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Biomedical subjects

M Iwabuchi

Publications and source records attributed to M Iwabuchi.

At least 55 records · Page 3Linked to original sources
PubMed1997

Structural characteristics of two wheat histone H2A genes encoding distinct types of variants and functional differences in their promoter activity.

To investigate the regulation of plant histone H2A gene expression, we isolated two H2A genes (TH254 and TH274) from wheat, which encode two variants of H2A. Both genes had an intron in the coding region. In the promoters, some characteristic sequences, such as Oct and Nona motifs, which are conserved among plant histone genes, were located in a short region (about 120 bp) upstream from the putative TATA box. Transient expression analyses of promoter activity with H2A-GUS fusion genes using tobacco protoplasts revealed novel types of positive cis-acting sequences in the TH254 promoter: a direct repeat of a 13 bp sequence (AGTTACATTATTG) and a stretch composed of an AT-rich sequence (ATATAGAAAATTAAAA) and a G-box (CACGTG). Quantitative S1 assay of the mRNA amounts from the TH254/GUS and TH274/GUS chimeric genes in stably transformed and cell cycle-synchronized tobacco cell lines showed that the promoters of both genes contained at least one cis-acting element responsible for S phase-specific expression. Histochemical analysis of transgenic tobacco plants carrying the chimeric genes showed that the promoters of the two H2A genes were active in developing seedlings and flower organs but were regulated in a different manner.

Amino Acid Sequence↗
PubMed1997

Adrenal adenoma with bilateral adrenocortical nodular change in a patient with Cushing's syndrome.

We report a 57-year-old male patient with adrenocorticotrophin (ACTH)-independent Cushing's syndrome and long-standing hypertension. Both abdominal computed tomographic scan and magnetic resonance imaging revealed bilateral adrenal enlargement with the presence of a tumour in the left adrenal. Marked uptake of 131I-6 beta-iodomethyl-19-norcholesterol was observed only in the left adrenal gland. Left adrenalectomy and biopsy of the right adrenal gland were subsequently performed. Histological examination revealed the presence of an adrenocortical adenoma in the left adrenal with multiple adrenocortical nodules in both left and right non-neoplastic adrenals. Peri- and intraadrenal arteries and arterioles demonstrated marked arteriosclerotic vascular changes. Immunoreactivity for several steroidogenic enzymes was present in the tumour and markedly diminished in the non-neoplastic adrenals. This patient with Cushing's adenoma is considered to have developed adrenocortical nodules in the nonneoplastic adrenal possibly as a result of localized compensatory overgrowth of adrenocortical cells in response to ischaemic changes due to arteriopathy. When examining patients with Cushing's syndrome and bilateral adrenal enlargement, the possibility of concomitant adenoma and adrenocortical nodule formation should also be considered in the differential diagnosis

3-Hydroxysteroid Dehydrogenases↗
PubMed1997

Clinicopathological studies on coexisting gastric malignant lymphoma and gastric adenocarcinoma: report of four cases and review of the Japanese literature.

Among 121 cases of primary gastric malignant lymphoma from 1962 to 1994 at the National Cancer Center Hospital, Tokyo, we found four cases (three males and one female) of adenocarcinoma coexisting in the stomach. The incidence of gastric malignant lymphoma together with gastric adenocarcinoma was 3.3%, suggesting that patients with lymphoma may have an increased incidence of gastric adenocarcinoma. A review of the Japanese literature revealed an additional 62 patients who developed coexisting gastric malignant lymphoma and adenocarcinoma. In the total series of 66 patients whose age and sex were recorded, there were 48 males with a mean age of 63.8 years and 18 females with a mean age of 58.6 years. Most adenocarcinomas were macroscopically early (76%) and of histologically differentiated type (75%). Conversely, 71% of lymphomas were of the advanced type macroscopically. The correct preoperative diagnoses were made in only 27% (16/59) of cases, when both tumors were located independently.

Adenocarcinoma↗
PubMed1997

A strain of calicivirus isolated from lions with vesicular lesions on tongue and snout.

In December 1992, 17 African lions and 7 Siberian tigers in a Safari park in Japan became sick with characteristic clinical symptoms of acute vesicular formations on tongue and snout. The disease was highly contagious since all of these animals showed similar symptoms within two days after the onset of the first case. Swabs were taken from affected animals in rubbing tongues, snouts and some from rectums. Cytopathic viruses were isolated on CRFK cell culture by virological tests. The physicochemical property of a representative virus strain, named Arthur/L, isolated from a male lion was identified as a member of Caliciviridae. However, seroneutralization test indicated that this virus strain was antigenically distinct from Japanese isolates of feline caliciviruses used for comparison. Viral capsid proteins of the present isolate, Arthur/L, and of a feline calicivirus, strain FC7, were compared in an electrophoresis in SDS-PAGE gel. The major viral capsid polypeptide of them were proved to be significantly different in molecular weight. The polypeptide of FC7 was estimated to be ca. 63 KDa whereas that of Arthur/L consisted of 2 components of ca. 65 and 62 KDa. The viral proteins of these two strains were also proved to be distinct by an immunoblotting test.

Animals↗
PubMed1997

Adenovirus isolation from spleen lymphocytes of apparently healthy pigs.

A polyethylene glycol treatment was given to fuse KSEK6 cells, an established cell line derived from porcine embryo kidney, with the lymphocytes, separated from spleens of 35 apparently healthy slaughtered pigs. Eight cytopathic virus strains were isolated from the lymphocytes of these pigs. Two virus strains were isolated by inoculating the spleen tissue homogenates to KSEK6 monolayer cultures. All of viruses were identified as porcine adenoviruses according to their physicochemical, serological and immunological properties. One of these virus strains was serologically proved to be independent from six serotypes of porcine adenoviruses ever known. The electrophoretic property of viral DNA of this strain was indicated to be different from those of other reference porcine adenoviruses. This means the presence of a 7th serotype in porcine adenoviruses.

Adenoviridae↗
PubMed1996

HALF-1, a bZIP-type protein, interacting with the wheat transcription factor HBP-1a contains a novel transcriptional activation domain.

BACKGROUND: Nuclear factors bind to cis-acting elements and mediate transcriptional regulation through protein-protein interactions with other factors. The bZIP-type wheat nuclear protein HBP-1a(17) is a putative transcriptional activator specifically binding to the Hex (ccACGTCA) and G-box (CCACGTGG) motifs, which are often found in the cis-acting elements critical for various responses in plants. RESULTS: In order to investigate the mechanisms for gene expression mediated via the Hex and G-box motifs, we attempted to isolate proteins interacting with HBP-1a(17) based on protein-protein interactions. A cDNA expression library from wheat seedlings was screened with 32P-labelled HBP-1a(17), and a bZIP-type protein, termed HALF-1 (HBP-1-associated leucine-zipper factor-1), was isolated. GST-pulldown assay, yeast two-hybrid system and EMSA showed that HALF-1 and HBP-1a(17) interact with each other through their leucine-zipper regions. Dissection experiments showed that HALF-1 has at least one potential trans-activation domain which includes a nine amino acid motif conserved between several plant bZIP-type proteins. This motif, named GCB (GBF-conserved box; consensus, NLNIGMDXW), activated the expression of a reporter gene, when fused to the GAL4 DNA-binding domain. The corresponding region of Arabidopsis GBF1 also stimulated transcription. However, the trans-activation domain of HALF-1 did not function in yeast. CONCLUSIONS: We identified a novel trans-activation domain which contains the GCB motif conserved among plant bZIP-type factors. The trans-activation appears to be mediated by interaction between the GCB motif and a factor conserved in plants.

Amino Acid Sequence↗
PubMed1996

A zinc-finger-type transcription factor WZF-1 that binds to a novel cis-acting element of histone gene promoters represses its own promoter.

WZF-1 is a zinc-finger protein which binds to the wheat histone gene promoter. Southwestern-binding analyses revealed that it bound a CACTC sequence, a novel positive cis-acting element. The activity of WZF-1 gene promoter, containing six CACTC sequences, was markedly reduced when WZF-1 was co-expressed, suggesting that WZF-1 is a transcriptional repressor.

Base Sequence↗
PubMed1996

A rare case of ectopic antidiuretic hormone-producing pancreatic adenocarcinoma: new diagnostic approach.

We describe a 73-year old man with the syndrome of inappropriate antidiuretic hormone secretion (SIADH) due to an ectopic ADH-producing pancreatic adenocarcinoma. His laboratory findings showed marked hyponatremia, and the water load test showed uncontrolled ADH secretion. The imaging studies revealed pancreatic body cancer. Histological examination revealed an adenocarcinoma of the pancreas, which was positive for ADH immuno-staining. The ADH in the tumor extract was 53.3 pg/g wet weight. In attempt to diagnose ADH-production from the tumor, the ADH in his pancreatic juice was measured and found to be 2.1 pg/ml. We conclude that it is valid to measure the ADH in pancreatic juice to diagnose ectopic ADH production by tumors.

Adenocarcinoma↗
PubMed1995

Developmental and tissue-specific regulation of the gene for the wheat basic/leucine zipper protein HBP-1a(17) in transgenic Arabidopsis plants.

Wheat basic/leucine zipper protein HBP-1a(17) binds in vitro specifically to ACGT motif-containing cis-acting elements, such as the type I element of plant histone promoters and the G-box of hormone- and light-inducible promoters. To address the in vivo function of HBP-1a(17), we isolated and structurally analyzed the HBP-1a(17) gene and examined its expression in transgenic Arabidopsis plants. The HBP-1a(17) gene is composed of 14 exons; the basic region and leucine zipper are encoded by separate small exons, as is the case for other bZIP protein genes. The G-box of the HBP-1a(17) promoter bound specifically to HBP-1a(17) and its related HBP-1a isoforms, suggesting that the HBP-1a(17) gene may be autoregulated, although the binding affinity of these proteins in vitro is very low. In Arabidopsis plants, activation of the HBP-1a(17) promoter was highly restricted to photosynthetically active mesophyll, and guard cells and vascular bundles of vegetative leaves. Etiolation of transgenic plants resulted in inhibition of expression of the HBP-1a(17) promoter. Indeed, the HBP-1a(17) promoter contains several sequence elements homologous to cis-acting elements conserved in light-inducible promoters. It is, therefore, assumed that the HBP-1a(17) gene is light regulated and that HBP-1a(17) is involved in light-responsive gene transcription via the G-box.

Amino Acid Sequence↗
PubMed1995

Differential expression of the two types of histone H2A genes in wheat.

Five histone H2A cDNA clones have been isolated from a wheat cDNA library. They were divided into two groups, termed type 1 and type 2, based on their deduced amino acid sequences and their gene expression patterns. Three type 1 clones had ORFs encoding proteins similar to angiosperm histone H2As known so far, whereas two type 2 clones encoded an identical protein, which was more similar to Norway spruce (gymnosperm) H2A than to the angiosperm H2As. The C-terminus of the type 2 H2A was shorter than that of the type 1 H2As and lacked the characteristic SPKK motif that is conserved in angiosperm H2As. Northern analysis revealed that the mRNA levels of the type 1 H2A genes were high in proliferating cells during germination and in various tissues of young seedlings, while the mRNA levels of the type 2 genes were high in non-proliferating cells in which the type 1 gene was poorly expressed. This result suggests that the expression of these two groups of H2A genes is differently regulated during development in wheat.

Amino Acid Sequence↗
PubMed1995

Isolation of porcine adenovirus as a candidate of 5th serotype.

A strain of cytopathic virus, named strain TG/K79, was isolated from the brain of a newborn piglet, pure Hampshire breed, which died shortly after birth. The physicochemical property of virus was considered to be that of the family Adenoviridae. A significant difference between our isolated and 4 reference porcine adenoviruses was demonstrated by cross-seroneutralization test. Differences between TG/K79 and other porcine adenoviruses were also seen in electrophoretic patterns of viral DNA in agarose gel after digested by restriction endonucleases. Two SPF pigs, 2-month-old, experimentally infected via intranasal showed a fever and a hemorrhagic enteritis. A serological survey indicates that at least swine in the farm where the virus was isolated have been highly contaminated.

Adenoviridae Infections↗
PubMed1995

A type I element composed of the hexamer (ACGTCA) and octamer (CGCGGATC) motifs plays a role(s) in meristematic expression of a wheat histone H3 gene in transgenic rice plants.

Type I element (CCACGTCACCGATCCGCG) is a well-conserved regulatory element found in proximal promoter region of a certain class of plant histone genes, that is composed of two independent cis-acting elements of the hexamer (ACGTCA) and the reverse-oriented octamer (GATCCGCG) motifs. To investigate functional role(s) of the type I element in regulation of a wheat histone H3 gene (TH012) promoter activity in vivo, base substitution mutations were introduced into the element and activities of the mutated promoters were examined in cultured rice cells, and in regenerated roots and anther walls of transgenic rice plants by employing a GUS reporter system. Mutations of each or both of the hexamer and the octamer motifs caused a reduction in the promoter activity in protoplasts transfected transiently or stably transformed calli. The mutation of the octamer motif with or without the mutation of the hexamer motif caused a marked reduction of the promoter activity in the root meristem of transgenic rice although the mutation of the hexamer motif alone caused a weak reduction. In contrast to these results, no effect of the mutations of either the hexamer or the octamer motif was found in the anther wall in which replication-independent activity of the H3 promoter was observed. Our results suggested that the hexamer and the octamer motifs may play important role(s) in regulation of replication-dependent but not of replication-independent expression of the wheat histone H3 gene.

Base Sequence↗
PubMed1995

Structural and functional characterization of two wheat histone H2B promoters.

Two wheat histone H2B genes (TH123 and TH153) were isolated. Nucleotide sequence analysis revealed that some characteristic sequence motifs were conserved in both the 5'- and 3'-flanking regions. A canonical TATA box and several CCAAT sequences were present in the presumed promoter regions. Motifs similar or identical to the hexamer (ACGTCA) and octamer (CGCGGATC) motifs that are positive cis-acting elements of the wheat H3 (TH012) promoter were also observed in both the H2B promoters. A gel mobility shift assay indicated that the hexamer and hexamer-like motifs bound the wheat bZIP proteins HBP-1a and/or HBP-1b in vitro. A novel sequence motif, (A/T)(G/A)AAAT(A/G), was found downstream of a translational stop codon as observed in several plant histone H2B cDNAs. Promoter activity was analyzed with H2B promoter-GUS fusion genes in the transient system using tobacco protoplasts. Studies of the promoter function in transgenic tobacco plants showed that the H2B promoters were preferentially active in meristematic tissues. Taken together, our data indicate that the H2B genes are regulated, in part, by the same mechanism as found in H3 and H4 gene transcription.

Amino Acid Sequence↗
PubMed1995

The role of sodium in mediating adrenocorticotropin secretion by perifused rat anterior pituitary cells.

We studied the role of sodium ions in mediating basal and stimulated ACTH release from perifused rat anterior pituitary cells by exposing the cells to the sodium channel opener veratridine or the Na+/K(+)-adenosine triphosphatase inhibitor ouabain to increase the intracellular Na+ concentration or, conversely, by omitting Na+ from the perifusion medium or blocking Na+ entry into the cell with tetrodotoxin, a voltage-dependent sodium channel blocker, to decrease the intracellular Na+ concentration. Neither tetrodotoxin nor Na(+)-free medium had a significant effect on 100 nM arginine vasopressin (AVP) or 10 nM ovine corticotropin-releasing hormone (CRH)-induced ACTH secretion. Veratridine increased basal ACTH secretion by 122% (41.3 +/- 2.9 vs. 18.6 +/- 0.4 pg/min; P < 0.001), the initial spike phase of the response to AVP by 65% (0.28 +/- 0.01 vs. 0.17 +/- 0.03 ng/3 min; P < 0.005), the subsequent sustained phase to AVP by 129% (0.16 +/- 0.01 vs. 0.07 +/- 0.01 ng/7 min; P < 0.005), and the total response to CRH by 70% (0.39 +/- 0.01 vs. 0.23 +/- 0.04 ng/10 min; P < 0.05). Ouabain increased basal ACTH secretion by 39% (45.7 +/- 2.8 vs. 32.9 +/- 2.1 pg/min; P < 0.05), the initial spike phase of the response to AVP by 88% (0.32 +/- 0.02 vs. 0.17 +/- 0.01 ng/3 min; P < 0.005), the sustained phase response to AVP by 67% (0.10 +/- 0.01 vs. 0.06 +/- 0.01 ng/7 min; P < 0.05), and the total integrated response to CRH by 49% (0.88 +/- 0.09 vs. 0.59 +/- 0.03 ng/10 min; P < 0.05). However, the effects of both veratridine and ouabain on basal ACTH secretion were significantly attenuated in Ca(2+)-free EGTA-containing medium, suggesting that this effect was indirect, due to membrane depolarization and consequent influx of extracellular Ca2+. Dexamethasone (100 nM) had no effect on the ACTH response to either veratridine or ouabain. We conclude that changes in the intracellular Na+ concentration and sodium channel activity are not directly involved in AVP- or CRH-induced ACTH secretion.

Adrenocorticotropic Hormone↗