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Biomedical subjects

M Horiuchi

Publications and source records attributed to M Horiuchi.

At least 217 records · Page 12Linked to original sources
PubMed1993

Distinct nuclear proteins competing for an overlapping sequence of cyclic adenosine monophosphate and negative regulatory elements regulate tissue-specific mouse renin gene expression.

The mouse renin locus (Ren-1d) exhibits specific patterns of tissue expression. It is expressed in kidney but not submandibular gland (SMG). This locus contains a negative regulatory element (NRE) and a cAMP responsive element (CRE) that share an overlapping sequence. In the kidney, CRE binding proteins (CREB) and NRE binding proteins (NREB) compete for binding to this sequence, with the CREB having a greater affinity. In the SMG, CREB is inactivated by an inhibitory protein, permitting NREB to bind to the sequence, thus inhibiting Ren-1d expression. We hypothesize that the competition between NREB and CREB for this sequence governs tissue-specific expression of mouse renin. We speculate that this may be a general paradigm that determines tissue-specific gene expression.

Animals↗
PubMed1993

Familial scrapie cases with shortened incubation periods.

Two familial scrapie cases successively occurred in 29-month-old and 30-month-old Corriedale dams and in three of their offspring as early as 10-19 months of age in a small flock. They showed ataxy but no pruritus. Histopathological and immunochemical examinations of those sheep revealed vacuolation of nerve cells in brain tissue and presence of PrPsc, a component of scrapie-associated fibrils, in brain, spleen and lymph node tissues. We discuss about shortened incubation periods and lacking pruritus in the present scrapie cases.

Animals↗
PubMed1993

DNA binding properties of c-Myc-related bHLH/LZ oncoproteins.

Structural features and DNA binding properties of bacterially expressed c-Myc related oncoproteins were examined. The circular dichroism spectra demonstrated highly alpha-helical nature of these proteins. Dimerization and the DNA binding of these proteins were examined by electrophoretic mobility shift assay.

Circular Dichroism↗
PubMed1993

[A new departure of an incorporated round visits; anesthesiologists and pharmacists ].

We commenced a new trial of an incorporated round visit. Members of round visit are 4 anesthesiologists and 2 pharmaceutists. This new trial gives us the following advantages; 1. We can get the newest drug informations at bed side during the round visit. 2. We can select a more reasonable therapy for patients through discussions. 3. Cooperative development of clinical studies concerning a new model or style of drugs may be possible. This new style of round visit is also of benefit for patients because it leads to administration of more pertinent drugs. We recommend to have a chance of cooperation between anesthesiologists and pharmaceutists in other hospitals.

Anesthesia Department, Hospital↗
PubMed1992

Carnitine administration to juvenile visceral steatosis mice corrects the suppressed expression of urea cycle enzymes by normalizing their transcription.

Previous studies in our laboratories have revealed that juvenile visceral steatosis mice show suppressed transcription of urea cycle enzyme genes during development and are systemically deficient in carnitine. It has not yet been explained, however, how this carnitine deficiency relates to the abnormal gene expression. We investigated the effect of carnitine on abnormal gene expression, growth retardation, and fatty liver. Carnitine administration relieved the suppression of the developmental induction of two urea cycle enzymes examined, carbamoyl-phosphate synthetase and argininosuccinate synthase, and kept the activities of enzymes normal. However, carnitine did not reduce accumulated lipid in the liver to the normal level. These results suggest that carnitine deficiency plays an important role in the abnormal expression of urea cycle enzyme genes and that the abnormal expression of the genes is not directly caused by lipid accumulation in the liver.

Aging↗
PubMed1992

Abnormal expression of urea cycle enzyme genes in juvenile visceral steatosis (jvs) mice.

Juvenile visceral steatosis (jvs) mice from the C3H-H-2 degrees strain have markedly low levels of all the hepatic urea cycle enzymes (Imamura et al. (1990) FEBS Lett. 260, 119-121). The steady state levels of messenger RNA for the four urea cycle enzymes examined and also for albumin and serine dehydratase were severely reduced in the liver. The levels of mRNA for other liver-specific enzymes including aldolase B and phospho enol pyruvate carboxykinase did not vary significantly from normal littermates. As for extrahepatic expression of the urea cycle enzymes, only argininosuccinate synthetase in the kidney was decreased. Nuclear run-on experiments showed reduced transcription of the corresponding genes, which mostly accounts for the low mRNA levels. Furthermore, the time-course of mRNA accumulation from 5 days of age showed that the developmental induction of hepatic carbamyl phosphate synthetase and argininosuccinate synthetase mRNAs was strongly suppressed. These results suggest that jvs affects not only the regulation of the tissue-specific expression of the urea cycle enzymes but also the regulation of their developmental induction.

Animals↗
PubMed1992

Identification of a negative regulatory element involved in tissue-specific expression of mouse renin genes.

The 5' flanking region of the mouse renin genes (Ren-1d and Ren-2d) contains two motifs that are homologous to known negative regulatory elements (NREs). Ren-2d has a 150-base-pair (bp) insertion 5' to the upstream putative NRE (NRE-1), which is lacking in Ren-1d. We tested the functionality of these sequences by using site-directed mutagenesis to delete individually each putative NRE from Ren-1d and to delete the 150-bp insertion from Ren-2d. We examined the effect of these mutations on the expression of the reporter gene chloramphenicol acetyltransferase, which was expressed from a truncated thymidine kinase promoter fused to the renin regulatory region. This plasmid was transfected into human choriocarcinoma JEG-3 cells. Only the upstream NRE (positions -619 to -597) was found to be functional in Ren-1d. The deletion of a 150-bp insertion from Ren-2d resulted in the suppression of chloramphenicol acetyltransferase activity to the level of Ren-1d expression. These data suggest that the upstream NRE that is functional in Ren-1d, but not in Ren-2d, may be partly responsible for differential expression of the renin genes in various tissues. The molecular mechanism of the NRE was examined by studying its interaction with nuclear proteins in submandibular gland and JEG-3 cells by gel-mobility-shift assays. Specific nuclear protein binding was observed only to the upstream NRE and the molecular mass of this protein was approximately 72 kDa as determined by Southwestern blot analysis. Thus our results suggest that both Ren-1d and Ren-2d conserve a cis-acting NRE in the 5' flanking region. In Ren-1d, this NRE could bind a specific nuclear protein resulting in the inhibition of Ren-1d expression in these tissues. On the other hand, the NRE in Ren-2d is nonfunctional due to interference by an adjacent 150-bp insertion.

Animals↗
PubMed1992

A specific RFLP type associated with the occurrence of sheep scrapie in Japan.

We have investigated restriction fragment length polymorphism (RFLP) on the PrP gene and the frequencies of RFLP patterns in 35 healthy Suffolk sheep randomly collected. According to the combinations of PrP encoding DNA fragments generated by restriction enzymes Eco RI and Hind III, the RFLP patterns were classified into six types and designated as types I to VI. The frequencies of these types were as follows: I, 8.6%; II, 11.4%; III, 17.6%; IV, 11.4%; V, 28.6%; and VI, 22.9%. In 10 sheep diagnosed as having natural scrapie, RFLP types, I, III, IV, and V were determined. To examine the correlation between the RFLP type and the occurrence of scrapie, the frequencies of RFLP types in sheep infected with natural scrapie were compared with those in healthy sheep. It was found that the frequency of type I in the sheep with natural scrapie was 70%, about eight times higher than that in randomly collected healthy sheep. In the 13 experimentally infected sheep that had been used for other purposes, however, no relationship between the RFLP type and onset of scrapie was found.

Animals↗
PubMed1992

Comparative sequence analysis and expression of bovine PrP gene in mouse L-929 cells.

A cDNA clone encoding bovine scrapie-associated fibril protein, PrP, from a bovine brain cDNA library and six amplified genomic DNA clones of bovine PrP were characterized. These clones possessed specific characteristics observed in other animal PrP genes. However, the bovine PrP was divided into two types by the number of repeats. One possessed four octapeptide repetitive sequences, like other animal PrP genes, and consisted of 256 amino acids; the other had five such repetitive sequences and 264 amino acids. The amino acid sequence of the former bovine PrP agreed with that of sheep PrP up to the 165th amino acid from the N-terminus. Bovine PrP cDNA introduced into mouse L-929 cells were stably expressed. The expression level of recombinant bovine PrP in the cells judged by immunofluorescence was higher than that of authentic mouse PrP. The recombinant PrP comigrated with authentic bovine PrP in SDS-polyacrylamide gel electrophoresis, suggesting that the recombinant product was fully glycosylated in L-929 cells. Distinct bundles of the intermediate filaments were frequently seen at the perinuclear region of the cells.

Amino Acid Sequence↗
PubMed1992

Characterization of the stage(s) in the virus replication cycle at which the host-cell specificity of the feline parvovirus subgroup is regulated in canine cells.

Feline panleukopenia virus (FPLV), mink enteritis virus (MEV), and canine parvovirus (CPV) are classified as a host-range variants. They show different host-range specificity in vivo and host-cell specificity in vitro. For instance, FPLV and MEV cannot grow or can grow only inefficiently in canine cell lines such as MDCK and the canine fibroma cell line A72. Here we have studied the mechanism(s) by which the different cell tropism is mediated in vitro. When FPLV or MEV was inoculated to A72 cells, viral DNA replicated slightly, few viral-antigen-positive cells were detected, and the culture fluid contained the threshold level of infectivity. On the other hand, when an infectious molecular clone of MEV (pMEV) was introduced into A72 cells, viral DNA replicated efficiently, and the culture fluid of pMEV-transfected cells contained much higher infectivities than that of MEV-infected cells. In spite of the restrictive growth in A72 cells, MEV could bind to A72 cells as efficiently as CPV. No detectable viral RNA was produced in MEV-infected A72 cells. In contrast, efficient viral transcription occurred in pMEV-transfected A72 cells. These results suggest that the restrictive infections of MEV and FPLV in A72 cells are not mediated by the attachment of the virus to the cells or by the events occurring after the viral transcription. It appears to be caused by the stage(s) in the virus replication cycle, which exists between a postadsorptional step required for virus penetration and the initiation of viral transcription.

Aleutian Mink Disease Virus↗
PubMed1992

Biological activity of subfractions from scrapie-associated fibrils.

Subfractions, a nucleic acid fraction and a PrP fraction consisting of PrP17-25, a core fragment of PrPsc, were prepared from the scrapie-associated fibril-enriched fraction from scapie-affected mouse brains. The nucleic acid fraction consisted mainly of variously fragmented DNA and no scrapie-specific nucleic acid was detected in the fraction by SDS polyacrylamide gel electrophoresis. To examine the biological activity, the nucleic acid fraction was either first introduced into mouse L-929 cells before or after nuclease treatments, then transfected cell lysates prepared 2 weeks later were inoculated into mice, or directly inoculated into mice with or without the PrP fraction. The PrP fraction alone was also inoculated into mice. Mice inoculated with the transfected cell lysates or with the nucleic acid fraction alone showed no scrapie signs during their lifespan or the observation period. While 60% of the mice inoculated with the PrP fraction alone and 67% of those inoculated with the fraction together with the nucleic acid fraction showed clinical signs of scrapie. A nucleic acid molecule bound covalently to PrP17-25 was not detected. The results obtained by the present procedures so far suggest scrapie infectivity to be associated with PrPsc, which does not contain any detectable scrapie-genome molecule as either free or covalently bound nucleic acid.

Animals↗
PubMed1992

[Ototoxicity of cis-diammine glycolato platinum, 254-S].

Ototoxicity of cis-diammine glycolato platinum, 254-S, was evaluated from the results obtained in phase II studies for head & neck cancer, lung cancer, breast cancer, gastrointestinal cancer, urogenital cancer and gynecological cancer at 114 institutions, and in randomized comparative study of 254-S plus vindesine vs. cisplatin plus vindesine for advanced non-small cell lung cancer conducted at 41 institutions. In these studies, 254-S was administered at doses ranging from 80 to 100 mg/m2, repeated at least 2 times at 4-week intervals. Impaired hearing was examined in a hearing audiometry test before and after 254-S administration. The incidence of impaired hearing was 25.8% (16/62) in the 254-S phase II studies. The incidences in the randomized comparative study were 17.6% (3/17) for the 254-S/vindesine group and 20.0% (3/15) for the cisplatin/vindesine group. From these results, the ototoxicity of 254-S was thought to be similar to that of cisplatin in incidence and type.

Aged↗
PubMed1992

[An early phase II clinical study of cis-diammine glycolato platinum, 254-S, for head and neck cancers].

An early phase II clinical study of 254-S, a new anticancer platinum complex, for head and neck cancer was conducted by the 254-S Head and Neck Cancer Study Group consisting of 10 institutions. Based on the results obtained in the phase I study, 254-S was administered at 100 mg/m2 by 60 min intravenous drip infusion after being dissolved in 300 ml of 5% xylitol. In principle, the 254-S administration was repeated at least 2 times at 4 week intervals. Hydration was performed, if needed. All 24 cases registered were regarded as complete cases evaluable for tumor response. Complete response (CR) was observed in 4 patients (16.7%), partial response (PR) in 5 (20.8%), no change (NC) in 11 and progressive disease (PD) in 4, for a 37.5% response rate. Three CR and 3 PR (40.0%) were obtained in 15 patients with prior chemotherapy, including 1 CR and 2 PR (33.3%) in 9 patients previously treated with cisplatin. Side effects were observed in 19 patients (79.2%). Major toxic effects were hematotoxicity, including thrombocytopenia (58.3%), leukopenia (58.3%) and anemia (33.3%), and gastrointestinal toxicity, including nausea and vomiting (45.8%) and anorexia (37.5%). Abnormal parameter changes on renal function were found in 2 patients (8.3%). Based on these results, it was concluded that 254-S is potentially a useful anticancer agent for the treatment of head and neck cancer, and should be further investigated in a late phase II clinical study.

Adenocarcinoma↗
PubMed1992

[A late phase II clinical study of cis-diammine glycolato platinum, 254-S, for head and neck cancers].

A late phase II clinical study of 254-S, a new anticancer platinum complex, for head and neck cancer was conducted by the 254-S Head and Neck Cancer Study Group consisting of 31 institutions. As in the early phase II study for head and neck cancers, 254-S was administered at 100 mg/m2 by 60 min intravenous drip infusion, repeated at least twice at 4-week intervals. Of 80 cases registered, 66 were regarded as complete cases evaluable for tumor response. Complete response (CR) was observed in 7 patients (10.6%), partial response (PR) in 22 (33.3%), no change (NC) in 24 and progressive disease (PD) in 13, for a 43.9% response rate. Two CR and 11 PR (37.1% response rate) were obtained in 35 patients with prior chemotherapy, including 2 CR and 7 PR (33.3% response rate) in 27 patients previously treated with cisplatin. Of 70 patients evaluable for toxicity, side effects were observed in 60 patients (85.7%). Major toxic effects were hematotoxicity, including leukopenia (62.9%), thrombocytopenia (40.0%) and anemia (45.7%), gastrointestinal toxicity, including nausea and vomiting (64.3%), and anorexia (47.1%); grade 3 or 4 thrombocytopenia was found in 20.0% of the patients, and this toxicity was regarded as the dose limiting factor. Nephrotoxicity observed was mild and infrequent. Based on these results, it was concluded that 254-S is a very useful anticancer agent for the treatment of head and neck cancer.

Adenocarcinoma↗
PubMed1992

[Effects of hypotensive anesthesia with prostaglandin E1 or trimethaphan on renal microstructure].

A study was made on the presence or absence and the degree of histopathological renal cell damage, in hypotensive anesthesia models with prostaglandin E1 (PGE1) or trimethaphan. Cell damage was most noticeable in the S3 segment, the straight and second half part of the proximal renal tubule. The lesion was evaluated and semiquantified. The trimethaphan group in this area exhibited degeneration--including cell vacuolation and granule increase in this site, as well as cytoclasis such as cell fragments in the lumen, luminal extension, flattening of epithelial cell and damage of distal renal tubular columns. In the PGE1 group, cell degeneration was milder than in the trimethaphan group, and there were no cytoclasis findings. Renal cell damage in the PGE1 group was slighter than in the trimethaphan group.

Alprostadil↗
PubMed1991

Molecular mechanism of tissue-specific regulation of mouse renin gene expression by cAMP. Identification of an inhibitory protein that binds nuclear transcriptional factor.

Renin gene expression in the mouse kidney and submandibular gland (SMG) are differentially regulated by cAMP. In this study, we examined the potential molecular mechanism responsible for this tissue-specific regulation. 32P end-labeled synthetic oligonucleotide containing mouse renin cAMP-responsive element (CRE) was incubated with kidney nuclear extracts from either control or cAMP-treated mice and analyzed by gel mobility shift assay. Our results demonstrated that cAMP induced a nuclear protein which complexed with the CRE oligonucleotide in a specific manner. This nuclear protein-DNA binding was competed effectively by the oligonucleotide containing human chorionic gonadotropin alpha-subunit CRE but not by the mouse renin DNA fragment from which the CRE was deleted by site-directed mutagenesis. In contrast, no DNA-protein complex formation could be detected when this [32P]CRE oligonucleotide was incubated with the SMG nuclear extract from control or cAMP-treated mice. However, CRE-binding protein complex formation was demonstrated in the SMG nuclear extract when the incubation was performed in the presence of 0.8% sodium deoxycholate and 1.2% Nonidet P-40, detergents that dissociate protein-protein complexes. Furthermore, in the absence of deoxycholate, we observed that SMG nuclear extract attenuated the binding of the kidney CRE-binding protein to mouse renin CRE in a dose-dependent manner and this inhibitory effect of SMG nuclear extract disappeared in the presence of sodium deoxycholate. This inhibitory nuclear protein in SMG is specific for CRE-binding protein since it does not affect nuclear protein binding to synthetic DNA oligonucleotides of human collagenase AP-1 and human metallothionein AP-2. Our data further suggest that inhibitory nuclear protein is present in lower quantities in other extrarenal tissues, i.e. testes, liver, brain, heart, but is not detectable in the kidney. Taken together, these results suggest that the SMG and certain extrarenal tissues contain nuclear trans-acting factor(s) that interact with CRE-binding protein, thereby interfering with its binding to mouse renin CRE. The presence of this inhibitory protein in the mouse SMG nucleus may contribute to the tissue-specific regulation of the renin gene expression by cAMP.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1991

Animal model of systemic carnitine deficiency: analysis in C3H-H-2 degrees strain of mouse associated with juvenile visceral steatosis.

We analyzed carnitine profiles in C3H-H-2 degrees strain of mouse associated with fatty liver, hyperammonemia and hypoglycemia (Koizumi et al., 1988). Carnitine levels in serum, liver and muscle of mouse with fatty liver were markedly decreased in comparison with those of control mouse (littermates without fatty liver). This is a useful animal model to analyze the role of carnitine in lipid, amino acid and carbohydrate metabolism.

Aging↗