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Biomedical subjects

T Kikuchi

Publications and source records attributed to T Kikuchi.

At least 325 records · Page 18Linked to original sources
PubMed1995

Thermostable chimeric PQQ glucose dehydrogenase.

The thermal stability of PQQ glucose dehydrogenases (PQQGDHs) which were chimeras with more than 95% made up of the N-terminal region of Escherichia coli PQQGDH and the rest made up of the C-terminal region of Acinetobacter calcoaceticus PQQGDH was investigated. Among the chimeric PQQGDHs, E97A3 (E. coli 97% and A. calcoaceticus 3%) and E95A5 were found to possess higher thermal stability than parental E. coli PQQGDH. Further detailed characterization of the thermal stability was carried out, focusing on E97A3. E97A3 showed a more than 3-fold and 12-fold increase in half life time at 40 degrees C, compared with the PQQGDHs of E. coli and A. calcoaceticus, respectively. Using transition state theory, the increase in the free energy of inactivation observed in E97A3 was compared with those of the E. coli and A. calcoaceticus parental enzymes. The region responsible for this stabilization was also discussed.

Acinetobacter calcoaceticus↗
PubMed1995

Single cell monitoring of growth arrest and morphological changes induced by transfer of wild-type p53 alleles to glioblastoma cells.

Mutation of the p53 tumor suppressor gene is one of the earliest identified genetic lesions during malignant progression of human astrocytomas. To assess the functional significance of these mutations, wild-type (WT) p53 genes were introduced into glioblastoma cell lines having mutant, WT, or null endogenous p53 alleles. Populations of cells with mutant or null endogenous p53 alleles and exogenous WT p53 were spontaneously selected in culture for cells expressing only mutant p53 or no p53, which then displayed a growth and tumorigenic phenotype identical to the parental cells. To determine the phenotypic consequences of WT p53 expression before the occurrence of mutations, we developed a single cell assay to monitor WT p53-dependent transcription activity. Transfer and expression of exogenous WT p53 genes to cells with endogenous mutant or deleted, but not WT, p53 alleles caused growth arrest and morphological changes, including increased cell size and acquisition of multiple nuclei. This supports the hypothesis that genetic lesions of the p53 gene play an important role in the genesis of astrocytomas. Furthermore, the high sensitivity of the episomal single cell reporter strategy developed here has potential clinical applications in the rapid screening of patients for germ-line mutations of the p53 gene or any other gene with known targets for transcriptional transactivation.

Alleles↗
PubMed1995

Gap junctions in the rat cochlea: immunohistochemical and ultrastructural analysis.

Gap junctions in the rat cochlea were investigated using immunostaining for connexin26 and transmission electron microscopy. Electron microscopy of normal and pre-embedded immunostained material showed that there were gap junctions between and among all cells that light microscopy showed to have immunostained appositions. Light microscopy showed immunostaining between and among cell types that electron microscopy showed to be joined by gap junctions. Immunostaining for connexin26 was therefore taken as providing a reasonable approximation of the locations of gap junctions throughout the cochlea and was used to provide an overview of the extent of those locations. Cells interconnected via gap junctions fell into one of two groups. The first group consists of nonsensory epithelial cells and includes interdental cells of the spiral limbus, inner sulcus cells, organ of Corti supporting cells, outer sulcus cells, and cells within the root processes of the spiral ligament. The second group consists of connective tissue cells and includes various fibrocyte types of the spiral limbus and spiral ligament, basal and intermediate cells of the stria vascularis, and mesenchymal cells which line the scala vestibuli. The present work represents a first attempt towards a description of how serial gap junctions among cochlear cells reflect a level of organization of the tissue. The organization described here, together with a great deal of information from previous investigators, suggest that serially arranged gap junctions of both epithelial and connective tissue cells serve as the structural basis for recycling endolymphatic potassium ions that pass through the sensory cells during the transduction process.

Animals↗
PubMed1995

Feasibility of in vitro culturing of lesional psoriatic keratinocytes in medium containing high calcium concentrations.

Lesional psoriatic keratinocyte (LPK) culture is considered to be difficult under high-Ca2+ conditions in the absence of special proliferative agents. Using a permeable collagen membrane, we obtained a culture of LPKs under high-Ca2+ conditions without any special proliferative agents. Single-cell suspensions were prepared from the epidermis of chronic psoriatic plaques. Cells were inoculated on the collagen membrane suspended slightly above the bottom of a Petri dish. We used a culture medium of Eagle's MEM containing 10% fetal calf serum. LPKs attached to the membrane 12 h after inoculation and gradually spread. They reached a confluent state by the 10th day of culture. We measured the concentrations of TGF alpha and IL-6 in the medium of LPKs, and compared these with the concentrations in normal keratinocyte (NK) cultures. Significantly increased secretion of TGF alpha by LPKs was observed during the initial phase but this secretion subsequently decreased. Concentrations of IL-6 were below the detectable level in both of NKs and LPKs throughout the observation period. Our results demonstrate that cultured LPKs under high-Ca2+ conditions secrete a larger amount of TGF alpha but not IL-6. Our cell culture system, which allows LPKs to spread and stratify, contributes to the study of the pathogenesis of psoriasis.

Adult↗
PubMed1995

Does hypoplasia of one pulmonary artery preclude a definitive repair in pulmonary atresia, intact ventricular septum, and hypoplastic right ventricle?

Twins with pulmonary atresia, intact ventricular septum, and hypoplastic right ventricle associated with underdeveloped and discontinuous left pulmonary artery are described. Operations to connect the left pulmonary artery to the main pulmonary trunk, with subsequent biventricular repair assisted by bidirectional cavopulmonary anastomosis and atrial fenestration were performed. Follow-up catheterization proved spontaneous closure of the fenestration in one patient. Both patients have been in a satisfactory condition for 3 years since operation.

Anastomosis, Surgical↗
PubMed1995

Tissue-selective inhibition of sterol synthesis in mice by pravastatin sodium after a single or repeated oral administrations.

Pravastatin, an inhibitor of 3-hydroxy-3-methylglutaryl CoA (HMG-CoA) reductase, exhibits liver-selectivity in inhibiting sterol synthesis, when administered as a single oral dose to mice or rats, whereas lovastatin and simvastatin do not. This may be due to the fact that pravastatin is distributed intracellularly, to a large extent, in the liver and extracellularly in nonhepatic tissues. In the present study, we examined whether the difference in liver-selectivity among these three HMG-CoA reductase inhibitors observed in single-dose studies was preserved after repeated oral administrations of drugs to mice. De novo sterol synthesis in different tissues of mice was examined in vivo three hours after the last dose of drug by measuring incorporation of intraperitoneally injected [14C]acetate into total sterols. Pravastatin administered orally for 11 consecutive days at 5 and 10 mg/kg exhibited a greater liver-selectivity than lovastatin and simvastatin: sterol synthesis was inhibited more than 60% in the liver by all three drugs, whereas that in nonhepatic tissues was inhibited less than 10% by pravastatin and more than 30% by lovastatin and simvastatinin in most of the nonhepatic tissues examined. Pravastatin administered orally for 11 consecutive days at 10 mg/kg caused more selective inhibition of sterol synthesis in liver ex vivo than two other inhibitors at the same dose. Pravastatin inhibited de novo sterol synthesis from [14C]acetate into sterol fraction in the liver slices in vitro, but minimally in those of the spleen and testis, whereas lovastatin and simvastatin inhibited in those of all three tissues.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Lentinan augments skin reaction induced by bradykinin: its correlation with vascular dilatation and hemorrhage responses and antitumor activities.

The effects of lentinan, an antitumor polysaccharide, on vascular reactions against vasoactive mediators were investigated in murine systems. Lentinan augmented intradermal reactions against bradykinin. Induction of acute phase proteins (APP) and the vascular dilatation hemorrhage (VDH) reaction on the ears have been reported to reflect the host responses to lentinan. The strain difference in the intensity of skin reactions coincided with those observed in VDH responses and with lentinan-induced antitumor effects against Sarcoma 180. Augmentation of skin reactions was not observed in T-cell-deficient mice. Inhibitors of lipoxygenase, thrombin and plasmin which reduced skin reactions also decreased the incidence of tumor necrosis positive mice among FBL-3-bearing mice treated with lentinan. Furthermore, B10D2 mice treated with fluorouracl (5-FU) and lentinan 10 days after S908.D2 transplantation showed complete tumor regression and augmented skin reactions, whereas augmentation of skin reactions and tumor regression were not observed in mice treated with 5-FU and lentinan 32 days after tumor inoculation. Taken together, these results suggest that these vascular reactions might play crucial roles in antitumor effects of lentinan and that the skin reaction, the convenient method for investigating vascular reactions, is a promising tool to monitor host sensitivity to lentinan in antitumor responses.

Adjuvants, Immunologic↗
PubMed1995

Endoscopic ultrasound-guided pancreatography: a case report.

Endoscopic ultrasound-guided pancreatography was performed on a 48-year-old man with a diagnosis of pancreatic stone. A pylorus-preserving pancreaticoduodenectomy had been performed previously on this patient, approximately two years earlier, following the diagnosis of a tumor-forming pancreatitis. Endoscopic retrograde pancreatography and conventional ultrasound-guided percutaneous pancreatography had failed to yield a diagnosis. However, endoscopic ultrasound-guided pancreatography was performed successfully, delineating the pancreatic duct and a filling defect caused by intraductal calculi. Endoscopic ultrasound-guided pancreatography will be a potential alternative in cases when endoscopic retrograde pancreatography has failed or proved non-diagnostic.

Calculi↗
PubMed1995

Cytokine production in cerebrospinal fluid after subarachnoid haemorrhage.

Pathophysiological mechanisms for vasospasm after subarachnoid haemorrhage (SAH) remain unclear and, so far, roles of cytokines in vasospasm have not been known. In the present study, we measured interleukin-1 alpha (IL-1 alpha), interleukin-1 beta (IL-1 beta), interleukin-6 (IL-6), interleukin-8 (IL-8), and tumour necrosis factor-alpha (TNF-alpha) concentrations in the cerebrospinal fluid (CSF) of patients with subarachnoid haemorrhage (SAH). ELISA assay were performed on 21 CSF samples from 7 patients with SAH and on 4 sera samples. Both IL-6 and IL-8 were detected in all CSF samples, but IL-1 alpha, IL-1 beta, and TNF-alpha were not detected. IL-6 and IL-8 were also detected in sera, but at much lower concentrations. This study indicates that IL-6 and IL-8 may play roles as immunomodulators in patients with SAH. In addition, it has been reported that IL-6 inhibits prostaglandin I2 production and increases the mRNA level of c-sis gene, suggesting that IL-6 may play an important role in vasospasm as vasoconstrictor.

Aged↗
PubMed1995

Iron-regulated expression and membrane localization of the magA protein in Magnetospirillum sp. strain AMB-1.

The magA gene from Magnetospirillum sp. strain AMB-1 is required for the synthesis of bacterial magnetic particles (BMPs). This gene has been cloned, sequenced and found to encode a protein which is homologous to the Escherichia coli potassium efflux membrane-binding protein, KefC. By using the firefly luciferase gene (luc) cloned downstream of the magA promoter, the effect of iron on regulation of magA expression was investigated, and transcription of magA was found to be enhanced by low concentrations of iron. Intracellular localization of the MagA protein was studied using magA-luc fusion proteins. The luc gene was cloned downstream of the magA hydrophilic C-terminal domain. Detection of luciferase activity in the cytoplasm, cell membrane, and magnetic particle membrane subcellular fractions confirmed that the MagA fusion protein was localized in the cell membrane. The fusion protein was also detected on the surface of the lipid bilayer covering the magnetic particles. These results suggest that MagA is a membrane-bound protein, the expression of which is enhanced at low iron concentrations.

Amino Acid Sequence↗
PubMed1995

Influence of parental obesity on the physical constitution of preschool children in Japan.

The objective of this study was to assess the influence of parental obesity on the physical constitution of preschool children. A total of 3187 children aged between 1-6 years and their parents were studied. A child whose per cent obesity (%OB; per cent overweight for age, height and sex) was greater than 15%, and a parent whose body mass index (BMI; kg/m2) was greater than the 95th percentile were defined to be obese (27.40 and 25.97 for a father and a mother, respectively). We found that the incidence of obesity in children with obese fathers (11.5%) was significantly higher than in those with non-obese fathers (6.2%), and a similar difference was obtained between children with obese mothers (14.5%) and with non-obese mothers (6.2%), respectively. The incidence of obesity in children was 6.0% if both parents were non-obese; this incidence rose to 22.7% if one parent was obese, and to 30.8% if both were obese. The %OB of children was more markedly correlated with the mothers' BMI (r = 0.219) than the fathers' BMI (r = 0.165). The %OB of children correlated significantly with fathers' BMI, but only from the age of 3-6 years, whereas mothers' BMI correlated from the age of 1-6 years. We conclude that parental obesity was of significance in determining the development of juvenile obesity even in the preschool period.

Body Constitution↗
PubMed1995

Congenital hypothyroidism with delayed rise in serum TSH missed on newborn screening.

We report on a female patient with congenital hypothyroidism (CH) missed on a newborn screening test. She is now 10 years old with retarded development. The patient was born premature at 34 weeks of gestation with birth-weight of 1515 g, and was judged to be normal in the screening programme of Niigata Prefecture. However, she gradually suffered from poor weight gain and retarded development with stridor at breathing. Serum thyroid stimulating hormone (TSH) levels were rechecked and showed high values with normal T3 and T4 levels. She was referred to our hospital at the age of 13 months. She was diagnosed as having CH (ectopic thyroid) with a delayed rise in blood TSH concentration, probably due to the prematurity of the hypothalamic-pituitary-thyroid axis. L-thyroxine therapy brought a decline in TSH levels with partial improvement of her symptoms. Regardless of the result of newborn screening, infants with elevated serum TSH levels should be carefully examined for possible CH, even when T3, T4 and free T4 values are in the normal range.

Child↗
PubMed1995

Pharmacology of a non-selective ETA and ETB receptor antagonist, TAK-044 and the inhibition of myocardial infarct size in rats.

1. The aims of the present study were to characterize the pharmacological profile of a new endothelin (ET) receptor antagonist, TAK-044 and to consider whether it limits the extension of myocardial infarct size in rats. 2. Binding of [125I]-ET-1 to ET receptors on rabbit ventricular and cerebellar membrane fractions was inhibited by TAK-044 with IC50 values of 3.8 nM and 130 nM, respectively. 3. It inhibited ET-1, ET-2 and ET-3-induced vasoconstriction of porcine isolated coronary arteries in a competitive (ET-1, ET-2) and a non-competitive (ET-3) manner. 4. In the rat in vivo, the ET-1-induced blood pressure changes including transient hypotension followed by sustained hypertension, were inhibited by TAK-044 (0.1-10 mg kg-1, i.v.) in a dose-dependent manner. 5. Acute myocardial infarction induced by 1 h coronary occlusion followed by 24 h reperfusion in rats caused an infarct size of 60 +/- 2% (n = 12) of the area-at-risk by weight. 6. Intravenous injection of TAK-044 10 min before coronary occlusion reduced the infarct size in a dose-dependent manner: 32% and 54% reductions at 1 and 3 mg kg-1, respectively. 7. TAK-044 administered 10 min before or 1 h after reperfusion (1 mg kg-1, i.v.) showed similar inhibitory effects: 34% and 23% reductions, respectively. 8. We conclude that TAK-044 is an ETA/ETB receptor antagonist which shows strong inhibitory effects on the extension of myocardial infarct size after coronary artery occlusion-reperfusion in rats.

Animals↗
PubMed1995

A new inherited muscular disorder in Japanese quails (Coturnix coturnix japonica).

Thirteen adult mutant (LWC strain) Japanese quails (Coturnix coturnix japonica), between the ages of 8 and 60 weeks were examined for a progressive muscular disorder. The disorder, inherited as an autosomal dominant trait, was clinically apparent as early as 28 days of age; it was characterized by generalized myotonia, muscle stiffness, and muscle weakness. Affected birds were identified by their inability to lift their wings vertically upward and by their inability to right themselves when placed on their dorsum. Electromyographic studies in two mutant quails showed high-frequency repetitive discharges comparable to those of myotonic runs. These discharges persisted after nerve resection. The distinctive histopathologic changes in the various muscles examined were ring fibers, sarcoplasmic masses, and internal migration of sarcolemmal nuclei. A slight decrease in the size of type IIB muscle fibers and a slight increase in the size of type IIA fibers were observed in the M. pectoralis thoracicus of affected quails. In older affected birds, inter- and intrafascicular fatty infiltration with replacement of type IIB fibers by fat cells was seen in the pectoral muscles. Single fiber necrosis, nonspecific lymphorrages, and variations in the muscle fiber size and shape were also noted. The typical muscle lesions and multisystem involvement, which was manifested by testicular degeneration and atrophy in the male LWC specimens and bilateral lenticular cataracts in 6 of 13 affected mutant quails, suggest resemblance of this new inherited muscular disorder to myotonic dystrophy in man.

Animals↗
PubMed1995

Studies on metabolites of mycoparasitic fungi. IV. Minor peptaibols of Trichoderma koningii.

Three minor peptaibols, trichokonins (TKs)-Ia, Ib, and IX, were obtained from the culture broth of Trichoderma koningii Oudemans. Primary structures of these peptaibols were elucidated by ion-spray ionization mass spectrometry (ISI-MS) including the collision-induced dissociation (CID) technique together with two-dimensional nuclear Overhauser enhancement spectroscopy (NOESY).

Alamethicin↗
PubMed1995

Studies on metabolites of mycoparasitic fungi. II. Metabolites of Trichoderma koningii.

Four peptaibols, named trichokonins (TKs) V, VI, VII, and VIII, were isolated from the culture broth of Trichoderma koningii Oudemans. Primary structures of these peptaibols were elucidated by electrospray ionization mass spectrometry (ESI-MS), FAB-MS, and collision-induced dissociation (CID) techniques along with nuclear Overhauser enhancement spectroscopy (NOESY).

Alamethicin↗
PubMed1995

Cloning of the creatinine amidohydrolase gene from Pseudomonas sp. PS-7.

The gene encoding creatinine amidohydrolase (EC 3.5.2.10) was isolated from Pseudomonas sp. PS-7. The primary structure of creatinine amidohydrolase deduced from the nucleotide sequence showed that the protein is composed of 259 amino acids and has a molecular weight of 28,437. The enzymatic property of creatinine amidohydrolase produced by recombinant E. coli was identical with those by Pseudomonas sp. PS-7.

Amidohydrolases↗