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Biomedical subjects

Y Tsukamoto

Publications and source records attributed to Y Tsukamoto.

At least 109 records · Page 6Linked to original sources
PubMed1997

Gicerin, a cell adhesion molecule, participates in the histogenesis of retina.

Gicerin is a novel cell adhesion molecule that belongs to the immunoglobulin superfamily. Gicerin protein adheres to neurite outgrowth factor (NOF), an extracellular matrix protein in the laminin family, and also exhibits homophilic adhesion. Heterophilic adhesion of gicerin to NOF is thought to play an active role in neurite outgrowth of developing retinal cells in vitro. In this study, we examined the adhesion activity of gicerin during the retinal development of Japanese quail using an antibody directed against gicerin, to elucidate the biological importance of gicerin in retinal histogenesis. Immunohistochemical and Western blot analysis showed that gicerin was highly expressed in the developing retina but suppressed in the mature retina. The aggregation of neural retinal cells from 5-day embryonic quail retina was significantly inhibited when incubated with a polyclonal antibody to gicerin, suggesting that gicerin protein participates in the adhesion of neural retinal cells of the developing retina. Furthermore, histogenesis of retina both in the organ cultures and in ovo embryos was severely disrupted by incubation with a gicerin antibody. These findings provide evidence that gicerin plays an important role in retinal histogenesis.

Animals↗
PubMed1997

Silencing factors participate in DNA repair and recombination in Saccharomyces cerevisiae.

DNA double-strand breaks are repaired by homologous recombination or DNA end-joining, but the latter process often causes legitimate recombination and chromosome rearrangements. One of the factors involved in the end-joining process is Hdf1, a yeast homologue of Ku protein. We used the yeast two-hybrid assay to show that Hdf1 interacts with Sir4, which is involved in transcriptional silencing at telomeres and HM loci. Analyses of sir4 mutants showed that Sir4 is required for deletion by illegitimate recombination and DNA end-joining in the pathway involving Hdf1. Sir2 and Sir3, but not Sir1, were also found to participate in these processes. Furthermore, mutations of the SIR2, SIR3 and SIR4 genes conferred increased sensitivity to gamma-radiation in a genetic background with a mutation of the RAD52 gene, which is essential for double-strand break repair mediated by homologous recombination. These results indicate that Sir proteins are involved in double-strand break repair mediated by end-joining. We propose that Sir proteins act with Hdf1 to alter broken DNA ends to create an inactivated chromatin structure that is essential for the rejoining of DNA ends.

DNA Repair↗
PubMed1997

Differential N-glycan patterns of secreted and intracellular IgG produced in Trichoplusia ni cells.

Structures of the N-linked oligosaccharide attached to the heavy chain of a heterologous murine IgG2a produced from Trichoplusia ni (TN-5B1-4, High Five) insect cells were characterized. Coexpression of the chaperone immunoglobulin heavy chain-binding protein (BiP) in the baculovirus-infected insect cells increased the soluble intracellular and secreted IgG level. This facilitated the detailed analysis of N-glycans from both intracellular and secreted IgG. Following purification of the immunoglobulins using Protein A-Sepharose, glycopeptides, prepared by trypsin-chymotrypsin digestion, were further digested with glycoamidase from sweet almond emulsin to obtain the oligosaccharide moieties. The resulting oligosaccharides were then reductively aminated with 2-aminopyridine and the structures identified by two-dimensional high performance liquid chromatography mapping (Tomiya, N., Awaya, J., Kurono, M., Endo, S., Arata, Y., and Takahashi, N. (1988) Anal. Biochem. 171, 73-90). The N-glycans obtained from the secreted IgG contain 35% complex type, some with terminal galactose residues at either alpha1, 3-Man or alpha1,6-Man branches of the Man3GlcNAc2 core. The remaining oligosaccharides detected in the secreted IgG were principally hybrid (30%) and paucimannosidic (35%) type N-glycans. Most (84%) of these secreted glycoforms contained fucose alpha1, 6-linked to the innermost GlcNAc residue and the presence of a potentially allergenic fucose alpha1,3-linked to the innermost GlcNAc residue was also detected. In contrast, the intracellular immunoglobulins included 50% high mannose-type N-glycans with lower levels of complex, hybrid, and paucimannosidic-type structures. Reverse phase one-dimensional high performance liquid chromatography analysis of the IgG N-glycans in the absence of heterologous BiP exhibited a similar distribution of intracellular and secreted glycoforms. These studies indicate that Trichoplusia ni TN-5B1-4 cells are capable of terminal galactosylation. However, the processing pathways in these cell lines appear to diverge from mammalian cells in the formation of paucimannosidic structures, in the presence of alpha1,3-fucose linkages, and in the absence of sialylation.

Animals↗
PubMed1997

Control of the limb bud outgrowth in quail-chick chimera.

It is well known that the apical ectodermal ridge (AER) and the zone of polarizing activity (ZPA) play a major role in growth and patterning of the limb. But a mechanism underlying species-specific growth of the limb has not yet been fully elucidated. To investigate the role of AER and ZPA in limb size control, we constructed quail-chick limb chimeras. When we grafted a whole forelimb bud from one species to another, the size of the developed grafted limb was comparable to the limb of the donor species. Moreover, we demonstrated that neither the interspecific substitution of the posterior half region of the limb bud containing the ZPA nor the exchange of the ectodermal component of the limb involving the AER could alter the species-specific size of the limb. These results indicate that the factors affecting the size of the limb are already involved in the mesodermal component of the limb bud at stage 20 of chick embryo. Thus, the mesoderm dictates limb specificity including size.

Animals↗
PubMed1997

Effects of tolcapone, a catechol-O-methyltransferase inhibitor, on motor symptoms and pharmacokinetics of levodopa in patients with Parkinson's disease.

The effects of tolcapone, a catechol-O-methyltransferase inhibitor, on the bioavailability and efficacy of levodopa were evaluated in 12 patients with Parkinson's disease (PD), 8 of whom showed signs of daily motor fluctuations (wearing-off phenomenon). Motor disabilities were assessed in 12 patients at 7 time points before and after the chronic administration of tolcapone using the Unified Parkinson's Disease Rating Scale (UPDRS). The UPDRS score was improved at all points of determination. Eight patients with wearing-off phenomenon on levodopa showed symptomatic improvement on the combination. The area under the curve (AUC) for levodopa increased by 34% (p = 0.0059) after the administration of tolcapone. The elimination half-life (T1/2) of levodopa was significantly prolonged by 81% (p = 0.0001) after the treatment. The AUC of 3-O-methyldopa, a metabolite of levodopa, was decreased by 79% (p = 0.0001) and the Cmax (maximum concentration) was also decreased by 80%d after the administration (p = 0.0001) of tolcapone. The combination of tolcapone and levodopa was well tolerated. Our findings suggest that tolcapone improves the pharmacokinetics of levodopa in plasma and motor symptoms of fluctuating PD patients. It is suggested that tolcapone may be useful drug adjunct to levodopa in treating patients with PD with wearing-off phenomena.

Aged↗
PubMed1997

Establishment and characterization of cell lines derived from a transplantable rat malignant meningioma: morphological heterogeneity and production of nerve growth factor.

A cell line (KMY-J) was established from a transplantable tumor (MM-KMY) derived from a spontaneous malignant meningioma arising in an aged F344 rat, and three cloned cell lines (KMY-1, KMY-2 and KMY-3) were induced from the parent KMY-J. Morphologically, KMY-J and tumors induced in syngeneic rats by KMY-J showed cell pleomorphism. All neoplastic cells in KMY-J and its tumors were immunoreactive to vimentin; occasional cells reacted to ED1 (rat macrophage/histiocyte-specific antibody) and alpha-smooth muscle actin (alpha-SMA), indicating expression of histiocytic or myofibroblastic immunophenotypes of meningioma cells. In contrast, KMY-1, KMY-2 and KMY-3 consisted of a uniform cell population differing from each other. KMY-1-induced tumors were similar histologically to meningeal fibrosarcomas. Dendritic cells seen in KMY-2 cultures gave an appearance of arachnoid trabecular cells. In KMY-3 and its tumors, large round cells and multinucleated giant cells were predominant. Cells of these cloned cell lines also reacted to vimentin, but were negative for ED1 and alpha-SMA. By the bioassay using PC12 cells and reverse transcription-polymerase chain reaction for nerve growth factor (NGF) mRNA, production of NGF was demonstrated in the parent and cloned cell lines. The present cell lines may prove useful for studying the histological features of meningeal tumors and the bioactive factors produced by meningeal cells.

Animals↗
PubMed1997

Characteristics of a rat fibrosarcoma-derived transplantable tumour line (SS) and cultured cell lines (SS-P and SS-A3-1) showing myofibroblastic and histiocytic phenotypes.

A transplantable tumour line (SS) was established in syngeneic rats from a spontaneous fibrosarcoma that had arisen in the submandibular salivary gland of a 24-month-old male F344 rat. A cell line (SS-P) was induced from SS, and a cloned cell line (SS-A3-1) was isolated from SS-P. The primary tumour consisted of oval to spindle-shaped cells arranged in bundles with abundant collagen fibres; ultrastructurally, neoplastic cells exhibited fusiform morphology with prominent rough endoplasmic reticulum. SS tumours showed marked interlacing fascicle and herring-bone growth patterns. SS-P and SS-A3-1 were similar morphologically to each other, consisting of oval, spindle or polygonal cells and occasional multinucleated giant cells. Tumours induced by SS-P and SS-A3-1 were histologically similar to SS tumours. Immunohistochemically, all cells in the primary tumour, SS tumours and tumours induced both by SS-P and SS-A3-1 and by SS-P and SS-A3-1 cultures gave a positive reaction to vimentin. Interestingly, neoplastic cells reacting to ED1 (rat macrophage/histiocyte-specific antibody) and alpha-smooth muscle actin (alpha-SMA) appeared in SS tumours and tumours induced by SS-P and SS-A3-1 and by SS-P and SS-A3-1 cultures. Cells with histiocytic fine structures and myofibroblastic cells with cytoplasmic actin-like microfilaments were also observed by electron microscopy. The present rat fibrosarcoma-derived transplantable tumour line (SS) and cell lines (SS-P and SS-A3-1) might express myofibroblastic and histiocytic phenotypes, probably depending on the surrounding conditions. These cell lines may prove useful for studying the mechanisms of phenotypic plasticity in neoplastic fibroblasts.

Actins↗
PubMed1997

Budding yeast Rad50, Mre11, Xrs2, and Hdf1, but not Rad52, are involved in the formation of deletions on a dicentric plasmid.

We have previously shown that the RAD50, RAD52, MRE11, XRS2, and HDF1 genes of Saccharomyces cervisiae are involved in the formation of deletions by illegitimate recombination on a monocentric plasmid. In this study, we investigated the effects of mutations of these genes on formation of deletions of a dicentric plasmid, in which DNA double-strand breaks are expected to occur frequently because the two centromeres are pulled to opposite poles in mitosis. We transformed yeast cells with a dicentric plasmid, and after incubation for a few division cycles, cells carrying deleted plasmids were detected using negative selection markers. Deletions occurred at a higher frequency than on the monocentric plasmid and there were short regions of homology at the recombination junctions as observed on the monocentric plasmid. In rad50, mre11, xrs2, and hdf1 mutants, the frequency of occurrence of deletions was reduced by about 50-fold, while in the rad52 mutant, it was comparable to that in the wild-type strain. The end-joining functions of Rad50, Mre11, Xrs2, and Hdf1, suggest that these proteins play important roles in the joining of DNA ends produced on the dicentric plasmid during mitosis.

Base Sequence↗
PubMed1997

Structural changes of immunoglobulin G oligosaccharides with age in healthy human serum.

Age-related changes of IgG N-linked oligosaccharides isolated from normal human serum are reported for 403 individuals (male 227 and female 176), varying in age from 0 to 85 years. The IgG N-linked oligosaccharides were released from the protein by digestion with a glycoamidase and reductively aminated with the fluorescent reagent, 2-aminopyridine. The mixture of pyridylaminated oligosaccharides was separated at high resolution by HPLC using a reverse-phase column. From the results of neutral oligosaccharide analysis, agalactosyl glycoform and bisecting GlcNAc-containing glycoform were shown to increase with increasing age. Spearman's correlation coefficients were 0.503 and 0.473, respectively. Thus, in healthy people, an increase of both types of glycoforms correlates weakly with age. In addition, differences were demonstrated between male and female groups in their twenties. The quantity of agalactosyl glycoform was found to be lower in females than in males. No significant differences, however, were observed in the quantity of bisecting GlcNAc-containing glycoforms between males and females.

Adolescent↗
PubMed1997

Application of a deductive database system to search for topological and similar three-dimensional structures in protein.

A deductive database system PACADE (Protein Atomic Coordinate Analyzer with Deductive Engine) has been developed for protein structure analysis. With this system, super-secondary structures described in logical and declarative rules can be retrieved effectively. For protein structure analysis, comparison of local structures in different proteins is a necessary mean. A function to search for similar structures has, therefore, been added to the PACADE system. We describe herein the result of searches for the same topological structures and three-dimensionally similar ones. A user of PACADE can select these two levels of similarity by changing parameters. This function enables the inference system to retrieve similar structures, according to the restraints of variables defined by the user. Similar super-secondary structures among proteins can be searched for automatically, which is useful for protein structure analysis. The retrieved similar super-secondary structures can serve as criteria for protein spatial alignment.

Algorithms↗
PubMed1997

[Antibacterial actin of vinegar against food-borne pathogenic bacteria including Escherichia coli O157:H7 (Part 1). Examination of bacteriostatic and bactericidal activities].

Bacteriostatic and bactericidal activities of vinegar products against food-borne pathogenic bacteria including enterohemorrhagic Escherichia coli (EHEC) O157:H7, and other bacteria were examined. By the presence of spirit vinegar at 0.1% acidity, the growth of 34 strains of bacteria was completely inhibited. Grain and rice vinegars also inhibited the growth of bacteria at the same acidity. These results suggest that vinegars have strong bacteriostatic activity. Bactericidal activity of vinegar products was measured. The order of their activities against E. coli O157:H7 strains was spirit vinegar > grain vinegar > rice vinegar. Susceptibility of 7 EHEC strains (6 E. coli O157:H7 isolated from 3 outbreaks and 1 E. coli O26:H11 from a sporadic case) to spirit vinegar was similar to each other, and much lower than that of an enteropathogenic E. coli O111:K58:H- strain. It indicates that these EHEC strains are rather acid-tolerant. The bactericidal activities of vinegars were independent of bacterial inoculum sizes, but were dependent of growth phase. Bacteria of logarithmic growth phase were more sensitive than those of stationary phase. Bactericidal activity of spirit vinegar profoundly depended on the reaction temperature. At higher temperatures, spirit vinegar killed bacteria much more rapidly. In 2.5% acidity vinegar, the times for the log3 reduction of cells were 4,516 min at 10 degrees C, 739 min at 20 degrees C, 137 min at 30 degrees C, 14.4 min at 40 degrees C, and 0.84 min at 50 degrees C, respectively. These results suggest that treatment with vinegar solution at handy temperatures ranged 40-50 degrees C may be one of the useful methods to prevent bacterial food poisoning.

Acetic Acid↗
PubMed1997

[Antibacterial actin of vinegar against food-borne pathogenic bacteria including Escherichia coli O157:H7 (Part 2). Effect of sodium chloride and temperature on bactericidal activity].

Bactericidal effects of various kinds of AWASEZU (processed vinegar, 2.5% acidity) on food-borne pathogenic bacteria including Escherichia coli O157:H7 and other bacteria were examined. the order of bactericidal activities was NIHAIZU (3.5% NaCl was added) > SANBA-IZU (3.5% NaCl and 10% sucrose were added) > plain vinegar (spirit vinegar) > AMAZU (10% sucrose was added). This indicates that their activities were enhanced by the addition of sodium chloride and suppressed by the addition of sugar. On the other hand, when soy sauce was used instead of sodium chloride, the order of bactericidal activities was plain vinegar > AMAZU > NIHAIZU > SANBAIZU. This is mainly because their activities were suppressed by the increase in the pH value. The effect of sodium chloride (0.01-15%) and temperature (10-50 degrees C) on bactericidal activities against E. coli O157:H7 in spirit vinegar (0.5-2.5% acidity) was further examined. When vinegar was used in combination with sodium chloride, predominant synergism on the bactericidal activity was observed. Their activities were markedly enhanced by the addition of sodium chloride in proportion to the concentration. In addition to this, at higher temperatures spirit vinegar killed bacteria much more rapidly. It should be noted that the bactericidal activity of spirit vinegar was extremely enhanced by the combined use of the addition of sodium chloride and the rise of temperature. For example, in 2.5% acidity vinegar, the time required for 3 log decrease in viable cell numbers at 20 degrees C was shortened to 1/140-fold by the addition of 5% sodium chloride, shortened to 1/51-fold by the rise of the reaction temperature at 40 degrees C, and shortened to 1/830-fold; 0.89 minutes by both the addition of 5% sodium chloride and the rise of temperature at 40 degrees C. In order to propose the methods to prevent food poisoning by bacterial infection, bactericidal activities of vinegar solution containing sodium chloride on cooking tools and raw vegetables were examined. Vinegar solution (1-2% acidity, 3-7% NaCl) produced more than 3 log decrease in viable cell numbers of E. coli O157:H7 on the surface of cutting board, and cabbage and cucumber at 20-50 degrees C. These results suggested that the treatment with vinegar solution containing sodium chloride may be one of the useful methods to prevent food poisoning.

Acetic Acid↗
PubMed1997

Kinetics of fibroblasts in ulcer healing in rats: interference with indomethacin.

OBJECTIVE: The authors reported that the repair of submucosal tissue is important in ulcer healing. The kinetics of fibroblasts have not been well known in gastric ulcer healing. The effect of subcutaneous administration of indomethacin (1 mg/kg) to submucosal tissue was also examined. METHOD: Immunohistological staining was done using the antibodies for the proliferating cell nuclear antigen prolyl 4-hydroxylase and alpha-smooth muscle actin in acetic acid induced gastric ulcers in rats. The terminal deoxynucleotidyl transferase mediated deoxyuridine triphosphate-biotin nick end labeling method was also employed. RESULTS: The granulation tissue consisted predominantly of lymphocytes in indomethacin-treated rats. In the control group, proliferative cell nuclear antigen positive cells were at their peak 5 days after ulcer formation (day 5). Prolyl 4-hydroxylase positive fibroblasts were maximal on day 10. Alpha-smooth muscle actin positive myofibroblasts were few on day 5 and increased on day 15. In terminal deoxynucleotidyl transferase mediated deoxyuridine triphosphate-biotin nick end labeling, positive cells were sporadically seen on days 20 and 30. In indomethacin-administered rats, the fibroblasts proliferated weakly. The numbers of prolyl 4-hydroxylase and alpha-smooth muscle actin positive spindle-shaped cells were fewer and their appearance delayed. Nick end labeling positive cells were few before day 30 and sporadically observed on days 50 and 80. CONCLUSION: The results indicate that fibroblasts differentiated into several phenotypes and finally underwent apoptosis.

Acetic Acid↗
PubMed1997

[Adynamic bone disease].

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Chronic Kidney Disease-Mineral and Bone Disorder↗
PubMed1997

Incidence and clinical characteristics of hypoparathyroidism in dialysis patients.

The incidence and clinical characteristics of hypoparathyroidism (Hypo) were evaluated in 8188 hemodialysis (HD) and 1207 CAPD patients treated in 65 hospitals or clinics in Japan. Hypo was defined by an intact parathyroid hormone (PTH) level below 160 pg/ml, which corresponded to the low normal limit of intact PTH to maintain a normal osteoblastic surface in 40 bone biopsy specimens of Japanese dialysis patients, and patients were classified into two groups: absolute Hypo (A-Hypo), intact PTH < 60 pg/ml, and relative Hypo (R-Hypo), 60 pg/ml < or = intact PTH < 160 pg/ml. A total of 2537 (31.0%) and 2736 (33.4%) HD patients were classified into A- and R- Hypo, and 401 (31.3%) and 379 (31.4%) CAPD patients occupied A- and R-Hypo, respectively. A high incidence of Hypo was observed in the HD patients with diabetes mellitus (DM) and old age (> or = 70 years old) compared with that of a nationwide epidemiological report for dialysis patients by Japanese Society for Dialysis Therapy. Hypo patients who were treated by CAPD had a background of being younger, having a shorter duration on dialysis, and were less frequently diagnosed with DM than in those Hypo patients on HD. Bone pain and metastatic calcification were observed in approximately 20% and 25% of Hypo patients, respectively. No difference was observed in the background factors and the prevalence of signs and symptoms between the A- and R-Hypo groups, regardless of the mode of treatment (HD or CAPD). These results suggest that a very high incidence and specific backgrounds (DM and aging) of Hypo exist in Japanese dialysis patients.

Adult↗
PubMed1996

150-kD oxygen-regulated protein is expressed in human atherosclerotic plaques and allows mononuclear phagocytes to withstand cellular stress on exposure to hypoxia and modified low density lipoprotein.

The 150-kD oxygen-regulated protein (ORP150) was initially characterized based on its selective expression in astrocytes subjected to oxygen deprivation (Kuwabara, K., M. Matsumoto, J. Ikeda, O. Hori, S. Ogawa, Y. Maeda, K. Kitagawa, N. Imuta, K. Kinoshita, D.M. Stern, et al. 1996. J. Biol. Chem. 279:5025-5032). We have found that exposure of cultured human aortic smooth muscle cells and mononuclear phagocytes (MPs) to hypoxia (pO2 approximately 12-14 torr) induces ORP150 transcripts and production of the antigen, whereas incubation with either hydrogen peroxide, sodium arsenite, heat shock, or 2-deoxyglucose was without effect. Tissue extracts prepared from human atherosclerotic lesions demonstrated expression of ORP150 mRNA and antigen, vs lack of ORP150 in samples from nonatherosclerotic areas. In situ hybridization using ORP150 riboprobes showed the mRNA to be predominantly [correction of predominately] present in macrophages in in atherosclerotic plaques. Furthermore, autoantibody to ORP150 was demonstrated in the serum of patients with severe atherosclerosis, consistent with inducible in vivo expression of ORP150. Introduction of antisense oligonucleotide for ORP150 selectively diminished hypoxia-mediated induction of ORP150 antigen and reduced the viability of hypoxic MPs, especially in the presence of modified (oxidized/acetylated) LDL. In support of a role for ORP150 in the MPs' response to the microenvironment of an atheroma, the presence of oxidized LDL enhanced by approximately 10-fold ORP150 expression in hypoxic cultures. These data indicate that cells of the atherosclerotic vessel wall express ORP150 as part of a protective mechanism, potentially triggered by local hypoxia/hypoxemia and augmented by modified lipoproteins. The presence of antibody to ORP150 in sera of patients with severe atherosclerosis emphasizes the possibility that ORP150 may be a marker of vascular pathology.

Adolescent↗