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Biomedical subjects

H Yoshida

Publications and source records attributed to H Yoshida.

At least 523 records · Page 29Linked to original sources
PubMed1999

Autoantibodies define a family of proteins with conserved double-stranded RNA-binding domains as well as DNA binding activity.

Cellular responses to viral infection are signaled by double-stranded (ds) RNA, which is not found in substantial amounts in uninfected cells. Although cellular dsRNA-binding proteins have been described, their characterization is incomplete. We show that dsRNA-binding proteins are prominent autoantigens. Sera from B6 and B10.S mice with pristane-induced lupus and human autoimmune sera immunoprecipitated a novel set of 130-, 110-, 90-, 80-, and 45-kDa proteins. The proteins were all major cellular poly(IC)-binding factors. N-terminal amino acid sequences of p110 and p90 were identical and matched nuclear factor (NF) 90 and M phase phosphoprotein 4. p45 and p90 were identified as the NF45.NF90 complex, which binds the interleukin-2 promoter as well as certain highly structured viral RNAs. NF90.NF45 and M phase phosphoprotein 4 belong to a large group of proteins with conserved dsRNA-binding motifs. Besides binding dsRNA, NF90.NF45, p110, and p130 had single-stranded and dsDNA binding activity. Some sera contained autoantibodies whose binding was inhibited by poly(IC) but not single-stranded DNA or vice versa, suggesting that the DNA- and RNA-binding sites are different. These autoantibodies will be useful probes of the function of dsRNA-binding proteins. Their interaction with dsRNA, an immunological adjuvant, also could promote autoimmunity.

Amino Acid Sequence↗
PubMed1999

Inhibitory effect of tea flavonoids on the ability of cells to oxidize low density lipoprotein.

Dietary flavonoid intake has been reported to be inversely related to mortality from coronary heart disease, and the anti-atherosclerotic effect of flavonoids is considered to be due probably to their antioxidant properties. Oxidation of low density lipoprotein (LDL) has been reported to be induced by the constituent cells of the arterial wall. Accordingly, we examined the effect of pretreatment with tea flavonoids, such as theaflavin digallate, on the ability of cells to oxidize LDL. Theaflavin digallate pretreatment of macrophages or endothelial cells reduced cell-mediated LDL oxidation in a concentration- (0-400 microM) and time- (0-4 hr) dependent manner. This inhibitory effect of flavonoids on cell-mediated LDL oxidation was in the order of theaflavin digallate > theaflavin > or = epigallocatechin gallate > epigallocatechin > gallic acid. Further, we investigated the mechanisms by which flavonoids inhibited cell-mediated LDL oxidation using macrophages and theaflavin digallate. Theaflavin digallate pretreatment decreased superoxide production of macrophages and chelated iron ions significantly. These results suggest that tea flavonoids attenuate the ability of the cell to oxidize LDL, probably by reducing superoxide production in cells and chelating iron ions.

Animals↗
PubMed1999

Regulation of E- and P-cadherin expression correlated with melanocyte migration and diversification.

Melanocytes (Mc) and their progenitors melanoblasts (Mb) are derived from the neural crest and migrate along the dorsolateral pathway to colonize the dermis, the epidermis, and finally the hair matrix. To examine the involvement of cadherins in the migration of Mc lineage cells, we combined flow cytometric analysis of dissociated live cells with immunohistochemical staining of tissue sections to quantify the level of cadherin expression on the surface of Mb/Mc. At 11.5 days postcoitum, Mb are in the dermis and are E-cadherin(-)P-cadherin(-) (E-cad(-)P-cad(-)). During the next 48 h, a 200-fold increase of E-cadherin expression is induced on the surface of Mb prior to their entry into the epidermis, thereby forming a homogeneous E-cad(high)P-cad(-/low) population. The cadherin expression pattern then diversifies, giving rise to three populations, an E-cad(-)P-cad(-) dermal population, E-cad(high)P-cad(low) epidermal population, and E-cad(-)P-cad(med-high) follicular population. In all three populations, the patterns of expression are region-specific, being identical with those of surrounding cells such as keratinocytes and fibroblasts, and are preserved before and after pigmentation. While most of the epidermal Mb/Mc disappear after the neonatal stage in normal mice, forced expression of steel factor in the epidermis of transgenic mice promotes survival of epidermal Mb/Mc, maintaining epidermal-type cadherin expression pattern (E-cad(high)P-cad(low)) throughout the postnatal life. These findings indicate the involvement of extrinsic cues in coordinating the cadherin expression pattern of Mb/Mc and suggest a role for E- and P-cadherins in guiding Mc progenitors to their final destinations.

Animals↗
PubMed1999

Construction and characterization of mutant water-soluble PQQ glucose dehydrogenases with altered K(m) values--site-directed mutagenesis studies on the putative active site.

Based on a PCR mutant enzyme of water-soluble glucose dehydrogenase-harboring pyrroloquinoline quinone as the prosthetic group, PQQGDH-B, a site-directed mutagenesis study was carried out. The substitution of Glu277 residue with Gly resulted in a decrease in the K(m) value for glucose and altered the substrate specificity profile, compared with the wild-type enzyme. Mutational analyses on the neighboring amino acid residues of Glu277 were also carried out and constructed Asp275Glu, Asp276Glu, Ile278Phe, and Asn279His. Considering that Asp275Glu, Asp276Glu and also Glu277Gly showed drastic decreases in EDTA tolerance, this region may construct a PQQGDH-B putative active site, such as a binding site for Ca(2+), which is responsible for the binding PQQ. A series of Glu277 variants, Glu277 substituted by Ala, Val, Asp, Asn, His, Gln, or to Lys, was constructed and they all showed decreased K(m) values and altered substrate specificity profiles. Among them, Glu277Lys showed similar thermal stability with the wild-type enzyme, but its catalytic efficiency increased significantly, compared with the wild-type enzyme. The potential applications of Glu277Lys in analytical use are also discussed.

Amino Acid Sequence↗
PubMed1999

The myocardial Na(+)-H(+) exchange: structure, regulation, and its role in heart disease.

The Na(+)-H(+) exchange (NHE) is a major mechanism by which the heart adapts to intracellular acidosis during ischemia and recovers from the acidosis after reperfusion. There are at least 6 NHE isoforms thus far identified with the NHE1 subtype representing the major one found in the mammalian myocardium. This 110-kDa glycoprotein extrudes protons concomitantly with Na(+) influx in a 1:1 stoichiometric relationship rendering the process electroneutral, and its activity is regulated by numerous factors, including phosphorylation-dependent processes. There is convincing evidence that NHE mediates tissue injury during ischemia and reperfusion, which probably reflects the fact that under conditions of tissue stress, including ischemia, Na(+)-K(+) ATPase is inhibited, thereby limiting Na(+) extrusion, resulting in an elevation in [Na(+)](i). The latter effect, in turn, will increase [Ca(2+)](i) via Na(+)-Ca(2+) exchange. In addition, NHE1 mRNA expression is elevated in response to injury, which may further contribute to the deleterious consequence of pathological insult. Extensive studies using NHE inhibitors have consistently shown protective effects against ischemic and reperfusion injury in a large variety of experimental models and has led to clinical evaluation of NHE inhibition in patients with coronary artery disease. Emerging evidence also implicates NHE1 in other cardiac disease states, and the exchanger may be particularly critical to postinfarction remodeling responses resulting in development of hypertrophy and heart failure.

Animals↗
PubMed1999

Peroxiredoxin I expression in human thyroid tumors.

Peroxiredoxin I (Prx I) is newly discovered oxidative stress inducible protein, having a thioredoxin peroxidase activity. The Prx I expression level in 107 samples out of 60 thyroid lesions, including normal thyroid, tumors and thyroiditis including Graves' disease were examined using immunoblotting. Prx I expression levels in follicular neoplasm (P = 0.00005) and thyroiditis group (P = 0.0037) were significantly higher than that of the control group, while papillary carcinoma group did not show statistical significance. Immunohistochemistry indicated that Prx I was in epithelial cells of thyroid follicles. These results suggest that Prx I is expected to be a candidate for novel tumor markers to discriminate tissue types of tumors.

Adult↗
PubMed1999

Adenovirus-mediated kallikrein gene delivery attenuates hypertension and protects against renal injury in deoxycorticosterone-salt rats.

To demonstrate potential therapeutic effects of kallikrein gene delivery in salt-induced hypertension and renal diseases, we delivered adenovirus carrying the human tissue kallikrein gene (Ad.CMV-cHK) into deoxycorticosterone acetate (DOCA)-salt hypertensive rats. A single intravenous injection of Ad.CMV-cHK caused a delay in the rise of blood pressure that began 2 days post gene delivery and lasted for more than 23 days. A maximal blood pressure reduction of 50 mm Hg was observed in rats receiving kallikrein gene delivery, as compared to rats receiving adenovirus containing the luciferase gene (Ad.CMV-Luc) (172 +/- 5 vs. 222 +/- 13 mm Hg, n = 6, P < 0.01). Throughout the experimental period, a blood pressure reduction of at least 32 mm Hg was observed in the DOCA-salt rats injected with Ad.CMV-cHK as compared to DOCA-salt rats receiving control adenovirus. Immunoreactive human tissue kallikrein levels were detected in rat serum and urine post gene delivery. Adenovirus-mediated kallikrein gene delivery caused a significant reduction in urinary excretion, urinary protein levels and body weight. Morphological examination of the kidney showed that kallikrein gene transfer significantly reduced DOCA-salt-induced glomerular sclerotic lesions, brush border disruption of proximal tubules, tubular dilatation and protein cast accumulation. These findings showed that the expression of human tissue kallikrein via gene delivery has protective effects against hypertension and renal injury in DOCA-salt hypertensive rats.

Adenoviridae↗
PubMed1999

Production of fungal fructosyl amino acid oxidase useful for diabetic diagnosis in the peroxisome of Candida boidinii.

A high-level production of fructosyl amino acid oxidase (FAOD), whose production was toxic in Escherichia coli, was investigated through attempts to utilize the peroxisome of Candida boidinii as the place for protein accumulation. The alcohol oxidase-depleted strain (strain aod1Delta) produced FAOD at a four to five times higher level than the wild type strain in terms of protein amount and enzyme activity, although the transcriptional level was similar. As a result of this study, we could improve FAOD productivity approximately 47-fold from the original transformant, and FAOD accumulated within membrane-bound peroxisomes up to 18% of the total soluble proteins.

Amino Acid Oxidoreductases↗
PubMed1999

Progressive impairment of kidneys and reproductive organs in mice lacking Rho GDIalpha.

The Rho small G protein family members regulate various actin cytoskeleton-dependent cell functions. The Rho GDI (GDP dissociation inhibitor) family, consisting of Rho GDIalpha, -beta, and -gamma, is a regulator that keeps the Rho family members in the cytosol as the GDP-bound inactive form and translocates the GDP-bound form from the membranes to the cytosol after the GTP-bound form accomplishes their functions. Rho GDIalpha is ubiquitously expressed in mouse tissues and shows GDI activity on all the Rho family members in vitro. We have generated mice lacking Rho GDIalpha by homologous recombination to clarify its in vivo function. Rho GDIalpha -/- mice showed several abnormal phenotypes. Firstly, Rho GDIalpha -/- mice were initially viable but developed massive proteinuria mimicking nephrotic syndrome, leading to death due to renal failure within a year. Histologically, degeneration of tubular epithelial cells and dilatation of distal and collecting tubules were readily detected in the kidneys. Secondly, Rho GDIalpha -/- male mice were infertile and showed impaired spermatogenesis with vacuolar degeneration of seminiferous tubules in their testes. Thirdly, Rho GDIalpha -/- embryos derived from Rho GDIalpha -/- female mice were defective in the postimplantation development. In addition, these morphological and functional abnormalities showed age-dependent progression. These results suggest that the signaling pathways of the Rho family members regulated by Rho GDIalpha play important roles in maintaining the structure and physiological function of at least kidneys and reproductive systems in adult mice.

Age Factors↗
PubMed1999

Afadin: A key molecule essential for structural organization of cell-cell junctions of polarized epithelia during embryogenesis.

Afadin is an actin filament-binding protein that binds to nectin, an immunoglobulin-like cell adhesion molecule, and is colocalized with nectin at cadherin-based cell-cell adherens junctions (AJs). To explore the function of afadin in cell-cell adhesion during embryogenesis, we generated afadin(-/-) mice and embryonic stem cells. In wild-type mice at embryonic days 6.5-8.5, afadin was highly expressed in the embryonic ectoderm and the mesoderm, but hardly detected in the extraembryonic regions such as the visceral endoderm. Afadin(-/-) mice showed developmental defects at stages during and after gastrulation, including disorganization of the ectoderm, impaired migration of the mesoderm, and loss of somites and other structures derived from both the ectoderm and the mesoderm. Cystic embryoid bodies derived from afadin(-/-) embryonic stem cells showed normal organization of the endoderm but disorganization of the ectoderm. Cell-cell AJs and tight junctions were improperly organized in the ectoderm of afadin(-/-) mice and embryoid bodies. These results indicate that afadin is highly expressed in the ectoderm- derived cells during embryogenesis and plays a key role in proper organization of AJs and tight junctions of the highly expressing cells, which is essential for proper tissue morphogenesis.

Actins↗
PubMed1999

Physostigmine antagonizes ketamine-induced noradrenaline release from the medial prefrontal cortex in rats.

Physostigmine is known to antagonize ketamine anesthesia. In this study, effects of physostigmine (0.1 mg kg(-1) i.p.) on ketamine (100 mg kg(-1) i.p.)-induced anesthesia time and noradrenaline release from the medial prefrontal cortex in rats were examined. Ketamine produced anesthesia for 27+/-1 min and increased noradrenaline release to 405% of the basal. Physostigmine significantly reduced anesthesia time to 23+/-1 min (p<0.05), and noradrenaline to 248% (p<0.05). Therefore, noradrenaline release may play an important role in ketamine anesthesia.

Anesthesia↗
PubMed1999

A single nucleotide insertion in the 5'-untranslated region of hepatitis C virus leads to enhanced cap-independent translation.

The 5'-untranslated region (5'-UTR) of hepatitis C virus (HCV) contains an internal ribosome entry site (IRES) that directs translation of the viral open reading frame (ORF). The 5'-UTR consists of 341 nucleotides (nt) in most strains, and multiple segments within this region are important for its IRES activity. Sequencing analysis of a full-length HCV cDNA clone derived from a Japanese HCV1b-positive patient showed the 5'-UTR was 342 nt long due to a nucleotide T insertion at position 207. The influence of this T insertion on the IRES activity in directing cap-independent translation was investigated. The IRES of the 5'-UTR342 was approximately five- and two- to sevenfold more active in directing luciferase expression in monocistronic and bicistronic expression systems, respectively, when compared with the IRES of the 5'-UTR341 of a previously reported HCV1b strain. In addition to the T insertion, another point mutation involving an A to C transition at position 119 was also present in the 5'-UTR342. Simultaneous comparison of the IRES activities in engineered constructs that contained each of the two mutations indicated that the insertion at position 207 is responsible for the enhanced IRES activity of the 5'-UTR342. Further determination of the abilities of the engineered 5'-UTRs harbouring A, G, or C insertions at the same position to initiate translation indicated that both T and non-T nucleotide insertions lead to enhanced cap-independent translation.

5' Untranslated Regions↗
PubMed1999

Interferon therapy reduces the risk for hepatocellular carcinoma: national surveillance program of cirrhotic and noncirrhotic patients with chronic hepatitis C in Japan. IHIT Study Group. Inhibition of Hepatocarcinogenesis by Interferon Therapy.

BACKGROUND: Previous studies on the effect of interferon therapy on the incidence of hepatocellular carcinoma have not sufficiently assessed degree of liver fibrosis, a major risk factor for hepatocellular carcinoma. OBJECTIVE: To evaluate the effect of interferon therapy on incidence of hepatocellular carcinoma, adjusting for risk factors, including the degree of liver fibrosis. DESIGN: Retrospective cohort study. SETTING: Seven university hospitals and one regional core hospital in Japan. PATIENTS: 2890 patients with chronic hepatitis C who had undergone liver biopsy since 1986. Of these patients, 2400 received interferon and 490 were untreated. MEASUREMENTS: The degree of liver fibrosis was assessed from stage F0 (no fibrosis) to stage F4 (cirrhosis). Response to interferon was determined virologically and biochemically. Screening for development of hepatocellular carcinoma was performed periodically during an average follow-up of 4.3 years. Effect of interferon therapy on the risk for hepatocellular carcinoma was analyzed by using Cox proportional hazards regression. RESULTS: Hepatocellular carcinoma developed in 89 interferon-treated patients and in 59 untreated patients. Among untreated patients, the annual incidence of hepatocellular carcinoma increased with the degree of liver fibrosis, from 0.5% among patients with stage F0 or F1 fibrosis to 7.9% among patients with stage F4 fibrosis. The cumulative incidence in treated and untreated patients differed significantly for patients with stage F2 fibrosis (P = 0.0128) and for those with stage F3 fibrosis (P = 0.0011). In multivariate analysis, interferon therapy was associated with a reduced risk for hepatocellular carcinoma (adjusted risk ratio, 0.516 [95% CI, 0.358 to 0.742]; P < 0.001), especially among patients with sustained virologic response (risk ratio, 0.197 [CI, 0.099 to 0.392]), among those with persistently normal serum alanine aminotransferase levels (risk ratio, 0.197 [CI, 0.104 to 0.375]), and among those with alanine aminotransferase levels less than two times the upper limit of normal (risk ratio, 0.358 [CI, 0.206 to 0.622]). CONCLUSIONS: Interferon therapy significantly reducesthe risk for hepatocellular carcinoma, especially among virologic or biochemical responders.

Alanine Transaminase↗
PubMed1999

Vascular endothelial growth factor can substitute for macrophage colony-stimulating factor in the support of osteoclastic bone resorption.

We demonstrated previously that a single injection of recombinant human macrophage colony-stimulating factor (rhM-CSF) is sufficient for osteoclast recruitment and survival in osteopetrotic (op/op) mice with a deficiency in osteoclasts resulting from a mutation in M-CSF gene. In this study, we show that a single injection of recombinant human vascular endothelial growth factor (rhVEGF) can similarly induce osteoclast recruitment in op/op mice. Osteoclasts predominantly expressed VEGF receptor 1 (VEGFR-1), and activity of recombinant human placenta growth factor 1 on osteoclast recruitment was comparable to that of rhVEGF, showing that the VEGF signal is mediated through VEGFR-1. The rhM-CSF-induced osteoclasts died after injections of VEGFR-1/Fc chimeric protein, and its effect was abrogated by concomitant injections of rhM-CSF. Osteoclasts supported by rhM-CSF or endogenous VEGF showed no significant difference in the bone-resorbing activity. op/op mice undergo an age-related resolution of osteopetrosis accompanied by an increase in osteoclast number. Most of the osteoclasts disappeared after injections of anti-VEGF antibody, demonstrating that endogenously produced VEGF is responsible for the appearance of osteoclasts in the mutant mice. In addition, rhVEGF replaced rhM-CSF in the support of in vitro osteoclast differentiation. These results demonstrate that M-CSF and VEGF have overlapping functions in the support of osteoclastic bone resorption.

Animals↗
PubMed1999

TGF-beta1 inhibits NF-kappaB activity through induction of IkappaB-alpha expression in human salivary gland cells: a possible mechanism of growth suppression by TGF-beta1.

Transforming growth factor (TGF)-beta is the prototype of a large superfamily of signaling molecules involved in the inhibition of proliferation of multiple epithelial cell types. Although accumulated evidence indicates the mechanisms of the antimitogenic effect of TGF-beta in a variety of cell types, the signal transduction mechanism underlying the regulation of NF-kappaB transcription factor by TGF-beta is largely unknown. Because NF-kappaB is not only involved in inflammatory responses but also mediates cell growth, we have investigated the effect of TGF-beta1 on the activity of NF-kappaB and the role of the inhibitory IkappaB-alpha protein in the growth of the human salivary gland cell clones NS-SV-AC, HSGc, and cl-1. NF-kappaB, which is usually maintained in an inactive state by protein-protein interaction with IkappaB, was found to be constitutively active in salivary gland cell lines. Upon treatment of cell clones with TGF-beta1, the NF-kappaB activity in NS-SV-AC and HSGc, but not in cl-1, which lacks the expression of TGF-beta type II receptor, was suppressed. In NS-SV-AC and HSGc, this inhibition was mediated by the induction of IkappaB-alpha at the mRNA and protein levels. The blocking of NF-kappaB subunit with a specific antisense oligonucleotide reduced the growth rate of all of the cell clones, including cl-1. Introduction of a mutated form of IkappaB-alpha cDNA into NS-SV-AC suppressed the growth rate of this cell clone. These results indicate that TGF-beta1 downregulates NF-kappaB activity through the induction of IkappaB-alpha expression in human salivary gland cells and that inhibition of NF-kappaB activity suppresses the growth rate of these cells.

Apoptosis↗
PubMed1999

A pitch glide activates an intermediate response between auditory N1 and mismatch negativity.

Pitch glides of a continuous tone elicit auditory N1-like responses. However, their characteristics have not well been investigated, and it remained unclear whether the response is an auditory true N1 or the mismatch negativity (MMN). We found here that a rapid pitch glide activates almost the same response as a true N1. On the contrary, as the rate of the pitch glide decreases, the response continuously varies the characteristics from true N1 to MMN. This suggests that there would exist intermediate responses between auditory N1 and MMN.

Acoustic Stimulation↗