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T Joh

Publications and source records attributed to T Joh.

At least 91 records · Page 5Linked to original sources
PubMed1996

Identification of MLL and chimeric MLL gene products involved in 11q23 translocation and possible mechanisms of leukemogenesis by MLL truncation.

11q23 chromosome aberrations are frequently observed in infantile as well as therapy-related leukemias. The target gene at 11q23, MLL, is disrupted by the translocation and becomes fused to various translocation partner genes such as AF4/FEL, LTG9/AF9 and LTG19/ENL. The resulting chimeric mRNAs are fused in frame and have been predicted to encode leukemia-specific chimeric proteins. In the present study, we raised antibodies against MLL, LTG9 and LTG19 and demonstrated that MLL and chimeric MLL-LTG9 and MLL-LTG19 products are synthesized in vivo and are localized in the nuclei, using immunofluorescence and cell fractionation studies. The truncated N-terminal portion of the MLL product common to the various types of 11q23 translocation was also localized in the nuclei in a similar fashion. Murine 32Dc13 cells stably expressing the truncated N-terminal MLL protein exhibited an inhibition of differentiation and a growth advantage following stimulation by granulocyte-colony stimulating factor, although the IL-3 dependency was not significantly changed in comparison to the parental cells. These results suggest that the N-terminal portion common to various MLL-chimeric products plays an important role in leukemogenesis.

Amino Acid Sequence↗
PubMed1996

Complement plays an essential role in shock following intestinal ischaemia in rats.

Intestinal ischaemia lasting more than 30 min in rats causes fatal systemic shock. Systemic shock was suppressed by preadministration of cobra venom factor (CVF), which reduced the serum complement to less than 5% of the normal level, indicating that complement is involved in the syndrome. After complement activation, anaphylatoxins such as C3a and C5a are generated, and their activity is restricted by carboxypeptidases which remove C-terminal arginine from such bioactive peptides. As expected, preadministration of a carboxypeptidase inhibitor enhanced the systemic shock induced by the intestinal ischaemia. However, when the complement level was suppressed by CVF treatment, no fatal systemic shock was induced by the intestinal ischaemia even with preadministration of the carboxypeptidase inhibitor. These results indicate that complement plays a crucial role in systemic shock induced by intestinal ischaemia, and that anaphylatoxins generated by the complement activation should be involved in induction of the shock syndrome.

3-Mercaptopropionic Acid↗
PubMed1996

A catalogue of genes in mouse embryonal carcinoma F9 cells identified with expressed sequence tags.

We used expressed sequence tags (ESTs) to identify genes expressed in mouse embryonal carcinoma F9 cells and prepared 2132 ESTs from undifferentiated F9 cDNA libraries: 1026 were prepared after randomly selecting clones from one of the libraries and the remaining 1106 ESTs were prepared after classifying 2896 clones of the libraries into four classes, according to the levels and patterns of expression. Among the former 1026 ESTs, 797 (78%) matched known genes, 61 (6%) matched database sequences of uncharacterized cDNAs, and 168 (16%) represented novel genes. The ESTs matching known genes were catalogued according to putative structural and cellular functions. As many as 53% were related to transcription and translation, and 19% were related to energy metabolism, including transcripts of mitochondrial DNA. These percentages were significantly higher in F9 cells than in the human heart and brain, and a human liver cell line, HepG2. We found that approximately 7% of the ESTs corresponding to low-abundance mRNAs are either related to retinoic acid-regulated genes or mammalian development- and/or differentiation-related genes. Cataloguing of the genes expressed in the F9 cells paves the way for isolating genes involved in early mammalian development.

Adult↗
PubMed1996

Genomic structures and characterization of Rae1 family members encoding GPI-anchored cell surface proteins and expressed predominantly in embryonic mouse brain.

Rae1 alpha, Rae1 beta, and Rae1 gamma cDNAs isolated from retinoic acid-treated mouse embryonal carcinoma F9 cells encode cell surface proteins sharing partial homology with MHC class I molecules, and mRNAs corresponding to these cDNAs were detected exclusively in early mouse embryos, especially in the head region. To initiate studies on their roles, the rae1 alpha gene and the genomic DNAs covering the complete coding regions of the rae1 beta and rae1 gamma genes were isolated and their structures were analyzed. Although the coding regions of the three rae1 genes were highly homologous, the restriction map of the 5'-end region of the rae1 alpha gene differed from that of the rae1 beta and rae1 gamma genes. The rae1 family members were mapped by FISH on mouse chromosome 10A4 region. Genomic DNAs hybridizable with a Rae1 cDNA were not detected in rat and human. Rae1 genes were preferentially expressed in early mouse embryos, preferentially in the brain, and RAE1 proteins were anchored on the cell surface by a glycosyl phosphatidylinositol (GPI)-tail, a feature shared by important cell surface ligands.

Animals↗
PubMed1996

Effects of the anti-gastric secretory drugs IT-066 and omeprazole mitogenic activities in the gastric juice of the rat.

BACKGROUND: Salivary epidermal growth factor (EGF) retains its biologic function in gastric juice and may play a physiologic role. Little is know, however, about the existence of mitogens other than EGF and the constitutional alterations of these factors in gastric juice by anti-secretagogues. METHODS: The mitogenic activity was evaluated by measuring [3H]-thymidine incorporation, and the EGF contribution was determined by using a specific anti-rat EGF antibody. An H2-receptor antagonist (IT-066) and a proton pump inhibitor (omeprazole) were used to determine whether these drugs alter the relative composition of active mitogens in gastric juice. RESULTS: Normal gastric juice significantly increased DNA synthesis. This activity was suppressed by antibody (87-88%). Both drugs increased EGF concentrations and activity dose-dependently IT-066 specifically increased total amount and activity of EGF. Approximately 50% of this activity was reduced by boiling or antibody. CONCLUSION: The major mitogenic activity of normal rat gastric juice depends on EGF, and antisecretory drugs enhance the mitogenic activity by preserving and including intraluminal mitogens than EGF.

Animals↗
PubMed1996

[Evaluation of myocardial damage using 123I-BMIPP imaging in patients with vasospastic angina].

The purpose of this study is to determine whether left ventricular dysfunction following coronary artery spasm by 123I-BMIPP myocardial imaging. To reveal the clinical efficacy of 123I-BMIPP SPECT, 20 patients with vasospastic angina were studied using resting, 3-hour delayed image with 123I-BMIPP and exercise, 3-hour delayed image with 201Tl SPECT. 123I-BMIPP uptake was decreased compared to 201Tl (discordant) in 12 patients (60%) and in 49/100 myocardial segments (49%). The extent and severity score in resting image with 123I-BMIPP were significantly larger than that in delayed image with 201Tl (p < 0.01). In 123I-BMIPP SPECT, the severity score in the latest ischemia were significantly larger than that in others. The incidence of a complete agreement of decreased 123I-BMIPP uptake and coronary artery spasm was significantly higher (75%) than that in 201Tl (28%, p < 0.01). Furthermore, compared to 201Tl uptake, decreased 123I-BMIPP uptake much more corresponded to reduced wall motion in 9 of patients with mismatching. The severity of regional wall motion abnormality was significantly correlated with severity score of 123I-BMIPP. Late redistribution in delayed image with 123I-BMIPP was seen in 6 patients. The regional washout rate and the severity of regional wall motion abnormality in 6 patients was significantly lower than that in others (p < 0.05). Thus, metabolic abnormality assessed by 123I-BMIPP is well associated with left ventricular asynergy and spastic region in patients with vasospastic angina. In conclusion, 123I-BMIPP SPECT may sensitively delineate the impaired myocardium following coronary artery spasm, and it is very useful in diagnosing and estimating the severity of vasospastic angina.

Adult↗
PubMed1995

Effects of dibutyryl guanosine 3',5'-cyclic monophosphate and sodium nitroprusside in pepsinogen secretion from guinea pig chief cells with respect to intracellular Ca2+.

Both Ca2+ and adenosine 3',5'-cyclic monophosphate act as intracellular second messengers in pepsinogen secretion from chief cells. However, the role of intracellular guanosine 3',5'-cyclic monophosphate (cGMP) in this process has not been defined. Although dibutyryl cGMP (dbcGMP), a membrane-permeable derivative of cGMP, has been shown to inhibit pepsinogen secretion only stimulated by cholecystokinin (CCK), the intracellular mechanism of this effect remains unclear. We evaluated the role of intracellular cGMP in pepsinogen secretion from monolayer cultured guinea pig chief cells using dbcGMP and sodium nitroprusside, both of which increase intracellular cGMP. Dibutyryl cGMP and sodium nitroprusside have now been shown to inhibit pepsinogen secretion induced by not only CCK octapeptide but also carbamylcholine chloride and ionomycin in a dose-dependent manner. Furthermore, dbcGMP reduced the increase in intracellular free Ca2+ concentration induced by carbamylcholine chloride, CCK octapeptide, and ionomycin. These results suggest that intracellular cGMP may inhibit pepsinogen secretion by reducing the intracellular free Ca2+ concentration.

Animals↗
PubMed1995

Mediation of pepsinogen secretion from guinea pig chief cells by Ca2+/calmodulin-dependent protein kinase II.

In the presence of Ca2+ bound to calmodulin, Ca2+/calmodulin-dependent protein kinase II (CaMK II) exhibits an intramolecular autophosphorylation and modulates many cell functions. In this study, the role of CaMK II in pepsinogen secretion was investigated in cultured guinea pig chief cells by using a specific CaMK II inhibitor, 1-[N,O-Bis(5-isoquinolinesulfonyl)-N-methyl-L-tyrosyl]-4-phenylpipera zin e (KN-62), and an antibody for the Thr-286-autophosphorylated alpha subunit of CaMK II which specifically recognized the autophosphorylated form of CaMK II. KN-62 inhibited the pepsinogen secretion stimulated by carbamylcholine chloride, cholecystokinin octapeptide, and ionomycin in a dose-dependent manner without affecting intracellular Ca2+ concentrations, but had no effect on the secretion by 12-O-tetradecanoyl phorbol-13-acetate (TPA) and forskolin. Heavy staining with the antibody for autophosphorylated CaMK II was observed in the cytoplasm of chief cells treated with carbamylcholine chloride or ionomycin, but only light staining was seen in cells treated with TPA or forskolin. Thus, CaMK II and its autophosphorylation may be a critical step in the intracellular pathway in which Ca2+ causes pepsinogen secretion from guinea pig chief cells.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1995

Preparation of a murine cell line which stably expresses human T lymphotropic virus type I (HTLV-I) env genome products.

We prepared the murine myeloma cell line NS-1, which stably expressed the human T lymphotropic virus type I (HTLV-I) env gene. The plasmid BCMGEnv was constructed from the episomal vector BCMGSNeo, which was primarily derived from bovine papilloma virus. Transfected env expression was detected by Northern blotting, as well as by flow cytometry using envelope protein-specific monoclonal antibodies (mAb). Expression was detectable for at least seven months. The env transfectants induced syncytium formation which is characteristic of HTLV-I-infected cells, in the human uterine cervical cancer line, HeLa, and the rat cell line, XC. The requirement of envelope proteins for syncytium formation was confirmed by an inhibition assay with envelope protein-specific mAb. Therefore, env transfectants are not only stable, but also have its specific biological function. This system may be useful to analyze the initial steps of viral attachment to the cell surface and to search for the HTLV-I receptor.

Animals↗
PubMed1995

Epidermal growth factor enhances repair of rat intestinal mucosa damaged by oral administration of methotrexate.

To examine the trophic effect of epidermal growth factor on the rat small intestine, we measured diamine oxidase and ornithine decarboxylase activities in intestinal mucosa injured by methotrexate. Methotrexate was infused orally via a gastric tube at a dose of 10 mg/kg per day on 3 successive days (days 1-3). Epidermal growth factor was injected intraperitoneally at a dose of 40 micrograms/kg per day on 4 successive days following methotrexate infusion (days 4-7). Methotrexate caused a marked decrease in diamine oxidase activity; this decrease returned to a normal level on day 13 in controls. In rats injected with epidermal growth factor, diamine oxidase activity began to recover earlier than in the controls, and returned to a normal level on day 11. Epidermal growth factor enhanced the increase of ornithine decarboxylase activity in mucosa injured by methotrexate. When the increase of ornithine decarboxylase activity was suppressed by alpha-difluoromethylornithine, epidermal growth factor failed to facilitate the repair of intestinal mucosa. These results indicate that epidermal growth factor enhances intestinal repair following methotrexate infusion, and that this effect is mediated, at least in part, by ornithine decarboxylase. It is proposed that epidermal growth factor can be used clinically as a means to enhance mucosal repair of the intestine after chemotherapy with methotrexate.

Administration, Oral↗
PubMed1995

Nicotine stimulates pepsinogen secretion from guinea pig gastric chief cells in monolayer culture.

We evaluated the effects of nicotine on pepsinogen secretion in vitro, using a monolayer culture system of guinea pig gastric chief cells. Pepsinogen secretion was increased by above 5 mM nicotine in a dose-dependent manner, as was the elevation of intracellular free calcium concentration ([Ca2+]i). The pepsinogen secretion stimulated by 10 mM nicotine was inhibited by above 1 mM d-tubocurarine, a nicotinic receptor antagonist, but not by same concentrations of scopolamine hydrobromide monohydrate or pirenzepine, a muscarinic receptor antagonist. The elevation of [Ca2+]i induced by 5 mM nicotine was also reduced by 10 mM d-tubocurarine, but not by 10 mM pirenzepine. A calmodulin inhibitor, N-(6-aminohexyl)-5-chloro-1-naphthalene-sulfonamide (W-7), at the concentration of 10(-6) M and a myosin light-chain kinase inhibitor, 1-(5-chloronaphthalene-1-sulfonyl)-1H-hexahydro-1,4-diazepine (ML-9), at concentrations above 10(-7) M also significantly blocked 10 mM nicotine-induced pepsinogen secretion. These finding indicate that nicotine directly stimulates pepsinogen secretion probably via nicotinic receptors on the gastric chief cells, and that the Ca(2+)-mediated messenger system, including calmodulin and myosin light-chain kinase, is involved in this event.

Animals↗
PubMed1995

The role of signal transduction systems in mediating cell density dependent changes in tyrosine hydroxylase gene expression.

Cell density has been implicated in the regulation of neuronal gene phenotype. This study tested the interaction of signal transduction pathways and the expression of tyrosine hydroxylase (TH) mRNA with varying cell density. Increasing cell density in a parental, wild type PC12 cell line elevated steady state levels of TH mRNA. Three observations suggested that this induction is not related to the cyclic AMP dependent signalling pathway: (1) Forskolin stimulated the level of TH mRNA similarly at multiple densities. (2) PKA deficient mutant PC12 cell lines that have either one third (A123.7, AB11) or 3% (A126-1B2) of normal basal expression of TH mRNA still exhibit the same density induced elevation of TH mRNA levels as the wild type. (3) Different cell densities did not change cyclic AMP concentrations in the basal or in the receptor stimulated state. Increasing cell density did not change basal levels of inositol triphosphate (IP3) levels, which suggests that the phosphatidylinositol cascade (PI) is not responsible for density dependent changes in TH expression. Increasing confluence was highly correlated to [Ca2+]i in control (r = 0.70; P < 0.0001), A123.7 (r = 0.92; P < 0.001), AB11 (r = 0.72; P < 0.0001) and A126 (r = 0.42; P < 0.07). Taken together, the results show that neither cyclic AMP nor the PI cascade is involved in cell density induced changes in TH mRNA and suggest that altered [Ca2+]i may have a role.

Animals↗
PubMed1995

Role of mucus in gastric mucosal injury induced by local ischemia/reperfusion.

The role of gastric mucus was evaluated in a rat model of gastric epithelial damage induced by local ischemia/reperfusion (I/R) stress. In this model, blood-to-lumen chromium 51-labeled ethylenediaminetetraacetic acid (51Cr-EDTA) clearance served as an index of injury. Tetraprenyl acetone (TPA; 100 mg, 200 mg/kg IP) was used to stimulate mucus production. Administration of TPA increased both the hexosamine content in gastric tissue and the amount of alcian blue-periodic acid Schiff (AB-PAS) stained mucus in the mucosa in a dose-dependent manner. Increases in 51Cr-EDTA clearance induced by I/R were significantly attenuated by TPA in a dose-dependent manner. N-acetyl-L-cysteine (NAC; 0.6%, 0.8%) was perfused into the gastric lumen to assess the effect of reduction in mucus on the injury induced by I/R. Although mean values of hexosamine content were increased by perfusion with NAC, AB-PAS-stained mucus in the mucosa was significantly decreased in a dose-dependent manner. Perfusion of NAC did not change basal 51Cr-EDTA clearance but significantly exacerbated the increase in clearance induced by I/R in a dose-dependent manner. These results indicate that gastric mucus protects the gastric mucosa against I/R stress in vivo.

Acetylcysteine↗
PubMed1995

Molecular cloning and expression of hardening-induced genes in Chlorella vulgaris C-27: the most abundant clone encodes a late embryogenesis abundant protein.

To investigate the effects of hardening on gene expression in Chlorella vulgaris Beijerink IAM C-27 (formerly Chlorella ellipsoidea Gerneck IAM C-27), a frost-hardy strain, 17 cDNA clones corresponding to hardening-induced Chlorella (hiC) genes were isolated by differential screening of a cDNA library from 6-h hardened cells. Northern blot analysis of transcripts of hiC genes showed that these genes are specifically induced by hardening and that their patterns of induction vary. Southern blots of genomic DNAs from two strains (Chlorella ellipsoidea Gerneck IAM C-102, chilling-sensitive; and C. vulgaris C-27, frost-hardy) of Chlorella indicated that ten hiC clones out of 17 hybridized only with DNA of strain C-27 and the other seven clones hybridized with DNA of both strains. However, of these seven clones, transcripts corresponding to six clones did not accumulate in strain C-102 at low temperatures. The sequence of a deduced protein encoded by the most abundant clone, hiC6, exhibited homology to sequences of Group III LEA (late embryogenesis abundant) proteins and had an amino-terminal amino acid sequence that was similar to the sequences of chloroplast transit peptides.

Acclimatization↗
PubMed1995

Isolation and characterization of hardening-induced proteins in Chlorella vulgaris C-27: identification of late embryogenesis abundant proteins.

Hardening-induced soluble proteins of Chlorella vulgaris Beijerink IAM C-27 (formerly Chlorella ellipsoidea Gerneck IAM C-27) were isolated and purified by two-dimensional high-performance liquid chromatography (2D-HPLC) on an anion-exchange column, with subsequent reversed-phase chromatography. Some of the proteins were resolved by SDS-PAGE, characterized by amino-terminal sequencing and identified by searching for homologies in databases. Separation of the soluble proteins during the hardening of Chlorella by a combination of 2D-HPLC and SDS-PAGE revealed that at least 31 proteins were induced or increased in abundance. Of particular interest was the induction after 12 h of a 10-kDa protein with the amino-terminal amino acid sequence AGNKPITEQISDAVGAAGQKVG and the induction after 6 h of a 14-kDa protein with the amino-terminal sequence ALGEESLGDKAKNAFEDAKDAVKDAAGNVKEAV. The amino-terminal sequences of these proteins indicated that they were homologous to late embryogenesis abundant (LEA) proteins. Furthermore, the level of a 22-kDa protein also increased after 12 h. The amino-terminal sequence of this protein, AAPLVGGPAPDFTAAAVFD, indicated that it was homologous to thioredoxin peroxidase.

Amino Acid Sequence↗
PubMed1995

Role of endogenous acid in gastric mucosal injury induced by local ischemia-reperfusion in the rat.

The role of endogenous acid was evaluated in a rat model of gastric epithelial damage induced by local ischemia-reperfusion (IR). Because no gross lesion was induced in this model, the damage was quantified by measuring the blood-to-lumen [51Cr]EDTA clearance. A proton pump inhibitor (omeprazole) or an H2-receptor antagonist (T-593) was used to suppress luminal acidity from pH 5 to pH 6.3-7.0. Both drugs significantly attenuated the increase in clearance induced by IR, indicating an important role for endogenous acid. A second series of experiments was performed to confirm whether the change in pH from around 5 to 7 was sufficient to reduce IR-induced gastric mucosal damage. Phosphate-buffered saline was perfused into the gastric lumen to neutralize the endogenous luminal acid. Although the luminal acid was completely neutralized, no reduction in clearance was observed. These data indicate that endogenous luminal acid does not play an important role in gastric injury induced by local IR stress and that a proton pump inhibitor or H2-receptor antagonist may suppress IR injury by a mechanism other than reducing luminal acidity, i.e., reducing consumption of ATP needed for acid secretion, thereby improving gastric mucosal energy metabolism.

Animals↗
PubMed1994

Effects of long-term treatment with sustained-release nicardipine on left ventricular hypertrophy and function in patients with essential hypertension.

The effects of long-term treatment with sustained-release nicardipine (nicardipine SR) on left ventricular hypertrophy and function were studied. Ten uncomplicated essential hypertensive patients with left ventricular hypertrophy, aged 61 +/- 7.6 years old, were treated with nicardipine SR alone for an average of 20 months (range: 12-26 months). All patients underwent echocardiography for assessment of left ventricular diameters and function before and after the treatment. At the end of the treatment, systolic and diastolic blood pressures significantly decreased from 176.0 +/- 13.9 to 140.0 +/- 14.3 mm Hg and from 97.0 +/- 5.3 to 77.4 +/- 7.2 mm Hg, respectively (each P < 0.01), while heart rate did not change (73.8 +/- 14.6 vs. 69.9 +/- 13.5 beats/min). The left ventricular mass index significantly decreased from 132.1 +/- 14.4 to 114.4 +/- 15.7 g/m2 (P < 0.01) due to significant reductions in both interventricular septal thickness (P < 0.01) and left ventricular posterior wall thickness (P < 0.05). The ejection fraction (EF), fractional shortening (FS), peak shortening rate (PSR), and peak lengthening rate (PLR) were also improved significantly by the treatment (EF and FS, P < 0.05; PSR and PLR, P < 0.01). Significant inverse relationships existed between end-systolic wall stress and peak shortening or lengthening rate before the treatment (r = 0.80, P < 0.05; r = 0.86, P < 0.05, respectively). These relationships were unchanged after the treatment. Nicardipine SR reduced left ventricular hypertrophy and improved both left ventricular systolic and diastolic functions without causing any consistent augmentation of intrinsic left ventricular function in essential hypertensive patients with left ventricular hypertrophy.

Aged↗