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K Ichikawa

Publications and source records attributed to K Ichikawa.

At least 127 records · Page 7Linked to original sources
PubMed1999

[Quantitation and heterogeneity of serum alpha 2-macroglobulin].

alpha 2-Macroglobulin (alpha 2M) is a major protease inhibitor in human plasma. In this study, serum alpha 2M was determined by means of immunoelectrophoresis (IEP), rocket immunoelectrophoresis (R-IEP), laser nephelometry (LN) and single radial immunodiffusion (SRID) in 133 subjects. The values obtained by these methods coincided well in most specimens, but some specimens showed disagreement. The sera of alpha 2M deficiency found by IEP were analyzed by the other methods. We found that R-IEP gave the results of alpha 2M deficiency most frequently while the other methods gave the results of normal alpha 2M level for some specimens. We studied on the presumption that the phenomenon is due to heterogeneity in molecular weight of alpha 2M. After alpha 2M was purified by affinity chromatography and gel filtration chromatography, we further employed gel-filtration on a high-performance liquid chromatography (HPLC) to isolate alpha 2M with different molecular size. Two peaks of immunoreactive alpha 2M were found by the gel-filtration HPLC. When we performed IEP for both portions, the first portion with higher molecular size showed larger rate of migration than the second portion. Serum alpha 2M quantitation with SRID is not appropriate because molecular weight influences on the determination by SRID. We conclude that R-IEP is best suitable for the detection of decrease of serum alpha 2M, although this method requires expertness of manipulation.

Adolescent↗
PubMed1999

[The antiphospholipid syndrome].

Antiphospholipid antibodies such as anticardiolipin antibodies and lupus anticoagulant are frequently detected in sera from patients with systemic lupus erythmatosus and from those with related autoimmune disorders. Thromboembolic manifestations, fetal losses or thrombocytopenia in association with antiphospholipid antibodies, are hallmarks of the antiphospholipid syndrome (APS). Recent studies indicates that anticardiolipin antibodies bind to beta 2-glycoprotein I and that a part of lupus anticoagulant binds to beta 2-glycoprotein I or to prothrombin. Antiphospholipid antibodies might induce thrombosis by altering the function of vascular endothelial cells or by accelerating the progression of atherosclerosis. Warfarin, heparin or low dose aspirin have been recommended to prevent recurrent episodes of thrombosis in patients with the APS.

Antiphospholipid Syndrome↗
PubMed1999

[Evaluation of child-rearing environmental factors that affect the occurrence of sudden infant death syndrome: interview conducted by public health nurses].

PURPOSE: We examined the child-rearing environmental factors that affect the occurrence of sudden infant death syndrome (SIDS) by using a nation-wide survey. METHOD: Infants who died due to SIDS between January 1996 and June 1997 in Japan were identified from death certificates. Controls of the same sex, birthplace, and birth months as the corresponding SIDS were chosen from birth certificates. Interviews of both cases and controls were undergone in January and February 1998 by public health nurses. RESULTS: The following Child-rearing factors exhibited a significant relationship with the occurrence of SIDS: 1. Concerning the sleeping position, the prone position was associated with increased risk compared to the supine position, with an odds ratio of 3.02 (95% c.i. 2.07-4.65). 2. Regarding the feeding method, artificial feeding only demonstrated a higher risk than breast feeding only, with an odds ratio of 4.92 (95% c.i. 2.78-9.63). 3. With regard to smoking, infants with both parents who smoked exhibited a higher risk than infants where neither parents smoked, with an odds ratio of 3.50 (95% c.i. 1.74-8.32).

Child Rearing↗
PubMed1998

Cloning of two new human helicase genes of the RecQ family: biological significance of multiple species in higher eukaryotes.

Two new human DNA helicase genes, RecQ4 and RecQ5, that belong to the RecQ helicase family were cloned and characterized. The addition of these genes increases the total to five helicase genes in the human RecQ family, which includes helicases involved in Bloom and Werner syndromes, the genetic diseases manifesting the distinctive but overlapping clinical phenotypes of immunodeficiency, premature aging, and an enhanced risk of cancer. The RecQ4 helicase is as large as the Bloom (BLM) and Werner (WRN) helicases, and its gene expression profile is organ-specific, resembling that of BLM helicase. In contrast, the RecQ5 helicase has a low molecular weight, similar to the human progenitor RecQ1 helicase, and is expressed in all the organs examined. All five human helicase genes are expressed in cultured K562 leukemia and fibroblast cells. Synchronized K562 cell cultures showed that the genes RecQ4 and BLM, and RecQ1 and WRN, seem to be upregulated at the G1/S and G2/M phases, respectively, of the cell cycle. The biological significance of multiple species of human RecQ helicases, which are apparently nonessential for life but may be related to distinct diseases, is discussed in light of the fact that unicellular organisms, like Escherichia coli and yeast, contain only one species of helicase of this particular family.

Adenosine Triphosphatases↗
PubMed1998

Interaction of myosin phosphatase target subunit 1 with the catalytic subunit of type 1 protein phosphatase.

In the investigation of the sequences of myosin phosphatase target subunit 1 (MYPT1) involved in binding the substrate and catalytic subunit of protein phosphatase type 1 (PP1c), fragments of MYPT1 were prepared and characterized. The shortest fragment capable of full activation of PP1c contained the sequence of residues 1-295. Within this fragment, the N-terminal sequence of residues 1-38 is involved in activation of PP1c (kcat) and the ankyrin repeats (residues 39-295) were involved in substrate binding (Km). The ankyrin repeats alone (residues 39-295) and the C-terminal fragment of residues 667-1004 did not activate PP1c. Using gel filtration, an interaction with PP1c was detected for the sequences of residues 1-295, 17-295, and 1-170. Affinity columns were prepared with various fragments to assess binding of PP1c. Binding to the column with residues 1-295 was strongest, followed by the binding to the column with residues 1-170. A weak interaction was observed with the column with residues 1-38. The column with residues 1-295 was used to isolate PP1c from gizzard. The purified PP1c was activated by MYPT1 and fragments to a greater extent than previous preparations. These results suggest that the N-terminal sequence (residues 1-38) and the ankyrin repeats are involved in binding PP1c. The C-terminal ankyrin repeats appear to be dominant, but there is an interaction of PP1c with the N-terminal ankyrin repeats. The N-terminal peptide has two apparent functions, the binding of PP1c via the consensus binding sequence and activation of PP1c by the sequence of residues 1-16.

Animals↗
PubMed1998

The delta isoform of protein phosphatase type 1 is localized in nucleolus and dephosphorylates nucleolar phosphoproteins.

The immunolocalization and substrates of protein phosphatases present in nucleolus were investigated using Swiss 3T3 cells and Novikoff hepatoma ascites cells. The protein phosphatase activity was detected in the extract of the isolated nucleoli and its activity was inhibited by okadaic acid with IC50 value of 160 nM. Immunoblotting assay indicated that PP1c delta but not PP1c alpha, PP1c gamma 1, and PP2Ac was localized in the isolated nucleoli. Confocal microscopy showed that PP1c delta was localized in nucleoli, nuclei, and cytosol, though the intensity of fluorescence at the nucleoli was stronger than that of the cytosol or nuclei. PP1c delta was co-localized with the major nucleolar phosphoprotein B23 at nucleoli. The phosphatase was capable of dephosphorylating several proteins in the nucleolus, including B23. The Km of PP1 for the recombinant B23.1, phosphorylated by endogenous kinase(s), was 3.5 microM. These results indicate that PP1c delta is the major serine/threonine phosphatase present in nucleolus and it dephosphorylates nucleolar phosphoproteins, including B23.

3T3 Cells↗
PubMed1998

Human beta 2-glycoprotein I binds to endothelial cells through a cluster of lysine residues that are critical for anionic phospholipid binding and offers epitopes for anti-beta 2-glycoprotein I antibodies.

Beta 2-Glycoprotein I (beta 2GPI) is a phospholipid-binding protein recognized by serum autoantibodies from the anti-phospholipid syndrome both in cardiolipin- and beta 2GPI-coated plates. We found that: 1) recombinant wild-type beta 2GPI bound to HUVEC and was recognized by both human monoclonal IgM and affinity-purified polyclonal IgG anti-beta 2GPI anti-phospholipid syndrome Abs; and 2) a single amino acid change from Lys286 to Glu significantly reduced endothelial adhesion. Double and triple mutants (from Lys284,287 to Glu284,287, from Lys286,287 to Glu286,287, and from Lys284,286,287 to Glu284,286,287) completely abolished endothelial binding. A synthetic peptide (P1) spanning the sequence Glu274-Cys288 of the beta 2GPI fifth domain still displayed endothelial adhesion. Another peptide (P8), identical with P1 except that Cys281 and Cys288 were substituted with serine residues, did not bind to HUVEC. Anti-beta 2GPI Abs, once bound to P1 adhered to HUVEC, induced E-selectin expression and up-regulated IL-6 secretion. Control experiments conducted with irrelevant Abs as well as with the P8 peptide did not show any endothelial Ab binding nor E-selectin and IL-6 modulation. Our results suggest that: 1) beta 2GPI binds to endothelial cells through its fifth domain; 2) the major phospholipid-binding site that mediates the binding to anionic phospholipids is also involved in endothelial binding; 3) HUVEC provide a suitable surface for beta 2GPI binding comparable to that displayed by anionic phospholipids dried on microtiter wells; and 4) the formation of the complex between beta 2GPI and the specific Abs leads to endothelial activation in vitro.

Amino Acid Sequence↗
PubMed1998

Physical map of the human chromosome 8p12-p21 encompassing tumor suppressor and Werner's syndrome gene loci.

Detailed physical maps of the human genome are important resources for identification and isolation of genes responsible for diseases and for the study of their structure and function. We constructed a 2.0-Mb high-resolution physical map within the human chromosome 8p12-p21 region extending from marker D8S131 to D8S283. The map comprises a series of contigs mostly P1/PAC clones, which span the loci of potential tumor suppressor genes and the Werner's syndrome gene. Each P1/PAC DNA was defined by its size, restriction sites, terminal sequences, intermarker distances and location relative to major genes and markers. The genes on these P1/PAC DNAs were analyzed by an exon amplification method to determine their locations. The genes newly found by the exon amplification method together with other known genes, including those of glutathion reductase, a general transcription factor, protein phosphatase 2A beta subunit and Werner's syndrome, were precisely mapped within the contigs. These P1/PAC DNAs are useful reagents for the generation of new microsatellite markers to narrow the candidate region of the tumor suppressor gene(s) and/or genes responsible for other diseases, which are believed to exist in this region by linkage analysis.

Animals↗
PubMed1998

A new isoform of human myosin phosphatase targeting/regulatory subunit (MYPT2): cDNA cloning, tissue expression, and chromosomal mapping.

Myosin phosphatase target subunit 1 (MYPT1), a subunit of myosin phosphatase, plays a pivotal role in the regulation of myosin phosphatase activity. Here we have cloned a novel isoform of MYPT1, termed MYPT2, from a human brain cDNA library screened with a cDNA fragment of rat MYPT1. Overlapping clones indicated an open reading frame of 3763 nucleotides and a predicted polypeptide of mass 110,398. Ankyrin repeats and leucine zipper motifs were identified for the sequences 57-316 and 956-982, respectively. Overall, the deduced amino acid sequence of MYPT2 was 61% identical to MYPT1. MYPT2 gene is transcribed abundantly in heart and skeletal muscle, while Western blots using an antibody specific for MYPT2 showed exclusive expression of MYPT2 in heart and brain. A recombinant of the N-terminal two-thirds of MYPT2 bound to the catalytic subunit of type 1 phosphatase (delta isoform) and increased activity toward phosphorylated myosin light chain. In situ hybridization localized the human MYPT2 gene on chromosome 1q32.1, compared to the chromosomal location 12q15-q21-2 for MYPT1. It is suggested that the products of the two gene families of myosin phosphatase target subunit may be localized differently among various tissues.

Amino Acid Sequence↗
PubMed1998

Arterial disease and thrombosis in the antiphospholipid syndrome: a pathogenic role for endothelin 1.

OBJECTIVE: To explore a possible correlation between endothelin 1 (ET-1), the most potent endothelium-derived contracting factor that modulates vascular smooth muscle tone, and arterial disease in patients with the antiphospholipid syndrome (APS). METHODS: Plasma levels of ET-1 were measured in APS patients with (n = 16) and without (n = 11) arterial thrombosis and in non-APS patients with arterial thrombosis (n = 9). In addition, steady-state prepro-ET-1 messenger RNA (mRNA) levels were determined in endothelial cells treated with a range of human monoclonal anticardiolipin antibodies (aCL) (as anti-beta2-glycoprotein I antibodies) by semiquantitative 32P-dCTP-labeled reverse transcription-polymerase chain reaction. RESULTS: Compared with healthy controls, markedly increased plasma levels of ET-1 were found in APS patients with arterial thrombosis (2.00 +/- 0.87 versus 0.96 +/- 0.37 pg/ml; P = 0.0001) but not in other groups. Three human monoclonal aCL induced prepro-ET-1 mRNA levels significantly more than did control monoclonal antibody lacking aCL activity. CONCLUSION: Plasma ET-1 levels correlated significantly with a history of arterial thrombosis in patients with APS. Prepro-ET-1 mRNA was induced by human monoclonal aCL in the in vitro experimental system. The induction of ET-1 by antiphospholipid antibodies might contribute to increased arterial tone, leading to vasospasm and, ultimately, to arterial occlusion.

Adult↗
PubMed1998

Effects of human monoclonal anticardiolipin antibodies on platelet function and on tissue factor expression on monocytes.

OBJECTIVE: To investigate the effect of human monoclonal anticardiolipin antibodies (aCL) on platelet interaction with the subendothelium under flow conditions and on tissue factor (TF) expression on normal monocytes. METHODS: Three monoclonal IgM aCL (TM1B3, GR1D5, and EY2C9) and 2 affinity-purified IgM aCL were studied. Immunoglobulins were added to normal blood and perfused through chambers containing denuded vascular segments. Platelet interactions were morphometrically evaluated by determining the percentage of total surface covered by platelets (PCS) or by large aggregates of thrombi platelets (TP). Expression of TF on monocytes was measured after immunoglobulin incubation with normal mononuclear cells. RESULTS: Significant increases in the total PCS and expression of TF were observed using all aCL. Increased levels of TP were induced by all aCL except EY2C9 (obtained from a patient without thrombosis). Previous incubations of these aCL with subendothelial surfaces did not increase platelet interaction. CONCLUSION: The effects of aCL on platelet function may help to explain the pathophysiology of thrombosis in the antiphospholipid syndrome.

Adult↗
PubMed1998

Process development for high-level secretory production of carboxypeptidase Y by Saccharomyces cerevisiae.

In order to develop a production process for carboxypeptidase Y (CPY, yeast vacuolar protease) secreted by Saccharomyces cerevisiae KS58-2D, medium composition, culture conditions, and expression systems were investigated. We found that the addition of histidine to thiamine-free medium, in which CPY production was almost negligible, raised the intracellular thiamine level, resulting in the increase of CPY production. On the basis of the choice of an expression system that uses an inducible GAL10 promoter, reassessment of histidine concentration in the medium, and optimization of the pH level during cultivation (pH 6.5), active CPY was secreted in a quantity of over 400 mg/l, which was more than tenfold that higher than that previously reported. The process developed could be easily scaled-up to industrial-scale fermentation.

Biomass↗
PubMed1998

Acute traumatic injury of the distal descending aorta associated with thoracic spine injury.

A rare case of traumatic injury of the distal descending aorta associated with thoracic spine injury is reported. A 21-year-old man was admitted after a traffic accident. Thoracic CT and angiography demonstrated a false aneurysm of the distal descending aorta and a compression fracture of the eleventh thoracic vertebra. At emergency surgery, a transverse linear tear at the level of the aortic hiatus was confirmed and repaired.

Accidents, Traffic↗
PubMed1998

Age-related changes in the cerebrospinal fluid level of beta-endorphin and substance P. Short communication.

To evaluate the early age-related changes in neuropeptides, we have measured the cerebrospinal fluid (CSF) levels of beta-endorphin and substance P in young patients over a range of ages. Specimens of CSF were obtained from 39 neurologically normal children, aged 1 month to 10 years of age, and in 9 adult controls. CSF levels of both neuropeptides were observed to peak during the first year of life, and showed a negative correlation with increasing age. A significant positive correlation was observed between the CSF level of beta-endorphin and that of substance P.

Adult↗
PubMed1998

Advanced glycosylation end products induced tissue factor expression in human monocyte-like U937 cells and increased tissue factor expression in monocytes from diabetic patients.

Tissue factor (TF) plays a central role in the initial activation of the extrinsic coagulation pathway and is thought to be involved in the development of atherosclerosis and thrombosis. The effect of advanced glycosylation end products (AGEs) on TF expression and its mechanism were assessed by flow cytometric analysis. Human macrophage-like U937 cells, which were shown to contain mRNA encoding the receptors of advanced glycosylation end products (RAGE), expressed TF in a dose-dependent manner on incubation with AGE-albumin. AGE-albumin-induced TF expression was completely inhibited by the anti-oxidant agents, catalase and probucol. TF expression in peripheral monocytes from normal volunteers was also increased by AGE-albumin. Finally, TF expression in monocytes from individuals with diabetes mellitus, in whom the concentration of circulating AGEs is reported to be increased, was higher than that in monocytes from normal controls. These results suggest that AGE-induced TF expression in macrophages/monocytes is mediated by oxidant stress. AGEs may promote thrombosis and the development of atherosclerosis by inducing TF expression in monocytes in patients with diabetes mellitus.

Albumins↗