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Biomedical subjects

K Ishihara

Publications and source records attributed to K Ishihara.

At least 127 records · Page 7Linked to original sources
PubMed2000

Chemical modification of silk fibroin with 2-methacryloyloxyethyl phosphorylcholine. II. Graft-polymerization onto fabric through 2-methacryloyloxyethyl isocyanate and interaction between fabric and platelets.

2-Methacryloyloxyethyl phosphorylcholine (MPC) was grafted onto silk fabric in a two-step heterogeneous system through the vinyl bonds of 2-methacryloyloxyethyl isocyanate (MOI) modified on the fabric. First, habutae silk fabric was modified with the MOI monomer in anhydrous dimethyl sulfoxide using di-n-butyltin (IV) dilaurate and hydroquinone at 35 degrees C. The saturated weight gain of modified MOI monomer on the fabric was 7.3 wt% versus the original silk. Second, graft polymerization with MPC onto the MOI modified silk was conducted using 2,2'-azo bis[2-(2-imidazolin-2-yl)propane dihydrochloride] (VA-044) as an azo polymerization initiator. The weight of the grafted MPC eventually gained was about 26.0 wt%. The MOI-modified and MPC-grafted silk fabrics were analyzed by Fourier transform infrared (FT-IR) spectroscopy. To confirm the improved biocompatibility of the silk fabric, platelet adhesion was preliminarily tested measuring lactate dehydrogenase. The number of platelets adhering to polyMPC-grafted silk fabric decreased by about one tenth compared to original and MOI-modified silk after 60 min of contact with human platelet-rich plasma (1.0 x 10(6) platelets cm(-2)).

Animals↗
PubMed2000

Colonic mucin-carbohydrate components in colorectal tumors and their possible relationship to MUC2, p53 and DCC immunoreactivities.

To clarify changes in mucus components during colorectal tumorigenesis, we developed novel monoclonal antibodies (Abs) against carbohydrate chains of human colorectal mucin (HCM) obtained from normal sigmoid and rectal mucosae. A hundred and ninety-nine cases of colorectal carcinoma and 67 cases of tubular adenoma, along with 250 normal colonic tissue samples, were investigated immunohistochemically. The results were compared with clinical stage, survival and MUC2 (core protein of the intestinal type mucin) expression, as well as with the status of the p53 and DCC (deleted in colorectal carcinomas) genes. In the normal colonic epithelium, HCM14 Ab reacted with the cytoplasmic regions of the goblet cells and enterocytes, while HCM21 Ab bound to mucous droplets in the former, suggesting a more mature carbohydrate structure. Both HCM14 and 21 scores were significantly decreased in adenomas and carcinomas. This is in line with an altered PAS-Alcian blue staining, indicating accumulation of mucins with incomplete or abnormal glycosylation in tumors. Levels of HCM14 and 21 binding tended to show a positive correlation with expression of MUC2 and DCC, and a negative association with p53 protein accumulation in carcinomas, although there was no apparent link to Duke's stage or the prognostic outcome. These findings suggest a possible involvement of alterations in mucin carbohydrate in colorectal tumor development. The observed changes may be associated with loss of MUC2 and DCC expression, as well as with p53 protein accumulation.

Adenocarcinoma↗
PubMed2000

Dissection of signaling cascades through gp130 in vivo: reciprocal roles for STAT3- and SHP2-mediated signals in immune responses.

We generated a series of knockin mouse lines, in which the cytokine receptor gp130-dependent STAT3 and/or SHP2 signals were disrupted, by replacing the mouse gp130 gene with human gp130 mutant cDNAs. The SHP2 signal-deficient mice (gp130F759/F759 were born normal but displayed splenomegaly and lymphadenopathy and an enhanced acute phase reaction. In contrast, the STAT3 signal-deficient mice (gp130FXQ/FXXQ) died perinatally, like the gp130-deficient mice (gp130D/D). The gp130F759/F759 mice showed prolonged gp130-induced STAT3 activation, indicating a negative regulatory role for SHP2. Th1-type cytokine production and IgG2a and IgG2b production were increased in the gp130F759/F759 mice, while they were decreased in the gp130FXXQ/FXXQ immune system. These results indicate that the balance of positive and negative signals generated through gp130 regulates the immune responses.

Acute-Phase Reaction↗
PubMed2000

Regioselective acylation of flavonoid glucoside with aromatic acid by an enzymatic reaction system from cultured cells of Ipomoea batatas.

The regioselective acylation of naturally occurring plant pigments with aromatic acids such as caffeic acid and p-coumaric acid was examined by an enzymatic reaction system from cultured cells of Ipomoea batatas. Isoquercitrin, a flavonoid glucoside, was converted to isoquercitrin 6''-O-caffeate by the enzymatic system. Chrysanthemin, an anthocyanin, was also acylated to the corresponding caffeate ester. This enzymatic method should prove useful for the synthesis of acylated flavonoid glucosides such as isoquercitrin caffeate, whose productivity is low using lipase-catalyzed transesterification.

Journal Article↗
PubMed2000

Effects of ecabet sodium, a novel gastroprotective agent, on mucin metabolism in rat gastric mucosa.

The effects of ecabet sodium (ecabet), 12-sulfodehydroabietic acid monosodium salt, on gastric mucin biosynthesis in rat antrum were compared with those in the corpus. Intragastric administration of ecabet significantly increased [3H]glucosamine incorporation into antral mucin as well as into corpus mucin during five successive hours of organ culture. In contrast, mucin biosynthesis in either antrum or corpus was not susceptible to the addition of ecabet to the culture medium. Ecabet-induced stimulation of prostaglandin E2 production in the antrum was essentially the same as that seen in the corpus. In antrum treated with 100 mg/kg ecabet, immunoreactivity with three distinct anti-mucin monoclonal antibodies was found not only in the specific mucus-producing cells, but also in the secreted mucus present at the surface gel layer. These results suggest that ecabet enhances the mucin metabolism, and this stimulation occurs in both the corpus and antrum, suggesting that ecabet might be a useful tool for the further clarification of the regulatory mechanism of antral mucin synthesis.

Abietanes↗
PubMed2000

Calcium-channel blocker attenuates Kupffer cell production of cytokine-induced neutrophil chemoattractant following ischemia-reperfusion in rat liver.

We investigated the effects of the calcium-channel blocker verapamil hydrochloride on the production of cytokine-induced neutrophil chemoattractant (CINC) following reperfusion injury in rat liver. Ischemia was induced for 30 min by portal vein occlusion. Animals were pretreated with intravenous injection of verapamil hydrochloride (2.5 mg/kg) 5 min before vascular clamp. Verapamil hydrochloride limited increases in the chemoattractant compared with nonpretreated rats. Most cells immunostained for chemoattractant were ED2-positive macrophages in sinusoids. In vitro chemoattractant production by Kupffer cells isolated from animals pretreated with verapamil hydrochloride was significantly lower than by Kupffer cells from nonpretreated animals. Expression of transcripts in liver for chemoattractant peaked 3 hr after reperfusion in nonpretreated animals, while pretreatment with verapamil hydrochloride significantly decreased chemoattractant mRNA levels. In vitro chemoattractant production could be induced in naive Kupffer cells after stimulation with oxygen radicals generated by hypoxanthine and xanthine oxidase, but verapamil hydrochloride prevented these increases. We concluded that the calcium-channel blocker verapamil hydrochloride significantly attenuates chemoattractant release by Kupffer cells after ischemia-reperfusion in the rat liver.

Animals↗
PubMed2000

Reduced interleukin-12, interleukin-18, and interferon-gamma production with prolonged rat hepatic allograft survival after donor-specific blood transfusion.

Interferon-gamma is a key immunoregulatory cytokine involved in acute graft rejection. Immunologic unresponsiveness to organ allografts has been induced by pretransplantation donor-specific blood transfusion, both experimentally and clinically. We investigated interferon-gamma production and intragraft gene expression of type-1 T-helper cytokines such as interleukin-12 and -18 and type-2 T-helper cytokines such as interleukin-10 and transforming growth factor-beta in rats receiving hepatic allografts after such transfusions. The animals were divided into four groups: group I received isografts; group II received allografts; group III received allografts after donor-specific transfusion; and group IV received allografts and was treated with FK 506. Donor blood given seven days prior to transplantation significantly prolonged allograft survival. The serum interferon-gamma concentrations in group II increased, peaking on day 5 and then decreasing. Serum interferon-gamma concentrations in groups I, III, and IV were significantly lower than those observed in group II, as were levels of interleukin-12 and interleukin-18 mRNA in the graft. Transforming growth factor-beta and interleukin-10 mRNA levels in grafts in transfused animals were significantly greater than those in the untreated allograft group. Interleukin-12 and -18 mRNA transcripts in an allogeneic mixed lymphocyte reaction were inhibited by interleukin-10 and transforming growth factor-beta. These results suggest that interleukin-12 and -18 expression in hepatic allografts is inhibited in the immunologically unresponsive state induced by donor-specific transfusion.

Animals↗
PubMed2000

Relationships between the onset of pustulosis palmaris et plantaris, periodontitis and bacterial heat shock proteins.

Relationships between the onset of pustulosis palmaris et plantaris, periodontitis and heat shock proteins were studied by using enzyme-linked immunosorbent assay to examine levels of immunoglobulin G (IgG) against Escherichia coli GroEL, a recombinant DnaJ of Actinobacillus actinomycetemcomitans heat shock protein, a synthetic peptide made from the 180th to the 188th amino acids of Mycobacterium bovis BCG Hsp65, and a recombinant human Hsp60, in sera obtained from 43 pustulosis palmaris et plantaris patients judged to have chronic infectious diseases of the oral cavity. We found that the titers of IgG against E. coli GroEL and A. actinomycetemcomitans DnaJ in the sera from pustulosis palmaris et plantaris patients were significantly higher than those in the control group, whereas the titers of IgG against the synthetic M. bovis Hsp65 and the recombinant Hsp60 did not differ significantly. Periodontal therapy and extraction of teeth with periapical infectious resulted in remission of pustulosis palmaris et plantaris and a statistically significant reduction in the levels of IgG against E. coli GroEL in 9 of the 22 patients (41%) examined. We also found that the IgG levels against A. actinomycetemcomitans DnaJ in 6 serum samples of 16 (37%) were reduced, but not significantly, after the treatment. These results suggest that the IgG responses to heat shock proteins partially induced by oral bacteria may be related to the onset of pustulosis palmaris et plantaris in some patients.

Adult↗
PubMed2000

Gastric adenomas and superficial adenocarcinomas display distinct patterns of mucin carbohydrate and core protein expression.

AIMS: To investigate the histogenetic relationship between gastric epithelial neoplasms we studied differences in expression of mucin carbohydrate antigens and mucin core protein, in normal and metaplastic gastric mucosa, and in gastric adenomas and superficial adenocarcinomas. METHODS AND RESULTS: We generated four monoclonal antibodies, including HGM72/75 against human gastric mucin and HCM14/21 against human colonic mucin, and investigated immunoreactivities of these antibodies and MUC2 protein expression in normal and metaplastic gastric mucosa, adenomas (15 samples) and superficial adenocarcinomas (intestinal-type, 77; diffuse-type, 59 samples). HGM72 reacted with mucous neck cells of the fundic glands and with pyloric glandular cells whereas HGM75 stained foveolar cells and metaplastic goblet cells. Weak binding of HCM14/21 and strong staining with MUC2 were found in metaplastic goblet cells. Binding of HGM75, HCM14, MUC2, but not HGM72 was high in adenomas. An equivalent staining with HGM72 and HGM75 with low expression of MUC2 and HCM14 was shown in intestinal-type carcinomas while the diffuse-type demonstrated more strong reactivity with HGM75 than with HGM72, MUC2 and HCM14. Little binding of HCM21 was observed in any specimens. CONCLUSIONS: This study demonstrates that adenomas predominantly have a intestinal phenotype, but both types of adenocarcinomas retain some cells with a gastric phenotype during the early steps of neoplastic development.

Adenocarcinoma↗
PubMed2000

Small diameter vascular prosthesis with a nonthrombogenic phospholipid polymer surface: preliminary study of a new concept for functioning in the absence of pseudo- or neointima formation.

The purpose of this study was to prepare a small diameter vascular prosthesis functioning without pseudointima formation. A nonthrombogenic phospholipid polymer, the 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer, has a cell membrane-like structure and has demonstrated strong nonthrombogenicity. We have recently prepared 2 kinds of vascular prostheses, 2 mm in diameter, composed of the MPC polymer and segmented polyurethane (SPU). One includes 7.5 wt% MPC polymer (SPU/MPC[7.5] prosthesis), and the other includes 10.0 wt% (SPU/MPC[10] prosthesis). These prostheses were placed in rabbit carotid arteries and were retrieved at 1 and 4 weeks after implantation. A pseudointima was observed at 4 weeks on the SPU/MPC(7.5). For the SPU/MPC(10), the surface was macroscopically clear without a pseudointima even after a 4 week implantation. It appears that the SPU/MPC(10) prosthesis, functioning without a pseudointima, possesses a stronger nonthrombogenicity and would be more applicable for clinical use.

Anastomosis, Surgical↗
PubMed2000

Chronic (-)-hydroxycitrate administration spares carbohydrate utilization and promotes lipid oxidation during exercise in mice.

(-)-Hydroxycitrate (HCA) is an active ingredient that is extracted from the rind of the Indian fruit, Garcinia cambogia, which is available as an herbal supplement and is used to lose weight. In this study, the acute and chronic effects of HCA on energy metabolism were examined in male Std ddY mice. Mice were placed into metabolic chambers and administered 10 mg HCA or water (control) orally. Serum free fatty acid levels were significantly higher 100 min after administration in the HCA group, but the respiratory exchange ratio was not different from that in the control group. The concentration of glycogen in the gastrocnemius muscle was higher in the HCA group 16 h after administration, and in a separate study, the maximum swimming time until fatigue was slightly longer (P: = 0. 21) than that in the control group on d 1. The difference was significant on d 3 after 3 d of HCA or water administration. Other mice were administered 10 mg HCA or water orally twice a day for 25 d. On d 26, they were placed into metabolic chambers after administration and allowed to rest for 1 h, followed by 1 h of running at 15 m/min. Respiratory gas was monitored. The respiratory exchange ratio was significantly lower in the HCA group during both resting and exercising conditions. These results suggest that chronic administration of HCA promotes lipid oxidation and spares carbohydrate utilization in mice at rest and during running.

Administration, Oral↗
PubMed2000

Mechanisms of Igf2/H19 imprinting: DNA methylation, chromatin and long-distance gene regulation.

The mouse Igf2 and H19 genes lie 70-kb apart on chromosome 7 and are reciprocally imprinted. Two regulatory regions are important for their parental allele-specific expression: a differentially methylated region (DMR) upstream of H19 and a set of tissue-specific enhancers downstream of H19. The enhancers specifically activate Igf2 on the paternal chromosome and H19 on the maternal chromosome. The interactions between the enhancers and the genes are regulated by the DMR, which works as a selector by exerting dual functions: a methylated DMR on the paternal chromosome inactivates adjacent H19 and an unmethylated DMR on the maternal chromosome insulates Igf2 from the enhancers. These processes appear to involve methyl-CpG-binding proteins, histone deacetylases and the formation of chromatin insulator complexes. The Igf2/H19 region provides a unique model in which to study the roles of DNA methylation and chromatin structure in the regulation of chromosome domains.

Animals↗
PubMed2000

Comparative genomic sequencing identifies novel tissue-specific enhancers and sequence elements for methylation-sensitive factors implicated in Igf2/H19 imprinting.

A differentially methylated region (DMR) and endoderm-specific enhancers, located upstream and downstream of the mouse H19 gene, respectively, are known to be essential for the reciprocal imprinting of Igf2 and H19. To explain the same imprinting patterns in non-endodermal tissues, additional enhancers have been hypothesized. We determined and compared the sequences of human and mouse H19 over 40 kb and identified 10 evolutionarily conserved downstream segments, 2 of which were coincident with the known enhancers. Reporter assays in transgenic mice showed that 5 of the other 8 segments functioned as enhancers in specific mesodermal and/or ectodermal tissues. We also identified a conserved 39-bp element that appeared repeatedly within the DMR and formed complexes with specific nuclear factors. Binding of one of the factors was inhibited when the target sequence contained methylated CpGs. These complexes may contribute to the presumed boundary function of the unmethylated DMR, which is proposed to insulate maternal Igf2 from the enhancers. Our results demonstrate that comparative genomic sequencing is highly efficient in identifying regulatory elements.

5' Untranslated Regions↗
PubMed2000

Seroepidemiological investigation of feline chlamydiosis in cats and humans in Japan.

The prevalence of chlamydia antibodies in Japan was investigated in 215 cat sera, consisting of 88 sera of stray cats and 127 sera of pet cats, and 2,184 human sera, taken from 2,003 general persons and 181 small animal clinic veterinarians, by microimmunofluorescence (MIF) testing with Chlamydia psittaci Fe/Pn1 of feline origin and Prk/6BC of avian origin as antigens. The prevalence rates of anti-Fe/Pn1 antibodies were 45.5% in stray cats, 17.3% in pet cats, 1.7% in general persons and 8.8% in small animal clinic veterinarians. The prevalence rates of anti-Prk/6BC antibodies were 51.1% in stray cats, 15.0% in pet cats, 3.1% in general persons and 5.0% in small animal clinic veterinarians. These results suggested that feline chlamydia infection is widely spread in cats especially in stray cats in Japan, and suggested that feline chlamydiosis could be transmitted to people who are in close contact with infected cats.

Animals↗
PubMed2000

Helicobacter pylori may have only a transient presence in the oral cavity and on the surface of oral cancer.

We used the reverse transcription polymerase chain reaction (RT-PCR) and culture methods to study the presence of Helicobacter pylori in the gastric and oral samples from a total of 116 gastritis and peptic ulcer patients, including 58 with oral cancer. Detection rates of H. pylori were 46.6% in stomach samples and 12.1% in oral swab samples. All of the oral cancer surface swab samples were positive for H. pylori, as were their gastric samples suggesting that oral H. pylori derived from the stomach. The culture supernatants of Streptococcus mutans and Prevotella intermedia inhibited the growth of the H. pylori strain and caused the formation of the coccal form. In cases where H. pylori was detected in the oral cavity samples, including the oral cancer surface samples, it was believed that this species had colonized the stomach and were present in the oral cavity only as a transient organism.

Bacterial Proteins↗
PubMed2000

CGRP modulates mucin synthesis in surface mucus cells of rat gastric oxyntic mucosa.

We examined the effects of the calcitonin gene-related peptide (CGRP), including the possible participation of nitric oxide (NO), on mucin biosynthesis in the surface epithelium and remaining deep mucosa as well as the entire mucosa and compared the distribution of CGRP and NO synthase (NOS) using a combination of double immunofluorescence labeling and multiple dye filter. Pieces of tissue obtained from the corpus and antrum were incubated in a medium containing [(3)H]glucosamine and CGRP, with or without the NOS inhibitor. CGRP dose-dependently enhanced [(3)H]glucosamine incorporation into the corpus mucin but had no effect on antral mucin biosynthesis. The CGRP receptor antagonist, CGRP-(8-37), prevented the increase in (3)H-labeled corpus mucin. This stimulation of corpus mucin synthesis disappeared after removal of the surface mucus cell layer. CGRP activated the mucin biosynthesis in the surface mucus cells. In the full-thickness corpus mucosa, CGRP-induced activation was completely blocked by the NOS inhibitor. CGRP-immunoreactive fibers were intertwined within the surface mucus cell layer with type I NOS immunoreactivity. These results show that CGRP-stimulated mucin biosynthesis mediated by NO is limited to surface mucus cells of the rat gastric oxyntic mucosa.

Animals↗
PubMed2000

Analysis of the prolongation of rat eosinophil survival induced by recombinant rat interleukin-5.

Rat eosinophil survival was prolonged by recombinant rat IL-5 prepared by the baculovirus expression system. The IL-5-induced prolongation of eosinophil survival was dose-dependently inhibited by the protein synthesis inhibitor cycloheximide, the DNA-dependent RNA synthesis inhibitor actinomycin D, and the tyrosine kinase inhibitor herbimycin A. The MEK-1 inhibitor PD98059 inhibited IL-5-induced phosphorylation of both p44 and p42 MAP kinases, but the IL-5-induced prolongation of eosinophil survival was not inhibited. In contrast, the JAK2 inhibitor AG490 inhibited the IL-5-induced prolongation of eosinophil survival. Treatment of eosinophils with IL-5 resulted in phosphorylation of STAT5 but not STAT1, and the IL-5-induced phosphorylation of STAT5 was inhibited by AG490. These findings suggest that recombinant rat IL-5 activates JAK2 tyrosine kinase, which phosphorylates STAT5, and induces protein synthesis required for the prolongation of rat eosinophil survival.

Animals↗