Search PubMed⌕ Search

Biomedical subjects

S Toda

Publications and source records attributed to S Toda.

At least 37 records · Page 2Linked to original sources
PubMed2001

Immunologic characterization of HIV-specific DNA vaccine.

We developed a method for applying HIV-1 DNA vaccine topically in mice. Topical application of DNA vaccine to the skin is useful against infections. To find a less expensive and less cumbersome vaccination method, we administered HIV-1 DNA vaccine to the skin of mice after elimination of keratinocytes using a fast-acting adhesive. HIV-1 DNA vaccine induced high levels of both humoral and cell-mediated immune activity against HIV-1 envelope antigen. A high level of HIV-1-specific cytotoxic T lymphocyte response was also observed, and a high level of IFN-gamma and IL-4 production was induced by the improved skin application of DNA vaccine. High levels of both HIV-specific cytotoxic T lymphocyte and delayed type hypersensitivity in topical application were induced by coadministration of the DNA vaccine with IL-12 expression plasmids and granulocyte-macrophage colony-stimulating factor expression plasmids. These immune responses were inhibited by intradermal injection of anti-CD11c or anti-I-A/I-E antibody. Therefore, topical administration of DNA vaccine is an effective route, and may be very useful for the prevention of infectious diseases.

Adjuvants, Immunologic↗
PubMed2001

Morphogenesis of MDCK cells in a collagen gel matrix culture under stromal adipocyte-epithelial cell interaction.

BACKGROUND: The stromal-epithelial cell interaction is essential for epithelial morphogenesis. Recently, the specific stromal cell type adipocytes, which abundantly exist in perirenal adipose tissue, have been suggested to affect the biological behavior of some epithelial cell types. However, adipocyte-renal epithelial cell interaction remains unclear. We thus examined the effects of adipocytes on the morphogenesis of renal epithelial cells. METHODS: The renal epithelial cell line, Madin-Darby canine kidney (MDCK), cells were cultured in three-dimensional collagen gel matrix with or without mature unilocular adipocytes. Cultures cells were examined by histochemistry, immunohistochemistry, and electron microscopy. RESULTS: Adipocytes extensively promoted the tubule formation of MDCK cells in two different manners. In the first type, after approximately 20% of MDCK cells actively adhered to adipocytes; they organized double-cell structured tubules between the adipocytes and the gel, contacting directly with the entire surface of the adipocytes. In the second type, approximately 70% of MDCK cells apart from adipocytes also formed tubules that had no contact with adipocytes. The component cells of both tubule types at the apical side showed microvilli and peanut agglutinin lectin-positive stain. These cells at the basal side had the basal lamina and type IV collagen-positive stain. CONCLUSIONS: These results indicate that the specific stromal cell type adipocytes cause MDCK cells to organize the well-polarized tubular structures in two different manners according to their direct and indirect interactions, suggesting that adipocytes may be involved in the regulatory mechanism of renal epithelial morphogenesis.

3T3 Cells↗
PubMed2001

Microvolt T wave alternans in human cardiac hypertrophy: electrical instability and abnormal myocardial arrangement.

INTRODUCTION: Although T wave alternans (TWA) is a promising risk marker for myocardial electrical instability, it remains unclear how the presence of TWA is related to myocardial damage. METHODS AND RESULTS: TWA was measured in 28 patients with hypertrophic cardiomyopathy (HCM), 29 patients with hypertensive left ventricular hypertrophy (HLVH), and 15 normal volunteers using a CH2000 system. The amplitude of TWA (Valt) was measured at the lead with the maximum amplitude. Cardiac biopsy was performed in 12 HCM patients, who were divided into two groups (severe and mild) based on histologic findings of myocardial disarray and fibrosis. TWA was positive (Valt > 1.9 microV) in 61% of HCM and 31% of HLVH, despite a nearly identical left ventricular mass index (176 +/- 65 g/m2 vs 175 +/- 39 g/m2). Valt at heart rate = 110 beats/min was significantly greater in HCM with severe disarray and fibrosis than in HCM with mild disarray and in HLVH. CONCLUSION: In HCM patients, a positive TWA test probably is related to abnormal myocardial arrangement (disarray) and/or fibrosis, and it may reflect electrical instability of the myocardium.

Aged↗
PubMed2001

Electroporation in a model of cardiac defibrillation.

INTRODUCTION: It is known that high-strength shock disrupts the lipid matrix of the myocardial cell membrane and forms reversible aqueous pores across the membrane. This process is known as "electroporation." However, it remains unclear whether electroporation contributes to the mechanism of ventricular defibrillation. The aim of this computer simulation study was to examine the possible role of electroporation in the success of defibrillation shock. METHODS AND RESULTS: Using a modified Luo-Rudy-1 model, we simulated two-dimensional myocardial tissue with a homogeneous bidomain nature and unequal anisotropy ratios. Spiral waves were induced by the S1-S2 method. Next, monophasic defibrillation shocks were delivered externally via two line electrodes. For nonelectroporating tissue, termination of ongoing fibrillation succeeded; however, new spiral waves were initiated, even with high-strength shock (24 V/cm). For electroporating tissue, high-strength shock (24 V/cm) was sufficient to extinguish ongoing fibrillation and did not initiate any new spiral waves. Weak shock (16 to 20 V/cm) also extinguished ongoing fibrillation; however, in contrast to the high-strength shock, new spiral waves were initiated. Success in defibrillation depended on the occurrence of electroporation-mediated anodal-break excitation from the physical anode and the virtual anode. Some excitation wavefronts following electrical shock used a deexcited area with recovered excitability as a pass-through point; therefore, electroporation-mediated anodal-break excitation is necessary to block out the pass-through point, resulting in successful defibrillation. CONCLUSION: The electroporation-mediated anodal-break excitation mechanism may play an important role in electrical defibrillation.

Action Potentials↗
PubMed2001

Comparison of antioxidative and chelating effects of daidzein and daidzin on protein oxidative modification by copper in vitro.

Daidzein and its glycoside daidzin are isoflavones. Their antioxidative effects were compared in vitro. Although both compounds inhibited protein oxidative modification by copper, the inhibitory effect of daidzein was stronger than that of daidzin. Because daidzein showed a greater affinity for Cu2+, the antioxidant effect of these isoflavones may be dependent on their respective copper-chelating abilities.

Antioxidants↗
PubMed2001

Inhibitory effects of echinoisoflavanone and sophoraisoflavanone D in Sophora chrysophylla SEEM on lipid peroxidation of mice brain homogenate by interaction of ferrous ion and hydrogen peroxide, in vitro.

We present the results of an in vitro investigation of the inhibitory effects of echinoisoflavanone and sophoraisoflavanone D isolated from Sophora chrysophylla SEEM on lipid peroxidation of mice brain homogenate by interaction of ferrous ion and hydrogen peroxide, in vitro. They inhibited lipid peroxidation. The order of inhibitory effects of these isoflavanones and mannitol as a hydroxy radical scavenger was echinoisoflavanone > mannitol > sophoraisoflavanone D. The results suggest that some isoflavanones may be of use in cases where oxidative stress is present.

Animals↗
PubMed2001

Inhibitory effects of licoisoflavones A and B and sophoraisoflavone A of Sophra mooracroftiana Beth ex Baker on copper-ion-induced protein oxidative modification of mice brain homogenate, in vitro.

We present the results of an in vitro investigation of the inhibitory effects of licoisoflavones A and B and sophoraisoflavone A isolated from Sophra mooracroftiana BETH ex BAKER on copper-induced protein oxidative modification of mice brain homogenate in vitro. Although inhibitory effect of sophoraisoflavone A was stronger than those of licoisoflavones A and B, genistein as a related isoflavone, and mannitol as a hydroxy radical scavenger, inhibitory effects of licoisoflavones A and B were weaker than those of genistein and mannitol. These results demonstrated that the difference of inhibitory effects are dependent on the relation between chemical structures of these isoflavones, such as hydroxy group or benzopyran, and oxidative stress.

Animals↗
PubMed2001

Cellular integration of thyrocytes and thyroid folliculogenesis: a perspective for thyroid tissue regeneration and engineering.

Thyroid gland is composed of many spheroid structures called thyroid follicles, in which thyrocytes are integrated in their specific structural and functional polarization. In conventional monolayer and floating cultures, the cells cannot reorganize follicle structures with normal polarity. By contrast, in a 3-D collagen gel culture thyrocytes easily and stably reconstruct follicles with physiological polarity. Integration of thyrocyte growth and differentiation appears to result in eventual thyroid folliculogenesis. 3-D collagen gel culture and subacute thyroiditis, a specific thyroid disorder, are the promising models for addressing the mechanism of thyroid folliculogenesis. Because formation of 3-D follicles actively occurs both in this culture system and at the regenerative stage of the disease. The understanding of the mechanistic basis of folliculogenesis is prerequisite for establishment of an artificial thyroid tissue, which would enable a more physiological approach to the treatment of hypothyroidism caused by various diseases and surgical processes than conventional hormone replacement therapy. In this review, we have discussed thyrocyte integration, and thyroid folliculogenesis and tissue regeneration, to further thyroid biology. Also, we briefly discussed a perspective on thyroid tissue regeneration and engineering.

Animals↗
PubMed2000

Reciprocal expression of infant- and adult-preferring transcripts of CDCrel-1 septin gene in the rat neocortex.

We report here the isolation and characterization of cDNA clones for a novel isoform of CDCrel-1 septin, termed CDCrel-1A, with a different 5' end sequence from the transcripts encoding the known CDCrel-1 (designated as CDCrel-1F) in the developing rat neocortex. Alternative polyadenylation site selections resulted in various transcripts for CDCrel-1A including the fusion forms with another gene, platelet glycoprotein Ibbeta (GPIbbeta). Expression of the distinct transcripts encoding CDCrel-1A and CDCrel-1F increased and decreased, respectively, from the infant to adult period. Therefore CDCrel-1A might be a major form of the CDCrel-1 septin in the adult neocortex of mammals.

Amino Acid Sequence↗
PubMed2000

An air-liquid interface promotes the differentiation of gastric surface mucous cells (GSM06) in culture.

The gastric surface epithelium is situated at an air-liquid interface because the luminal surface of the alimentary tract is in continuity with the air phase. However, the effects of this microenvironment on the gastric epithelium remain unclear. The aim of this study was to clarify the effects of an air-liquid interface on gastric epithelial cell biology. Gastric surface mucous cells (GSM06) were cultured at an air-liquid interface. Cultured cells were examined by histology, histochemistry, and transmission electron microscopy. When the cells were cultured at an air-liquid interface, the surface cells on the collagen gel became tall columnar and secreted periodic acid-Shiff-positive substances at the apical surface. These cells indicated many mucous granules in the apical cytoplasm and organized the basal lamina at the contact side with the gel. In contrast, under immersed condition, the surface cells showed immature features. This is the first report of an air-liquid interface promoting the differentiation of gastric surface mucous cells in a reconstruction culture of the gastric surface epithelial layer, suggesting that an air-liquid interface may function as a crucial luminal factor to maintain the homeostasis of gastric mucosa.

Air↗
PubMed2000

Heightened odds of large earthquakes near istanbul: An interaction-based probability calculation

We calculate the probability of strong shaking in Istanbul, an urban center of 10 million people, from the description of earthquakes on the North Anatolian fault system in the Marmara Sea during the past 500 years and test the resulting catalog against the frequency of damage in Istanbul during the preceding millennium. Departing from current practice, we include the time-dependent effect of stress transferred by the 1999 moment magnitude M = 7.4 Izmit earthquake to faults nearer to Istanbul. We find a 62 +/- 15% probability (one standard deviation) of strong shaking during the next 30 years and 32 +/- 12% during the next decade.

Journal Article↗
PubMed2000

Air exposure promotes fibroblast growth with increased expression of mitogen-activated protein kinase cascade.

Subepithelial tissue cell types in vivo are separated from air by the surface-covering epithelial layer of various organs, e.g., the skin, cornea, and respiratory and upper alimentary tracts. The epithelial defect caused by inflammatory, traumatic or surgical injury would be expected to expose the subepithelial tissue-localized fibroblasts to influx air. However, it is unclear what effects air stimulation elicits in fibroblast growth, which is critical for wound healing. To address this question, we examined the proliferation of 3T3 fibroblasts with bromodeoxyuridine (BrdU) uptake, using fibroblast-embedded collagen gel culture with or without air exposure. The BrdU intake of air-exposed fibroblasts was about 6 times that of air-nonexposed cells. To further characterize this fibroblast growth, we examined the expression of mitogen-activated protein kinase (MAPK) cascade, which plays a key role in the growth-signaling pathway of various cell types. Immunohistochemistry and Western blotting showed that air exposure increased MAPK cascade expression of the cells more strongly than air nonexposure. The data indicate that air exposure promotes MAPK cascade-associated fibroblast growth, suggesting in turn that in wound repair air stimulation itself may be involved in the basic mechanisms of subepithelial fibroblast proliferation and that it may be related to the pathogenesis of excessive fibroplasia through fibroblast overgrowth.

3T3 Cells↗
PubMed2000

Inhibitory effects of astragali radix, crude drug in Oriental medicines on lipid peroxidation and protein oxidative modification of mouse brain homogenate by copper.

Astragali Radix, the root of Astragalus membranaceus Bunge, is a crude drug used widely in Oriental medicines. It is a major component of Ougi-Keishi-gomotsu-to, a traditional herbal medicine, used for neurop patients with abnormal sensations and neuropathic pain of the legs. It was shown to have inhibitory effects on lipid peroxidation and protein oxidative modification by copper. The effects were similar to and stronger than those of mannitol and superoxide dismutase as free radical scavengers. These results demonstrated that Astragali Radix has inhibitory effects on oxidative stress induced by metal.

Animals↗
PubMed2000

Molecular cloning and characterization of a microsatellite locus found in an RAPD marker of a spider mite, Panonychus citri (Acari: Tetranychidae).

Genetic markers were searched using PCR with 40 kinds of decanucleotide primers to investigate DNA polymorphism in Panonychus citri. A region consisting of a variable number of CT tandem repeats (microsatellite) was found in a fragment amplified with the OPB10 primer. The microsatellite differed in size by ca. 100bp among several P. citri populations screened and was derived from at least seven alleles. This region was characteristic of P. mori and P. osmanthi, but was lacking in P. ulmi. The flanking regions were highly conserved among these species.

Alleles↗
PubMed2000

Interspecific diversity of mitochondrial COI sequences in Japanese Panonychus species (Acari: Tetranychidae).

Sequences of a part of the mitochondrial cytochrome oxidase subunit I (COI) gene were analyzed in four Japanese Panonychus species to determine their phylogenetic relationships. Neighbor-Joining and maximum likelihood analysis resulted in a high bootstrap support of the relationships within the genus Panonychus. In contrast with a previous study based on ribosomal DNA data, the COI phylogeny suggested that P. mori was more distantly related to P. citri than to P. ulmi. This study shows for the first time that P. osmanthi is closely related to P. citri. Intraspecific variation analysis shows that the genetic distance between two local populations of P. mori is higher than between P. citri and P. osmanthi.

Animals↗
PubMed2000

Expression of H type 1 antigen of ABO histo-blood group in normal colon and aberrant expressions of H type 2 and H type 3/4 antigens in colon cancer.

We have immunohistochemically examined the distribution of the H antigens of type 1, type 2 and type 3/4 chains of the ABO(H) histo-blood group system in human normal colon and in colon cancer using three monoclonal antibodies specific for each of the H type 1/2, H type 2, and the H type 3/4 chain. We unexpectedly found that mucosa of the normal colon from secretors but not that from nonsecretors expressed only H type 1 and did not express H type 2 or H type 3/4. The H type 1 was expressed in goblet cells. Positive goblet cells expressing H type 1 were decreased in number progressively from the proximal colon to the rectum. In tumors, 4 (57%) of 7 cancer tissues of the proximal colon from secretors expressed no H type 1, whereas all 8 cancer tissues of the distal colon from secretors expressed H type 1. The aberrant expressions of H type 2 and H type 3/4 (47 and 67%, respectively) were found in cancer tissues from both the proximal and the distal colon. Tumors from nonsecretors did not express any H antigens. Our results suggested that the expression of H type 1 in the normal colon and the aberrant expressions of H type 2 and H type 3/4 in colon cancer tissues were regulated by FUT2-encoded Se type alpha(1,2)fucosyltransferase. However, UEA-I-positive substance(s) rather than H type 2 were uniquely expressed throughout the normal colon and in colon cancers from both secretors and nonsecretors.

ABO Blood-Group System↗
PubMed2000

8 Br-cAMP enhances both humoral and cell-mediated immune responses induced by an HIV-1 DNA vaccine.

From a series of preclinical studies and animal experiments, we have been able to demonstrate that DNA vaccines are a promising tool in strategies for protecting hosts from a variety of infectious diseases. Since the promoter activity of the human cytomegalovirus immediate-early promoter/ enhancer (CMV promoter) is known to be responsive to an elevation in the level of intracellular cAMP, we hypothesized that use of cAMP analogue (8-Bromo adenosine 3'5'-cyclic monophosphate, 8 Br-cAMP) would increase the level of transgene expression supported by the CMV, and enhance the ability of DNA vaccines to evoke an immune response against the transgene product in vivo. To evaluate this hypothesis, immune responses against HIV-1 envelope protein, gp160, an immunogenic HIV-1 component expressed under the control of the CMV promoter, were evaluated in BALB/c mice with or without stimulation by 8 Br-cAMP. DNA vaccine with 8 Br-cAMP was intramuscularly (i.m.) or intranasally (i.n.) administered to BALB/c mice twice on days 0 and 14. Regardless of which route was used, the combination increased the serum IgG antibody (Ab) titer, HIV-1-specific cytotoxic T lymphocyte (CTL) activity and the delayed-type hypersensitivity (DTH) response, compared with the effect of using the vaccine alone. When administered via the i.n. route, the combination also remarkably increased the titer of secretory IgA (sIgA). Moreover, it induced increased production of interferon-gamma with reduction in IL-4 synthesis, and decreased the ratio of serum IgG1/IgG2a. However, these enhancements were not observed when 8 Br-cAMP was coadministered with peptide vaccine or protein antigen. These data suggest that 8 Br-cAMP is able to enhance both humoral and cellular immune responses induced by the DNA vaccine. The induction of T helper type 1 (Th1) immunity against HIV-1 was also enhanced by coadministration of 8 Br-cAMP. A CAT assay study demonstrated that the adjuvant effect of 8 Br-cAMP may be due to the activation of the CMV promoter in the DNA vaccine. The virus challenge experiment in a mouse influenza model also proved our hypothesis.

8-Bromo Cyclic Adenosine Monophosphate↗