Biomedical subjects

S Akamatsu

Publications and source records attributed to S Akamatsu.

At least 19 recordsLinked to original sources

PubMed2002

Surface effects in nucleation and growth of smectic-B crystals in thin samples.

We present an experimental study of the surface effects (interactions with the container walls) during the nucleation and growth of smectic-B (SmB) crystals from the nematic in free growth and directional solidification of a mesogenic molecule [C4H9-(C6H10)2CN] called CCH4 in thin (of thickness in the 10-microm range) samples. We follow the dynamics of the system in real time with a polarizing microscope. The inner surfaces of the glass-plate samples are coated with polymeric films, either rubbed polyimid (PI) films or mono-oriented poly(tetrafluoroethylene) (PTFE) films deposited by friction at high temperature. The orientation of the nematic and the smectic-B is planar. In PI-coated samples, the orientation effect of SmB crystals is mediated by the nematic, whereas, in PTFE-coated samples, it results from a homoepitaxy phenomenon occurring for two degenerate orientations. A recrystallization phenomenon partly destroys the initial distribution of crystal orientations. In directional solidification of polycrystals in PTFE-coated samples, a particular dynamics of faceted grain boundary grooves is at the origin of a dynamical mechanism of grain selection. Surface effects also are responsible for the nucleation of misoriented terraces on facets and the generation of lattice defects in the solid.

Journal Article↗

PubMed2002

Pattern stability and trijunction motion in eutectic solidification.

We demonstrate by both experiments and phase-field simulations that lamellar eutectic growth can be stable for a wide range of spacings below the point of minimum undercooling at low velocity, contrary to what is predicted by existing stability analyses. This overstabilization can be explained by relaxing Cahn's assumption that lamellae grow locally normal to the eutectic interface.

Journal Article↗

PubMed2001

Dynamics of a faceted nematic-smectic-B front in thin-sample directional solidification.

We present an experimental study of the directional-solidification patterns of a nematic-smectic-B front. The chosen system is C4H9-(C6H10)2CN (in short, CCH4) in 12 microm-thick samples, and in the planar configuration (director parallel to the plane of the sample). The nematic-smectic-B interface presents a facet in one direction-the direction parallel to the smectic layers--and is otherwise rough and devoid of forbidden directions. We measure the Mullins-Sekerka instability threshold and establish the morphology diagram of the system as a function of the solidification rate V and the angle straight theta(0) between the facet and the isotherms. We focus on the phenomena occurring immediately above the instability threshold when straight theta(0) is neither very small nor close to 90 degrees. Under these conditions, we observe drifting shallow cells and a type of solitary wave, called "faceton," which consists essentially of an isolated macroscopic facet traveling laterally at such a velocity that its growth rate with respect to the liquid is small. Facetons may propagate either in a stationary or an oscillatory way. The detailed study of their dynamics casts light on the microscopic growth mechanisms of the facets in this system.

Journal Article↗

PubMed2001

Involvement of p38 MAP kinase in TGF-beta-stimulated VEGF synthesis in aortic smooth muscle cells.

Although it is known that transforming growth factor (TGF)-beta induces vascular endothelial growth factor (VEGF) synthesis in vascular smooth muscle cells, the underlying mechanisms are still poorly understood. In the present study, we examined whether the mitogen-activated protein (MAP) kinase superfamily is involved in TGF-beta-stimulated VEGF synthesis in aortic smooth muscle A10 cells. TGF-beta stimulated the phosphorylation of p42/p44 MAP kinase and p38 MAP kinase, but not that of SAPK (stress-activated protein kinase)/JNK (c-Jun N-terminal kinase). The VEGF synthesis induced by TGF-beta was not affected by PD98059 or U0126, specific inhibitors of the upstream kinase that activates p42/p44 MAP kinase. We confirmed that PD98059 or U0126 did actually suppress the phosphorylation of p42/p44 MAP kinase by TGF-beta in our preparations. PD169316 and SB203580, specific inhibitors of p38 MAP kinase, significantly reduced the TGF-beta-stimulated synthesis of VEGF (each in a dose-dependent manner). PD169316 or SB203580 attenuated the TGF-beta-induced phosphorylation of p38 MAP kinase. These results strongly suggest that p38 MAP kinase plays a part in the pathway by which TGF-beta stimulates the synthesis of VEGF in aortic smooth muscle cells.

Animals↗

PubMed2001

A principal component analysis of facial expressions.

Pictures of facial expressions from the Ekman and Friesen set (Ekman, P., Friesen, W. V., (1976). Pictures of facial affect. Palo Alto, California: Consulting Psychologists Press) were submitted to a principal component analysis (PCA) of their pixel intensities. The output of the PCA was submitted to a series of linear discriminant analyses which revealed three principal findings: (1) a PCA-based system can support facial expression recognition, (2) continuous two-dimensional models of emotion (e.g. Russell, J. A. (1980). A circumplex model of affect. Journal of Personality and Social Psychology, 39, 1161-1178) are reflected in the statistical structure of the Ekman and Friesen facial expressions, and (3) components for coding facial expression information are largely different to components for facial identity information. The implications for models of face processing are discussed.

Adolescent↗

PubMed2001

Trehalose suppresses lipopolysaccharide-induced osteoclastogenesis bone marrow in mice.

We have previously shown that trehalose suppresses bone loss in ovariectomized (OVX) mice by way of inhibiting osteoclast differentiation in bone marrow. Also, trehalose inhibits the secretion of interleukin-6 in bone marrow cell cultures, resulting in a decrease in osteoclast formation. In this study, we examined the effect of trehalose on osteoclastogenesis using another model of bone resorption, namely lipopolysaccharide (LPS)-stimulated osteoclast induction. Mice were given trehalose (1g/kg) by gastric intubation for 5 consecutive days, and 24 hours later, 14 mg/kg of LPS was injected intraperitoneally. Trehalose significantly suppressed LPS-induced tumor necrosis factor (TNF)-alpha production after 90 min and decreased the number of osteoclasts in the bone marrow 48 hours after LPS injection. These results indicate that trehalose suppresses excessive osteoclastogenesis not only in OVX mice but also in a LPS-induced bone resorption mouse model and further suggest that the latter finding may be mediated at least in part through a decrease in TNF-alpha production.

Journal Article↗

PubMed2001

On-site diagnosis of H. pylori infection by urine.

We have recently developed an on-site diagnostic kit for H. pylori infection using urine (utilizing immunochromatographic method employing a nitrocellulose membrane coated by extracted H. pylori antigen). Accordingly, we investigated its usefulness in 155 consecutive dyspeptic patients using the 13C urea breath test as a gold standard and further compared its performance with two commercially available rapid diagnostic kits that use whole blood (Helisal Rapid Blood, and ImmunoCard H. pylori). As the results, the urine based on-site diagnostic kit provided 95.9% sensitivity and 87.9% specificity with 92.9% accuracy, which were comparable or even better than that of both rapid whole blood tests, suggesting its usefulness in screening of H. pylori infection.

Antigens, Bacterial↗

PubMed2001

Attractiveness of facial averageness and symmetry in non-western cultures: in search of biologically based standards of beauty.

Averageness and symmetry are attractive in Western faces and are good candidates for biologically based standards of beauty. A hallmark of such standards is that they are shared across cultures. We examined whether facial averageness and symmetry are attractive in non-Western cultures. Increasing the averageness of individual faces, by warping those faces towards an averaged composite of the same race and sex, increased the attractiveness of both Chinese (experiment 1) and Japanese (experiment 2) faces, for Chinese and Japanese participants, respectively. Decreasing averageness by moving the faces away from an average shape decreased attractiveness. We also manipulated the symmetry of Japanese faces by blending each original face with its mirror image to create perfectly symmetric versions. Japanese raters preferred the perfectly symmetric versions to the original faces (experiment 2). These findings show that preferences for facial averageness and symmetry are not restricted to Western cultures, consistent with the view that they are biologically based. Interestingly, it made little difference whether averageness was manipulated by using own-race or other-race averaged composites and there was no preference for own-race averaged composites over other-race or mixed-race composites (experiment 1). We discuss the implications of these results for understanding what makes average faces attractive. We also discuss some limitations of our studies, and consider other lines of converging evidence that may help determine whether preferences for average and symmetric faces are biologically based.

Adolescent↗

PubMed2001

Dynamic properties influence the perception of facial expressions.

Two experiments were conducted to investigate the role played by dynamic information in identifying facial expressions of emotion. Dynamic expression sequences were created by generating and displaying morph sequences which changed the face from neutral to a peak expression in different numbers of intervening intermediate stages, to create fast (6 frames), medium (26 frames), and slow (101 frames) sequences. In experiment 1, participants were asked to describe what the person shown in each sequence was feeling. Sadness was more accurately identified when slow sequences were shown. Happiness, and to some extent surprise, was better from faster sequences, while anger was most accurately detected from the sequences of medium pace. In experiment 2 we used an intensity-rating task and static images as well as dynamic ones to examine whether effects were due to total time of the displays or to the speed of sequence. Accuracies of expression judgments were derived from the rated intensities and the results were similar to those of experiment 1 for angry and sad expressions (surprised and happy were close to ceiling). Moreover, the effect of display time was found only for dynamic expressions and not for static ones, suggesting that it was speed, not time, which was responsible for these effects. These results suggest that representations of basic expressions of emotion encode information about dynamic as well as static properties.

Adolescent↗

PubMed2001

Incidental learning of real-world regularities.

The large literature on incidental learning relies almost exclusively on laboratory experiments. Whenever researchers have attempted to demonstrate incidental learning of real-world regularities, they have typically failed to show learning. For example, it is well established that people do not learn regularities in everyday objects, such as the left-right orientation of faces on coins, despite a very large exposure to them. In this report, we examine this apparent contradiction. We argue that most studies exploring real-life incidental learning use tests that are not as sensitive to low-confidence information as those traditionally used in laboratory tasks. Using more sensitive measures, we show that it is possible to learn regularities from British and Japanese cultural life as a direct result of exposure to these regularities. Further, confidence measures suggest that although the information may be acquired incidentally, it can be expressed with and without concomitant awareness of that knowledge.

Adult↗

PubMed2001

Novel malonamide derivatives as alpha v beta 3 antagonists. Syntheses and evaluation of 3-(3-indolin-1-yl-3-oxopropanoyl)aminopropanoic acids on vitronectin interaction with alpha v beta 3.

In attempt to find novel integrin alphavbeta3 antagonists, we selected SC65811 and its guanidine analogue (1) as lead compounds. Modification of the glycine part of SC65811 led to a new series of malonamide derivatives that exhibited alphavbeta3 inhibitory activity. Among them, (R,S)-3-[3-[6-(3-benzylureido)indolin-1-yl]-3-oxopropanoylamino]-3- (pyridin-3-yl)propanoic acid (43a) showed not only potent activity with an IC50 value of 3.0 nM but also good selectivity for alphavbeta3 relative to alphaIIbbeta3, alpha5beta1, and alphavbeta5 with IC50 values of 19,000, 11,000, and 14 nM, respectively. Furthermore, optimization of 43a led to the most potent alphavbeta3 antagonist, (R,S)-3-(3-[6-[(4,5-dihydro-1H-imidazol-2-yl)amino]indolin-1-yl]-3-oxopropanoylamino)-3-(quinolin-3-yl)propanoic acid (431) with an IC50 value of 0.42 nM. The synthesis and the structure-activity relationships of these malonamide derivatives are presented.

Aniline Compounds↗

PubMed2001

Magnitude of the regression to the mean within one-year intra-individual changes in serum lipid levels among Japanese male workers.

To investigate the magnitude of the 'regression to the mean' effect for the changes in serum total cholesterol (TC), triglycerides (TG), and high density lipoprotein cholesterol (HDLC) levels during one-year interval between annual health check-ups in occupational settings, the relationships between the baseline level and subsequent one-year change in TC, TG or HDLC were analyzed using paired health check-up data in 1998 and 1999 of 547 Japanese male clerical workers. After adjustment for age, body mass index (BMI), yearly change in BMI, drinking score and smoking score by the multivariate analyses, the yearly changes in each serum lipid (deltaTC, deltaLn(TG) or deltaHDLC) were clearly inversely associated with the lipid levels in 1998. For example, in the multiple linear regression analyses setting delta value in each serum lipid as a dependent variable, the partial regression coefficients for the baseline lipid levels (beta1) were - 0.21 (p<0.001) for the TC, -0.39 (p<0.001) for the Ln(TG) and -0.15 (p<0.001) for the HDLC, respectively. These results suggest that the observed yearly change in each serum lipid level may largely reflect the 'regression to the mean' effect in addition to the real yearly biological change.

Adult↗

PubMed2000

The Noh mask effect: vertical viewpoint dependence of facial expression perception.

Full-face masks, worn by skilled actors in the Noh tradition, can induce a variety of perceived expressions with changes in head orientation. Out-of-plane rotation of the head changes the two-dimensional image characteristics of the face which viewers may misinterpret as non-rigid changes due to muscle action. Three experiments with Japanese and British viewers explored this effect. Experiment 1 confirmed a systematic relationship between vertical angle of view of a Noh mask and judged affect. A forward tilted mask was more often judged happy, and one backward tilted more often judged sad. This effect was moderated by culture. Japanese viewers ascribed happiness to the mask at greater degrees of backward tilt with a reversal towards sadness at extreme forward angles. Cropping the facial image of chin and upper head contour reduced the forward-tilt reversal. Finally, the relationship between head tilt and affect was replicated with a laser-scanned human face image, but with no cultural effect. Vertical orientation of the head changes the apparent disposition of facial features and viewers respond systematically to these changes. Culture moderates this effect, and we discuss how perceptual strategies for ascribing expression to familiar and unfamiliar images may account for the differences.

Adolescent↗

PubMed2000

Enhancement by sphingosine 1-phosphate in vasopressin-induced phosphoinositide hydrolysis in aortic smooth-muscle cells: involvement of p38 MAP kinase.

We previously reported that sphingosine 1-phosphate (S-1-P), a sphingomyelin metabolite, activates p44/p42 mitogen-activated protein (MAP) kinase and p38 MAP kinase in aortic smooth-muscle A10 cells. In the present study, we investigated the effect of sphingomyelin metabolites on phospholipase C-catalyzing phosphoinositide hydrolysis induced by arginine vasopressin (AVP) in A10 cells. C(2)-ceramide and sphingosine had little effect on inositol phosphate (IP) formation stimulated by AVP. S-1-P, which alone slightly stimulated the IPs formation, dose-dependently amplified the AVP-induced formation of IPs. Tumor necrosis factor-alpha enhanced the AVP-induced formation of IPs. However, S-1-P did not enhance the formation of IPs by NaF, a heterotrimeric GTP-binding protein activator. Pertussis toxin inhibited the effect of S-1-P. PD98059, an inhibitor of the upstream kinase that activates p44/p42 MAP kinase, had little effect on the enhancement by S-1-P. SB203580, an inhibitor of p38 MAP kinase, suppressed the effect of S-1-P on the formation of IPs by AVP. SB203580 inhibited the AVP-induced phosphorylation of p38 MAP kinase. Pertussis toxin suppressed the phosphorylation of p38 MAP kinase by S-1-P. These results indicate that S-1-P amplifies AVP-induced phosphoinositide hydrolysis by phospholipase C through p38 MAP kinase in vascular smooth-muscle cells.

Aorta↗

PubMed2000

IL-18 prevents the development of chronic graft-versus-host disease in mice.

The development of chronic graft-versus-host disease (GVHD), which is induced by the transfer of DBA/2 spleen cells into (C57BL/6 x DBA/2)F1 (BDF1) mice, is closely related to diminished donor anti-host CTL activity and host B cell hyperactivation. Therefore, an approach which activates donor CD8+ T cells or suppresses donor CD4+ T cell-host B cell interaction may have clinical utility in the treatment of chronic GVHD. We have previously demonstrated that IL-18 induces the development of naive CD8+ T cells into type I effector cells in DBA/2 anti-BDF1 MLC. In this paper we examined the effect of IL-18 administration on the development of chronic GVHD in mice. The treatment was started before or after the onset of clinical evidence of the disease. Regardless of the treatment schedule, IL-18 significantly decreased immunological parameters indicative of chronic GVHD, such as elevated serum IgG antinuclear Abs, IgG1, and IgE levels, and host B cell numbers and their activation. Importantly, IL-18-treated mice did not show the same acute GVHD-like symptoms reported for IL-12 treatment, because there was no weight loss, death, or severe immunodeficiency as indicated by a decrease in IL-2 and IFN-gamma production by Con A-stimulated spleen cells. In contrast, IL-18 treatment partially but significantly restored the production of these cytokines. Data further suggested that these IL-18-mediated therapeutic effects may be due to the induction of donor CD8+ CTL, the decrease in donor CD4+ T cell numbers, and a down-regulation of host B cell MHC class II expression. Thus, our results suggest that IL-18 has beneficial effects in the prevention and treatment of chronic GVHD.

Acute Disease↗

PubMed2000

A new method for assaying adhesion of cancer cells to the greater omentum and its application for evaluating anti-adhesion activities of chemically synthesized oligosaccharides.

A new ex vivo method for assaying adhesion of cancer cells to the greater omentum has been developed using mouse greater omentum and [3H]labelled human gastric and mouse colorectal cancer cells. Since the adhesion rates were found to increase up to 18 h and labelled cells seemed to be stable during the period, the present method could be useful for investigating adhesion of cancer cells to the greater omentum, which must occur at the first step of the peritoneal dissemination. The adhesion of cancer cells to the greater omentum was inhibited by a series of chemically synthesized oligosaccharides and Gal beta1,3[3OMeGal beta1,4GlcNAc beta1,6]alphaBn was found to be the best inhibitor. The anti-tumor effect of this novel tetrasaccharide in vivo was shown in preliminary experiments using Balb/c mice and colon26 cells.

Animals↗

PubMed2000

Interleukin-18 in combination with IL-2 enhances natural killer cell activity without inducing large amounts of IFN-gamma in vivo.

Interleukin-18 (IL-18) is known to synergistically enhance murine natural killer (NK) cell activity in vitro when combined with either IL-12 or IL-2. However, it has also been demonstrated that simultaneous administration of IL-18 and IL-12 to mice induces extraordinarily large amounts of interferon-gamma (IFN-gamma) in the serum. In this study, we examined the effects of a combination of IL-18 and IL-2 on in vivo NK cell activation in parallel with the induction of toxicity. In contrast to the IL-18 and IL-12 combination, the combined administration of IL-18 and IL-2 to BALB/c mice for 3 days induced neither high levels of IFN-gamma production nor other visible side effects. When compared with treatment with IL-18 or IL-2 alone, the combined treatment resulted in a significant increase in the number of DX-5 (pan-NK cells marker)-positive cells in spleens and a marked enhancement of splenic NK activity, as determined by standard cytotoxicity assays. Enhanced splenic cytotoxicity generated in the mice treated with both IL-18 and IL-2 was also observed against syngeneic Colon 26 adenocarcinoma cells. Consistent with this in vitro observation, combined treatment produced a significantly stronger inhibitory effect on the pulmonary metastases following i.v. injection of Colon 26 tumor cells than treatment with either cytokine alone. These results suggest that IL-18 combined with IL-2 potentiates in vivo NK cell activity and contributes to inhibition of tumor metastasis without inducing significant toxicity.

Animals↗

PubMed2000

Pentobarbital, but not propofol, suppresses vasopressin-stimulated heat shock protein 27 induction in aortic smooth muscle cells.

BACKGROUND: Although it is known that systemic blood pressure decreases after the administration of pentobarbital or propofol, the mechanisms underlying the cardiovascular effects of these anesthetics are still poorly understood. The authors previously showed that vasopressin stimulates the induction of heat shock protein (HSP) 27, a low-molecular-weight HSP, by a protein kinase C-dependent manner in aortic smooth muscle A10 cells. It is recognized that HSP27 may act as a chaperone like high-molecular-weight HSPs such as HSP70. HSP27 is reportedly associated with agonist-induced contraction of vascular smooth muscle cells. The authors examined the effects of pentobarbital and propofol on the vasopressin-stimulated HSP27 induction in A10 cells. METHODS: Cultured A10 cells were pretreated with pentobarbital or propofol and then stimulated by vasopressin or 12-o-tetradecanoylphorbol 13-acetate (TPA). The effect of vasopressin on HSP70 was evaluated by Western blot analysis and compared with its effect on HSP27. The concentrations of HSP27 were determined by a specific immunoassay. The effect of pentobarbital on the expression levels of mRNA for HSP27 by vasopressin was evaluated by Northern blot analysis. RESULTS: Vasopressin induced HSP27 but had little effect on HSP70. At concentrations used clinically, pentobarbital inhibited the accumulation of HSP27 by vasopressin or TPA. Pentobarbital reduced the levels of mRNA for HSP27 induced by vasopressin. In contrast, propofol affected neither the vasopressin- nor TPA-induced HSP27 accumulation. CONCLUSIONS: These results suggest that pentobarbital suppresses the vasopressin-stimulated HSP27 induction in vascular smooth muscle cells. This inhibitory effect is probably exerted at a point downstream from protein kinase C.

Anesthetics, Intravenous↗