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Biomedical subjects

N Kojima

Publications and source records attributed to N Kojima.

At least 127 records · Page 7Linked to original sources
PubMed1994

Role of cell surface O-linked oligosaccharides in adhesion of HL60 cells to fibronectin: regulation of integrin-dependent cell adhesion by O-linked oligosaccharide elongation.

The adhesion of the myelogenous leukemia cell line, HL60, to fibronectin and its fragments, heparin binding fragment (40 kDa) and cell attachment fragment (120 kDa), was enhanced by culturing with benzyl-alpha-GalNAc (BZ alpha GalNAc). Enhancement of cell adhesion to fibronectin was also observed on treatment of HL60 cells with 12-O-tetradecanoylphorbol 13-acetate (TPA). However, an additive effect of BZ alpha GalNAc and TPA treatments was not observed. The expression of VLA4 and VLA5 did not change during treatment with BZ alpha GalNAc or TPA. Cell adhesion to fibronectin before and after treatment with BZ alpha GalNAc or TPA was inhibited by anti-VLA4 and anti-VLA5 monoclonal antibodies. Staining of the cells with Helix pomatia lectin demonstrated that culturing of the cells with BZ alpha GalNAc blocked elongation of O-linked oligosaccharides on the cell surface and led to accumulation of GalNAc-O-Ser/Thr. Labeling of cell surface carbohydrates with [3H]-glucosamine followed by treatment with TPA revealed that O-glycosylated glycoproteins including CD43 were released from the cell surface during this treatment. These findings indicate that integrin-dependent cell adhesion, particularly VLA4- or VLA5-dependent cell adhesion, of HL60 cells is prevented with the extension of O-linked oligosaccharides and recovers with the disappearance of O-linked oligosaccharides from the cell surface.

Acetylgalactosamine↗
PubMed1994

Further studies on cell adhesion based on Le(x)-Le(x) interaction, with new approaches: embryoglycan aggregation of F9 teratocarcinoma cells, and adhesion of various tumour cells based on Le(x) expression.

We previously proposed specific interaction of Le(x) (Gal beta 1-->4 [Fuc alpha 1-->3]-GlcNAc beta 1-->3Gal) with Le(x) as a basis of cell adhesion in pre-implantation embryos and in aggregation of F9 teratocarcinoma cells, based on several lines of evidence (Eggens et al., J. Biol Chem (1989) 264:9476-9484). We now present additional evidence for this concept, based on autoaggregation studies of plastic beads coated with glycosphingolipids (GSLs) bearing Le(x) or other epitopes, and affinity chromatography on Le(x)-columns of multivalent lactofucopentaose III (Le(x) oligosaccharide) conjugated with lysyllysine. Comparative adhesion studies of Le(x)-expressing tumour cells vs their Le(x)-non-expressing variants showed that only Le(x)-expressing cells adhere to Le(x)-coated plates and are involved in tumour cell aggregation, in analogy to F9 cell aggregation. The major carrier of Le(x) determinant in F9 cells is not GSL but rather polylactosaminoglycan ('embryoglycan'), and we demonstrated autoaggregation of purified embryoglycan in the presence of Ca2+, and reversible dissociation in the absence of Ca2+ (addition of EDTA). Defucosylated embryoglycan did not show autoaggregation under the same conditions. Thus, Le(x)-Le(x) interaction has been demonstrated on a lactosaminoglycan basis as well as a GSL basis. A molecular model of Le(x)-Le(x) interaction based on minimum energy conformation with involvement of Ca2+ is presented.

Carbohydrate Sequence↗
PubMed1994

Expression of mouse Gal beta 1,4GlcNAc alpha 2,6-sialyltransferase in an insoluble form in Escherichia coli and partial renaturation.

Mouse Gal beta 1,4GlcNAc alpha 2,6-sialyltransferase was produced in an insoluble form in Escherichia coli cells harboring expression plasmids. The insoluble protein was solubilized with 8 M urea and diluted for renaturation of the enzyme. The substrate specificity and kinetic parameters, except for the specific activity, of the renatured enzyme were similar to those of the enzyme obtained from rat liver. These results suggest that a bacterial expression system is a potentially powerful tool for the large scale production of sialyltransferases and for elucidating the molecular mechanisms of sialyltransferases.

Animals↗
PubMed1994

Colonic submucosal tumors: comparison of endoscopic US and target air-enema CT with barium enema study and colonoscopy.

PURPOSE: To compare the imaging characteristics of colonic submucosal tumors at endoscopic ultrasound (US) and target air-enema computed tomography (TACT) with those at conventional double-contrast barium enema study and colonoscopy. MATERIALS AND METHODS: Twenty consecutive patients with suspected colonic submucosal tumors at barium enema study and colonoscopy underwent endoscopic US, TACT, or both. Morphologic features and posture-related change in shape of tumor were evaluated with barium enema study, color and consistency of tumor with colonoscopy, internal echogenicity of tumor and layer of origin in normal colonic wall with endoscopic US, and CT attenuation number with TACT. RESULTS: Eight lipomas, seven carcinoids, three leiomyomas, four lymphangiomas, and one hemangioma were found at histologic examination. Lipomas and lymphangiomas had characteristic findings at endoscopic US and TACT. The differential diagnosis of the other submucosal tumors was facilitated by using endoscopic US. CONCLUSION: Endoscopic US and TACT may play a valuable role in the evaluation of colonic submucosal tumors.

Adult↗
PubMed1994

[Effects of cyclosporin A on experimental nephritis in rats (2): Cyclosporin A suppresses the development of accelerated passive Heymann nephritis].

We investigated the effects of cyclosporin A (CyA) on accelerated passive Heymann nephritis, an experimental model of membranous nephropathy, that is characterized by immune complex deposition on the glomerular basement membrane. The nephritis was induced in rats by injection of antiserum against the antigen located in the renal tubular brush border membrane and sensitization with rabbit gamma-globulin. CyA was administered p.o. at the dose of 2.5, 10 or 20 mg/kg/day for 40 days after the injection of the antiserum. The administration of CyA resulted in marked suppression of proteinuria and hypercholesterolemia in the nephritic rats. In light microscopy, nephritic control rats showed thickening of the glomerular basement membrane and spike formation in the glomeruli. CyA significantly reduced the appearance of the glomerular alteration. The production of antibody was dramatically attenuated by CyA administration. However, CyA did not decrease the number of circulating white blood cells and platelets below the normal level. In conclusion, CyA suppressed the progress of accelerated passive Heymann nephritis in a dose-dependent manner. The effect of CyA is likely attributable to the powerful depression of antibody production.

Animals↗
PubMed1994

Isolation and characterization of two chitin synthase genes from Aspergillus nidulans.

Two chitin synthase genes, designated chsA and chsB, were isolated from Aspergillus nidulans with the Saccharomyces cerevisiae CHS2 gene as the hybridization probe. Nucleotide sequencing showed that chsA and chsB encoded polypeptides consisting of 1013 and 916 amino acid residues, respectively; the hydropathy profiles of the enzymes were similar to those of other fungal chitin synthases. Northern analysis indicated that both genes were transcribed, suggesting that cellular chitin in A. nidulans is synthesized by at least two chitin synthases. For examination of the roles of the chitin synthase genes in cell growth, gene disruption experiments were done. The chsA disruptant grew as well as the wild-type strain, but the chsB disruptant had severe growth defects that could not be overcome by the addition of 1.2M sorbitol as an osmotic stabilizer. These findings suggested that chsB but not chsA is essential for hyphal growth.

Amino Acid Sequence↗
PubMed1994

Isolation of a chitin synthase gene (chsC) of Aspergillus nidulans.

We isolated a class I chitin synthase gene (chsC) from Aspergillus nidulans. Expression of this gene was confirmed by Northern analysis and by sequencing of the PCR-amplified DNA fragments from cDNA. chsC disruptants showed no difference of morphology in the asexual cycle and no difference of growth rate compared to a wild-type strain.

Amino Acid Sequence↗
PubMed1994

[Adrenocortical function in children with near fatal asthma].

The adrenal function of children with near fatal asthma was evaluated by a modified rapid ACTH test. The rapid ACTH tests, which were performed within six months of each life-threatening asthmatic episode, showed extremely low responsiveness. The response in the subjects was significantly lower than that of patients who had received high dose of corticosteroid therapy. It was suggested that the adrenocortical function of children with near fatal asthma had been already suppressed and that adrenal suppression could easily occur in such patients. We advocate the following measures: (1) environmental control, education of patients and their families, physical training accurate medication should be supplied to reduce the use of corticosteroids, (2) sufficient doses of corticosteroids should, however be given to patients with acute exacerbation, (3) not only lung function tests or allergic examinations, but also adrenocortical function tests should be performed on severe asthmatic patients.

Adolescent↗
PubMed1993

Evaluation of thyroid function in patients with thyroid hormone autoantibodies.

Serum free thyroxine (FT4) levels were measured in patients with Hashimoto's thyroiditis and Graves' disease who were seropositive for thyroid hormone autoantibodies. The methods used were equilibrium dialysis/radioimmunoassay (FT4 by equilibrium dialysis, Nichols Institute) and FT4 analog radioimmunoassay (Amerlex MFT4) before and after treatment of sera with 12.5% polyethylene glycol (PEG). Furthermore, FT4 measurement in the PEG-treated sera was done using two other analog radioimmunoassays (DPC FT4 Kit and N-FT4 Corning). Serum thyrotropin (TSH) concentration before and after i.v. infusion of thyrotropin releasing hormone (TRH) was measured in five cases of Hashimoto's thyroiditis and four cases of Graves' disease with thyroid hormone autoantibodies. Although FT4 determination by analog tracer radioimmunoassays showed unusually high values for the hormone, results obtained by an equilibrium dialysis/radioimmunoassay method showed compatible values with basal TSH. Furthermore, FT4 concentrations measured with Amerlex MFT4 after treatment of sera with 12.5% PEG, correlated well with the values obtained by equilibrium dialysis/radioimmunoassay (r = 0.98, P < 0.001). Similar results were obtained with two other analog FT4 radioimmunoassays after treatment of sera with PEG. These results indicate that real FT4 values in patients with thyroid hormone autoantibodies are compatible with basal TSH concentrations. The presence of thyroid hormone autoantibodies per se does not affect the control mechanism of the hypothalamo-pituitary-thyroid axis. It was concluded that measurement of basal TSH as well as FT4 values by either equilibrium dialysis/radioimmunoassay or analog radioimmunoassays after PEG treatment provides clinicians with valid information for assessment of the precise status of thyroid function in patients with thyroid hormone autoantibodies.

Adolescent↗
PubMed1993

Molecular cloning of a developmentally regulated brain protein, chicken drebrin A and its expression by alternative splicing of the drebrin gene.

Drebrins are developmentally regulated proteins found in the chicken brain and are classified into three forms, E1, E2 and A. Previously we isolated two cDNAs corresponding to the embryonic drebrin mRNAs from a chick embryo cDNA library. They differed in that an internal 129-nucleotide sequence, designated ins1, was inserted in the cDNA encoding drebrin E2 and was deleted in the other cDNA encoding drebrin E1. To search for the cDNA clone encoding drebrin A, a cDNA library of 1-day-old chick brains was screened using embryonic drebrin cDNA fragments as probes. Consequently, a novel cDNA was isolated, the sequence of which was entirely identical with that of drebrin E2 except for the insertion of a 138-nucleotide sequence, designated ins2, in the 5' direction immediately upstream from ins1. Since the translation product of the entire coding region was similar to that of drebrin A, this cDNA should correspond to the mRNA for drebrin A. Sequencing analysis of three drebrin cDNAs clearly indicated that the heterogeneity of chicken drebrins was caused by the insertion or deletion of the two sequences, ins1 and ins2. The amino-terminal half region including ins2 and two short sequences in the carboxyl-terminal region of the predicted drebrin A were highly evolutionarily conserved. Cloning and sequencing of the drebrin gene revealed that ins1 and ins2 were independently encoded by separate exons and three drebrin isoforms were thought to arise by alternative splicing from a single drebrin gene. The difference in the time course of expression and tissue distribution of each drebrin suggests that the machinery of alternative splicing site selection of the drebrin gene is regulated in a developmental stage-dependent and tissue-specific manner.

Alternative Splicing↗
PubMed1993

Sensitive spectrophotometric method for the determination of ethylenediaminetetraacetic acid in foods.

A sensitive spectrophotometric method for the determination of ethylenediaminetetraacetic acid (EDTA) in foods is described. The method involves the reaction of EDTA with Fe3+ to produce the EDTA-Fe chelate, followed by the removal of excess of Fe3+ by a chelate extraction technique using chloroform and N-benzoyl-N-phenylhydroxylamine and the formation of a chromophore with 4,7-diphenyl-1,10-phenanthroline-disulfonic acid. The calibration graph was linear in the range 0.5-40.0 micrograms cm-3 of EDTA with a slope of 21.1. The relative standard deviation at 10 micrograms cm-3 of EDTA was 1.6% (n = 10). There was no interference from most of the common ingredients of commercial foods. More than 90% of EDTA added at two levels was recovered from real samples. The method was applied to the determination of EDTA in various foods, and the results obtained were compared with those given by high-performance liquid chromatography.

Edetic Acid↗
PubMed1993

Phosphatidylserine specific binding protein in rat brain: purification and characterization.

A calcium-independent phosphatidylserine specific binding protein detected on liposome blotting analysis was purified from rat brain and revealed to be identical to myristoylated, alanine-rich C kinase substrate (MARCKS). MARCKS specifically binds to phosphatidylserine but not phosphatidylcholine. The binding of MARCKS to phosphatidylserine was abolished on protein kinase C-dependent phosphorylation. Since bacterially expressed MARCKS also specifically binds to phosphatidylserine, myristoylation of the N-terminal glycine seems not to be essential for the binding of MARCKS to phosphatidylserine. These data suggest that phosphatidylserine is a membranous target molecule of MARCKS.

Amino Acid Sequence↗
PubMed1993

Yearling bulls shorten the duration of postpartum anestrus in beef cows to the same extent as do mature bulls.

The objective of this study was to determine whether yearling bulls, when pastured with cows, reduced the duration of postpartum anestrus to the same extent as did mature bulls. This experiment was conducted over a 3-yr period. Cows were stratified by parity group to achieve 37% 2-yr-old and 63% mature (> 2-yr-old) cows within each treatment group (approximately 50 cows per treatment per year). Cows were assigned in the order in which they calved to one of three treatment groups: 1) isolated from bulls (NBE; n = 158); 2) exposed to mature bulls that were > 3 yr of age (MBE; n = 154); or 3) exposed to bulls that were 1 yr of age (YBE; n = 152). Beginning the 2nd wk after calving, cows were pastured with either sterile bulls that were 1 yr (YBE) or > 3 yr of age (MBE) (three bulls per treatment group). Blood samples were collected twice weekly from late March until mid-July each year. Cows with serum concentrations of progesterone > 1 ng/mL for two consecutive sampling periods were assumed to have initiated estrous cycles after calving. Duration of postpartum anestrus in cows exposed to yearling bulls (YBE = 61.8 +/- 1.8 d) did not differ (P > .10) from duration of postpartum anestrus in cows exposed to mature bulls (MBE = 59.5 +/- 1.7 d). Duration of postpartum anestrus was shorter (P < .01) for cows exposed to bulls (MBE+YBE = 61.0 +/- 1.7 d) than for cows isolated from bulls (NBE = 72.3 +/- 1.8 d).(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗