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Biomedical subjects

N Miki

Publications and source records attributed to N Miki.

At least 91 records · Page 5Linked to original sources
PubMed1994

Molecular cloning of cDNA encoding the precursor for hamster hypothalamic growth hormone-releasing factor.

The structure of rat and mouse growth hormone-releasing factor (GRF) peptide and precursor shows considerable divergence from that of the human counterpart and also within rodents themselves. To study such structural divergence in another rodent, we cloned a cDNA encoding the GRF precursor from golden hamster. The hamster GRF (haGRF) cDNA clone had an open-reading frame that predicts a haGRF precursor protein with 107 amino acids. The haGRF precursor bore greater overall homology (82%) to the human than the same rodent homologue (58-64%) and contained two processing sites identical to the human sequence that would generate mature haGRF peptide. Furthermore, the haGRF peptide, like human but unlike rat or mouse GRF, consisted of 44 amino acids and also had greater homology to the human (89%) than the rodent sequence (64-75%), conserving a Tyr residue at the N-terminus and an amidated Leu residue at the C-terminus. Thus, both haGRF precursor and peptide are structurally more related to those of human than of other rodents, suggesting that rodent GRF precursor diverged from the human sequence at differential rates within the species.

Animals↗
PubMed1994

[Involvement of gene expression in drug tolerance and dependence].

The development of drug tolerance and dependence are thought to be associated with gene expression. Our studies showed that the binding activity of nuclear factors to several DNA sequences is altered by long-term treatment with methamphetamine, cocaine and morphine: 1) the binding activity of AP-1 increased markedly in the mouse brain after administration of methamphetamine and cocaine, 2) CRE-binding activity was decreased by chronic morphine treatment in the amygdala complex, cerebral cortex and hypothalamus of the mouse brain, and 3) the binding activity of single-stranded CRE binding proteins was decreased by chronic morphine treatment in the mouse cerebellum. These data suggest that the changes of DNA binding proteins can be involved in the development of drug tolerance and dependence.

Amphetamine↗
PubMed1993

Regulation of class II MHC gene expression by the inducible anti-sense RNA in transgenic mice.

We have established a gene regulatory system in mice by the inducible anti-sense RNA. We have generated transgenic mice carrying the anti-sense DNA composed of the class II MHC gene under the control of the human metallothionein IIa gene promoter. The detectable amount of anti-sense RNA was constitutively produced in spleen and bone marrow from transgenic mice and the amount in spleen was increased about fivefold by the stimulation of mice with heavy metal ions. We have previously reported that the reduction of class II MHC molecules on early B lineage cells by the anti-sense RNA results in delay of their development in the bone marrow culture. The early B cell development was slightly delayed in the culture from the transgenic mice. This delay was augmented in the culture by the addition of heavy metal ions in proportion to its concentration. These results suggest that the inducible anti-sense RNA reduces the expression of class II MHC molecules on B lineage cells.

Animals↗
PubMed1993

Purification and characterization of three MEKA-like proteins in liver: association of a 94 kDa protein with beta gamma subunits of G-proteins.

Retinal 32 kDa MEKA protein (rMEKA) exists in the photoreceptor cells and forms a complex with beta gamma subunit of transducin. Bovine liver contained three MEKA-like proteins (94 kDa, 35 kDa-a, 35 kDa-b) which reacted with a rMEKA antibody. Each protein was purified as a single band on a SDS-PAGE and used for a reconstitution experiment with alpha and beta gamma subunits of cerebral G-proteins (Go/i). The 94 kDa protein inhibited GTP-binding ability of G alpha by forming a complex with beta gamma subunit.

Animals↗
PubMed1993

Marek's disease virus protein kinase gene identified within the short unique region of the viral genome is not essential for viral replication in cell culture and vaccine-induced immunity in chickens.

The open reading frame (ORF) of 1206 bp within the short unique region (Us) of Marek's disease virus type 1 (MDV1) shows significant homology with the herpes simplex virus type 1 US3 gene encoding protein kinase (PK). The lacZ gene of Escherichia coli was inserted within the ORF, designated MDV1-US3, of MDV1 K544 strain DNA by homologous recombination. The plaque-purified recombinant MDV1 stably expressed the beta-galactosidase encoded by the inserted lacZ gene in infected cells and replicated well as the parental K544 strain. Antibodies against both MDV1 antigen and beta-galactosidase were detected in the sera of chickens immunized with recombinant MDV1. Chickens vaccinated with the recombinant MDV1 were protected from challenge with virulent MDV1. The MDV1 US3 gene expressed by a baculovirus vector encoded a 44-kDa protein. Mouse antisera against the 44-kDa protein reacted with two proteins of 44 and 45 kDa in extracts of cells infected with MDV1 but not with MDV types 2 or 3. The PK activity was detected in immune complexes of the anti-44-kDa sera with extracts of cells infected with MDV1 but not with the recombinant MDV1. Thus, PK encoded from the MDV1-US3 is not essential for virus replication in cell culture and vaccine-induced immunity.

Amino Acid Sequence↗
PubMed1993

Extracellular matrix proteins with neurite promoting activity and their receptors.

Characteristic features of the nervous system converge into network formation during the development. The neurons recognize precisely their target cells and form synapses, and these steps are complex, but well organized spatially and temporally. The neurite promotion from the neurons is one of the most important events for synapse formation. It is well known that extracellular matrix proteins such as laminin and their receptors, and cell adhesion molecules such as NCAM participate in cell migration and synaptic formation. We have isolated a neurite outgrowth factor (NOF) which promotes neurite outgrowth from various neurons and belongs to laminin family, and also its receptor which is identified to be an immunoglobulin superfamily protein by cDNA cloning. This ligand-receptor system is a unique example that a receptor with immunoglobulin-like structure interacts with an extracellular matrix protein.

Animals↗
PubMed1993

B cell development is perturbed in bone marrow from c-fos/v-jun doubly transgenic mice.

c-fos and c-jun gene products form a heterodimeric complex (AP-1) that regulates target gene expression by binding to a specific DNA sequence motif. In order to study a role of AP-1 (Fos/Jun) in growth and differentiation of immature B lineage cells, we have established and mated two independent transgenic mice carrying the mouse c-fos gene or the viral v-jun gene fused to the H-2K promoter. IL-7 dependent bone marrow cell culture from doubly transgenic (H2-fos/jun) mice demonstrated severe delay of early B cell development. Proliferation of pre-B cells in the fresh bone marrow from H2-fos/jun mice to IL-7 stimulation was very low. These results suggest that the deregulated production of AP-1 perturbs IL-7 mediated proliferation and differentiation of immature B cells.

Animals↗
PubMed1992

Identification of NGF-response element in the rat neuropeptide Y gene and induction of the binding proteins.

Gene expression of the rat neuropeptide Y (NPY) increases by 100 times, as the PC12 cells differentiate into sympathetic neuron-like cells with NGF treatment and this increase is partly due to transcriptional activation of the NPY gene (Sabol and Higuchi, Mol. Endocrinol. 4, 384, 1990). To identify the NGF-response element, a transient expression assay was carried out by using the CAT reporter genes containing various lengths of the 5' upstream region of the NPY gene in the PC12 cells. The 48-base element (-80/-33 upstream of the Cap site) was identified as a NGF-response element (NGFRE). Gel shift assay indicated the existence of at least two DNA-binding proteins to NGFRE. The binding activity of the protein(s) (NDF1) to the upper region (-80/-63) was increased by 3-fold with NGF treatment for 24 h. These findings suggest that these nuclear proteins are involved in the enhanced transcription of the NPY gene by NGF.

Animals↗
PubMed1992

In situ DNA-protein binding: a novel method for detecting DNA-binding activity of transcription factor in brain.

A novel method, in situ DNA-protein binding (in situ DPB), was developed to detect the distribution and DNA-binding activity of AP-1 and Sp1 binding proteins in situ. The regional distribution of AP-1 binding protein in mouse brain was different from that of Sp1. Antibody against the DNA-binding domain of Jun protein markedly reduced the AP-1 but not the Sp1 binding activity. The binding activity of AP-1 probe increased markedly in the brain after administration of methamphetamine. These results suggest that the in situ DPB is convenient and sensitive for detecting the distribution and the DNA-binding activity of transcription factors in situ.

Animals↗
PubMed1992

Role of I-A molecules in early stages of B cell maturation.

The role of the Ia molecule in the early phase of B cell development remains controversial. In contrast to previous studies, we have detected minute amounts of Ia (I-A) molecule on early B lineage (B220+IgM-) cells from normal bone marrow, using ELISA. The presence of the I-A molecule even on pro-B cells was deduced from experiments in which a monoclonal anti-I-A antibody completely blocked the generation of pre-B cells from B progenitor (B220-) cells in stromal cell-dependent B cell culture. Inasmuch as this antibody did not inhibit the maturation of pre-B cells to IgM+ B cells in culture, the I-A molecule on early B lineage cells probably plays a role in their maturation. We also examined the role of the I-A molecule in early B cell development, using transgenic mice harboring the antisense DNA to I-A beta-chain gene. The amount of I-A molecule on splenic B cells from the young transgenic mice decreased in the presence of abundant amounts of the antisense RNA. B cell development was perturbed in spleen from the transgenic mice. Stromal cell-dependent B cell cultures from these mice clearly showed that the maturation of B lineage cells was delayed at a very early stage of development (B220- to B220+). We propose that the I-A molecule on early B lineage cells may play an essential role in their maturation.

Animals↗
PubMed1992

Inhibition of class II MHC gene expression by anti-sense RNA in transgenic mice.

We have established transgenic mice carrying the anti-sense DNA to the gene encoding beta chain of the class II major histocompatibility complex (I-A) molecule. The amount of I-A molecule on splenic B lymphocytes from the mice was reduced in the presence of a large amount of the exogenous anti-sense RNA. The amount of I-A beta chain RNA was selectively reduced and inversely correlated with the amount of anti-sense RNA in the spleens. These results suggest that the I-A beta chain RNA is rapidly degraded by duplex formation with the anti-sense RNA in splenic B cells from the transgenic mice.

Animals↗
PubMed1992

Involvement of a receptor for neurite outgrowth factor (NOFR) in cerebellar neurogenesis.

A receptor for neurite outgrowth factor (82 kDa membrane protein, NOFR) was detected in the developing chick cerebellum by immuno- and ligand blots. In immunohistochemical study, NOFR was maximally expressed in the external granular layer of cerebellum at embryonic day 10-12 and gradually decreased until embryonic day 18. Neurite outgrowth and cell migration induced by NOF from cerebellar explants were completely suppressed by the addition of anti-NOFR IgG. These results suggest that NOFR plays an important role in the cerebellar neurogenesis.

Animals↗
PubMed1992

Topography of opsin within disk and plasma membranes revealed by a rapid-freeze deep-etch technique.

Rod outer segments in fresh rat retinas were examined by a rapid-freeze, deep-etch technique to explore how membrane proteins are organized at the macromolecular level. Cross-fractures revealed that intradiscal membranes are adherent to each other except at the rim. When an isolated fresh retina was incubated in a hypotonic solution for a few minutes, the interdiscal space was expanded and the cytoplasmic surface of the disk membrane was found to be covered with protrusions except at the rim. A few particles were scattered among the protrusions and were attached to the cytoplasmic surface. Since the distribution density of the cytoplasmic surface protrusions was similar to that of the P-face particles, which are known to reflect opsins, the protrusions were considered to be portions of opsins extending into the cytoplasm. The intradiscal surfaces in chemically-fixed retinas were rather smooth and were labelled with anti-opsin antibodies and wheat germ agglutinin. The true surfaces of the plasma membrane were found to be similar in fine structure to those of the disk. A model of the macromolecular organization of rod outer segments is proposed on the basis of these observations. The model shows apposed opsins within a disk membrane adhering to one another except at the rim. These opsins, as well as those in the plasma membrane, are minimally exposed to the extracellular surface, but protrude deeply into the cytoplasm.

Animals↗
PubMed1992

Sequence determination and genetic content of an 8.9-kb restriction fragment in the short unique region and the internal inverted repeat of Marek's disease virus type 1 DNA.

The DNA sequence (8.9 kb) covering about 70% of the short unique region (Us) and part of the short inverted repeat of the Marek's disease virus type 1 GA strain was determined. Computer analysis of the sequence showed the presence of nine potential open reading frames (ORFs), consisting of more than 300 nucleotides in the Us region. Of these ORFs, four were found to be homologous to US10 (minor virion protein), US3 (protein kinase), US2, and US6 (gD) in the Us region of alpha-herpesvirus herpes simplex virus type 1. The protein kinase homologue is especially well conserved in alpha-herpesviruses. No counterpart of the nine MDV1 ORFs was found in the beta-herpes virus human cytomegalovirus and gamma-herpesvirus Epstein-Barr virus, suggesting that MDV1 is more similar to the alpha-herpesviruses. The junction of the Us region and the short inverted repeat was also determined by comparison between the sequences of the DNA fragments, including the terminal and internal repeats. Northern blot analysis showed that the Us region within the 8.9 kb sequence was transcriptionally active in MDV1-infected cells.

Amino Acid Sequence↗
PubMed1992

Identification of glucocorticoid responsive elements (GREs) at far upstream of rat NPY gene.

The location of three glucocorticoid responsive elements (GREs) in rat neuropeptide Y (NPY) gene was determined by chloramphenicol acetyltransferase (CAT) assay and nucleotide sequencing. We have reported that mRNA content of rat prepro-NPY is increased by 1.7-fold in NG108-15 cells by 1 microM dexamethasone, suggesting the presence of GRE in the gene. To identify the element, the 5'-flanking DNA of 3.3 kilobases (kb) was isolated from rat NPY gene. When chimeric chloramphenicol CAT plasmids containing various deletions of the NPY upstream sequence were transfected into NG108-15 cells, the region between -2.9 and -2.1 kb relative to the cap site was found to potentiate the transcription of CAT gene in the presence of 1 microM dexamethasone. The nucleotide sequencing of this region revealed three GRE consensus sequences at -2.5, -2.2 and -2.1 kb. The results indicate that these elements present in the far upstream region of the NPY gene confer induction by glucocorticoids.

Animals↗
PubMed1992

Diagnostic validity of fecal occult blood tests for detecting gastroenterological cancers.

In order to estimate the diagnostic validity of chemical fecal occult blood tests, i.e. orthotolidine (Shionogi A) and guajac (Shionogi B) slides for detecting cancers of the esophagus, stomach and colorectum, the authors followed up all the examinees (n = 3,449) of comprehensive medical check-ups at the Center for Adult Diseases, Osaka, by means of record linkage to the Osaka Cancer Registry's files. Then, diagnostic validity was calculated based on the results of two years' follow-up. Sensitivity for the respective cancers was 20.0%, 11.8% and 62.5% for Shionogi A, and 20.0%, 5.9% and 43.8% for Shionogi B slides. Likelihood ratio for the respective cancers was 1.4, 0.8 and 4.5 for Shionogi A, and 3.3, 1.0 and 7.5 for Shionogi B. Specificity was analogous among the three cancer sites, being 86% for Shionogi A and 94% for Shionogi B. These results suggest that the diagnostic validity of chemical occult blood tests for detecting cancers of the esophagus and the stomach is very poor, and therefore imply that close examinations of these sites for screening positives is unnecessary in mass screenings for colorectal cancer.

Adult↗
PubMed1992

Measurement of sound-pressure distribution in replicas of the oral cavity.

The spatial distributions of sound pressure in artificial oral cavities were measured to examine the characteristics of wave propagation in the vocal tract. The measurement was performed with plaster replicas of the oral cavity, and pure tones were used as the driving signals to obtain both amplitude and phase distributions at varied frequencies. Plane-wave propagation, which has been widely assumed for speech production models, was examined from the measured spatial distributions of sound pressure. Trajectories of media particles and vectorial maps of acoustic intensity, which can be computed from the measured pressure distributions, were also presented to visualize the acoustic field in the oral cavity. The results showed that at certain frequencies there existed points where sound pressure was absolutely zero, with the phase spatially circulating around them. Up to about 4 kHz, except at these certain frequencies, the wave front was almost one-dimensional, though an amplitude gradient was seen in the vertical direction.

Acoustics↗