Biomedical subjects

M Kato

Publications and source records attributed to M Kato.

At least 73 records · Page 4Linked to original sources

PubMed2003

Discovery of temperature-dependent phenomena of muon-catalyzed fusion in solid deuterium and tritium mixtures.

A systematic experimental study on muon-catalyzed fusion was conducted using a series of solid deuterium and tritium mixtures. A variety of conditions were investigated, i.e., tritium concentrations from 20% to 70%, and temperatures from 5 to 16 K. With decreasing temperature, we observed an unexpected decrease in the muon cycling rate (lambda(c)) and an increase in the muon loss probability (W). The origins of these observed changes were interpreted by the temperature-dependence in the dt mu formation process for lambda(c) and that in the muon reactivation process after muon-to-alpha sticking for W.

Journal Article↗

PubMed2003

Soluble soybean fiber: a 3-month dietary toxicity study in rats.

Soluble soybean fiber (SSF) is a food ingredient intended for human consumption. SSF was administered in the diet to Sprague-Dawley CD(R) rats at concentrations up to 40,000 ppm for three months. Unformed stool was detected during the early and middle part of the treatment period and was considered an exaggeration of a normal physiological response to the fibre content in the diets, to which the animals appeared to adapt. This finding has been reported with other water-soluble fibres and was not considered an adverse effect. Decreased weight gain and food intake during the first half of the treatment period are possible sequelae of increased intestinal throughput. Adaptation was indicated by subsequently improved weight gain and food consumption. Decreased serum cholesterol occurred in males receiving 30,000 or 40,000 ppm and this has been reported before in rats fed soluble fibre. Haemoconcentration (indicated by increased erythrocyte count, haematocrit and haemoglobin concentration) and decreased spleen weight are likely related to minor fluid imbalances during exposure to high concentrations of dietary fibre and occurred at all SSF concentrations. The spleen was microscopically normal. In conclusion, the no-observed-adverse-effect level (NOAEL) for SSF in this study was 40,000 ppm (equivalent to 2.43 g/kg bodyweight/day for males and 2.91 g/kg bodyweight for females).

Adaptation, Physiological↗

PubMed2003

Intravitreal injections of neurotrophic factors and forskolin enhance survival and axonal regeneration of axotomized beta ganglion cells in cat retina.

Some retinal ganglion cells in adult cats survive axotomy for two months and regenerate their axons when a peripheral nerve is transplanted to the transected optic nerve. However, regenerated retinal ganglion cells were fewer than 4% of the total retinal ganglion cell population in the intact retina. The present study examined the effects of intravitreal injections of neurotrophic factors (brain-derived neurotrophic factor, ciliary neurotrophic factor, basic fibroblast growth factor, glial cell-derived neurotrophic factor, neurotrophin 4), first on the survival of axotomized cat retinal ganglion cells within 2 weeks, and then on axonal regeneration of the retinal ganglion cells for 2 months after peripheral nerve transplantation. We tested first enhancement of the survival by one of the factors, and then one or two of them supplemented with forskolin, which increases intracellular cAMP. Single injections of 0.5 microg or 1 microg brain-derived neurotrophic factor, 1 microg ciliary neurotrophic factor, or 1 microg glial cell-derived neurotrophic factor significantly increased total numbers of surviving retinal ganglion cells; 1.6-1.8 times those in control retinas. Identification of retinal ganglion cell types with Lucifer Yellow injections revealed that the increase of surviving beta cells was most conspicuous: 2.5-fold (brain-derived neurotrophic factor) to 3.6-fold (ciliary neurotrophic factor). A combined injection of 1 microg brain-derived neurotrophic factor, 1 microg ciliary neurotrophic factor, and 0.1 mg forskolin resulted in a 4.7-fold increase of surviving beta cells, i.e. 50% survival on day 14. On the axonal regeneration by peripheral nerve transplantation, a combined injection of brain-derived neurotrophic factor, ciliary neurotrophic factor, and forskolin resulted in a 3.4-fold increase of beta cells with regenerated axons. The increase of regenerated beta cells was mainly due to the enhancing effect of neurotrophic factors on their survival, and possibly to a change of retinal ganglion cell properties by cAMP to facilitate their axonal regeneration.

Animals↗

PubMed2003

Inhibitory effect of titanium particles on osteoclast formation generated by treatment of mouse bone marrow cells with PGE2.

OBJECTIVE: The present study was designed to evaluate the effect of titanium (Ti) particles with no endotoxin on osteoclast differentiation and osteoclast activity in in vitro experiments. METHODS: Osteoclast formation as well as osteoclastic bone resorbing activity were examined using the mouse bone marrow culture system and purified rabbit osteoclasts treated with Ti particles (2.5-20 microgram cm-2). RESULTS: Ti particles, with no adherent endotoxin, inhibited osteoclastogenesis and receptor activator of NF-kappaB ligand (RANKL) expression in bone marrow cells treated with prostaglandin E2 (PGE2) (100 nM). The inhibitory effect of Ti particles was concentration-dependent (5-20 microgram cm-2), and was observed only on the generation of osteoclasts by PGE2, but not by 1,25-dihydroxyvitamin D3 or soluble RANKL. This suggests that Ti particles did not act uniformly on a common process in the generation of osteoclasts, but specifically on signal transduction for PGE2 in generating osteoclasts. In highly purified osteoclasts, Ti particles showed no effect on survival and bone resorbing activity. CONCLUSION: Ti particles inhibited osteoclast differentiation and RANKL expression in mouse bone marrow cells treated with PGE2, without affecting mature osteoclast survival or activity. Thus, Ti particles may alter the osteoclastogenetic action of PGE2, which is one of the regulatory factors of bone remodeling.

Animals↗

PubMed2003

Protein phosphatase 2A-linked and -unlinked caspase-dependent pathways for downregulation of Akt kinase triggered by 4-hydroxynonenal.

We studied the signal pathways for regulation of serine/threonine protein kinase Akt in Jurkat cells that had been treated with 4-hydroxynonenal (HNE) for caspase-dependent apoptosis induction. Treatment of cells with HNE led to a decrease in the level of Akt activity due to the dephosphorylation at Ser473, a major regulatory phosphorylation site. HNE-mediated dephosphorylation of Akt was prevented by a protein phosphatase 2A (PP2A) inhibitor, okadaic acid, and by a caspase-3 inhibitor, DEVD-CHO. HNE treatment resulted in an increase in the total level of PP2A activity, release of active tyrosine-dephosphorylated PP2A from the cytoskeleton and PP2A-Akt association, which were all dependent on caspase-3 activation. These results suggest that the level of PP2A activity is at least in part determined by its tyrosine phosphorylation, which is dually controlled by okadaic acid-sensitive phosphatases and protein-tyrosine kinases. Possibly underlying the mechanism of caspase-mediated activation of PP2A, HNE treatment resulted in downregulation of the activity of Src kinase, as a representative caspase-sensitive kinase to phosphorylate PP2A at tyrosine. In addition, activated caspase-3 partially cleaved Akt at a late stage of the apoptosis. These results indicate the existence of two distinct caspase-dependent signal pathways for downregulation of Akt that works as a mechanism of positive feedback regulation for HNE-triggered apoptotic signals.

Aldehydes↗

PubMed2003

Inactivation of the E3/LAPTm5 gene by chromosomal rearrangement and DNA methylation in human multiple myeloma.

Chromosomal band 1p34-36 is a commonly rearranged locus in many types of cancers. We cloned the breakpoint region of a chromosomal translocation, t(1;14)(p34;q32), found in the human multiple myeloma (MM) cell line, ODA. This rearrangement occurred between the nearby switch region of the immunoglobulin heavy chain (IgH) gene (Sgamma3) at 14q32 and the first intron of the human retinoic acid-inducible E3 protein (E3)/lysosome-associated protein, transmembrane-5 (LAPTm5) gene at the 1p34 locus. Consequently, the E3 gene, which is a hematopoietic cell-specific transcript induced by retinoic acid and located at the rearranged allele, was interrupted within its coding region and was not expressed in the ODA cell line in spite of the other allele still being intact. The expression derived from the remaining intact allele in ODA cells was silenced by DNA methylation at sequences within the first intron around a GC-rich EagI site. Interestingly, the silenced expression of E3 mRNA due to DNA methylation of intron 1 sequences was frequently encountered in MM cells [6/10 (60%) of MM cell lines tested], while E3 is expressed in normal plasma cells and in most other hematopoietic cell lines including those of B-cell lineage. Thus, as the E3 protein has been suggested to be involved in cellular differentiation and apoptotic pathways in certain cell types, our results suggest that loss of E3 gene expression might be a crucial event during the progression of human MM.

Alleles↗

PubMed2003

A new and simple method for evaluating masticatory function using newly developed artificial test food.

The aim of this study was to develop an objective evaluation system for the masticatory function. This system used paraffin wax cubes as a test food, which had six red- and green-coloured layers so that each of the six surfaces showed a pseudo-checkered pattern. A total of 100 paraffin cubes were chewed by 37 subjects and the images of these samples were captured and analysed using a digital image analyzer. With regard to the colour and the shape of each sample, five parameters were obtained. Furthermore, an independent examiner graded the degree of colour mixing in the chewed samples into three groups (poor, medium and good) by visual inspection. A discriminant analysis was performed using the five variables as predictors of two groups (good and poor). Mixing Ability Index (MAI) was calculated from the discriminant function and using this index, 97% of the samples from these two groups were classified correctly. This system needed only a few minutes to complete and is easy to use. Therefore, it has high potentials for clinical use.

Adult↗

PubMed2003

Validity and reliability of a newly developed method for evaluating masticatory function using discriminant analysis.

The objective of the study was to assess validity and reliability of a newly developed method for evaluating mixing ability of masticatory function. A two-coloured paraffin wax cube was used as a test food in the mixing ability test. Eleven full dentate and 33 denture wearers participated in the validity assessment. They were divided into three groups according to their dental state. Validity was assessed by the Spearman's coefficient of correlations between the mixing ability test and the sieving method used as a 'gold standard' test of the masticatory performance. The subjects were asked to masticate the test foods for 5, 7, 10, 15, 20 and 30 strokes in each test. Significant correlations (P < 0.001) were obtained in natural dentition group (r(s) = 0.66), in denture-natural dentition group (r(s) = 0.72) and in denture-denture group (r(s) = 0.56). In the reliability assessment, three full dentate subjects were asked to repeat the mixing ability test a number of times. The intraclass correlation coefficients were 0.94 in interexaminer consistency, 0.98 in intra-examiner consistency, 0.89 in test-retest consistency and 0.99 in measuring consistency. These results indicated that the mixing ability test had the validity and the reliability for evaluation of the masticatory performance.

Adult↗

PubMed2003

Influence of working side contacts on masticatory function for mandibular distal extension removable partial dentures.

The aim of this study was to clarify the influence of working side contacts for masticatory function for a distal extension removable partial denture. Five subjects who had edentulous arches from second premolar to second molar opposing natural teeth participated. Working side contacts were altered by using three types of artificial teeth attached to the denture base. A-form teeth made contact with opposite teeth while acting as the working side in a lateral excursion. The cusp angles of B- and C-form teeth were decreased by 10 degrees and 20 degrees, respectively compared with A-form teeth. B-and C-form teeth discluded with opposite teeth on the working side. Subjects were asked to perform two kinds of masticatory performance test. Obtained data were evaluated by the repeated-measures anova and the Tukey test for multiple comparisons. Results revealed that there was a significant difference (P=0.001) in the three types of teeth in the mixing ability test and the value of A-form teeth was statistically less value than those of the other teeth. However, there was no significant difference in the comminuting ability test. These results suggested that working side contacts between artificial teeth and opposite natural teeth influenced mixing ability, but not comminuting ability.

Adult↗

PubMed2003

Effects of activator on masticatory muscle activity during daytime and sleep.

The purpose of this study was to investigate masticatory muscle activity with and without the use of an activator during daytime and sleep, and further to focus on the changes in muscle activity produced by the daytime use. The subjects in this study were 10 healthy males (mean age: 27.6 years). A portable electromyogram (EMG) recording device was used to record the activity from the right temporal, masseter and digastric muscles. After recording, the integrated EMG values (microV s) were measured. The muscle activity was lower during sleep than during daytime, irrespective of the use of the activator. In sleep-time, temporal and digastric muscle activity was significantly decreased, although masseter muscle activity presented no significant differences. With the activator in use, the digastric muscle activity tended to increase in comparison with the elevator muscles during daytime and sleep. Although the activity of both elevator muscles was diminished by use of the activator during sleep in all subjects, some subjects showed an increase during daytime. These results suggested that the activator should be used, if possible, not only during sleep, but also during daytime and clenched on consciously to obtain the adaptation and development of the masticatory muscles for the 're-training of the muscles' at a new favourable mandibular position.

Adult↗

PubMed2003

Characterization of AnRP-mediated negative regulation of the xylanase gene, cgxA, from Chaetomium gracile in Aspergillus nidulans.

AIM: In vivo regulatory features of AnRP, a repressor for the cgxA gene, were characterized. METHODS AND RESULTS: Titration of AnRP by introducing multiple copies of its specific binding sequence 'TTGACAAAT' into an Aspergillus nidulans strain containing the Chaetomium gracile cgxA gene enhanced the cgxA gene expression. AnRP functions independently of and cooperatively with CreA to modulate the cgxA gene expression. CONCLUSIONS: AnRP is a CreA-independent negative regulatory factor controlling the cgxA expression. SIGNIFICANCE AND THE IMPACT OF THE STUDY: Xylanases of filamentous fungi have received increased interest because of their potential biotechnological applications. Elucidation of the factors involved in the regulation of the xylanolytic genes in fungi will help to increase levels of xylanase production.

Amylases↗

PubMed2003

Plural transformation-processes from spiral to coccoid Helicobacter pylori and its viability.

OBJECTIVES: Helicobacter pylori (H. pylori), present in a half of the world's population, is a very successful pathogen. The infection by this bacterium causes several gastric diseases in human. H. pylori is morphologically divided into two types; a spiral and a coccoid form. Both types are observed in human stomach. Although the former is converted into the latter in vitro, the process of coccoid formation remains obscure. Furthermore, whether coccoid forms possess viability arouses much controversy among scientists. We investigated both the process of coccoid formation by electron microscopy and the viability of coccoid H. pylori. METHODS: A laboratory strain, ATCC43504, was cultured in liquid medium (Brucella Broth medium with 10% heat inactivated horse serum) for seven days. In each culture day, the organisms were observed by scanning-, conventional transmission- and immuno-electron microscopy and were simultaneously examined the culturability of H. pylori to identify the viability of coccoid form. RESULTS: As the days went by, spiral forms were replaced by coccoid forms in each medium which possessed culturability to some degree until the 4th day. By the detailed observation of ultrastructural features, coccoid forms were classified into two types on the ground that represents different transformation-processes and distinctive ultrastructures. One was the coccoid form that we named Type A with an irregularly surface- and intracytoplasmic-structure which adhered to one another. The other was Type B having a smooth surface with flagella coiled around its own body and the strictly membranous structure. This type was not adhered to another organism. In later days, each type came to be similar external structure and lost the culturability. CONCLUSIONS: The coccoid forms of H. pylori can be classified into two types by electron microscopy which represent different transformation-processes and consist of the dying bacteria, the living ones with culturability and the viable but non-culturable ones.

Culture Media↗

PubMed2003

Head and neck cancer arising after endoscopic mucosal resection for squamous cell carcinoma of the esophagus.

BACKGROUND AND STUDY AIMS: It is well known that patients with head and neck cancer often have synchronous or metachronous squamous cell carcinoma of the esophagus. However, the prevalence of subsequent head and neck cancer in patients with early-stage esophageal cancer is still unknown. The aims of this study were to analyze the frequency of metachronous head and neck cancer after endoscopic mucosal resection (EMR) for esophageal cancer and to investigate whether minute iodine-unstained areas, often associated with squamous cell carcinomas, would be an index for metachronous head and neck cancer. PATIENTS AND METHODS: 99 patients with esophageal squamous cell carcinoma who underwent EMR were studied. Based on the iodine-staining pattern at initial EMR, they were categorized into those with uniform (group U) and scattered (group S) types of background mucosa. Patients were monitored endoscopically and otolaryngologically (group U, median 46 months, range 12-83 months; group S, median 44 months, range 13-80 months). RESULTS: In total, 5/99 patients (5.1 %) were found to have metachronous head and neck cancer during the follow-up, including 4/20 patients (20 %) in group S. In three cases laryngeal or hypopharyngeal cancer was found by endoscopic examination. The cumulative proportion of metachronous head and neck cancer-free subjects was significantly lower in group S than group U (P = 0.0007). CONCLUSIONS: Among patients who undergo EMR for esophageal carcinoma, those with scattered-type iodine staining of the background mucosa have an increased risk of metachronous head and neck cancer, and should therefore be closely observed. Careful endoscopic observation led to early detection of laryngeal and hypopharyngeal cancer.

Aged↗

PubMed2003

Resource use of insect seed predators during general flowering and seeding events in a Bornean dipterocarp rain forest.

Insect seed predators of 24 dipterocarp species (including the genera ot Dipterocarpus, Dryobalanops and Shorea) and five species belonging to the Moraceae, Myrtaceae, Celastraceae and Sapotaceae were investigated. In a tropical lowland dipterocarp forest in Sarawak, Malaysia, these trees produces seeds irregularly by intensely during general flowering and seeding events in 1996 and/or 1998. Dipterocarp seeds were preyed on by 51 insect species (11 families), which were roughly classified into three taxonomic groups: smaller moths (Trotricidae, Pyralidae, Crambidae, Immidae, Sesiidae, and Cosmopterigidae), scolytids (Scolydae) and weevils (Curdulionidae, Apionidae, Anthribidae, and Attelabidae). Although the host-specificity of invertebrate seed predators has been assumed to be high in tropical forests, it was found that the diet ranges of some insect predators were relatively wide and overlapped one another. Most seed predators that were collected in both study years changes their diets between general flowering and seeding events. The results of cluster analyses based on the number of adult of each predator species that emerged from 100 seeds of each tree species, suggested that the dominant species was not consistent, alternating between the two years.

Animals↗

PubMed2003

High-level beta-lactam resistance associated with acquired multidrug resistance in Helicobacter pylori.

Four clinical Helicobacter pylori isolates with high-level resistance to beta-lactams exhibited low- to moderate-level resistance to the structurally and functionally unrelated antibiotics ciprofloxacin, chloramphenicol, metronidazole, rifampin, and tetracycline. This pattern of multidrug resistance was transferable to susceptible H. pylori by natural transformation using naked genomic DNA from a clinical multidrug-resistant isolate. Acquisition of the multidrug resistance was also associated with a change in the genotype of the transformed multidrug-resistant H. pylori. DNA sequence analyses of the gene encoding penicillin binding protein 1A (PBP 1A) showed 36 nucleotide substitutions resulting in 10 amino acid changes in the C-terminal portion (the putative penicillin binding domain). Acquisition of beta-lactam resistance was consistently associated with transfer of a mosaic block containing the C-terminal portion of PBP 1A. No changes of genes gyrA, rpoB, rrn16S, rdxA, and frxA, and nine other genes (ftsI, hcpA, llm, lytB, mreB, mreC, pbp2, pbp4, and rodA1) encoding putative PBPs or involved in cell wall synthesis were found among the transformed resistant H. pylori. Antibiotic accumulations of chloramphenicol, penicillin, and tetracycline were all significantly decreased in the natural and transformed resistant H. pylori compared to what was seen with susceptible H. pylori. Natural transformation also resulted in the outer membrane protein profiles of the transformed resistant H. pylori becoming similar to that of the clinical resistant H. pylori isolates. Overall, these results demonstrate that high-level beta-lactam resistance associated with acquired multidrug resistance in clinical H. pylori is mediated by combination strategies including alterations of PBP 1A and decreased membrane permeability.

Amino Acid Sequence↗

PubMed2003

Immunohistochemical localization of truncated midkine in developing human bile ducts.

Midkine (MK) is a heparin-binding growth factor whose gene has been identified in embryonal carcinoma cells in early stages of retinoic acid-induced differentiation. In the present study, we investigated the developmental localization of truncated MK protein in human bile ducts. Thirty specimens of the livers from 25 fetuses (from 9 to 40 gestational weeks) and from five neonates less than 4 weeks old were examined. Immunohistochemical analysis was performed using a mouse IgG2b monoclonal antibody against recombinant-truncated MK. Truncated MK was expressed moderately in the fetal liver from 9 to 15 gestational weeks. The immunoreactivities were found in the primitive hepatocytes, ductal plates, migrating biliary cells and immature bile ducts. The reaction products were localized in the cytoplasm heterogeneously. The intensity of immunostaining was weak from 15 gestational weeks to 26 gestational weeks. After 27 gestational weeks, truncated MK was not detected in the fetal livers. It was suggested that primitive hepatocytes, ductal plates and immature bile ducts produced truncated MK transiently during human bile ducts development.

Bile Ducts↗

PubMed2003

[Stent-graft implantation for the patient with ruptured acute aortic syndrome: report of a case].

We report a ruptured case of acute aortic syndrome and a successful treatment with transcatheter placed stent-graft. A 67-year-old man underwent a stent-graft implantation for the patient with ruptured acute aortic syndrome. The patient admitted in our institute for a diagnosis of ruptured acute aortic dissection. We planned to operate a graft replacement for distal arch aorta. But he was complicated with right-side monoplesia before the operation. Then we performed a stent-graft implantation in order to avoid the usage of extra-corporeal circulation. The implantation of the stent-graft was successful and shrinkage of the hematoma around the ruptured aorta was documented on the computed tomography of 7 post-operative day.

Acute Disease↗

PubMed2003

[Coronary artery aneurysm developed acute myocardial infarction: report of a case].

A 68-year-old woman without angina developed acute antero-septal myocardial infarction. Coronary angiogram revealed saccular coronary artery aneurysm at the origin of the diagonal branch and relatively mild coronary artery stenosis. Emboli from the coronary aneurysm was strongly suggested. We placed coronary bypass grafts onto left anterior descending, diagonal and obtuse marginal branches, and excluded the coronary aneurysm by ligating both its inflow and outflow. The postoperative course was uneventful. There are several treatments of choice for patients with coronary aneurysm. We believe that surgery is mandatory and that exclusion of the coronary aneurysm should be considered in every possible case.

Aged↗