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Biomedical subjects

Yasuo Kubota

Publications and source records attributed to Yasuo Kubota.

At least 19 recordsLinked to original sources
PubMed2006

Hydrogen peroxide induces S1P1 receptors and sensitizes vascular endothelial cells to sphingosine 1-phosphate, a platelet-derived lipid mediator.

Sphingosine 1-phosphate (S1P) is a platelet-derived angiogenic lipid growth factor, modulating G-protein-coupled S1P(1) receptors (S1P(1)-R) to activate endothelial nitric oxide synthase (eNOS), as well as MAPK pathways in endothelial cells. We explored whether and how hydrogen peroxide (H(2)O(2)), a representative reactive oxygen species, alters S1P(1)-R expression and influences S1P signaling in cultured bovine aortic endothelial cells (BAECs). When BAECs are treated with pathophysiologically relevant concentrations of H(2)O(2) (150 microM for 30 min), S1P(1)-R protein expression levels are acutely augmented by approximately 30-fold in a dose-dependent fashion. When BAECs have been pretreated with H(2)O(2), subsequent S1P stimulation (100 nM) leads to a higher degree of eNOS enzyme activation (assessed as intracellular cGMP content, 1.7 +/- 0.2-fold vs. no H(2)O(2) pretreatment groups, P < 0.05), associated with a higher magnitude of phosphorylation responses of eNOS and MAPK ERK1/2. PP2, an inhibitor of Src-family tyrosine kinase, abolished the effects of H(2)O(2) on both S1P(1)-R protein upregulation and enhanced BAEC responses to S1P. H(2)O(2) does not augment S1P(1) mRNA expression, whereas VEGF under identical cultures leads to increases in S1P(1) mRNA signals. Whereas H(2)O(2) attenuates proliferation of BAECs, addition of S1P restores growth responses of these cells. These results demonstrate that extracellularly administered H(2)O(2) increases S1P(1)-R expression and promotes endothelial responses for subsequent S1P treatment. These results may identify potentially important points of cross-talk between reactive oxygen species and sphingolipid pathways in vascular responses.

Animals↗
PubMed2006

Effects of skin care and makeup under instructions from dermatologists on the quality of life of female patients with acne vulgaris.

Acne vulgaris significantly affects patients' quality of life (QOL) and their lives in various ways, including social behavior and body dissatisfaction. This may be heightened by acne's typical involvement of the face. We investigated whether the use of skin care and makeup could influence the QOL of affected patients without deteriorating conventional acne treatments. Fifty female patients with acne were recruited for our study. Twenty-five patients were instructed how to use skin care and cosmetics, while 25 patients received no specific instructions from dermatologists. Both groups received conventional topical and/or oral medication for acne during the study period for 4 weeks. Both groups did not show any significant difference in clinical improvement of acne severity. Two validated QOL questionnaires, World Health Organization (WHO)QOL26 and the Dermatology Life Quality Index (DLQI) were administered to all patients at first visit and 4 weeks later. The mean scores of psychological and overall domains in WHOQOL26 for patients with instructions were improved significantly, while only the overall score was significantly improved for patients without instructions. The total mean scores and all domains except work/school in DLQI for patients with instructions were improved significantly, while the total scores and all domains except discomfort for treatment in DLQI were significantly improved for patients without instructions. Thus, instructions on the use of skin care and cosmetics for female acne patients did not deteriorate acne treatment and influenced patients' QOL effectively. We therefore suggest that instructions for using skin care and cosmetics complement conventional medical treatments for acne.

Acne Vulgaris↗
PubMed2005

Activity of striatal neurons reflects dynamic encoding and recoding of procedural memories.

Learning to perform a behavioural procedure as a well-ingrained habit requires extensive repetition of the behavioural sequence, and learning not to perform such behaviours is notoriously difficult. Yet regaining a habit can occur quickly, with even one or a few exposures to cues previously triggering the behaviour. To identify neural mechanisms that might underlie such learning dynamics, we made long-term recordings from multiple neurons in the sensorimotor striatum, a basal ganglia structure implicated in habit formation, in rats successively trained on a reward-based procedural task, given extinction training and then given reacquisition training. The spike activity of striatal output neurons, nodal points in cortico-basal ganglia circuits, changed markedly across multiple dimensions during each of these phases of learning. First, new patterns of task-related ensemble firing successively formed, reversed and then re-emerged. Second, task-irrelevant firing was suppressed, then rebounded, and then was suppressed again. These changing spike activity patterns were highly correlated with changes in behavioural performance. We propose that these changes in task representation in cortico-basal ganglia circuits represent neural equivalents of the explore-exploit behaviour characteristic of habit learning.

Acoustic Stimulation↗
PubMed2004

Dynamic analysis of learning in behavioral experiments.

Understanding how an animal's ability to learn relates to neural activity or is altered by lesions, different attentional states, pharmacological interventions, or genetic manipulations are central questions in neuroscience. Although learning is a dynamic process, current analyses do not use dynamic estimation methods, require many trials across many animals to establish the occurrence of learning, and provide no consensus as how best to identify when learning has occurred. We develop a state-space model paradigm to characterize learning as the probability of a correct response as a function of trial number (learning curve). We compute the learning curve and its confidence intervals using a state-space smoothing algorithm and define the learning trial as the first trial on which there is reasonable certainty (>0.95) that a subject performs better than chance for the balance of the experiment. For a range of simulated learning experiments, the smoothing algorithm estimated learning curves with smaller mean integrated squared error and identified the learning trials with greater reliability than commonly used methods. The smoothing algorithm tracked easily the rapid learning of a monkey during a single session of an association learning experiment and identified learning 2 to 4 d earlier than accepted criteria for a rat in a 47 d procedural learning experiment. Our state-space paradigm estimates learning curves for single animals, gives a precise definition of learning, and suggests a coherent statistical framework for the design and analysis of learning experiments that could reduce the number of animals and trials per animal that these studies require.

Algorithms↗
PubMed2004

Identification of intracellular target proteins of the calcium-signaling protein S100A12.

In this report, we have focused our attention on identifying intracellular mammalian proteins that bind S100A12 in a Ca2+-dependent manner. Using S100A12 affinity chromatography, we have identified cytosolic NADP+-dependent isocitrate dehydrogenase (IDH), fructose-1,6-bisphosphate aldolase A (aldolase), glyceraldehyde-3-phosphate dehydrogenese (GAPDH), annexin V, S100A9, and S100A12 itself as S100A12-binding proteins. Immunoprecipitation experiments indicated the formation of stable complexes between S100A12 and IDH, aldolase, GAPDH, annexin V and S100A9 in vivo. Surface plasmon resonance analysis showed that the binding to S100A12, of S100A12, S100A9 and annexin V, was strictly Ca2+-dependent, whereas that of GAPDH and IDH was only weakly Ca2+-dependent. To localize the site of S100A12 interaction, we examined the binding of a series of C-terminal truncation mutants to the S100A12-immobilized sensor chip. The results indicated that the S100A12-binding site on S100A12 itself is located at the C-terminus (residues 87-92). However, cross-linking experiments with the truncation mutants indicated that residues 87-92 were not essential for S100A12 dimerization. Thus, the interaction between S100A12 and S100A9 or immobilized S100A12 should not be viewed as a typical S100 homo- or heterodimerization model. Ca2+-dependent affinity chromatography revealed that C-terminal residues 75-92 are not necessary for the interaction of S100A12 with IDH, aldolase, GAPDH and annexin V. To analyze the functional properties of S100A12, we studied its action in protein folding reactions in vitro. The thermal aggregation of IDH or GAPDH was facilitated by S100A12 in the absence of Ca2+, whereas in the presence of Ca2+ the protein suppressed the aggregation of aldolase to less than 50%. These results suggest that S100A12 may have a chaperone/antichaperone-like function which is Ca2+-dependent.

Amino Acid Sequence↗
PubMed2003

Ascorbate enhances iNOS activity by increasing tetrahydrobiopterin in RAW 264.7 cells.

Studies on the effect of ascorbic acid on inducible nitric oxide synthase (iNOS) activity are few and diverse, likely to be dependent on the species of cells. We investigated a role of ascorbic acid in iNOS induction and nitric oxide (NO) generation in mouse macrophage cell line RAW 264.7. Although interferon- (IFN-) gamma alone produced NO end products, ascorbic acid enhanced NO production only when cells were synergistically stimulated with IFN-gamma plus Escherichia coli lipopolysaccharide (LPS). Ascorbate neither enhanced nor decreased the expression of iNOS protein in RAW 264.7 cells, in contrast to the reports that ascorbic acid augments iNOS induction in a mouse macrophage-like cell line J774.1 and that ascorbate suppresses iNOS induction in rat skeletal muscle endothelial cells. Intracellular levels of tetrahydrobiopterin (BH4), a cofactor for iNOS, were increased by ascorbate in RAW 264.7 cells. However, ascorbate did not increase GTP cyclohydrolase I mRNA, the main enzyme at the critical steps in the BH4 synthetic pathway, expression levels and activity. Sepiapterin, which supplies BH4 via salvage pathway, more efficiently enhanced NO production if ascorbate was added. These data suggest that enhanced activation of iNOS by ascorbic acid is mediated by increasing the stability of BH4 in RAW 264.7 cells.

Animals↗
PubMed2003

Effects of high glucose on NO synthesis in human keratinocyte cell line (HaCaT).

BACKGROUND: There is a possibility that alteration of nitric oxide (NO) synthesis by high glucose leads to a variety of diabetic complications. OBJECTIVE: In this study, we examined whether NO synthesis is altered by high glucose in spontaneously immortalized human keratinocyte cell line (HaCaT) that have three isoforms of NO synthases (NOS). METHODS: We measured NO end product nitrite in the culture medium using the Griess reagent and analyzed mRNA expression of three isoforms of NOS in HaCaT cells by RT-PCR. RESULTS: High glucose enhanced constitutively produced NO production in HaCaT cells, which persisted for 10 days and was attenuated by an inhibitor of protein kinase C (PKC), without altering eNOS/nNOS mRNA levels. Cytokine stimulation induced iNOS mRNA in HaCaT cells. Pretreatment with high glucose for 24 h enhanced cytokine-induced NO production in HaCaT cells. However, when these cells were exposed to high glucose for 10 days, cytokine treatment did not induce iNOS mRNA and nitrite production. CONCLUSION: These diverse alterations in NO production by high glucose may be involved in impaired host-defense and wound healing in the skin of diabetic patients.

Cell Line↗
PubMed2003

Dyshidrosiform pemphigoid: report of a case.

A Japanese woman had bullous eruptions on her palms and soles for two months, histopathologic examination, immunofluorescence microscopy, and ELISA for BP180 antigen led to the definitive diagnosis of dyshidrosiform pemphigoid (DP). This paper also includes a study of 15 other cases of DP.

Aged↗
PubMed2002

Guest-induced organization of an optimal receptor from a dynamic receptor library: spectroscopic screening.

Complexation of a cis-protected palladium ion and a family of exo-bidentate and -tridentate ligands results in the formation of an equilibrium mixture of numerous metal-linked receptors that are referred to as a dynamic receptor library. We found that a guest induced the selective formation of the optimal receptor of its own. Screening of the library by using difference NMR facilitates the search for new receptors because in difference NMR only receptors interacting with the guest can be observed. An unpredictable heterotopic receptor was discovered by this screening method. Interestingly, the new receptor thus found was assembled quantitatively only in the presence of its optimal guest.

Chemistry↗
PubMed2002

Interaction of S100 proteins with the antiallergic drugs, olopatadine, amlexanox, and cromolyn: identification of putative drug binding sites on S100A1 protein.

S100 proteins are a multigenic family of low-molecular-weight Ca(2+)-binding proteins comprising 19 members. These proteins undergo a conformational change by Ca(2+)-binding and consequently interact with their target proteins. Recently, we reported that two antiallergic drugs, Amlexanox and Cromolyn, bind to S100A12 and S100A13 of the S100 protein family. In the present study, we used a newly developed antiallergic drug, Olopatadine, as a ligand for affinity chromatography and examined binding specificity of the drug to S100 protein family. Olopatadine binds specifically to S100 proteins, such as S100A1, S100B, S100L, S100A12, and S100A13, in a Ca(2+)-dependent manner but not to calmodulin. Mutagenesis study showed that amino acid residues 76-85 in S100A1 are necessary for its binding to Olopatadine. In contrast, residues 89-94 were identified as an Amlexanox-binding site in S100A1. Moreover, Olopatadine did not competitively inhibit S100A1-binding site of Amlexanox. Furthermore, we showed that Olopatadine inhibited the binding of S100A1 target protein's binding site peptides to S100A1. These results indicate that C-terminal region of S100A1 is important for antiallergic drug binding, although the drug binding sites are different according to each antiallergic drug. Differences in the binding sites of S100A1 to antiallergic drugs suggest that the regulatory functions of S100 proteins may exist in several regions. Therefore, these drugs may serve as useful tools for evaluating the physiological significance of S100 protein family.

Aminopyridines↗
PubMed2002

CD35 expression on peripheral blood granulocytes of patients with atopic dermatitis.

We examined CD35 expression on granulocytes from 45 patients with atopic dermatitis (AD) (male, 21, female, 24) and 25 age and sex-matched controls (male, 15; female, 10). There was no significant difference in the peripheral blood neutrophil count between AD patients and controls, whereas the eosinophil count in AD patients was significantly higher than that of controls. The percentages of CD35 positive eosinophils and neutrophils were determined by using two-color flow cytometric analysis. As regards eosinophils, we found CD35 expression from AD patients to be lower than that of controls (P < 0.05), but there was no correlation between the CD35 expression and disease severity. In contrast, the CD35 expression on neutrophils from AD patients was much lower than that of controls (P < 0.005). Furthermore, CD35 expression on neutrophils of severe AD group was significantly higher than that of the mild AD group (P < 0.05). This suggests that the CD35 expression of neutrophils but not eosinophils reflects disease severity in AD patients and the CD35 expression on neutrophils in AD patients may associate with susceptibility to bacterial infection.

Administration, Oral↗
PubMed2002

Fibronectin combined with stem cell factor plays an important role in melanocyte proliferation, differentiation and migration in cultured mouse neural crest cells.

Stem cell factor (SCF) is essential to the migration and differentiation of melanocytes during embryogenesis because mutations in either the SCF gene, or its ligand, KIT, result in defects in coat pigmentation in mice. Using a neural crest cell (NCC) primary culture system from wild-type mice, we previously demonstrated that KIT-positive and/or L-3, 4-dihydroxyphenylalanine (DOPA)-positive melanocyte precursors proliferate following the addition of SCF to the culture medium. Extracellular matrix (ECM) proteins are considered to play a role in the migration and differentiation of various cells including melanocytes. We cultured mouse NCCs in the presence of SCF in individual wells coated with ECM; fibronectin (FN), collagen I (CLI), chondroitin sulphate, or dermatan sulphate. More KIT-positive cells and DOPA-positive cells were detected in the presence of SCF on ECM-coated wells than on non-coated wells. A statistically significant increase in DOPA-positive cells was evident in FN and CLI wells. In contrast, in the absence of SCF, few DOPA-positive cells and KIT-positive cells were detected on either the ECM-coated or non-coated wells. We concluded that ECM affect melanocyte proliferation and development in the presence of SCF. To determine the key site of FN function, RGDS peptides in the FN sequence, which supports spreading of NCCs, were added to the NCC culture. The number of DOPA-positive cells decreased with RGDS concentration in a dose-dependent fashion. Immunohistochemical staining revealed the presence of integrin alpha5, a receptor of RGDS, in NCCs. These results suggest the RGDS domain of FN plays a contributory role as an active site in the induction of FN function in NCCs. In addition, we examined the effect of FN with SCF on the NCC migration by measuring cluster size, and found an increase in size following treatment with FN.

Animals↗