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Biomedical subjects

M Ozawa

Publications and source records attributed to M Ozawa.

At least 19 recordsLinked to original sources
PubMed2007

Cytoplasmic glutathione regulated by cumulus cells during porcine oocyte maturation affects fertilization and embryonic development in vitro.

It is generally accepted that cumulus cells support the nuclear maturation of mammalian oocytes. In the present study, we examined relationships between the cytoplasmic glutathione (GSH) content of porcine oocytes, and oocyte nuclear maturation, fertilization or subsequent embryonic development. Cumulus-oocyte complexes (COCs; control group) and oocytes denuded of cumulus cells after collection (DO 0h group) were cultured for 24h with dibutyryl cAMP, eCG and hCG (first culture step) and then for a further 20h without supplements (second culture step; 44h total culture). After the first culture step, some of the COCs were denuded, either completely (DO 24h group) or partly (H-DO 24h group), and then matured by the second culture step. Also, in the second culture step, some DOs were co-cultured with cumulus cells that had been pre-cultured for 24h (DO 24h+CC group). The maturation rates of all the cumulus-removed groups (DO 0h, DO 24h, H-DO 24h and DO 24h+CC groups) were lower (34.3-45.0%) than that of the control group (64.5%; P<0.05). The GSH contents of matured oocytes in the completely denuded groups (DO 0h, DO 24h and DO 24h+CC groups) were lower (4.03-5.26pmol/oocyte) than that of the control group (9.60pmol/oocyte; P<0.05); however, the H-DO 24h group had an intermediate value (7.0pmol/oocyte). The male pronuclear formation rates of completely denuded oocytes were lower (41.4-59.3%) than that of the control group (89.4%; P<0.05), whereas the H-DO 24h group had an intermediate rate (80.0%). The blastocyst formation rates of the completely denuded oocytes were lower (3.0-4.5%) than that of the control group (19.9%; P<0.05), and the H-DO 24h group again had an intermediate rate (11.6%). The GSH content was correlated with the rates of male pronuclear formation (P<0.01) and blastocyst formation (P<0.01), and also with the number of cells per blastocyst (P<0.01). In conclusion, we inferred that GSH synthesized by intact cumulus cells during maturation culture improved oocyte maturation and played an important role in fertilization and embryonic development.

Animals↗
PubMed2007

Four-year follow-up of a prospective trial of HLA and MICA antibodies on kidney graft survival.

In 2002, 1329 patients with functioning transplants were prospectively tested for HLA antibodies in the 13th International Histocompatibility Workshop. Four years after testing, deceased donor graft survival among 806 patients not having antibodies in 2002 was 81% compared to 58% for 158 patients with HLA antibodies (p < 0.0001) and 72% for 69 patients with MICA antibodies (p = 0.02). Hazard ratio (HR) using death-censored graft survival from multivariate analysis of HLA antibodies was 3.3 (p < 0.00001) and 2.04 for MICA (p = 0.01). In the 14th Workshop, at 1 year follow-up, survival for 1319 patients receiving deceased donor grafts and no HLA antibodies was 96% compared to 94% for 344 patients with HLA antibodies (p = 0.0004) and 83% survival for 33 patients with MICA (p = 0.0005). HR from multivariate analysis: HLA antibodies was 3.6 (p < 0.00001) and 6.1 for MICA (p = 0.006). Twelve patients with donor specific antibodies tested by single antigen beads had a 1 year survival of 64% (p = 0.008), and 27 patients with non-donor specific 'strong' antibodies had a 66% survival (p = 0.0003) compared to 92% survival in those with no antibodies. In conclusion, these two prospective trials, after 1 and 4 years, provided strong evidence that HLA and MICA antibodies are associated with graft failure.

Antibodies↗
PubMed2006

PACAP stimulates the release of interleukin-6 in cultured rat Müller cells.

We have investigated the in vivo effect of PACAP on rat Müller cells that are the predominant glial element in the retina. Müller cells were treated with PACAP38, either alone or in the presence of the PACAP-selective antagonist, PACAP6-38. Cellular proliferation was determined by measuring the incorporation of bromodeoxyuridine, while interleukin-6 (IL-6) levels in the culture medium were examined using a B9 cell bioassay. In cultured rat Müller cells, the expression of PACAP receptor (PAC1-R) was assessed with immunohistochemistry using a PAC1-R-specific antiserum. PACAP stimulated IL-6 production in Müller cells at a concentration as low as 10(-12) M, which was not sufficient to induce cell proliferation. This elevation of IL-6 production was significantly inhibited by PACAP6-38. These data suggest that Müller cells are one of the target cells for PACAP, stimulating the release of IL-6, and providing a mechanism whereby PACAP exerts a significant neuroprotective effect in the retina.

Animals↗
PubMed2006

[Surgical technique of aortic valve replacement for small aortic annulus in elderly patients].

Recent reports have shown that aortic valve replacement in elderly patients over 65 years with atherosclerotic aortic stenosis and a small aortic annulus is possible by using a small sized bioprosthesis (Carpentier-Edwards pericardial valve). Here we present out surgical technique. Firstly, the native calcified aortic valve was removed completely to gain total exposure of the surrounding aortic root and sinus of Valsalva like Bentall procedure. Secondly, a small sized bioprosthesis was implanted with intermittent noneverting mattress 2-0 sutures with spaghetti and small polytetrafluoroethylene (PTFE) felt. Aortic annulus is the dilated by inserting Hegar dilator sizing from 25 to 27 mm. Therefore, aortic valve replacement for small aortic annulus in intra- or supra-annular position should be easily accomplished. Good surgical results and hemodynamic state were achieved in 25 consecutive cases using this technique.

Aged↗
PubMed2005

Alterations in follicular dynamics and steroidogenic abilities induced by heat stress during follicular recruitment in goats.

We investigated the changes in follicular dynamics and steroidogenic activity during heat stress in goats. Adult female goats were exposed to heat stress at 36 degrees C and 70% relative humidity for 48 h and then injected with prostaglandin (PG) F2alpha (the time of PGF2alpha injection was designated as 0 h). In experiment 1, every follicle greater than 2 mm in diameter was monitored by ultrasonography to investigate the follicular dynamics, and plasma concentrations of FSH, LH, progesterone, and oestradiol were measured from -48 h to 120 h. In experiment 2, the follicles were recovered from the goats at 48 h, and the concentration of oestradiol, the aromatase activity, and the LH receptor level in the follicles were determined. In control (non-heat-stressed) goats, ovulatory follicles were mainly recruited from -24 h to 0 h, whereas no follicles recruited during that period were ovulated in the heat-stressed goats. The timing of the recruitment of ovulatory follicles was delayed by heat stress by approximately 24 h. The plasma concentration of oestradiol in the heat-stressed goats was significantly lower from 36 to 54 h compared with the controls, although the concentrations of FSH and progesterone did not differ between the treatments. In addition, the concentration of oestradiol, the aromatase activity, and the LH receptor level in the follicles from heat-stressed goats were significantly lower compared with the controls. These results indicate that heat stress during follicular recruitment suppresses subsequent growth to ovulation, accompanied by decreased LH receptor level and oestradiol synthesis activity in the follicles.

Animals↗
PubMed2004

Quantitative flow visualization of fluidized-bed heat exchanger by neutron radiography.

Quantitative flow visualization of a gas-solid fluidized-bed installed vertical tube-bank has been successfully conducted using neutron radiography and image processing technique. The quantitative data of void fraction distribution as well as the fluctuation data are presented. The time-averaged void fraction is well correlated by the drift-flux model. The bubbles formed in the bed, rise along the vertical tubes and the observed bubble size is smaller than that in a free bubbling bed without tube-banks. The bubble diameter is well correlated by the modified Mori and Wen's correlation taking into account the pitch of tube arrangement. The bubble rise velocity is also well correlated by applying the drift-flux model. These results are consistent for both bed materials of Geldart's B- and A-particles, while the bubble size is significantly different between two kinds of particles.

Journal Article↗
PubMed2002

Non-myeloablative haematopoietic stem cell transplantation for severe aplastic anaemia with various complications.

We report a 20-year-old-male with severe aplastic anaemia who was treated with nonmyeloablative haematopoietic stem cell transplantation (NSCT) from a sibling donor. As the patient presented with complications consisting of mental retardation, severe obesity, a bone fracture, and recurrent infections, we selected NSCT instead of a myeloablative regimen, to reduce regimen-related toxicity (RRT). Conditioning therapy consisting of busulfan, fludarabine, antithymocyte globulin and FK506 was used to obtain immune suppression. RRT was limited and he is now in complete remission 19 months after NSCT. On day 91, he developed chronic graft-vs.-host disease; it was resolved by the combination of FK506, corticosteroids, and mycophenolate mofetil. Our experience contributes to the growing interest in NSCT as a modality for treating not only malignant haematological disorders associated with complications, but also nonmalignant haematological diseases.

Adult↗
PubMed2002

Developmental competence and oxidative state of mouse zygotes heat-stressed maternally or in vitro.

Mammalian preimplantation embryos are sensitive to maternal and direct heat stress. However, the mechanisms by which heat stress affects early embryonic development in vivo or in vitro are unknown. This study examined whether heat-stress-induced loss of developmental competence in mouse embryos was mediated by physiological changes in the maternal environment or by high temperatures alone. After fertilization, zygotes at the same stage were heat-stressed at 39.5 degrees C for 12 h either maternally (measured by maternal rectal temperature) or directly in culture. Zygotes in each group were cultured at 37.5 degrees C for a further 84 h to assess their developmental ability. Neither type of heat stress affected the first cleavage rate. However, the proportion of embryos that developed to morulae or blastocysts was significantly lower in the maternally heat-stressed group, but not in the directly heat-stressed group. Moreover, maternal heat stress significantly reduced intracellular glutathione concentrations and enhanced hydrogen peroxide concentrations in both zygotes and two-cell embryos that were recovered immediately after heat stress or 12 h later, respectively. In contrast, direct heat stress had little effect on concentrations of glutathione or hydrogen peroxide in cultured early embryos. These results demonstrate that maternal heat stress at the zygote stage reduces the developmental ability of mouse embryos via physiological changes in the maternal environment that lead to an increase in intracellular oxidative stress on the embryo.

Animals↗
PubMed2001

Comparison of sequences of cDNA clones obtained from oligo-capping cDNA libraries with those from unigene.

We compared in detail the characteristics of the sequences of the cDNA clones obtained by the oligo-capping method (oligo-capping clones) with that of the sequences in the UniGene database. To compare the completeness of the sequences, three new variables, "fullness-proportion of clones" (the ratio of complete clones to total clones in a library), "fullness-proportion of genes" (the ratio of complete genes to total genes in a library), and "fullness-proportion of database" (the ratio of complete genes to total genes in a database sampled from a library), were defined. The fullness-proportion of clones of oligo-capping clones was 57.3%, 2.2 times larger than that of UniGene (25.9%). The fullness-proportion of genes of oligo-capping clones was 41.8%, 2.4 times larger than that of UniGene (17.8%). When gene length was restricted to > or = 1.5 kb, the fullness-proportion of genes of oligo-capping clones was four times larger than that of UniGene. The fullness-proportion of database of oligo-capping clones was approximately the same as that of UniGene. By simulating the clone redundancy, this coincidence was found to be due to the large redundancy of the UniGene database. Consequently, the cDNA sequence database of oligo-capping clones enabled high throughput selection of full-length cDNA clones.

Algorithms↗
PubMed2001

Effects of surface soil removal on dynamics of dissolved inorganic nitrogen in a snow-dominated forest.

To clarify the effect of vegetation and surface soil removal on dissolved inorganic nitrogen (N) dynamics in a snow-dominated forest soil in northern Japan, the seasonal fluctuation of N concentrations in soil solution and the annual flux of N in soil were investigated at a treated site (in which surface soil, including understory vegetation and organic and A horizons, was removed) and control sites from July 1998 to June 2000. Nitrate (NO3-) concentration in soil solution at the treated site was significantly higher than that of the control in the no-snow period, and it was decreased by dilution from melting snow. The annual net outputs of NO3- from soil at the treated site and control sites were 257 and -12 mmol m(-2) year(-1), and about 57% of the net output at the treated site occurred during the snowmelt period. NO3- was transported from the upper level to the lower level of soil via water movement during late autumn and winter, and it was retained in soil and leached by melt water in early spring. Removing vegetation and surface soil resulted in an increase in NO3- concentration of soil solution, and snowmelt strongly affected the NO3- leaching from treated soil and the NO3- restoration process in a snow-dominated region.

Ammonia↗
PubMed2001

TGF-beta-producing CD4+ mediastinal lymph node cells obtained from mice tracheally tolerized to ovalbumin (OVA) suppress both Th1- and Th2-induced cutaneous inflammatory responses to OVA by different mechanisms.

Advances in the treatment of allergic disorders require elucidation of the autoregulatory immune systems induced in averting detrimental inflammatory responses against invading foreign Ags. We previously reported that excessive Ags intruding through the airway mucosa induce a subset of regulatory CD4+ T cells secreting TGF-beta in the regional mediastinal lymph nodes (MLNs), which inhibits Th2 cells and subsequent eosinophilic inflammation in the trachea. In the present experiments we examined whether and in what mechanisms TGF-beta-secreting CD4+ T cells in the MLNs regulate Th cell-mediated skin inflammation using a previously established murine model. Th1 or Th2 cells injected s.c. into ear lobes of naive mice induced swelling, whereas the concomitant local injection of MLN cells suppressed the inflammation. The suppressor activities of MLN cells were markedly neutralized by anti-TGF-beta mAb and were mimicked by rTGF-beta. The MLN cell- and rTGF-beta-induced inhibition was reversed by anti-IL-10 mAb significantly in Th1-induced inflammation and only partially in Th2-induced inflammation. rIL-10 reduced Th-induced ear swelling, although higher doses of rIL-10 were required in Th2-induced one. Thus, allergen-specific TGF-beta-producing CD4+ T cells induced in the respiratory tract controlled cutaneous inflammatory responses by Th1 or Th2 cells either directly by TGF-beta or indirectly through IL-10 induction. From a clinical standpoint, these observations might explain the mechanism of spontaneous regression in some patients with atopic dermatitis, which exhibits both Th1- and Th2-mediated skin inflammation in response to airborne protein Ags.

Animals↗
PubMed2001

Expression of alpha-catenin in alpha-catenin-deficient cells increases resistance to sphingosine-induced apoptosis.

Alpha-catenin, an intracellular protein, associates with the COOH-terminal region of cadherin cell adhesion molecules through interactions with either beta-catenin or gamma-catenin (plakoglobin). The full activity of cadherins requires a linkage to the actin cytoskeleton mediated by catenins. We transfected alpha-catenin-deficient colon carcinoma cells with a series of alpha-catenin constructs to determine that alpha-catenin expression increases the resistance to apoptosis induced by sphingosine. Two groups of constructs, containing deletions in either the middle segment of the molecule or the COOH terminus, induced morphological changes, cell compaction, and decreases in cell death. In alpha-catenin-expressing cells, inhibition of cadherin cell adhesion by treatment with anti-E-cadherin antibodies did not decrease the cells viability. alpha-Catenin expression partially suppressed the downregulation of Bcl-xL and the activation of caspase 3. Expression of p27kip1 protein, an inhibitor of cyclin-dependent kinases, was increased by alpha-catenin expression in low density cell cultures. The increased levels of p27kip1 correlated with both increased resistance to cell death and morphological changes in transfectants containing deletion mutants. Transfection-mediated upregulation of p27kip1 decreases sphingosine-induced cell death in alpha-catenin-deficient cells. We postulate that alpha-catenin mediates transduction of signals from the cadherin-catenin complex to regulate the apoptotic cascade via p27kip1.

Antibodies↗
PubMed2001

Presenilin-1 binds cytoplasmic epithelial cadherin, inhibits cadherin/p120 association, and regulates stability and function of the cadherin/catenin adhesion complex.

Here we show that presenilin-1 (PS1), a protein involved in Alzheimer's disease, binds directly to epithelial cadherin (E-cadherin). This binding is mediated by the large cytoplasmic loop of PS1 and requires the membrane-proximal cytoplasmic sequence 604-615 of mature E-cadherin. This sequence is also required for E-cadherin binding of protein p120, a known regulator of cadherin-mediated cell adhesion. Using wild-type and PS1 knockout cells, we found that increasing PS1 levels suppresses p120/E-cadherin binding, and increasing p120 levels suppresses PS1/E-cadherin binding. Thus PS1 and p120 bind to and mutually compete for cellular E-cadherin. Furthermore, PS1 stimulates E-cadherin binding to beta- and gamma-catenin, promotes cytoskeletal association of the cadherin/catenin complexes, and increases Ca(2+)-dependent cell-cell aggregation. Remarkably, PS1 familial Alzheimer disease mutant DeltaE9 increased neither the levels of cadherin/catenin complexes nor cell aggregation, suggesting that this familial Alzheimer disease mutation interferes with cadherin-based cell-cell adhesion. These data identify PS1 as an E-cadherin-binding protein and a regulator of E-cadherin function in vivo.

Animals↗
PubMed2001

Mg@C72 MNDO/d evaluation of the isomeric composition.

Temperature development of the relative stabilities of isomers of Mg@C72 (which has not yet been isolated) is computed using the recently introduced MNDO/d method. Four isomers originally considered for the Ca@C72 case are treated: one isolated-pentagon-rule (IPR) structure, two structures with a pair of adjacent pentagons, and one cage with a heptagon. The IPR structure comes as the lowest in MNDO/d potential energy, being rather closely followed by the two structures with a pentagon-pentagon pair. On the other hand, the structure with a heptagon is located too high in potential energy to be of any experimental significance. The entropy contributions are evaluated by the MNDO/d-based partition functions so that the relative concentrations can be treated accordingly. The computations suggest that if Mg@C72 is isolated, it should be a mixture of either two or three isomers. The prediction depends on temperature prehistory. If preparation takes place at temperatures of approximately 1000 K, two isomers should be produced. If temperatures are increased to approximately 2000 K, there will already be three isomers with significant relative concentrations. The study supplies a further interesting example of the profound role of enthalpy-entropy interplay in stabilities of isomeric fullerenic structures.

Carbon↗
PubMed2001

Production and pharmacologic modulation of the granulocyte-associated allergic responses to ovalbumin in murine skin models induced by injecting ovalbumin-specific Th1 or Th2 cells.

Because interferon-gamma, interleukin-4, and interleukin-5 have been identified at the mRNA and protein levels in the lesional skin of patients with atopic dermatitis, we investigated the roles played by granulocytes as effector cells in allergic inflammation by using two unique murine skin models. In vitro generated Th1 and Th2 cells from naïve splenocytes of antiovalbumin T cell receptor transgenic BALB/C mice were adoptively transferred with ovalbumin into the ear pinnae or air-pouches produced in the back skin of naïve, nontransgenic BALB/C mice. The injection of Th1 cells with ovalbumin induced delayed type ear swelling that peaked at 48 h, whereas that of Th2 resulted in ear swelling that peaked at a much earlier time, 24 h. Histologic study of the swollen ear skin and granulocytes recruited into the air-pouch demonstrated that, although the Th1-induced inflammation caused a neutrophil-predominant infiltrate with few eosinophils, larger numbers of eosinophils accumulated in the Th2-induced inflammation. Using these murine models, we further evaluated the effects of drugs used for the treatment of atopic diseases. The results showed that FK506 administration could effectively reduce skin inflammation induced by either Th cells. Interestingly, the neutrophil elastase inhibitor ONO-6818 efficiently inhibited Th1-induced inflammation. In contrast, a leukotriene receptor antagonist, ONO-1078, specifically suppressed Th2-induced inflammation. We also found that each ONO drug exerted direct influence on specified granulocytes, as neither affected in vitro production of relevant Th cytokines. Thus, we succeeded in developing animal skin inflammation models in which we can evaluate the contribution of protein antigen-specific Th1 or Th2 cells through the action of granulocytic effector cells.

Animals↗
PubMed2001

Tyrosine phosphorylation of p120(ctn) in v-Src transfected L cells depends on its association with E-cadherin and reduces adhesion activity.

Cadherins are transmembrane glycoproteins involved in Ca2+-dependent cell-cell adhesion. Using L cells expressing one of three functional E-cadherin constructs, the wild-type, a chimeric molecule with alpha-catenin (EalphaC), and a tail-less one, we determined the effect of v-Src expression on E-cadherin-mediated adhesion. The aggregation of L cells expressing the wild-type or EalphaC chimeric protein, which both interact with p120(ctn), was reduced by v-Src expression, whereas that of L cells expressing the tail-less E-cadherin was not affected by the expression. Tyrosine phosphorylation of p120(ctn) was observed in v-Src-transformed L cells expressing the wild-type or EalphaC chimeric protein, but not in ones expressing the tail-less E-cadherin. Thus, tyrosine phosphorylation of p120(ctn) depends on the complex formation with E-cadherin and the resulting membrane localization. Constitutive phosphorylation of p120(ctn) on serine and threonine residues also depends on the complex formation and membrane localization. Coexpression of the p120(ctn) protein with an N-terminal deletion, which eliminates some potential tyrosine phosphorylation sites, or the protein with a single amino acid substitution (tyrosine at 217 to phenylalanine) resulted in an increase in the aggregation of v-Src-transformed EL and EalphaCL cells. These results indicate that tyrosine phosphorylation of p120(ctn) is involved in the v-Src modulation of E-cadherin-mediated cell adhesion.

Amino Acid Substitution↗