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Biomedical subjects

K Kojima

Publications and source records attributed to K Kojima.

At least 361 records · Page 20Linked to original sources
PubMed1995

Activated protein C resistance: molecular mechanisms.

Activated protein C (APC) resistance is usually associated with a single DNA mutation predicting replacement of Arg506 by Gln in factor V (FV). Studies using synthetic peptides suggest that FV residues 493-506 provide factor Xa (FXa) and protein S binding sites. Biochemical studies were performed to test the hypothesis that the Arg506Gln FV mutation causes APC resistance and to define the nature of the resistance of Gln506-FVa to APC. Purified Gln506-FV conveyed APC resistance to FV-deficient plasma in APTT and FXa-1-stage assays. Purified Gln506-FVa, generated either by thrombin or by FXa, was resistant to APC. Nonetheless, Gln506-FVa was not completely resistant to APC since it was inactivated by APC approximately 10-fold slower than normal Arg506-FVa, probably due to cleavage at Arg306. This reduced but significant susceptibility of Gln506-FVa to APC inactivation may help explain why APC resistance, especially for heterozygotes, is a relatively moderate risk factor for venous thrombosis. Cardiolipin promotes APC anticoagulant activity better than FXa coagulant activity, and antibodies from some antiphospholipid antibody syndrome patients downregulate APC activity. Thus, acquired APC resistance may contribute to pathogenesis of thrombosis in the antiphospholipid antibody syndrome.

Amino Acid Sequence↗
PubMed1994

A novel oligosaccharide, GlcA beta 1-4Xyl beta 1-(4-methylumbelliferone), synthesized by human cultured skin fibroblasts.

Human skin fibroblasts were cultured in the presence of 4-methylumbelliferyl-beta-D-xyloside (Xyl-MU) using a mass-culture system with a microcarrier. The structures of Xyl-MU-induced sugars purified from the dialysable fraction of the incubation medium were investigated. In addition to glycosaminoglycans the elongation of which initiated by Xyl-MU has already been reported, and oligosaccharides similarly initiated by Xyl-MU, such as Gal-Gal-Xyl-MU, Gal-Xyl-MU and SA-Gal-Xyl-MU, a novel Xyl-MU-induced oligosaccharide was detected. This oligosaccharide was identified as GlcA beta 1-4Xyl beta 1-(4-methylumbelliferone) using sugar composition analysis, enzyme digestion, mass spectrometry and Smith degradation. Using this culture system, the amount of the new oligosaccharide produced increased with the incubation time, even after the production of glycosaminoglycan initiated by Xyl-MU and Gal-Xyl-MU had reached a plateau. These results suggest that this oligosaccharide may be involved in terminating the elongation of glycosaminoglycan chains that is initiated by Xyl-MU.

Benzoates↗
PubMed1994

[Results of radiotherapy for stage III uterine cervical carcinomas and preliminary study of combined radiotherapy and transarterial infusion chemotherapy].

This is a retrospective analysis of 55 patients with stage III carcinoma of the uterine cervix treated with radiation from November 1984 through December 1991. Eleven of the patients were treated with radiation and transarterial infusion chemotherapy (TAI), using cis-platinum and pepleomycin. The 3- and 5-year cumulative survival rates for all patients were 61% and 58%, respectively, and the 3-year cumulative survival rate for the group with combined radiation and TAI was 47%. According to initial failure site, the locoregional recurrence rate was 36.8%, and that for para-aortic lymph node metastasis and distant metastasis was 31.6%. The failure pattern was similar between the irradiation only group and the group with combined radiation and TAI. The incidence of intestinal complications of grades 1 and 2 was 20%. Irradiation combined with TAI did not increase the incidence of complications.

Adult↗
PubMed1994

[Evaluation of liver function in carbon tetrachloride-damaged rabbits by dynamic SPECT: comparison of 99mTc-GSA and 99mTc-Sn colloid].

Technetium-99m-DTPA-galactosyl human serum albumin (99mTc-GSA) is a new ligand that binds specifically to asialoglycoprotein receptors in hepatocytes. We performed liver dynamic SPECT using 99mTc-GSA and 99mTc-Sn colloid in nine normal control rabbits and 17 chronically CCI4-damaged rabbits (total 29 examinations), and also performed liver function tests (ICGR15, Alb, etc). Using the obtained dynamic SPECT data, we analyzed the liver kinetics of 99mTc-Sn colloid using a one-compartment model (hepatic blood flow [K]) and 99mTc-GSA using a two-compartment model (hepatic blood flow and receptor binding [K1], catabolism [K2]). As the CCl4-treated period increased, K1 decreased most significantly. K1 showed the most significant statistical correlation with the results of liver function tests, ICGR15 (p < 0.0001), Alb, PT, HP, Bil and GPT. Further, only K1 showed a correlation with the hepatic fibrosis of the HAI score. From the present results, liver dynamic SPECT using 99mTc-GSA may be said to provide a novel method for the evaluation of hepatic functional reserve.

Animals↗
PubMed1994

Experimental autoimmune panencephalitis and uveoretinitis transferred to the Lewis rat by T lymphocytes specific for the S100 beta molecule, a calcium binding protein of astroglia.

The pathogenic potential of autoimmune T cell responses to nonmyelin autoantigens was investigated in the Lewis rat using the astrocyte-derived calcium binding protein S100 beta, as a model nonmyelin autoantigen. The Lewis rat mounts a vigorous RT1B1 (major histocompatibility complex class II) restricted autoimmune response to an immunodominant S100 beta epitope (amino acid residues 76-91). The adoptive transfer of S100 beta-specific T cell lines induced a severe inflammatory response in the nervous system, but only minimal neurological dysfunction in naive syngeneic recipients. The inability of S100 beta-specific T cell transfer to induce severe disease was associated with a decreased recruitment of ED1+ macrophages into the central nervous system (CNS) in comparison with that seen in severe experimental autoimmune encephalomyelitis (EAE) induced by the adoptive transfer of myelin basic protein (MBP)-specific T line cells. Moreover, unlike encephalitogenic MBP-specific T cell lines, S100 beta-specific T cell lines exhibited no cytotoxic activity in vitro. Histopathological analysis also revealed striking differences in the distribution of inflammatory lesions in MBP- and S100 beta-specific T cell-mediated disease. In contrast to the MBP paradigm, S100 beta-specific T cell transfer induces intense inflammation not only in the spinal cord, but throughout the entire CNS and also in the uvea and retina of the eye. In view of the distribution of lesions throughout the grey and white matter of the CNS we propose to term this new model experimental autoimmune panencephalomyelitis (EAP) to differentiate it from EAE. These experiments demonstrate for the first time that nonmyelin CNS autoantigens can initiate a pathogenic autoimmune T cell response, although the nature of the target autoantigen profoundly influences the clinical and histopathological characteristics of the resulting autoimmune disease. This is not simply a consequence of the distribution of the autoantigen, as both MBP and S100 beta are coexpressed in many areas of the CNS, but reflects differences in the capacity of different regions of the CNS to process and present specific autoantigens. This new model of T cell-mediated autoimmune CNS disease exhibits a number of similarities to multiple sclerosis (MS), such as its mild clinical course and the involvement of areas of the brain and eye, which are absent in myelin-mediated models of EAE. Nonmyelin autoantigens may therefore play an unexpectedly important role in the immunopathogenesis of inflammatory diseases of the CNS.

Amino Acid Sequence↗
PubMed1994

Characterization of hydrolysis and transglycosylation by testicular hyaluronidase using ion-spray mass spectrometry.

Various oligosaccharides from hyaluronic acid, which were fluorescence-labeled and blocked by pyridylamination at the reducing terminal, were incubated as substrates or acceptors with bovine testicular hyaluronidase. Fluorescence-labeled reaction products in the reaction mixture were monitored selectively and directly by ion-spray mass spectrometry without chemical derivatization. As a result, several features of the relationship between oligosaccharides, substrates, and testicular hyaluronidase were clarified. When hexasaccharides or larger oligosaccharides having D-glucuronic acid at the nonreducing terminal were used as substrates, they were hydrolyzed sequentially to disaccharides from the nonreducing terminal, and these disaccharides were then transferred to other hexasaccharides. On the other hand, when heptasaccharides or larger oligosaccharides having N-acetyl-D-glucosamine at the nonreducing terminal were used as substrates, trisaccharides were released from the nonreducing terminal, and then also transferred to other hexasaccharides, thus forming nonasaccharides. Thus, the relationship between hydrolysis and transglycosylation reactions with testicular hyaluronidase was characterized using ion-spray mass spectrometry.

Animals↗
PubMed1994

Purification and characterization of nuclear phospholipase C specific for phosphoinositides.

A phosphoinositide-specific phospholipase C (PLC) was solubilized from the isolated nuclei of rat ascites hepatoma AH7974 cells by ultrasonication in 2 M KCl. The extract was then subjected to five steps of column chromatographies in the order of Sephacryl S-300, phosphocellulose, Mono Q, Mono S, and Superose 6. Four forms of PLC (tentatively designated as N1, N2, N3, and N4) were purified 440-1400-fold. N1, N2, N3, and N4 showed apparent molecular masses of 85, 83, 80, and 88 kDa, respectively, on SDS-polyacrylamide gel electrophoresis. N1 cross-reacted with the antibody against the delta 1 isoform, while the other three forms did not cross-react with any of the antibodies against PLC-delta 1, -gamma 1, -gamma 2, and -beta 1. They hydrolyzed phosphatidylinositol (PI), phosphatidylinositol 4-monophosphate (PIP), and phosphatidylinositol 4,5-bisphosphate (PIP2) but did not show any activities against phosphatidylcholine and phosphatidylethanolamine. They showed the same optimal pH:pH 6.5 for PI hydrolysis and pH 7.0 for both PIP and PIP2 hydrolyses. They absolutely required Ca2+ for activity, with optimal concentrations of 10(-3)-10(-5) M for PIP and 10(-4)-10(-5) M for PIP2. For PI hydrolysis, N1, N2, and N3 required a Ca2+ concentration higher than 10(-2) M whereas N4 revealed significant activity even at 10(-5) M Ca2+ concentrations. Two forms of plasma membrane PLC and three forms of cytosolic PLC were purified from AH7974 cells by the same procedure as for nuclear PLC. Comparative study with these three groups revealed that all of the purified PLC isoforms shared similar enzymological properties except N4, which showed an exceptionally high affinity to Mono S column and was active at low concentrations of Ca2+ for PI as substrate. Furthermore, when PLC isoforms of nuclei from adult resting rat liver were compared with those from regenerating rat liver after partial hepatectomy, a PLC isoform corresponding to N4 of AH7974 cells was found only in regenerating liver nuclei. From these results, it was suggested that the nuclei of growing liver cells possessed a unique form of PLC (N4).

Animals↗
PubMed1994

Highly polarized expression of carbohydrate-binding protein p33/41 (annexin IV) on the apical plasma membrane of epithelial cells in renal proximal tubules.

p33/41 is a Ca(2+)-dependent carbohydrate-binding protein and is identical to annexin IV, a member of the annexin protein family. The localization of p33/41 in bovine kidney specimens was investigated immunohistochemically by use of specific polyclonal antibodies. The most interesting finding on immunostaining was that p33/41 was highly concentrated in the apical plasma membrane of the epithelial cells in the proximal tubules contrary to the distribution throughout the cytoplasm in the papillary ducts and papilla epithelium. The enrichment of p33/41 in the apical membrane was confirmed by immunoblotting of the brush border membrane fraction prepared from a kidney homogenate. Sequential extraction with EDTA and Triton X-100, and a partition experiment with Triton X-114 revealed that most p33/41 associates with the renal brush border membrane in a Ca(2+)-independent manner and is integrated into the membrane like intrinsic membrane proteins.

Animals↗
PubMed1994

Animal models.

Different models of experimental autoimmune encephalomyelitis (EAE) have been successfully applied to investigate and manifold aspects of the autoimmune pathogenesis of multiple sclerosis. Studies using myelin-specific T-cell lines that transfer EAE to naive recipient animals established that only activated lymphocytes are able to cross the endothelial blood-brain barrier and cause autoimmune disease within the local parenchyma. All encephalitogenic T cells are CD4+ Th1-type lymphocytes that recognize autoantigenic peptides in the context of MHC class II molecules. In the case of myelin basic protein (MBP) specific EAE in the Lewis rat, the T-cell response is directed against one strongly dominant peptide epitope. The encephalitogenic T cells preferentially use one particular set of T-cell receptor genes. Although MBP is a strong encephalitogen in many species, a number of other brain protein are now known to induce EAE. These include mainly myelin components (PLP, MAG, and MOG), but also, the astroglial S-100 beta protein. Encephalitogenic T cells produce only inflammatory changes in the central nervous system, without extensive primary demyelination. Destruction of myelin and oligodendrocytes in these models requires additional effector mechanisms such as auto-antibodies binding to myelin surface antigens such as the myelin-oligodendrocyte glycoprotein.

Animals↗
PubMed1994

Hemiatrophy of the tongue due to hypoglossal schwannoma shown by MRI.

Schwannomas account for 8.5% of all intracranial tumours; more than 90% arise from the 8th cranial nerve. Only 42 cases of schwannoma of the hypoglossal nerve have been reported. A 59 year-old woman developed right hemiatrophy of the tongue, clearly demonstrated on MRI, as was a small hypoglossal schwannoma. High signal was seen in the atrophic side of the tongue on both T1- and T2-weighted images, as described in the literature.

Cranial Nerve Neoplasms↗
PubMed1994

Detection of mecA, femA, and femB genes in clinical strains of staphylococci using polymerase chain reaction.

MecA, a structural gene located on the chromosome of Staphylococcus aureus, characterizes methicillin-resistant S. aureus (MRSA), and femA and femB(fem) genes encode proteins which influence the level of methicillin resistance of S. aureus. In order to examine effectiveness of detecting mecA and fem genes in identification of MRSA, the presence of these genes in 237 clinically isolated strains of staphylococci was investigated by polymerase chain reaction (PCR). An amplified mecA DNA fragment of 533 base pairs (bp) was detected in 100% of oxacillin-resistant S. aureus, in 16.7% of oxacillin-sensitive S. aureus, in 81.5% of S. epidermidis, and in 58.3% of other coagulase-negative staphylococci (CNS). While the PCR product of femA (509 bp) or femB (651 bp) was obtained from almost all the S. aureus strains except for five oxacillin-resistant strains (2.5%), neither of these genes were detected in CNS. Therefore, the detection of femA and femB together with mecA by PCR was considered to be a more reliable indicator to identify MRSA by differentiating it from mecA-positive CNS than single detection of mecA.

Base Sequence↗
PubMed1994

Reserpine-induced cell transformation without detectable genetic effects in Syrian hamster embryo cells in culture.

Reserpine, a naturally occurring rauwolfia alkaloid, used mainly as an antihypertensive drug, was examined for its ability to induce cell transformation and genetic effects in Syrian hamster embryo (SHE) cells in culture. Treatment of SHE cells with 2 micrograms/ml of reserpine had no effect on cell growth, while 4 micrograms/ml of reserpine reduced the growth rate slightly and 8 micrograms/ml resulted in a significant inhibition of cell growth. Reserpine at doses of 4-8 micrograms/ml for 48 h induced a dose-related increase in morphological transformation of the cells. Reserpine-transformed colonies were morphologically indistinguishable from colonies transformed with benzo[a]pyrene (B[a]P) or other chemical carcinogens. Over the dose range that resulted in cell transformation, treatment of SHE cells with reserpine failed to induce any detectable gene mutations at two genetic loci, chromosomal abnormalities including structural and numerical changes, or DNA adduct formation. These findings indicate that reserpine may have carcinogenic potential by unknown mechanisms that do not include direct induction of gene and/or chromosome mutations.

Aneuploidy↗