Search PubMed⌕ Search

Biomedical subjects

H Yamaguchi

Publications and source records attributed to H Yamaguchi.

At least 397 records · Page 22Linked to original sources
PubMed1998

Purification, characterization and immunochemical properties of a novel 60-kDa protein of Vibrio anguillarum strains.

Vibrio anguillarum strains expressed increased amounts of a novel 60-kDa protein when cells were grown at physiologically elevated temperatures. The relative amounts of the 60-kDa protein were unaltered by changes in osmolarity or ionic concentration of the growth medium in cells grown at optimal growth temperatures. The N-terminal amino acid sequence analysis of the V. anguillarum 60-kDa protein showed extensive (94-89%) sequence identity with the 60-kDa heat shock protein of Yersinia enterocolitica and with Serratia rubidaea GroEL protein. Monoclonal antibodies against the Y. enterocolitica chaperonin reacted with the 60-kDa protein from V. anguillarum strains, and with a temperature-induced protein of similar molecular mass in other Gram-negative pathogens of fish.

Amino Acid Sequence↗
PubMed1998

Evidence for mRNA expression of vascular endothelial growth factor by X-ray irradiation in a lung squamous carcinoma cell line.

Vascular endothelial growth factor (VEGF) is a multipotent cytokine which plays an important role in various angiogenic conditions as well as in some tumor behaviors. Here we examined the induction of VEGF mRNA by X-ray irradiation in a lung squamous cell carcinoma cell line (RERF-LC-AI). Irradiating the cells with 15 Gy X-rays significantly increased the mRNA expression up to 2.5-fold of control at a post-irradiation time of 16-24 h. The induction of VEGF mRNA by X-ray irradiation was completely blocked by treating cells with either genistein (Src tyrosine kinase inhibitor) or H7 (protein kinase C inhibitor). This suggests that the mechanism of induction might be concerned with the pathway which triggers Src tyrosine kinase of the cell surface and the protein kinase C pathway.

Antineoplastic Agents↗
PubMed1998

Expanded genomic organization of conserved mammalian MHC class I-related genes, human MR1 and its murine ortholog.

MR1 is a major histocompatibility complex (MHC) class I-related gene located outside the human MHC. Among several divergent class I molecules, the predicted MR1 molecule is closest, in the alpha1 and alpha2 domains, to the class I group to which the vertebrate classical class I molecules belong. We report here the genomic organizations of the human MR1 and mouse Mr1 genes. Both genes exhibit genomic structures largely similar to those of the MHC class I genes. However, they are highly expanded in their scale in contrast to the classical MHC class I genes. Inclusion of transposable elements into introns seems to partly contribute to these genomic structures. Several other MHC class I-related genes also show relatively large genomic structures. The present study extended heterogeneity in the genomic organization among the class I gene family by revealing a highly expanded structure of the human MR1 gene and its murine ortholog.

Amino Acid Sequence↗
PubMed1998

Effects of a time-varying strong magnetic field on transient increase in cytosolic free Ca2+ induced by bradykinin in cultured bovine adrenal chromaffin cells.

We tested the effects of exposure to a time-varying magnetic field changing between 0.07 and 1.7 T at an interval of 3 s on transient increase in intracellular Ca2+ stimulated by bradykinin in bovine adrenal chromaffin cells. Addition of bradykinin induced the increase in intracellular Ca2+ within a few minutes. The exposure to the magnetic field perfectly suppressed the increase in intracellular Ca2+ in Ca2+-free medium. The inhibition occurred for 15 min when the maximum magnetic flux density was more than 1.4 T. These results suggest that the exposure inhibits Ca2+ release from intracellular Ca2+ stores.

Animals↗
PubMed1998

Presenilin 1 associates with glycogen synthase kinase-3beta and its substrate tau.

Families bearing mutations in the presenilin 1 (PS1) gene develop Alzheimer's disease. Previous studies have shown that the Alzheimer-associated mutations in PS1 increase production of amyloid beta protein (Abeta1-42). We now show that PS1 also regulates phosphorylation of the microtubule-associated protein tau. PS1 directly binds tau and a tau kinase, glycogen synthase kinase 3beta (GSK-3beta). Deletion studies show that both tau and GSK-3beta bind to the same region of PS1, residues 250-298, whereas the binding domain on tau is the microtubule-binding repeat region. The ability of PS1 to bring tau and GSK-3beta into close proximity suggests that PS1 may regulate the interaction of tau with GSK-3beta. Mutations in PS1 that cause Alzheimer's disease increase the ability of PS1 to bind GSK-3beta and, correspondingly, increase its tau-directed kinase activity. We propose that the increased association of GSK-3beta with mutant PS1 leads to increased phosphorylation of tau.

Adult↗
PubMed1998

Multiple modulation pathways of calcium channel activity by a beta subunit. Direct evidence of beta subunit participation in membrane trafficking of the alpha1C subunit.

In order to study the precise mechanisms of alpha1 subunit modulation by an auxiliary beta subunit of voltage-dependent calcium channels, a recombinant beta3 subunit fusion protein was produced and introduced into oocytes that express the human alpha1C subunit. Injection of the beta3 subunit protein rapidly modulated the current kinetics and voltage dependence of activation, whereas massive augmentation of peak current amplitude occurred over a longer time scale. Consistent with the latter, a severalfold increase in the amount of the alpha1C subunit in the plasma membrane was detected by quantitative confocal laser-scanning microscopy after beta3 subunit injection. Pretreatment of oocytes with bafilomycin A1, a vacuolar type H+-ATPase inhibitor, abolished the increase of the alpha1C subunit in the plasma membrane, attenuated current increase, but did not affect the modulation of current kinetics and voltage dependence by the beta3 subunit. These results provide clear evidence that the beta subunit modifies the calcium channel complex in a binary fashion; one is an allosteric modulation of the alpha1 subunit function and the other is a chaperoning of the alpha1 subunit to the plasma membrane.

Animals↗
PubMed1998

Identification and cloning of two novel allergens from the lipophilic yeast, Malassezia furfur.

Two novel allergens, designated Mal f 2 and Mal f 3 according to the WHO/IUIS Allergen Nomenclature Subcommittee recommendation, were isolated from the lipophilic yeast Malassezia furfur cell extracts and the genes coding for those were cloned. Mal f 2 and Mal f 3 had apparent molecular weights of 21 kDa and 20 kDa, respectively, on SDS-PAGE under reducing conditions. The identified cDNA clone of Mal f 2 encoded an open reading frame of 177 amino acid residues. Fifty-one percent identity was found between the Mal f 2 and Mal f 3 sequences. Comparison of the Mal f 2 and Mal f 3 sequences with known protein sequences revealed that they had sequence homology with two peroxisomal membrane proteins of Candida boidinii and an Aspergillus fumigatus allergen, Asp f 3. In RAST, both Mal f 2- and Mal f 3-specific IgE antibodies could be detected in approximately 70 % of sera from M. furfur sensitized patients with atopic dermatitis.

Allergens↗
PubMed1998

Redox-coupled crystal structural changes in bovine heart cytochrome c oxidase.

Crystal structures of bovine heart cytochrome c oxidase in the fully oxidized, fully reduced, azide-bound, and carbon monoxide-bound states were determined at 2.30, 2.35, 2.9, and 2.8 angstrom resolution, respectively. An aspartate residue apart from the O2 reduction site exchanges its effective accessibility to the matrix aqueous phase for one to the cytosolic phase concomitantly with a significant decrease in the pK of its carboxyl group, on reduction of the metal sites. The movement indicates the aspartate as the proton pumping site. A tyrosine acidified by a covalently linked imidazole nitrogen is a possible proton donor for the O2 reduction by the enzyme.

Animals↗
PubMed1998

Essential dynamics of DNA containing a cis.syn cyclobutane thymine dimer lesion.

Conformational properties of a UV-damaged DNA decamer containing a cis.syn cyclobutane thymine dimer (PD) have been investigated by molecular dynamics (MD) simulations. Results from MD simulations of the damaged decamer DNA show a kink of approximately 21.7 degrees at the PD damaged site and a disruption of H bonding between the 5'-thymine of the PD and its complementary adenine. However, no extra-helical flipping of the 3'-adenine complementary to the PD was observed. Comparison to two undamaged DNA decamers, one with the same sequence and the other with an AT replacing the TT sequence, indicates that these properties are specific to the damaged DNA. Essential dynamics (ED) derived from the MD trajectories of the three DNAs show that the backbone phosphate between the two adenines complementary to the PD of the damaged DNA has considerably larger mobility than the rest of the molecule and occurs only in the damaged DNA. As observed in the crystal structure of T4 endonuclease V in a complex with the damaged DNA, the interaction of the enzyme with the damaged DNA can lead to bending along the flexible joint and to induction of adenine flipping into an extra-helical position. Such motions may play an important role in damage recognition by repair enzymes.

Adenine↗
PubMed1998

The clinicopathologic significance of small areas unstained by Lugol's iodine in the mucosa surrounding resected esophageal carcinoma: an analysis of 147 cases.

BACKGROUND: Small areas unstained with Lugol's iodine are often observed in the mucosa surrounding esophageal carcinomas. METHODS: For light microscopic evaluation, the histologic features of 131 small areas unstained by Lugol's iodine in 12 selected cases were investigated. For clinicopathologic evaluation, the numbers of small areas unstained by Lugol's iodine in the mucosa surrounding 147 consecutively resected esophageal carcinomas, including these 12 cases, were counted. The relation between the incidence of such areas and the development of multiple primary cancers in the upper aerodigestive tract was examined together with data on the patients' tobacco and alcohol consumption. RESULTS: Ninety-two percent (131) of the small areas unstained by Lugol's iodine contained dysplastic lesions. Seventeen (12%) of the 147 resected specimens contained fewer than 5 small unstained areas, whereas 52 (35%) had 6-10 and 78 (53%) had more than 11 such areas. The incidence of multicentric cancer in the upper aerodigestive tract and the average alcohol index scores were significantly higher for patients who had more than 11 unstained areas than for patients who had fewer than 5 such areas (P < 0.01). CONCLUSIONS: Lugol's iodine staining method is useful for detecting groups at high risk of multicentric cancer in the upper aerodigestive tract.

Adult↗
PubMed1998

Evidence for presenilin-1 involvement in amyloid angiopathy in the Alzheimer's disease-affected brain.

Presenilin-1 (PS-1) has been identified as the protein encoded by the chromosome 14 locus that, when mutated, leads to familial Alzheimer's disease (FAD). The role PS-1 plays in the pathogenesis of Alzheimer's disease (AD) remains unclear. Using a set of antibodies raised against PS-1 synthetic peptides, polyclonal antibody to amyloid beta protein (Abeta) and end-specific antibodies against Abeta40, and Abeta42, immunohistochemical studies were performed on brain sections obtained from AD cases and controls. The PS-1 antibodies clearly stained amyloid angiopathies in AD-affected brains, but no recognizable immunoreactions were observed in any other vessels free from amyloid involvement in either AD-affected brains or controls. Abeta antibodies and the end-specific antibody against Abeta40 also decorated amyloid angiopathies, showing localization similar to that of PS-1. Western blot analyses predominantly detected protein band polypeptide species of a 50 kDa, band, presumably full-length PS-1 protein with N-terminus antisera, since these antibodies turned out to recognize a 50-kDa full-length band in cell lysate of transfected HeLa cell overexpressing PS-1. In addition, we recognized 30, 27 and 25 kDa proteins in both AD and control brain homogenate with these antibodies. In microvessel fractions extracted from brain homogenates, the 50, and 27 kDa fragments were observed in AD-affected brains but not in those of controls. C-terminus rabbit antisera reacted strongly with the 33 and 27 kDa bands, and additionally detected a small amount of full-length PS-1 protein in extracts from AD and control brains. Our present data indicate that PS-1 might be involved in the pathogenesis of amyloid angiopathy in the AD brain.

Alzheimer Disease↗
PubMed1998

Extramedullary presentation of chronic myelogenous leukemia with p190 BCR/ABL transcripts.

We present here a rare case of Philadelphia chromosome (Ph)-positive chronic myelogenous leukemia having p190 BCR/ABL with a malignant clinical picture of extramedullary blast crisis at onset, followed by rapid evolution to bone-marrow blast crisis. The patient was a 44-year-old woman presenting with leukocytosis and multiple lymph-node swelling in the neck. Lymph-node biopsy revealed a myeloperoxidase-positive blastoma with cell-surface markers of myeloid and T-lymphoid lineages. Fluorescence in situ hybridization and the reverse transcription polymerase chain reaction detected a minor BCR breakpoint but failed to detect a major BCR breakpoint. By single-strand conformation polymorphism and direct sequencing, no alteration in the TP53 gene was found, and no additional chromosomal abnormalities other than Ph were identified. The present case suggests that p190 BCR/ABL is associated with the aggressive course of the disease.

Adult↗
PubMed1998

Anandamide amidohydrolase reacting with 2-arachidonoylglycerol, another cannabinoid receptor ligand.

Two endogenous ligands for cannabinoid receptors, anandamide (arachidonylethanolamide) and 2-arachidonoylglycerol, lose their biological activities by enzymatic hydrolysis. A cDNA for a rat liver enzyme hydrolyzing anandamide as well as oleamide was overexpressed in COS-7 cells. When the particulate fraction was allowed to react with 2-arachidonoylglycerol, arachidonic acid was produced. In contrast, this hydrolytic reaction did not occur with the control cells. The hydrolysis of 2-arachidonoylglycerol proceeded about 4-fold faster than the anandamide hydrolysis with a Km value as low as 6 microM and an optimal pH of 10. Phenylmethylsulfonyl fluoride and methyl arachidonyl fluorophosphonate inhibited the hydrolysis of both anandamide and 2-arachidonoylglycerol in parallel. Furthermore, the hydrolysis of [14C]2-arachidonoylglycerol was inhibited by anandamide dose-dependently. These results suggest that anandamide and 2-arachidonoylglycerol can be inactivated by the same enzyme.

Amidohydrolases↗
PubMed1998

Helicobacter pylori promotes development of pepsinogen-altered pyloric glands, a preneoplastic lesion of glandular stomach of BALB/c mice pretreated with N-methyl-N-nitrosourea.

H. pylori is thought to be a stomach carcinogen. Since no experimental model has hitherto been established to clarify the relationship between H. pylori and stomach carcinogenesis, the effects of infection with the bacteria on experimental carcinogenesis in the glandular stomach of mice were investigated. BALB/c mice were given salty diet or N-methyl-N-nitrosourea (MNU) and administered broth culture of H. pylori. The incidence of pepsinogen-altered pyloric glands, considered as precancerous lesions, was increased in the H. pylori inoculated group pre-treated with MNU. The findings provide the new experimental model demonstrating the relationship between stomach cancer and H. pylori.

Animals↗
PubMed1998

Establishment of a cell line with variant BCR/ABL breakpoint expressing P180BCR/ABL from late-appearing Philadelphia-positive acute biphenotypic leukemia.

In acute leukemia (AL) with a late-appearing Philadelphia (la-Ph) translocation, it is unclear whether these translocations arise from the same molecular event as classical Ph translocations. In order to elucidate the molecular events of la-Ph and subsequent translocations of la-Ph leukemia, we performed molecular analysis on the complex rearrangements, in a cell line, MY, which was established from bone marrow mononuclear cells of a patient with a la-Ph acute biphenotypic leukemia. This la-Ph, expressing an acute lymphoblastic leukemia (ALL)-type BCR/ABL transcript, produces a novel P180BCR/ABL fusion protein reflecting deletion of 174 bases (58 amino acids) encoded by the a2 exon of the ABL gene. An immune complex kinase assay showed that this protein had autophosphorylation activity. Fluorescence in situ hybridization (FISH) in conjunction with G-banding analysis revealed that the initial der(9)t(9;22)(q34;q11) progressed to a der(9)(9pter-->9q34::22q11-->22q13::5q11.2 -->5q15:: 10q23-->10qter) by, first, a three-way translocation among the der(9)t(9;22)(q34;q11), chromosome 5, and the normal chromosome 22, and then a subsequent translocation with chromosome 10. Moreover, both the end-stage leukemic cells of the patient and the MY cell line had another translocation, t(X;12)(p11.2;p13). The 12p breakpoint was located near the ETV6 gene by analysis of pulsed-field gel electrophoresis, but transcription of ETV6 was unaffected. Tumorigenicity analysis indicated that an additional translocation, t(2;3)(p16;q29), may have caused a more malignant clone, because only MY cells with the t(2;3)(p16;q29) were capable of growing subcutaneously in nude mice within 40 days. The molecular events of leukemogenesis and leukemic progression in the present la-Ph AL occurred by accumulation of unique translocations. This cell line, MY, expressing a novel variant P180BCR/ABL protein with a deletion of the a2 exon of the ABL gene, may be useful for elucidating the pathophysiology of this fusion protein and for studying ETV6-related leukemogenesis and t(2;3), as well as the molecular mechanisms of the complex translocations.

Amino Acid Sequence↗
PubMed1998

Prevalence of IgG anti-Der p 2 antibodies in children from high and low antigen exposure groups: relationship of IgG and subclass antibody responses to exposure and allergic symptoms.

Serum IgG PAN, IgG1-4, and IgE antibodies (Ab) specific for the house dust mite Dermatophagoides antigen (Ag) Der p 2 were measured by enzyme-linked immunosorbent assay (ELISA) in two groups of school children, age 12-14, exposed to high (Charlottesville, VA) and low (Los Alamos, NM) mite Ag levels in their environment. More than 90% of the children were found to have Der p 2-specific IgG antibodies, although the levels of both IgG PAN and IgG 1-4 Ab were substantially higher in the high exposure group (P = 0.001). In addition, there was considerable overlap between these two groups in all Ab measurements. The presence of IgG anti-Der p 2 Ab in the Los Alamos children was unexpected and suggests continuing Ag exposure, although the source of such exposure is not apparent. There is no correlation between RAST (+) and RAST (-) subjects with respect to the level of IgG Ab measured by ELISA. These results suggest that the IgG Ab response to house dust mite has been underestimated in the RAST negative population. Two twin pairs were included in this study and the divergent and varied Ab responses in these individuals indicate that factors in addition to environmental exposure and genetic susceptibility require further investigation and provide evidence for the complexity of the pathogenesis of the allergic response.

Adolescent↗
PubMed1998

The present mercury contents of scalp hair and clinical symptoms in inhabitants of the Minamata area.

A total of 191 fishermen and their family (32-82 years) living in some mercury-polluted areas along the Shiranui Sea volunteered for the present study. They made a living by fishery and had formerly eaten the methyl mercury-contaminated fish and shellfish caught there. The questionnaire on subjective symptoms, fish eating habits, and past living history was conducted on the subjects. In addition, they were clinically examined in detail by several neurologists and scalp hair was collected. With six exceptions, all the 185 subjects showed a normal total mercury level in hair (<10 ppm). The ratio of methyl mercury to total mercury was 79-94% on the average for each group examined, suggesting indirect contamination (perhaps through the food chain). Despite their low mercury level in scalp hair, however, the subjects showed various neurological symptoms, particularly, sensory disturbance (such as the glove and stocking type), at a very high rate. Thus, it seems fair to state that, in addition to officially recognized Minamata disease patients, there still exist many people with atypical, slight Minamata disease on the coast of the Shiranui Sea. The current hair mercury level is not necessarily useful as a criterion for diagnosing chronic Minamata disease because of the long lapse of time.

Adult↗