Biomedical subjects

K Ohyama

Publications and source records attributed to K Ohyama.

At least 55 records · Page 3Linked to original sources

PubMed2000

Dilated cardiomyopathy in Noonan's syndrome: a first autopsy case.

The first autopsy case of dilated cardiomyopathy associated with Noonan's syndrome is described. A 9-month-old girl with Noonan's syndrome died from cardiac failure. Autopsy showed biatrial and biventricular enlargement of the heart. The posterior half of the ventricular septum and right ventricular wall were remarkably thin. Other parts of the wall were nearly normal in thickness, but both ventricular cavities were dilated. Microscopically, the myocardium of both ventricles consisted of mainly abnormally thinned, elongated, and loosely arranged myocardial fibers lacking immunoreactivity to anti-dystrophin antibody. Myocardial disarray was not found except for where it normally existed. The abnormal changes of the myocardial fibers were considered to be primary. Common cardiomyopathy associated with Noonan's syndrome is a hypertrophic type. Various types of cardiovascular abnormality associated with Noonan's syndrome, including dilated cardiomyopathy, might be disclosed by further investigation and precise diagnosis of Noonan's syndrome.

Cardiomyopathy, Dilated↗

PubMed2000

[Apoptotic cell death induced by actinomycin D arisen at different levels and cell cycle stages according to human cultured cell species].

Nine kinds of human cultured cells, including fetus cells (smooth chorion trophoblast cells, amnion epithelial cells and HE-21), adult non-carcinoma cells (HCF), and carcinoma cells (KATO-III, COLO 201, Lu-134-AH, SK-OV-3 and SKG-3a) were stimulated with Actinomycin (Act.) D for 24 h. Apoptosis induction was investigated by agarose gel electrophoresis for DNA fragmentation analysis and by flow cytometric analysis of stained cells using in situ terminal deoxynucleotidyl-transferase (TdT)-mediated dUTP nick-end labeling TUNEL) staining techniques for the quantification of apoptosis, and simultaneously using propidium iodide for the gain of some information about cell cycle. By agarose gel electrophoresis, DNA fragmentation of these cells except amnion epithelial and SKG-3a cells was detected, depending on concentration of Act. D. Using flow cytometric analysis, these cells were separated into four groups according to the information about cell cycle. Group 1 included amnion epithelial and SKG-3a cells, which were TUNEL negative. In group 2, all cell populations at G0/G1 and G2/M phases of HCC, KATO-III and SK-OV-3 were TUNEL staining positive. A portion of each G0/G1 or G2/M phase cell of Lu-134-AH and COLO 201 in group 3 was TUNEL stain positive. In group 4, G2/M phase cells of smooth chorion trophoblast cells and HE-21 were mostly stained and a small population of G0/G1 phase cells were also TUNEL stain positive. These results show that the stages of the cell cycle at which apoptosis was arisen by Act. D stimulation were significantly different depending on the cells types.

Amnion↗

PubMed2000

Systematic isolation of highly transcribed genes in inflorescence apices in Arabidopsis thaliana from an equalized cDNA library.

To analyze plant meristem functions, we systematically isolated thirteen cDNA clones for transcripts that are highly expressed in the inflorescence apices of Arabidopsis by differential screening, using an equalized cDNA library with the clones arrayed on membranes. Their deduced amino acid sequences indicate important functions for proteins in determining the cell wall architecture, translation capacity and mitotic activity in the shoot apex during reproductive growth.

Arabidopsis↗

PubMed2000

[Identification of bacterial strain at each episode of recurrent acute otitis media].

This study was undertaken to investigate whether each episode of recurrent acute otitis media (rAOM) is caused by the same strain of bacteria or different strains at each episode. Seventy infants less than 3-years of age, having experienced rAOM for a period shorter than 8 weeks, were selected and included in the present study. The total number of AOM episodes experienced by this group was 282. At each subsequent episode of AOM, otorrhea and nasopharyngeal swabs were taken for bacterial culture and determination of the MIC for antibiotics. When S. pneumoniae was identified, its serotype, and its pbp, ermAM, and mefE genes were also investigated to determine the bacterial species and strains. S. pneumoniae was the most frequently cultured bacteria with 26 penicillin-sensitive S. pneumoniae (PSSP), 65 penicillin-insensitive S. pneumoniae (PISP), and 50 penicillin-resistant S. pneumoniae (PRSP). H. influenzae was the next most frequently cultured bacteria of which 65 were sensitive to penicillin, 27 were found to be beta-bactamase-negative-ampicillin-resistant (BLNAR) and 17 were found to be beta-bactamase positive. Bacteria cultured from each pair of two successive episodes of AOM were compared as to the identity of the bacteria during the two episodes. In 150 out of 202 pairs (74%), the cultured pathogen was different. In 22 cases in which either PISP or PRSP was the pathogen detected in two consecutive AOM episodes, 15 cases (68%) were found in which the involved strain differed between the two episodes. This study indicates that the pathogen involved in rAOM is likely to differ at each episode of AOM, not only in cases caused by PSSP, but also in those caused by PRSP.

Acute Disease↗

PubMed2000

Biosynthesis of Vicia graminea lectin- and Vicia unijuga lectin-binding glycoproteins in human tumor and nontumor cells and an estimation of its epitope structure.

We investigated biosynthesis of Vicia graminea lectin (VGA)- and Vicia unijuga lectin (VUA)-binding (Vgu) glycoproteins, which are human malignant tumor-associated antigens, in cultured human tumor and non-tumor cells by pulse-labeling experiments with [35S]-methionine, followed by immunoprecipitation using immobilized VUA, SDS-PAGE and autofluorography. It was shown that Vgu glycoproteins synthesized by tumor cells were 15-30 times greater than those of non-tumor cells. It was also shown that about 40-70% of Vgu glycoproteins synthesized by non-tumor cells were secreted from the cells while more than 80% of the antigen synthesized by tumor cells was not secreted, and that Vgu glycoproteins consisted of multiple molecular species with the same epitope. To estimate the epitope structure of Vgu glycoproteins, in preliminary experiments we prepared sialoglycoproteins and/or sialoglycopeptides from purified human glycophorin A. Human glycophorins A(M) and A(N) (GPs-A(M) and A(N)) were treated with Clostridium perfringens neuraminidase to remove all sialic acid residues linked to carbohydrate chains, with Newcastle disease virus (NDV) to remove alpha2-3 linked sialic acid residues, and by Edman's degradation to eliminate N-terminal amino acid of GP-As. Partial or complete desialylation reactions resulted in disappearance of the reactivity of GP-A(M) and GP-A(N) with corresponding antisera and in appearance of reactivities with VUA and VGA. Elimination of N-terminal amino acid of GP-As also resulted in appearance of reactivities with VUA. These results show that sialoglycoproteins with similar serological properties of Vgu glycoprotein could be prepared from GP-As, and suggest that the epitope structure of Vgu glycoprotein may be related to the MN blood type-epitope structure and its sialic acid residues at N-terminal moiety of GP-As.

Amnion↗

PubMed2000

A significant role of human cytochrome P450 2C8 in amiodarone N-deethylation: an approach to predict the contribution with relative activity factor.

Human cytochrome P450 (CYP) isoforms involved in amiodarone N-deethylation were identified, and the relative contributions of these CYP isoforms were evaluated in different human liver microsomes. The mean K(M) and V(max) values of amiodarone N-deethylation in microsomes from six human livers were 31.6 +/- 7.5 microM and 1.2 +/- 0.7 pmol/min/pmol of CYP, respectively. Ketoconazole and anti-CYP3A antibodies strongly inhibited amiodarone N-deethylase activity in human liver microsomes at a substrate concentration of 50 microM. Of 15 recombinant human CYP enzymes (19 preparations), CYP1A1, CYP3A4, CYP1A2, CYP2D6, CYP2C8, and CYP2C19 catalyzed amiodarone N-deethylation. The amiodarone N-deethylase activity at a substrate concentration of 5 microM was significantly correlated with the paclitaxel 6alpha-hydroxylase activity (r = 0.84, P <.05) in the human liver microsomes, whereas the amiodarone N-deethylase activity at 100 microM was significantly correlated with the testosterone 6beta-hydroxylase activity (r = 0.94, P <.005). According to the concept of relative activity factor, it was clarified that CYP2C8 as well as CYP3A4 were significantly involved in amiodarone N-deethylation in human livers at clinically significant concentrations and that the contributions of CYP1A2, CYP2C19, and CYP2D6 were relatively minor. However, there was a large interindividual variability in the contribution of each CYP isoform to amiodarone N-deethylase activity in human liver; the relevance of these enzymes would be dependent on the content of the respective isoforms and on the amiodarone concentration in the liver.

Alkylation↗

PubMed1999

Systematic isolation of genes expressed at low levels in inflorescence apices of Arabidopsis thaliana.

We constructed an equalized cDNA library from Arabidopsis inflorescence shoot apices including inflorescence meristem, floral meristem and flower tissue collected before stage 5 of flower development. The cDNA clones were arrayed on membranes and were differentially screened using cDNA pools from vegetative and inflorescence tissues as probes. Each clone was classified by expression specificity and expression level. By removing the clones that displayed hybridization signals, 384 out of 3264 clones in this library remained as candidates for inflorescence-specific mRNAs expressed at low levels. Sequence analysis of all selected clones indicated that 53 were identical and 120 were homologous to genes in public protein databases. The remaining 211 selected clones had no significant amino acid sequence similarities with those deduced from any reported genes, though 62 of them appeared in Arabidopsis expressed sequenced tags (ESTs). About 40% of the selected clones were novel, validating the present approach for gene discovery. Northern blot analysis of 22 randomly selected clones confirmed that most were expressed preferentially in inflorescence tissues. In addition, many clones were transcribed at relatively low levels. We demonstrate that the screening method of the present study is useful for systematic classification of cDNA species based on expression specificity.

Animals↗

PubMed1999

The roles of diesel exhaust particle extracts and the promotive effects of NO2 and/or SO2 exposure on rat lung tumorigenesis.

This experiment was carried out to clarify the roles of diesel exhaust particle (DEP) extracts and the promotive effects of nitrogen dioxide (NO2) and/or sulfur dioxide (SO2) exposure on rat lung tumorigenesis. F344 male rats were intratracheally administered DEP extract-coated carbon black particles (DEcCBP) and exposed to 6 ppm NO2 and/or 4 ppm SO2 for 10 months. At 18 months after starting the experiment, lung lesions were histopathologically investigated and DNA in rat lungs was analyzed for the presence of adducts using the 32P-postlabeling assay. Infiltration of alveolar macrophages, which was significant in the lungs of rats administered carbon black particles, was not prominent in those administered DEcCBP. DEcCBP occasionally formed small hyaline masses in the alveolar ducts and alveolar bronchiolization developed in the epithelium of alveolar ducts near the masses. Lung tumorigenesis and DNA aduct formation were observed in the animals administered DEcCBP with exposure to NO2 and/or SO2, but not in those administered DEcCBP alone. The results of the present study suggested that DEP extracts eluting from the small masses cause DNA damage in alveolar epithelial cells and alveolar epithelial cell proliferation, and that NO2 and/or SO2 exposure promote lung tumor induction by DEP extracts.

Animals↗

PubMed1999

Expressed sequence tags from immature female sexual organ of a liverwort, Marchantia polymorpha.

A total of 970 expressed sequence tag (EST) clones were generated from immature female sexual organ of a liverwort, Marchantia polymorpha. The 376 ESTs resulted in 123 redundant groups, thus the total number of unique sequences in the EST set was 717. Database search by BLAST algorithm showed that 302 of the unique sequences shared significant similarities to known nucleotide or amino acid sequences. Six unique sequences showed significant similarities to genes that are involved in flower development and sexual reproduction, such as cynarase, fimbriata-associated protein and S-receptor kinase genes. The remaining unique 415 sequences have no significant similarity with any database-registered genes or proteins. The redundant 123 ESTs implied the presence of gene families and abundant transcripts of unknown identity. Analyses of the coding sequences of 61 unique sequences, which contained no ambiguous bases in the predicted coding regions, highly homologous to known sequences at the amino acid level with a similarity score greater than 400, and with stop codons at similar positions as their possible orthologues, indicated the presence of biased codon usage and higher GC content within the coding sequences (50.4%) than that within 3' flanking sequences (41.9%).

Amino Acid Sequence↗

PubMed1999

Chondrocyte death is linked to development of a mitochondrial membrane permeability transition in the growth plate.

In the companion article, we reported that the local phosphate (Pi) concentration triggers apoptosis in epiphyseal chondrocytes. The goal of the current investigation was to evaluate the apoptotic process in relationship to the energy status of cells in the growth plate. For these studies, we used sections of the adolescent growth plate, as well as cells isolated from the tissue. We found that there was a maturation-dependent loss of mitochondrial function in growth plate chondrocytes and these cells generated energy by glycolysis. Since treatment with the uncoupler 2,4-dinitrophenol as well as the site-specific inhibitors antimycin A and rotenone failed to elicit a further increase in the activity of the glycolytic pathway, we concluded that oxidative metabolism was minimum in these cells. Flow cytometric studies of growth plate cells and confocal microscopy of growth plate sections using the mitochondrial probes Rh123 and DiOC6(3) provided unequivocal evidence that there was loss of mitochondrial membrane potential in hypertrophic cells. Furthermore, the intrinsic fluorescence of the flavoprotein lipoamide dehydrogenase complex of the electron transport chain revealed that the mitochondria were in an oxidized state. Finally, we assessed Bcl-2 expression in these cells. Although immunohistochemical and Western blot analysis showed that the chick cells contained a low level of the anti-apoptotic protein Bcl-2, reverse transcription-polymerase chain reaction (RT-PCR) analysis indicated that transcripts were present in chondrocytes. Based on these observations, we suggest that terminally differentiated chondrocytes undergo a maturation-dependent loss of mitochondrial function. In concert with the low expression of Bcl-2, they become sensitive to signals for programmed cell death. We hypothesize that Pi triggers apoptosis in these energy-compromised cells by promoting a mitochondrial membrane transition, thereby inducing the death process.

Adenosine Triphosphate↗

PubMed1999

Evidence for organochlorine contamination in tissues of salmonids in Lake Tahoe.

To evaluate the extent of organochlorine pollution in the Sierra Nevada ecosystem, residues of certain organochlorines in lake trout and Kokanee fish from Lake Tahoe, an alpine lake located between the Sierra Nevada Mountain Range and the Carson Range of California and Nevada, were analyzed. Multiresidue analysis in fish muscle revealed wet weight concentrations of total polychlorinated biphenyls (PCBs) in the range 18 to 430 ppb and of p,p'-DDE in the range 5 to 85 ppb in the two fish species studied. In one large lake trout sample (6.6 kg), which was studied in more detail as compared with others, residue levels of PCB (267 ppb), toxaphene (154 ppb), a chlordane mixture (78 ppb), and a DDT mixture (154 ppb) were found in muscle. Full spectra of specific PCB congeners and p,p'-DDE were obtained from fish fat tissues and their identities were confirmed using gas chromatography/mass spectrometry (GC-MS). The results of total PCB analysis indicated that residues found in fish consisted mostly of moderately (tri- to tetrachloro-) to highly (penta- to heptachloro-) chlorinated biphenyls. For all fish residues analyzed, the best match to PCB residue profiles was with Aroclor 1260 or 1262.

Adipose Tissue↗

PubMed1999

Biosynthesis of 20-hydroxyecdysone in Ajuga hairy roots: fate of 6alpha- and 6beta-hydrogens of lathosterol.

The fate of 6alpha- and 6beta-hydrogens of lathosterol during the transformation into 20-hydroxyecdysone was chased by feeding [3alpha,6beta-2H2]- and [3alpha,6alpha-2H2]-lathosterols to hairy roots of Ajuga reptans var. atropurpurea. The behavior of 6beta-hydrogen, which mostly migrated to the C-5 position of 20-hydroxyecdysone, was in agreement with that of C-6 hydrogen of cholesterol. The results strongly supported the view that cholesterol and lathosterol are first metabolized into 7-dehydrocholesterol, which is then converted into 20-hydroxyecdysone via 7-dehydrocholesterol 5alpha,6alpha-epoxide in the hairy roots.

Cholesterol↗

PubMed1999

Bryophyte 5S rDNA was inserted into 45S rDNA repeat units after the divergence from higher land plants.

The 5S ribosomal RNA genes (5S rDNA) are located independently from the 45S rDNA repeats containing 18S, 5.8S and 26S ribosomal RNA genes in higher eukaryotes. Southern blot and fluorescence in situ hybridization analyses demonstrated that the 5S rDNAs are encoded in the 45S rDNA repeat unit of a liverwort, Marchantia polymorpha, in contrast to higher plants. Sequencing analyses revealed that a single-repeat unit of the M. polymorpha nuclear rDNA, which is 16,103 bp in length, contained a 5S rDNA downstream of 18S, 5.8S and 26S rDNA. To our knowledge, this is the first report on co-localization of the 5S and 45S rDNAs in the rDNA repeat of land plants. Furthermore, we detected a 5S rDNA in the rDNA repeat of a moss, Funaria hygrometrica, by a homology search in a database. These findings suggest that there has been structural re-organization of the rDNAs after divergence of the bryophytes from the other plant species in the course of evolution.

Blotting, Southern↗

PubMed1999

Two mRNA species encoding calcium-dependent protein kinases are differentially expressed in sexual organs of Marchantia polymorpha through alternative splicing.

In plants, calcium-dependent calmodulin-independent protein kinases (CDPKs) are the predominant calcium-regulated protein kinases and their genes are encoded by a multigene family. A CDPK gene was cloned from a liverwort, Marchantia polymorpha, which showed a high level of sequence similarities to other higher plant CDPK genes. The liverwort CDPK gene consisted of 9 exons and 8 introns. The 6th and 7th exons (Exon 6A and Exon 6B) were almost identical except for 4-amino acid substitutions, both of which coded for EF-hands in the calcium-binding domain. RT-PCR analysis revealed that two species of mature mRNA containing either Exon 6A or Exon 6B were generated from a single CDPK gene by mutually exclusive alternative splicing. Both histidine-tagged fusion proteins derived from cDNAs containing either Exon 6A or Exon 6B exhibited calcium-dependent protein kinase activity in vitro. Preferential accumulation of the mature mRNA with Exon 6A detected in male sexual organ implies possible sexual control of the ratio between the two CDPK isozymes through alternative splicing. Functions and evolution of CDPKs are discussed based on the structure and expression of the liverwort CDPK gene.

Alternative Splicing↗

PubMed1999

CO(2)-responsive transcriptional regulation of CAH1 encoding carbonic anhydrase is mediated by enhancer and silencer regions in Chlamydomonas reinhardtii.

Chlamydomonas reinhardtii adapts to the stress of CO(2)-limiting conditions through the induction of a set of genes including CAH1, which encodes a periplasmic carbonic anhydrase. CAH1 is up-regulated under low-CO(2) conditions (air containing 0.04% [v/v] CO(2)) in the presence of light, whereas it is down-regulated under high-CO(2) conditions (5% [v/v] CO(2)) or in the dark. In an effort to identify cis-elements involved in the transcriptional regulation of CAH1, a series of 5'-nested deletions of the region upstream of CAH1 were fused to a promoterless arylsulfatase reporter gene (ARS). The upstream region from -651 to +41 relative to the transcription start site was sufficient to regulate the expression of ARS with kinetics similar to those of endogenous CAH1. Deletion of the region between -651 and -294 resulted in a significant decrease in the level of arylsulfatase activity expressed under low-CO(2) conditions. The 543-bp upstream region from -651 to -109, without any promoter elements, CAAT-box, or TATA-box, could confer CO(2) and light responsiveness on the beta(2)-tubulin minimal promoter. This 543-bp region was divided into two parts: a 358-bp silencer region from -651 to -294, which represses the minimal promoter activity under high-CO(2) conditions, and a 185-bp enhancer region from -293 to -109, which activates the promoter under low-CO(2) conditions in the presence of light.

5' Untranslated Regions↗

PubMed1999

Growth hormone advances spermatogenesis in premature rats treated with gonadotropin-releasing hormone agonist.

To clarify the effect of GH on the development of seminiferous tubules in premature male rats, we investigated whether GH accelerates spermatogenesis under the condition of gonadotropin deprivation. Male Wistar rats aged three weeks were divided into three groups and subjected to administration of either long-acting GnRH agonist (GnRHa) or a combination of GnRHa and rat GH, with normal saline solution as control. After the 4-week treatment, sperm density and motility in the right epididymis were measured and seminiferous tubules of right testes were histologically examined. Sperm density and motility were significantly higher in GnRHa+GH-treated rats than in GnRHa-treated rats. In histological examination, the numbers of germ cells in various stages were increased in GnRHa+GH-treated rats compared with GnRHa-treated rats, with the number of mature spermatid being noticeably higher in GnRHa+GH-treated rats. These results suggest that administration of GH decreases loss of germ cells at various stages of spermatogenesis under the condition of gonadotropin withdrawal.

Analysis of Variance↗

PubMed1999

[Breast cancer at the site of an implanted pacemaker].

We report here an 81-old-female patient who had a permanent pacemaker implanted in the right chest and who developed breast cancer near the site of the implanted generator. The cancer was diagnosed as stage I adenocarcinoma and radical mastectomy preserving pectoral muscles was indicated. During temporary pacing via the femoral approach, the pacemaker lead was transferred to the left subclavicular area crossing before the sternum and the generator was reimplanted in the left chest without use of lead extension kit. After reimplantation of the generator, radical mastectomy was performed. Clinical course was uneventful after the operation without infection or pacing failure. For the patient who needs surgical procedure in the site of implanted pacemaker generator, this technique of reimplantation is one of the useful choices.

Adenocarcinoma↗

PubMed1999

Inhibitory effects of azelastine and its metabolites on drug oxidation catalyzed by human cytochrome P-450 enzymes.

Azelastine, an antiallergy and antiasthmatic drug, has been reported to be metabolized mainly to desmethylazelastine and 6-hydroxyazelastine in mammals. In the present study, the inhibitory effects of azelastine and its two metabolites on human cytochrome P-450 (CYP) isoform-dependent reactions were investigated to predict the drug interactions of azelastine using microsomes from human B-lymphoblast cells expressing CYP. The specific activities for human CYP isoforms included: 7-ethoxyresorufin O-deethylation (CYP1A1), phenacetin O-deethylation (CYP1A2), coumarin 7-hydroxylation (CYP2A6), 7-benzyloxyresorufin O-dealkylation (CYP2B6), S-warfarin 7-hydroxylation (CYP2C9), S-mephenytoin 4'-hydroxylation (CYP2C19), bufuralol 1'-hydroxylation (CYP2D6), chlorzoxazone 6-hydroxylation (CYP2E1), and testosterone 6beta-hydroxylation (CYP3A4). In almost all the activities, desmethylazelastine exhibited stronger inhibition than azelastine and 6-hydroxyazelastine. Desmethylazelastine, but not azelastine and 6-hydroxyazelastine, uncompetitively inhibited CYP2B6 activity (Ki = 32.6 +/- 4.8 microM). Azelastine, desmethylazelastine, and 6-hydroxyazelastine competitively inhibited CYP2C9 activity (Ki = 13. 9 +/- 1.8, 15.0 +/- 3.1, and 17.0 +/- 4.1 microM, respectively), CYP2C19 activity (Ki = 21.9 +/- 2.2, 7.3 +/- 1.6, and 9.3 +/- 1.6 microM, respectively), and CYP2D6 activity (Ki = 1.2 +/- 0.1, 1.5 +/- 0.2, and 3.0 +/- 0.5 microM, respectively). Azelastine and desmethylazelastine competitively inhibited CYP3A4 activity (Ki = 23. 7 +/- 4.6 and 13.2 +/- 2.3 microM). 6-Hydroxyazelastine interfered with the determination of testosterone 6beta-hydroxylation by HPLC. CYP1A2, CYP2A6, and CYP2E1 activities were not significantly inhibited by azelastine and the two metabolites. Among the human CYPs tested, the inhibitory effects of azelastine and its two metabolites were the most potent on human CYP2D6. In consideration of the Ki values and the concentration of azelastine and desmethylazelastine in human livers after chronic oral administration of azelastine, the possibility of in vivo drug interaction of azelastine and other drugs that are mainly metabolized by CYP2D6 was suggested although it might not cause critical side effects. The inhibition of CYP2C9, CYP2C19, and CYP3A4 activity by azelastine and its two metabolites might be clinically insignificant.

Anti-Allergic Agents↗