Biomedical subjects

H Shindo

Publications and source records attributed to H Shindo.

At least 55 records · Page 3Linked to original sources

PubMed1999

Magnetization transfer ratio in cerebral white matter lesions of Binswanger's disease.

We measured the magnetization transfer (MT) ratios in white matter lesions of Binswanger's disease (BD) and compared them with BD and with similar-appearing changes in non-demented elderly subjects and cerebral infarction. Four subject groups were studied: 30 patients with BD and periventricular hyperintensity (PVH) on MRI, 29 patients with ischemic cerebrovascular event with PVH but no dementia, 17 patients with old cerebral infarction, and 26 elderly control subjects. MT ratios were calculated for areas of PVH in BD and non-demented subjects, of infarction, and of normal-appearing white matter in controls. The decrease in MT ratios for areas in PVH of non-demented subjects and BD and in infarction compared with normal white matter in controls was 12, 20, and 35%, respectively. The MT ratio in PVH of BD was significantly lower than that in PVH of non-demented subjects, but not to the levels seen in areas of infarction. There was a significant high correlation between the Mini-Mental State Examination score and MT ratio for area of PVH (r = 0.790). MT ratio distinguishes PVH in BD patients from those in non-demented subjects, suggesting underlying histopathological differences. Tissue damage in white matter lesions of BD may be more severe than that in non-demented subjects, but not as much as with complete infarction.

Aged↗

PubMed1999

Wear of alumina ceramics prosthesis.

To investigate the process of wear in the total knee prosthesis consisting of alumina ceramics (Al-ceramics) and ultra-high molecular weight polyethylene (UHMWP) in vivo, we observed the fine structures of the articular surface of the prostheses used for four patients with osteosarcoma of the distal femur. We also examined the wear debris in the surrounding soft tissues. The prostheses were extracted at autopsy between 13 and 48 months after surgery. An increase of pores, indicating where Al-ceramics grains fell off, and many streaks on the UHMWP running parallel to the gliding direction of the joint were observed on the articular surface. The streaks had similar widths to the Al-ceramics grains. Al-ceramics debris was detected in the soft tissues around the joint mixed with UHMWP debris. We concluded that the wear of UHMWP in Al-ceramics prosthesis was promoted by interposition of Al-ceramics debris.

Adolescent↗

PubMed1999

Cilostazol, a cyclic AMP phosphodiesterase inhibitor, stimulates nitric oxide production and sodium potassium adenosine triphosphatase activity in SH-SY5Y human neuroblastoma cells.

Deficiencies in cellular cyclic AMP (cAMP) and nitric oxide (NO) production are thought to be involved in the pathogenesis of diabetic neuropathy. We used a human neuroblastoma cell line, SH-SY5Y, to investigate the effect of cilostazol, a specific cAMP phosphodiesterase inhibitor, on NO production and Na+, K+-ATPase activity. SH-SY5Y cells were cultured under 5 or 50 mM glucose for 5-6 days, the cells were then exposed to cilostazol or other chemicals and nitrite, cAMP and Na+, K+-ATPase activity were measured. In cells grown in 50 mM glucose, cilostazol was observed to increase significantly both NO production and cellular cAMP accumulation in a time- and dose-dependent manner. Cilostazol also significantly recovered reduced levels of protein kinase A activity (PKA) in 50 mM glucose. Furthermore, a PKA inhibitor, H-89 significantly suppressed the increase in NO production stimulated by cilostazol, suggesting that cilostazol stimulates NO production by activating PKA. Cilostazol did not affect either sorbitol or myo-inositol concentrations. Dexamethasone, which is known to induce inducible NO synthase, had no effect on NO production stimulated by cilostazol, suggesting that cilostazol stimulates NO production catalyzed by neuronal constitutive NO synthase (ncNOS) in SH-SY5Y cells. L-arginine, which is an NO agonist enhanced Na+, K+-ATPase activity in cells grown in 50 mM glucose, NG-nitro-L-arginine methyl ester (L-NAME), which is an NOS inhibitor inhibited basal Na+, K+-ATPase activity in 5 mM glucose and suppressed the increased enzyme activity induced by cilostazol in 50 mM glucose. The above results confirmed our previous observation that NO regulates Na+, K+-ATPase activity in SH-SY5Y cells and suggest that cilostazol increases Na+, K+-ATPase activity, at least in part, by stimulating NO production. The present results also suggest that cilostazol has a beneficial effect on diabetic neuropathy by improving Na+, K+-ATPase activity via directly increasing cAMP and NO production in nerves.

Cilostazol↗

PubMed1999

Fur mites induce dermatitis associated with IgE hyperproduction in an inbred strain of mice, NC/Kuj.

An inbred strain of mice, NC, has been introduced as an animal model for atopic dermatitis because the mice develop dermatitis associated with severe scratch preceded by elevated serum IgE level when kept in conventional conditions. Although hypersensitivity to some environmental factors is suggested to cause dermatitis, the precise factor remains unclear. As the mice maintained under conventional conditions were often infected with fur mites, we investigated whether an infection of fur mites induces skin lesions in NC. Infection with the fur mites induced NC to develop skin lesions associated with highly elevated serum IgE, whereas no obvious skin lesions were observed in BALB/c and C57BL/6, and the elevation of serum IgE level was minimal in these two strains of mice. The role of the fur mites in the manifestation of skin lesions and IgE hyperproduction was confirmed by eliminating the fur mites by treatment with ivermectin. In addition, the existence of specific IgE antibody to Myocoptes musculinus antigen in the sera of mite-infested NC was detected by the antigen-induced histamine release from bone marrow-derived cultured mast cells after sensitization with the serum. These results suggest that continuous exposure to fur mite antigen is a potential factor in the development of dermatitis in NC. We provide a new model system of antigen-induced dermatitis for investigating the role of IgE in eliciting dermatitis.

Animals↗

PubMed1999

Osteitis fibrosa cystica generalizata with adult T-cell leukaemia: a case report.

We report on a 62-year-old female initially suffering from extreme pain in both her lower extremities. Plain radiographs revealed multiple osteolytic lesions. Laboratory analyses indicated high levels of serum calcium and parathyroid hormone related protein (PTHrP) and detected HTLV-1 antibody. Histological examination of biopsied specimens which were obtained from osteolytic lesions indicated osteitis fibrosa cystica (OFC) without tumour cells. After the initial biopsy, a subcutaneous mass developed in the left thigh. Microsections of the biopsied mass disclosed adult T-cell leukaemia (ATL) neoplastic cells. Immunohistochemical findings revealed that PTHrP secreted from ATL neoplastic cells induced the OFC.

Female↗

PubMed1999

A role of the C-terminal region adjacent to the zinc-fingers in the DNA binding ability of Rme1p, a regulator of meiosis in S. cerevisiae.

Rme1p is a zinc-finger protein and has a pivotal role in control of meiosis in Saccharomyces cerevisiae. The DNA binding domain of Rme1p consists of three zinc-finger segments and the C-terminal 16 amino acid residues (called C-TR). To examine the role of C-TR, a series of mutant Rme1p fused with maltose binding protein (MBP) were constructed, purified, and characterized, in terms of the DNA binding ability. The basic amino acid residues R287 and K290, and the hydrophobic residues F288, L292, 1295, and L296 play an important role for DNA binding, suggesting that the C-TR forms an amphipathic alpha-helix. Also, it was shown that the mutations in the basic amino acid residues abolish the repression and inhibition of spore formation by Rme1p in vivo. Hence, the C-TR is important for in vivo function of Rme1p.

Amino Acid Sequence↗

PubMed1999

Regional differences in diffusion abnormality in cerebral white matter lesions in patients with vascular dementia of the Binswanger type and Alzheimer's disease.

We investigated changes in water diffusion in the cerebral white matter of 14 patients with vascular dementia of the Binswanger type (VDBT) and ten patients with Alzheimer's disease (AD) with periventricular hyperintensity (PVH) lesions using diffusion-weighted magnetic resonance imaging (MRI) and studied the pathophysiological differences between white matter lesions found in these two conditions. Apparent diffusion coefficients (ADCs) in the anterior and posterior white matter and the genu and splenium of the corpus callosum were significantly higher in both groups of patients than in the 12 age-matched controls, and ADC values in VDBT and AD groups were almost the same. ADC ratios, defined as diffusion restricted perpendicular to the direction of nerve fibers, were also significantly higher in the patients than in the control subjects. However, there were regional differences in ADC ratios in the two conditions, with ratios in VDBT being higher in the anterior portions of the white matter but ratios in AD were higher in the posterior portions. The diffusion-weighted MRI technique may be useful in the differential diagnosis of VDBT and AD with white matter lesions.

Aged↗

PubMed1999

Regulation of c-fos gene induction and mitogenic effect of transforming growth factor-beta1 in rat articular chondrocyte.

We have previously reported that type I transforming growth factor beta (TGF-beta1) is a potent stimulator of cell growth in articular chondrocytes. In this study, we examined the mechanism of TGF-beta1 induced cellular proliferation by using cultured rat articular chondrocytes (CRAC). A time-course study of [3H]thymidine incorporation upon TGF-beta1 (1 ng/mL) or 10% fetal bovine serum stimulation revealed that TGF-beta1 directly stimulates DNA synthesis in CRAC. Pretreatment with H7, an inhibitor for protein kinase C (PKC), completely blocks TGF-beta1-induced proliferation. Since TGF-beta1 has been shown to transduce signals through MAP kinase cascades, we investigated the induction of several protooncogenes by Northern blotting. TGF-beta1 addition causes an immediate and transient induction of c-fos but not myc or jun mRNA. Furthermore, this c-fos expression is not inhibited by cycloheximide, but is completely abolished by pretreatment with TPA, so that the c-fos gene is a direct target of TGF-beta1 signalling and PKC is involved in this c-fos induction. To refine our understanding of TGF-beta1 regulation of the c-fos promoter region, we performed chloramphenicol acetyltransferase (CAT) assays. A serial deletion analysis of the c-fos promoter region reveals a TGF-beta1 responsive element in a region between -403 and -329 bp upstream of the transcription initiation site. We attempted gel shift assays on this response element with CRAC nuclear extracts. Although this region contains a sis-inducible binding element, we fail to detect specific DNA-protein complexes. Our results, however, suggest that TGF-beta1 acts as a primary mitogen in CRAC and this mitogenic activity requires PKC activation. Finally, the subsequent induction of c-fos expression occurs through an as yet unidentified transactivation mechanism.

Animals↗

PubMed1999

Transforming growth factor-beta stimulates articular chondrocyte cell growth through p44/42 MAP kinase (ERK) activation.

Transforming growth factor-beta1 (TGF-beta1) stimulates articular chondrocyte cell proliferation and extracellular matrix formation. We reported previously that immediate and transient expression of c-fos mRNA through protein kinase C activation is required for the mitogenic effect of TGF-beta1 on cultured rat articular chondrocytes (CRAC). In gel kinase assays using myelin basic protein (MBP) showed that total cell lysates from cells treated with TGF-beta1 caused rapid phosphorylation of MBP, which suggests the involvement of mitogen-activated protein kinase (MAPK) activation. To identify specific MAPK pathways activated by TGF-beta1, we performed in vitro kinase assays using specific substrates. TGF-beta1 induced a rapid activation of extracellular signal regulated kinase (ERK) with a peak at 5 min, which decreased to basal levels within 240 min after TGF-beta1 stimulation. In contrast, the c-jun N-terminal kinase activity increased only about 2.5-fold after 240 min of stimulation and p38 MAPK activity did not change significantly. ERK activation by TGF-beta1 was also confirmed by in vivo phosphorylation assays of Elk1. However, a specific MEK1 inhibitor, PD98059, significantly decreased TGF-beta1 induced Elk1 phosphorylation in a dose-dependent manner. Furthermore, PD98059 reduced the TGF-beta1-induced cell growth by 40%. These results indicate that TGF-beta1 specifically activates MEK1 and subsequent ERK pathways in CRAC, and that the activation of this MAPK pathway plays a role in the mitogenic response to TGF-beta1.

Animals↗

PubMed1999

cDNA cloning and chromosomal mapping of rat Smad2 and Smad4 and their expression in cultured rat articular chondrocytes.

Smad proteins are known to transduce signalling of TGF-beta receptor superfamily. We report here the entire sequences of rat Smad2 and Smad4 which have not been identified yet. Entire sequences were identified by degenerated polymerase chain reaction and following phage library screening and 5' RACE. The predicted amino acid sequences of rat Smad2 and Smad4 are highly conserved among rat, human and mouse. We also mapped these Smads to chromosome 18q.12.3. Unlike endothelial cells, TGF-beta1 stimulates articular chondrocyte proliferation as well as extracellular matrix production, and acts as a repairing agent against cartilage destruction. Since both Smad2 and Smad4 are essential factors for TGF-beta signalling, we examined their expression and regulation in cultured articular chondrocytes. Northern blot analysis showed that TGF-beta1 significantly increased the mRNA level of Smad2 but not of Smad4 in a dose- and time-dependent manner, suggesting that the augmentation of TGF-beta1 action is caused by increasing the expression of the downstream signalling molecule.

Amino Acid Sequence↗

PubMed1998

Genomic footprinting of the yeast zinc finger protein Rme1p and its roles in repression of the meiotic activator IME1.

The zinc finger protein Rme1p is a negative regulator of the meiotic activator IME1 in Saccharomyces cerevisiae . Prior studies have shown that Rme1p binds in vitro to a site near nt -2030 in the IME1 upstream region, but a genomic mutation in that site has little effect on repression of IME1 . To identify Rme1p binding sites in vivo , we have examined the binding of Rme1p to genomic sites through in vivo footprinting. We show that Rme1p binds to two sites in the IME1 upstream region, near nt -1950 and -2030. Mutations in both binding sites abolish repression of chromosomal IME1 by Rme1p, whereas a mutation in either single site causes partial derepression. Therefore, both Rme1p binding sites are essential for repression of IME1 . Prior studies have shown that repression by Rme1p depends upon RGR1 and SIN4 , which specify RNA polymerase II mediator subunits that are required for normal nucleosome density. We find that RGR1 and SIN4 are not simply required for Rme1p to bind to DNA in vivo . These results suggest that Rme1p functions directly as a repressor of IME1 and that Rgr1p and Sin4p are required for DNA-bound Rme1p to exert repression.

Binding Sites↗

PubMed1998

Diffusion-weighted MR imaging of the hippocampus and temporal white matter in Alzheimer's disease.

We investigated the changes in water diffusion in the hippocampus and the temporal white matter (the temporal stem) in eight patients with possible Alzheimer's disease (AD), 10 patients with probable AD, and 10 age-matched controls, using coronal diffusion-weighted magnetic resonance (MR) imaging. Apparent diffusion coefficients (ADCs) were derived for the three orthogonal axes and an index of diffusion anisotropy (IDA = ADC(max-min)/ADC(mean)) was then calculated. Although no significant differences were found in ADC and IDA values in the hippocampal body between controls and patients, vertical (superior-inferior) ADC values and ADC(mean) values in the temporal stem of patients with AD were significantly higher than those in controls, and IDA values were therefore significantly lower in patients with possible or probable AD than those in controls. Moreover, IDA values in the temporal stem were significantly correlated with the clinical severity. These results suggest that decreased fiber density, such as the disruption and loss of axonal membranes or myelin, occur early in the temporal stem, probably due to secondary degeneration related to grey matter pathology including the medial temporal lobe.

Aged↗

PubMed1998

cAMP regulates nitric oxide production and ouabain sensitive Na+, K+-ATPase activity in SH-SY5Y human neuroblastoma cells.

We investigated the relation between cyclic AMP (cAMP) and nitric oxide (NO) production, as well as the effect of NO on Na , K+-ATPase activity in the human neuroblastoma cell line SH-SY5Y. Two cAMP agonists, dibutyryl cAMP (DBC) and beraprost sodium (BPS), increased cAMP accumulation and NO production in a time and dose dependent manner at 50 mmol/l glucose. On the other hand, cellular sorbitol and myo-inositol contents and protein kinase C activity were not altered by DBC or BPS. A specific protein kinase A inhibitor, H-89, suppressed increases in nitrite/nitrate and cyclic GMP (cGMP) and protein kinase A activity stimulated by DBC or BPS. This finding suggests that cAMP stimulates NO production by activating protein kinase A via a pathway different from the sorbitol-myo-inositol-protein kinase C pathway. We observed that an NO donor, sodium nitroprusside, and an NO agonist, L-arginine, enhanced ouabain sensitive Na+, K+-ATPase activity at 50 mmol/l glucose. We also found that a nitric oxide synthase inhibitor, NG-nitro-L-arginine methyl ester (L-NAME), inhibited Na+, K+-ATPase activity at 5 mmol/l glucose, and partially suppressed the enzyme activity stimulated by DBC or BPS. The results of this study suggest that cAMP regulates protein kinase A activity, NO production and ouabain sensitive Na+, K+-ATPase activity in a cascade fashion. The results also suggest that protein kinase A at least partially regulates Na+, K+-ATPase activity without mediation by NO in SH-SY5Y cells. We speculate that cAMP and NO are two important regulatory factors in the pathogenesis of diabetic neuropathy.

Bucladesine↗

PubMed1998

Diffusion-weighted magnetic resonance and magnetization transfer imaging in the assessment of ischemic human stroke.

We compared characteristic features in ischemic stroke lesions from the hyperacute to the chronic stage on diffusion-weighted (DW) and magnetization transfer (MT) images with those on T2-weighted (T2W) images, and assessed changes in apparent diffusion coefficient (ADC), MT effect (MTe), and T2 ratios (infarct/normal) over time. DW images were particularly useful for detecting hyperacute infarcts within 6 hours of onset and in distinguishing acute lesions from chronic lesions. ADC ratios were lower within 7 days after onset and rose toward 1.0 in the subacute phase, becoming relatively isotense on ADC maps, but elevated thereafter. Although MTe ratios were unchanged or only subtly changed in the acute stage, they became significantly lower in the subacute and chronic stages. These combined magnetic resonance (MR) techniques were useful in the assessment of ischemic stroke and facilitated the determination of the age of cerebral infarct.

Aged↗

PubMed1997

Dynamics in the isomerization of intramolecular DNA triplexes in supercoiled plasmids.

We report here kinetic and thermodynamic studies on differential isomerization of intramolecular Pyr*Pur.Pyr triplexes in supercoiled plasmids. Two structural isomers of the triplex exist: one with the 3'-half of the Pyr strand as the third strand (H-y3 form) and the other with the 5'-half as the third strand (H-y5 form). The relative populations of the two triplex isomers was determined using the chemical probe with diethyl pryrocarbonate as a function of incubation time. The results demonstrated that triplexes were formed rapidly after a pH change from pH 8.0 to 5.0 and that the initial population of the two isomers exponentially changed with incubation time to reach true thermodynamic equilibrium with a time constant of 0.6-10 h, depending on temperature and the presence of Mg2+. The results clearly demonstrated that interconversion occurs between the two isomers and that the presence of Mg2+ generally retarded the interconversion rates. Kinetic and thermodynamic analyses of the relative populations of the two isomers revealed that the apparent energy barrier for transition from duplex to the H-y3 form is higher than that to the H-y5 form, but H-y3 is more stable in enthalpy terms than H-y5. Therefore, H-y3 is kinetically inferior but thermodynamically favored at higher supercoil levels in plasmids. The presence of Mg2+ resulted in both a kinetic and a thermodynamic preference for H-y5 formation, relative to the H-y3 form.

DNA↗

PubMed1997

Functional domains of Escherichia coli single-stranded DNA binding protein as assessed by analyses of the deletion mutants.

A series of C- and N-terminal deletion mutants of Escherichia coli single-stranded DNA binding protein (SSB) was constructed, purified, and characterized in terms of ability to self-multimerize and to bind to DNA. High-performance gel filtration chromatography revealed that the amino acids 89-105 play a key role in the maintenance of homotetramer for native SSB of 177 amino acids. Interestingly, all of the N-terminal deletion mutants studied here were eluted as octamers, indicating that the N-terminal 11 residues are involved in the prevention of the formation of octamers. The binding of SSB and its deletion mutant proteins to single-stranded d(T)n was examined by gel mobility shift assay and circular dichroism spectroscopy. C-terminal deletion mutant proteins, SSB1-135 and SSB1-115, maintained high affinity and may be wrapped by single-stranded DNA (ssDNA) in the same way as in the case of native SSB. In contrast, deletion of the C-terminal region (residues 89-115) or N-terminal region (residues 1-11) caused a dramatic decrease in the binding affinity. Furthermore, two different stoichiometries of SSB in the complexes with d(T)64, but not with d(T)32, were observed for native SSB, SSB1-135, SSB1-115, and SSB37-177, suggesting that the (SSB)65 and (SSB)35 binding modes, as previously demonstrated [Lohman, T. M., & Overman, L. B. (1985) J. Biol. Chem. 260, 3594-3603; Bujalowski, W., & Lohman, T. M. (1986) Biochemistry 25, 7799-7802], occurred at lower and higher SSB concentrations, respectively. A functional map for SSB molecule was presented and discussed.

Binding Sites↗

PubMed1997

How amino acids control the binding of Cu(II) ions to DNA (II): effect of basic amino acid residues and the chirality on the orientation of the complexes.

The binding structures of bis-lysine and bis-arginine complexes of copper(II) on highly oriented DNA fibers have been investigated by ESR spectroscopy. These complexes bind to DNA in two different modes; species A in one mode has a planar coordination structure as in solution, and species B in the other mode has a distorted planar structure on the DNA. The relative amount of A and B changes with the conformation of the DNA, as well as with the type and chirality of the amino acids. Arginine forms A more than lysine. On A-form DNA fibers, A for L-lysine and L-arginine complexes are bound with the angle theta = 45 degrees between the g// axis and the DNA helical axis, while A and B for the D-isomers are almost randomly oriented. L-arginine fixes the orientation of A on A-form DNA fibers more firmly than L-lysine. On B-form DNA fibers, the orientation of the complexes is modulated dynamically, and the g// axes have a tendency to be reoriented along the fiber axis by the conformational change of the DNA from A- to B-form at room temperature. The D-arginine complex on B-form DNA is peculiar in that it rotates ore freely than the other complexes at room temperature and shows only the A at low temperature.

Animals↗

PubMed1997

Transcriptional repression at a distance through exclusion of activator binding in vivo.

The yeast repressor Rme1p acts from distant binding sites to block transcription of the chromosomal IME1 gene. Rme1p can also repress the heterologous CYC1 promoter when Rme1p binding sites are placed 250-300 bp upstream of CYC1 transcriptional activator binding sites (UAS1 and UAS2). Here, in vivo footprinting studies indicate that Rme1p acts over this distance by preventing the binding of the CYC1 transcriptional activators to UAS1 and UAS2. Inhibition of activator binding by Rme1p has the same genetic requirements as repression: both depend upon sequences flanking the Rme1p binding sites and upon Rgr1p and Sin4p, two subunits of the RNA polymerase II-associated Mediator complex that are required for normal nucleosome density. Thus Rme1p may alter chromatin to prevent binding of transcriptional activators to distant DNA sequences.

CCAAT-Binding Factor↗