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T Ikuta

Publications and source records attributed to T Ikuta.

At least 55 records · Page 3Linked to original sources
PubMed1995

Cholesterol sulfate, a second messenger for the eta isoform of protein kinase C, inhibits promotional phase in mouse skin carcinogenesis.

Cholesterol sulfate is a second messenger for the eta isoform of protein kinase C mediating squamous differentiation. We found that cholesterol sulfate inhibited the promotional phase of skin carcinogenesis in female CD-1 mice, which was initiated by 100 micrograms 7,12-dimethylbenz[a]-anthracene and promoted by a single application of 10 micrograms 12-O-tetradecanoylphorbol-13-acetate, followed by repeated applications of 10 micrograms mezerein once a week for 19 weeks. Cholesterol sulfate, when applied topically at a dose of 400 micrograms (820 mumol) 10 min before treatment with the promoters, markedly suppressed tumor formation, resulting in decrease of 56% in the incidence of tumor-bearing mice, 81% in the number of tumors/mouse, and 60% in the size of tumors at 20 weeks of the promotion. This inhibition was not due to elimination of the initiated cells. Treatment with the parental cholesterol at a dose of 320 micrograms (820 mumol), which does not activate the eta isoform, did not inhibit tumor promotion. Repeated treatment with cholesterol sulfate induced scaling of skin at the site of application. Cholesterol sulfate, unlike most inhibitors of tumor promotion, did not inhibit induction of ornithine decarboxylase and hyperplasia in mouse epidermis caused by topical treatment with 12-O-tetradecanoylphorbol-13-acetate. These findings suggest that cholesterol sulfate inhibits tumor promotion by stimulating a differentiation pathway mediated by the eta isoform of protein kinase C.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1995

UCN-01, an anti-tumor drug, is a selective inhibitor of the conventional PKC subfamily.

A selective PKC inhibitor, UCN-01, was shown to exhibit anti-tumor activity in vitro and in vivo. We investigated UCN-01 with respect to isozyme-specific PKC inhibition using purified recombinant or rabbit brain PKC isozymes, cPKC alpha, beta and gamma, nPKC delta, epsilon and eta, and a PKC zeta. Of the PKC isozymes examined, cPKC alpha was inhibited by UCN-01 most effectively (Ki = 0.44 nM), suggesting cPKC alpha is the prime candidate for the physiological target of UCN-01. The Ki values of UCN-01 estimated from Dixon plots for cPKC isozymes are approximately 1 nM, whereas the Ki values for nPKC isozymes are about 20 nM. Moreover, the Ki value for aPKC zeta is 3.8 microM. Thus, UCN-01 discriminates between PKC subfamilies. In addition, the inhibitory effects of staurosporine, H7, and calphostin C on aPKC zeta were examined and compared with those for cPKC alpha.

Alkaloids↗
PubMed1995

Growth enhancement of normal human keratinocytes by the antisense oligonucleotide of retinoblastoma susceptibility gene.

We have found that the growth of normal human keratinocytes, grown in serum-free medium, was significantly stimulated by the antisense oligonucleotide of retinoblastoma susceptibility gene (Rb). Normal human keratinocytes were exposed to phosphorothionate oligonucleotides which were complementary to translation initiation codon of Rb gene. The growth of keratinocytes was enhanced by the antisense, but not the sense, oligonucleotide of Rb gene in a dose-dependent manner from 1 to 10 microM. The Rb antisense oligonucleotide, however, did not result in any appreciable change in transcription of the gene when examined by reverse-transcription polymerase chain reaction (RT-PCR) analysis or in the protein expression and the phosphorylation pattern when examined by immunoprecipitation and Western blotting.

Base Sequence↗
PubMed1995

Three year outcome of the residents in a special nursing home.

The 3 year outcome of 48 residents in a special nursing home was investigated, using Hasegawa's dementia rating scale (HDS) and activities of daily living (ADL). For all the residents, HDS score correlates well with age (P < 0.01) and ADP score (P < 0.001). Nineteen residents (40.4%) died during the period surveyed. Two-thirds of the residents with low ADL score died during the period, whereas 70% of the residents with high ADL score are alive. Of these scales, ADL correlated well with the fatal prognosis, suggesting that ADL is a valuable prognostic tool. As for the causes of death, pulmonary disease was prominent (n = 12, 63.2%). Consequently, the prevention of pulmonary disease is needed to achieve a good outcome in the management of nursing home residents.

Activities of Daily Living↗
PubMed1994

Cholesterol sulfate, a novel activator for the eta isoform of protein kinase C.

Activity of protein kinase C depends on the interaction with polar head-groups of two membrane lipids, i.e., phosphatidylserine and diacylglycerol. In the present study, we demonstrated a novel activation mechanism of the eta isoform of protein kinase C (nPKC eta), which is predominantly expressed in epithelial tissues in close association with epithelial differentiation. We found that the nPKC eta was activated by cholesterol sulfate, a metabolite of cholesterol formed during squamous differentiation. This activation was greater than that by phosphatidylserine plus phorbol ester; the Vmax for the activation by cholesterol sulfate was 3.6 times that by phosphatidylserine plus phorbol ester, while Kms were almost equal. In the presence of cholesterol sulfate, phorbol ester only weakly enhanced the activity of nPKC eta. Activation of nPKC eta by cholesterol sulfate was further demonstrated by autophosphorylation of the kinase molecule. However, the alpha and delta isoforms of protein kinase C were not activated by cholesterol sulfate. The present observation affords a new insight into a signal transduction pathway of squamous differentiation.

Amino Acid Sequence↗
PubMed1993

Hyperphosphorylation of keratins by treatment with okadaic acid of BALB/MK-2 mouse keratinocytes.

Protein hyper- or hypophosphorylation induced by okadaic acid (OA) treatment was examined using quiescent cultures of the BALB/MK-2 mouse epidermal keratinocytes. Treatment with OA enhanced the phosphorylation of five proteins with molecular weights of 65,000, 55,000, 50,000, 28,000 and 15,000 (p65, p55, p50, p28, and p15, respectively) and decreased that of two proteins with molecular weights of 22,000 and 20,000 (p22 and p20, respectively). The two major phosphorylated proteins, p65 and p55, were identified as type II and type I keratins, respectively, by immunoblotting and immunoprecipitation with keratin specific antibodies. Serine was the only phosphoamino acid residue in hydrolysates of the 32P-labeled keratins purified from OA-treated cells. Two-dimensional tryptic peptide maps of the phosphorylated keratins showed that the hyperphosphorylation was largely due to phosphorylation at several additional sites in both keratins. The hyperphosphorylation of keratins induced by OA treatment resulted in a drastic change in their solubility. This change closely correlated with reorganization of the keratin filament network, which finally collapsed into large perinuclear aggregates. Concomitantly the cells changed from a typical epithelial shape to a round shape. Of several protein kinase inhibitors tested, only staurosporine interfered with this OA-induced morphological change and reorganization of the keratin network.

Animals↗
PubMed1993

Rapid phosphorylation of 28-kDa heat-shock protein by treatment with okadaic acid and phorbol ester of BALB/MK-2 mouse keratinocytes.

Protein phosphorylation by okadaic acid and 12-O-tetradecanoylphorbol-13-acetate (TPA) was examined using quiescent cultures of BALB/MK-2, a cell line derived from mouse epidermal keratinocytes. Treatment with okadaic acid caused rapid phosphorylation of five proteins with molecular masses of 65, 55, 50, 28 and 15 kDa (p65, p55, p50, p28, p15, respectively) while TPA caused rapid phosphorylation of five proteins with molecular masses of 80, 70, 40, 34 and 28 kDa (p80, p70, p40, p34, p28, respectively). In the present study, we examined p28, a common target protein of okadaic acid and TPA. The phosphorylation of p28 increased depending on time of exposure and doses of okadaic acid and TPA. Combined treatment with okadaic acid and TPA resulted in an additive effect. Its position on two-dimensional gel electrophoresis suggested that p28 is the 28-kDa heat-shock protein (HSP28). This possibility was confirmed by migration of p28 with HSP28 and comparative peptide mapping of the two proteins. The phosphoamino-acid residue of phosphorylated HSP28 was serine. In two-dimensional tryptic peptide maps, the same peptides were phosphorylated after treatment with both okadaic acid and TPA.

Animals↗
PubMed1993

A short-term trial of butyrate to stimulate fetal-globin-gene expression in the beta-globin disorders.

BACKGROUND: Fetal-globin (gamma-globin) chains inhibit the polymerization of hemoglobin S (sickle hemoglobin) and can functionally substitute for the beta-globin chains that are defective or absent in patients with the beta-thalassemias. Identifying safe mechanisms to stimulate fetal-hemoglobin production is therefore of great interest. Previous studies have shown that administering butyrate selectively stimulates the promoter of the human fetal-globin gene and leads to increases in gamma-globin--gene expression in the developing fetus, cultured cells, and animal models. METHODS: To determine whether butyrate can stimulate fetal-globin production in humans, we treated three patients (3 to 13 years old) with sickle cell anemia and three patients (7 to 27 years old) with beta-thalassemia syndromes with a short course of intravenous infusions of arginine butyrate. The drug was infused continuously for either two or three weeks; the initial dose was 500 mg per kilogram of body weight per day. Globin-chain ratios, proportions of reticulocytes producing hemoglobin F (F reticulocytes), and levels of gamma-globin messenger RNA (mRNA) were determined before and during treatment. RESULTS: In all six patients, fetal-globin synthesis increased by 6 to 45 percent above pretreatment levels (P < 0.01). The proportion of F reticulocytes increased about twofold, and the level of gamma-globin mRNA increased twofold to sixfold. The increase in gamma-globin synthesis led to improvement in the globin-chain ratios in the patients with thalassemia. The treatment of one patient was extended for seven weeks, and her hemoglobin level increased from 4.7 to 10.2 g per deciliter (2.9 to 6.3 mmol per liter). Side effects were minimal; one patient had a transient increase in serum aminotransferase concentrations. CONCLUSIONS: In patients with beta-hemoglobinopathies butyrate, a natural fatty acid, can significantly and rapidly increase fetal-globin production to levels that can ameliorate beta-globin disorders. Further trials of this class of compounds are warranted to determine long-term tolerance and efficacy in patients with sickle cell anemia or beta-thalassemia.

Adolescent↗
PubMed1993

Inter-ethnic polymorphism of the beta-globin gene locus control region (LCR) in sickle-cell anemia patients.

Sequence polymorphisms within the 5'HS2 segment of human locus control region is described among sickle cell anemia patients. Distinct polymorphic patterns of a simple sequence repeat are observed in strong linkage disequilibrium with each of the five major beta s haplotypes. Potential functional relevance of this polymorphic region in globin gene expression is discussed.

Algeria↗
PubMed1993

Sexual intercourse as a precipitating factor of transient global amnesia.

A Japanese female case of transient global amnesia (TGA), who developed an amnesic episode after sexual intercourse, is reported. The mechanism of how TGA in the present case is precipitated by sexual intercourse could be explained by the elevated blood pressure during sexual intercourse that drops rapidly, causing a temporal ischemia in the distribution of the basilar artery. Furthermore, the importance of sexual intercourse as a precipitating factor of TGA is stressed.

Adult↗
PubMed1991

In vivo protein-DNA interactions at the beta-globin gene locus.

We have investigated in vivo protein-DNA interactions in the beta-globin gene locus by dimethyl sulfate (DMS) footprinting in K562 cells, which express epsilon- and gamma-globin but not beta-globin. In the locus control region, hypersensitive site 2 (HS-2) exhibited footprints in several putative protein binding motifs. HS-3 was not footprinted. The beta promoter was also not footprinted, while extensive footprints were observed in the promoter of the active gamma-globin gene. No footprints were seen in the A gamma and beta 3' enhancers. With several motifs, additional protein interactions and alterations in binding patterns occurred with hemin induction. In HeLa cells, some footprints were observed in some of the motifs in HS-2, compatible with the finding that HS-2 has some enhancer function in HeLa cells, albeit much weaker than its activity in K562 cells. No footprint was seen in B lymphocytes. In vivo footprinting is a useful method for studying relevant protein-DNA interactions in erythroid cells.

Alkylating Agents↗
PubMed1991

Identification of lamin B2 as a substrate of protein kinase C in BALB/MK-2 mouse keratinocytes.

Protein phosphorylation by activation of protein kinase C was examined using quiescent cultures of the mouse epidermal keratinocyte line BALB/MK-2. Treatment with phorbol ester caused rapid phosphorylation of five proteins with molecular weights of 80,000, 70,000, 40,000, 34,000, 28,000. Of these proteins, the 70,000 molecular weight one (p70) was studied further. Its position on two-dimensional gel suggested that p70 is nuclear envelope lamin B. This possibility was confirmed by the co-migration of p70 with the lamin fraction of mouse liver and its immunoprecipitation with antinuclear lamina antibody. The lamin B fraction consists of lamin B1 and lamin B2. Evidence that p70 is lamin B2 was obtained by peptide mapping and amino acid sequencing. Lamin B2 is the only lamin that shows a substantial increase in phosphorylation on treatment of BALB/MK-2 cells with phorbol ester.

Amino Acid Sequence↗
PubMed1990

Enlargement of the anterior horn of the lateral ventricle in schizophrenic patients: chronological and morphometrical studies.

The anterior horn and lateral ventricular sizes of the brain CT were selected for measurement and comparison between 47 schizophrenic patients and 48 neurotic cases, which constituted the control subjects. The ventricular brain ratio (VBR) and the linear ratio (LR 1-6) in multiple age groups were calculated, analyzed and compared using the Student's t test, the two-way ANOVA and Bonferroni's methods. It was found that the VBR of the anterior horn and modified bicaudate cerebroventricular index of the teenage schizophrenics were significantly greater than those of the teenage controls (p less than 0.01) and the ventricular sizes were not associated with the different stages of age except for the cases of the teenage group. These results support the hypothesis of previous investigators that the ventricular enlargement is present early in the course of schizophrenia and provide additional evidence that in teenage schizophrenic patients there is a tendency of the enlargement of the anterior horn of the lateral ventricle which may be related with a morphological vulnerability in the prefrontal cortex.

Adolescent↗
PubMed1990

Electroencephalographic changes during and after water intoxication.

A case of water intoxication with remarkable hyponatremia was investigated with a special reference to EEG changes during and after the episode. The patient recovered his EEG as his consciousness disturbance had improved through an intravenous infusion of high osmolality saline, correlating with the serum sodium level. Further, the clinical importance of recording EEG for water intoxication was stressed.

Adult↗
PubMed1990

The complex episode of transient global amnesia.

In most reports, Transient Global Amnesia (TGA) consisted of a single episode of total amnesia. The detailed investigation on the process of recovery from amnesia in the present two cases of TGA indicated the existence of a complex episode of TGA which consisted of a sequence of episodes of total amnesia.

Amnesia↗
PubMed1990

Evoked potentials of self-interrupted Jacksonian epilepsy.

We describe a female case of Jacksonian epilepsy who can interrupt the spreading of her march by grasping her fingers firmly with her right hand. Neurophysiologically, Somatosensory evoked potential (SEP) was remarkably decreased in amplitude with pressure stimulation similar to her method. Such a change in SEP was observed also in a healthy subject. Accordingly, it is suggested that the stimulation only to the proprioceptor of fascia suppresses the activity in the cortex.

Aged↗
PubMed1989

Normal mouse lung tissue produces a growth-inhibitory factor(s) preferential for mouse monocytic leukemia cells.

A growth-inhibitory (GI) factor, that specifically inhibits the growth of mouse monocytic leukemia cells, was found in conditioned medium of mouse lung tissue, but not in that of mouse brain, heart, liver, or kidney tissue. Conditioned medium of spleen or bone marrow cells had low GI activity. Pulmonary macrophages were as active as peritoneal and bone-marrow-derived macrophages in production of the GI activity. The GI factor inhibited the growth of murine monocytic leukemia cell lines Mm-A and J774.1, but scarcely inhibited the growth of other mouse cell lines, such as a myeloblastic leukemia cell line (M1), a Friend erythroleukemia cell line (745A) and a mammary carcinoma cell line (FM3A). It had no significant effect on the growth of human monocytic leukemia cell lines U937 and THP-1 or on the HL-60 promyelocytic leukemia cell line. These results suggest that the GI factor produced by mouse lung tissue preferentially inhibits the growth of mouse monocytic cells. The GI factor was found to be a proteinaceous substance with a molecular mass of 25 kDa. On chromatofocusing, the GI activity was eluted with Polybuffer 96/acetic acid at pH 7.2-7.5. The GI activity was not significantly decreased by heat treatment at 56 degrees C for 30 min or acid treatment (0.01 M HCl, 14 h), but the GI activity in glycosidase-treated conditioned medium of lung tissue was lost on heat treatment. The GI activity could not be neutralized with anti-(interferon alpha + beta) antibody. The activity was produced constitutively by lung tissues and its production was not stimulated appreciably by lipopolysaccharide, lectin, or poly(I).poly(C). The GI factor appears to be a cytokine unrelated to known cytokines such as tumor necrosis factor, interleukin-1, transforming growth factor beta, and interferons. These results suggest that the GI factor may be involved in negative feedback regulation of macrophage production in steady-state conditions in the lungs.

Animals↗