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Biomedical subjects

H Shimada

Publications and source records attributed to H Shimada.

At least 415 records · Page 23Linked to original sources
PubMed1996

Matrilysin is associated with progression of colorectal tumor.

Matrilysin and gelatinase A, B mRNA expressions were examined in colorectal tumors. Matrilysin mRNA was observed exclusively in tumors, while the others were also found in normal mucosa surrounding tumors. Further analysis revealed that colorectal adenomas with severe dysplasia, not with mild dysplasia, expressed matrilysin with lower levels than cancers. The level of matrilysin mRNA expression increased with the advancement of stages of colorectal cancers, consequently a relatively higher expression was observed in liver metastatic tumors than primary tumors. These results suggest that matrilysin mRNA expression was correlated with the progression of colorectal tumors, and this enzyme may also play a role in developing metastatic tumors in liver.

Adenoma↗
PubMed1996

Reduction of 14-16 kDa allergenic proteins in transgenic rice plants by antisense gene.

An antisense gene strategy was applied to suppress the 14-16 kDa allergen gene expression in maturing rice seeds. Gene constructs producing antisense RNAs of the 16 kDa allergen under the control of some rice seed-specific promoters were introduced into rice by electroporation. Immunoblot and RNA blot analyses of the seeds from the transgenic rice plants using the allergen-specific monoclonal antibody and a sequence-specific antisense RNA probe demonstrated that the 14-16 kDa allergen proteins and their transcripts of the seeds from several transgenic lines were present in much lower in amounts than those of the seeds from parental wild-type rice. The high levels of reduction observed were stably inherited in at least three generations.

Allergens↗
PubMed1996

Re-evaluation of chromosomal aberration induction on nine mouse lymphoma assay "unique positive' NTP carcinogens.

In a collaborative study organized under the JEMS MMS, nine mouse lymphoma assay (MLA) "unique positive' NTP rodent carcinogens were re-evaluated by an in vitro chromosomal aberration assay using Chinese hamster lung fibroblast cells (CHL/IU). Six of nine chemicals induced chromosomal aberrations; bromodichloromethane, chlorendic acid and isophorone induced structural aberrations, and chlorodibromomethane, pentachloroethane and 1,1,1,2-tetrachloroethane induced numerical aberrations (polyploidy). These six chemicals, therefore, are not uniquely positive in the MLA. The difference between the NTP results and ours might be due to the use of different cell lines and protocols, and in some cases, to different interpretations of polyploidy. The remaining three chemicals, benzyl acetate, cinnamyl anthranilate and trichloroethylene, were negative in this study.

Animals↗
PubMed1996

Role of Arg112 of cytochrome p450cam in the electron transfer from reduced putidaredoxin. Analyses with site-directed mutants.

The mechanism for the reduction of ferric cytochrome P450cam by reduced putidaredoxin, the physiological electron donor for the cytochrome, has been studied by using site-directed mutants of cytochrome P450cam, in which Arg112, an amino acid residue at the presumed binding site for putidaredoxin, was changed to several other amino acid residues. The affinity of reduced putidaredoxin for ferric cytochrome P450cam to form a diprotein complex was decreased greatly by changing Arg112 to a neutral amino acid such as Cys, Met, or Tyr. The rate of intracomplex electron transfer from putidaredoxin to cytochrome P450cam also diminished upon replacing the basic residue with neutral ones, being 42, 18, 4.0, 1.3, and 0. 16 s-1 for Arg (wild type), Lys, Cys, Met, and Tyr enzymes, respectively. Furthermore, the oxidation-reduction potential of cytochrome P450cam (Fe3+/Fe2+ couple) decreased in a similar way to the decrease in the rate of electron transfer upon amino acid substitution; the values were -138, -162, -182, -200, and -195 mV for Arg (wild type), Lys, Cys, Met, and Tyr enzymes, respectively. These results indicate that the amino acid substitution at position 112 affects the oxidation-reduction potential of the heme iron in cytochrome P450cam, thereby diminishing the rate of electron transfer between the two metal centers. The rate of electron transfer from putidaredoxin to oxyferrous cytochrome P450cam also diminished upon substitution of Arg112 with a neutral amino acid.

Arginine↗
PubMed1996

Overexpression of tissue inhibitor of metalloproteinases-2 retroviral-mediated gene transfer in vivo inhibits tumor growth and invasion.

We have demonstrated previously that overexpression of tissue inhibitor of metalloproteinases-2 (TIMP-2), an inhibitor of matrix-degrading metalloproteinases, not only inhibits the invasive and metastatic behavior of tumor cells but also significantly decreases tumor growth in vivo (Y. A. DeClerck et at, Cancer Res., 52: 701-708, 1992). This latter effect was found to be dependent on the ability of TIMP-2 to prevent the degradation of the collagen matrix (A. M. Montgomery et al., Cancer Res., 54: 5467-5473, 1994). In this report, we have overexpressed TIMP-2 in tumor tissue by retroviral-mediated gene transfer into tumor cells by co-injecting s.c. in nude mice tumorigenic c-Ha-ras-transfected rat embryo fibroblasts with irradiated packaging cells producing high titer retroviral vectors containing the human TIMP-2 cDNA. The growth rate of tumors derived from cells co-injected with the TIMP-2 vector producer cells was significantly slower than the growth rate of tumors derived from cells co-injected with packaging cells producing a retrovirus containing the Escherichia coli beta-galactosidase gene. The transduction efficiency was estimated at 13%, and the production of a functional human TIMP-2 in tumor cells transduced with the TIMP-2-containing vector was documented. Furthermore, histological analysis of tumors derived from tumor cells co-injected with the TIMP-2 vector producer cells revealed the presence of a thick connective tissue capsule and a lack of local invasion. The data indicate that retroviral-mediated transduction of TIMP-2 cDNA into a limited population of tumor cells in vivo is sufficient to increase the accumulation of connective tissue proteins in tumor tissue, to inhibit growth, and to prevent local invasion.

3T3 Cells↗
PubMed1996

Different exon-intron organizations of the genes for two astacin-like proteases, high choriolytic enzyme (choriolysin H) and low choriolytic enzyme (choriolysin L), the constituents of the fish hatching enzyme.

The hatching enzyme of the teleost, Oryzias latipes, is composed of two proteases, high choriolytic enzyme (choriolysin H, HCE) and low choriolytic enzyme (choriolysin L, LCE), which are similar in some enzymological characteristics and protein structure (55% identity in amino acid sequence) and belong to the astacin family. Two isoforms of HCE are detected. In the present study, the genes for HCE and LCE were isolated from the genomic library constructed from DNA of the inbred drR strain fish. In contrast to the close similarity of the enzymes, there was a marked difference in their gene organization. The LCE gene was a single copy gene and composed of eight exons interrupted by seven introns. The HCE genes were multicopy genes and lacked introns. In the haploid genome of the drR strain fish, there are eight HCE genes, seven of which were cloned. Each HCE gene was identified as that for either of the two isoforms of HCE. 5' flanking regions of the LCE gene and the HCE genes had consensus TATA box sequences, but not CAT box nor GC box sequences. The big difference in the exon-intron organization between the HCE genes and the LCE gene is discussed from an evolutionary viewpoint.

Amino Acid Sequence↗
PubMed1996

Micronucleus induction by chromium and selenium, and suppression by metallothionein inducer.

The clastogenic effects of chromium compounds (CrCl3 and K2CrO4) and selenium compounds (H2SeO3 and Na2SeO4) in mouse bone marrow cells have been investigated. K2CrO4 induced significant, dose-related increases in micronuclei. H2SeO3 also showed a significant micronucleus induction at the highest dose. CrCl3 and Na2SeO4 were negative for micronuclei induction in mice. The suppressive effect of Bi(NO3)3, a metallothionein inducer, on the micronucleus induction by K2CrO4 and H2SeO3 has been also investigated. Pretreatment with Bi(NO3)3 suppressed the micronucleus induction by K2CrO4 and H2SeO3. In addition, the incidence of micronucleus induction seemed to be reduced by double dosing with K2CrO4 and H2SeO3, compared to single dosing. It is generally recognized that a number of metal compounds induce metallothionein synthesis. These results suggest that the mechanism of suppression of micronucleus induction by K2CrO4 and H2SeO3 involve possible participation of metallothionein in mouse bone marrow.

Animals↗
PubMed1996

Antitumor effect induced by the expression of granulocyte macrophage-colony stimulating factor gene in murine colon carcinoma cells.

Murine colon carcinoma cells which secrete several kinds of cytokine after retroviral transduction with corresponding genes, were examined for their antitumor effects in syngeneic mice. The mice inoculated with granulocyte macrophage-colony stimulating factor (GM-CSF) producer cells showed not only prolonged survival but also reduced tumorigenicity. The antitumor effect caused by the expression of interleukin-4 was less than that of GM-CSF, and interleukin-6 producer cells did not show any effects on the survival of the host animals. Histological examination of the GM-CSF-producing tumor revealed predominant infiltration of neutrophils and necrotic change of the tumor. The present study indicates the feasibility of cancer gene therapy with the expression of GM-CSF gene in tumor cells.

Animals↗
PubMed1996

Murine colon carcinoma cells engineered to produce human interleukin-2 induce tumor-specific anti-tumor response.

Murine colon carcinoma cells (colon 26) transduced by a retrovirus vector with the human interleukin-2 (IL-2) cDNA were studied for their tumorigenicity. Although cell growth in vitro was not affected by integration of the IL-2 gene, s.c. tumors of IL-2-producing colon 26 cells (H2) in syngeneic mice regressed spontaneously after producing small masses. Histological examination of the sites of tumor rejection revealed predominant infiltration of macrophages around the tumor necrotic mass. Subsequent challenge with parent colon 26 cells, but not with Meth A cells (fibrosarcoma of the same genetic background), did not result in tumor formation in mice which had been protected against H2 cells. Inoculation of H2 cells into syngeneic nude mice resulted in tumors with a retarded growth rate. Taken together, T cell-dependent, tumor-specific immunity is obtained by local IL-2 secretion around colon tumors, and this experimental animal model gives us a clue(s) for investigating host anti-tumor responses by cytokine production.

Animals↗
PubMed1996

Antibody against synthetic multiple antigen peptides (MAP) of JC virus capsid protein (VP1) without cross reaction to BK virus: a diagnostic tool for progressive multifocal leukoencephalopathy.

Antibody against JC virus (JCV) was raised in rabbits with the use of synthetic multiple antigen peptides. The peptide sequences were derived from three regions of JCV VP1 protein, which showed less similarity with BK virus (BKV) counterpart. The antibodies raised with these peptides were designated as JCAb1, 2 and 3. JCAb1 specifically reacted with JCV and not with BKV, while JCAb2 and 3 reacted both with JCV and BKV. All of these antibodies reacted with JCV antigen of formalin-fixed paraffin sections of progressive multifocal leukoencephalopathy (PML) brain tissue. As JCAb1 is JCV-specific and reacted with JCV in formalin-fixed paraffin sections, it will contribute not only to rapid and accurate immunohistochemical diagnoses of PML but also to clarification of the pathogenesis of JCV infection.

Amino Acid Sequence↗
PubMed1996

NADPH-specific quinone reductase is induced by 2-methylene-4-butyrolactone in Escherichia coli.

2-Methylene-4-butyrolactone (MBL), an inducer of NAD(P)H:(quinone acceptor) oxidoreductase (EC 1.699.2) in animal cells, was found to induce NADPH-specific quinone reductase about 25-fold in Escherichia coli. MBL induced NADPH-quinone reductases with relative mobilities (Rm) of 0.70, 0.76 and 0.91 on polyacrylamide gel electrophoresis (PAGE). These three enzymes were found to be charge isomers with the same molecular size of 42 kDA. Two NADPH-quinone reductases (A and B) were purified to single proteins both with an apparent mass of 21 kDa on SDS-PAGE. Enzyme A corresponded to the activity of the band at Rm 0.76 with a minor active band at Rm 0.70, and enzyme B to the activity of band Rm 0.91. Both enzymes reacted exclusively with NADPH and were most active toward quinone derivatives and ferricyanide with the optimum pH at 7.0. The reaction followed a ping-pong mechanism with Km values for NADPH and menadione of 10.5 microM and 6 microM, respectively. The sequences of 20 amino acids at the N-terminal of enzymes A and B were identical, and furthermore coincided with that of the E. coli modulator of drug activity (mda66) submitted under the accession number U18656.

4-Butyrolactone↗
PubMed1996

Effects of new quinolone antibacterial agents on mammalian chromosomes.

The clastogenic effects of several new quinolones (ciprofloxacin, enoxacin, levofloxacin, nalidixic acid, ofloxacin, pipemidic acid, and N1-cyclopropyl quinolones for drug candidate) were studied cytogenetically using Chinese hamster lung cells (CHL) and the mouse micronucleus test. Some N1-cyclopropyl quinolones strongly induced chromosomal aberration on CHL cells, and some, but not all, were also capable of inducing micronuclei in mouse bone marrow cells. Levofloxacin showed weak clastogenicity in CHL cells but did not induce either micronuclei in mouse bone marrow or unscheduled DNA synthesis (UDS) in rat hepatocytes when administered to intact live animals. The lack of concordance between in vitro and in vivo assays could reflect the differences in the tissue levels of the drugs and the in vitro conditions.

Animals↗
PubMed1996

Chick embryos as an alternative experimental animal for cardiovascular investigations: stable recording of electrocardiogram of chick embryos in ovo on the 16th day of incubation.

Recording of electrocardiogram (ECG) tracings in developing chick embryos often fails because of spontaneous motion of the embryos in the egg shell. We attempted to record ECG of chick embryos in ovo. When we injected a mixture of 450 mg/ml urethane and 45 mg/ml alpha-chloralose into the air sac of fertile eggs at volumes of 0.1 to 0.3 ml, the spontaneous motor activity of chick embryos was decreased and stable ECG tracings could be obtained from at least 10 min after the injection. The P, QRS, and T waves were noted in the electrograms, and the QT interval was positively correlated to the RR interval. The heart rate (HR) could be analyzed for the RR interval in fertile eggs after the 8th day of incubation. The HR of the 16-day fertile embryos was linearly increased with incubation temperature in the range from 31 to 41 degrees C. Using this system, cardiac effects of some drugs were examined. Isoprenaline and acetylcholine increased and decreased the HR in a dose-dependent manner, respectively, and these effects were inhibited by respective antagonists, propranolol and atropine. These ECG responses of chick embryos were similar to those of mammals or humans. In conclusion, stable ECG tracings could be obtained from chick embryos anesthetized by urethane and alpha-chloralose in ovo and this method may be applicable for the investigation of the developing heart and the evaluation of cardiovascular drugs.

Age Factors↗
PubMed1996

Male sexual function after autonomic nerve-preserving operation for rectal cancer.

PURPOSE: Sexual dysfunction after surgery of the rectum is a serious complication to male patients. Autonomic nerve-preserving operation for rectal cancer has been performed within the recent ten years to maintain urinary and male sexual functions without spoiling of therapeutic radicality. To clarify male sexual function as the degree of autonomic nerve-preserving operation, the function was outlined through clinical interview. METHOD: In a series of 134 male patients who were undergoing autonomic nerve-preserving operation for rectal cancer, a detailed history of postoperative sexual function was obtained by interviews. RESULTS: In 87.7 and 66.9 percent of patients, erectile and ejaculatory potencies were maintained, respectively, which were higher rates than those after extended and conventional pelvic dissections. According to the preserving extent of autonomic nerve, patients undergoing complete preserving operations showed higher rates of maintained erectile (92.9 percent) and ejaculatory functions (82.5 percent), sexual intercourse (89.9 percent), and orgasm (93.9 percent) compared with those undergoing hemilateral autonomic nerve-preserving (82.3, 47.1, 52.9, 64.7 percent) or partial pelvic plexus-preserving operation (61.1, 0, 26.3, 22.2 percent). CONCLUSION: Pelvic plexus preservation is necessary to maintain erectile potency, and both hypogastric nerve and pelvic plexus preservation are necessary to maintain ejaculate function and orgasm. To maintain satisfactory sexual function, complete autonomic nerve-preserving operation is suitable.

Aged↗
PubMed1996

Immediate application of hyperbaric oxygen therapy using a newly devised transportable chamber.

A transportable hyperbaric chamber called the Gamow bag has been reported as an effective means of treating high-altitude illness. The pressure limit of the original bag is set at 2 psi because of the fragility of the fabric. However, improvement of the hardware to make the bag capable of withstanding higher pressures has made it possible to perform standard hyperbaric oxygen therapy with the newly devised portable chamber, the Chamberlite 15. In this study, the safety of the new bag was examined using healthy human volunteers, and the bag was shown to be usable in clinical emergency cases, such as CO intoxication and decompression sickness. The effectiveness of emergency hyperbaric oxygen therapy was also examined using the CO intoxication model of the rat. It was suggested that hyperbaric therapy was especially beneficial if applied during the first 30 minutes of rescue work. It was concluded that the transportable chamber was a promising emergency tool for CO intoxication.

Animals↗
PubMed1996

Spatial expression of a forkhead homologue in the sea urchin embryo.

Echinoderms are the sister group of the chordates and hemichordates within the deuterostomes. They lack a notochord or any structures obviously homologous with it. To gain insight into developmental mechanisms important in the origin and early evolution of chordates, we investigated sea urchin homologues of chordate genes that are implicated in notochord formation, viz. Brachyury and HNF-3 beta. Here we report the pattern of expression of a sea urchin orthologue of forkhead, Hphnf3 which is present as a single copy per haploid genome. An Hphnf3 transcript of 3.0 kb was first detected at the swimming blastula stage, accumulated maximally at the gastrula and prism-embryo stages, and decreased at the pluteus-larva stage. In situ hybridization signals were found in cells of the vegetal plate of the swimming blastula. During gastrulation, intense staining was evident in the cells surrounding the blastopore, whereas weak staining was detected in the invaginating archenteron. At the prism-embryo stage, the entire archenteron stained intensely; then, at pluteus stage, the larva staining decreased in intensity. The forkhead and Brachyury genes begin to be expressed almost simultaneously in sea urchin embryos, in the vegetal plate at the late blastula stage. After the onset of gastrulation, however, Hphnf3 is expressed in the posterior part of the archenteron, whereas the Brachyury orthologue, HpTa, is expressed in the secondary mesenchyme founder cells, which occupy the anterior tip of archenteron. Hphnf3 may contribute to specification of embryonic cells as archenteron, and the role of HpTa may be directed towards specification of mesodermal founder cells. Except for the basal character of expression in endoderm and endomesoderm, these transcription factors are clearly utilized differently in chordates.

Amino Acid Sequence↗
PubMed1996

Bioactive ent-kaurene diterpenoids from Annona senegalensis.

Activity-guided fractionation of the stem bark of Annona senegalensis gave four bioactive ent-kaurenoids (1-4). Compound 2 showed selective and significant cytotoxicity for MCF-7 (breast cancer) cells (ED50 1.0 microgram/mL), and 3 and 4 exhibited cytotoxic selectivity for PC-3 (prostate cancer) cells but with weaker potencies (ED50 17-18 micrograms/mL). The structure of the new compound, 3, was deduced from spectral evidence.

Africa↗