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Biomedical subjects

K Yamada

Publications and source records attributed to K Yamada.

At least 127 records · Page 7Linked to original sources
PubMed2002

Freezing of a stripe liquid.

The existence of a stripe-liquid phase in a layered nickelate, La(1.725)Sr(0.275)NiO(4), is demonstrated through neutron scattering measurements. We show that incommensurate magnetic fluctuations evolve continuously through the charge-ordering temperature, although an abrupt decrease in the effective damping energy is observed on cooling through the transition. The energy and momentum dependence of the magnetic scattering are parametrized with a damped-harmonic-oscillator model describing overdamped spin waves in the antiferromagnetic domains defined instantaneously by charge stripes.

Journal Article↗
PubMed2002

Increase of transcriptional levels of egr-1 and nur77 genes due to both nicotine treatment and withdrawal in pheochromocytoma cells.

The influence of nicotine on the expression of egr-1 and nur77 genes by nicotine treatment and withdrawal was assessed using PC12 cells. Nicotine treatment significantly increased the amount of mRNA for egr-1 and nur77 genes at 0.5 h post-nicotine treatment in the PC12 cells. In addition, nicotine withdrawal also elevated transcriptional levels of egr-1 and nur77 genes in Northern blot analyses. Nicotine treatment (200 microM) was also found to significantly increase expressional levels of Egr-1 and Nur77 proteins at 0.5 h post-nicotine treatment. In contrast, Egr-1 and Nur77 protein levels were dramatically decreased by nicotine withdrawal. These results suggest that expressional levels of Egr-1 and Nur77 proteins in neural cells may affect the transcriptional activity of late-response genes after nicotine withdrawal.

Animals↗
PubMed2002

Inhibition of aromatase activity by green tea extract catechins and their endocrinological effects of oral administration in rats.

We orally administered polyphenone-60 (P-60), green tea extract catechins, in the diet (0, 1.25 and 5%) to male rats for 2, 4 and 8 weeks initiated at 5 weeks old. It was found that a 5% dose to male rats for 2-8 weeks induced goiters and decreased weights of the body, testis and prostate gland. Endocrinologically, elevating plasma thyroid stimulating hormone (TSH), luteinizing hormone (LH) and testosterone levels and decreasing tri-iodothyronine (T(3)) and thyroxine (T(4)) levels were induced by this treatment. We also found that P-60 as a whole and some of its constituents exhibited inhibitory effects on human placental aromatase activity by in vitro assay. The concentration of P-60 that required producing 50% inhibition of the aromatase activity (IC(50) value) was 28 microg/ml. The IC(50) values of (-)-catechin gallate (Cg), (-)-epigallocatechin (EGC), (-)-epigallocatechin gallate (EGCg) and (-)-gallocatechin gallate (GCg) were 5.5 x 10(-6), 1.0 x 10(-4), 6.0 x 10(-5) and 1.5 x 10(-5) M, respectively. (-)- Epicatechin gallate (ECg) at 1.0 x 10(-4) M produced 20% inhibition. (-)-Epicatechin (EC) and (+)-catechin (CT) exhibited no effects on aromatase activity. The endocrinological changes observed in vivo were in conformity with antithyroid effects and aromatase inhibition effects of P-60 and its constituents.

Administration, Oral↗
PubMed2002

Eradication of residual bcr-abl-positive clones by inducing graft-versus-host disease after allogeneic stem cell transplantation in patients with Philadelphia chromosome-positive acute lymphoblastic leukemia.

Persistence of bcr-abl transcripts after marrow grafting is thought to convey a high risk for relapse in patients with Philadelphia chromosome (Ph)-positive acute lymphoblastic leukemia (ALL). Donor leukocyte infusion (DLI) is closely associated with development of graft-versus-host disease (GVHD) and has well-defined activity against relapsed chronic myelogenous leukemia (CML) but not ALL. We report two patients with Ph-positive ALL who remained bcr-abl positive by reverse transcriptase polymerase chain reaction (RT-PCR) after marrow grafting. Residual bcr-abl transcripts in both patients were eliminated following acute GVHD, which was induced by either DLI or rapid reduction of immunosuppression. Both patients have continued in complete molecular remission for 18 months and 8 months following transplantation, respectively. Our observation suggests that induction of GVHD may eliminate minimal residual disease, thereby preventing leukemia relapse in patients transplanted for Ph-positive ALL.

Clone Cells↗
PubMed2002

Sequencing of the putative promoter region of the cocaine- and amphetamine-regulated-transcript gene and identification of polymorphic sites associated with obesity.

OBJECTIVE: We tested the hypothesis that polymorphisms in the cocaine- and amphetamine-regulated-transcript (CART) gene is associated with the development of obesity. SUBJECTS: Five-hundred and twenty-eight subjects (325 men and 203 women) aged 49.6+/-11.0 y with body mass index (BMI) of 26.9+/-5.1. MEASUREMENTS: The 5(')-flanking region of the CART gene was cloned using adaptor-ligated genomic DNA fragments. The CART gene including the 5(')-flanking region was screened for mutation by PCR-single strand conformation polymorphism and direct sequencing. Associations between polymorphisms and obesity were investigated by PCR-restriction fragment length polymorphism analysis and direct sequencing. RESULTS: The 5(')-flanking region of the CART gene up to -1072 bp from the transcription initiation site was sequenced. The region contained a putative cyclic AMP-responsive element and four E-box motifs upstream of a TATA box. Six polymorphic sites were identified in the upstream region; A-->G at -156, T-->C at -390, T-->G at -484, G-->T at -915, G-->C at -929 and C-->T at -962. The nucleotide substitution at -156 was significantly associated with greater BMI (P=0.036). The allele frequency of the -156 variant was significantly higher in obese subjects with BMI > or = 30 than in non-obese subject (0.41 vs 0.32, P=0.0076). The -929 variant allele in linkage disequilibrium with the -156 variant was also more common in obese subjects. No mutation was found in the coding regions. A single nucleotide insertion/deletion polymorphism at +1355 in the 3(') untranslated region was not associated with obesity. CONCLUSION: The 5(')-flanking region of the CART gene was highly polymorphic. The -156 polymorphism or polymorphisms in linkage disequilibrium with the site may be associated with genetic predisposition to obesity.

Base Sequence↗
PubMed2002

Role of bombesin (BN)-like peptides/receptors in emotional behavior by comparison of three strains of BN-like peptide receptor knockout mice.

Bombesin (BN)-like peptides are involved in the regulation of a wide variety of behaviors, such as spontaneous activity and feeding. We assessed the role of BN-like peptides/receptors in emotional and/or anxiety-related behavior using three strains of knockout mice, each deficient in a single BN-like peptide receptor (gastrin-releasing peptide receptor, bombesin receptor subtype-3, or neuromedin B receptor). Two representative behavioral paradigms, the light-dark (L-D) box test and the elevated plus maze test, were chosen for this purpose. In these two tests, the level of anxiety can be measured as the preference for exploring the light box, or the length of time spent in the open arms, respectively. By conventional parameters, the only significant finding was that BRS-3-deficient mice exhibited a longer duration of remaining in the open arms compared to the wild-type cohort (P < 0.01). However, analyses of risk assessment behavior revealed that BRS-3-deficient mice exhibited increased 'stretched attend posture' behavior (P < 0.01, compared to wild-type mice in both the L-D box and elevated plus maze tests) while NMB-R-deficient mice exhibited decreased behavior (P < 0.05, compared to wild-type mice in both tests). These results suggest that BN-like peptides/receptors may play a role in modulating emotion including some forms of anxiety (e.g., risk assessment behavior). Further, we found that the type of emotional behavior to which each of the peptide/receptor pathways contributes can be clearly specified.

Animals↗
PubMed2002

Association between serotonin 4 receptor gene polymorphisms and bipolar disorder in Japanese case-control samples and the NIMH Genetics Initiative Bipolar Pedigrees.

Possible irregularities in serotonergic neurotransmission have been suggested as causes of a variety of neuropsychiatric diseases. We performed mutation and association analyses of the HTR4 gene, on 5q32, encoding the serotonin 4 receptor in mood disorders and schizophrenia. Mutation analysis was performed on the HTR4 exons and exon/intron boundaries in 48 Japanese patients with mood disorders and 48 patients with schizophrenia. Eight polymorphisms and four rare variants were identified. Of these, four polymorphisms at or in close proximity to exon d, g.83097C/T (HTR4-SVR (splice variant region) SNP1), g.83159G/A (HTR4-SVRSNP2), g.83164 (T)9-10 (HTR4-SVRSNP3), and g.83198A/G (HTR4-SVRSNP4), showed significant association with bipolar disorder with odds ratios of 1.5 to 2. These polymorphisms were in linkage disequilibrium, and only three common haplotypes were observed. One of the haplotypes showed significant association with bipolar disorder (P = 0.002). The genotypic and haplotypic associations with bipolar disorder were confirmed by transmission disequilibrium test in the NIMH Genetics Initiative Bipolar Pedigrees with ratios of transmitted to not transmitted alleles of 1.5 to 2.0 (P = 0.01). The same haplotype that showed association with bipolar disorder was suggested to be associated with schizophrenia in the case-control analysis (P = 0.003) but was not confirmed when Japanese schizophrenia families were tested. The polymorphisms associated with mood disorder were located within the region that encodes the divergent C-terminal tails of the 5-HT(4) receptor. These findings suggest that genomic variations in the HTR4 gene may confer susceptibility to mood disorder.

Adolescent↗
PubMed2002

Changes in occlusal force and occlusal contact area after active orthodontic treatment: a pilot study using pressure-sensitive sheets.

The aim of this study was to investigate functional changes in occlusion during retention. Data on occlusal force (OcFr) and occlusal contact area (OcAr) was obtained using the pressure-sensitive sheet, from a treated group (20 female patients) who had had four premolar extractions and treatment with standard edgewise appliances, and a control sample who matched the treated group of retainer for sex, age and Angle classification at 1 year after removal. A repeated measures analysis of variance showed that the mean values of total OcFr and OcAr in the treatment group gradually increased during retention and were 669.3 N and 15.1 mm2, respectively, at 1 year after removal of retainer. The increases of OcFr and OcAr were larger in the molar region, especially at the second molar. At 1 year after removal of retainer, OcFr and OcAr in the second molar were significantly larger in the treatment group than in the control sample, and a similar distribution pattern of OcFr and OcAr to those in normal occlusion was seen. These results suggested that balanced OcFr and OcAr might be obtained during and after retention, due to the settling of molars that had been discluded by active orthodontic treatment.

Adolescent↗
PubMed2002

Case of radiation-induced esophageal ulcer worsened after endoscopic biopsy.

Esophageal ulcer is one of the most important late complications of the esophagus treated with radiation therapy, especially with intraluminal brachytherapy. We encountered a patient with esophageal cancer treated with external radiation therapy and intraluminal brachytherapy, who developed radiation ulcer and who had severe dysphagia soon after endoscopic biopsy of the ulcer edge. A 55-year-old man was diagnosed as esophageal cancer without symptoms. He received 60 Gy/30 Fr of external radiation therapy and 12 Gy/3 Fr of intraluminal brachytherapy at a point of 5 mm in depth from the mucosa surface. He developed an asymptomatic esophageal ulcer 13 months after treatment, and endoscopic biopsy was obtained from the edge of the ulcer. Thereafter, swallowing difficulties appeared, and endoscopy revealed severe esophageal stenosis and a deep ulcer. A possibility that the biopsy contributed to worsening the ulcer can be considered. Except for cases where relapse is apparent, endoscopic biopsy is considered to be avoided.

Biopsy, Needle↗
PubMed2002

Ventricular activation and recovery measured in electrocardiographic limb leads correlate with measurements from specific areas in body surface mapping.

AIMS: Dispersion of ventricular depolarization-repolarization in 12-lead electrocardiograms (ECGs) has been reported to provide noninvasive information on arrhythmogenicity. However, there are two methods to calculate the dispersion from ECGs including and excluding limb leads. The aim of this study was to examine whether temporal parameters from limb leads represent activation and repolarization of a particular part of the body surface. METHODS AND RESULTS: We compared the temporal parameters of activation time (AT), activation-recovery interval (ARI), and recovery time (RT) from limb leads of ECGs with those from an 87-lead body surface maps. The study population consisted of 50 normal subjects (25 men and 25 women, 19.4 +/- 1.6 years). The temporal parameters in leads I, II, and III were highly (r > 0.9) correlated with those in unipolar leads over the left lateral, left lower, and right lower chest, respectively. The temporal parameters in leads aVR, aVL, and aVF showed a significant correlation (r > 0.8) with those in unipolar leads over the right upper, left upper, and lower anterior chest, respectively. The mean AT, ARI, and RT from each limb lead of ECG were almost the same as those of unipolar leads over the corresponding areas of the body surface. CONCLUSIONS: These findings suggest that ATs, ARIs, and RTs from limb leads may represent those from unipolar leads of particular areas over the body surface in normal subjects. The temporal parameters from limb leads of ECGs may provide information on activation and repolarization as well as the precordial leads of ECGs.

Adolescent↗
PubMed2002

Subchondral bone of the human knee joint in aging and osteoarthritis.

OBJECTIVE: Although most research investigating the pathogenesis of osteoarthritis (OA) has focused on cartilage, it has been suggested that the subchondral bone (SCB) plays an important role in the development of OA. The relationships between aging, severity of OA change and the SCB thickness and density in the human knee joint specimens from a wide range of ages were examined. METHODS: One hundred forty knee joints from 72 individuals (25 females, 45 males and 2 unknowns; average age 54.8 years, range 17 to 91 years) were obtained. The surface of the articular cartilage of both the femur and tibia was evaluated for gross morphological changes with a 4-point grading scale. The lateral and medial femoral condyles were cut along a sagittal plane and the tibia along a coronal plane to make bone and cartilage strip specimens. The strips were X-rayed onto mammography film and then scanned into a computer for assessment of SCB thickness and density using image analysis software. RESULTS: Medial tibial SCB thickness was significantly lower among the elderly (age>69 years) than among the young (age<40) or the middle-aged (40 to 69) (P< 0.001 via ANOVA). Lateral tibial SCB thickness also showed the same trend of decreasing thickness with increasing age, but differences between age groups were not statistically significant. Tibial SCB thicknesses were significantly lower in arthritic grades compared to normal grades (P=0.008 in lateral and 0.017 in medial via ANOVA); in contrast, no significant differences between normal and arthritic were found in femoral SCB thicknesses. The arthritic group tended to have lower SCB densities than the normal group, but this was statistically significant in only the lateral femoral condyle. CONCLUSIONS: The results obtained in the present study are not consistent with generally accepted notions of the relationship between subchondral bone thickness or density and OA. Subchondral bone changes are not etiologic for OA but, more likely, are secondary to loss of articular cartilage which precedes the appearance of subchondral sclerosis.

Adolescent↗
PubMed2002

Enhanced oxidative damage induced by total body irradiation in mice fed a low protein diet.

PURPOSE: To examine the influence of the level of dietary protein on oxidative damage to lipid and protein in the liver and on chromosomal damage in the bone marrow after total body irradiation (TBI). MATERIALS AND METHODS: Male mice were fed a low (7%), basal (20%) or high (33%) protein diet for 3 weeks, and then received TBI at a dose of 0, 0.5 or 1 Gy. Chromosomal damage in the bone marrow was evaluated by determining the proportion of micronucleated reticulocytes in peripheral blood. Oxidative damage in the liver and plasma, and chromosomal damage in the bone marrow were evaluated on day 2 after TBI. RESULTS: The levels of lipid peroxides and protein carbonyls in the liver, lipid peroxides in the plasma, and chromosomal damage in the bone marrow, did not differ among the groups that did not receive TBI. However, the oxidative damage to lipid and protein in the liver, and the level of lipid peroxides in the plasma were increased by TBI only in the low protein group. Chromosomal damage in the bone marrow was increased by TBI in a dose-dependent manner, and the damage was consistently higher in the low protein group than in the basal and high protein groups. In the low protein group, a greater decrease of the relative spleen weight by TBI was also observed. The concentrations of antioxidants (vitamin C, E and GSH) in the liver were lower, and the concentration of non-heme iron in the liver was higher in the low protein group than in the basal and high protein groups. The TBI-induced increase in the level of plasma iron was greater in the low protein group. CONCLUSIONS: Mice fed a low protein diet became susceptible to TBI-induced oxidative damage, and a decrease in antioxidants and an increase in iron are involved in the mechanism of this susceptibility.

Animals↗
PubMed2002

Evaluation of axillary status in breast cancer. CT-based determination of sentinel lymph node size.

PURPOSE: To determine whether the location and size of sentinel lymph nodes (SLN) on CT are predictive of the axillary lymph node status in patients with breast cancer. MATERIAL AND METHODS: Forty patients with confirmed breast cancer underwent 5-mm CT of both breasts and axillae and the most inferior lymph node in the affected axilla was designated the SLN. Based on CT assessment of the axillary lymph node status, 22 (55%) patients then underwent dye- and gamma probe (DGP)-guided SLN biopsy followed by axillary dissection; 18 (45%) underwent dissection without prior SLN biopsy. The localization and status of the SLN determined on CT and by DGP-guided biopsy were compared. Biopsied and excised nodes were subjected to histopathologic examinations. RESULTS: All SLN identified on CT were close to the lateral thoracic artery and their localization corresponded well with SLN identified by the DGP-guided method. The positive predictive value of CT diagnosis was 100%. Histopathologic examination of excised nodes confirmed that none of the SLN biopsies was false-negative. CONCLUSION: Our CT criteria were highly accurate for identification and diagnostic assessment of SLN and useful for evaluating the axillary status in patients with breast cancer.

Adult↗
PubMed2002

Rhabdomyosarcoma (botryoid sarcoma) of the urinary bladder in a Maltese.

A urinary bladder tumour was diagnosed in a two-year-old female Maltese with haematuria and pollakiuria on the basis of ultrasonography and pneumocystography findings. The mass was resected, and the bladder was preserved at surgery. Histological and immunohistochemical examination confirmed the tumour to be a rhabdomyosarcoma, which has rarely been reported in small breeds of dog. There was no recurrence of the tumour at the original site in the urinary bladder two months later, when the dog died due to metastasis to the liver. This is believed to be the first report of bladder rhabdomyosarcoma in a Maltese.

Animals↗
PubMed2002

Molecular cloning and characterization of novel centromeric repetitive DNA sequences in the blue-breasted quail (Coturnix chinensis, Galliformes).

A new family of centromeric highly repetitive DNA sequences was isolated from EcoRI-digested genomic DNA of the blue-breasted quail (Coturnix chinensis, Galliformes), and characterized by filter hybridization and chromosome in situ hybridization. The repeated elements were divided into two types by nucleotide length and chromosomal distribution; the 578-bp element predominantly localized to microchromosomes and the 1,524-bp element localized to chromosomes 1 and 2. The 578-bp element represented tandem arrays and did not hybridize to genomic DNAs of other Galliformes species, chicken (Gallus gallus), Japanese quail (Coturnix japonica) and guinea fowl (Numida meleagris). On the other hand, the 1,524-bp element was not organized in tandem arrays, and did hybridize to the genomic DNAs of three other Galliformes species, suggesting that the 1,524-bp element is highly conserved in the Galliformes. The 578-bp element was composed of basic 20-bp internal repeats, and the consensus nucleotide sequence of the internal repeats had homologies to the 41-42 bp CNM repeat and the XHOI family repeat of chicken. Our data suggest that the microchromosome-specific highly repetitive sequences of the blue-breasted quail and chicken were derived from a common ancestral sequence, and that they are one of the major and essential components of chromosomal heterochromatin in Galliformes species.

Animals↗