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Biomedical subjects

K Nagata

Publications and source records attributed to K Nagata.

At least 829 records · Page 46Linked to original sources
PubMed1989

[Changes in serum RNase activities in chronic phase and acute crisis of chronic myelocytic leukemia].

We investigated serum acid and alkaline RNase activities in 16 cases of acute crisis of chronic myelocytic leukemia (CML), 21 cases of untreated CML, and 13 cases of treated CML, to clarify clinical significance of the determination of RNase activities in acute crisis of CML. We obtained results as follows; the ratio of acid to alkaline Rnase activities (Ac/Al ratio) of chronic phase of CML was 1.64 +/- 0.47 (mean +/- SD) in the untreated cases, and was 1.32 +/- 0.16 in the treated cases. The Ac/Al ratio always indicated over 1.0 in the chronic phase of CML without any relationship to treatments. On the other hand, in the cases of acute crisis, the Ac/Al ratio was significantly lowered (0.94 +/- 0.22) as compared to the chronic phase of CML (p less than 0.001), and was similar to that of acute leukemia. The acid and alkaline RNase activities of the blast from the patients with acute crisis of CML showed remarkably lower value than those of leukemic cells from patients with chronic phase of CML. Therefore, it was Suggested that the return to normal range of Ac/Al ratio in acute crisis of CML depended on marked decrease of RNase activities of blasts. Thus, serial determinations of the enzyme activities are considered to be one of useful tools for prediction of acute crisis of CML.

Adult↗
PubMed1989

[Clinical research on specific IgE and IgG4 antibodies in allergic children. Correlation specific IgE and IgG4 antibodies to food allergens to other allergic factors].

We examined the correlation specific IgE and IgG4 antibodies to food allergens to other allergic factors in 150 asthmatic children by Multiple Factor Analysis-Type II. The following results were obtained. 1) 3 explanation variables (IgE RIST, Eosinophil count, Family history of allergy) had the strong influence power to 8 objective variables of food allergens. 2) By calculating the category score of explanation variables, the high IgE RAST score to Dermatophagoides farinae group had the strong influence power to the high score groups of IgE RAST and IgG4 antibody titers to food allergens. The fact indicated the linkage between specific IgE and IgG4 antibodies to food allergens to specific IgE antibody to Dermatophagoides farinae. 3) In the same way, the severe group of asthma had the strong influence power to the high score groups of IgE RAST and IgG4 antibody titers to food allergens, and specific IgG4 antibody group had a same directivity of specific IgE antibody group to the other allergic factors. So specific IgG4 antibody may play a "role of reaginic antibody".

Adolescent↗
PubMed1988

Enhancer of human polyoma JC virus contains nuclear factor I-binding sequences; analysis using mouse brain nuclear extracts.

Neurotrophic human JC virus carries a 98 bp duplicate enhancer responsible for tissue-specific gene expression. DNase I footprinting studies using mouse brain nuclear extracts revealed weak (pseudo NFI motif) and strong (NFI motif) nuclear factor I-binding sequences just upstream (at 229) and in the middle (at 156 and 58) of the enhancer, respectively. In vitro transcription driven in brain extracts demonstrated that the NFI motif is a possible transcription control element. Together with previous observations (Khalili, K., Rappaport, J. and Khoury, G. (1988) EMBO J. 7, 1205-1210 (20], the NFI motif is suggested to play an important role in early gene expression of JCV.

Animals↗
PubMed1988

Gene conversion and differential regulation in the rat P-450 IIA gene subfamily. Purification, catalytic activity, cDNA and deduced amino acid sequence, and regulation of an adult male-specific hepatic testosterone 15 alpha-hydroxylase.

Previous studies on regulation of the rat hepatic P-450 IIA1 cDNA have provided evidence for a second gene closely related to but regulated in a manner quite distinct from P-450 IIA1. Experiments were carried out to isolate the cDNA for this second P-450 gene, designated IIA2, in order to study more directly its regulation and relationship to IIA1. A full length cDNA to IIA2 was isolated from an adult male rat liver lambda gt11 library and sequenced completely. The IIA2 cDNA shared 93% nucleotide and 88% deduced amino acid similarities with the previously characterized IIA1 cDNA (Nagata, K., Matsunaga, T., Gillette, J., Gelboin, H. V., and Gonzalez, F. J. (1987) J. Biol. Chem. 262, 2787-2793). The protein, deduced from the cDNA, contained 492 amino acids and a calculated Mr of 56,352. Comparison of the IIA1 and IIA2 cDNAs revealed areas of low nucleotide similarity interspersed with areas of absolute identity, suggesting that gene conversions have played a role in the evolution of the IIA subfamily. Expression of IIA1 and IIA2 mRNAs in rat liver during development was studied with use of specific oligonucleotide probes. IIA1 mRNA was increased within 1 week after birth in both male and female rats; however, its postpubertal expression was decreased in males yet remained elevated in females. In contrast, IIA2 mRNA was markedly induced in male rat liver at puberty but was not detectable in females at any age examined. Furthermore, only IIA1 mRNA was induced by treatment of rats with 3-methylcholanthrene. Although IIA1 and IIA2 mRNAs were actively expressed in hepatic tissue, no evidence for their expression was found in lung, kidney, or intestine, suggesting that the IIA genes have tissue-specific promoters. Reconstituted enzyme assays on the purified protein products P-450 IIA1 and P-450 IIA2 showed that, although both enzymes share considerable sequence similarity, their positional specificities toward the prototype substrate testosterone are strikingly different.

Amino Acid Sequence↗
PubMed1988

Production of growth potentiating factor(s) for autologous blast cells by acute myeloblastic leukemia cells.

The effects of media conditioned by leukemic cells from 11 acute myeloblastic leukemia patients on the growth of autologous blast progenitors were studied. First, it was shown that T-cell-depleted leukemic cells from some patients release high levels of colony-stimulating activity into the culture medium, whereas following further depletion of phagocytic cells, the levels of colony-stimulating activity become undetectable. Second, media conditioned by purified blast cell fraction depleted of both T-cells and phagocytic cells potentiated autologous blast progenitor growth both in methylcellulose and suspension cultures stimulated by optimal concentration of media conditioned by human bladder carcinoma line 5637. Third, media conditioned by these purified blast cells generally did not contain measurable colony-stimulating activity or interleukin 1, whereas substantial levels of granulocyte colony-stimulating factor, granulocyte-macrophage colony-stimulating factor, and interleukin 1 were observed in media conditioned by human bladder carcinoma line 5637 using bioassays and specific immunological assays. Therefore, purified blast cell fraction from acute myeloblastic leukemia patients appears to produce factor(s) other than granulocyte colony-stimulating factor, granulocyte-macrophage colony-stimulating factor, or interleukin 1, which potentiate the growth of autologous blast progenitors both in methylcellulose and suspension cultures.

Adult↗
PubMed1988

Purification and characterization of two GTP-binding proteins of 22 kDa from human platelet membranes.

Two GTP-binding proteins (G-proteins) of 22 kDa were purified to near homogeneity from a sodium cholate extract of human platelet membranes by successive chromatographies on DEAE-Sephacel, Ultrogel AcA-44, phenyl-Sepharose CL-4B, Mono Q HR5/5 and hydroxyapatite columns. They bound maximally 0.89 mol of [35S]guanosine 5'-(3-O-thio)triphosphate per mol of both purified proteins, and this binding was inhibited by GTP and GDP but not by ATP and AppNHp. Their molecular masses were somewhat lower than that of ras p21 and they were not recognized by an anti-v-Ki-ras p21 antibody. These results indicate that human platelet membranes contain at least two low-molecular-mass G-proteins distinct from ras p21, in addition to the heterotrimeric G-proteins, the alpha-subunits of which possess molecular mass values of about 40 kDa.

Blood Platelets↗
PubMed1988

GTP-binding proteins in human platelet membranes serving as the specific substrate of islet-activating protein, pertussis toxin.

Two GTP-binding proteins serving as the specific substrate of islet-activating protein (IAP), pertussis toxin, were purified from human platelet membranes as heterotrimers with an alpha beta gamma-subunit structure. The alpha of the major IAP substrate had a molecular mass of 40 kDa and differed from that of Gi 1 or Go previously purified from brain membranes. The partial amino acid sequences of the 40 kDa alpha completely matched with the sequences which were deduced from the nucleotide sequences of the human Gi 2 alpha gene. On the other hand, the alpha of the minor IAP substrate purified from human platelets was about 41 kDa and cross-reacted with an antibody raised against alpha of brain Gi 1 (Gi 1 alpha). These results indicate that the major IAP substrate present in human platelet membranes is a product of the Gi 2 alpha gene.

Blood Platelets↗
PubMed1988

Biosynthesis of a novel transformation-sensitive heat-shock protein that binds to collagen. Regulation by mRNA levels and in vitro synthesis of a functional precursor.

The synthesis of a major collagen-binding glycoprotein of molecular weight 47,000 was previously shown to be altered by malignant transformation as well as by heat shock in chick embryo fibroblasts (Nagata, K., and Yamada, K.M. (1986) J. Biol. Chem. 261, 7531-7536 and Nagata, K., Saga, S., and Yamada, K.M. (1986) J. Cell Biol. 103, 223-229). In this paper, we examined the synthesis of this heat shock protein (hsp47) in terms of possible functional precursors and its regulation after heat shock and transformation by Rous sarcoma virus. Actinomycin D inhibited the induction of hsp47 after heat shock. Messenger RNAs purified from chick embryo fibroblasts (CEF), heat-treated CEF, and transformed CEF were analyzed in an in vitro translation system. In vitro translated products readily bound to gelatin-Sepharose, and levels were increased after heat shock and decreased after transformation. The increase in mRNA after heat shock was shown more directly by Northern assay using a synthetic oligonucleotide probe. We identified two putative precursors of hsp47 using an in vitro translation/processing system and tunicamycin: one is a 42-kDa primary translation product and the second is a 41-kDa polypeptide lacking signal peptide and carbohydrate moieties. Both of these precursors are biologically active as determined by gelatin-binding activity, in contrast to the lack of binding activity of precursors in several other membrane-associated receptor systems.

Animals↗
PubMed1988

Characterization of a novel transformation-sensitive heat-shock protein (HSP47) that binds to collagen.

The synthesis of a major collagen-binding glycoprotein of molecular weight 47,000 was previously shown to be regulated by malignant transformation as well as by heat shock in chick embryo fibroblasts. The 47-kDa protein purified from chick embryos was characterized biochemically, and was found to exist as a monomer in native form. Its composition was enriched in basic amino acids and glycine, with fewer acidic residues and virtually no cysteine. N-terminal amino acid sequencing covering 36 residues revealed a single, novel sequence with an internal tandem repeat of Asp-Lys-Ala-Thr-Thr-Leu-Ala and Asp-Arg-Ser-Thr-Thr-Leu-Ala.

Amino Acid Sequence↗
PubMed1988

An enzymatic method for the alpha-amylase assay which comprises a new procedure for eliminating glucose and maltose in biological fluids.

An alpha-amylase assay in biological fluids, characterized by a new procedure for eliminating glucose and/or maltose, was developed. The reagent includes thermostable glucokinase, glucosephosphate isomerase and phosphofructokinase obtained from a thermophile Bacillus stearothermophilus. Up to 4,000 mg/dl glucose or 600 mg/dl maltose had no effect on the measured value of alpha-amylase activity when measured at 37 degrees C, even at a serum volume fraction in the reagent of 1/50. Alpha-Amylase activity was monitored by the absorbance increase at 340 nm due to NADPH production. The assay has a high degree of precision, with the within-run and day-to-day coefficients of variation being 2.17% at 75.0 U/l and 2.49% at 112 U/l, respectively, and is linear up to about 2,500 U/l. Regarding interferences, bilirubin, urate, ascorbate, pyruvate, EDTA, sodium fluoride and others were found to have no effect on the assay, and the reagent in solution is stable for about 2 wk at low temperatures (6-8 degrees C).

Body Fluids↗
PubMed1988

Concanavalin A- or phorbol ester-induced translocation of protein kinase C in thymoma cells from a patient with myasthenia gravis.

We have examined the localization of phospholipid/calcium-dependent protein kinase (protein kinase C) in thymoma cells, which were resected from a patient with myasthenia gravis. Upon stimulation with 4 micrograms/ml of concanavalin A (Con A) for 30 min, protein kinase C activity in the cytosolic fraction was increased from 7.44 pmol/min per 10(7) cells to 11.42 pmol/min per 10(7) cells. On the other hand, membrane-associated protein kinase C activity was decreased from 1.69 to 0.71 pmol/min per 10(7) cells. On the contrary, 10(-7) mol/l tetradecanoyl phorbol acetate (TPA) decreased cytosolic protein kinase C activity from 9.31 to 8.04 pmol/min per 10(7) cells, while membrane-associated protein kinase C activity was increased from 1.69 to 2.94 pmol/min per 10(7) cells. Several endogenous phosphorylated proteins (mol wt 20,000, 23,000) were observed as inferred by SDS-polyacrylamide gel electrophoresis. These findings indicated that Con A and TPA produce differential translocation of protein kinase C.

Concanavalin A↗
PubMed1988

Biphasic effects of 12-O-tetradecanoylphorbol-13-acetate on the cell morphology of low calcium-grown human epidermal carcinoma cells: involvement of translocation and down regulation of protein kinase C.

The present study was performed to investigate involvement of protein kinase C in the biphasic effects of 12-O-tetradecanoylphorbol-13-acetate (TPA) on cell morphology in low calcium (0.07 mM)-grown cells of a human epidermal squamous cell carcinoma cell line. The low calcium-grown cells formed no desmosomal cell-cell contact and showed roughly circular arrangements of keratin intermediate filaments around the nucleus. Treatment with 10 ng/ml of TPA induced a rapid formation (within 15 min) of cell-cell contact and reorganization of keratin intermediate filaments from a circular organization to a radial arrangement in these low calcium-grown cells. These structural phenomena were associated with a transient increase in membrane-bound protein kinase C activity. However, the prolonged treatment longer than 24 h led to a prominent decrease in the number of cell-cell contacts, that had been once formed, and caused fibroblastic changes of cell morphology in association with a decrease in the membrane-bound protein kinase C activity. Addition of 20 microM 1-(5-isoquinolinesulfonyl)-2-methylpiperazine dihydrochloride, a potential inhibitor of protein kinase C, to the medium with TPA blocked the formation of cell-cell contact. Addition of 1-(5-isoquinolinesulfonyl)-2-methylpiperazine dihydrochloride alone to normal calcium-grown cell cultures exhibiting cell-cell contact resulted in a decrease in the number of cell-cell contacts and in the fibroblastic morphological changes after 24-h incubation. These results suggest that the effects of TPA are biphasic as follows: the initial stage, inducing cell-cell contact formation associated with the translocation of protein kinase C activity from the cytosol to the membrane; and the late stage, exhibiting a fibroblastic morphological change with a decrease in the number of cell-cell contacts associated with the down regulation of this enzyme activity by TPA.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1988

Translational regulation of influenza virus mRNAs.

cDNAs for genome RNAs of influenza virus A/PR/8/34 were cloned, and portions containing the ATG for initiation codon of translation were inserted into the 5' leader sequence of the chloramphenicol acetyltransferase (CAT) gene in a pSV2cat vector. When transfected cells were super-infected with influenza virus, the CAT activity was found to vary in a time-dependent fashion: A construct containing a cDNA segment for the nonstructural (NS) protein directed the highest activity during the early stage of infection, while a construct containing a cDNA segment for the neuraminidase (NA) directed the highest activity during the late stage of infection. This time-dependent variation in the CAT activity is in good agreement with that of the synthesis rate of respective viral proteins in infected cells. We propose that the translational efficiency of viral mRNA is subjected to temporal control following viral infection, although viral protein synthesis itself is regulated primarily at the level of mRNA synthesis.

Base Sequence↗
PubMed1988

Topographic EEG in brain ischemia--correlation with blood flow and metabolism.

A review is made of topographic EEG analyses in patients with brain ischemia. Features correlating EEG measures and vascular and metabolic studies are presented and discussed within the content of the stage of ischemia. Quantitative EEG data was found to provide useful information regarding the effects of brain ischemia.

Alpha Rhythm↗
PubMed1988

Stimulation of arachidonic acid release by guanine nucleotide in saponin-permeabilized neutrophils: evidence for involvement of GTP-binding protein in phospholipase A2 activation.

Addition of a guanine nucleotide analog, guanosine 5'-O-(thiotriphosphate) (GTP gamma S)(1-100 microM) induced release of [3H]arachidonic acid from [3H]arachidonate-prelabeled rabbit neutrophils permeabilized with saponin. The chemotactic peptide N-formyl-methionyl-leucyl-phenylalanine (fMLP)-induced arachidonate release was enhanced by GTP gamma S, Ca2+, or their combination. Ca2+ alone (up to 100 microM) did not effectively stimulate lipid turnover. However, the combination of fMLP plus GTP gamma S elicited greater than additional effects in the presence of resting level of free Ca2+. The addition of 100 microM of GTP gamma S reduced the Ca2+ requirement for arachidonic acid liberation induced by fMLP. Pretreatment of neutrophils with pertussis toxin resulted in the abolition of arachidonate release and diacylglycerol formation. Neomycin (1 mM) caused no significant reduction of arachidonate release. In contrast, about 40% of GTP gamma S-induced arachidonate release was inhibited by a diacylglycerol lipase inhibitor, RHC 80267 (30 microM). These observations indicate that liberation of arachidonic acid is mediated by phospholipase A2 and also by phospholipase C/diacylglycerol lipase pathways. Fluoride, which bypasses the receptor and directly activates G proteins, induced arachidonic acid release and diacylglycerol formation. The fluoride-induced arachidonate release also appeared to be mediated by these two pathways. The loss of [3H]arachidonate was seen in phosphatidylinositol, phosphatidylcholine, and phosphatidylethanolamine. These data indicate that a G protein is involved between the binding of fMLP to its receptor and activation of phospholipase A2, and also that the arachidonic acid release is mediated by both phospholipase A2 and phospholipase C/diacylglycerol lipase.

Animals↗
PubMed1988

Alexia with agraphia due to the left posterior inferior temporal lobe lesion--neuropsychological analysis and its pathogenetic mechanisms.

We report three cases of alexia with agraphia due to the left posterior inferior temporal lesions. In Case 1, the reading disability was more prominent in the use of Kana than in the use of Kanji, which is similar to previously reported cases of alexia with agraphia due to angular gyrus lesion. In Cases 2 and 3, by contrast, the reading disability was more prominent in the use of Kanji than in the use of Kana. In spontaneous writing and dictation, the disability was more pronounced in the use of Kanji compared with the use of Kana. In each of the three cases, the CT scan and positron emission tomography showed a localized lesion in the lower part of the left posterior temporal lobe. A typical form of an alexia with agraphia could be caused not only by the left angular lesion but also by the left posterior inferior temporal lesion. We discuss the neuropsychological analysis and pathogenetic mechanisms of alexia with agraphia due to the left posterior inferior temporal lesion in the comparison of alexia with agraphia caused by the left angular lesion.

Aged↗
PubMed1988

Effects of recombinant G-CSF and GM-CSF on the growth in methylcellulose and suspension of the blast cells in acute myeloblastic leukemia.

The effects of two recombinant human CSFs (G-CSF and GM-CSF) on the growth of blast progenitors from 36 acute myeloblastic leukemia patients were studied in methylcellulose and suspension cultures. Blast colony formation in methylcellulose and the growth of blast progenitors in suspension were stimulated by G-CSF or GM-CSF. Their responses to CSFs were different from those of normal myeloid progenitors. First, the sensitivity of blasts to 0.01 ng/ml of G-CSF and 0.001 ng/ml of GM-CSF was significantly increased compared with normal. Second, in more than 70% of patients, the pattern of the responsiveness to the two CSFs was aberrant compared with ordered response in normal subjects. Third, in about half of the patients, combination of G-CSF and GM-CSF showed synergism for the growth of blast progenitors in both culture methods, whereas negligible or no synergism was observed in normal subjects. Finally, when stimulated by G-CSF, GM-CSF, or both, a significant relationship was noted between blast colony formation in methylcellulose and blast progenitor growth in suspension, suggesting that CSFs do not affect the balance between self-renewal and terminal divisions of blast stem cells.

Adult↗