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Biomedical subjects

K Okuda

Publications and source records attributed to K Okuda.

At least 253 records · Page 14Linked to original sources
PubMed1998

[Diagnosis of extension and treatment of carcinoma of the gallbladder].

Diagnosis of extension by intraoperative ultrasonography (IOUS) and treatment based on the degree of histological extension in carcinoma of the gallbladder are discussed. IOUS is a useful technique for the diagnosis of the depth of wall invasion and direct invasion of the liver. The authors diagnose the depth of wall invasion based on the layer structure, unequal width, and discontinuity of the layer echogram. By this technique, mucosal cancer (m cancer) or cancer extending to the proper muscle layer (mp cancer) can be differentiated from cancer with submucosal invasion (ss cancer), and also ss cancer from cancer exposing the serosa (se) or cancer infiltrating to the serosa (si). However, differentiation between m cancer and mp cancer is not possible by IOUS or by other diagnostic techniques. In terms of histological extension, lymph node metastasis or vascular and nerve invasion is not found in m cancer, but in some cases of mp cancer vascular invasion is present. As a radical operative procedure for early m and mp cancer, full-thickness cholecystectomy or partial resection of the liver bed and dissection of lymph nodes 8, 12, and 13 should be conducted. As lymph node metastasis and vascular and nerve invasion are frequent in ss or more advanced cancer, complete lymph node dissection should be performed. Cholecystectomy, partial resection of the liver bed, bile duct resection, and dissection of lymph nodes 8, 12, and 13 is the preferred radical operative procedure for ss cancer. In the cases with in metastasis to lymph nodes 8 and 13, pancreatoduodenectomy is combined. The basic operative procedure for se and si cancer has not been established, but is should be radical and safe. Considering the poor prognosis and frequency of lethal postoperative complications, at present we should not only expand the resected area but select a reasonable and well-balanced operative procedure depending on the degree of cancer extension.

Gallbladder Neoplasms↗
PubMed1998

Relationships between chronic oral infectious diseases and systemic diseases.

There are over 300 species of bacteria forming populations of several hundred billion in the human oral cavity. The number of bacteria reaches a thousand billion when the mouth is not sufficiently cleaned. Using saliva and gingival crevicular fluid as their main nutrients, these bacteria create their ecological niches on tooth surfaces, gingival crevices, saliva, dorsum linguae, and buccal and pharyngeal mucosa, threatening oral and systemic health. It is known that primary lesions of these chronic bacterial infections secondarily cause nephritis, rheumatoid arthritis, and dermatitis. Further, it has been demonstrated in recent years that bacteria inhabiting the oral cavity can cause bacterial pneumonia and endocarditis and that the periodontal-disease-associated bacteria become causative agents for pregnancy troubles and are involved in blood circulation problem and coronary heart disease. Dentistry reviewed the theme of World Health Day, Oral Health for a Healthy Life, in 1994. The 8020 campaign to promote tooth care is also becoming established in Japan; however, the authors emphasized that this achievement is not the goal of dental health care. In this article, we explain the bases supporting the concept that oral health care, primarily mouth cleaning, is important for not only oral disease but also a healthy life.

Bacterial Infections↗
PubMed1997

Signaling functions of the tyrosine residues in the betac chain of the granulocyte-macrophage colony-stimulating factor receptor.

The granulocyte-macrophage colony-stimulating factor (GM-CSF) receptor (GMR) is a heterodimeric receptor expressed by myeloid lineage cells. Binding of GM-CSF activates at least one receptor-associated tyrosine kinase, JAK2, and rapidly induces tyrosine phosphorylation of the GMR betac-chain (GMRbeta), but not the GMR alpha-chain (GMRalpha). To examine the role of GMRbeta tyrosine phosphorylaiton, each of the 8 tyrosine residues in the cytoplasmic domain of the human GMRbeta was mutated to phenylalanine (GMRbeta-F8), and this mutant receptor was expressed with wild-type GMRalpha in the interleukin-3-dependent murine hematopoietic cell line, Ba/F3. GM-CSF induced tyrosine phosphorylation of multiple cellular proteins in cells expressing GMRbeta-F8 , including JAK2 and STAT5. However, GM-CSF-induced tyrosine phosphorylation of both SHP2 and SHC was reduced or absent compared with wild-type. Next, a series of 8 receptors were generated, each containing only a single, restored, tyrosine residue. Tyrosine 577 was found to be sufficient to regenerate GM-CSF-dependent phosphorylation of SHC, and any of Y577, Y612, or Y695 was sufficient to regenerate GM-CSF-inducible phosphorylation of SHP2. Despite the signaling defect to SHC and SHP2, Ba/F3 cells expressing GMRbeta-F8 were still able to proliferate in response to 10 ng/mL of human GM-CSF, although mitogenesis was impaired compared with wild-type GMRbeta, and this effect was even more prominent at lower concentrations of GM-CSF (1 ng/mL). Overall, these results indicate that GMRbeta tyrosine residues are not necessary for activation of the JAK/STAT pathway or for proliferation, viability, or adhesion signaling in Ba/F3 cells, although tyrosine residues significantly affect the magnitude of the response. However, specific tyrosine residues are needed for activation of SHC and SHP2.

Animals↗
PubMed1997

Cationic liposomes are a strong adjuvant for a DNA vaccine of human immunodeficiency virus type 1.

Liposomes have been widely used to enhance the immune response. In the present investigation, we studied their in vivo immunomodulation of an HIV-1-specific DNA vaccine candidate (pCMV160/REV) constructed with the cytomegalovirus (CMV) promoter-conjugated HIV-1 env and rev DNA plasmids. By immunizing with pCMV160/REV and cationic liposomes through various routes (intramuscular, intraperitoneal, subcutaneous, intradermal, and intranasal), we induced higher levels of both antibody production and delayed-type hypersensitivity (DTH) than by using DNA vaccine alone. The HIV-1-specific cytotoxic T lymphocyte (CTL) activity was observed to be stronger on immunization with the DNA vaccine and cationic liposome combination. The intramuscular, intraperitoneal, and intranasal inoculation routes were more effective in inducing strong DTH and antibody responses than the subcutaneous and intradermal routes. Taken together, these results suggest that cationic liposomes can be highly effective when used with DNA vaccines and administered by various routes.

Acquired Immunodeficiency Syndrome↗
PubMed1997

A chimeric receptor/oncogene that can be regulated by a ligand in vitro and in vivo.

The BCR/ABL oncogene encodes an activated tyrosine kinase that causes human chronic myelogenous leukemia. The mechanism of transformation, however, is complex and not well understood. One of the important contributions of BCR to transformation is believed to be dimerization or oligomerization of ABL, thereby activating ABL tyrosine kinase activity. We reasoned that if ABL was dimerized through other mechanisms, activation of the tyrosine kinase activity should also result, and the activated kinase may also be transforming. Erythropoietin is known to activate its receptor by causing dimerization, and therefore a synthetic oncogene was created by linking the extracytoplasmic and transmembrane domains of the EPO receptor with c-ABL. This chimeric receptor was stably expressed in Ba/F3 cells and, in the absence of EPO, had no detectable biological effect on the cells. EPO, however, induced a rapid, dose-dependent activation of ABL tyrosine kinase activity and phosphorylation of several cellular proteins. The major target proteins have been identified, and are very similar to the known substrates of BCR/ABL, including Shc, CBL, CRKL, and several proteins in the cytoskeleton. EPO treatment also resulted in biological effects that were remarkably similar to those of BCR/ABL, including improved viability, altered integrin function, and a weak mitogenic signal. The biological effects were in part dose-dependent, in that low EPO concentrations enhanced viability but did not cause proliferation. At high EPO doses, kinase activation was maximal, and a mitogenic effect was also revealed. In nude mice, Ba/F3 cells expressing this chimeric receptor did not cause detectable disease without administration of pharmacologic doses of EPO. If EPO was given intraperitoneally 5 days a week, however, a dose-dependent lethal leukemia resulted. This ligand-regulatable oncogene mimics some of the biological effects of BCR/ABL, and analysis of ABL mutants in this system will be useful to dissect the signaling pathways that cause CML.

Amino Acid Sequence↗
PubMed1997

Intranasal immunization of a DNA vaccine with IL-12- and granulocyte-macrophage colony-stimulating factor (GM-CSF)-expressing plasmids in liposomes induces strong mucosal and cell-mediated immune responses against HIV-1 antigens.

A DNA vaccine constructed with the CMV promoter conjugated to env gp160 and rev genes has been shown to induce an effective Th1-type immune response when inoculated via an intramuscular route. In the present study, we obtained high levels of both humoral and cell-mediated immune activity by intranasal administration of this DNA vaccine. The production of mucosal IgA Ab in feces and vaginal fluid was stimulated significantly by intranasal DNA administration. This route of administration resulted in a significant level of HIV-1-neutralizing Abs in feces and serum. Cytokine assays revealed that intranasal administration of this DNA vaccine induces a Th2-type immune response. Interestingly, cationic liposomes greatly enhanced these activities. Abs against HIV-1 were present for at least 10 mo. Coadministration of the DNA vaccine with IL-12- and granulocyte/macrophage-CSF-expressing plasmids induced high levels of HIV-specific CTLs and an increase in delayed type hypersensitivity when administered by the intranasal route. These results clearly demonstrate that intranasal administration of this DNA vaccine with liposomes, together with IL-12- and/or granulocyte/macrophage-CSF-expressing plasmids, induces a strong level of anti-HIV-1 immune response.

Administration, Intranasal↗
PubMed1997

Oral bacteria inhibit Helicobacter pylori growth.

Various oral bacterial species were found to inhibit the growth of Helicobacter pylori strains. The growth inhibitory activities of most of these oral bacteria were adversely affected by heating at 80 degrees C for 60 min or by protease treatment, indicating that these bacteria produce bacteriocin-like inhibitory proteins against H. pylori strains. The antagonistic effects of oral bacteria against H. pylori may restrain colonization by this organism in the oral cavity.

Adult↗
PubMed1997

Functional expression of the CXC-chemokine receptor-4/fusin on mouse microglial cells and astrocytes.

The mRNA for the seven-transmembrane-spanning G protein-coupled receptor fusin/CXCR-4 is expressed in primary mouse astrocyte cultures and the transformed mouse microglial cell line, N9. Cell surface expression of fusin in these cells was confirmed by staining with a polyclonal anti-fusin Ab. The functional capacity of this chemokine receptor was examined by evaluating the calcium responses following stimulation of glial cells with the CXC-chemokine, stromal-derived cell factor-1alpha (SDF-1alpha). Both astrocytes and microglial cells mobilized calcium following stimulation with chemically synthesized SDF-1alpha. SDF-1alpha- and carbachol-mediated calcium responses of astrocytes were partially inhibited by treatment with pertussis toxin (PTx), suggesting receptor coupling to a combination of G alpha(i) and other G proteins. In contrast, the calcium responses of microglial cells to SDF-1alpha were completely PTx sensitive, while responses to carbachol stimulation were PTx resistant. The ability of SDF-1alpha to induce glial cell migration was also examined. Synthetic SDF-1alpha was a potent chemoattractant for mouse microglial cells at ligand concentrations of 10 to 500 ng/ml; peak responses were noted at 100 ng/ml. In contrast, astrocytes did not migrate toward a gradient of SDF-1alpha. The failure of SDF-1alpha to induce astrocyte migration was specific, as another chemokine, macrophage inflammatory protein-1alpha, triggered astrocyte chemotaxis.

Animals↗
PubMed1997

Enhancement of cell-mediated immunity against HIV-1 induced by coinnoculation of plasmid-encoded HIV-1 antigen with plasmid expressing IL-12.

Previous investigations have demonstrated that CTL may play an important role in suppressing the disease progression of HIV infection. In this study, we inoculated mice with IL-12 expression plasmid together with plasmid-encoding HIV-1 envelope to enhance CTL activity by activating a Th1-type response. The results of delayed-type hypersensitivity using the footpad swelling response and of CTL activity clearly showed that HIV-1-specific cell-mediated immunity was enhanced by inoculation of the IL-12 expression plasmid. Quantitation of cytokine in the sera of IL-12-inoculated mice revealed that IFN-gamma significantly increased. The enhanced cell-mediated immunity responses were abrogated by combined administration of the IL-12 expression plasmid and neutralizing anti-IFN-gamma Ab. Together, these results suggest that enhanced virus-specific cell-mediated immunity occurred via an endogenously produced IFN-gamma by inoculation of IL-12 expression plasmid.

AIDS Vaccines↗
PubMed1997

Do DNA vaccines induce autoimmune disease?

This report examines whether plasmid DNA vaccines induce the production of anti-DNA or anti-muscle cell autoantibodies. A three-fold increase in the number of B cells secreting immunoglobulin G (IgG) anti-DNA autoantibodies was detected in BALB/c mice immunized and boosted with any of three DNA plasmids (p < 0.004). This correlated with a transient increase in serum anti-DNA autoantibody titers but was not associated with the development of glomerulonephritis or autoimmune disease. None of the DNA vaccines examined stimulated the production of anti-muscle cell autoantibodies or the development of myositis. The effect of DNA vaccines on the development of nascent autoimmunity in lupus-prone (NZB x NZW)F1 mice was also examined. Repeated vaccination did not alter the onset or course of disease in these animals. These findings suggest that DNA vaccines neither initiate nor accelerate the development of systemic autoimmunity.

Animals↗
PubMed1997

Analysis of the glycine binding domain of the NMDA receptor channel zeta 1 subunit.

In an attempt to examine glycine binding domain of the zeta 1 subunit of the mouse N-methyl-D-aspartate (NMDA) receptor channel, we constructed N-terminal or C-terminal deletion mutants of the zeta 1 subunit cDNA and expressed them in Spodoptera frugiperda cells using a baculovirus system. Analysis of binding of a glycine binding site antagonist, 5,7-[3(-3)H]dichlorokynurenate ([3H]DCKA) to the deleted zeta 1 mutants provided the first direct experimental evidence that the regions of N-terminal 282 and C-terminal 102 amino acid residues do not significantly affect glycine binding, and that both the region of approximately 260 amino acid residues preceding the putative transmembrane segment M1 and the region between the segments M3 and M4 are required to form the glycine binding domain.

Animals↗
PubMed1997

Dissection of the promoter/operator region and evaluation of N-acylhomoserine lactone mediated transcriptional regulation of elastase expression in Pseudomonas aeruginosa.

In Pseudomonas aeruginosa, expression of the lasB gene which codes for the metalloprotease, elastase, depends on small diffusible N-acylhomoserine lactones. lasB expression is regulated through the interactions of N-3-oxododecanoyl-L-homoserine lactone and N-butanoyl-L-homoserine lactone with the transcriptional activators LasR and VsmR(RhlR), respectively. To investigate lasB expression further, we first located the transcriptional start site to a position 141 bp upstream from the translational start site. Using this information, we constructed a series of plasmids containing consecutive 5' deletions of the upstream region of lasB fused to a promoterless chloramphenicol acetyltransferase reporter gene. The results obtained indicate that three regions are required for efficient transcription of lasB; a 35 bp palindromic sequence located at +26 to +60 bp upstream from the translation start site, and two regions located upstream of the transcription start site, at -135 to -85 bp and -63 to -26 bp, respectively. Deletion of the latter region results in the loss of both N-butanoyl-L-homoserine lactone- and N-3-oxododecanoyl-L-homoserine lactone-mediated stimulation of lasB expression and provides further support for the role of this operator site as a target for either or both LasR and VsmR.

Bacterial Proteins↗
PubMed1997

Immunomodulatory effects of a plasmid expressing B7-2 on human immunodeficiency virus-1-specific cell-mediated immunity induced by a plasmid encoding the viral antigen.

B7 co-stimulation is essential for activating resting T cells following antigen recognition by the T cell receptor. To determine whether B7 has adjuvant activities on human immunodeficiency virus type-1 (HIV-1)-specific immunity induced by inoculation of a plasmid encoding HIV-1 env and rev (DNA vaccine), B7-1 and B7-2 expression plasmids were co-inoculated with the DNA vaccine. The delayed-type hypersensitivity response and cytotoxic T lymphocyte (CTL) activity were significantly enhanced when B7-2 expression plasmid was co-inoculated with the DNA vaccine, but were unaffected when the B7-1 expression plasmid was used with the vaccine instead. The immunological response enhanced by B7-2 decreased below the level of mice immunized with the DNA vaccine in combination with CTLA4Ig, an inhibitor of the B7/CD28 co-stimulatory signal, suggesting that this signal is critical for the enhanced response induced by co-inoculation of the DNA vaccine and B7-2 expression plasmid. This enhancement appeared to occur via an interferon-gamma (IFN-gamma)-dependent mechanism, as combined administration of the B7-2 plasmid and neutralizing anti-IFN-gamma antibody abrogated the virus-specific cell-mediated immunity. These results suggest that this gene-based co-inoculation strategy using HIV-1 viral antigen and B7-2 co-stimulatory molecule could be a powerful means of combating HIV-1 infection.

AIDS Vaccines↗
PubMed1997

Human immunodeficiency virus type-1-specific immune responses induced by DNA vaccination are greatly enhanced by mannan-coated diC14-amidine.

Use of mannan-coated N-t-butyl-N'-tetradecyl-3-tetradecylamino-propionamidine (diC14-amidine) as an adjuvant for a DNA vaccine encoding glycoprotein 160 of human immunodeficiency virus type-1 (HIV-1) enhanced the antigen-specific immune responses. The role of interferon-gamma (IFN-gamma) and interleukin-12 in the mechanism of adjuvant action was also evaluated. Coating of diC14-amidine with mannan significantly augmented the HIV-specific delayed-type hypersensitivity reaction induced by the immunogenic DNA. HIV-1-specific cytotoxic T lymphocyte activity was also markedly enhanced by the mannan-diC14-amidine cocktail. An immunomodulatory effect of this cocktail was inhibited by treatment with anti-IFN-gamma monoclonal antibody in vivo, which suggests that IFN-gamma plays an important role in inducing cell-mediated immunity by the DNA vaccine containing this adjuvant. The results of both antigen-specific immunoglobulin isotype analysis and cytokine measurement showed that the immunogenic DNA incorporated into mannan-coated diC14-amidine elicits Th1-biased immune responses.

AIDS Vaccines↗
PubMed1997

Strong augment effect of IL-12 expression plasmid on the induction of HIV-specific cytotoxic T lymphocyte activity by a peptide vaccine candidate.

We previously reported that repeated inoculation of VC1, a macromolecular multicomponent peptide vaccine emulsified with Freund's adjuvant (VC1-F), induced high cytotoxic T lymphocyte (CTL) levels and a substantial level of multivalent antibodies which neutralized various human immunodeficiency virus type 1 (HIV-1) isolates. In the present study, we report that inoculation of VC1-F plus interleukin (IL)-12 expression plasmid can induce a higher antigen-specific CTL response compared to that with VC1-F alone. VC1-F plus IL-12 expression plasmid or VC1-F alone were inoculated to BALB/c mice twice at interval of 2 weeks. Two weeks after the second inoculation, spleen effector cells from these mice were examined. Stronger CTL responses against target cells were observed from the inoculation of VC1-F plus IL-12 plasmid than from that with VC-1F alone, but there was no difference in antibody induction. The inoculation of VC1 plus IL-12 plasmid also produced higher CTL activity than the inoculation of VC1 alone. These augmented CTL activities were not observed using target cells pulsed with non-HIV-specific peptides and different class I haplotype cells. These data demonstrate that co-inoculation of cell-mediated immune potent antigen and IL-12 plasmids can enhance the antigen-specific CTL response. This may be a potential approach for the induction of cellular immunization against HIV-1 and other diseases.

AIDS Vaccines↗
PubMed1997

Cloning and sequence analysis of the fimbriae associated protein (fap) gene from Actinobacillus actinomycetemcomitans.

Fimbrial-associated protein, an attachment factor of Actinobacillus actinomycetemcomitans, was genetically analysed by cloning. The plasmid obtained was found to harbor a 1.7kb fragment which contained a 228bp open reading frame encoding 76 amino acids (7.970kDa). The fimbriae associated protein gene (fap) was strongly expressed in fimbriated A. actinomycetemcomitans 310a but not in non-fimbriated strains.

Aggregatibacter actinomycetemcomitans↗
PubMed1997

Adherence of oral streptococci to an immobilized antimicrobial agent.

An antimicrobial agent, 3-(trimethoxysilyl)-propyldimethyloctadecyl ammonium chloride, was immobilized on silica. Interaction between the material (termed) OAIS) and various oral bacterial species were then studied. Seven species of Streptococcus and two Actinomyces were investigated for their ability to adhere to this biomaterial. Cell-surface hydrophobicity and zeta-potential were examined as well. Analysis of extracted hydrophobic proteins which adhered to OAIS revealed that the adherence of these micro-organisms was closely related to the hydrophobicity of their cell surfaces. The results of zeta-potential assays indicated that negative charge on the cell surface inhibited adherence to OAIS. Gel electrophoresis revealed that OAIS could absorb cell-surface hydrophobic proteins from all bacterial species tested. Preadsorption of hydrophobic components on the cell surface inhibited adherence of the Strep. mutans strain to OAIS in a dose-dependent manner. The results indicate that OAIS adsorption of these oral bacteria was dependent on the degree of hydrophobicity of their surfaces. A major component of this adherence was hydrophobic cell-surface proteins.

Absorption↗