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Biomedical subjects

N Hayashi

Publications and source records attributed to N Hayashi.

At least 145 records · Page 8Linked to original sources
PubMed2000

Optic Disc Blood Flow Measured by Scanning Laser-Doppler Flowmetry Using a New Analysis Program.

Purpose: Using a new analysis program for scanning laser-Doppler flowmetry (SLDF) by a Heidelberg retina flowmeter (HRF), we studied the relation between flow and visual field or disc morphology.Subjects and Methods: In 42 eyes of 21 patients with normal tension glaucoma (NTG) the mean-flow of the HRF blood flow parameters at the disc rim was measured and analyzed by a new analysis program for perfusion maps (the SLDF analysis tool), to minimize the influence of large vessels or/and artifacts caused by small eye movements. We investigated whether difference of the mean-flow between a pair of eyes had any relation to differences between a pair of eyes in visual field indices and those in disc morphological measurements of the Heidelberg retina tomograph.Results: We found statistically significant correlations between the mean-flow and optic disc parameters (Disk Area, Cup Area, Height Variation Contour, Cup Volume, Rim Volume, Mean RNFL Thickness). We found no statistically significant correlations between the mean-flow and visual field parameters (mean deviation, corrected pattern standard deviation).Conclusion: The results suggested that eyes with less flow in the optic disc rim have more advanced glaucomatous morphological changes.

Journal Article↗
PubMed2000

Effect of interferon therapy on the incidence of hepatocellular carcinoma and mortality of patients with chronic hepatitis C: a retrospective cohort study of 738 patients.

The effect of interferon on the long-term clinical outcome of patients with chronic hepatitis C remains unclear. This study included 594 patients with chronic hepatitis C who received interferon-alpha therapy (Interferon group) and 144 patients with chronic hepatitis C who did not receive interferon (Control group). The patients in the Interferon group were classified into the following three groups based on the response of the serum aminotransaminase level of the patient during and after completion of the therapy protocol: sustained responders (n = 175), transient responders (n = 165), and non-responders (n = 254). The age, sex, serum aminotransaminase level, platelet count, histological staging, hepatitis C virus (HCV) subtype, and HCV concentration at baseline were adjusted with the Cox proportional hazards model. The length of follow-up for assessment of the risk for developing hepatocellular carcinoma (HCC) was 57.2 +/- 13.9 months in the Interferon group and 67.7 +/- 28.7 months in the Control group. Multivariate analysis showed that interferon therapy decreased the risk for developing HCC by 48% compared with that in the Control group (P = 0.064). The older the age, being male, having a low platelet count, and higher histological stage were independent factors associated with the development of HCC. The hazard rate ratio for development of HCC in the sustained responders, transient responders, and non-responders was 0.16 (95% confidence interval [CI]: 0.04-0.62), 0.27 (95% CI: 0. 09-0.79), and 0.74 (95% CI: 0.37-1.48), respectively. During follow-up, 18 patients in the Interferon group died (10 from liver-related diseases) and 17 patients in the Control group died (10 from liver-related diseases). No sustained responder or transient responder in the Interferon group died of liver-related disease. The cumulative survival rates of the Interferon and Control groups were nearly identical during the first 5 years following diagnosis. Thereafter, the cumulative survival rate of the Control group declined, resulting in an 8-year survival rate in the Interferon and Control groups of 97% and 81%, respectively (P = 0. 061). Similar trends were seen in the survival analysis of those who had died of liver disease: the 8-year survival rates of the Interferon and Control groups were 98% and 88%, respectively (P = 0. 32). Our study demonstrated that interferon therapy significantly lowered the incidence of HCC among patients with chronic hepatitis C who showed sustained normalization and among patients who showed transient normalization of the serum aminotransferase level after completion of interferon therapy. The survival analyses and determination of cause of death suggested that interferon therapy improves the long-term survival of chronic hepatitis C patients who respond to this therapy, possibly by decreasing mortality from liver-related diseases.

Antiviral Agents↗
PubMed2000

Telomerase activity reconstituted in vitro with purified human telomerase reverse transcriptase and human telomerase RNA component.

Telomerase is a specialized reverse transcriptase that catalyzes elongation of the telomeric tandem repeat, TTAGGG, by addition of this sequence to the ends of existing telomeres. Human telomerase reverse transcriptase (hTERT) has been identified as a catalytic enzyme involved in telomere elongation that requires telomerase RNA, human telomerase RNA component (hTR), as an RNA template. We established a new method to express and purify soluble insect-expressed recombinant hTERT. The partially purified FLAG-hTERT retained the catalytic activity of telomerase in a complementation assay in vitro to exhibit telomerase activity in telomerase-negative TIG3 cell extract and in a reconstitution assay with FLAG-hTERT and purified hTR in vitro. FLAG-hTERT (D712A) with a mutation in the VDV motif exhibited no telomerase activity, confirming the authentic catalytic activity of FLAG-hTERT. The reconstituted complex of FLAG-hTERT and hTR in vitro was detected by electrophoretic mobility shift assay, and its activity was stimulated by more than 30-fold by TIG3 cell extract. This suggested that some cellular component(s) in the extract facilitated the reconstituted telomerase activity in vitro. Geldanamycin had no effect on the reconstituted activity but partially reduced the stimulated activity of the reconstituted telomerase by the TIG3 cell extract, suggesting that Hsp90 may contribute to the stimulatory effect of the cellular components.

Benzoquinones↗
PubMed2000

Cloning of a coproporphyrinogen oxidase promoter regulatory element binding protein.

Coproporphyrinogen oxidase [CPO] gene promoter regulatory element (CPRE) plays an important role in CPO gene regulation. To isolate a CPRE binding protein, we performed Southwestern screening of K562 cDNA expression library using CPRE as a probe and isolated a cDNA clone which encoded a novel protein, Klp1 (K562 cell-derived leucine-zipper-like protein 1). Klp1 mRNA was highly expressed in K562 cells, HeLa cells, and brain as a single transcript (1.4 kb). Gel mobility shift assays revealed that Klp1 specifically binds to CPRE. Computational analysis revealed that Klp1 has a leucine-zipper-like structure, a Leu-X-X-Leu-Leu motif, and a putative nuclear localization signal in the basic amino acid rich region. Transfection of the Klp1 expression vector into THP-1 cells resulted in transcriptional activation of a reporter construct containing CPRE. These results indicate that Klp1 is a DNA sequence-specific transcription factor that regulates gene expression of genes that contain CPRE in their regulatory region.

Adult↗
PubMed2000

Regional differences in cerebral blood flow during recitation of the multiplication table and actual calculation: a positron emission tomography study.

UNLABELLED: Regional cerebral differences in activation by two types of calculation, quantitative number processing and use of rote verbal arithmetic memory, were investigated. METHODS: The two types of processing were induced by serial number subtraction (the Subtra-task) and recitation of the multiplication table (the Multi-task), respectively. Regional cerebral blood flow (rCBF) under the two tasks was measured in ten healthy right-handed Japanese men using (15)O-labeled water and positron emission tomography (PET). Statistical parametric mapping (SPM) was used for estimating rCBF differences during these tasks. RESULTS: The activated areas during the Subtra-task were consistent with those reported to be involved in quantitative number processing. Although most of the regions activated during the Multi-task were in common with the regions activated during the Subtra-task, the spatial extent of the activation during the Multi-task was smaller. Moreover, the left lenticular nucleus was activated during the Multi-task, but not in the Subtra-task, while the prefrontal cortex was activated in the Subtra-task but not in the Multi-task. CONCLUSION: The difference in the regions activated by the two tasks, and the difference in the spatial extent of each region by the two tasks indicated that the anatomical networks of the two processes were segregated.

Adult↗
PubMed2000

Oxidative stress abolishes leptomycin B-sensitive nuclear export of transcription repressor Bach2 that counteracts activation of Maf recognition element.

The mammalian transcription activator Nrf2 plays critical roles in executing oxidative stress response by binding to the regulatory DNA sequence Maf recognition element. Bach2 is an Nrf2-related transcription repressor and a tissue-specific partner of the Maf oncoprotein family. We show here how Bach2 is regulated by an oxidative stress-sensitive conditional nuclear export. In cultured cells, Bach2 was localized in cytoplasm through its C-terminal evolutionarily conserved cytoplasmic localization signal (CLS). The CLS directed leptomycin B-sensitive nuclear export of reporter proteins, suggesting its dependence on the nuclear exporter Crm1/exportin 1. However, the CLS sequence does not bear a resemblance to the leucine-rich class of nuclear export signal, and mutagenesis analysis indicated that a stretch of nonhydrophobic amino acids is essential for its activity. Oxidative stressors aborted the CLS activity and induced nuclear accumulation of Bach2. Whereas oxidative stress is known to activate MARE-dependent transcription, overexpression of Bach2 in cultured cells silenced the inducibility of MARE. The results suggest that Bach2 mediates nucleocytoplasmic communication to couple oxidative stress and transcription repression in mammalian cells.

Amino Acid Sequence↗
PubMed2000

Ca2+-bound calmodulin forms a compact globular structure on binding four trifluoperazine molecules in solution.

Small-angle X-ray scattering (SAXS), which determines the radius of gyration, R(g), and the pair distance distribution function, was used to investigate the conformational changes of calmodulin (CaM) on binding to an antagonist, trifluoperazine (TFP), with or without Ca(2+) in solution. We previously applied this SAXS method to CaM complexed with N-(6-aminohexyl)-5-chloro-1-naphthalenesulphonamide (W-7) [Osawa, Kuwamoto, Izumi, Yap, Ikura, Shibanuma, Yokokura, Hidaka and Matsushima (1999) FEBS Lett. 442, 173-177] and found that the binding of two W-7 TFP molecules to one Ca(2+)-saturated CaM molecule induces structural changes from a 'dumb-bell' shape to a compact globular shape. We report here that the most compact globular shape whose size is consistent with that of the 1:2 Ca(2+)-saturated CaM-W-7 complex is formed by the binding of four TFP molecules to one Ca(2+)-saturated CaM molecule. Even in the absence of Ca(2+), the conformational changes of CaM occur on TFP binding, giving a slightly smaller R(g) than Ca(2+)-free CaM alone.

Animals↗
PubMed2000

Molecular mechanism of the nacreous layer formation in Pinctada maxima.

We have cloned the cDNAs that encode two kinds of molluscan shell matrix proteins, namely N66 and N14, in the nacreous layer of Pinctada maxima. N66 is composed of carbonic anhydrase-like and repeat domains, as described for nacrein (1) in the pearls of P. fucata. N14 is homologous to N16, recently found in the nacreous layer of P. fucata (2) and is characterized by high proportions of Gly, Tyr, and Asn together with NG repeat sequences. The molecular weights of these proteins were estimated as 59,814 and 13,734 Da, respectively. Structural differences were clearly indicated in the alignment and length of the repeat sequences of the sets of the homogeneous proteins (N66/nacrein and N14/N16). The longer repeat sequences of N66 and N14 may be responsible for P. maxima's excellent property of calcification. The in vitro crystallization experiments revealed that the mixture of N66 and N14 could induce platy aragonite layers highly similar to the nacreous layer, once adsorbed onto the membrane of the water-insoluble matrix.

Animals↗
PubMed2000

Copper-dependent formation of disulfide-linked dimer of S100B protein.

Previous cell biological studies demonstrated that S100B protein enhances neurite extension of cortical neurons and stimulates proliferation of glial cells. Although these activities of the protein are ascribed to its disulfide-linked dimeric form, there have been no indications as to how the dimer is formed in vivo. We have found by an in vitro study that it is produced by copper-dependent oxidation of noncovalent S100B dimer. The disulfide-linked dimer markedly stimulated nitric oxide production in a microglial cell line, BV2. Interestingly, the disulfide-linked dimer formation was found to be prevented by ascorbic acid. The copper-dependent formation of the dimer may not happen in vivo under normal conditions; however, under pathological conditions where copper is likely to be released from tissues and catalyze autoxidation of ascorbic acid, the dimer formation may proceed, resulting in the stimulated production of nitric oxide that would induce toxic signaling pathways.

Animals↗
PubMed2000

Serum levels of des-gamma-carboxy prothrombin measured using the revised enzyme immunoassay kit with increased sensitivity in relation to clinicopathologic features of solitary hepatocellular carcinoma.

BACKGROUND: Des-gamma-carboxy prothrombin (DCP) is an established marker for hepatocellular carcinoma (HCC), but the conventional enzyme immunoassay (EIA) kit lacks adequate sensitivity. Thus, a revised EIA kit with increased sensitivity has been developed. In this kit, the sensitivity has increased while high specificity to HCC has been maintained. The authors have already reported the clinical usefulness of this revised EIA kit. In this study, they examined the serum levels of DCP measured by this revised EIA kit in relation to the clinicopathologic features of solitary HCC. METHODS: Fifty-six patients with solitary HCC who underwent hepatectomy were studied. The relation between the greatest dimension and the histologic differentiation of HCC was investigated in these 56 patients, as were the serum levels of DCP measured by the revised EIA kit (Sensitive DCP), alpha-fetoprotein (AFP), and DCP measured by the conventional EIA kit (DCP). The cutoff value for Sensitive DCP was set at 40 mAU/mL, and the values for AFP and DCP were 20 ng/mL and 100 mAU/mL (0.1 AU/mL), respectively. RESULTS: The positivity rates for Sensitive DCP, AFP, and DCP (n = 56) were 53.6%, 53.6%, and 35.7%, respectively, and the rate was 73.2% when Sensitive DCP was used in combination with AFP (Sensitive DCP + AFP). The positivity rates for these markers were as follows: 1) When the greatest dimension of HCC was more than 3 cm (n = 16) and less than 2 cm (n = 23), the rates were 81.3% and 30.4% for Sensitive DCP, 68. 8% and 39.1% for AFP, 56.3% and 13.0% for DCP, and 93.8% and 56.5% for Sensitive DCP + AFP. 2) When HCC was moderately to poorly differentiated (n = 41) and well differentiated (n = 15), the rates were 68.3% and 13.3% for Sensitive DCP, 61.0% and 33.3% for AFP, 48. 8% and 0% for DCP, and 85.4% and 40% for Sensitive DCP + AFP. 3) When HCC was either more than 3 cm or moderately to poorly differentiated (n = 42) and either less than 2 cm or well differentiated (n = 27), the rates were 69.0% and 29.6% for Sensitive DCP, 61.9% and 37.0% for AFP, 47.6% and 11.1% for DCP, and 85.7% and 51.9% for Sensitive DCP + AFP. CONCLUSIONS: DCP measured by the revised EIA kit with increased sensitivity has a stronger correlation than AFP with size and histologic differentiation of HCC. This Sensitive DCP is a very useful marker for HCC and should be used in combination with AFP.

Adult↗
PubMed2000

Positive charge intrinsic to Arg(37)-Arg(38) is critical for dopamine inhibition of the catalytic activity of human tyrosine hydroxylase type 1.

Tyrosine hydroxylase (TH), which converts L-tyrosine to L-3, 4-dihydroxyphenylalanine, is a rate-limiting enzyme in the biosynthesis of catecholamines; its activity is regulated by the feedback inhibition of the catecholamine products including dopamine. To rationalize the significant role of the N-terminal sequence Arg(37)-Arg(38) of human TH type 1 (hTH1) in determining the efficiency of feedback inhibition, we produced mutants of which the positively charged Arg(37)-Arg(38) site was replaced by electrically neutral Gly and/or negatively charged Glu and analyzed the degree of inhibition of these mutant enzymes by dopamine. The replacement of Arg by Gly reduced the inhibitory effect of dopamine on the catalytic activity measured in the basic pH range and the replacement of Arg by Glu was enough to abolish the inhibitory effect, although these mutations brought no significant changes to the circular dichroism spectrum. The prediction of the secondary structure of N-terminal residues 1-60 by computer software specified the location of the Arg(37)-Arg(38) sequence in the turn intervening between the two alpha-helices (residues 16-29 and residues 41-59). These results suggest that the positive charge of the amino acid residues at positions 37 and 38 is one of the main factors that maintains the characteristic of the turn and is responsible for the enzyme inhibition by dopamine.

Amino Acid Sequence↗
PubMed2000

A giant cell angiofibroma involving 6q.

Giant cell angiofibroma, a recently proposed new clinicopathological entity, arises exclusively in the orbit in adults and histologically exhibits features intermediate between those of giant cell fibroblastoma and solitary fibrous tumor. In a typical case of giant cell angiofibroma, abnormalities of chromosome 6 with a common pattern involving 6q13 were detected together with various other chromosomal aberrations. To our knowledge, this is the first reported case of giant cell angiofibroma demonstrating chromosomal abnormalities.

Angiofibroma↗
PubMed2000

Mechanical compression of the lumbar nerve root alters pain-related behaviors induced by the nucleus pulposus in the rat.

The purpose of this study was to refine a method of nerve-root injury in the rat to produce hyperalgesia, a pain-related behavior, and to determine if there were any relationships between the histological extent of nerve-root injury and the magnitude of hyperalgesia. Three methods were used to produce hyperalgesia: irritation of a nerve root by ectopic nucleus pulposus, silk loop alone, or both silk loop and ectopic nucleus pulposus. Autologous nucleus pulposus obtained from coccygeal intervertebral discs was relocated on the lumbar nerve roots after laminectomy. Two loops of 4-0 silk were placed around the exposed nerve roots. Hyperalgesia was measured preoperatively and postoperatively. The distribution of myelinated axons in the dorsal nerve roots was evaluated histologically. Mechanical hyperalgesia was detected in rats in which autologous nucleus pulposus was applied to the nerve root but not in those in which silk loops were used. Silk loops around the nerve root resulted in thermal hyperalgesia only in rats in which autologous nucleus pulposus was applied to the nerve root. Fewer large myelinated fibers were seen in the rats in which silk loops were used. Although a silk loop around the nerve root was not sufficient to produce hyperalgesia, supplemental application of autologous nucleus pulposus to the nerve root produced thermal hyperalgesia. It is possible that mechanical constriction of the nerve root alters the pain-related behavior elicited by chemical factors from the nucleus pulposus.

Animals↗
PubMed2000

A diagnostic method for suspected Alzheimer's disease using H(2)15O positron emission tomography perfusion Z score.

We developed cerebral perfusion Z score map (Z map) images using H(2)15O and positron emission tomography (PET), and examined their use in diagnosing Alzheimer's disease (AD). Cerebral blood flow (CBF) images were obtained using the PET and H(2)15O autoradiographic method. The best region for normalising the CBF value to remove individual variantion was determined. Then CBF images were transformed to Talairach's standard space, and each pixel value of an individual's image set was normalized to the mean value of the sensorimotor area. Based on the CBF images of 20 normal volunteers, normative mean and standard deviation (SD) CBF images were constructed. Then, each pixel value of the axial CBF images in 28 patients with probable AD and 10 further normal volunteers was converted to a Z score (Z = [normal mean--individual value]/normal SD). A Z map, showing pixels exceeding a threshold of Z score > 2 on MRI of standardised anatomical space was demonstrated. These 38 Z maps were interpreted by four radiologists. When regions in the temporoparietal area were found with Z scores > 2, the subject was diagnosed as having AD. A receiver operating characteristic (ROC) analysis was performed to compare the conventional CBF images and Z maps. The diagnostic performance of the Z map was superior to that of visual inspection of conventional CBF images (mean areas under the ROC curve of the four radiologists were 0.946 and 0.584, respectively). These results indicate that a Z map obtained in this way is superior to conventional PET for diagnosing AD.

Aged↗