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Biomedical subjects

Y Fujimura

Publications and source records attributed to Y Fujimura.

At least 307 records · Page 17Linked to original sources
PubMed1986

Isolation and characterization of a collagen binding domain in human von Willebrand factor.

von Willebrand factor binds to fibrillar type I collagen in a rapid, temperature-independent, reversible, specific, and saturable manner. Evaluation of binding isotherms by Scatchard-type analysis demonstrated that 6-18 micrograms of von Willebrand factor bind per mg of collagen, with Ka between 2 and 8 X 10(8) M-1. Five distinct tryptic fragments, purified under denaturing and reducing conditions and representing over 75% of the molecular mass of the von Willebrand factor subunit, were tested for their capacity to inhibit the von Willebrand factor-collagen interaction. Complete inhibition was obtained with a 52/48-kDa fragment at a concentration of approximately 1 microM. The location of this fragment in the subunit was established to be between Val-449 and Lys-728. Fifteen monoclonal antibodies against the 52/48-kDa fragment inhibited von Willebrand factor binding to collagen. Six antibodies against other portions of the von Willebrand factor subunit had no inhibitory effect. The tryptic fragment was a competitive inhibitor of von Willebrand factor binding to collagen and, therefore, recognizes the same interaction site as the intact molecule. These studies precisely define a domain in the von Willebrand factor subunit that interacts with type I collagen.

Antibodies, Monoclonal↗
PubMed1986

von Willebrand factor. A reduced and alkylated 52/48-kDa fragment beginning at amino acid residue 449 contains the domain interacting with platelet glycoprotein Ib.

We have purified a reduced and alkylated tryptic fragment of von Willebrand factor (vWF) which migrated in sodium dodecyl sulfate-polyacrylamide gel electrophoresis as a 52/48-kDa doublet, but behaved as a single 46-kDa species after partial deglycosylation. After extensive treatment with denaturants, the 52/48-kDa polypeptide retained its ability to inhibit ristocetin-induced platelet aggregation in the presence of native vWF, as well as aggregation induced by desialylated vWF alone. Therefore, the 52/48-kDa polypeptide interacts with the platelet glycoprotein Ib receptor even in the absence of ristocetin. Both the 52/48- and the 46-kDa species inhibited ristocetin-induced binding of the intact molecule to platelets, but did not affect thrombin-induced binding. Determination of the NH2-terminal sequence of both members of the doublet gave identical results: VTLNPSDPEHCQ. This provided additional evidence that differences between the doublet constituents were only of carbohydrate composition and established the position of this peptide within the vWF polypeptide chain of approximately 2050 amino acid residues as beginning with the residue tentatively designated 449. These studies suggest that native conformation is not necessary for binding of vWF to platelets at the glycoprotein Ib receptor and that a linear amino acid sequence following residue 449 defines a domain responsible for this interaction.

Amino Acid Sequence↗
PubMed1986

Functional morphology of microfold cells (M cells) in Peyer's patches--phagocytosis and transport of BCG by M cells into rabbit Peyer's patches.

Suspensions of BCG (32-80 X 10(7) viable bacilli/ml) were injected into constricted loops of ileum containing a Peyer's patch from non-immunized young adult rabbits after laparotomy under anesthesia. Light microscopically (rhodamine B-auramine double staining, Ziehl-Neelsen staining), many mycobacteria were observed adhering to the surface of follicle-associated epithelium (FAE) and in phagocytes that had migrated within FAE and to deep lymphoid follicles. Electron microscopically in 1-hour post inoculated specimens, the bacteria were found adhering specifically to M cells, and the microfolds of the M cells were seen to stretch like tentacles toward the bacteria to catch them. The bacteria were recognized in the large vesicle of the cytoplasm of the M cells. The bacteria phagocytized by the M cells were found in the intercellular space between M cells and columnar cells. The bacteria were also seen in macrophages enfolded by the M cells as well as in macrophages below the FAE. In this experiment, BCG were found to have been phagocytized only by M cells, and none were found in absorptive cells. It was verified that M cells are the first entrance through which BCG invade the host and that they are transported from M cells to macrophages of the epithelium.

Animals↗
PubMed1985

Immunoassays of factor IX antigen using monoclonal antibodies.

Monoclonal antibodies to factor IX were produced by immunization of balb/c mice with purified factor IX and fusion of spleen cells with SP-1 murine myeloma cells. Antibody producing hybrids were detected by an enzyme linked immunoassay (ELISA) and by coagulation inhibitor (Bethesda type) methods. Monoclonal antibodies with titres of greater than 1 X 10(5) tested by the ELISA and 5000-8000 inhibitor units were obtained. A new ELISA method was developed using one of these monoclonal antibodies to quantitate factor IX antigen (IXAg) in plasma samples from patients with hereditary factor IX deficiency. In addition a two-site solid phase immunoradiometric assay (IRMA) for factor IX was established. The results of these new methods were compared with those obtained on the same plasma samples using conventional factor IX coagulation assays and the Laurell rocket method. The lower limit for the detection of IXAg by the ELISA was approximately 0.01 unit per ml whilst that for the IRMA was about 0.001 unit per ml (normal plasma = 1 unit per ml). The lower detection limit for IXAg using the Laurell rocket method was about 0.06 units per ml. The improved sensitivity of the new immunoassays enabled quantitation of low levels of IXAg in patients with moderately severe factor IX deficiency and confirmed the presence of excess IXAg compared to IX activity (IXC) in a relatively high proportion of cases (28 out of 51 tested). Results of testing plasma from obligate carriers confirm the suggestion that measurements of IXAg and IXC may improve the classification of carrier status in these kindred.

Animals↗
PubMed1984

Multiple catalytic properties of the purified and reconstituted cytochrome P-450 (P-450sccII) system of pig testis microsomes.

The catalytic properties of the testis microsomal P-450, termed P-450sccII, have been studied in a refined assay system which consists of P-450sccII (13 nmol of P-450 heme/mg of protein) and its reductase has been purified extensively from pig testis. The results indicated that P-450sccII was highly active in catalyzing hydroxylation of 11 beta-hydroxyprogesterone at the 17 alpha-position to give 21-deoxycortisol and cleavage of 17 alpha-hydroxyprogesterone at the 17-20 bond to give androstenedione with turnover numbers of 25 and 30 mol/min X mol of P-450, respectively. In contrast, many physiologically important corticosteroids we tested were found to be poor substrates for both the hydroxylase and lyase reactions. The possible reason for the importance of these substrate specificity of P-450sccII in production of both corticosteroids and androgens in the endocrine tissues is discussed. P-450sccII also catalyzed conversion of testosterone to androstenedione, but 18O experiments failed to show incorporation of atmospheric oxygen into the androstenedione formed. However, this does not preclude the possibility that the P-450-bound intermediate gem-diol stereoselectively dehydrates to give the nonlabeled ketosteroid. In addition to these steroid-oxidizing activities, P-450sccII revealed considerable specificities toward various xenobiotics, suggesting that P-450sccII and liver microsomal P-450 are basically similar as regards enzymatic functions and activities.

Adrenal Cortex Hormones↗
PubMed1984

The surgical reconstruction of fractures and fracture dislocations of the thoraco-lumbar spine.

Sixty patients have undergone surgical reconstruction of the injured thoraco-lumbar spine during the period 1968 to 1978 at the Spinal Unit of the National Murayama Hospital. The aim of treatment of any fracture, dislocation, or fracture-dislocation of the spine is to render it stable and painfree. This is best achieved by reduction and stabilisation of the involved segment of the spinal column. Where the posterior ligaments and intervertebral disc are ruptured healing of these structures with return to normal stability cannot be anticipated. In order to obtain permanent stability at the affected vertebral level we elect to perform anterior intervertebral fusion.

Adult↗
PubMed1984

Studies on precursor proteins PIVKA-II, -IX, and -X in the plasma of patients with 'hemorrhagic disease of the newborn'.

Factors II, IX, and X in the plasmas of 10 patients with 'hemorrhagic disease of the newborn' were investigated by means of electroimmunoassay and crossed immunoelectrophoresis (CIE). The biological activity was within 4.2-30 U/dl for factor II, 5.1-20 U/dl for factor IX, and 5.2-24 U/dl for factor X, whereas the immunological antigen was within 33-58, 25-50, and 35-60 U/dl, respectively. Thus, for all factors, 1.7 times more antigen than activity was present. The CIE pattern of factors II and IX in the presence of Ca++ ions clearly showed a biphasic precipitin arc, and in the absence of Ca++ ions, only one precipitin arc was observed. These results implied the presence of precursor proteins PIVKA-II and -IX in the plasma. However, even in the presence of Ca++ ions the CIE pattern of factor X antigen in the patient plasmas only showed a single precipitin arc with a slightly faster than normal electrophoretic mobility. PIVKA-II, -IX, and the abnormal factor X antigen (PIVKA-X) disappeared within 24 h after the patients were treated with vitamin K.

Adult↗
PubMed1984

[Effect of radiotherapy against advanced carcinoma of the rectum].

In treating advanced carcinoma of the rectum, we have actively used radiotherapy as an adjunct to surgery to enlarge the group of patients indicating surgery and improve the remote results. Of total 423 patients with rectal cancer treated by us in the past 16 years, 202 patients (47.8%) received radiotherapy. Preoperative radiotherapy was performed on 90 of these patients, postoperative radiotherapy on 73 patients, preoperative plus postoperative radiotherapy on 15 patients, and radiotherapy alone on 24 patients. The present study is mainly concerned with preoperative radiotherapy. The purpose of preoperative radiotherapy is to increase the number of patients suitable for surgery. We selected Dukes-C cases without distant metastasis as indications for preoperative radiotherapy, and treated them by 2-step irradiation with 3,000-6,000 rads using Linac after 2 weeks of preoperative observation. The gross and histologic evaluation of the results of irradiation permitted us to conclude that over 3,000 rads was necessary for preoperative radiotherapy. Comparison of the results between preoperative radiotherapy and control groups showed that local recurrence occurred in 6.7% of the radiotherapy group and 9.0% of the control, and 5-year-survival rate was 62.7% and 53.2% respectively, with prognosis improved in the radiotherapy group.

Combined Modality Therapy↗
PubMed1983

Mass screening of urea cycle diseases: a new mass screening method of hyperornithinemia by using two coupling enzymes.

We devised a new microfluorometric mass screening method for determining ornithine in only one blood disc of 3 mm in diameter (blood of 2-3 microliters) by use of two coupling enzymes, ornithine aminotransferase and delta'-pyrroline-5-carboxylate reductase. We could apply this method to some cases of gyrate atrophy of the choroid and retina. Our method can be applied in range of 0 to 12-16 nmoles or about 54.8 mg% or about 4 mM ornithine in blood. Ornithine values by our method were well correlated with those by an amino acid analyser.

Amino Acid Metabolism, Inborn Errors↗