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Biomedical subjects

H Esumi

Publications and source records attributed to H Esumi.

At least 91 records · Page 5Linked to original sources
PubMed1995

Marked increase in urinary excretion of nitrate and N-nitrosothioproline in the osteogenic disordered syndrome rats, lacking ascorbic acid biosynthesis, by administration of lipopolysaccharide and thioproline.

Urinary excretions of nitrate and N-nitrosothiazolidine-4-carboxylic acid (N-nitrosothioproline; NTPRO) were determined in rats with osteogenic disordered syndrome (ODS, od/od), lacking L-ascorbic acid (ASC) biosynthesis, after i.p. administration of Escherichia coli lipopolysaccharide (LPS, 1 mg/kg) followed by thiazolidine-4-carboxylic acid (thioproline, 20 mg/rat). L-Ascorbic acid-sufficient ODS rats showed the excretion of nitrate and NTPRO at the levels of 20.3 +/- 7.9 mumol/24h and 369 +/- 111 pmol/24 h respectively, whereas the levels of nitrate and NTPRO in ASC-deficient (scorbutic) rats increased to 54.7 +/- 5.6 mumol/24 h (P < 0.01) and 796 +/- 367 pmol/24 h (P < 0.05) respectively. Administration of L-arginine further increased urinary excretion of nitrate and NTPRO while D-arginine showed no effect. NG-Monomethyl-L-arginine, a specific inhibitor of nitric oxide synthase (NOS), strongly inhibited endogenous formation of both nitrate and NTPRO. These results indicate that increased excretion of NTPRO in ODS rats stimulated by LPS involves induction of NOS leading to an increase in endogenous formation of reactive nitrogen oxides such as N2O3, a potent nitrosating agent at physiological pH conditions. Increased NOS activities in the plasma and various tissues of ODS rats were observed 5 h after treatment with LPS. The possibility of extragastric N-nitroso compound formation in inflammation sites is discussed.

Animals↗
PubMed1995

Implication of nitric oxide synthase in carcinogenesis: analysis of the human inducible nitric oxide synthase gene.

Nitric oxide (NO) is a newly identified, multifunctional biological mediator. However, it also has deleterious effects on biological materials. For instance, nucleic acids, proteins, and some prosthetic groups of enzymes can be modified by NO or its reaction products with other reactive oxygen species. Endogenous nitrosamine formation through the reaction of NO or its oxidized products with amines might be involved in carcinogenesis. These deleterious effects of NO are often associated with inflammatory processes both in experimental animals and human. We analyzed the molecular mechanism of control of expression of the inducible nitric oxide synthase (NOS) gene in mouse cells by cloning its putative promoter region. This promoter responded to various cytokines and endotoxin similarly to the endogenous NOS gene in mouse cells. No appreciable induction of NOS was observed in human peripheral blood cells, but induction was detected in a human glioblastoma cell line A-172. Therefore, the human inducible NOS cDNA was cloned from A-172 cells and its cDNA-deduced amino acid sequence found to have about 80% similarity to those of both mouse and rat inducible NOSs. The effects of various cytokines on the induction of the gene were somewhat different from those observed in mouse cells, but the mouse promoter responded to these cytokines similarly to the endogenous NOS gene in human cells, indicating functional similarity of cis-elements of the genes encoding both human and mouse inducible NOS. Structural analysis of the human inducible NOS gene by Southern blot analysis revealed putative genetic restriction fragment length polymorphism in intron 5.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Sampling method as a key factor in identifying K-ras oncogene mutations in preneoplastic colorectal lesions.

The development of sensitive polymerase chain reaction (PCR)-based techniques in recent years has enabled us to verify the possible presence of mutated oncogenes and tumor suppressor genes in stages preceding tumor formation. Early detection of mutants serves as a powerful tool for detecting exposure to carcinogens and can assist in diagnosis. In studies performed in the past few years, we have identified mutant ras alleles in preneoplastic samples of patients with and without colorectal cancer. Our studies have shown (i) that mutant ras alleles are present at low incidence in normal appearing tissues of patients with colorectal cancer. Such mutations are also found in colonic effluents of patients at risk for developing this tumor type; and (ii) that the method of sampling is critical to ensure true representation of the entire colonic mucosa. The implications of identifying ras mutations in patients without evidence for neoplasma are discussed.

Biomarkers, Tumor↗
PubMed1994

Nitric oxide synthase-immunoreactive nerve fibers in the nasal mucosa of the rat.

An immunohistochemical study was performed to detect the localization of nitric oxide synthase (NOS) in the rat nasal mucosa by light and electron microscopy. NOS-immunoreactive nerve fibers were observed around blood vessels and seromucous glands. They were found in the subepithelial layer and even within the epithelium. But no NOS-immunoreactivity was found in the olfactory neuroepithelium. Electron microscopy showed that NOS-immunoreactive nerve profiles were in close contact with the cytolemma of respiratory epithelial cells and acinar cells of seromucous glands. NOS-immunoreactive axon varicosities were located at a considerable distance from the smooth muscle of arterioles and small veins as well as the endothelial cells of venules and capillaries. We confirmed that NOS-containing nerves innervated the epithelium, blood vessels and seromucous glands of the nasal mucosa. These findings, collectively, suggested the possibility that nitric oxide participated in the sensory function of the epithelium, the secretory activities of the nasal gland, and the regulation of vascular tone and vascular permeability in the nasal mucosa.

Amino Acid Oxidoreductases↗
PubMed1994

Effect of docosahexaenoic acid on azoxymethane-induced colon carcinogenesis in rats.

The effect of intragastric gavage administration of docosahexaenoic acid (DHA) on azoxymethane (AOM)-induced colon carcinogenesis in rats was studied. Male F344 rats were treated s.c. with 15 mg/kg of AOM once a week for 2 weeks and were given either 0.7 ml of DHA or water intragastrically twice a week starting the day before the first carcinogen treatment. The number of crypt multiplicity (number of crypts/focus) of aberrant crypt foci (ACF) in the colon were measured after 4, 12, and 36 weeks. The numbers and average crypt multiplicities of ACF induced by AOM were significantly lower after 12 and 36 weeks in animals given DHA. DHA also reduced the incidence of spontaneous ACF in animals without carcinogen treatment. Colorectal tumor incidence and number of tumors per rat after 36 weeks were slightly, but not significantly, lower in the DHA-treated group. These results suggest that DHA slightly suppresses colon carcinogenesis, and a possibility that warrants further study.

Animals↗
PubMed1994

Cell type specific patterns of mRNA splicing in hepatoma cells transfected with the mutated albumin minigene of Nagase analbuminemic rats.

We constructed an SV40-derived expression vector containing a mutated albumin minigene of Nagase analbuminemic rats (NAR), and introduced it into cultured cells. Transient expression of the minigene mRNA was determined by RT-PCR. Three kinds of aberrant mRNAs were expressed by the non-hepatic cells COS-1, and the undifferentiated human hepatoma cells HLE, transfected with the minigene. Their predominant mRNA lacked exon H (delta H), while mRNAs lacking exons H and I, or exons G and H were less abundant. This pattern of the mRNAs was similar to that of albumin mRNAs in the liver of old NAR. In contrast, a differentiated type of human hepatoma cell line, HepG2, expressed only delta H mRNA, like young NAR. These findings indicate that the expression system of the mutated minigene in cultured hepatoma cells is useful for understanding two-exon-skipping of albumin pre-mRNA of NAR.

Alternative Splicing↗
PubMed1994

Co-existence of PACAP and nitric oxide synthase in the rat hypothalamus.

The possible co-existence of pituitary adenylate cyclase-activating polypeptide (PACAP)-38 and nitric oxide synthase (NOS) in the rat hypothalamus was examined by a combination of PACAP-immunocytochemistry and NADPH-diaphorase histochemistry. Virtually all PACAP-38-immunoreactive neurones in the paraventricular and supraoptic nuclei exhibited NADPH-diaphorase activity. Since NADPH-diaphorase activity was identical to NOS-immunoreactivity in the magnocellular neurosecretory neurones, this finding indicates that the PACAP neurones synthesize NO.

Amino Acid Oxidoreductases↗
PubMed1994

Infrequent K-ras activation in superficial-type (flat) colorectal adenomas and adenocarcinomas.

Clinicopathological evidence is accumulating that a superficial-type (flat) colorectal tumor is a distinct neoplastic entity. To clarify the genetic characteristics of this tumor, we investigated the K-ras gene mutations and morphological features of 43 tumors of this type. A mutation of the K-ras codon 12 was detected in only 5 (16%) of 31 adenomas and 2 (17%) of 12 adenocarcinomas. The presence or absence of this mutation was not correlated with the tumor size or stage or with histopathological findings. None of these tumors had a mutation in codon 13 or exon 2, including codon 61. This low incidence of K-ras mutations (16%) suggests that superficial-type colorectal tumors are etiologically distinct from ordinary colorectal polypoid tumors and that there may be an alternative pathway of colorectal tumorigenesis.

Adenocarcinoma↗
PubMed1994

Dual mechanism for the control of inducible-type NO synthase gene expression in macrophages during activation by interferon-gamma and bacterial lipopolysaccharide. Transcriptional and post-transcriptional regulation.

Production of nitric oxide (NO) by macrophages is enhanced upon activation by bacterial endotoxins and cytokines mainly via an increase of the intracellular content of the inducible isoform of nitric oxide synthase (i-NOS). We have studied in detail the effect of several modulators of macrophage activity on steady state levels of i-NOS mRNA in the mouse macrophage-like cell line RAW 264.7. Bacterial lipopolysaccharide (LPS) and interferon-gamma (IFN-gamma) were found to be effective inducers of i-NOS mRNA, in accordance with their known ability to stimulate both i-NOS activity and NO production in macrophages from different sources, while TNF-alpha, IL-1, or IL-6 was ineffective in this regard. Accumulation of i-NOS mRNA in response to either LPS or IFN-gamma stimulation was accompanied by increased i-NOS gene transcription, as detected both by using a nuclear "run-on" transcription assay and by transient transfection of the cloned gene promoter in RAW 264.7 cells. Co-stimulation of the cells with both inducers resulted in higher steady state levels of i-NOS mRNA in the absence, however, of a corresponding potentiation of the rate of gene transcription. This was due primarily to a considerable effect of LPS on i-NOS mRNA stability, with prolongation of its half-life from 1-1.5 h, in the presence of IFN-gamma alone, to 4-6 h in the presence of both LPS and IFN-gamma.

Amino Acid Oxidoreductases↗
PubMed1994

Liver fluke infection and cholangiocarcinoma: model of endogenous nitric oxide and extragastric nitrosation in human carcinogenesis.

Cancers arising during bacterial, viral and parasitic infection provide useful models to investigate the link between inflammation and carcinogenesis. Because the inflammatory agent is known, relationships between immune responses, the production of DNA-damaging agents, such as nitric oxide, oxygen radicles and N-nitroso compounds, and cancer risk can be explored. This paper first describes the close relationship between infection with the liver fluke, Opisthorchis viverrini, and cholangiocarcinoma in humans. Data are then presented which demonstrate an elevation in levels of salivary nitrite and urinary and plasma nitrate among men with moderate and heavy liver fluke infections compared to uninfected controls which was absent 4 months after the parasites were cleared with praziquantel. Because of the strict control over subject selection and dietary intake plus the absence of the increase following treatment, we conclude that the higher levels of nitrate and nitrite reflect endogenous generation of nitric oxide resulting from liver fluke infection. Excess nitric oxide generation in the inflamed tissue is likely to lead directly to the formation of N-nitroso compounds mediated by activated macrophages. Further work will attempt to demonstrate a link between this increase and both parasite-specific immune responses and the risk of cancer.

Adult↗
PubMed1994

Cloning and functional expression of poly(ADP-ribose) polymerase cDNA from Sarcophaga peregrina.

A cDNA spanning the entire coding region for poly(ADP-ribose) polymerase (PARP) of Sarcophaga peregrina was isolated and the nucleotide sequence was determined. The longest open reading frame encodes a polypeptide of 996 amino acid residues with a molecular mass of 113,033 Da. The similarities to the human PARP in amino acid sequence were relatively low in the DNA-binding and auto-modification domains, but very high in the C-terminal catalytic domain: identity of amino acids is 34% in the N-terminal DNA-binding domain (residues 1-369), 27% in the auto-modification domain (residues 370-507), and 56% in the C-terminal NAD-binding domain (residues 508-996). Two zinc-fingers (C-X2-C-X28-H-X2-C and C-X2-C-X31-H-X2-C)2 and a basic region in the N-terminal DNA-binding domain recognized in other PARP are conserved. Downstream of the basic region, another cysteine-rich motif (C-X2-C-X13-C-X9-C), a putative zinc-finger, was found to be well conserved in the PARP of Sarcophaga, Drosophila and human. A leucine-zipper motif (L-X6-L-X6-L-X6-L) which was found in the auto-modification domain of Drosophila PARP, is disrupted in the Sarcophaga enzyme: the second leucine is replaced by proline, and the third leucine by valine. Full-length cDNA for Sarcophaga PARP was cloned into an expression plasmid and expressed in Escherichia coli. A lysate of E. coli cells containing expressed protein reacted with antibody against Sarcophaga PARP, and PARP activity was detected. Thus, we conclude that isolated cDNA encodes a functional Sarcophaga PARP cDNA.

Amino Acid Sequence↗
PubMed1994

Enhancement of inducible-type NO synthase gene transcription by protein synthesis inhibitors. Activation of an intracellular signal transduction pathway by low concentrations of cycloheximide.

Treatment of mouse macrophage-like RAW 264.7 cells with certain protein synthesis inhibitors is followed by accumulation of the mRNA for the inducible isoform of nitric oxide synthase (i-NOS). The activity of these compounds on the i-NOS gene in RAW 264.7 cells was analyzed here in detail. Results show that both cycloheximide and anisomycin can efficiently induce i-NOS mRNA, even when used at concentrations so low (0.25 microgram/ml) to have only negligible effects on protein synthesis; puromycin, on the other hand, shows only a limited effect on i-NOS mRNA expression, detectable only when cells are treated with higher concentrations of inhibitor (25 micrograms/ml). In RAW 264.7 cells, low concentrations of cycloheximide trigger an immediate-early gene response, as indicated by induction of c-fos and JE mRNAs, and can efficiently activate transcription of transiently transfected recombinant reporter genes including either the i-NOS or the c-fos gene promoters.

Amino Acid Oxidoreductases↗
PubMed1994

Non-covalent interaction between poly(ADP-ribose) and cellular proteins: an application of a poly(ADP-ribose)-western blotting method to detect poly(ADP-ribose) binding on protein-blotted filter.

We describe a sensitive method for the detection of interactions between poly(ADP-ribose) and proteins. Proteins were blotted onto nitrocellulose filters and incubated with 32P-labeled poly(ADP-ribose). Purified core histones and poly(ADP-ribose) polymerase were found to bind poly(ADP-ribose) polymer. Blots of HeLa cell protein extracts revealed a 48 kDa protein and several others of smaller than 35 kDa likewise bound the polymers even at high salt concentrations. Those proteins, along with a 69 kDa protein, also showed resistance to competitor DNA. Polymer binding of aforesaid HeLa extract proteins was restricted to polymers above 20 residues in length. Thus poly(ADP-ribose)-protein affinities were polymer-length dependent.

Base Sequence↗
PubMed1994

Expression of two types of nitric oxide synthase mRNA in human neuroblastoma cell lines.

Expression of nitric oxide synthase (NOS) was studied in nine human neuroblastoma and two human glioblastoma cell lines. Neuronal NOS (n-NOS) mRNA of approximately 10 kb was detected in four of the nine neuroblastoma cell lines by northern blot analysis using human n-NOS cDNA as a probe. Expression of the n-NOS mRNA was also detected in another neuroblastoma cell line in a subsequent reverse transcriptase polymerase chain reaction (RT-PCR) study, but no n-NOS mRNA expression was observed in the other four neuroblastoma cell lines or in the glioblastoma cell lines. The level of NOS activity correlated well with that of n-NOS mRNA expression in neuroblastoma cell lines expressing n-NOS mRNA. Western blot analysis showed that the n-NOS expressed in neuroblastoma cells was a 160-kDa protein reacted with anti-n-NOS antibody. By using the RT-PCR method, a short n-NOS (n-NOS-2) mRNA with a 315-bp inframe deletion from the entire n-NOS (n-NOS-1) mRNA was detected in the human neuroblastoma cells. The structural diversity of human n-NOS mRNA was demonstrated for the first time.

Amino Acid Oxidoreductases↗
PubMed1994

Cloning and functional expression of human inducible nitric oxide synthase (NOS) cDNA from a glioblastoma cell line A-172.

Nitric oxide (NO) is a messenger molecule with diverse functions throughout the body. The inducible type of nitric oxide synthase (NOS) is considered to be a key molecule in the immune responses to bacteria, parasites, and tumors, and its gene expression is regulated by cytokines. We isolated 3 overlapping partial inducible NOS cDNA clones from a human glioblastoma cell line A-172 induced by IL-1, TNF-alpha, and IFN-gamma. The 3,963-bp human glioblastoma inducible NOS cDNA contained the longest open reading frame of 3,459 bp, which encoded a polypeptide of 1,153 amino acids with a calculated molecular mass of 131 kDa. This human inducible NOS possessed consensus recognition sites for the cofactors FMN, FAD, and NADPH and calmodulin recognition sites, and displayed 48.1% sequence identity with the endothelial type, 43.1% with the neuronal type, and 99.3% with the inducible type from hepatocytes, and 99.9% with the inducible type from chondrocytes and adenocarcinoma. An expression plasmid consisting of pSG5 expression vector and cDNA containing the entire putative coding sequence was constructed and transfected into COS-1 cells. COS-1 cells showed nitric oxide synthase activity together with a 130 kDa immunoreactive band on Western blot analysis.

Amino Acid Oxidoreductases↗
PubMed1994

Increased cell proliferation of azoxymethane-induced aberrant crypt foci of rat colon.

Aberrant crypt foci (ACF) were induced in the colon of F344 rats by s.c. injection of azoxymethane (AOM) twice in a three day-interval and examined after 4 and 12 weeks. The number and crypt multiplicity of ACF in each section of rat colon increased during this period. Histologically, aberrant crypts consisted of proliferating atypical epithelial cells. Cell proliferation of ACF consisting of 4 aberrant crypts [ACF(4)] and 2 aberrant crypts [ACF(2)], and normal crypts in the colon of rats treated with AOM [normal crypts/AOM(+)] or saline [normal crypts/AOM(-)] was investigated by measurement of the mitotic index, proliferating cell nuclear antigen-labeling index (PCNA-LI), and 5-bromo-2'-deoxyuridine-labeling index (BrdU-LI). All three parameters of the cell proliferative activity of ACF(4) were higher than those of normal crypts/AOM(+) and normal crypts/AOM(-). The PCNA-LI and BrdU-LI in ACF(2) were the same as those in ACF(4). These findings suggest that ACF have increased cell proliferative activity. The correlation of these three parameters confirmed that the PCNA-LI is also a useful parameter for evaluating cell proliferative activity in ACF. The presence of many cells stained by PCNA in the upper portion of ACF suggested that ACF have more G1 phase cells, which readily respond to mitogenic stimulation, than G0 phase cells, which are predominant in normal crypts.

Animals↗
PubMed1994

Suppression of G1 arrest and enhancement of G2 arrest by inhibitors of poly(ADP-ribose) polymerase: possible involvement of poly(ADP-ribosyl)ation in cell cycle arrest following gamma-irradiation.

Low-dose gamma-irradiation of mouse embryonic fibroblast C3D2F1 3T3-a cells caused G1 arrest along with G2 arrest and inhibition of replicative DNA synthesis. When the cells were cultured in the presence of inhibitors of poly(ADP-ribose) polymerase [EC 2.4.2.30], such as 3-aminobenzamide, benzamide and luminol, G1 arrest of C3D2F1 3T3-a cells was suppressed and enhancement of G2 arrest was observed. In contrast, 3-aminobenzoic acid, a non-inhibitory analog of 3-aminobenzamide, did not suppress G1 arrest following gamma-irradiation. These results suggest that the poly(ADP-ribosyl)ation reaction is critical for the pathway of G1 arrest and is also involved in the pathway of G2 arrest.

Animals↗