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Biomedical subjects

M Iwamoto

Publications and source records attributed to M Iwamoto.

At least 163 records · Page 9Linked to original sources
PubMed1996

E-selectin binding promotes neutrophil activation in vivo in E-selectin transgenic mice.

E-selectin is a membrane protein expressed by endothelial cells activated by cytokines released during the inflammatory process; it plays an important role in neutrophil emigration into inflamed tissues. To further explore in vivo the function of E-selectin, we have generated transgenic mouse line expressing E-selectin under the control of a chicken beta-actin promoter. In these mice, the number of blood neutrophils was reduced, without any other obvious phenotype or tissue damage. These neutrophils, however, displayed two significant changes: first, an alteration in the levels of expression of two membrane receptors involved in neutrophil adhesion to endothelial cells, namely a marked increased in the Mac-1 antigen (CD11b/CD18) and a decrease in the Mel-14 antigen (L-selectin); second, an increased oxidative activity when compared to blood neutrophils of non-transgenic mice, as shown by their capacity to oxidize 2',7'-dichlorofluorescein (DCFH) into a fluorescent compound. These observations indicate that the binding of E-selection with neutrophils bearing its ligands promotes neutrophil activation in vivo.

Actins↗
PubMed1996

Imbalance towards Th1 predominance is associated with acceleration of lupus-like autoimmune syndrome in MRL mice.

To investigate the respective roles of Th1 and Th2 cells in the pathogenesis of lupus-like autoimmune disease, we have analyzed the spontaneous and antigen-induced productions of IgG1 vs IgG2a and IgG3 subclasses in relation to the mRNA expression of INF-gamma (Th1 cytokine promoting IgG2a and IgG3 production), IL-4 (Th2 cytokine promoting IgG1 production), and IL-10 (Th2 cytokine) in CD4+ T cells from lupus-prone MRL mice. For this purpose, two paired sets of MRL mice were chosen for the comparison of these parameters: (a) MRL-lpr/lpr (lpr for lymphoproliferation) and its recently described substrain with a prolonged survival, termed MRL-lpr/lpr.ll (ll for long lived) and (b) MRL male mice bearing the Yaa (Y-linked autoimmune acceleration) gene (MRL.Yaa) with an accelerated disease and their male counterparts lacking the Yaa gene. We demonstrate herein that the accelerated development of lupus-like autoimmune disease in MRL-lpr/lpr and MRL.Yaa mice, as compared with MRL-lpr/lpr.ll and MRL-+/+ mice, respectively, was correlated with an enhanced expression of IFN-gamma vs IL-4 and IL-10 mRNA in CD4+ T cells, which paralleled with an increase of spontaneous and foreign T cell-dependent antigen-induced productions of IgG2a and IgG3 vs IgG1 antibodies. These data suggest that an imbalance towards Th1 predominance may play a significant role in the acceleration of lupus-like autoimmune disease in MRL mice.

Animals↗
PubMed1996

Apoptosis of crypt epithelial cells in ulcerative colitis.

In the colon of ulcerative colitis (UC) patients, apoptotic bodies have been recognized in routine histopathological preparations. To investigate the extent of the apoptosis, colonic biopsies were examined from involved and uninvolved areas of untreated active UC and from normal areas in patients with colonic polyps, utilizing various markers of apoptosis. The markers included DNA breaks detected by TUNEL, Fas (CD95/APO-1) and Fas ligand (Fas-L) localized by immunohistochemistry, electron microscopic features of apoptosis, and laddering of extracted DNA. Apoptosis marker positive cells were found mainly on the luminal epithelium of the normal colon and were present in active UC in crypts of involved and uninvolved areas of the colon, in addition to the luminal epithelium. The DNA extracted from active UC colon electrophoresed as a ladder. These findings suggest that the loss of epithelial cells in active UC occurs mainly by apoptosis in crypts of involved and adjacent uninvolved areas and that the Fas/Fas-L interaction is a mediator of the apoptosis.

Apoptosis↗
PubMed1996

Prevention of murine lupus by an I-E alpha chain transgene: protective role of I-E alpha chain-derived peptides with a high affinity to I-Ab molecules.

The expression of a transgene encoding the I-E alpha chain prevents a lupus-like autoimmune syndrome in BXSB mice. However, it had not been elucidated whether the E alpha d transgene-mediated protective effect results from I-E expression or from the generation of I-E alpha chain-derived peptides (E alpha peptide) displaying high affinity for the I-Ab molecule. To address this question, two different BXSB lines expressing the transgene at low or high levels were crossed with lupus-prone MRL mice; this resulted in three types of (MRL x BXSB)F1 mice, differing in the expression levels of I-E molecules and of E alpha peptides presented by I-Ab molecules. Comparative analysis of these three (MRL x BXSB)F1 mice as well as several BXSB transgenic lines showed that the E alpha d transgene-mediated protection paralleled the expression levels of E alpha peptide presented by I-Ab molecules, but not of I-E molecules on B cells. In addition, use of transgenic and nontransgenic double bone marrow chimeras showed a selective activation of nontransgenic B cells during I-Ab-restricted T cell-dependent immune responses, while both transgenic and nontransgenic B cells were comparably activated during T cell-independent responses. These results favor a model of autoimmunity prevention based on competition for antigen presentation, in which excessive generation of E alpha peptides prevents, because of their high affinity to the I-A molecules, activation of potential autoreactive T and B cells.

Amino Acid Sequence↗
PubMed1996

Establishment of bone morphogenetic protein 2 responsive chondrogenic cell line.

A clonal cell line named RMD-1 was established from the skeletal muscle of a 20-day fetal rat. RMD-1 represents a morphologically homogeneous population of undifferentiated mesenchymal cells, expressing alpha-smooth muscle actin and type I collagen, but no cartilage-associated genes. When cultured in agarose gel containing 100 ng/ml of recombinant human bone morphogenetic protein 2 (rhBMP-2; BMP-2), RMD-1 cells formed colonies and showed chondrocyte-like features as assessed by their ultrastructure, metachromatic staining with toluidine blue, and the production of large hydrodynamic-size proteoglycans. RMD-1 cells also differentiated into chondrocytes when the cells were plated at high density (over 2.5 x 10(5) cells/cm2) on type I collagen and incubated in medium containing 0.5% fetal bovine serum and 100 ng/ml of BMP-2. This chondrogenic differentiation was evidenced by a distinct morphological change into spherical cells, an increase in the levels of sulfated glycosaminoglycans, a decrease in type I collagen mRNA and the expression of cartilage-associated genes, including type II collagen, type IX collagen, aggrecan and alkaline phosphatase. In the presence of ascorbic acid and 10% serum, RMD-1 cells increased in size and expressed type X collagen as well as high alkaline phosphatase activity, then induced matrix mineralization. Thus, RMD-1 is a unique cell line that can differentiate from undifferentiated mesenchymal cells into hypertrophic chondrocytes.

Actins↗
PubMed1996

Selective accumulation of anti-histone antibodies in glomeruli of lupus-prone lpr mice.

Immunoglobulins were eluted from glomeruli of 50 lupus-prone, lpr mice and their physicochemical properties and specificity were compared with those in sera pooled from the same mice. Although immunoglobulins in glomeruli had higher isoelectric points than those in sera, there were no appreciable differences in the relative contents of neutral and acidic immunoglobulins between them. The proportion of IgG3 subclass was slightly higher in glomerular than serum immunoglobulins. Both anti-single-stranded and anti double-stranded DNA antibodies were twofold higher in glomerular than serum immunoglobulins, while anti-Sm antibodies were not recovered in glomerular eluate despite their high activity in serum. Antibodies in glomerular eluate reacted most strongly with histones, especially with core histones, while those in sera bound preferentially with histone H1, Sm-B, -B', and -D antigens. Since histones are very basic, they would have a higher affinity for negatively charged glomerular constituents, leading to an in situ formation of immune complexes involving fixed histones and their binding with antibodies for the induction of nephritides. Otherwise, such immune complexes themselves might retain positive charges sufficient for an affinity with the glomerular basement membrane. These results indicate that histone-anti-histone antibody system may play a role in the perpetuation of murine lupus nephritis.

Animals↗
PubMed1996

Effects of X-ray irradiation on terminal differentiation and cartilage matrix calcification of rabbit growth plate chondrocytes in culture.

The retardation of long bone growth caused by irradiation is thought to be closely related to the impairment of growth plate function, but its mechanism remains unclear. In this study, we examined the effects of irradiation on the terminal differentiation of growth plate chondrocytes and on calcification. Chondrocytes were isolated from the growth plate of the ribs of four-week-old rabbits and inoculated at a high density on a type-I collagen-coated dish. Following logarithmic proliferation, they reached confluence (premature chondrocytes), then matured (mature chondrocytes), and became hypertrophied (hypertrophic chondrocytes). 10 Gy or less irradiation of the premature chondrocytes potently inhibited the terminal differentiation and matrix mineralization. Irradiation inhibited chondrocyte hypertrophy and suppressed alkaline phosphatase induction and the expression of type-X collagen without changing the protein composition profile of any other cell layer. Premature cells had the highest radiosensitivity. The sensitivity was decreased as the cells differentiated; the effects of irradiation on hypertrophic chondrocytes with terminal differentiation-related phenotypes were reduced. This study showed that 10 Gy or less irradiation of growth plate chondrocytes impaired terminal differentiation and mineralization. Since chondroclasts and bone marrow cells invade only to the mineralized cartilage, the induction of calcification in cartilage matrices is one of the most important steps in endochondral ossification. Therefore, it is conceivable that the damage in the growth plate induced by irradiation could account for the subsequent abnormal bone and skeletal growth.

Alkaline Phosphatase↗
PubMed1996

Granulocyte-colony stimulating factor concentrations in a patient with plasma cell dyscrasia and clinical features of chronic neutrophilic leukaemia.

In order to study the pathogenesis of plasma cell dyscrasias with associated clinical features of chronic neutrophilic leukaemia, the concentration of granulocyte-colony stimulating factor (G-CSF) was measured in a patient, a 73 year old man, who underwent steroid pulse therapy. High G-CSF concentrations and leucocyte counts prior to treatment declined rapidly on administration of dexamethazone, but rose subsequently. G-CSF was not detected in primary cultures of bone marrow cells, but large amounts of interleukin-6 were found in the culture supernatant. These observations suggest that the neutrophilia observed in the patient represented a reactive response to G-CSF secreted from abnormal plasma cells or stromal cells rather than the existence of a genuine myeloproliferative disorder.

Aged↗
PubMed1996

BMP signaling during bone pattern determination in the developing limb.

To examine the role of BMP signaling during limb pattern formation, we isolated chicken cDNAs encoding type I (BRK-1 and BRK-2) and type II (BRK-3) receptors for bone morphogenetic proteins. BRK-2 and BRK-3, which constitute dual-affinity signaling receptor complexes for BMPs, are co-expressed in condensing precartilaginous cells, while BRK-1 is weakly expressed in the limb mesenchyme. BRK-3 is also expressed in the apical ectodermal ridge and interdigital limb mesenchyme. BRK-2 is intensely expressed in the posterior-distal region of the limb bud. During digit duplication by implanting Sonic hedgehog-producing cells, BRK-2 expression is induced anteriorly in the new digit forming region as observed for BMP-2 and BMP-7 expression in the limb bud. Dominant-negative effects on BMP signaling were obtained by over-expressing kinase domain-deficient forms of the receptors. Chondrogenesis of limb mesenchymal cells is markedly inhibited by dominant-negative BRK-2 and BRK-3, but not by BRK-1. Although the bone pattern was not disturbed by expressing individual dominant-negative BRK independently, preferential distal and posterior limb truncations resulted from co-expressing the dominant-negative forms of BRK-2 and BRK-3 in the whole limb bud, thus providing evidence that BMPs are essential morphogenetic signals for limb bone patterning.

Amino Acid Sequence↗
PubMed1996

Hepatocyte growth factor is involved in the morphogenesis of tooth germ in murine molars.

The patterns of gene expression for hepatocyte growth factor (HGF) and its receptor, c-Met, were revealed in the tooth germ of rat mandibular molars using RT-PCR. In situ hybridization demonstrated that the HGF gene was expressed only in the cells of the dental papilla of the tooth germ in vivo. The characteristic temporospatial distribution of HGF and c-Met during germ development was revealed using immunohistochemical studies in vivo. In order to demonstrate the functional role played by HGF in tooth development, HGF translation arrest by antisense phosphorothioate oligodeoxynucleotide (ODN) was carried out in vitro. In the control experiment, explants of tooth germs from embryonic 14 day mice were cultured in a modification of Trowell's system under serum-free and chemically defined conditions for two weeks. Other explants were cultured with 15mer antisense or sense ODN targeted to the HGF mRNA. Both the control and the sense-treated explants showed normal histological structure, as observed in vivo. On the other hand, antisense-treated explants exhibited an abnormal structure in which the enamel organs were surrounded by a thin layer of dentin and dental papilla, appearing 'inside-out' compared to the control and sense-treated explants, although the cytodifferentiation of ameloblasts and odontoblasts was not inhibited. The explants treated with recombinant human HGF combined with antisense ODN showed normal development, indicating that exogenous HGF rescued the explants from the abnormal structure caused by antisense ODN. The findings of a BrdU incorporation experiment suggested that the imbalance between the proliferation activity of the inner enamel epithelium and that of the dental papilla caused by HGF translation arrest results in the abnormal structure of the tooth germ. These results indicate that HGF is involved in the morphogenesis of the murine molar.

Animals↗
PubMed1996

A pylorus-retaining pancreatic head-duodenectomy for cancers of the duodenal papilla and the lower bile duct.

With the development of diagnostic technology, the surgical methods of cancer therapy have been expanded, and operations have been performed using a procedure corresponding to the stage of cancer to improve the postoperative QOL. A 79-year-old man with cancer of the duodenal papilla and obstructive jaundice, and a 63-year-old woman with cholangiocarcinoma in the lower region complicated by cholangitis caused by Candida underwent resections of the pancreatic head and duodenum, and pancreaticogastrostomies retaining the pylorus. Satisfactory results were obtained in both cases. The merits of the procedure were that there were few complaints, sufficient food could be ingested and the QCL was maintained. The benefits of pancreaticogastrostomy are that the anastomosis procedure is simple, the gastric wall is thicker than the jejunum and blood flow is plentiful. The dorsal gastric wall is located close to the pancreatic cut-end, therefore tension is not created, and the pancreatic enzymes are not activated because the anastomosis site does not contact the intestinal fluid. These characteristics should decrease the rate of anastomosis failure which can be a fetal complication. A safer operation is desirable, particularly for elderly patients or patients who have complications.

Aged↗
PubMed1996

Effects of X irradiation on metabolism of proteoglycans.

The effects of X irradiation on matrix formation by growth-plate and articular chondrocytes, as reflected by metabolism of proteoglycans and type II collagen, were examined in a rabbit chondrocyte culture system. Irradiation with 1 to 10 Gy selectively inhibited synthesis of proteoglycans (incorporation of [35S]sulfate) depending on the stage of differentiation of the irradiated cells; however, synthesis of type II collagen was not affected. Irradiation of an immature culture, in which chondrocytes had just reached confluence, suppressed incorporation of [35S]sulfate into the glycosaminoglycan, 10 Gy inducing approximately 45-50% inhibition. In contrast, the irradiation of mature cultures, in which chondrocytes had already secreted extensive cartilage matrix, did not affect the rate of synthesis of proteoglycans (incorporation of [35S]sulfate). We also found that here irradiation stimulated the degradation of proteoglycans, but with the effect differing in growth-plate chondrocytes and articular chondrocytes. In growth-plate chondrocytes, cleavage from a site close to the G1 globular domain induced by 10 Gy enhanced the release of 35S-labeled proteoglycans into the medium, whereas in articular chondrocytes, irradiation had only marginal effects on the release of 35S-labeled proteoglycans. Our results show that irradiation with 1-10 Gy impaired proteoglycan metabolism in cartilage, with differing effects according to the stage of cell differentiation and the type of chondrocyte.

Animals↗
PubMed1996

[Development of quality of life questionnaire for patients with colorectal cancer in surgical area--a study of reliability and validity of Tokyo Yamabuki Forum Version].

We developed a new questionnaire in the surgical area based on a core quality of life (QOL) questionnaire for patients with gastrointestinal cancer. In this study, we investigated the validity and reliability of a QOL questionnaire (Tokyo Yamabuki Forum Version) for patients with colorectal cancer. The questionnaire was composed of 17 items including 5 scales (basic sensory scale, psychological scale, physiological scale, defection-related scale and active scale) and a face scale as an global scale. The time needed to answer questionnaires was expected to be around 7 minutes and the questionnaires should basically be answered by the patients themselves everyday in the hospital. The study was performed in 10 hospitals in the Tokyo area, and 394 samples collected from 21 patients with rectal and colonic cancers were analyzed. A number of respondents failed to answer the question "Do you feel your foods tasty?", so we judged this item inappropriate and deleted it from the analysis. Fifteen items, including 5 scales showed satisfactory internal consistency and construct validity in correlation and factor analyses. Performance status showed a low correlation between each item, each scale and the global scale, while SDS and STAI showed an inordinately negative correlation with the fundamental and physical scales. Especially, SDS revealed an extremely close correlation with the active scale, and STAI showed an excessive correlation with the psychological scale. In the time course of QOL under chemotherapy, reductions (aggravations) were observed in both the total score of 15 items and global scale within one week postoperatively, but after that recovered to preoperative levels at 2 weeks postoperatively. A tendency to QOL improvement was observed 2 weeks after starting chemotherapy or chemoimmunotherapy. QOL of 13 patients was measured over 3 months, and the longest term was 8 months. The results suggested that this QOL questionnaire has sufficient reliability and validity to be usable for patients with colorectal cancer in the surgical area and that this model is applicable for long-term QOL surveys and frequent measurement.

Adult↗