Biomedical subjects

K Shinkai

Publications and source records attributed to K Shinkai.

At least 37 records · Page 2Linked to original sources

PubMed1999

[Treatment with 5-FU modulated by low-dose CDDP for advanced cancers and recurrent cases of metastasis].

Advanced gastric, colon and esophageal cancers (n = 21) were treated with 5-FU (250 mg) modulated by CDDP (5 mg). The reductive ratio of tumor was 6/21 (28.6%). Six cases of partial response (PR) were limited with no surgical treatment and exploratory laparotomy of all cases, and the effectiveness rate was 54.5% (6/11). Few side effects, such as dysfunction of bone marrow and kidney, were noted. Even if side effects occurred, they were mild. We concluded that excellent treatment with 5-FU modulated by CDDP has markedly improved the efficacy.

Adult↗

PubMed1998

Development of CD4+ effector T cells and susceptibility to infectious diseases.

The mechanisms by which naive helper T cells differentiate into potent cytokine-expressing effectors remain critical to understanding both successful and aberrant immune responses. Studies using Leishmania major infection of mice have revealed genetic contributions to factors that influence this differentiative process. Further, antigen recognition at the level of the T cell repertoire can also profoundly affect the outcome of disease and the appearance of discrete T cell subsets. It is likely that such mechanisms also underpin genetic susceptibility to diverse other infectious and autoimmune diseases.

Animals↗

PubMed1998

Quantitative structure-activity studies of octopaminergic agonists and antagonists against nervous system of Locusta migratoria.

The quantitative structure activity relationship (QSAR) of octopaminergic agonists and antagonists against the thoracic nerve cord of the migratory locust, Locusta migratoria L., was analyzed using physicochemical parameters and regression analysis. The hydrophobic effect, dipole moment, and shape index were important in terms of Ki: the more hydrophobic, the greater dipole moment, and the smaller shape index of the molecules, the greater the activity. A receptor surface model (RSM) was generated using some subset of the most active structures. Three-dimensional energetics descriptors were calculated from RSM/ligand interaction and these three-dimensional descriptors were used in QSAR analysis. This data set was studied further using molecular shape analysis.

Animals↗

PubMed1998

Down-regulation of focal adhesion kinase, pp125FAK, in endothelial cell retraction during tumor cell invasion.

Although endothelial cell retraction is required before tumor cell invasion, its molecular mechanism still remains obscure. We previously demonstrated that conditioned medium (CM) derived from a human pancreatic cancer cell line, PSN-1, induced endothelial cell retraction and facilitated tumor cell invasion. To investigate the molecular change of events in the transduction of extracellular signals during endothelial cell retraction, we examined the effect of the CM derived from PSN-1 cells on the tyrosine phosphorylation in endothelial cells. Immunoblot analyses revealed that the PSN-1 CM decreased tyrosine phosphorylation of a 120-130 kD protein, and induced the concomitant down-regulation of focal adhesion kinase, pp125FAK, during endothelial cell retraction in time- and dose-dependent fashions. These changes preceded endothelial cell retraction and were reversible after removal of the CM. Further quantitative densitometric analyses demonstrated that the extent of decrease in tyrosine phosphorylated 120-130 kD protein during the endothelial cell retraction was likely to be proportional to that of the down-regulation of pp125FAK. A tyrosine phosphorylated 120-130 kD protein immunoprecipitated by anti-phosphotyrosine antibody immunoreacted with anti-pp125FAK antibody. These results suggested that decreased amount of a tyrosine phosphorylated 120-130 kD protein probably due to the down-regulation of pp125FAK might be associated with the signal transduction pathway in the endothelial cells during their retraction. Furthermore, these findings were also observed in the CM from another four human cancer cell lines, suggesting the down-regulation of pp125FAK in endothelial cells during tumor cell invasion.

Animals↗

PubMed1998

Evaluation of allergenic potential of low-molecular compounds by mouse popliteal lymph node assay.

In the present study, the correlation between mouse PLNA results and those obtained from GP-PCA and from GP-ASA reactions for sodium 2,4,6-trinitrobenzenesulfonate dihydrate (TNBS), penicillin G and cephalothin was investigated. Next, various drugs were tested using the mouse PLNA to study whether PLN reactivity could be related to the potential of the compounds to induce allergic and autoimmune disorders in humans. The parameter of the PLNA was determined by the PLN cellularity index in BALB/c and A/J mice treated with a single subcutaneous injection of compounds. Hartley guinea pigs were immunized subcutaneously with the compounds without adjuvant, and then the GP-PCA and GP-ASA reactions were assessed. The examinations using mice and guinea pigs showed that mouse PLN responses to TNBS, penicillin G and cephalothin correlated with the allergenicity responses obtained in the GP-PCA reaction to three compounds. In the mouse PLNA, ten drugs considered to be well-known inducers of allergic side-effects in humans (i.e., penicillin G, cephalothin, ampicillin, carbenicillin, cefazolin, cefotaxime, streptomycin, 4-aminoantipyrine, chlorhexidine and sulfamethoxazole) caused increases in PLN cellularity indices as well. These results indicate that the PLNA may be useful as a short-term and simple test system for detecting low-molecular drugs exhibiting allergenicity potential.

Allergens↗

PubMed1998

Sex differences in immune responses to cephalothin in guinea pigs.

Guinea pigs of two strains, outbred Hartley and inbred Strain 2, were immunized subcutaneously with cephalothin (CET, 20 mg/body) alone, without adjuvant. Immune responses to the antibiotic were assessed by guinea-pig passive cutaneous anaphylaxis (GP-PCA) and active systemic anaphylaxis (GP-ASA) reactions. The immune response to CET in the female Hartley guinea pigs was higher than that in the males. In contrast, no difference in response to CET in Strain 2 guinea pigs was observed between males and females. These results suggested that female Hartley guinea pigs possessing a higher response should be employed in antigenicity studies involving the beta-lactam antibiotics.

Animals↗

PubMed1998

Disease susceptibility and development of the cytokine repertoire in the murine Leishmania major model.

The murine Leishmania major model has proven fertile ground for the elucidation of CD4+ T cell effector subset differentiation in vivo. The availability of a highly susceptible inbred strain, BALB/c, that develops progressive disease due to the aberrant differentiation of Th2, as opposed to protective Th1, responses, has allowed the identification of both T cell intrinsic as well as T cell extrinsic properties that combine to mediate disease outcome. The intrinsic T cell phenotype relates to the capacity of BALB/c-derived CD4+ T cells to acquire the potential to secrete IL-4 more readily than cells from other strains of mice. The extrinsic T cell phenotype relates to the creation of a T cell repertoire capable of recognizing the immunodominant parasite antigen. Together, the two traits confer the aberrant response seen in susceptible mice challenged with L. major.

Animals↗

PubMed1997

Increased endothelial cell retraction and tumor cell invasion by soluble factors derived from pancreatic cancer cells.

BACKGROUND: Tumor cells induce endothelial cell retraction before invasion. In pancreatic cancer cells, the factors affecting endothelial cell retraction are not well-understood. METHODS: The activities of the endothelial cell retraction in conditioned media (CM) derived from three human pancreatic cancer cell lines, PSN-1, MiaPaca-2, and Capan-1, were measured for the amount of intercellular junctional transport of FITC dextran through an endothelial cell monolayer in a transwell cell culture system. RESULTS: The CM derived from the three pancreatic cancer cells induced endothelial cell retraction. The endothelial cell retraction activity in the CM from PSN-1 cells was significantly higher than those from MiaPaca-2 and Capan-1 cells. The CM from PSN-1 cells enhanced both the adhesion and the invasion of MiaPaca-2 and Capan-1 cells. The factors with endothelial cell retraction activity in the CM from PSN-1 cells were characterized as heat-stable, trypsin-sensitive glycoproteins ranging from 10,000 to 50,000 in molecular weight, and were found both in heparin-bound and unbound fractions. CONCLUSIONS: PSN-1 cells produced and secreted at least two factors inducing the endothelial cell retraction. The factors could play an important role in the establishment of invasion and metastasis of PSN-1 cells.

Cell Adhesion↗

PubMed1997

Inhibition by ginsenoside Rg3 of bombesin-enhanced peritoneal metastasis of intestinal adenocarcinomas induced by azoxymethane in Wistar rats.

The effects of concomitant use of bombesin and ginsenoside Rg3 on the incidence of peritoneal metastasis of intestinal adenocarcinomas induced by azoxymethane were investigated in male inbred Wistar rats. From the start of the experiment, rats were given weekly s.c. injections of azoxymethane (7.4 mg/kg body weight) for 10 weeks and s.c. injection of bombesin (40 microg/kg body weight) every other day, and from week 20, s.c. injections of ginsenoside Rg3 (2.5 or 5.0 mg/kg body weight) every other day until the end of the experiment in week 45. Bombesin significantly increased the incidence of intestinal tumors and cancer metastasis to the peritoneum in week 45. It also significantly increased the labeling index of intestinal cancers. Although administration of a higher dose of ginsenoside Rg3 with bombesin had little or no effect on the enhancement of intestinal carcinogenesis by bombesin, the location, histologic type, depth of involvement, infiltrating growth pattern, labeling and apoptotic indices and tumor vascularity of intestinal cancers, it significantly decreased the incidence of cancer metastasis. These findings indicate that ginsenoside Rg3 inhibits cancer metastasis through activities that do not affect the growth or vascularity of intestinal cancers.

Adenocarcinoma↗

PubMed1997

NG-nitro-L-arginine methyl ester inhibits bone metastasis after modified intracardiac injection of human breast cancer cells in a nude mouse model.

We investigated the effects of NG-nitro-L-arginine-methyl ester (L-NAME), a nitric oxide synthase (NOS) inhibitor, on bone metastasis of human breast cancer, MDA-231 cells. Tumor cells (2 x 10(5) cells in 0.2 ml of phosphate-buffered saline; PBS) were injected through the diaphragm into the left ventricle of the heart of laparotomized nude mice (male 5-week-old ICR-nu/nu). L-NAME (2 mg/mouse/injection in 0.1 ml of PBS) was given intraperitoneally to mice 6 h and 3 h before and immediately, 3 h, 6 h, 18 h and 21 h after the intracardiac injection of tumor cells. As a control, 0.1 ml of PBS was injected instead of L-NAME. The effect of NG-nitro-D-arginine-methyl ester (D-NAME; 2 mg/mouse/injection), an inactive analogue of L-NAME, was also investigated to evaluate the specificity of L-NAME action. Radiographical examination 31 days after the tumor-cell injection showed that the incidence and number of osteolytic bone metastases and the number of bones with metastasis in L-NAME-treated mice were significantly reduced compared with those in PBS-treated mice (P < 0.05). The differences between PBS-treated and D-NAME-treated mice were not significant. Our findings suggest that specific and appropriate NOS inhibitors may represent a new pharmacological approach to therapy for cancer patients at risk of developing osteolytic bone metastases.

Animals↗

PubMed1997

Differences in immune responses to a low-molecular compound in three guinea-pig strains.

The present experiments were undertaken to clarify the differences in humoral and cellular immune responses to a low-molecular compound, sodium 2,4,6-trinitrobenznnesul fonate dihydrate (TNBS) in guinea-pig strains. Guinea pigs of three different strains, Hartley, Strain 2 and Strain 13, were immunized subcutaneously with TNBS (3 mg/body) 2 or 3 times a week, 9 times in total. Humoral immune responses to TNBS were assessed by passive cutaneous anaphylaxis (PCA) and Arthus reaction, and cellular immune response was assessed by delayed-type hypersensitivity (DTH). Hartley guinea pigs showed high humoral immune responses to TNBS, whereas Strain 2 and 13 guinea pigs showed low responses. Strain 2 guinea pigs displayed high cellular immune response to TNBS, and Strain 13 displayed low cellular immune responses. These results suggest that the pattern of humoral immune response to TNBS does not correlate with that of the cellular immune responses to TNBS for Strain 2 and Hartley guinea pigs.

Animals↗

PubMed1997

Differences in immune responses to antibiotics in three guinea-pig strains.

The present experiments were undertaken to clarify the differences in humoral immune response to two beta-lactam antibiotics, benzylpenicillin potassium (PcG) and cephalothin sodium (CET), in guinea-pig strains. Guinea pigs of three different strains, Hartley, Strain 2 and Strain 13, were immunized subcutaneously with PcG (10 mg/body) 1 or 3 times a week, 10 times in total, or with CET (20 mg/body) 3 times a week, 12 times in total. Humoral immune responses to the two antibiotics were assessed by passive cutaneous anaphylaxis (PCA) and active systemic anaphylaxis (ASA) reactions. The relative intensities of the responses to PcG and CET detected by PCA reaction were Hartley > Strain 2 > Strain 13. On the other hand, Hartley and Strain 13 guinea pigs displayed high responses to the two antibiotics by ASA reaction, and Strain 2 exhibited a relatively low response. Based on these results, it was clarified that the Hartley strain, which is the most common strain used in ordinary allergenicity tests, showed the highest response to the two antibiotics tested in PCA and ASA reactions.

Anaphylaxis↗

PubMed1997

Effect of an adhesive bonding system on wear resistance of resin composite restorations.

The effect of an adhesive bonding system on wear of posterior resin composite restorations was investigated using an in vitro three-body wear test. Resin composite restorations were placed with an adhesive system (Syntac) in Class I cavities on occlusally flattened extracted molars. Control restorations were prepared with the same resin composites but without etching or bonding. The surface of each restoration was replicated with poly(vinyl siloxane) for epoxy dies at baseline and after every 100,000 cycles until the completion of 400,000 wear cycles. The generalized wear (contact-free wear) of the composite restorations was scanned and traced at the same stage of replication with a profilometer. The use of an adhesive system significantly reduced the wear rate of the resin composites used in this study.

Composite Resins↗

PubMed1996

rho-Mediated protein tyrosine phosphorylation in lysophosphatidic-acid-induced tumor-cell invasion.

Rat ascites hepatoma cell (MM1) invade a mesothelial cell monolayer in vitro in assay medium containing serum, but not in serum-free medium. Serum could be completely replaced by 1-oleoyl lysophosphatidic acid (LPA) in inducing invasion. LPA-induced invasion was inhibited by genistein, a tyrosine-kinase inhibitor. Protein tyrosine phosphorylation in response to LPA was thus analyzed in order to determine the molecular mechanism of invasion. LPA of invasion-inducible concentrations evoked a transient increase in tyrosine phosphorylation, mainly of 110- to 130-kDa proteins in MM1 cells but not in mesothelial cells. These concentrations of LPA were over 10 times higher (10 to 25 micron) than those necessary to produce a variety of biological actions, such as tyrosine phosphorylation in fibroblasts, neurite retraction and platelet aggregation. Protein tyrosine phosphorylation and invasion by MM1 cells induced by LPA are largely regulated by rho p21, because both were inhibited by Clostridium botulinum C3 exo-enzyme, which is known to specifically inactivate rho p21. Invasion of MCL by MM1 cells induced by serum and that by B16FE7 cells induced by LPA were inhibited by genistein or C3 as well. By immunoprecipitation, we detected p 125 focal adhesion kinase (FAK) as a major protein of 110- to 130-kDa tyrosine phosphorylated in response to LPA. Tyrosine phosphorylation of paxillin by LPA was also detected.

Animals↗

PubMed1996

Inhibition of in vitro tumor cell invasion by ginsenoside Rg3.

The effect of plant glycosides on tumor cell invasion was examined. Among the glycosides tested, ginsenoside Rg3 was found to be a potent inhibitor of invasion by rat ascites hepatoma cells (MM1), B16FE7 melanoma cells, human small cell lung carcinoma (OC10), and human pancreatic adenocarcinoma (PSN-1) cells, when examined in a cell monolayer invasion model. Structurally analogous ginsenosides, Rb2, 20(R)-ginsenoside Rg2 and 20(S)-ginsenoside Rg3 (a stereoisomer of Rg3), showed little inhibitory activity. Neither Rh1, Rh2, 20(R)-ginsenosides Rh1, Rb1, Rc nor Re had any effect. The effective ginsenoside, Rg3, tended to inhibit experimental pulmonary metastasis by highly metastatic mouse melanoma B16FE7 cells as well. Taking account of our previous finding that 1-oleoyl-lysophosphatidic add (LPA) induced invasion by MM1 cells in the monolayer invasion model, the effect of Rg3 on molecular events associated with the invasion induced by LPA was analyzed in order to understand the mechanism of the inhibition. Rg3, which suppressed the invasion induced by LPA, dose-dependently inhibited the LPA-triggered rise of intracellular Ca2+. Protein tyrosine phosphorylation triggered by LPA was not inhibited by Rg3.

Adenocarcinoma↗

PubMed1995

Cell-cycle-dependent invasion in vitro by rat ascites hepatoma cells.

The relationship between cell cycle and experimental metastasis of tumor cells in vivo has been investigated, but it remains to be elucidate which step of metastasis, or whether tumor-cell invasion in particular, depends on cell cycle. We previously reported an in vitro cell-monolayer invasion (transcellular migration) assay system, in which the invasive capacity of tumor cells is measured by counting tumor cells penetrating beneath a cultured mesothelial cell monolayer after tumor-cell seeding. Using our invasion assay system, the relationship between invasive capacity and cell-cycle distribution of MMI cells, a highly invasive clone of rat ascites hepatoma AHI30, was investigated. Invasive capacity of aphidicolin- or hydroxyurea-synchronized tumor cells enriched in G1/S-early S-phase cells was about 2 to 6 times higher than that of asynchronous cells. According to time-course experiments to examine the relationship between invasive capacity and the size of fraction of cells in each phase after release from an aphidicolin or a nocodazole block, it was suggested that MMI cells are most invasive in G1/S-S phase. Phagokinetic assay using colloidal gold particles showed that one possible reason for the enhanced invasiveness might be the increased cell motility in such phases, as suggested by the in vitro invasion assay.

Animals↗

PubMed1995

Enhancement of in vitro tumor-cell transcellular migration by tumor-cell-secreted endothelial-cell-retraction factor.

To investigate the factors affecting endothelial-cell retraction, we have studied the interaction of tumor cells with endothelial cells in 2 human pancreatic cancer cell lines, PSN-1 and MiaPaca-2. The extent of endothelial-cell retraction measured by the amount of intercellular junctional transport of FITC-dextran through an endothelial monolayer was increased by the addition of a conditioned medium (CM) from both cell lines, while CM from PSN-1 cells was 2 to 3 times more potent than that from MiaPaca-2 cells. After the treatment of endothelial monolayer with CM of PSN-1 cells, the ability of both PSN-1 cells and MiaPaca cells to adhere to or invade the monolayer increased. The addition of CM from PSN-1 cells did not affect the growth rate of either the endothelial or the tumor cells. The activity in the CM was heat-stable and bound to heparin-Sepharose, but was inactivated when treated by 0.5% trypsin. Protease inhibitors did not influence the activity. Pre-treatment of PSN-1 cells by an inhibitor of protein synthesis, cycloheximide, or of protein processing, benzyl-N-acetyl-alpha-D-galactosaminide, reduced endothelial-cell-retraction activity in the CM. The active substance in the CM fractionated in the molecular-weight range of 10,000 to 50,000. These results suggest that PSN-1 cells produce and secrete (a) soluble factor(s) that can induce endothelial-cell retraction, thus facilitating tumor-cell invasion.

Animals↗

PubMed1995

Participation of rhop21 in serum-dependent invasion by rat ascites hepatoma cells.

Rat ascites hepatoma cells (MM1 cells) penetrate through a cultured mesothelial cell monolayer (MCL) in the presence of fetal calf serum (FCS), but scarcely do so in its absence. Inactivation of rhop21 of MM1 cells by ADP-ribosyltransferase C3 resulted in the suppression of this serum effect on the penetration, suggesting that the serum effect was mediated by rhop21. To ascertain this assumption MM1 cells were transfected with an activated (Val14) human rhoA cDNA (Neo/RhoA 1-7). The transfectants penetrated MCL extensively even in the absence of FCS and became largely independent of serum for the penetration. These results suggest that serum-induced invasion by MM1 cells is mainly mediated by rhop21.

ADP Ribose Transferases↗