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Biomedical subjects

T Tsuchiya

Publications and source records attributed to T Tsuchiya.

At least 109 records · Page 6Linked to original sources
PubMed2000

Studies on the mechanisms of tumorigenesis induced by polyetherurethane in rats: production of superoxide, tumor necrosis factor, and interleukin 1 from macrophages cultured on different polyetherurethanes.

Interaction of macrophages (Mos) with polyetherurethane (PEU) was investigated to clarify the role of the Mos in the early stage of tumorigenesis of PEUs. As for the inflammatory cytokines produced from Mos, the amount of tumor necrosis factor (TNF) produced on three PEUs (PU-4, 6, and 8) was similar, but less than that on a control glass dish. Interleukin 1 (IL-1) production levels on the PEUs, especially on PU-6, also decreased in comparison with the glass dish. Superoxide (O(2)(-)) release from Mos on the PEUs was similar or more than that on the glass dishes within 24 h incubation. In particular, the O(2)(-) release on PU-6, possessing the lowest tumorigenic potential in vivo, reached the highest level among the PEUs tested. To clarify the causes that enhanced O(2)(-) release from Mos, the methanol extracts of the three PEUs and chemicals that constitute the PEUs were tested. The extracts and 1,4-butanediol did not show an effect on O(2)(-) release. However, 4, 4'-di(ethoxycarboamide) diphenylmethane, a model hard segment of PEU, was remarkably enhanced, whereas poly(tetramethyleneoxide), a soft segment of PEU, reduced the O(2)(-) release in a dose-dependent manner. From these results, although it is still unclear what affects different types of O(2)(-) production, lower tumorigenic potentials of PU-6 may be caused by O(2)(-) release from Mos, which play an important role in the tumoricidal process. Further, the low IL-1 production on PU-6 suggests that PU-6 suppresses inflammatory responses other than O(2)(-) production in vivo, resulting in lower tumorigenic potentials. On the other hand, TNF production was almost similar when Mos were cultured on three PEUs, suggesting TNF did not play a role in the different tumorigenic potentials of PEUs.

Animals↗
PubMed2000

Chondro-osseous differentiation in fat tissue tumors: magnetic resonance imaging with pathological correlation.

Chondro-osseous differentiation of three benign or malignant fat tissue tumors--two chondrolipomas and a liposarcoma with cartilaginous metaplasia--was studied with magnetic resonance (MR) imaging and compared with their pathological findings. The results suggest that demarcation of cartilage tissue can be clearly defined on MR imaging when the size of the cartilaginous area is large. Myxoid matrix, degenerative fat tissue and lipodystrophic change may decrease the delineation of the cartilage tissue.

Biopsy↗
PubMed2000

A DEFICIENS homologue is down-regulated during apomictic initiation in ovules of Hieracium.

Hieracium is a member of the Asteraceae family, and contains sexual species in addition to apomictic species that reproduce by apospory and produce seed without fertilization. A homologue of the floral organ-identity gene DEFICIENS (DEF) was isolated from an apomictic line of Hieracium piloselloides (Vill.) following differential display between mature ovules and those initiating autonomous embryogenesis. The gene termed HPDEF has 93% amino acid identity with GDEF2, a DEF homologue isolated from Gerbera hybrida (D. Yu et al., 1999, Plant J. 17: 51-62), another member of the Asteraceae. In-situ analysis showed that early in floral development HPDEF is expressed in stamen and petal primordia, indicating expected B-function activity, according to the ABC model of floral organ identity (J. L. Bowman et al., 1991, Development 112: 1-20; E. S. Coen and E. M. Meyerowitz, 1991, Nature 353: 31-37). However, HPDEF expression was also observed in ovule primordia and expression continued in developing ovules until anthesis, indicating that this gene may have a role in ovule development. Expression of HPDEF was not detected in megaspore mother cells, or in sexual or aposporous embryo sacs. In sexual Hieracium, HPDEF was uniformly expressed throughout the ovule integument until anthesis. In most ovules of the apomict, however, HPDEF expression was transiently down-regulated in a specific zone in the chalazal region where cells initiating aposporous embryo sac formation differentiate. Uniform low-level HPDEF expression was subsequently observed prior to anthesis in ovules from sexual and apomictic plants. HPDEF may be down-regulated as a consequence of apomictic initiation and/or its down-regulation may facilitate progression of apomictic events.

Amino Acid Sequence↗
PubMed2000

Dietary restriction reduces hepatocyte proliferation and enhances p53 expression but does not increase apoptosis in normal rats during development.

Dietary restriction (DR) retards physical growth, resulting in small body size, reduced liver weight and reduced number of hepatocytes in rats. We examined the effects of DR on proliferation and apoptosis of hepatocytes during development and explained these changes subcellularly using immunohistochemistry for bromodeoxyuridine (BrdU) incorporation, proliferating cell nuclear antigen (PCNA) and p53, terminal dUTP nick end labeling (TUNEL) and quantitative reverse transcription-polymerase chain reaction (RT-PCR) for TGFalpha, TGFbeta1, p53, Fas and TNF receptor (TNFr). Tissue samples included the livers of 3-month-old male Fischer 344 rats fed ad libitum (AL) or on 70% DR. DR significantly reduced the proportions of BrdU-positive and PCNA-strongly-positive hepatocytes compared with AL rats but not the proportions of PCNA-positive hepatocytes and TUNEL-positive hepatocytes. On the other hand, DR enhanced the expression of p53 and Fas mRNAs but failed to influence the expression of TGFalpha, TGFbeta1 and TNFr mRNAs. Moreover, DR significantly increased the proportion of p53-positive hepatocytes. Our findings suggest that DR suppresses the proliferation of hepatocytes, resulting in a reduced number of hepatocytes during development. This process may be mediated by overexpression of p53 suppressor gene. While DR accelerates the expression of Fas antigen, this result does not influence the rate of apoptosis of hepatocytes under physiological conditions.

Animals↗
PubMed2000

Extensive lymphopenia due to apoptosis of uninfected lymphocytes in acute measles patients.

Infection with measles virus induces a transient immunosuppression, which occasionally results in fatal opportunistic infections. To obtain fundamental information about the mechanism, we examined peripheral blood mononuclear cells (PBMC) from acute measles patients aged from infants to 35 years old, obtained at various times from incubation periods to 103 days after onset of rash, for the number of lymphocyte subsets by flowcytometry. The data were analyzed for relationships between aging of the patients and the severity of immunosuppression. In classical measles cases, infected lymphocytes detected as a minor population during the incubation period disappeared soon after onset of rash, whereas in the cases of serious illness, the infected cells persisted longer after the rash. At the onset of rash, remarkable lymphopenia had already occurred in all measles cases with reduction in cell numbers of CD4+ T cells, CD8+ T cells, B cells, neutrophils, and monocytes. In contrast, natural killer (NK) cells were increased in number and activated, which might be a response compensatory for the lymphopenia. Apoptosis-associated molecules such as CD95(Fas) and TNF-related apoptosis-inducing ligand-receptor (TRAIL-R) were highly expressed on the cell surface of most surviving non-infected lymphocytes, and DNA fragmentation was also observed upon incubation in vitro. These results suggested that the profound lymphopenia was primarily due to extended death of non-infected blood cells caused by apoptosis. The severity and duration of the lumphopenia were age-dependent; less severe in young children whereas much severer in infants under one year of age as well as adolescents and adults. From these results, it was suggested that remarkable lymphopenia due to apoptosis of uninfected cells is one of the principal causes for immunosuppression induced by measles virus infection, and is correlated with the age-dependent severity of the disease.

Acute Disease↗
PubMed2000

A single plate ultrasonic gyroscope in plane motion

We have proposed a vibration gyroscope made of a single piezoelectric plate in plane motion. The gyroscope makes use of the degenerated modes associated with a square plate. In the present paper, the experimental verification using an enlarged piezoelectric ceramic plate is presented, whose results are compared with the numerical prediction based on two-dimensional and three-dimensional finite element modelling.

Journal Article↗
PubMed2000

Effect of heat treatment of poly(L-lactide) on the response of osteoblast-like MC3T3-E1 cells.

Poly(L-lactide) (PLLA) products are molded by heat extrusion. These treatments may change chemical properties and biological response of the PLLA to cells. In this study, the effect of heat treatment of PLLA on osteoblast proliferation and differentiation was examined in vitro. Osteoblast-like MC3T3-E1 cells were cultured for 2 weeks on the PLLA subjected to various heating temperature and time combinations. The protein, DNA, and hydroxyproline (HYP) contents and alkaline phosphatase (ALP) activity of cells cultured on the untreated (non-heated) PLLA with a weight average molecular weight (Mw) of 1,000,000 (high Mw PLLA) were not significantly different from those of cells cultured on glass. The activation of osteoblast differentiation by the high Mw PLLA was weak. In contrast, increases in ALP activity and HYP content were found for cells cultured on the PLLA heated at a high temperature of 200 or 250 degrees C. Heat treatment of high Mw PLLA increased differentiation of MC3T3-E1 cells cultured upon it. Significant degradation of PLLA (decrease in molecular weight and increase in molecular weight distribution) were observed following heat treatment. The Mw of PLLA decreased from 1,000,000 to below 20,000, and 14.4 microg of L-lactic acid was released from 10 mg of PLLA by heating at 250 degrees C. Therefore, the effect of low Mw chemicals, which were expected to be the degradation products of high Mw PLLA after heat treatment, on MC3T3-E1 cell activities was examined. Increases in the protein, DNA and HYP amounts and ALP activity for cells cultured with L-lactide or L-lactic acid were observed at 100 microg/ml, but not at 10 microg/ml. When the cells were cultured on the low Mw PLLA (Mw 20,000), their biological parameters also increased. Twelve micrograms of L-lactic acid released from 10 mg of the low Mw PLLA during 2 weeks incubation. The concentration of L-lactic acid in the incubation solution of low Mw PLLA or heat-treated PLLA was too small to cause cell activation. These results suggested that increases in osteoblast differentiation on the heat-treated PLLA was not to due to soluble degradation chemicals, such as L-lactic acid, rather than the remaining low Mw PLLA.

Absorbable Implants↗
PubMed2000

Control of melanosome movement in intact and cultured melanophores in the bitterling, Acheilognathus lanceolatus.

The melanophores in the dermis on scales in the bitterling, Acheilognathus lanceolatus were studies to obtain information about the control mechanism of aggregation and dispersion using intact, membrane-permeabilized and cultured cells. The cultured melanophores showed supersensitivity, namely, they responded to norepinephrine with much higher sensitivity than intact cells. The cultured melanophores failed to respond to high KCl. Melatonin aggregated and adenosine dispersed melanosomes within a cell. Digitonin permeabilized cells showed aggregation with Ca ions and dispersion by cyclic adenosine 3',5'-monophosphate (cAMP) in the presence of ATP. Movement of melanosomes was observed under the high magnification of light microscope and the tracks of each pigment granule were followed. The granules moved fast and linearly during aggregation, whereas they showed to-and-fro movement during dispersion.

Animals↗
PubMed2000

Degradation pathway(s) of chlorophyll: what has gene cloning revealed?

The mechanism responsible for the degreening of plants and the degradation of chlorophyll was unclear for many years. However, recent studies have identified the colorless intermediates and helped to construct a basic pathway for degradation. After the successive removal of phytol and Mg21 from the chlorophyll molecule by chlorophyllase and 'Mg dechelatase', pheophorbide a is cleaved and reduced to yield a colorless, open tetrapyrrole intermediate. After further modifications, this is finally transported to the vacuole. Cloning the genes for chlorophyllase isozymes and the reductase should help to elucidate the physiological roles of each enzyme at a molecular level.

Amino Acid Sequence↗
PubMed2000

Spontaneous apoptotic DNA fragmentation in cultured guinea pig gastric mucosal cells.

The purpose of this study was to elucidate the mechanism of spontaneous and rapid cell death of cultured gastric pit cells. Gastric pit cells have a rapid cell turnover rate in vivo. We here show that guinea pig gastric pit cells in culture undergo spontaneous and rapid apoptotic DNA fragmentation, which may represent the rapid cell turnover cycle of gastric pit cells in vivo. This spontaneous apoptotic DNA fragmentation required the presence of fetal calf serum in the culture media. Furthermore, the spontaneous apoptotic DNA fragmentation was prevented by protein synthesis and caspase inhibitors.

Animals↗
PubMed2000

Geranylgeranylacetone protects cultured guinea pig gastric mucosal cells from indomethacin.

One of the major side effects of nonsteroidal antiinflammatory drugs, such as indomethacin, is gastropathy. The purpose of this study was to search for a therapeutic drug to prevent this side effect in vitro. We found that geranylgeranylacetone, a unique antiulcer drug with a heat-shock protein-inducing ability, protected cultured guinea pig gastric mucosal cells from cell damage caused by indomethacin. This cytoprotective effect of geranylgeranylacetone required concentrations of more than 10(-6) M and incubation periods of longer than 2 hr. Pretreatment of cells with an inhibitor of protein synthesis completely abolished the cytoprotective effect of geranylgeranylacetone, suggesting that some proteins induced by the drug are responsible for the cytoprotection. Since pretreatment of cells with low concentrations of ethanol, which also induced the heat-shock proteins, made cells resistant to indomethacin, heat-shock proteins are candidates for the proteins that are involved in the cytoprotective effect of geranylgeranylacetone against indomethacin.

Animals↗
PubMed2000

Regulation of the cutaneous allergic reaction by humidity.

Humidity is 1 of the environmental factors which regulate skin conditions. Effects of humidity on the cutaneous immune reaction were examined. Contact hypersensitivity to 2,4,6-trinitrochlorobenzene was elicited in C57BL/6 mice. The reaction was greater in mice housed under low humidity conditions (about 10%) for 2 days, at either the induction or elicitation phase, than in mice housed under rather high humidity conditions (80%). After housing under controlled humidity for 2 days, the number of I-A positive cells was 16% higher in the epidermis exposed to the dry condition. The increased population of FITC-positive cells were in regional lymph nodes after painting of FITC during housing under lower humidity. Our study demonstrated that the cutaneous immune reaction is regulated by environmental humidity and suggested 2 possible mechanisms, i.e., increase in Langerhans cells and increased penetration of allergen with low humidity.

Allergens↗
PubMed2000

Barrier recovery rate varies time-dependently in human skin.

The recovery in cutaneous barrier functions, assessed in terms of transepidermal water loss, 1 h after tape stripping of volar forearm skin in human volunteers, was investigated at different times over the 24 h day. The barrier recovery rate was significantly lower between 20:00 h and 23:00 h than that at other time points. The skin surface temperature and the basal transepidermal water loss reached their highest values at about 03:00 h (33.6 degrees C and 0.30 mg cm-2 h-1), while the cortisol level in the saliva was highest at 09:00 h (7.8 pmol mL-1). These results suggest significant time-dependent variation in cutaneous barrier repair independent of changes in skin temperature and cortisol level.

Adult↗
PubMed2000

Odorant inhalation affects skin barrier homeostasis in mice and humans.

Previous studies have suggested that psychological stress delays cutaneous barrier recovery following acute barrier disruption, and that sedative drugs block this delay. A sedative effect of some odorants has been reported. In the present study, we demonstrate that odorant inhalation affects cutaneous barrier homeostasis in both mice and humans. Odorants with a sedative effect prevented the delay of skin barrier recovery induced by stress after acute barrier disruption. Other odorants did not show this effect.

Administration, Inhalation↗
PubMed2000

Functional expression of mung bean Ca2+/H+ antiporter in yeast and its intracellular localization in the hypocotyl and tobacco cells.

The Ca2+-transport activity and intracellular localization of the translation product of cDNA for mung bean Ca2+/H+ antiporter (VCAX1) were examined. When the cDNA was expressed in Saccharomyces cerevisiae that lacked its own genes for vacuolar Ca2+-ATPase and the antiporter, VCAX1 complemented the active Ca2+ transporters, and the microsomal membranes from the transformant showed high activity of the Ca2+/H+ antiporter. Treatment of the vacuolar membranes with a cross-linking reagent resulted in a clear band of the dimer detected with antibody specific for VCAX1p. The antibody was also used for immunolocalization of the antiporter in fractions obtained by sucrose-density-gradient centrifugation of the microsomal fraction from mung bean. The immunostained band was detected in the vacuolar membrane fraction and the slightly heavy fractions that exhibited activity of the Golgi marker enzyme. A fusion protein of VCAX1p and green fluorescent protein was expressed in tobacco cells. The green fluorescence was clearly observed on the vacuolar membrane and, in some cases, in the small vesicles. The subcellular fractionation of transformed tobacco cells confirmed the vacuolar membrane localization of the fusion protein. These results confirm that VCAX1p functions in the vacuolar membrane as a Ca2+/H+ antiporter and also suggest that VCAX1p may exist in the Golgi apparatus.

Antiporters↗
PubMed2000

Malignant intramuscular forearm tumor with overwhelming squamous element.

Squamous cell carcinoma (SCC) arising in the skeletal muscle is rare. A case of a 19-year-old female patient with an intramuscular forearm tumor showing a histopathologically overwhelming squamous element is presented. Microscopic examination revealed the classical features of SCC, including horn pearls, individual cell keratinization and intercellular bridge. A malignant spindle cell component was not detected. Neither evidence of another primary site nor skin lesion over the tumor was found and no metastatic lesion was detected in the 5 years since the appearance of the mass.

Actins↗
PubMed2000

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Journal Article↗