designated as PIR-A and PIR-B. In this study, the transmembrane and cytoplasmic regions of the PIR-A subtype were shown to mediate activation signal events such as cytoplasmic calcium mobilization, protein tyrosine phosphorylations, and degranulation in rat mast cell line RBL-2H3. The association of the Fc receptor gamma and beta subunits with PIR-A was shown to be responsible for PIR-A function but not required for membrane expression of PIR-A on COS-7 cells. We further revealed the role of two charged amino acid residues in the transmembrane region, namely arginine and glutamic acid, in PIR-A function and its association with the above subunits. In contrast to the inhibitory nature of the PIR-B subtype, present findings reveal that PIR-A potentially acts as a stimulatory receptor in mast cells, suggesting a mechanism for regulation of mast cell functions by the PIR family.

Amino Acid Sequence↗

PubMed1999

Fission yeast condensin complex: essential roles of non-SMC subunits for condensation and Cdc2 phosphorylation of Cut3/SMC4.

The condensin complex in frog extracts, containing two SMC (structural maintenance of chromosomes) and three non-SMC subunits, promotes mitotic chromosome condensation, and its supercoiling activity increases during mitosis by Cdc2 phosphorylation. Here, we report that fission yeast has the same five-member condensin complex, each of which is essential for mitotic condensation. The condensin complex was purified and the subunits were identified by microsequencing. Cnd1, Cnd2, and Cnd3, three non-SMC subunits showing a high degree of sequence conservation to frog subunits, are essential for viability, and their gene disruption leads to a phenotype indistinguishable from that observed in cut3-477 and cut14-208, known mutations in SMC4 and SMC2-like subunits. Condensin subunits tagged with GFP were observed to alter dramatically their localization during the cell cycle, enriched in the nucleus during mitosis, but cytoplasmic during other stages. This stage-specific alteration in localization requires mitosis-specific phosphorylation of the T19 Cdc2 site in Cut3. The T19 site is phosphorylated in vitro by Cdc2 kinase and shows the maximal phosphorylation in metaphase in vivo. Its alanine substitution mutant fails to suppress the temperature-sensitive phenotype of cut3-477, and shows deficiency in condensation, probably because Cut3 T19A remains cytoplasmic. Therefore, direct Cdc2 phosphorylation of fission yeast condensin may facilitate its nuclear accumulation during mitosis.

Amino Acid Sequence↗

PubMed1999

Detection of circulating testicular cancer cells in peripheral blood.

Patients who receive peripheral blood stem cell transplants are at risk of developing cancer recurrence due to the presence of malignant cells in the transplants. We investigated a sensitive method to detect malignant cells in the peripheral blood and peripheral blood stem cells of patients with testicular cancer using nested, reverse transcription-polymerase chain reaction (RT-PCR) to measure alpha-fetoprotein gene expression. Using this technique, a single cancer cell could be detected in 10(6) peripheral blood mononuclear cells. This is the first report of an attempt to detect circulating malignant cells in the peripheral blood of patients with testicular cancer by nested RT-PCR.

Actins↗