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Biomedical subjects

K Takayama

Publications and source records attributed to K Takayama.

At least 73 records · Page 4Linked to original sources
PubMed2000

In vivo effects of highly purified docosahexaenoic acid on rectal insulin absorption.

The purpose of this study was to evaluate the effectiveness and the toxicity of polyunsaturated fatty acid, such as oleic acid, eicosapentaenoic acid (DHA), as potential absorption enhancer for rectal delivery of insulin, using a water-in-oil-in water (W/O/W) multiple emulsion. In a single administration study, rectal insulin absorption was enhanced markedly, and marked hypoglycemia was induced by the emulsion incorporating various fatty acids in an insulin dose-related fashion. The pharmacological availability of the emulsion incorporating 2% oleic acid, EPA and DHA was approximately 7.7, 11.0 and 25.4%, respectively. The insulin absorption enhancement effect was not increased in proportion to the amount of DHA in the emulsion, the mean T(max) value of the serum glucose-time curve could be extended to twice that of the emulsion without PF 127. In a multiple administration study, the mean AUC(glucose) values of the emulsion incorporating DHA showed almost the same value on the first and the tenth day. From the morphological appearance of the mucosal surface, the emulsion incorporating DHA induced no or little mucosal damage. Our findings demonstrated that DHA has a strong insulin permeability enhancement effect and little toxicity. Thus, DHA is an attractive candidate as an absorption enhancer for intestinal delivery of insulin.

Animals↗
PubMed2000

Signal transducer and activator of transcription 6 is essential in the induction of contact hypersensitivity.

Contact hypersensitivity (CHS) is thought to be mainly associated with the activation of T helper type 1 (Th1) cells. However, there is also evidence that Th2 cells or Th2 cytokines play a role in the development of CHS. To analyze the functional contribution of Th2 cytokines interleukin (IL)-4 and IL-13, signal transducer and activator of transcription 6 (STAT6)-deficient (STAT6(-/)-) and wild-type (wt) control C57BL/6 mice were contact sensitized with 5% 2,4,6-trinitrochlorobenzene (TNCB), 0.5% 2,4-dinitrofluorobenzene, or 5% 4-ethoxyl methylene-2-phenyl-2-oxazolin-5-one, and any skin reactions were examined. Ear swelling was significantly reduced with a delayed peak response in STAT6(-/)- mice compared with wt mice.A histological analysis revealed that the infiltration of both eosinophils and neutrophils in the skin challenged after 24 h in STAT6(-/)- mice decreased substantially compared with that in wt mice. The expression of Th2 cytokines (IL-4, IL-5) in TNCB-challenged skin tissues and the supernatants from T cells stimulated by 2,4,6-trinitrobenzene sulfonate-modified spleen cells, as well as the immunoglobulin (Ig)E and IgG1 response after challenge, were also profoundly reduced in STAT6(-/)- mice, whereas the expression of interferon gamma was the same in STAT6(-/)- and wt mice after challenge. Furthermore, adoptive transfer experiments revealed that STAT6(-/)- mice induced CHS after injection of lymph node cells obtained from sensitized wt mice. Our data suggest that the STAT6 signal plays a critical role in the induction phase of CHS.

Animals↗
PubMed2000

Evaluation of skin damage caused by percutaneous absorption enhancers using fractal analysis.

Fractal analysis of the cross-sectional morphology of rat skin was conducted to evaluate pathologic changes evoked by percutaneous absorption enhancers. Male hairless rats (WBN/Ht-ILA), 8 weeks old, weighing 160 to 180 g were used. Under anesthetization, glass cells (10-mm inner diameter) were attached to the rats' abdomens, and test solutions containing various mixtures of the percutaneous absorption enhancers, sodium lauryl sulfate, isopropanol, 2-methyl-1-butanol, and sodium myristate were applied. Six hours after application, the solutions were removed and the abdominal skin was excised. Skin cross sections were analyzed with a charge-coupled device (CCD) camera. Image data taken by the CCD camera were fed into a desktop digital computer; then the fractal dimension of each skin cross section was determined on the basis of the box-counting algorithm. A pathologic study was also performed on the skin treated with the test solution. All sections of skin were examined with an optical photo microscope. Pathologic findings were classified into five levels. The total irritation score (TIS) was defined as the summation of damage levels in all regions. Only with the administration of hydrogel containing 2-methyl-1-butanol or sodium lauryl sulfate were positive values of TIS observed. However, the TIS values were independent of the concentration of these components. The most severe skin damage was evoked by application of sodium lauryl sulfate. Noticeable skin damage was also seen with 2-methyl-1-butanol. No irritation to the skin resulted from treatment with isopropanol or sodium myristate. When test solution containing sodium lauryl sulfate was applied to the skin, a remarkable increment in fractal dimensions was noted. This may suggest that the structure of the skin was greatly compromised as a result of sodium lauryl sulfate application. Although no change in fractal dimension was observed as a result of application of the test solution containing only 25% isopropanol, the fractal dimension of skin cross section gradually increased with increasing concentrations of isopropanol, 2-methyl-1-butanol or sodium myristate in the test solutions. The increment of fractal dimension was around 0.4. Thus, the skin structure was also altered by the application of high concentrations of these compounds. Although the relevance to humans is not known, fractal analysis of skin structure is thought to be useful as a novel method for detecting skin damage that is brought about by the application of percutaneous absorption enhancers.

Animals↗
PubMed2000

Enhanced enteral bioavailability of vancomycin using water-in-oil-in-water multiple emulsion incorporating highly purified unsaturated fatty acid.

The aim of this study was to evaluate the potential of an emulsion incorporating unsaturated fatty acids to improve the mucosal absorption of poorly absorbed drugs from rat intestinal loops in situ, using a water-in-oil-in-water (W/O/W) multiple emulsion. Vancomycin hydrochloride (VCM) was used as a model drug with low oral bioavailability. The entrapment efficiency of VCM in the emulsion was approximately 60% and remained constant over storage for 1 month at 4 degrees C. The emulsion incorporating C18 unsaturated fatty acids or docosahexaenoic acid (DHA) markedly enhanced VCM absorption after colonic and rectal dosing. The effectiveness of DHA on VCM colonic absorption improvement was the same as that of oleic acid, and less than that of linoleic and linolenic acids. For rectal dosing, bioavailability was similar among various emulsions, in the range 40-50%. The effect of the emulsion incorporating oleic acid or DHA on improving VCM enteral bioavailability was not increased proportional to the incorporated amount. The electrical resistance of membranes was not changed by the incorporation of various fatty acids in emulsions. Our results indicated that W/O/W emulsions incorporating C18 unsaturated fatty acid or DHA were useful carriers for improving the absorption of poorly absorbable drugs via the intestinal tract without gross changes to tight junction function.

Administration, Rectal↗
PubMed2000

Analysis of Fas and Fas ligand expression and function in lung cancer cell lines.

The aim of this study was to investigate the expression of Fas and Fas ligand (FasL) and to determine the significance of these molecules in lung cancer cell lines. Immunoblotting, RT-PCR and flow cytometric analyses were carried out to measure the expression of Fas and FasL and to examine their interactions and effects on cell growth and apoptosis. Fas and FasL were co-expressed in most of the cell lines but to varying degrees. Apoptosis induced by the agonistic anti-Fas antibody was significantly correlated with Fas expression (P=0.0075), whereas cisplatin-induced apoptosis was not. Upregulation of Fas and FasL expression by the administration of cisplatin was found in 7 of 11 (64%) and 9 of 11 (82%) cell lines, respectively. However, cisplatin-induced apoptosis was not suppressed by antagonistic anti-FasL antibody. Thus, our data indicated that Fas and FasL were co-expressed in lung cancer cell lines, and that Fas ligation induced by agonistic anti-Fas antibody is functional and induced apoptosis that was dependent on the levels of Fas expression. In contrast, Fas-FasL interactions appeared to be non-functional. Furthermore, our results suggest that cisplatin-induced apoptosis in lung cancer cells was independent of the Fas-FasL interaction.

Antineoplastic Agents↗
PubMed2000

Expression of membrane-type 1 matrix metalloproteinase in coronary vessels of allotransplanted primate hearts.

BACKGROUND: The mechanisms of intimal thickening in cardiac allograft vasculopathy (CAV) remain controversial after heart transplantation. Matrix metalloproteinase-2 (MMP-2) plays a crucial role in degrading extracellular matrix (ECM) during neointimal formation. Recently, it has been revealed that MMP-2 is activated by membrane-type 1 matrix metalloproteinase (MT1-MMP). This process involves tissue inhibitor of MMP-2 (TIMP-2), forming an MT1-MMP/TIMP-2/pro-MMP-2 complex. In this study, we hypothesize that these components contribute to the pathogenesis of CAV. METHODS: Heterotopic cardiac allografting was performed in randomly paired Japanese monkeys with an immunosuppressive regimen of intravenous administration of antihuman CD18 monoclonal antibody. The donor hearts were harvested at Days 22, 28, 40, 41, and 95 posttransplantation. We examined expression of MMP-2, MT1-MMP, and TIMP-2 of graft vessels using immunohistochemistry and protein level by western blot analysis. RESULTS: Pathologically, various degrees of neointimal formation were observed. In the allografts harvested at Days 22, 28, 40, and 41, MT1-MMP was expressed in the endothelial cells and smooth muscle cells (SMCs) in media of some arteries without histological change, accompanied by expression of MMP-2 and TIMP-2. In the severely thickened neointima of the allograft harvested at Day 95, MMP-2 and faint MT1-MMP were expressed in SMCs of severely thickened neointima and media; TIMP-2 expression was seen only in noncollagenous tissue of severely thickened neointima. MMP-2 protein was more intensely expressed in the allograft harvested at Day 95 than in the allograft harvest at Day 41, while TIMP-2 protein level was almost same in the 2 samples. CONCLUSION: We observed the simultaneous expression of MMP-2, MT1-MMP, and TIMP-2. Thus, ECM degradation triggered by MT1-MMP/TIMP-2/pro-MMP-2 complex could be a novel mechanism of CAV.

Animals↗
PubMed2000

Pharmacokinetics and antitumor effect of doxorubicin carried by stealth and remote loading proliposome.

PURPOSE: The aim of the study was to prepare stealth and remote loading proliposome (SRP-L) to carry doxorubicin (DXR) and evaluate the pharmacokinetics, acute toxicity, and anticancer effect of DXR carried with SRP-L. METHODS: SRP-L was transparent solution. When SRP-L was injected into 0.9%, NaCl aqueous solution containing DXR. liposomes formed and automatically loaded DXR (SRP-L-DXR). The long circulation of SRP-L-DXR was evaluated using the pharmacokinetics of SRP-L-DXR. cardiolipin liposomal DXR (CL-DXR) and free DXR (F-DXR). The acute toxicity and anticancer effect of SRP-L-DXR were evaluated in C57BL/6 mice and murine hystocytoma M5076 tumor model. RESULTS: The average diameter of SRP-L-DXR in pure water was 112.9 +/- 8.6 (nm) and the encapsulation efficiency of SRP-L-DXR was 96.5 +/- 0.2% in pure water, 95.5 +/- 0.1% in 5% glucose and 98.01 +/- 0.6% in 0.9% NaCl. The plasma concentration of SRP-L-DXR was much higher than those of F-DXR and CL-DXR. Compared with that of F-DXR, the SRP-L-DXR had lower acute toxicity and its anticancer effects depended upon the therapeutic treatment. CONCLUSIONS: A novel proliposome (SRP-L) was developed, which could automatically load DXR and form SRP-L-DXR with excellent characteristics. SRP-L-DXR had lower acute toxicity but was not always more effective for the treatment of the ascitic M5076 than F-DXR.

Animals↗
PubMed2000

Alteration of drug chemosensitivity caused by the adenovirus-mediated transfer of the wild-type p53 gene in human lung cancer cells.

The aim of the present study is to identify the optimal anticancer agents for use in combination with gene therapy using wild-type (wt) p53 gene transfer. We used adenoviral vectors expressing human wt p53 (AdCAp53) and investigated the effects of wt p53 gene transfer in combination with 12 anticancer agents on a human pulmonary squamous cell carcinoma cell line, NCI-H157, and a human pulmonary large cell carcinoma cell line, NCI-H1299. Solutions containing anticancer agents at various concentrations were added followed by the addition of recombinant adenovirus solutions; after a 5-day incubation period, the anticancer activity was then evaluated by a 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carbo xanilide assay. Each 50% inhibitory concentration was calculated based on the dose-response curves. The agents showing a high degree of effectiveness on NCI-H157 cells were cisplatin (CDDP), 5-fluorouracil (5-FU), bleomycin, and 7-ethyl-10-hydroxy-camptothecin (SN-38), an active metabolite of irinotecan (CPT-11); conversely, cyclophosphamide and paclitaxel showed a low degree of effectiveness. Based on these data, an isobologram was performed to investigate the interaction between AdCAp53 and some anticancer agents. A supra-additive effect was thus observed for 5-FU and SN-38 on NCI-H157 cells. An additive effect was also observed for CDDP, paclitaxel, bleomycin, and cyclophosphamide on NCI-H157 cells. CDDP, paclitaxel, 5-FU, and SN-38 had an additive effect on NCI-H1299 cells. No drug showed any subadditive or protective effects. These findings suggest that CPT-11 and 5-FU may thus be useful as possible anticancer agents for use in a combination therapy regimen using wt p53 gene transfer. CDDP and CPT-11 had a significant antitumoral effect on H157 cell xenografts of nude mice in vivo. These results indicate that CPT-11 as well as CDDP would be a candidate for the combination of chemotherapy and gene therapy for non-small cell lung cancer.

Adenoviridae↗
PubMed2000

Enhancement pattern of normal extraocular muscles in dynamic contrast-enhanced MR imaging with fat suppression.

PURPOSE: To evaluate the internal structure of normal extraocular muscles on fat-suppressed dynamic contrast-enhanced MR imaging. MATERIAL AND METHODS: Ten subjects were examined using fat-suppressed dynamic contrast-enhanced MR imaging. We evaluated the enhancement pattern (C-shaped or ring-like) of extraocular muscles and quantified the maximum ratios of enhancement (Rmax) and maximum ratios of signal increase (Vmax). We also quantified Rmax and Vmax in the central and peripheral portions of medial rectus muscles. RESULTS: In the early phase of dynamic contrast-enhanced MR imaging, a C-shaped or ring-like pattern was observed in 100% of inferior rectus, 95% of medial rectus, 55% of superior rectus, 20% of lateral rectus, and 15% of superior oblique muscles. Overall mean Rmax and Vmax values showed statistically significant differences to the temporal muscles. For the peripheral portion of medial rectus muscles, mean Rmax and Vmax values were greater than for the central portion. CONCLUSION: Using fat-suppressed dynamic contrast-enhanced MR imaging, the C-shape or ring-like internal structure of the extraocular muscles could be visualized, and were considered to reflect their structure of orbital and global layers. Potential usefulness of the fat-suppressed dynamic contrast-enhanced MR imaging for detecting pathological status is suggested.

Adipose Tissue↗
PubMed2000

Transdermal absorption of L-dopa from a new system composed of two separate layers of L-dopa and hydrogel in rats.

To maintain the stability of L-dopa in hydrogel, a new system composed of two separate layers of L-dopa and hydrogel was developed. L-Dopa sheets were made by immersing L-dopa solution into wiper sheets and by lyophilizing them. Examination for stability of L-dopa in the L-dopa sheet revealed that its stability was maintained for at least 12 weeks, providing the sheet was kept at room temperature in a dark box. In a cutaneous absorption study of L-dopa in rats, an L-dopa sheet was attached to the shaved abdominal skin. A hydrogel composed of cutaneous absorption enhancers, water and ethanol, was spread on vinyl tape (hydrogel sheet), and this sheet was placed over the L-dopa sheet. L-Dopa that was administered transdermally effectively penetrated through the skin: The plasma level of L-dopa peaked at 30 min and remained high between 60 and 180 min after the cutaneous application. Our system, composed of two separated layers of L-dopa and hydrogel, enabled the stability of L-dopa to be maintained without losing transdermal absorption of L-dopa.

Administration, Cutaneous↗
PubMed2000

Nonlinear-resonance analysis of halo formation excited by beam-core oscillation

The emittance growth and halo formation for a mismatched beam of a one-dimensional Gaussian distribution in a uniform focusing channel were examined by means of a macroparticle simulation. The results were analyzed by isolated nonlinear resonance theory. The second-harmonic resonance driven by beam-core oscillation was both numerically and analytically shown to assume a key role in forming a halo. An analytic estimation of the halo location was explored, and the halo location was proved to correspond to the outer edge of the resonance islands. Nonlinear fields in an actual particle distribution have been shown to significantly affect both the halo's location and size.

Journal Article↗
PubMed2000

Evidence for a role of rpoE in stressed and unstressed cells of marine Vibrio angustum strain S14.

We report the cloning, sequencing, and characterization of the rpoE homolog in Vibrio angustum S14. The rpoE gene encodes a protein with a predicted molecular mass of 19.4 kDa and has been demonstrated to be present as a single-copy gene by Southern blot analysis. The deduced amino acid sequence of RpoE is most similar to that of the RpoE homolog of Sphingomonas aromaticivorans, sigma(24), displaying sequence similarity and identity of 63 and 43%, respectively. Northern blot analysis demonstrated the induction of rpoE 6, 12, and 40 min after a temperature shift to 40 degrees C. An rpoE mutant was constructed by gene disruption. There was no difference in viability during logarithmic growth, stationary phase, or carbon starvation between the wild type and the rpoE mutant strain. In contrast, survival of the mutant was impaired following heat shock during exponential growth, as well as after oxidative stress at 24 h of carbon starvation. The mutant exhibited microcolony formation during optimal growth temperatures (22 to 30 degrees C), and cell area measurements revealed an increase in cell volume of the mutant during growth at 30 degrees C, compared to the wild-type strain. Moreover, outer membrane and periplasmic space protein analysis demonstrated many alterations in the protein profiles for the mutant during growth and carbon starvation, as well as following oxidative stress, in comparison with the wild-type strain. It is thereby concluded that RpoE has an extracytoplasmic function and mediates a range of specific responses in stressed as well as unstressed cells of V. angustum S14.

Amino Acid Sequence↗