Search PubMed⌕ Search

Biomedical subjects

M Takagi

Publications and source records attributed to M Takagi.

At least 469 records · Page 26Linked to original sources
PubMed1995

Functional magnetic resonance imaging of the primary visual cortex: evaluation of human afferent visual system.

The authors evaluated signal changes in the human primary visual cortex during visual stimulation using functional magnetic resonance imaging (MRI) scanner at 1.5 Tesla. Experiments were performed on 10 normal volunteers and 2 patients with homonymous hemianopsia. In the normal volunteers, a signal increase was observed on the bilateral primary visual cortex during hemifield stimulation. In one patient with homonymous hemianopsia after cerebral infarction, the signal change was clearly decreased on the affected side. In the other patient, who was recovering from multiple sclerosis to an almost normal visual field, the fMRI results were within normal limits. These results suggest that it is possible to map noninvasively the activation of the visual stimulation with a clinical MRI system, and that this test might be useful as an objective method of visual field examination.

Adult↗
PubMed1995

[31P-MR spectroscopy of bone and soft tissue lesions].

We studied 24 patients with bone and soft tissue lesions using 31P-MR spectroscopy (MRS). On image selected in vivo spectroscopy (ISIS) localized spectra, spectroscopic parameters were calculated: PME/noise ratio, gamma NTP/noise ratio, PME/gamma NTP and total metabolite signals (TMS). PME/noise, PME/gamma NTP and TMS were higher in malignant lesions than in benign ones. We set the criterion for malignancy as follows: PME/noise > 2.0 and gamma NTP/noise > 2.0 and PME/gamma NTP > 1.0. The accuracy of this criterion was 0.91 for malignant lesions and 1.0 for benign lesions. In six malignant tumors, MR spectra were obtained before and after chemotherapy. They were compared with the degree of tissue degeneration evaluated on pathological specimens. TMS after chemotherapy were markedly reduced in 3 cases. TMS seemed to reflect the degeneration of tumors. It could be said that MRS is a useful tool in differentiating from benign tumor lesions malignant bone or soft tissue lesions and in monitoring the effect of chemotherapy.

Adolescent↗
PubMed1995

The 5' flanking sequences of two S alleles in Lycopersicon peruvianum are highly heterologous but contain short blocks of homologous sequences.

To characterize the molecular structure of the S alleles in Lycopersicon peruvianum, we isolated two genomic fragments that corresponded to cDNAs for S11 and S12 RNases from a genomic library of a plant with the S11S12 genotype. The coding regions and the flanking regions in both fragments were sequenced. A single short intron was found in each gene for RNase, and it was located in the previously identified HV2 region [Chung et al. (1994) Plant Mol. Biol. 26: 757]. The site of initiation of transcription of the gene for S11 RNase was determined by a primer extension analysis and a putative TATA box was identified. Three short sequences that were highly homologous in the two S alleles were found within 360 bp upstream of the ATG initiation codon. It is suggested that these sequences might be involved in the regulation of transcription required for the appropriate-level or tissue-specific expression of the S genes in L. peruvianum.

Alleles↗
PubMed1995

Laboratory evaluation of a juvenile hormone mimic, pyriproxyfen, against Chironomus fusciceps (diptera: chironomidae).

The efficacy of the insect growth regulator, pyriproxyfen, against Chironomus fusciceps was examined in the laboratory. A series of 6 concentrations (0.1-0.00001 ppm) was used. A positive relationship between mortality and concentration was observed in the pupal stage as well as in the larval stage. Pyriproxyfen caused 50 and 90% emergence inhibition of C. fusciceps at 0.00177 and 0.05369 ppm, respectively.

Animals↗
PubMed1995

Tissue inhibitor of metalloproteinase 1, collagenolytic and gelatinolytic activity in loose hip endoprostheses.

OBJECTIVE: To study tissue inhibitor of metalloproteinase 1 (TIMP-1) in relation to collagenolytic and gelatinolytic potential, namely dinitrophenyl-Pro-Gln-Gly-Ile-Ala-Gly-Gln-D-Arg (DNP-S) sensitive proteolytic activity, in loose total hip arthroplasty (THA) endoprostheses. METHODS: Tissue localization of TIMP-1 was investigated immunohistochemically. TIMP-1 level of the periprosthetic tissues and fluid samples from 9 loose THA endoprostheses was measured by competitive ELISA, and DNP-S sensitive collagenolytic and gelatinolytic potential was evaluated by the degradation of synthetic DNP-S and reverse phase high performance liquid chromatography. RESULTS: Immunohistochemical analysis revealed moderate to marked immunoreactivity of TIMP-1 in pseudosynovial lining cells, and weak to moderate immunoreactivity often in monocyte/macrophages, endothelial cells, and fibroblasts in both interface tissues between bone and implant and pseudocapsular tissues around the artificial joints. TIMP-1 level was low in interface tissue samples (795 +/- 203 ng/ml) compared to pseudosynovial fluid samples (2026 +/- 584 ng/ml). Degradation rate of the substrate was higher in interface tissue samples (56 +/- 6%) than in pseudocapsular tissue samples (32 +/- 4%) and pseudosynovial fluid samples (6 +/- 2%). CONCLUSION: Low TIMP-1 level combined with high percentage of degradation of synthetic substrate DNP-S leads to high collagenolytic and gelatinolytic activity in interface tissue samples. This may in part explain the weakening of periprosthetic connective tissue. Weakening combined with cyclic mechanical loading may lead to loosening of THA endoprostheses.

Aged↗
PubMed1995

Evaluation of shading of fish farming ponds as a larval control measure against Anopheles sundaicus Rodenwaldt (Diptera:Culicidae).

Larval density of Anopheles sundaicus in shaded and unshaded fish farming ponds was monitored at a coastal village in North Sumatra, Indonesia. The average density in the experimentally shaded ponds with Nipa leaves was reduced to < 1/10. Disappearance of algae and decline of water temperature also were observed, but the salinity did not change. The larval density was lower in ponds with Tilapia sp than without fish, but that in ponds with Ophiocephalus sp was not significantly lower. Dominant insects collected by dipping were Agrionidae and Libellulidae (Odonata), Corixidae, Notonectidae and Nepidae (Hemiptera), and Dytiscidae (Coleoptera). Density of nymphs of both Odonata and Notonectidae was higher in unshaded ponds. Taking into account longevity of the materials, and easiness in construction and applicability, shading by Nipa leaves was an easy and effective larval control measure against A. sundaicus in non-operating small fish farming ponds if leaves were renewed once in every two months.

Animal Husbandry↗
PubMed1994

Identification of the bphA and bphB genes of Pseudomonas sp. strains KKS102 involved in degradation of biphenyl and polychlorinated biphenyls.

The nucleotide sequence of the upstream region of the bphC gene from Pseudomonas sp. strain KKS102 was determined. Four genes were found in this region. Deduced amino acid sequences of the first, second, third and fourth genes showed significant homology with a large subunit of iron-sulfur protein, a small subunit of iron-sulfur protein, ferredoxin and dihydrodiol dehydrogenase, respectively, from other bacteria which degrade biphenyl/polychlorinated biphenyls, toluene and benzene. E. coli, in which the four genes, bphC and the gene for ferredoxin reductase from benzene degrading bacterium were expressed, was able to produce meta-cleavage compounds from chlorinated biphenyls. These results show that these gene products are functional in both biphenyl and polychlorinated biphenyls degradation.

Alcohol Oxidoreductases↗
PubMed1994

Loss of phosphatidylserine synthesis results in aberrant solute sequestration and vacuolar morphology in Saccharomyces cerevisiae.

Null cho1 mutants of Saccharomyces cerevisiae are incapable of phosphatidyl-serine synthesis. They were more susceptible than wild-type strains to 100 mM CaCl2, 3 mM ZnCl2 or 1 mM MnCl2, but not to MgCl2 nor KCl. They were also susceptible to high concentrations of basic amino acids, L-lysine and L-arginine, and to an L-lysine analog, S-2-aminoethyl-L-cysteine. Their vacuolar pools of amino acids, especially those of basic ones, were decreased. Pigmentation of cho1 ade2 double mutants was obscured and vacuoles of cho1 mutants were considerably fragmented. These indicate that phosphatidylserine plays vital roles in normal vacuolar function and morphogenesis.

CDPdiacylglycerol-Serine O-Phosphatidyltransferase↗
PubMed1994

Electrochemically active DNA probes: detection of target DNA sequences at femtomole level by high-performance liquid chromatography with electrochemical detection.

Electrochemically active DNA probes were prepared by linking a ferrocene unit with 5'-aminohexyl-terminated oligonucleotides. The DNA sequences of probes 5a, 5b, and 5c were 5'-T12-3', 5'-T20-3', and 5'-TGCAG TTCCG GTGGC TGATC-3', respectively. Probe 5a could form a complex selectively with a single-strand poly(A) and a double-strand DNA fragment containing an A13 sequence and these complexes could be detected at femtomole levels by an electrochemical detector (ECD) on HPLC. The observed ECD response was proportional to the amount of the complex over the range 20-100 fmol. Probe 5c was capable of detecting femtomole levels of a restriction DNA fragment having oncogene v-myc. Moreover, probe 5b was able to detect picogram levels of mRNA taken from rat brain or yeast total cellular RNA. This proves that the electrochemically active DNA probes are useful in analyzing traces of DNA and RNA carrying the complementary sequence.

Base Sequence↗
PubMed1994

The prosequence of Rhizopus niveus aspartic proteinase-I supports correct folding and secretion of its mature part in Saccharomyces cerevisiae.

Extracellular Rhizopus niveus aspartic proteinase-I (RNAP-I) was secreted effectively by Saccharomyces cerevisiae when RNAP-I with its preprosequence was synthesized in this organism (Horiuchi, H., Ashikari, T., Amachi, T., Yoshizumi, H., Takagi, M., and Yano, K. (1990) Agric. Biol. Chem. 54, 1771-1779). Certain deletions (delta pro, delta 1, delta 2), and amino acid substitutions (M1) in the prosequence blocked secretion of RNAP-I, although the protease protection assay revealed that even delta pro could be translocated across the membrane of the endoplasmic reticulum. When delta pro or M1 was synthesized simultaneously with the wild-type preprosequence in S. cerevisiae, secretion of RNAP-I was recovered. Therefore, the physical linkage of the prosequence to the mature region is not a prerequisite for secretion of active RNAP-I. Purified RNAP-I with the prosequence once denatured in 6 M guanidine HCl could be renatured and activated to have its enzymatic activity by removing guanidine HCl in vitro, but RNAP-I without the prosequence could not. Furthermore, the wild-type prosequence helped the recovery of the activity of the denatured RNAP-I in trans, but the prosequences of M1 with which secretion of RNAP-I was not observed in vivo, did not. From these results we concluded that the prosequence of RNAP-I supports correct folding of RNAP-I in the endoplasmic reticulum lumen and its subsequent secretion in S. cerevisiae. The functional role of the prosequence of an aspartic proteinase was elucidated.

Amino Acid Sequence↗
PubMed1994

Modification by cyclopiazonic acid and ryanodine of depolarization-induced constriction in rat mesenteric artery.

Cyclopiazonic acid (53 or 159 nmol/min) or ryanodine (53 or 530 nmol/min) was applied to perfused rat mesenteric artery contracted with 40 mM K+ and 0.1 mM Ca2+. Both agents transiently elevated the perfusion pressure. The transient pressor response to caffeine observed after ryanodine was depressed more than after cyclopiazonic acid. This suggests that ryanodine increased the constriction through acceleration of Ca2+ release while cyclopiazonic acid increased it by inhibiting Ca2+ uptake into Ca2+ stores. In the continued presence of ryanodine, the next depolarization-dependent constriction was greatly depressed, suggesting that Ca(2+)-induced Ca2+ release was involved in the constriction.

Animals↗
PubMed1994

Highly sensitive detection of viral RNA genomes in blood specimens by an optimized reverse transcription-polymerase chain reaction.

A protocol was developed for a highly sensitive detection of viral RNA in blood specimens by reverse transcription coupled with a nested polymerase chain reaction. Using Japanese encephalitis virus (JEV) as a model, the optimized reverse transcription-polymerase chain reaction (ORTPCR) detects as few as 3-5 virions in 0.1 ml of whole blood specimens. The effectiveness of this assay system is confirmed by diagnosis of human hepatitis C viral (HCV) infection.

Animals↗
PubMed1994

Developmental competence of bovine oocytes frozen at different cooling rates.

Experiments were conducted to determine the optimal cooling conditions for improving the developmental competence of in vitro-matured bovine oocytes when frozen in 1.6 M 1,2-propanediol. Bovine oocytes were cooled from 0 degree to -5.5 degrees C at 1 degree C/min, seeded, and then cooled to -30 degrees C at different cooling rates (0.3 degree, 0.6 degree or 0.9 degree C/min) and then plunged into LN2. When frozen-thawed oocytes were fertilized in vitro, the proportions of fertilization and developmental competence did not differ among the three groups frozen at different cooling rates. The findings indicated that a cooling rate of less than 1.0 degree C/min in the freezing procedure did not affect the developmental competence of postthaw in vitro-matured bovine oocytes.

Animals↗
PubMed1994

Postthaw viability of the inner cell mass of in vitro-matured/in vitro-fertilized bovine embryos frozen in various cryoprotectants.

A study was conducted to examine the viability of inner cell mass (ICM) cells of frozen-thawed in vitro-matured (IVM)/in vitro-fertilized (IVF)-derived embryos using various cryoprotectants. Expanded blastocysts were frozen and thawed in 1.4 M glycerol with 0.25 M sucrose (GL), 1.6 M propylene glycol (PG), 1.8 M ethylene glycol (EG), or 1.3 M ethylene glycol monomethyl ether (EME) as cryoprotectants using a one-step method. After thawing, the embryos were cocultured for 24 h with cumulus cells in TCM199. Embryos which were viable after thawing and developed beyond the blastocyst stage were treated by immunosurgery and differential fluorochrome staining for ICM cell counts. Overall, there were no significant differences in the development to blastocyst stage after 24 h culture in each cryoprotectant (P < 0.05, chi 2 analysis). The viability of ICM cells of frozen-thawed embryos with each cryoprotectant was lower (GL, 72.7%; PG, 67.8%; EG, 77.5%; EME, 74.7%) than that of unfrozen embryos (84.4%). In the case of PG as a cryoprotectant, viability of ICM cells was significantly lower than that of unfrozen embryos (P < 0.05, ANOVA analysis). Our results suggest that the viability of ICM cells of frozen-thawed bovine embryos tend to be lower than that of unfrozen embryos irrespective of the cryoprotectants used. PG was significantly more toxic to the ICM cells compared with the other cryoprotectants.

Animals↗